gcc/go/gofrontend/expressions.cc

   1 // expressions.cc -- Go frontend expression handling.
   2
   3 // Copyright 2009 The Go Authors. All rights reserved.
   4 // Use of this source code is governed by a BSD-style
   5 // license that can be found in the LICENSE file.
   6
   7 #include "go-system.h"
   8
   9 #include <gmp.h>
  10
  11 #ifndef ENABLE_BUILD_WITH_CXX
  12 extern "C"
  13 {
  14 #endif
  15
  16 #include "toplev.h"
  17 #include "intl.h"
  18 #include "tree.h"
  19 #include "gimple.h"
  20 #include "tree-iterator.h"
  21 #include "convert.h"
  22 #include "real.h"
  23 #include "realmpfr.h"
  24
  25 #ifndef ENABLE_BUILD_WITH_CXX
  26 }
  27 #endif
  28
  29 #include "go-c.h"
  30 #include "gogo.h"
  31 #include "types.h"
  32 #include "export.h"
  33 #include "import.h"
  34 #include "statements.h"
  35 #include "lex.h"
  36 #include "runtime.h"
  37 #include "backend.h"
  38 #include "expressions.h"
  39 #include "ast-dump.h"
  40
  41 // Class Expression.
  42
  43 Expression::Expression(Expression_classification classification,
  44                        Location location)
  45   : classification_(classification), location_(location)
  46 {
  47 }
  48
  49 Expression::~Expression()
  50 {
  51 }
  52
  53 // If this expression has a constant integer value, return it.
  54
  55 bool
  56 Expression::integer_constant_value(bool iota_is_constant, mpz_t val,
  57                                    Type** ptype) const
  58 {
  59   *ptype = NULL;
  60   return this->do_integer_constant_value(iota_is_constant, val, ptype);
  61 }
  62
  63 // If this expression has a constant floating point value, return it.
  64
  65 bool
  66 Expression::float_constant_value(mpfr_t val, Type** ptype) const
  67 {
  68   *ptype = NULL;
  69   if (this->do_float_constant_value(val, ptype))
  70     return true;
  71   mpz_t ival;
  72   mpz_init(ival);
  73   Type* t;
  74   bool ret;
  75   if (!this->do_integer_constant_value(false, ival, &t))
  76     ret = false;
  77   else
  78     {
  79       mpfr_set_z(val, ival, GMP_RNDN);
  80       ret = true;
  81     }
  82   mpz_clear(ival);
  83   return ret;
  84 }
  85
  86 // If this expression has a constant complex value, return it.
  87
  88 bool
  89 Expression::complex_constant_value(mpfr_t real, mpfr_t imag,
  90                                    Type** ptype) const
  91 {
  92   *ptype = NULL;
  93   if (this->do_complex_constant_value(real, imag, ptype))
  94     return true;
  95   Type *t;
  96   if (this->float_constant_value(real, &t))
  97     {
  98       mpfr_set_ui(imag, 0, GMP_RNDN);
  99       return true;
 100     }
 101   return false;
 102 }
 103
 104 // Traverse the expressions.
 105
 106 int
 107 Expression::traverse(Expression** pexpr, Traverse* traverse)
 108 {
 109   Expression* expr = *pexpr;
 110   if ((traverse->traverse_mask() & Traverse::traverse_expressions) != 0)
 111     {
 112       int t = traverse->expression(pexpr);
 113       if (t == TRAVERSE_EXIT)
 114         return TRAVERSE_EXIT;
 115       else if (t == TRAVERSE_SKIP_COMPONENTS)
 116         return TRAVERSE_CONTINUE;
 117     }
 118   return expr->do_traverse(traverse);
 119 }
 120
 121 // Traverse subexpressions of this expression.
 122
 123 int
 124 Expression::traverse_subexpressions(Traverse* traverse)
 125 {
 126   return this->do_traverse(traverse);
 127 }
 128
 129 // Default implementation for do_traverse for child classes.
 130
 131 int
 132 Expression::do_traverse(Traverse*)
 133 {
 134   return TRAVERSE_CONTINUE;
 135 }
 136
 137 // This virtual function is called by the parser if the value of this
 138 // expression is being discarded.  By default, we give an error.
 139 // Expressions with side effects override.
 140
 141 void
 142 Expression::do_discarding_value()
 143 {
 144   this->unused_value_error();
 145 }
 146
 147 // This virtual function is called to export expressions.  This will
 148 // only be used by expressions which may be constant.
 149
 150 void
 151 Expression::do_export(Export*) const
 152 {
 153   go_unreachable();
 154 }
 155
 156 // Give an error saying that the value of the expression is not used.
 157
 158 void
 159 Expression::unused_value_error()
 160 {
 161   error_at(this->location(), "value computed is not used");
 162 }
 163
 164 // Note that this expression is an error.  This is called by children
 165 // when they discover an error.
 166
 167 void
 168 Expression::set_is_error()
 169 {
 170   this->classification_ = EXPRESSION_ERROR;
 171 }
 172
 173 // For children to call to report an error conveniently.
 174
 175 void
 176 Expression::report_error(const char* msg)
 177 {
 178   error_at(this->location_, "%s", msg);
 179   this->set_is_error();
 180 }
 181
 182 // Set types of variables and constants.  This is implemented by the
 183 // child class.
 184
 185 void
 186 Expression::determine_type(const Type_context* context)
 187 {
 188   this->do_determine_type(context);
 189 }
 190
 191 // Set types when there is no context.
 192
 193 void
 194 Expression::determine_type_no_context()
 195 {
 196   Type_context context;
 197   this->do_determine_type(&context);
 198 }
 199
 200 // Return a tree handling any conversions which must be done during
 201 // assignment.
 202
 203 tree
 204 Expression::convert_for_assignment(Translate_context* context, Type* lhs_type,
 205                                    Type* rhs_type, tree rhs_tree,
 206                                    Location location)
 207 {
 208   if (lhs_type == rhs_type)
 209     return rhs_tree;
 210
 211   if (lhs_type->is_error() || rhs_type->is_error())
 212     return error_mark_node;
 213
 214   if (rhs_tree == error_mark_node || TREE_TYPE(rhs_tree) == error_mark_node)
 215     return error_mark_node;
 216
 217   Gogo* gogo = context->gogo();
 218
 219   tree lhs_type_tree = type_to_tree(lhs_type->get_backend(gogo));
 220   if (lhs_type_tree == error_mark_node)
 221     return error_mark_node;
 222
 223   if (lhs_type->interface_type() != NULL)
 224     {
 225       if (rhs_type->interface_type() == NULL)
 226         return Expression::convert_type_to_interface(context, lhs_type,
 227                                                      rhs_type, rhs_tree,
 228                                                      location);
 229       else
 230         return Expression::convert_interface_to_interface(context, lhs_type,
 231                                                           rhs_type, rhs_tree,
 232                                                           false, location);
 233     }
 234   else if (rhs_type->interface_type() != NULL)
 235     return Expression::convert_interface_to_type(context, lhs_type, rhs_type,
 236                                                  rhs_tree, location);
 237   else if (lhs_type->is_slice_type() && rhs_type->is_nil_type())
 238     {
 239       // Assigning nil to an open array.
 240       go_assert(TREE_CODE(lhs_type_tree) == RECORD_TYPE);
 241
 242       VEC(constructor_elt,gc)* init = VEC_alloc(constructor_elt, gc, 3);
 243
 244       constructor_elt* elt = VEC_quick_push(constructor_elt, init, NULL);
 245       tree field = TYPE_FIELDS(lhs_type_tree);
 246       go_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)),
 247                         "__values") == 0);
 248       elt->index = field;
 249       elt->value = fold_convert(TREE_TYPE(field), null_pointer_node);
 250
 251       elt = VEC_quick_push(constructor_elt, init, NULL);
 252       field = DECL_CHAIN(field);
 253       go_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)),
 254                         "__count") == 0);
 255       elt->index = field;
 256       elt->value = fold_convert(TREE_TYPE(field), integer_zero_node);
 257
 258       elt = VEC_quick_push(constructor_elt, init, NULL);
 259       field = DECL_CHAIN(field);
 260       go_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)),
 261                         "__capacity") == 0);
 262       elt->index = field;
 263       elt->value = fold_convert(TREE_TYPE(field), integer_zero_node);
 264
 265       tree val = build_constructor(lhs_type_tree, init);
 266       TREE_CONSTANT(val) = 1;
 267
 268       return val;
 269     }
 270   else if (rhs_type->is_nil_type())
 271     {
 272       // The left hand side should be a pointer type at the tree
 273       // level.
 274       go_assert(POINTER_TYPE_P(lhs_type_tree));
 275       return fold_convert(lhs_type_tree, null_pointer_node);
 276     }
 277   else if (lhs_type_tree == TREE_TYPE(rhs_tree))
 278     {
 279       // No conversion is needed.
 280       return rhs_tree;
 281     }
 282   else if (POINTER_TYPE_P(lhs_type_tree)
 283            || INTEGRAL_TYPE_P(lhs_type_tree)
 284            || SCALAR_FLOAT_TYPE_P(lhs_type_tree)
 285            || COMPLEX_FLOAT_TYPE_P(lhs_type_tree))
 286     return fold_convert_loc(location.gcc_location(), lhs_type_tree, rhs_tree);
 287   else if (TREE_CODE(lhs_type_tree) == RECORD_TYPE
 288            && TREE_CODE(TREE_TYPE(rhs_tree)) == RECORD_TYPE)
 289     {
 290       // This conversion must be permitted by Go, or we wouldn't have
 291       // gotten here.
 292       go_assert(int_size_in_bytes(lhs_type_tree)
 293                  == int_size_in_bytes(TREE_TYPE(rhs_tree)));
 294       return fold_build1_loc(location.gcc_location(), VIEW_CONVERT_EXPR,
 295                              lhs_type_tree, rhs_tree);
 296     }
 297   else
 298     {
 299       go_assert(useless_type_conversion_p(lhs_type_tree, TREE_TYPE(rhs_tree)));
 300       return rhs_tree;
 301     }
 302 }
 303
 304 // Return a tree for a conversion from a non-interface type to an
 305 // interface type.
 306
 307 tree
 308 Expression::convert_type_to_interface(Translate_context* context,
 309                                       Type* lhs_type, Type* rhs_type,
 310                                       tree rhs_tree, Location location)
 311 {
 312   Gogo* gogo = context->gogo();
 313   Interface_type* lhs_interface_type = lhs_type->interface_type();
 314   bool lhs_is_empty = lhs_interface_type->is_empty();
 315
 316   // Since RHS_TYPE is a static type, we can create the interface
 317   // method table at compile time.
 318
 319   // When setting an interface to nil, we just set both fields to
 320   // NULL.
 321   if (rhs_type->is_nil_type())
 322     {
 323       Btype* lhs_btype = lhs_type->get_backend(gogo);
 324       return expr_to_tree(gogo->backend()->zero_expression(lhs_btype));
 325     }
 326
 327   // This should have been checked already.
 328   go_assert(lhs_interface_type->implements_interface(rhs_type, NULL));
 329
 330   tree lhs_type_tree = type_to_tree(lhs_type->get_backend(gogo));
 331   if (lhs_type_tree == error_mark_node)
 332     return error_mark_node;
 333
 334   // An interface is a tuple.  If LHS_TYPE is an empty interface type,
 335   // then the first field is the type descriptor for RHS_TYPE.
 336   // Otherwise it is the interface method table for RHS_TYPE.
 337   tree first_field_value;
 338   if (lhs_is_empty)
 339     first_field_value = rhs_type->type_descriptor_pointer(gogo, location);
 340   else
 341     {
 342       // Build the interface method table for this interface and this
 343       // object type: a list of function pointers for each interface
 344       // method.
 345       Named_type* rhs_named_type = rhs_type->named_type();
 346       bool is_pointer = false;
 347       if (rhs_named_type == NULL)
 348         {
 349           rhs_named_type = rhs_type->deref()->named_type();
 350           is_pointer = true;
 351         }
 352       tree method_table;
 353       if (rhs_named_type == NULL)
 354         method_table = null_pointer_node;
 355       else
 356         method_table =
 357           rhs_named_type->interface_method_table(gogo, lhs_interface_type,
 358                                                  is_pointer);
 359       first_field_value = fold_convert_loc(location.gcc_location(),
 360                                            const_ptr_type_node, method_table);
 361     }
 362   if (first_field_value == error_mark_node)
 363     return error_mark_node;
 364
 365   // Start building a constructor for the value we will return.
 366
 367   VEC(constructor_elt,gc)* init = VEC_alloc(constructor_elt, gc, 2);
 368
 369   constructor_elt* elt = VEC_quick_push(constructor_elt, init, NULL);
 370   tree field = TYPE_FIELDS(lhs_type_tree);
 371   go_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)),
 372                     (lhs_is_empty ? "__type_descriptor" : "__methods")) == 0);
 373   elt->index = field;
 374   elt->value = fold_convert_loc(location.gcc_location(), TREE_TYPE(field),
 375                                 first_field_value);
 376
 377   elt = VEC_quick_push(constructor_elt, init, NULL);
 378   field = DECL_CHAIN(field);
 379   go_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__object") == 0);
 380   elt->index = field;
 381
 382   if (rhs_type->points_to() != NULL)
 383     {
 384       //  We are assigning a pointer to the interface; the interface
 385       // holds the pointer itself.
 386       elt->value = rhs_tree;
 387       return build_constructor(lhs_type_tree, init);
 388     }
 389
 390   // We are assigning a non-pointer value to the interface; the
 391   // interface gets a copy of the value in the heap.
 392
 393   tree object_size = TYPE_SIZE_UNIT(TREE_TYPE(rhs_tree));
 394
 395   tree space = gogo->allocate_memory(rhs_type, object_size, location);
 396   space = fold_convert_loc(location.gcc_location(),
 397                            build_pointer_type(TREE_TYPE(rhs_tree)), space);
 398   space = save_expr(space);
 399
 400   tree ref = build_fold_indirect_ref_loc(location.gcc_location(), space);
 401   TREE_THIS_NOTRAP(ref) = 1;
 402   tree set = fold_build2_loc(location.gcc_location(), MODIFY_EXPR,
 403                              void_type_node, ref, rhs_tree);
 404
 405   elt->value = fold_convert_loc(location.gcc_location(), TREE_TYPE(field),
 406                                 space);
 407
 408   return build2(COMPOUND_EXPR, lhs_type_tree, set,
 409                 build_constructor(lhs_type_tree, init));
 410 }
 411
 412 // Return a tree for the type descriptor of RHS_TREE, which has
 413 // interface type RHS_TYPE.  If RHS_TREE is nil the result will be
 414 // NULL.
 415
 416 tree
 417 Expression::get_interface_type_descriptor(Translate_context*,
 418                                           Type* rhs_type, tree rhs_tree,
 419                                           Location location)
 420 {
 421   tree rhs_type_tree = TREE_TYPE(rhs_tree);
 422   go_assert(TREE_CODE(rhs_type_tree) == RECORD_TYPE);
 423   tree rhs_field = TYPE_FIELDS(rhs_type_tree);
 424   tree v = build3(COMPONENT_REF, TREE_TYPE(rhs_field), rhs_tree, rhs_field,
 425                   NULL_TREE);
 426   if (rhs_type->interface_type()->is_empty())
 427     {
 428       go_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(rhs_field)),
 429                         "__type_descriptor") == 0);
 430       return v;
 431     }
 432
 433   go_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(rhs_field)), "__methods")
 434              == 0);
 435   go_assert(POINTER_TYPE_P(TREE_TYPE(v)));
 436   v = save_expr(v);
 437   tree v1 = build_fold_indirect_ref_loc(location.gcc_location(), v);
 438   go_assert(TREE_CODE(TREE_TYPE(v1)) == RECORD_TYPE);
 439   tree f = TYPE_FIELDS(TREE_TYPE(v1));
 440   go_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(f)), "__type_descriptor")
 441              == 0);
 442   v1 = build3(COMPONENT_REF, TREE_TYPE(f), v1, f, NULL_TREE);
 443
 444   tree eq = fold_build2_loc(location.gcc_location(), EQ_EXPR, boolean_type_node,
 445                             v, fold_convert_loc(location.gcc_location(),
 446                                                 TREE_TYPE(v),
 447                                                 null_pointer_node));
 448   tree n = fold_convert_loc(location.gcc_location(), TREE_TYPE(v1),
 449                             null_pointer_node);
 450   return fold_build3_loc(location.gcc_location(), COND_EXPR, TREE_TYPE(v1),
 451                          eq, n, v1);
 452 }
 453
 454 // Return a tree for the conversion of an interface type to an
 455 // interface type.
 456
 457 tree
 458 Expression::convert_interface_to_interface(Translate_context* context,
 459                                            Type *lhs_type, Type *rhs_type,
 460                                            tree rhs_tree, bool for_type_guard,
 461                                            Location location)
 462 {
 463   Gogo* gogo = context->gogo();
 464   Interface_type* lhs_interface_type = lhs_type->interface_type();
 465   bool lhs_is_empty = lhs_interface_type->is_empty();
 466
 467   tree lhs_type_tree = type_to_tree(lhs_type->get_backend(gogo));
 468   if (lhs_type_tree == error_mark_node)
 469     return error_mark_node;
 470
 471   // In the general case this requires runtime examination of the type
 472   // method table to match it up with the interface methods.
 473
 474   // FIXME: If all of the methods in the right hand side interface
 475   // also appear in the left hand side interface, then we don't need
 476   // to do a runtime check, although we still need to build a new
 477   // method table.
 478
 479   // Get the type descriptor for the right hand side.  This will be
 480   // NULL for a nil interface.
 481
 482   if (!DECL_P(rhs_tree))
 483     rhs_tree = save_expr(rhs_tree);
 484
 485   tree rhs_type_descriptor =
 486     Expression::get_interface_type_descriptor(context, rhs_type, rhs_tree,
 487                                               location);
 488
 489   // The result is going to be a two element constructor.
 490
 491   VEC(constructor_elt,gc)* init = VEC_alloc(constructor_elt, gc, 2);
 492
 493   constructor_elt* elt = VEC_quick_push(constructor_elt, init, NULL);
 494   tree field = TYPE_FIELDS(lhs_type_tree);
 495   elt->index = field;
 496
 497   if (for_type_guard)
 498     {
 499       // A type assertion fails when converting a nil interface.
 500       tree lhs_type_descriptor = lhs_type->type_descriptor_pointer(gogo,
 501                                                                    location);
 502       static tree assert_interface_decl;
 503       tree call = Gogo::call_builtin(&assert_interface_decl,
 504                                      location,
 505                                      "__go_assert_interface",
 506                                      2,
 507                                      ptr_type_node,
 508                                      TREE_TYPE(lhs_type_descriptor),
 509                                      lhs_type_descriptor,
 510                                      TREE_TYPE(rhs_type_descriptor),
 511                                      rhs_type_descriptor);
 512       if (call == error_mark_node)
 513         return error_mark_node;
 514       // This will panic if the interface conversion fails.
 515       TREE_NOTHROW(assert_interface_decl) = 0;
 516       elt->value = fold_convert_loc(location.gcc_location(), TREE_TYPE(field),
 517                                     call);
 518     }
 519   else if (lhs_is_empty)
 520     {
 521       // A convertion to an empty interface always succeeds, and the
 522       // first field is just the type descriptor of the object.
 523       go_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)),
 524                         "__type_descriptor") == 0);
 525       elt->value = fold_convert_loc(location.gcc_location(),
 526                                     TREE_TYPE(field), rhs_type_descriptor);
 527     }
 528   else
 529     {
 530       // A conversion to a non-empty interface may fail, but unlike a
 531       // type assertion converting nil will always succeed.
 532       go_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__methods")
 533                  == 0);
 534       tree lhs_type_descriptor = lhs_type->type_descriptor_pointer(gogo,
 535                                                                    location);
 536       static tree convert_interface_decl;
 537       tree call = Gogo::call_builtin(&convert_interface_decl,
 538                                      location,
 539                                      "__go_convert_interface",
 540                                      2,
 541                                      ptr_type_node,
 542                                      TREE_TYPE(lhs_type_descriptor),
 543                                      lhs_type_descriptor,
 544                                      TREE_TYPE(rhs_type_descriptor),
 545                                      rhs_type_descriptor);
 546       if (call == error_mark_node)
 547         return error_mark_node;
 548       // This will panic if the interface conversion fails.
 549       TREE_NOTHROW(convert_interface_decl) = 0;
 550       elt->value = fold_convert_loc(location.gcc_location(), TREE_TYPE(field),
 551                                     call);
 552     }
 553
 554   // The second field is simply the object pointer.
 555
 556   elt = VEC_quick_push(constructor_elt, init, NULL);
 557   field = DECL_CHAIN(field);
 558   go_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__object") == 0);
 559   elt->index = field;
 560
 561   tree rhs_type_tree = TREE_TYPE(rhs_tree);
 562   go_assert(TREE_CODE(rhs_type_tree) == RECORD_TYPE);
 563   tree rhs_field = DECL_CHAIN(TYPE_FIELDS(rhs_type_tree));
 564   go_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(rhs_field)), "__object") == 0);
 565   elt->value = build3(COMPONENT_REF, TREE_TYPE(rhs_field), rhs_tree, rhs_field,
 566                       NULL_TREE);
 567
 568   return build_constructor(lhs_type_tree, init);
 569 }
 570
 571 // Return a tree for the conversion of an interface type to a
 572 // non-interface type.
 573
 574 tree
 575 Expression::convert_interface_to_type(Translate_context* context,
 576                                       Type *lhs_type, Type* rhs_type,
 577                                       tree rhs_tree, Location location)
 578 {
 579   Gogo* gogo = context->gogo();
 580   tree rhs_type_tree = TREE_TYPE(rhs_tree);
 581
 582   tree lhs_type_tree = type_to_tree(lhs_type->get_backend(gogo));
 583   if (lhs_type_tree == error_mark_node)
 584     return error_mark_node;
 585
 586   // Call a function to check that the type is valid.  The function
 587   // will panic with an appropriate runtime type error if the type is
 588   // not valid.
 589
 590   tree lhs_type_descriptor = lhs_type->type_descriptor_pointer(gogo, location);
 591
 592   if (!DECL_P(rhs_tree))
 593     rhs_tree = save_expr(rhs_tree);
 594
 595   tree rhs_type_descriptor =
 596     Expression::get_interface_type_descriptor(context, rhs_type, rhs_tree,
 597                                               location);
 598
 599   tree rhs_inter_descriptor = rhs_type->type_descriptor_pointer(gogo,
 600                                                                 location);
 601
 602   static tree check_interface_type_decl;
 603   tree call = Gogo::call_builtin(&check_interface_type_decl,
 604                                  location,
 605                                  "__go_check_interface_type",
 606                                  3,
 607                                  void_type_node,
 608                                  TREE_TYPE(lhs_type_descriptor),
 609                                  lhs_type_descriptor,
 610                                  TREE_TYPE(rhs_type_descriptor),
 611                                  rhs_type_descriptor,
 612                                  TREE_TYPE(rhs_inter_descriptor),
 613                                  rhs_inter_descriptor);
 614   if (call == error_mark_node)
 615     return error_mark_node;
 616   // This call will panic if the conversion is invalid.
 617   TREE_NOTHROW(check_interface_type_decl) = 0;
 618
 619   // If the call succeeds, pull out the value.
 620   go_assert(TREE_CODE(rhs_type_tree) == RECORD_TYPE);
 621   tree rhs_field = DECL_CHAIN(TYPE_FIELDS(rhs_type_tree));
 622   go_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(rhs_field)), "__object") == 0);
 623   tree val = build3(COMPONENT_REF, TREE_TYPE(rhs_field), rhs_tree, rhs_field,
 624                     NULL_TREE);
 625
 626   // If the value is a pointer, then it is the value we want.
 627   // Otherwise it points to the value.
 628   if (lhs_type->points_to() == NULL)
 629     {
 630       val = fold_convert_loc(location.gcc_location(),
 631                              build_pointer_type(lhs_type_tree), val);
 632       val = build_fold_indirect_ref_loc(location.gcc_location(), val);
 633     }
 634
 635   return build2(COMPOUND_EXPR, lhs_type_tree, call,
 636                 fold_convert_loc(location.gcc_location(), lhs_type_tree, val));
 637 }
 638
 639 // Convert an expression to a tree.  This is implemented by the child
 640 // class.  Not that it is not in general safe to call this multiple
 641 // times for a single expression, but that we don't catch such errors.
 642
 643 tree
 644 Expression::get_tree(Translate_context* context)
 645 {
 646   // The child may have marked this expression as having an error.
 647   if (this->classification_ == EXPRESSION_ERROR)
 648     return error_mark_node;
 649
 650   return this->do_get_tree(context);
 651 }
 652
 653 // Return a tree for VAL in TYPE.
 654
 655 tree
 656 Expression::integer_constant_tree(mpz_t val, tree type)
 657 {
 658   if (type == error_mark_node)
 659     return error_mark_node;
 660   else if (TREE_CODE(type) == INTEGER_TYPE)
 661     return double_int_to_tree(type,
 662                               mpz_get_double_int(type, val, true));
 663   else if (TREE_CODE(type) == REAL_TYPE)
 664     {
 665       mpfr_t fval;
 666       mpfr_init_set_z(fval, val, GMP_RNDN);
 667       tree ret = Expression::float_constant_tree(fval, type);
 668       mpfr_clear(fval);
 669       return ret;
 670     }
 671   else if (TREE_CODE(type) == COMPLEX_TYPE)
 672     {
 673       mpfr_t fval;
 674       mpfr_init_set_z(fval, val, GMP_RNDN);
 675       tree real = Expression::float_constant_tree(fval, TREE_TYPE(type));
 676       mpfr_clear(fval);
 677       tree imag = build_real_from_int_cst(TREE_TYPE(type),
 678                                           integer_zero_node);
 679       return build_complex(type, real, imag);
 680     }
 681   else
 682     go_unreachable();
 683 }
 684
 685 // Return a tree for VAL in TYPE.
 686
 687 tree
 688 Expression::float_constant_tree(mpfr_t val, tree type)
 689 {
 690   if (type == error_mark_node)
 691     return error_mark_node;
 692   else if (TREE_CODE(type) == INTEGER_TYPE)
 693     {
 694       mpz_t ival;
 695       mpz_init(ival);
 696       mpfr_get_z(ival, val, GMP_RNDN);
 697       tree ret = Expression::integer_constant_tree(ival, type);
 698       mpz_clear(ival);
 699       return ret;
 700     }
 701   else if (TREE_CODE(type) == REAL_TYPE)
 702     {
 703       REAL_VALUE_TYPE r1;
 704       real_from_mpfr(&r1, val, type, GMP_RNDN);
 705       REAL_VALUE_TYPE r2;
 706       real_convert(&r2, TYPE_MODE(type), &r1);
 707       return build_real(type, r2);
 708     }
 709   else if (TREE_CODE(type) == COMPLEX_TYPE)
 710     {
 711       REAL_VALUE_TYPE r1;
 712       real_from_mpfr(&r1, val, TREE_TYPE(type), GMP_RNDN);
 713       REAL_VALUE_TYPE r2;
 714       real_convert(&r2, TYPE_MODE(TREE_TYPE(type)), &r1);
 715       tree imag = build_real_from_int_cst(TREE_TYPE(type),
 716                                           integer_zero_node);
 717       return build_complex(type, build_real(TREE_TYPE(type), r2), imag);
 718     }
 719   else
 720     go_unreachable();
 721 }
 722
 723 // Return a tree for REAL/IMAG in TYPE.
 724
 725 tree
 726 Expression::complex_constant_tree(mpfr_t real, mpfr_t imag, tree type)
 727 {
 728   if (type == error_mark_node)
 729     return error_mark_node;
 730   else if (TREE_CODE(type) == INTEGER_TYPE || TREE_CODE(type) == REAL_TYPE)
 731     return Expression::float_constant_tree(real, type);
 732   else if (TREE_CODE(type) == COMPLEX_TYPE)
 733     {
 734       REAL_VALUE_TYPE r1;
 735       real_from_mpfr(&r1, real, TREE_TYPE(type), GMP_RNDN);
 736       REAL_VALUE_TYPE r2;
 737       real_convert(&r2, TYPE_MODE(TREE_TYPE(type)), &r1);
 738
 739       REAL_VALUE_TYPE r3;
 740       real_from_mpfr(&r3, imag, TREE_TYPE(type), GMP_RNDN);
 741       REAL_VALUE_TYPE r4;
 742       real_convert(&r4, TYPE_MODE(TREE_TYPE(type)), &r3);
 743
 744       return build_complex(type, build_real(TREE_TYPE(type), r2),
 745                            build_real(TREE_TYPE(type), r4));
 746     }
 747   else
 748     go_unreachable();
 749 }
 750
 751 // Return a tree which evaluates to true if VAL, of arbitrary integer
 752 // type, is negative or is more than the maximum value of BOUND_TYPE.
 753 // If SOFAR is not NULL, it is or'red into the result.  The return
 754 // value may be NULL if SOFAR is NULL.
 755
 756 tree
 757 Expression::check_bounds(tree val, tree bound_type, tree sofar,
 758                          Location loc)
 759 {
 760   tree val_type = TREE_TYPE(val);
 761   tree ret = NULL_TREE;
 762
 763   if (!TYPE_UNSIGNED(val_type))
 764     {
 765       ret = fold_build2_loc(loc.gcc_location(), LT_EXPR, boolean_type_node, val,
 766                             build_int_cst(val_type, 0));
 767       if (ret == boolean_false_node)
 768         ret = NULL_TREE;
 769     }
 770
 771   HOST_WIDE_INT val_type_size = int_size_in_bytes(val_type);
 772   HOST_WIDE_INT bound_type_size = int_size_in_bytes(bound_type);
 773   go_assert(val_type_size != -1 && bound_type_size != -1);
 774   if (val_type_size > bound_type_size
 775       || (val_type_size == bound_type_size
 776           && TYPE_UNSIGNED(val_type)
 777           && !TYPE_UNSIGNED(bound_type)))
 778     {
 779       tree max = TYPE_MAX_VALUE(bound_type);
 780       tree big = fold_build2_loc(loc.gcc_location(), GT_EXPR, boolean_type_node,
 781                                  val, fold_convert_loc(loc.gcc_location(),
 782                                                        val_type, max));
 783       if (big == boolean_false_node)
 784         ;
 785       else if (ret == NULL_TREE)
 786         ret = big;
 787       else
 788         ret = fold_build2_loc(loc.gcc_location(), TRUTH_OR_EXPR,
 789                               boolean_type_node, ret, big);
 790     }
 791
 792   if (ret == NULL_TREE)
 793     return sofar;
 794   else if (sofar == NULL_TREE)
 795     return ret;
 796   else
 797     return fold_build2_loc(loc.gcc_location(), TRUTH_OR_EXPR, boolean_type_node,
 798                            sofar, ret);
 799 }
 800
 801 void
 802 Expression::dump_expression(Ast_dump_context* ast_dump_context) const
 803 {
 804   this->do_dump_expression(ast_dump_context);
 805 }
 806
 807 // Error expressions.  This are used to avoid cascading errors.
 808
 809 class Error_expression : public Expression
 810 {
 811  public:
 812   Error_expression(Location location)
 813     : Expression(EXPRESSION_ERROR, location)
 814   { }
 815
 816  protected:
 817   bool
 818   do_is_constant() const
 819   { return true; }
 820
 821   bool
 822   do_integer_constant_value(bool, mpz_t val, Type**) const
 823   {
 824     mpz_set_ui(val, 0);
 825     return true;
 826   }
 827
 828   bool
 829   do_float_constant_value(mpfr_t val, Type**) const
 830   {
 831     mpfr_set_ui(val, 0, GMP_RNDN);
 832     return true;
 833   }
 834
 835   bool
 836   do_complex_constant_value(mpfr_t real, mpfr_t imag, Type**) const
 837   {
 838     mpfr_set_ui(real, 0, GMP_RNDN);
 839     mpfr_set_ui(imag, 0, GMP_RNDN);
 840     return true;
 841   }
 842
 843   void
 844   do_discarding_value()
 845   { }
 846
 847   Type*
 848   do_type()
 849   { return Type::make_error_type(); }
 850
 851   void
 852   do_determine_type(const Type_context*)
 853   { }
 854
 855   Expression*
 856   do_copy()
 857   { return this; }
 858
 859   bool
 860   do_is_addressable() const
 861   { return true; }
 862
 863   tree
 864   do_get_tree(Translate_context*)
 865   { return error_mark_node; }
 866
 867   void
 868   do_dump_expression(Ast_dump_context*) const;
 869 };
 870
 871 // Dump the ast representation for an error expression to a dump context.
 872
 873 void
 874 Error_expression::do_dump_expression(Ast_dump_context* ast_dump_context) const
 875 {
 876   ast_dump_context->ostream() << "_Error_" ;
 877 }
 878
 879 Expression*
 880 Expression::make_error(Location location)
 881 {
 882   return new Error_expression(location);
 883 }
 884
 885 // An expression which is really a type.  This is used during parsing.
 886 // It is an error if these survive after lowering.
 887
 888 class
 889 Type_expression : public Expression
 890 {
 891  public:
 892   Type_expression(Type* type, Location location)
 893     : Expression(EXPRESSION_TYPE, location),
 894       type_(type)
 895   { }
 896
 897  protected:
 898   int
 899   do_traverse(Traverse* traverse)
 900   { return Type::traverse(this->type_, traverse); }
 901
 902   Type*
 903   do_type()
 904   { return this->type_; }
 905
 906   void
 907   do_determine_type(const Type_context*)
 908   { }
 909
 910   void
 911   do_check_types(Gogo*)
 912   { this->report_error(_("invalid use of type")); }
 913
 914   Expression*
 915   do_copy()
 916   { return this; }
 917
 918   tree
 919   do_get_tree(Translate_context*)
 920   { go_unreachable(); }
 921
 922   void do_dump_expression(Ast_dump_context*) const;
 923
 924  private:
 925   // The type which we are representing as an expression.
 926   Type* type_;
 927 };
 928
 929 void
 930 Type_expression::do_dump_expression(Ast_dump_context* ast_dump_context) const
 931 {
 932   ast_dump_context->dump_type(this->type_);
 933 }
 934
 935 Expression*
 936 Expression::make_type(Type* type, Location location)
 937 {
 938   return new Type_expression(type, location);
 939 }
 940
 941 // Class Parser_expression.
 942
 943 Type*
 944 Parser_expression::do_type()
 945 {
 946   // We should never really ask for the type of a Parser_expression.
 947   // However, it can happen, at least when we have an invalid const
 948   // whose initializer refers to the const itself.  In that case we
 949   // may ask for the type when lowering the const itself.
 950   go_assert(saw_errors());
 951   return Type::make_error_type();
 952 }
 953
 954 // Class Var_expression.
 955
 956 // Lower a variable expression.  Here we just make sure that the
 957 // initialization expression of the variable has been lowered.  This
 958 // ensures that we will be able to determine the type of the variable
 959 // if necessary.
 960
 961 Expression*
 962 Var_expression::do_lower(Gogo* gogo, Named_object* function,
 963                          Statement_inserter* inserter, int)
 964 {
 965   if (this->variable_->is_variable())
 966     {
 967       Variable* var = this->variable_->var_value();
 968       // This is either a local variable or a global variable.  A
 969       // reference to a variable which is local to an enclosing
 970       // function will be a reference to a field in a closure.
 971       if (var->is_global())
 972         {
 973           function = NULL;
 974           inserter = NULL;
 975         }
 976       var->lower_init_expression(gogo, function, inserter);
 977     }
 978   return this;
 979 }
 980
 981 // Return the type of a reference to a variable.
 982
 983 Type*
 984 Var_expression::do_type()
 985 {
 986   if (this->variable_->is_variable())
 987     return this->variable_->var_value()->type();
 988   else if (this->variable_->is_result_variable())
 989     return this->variable_->result_var_value()->type();
 990   else
 991     go_unreachable();
 992 }
 993
 994 // Determine the type of a reference to a variable.
 995
 996 void
 997 Var_expression::do_determine_type(const Type_context*)
 998 {
 999   if (this->variable_->is_variable())
1000     this->variable_->var_value()->determine_type();
1001 }
1002
1003 // Something takes the address of this variable.  This means that we
1004 // may want to move the variable onto the heap.
1005
1006 void
1007 Var_expression::do_address_taken(bool escapes)
1008 {
1009   if (!escapes)
1010     {
1011       if (this->variable_->is_variable())
1012         this->variable_->var_value()->set_non_escaping_address_taken();
1013       else if (this->variable_->is_result_variable())
1014         this->variable_->result_var_value()->set_non_escaping_address_taken();
1015       else
1016         go_unreachable();
1017     }
1018   else
1019     {
1020       if (this->variable_->is_variable())
1021         this->variable_->var_value()->set_address_taken();
1022       else if (this->variable_->is_result_variable())
1023         this->variable_->result_var_value()->set_address_taken();
1024       else
1025         go_unreachable();
1026     }
1027 }
1028
1029 // Get the tree for a reference to a variable.
1030
1031 tree
1032 Var_expression::do_get_tree(Translate_context* context)
1033 {
1034   Bvariable* bvar = this->variable_->get_backend_variable(context->gogo(),
1035                                                           context->function());
1036   tree ret = var_to_tree(bvar);
1037   if (ret == error_mark_node)
1038     return error_mark_node;
1039   bool is_in_heap;
1040   if (this->variable_->is_variable())
1041     is_in_heap = this->variable_->var_value()->is_in_heap();
1042   else if (this->variable_->is_result_variable())
1043     is_in_heap = this->variable_->result_var_value()->is_in_heap();
1044   else
1045     go_unreachable();
1046   if (is_in_heap)
1047     {
1048       ret = build_fold_indirect_ref_loc(this->location().gcc_location(), ret);
1049       TREE_THIS_NOTRAP(ret) = 1;
1050     }
1051   return ret;
1052 }
1053
1054 // Ast dump for variable expression.
1055
1056 void
1057 Var_expression::do_dump_expression(Ast_dump_context* ast_dump_context) const
1058 {
1059   ast_dump_context->ostream() << this->variable_->name() ;
1060 }
1061
1062 // Make a reference to a variable in an expression.
1063
1064 Expression*
1065 Expression::make_var_reference(Named_object* var, Location location)
1066 {
1067   if (var->is_sink())
1068     return Expression::make_sink(location);
1069
1070   // FIXME: Creating a new object for each reference to a variable is
1071   // wasteful.
1072   return new Var_expression(var, location);
1073 }
1074
1075 // Class Temporary_reference_expression.
1076
1077 // The type.
1078
1079 Type*
1080 Temporary_reference_expression::do_type()
1081 {
1082   return this->statement_->type();
1083 }
1084
1085 // Called if something takes the address of this temporary variable.
1086 // We never have to move temporary variables to the heap, but we do
1087 // need to know that they must live in the stack rather than in a
1088 // register.
1089
1090 void
1091 Temporary_reference_expression::do_address_taken(bool)
1092 {
1093   this->statement_->set_is_address_taken();
1094 }
1095
1096 // Get a tree referring to the variable.
1097
1098 tree
1099 Temporary_reference_expression::do_get_tree(Translate_context* context)
1100 {
1101   Bvariable* bvar = this->statement_->get_backend_variable(context);
1102
1103   // The gcc backend can't represent the same set of recursive types
1104   // that the Go frontend can.  In some cases this means that a
1105   // temporary variable won't have the right backend type.  Correct
1106   // that here by adding a type cast.  We need to use base() to push
1107   // the circularity down one level.
1108   tree ret = var_to_tree(bvar);
1109   if (!this->is_lvalue_
1110       && POINTER_TYPE_P(TREE_TYPE(ret))
1111       && VOID_TYPE_P(TREE_TYPE(TREE_TYPE(ret))))
1112     {
1113       Btype* type_btype = this->type()->base()->get_backend(context->gogo());
1114       tree type_tree = type_to_tree(type_btype);
1115       ret = fold_convert_loc(this->location().gcc_location(), type_tree, ret);
1116     }
1117   return ret;
1118 }
1119
1120 // Ast dump for temporary reference.
1121
1122 void
1123 Temporary_reference_expression::do_dump_expression(
1124                                 Ast_dump_context* ast_dump_context) const
1125 {
1126   ast_dump_context->dump_temp_variable_name(this->statement_);
1127 }
1128
1129 // Make a reference to a temporary variable.
1130
1131 Temporary_reference_expression*
1132 Expression::make_temporary_reference(Temporary_statement* statement,
1133                                      Location location)
1134 {
1135   return new Temporary_reference_expression(statement, location);
1136 }
1137
1138 // Class Set_and_use_temporary_expression.
1139
1140 // Return the type.
1141
1142 Type*
1143 Set_and_use_temporary_expression::do_type()
1144 {
1145   return this->statement_->type();
1146 }
1147
1148 // Take the address.
1149
1150 void
1151 Set_and_use_temporary_expression::do_address_taken(bool)
1152 {
1153   this->statement_->set_is_address_taken();
1154 }
1155
1156 // Return the backend representation.
1157
1158 tree
1159 Set_and_use_temporary_expression::do_get_tree(Translate_context* context)
1160 {
1161   Bvariable* bvar = this->statement_->get_backend_variable(context);
1162   tree var_tree = var_to_tree(bvar);
1163   tree expr_tree = this->expr_->get_tree(context);
1164   if (var_tree == error_mark_node || expr_tree == error_mark_node)
1165     return error_mark_node;
1166   Location loc = this->location();
1167   return build2_loc(loc.gcc_location(), COMPOUND_EXPR, TREE_TYPE(var_tree),
1168                     build2_loc(loc.gcc_location(), MODIFY_EXPR, void_type_node,
1169                                var_tree, expr_tree),
1170                     var_tree);
1171 }
1172
1173 // Dump.
1174
1175 void
1176 Set_and_use_temporary_expression::do_dump_expression(
1177     Ast_dump_context* ast_dump_context) const
1178 {
1179   ast_dump_context->ostream() << '(';
1180   ast_dump_context->dump_temp_variable_name(this->statement_);
1181   ast_dump_context->ostream() << " = ";
1182   this->expr_->dump_expression(ast_dump_context);
1183   ast_dump_context->ostream() << ')';
1184 }
1185
1186 // Make a set-and-use temporary.
1187
1188 Set_and_use_temporary_expression*
1189 Expression::make_set_and_use_temporary(Temporary_statement* statement,
1190                                        Expression* expr, Location location)
1191 {
1192   return new Set_and_use_temporary_expression(statement, expr, location);
1193 }
1194
1195 // A sink expression--a use of the blank identifier _.
1196
1197 class Sink_expression : public Expression
1198 {
1199  public:
1200   Sink_expression(Location location)
1201     : Expression(EXPRESSION_SINK, location),
1202       type_(NULL), var_(NULL_TREE)
1203   { }
1204
1205  protected:
1206   void
1207   do_discarding_value()
1208   { }
1209
1210   Type*
1211   do_type();
1212
1213   void
1214   do_determine_type(const Type_context*);
1215
1216   Expression*
1217   do_copy()
1218   { return new Sink_expression(this->location()); }
1219
1220   tree
1221   do_get_tree(Translate_context*);
1222
1223   void
1224   do_dump_expression(Ast_dump_context*) const;
1225
1226  private:
1227   // The type of this sink variable.
1228   Type* type_;
1229   // The temporary variable we generate.
1230   tree var_;
1231 };
1232
1233 // Return the type of a sink expression.
1234
1235 Type*
1236 Sink_expression::do_type()
1237 {
1238   if (this->type_ == NULL)
1239     return Type::make_sink_type();
1240   return this->type_;
1241 }
1242
1243 // Determine the type of a sink expression.
1244
1245 void
1246 Sink_expression::do_determine_type(const Type_context* context)
1247 {
1248   if (context->type != NULL)
1249     this->type_ = context->type;
1250 }
1251
1252 // Return a temporary variable for a sink expression.  This will
1253 // presumably be a write-only variable which the middle-end will drop.
1254
1255 tree
1256 Sink_expression::do_get_tree(Translate_context* context)
1257 {
1258   if (this->var_ == NULL_TREE)
1259     {
1260       go_assert(this->type_ != NULL && !this->type_->is_sink_type());
1261       Btype* bt = this->type_->get_backend(context->gogo());
1262       this->var_ = create_tmp_var(type_to_tree(bt), "blank");
1263     }
1264   return this->var_;
1265 }
1266
1267 // Ast dump for sink expression.
1268
1269 void
1270 Sink_expression::do_dump_expression(Ast_dump_context* ast_dump_context) const
1271 {
1272   ast_dump_context->ostream() << "_" ;
1273 }
1274
1275 // Make a sink expression.
1276
1277 Expression*
1278 Expression::make_sink(Location location)
1279 {
1280   return new Sink_expression(location);
1281 }
1282
1283 // Class Func_expression.
1284
1285 // FIXME: Can a function expression appear in a constant expression?
1286 // The value is unchanging.  Initializing a constant to the address of
1287 // a function seems like it could work, though there might be little
1288 // point to it.
1289
1290 // Traversal.
1291
1292 int
1293 Func_expression::do_traverse(Traverse* traverse)
1294 {
1295   return (this->closure_ == NULL
1296           ? TRAVERSE_CONTINUE
1297           : Expression::traverse(&this->closure_, traverse));
1298 }
1299
1300 // Return the type of a function expression.
1301
1302 Type*
1303 Func_expression::do_type()
1304 {
1305   if (this->function_->is_function())
1306     return this->function_->func_value()->type();
1307   else if (this->function_->is_function_declaration())
1308     return this->function_->func_declaration_value()->type();
1309   else
1310     go_unreachable();
1311 }
1312
1313 // Get the tree for a function expression without evaluating the
1314 // closure.
1315
1316 tree
1317 Func_expression::get_tree_without_closure(Gogo* gogo)
1318 {
1319   Function_type* fntype;
1320   if (this->function_->is_function())
1321     fntype = this->function_->func_value()->type();
1322   else if (this->function_->is_function_declaration())
1323     fntype = this->function_->func_declaration_value()->type();
1324   else
1325     go_unreachable();
1326
1327   // Builtin functions are handled specially by Call_expression.  We
1328   // can't take their address.
1329   if (fntype->is_builtin())
1330     {
1331       error_at(this->location(),
1332                "invalid use of special builtin function %qs; must be called",
1333                this->function_->name().c_str());
1334       return error_mark_node;
1335     }
1336
1337   Named_object* no = this->function_;
1338
1339   tree id = no->get_id(gogo);
1340   if (id == error_mark_node)
1341     return error_mark_node;
1342
1343   tree fndecl;
1344   if (no->is_function())
1345     fndecl = no->func_value()->get_or_make_decl(gogo, no, id);
1346   else if (no->is_function_declaration())
1347     fndecl = no->func_declaration_value()->get_or_make_decl(gogo, no, id);
1348   else
1349     go_unreachable();
1350
1351   if (fndecl == error_mark_node)
1352     return error_mark_node;
1353
1354   return build_fold_addr_expr_loc(this->location().gcc_location(), fndecl);
1355 }
1356
1357 // Get the tree for a function expression.  This is used when we take
1358 // the address of a function rather than simply calling it.  If the
1359 // function has a closure, we must use a trampoline.
1360
1361 tree
1362 Func_expression::do_get_tree(Translate_context* context)
1363 {
1364   Gogo* gogo = context->gogo();
1365
1366   tree fnaddr = this->get_tree_without_closure(gogo);
1367   if (fnaddr == error_mark_node)
1368     return error_mark_node;
1369
1370   go_assert(TREE_CODE(fnaddr) == ADDR_EXPR
1371              && TREE_CODE(TREE_OPERAND(fnaddr, 0)) == FUNCTION_DECL);
1372   TREE_ADDRESSABLE(TREE_OPERAND(fnaddr, 0)) = 1;
1373
1374   // For a normal non-nested function call, that is all we have to do.
1375   if (!this->function_->is_function()
1376       || this->function_->func_value()->enclosing() == NULL)
1377     {
1378       go_assert(this->closure_ == NULL);
1379       return fnaddr;
1380     }
1381
1382   // For a nested function call, we have to always allocate a
1383   // trampoline.  If we don't always allocate, then closures will not
1384   // be reliably distinct.
1385   Expression* closure = this->closure_;
1386   tree closure_tree;
1387   if (closure == NULL)
1388     closure_tree = null_pointer_node;
1389   else
1390     {
1391       // Get the value of the closure.  This will be a pointer to
1392       // space allocated on the heap.
1393       closure_tree = closure->get_tree(context);
1394       if (closure_tree == error_mark_node)
1395         return error_mark_node;
1396       go_assert(POINTER_TYPE_P(TREE_TYPE(closure_tree)));
1397     }
1398
1399   // Now we need to build some code on the heap.  This code will load
1400   // the static chain pointer with the closure and then jump to the
1401   // body of the function.  The normal gcc approach is to build the
1402   // code on the stack.  Unfortunately we can not do that, as Go
1403   // permits us to return the function pointer.
1404
1405   return gogo->make_trampoline(fnaddr, closure_tree, this->location());
1406 }
1407
1408 // Ast dump for function.
1409
1410 void
1411 Func_expression::do_dump_expression(Ast_dump_context* ast_dump_context) const
1412 {
1413   ast_dump_context->ostream() << this->function_->name();
1414   if (this->closure_ != NULL)
1415     {
1416       ast_dump_context->ostream() << " {closure =  ";
1417       this->closure_->dump_expression(ast_dump_context);
1418       ast_dump_context->ostream() << "}";
1419     }
1420 }
1421
1422 // Make a reference to a function in an expression.
1423
1424 Expression*
1425 Expression::make_func_reference(Named_object* function, Expression* closure,
1426                                 Location location)
1427 {
1428   return new Func_expression(function, closure, location);
1429 }
1430
1431 // Class Unknown_expression.
1432
1433 // Return the name of an unknown expression.
1434
1435 const std::string&
1436 Unknown_expression::name() const
1437 {
1438   return this->named_object_->name();
1439 }
1440
1441 // Lower a reference to an unknown name.
1442
1443 Expression*
1444 Unknown_expression::do_lower(Gogo*, Named_object*, Statement_inserter*, int)
1445 {
1446   Location location = this->location();
1447   Named_object* no = this->named_object_;
1448   Named_object* real;
1449   if (!no->is_unknown())
1450     real = no;
1451   else
1452     {
1453       real = no->unknown_value()->real_named_object();
1454       if (real == NULL)
1455         {
1456           if (this->is_composite_literal_key_)
1457             return this;
1458           if (!this->no_error_message_)
1459             error_at(location, "reference to undefined name %qs",
1460                      this->named_object_->message_name().c_str());
1461           return Expression::make_error(location);
1462         }
1463     }
1464   switch (real->classification())
1465     {
1466     case Named_object::NAMED_OBJECT_CONST:
1467       return Expression::make_const_reference(real, location);
1468     case Named_object::NAMED_OBJECT_TYPE:
1469       return Expression::make_type(real->type_value(), location);
1470     case Named_object::NAMED_OBJECT_TYPE_DECLARATION:
1471       if (this->is_composite_literal_key_)
1472         return this;
1473       if (!this->no_error_message_)
1474         error_at(location, "reference to undefined type %qs",
1475                  real->message_name().c_str());
1476       return Expression::make_error(location);
1477     case Named_object::NAMED_OBJECT_VAR:
1478       real->var_value()->set_is_used();
1479       return Expression::make_var_reference(real, location);
1480     case Named_object::NAMED_OBJECT_FUNC:
1481     case Named_object::NAMED_OBJECT_FUNC_DECLARATION:
1482       return Expression::make_func_reference(real, NULL, location);
1483     case Named_object::NAMED_OBJECT_PACKAGE:
1484       if (this->is_composite_literal_key_)
1485         return this;
1486       if (!this->no_error_message_)
1487         error_at(location, "unexpected reference to package");
1488       return Expression::make_error(location);
1489     default:
1490       go_unreachable();
1491     }
1492 }
1493
1494 // Dump the ast representation for an unknown expression to a dump context.
1495
1496 void
1497 Unknown_expression::do_dump_expression(Ast_dump_context* ast_dump_context) const
1498 {
1499   ast_dump_context->ostream() << "_Unknown_(" << this->named_object_->name()
1500                               << ")";
1501 }
1502
1503 // Make a reference to an unknown name.
1504
1505 Unknown_expression*
1506 Expression::make_unknown_reference(Named_object* no, Location location)
1507 {
1508   return new Unknown_expression(no, location);
1509 }
1510
1511 // A boolean expression.
1512
1513 class Boolean_expression : public Expression
1514 {
1515  public:
1516   Boolean_expression(bool val, Location location)
1517     : Expression(EXPRESSION_BOOLEAN, location),
1518       val_(val), type_(NULL)
1519   { }
1520
1521   static Expression*
1522   do_import(Import*);
1523
1524  protected:
1525   bool
1526   do_is_constant() const
1527   { return true; }
1528
1529   Type*
1530   do_type();
1531
1532   void
1533   do_determine_type(const Type_context*);
1534
1535   Expression*
1536   do_copy()
1537   { return this; }
1538
1539   tree
1540   do_get_tree(Translate_context*)
1541   { return this->val_ ? boolean_true_node : boolean_false_node; }
1542
1543   void
1544   do_export(Export* exp) const
1545   { exp->write_c_string(this->val_ ? "true" : "false"); }
1546
1547   void
1548   do_dump_expression(Ast_dump_context* ast_dump_context) const
1549   { ast_dump_context->ostream() << (this->val_ ? "true" : "false"); }
1550
1551  private:
1552   // The constant.
1553   bool val_;
1554   // The type as determined by context.
1555   Type* type_;
1556 };
1557
1558 // Get the type.
1559
1560 Type*
1561 Boolean_expression::do_type()
1562 {
1563   if (this->type_ == NULL)
1564     this->type_ = Type::make_boolean_type();
1565   return this->type_;
1566 }
1567
1568 // Set the type from the context.
1569
1570 void
1571 Boolean_expression::do_determine_type(const Type_context* context)
1572 {
1573   if (this->type_ != NULL && !this->type_->is_abstract())
1574     ;
1575   else if (context->type != NULL && context->type->is_boolean_type())
1576     this->type_ = context->type;
1577   else if (!context->may_be_abstract)
1578     this->type_ = Type::lookup_bool_type();
1579 }
1580
1581 // Import a boolean constant.
1582
1583 Expression*
1584 Boolean_expression::do_import(Import* imp)
1585 {
1586   if (imp->peek_char() == 't')
1587     {
1588       imp->require_c_string("true");
1589       return Expression::make_boolean(true, imp->location());
1590     }
1591   else
1592     {
1593       imp->require_c_string("false");
1594       return Expression::make_boolean(false, imp->location());
1595     }
1596 }
1597
1598 // Make a boolean expression.
1599
1600 Expression*
1601 Expression::make_boolean(bool val, Location location)
1602 {
1603   return new Boolean_expression(val, location);
1604 }
1605
1606 // Class String_expression.
1607
1608 // Get the type.
1609
1610 Type*
1611 String_expression::do_type()
1612 {
1613   if (this->type_ == NULL)
1614     this->type_ = Type::make_string_type();
1615   return this->type_;
1616 }
1617
1618 // Set the type from the context.
1619
1620 void
1621 String_expression::do_determine_type(const Type_context* context)
1622 {
1623   if (this->type_ != NULL && !this->type_->is_abstract())
1624     ;
1625   else if (context->type != NULL && context->type->is_string_type())
1626     this->type_ = context->type;
1627   else if (!context->may_be_abstract)
1628     this->type_ = Type::lookup_string_type();
1629 }
1630
1631 // Build a string constant.
1632
1633 tree
1634 String_expression::do_get_tree(Translate_context* context)
1635 {
1636   return context->gogo()->go_string_constant_tree(this->val_);
1637 }
1638
1639  // Write string literal to string dump.
1640
1641 void
1642 String_expression::export_string(String_dump* exp,
1643                                  const String_expression* str)
1644 {
1645   std::string s;
1646   s.reserve(str->val_.length() * 4 + 2);
1647   s += '"';
1648   for (std::string::const_iterator p = str->val_.begin();
1649        p != str->val_.end();
1650        ++p)
1651     {
1652       if (*p == '\\' || *p == '"')
1653         {
1654           s += '\\';
1655           s += *p;
1656         }
1657       else if (*p >= 0x20 && *p < 0x7f)
1658         s += *p;
1659       else if (*p == '\n')
1660         s += "\\n";
1661       else if (*p == '\t')
1662         s += "\\t";
1663       else
1664         {
1665           s += "\\x";
1666           unsigned char c = *p;
1667           unsigned int dig = c >> 4;
1668           s += dig < 10 ? '0' + dig : 'A' + dig - 10;
1669           dig = c & 0xf;
1670           s += dig < 10 ? '0' + dig : 'A' + dig - 10;
1671         }
1672     }
1673   s += '"';
1674   exp->write_string(s);
1675 }
1676
1677 // Export a string expression.
1678
1679 void
1680 String_expression::do_export(Export* exp) const
1681 {
1682   String_expression::export_string(exp, this);
1683 }
1684
1685 // Import a string expression.
1686
1687 Expression*
1688 String_expression::do_import(Import* imp)
1689 {
1690   imp->require_c_string("\"");
1691   std::string val;
1692   while (true)
1693     {
1694       int c = imp->get_char();
1695       if (c == '"' || c == -1)
1696         break;
1697       if (c != '\\')
1698         val += static_cast<char>(c);
1699       else
1700         {
1701           c = imp->get_char();
1702           if (c == '\\' || c == '"')
1703             val += static_cast<char>(c);
1704           else if (c == 'n')
1705             val += '\n';
1706           else if (c == 't')
1707             val += '\t';
1708           else if (c == 'x')
1709             {
1710               c = imp->get_char();
1711               unsigned int vh = c >= '0' && c <= '9' ? c - '0' : c - 'A' + 10;
1712               c = imp->get_char();
1713               unsigned int vl = c >= '0' && c <= '9' ? c - '0' : c - 'A' + 10;
1714               char v = (vh << 4) | vl;
1715               val += v;
1716             }
1717           else
1718             {
1719               error_at(imp->location(), "bad string constant");
1720               return Expression::make_error(imp->location());
1721             }
1722         }
1723     }
1724   return Expression::make_string(val, imp->location());
1725 }
1726
1727 // Ast dump for string expression.
1728
1729 void
1730 String_expression::do_dump_expression(Ast_dump_context* ast_dump_context) const
1731 {
1732   String_expression::export_string(ast_dump_context, this);
1733 }
1734
1735 // Make a string expression.
1736
1737 Expression*
1738 Expression::make_string(const std::string& val, Location location)
1739 {
1740   return new String_expression(val, location);
1741 }
1742
1743 // Make an integer expression.
1744
1745 class Integer_expression : public Expression
1746 {
1747  public:
1748   Integer_expression(const mpz_t* val, Type* type, bool is_character_constant,
1749                      Location location)
1750     : Expression(EXPRESSION_INTEGER, location),
1751       type_(type), is_character_constant_(is_character_constant)
1752   { mpz_init_set(this->val_, *val); }
1753
1754   static Expression*
1755   do_import(Import*);
1756
1757   // Return whether VAL fits in the type.
1758   static bool
1759   check_constant(mpz_t val, Type*, Location);
1760
1761   // Write VAL to string dump.
1762   static void
1763   export_integer(String_dump* exp, const mpz_t val);
1764
1765   // Write VAL to dump context.
1766   static void
1767   dump_integer(Ast_dump_context* ast_dump_context, const mpz_t val);
1768
1769  protected:
1770   bool
1771   do_is_constant() const
1772   { return true; }
1773
1774   bool
1775   do_integer_constant_value(bool, mpz_t val, Type** ptype) const;
1776
1777   Type*
1778   do_type();
1779
1780   void
1781   do_determine_type(const Type_context* context);
1782
1783   void
1784   do_check_types(Gogo*);
1785
1786   tree
1787   do_get_tree(Translate_context*);
1788
1789   Expression*
1790   do_copy()
1791   {
1792     if (this->is_character_constant_)
1793       return Expression::make_character(&this->val_, this->type_,
1794                                         this->location());
1795     else
1796       return Expression::make_integer(&this->val_, this->type_,
1797                                       this->location());
1798   }
1799
1800   void
1801   do_export(Export*) const;
1802
1803   void
1804   do_dump_expression(Ast_dump_context*) const;
1805
1806  private:
1807   // The integer value.
1808   mpz_t val_;
1809   // The type so far.
1810   Type* type_;
1811   // Whether this is a character constant.
1812   bool is_character_constant_;
1813 };
1814
1815 // Return an integer constant value.
1816
1817 bool
1818 Integer_expression::do_integer_constant_value(bool, mpz_t val,
1819                                               Type** ptype) const
1820 {
1821   if (this->type_ != NULL)
1822     *ptype = this->type_;
1823   mpz_set(val, this->val_);
1824   return true;
1825 }
1826
1827 // Return the current type.  If we haven't set the type yet, we return
1828 // an abstract integer type.
1829
1830 Type*
1831 Integer_expression::do_type()
1832 {
1833   if (this->type_ == NULL)
1834     {
1835       if (this->is_character_constant_)
1836         this->type_ = Type::make_abstract_character_type();
1837       else
1838         this->type_ = Type::make_abstract_integer_type();
1839     }
1840   return this->type_;
1841 }
1842
1843 // Set the type of the integer value.  Here we may switch from an
1844 // abstract type to a real type.
1845
1846 void
1847 Integer_expression::do_determine_type(const Type_context* context)
1848 {
1849   if (this->type_ != NULL && !this->type_->is_abstract())
1850     ;
1851   else if (context->type != NULL
1852            && (context->type->integer_type() != NULL
1853                || context->type->float_type() != NULL
1854                || context->type->complex_type() != NULL))
1855     this->type_ = context->type;
1856   else if (!context->may_be_abstract)
1857     {
1858       if (this->is_character_constant_)
1859         this->type_ = Type::lookup_integer_type("int32");
1860       else
1861         this->type_ = Type::lookup_integer_type("int");
1862     }
1863 }
1864
1865 // Return true if the integer VAL fits in the range of the type TYPE.
1866 // Otherwise give an error and return false.  TYPE may be NULL.
1867
1868 bool
1869 Integer_expression::check_constant(mpz_t val, Type* type,
1870                                    Location location)
1871 {
1872   if (type == NULL)
1873     return true;
1874   Integer_type* itype = type->integer_type();
1875   if (itype == NULL || itype->is_abstract())
1876     return true;
1877
1878   int bits = mpz_sizeinbase(val, 2);
1879
1880   if (itype->is_unsigned())
1881     {
1882       // For an unsigned type we can only accept a nonnegative number,
1883       // and we must be able to represent at least BITS.
1884       if (mpz_sgn(val) >= 0
1885           && bits <= itype->bits())
1886         return true;
1887     }
1888   else
1889     {
1890       // For a signed type we need an extra bit to indicate the sign.
1891       // We have to handle the most negative integer specially.
1892       if (bits + 1 <= itype->bits()
1893           || (bits <= itype->bits()
1894               && mpz_sgn(val) < 0
1895               && (mpz_scan1(val, 0)
1896                   == static_cast<unsigned long>(itype->bits() - 1))
1897               && mpz_scan0(val, itype->bits()) == ULONG_MAX))
1898         return true;
1899     }
1900
1901   error_at(location, "integer constant overflow");
1902   return false;
1903 }
1904
1905 // Check the type of an integer constant.
1906
1907 void
1908 Integer_expression::do_check_types(Gogo*)
1909 {
1910   if (this->type_ == NULL)
1911     return;
1912   if (!Integer_expression::check_constant(this->val_, this->type_,
1913                                           this->location()))
1914     this->set_is_error();
1915 }
1916
1917 // Get a tree for an integer constant.
1918
1919 tree
1920 Integer_expression::do_get_tree(Translate_context* context)
1921 {
1922   Gogo* gogo = context->gogo();
1923   tree type;
1924   if (this->type_ != NULL && !this->type_->is_abstract())
1925     type = type_to_tree(this->type_->get_backend(gogo));
1926   else if (this->type_ != NULL && this->type_->float_type() != NULL)
1927     {
1928       // We are converting to an abstract floating point type.
1929       Type* ftype = Type::lookup_float_type("float64");
1930       type = type_to_tree(ftype->get_backend(gogo));
1931     }
1932   else if (this->type_ != NULL && this->type_->complex_type() != NULL)
1933     {
1934       // We are converting to an abstract complex type.
1935       Type* ctype = Type::lookup_complex_type("complex128");
1936       type = type_to_tree(ctype->get_backend(gogo));
1937     }
1938   else
1939     {
1940       // If we still have an abstract type here, then this is being
1941       // used in a constant expression which didn't get reduced for
1942       // some reason.  Use a type which will fit the value.  We use <,
1943       // not <=, because we need an extra bit for the sign bit.
1944       int bits = mpz_sizeinbase(this->val_, 2);
1945       if (bits < INT_TYPE_SIZE)
1946         {
1947           Type* t = Type::lookup_integer_type("int");
1948           type = type_to_tree(t->get_backend(gogo));
1949         }
1950       else if (bits < 64)
1951         {
1952           Type* t = Type::lookup_integer_type("int64");
1953           type = type_to_tree(t->get_backend(gogo));
1954         }
1955       else
1956         type = long_long_integer_type_node;
1957     }
1958   return Expression::integer_constant_tree(this->val_, type);
1959 }
1960
1961 // Write VAL to export data.
1962
1963 void
1964 Integer_expression::export_integer(String_dump* exp, const mpz_t val)
1965 {
1966   char* s = mpz_get_str(NULL, 10, val);
1967   exp->write_c_string(s);
1968   free(s);
1969 }
1970
1971 // Export an integer in a constant expression.
1972
1973 void
1974 Integer_expression::do_export(Export* exp) const
1975 {
1976   Integer_expression::export_integer(exp, this->val_);
1977   if (this->is_character_constant_)
1978     exp->write_c_string("'");
1979   // A trailing space lets us reliably identify the end of the number.
1980   exp->write_c_string(" ");
1981 }
1982
1983 // Import an integer, floating point, or complex value.  This handles
1984 // all these types because they all start with digits.
1985
1986 Expression*
1987 Integer_expression::do_import(Import* imp)
1988 {
1989   std::string num = imp->read_identifier();
1990   imp->require_c_string(" ");
1991   if (!num.empty() && num[num.length() - 1] == 'i')
1992     {
1993       mpfr_t real;
1994       size_t plus_pos = num.find('+', 1);
1995       size_t minus_pos = num.find('-', 1);
1996       size_t pos;
1997       if (plus_pos == std::string::npos)
1998         pos = minus_pos;
1999       else if (minus_pos == std::string::npos)
2000         pos = plus_pos;
2001       else
2002         {
2003           error_at(imp->location(), "bad number in import data: %qs",
2004                    num.c_str());
2005           return Expression::make_error(imp->location());
2006         }
2007       if (pos == std::string::npos)
2008         mpfr_set_ui(real, 0, GMP_RNDN);
2009       else
2010         {
2011           std::string real_str = num.substr(0, pos);
2012           if (mpfr_init_set_str(real, real_str.c_str(), 10, GMP_RNDN) != 0)
2013             {
2014               error_at(imp->location(), "bad number in import data: %qs",
2015                        real_str.c_str());
2016               return Expression::make_error(imp->location());
2017             }
2018         }
2019
2020       std::string imag_str;
2021       if (pos == std::string::npos)
2022         imag_str = num;
2023       else
2024         imag_str = num.substr(pos);
2025       imag_str = imag_str.substr(0, imag_str.size() - 1);
2026       mpfr_t imag;
2027       if (mpfr_init_set_str(imag, imag_str.c_str(), 10, GMP_RNDN) != 0)
2028         {
2029           error_at(imp->location(), "bad number in import data: %qs",
2030                    imag_str.c_str());
2031           return Expression::make_error(imp->location());
2032         }
2033       Expression* ret = Expression::make_complex(&real, &imag, NULL,
2034                                                  imp->location());
2035       mpfr_clear(real);
2036       mpfr_clear(imag);
2037       return ret;
2038     }
2039   else if (num.find('.') == std::string::npos
2040            && num.find('E') == std::string::npos)
2041     {
2042       bool is_character_constant = (!num.empty()
2043                                     && num[num.length() - 1] == '\'');
2044       if (is_character_constant)
2045         num = num.substr(0, num.length() - 1);
2046       mpz_t val;
2047       if (mpz_init_set_str(val, num.c_str(), 10) != 0)
2048         {
2049           error_at(imp->location(), "bad number in import data: %qs",
2050                    num.c_str());
2051           return Expression::make_error(imp->location());
2052         }
2053       Expression* ret;
2054       if (is_character_constant)
2055         ret = Expression::make_character(&val, NULL, imp->location());
2056       else
2057         ret = Expression::make_integer(&val, NULL, imp->location());
2058       mpz_clear(val);
2059       return ret;
2060     }
2061   else
2062     {
2063       mpfr_t val;
2064       if (mpfr_init_set_str(val, num.c_str(), 10, GMP_RNDN) != 0)
2065         {
2066           error_at(imp->location(), "bad number in import data: %qs",
2067                    num.c_str());
2068           return Expression::make_error(imp->location());
2069         }
2070       Expression* ret = Expression::make_float(&val, NULL, imp->location());
2071       mpfr_clear(val);
2072       return ret;
2073     }
2074 }
2075 // Ast dump for integer expression.
2076
2077 void
2078 Integer_expression::do_dump_expression(Ast_dump_context* ast_dump_context) const
2079 {
2080   if (this->is_character_constant_)
2081     ast_dump_context->ostream() << '\'';
2082   Integer_expression::export_integer(ast_dump_context, this->val_);
2083   if (this->is_character_constant_)
2084     ast_dump_context->ostream() << '\'';
2085 }
2086
2087 // Build a new integer value.
2088
2089 Expression*
2090 Expression::make_integer(const mpz_t* val, Type* type, Location location)
2091 {
2092   return new Integer_expression(val, type, false, location);
2093 }
2094
2095 // Build a new character constant value.
2096
2097 Expression*
2098 Expression::make_character(const mpz_t* val, Type* type, Location location)
2099 {
2100   return new Integer_expression(val, type, true, location);
2101 }
2102
2103 // Floats.
2104
2105 class Float_expression : public Expression
2106 {
2107  public:
2108   Float_expression(const mpfr_t* val, Type* type, Location location)
2109     : Expression(EXPRESSION_FLOAT, location),
2110       type_(type)
2111   {
2112     mpfr_init_set(this->val_, *val, GMP_RNDN);
2113   }
2114
2115   // Constrain VAL to fit into TYPE.
2116   static void
2117   constrain_float(mpfr_t val, Type* type);
2118
2119   // Return whether VAL fits in the type.
2120   static bool
2121   check_constant(mpfr_t val, Type*, Location);
2122
2123   // Write VAL to export data.
2124   static void
2125   export_float(String_dump* exp, const mpfr_t val);
2126
2127   // Write VAL to dump file.
2128   static void
2129   dump_float(Ast_dump_context* ast_dump_context, const mpfr_t val);
2130
2131  protected:
2132   bool
2133   do_is_constant() const
2134   { return true; }
2135
2136   bool
2137   do_float_constant_value(mpfr_t val, Type**) const;
2138
2139   Type*
2140   do_type();
2141
2142   void
2143   do_determine_type(const Type_context*);
2144
2145   void
2146   do_check_types(Gogo*);
2147
2148   Expression*
2149   do_copy()
2150   { return Expression::make_float(&this->val_, this->type_,
2151                                   this->location()); }
2152
2153   tree
2154   do_get_tree(Translate_context*);
2155
2156   void
2157   do_export(Export*) const;
2158
2159   void
2160   do_dump_expression(Ast_dump_context*) const;
2161
2162  private:
2163   // The floating point value.
2164   mpfr_t val_;
2165   // The type so far.
2166   Type* type_;
2167 };
2168
2169 // Constrain VAL to fit into TYPE.
2170
2171 void
2172 Float_expression::constrain_float(mpfr_t val, Type* type)
2173 {
2174   Float_type* ftype = type->float_type();
2175   if (ftype != NULL && !ftype->is_abstract())
2176     mpfr_prec_round(val, ftype->bits(), GMP_RNDN);
2177 }
2178
2179 // Return a floating point constant value.
2180
2181 bool
2182 Float_expression::do_float_constant_value(mpfr_t val, Type** ptype) const
2183 {
2184   if (this->type_ != NULL)
2185     *ptype = this->type_;
2186   mpfr_set(val, this->val_, GMP_RNDN);
2187   return true;
2188 }
2189
2190 // Return the current type.  If we haven't set the type yet, we return
2191 // an abstract float type.
2192
2193 Type*
2194 Float_expression::do_type()
2195 {
2196   if (this->type_ == NULL)
2197     this->type_ = Type::make_abstract_float_type();
2198   return this->type_;
2199 }
2200
2201 // Set the type of the float value.  Here we may switch from an
2202 // abstract type to a real type.
2203
2204 void
2205 Float_expression::do_determine_type(const Type_context* context)
2206 {
2207   if (this->type_ != NULL && !this->type_->is_abstract())
2208     ;
2209   else if (context->type != NULL
2210            && (context->type->integer_type() != NULL
2211                || context->type->float_type() != NULL
2212                || context->type->complex_type() != NULL))
2213     this->type_ = context->type;
2214   else if (!context->may_be_abstract)
2215     this->type_ = Type::lookup_float_type("float64");
2216 }
2217
2218 // Return true if the floating point value VAL fits in the range of
2219 // the type TYPE.  Otherwise give an error and return false.  TYPE may
2220 // be NULL.
2221
2222 bool
2223 Float_expression::check_constant(mpfr_t val, Type* type,
2224                                  Location location)
2225 {
2226   if (type == NULL)
2227     return true;
2228   Float_type* ftype = type->float_type();
2229   if (ftype == NULL || ftype->is_abstract())
2230     return true;
2231
2232   // A NaN or Infinity always fits in the range of the type.
2233   if (mpfr_nan_p(val) || mpfr_inf_p(val) || mpfr_zero_p(val))
2234     return true;
2235
2236   mp_exp_t exp = mpfr_get_exp(val);
2237   mp_exp_t max_exp;
2238   switch (ftype->bits())
2239     {
2240     case 32:
2241       max_exp = 128;
2242       break;
2243     case 64:
2244       max_exp = 1024;
2245       break;
2246     default:
2247       go_unreachable();
2248     }
2249   if (exp > max_exp)
2250     {
2251       error_at(location, "floating point constant overflow");
2252       return false;
2253     }
2254   return true;
2255 }
2256
2257 // Check the type of a float value.
2258
2259 void
2260 Float_expression::do_check_types(Gogo*)
2261 {
2262   if (this->type_ == NULL)
2263     return;
2264
2265   if (!Float_expression::check_constant(this->val_, this->type_,
2266                                         this->location()))
2267     this->set_is_error();
2268
2269   Integer_type* integer_type = this->type_->integer_type();
2270   if (integer_type != NULL)
2271     {
2272       if (!mpfr_integer_p(this->val_))
2273         this->report_error(_("floating point constant truncated to integer"));
2274       else
2275         {
2276           go_assert(!integer_type->is_abstract());
2277           mpz_t ival;
2278           mpz_init(ival);
2279           mpfr_get_z(ival, this->val_, GMP_RNDN);
2280           Integer_expression::check_constant(ival, integer_type,
2281                                              this->location());
2282           mpz_clear(ival);
2283         }
2284     }
2285 }
2286
2287 // Get a tree for a float constant.
2288
2289 tree
2290 Float_expression::do_get_tree(Translate_context* context)
2291 {
2292   Gogo* gogo = context->gogo();
2293   tree type;
2294   if (this->type_ != NULL && !this->type_->is_abstract())
2295     type = type_to_tree(this->type_->get_backend(gogo));
2296   else if (this->type_ != NULL && this->type_->integer_type() != NULL)
2297     {
2298       // We have an abstract integer type.  We just hope for the best.
2299       type = type_to_tree(Type::lookup_integer_type("int")->get_backend(gogo));
2300     }
2301   else
2302     {
2303       // If we still have an abstract type here, then this is being
2304       // used in a constant expression which didn't get reduced.  We
2305       // just use float64 and hope for the best.
2306       Type* ft = Type::lookup_float_type("float64");
2307       type = type_to_tree(ft->get_backend(gogo));
2308     }
2309   return Expression::float_constant_tree(this->val_, type);
2310 }
2311
2312 // Write a floating point number to a string dump.
2313
2314 void
2315 Float_expression::export_float(String_dump *exp, const mpfr_t val)
2316 {
2317   mp_exp_t exponent;
2318   char* s = mpfr_get_str(NULL, &exponent, 10, 0, val, GMP_RNDN);
2319   if (*s == '-')
2320     exp->write_c_string("-");
2321   exp->write_c_string("0.");
2322   exp->write_c_string(*s == '-' ? s + 1 : s);
2323   mpfr_free_str(s);
2324   char buf[30];
2325   snprintf(buf, sizeof buf, "E%ld", exponent);
2326   exp->write_c_string(buf);
2327 }
2328
2329 // Export a floating point number in a constant expression.
2330
2331 void
2332 Float_expression::do_export(Export* exp) const
2333 {
2334   Float_expression::export_float(exp, this->val_);
2335   // A trailing space lets us reliably identify the end of the number.
2336   exp->write_c_string(" ");
2337 }
2338
2339 // Dump a floating point number to the dump file.
2340
2341 void
2342 Float_expression::do_dump_expression(Ast_dump_context* ast_dump_context) const
2343 {
2344   Float_expression::export_float(ast_dump_context, this->val_);
2345 }
2346
2347 // Make a float expression.
2348
2349 Expression*
2350 Expression::make_float(const mpfr_t* val, Type* type, Location location)
2351 {
2352   return new Float_expression(val, type, location);
2353 }
2354
2355 // Complex numbers.
2356
2357 class Complex_expression : public Expression
2358 {
2359  public:
2360   Complex_expression(const mpfr_t* real, const mpfr_t* imag, Type* type,
2361                      Location location)
2362     : Expression(EXPRESSION_COMPLEX, location),
2363       type_(type)
2364   {
2365     mpfr_init_set(this->real_, *real, GMP_RNDN);
2366     mpfr_init_set(this->imag_, *imag, GMP_RNDN);
2367   }
2368
2369   // Constrain REAL/IMAG to fit into TYPE.
2370   static void
2371   constrain_complex(mpfr_t real, mpfr_t imag, Type* type);
2372
2373   // Return whether REAL/IMAG fits in the type.
2374   static bool
2375   check_constant(mpfr_t real, mpfr_t imag, Type*, Location);
2376
2377   // Write REAL/IMAG to string dump.
2378   static void
2379   export_complex(String_dump* exp, const mpfr_t real, const mpfr_t val);
2380
2381   // Write REAL/IMAG to dump context.
2382   static void
2383   dump_complex(Ast_dump_context* ast_dump_context,
2384                const mpfr_t real, const mpfr_t val);
2385
2386  protected:
2387   bool
2388   do_is_constant() const
2389   { return true; }
2390
2391   bool
2392   do_complex_constant_value(mpfr_t real, mpfr_t imag, Type**) const;
2393
2394   Type*
2395   do_type();
2396
2397   void
2398   do_determine_type(const Type_context*);
2399
2400   void
2401   do_check_types(Gogo*);
2402
2403   Expression*
2404   do_copy()
2405   {
2406     return Expression::make_complex(&this->real_, &this->imag_, this->type_,
2407                                     this->location());
2408   }
2409
2410   tree
2411   do_get_tree(Translate_context*);
2412
2413   void
2414   do_export(Export*) const;
2415
2416   void
2417   do_dump_expression(Ast_dump_context*) const;
2418
2419  private:
2420   // The real part.
2421   mpfr_t real_;
2422   // The imaginary part;
2423   mpfr_t imag_;
2424   // The type if known.
2425   Type* type_;
2426 };
2427
2428 // Constrain REAL/IMAG to fit into TYPE.
2429
2430 void
2431 Complex_expression::constrain_complex(mpfr_t real, mpfr_t imag, Type* type)
2432 {
2433   Complex_type* ctype = type->complex_type();
2434   if (ctype != NULL && !ctype->is_abstract())
2435     {
2436       mpfr_prec_round(real, ctype->bits() / 2, GMP_RNDN);
2437       mpfr_prec_round(imag, ctype->bits() / 2, GMP_RNDN);
2438     }
2439 }
2440
2441 // Return a complex constant value.
2442
2443 bool
2444 Complex_expression::do_complex_constant_value(mpfr_t real, mpfr_t imag,
2445                                               Type** ptype) const
2446 {
2447   if (this->type_ != NULL)
2448     *ptype = this->type_;
2449   mpfr_set(real, this->real_, GMP_RNDN);
2450   mpfr_set(imag, this->imag_, GMP_RNDN);
2451   return true;
2452 }
2453
2454 // Return the current type.  If we haven't set the type yet, we return
2455 // an abstract complex type.
2456
2457 Type*
2458 Complex_expression::do_type()
2459 {
2460   if (this->type_ == NULL)
2461     this->type_ = Type::make_abstract_complex_type();
2462   return this->type_;
2463 }
2464
2465 // Set the type of the complex value.  Here we may switch from an
2466 // abstract type to a real type.
2467
2468 void
2469 Complex_expression::do_determine_type(const Type_context* context)
2470 {
2471   if (this->type_ != NULL && !this->type_->is_abstract())
2472     ;
2473   else if (context->type != NULL
2474            && context->type->complex_type() != NULL)
2475     this->type_ = context->type;
2476   else if (!context->may_be_abstract)
2477     this->type_ = Type::lookup_complex_type("complex128");
2478 }
2479
2480 // Return true if the complex value REAL/IMAG fits in the range of the
2481 // type TYPE.  Otherwise give an error and return false.  TYPE may be
2482 // NULL.
2483
2484 bool
2485 Complex_expression::check_constant(mpfr_t real, mpfr_t imag, Type* type,
2486                                    Location location)
2487 {
2488   if (type == NULL)
2489     return true;
2490   Complex_type* ctype = type->complex_type();
2491   if (ctype == NULL || ctype->is_abstract())
2492     return true;
2493
2494   mp_exp_t max_exp;
2495   switch (ctype->bits())
2496     {
2497     case 64:
2498       max_exp = 128;
2499       break;
2500     case 128:
2501       max_exp = 1024;
2502       break;
2503     default:
2504       go_unreachable();
2505     }
2506
2507   // A NaN or Infinity always fits in the range of the type.
2508   if (!mpfr_nan_p(real) && !mpfr_inf_p(real) && !mpfr_zero_p(real))
2509     {
2510       if (mpfr_get_exp(real) > max_exp)
2511         {
2512           error_at(location, "complex real part constant overflow");
2513           return false;
2514         }
2515     }
2516
2517   if (!mpfr_nan_p(imag) && !mpfr_inf_p(imag) && !mpfr_zero_p(imag))
2518     {
2519       if (mpfr_get_exp(imag) > max_exp)
2520         {
2521           error_at(location, "complex imaginary part constant overflow");
2522           return false;
2523         }
2524     }
2525
2526   return true;
2527 }
2528
2529 // Check the type of a complex value.
2530
2531 void
2532 Complex_expression::do_check_types(Gogo*)
2533 {
2534   if (this->type_ == NULL)
2535     return;
2536
2537   if (!Complex_expression::check_constant(this->real_, this->imag_,
2538                                           this->type_, this->location()))
2539     this->set_is_error();
2540 }
2541
2542 // Get a tree for a complex constant.
2543
2544 tree
2545 Complex_expression::do_get_tree(Translate_context* context)
2546 {
2547   Gogo* gogo = context->gogo();
2548   tree type;
2549   if (this->type_ != NULL && !this->type_->is_abstract())
2550     type = type_to_tree(this->type_->get_backend(gogo));
2551   else
2552     {
2553       // If we still have an abstract type here, this this is being
2554       // used in a constant expression which didn't get reduced.  We
2555       // just use complex128 and hope for the best.
2556       Type* ct = Type::lookup_complex_type("complex128");
2557       type = type_to_tree(ct->get_backend(gogo));
2558     }
2559   return Expression::complex_constant_tree(this->real_, this->imag_, type);
2560 }
2561
2562 // Write REAL/IMAG to export data.
2563
2564 void
2565 Complex_expression::export_complex(String_dump* exp, const mpfr_t real,
2566                                    const mpfr_t imag)
2567 {
2568   if (!mpfr_zero_p(real))
2569     {
2570       Float_expression::export_float(exp, real);
2571       if (mpfr_sgn(imag) > 0)
2572         exp->write_c_string("+");
2573     }
2574   Float_expression::export_float(exp, imag);
2575   exp->write_c_string("i");
2576 }
2577
2578 // Export a complex number in a constant expression.
2579
2580 void
2581 Complex_expression::do_export(Export* exp) const
2582 {
2583   Complex_expression::export_complex(exp, this->real_, this->imag_);
2584   // A trailing space lets us reliably identify the end of the number.
2585   exp->write_c_string(" ");
2586 }
2587
2588 // Dump a complex expression to the dump file.
2589
2590 void
2591 Complex_expression::do_dump_expression(Ast_dump_context* ast_dump_context) const
2592 {
2593   Complex_expression::export_complex(ast_dump_context,
2594                                       this->real_,
2595                                       this->imag_);
2596 }
2597
2598 // Make a complex expression.
2599
2600 Expression*
2601 Expression::make_complex(const mpfr_t* real, const mpfr_t* imag, Type* type,
2602                          Location location)
2603 {
2604   return new Complex_expression(real, imag, type, location);
2605 }
2606
2607 // Find a named object in an expression.
2608
2609 class Find_named_object : public Traverse
2610 {
2611  public:
2612   Find_named_object(Named_object* no)
2613     : Traverse(traverse_expressions),
2614       no_(no), found_(false)
2615   { }
2616
2617   // Whether we found the object.
2618   bool
2619   found() const
2620   { return this->found_; }
2621
2622  protected:
2623   int
2624   expression(Expression**);
2625
2626  private:
2627   // The object we are looking for.
2628   Named_object* no_;
2629   // Whether we found it.
2630   bool found_;
2631 };
2632
2633 // A reference to a const in an expression.
2634
2635 class Const_expression : public Expression
2636 {
2637  public:
2638   Const_expression(Named_object* constant, Location location)
2639     : Expression(EXPRESSION_CONST_REFERENCE, location),
2640       constant_(constant), type_(NULL), seen_(false)
2641   { }
2642
2643   Named_object*
2644   named_object()
2645   { return this->constant_; }
2646
2647   // Check that the initializer does not refer to the constant itself.
2648   void
2649   check_for_init_loop();
2650
2651  protected:
2652   int
2653   do_traverse(Traverse*);
2654
2655   Expression*
2656   do_lower(Gogo*, Named_object*, Statement_inserter*, int);
2657
2658   bool
2659   do_is_constant() const
2660   { return true; }
2661
2662   bool
2663   do_integer_constant_value(bool, mpz_t val, Type**) const;
2664
2665   bool
2666   do_float_constant_value(mpfr_t val, Type**) const;
2667
2668   bool
2669   do_complex_constant_value(mpfr_t real, mpfr_t imag, Type**) const;
2670
2671   bool
2672   do_string_constant_value(std::string* val) const
2673   { return this->constant_->const_value()->expr()->string_constant_value(val); }
2674
2675   Type*
2676   do_type();
2677
2678   // The type of a const is set by the declaration, not the use.
2679   void
2680   do_determine_type(const Type_context*);
2681
2682   void
2683   do_check_types(Gogo*);
2684
2685   Expression*
2686   do_copy()
2687   { return this; }
2688
2689   tree
2690   do_get_tree(Translate_context* context);
2691
2692   // When exporting a reference to a const as part of a const
2693   // expression, we export the value.  We ignore the fact that it has
2694   // a name.
2695   void
2696   do_export(Export* exp) const
2697   { this->constant_->const_value()->expr()->export_expression(exp); }
2698
2699   void
2700   do_dump_expression(Ast_dump_context*) const;
2701
2702  private:
2703   // The constant.
2704   Named_object* constant_;
2705   // The type of this reference.  This is used if the constant has an
2706   // abstract type.
2707   Type* type_;
2708   // Used to prevent infinite recursion when a constant incorrectly
2709   // refers to itself.
2710   mutable bool seen_;
2711 };
2712
2713 // Traversal.
2714
2715 int
2716 Const_expression::do_traverse(Traverse* traverse)
2717 {
2718   if (this->type_ != NULL)
2719     return Type::traverse(this->type_, traverse);
2720   return TRAVERSE_CONTINUE;
2721 }
2722
2723 // Lower a constant expression.  This is where we convert the
2724 // predeclared constant iota into an integer value.
2725
2726 Expression*
2727 Const_expression::do_lower(Gogo* gogo, Named_object*,
2728                            Statement_inserter*, int iota_value)
2729 {
2730   if (this->constant_->const_value()->expr()->classification()
2731       == EXPRESSION_IOTA)
2732     {
2733       if (iota_value == -1)
2734         {
2735           error_at(this->location(),
2736                    "iota is only defined in const declarations");
2737           iota_value = 0;
2738         }
2739       mpz_t val;
2740       mpz_init_set_ui(val, static_cast<unsigned long>(iota_value));
2741       Expression* ret = Expression::make_integer(&val, NULL,
2742                                                  this->location());
2743       mpz_clear(val);
2744       return ret;
2745     }
2746
2747   // Make sure that the constant itself has been lowered.
2748   gogo->lower_constant(this->constant_);
2749
2750   return this;
2751 }
2752
2753 // Return an integer constant value.
2754
2755 bool
2756 Const_expression::do_integer_constant_value(bool iota_is_constant, mpz_t val,
2757                                             Type** ptype) const
2758 {
2759   if (this->seen_)
2760     return false;
2761
2762   Type* ctype;
2763   if (this->type_ != NULL)
2764     ctype = this->type_;
2765   else
2766     ctype = this->constant_->const_value()->type();
2767   if (ctype != NULL && ctype->integer_type() == NULL)
2768     return false;
2769
2770   Expression* e = this->constant_->const_value()->expr();
2771
2772   this->seen_ = true;
2773
2774   Type* t;
2775   bool r = e->integer_constant_value(iota_is_constant, val, &t);
2776
2777   this->seen_ = false;
2778
2779   if (r
2780       && ctype != NULL
2781       && !Integer_expression::check_constant(val, ctype, this->location()))
2782     return false;
2783
2784   *ptype = ctype != NULL ? ctype : t;
2785   return r;
2786 }
2787
2788 // Return a floating point constant value.
2789
2790 bool
2791 Const_expression::do_float_constant_value(mpfr_t val, Type** ptype) const
2792 {
2793   if (this->seen_)
2794     return false;
2795
2796   Type* ctype;
2797   if (this->type_ != NULL)
2798     ctype = this->type_;
2799   else
2800     ctype = this->constant_->const_value()->type();
2801   if (ctype != NULL && ctype->float_type() == NULL)
2802     return false;
2803
2804   this->seen_ = true;
2805
2806   Type* t;
2807   bool r = this->constant_->const_value()->expr()->float_constant_value(val,
2808                                                                         &t);
2809
2810   this->seen_ = false;
2811
2812   if (r && ctype != NULL)
2813     {
2814       if (!Float_expression::check_constant(val, ctype, this->location()))
2815         return false;
2816       Float_expression::constrain_float(val, ctype);
2817     }
2818   *ptype = ctype != NULL ? ctype : t;
2819   return r;
2820 }
2821
2822 // Return a complex constant value.
2823
2824 bool
2825 Const_expression::do_complex_constant_value(mpfr_t real, mpfr_t imag,
2826                                             Type **ptype) const
2827 {
2828   if (this->seen_)
2829     return false;
2830
2831   Type* ctype;
2832   if (this->type_ != NULL)
2833     ctype = this->type_;
2834   else
2835     ctype = this->constant_->const_value()->type();
2836   if (ctype != NULL && ctype->complex_type() == NULL)
2837     return false;
2838
2839   this->seen_ = true;
2840
2841   Type *t;
2842   bool r = this->constant_->const_value()->expr()->complex_constant_value(real,
2843                                                                           imag,
2844                                                                           &t);
2845
2846   this->seen_ = false;
2847
2848   if (r && ctype != NULL)
2849     {
2850       if (!Complex_expression::check_constant(real, imag, ctype,
2851                                               this->location()))
2852         return false;
2853       Complex_expression::constrain_complex(real, imag, ctype);
2854     }
2855   *ptype = ctype != NULL ? ctype : t;
2856   return r;
2857 }
2858
2859 // Return the type of the const reference.
2860
2861 Type*
2862 Const_expression::do_type()
2863 {
2864   if (this->type_ != NULL)
2865     return this->type_;
2866
2867   Named_constant* nc = this->constant_->const_value();
2868
2869   if (this->seen_ || nc->lowering())
2870     {
2871       this->report_error(_("constant refers to itself"));
2872       this->type_ = Type::make_error_type();
2873       return this->type_;
2874     }
2875
2876   this->seen_ = true;
2877
2878   Type* ret = nc->type();
2879
2880   if (ret != NULL)
2881     {
2882       this->seen_ = false;
2883       return ret;
2884     }
2885
2886   // During parsing, a named constant may have a NULL type, but we
2887   // must not return a NULL type here.
2888   ret = nc->expr()->type();
2889
2890   this->seen_ = false;
2891
2892   return ret;
2893 }
2894
2895 // Set the type of the const reference.
2896
2897 void
2898 Const_expression::do_determine_type(const Type_context* context)
2899 {
2900   Type* ctype = this->constant_->const_value()->type();
2901   Type* cetype = (ctype != NULL
2902                   ? ctype
2903                   : this->constant_->const_value()->expr()->type());
2904   if (ctype != NULL && !ctype->is_abstract())
2905     ;
2906   else if (context->type != NULL
2907            && (context->type->integer_type() != NULL
2908                || context->type->float_type() != NULL
2909                || context->type->complex_type() != NULL)
2910            && (cetype->integer_type() != NULL
2911                || cetype->float_type() != NULL
2912                || cetype->complex_type() != NULL))
2913     this->type_ = context->type;
2914   else if (context->type != NULL
2915            && context->type->is_string_type()
2916            && cetype->is_string_type())
2917     this->type_ = context->type;
2918   else if (context->type != NULL
2919            && context->type->is_boolean_type()
2920            && cetype->is_boolean_type())
2921     this->type_ = context->type;
2922   else if (!context->may_be_abstract)
2923     {
2924       if (cetype->is_abstract())
2925         cetype = cetype->make_non_abstract_type();
2926       this->type_ = cetype;
2927     }
2928 }
2929
2930 // Check for a loop in which the initializer of a constant refers to
2931 // the constant itself.
2932
2933 void
2934 Const_expression::check_for_init_loop()
2935 {
2936   if (this->type_ != NULL && this->type_->is_error())
2937     return;
2938
2939   if (this->seen_)
2940     {
2941       this->report_error(_("constant refers to itself"));
2942       this->type_ = Type::make_error_type();
2943       return;
2944     }
2945
2946   Expression* init = this->constant_->const_value()->expr();
2947   Find_named_object find_named_object(this->constant_);
2948
2949   this->seen_ = true;
2950   Expression::traverse(&init, &find_named_object);
2951   this->seen_ = false;
2952
2953   if (find_named_object.found())
2954     {
2955       if (this->type_ == NULL || !this->type_->is_error())
2956         {
2957           this->report_error(_("constant refers to itself"));
2958           this->type_ = Type::make_error_type();
2959         }
2960       return;
2961     }
2962 }
2963
2964 // Check types of a const reference.
2965
2966 void
2967 Const_expression::do_check_types(Gogo*)
2968 {
2969   if (this->type_ != NULL && this->type_->is_error())
2970     return;
2971
2972   this->check_for_init_loop();
2973
2974   if (this->type_ == NULL || this->type_->is_abstract())
2975     return;
2976
2977   // Check for integer overflow.
2978   if (this->type_->integer_type() != NULL)
2979     {
2980       mpz_t ival;
2981       mpz_init(ival);
2982       Type* dummy;
2983       if (!this->integer_constant_value(true, ival, &dummy))
2984         {
2985           mpfr_t fval;
2986           mpfr_init(fval);
2987           Expression* cexpr = this->constant_->const_value()->expr();
2988           if (cexpr->float_constant_value(fval, &dummy))
2989             {
2990               if (!mpfr_integer_p(fval))
2991                 this->report_error(_("floating point constant "
2992                                      "truncated to integer"));
2993               else
2994                 {
2995                   mpfr_get_z(ival, fval, GMP_RNDN);
2996                   Integer_expression::check_constant(ival, this->type_,
2997                                                      this->location());
2998                 }
2999             }
3000           mpfr_clear(fval);
3001         }
3002       mpz_clear(ival);
3003     }
3004 }
3005
3006 // Return a tree for the const reference.
3007
3008 tree
3009 Const_expression::do_get_tree(Translate_context* context)
3010 {
3011   Gogo* gogo = context->gogo();
3012   tree type_tree;
3013   if (this->type_ == NULL)
3014     type_tree = NULL_TREE;
3015   else
3016     {
3017       type_tree = type_to_tree(this->type_->get_backend(gogo));
3018       if (type_tree == error_mark_node)
3019         return error_mark_node;
3020     }
3021
3022   // If the type has been set for this expression, but the underlying
3023   // object is an abstract int or float, we try to get the abstract
3024   // value.  Otherwise we may lose something in the conversion.
3025   if (this->type_ != NULL
3026       && (this->constant_->const_value()->type() == NULL
3027           || this->constant_->const_value()->type()->is_abstract()))
3028     {
3029       Expression* expr = this->constant_->const_value()->expr();
3030       mpz_t ival;
3031       mpz_init(ival);
3032       Type* t;
3033       if (expr->integer_constant_value(true, ival, &t))
3034         {
3035           tree ret = Expression::integer_constant_tree(ival, type_tree);
3036           mpz_clear(ival);
3037           return ret;
3038         }
3039       mpz_clear(ival);
3040
3041       mpfr_t fval;
3042       mpfr_init(fval);
3043       if (expr->float_constant_value(fval, &t))
3044         {
3045           tree ret = Expression::float_constant_tree(fval, type_tree);
3046           mpfr_clear(fval);
3047           return ret;
3048         }
3049
3050       mpfr_t imag;
3051       mpfr_init(imag);
3052       if (expr->complex_constant_value(fval, imag, &t))
3053         {
3054           tree ret = Expression::complex_constant_tree(fval, imag, type_tree);
3055           mpfr_clear(fval);
3056           mpfr_clear(imag);
3057           return ret;
3058         }
3059       mpfr_clear(imag);
3060       mpfr_clear(fval);
3061     }
3062
3063   tree const_tree = this->constant_->get_tree(gogo, context->function());
3064   if (this->type_ == NULL
3065       || const_tree == error_mark_node
3066       || TREE_TYPE(const_tree) == error_mark_node)
3067     return const_tree;
3068
3069   tree ret;
3070   if (TYPE_MAIN_VARIANT(type_tree) == TYPE_MAIN_VARIANT(TREE_TYPE(const_tree)))
3071     ret = fold_convert(type_tree, const_tree);
3072   else if (TREE_CODE(type_tree) == INTEGER_TYPE)
3073     ret = fold(convert_to_integer(type_tree, const_tree));
3074   else if (TREE_CODE(type_tree) == REAL_TYPE)
3075     ret = fold(convert_to_real(type_tree, const_tree));
3076   else if (TREE_CODE(type_tree) == COMPLEX_TYPE)
3077     ret = fold(convert_to_complex(type_tree, const_tree));
3078   else
3079     go_unreachable();
3080   return ret;
3081 }
3082
3083 // Dump ast representation for constant expression.
3084
3085 void
3086 Const_expression::do_dump_expression(Ast_dump_context* ast_dump_context) const
3087 {
3088   ast_dump_context->ostream() << this->constant_->name();
3089 }
3090
3091 // Make a reference to a constant in an expression.
3092
3093 Expression*
3094 Expression::make_const_reference(Named_object* constant,
3095                                  Location location)
3096 {
3097   return new Const_expression(constant, location);
3098 }
3099
3100 // Find a named object in an expression.
3101
3102 int
3103 Find_named_object::expression(Expression** pexpr)
3104 {
3105   switch ((*pexpr)->classification())
3106     {
3107     case Expression::EXPRESSION_CONST_REFERENCE:
3108       {
3109         Const_expression* ce = static_cast<Const_expression*>(*pexpr);
3110         if (ce->named_object() == this->no_)
3111           break;
3112
3113         // We need to check a constant initializer explicitly, as
3114         // loops here will not be caught by the loop checking for
3115         // variable initializers.
3116         ce->check_for_init_loop();
3117
3118         return TRAVERSE_CONTINUE;
3119       }
3120
3121     case Expression::EXPRESSION_VAR_REFERENCE:
3122       if ((*pexpr)->var_expression()->named_object() == this->no_)
3123         break;
3124       return TRAVERSE_CONTINUE;
3125     case Expression::EXPRESSION_FUNC_REFERENCE:
3126       if ((*pexpr)->func_expression()->named_object() == this->no_)
3127         break;
3128       return TRAVERSE_CONTINUE;
3129     default:
3130       return TRAVERSE_CONTINUE;
3131     }
3132   this->found_ = true;
3133   return TRAVERSE_EXIT;
3134 }
3135
3136 // The nil value.
3137
3138 class Nil_expression : public Expression
3139 {
3140  public:
3141   Nil_expression(Location location)
3142     : Expression(EXPRESSION_NIL, location)
3143   { }
3144
3145   static Expression*
3146   do_import(Import*);
3147
3148  protected:
3149   bool
3150   do_is_constant() const
3151   { return true; }
3152
3153   Type*
3154   do_type()
3155   { return Type::make_nil_type(); }
3156
3157   void
3158   do_determine_type(const Type_context*)
3159   { }
3160
3161   Expression*
3162   do_copy()
3163   { return this; }
3164
3165   tree
3166   do_get_tree(Translate_context*)
3167   { return null_pointer_node; }
3168
3169   void
3170   do_export(Export* exp) const
3171   { exp->write_c_string("nil"); }
3172
3173   void
3174   do_dump_expression(Ast_dump_context* ast_dump_context) const
3175   { ast_dump_context->ostream() << "nil"; }
3176 };
3177
3178 // Import a nil expression.
3179
3180 Expression*
3181 Nil_expression::do_import(Import* imp)
3182 {
3183   imp->require_c_string("nil");
3184   return Expression::make_nil(imp->location());
3185 }
3186
3187 // Make a nil expression.
3188
3189 Expression*
3190 Expression::make_nil(Location location)
3191 {
3192   return new Nil_expression(location);
3193 }
3194
3195 // The value of the predeclared constant iota.  This is little more
3196 // than a marker.  This will be lowered to an integer in
3197 // Const_expression::do_lower, which is where we know the value that
3198 // it should have.
3199
3200 class Iota_expression : public Parser_expression
3201 {
3202  public:
3203   Iota_expression(Location location)
3204     : Parser_expression(EXPRESSION_IOTA, location)
3205   { }
3206
3207  protected:
3208   Expression*
3209   do_lower(Gogo*, Named_object*, Statement_inserter*, int)
3210   { go_unreachable(); }
3211
3212   // There should only ever be one of these.
3213   Expression*
3214   do_copy()
3215   { go_unreachable(); }
3216
3217   void
3218   do_dump_expression(Ast_dump_context* ast_dump_context) const
3219   { ast_dump_context->ostream() << "iota"; }
3220 };
3221
3222 // Make an iota expression.  This is only called for one case: the
3223 // value of the predeclared constant iota.
3224
3225 Expression*
3226 Expression::make_iota()
3227 {
3228   static Iota_expression iota_expression(Linemap::unknown_location());
3229   return &iota_expression;
3230 }
3231
3232 // A type conversion expression.
3233
3234 class Type_conversion_expression : public Expression
3235 {
3236  public:
3237   Type_conversion_expression(Type* type, Expression* expr,
3238                              Location location)
3239     : Expression(EXPRESSION_CONVERSION, location),
3240       type_(type), expr_(expr), may_convert_function_types_(false)
3241   { }
3242
3243   // Return the type to which we are converting.
3244   Type*
3245   type() const
3246   { return this->type_; }
3247
3248   // Return the expression which we are converting.
3249   Expression*
3250   expr() const
3251   { return this->expr_; }
3252
3253   // Permit converting from one function type to another.  This is
3254   // used internally for method expressions.
3255   void
3256   set_may_convert_function_types()
3257   {
3258     this->may_convert_function_types_ = true;
3259   }
3260
3261   // Import a type conversion expression.
3262   static Expression*
3263   do_import(Import*);
3264
3265  protected:
3266   int
3267   do_traverse(Traverse* traverse);
3268
3269   Expression*
3270   do_lower(Gogo*, Named_object*, Statement_inserter*, int);
3271
3272   bool
3273   do_is_constant() const
3274   { return this->expr_->is_constant(); }
3275
3276   bool
3277   do_integer_constant_value(bool, mpz_t, Type**) const;
3278
3279   bool
3280   do_float_constant_value(mpfr_t, Type**) const;
3281
3282   bool
3283   do_complex_constant_value(mpfr_t, mpfr_t, Type**) const;
3284
3285   bool
3286   do_string_constant_value(std::string*) const;
3287
3288   Type*
3289   do_type()
3290   { return this->type_; }
3291
3292   void
3293   do_determine_type(const Type_context*)
3294   {
3295     Type_context subcontext(this->type_, false);
3296     this->expr_->determine_type(&subcontext);
3297   }
3298
3299   void
3300   do_check_types(Gogo*);
3301
3302   Expression*
3303   do_copy()
3304   {
3305     return new Type_conversion_expression(this->type_, this->expr_->copy(),
3306                                           this->location());
3307   }
3308
3309   tree
3310   do_get_tree(Translate_context* context);
3311
3312   void
3313   do_export(Export*) const;
3314
3315   void
3316   do_dump_expression(Ast_dump_context*) const;
3317
3318  private:
3319   // The type to convert to.
3320   Type* type_;
3321   // The expression to convert.
3322   Expression* expr_;
3323   // True if this is permitted to convert function types.  This is
3324   // used internally for method expressions.
3325   bool may_convert_function_types_;
3326 };
3327
3328 // Traversal.
3329
3330 int
3331 Type_conversion_expression::do_traverse(Traverse* traverse)
3332 {
3333   if (Expression::traverse(&this->expr_, traverse) == TRAVERSE_EXIT
3334       || Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
3335     return TRAVERSE_EXIT;
3336   return TRAVERSE_CONTINUE;
3337 }
3338
3339 // Convert to a constant at lowering time.
3340
3341 Expression*
3342 Type_conversion_expression::do_lower(Gogo*, Named_object*,
3343                                      Statement_inserter*, int)
3344 {
3345   Type* type = this->type_;
3346   Expression* val = this->expr_;
3347   Location location = this->location();
3348
3349   if (type->integer_type() != NULL)
3350     {
3351       mpz_t ival;
3352       mpz_init(ival);
3353       Type* dummy;
3354       if (val->integer_constant_value(false, ival, &dummy))
3355         {
3356           if (!Integer_expression::check_constant(ival, type, location))
3357             mpz_set_ui(ival, 0);
3358           Expression* ret = Expression::make_integer(&ival, type, location);
3359           mpz_clear(ival);
3360           return ret;
3361         }
3362
3363       mpfr_t fval;
3364       mpfr_init(fval);
3365       if (val->float_constant_value(fval, &dummy))
3366         {
3367           if (!mpfr_integer_p(fval))
3368             {
3369               error_at(location,
3370                        "floating point constant truncated to integer");
3371               return Expression::make_error(location);
3372             }
3373           mpfr_get_z(ival, fval, GMP_RNDN);
3374           if (!Integer_expression::check_constant(ival, type, location))
3375             mpz_set_ui(ival, 0);
3376           Expression* ret = Expression::make_integer(&ival, type, location);
3377           mpfr_clear(fval);
3378           mpz_clear(ival);
3379           return ret;
3380         }
3381       mpfr_clear(fval);
3382       mpz_clear(ival);
3383     }
3384
3385   if (type->float_type() != NULL)
3386     {
3387       mpfr_t fval;
3388       mpfr_init(fval);
3389       Type* dummy;
3390       if (val->float_constant_value(fval, &dummy))
3391         {
3392           if (!Float_expression::check_constant(fval, type, location))
3393             mpfr_set_ui(fval, 0, GMP_RNDN);
3394           Float_expression::constrain_float(fval, type);
3395           Expression *ret = Expression::make_float(&fval, type, location);
3396           mpfr_clear(fval);
3397           return ret;
3398         }
3399       mpfr_clear(fval);
3400     }
3401
3402   if (type->complex_type() != NULL)
3403     {
3404       mpfr_t real;
3405       mpfr_t imag;
3406       mpfr_init(real);
3407       mpfr_init(imag);
3408       Type* dummy;
3409       if (val->complex_constant_value(real, imag, &dummy))
3410         {
3411           if (!Complex_expression::check_constant(real, imag, type, location))
3412             {
3413               mpfr_set_ui(real, 0, GMP_RNDN);
3414               mpfr_set_ui(imag, 0, GMP_RNDN);
3415             }
3416           Complex_expression::constrain_complex(real, imag, type);
3417           Expression* ret = Expression::make_complex(&real, &imag, type,
3418                                                      location);
3419           mpfr_clear(real);
3420           mpfr_clear(imag);
3421           return ret;
3422         }
3423       mpfr_clear(real);
3424       mpfr_clear(imag);
3425     }
3426
3427   if (type->is_slice_type())
3428     {
3429       Type* element_type = type->array_type()->element_type()->forwarded();
3430       bool is_byte = (element_type->integer_type() != NULL
3431                       && element_type->integer_type()->is_byte());
3432       bool is_rune = (element_type->integer_type() != NULL
3433                       && element_type->integer_type()->is_rune());
3434       if (is_byte || is_rune)
3435         {
3436           std::string s;
3437           if (val->string_constant_value(&s))
3438             {
3439               Expression_list* vals = new Expression_list();
3440               if (is_byte)
3441                 {
3442                   for (std::string::const_iterator p = s.begin();
3443                        p != s.end();
3444                        p++)
3445                     {
3446                       mpz_t val;
3447                       mpz_init_set_ui(val, static_cast<unsigned char>(*p));
3448                       Expression* v = Expression::make_integer(&val,
3449                                                                element_type,
3450                                                                location);
3451                       vals->push_back(v);
3452                       mpz_clear(val);
3453                     }
3454                 }
3455               else
3456                 {
3457                   const char *p = s.data();
3458                   const char *pend = s.data() + s.length();
3459                   while (p < pend)
3460                     {
3461                       unsigned int c;
3462                       int adv = Lex::fetch_char(p, &c);
3463                       if (adv == 0)
3464                         {
3465                           warning_at(this->location(), 0,
3466                                      "invalid UTF-8 encoding");
3467                           adv = 1;
3468                         }
3469                       p += adv;
3470                       mpz_t val;
3471                       mpz_init_set_ui(val, c);
3472                       Expression* v = Expression::make_integer(&val,
3473                                                                element_type,
3474                                                                location);
3475                       vals->push_back(v);
3476                       mpz_clear(val);
3477                     }
3478                 }
3479
3480               return Expression::make_slice_composite_literal(type, vals,
3481                                                               location);
3482             }
3483         }
3484     }
3485
3486   return this;
3487 }
3488
3489 // Return the constant integer value if there is one.
3490
3491 bool
3492 Type_conversion_expression::do_integer_constant_value(bool iota_is_constant,
3493                                                       mpz_t val,
3494                                                       Type** ptype) const
3495 {
3496   if (this->type_->integer_type() == NULL)
3497     return false;
3498
3499   mpz_t ival;
3500   mpz_init(ival);
3501   Type* dummy;
3502   if (this->expr_->integer_constant_value(iota_is_constant, ival, &dummy))
3503     {
3504       if (!Integer_expression::check_constant(ival, this->type_,
3505                                               this->location()))
3506         {
3507           mpz_clear(ival);
3508           return false;
3509         }
3510       mpz_set(val, ival);
3511       mpz_clear(ival);
3512       *ptype = this->type_;
3513       return true;
3514     }
3515   mpz_clear(ival);
3516
3517   mpfr_t fval;
3518   mpfr_init(fval);
3519   if (this->expr_->float_constant_value(fval, &dummy))
3520     {
3521       mpfr_get_z(val, fval, GMP_RNDN);
3522       mpfr_clear(fval);
3523       if (!Integer_expression::check_constant(val, this->type_,
3524                                               this->location()))
3525         return false;
3526       *ptype = this->type_;
3527       return true;
3528     }
3529   mpfr_clear(fval);
3530
3531   return false;
3532 }
3533
3534 // Return the constant floating point value if there is one.
3535
3536 bool
3537 Type_conversion_expression::do_float_constant_value(mpfr_t val,
3538                                                     Type** ptype) const
3539 {
3540   if (this->type_->float_type() == NULL)
3541     return false;
3542
3543   mpfr_t fval;
3544   mpfr_init(fval);
3545   Type* dummy;
3546   if (this->expr_->float_constant_value(fval, &dummy))
3547     {
3548       if (!Float_expression::check_constant(fval, this->type_,
3549                                             this->location()))
3550         {
3551           mpfr_clear(fval);
3552           return false;
3553         }
3554       mpfr_set(val, fval, GMP_RNDN);
3555       mpfr_clear(fval);
3556       Float_expression::constrain_float(val, this->type_);
3557       *ptype = this->type_;
3558       return true;
3559     }
3560   mpfr_clear(fval);
3561
3562   return false;
3563 }
3564
3565 // Return the constant complex value if there is one.
3566
3567 bool
3568 Type_conversion_expression::do_complex_constant_value(mpfr_t real,
3569                                                       mpfr_t imag,
3570                                                       Type **ptype) const
3571 {
3572   if (this->type_->complex_type() == NULL)
3573     return false;
3574
3575   mpfr_t rval;
3576   mpfr_t ival;
3577   mpfr_init(rval);
3578   mpfr_init(ival);
3579   Type* dummy;
3580   if (this->expr_->complex_constant_value(rval, ival, &dummy))
3581     {
3582       if (!Complex_expression::check_constant(rval, ival, this->type_,
3583                                               this->location()))
3584         {
3585           mpfr_clear(rval);
3586           mpfr_clear(ival);
3587           return false;
3588         }
3589       mpfr_set(real, rval, GMP_RNDN);
3590       mpfr_set(imag, ival, GMP_RNDN);
3591       mpfr_clear(rval);
3592       mpfr_clear(ival);
3593       Complex_expression::constrain_complex(real, imag, this->type_);
3594       *ptype = this->type_;
3595       return true;
3596     }
3597   mpfr_clear(rval);
3598   mpfr_clear(ival);
3599
3600   return false;
3601 }
3602
3603 // Return the constant string value if there is one.
3604
3605 bool
3606 Type_conversion_expression::do_string_constant_value(std::string* val) const
3607 {
3608   if (this->type_->is_string_type()
3609       && this->expr_->type()->integer_type() != NULL)
3610     {
3611       mpz_t ival;
3612       mpz_init(ival);
3613       Type* dummy;
3614       if (this->expr_->integer_constant_value(false, ival, &dummy))
3615         {
3616           unsigned long ulval = mpz_get_ui(ival);
3617           if (mpz_cmp_ui(ival, ulval) == 0)
3618             {
3619               Lex::append_char(ulval, true, val, this->location());
3620               mpz_clear(ival);
3621               return true;
3622             }
3623         }
3624       mpz_clear(ival);
3625     }
3626
3627   // FIXME: Could handle conversion from const []int here.
3628
3629   return false;
3630 }
3631
3632 // Check that types are convertible.
3633
3634 void
3635 Type_conversion_expression::do_check_types(Gogo*)
3636 {
3637   Type* type = this->type_;
3638   Type* expr_type = this->expr_->type();
3639   std::string reason;
3640
3641   if (type->is_error() || expr_type->is_error())
3642     {
3643       this->set_is_error();
3644       return;
3645     }
3646
3647   if (this->may_convert_function_types_
3648       && type->function_type() != NULL
3649       && expr_type->function_type() != NULL)
3650     return;
3651
3652   if (Type::are_convertible(type, expr_type, &reason))
3653     return;
3654
3655   error_at(this->location(), "%s", reason.c_str());
3656   this->set_is_error();
3657 }
3658
3659 // Get a tree for a type conversion.
3660
3661 tree
3662 Type_conversion_expression::do_get_tree(Translate_context* context)
3663 {
3664   Gogo* gogo = context->gogo();
3665   tree type_tree = type_to_tree(this->type_->get_backend(gogo));
3666   tree expr_tree = this->expr_->get_tree(context);
3667
3668   if (type_tree == error_mark_node
3669       || expr_tree == error_mark_node
3670       || TREE_TYPE(expr_tree) == error_mark_node)
3671     return error_mark_node;
3672
3673   if (TYPE_MAIN_VARIANT(type_tree) == TYPE_MAIN_VARIANT(TREE_TYPE(expr_tree)))
3674     return fold_convert(type_tree, expr_tree);
3675
3676   Type* type = this->type_;
3677   Type* expr_type = this->expr_->type();
3678   tree ret;
3679   if (type->interface_type() != NULL || expr_type->interface_type() != NULL)
3680     ret = Expression::convert_for_assignment(context, type, expr_type,
3681                                              expr_tree, this->location());
3682   else if (type->integer_type() != NULL)
3683     {
3684       if (expr_type->integer_type() != NULL
3685           || expr_type->float_type() != NULL
3686           || expr_type->is_unsafe_pointer_type())
3687         ret = fold(convert_to_integer(type_tree, expr_tree));
3688       else
3689         go_unreachable();
3690     }
3691   else if (type->float_type() != NULL)
3692     {
3693       if (expr_type->integer_type() != NULL
3694           || expr_type->float_type() != NULL)
3695         ret = fold(convert_to_real(type_tree, expr_tree));
3696       else
3697         go_unreachable();
3698     }
3699   else if (type->complex_type() != NULL)
3700     {
3701       if (expr_type->complex_type() != NULL)
3702         ret = fold(convert_to_complex(type_tree, expr_tree));
3703       else
3704         go_unreachable();
3705     }
3706   else if (type->is_string_type()
3707            && expr_type->integer_type() != NULL)
3708     {
3709       expr_tree = fold_convert(integer_type_node, expr_tree);
3710       if (host_integerp(expr_tree, 0))
3711         {
3712           HOST_WIDE_INT intval = tree_low_cst(expr_tree, 0);
3713           std::string s;
3714           Lex::append_char(intval, true, &s, this->location());
3715           Expression* se = Expression::make_string(s, this->location());
3716           return se->get_tree(context);
3717         }
3718
3719       static tree int_to_string_fndecl;
3720       ret = Gogo::call_builtin(&int_to_string_fndecl,
3721                                this->location(),
3722                                "__go_int_to_string",
3723                                1,
3724                                type_tree,
3725                                integer_type_node,
3726                                fold_convert(integer_type_node, expr_tree));
3727     }
3728   else if (type->is_string_type() && expr_type->is_slice_type())
3729     {
3730       if (!DECL_P(expr_tree))
3731         expr_tree = save_expr(expr_tree);
3732       Array_type* a = expr_type->array_type();
3733       Type* e = a->element_type()->forwarded();
3734       go_assert(e->integer_type() != NULL);
3735       tree valptr = fold_convert(const_ptr_type_node,
3736                                  a->value_pointer_tree(gogo, expr_tree));
3737       tree len = a->length_tree(gogo, expr_tree);
3738       len = fold_convert_loc(this->location().gcc_location(), integer_type_node,
3739                              len);
3740       if (e->integer_type()->is_byte())
3741         {
3742           static tree byte_array_to_string_fndecl;
3743           ret = Gogo::call_builtin(&byte_array_to_string_fndecl,
3744                                    this->location(),
3745                                    "__go_byte_array_to_string",
3746                                    2,
3747                                    type_tree,
3748                                    const_ptr_type_node,
3749                                    valptr,
3750                                    integer_type_node,
3751                                    len);
3752         }
3753       else
3754         {
3755           go_assert(e->integer_type()->is_rune());
3756           static tree int_array_to_string_fndecl;
3757           ret = Gogo::call_builtin(&int_array_to_string_fndecl,
3758                                    this->location(),
3759                                    "__go_int_array_to_string",
3760                                    2,
3761                                    type_tree,
3762                                    const_ptr_type_node,
3763                                    valptr,
3764                                    integer_type_node,
3765                                    len);
3766         }
3767     }
3768   else if (type->is_slice_type() && expr_type->is_string_type())
3769     {
3770       Type* e = type->array_type()->element_type()->forwarded();
3771       go_assert(e->integer_type() != NULL);
3772       if (e->integer_type()->is_byte())
3773         {
3774           tree string_to_byte_array_fndecl = NULL_TREE;
3775           ret = Gogo::call_builtin(&string_to_byte_array_fndecl,
3776                                    this->location(),
3777                                    "__go_string_to_byte_array",
3778                                    1,
3779                                    type_tree,
3780                                    TREE_TYPE(expr_tree),
3781                                    expr_tree);
3782         }
3783       else
3784         {
3785           go_assert(e->integer_type()->is_rune());
3786           tree string_to_int_array_fndecl = NULL_TREE;
3787           ret = Gogo::call_builtin(&string_to_int_array_fndecl,
3788                                    this->location(),
3789                                    "__go_string_to_int_array",
3790                                    1,
3791                                    type_tree,
3792                                    TREE_TYPE(expr_tree),
3793                                    expr_tree);
3794         }
3795     }
3796   else if ((type->is_unsafe_pointer_type()
3797             && expr_type->points_to() != NULL)
3798            || (expr_type->is_unsafe_pointer_type()
3799                && type->points_to() != NULL))
3800     ret = fold_convert(type_tree, expr_tree);
3801   else if (type->is_unsafe_pointer_type()
3802            && expr_type->integer_type() != NULL)
3803     ret = convert_to_pointer(type_tree, expr_tree);
3804   else if (this->may_convert_function_types_
3805            && type->function_type() != NULL
3806            && expr_type->function_type() != NULL)
3807     ret = fold_convert_loc(this->location().gcc_location(), type_tree,
3808                            expr_tree);
3809   else
3810     ret = Expression::convert_for_assignment(context, type, expr_type,
3811                                              expr_tree, this->location());
3812
3813   return ret;
3814 }
3815
3816 // Output a type conversion in a constant expression.
3817
3818 void
3819 Type_conversion_expression::do_export(Export* exp) const
3820 {
3821   exp->write_c_string("convert(");
3822   exp->write_type(this->type_);
3823   exp->write_c_string(", ");
3824   this->expr_->export_expression(exp);
3825   exp->write_c_string(")");
3826 }
3827
3828 // Import a type conversion or a struct construction.
3829
3830 Expression*
3831 Type_conversion_expression::do_import(Import* imp)
3832 {
3833   imp->require_c_string("convert(");
3834   Type* type = imp->read_type();
3835   imp->require_c_string(", ");
3836   Expression* val = Expression::import_expression(imp);
3837   imp->require_c_string(")");
3838   return Expression::make_cast(type, val, imp->location());
3839 }
3840
3841 // Dump ast representation for a type conversion expression.
3842
3843 void
3844 Type_conversion_expression::do_dump_expression(
3845     Ast_dump_context* ast_dump_context) const
3846 {
3847   ast_dump_context->dump_type(this->type_);
3848   ast_dump_context->ostream() << "(";
3849   ast_dump_context->dump_expression(this->expr_);
3850   ast_dump_context->ostream() << ") ";
3851 }
3852
3853 // Make a type cast expression.
3854
3855 Expression*
3856 Expression::make_cast(Type* type, Expression* val, Location location)
3857 {
3858   if (type->is_error_type() || val->is_error_expression())
3859     return Expression::make_error(location);
3860   return new Type_conversion_expression(type, val, location);
3861 }
3862
3863 // An unsafe type conversion, used to pass values to builtin functions.
3864
3865 class Unsafe_type_conversion_expression : public Expression
3866 {
3867  public:
3868   Unsafe_type_conversion_expression(Type* type, Expression* expr,
3869                                     Location location)
3870     : Expression(EXPRESSION_UNSAFE_CONVERSION, location),
3871       type_(type), expr_(expr)
3872   { }
3873
3874  protected:
3875   int
3876   do_traverse(Traverse* traverse);
3877
3878   Type*
3879   do_type()
3880   { return this->type_; }
3881
3882   void
3883   do_determine_type(const Type_context*)
3884   { this->expr_->determine_type_no_context(); }
3885
3886   Expression*
3887   do_copy()
3888   {
3889     return new Unsafe_type_conversion_expression(this->type_,
3890                                                  this->expr_->copy(),
3891                                                  this->location());
3892   }
3893
3894   tree
3895   do_get_tree(Translate_context*);
3896
3897   void
3898   do_dump_expression(Ast_dump_context*) const;
3899
3900  private:
3901   // The type to convert to.
3902   Type* type_;
3903   // The expression to convert.
3904   Expression* expr_;
3905 };
3906
3907 // Traversal.
3908
3909 int
3910 Unsafe_type_conversion_expression::do_traverse(Traverse* traverse)
3911 {
3912   if (Expression::traverse(&this->expr_, traverse) == TRAVERSE_EXIT
3913       || Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
3914     return TRAVERSE_EXIT;
3915   return TRAVERSE_CONTINUE;
3916 }
3917
3918 // Convert to backend representation.
3919
3920 tree
3921 Unsafe_type_conversion_expression::do_get_tree(Translate_context* context)
3922 {
3923   // We are only called for a limited number of cases.
3924
3925   Type* t = this->type_;
3926   Type* et = this->expr_->type();
3927
3928   tree type_tree = type_to_tree(this->type_->get_backend(context->gogo()));
3929   tree expr_tree = this->expr_->get_tree(context);
3930   if (type_tree == error_mark_node || expr_tree == error_mark_node)
3931     return error_mark_node;
3932
3933   Location loc = this->location();
3934
3935   bool use_view_convert = false;
3936   if (t->is_slice_type())
3937     {
3938       go_assert(et->is_slice_type());
3939       use_view_convert = true;
3940     }
3941   else if (t->map_type() != NULL)
3942     go_assert(et->map_type() != NULL);
3943   else if (t->channel_type() != NULL)
3944     go_assert(et->channel_type() != NULL);
3945   else if (t->points_to() != NULL && t->points_to()->channel_type() != NULL)
3946     go_assert((et->points_to() != NULL
3947                 && et->points_to()->channel_type() != NULL)
3948                || et->is_nil_type());
3949   else if (t->points_to() != NULL)
3950     go_assert(et->points_to() != NULL || et->is_nil_type());
3951   else if (et->is_unsafe_pointer_type())
3952     go_assert(t->points_to() != NULL);
3953   else if (t->interface_type() != NULL && !t->interface_type()->is_empty())
3954     {
3955       go_assert(et->interface_type() != NULL
3956                  && !et->interface_type()->is_empty());
3957       use_view_convert = true;
3958     }
3959   else if (t->interface_type() != NULL && t->interface_type()->is_empty())
3960     {
3961       go_assert(et->interface_type() != NULL
3962                  && et->interface_type()->is_empty());
3963       use_view_convert = true;
3964     }
3965   else if (t->integer_type() != NULL)
3966     {
3967       go_assert(et->is_boolean_type()
3968                  || et->integer_type() != NULL
3969                  || et->function_type() != NULL
3970                  || et->points_to() != NULL
3971                  || et->map_type() != NULL
3972                  || et->channel_type() != NULL);
3973       return convert_to_integer(type_tree, expr_tree);
3974     }
3975   else
3976     go_unreachable();
3977
3978   if (use_view_convert)
3979     return fold_build1_loc(loc.gcc_location(), VIEW_CONVERT_EXPR, type_tree,
3980                            expr_tree);
3981   else
3982     return fold_convert_loc(loc.gcc_location(), type_tree, expr_tree);
3983 }
3984
3985 // Dump ast representation for an unsafe type conversion expression.
3986
3987 void
3988 Unsafe_type_conversion_expression::do_dump_expression(
3989     Ast_dump_context* ast_dump_context) const
3990 {
3991   ast_dump_context->dump_type(this->type_);
3992   ast_dump_context->ostream() << "(";
3993   ast_dump_context->dump_expression(this->expr_);
3994   ast_dump_context->ostream() << ") ";
3995 }
3996
3997 // Make an unsafe type conversion expression.
3998
3999 Expression*
4000 Expression::make_unsafe_cast(Type* type, Expression* expr,
4001                              Location location)
4002 {
4003   return new Unsafe_type_conversion_expression(type, expr, location);
4004 }
4005
4006 // Unary expressions.
4007
4008 class Unary_expression : public Expression
4009 {
4010  public:
4011   Unary_expression(Operator op, Expression* expr, Location location)
4012     : Expression(EXPRESSION_UNARY, location),
4013       op_(op), escapes_(true), create_temp_(false), expr_(expr)
4014   { }
4015
4016   // Return the operator.
4017   Operator
4018   op() const
4019   { return this->op_; }
4020
4021   // Return the operand.
4022   Expression*
4023   operand() const
4024   { return this->expr_; }
4025
4026   // Record that an address expression does not escape.
4027   void
4028   set_does_not_escape()
4029   {
4030     go_assert(this->op_ == OPERATOR_AND);
4031     this->escapes_ = false;
4032   }
4033
4034   // Record that this is an address expression which should create a
4035   // temporary variable if necessary.  This is used for method calls.
4036   void
4037   set_create_temp()
4038   {
4039     go_assert(this->op_ == OPERATOR_AND);
4040     this->create_temp_ = true;
4041   }
4042
4043   // Apply unary opcode OP to UVAL, setting VAL.  Return true if this
4044   // could be done, false if not.
4045   static bool
4046   eval_integer(Operator op, Type* utype, mpz_t uval, mpz_t val,
4047                Location);
4048
4049   // Apply unary opcode OP to UVAL, setting VAL.  Return true if this
4050   // could be done, false if not.
4051   static bool
4052   eval_float(Operator op, mpfr_t uval, mpfr_t val);
4053
4054   // Apply unary opcode OP to UREAL/UIMAG, setting REAL/IMAG.  Return
4055   // true if this could be done, false if not.
4056   static bool
4057   eval_complex(Operator op, mpfr_t ureal, mpfr_t uimag, mpfr_t real,
4058                mpfr_t imag);
4059
4060   static Expression*
4061   do_import(Import*);
4062
4063  protected:
4064   int
4065   do_traverse(Traverse* traverse)
4066   { return Expression::traverse(&this->expr_, traverse); }
4067
4068   Expression*
4069   do_lower(Gogo*, Named_object*, Statement_inserter*, int);
4070
4071   bool
4072   do_is_constant() const;
4073
4074   bool
4075   do_integer_constant_value(bool, mpz_t, Type**) const;
4076
4077   bool
4078   do_float_constant_value(mpfr_t, Type**) const;
4079
4080   bool
4081   do_complex_constant_value(mpfr_t, mpfr_t, Type**) const;
4082
4083   Type*
4084   do_type();
4085
4086   void
4087   do_determine_type(const Type_context*);
4088
4089   void
4090   do_check_types(Gogo*);
4091
4092   Expression*
4093   do_copy()
4094   {
4095     return Expression::make_unary(this->op_, this->expr_->copy(),
4096                                   this->location());
4097   }
4098
4099   bool
4100   do_must_eval_subexpressions_in_order(int*) const
4101   { return this->op_ == OPERATOR_MULT; }
4102
4103   bool
4104   do_is_addressable() const
4105   { return this->op_ == OPERATOR_MULT; }
4106
4107   tree
4108   do_get_tree(Translate_context*);
4109
4110   void
4111   do_export(Export*) const;
4112
4113   void
4114   do_dump_expression(Ast_dump_context*) const;
4115
4116  private:
4117   // The unary operator to apply.
4118   Operator op_;
4119   // Normally true.  False if this is an address expression which does
4120   // not escape the current function.
4121   bool escapes_;
4122   // True if this is an address expression which should create a
4123   // temporary variable if necessary.
4124   bool create_temp_;
4125   // The operand.
4126   Expression* expr_;
4127 };
4128
4129 // If we are taking the address of a composite literal, and the
4130 // contents are not constant, then we want to make a heap composite
4131 // instead.
4132
4133 Expression*
4134 Unary_expression::do_lower(Gogo*, Named_object*, Statement_inserter*, int)
4135 {
4136   Location loc = this->location();
4137   Operator op = this->op_;
4138   Expression* expr = this->expr_;
4139
4140   if (op == OPERATOR_MULT && expr->is_type_expression())
4141     return Expression::make_type(Type::make_pointer_type(expr->type()), loc);
4142
4143   // *&x simplifies to x.  *(*T)(unsafe.Pointer)(&x) does not require
4144   // moving x to the heap.  FIXME: Is it worth doing a real escape
4145   // analysis here?  This case is found in math/unsafe.go and is
4146   // therefore worth special casing.
4147   if (op == OPERATOR_MULT)
4148     {
4149       Expression* e = expr;
4150       while (e->classification() == EXPRESSION_CONVERSION)
4151         {
4152           Type_conversion_expression* te
4153             = static_cast<Type_conversion_expression*>(e);
4154           e = te->expr();
4155         }
4156
4157       if (e->classification() == EXPRESSION_UNARY)
4158         {
4159           Unary_expression* ue = static_cast<Unary_expression*>(e);
4160           if (ue->op_ == OPERATOR_AND)
4161             {
4162               if (e == expr)
4163                 {
4164                   // *&x == x.
4165                   return ue->expr_;
4166                 }
4167               ue->set_does_not_escape();
4168             }
4169         }
4170     }
4171
4172   // Catching an invalid indirection of unsafe.Pointer here avoid
4173   // having to deal with TYPE_VOID in other places.
4174   if (op == OPERATOR_MULT && expr->type()->is_unsafe_pointer_type())
4175     {
4176       error_at(this->location(), "invalid indirect of %<unsafe.Pointer%>");
4177       return Expression::make_error(this->location());
4178     }
4179
4180   if (op == OPERATOR_PLUS || op == OPERATOR_MINUS
4181       || op == OPERATOR_NOT || op == OPERATOR_XOR)
4182     {
4183       Expression* ret = NULL;
4184
4185       mpz_t eval;
4186       mpz_init(eval);
4187       Type* etype;
4188       if (expr->integer_constant_value(false, eval, &etype))
4189         {
4190           mpz_t val;
4191           mpz_init(val);
4192           if (Unary_expression::eval_integer(op, etype, eval, val, loc))
4193             ret = Expression::make_integer(&val, etype, loc);
4194           mpz_clear(val);
4195         }
4196       mpz_clear(eval);
4197       if (ret != NULL)
4198         return ret;
4199
4200       if (op == OPERATOR_PLUS || op == OPERATOR_MINUS)
4201         {
4202           mpfr_t fval;
4203           mpfr_init(fval);
4204           Type* ftype;
4205           if (expr->float_constant_value(fval, &ftype))
4206             {
4207               mpfr_t val;
4208               mpfr_init(val);
4209               if (Unary_expression::eval_float(op, fval, val))
4210                 ret = Expression::make_float(&val, ftype, loc);
4211               mpfr_clear(val);
4212             }
4213           if (ret != NULL)
4214             {
4215               mpfr_clear(fval);
4216               return ret;
4217             }
4218
4219           mpfr_t ival;
4220           mpfr_init(ival);
4221           if (expr->complex_constant_value(fval, ival, &ftype))
4222             {
4223               mpfr_t real;
4224               mpfr_t imag;
4225               mpfr_init(real);
4226               mpfr_init(imag);
4227               if (Unary_expression::eval_complex(op, fval, ival, real, imag))
4228                 ret = Expression::make_complex(&real, &imag, ftype, loc);
4229               mpfr_clear(real);
4230               mpfr_clear(imag);
4231             }
4232           mpfr_clear(ival);
4233           mpfr_clear(fval);
4234           if (ret != NULL)
4235             return ret;
4236         }
4237     }
4238
4239   return this;
4240 }
4241
4242 // Return whether a unary expression is a constant.
4243
4244 bool
4245 Unary_expression::do_is_constant() const
4246 {
4247   if (this->op_ == OPERATOR_MULT)
4248     {
4249       // Indirecting through a pointer is only constant if the object
4250       // to which the expression points is constant, but we currently
4251       // have no way to determine that.
4252       return false;
4253     }
4254   else if (this->op_ == OPERATOR_AND)
4255     {
4256       // Taking the address of a variable is constant if it is a
4257       // global variable, not constant otherwise.  In other cases
4258       // taking the address is probably not a constant.
4259       Var_expression* ve = this->expr_->var_expression();
4260       if (ve != NULL)
4261         {
4262           Named_object* no = ve->named_object();
4263           return no->is_variable() && no->var_value()->is_global();
4264         }
4265       return false;
4266     }
4267   else
4268     return this->expr_->is_constant();
4269 }
4270
4271 // Apply unary opcode OP to UVAL, setting VAL.  UTYPE is the type of
4272 // UVAL, if known; it may be NULL.  Return true if this could be done,
4273 // false if not.
4274
4275 bool
4276 Unary_expression::eval_integer(Operator op, Type* utype, mpz_t uval, mpz_t val,
4277                                Location location)
4278 {
4279   switch (op)
4280     {
4281     case OPERATOR_PLUS:
4282       mpz_set(val, uval);
4283       return true;
4284     case OPERATOR_MINUS:
4285       mpz_neg(val, uval);
4286       return Integer_expression::check_constant(val, utype, location);
4287     case OPERATOR_NOT:
4288       mpz_set_ui(val, mpz_cmp_si(uval, 0) == 0 ? 1 : 0);
4289       return true;
4290     case OPERATOR_XOR:
4291       if (utype == NULL
4292           || utype->integer_type() == NULL
4293           || utype->integer_type()->is_abstract())
4294         mpz_com(val, uval);
4295       else
4296         {
4297           // The number of HOST_WIDE_INTs that it takes to represent
4298           // UVAL.
4299           size_t count = ((mpz_sizeinbase(uval, 2)
4300                            + HOST_BITS_PER_WIDE_INT
4301                            - 1)
4302                           / HOST_BITS_PER_WIDE_INT);
4303
4304           unsigned HOST_WIDE_INT* phwi = new unsigned HOST_WIDE_INT[count];
4305           memset(phwi, 0, count * sizeof(HOST_WIDE_INT));
4306
4307           size_t ecount;
4308           mpz_export(phwi, &ecount, -1, sizeof(HOST_WIDE_INT), 0, 0, uval);
4309           go_assert(ecount <= count);
4310
4311           // Trim down to the number of words required by the type.
4312           size_t obits = utype->integer_type()->bits();
4313           if (!utype->integer_type()->is_unsigned())
4314             ++obits;
4315           size_t ocount = ((obits + HOST_BITS_PER_WIDE_INT - 1)
4316                            / HOST_BITS_PER_WIDE_INT);
4317           go_assert(ocount <= count);
4318
4319           for (size_t i = 0; i < ocount; ++i)
4320             phwi[i] = ~phwi[i];
4321
4322           size_t clearbits = ocount * HOST_BITS_PER_WIDE_INT - obits;
4323           if (clearbits != 0)
4324             phwi[ocount - 1] &= (((unsigned HOST_WIDE_INT) (HOST_WIDE_INT) -1)
4325                                  >> clearbits);
4326
4327           mpz_import(val, ocount, -1, sizeof(HOST_WIDE_INT), 0, 0, phwi);
4328
4329           delete[] phwi;
4330         }
4331       return Integer_expression::check_constant(val, utype, location);
4332     case OPERATOR_AND:
4333     case OPERATOR_MULT:
4334       return false;
4335     default:
4336       go_unreachable();
4337     }
4338 }
4339
4340 // Apply unary opcode OP to UVAL, setting VAL.  Return true if this
4341 // could be done, false if not.
4342
4343 bool
4344 Unary_expression::eval_float(Operator op, mpfr_t uval, mpfr_t val)
4345 {
4346   switch (op)
4347     {
4348     case OPERATOR_PLUS:
4349       mpfr_set(val, uval, GMP_RNDN);
4350       return true;
4351     case OPERATOR_MINUS:
4352       mpfr_neg(val, uval, GMP_RNDN);
4353       return true;
4354     case OPERATOR_NOT:
4355     case OPERATOR_XOR:
4356     case OPERATOR_AND:
4357     case OPERATOR_MULT:
4358       return false;
4359     default:
4360       go_unreachable();
4361     }
4362 }
4363
4364 // Apply unary opcode OP to RVAL/IVAL, setting REAL/IMAG.  Return true
4365 // if this could be done, false if not.
4366
4367 bool
4368 Unary_expression::eval_complex(Operator op, mpfr_t rval, mpfr_t ival,
4369                                mpfr_t real, mpfr_t imag)
4370 {
4371   switch (op)
4372     {
4373     case OPERATOR_PLUS:
4374       mpfr_set(real, rval, GMP_RNDN);
4375       mpfr_set(imag, ival, GMP_RNDN);
4376       return true;
4377     case OPERATOR_MINUS:
4378       mpfr_neg(real, rval, GMP_RNDN);
4379       mpfr_neg(imag, ival, GMP_RNDN);
4380       return true;
4381     case OPERATOR_NOT:
4382     case OPERATOR_XOR:
4383     case OPERATOR_AND:
4384     case OPERATOR_MULT:
4385       return false;
4386     default:
4387       go_unreachable();
4388     }
4389 }
4390
4391 // Return the integral constant value of a unary expression, if it has one.
4392
4393 bool
4394 Unary_expression::do_integer_constant_value(bool iota_is_constant, mpz_t val,
4395                                             Type** ptype) const
4396 {
4397   mpz_t uval;
4398   mpz_init(uval);
4399   bool ret;
4400   if (!this->expr_->integer_constant_value(iota_is_constant, uval, ptype))
4401     ret = false;
4402   else
4403     ret = Unary_expression::eval_integer(this->op_, *ptype, uval, val,
4404                                          this->location());
4405   mpz_clear(uval);
4406   return ret;
4407 }
4408
4409 // Return the floating point constant value of a unary expression, if
4410 // it has one.
4411
4412 bool
4413 Unary_expression::do_float_constant_value(mpfr_t val, Type** ptype) const
4414 {
4415   mpfr_t uval;
4416   mpfr_init(uval);
4417   bool ret;
4418   if (!this->expr_->float_constant_value(uval, ptype))
4419     ret = false;
4420   else
4421     ret = Unary_expression::eval_float(this->op_, uval, val);
4422   mpfr_clear(uval);
4423   return ret;
4424 }
4425
4426 // Return the complex constant value of a unary expression, if it has
4427 // one.
4428
4429 bool
4430 Unary_expression::do_complex_constant_value(mpfr_t real, mpfr_t imag,
4431                                             Type** ptype) const
4432 {
4433   mpfr_t rval;
4434   mpfr_t ival;
4435   mpfr_init(rval);
4436   mpfr_init(ival);
4437   bool ret;
4438   if (!this->expr_->complex_constant_value(rval, ival, ptype))
4439     ret = false;
4440   else
4441     ret = Unary_expression::eval_complex(this->op_, rval, ival, real, imag);
4442   mpfr_clear(rval);
4443   mpfr_clear(ival);
4444   return ret;
4445 }
4446
4447 // Return the type of a unary expression.
4448
4449 Type*
4450 Unary_expression::do_type()
4451 {
4452   switch (this->op_)
4453     {
4454     case OPERATOR_PLUS:
4455     case OPERATOR_MINUS:
4456     case OPERATOR_NOT:
4457     case OPERATOR_XOR:
4458       return this->expr_->type();
4459
4460     case OPERATOR_AND:
4461       return Type::make_pointer_type(this->expr_->type());
4462
4463     case OPERATOR_MULT:
4464       {
4465         Type* subtype = this->expr_->type();
4466         Type* points_to = subtype->points_to();
4467         if (points_to == NULL)
4468           return Type::make_error_type();
4469         return points_to;
4470       }
4471
4472     default:
4473       go_unreachable();
4474     }
4475 }
4476
4477 // Determine abstract types for a unary expression.
4478
4479 void
4480 Unary_expression::do_determine_type(const Type_context* context)
4481 {
4482   switch (this->op_)
4483     {
4484     case OPERATOR_PLUS:
4485     case OPERATOR_MINUS:
4486     case OPERATOR_NOT:
4487     case OPERATOR_XOR:
4488       this->expr_->determine_type(context);
4489       break;
4490
4491     case OPERATOR_AND:
4492       // Taking the address of something.
4493       {
4494         Type* subtype = (context->type == NULL
4495                          ? NULL
4496                          : context->type->points_to());
4497         Type_context subcontext(subtype, false);
4498         this->expr_->determine_type(&subcontext);
4499       }
4500       break;
4501
4502     case OPERATOR_MULT:
4503       // Indirecting through a pointer.
4504       {
4505         Type* subtype = (context->type == NULL
4506                          ? NULL
4507                          : Type::make_pointer_type(context->type));
4508         Type_context subcontext(subtype, false);
4509         this->expr_->determine_type(&subcontext);
4510       }
4511       break;
4512
4513     default:
4514       go_unreachable();
4515     }
4516 }
4517
4518 // Check types for a unary expression.
4519
4520 void
4521 Unary_expression::do_check_types(Gogo*)
4522 {
4523   Type* type = this->expr_->type();
4524   if (type->is_error())
4525     {
4526       this->set_is_error();
4527       return;
4528     }
4529
4530   switch (this->op_)
4531     {
4532     case OPERATOR_PLUS:
4533     case OPERATOR_MINUS:
4534       if (type->integer_type() == NULL
4535           && type->float_type() == NULL
4536           && type->complex_type() == NULL)
4537         this->report_error(_("expected numeric type"));
4538       break;
4539
4540     case OPERATOR_NOT:
4541     case OPERATOR_XOR:
4542       if (type->integer_type() == NULL
4543           && !type->is_boolean_type())
4544         this->report_error(_("expected integer or boolean type"));
4545       break;
4546
4547     case OPERATOR_AND:
4548       if (!this->expr_->is_addressable())
4549         {
4550           if (!this->create_temp_)
4551             this->report_error(_("invalid operand for unary %<&%>"));
4552         }
4553       else
4554         this->expr_->address_taken(this->escapes_);
4555       break;
4556
4557     case OPERATOR_MULT:
4558       // Indirecting through a pointer.
4559       if (type->points_to() == NULL)
4560         this->report_error(_("expected pointer"));
4561       break;
4562
4563     default:
4564       go_unreachable();
4565     }
4566 }
4567
4568 // Get a tree for a unary expression.
4569
4570 tree
4571 Unary_expression::do_get_tree(Translate_context* context)
4572 {
4573   Location loc = this->location();
4574
4575   // Taking the address of a set-and-use-temporary expression requires
4576   // setting the temporary and then taking the address.
4577   if (this->op_ == OPERATOR_AND)
4578     {
4579       Set_and_use_temporary_expression* sut =
4580         this->expr_->set_and_use_temporary_expression();
4581       if (sut != NULL)
4582         {
4583           Temporary_statement* temp = sut->temporary();
4584           Bvariable* bvar = temp->get_backend_variable(context);
4585           tree var_tree = var_to_tree(bvar);
4586           Expression* val = sut->expression();
4587           tree val_tree = val->get_tree(context);
4588           if (var_tree == error_mark_node || val_tree == error_mark_node)
4589             return error_mark_node;
4590           tree addr_tree = build_fold_addr_expr_loc(loc.gcc_location(),
4591                                                     var_tree);
4592           return build2_loc(loc.gcc_location(), COMPOUND_EXPR,
4593                             TREE_TYPE(addr_tree),
4594                             build2_loc(sut->location().gcc_location(),
4595                                        MODIFY_EXPR, void_type_node,
4596                                        var_tree, val_tree),
4597                             addr_tree);
4598         }
4599     }
4600
4601   tree expr = this->expr_->get_tree(context);
4602   if (expr == error_mark_node)
4603     return error_mark_node;
4604
4605   switch (this->op_)
4606     {
4607     case OPERATOR_PLUS:
4608       return expr;
4609
4610     case OPERATOR_MINUS:
4611       {
4612         tree type = TREE_TYPE(expr);
4613         tree compute_type = excess_precision_type(type);
4614         if (compute_type != NULL_TREE)
4615           expr = ::convert(compute_type, expr);
4616         tree ret = fold_build1_loc(loc.gcc_location(), NEGATE_EXPR,
4617                                    (compute_type != NULL_TREE
4618                                     ? compute_type
4619                                     : type),
4620                                    expr);
4621         if (compute_type != NULL_TREE)
4622           ret = ::convert(type, ret);
4623         return ret;
4624       }
4625
4626     case OPERATOR_NOT:
4627       if (TREE_CODE(TREE_TYPE(expr)) == BOOLEAN_TYPE)
4628         return fold_build1_loc(loc.gcc_location(), TRUTH_NOT_EXPR,
4629                                TREE_TYPE(expr), expr);
4630       else
4631         return fold_build2_loc(loc.gcc_location(), NE_EXPR, boolean_type_node,
4632                                expr, build_int_cst(TREE_TYPE(expr), 0));
4633
4634     case OPERATOR_XOR:
4635       return fold_build1_loc(loc.gcc_location(), BIT_NOT_EXPR, TREE_TYPE(expr),
4636                              expr);
4637
4638     case OPERATOR_AND:
4639       if (!this->create_temp_)
4640         {
4641           // We should not see a non-constant constructor here; cases
4642           // where we would see one should have been moved onto the
4643           // heap at parse time.  Taking the address of a nonconstant
4644           // constructor will not do what the programmer expects.
4645           go_assert(TREE_CODE(expr) != CONSTRUCTOR || TREE_CONSTANT(expr));
4646           go_assert(TREE_CODE(expr) != ADDR_EXPR);
4647         }
4648
4649       // Build a decl for a constant constructor.
4650       if (TREE_CODE(expr) == CONSTRUCTOR && TREE_CONSTANT(expr))
4651         {
4652           tree decl = build_decl(this->location().gcc_location(), VAR_DECL,
4653                                  create_tmp_var_name("C"), TREE_TYPE(expr));
4654           DECL_EXTERNAL(decl) = 0;
4655           TREE_PUBLIC(decl) = 0;
4656           TREE_READONLY(decl) = 1;
4657           TREE_CONSTANT(decl) = 1;
4658           TREE_STATIC(decl) = 1;
4659           TREE_ADDRESSABLE(decl) = 1;
4660           DECL_ARTIFICIAL(decl) = 1;
4661           DECL_INITIAL(decl) = expr;
4662           rest_of_decl_compilation(decl, 1, 0);
4663           expr = decl;
4664         }
4665
4666       if (this->create_temp_
4667           && !TREE_ADDRESSABLE(TREE_TYPE(expr))
4668           && !DECL_P(expr)
4669           && TREE_CODE(expr) != INDIRECT_REF
4670           && TREE_CODE(expr) != COMPONENT_REF)
4671         {
4672           tree tmp = create_tmp_var(TREE_TYPE(expr), get_name(expr));
4673           DECL_IGNORED_P(tmp) = 1;
4674           DECL_INITIAL(tmp) = expr;
4675           TREE_ADDRESSABLE(tmp) = 1;
4676           return build2_loc(loc.gcc_location(), COMPOUND_EXPR,
4677                             build_pointer_type(TREE_TYPE(expr)),
4678                             build1_loc(loc.gcc_location(), DECL_EXPR,
4679                                        void_type_node, tmp),
4680                             build_fold_addr_expr_loc(loc.gcc_location(), tmp));
4681         }
4682
4683       return build_fold_addr_expr_loc(loc.gcc_location(), expr);
4684
4685     case OPERATOR_MULT:
4686       {
4687         go_assert(POINTER_TYPE_P(TREE_TYPE(expr)));
4688
4689         // If we are dereferencing the pointer to a large struct, we
4690         // need to check for nil.  We don't bother to check for small
4691         // structs because we expect the system to crash on a nil
4692         // pointer dereference.
4693         HOST_WIDE_INT s = int_size_in_bytes(TREE_TYPE(TREE_TYPE(expr)));
4694         if (s == -1 || s >= 4096)
4695           {
4696             if (!DECL_P(expr))
4697               expr = save_expr(expr);
4698             tree compare = fold_build2_loc(loc.gcc_location(), EQ_EXPR,
4699                                            boolean_type_node,
4700                                            expr,
4701                                            fold_convert(TREE_TYPE(expr),
4702                                                         null_pointer_node));
4703             tree crash = Gogo::runtime_error(RUNTIME_ERROR_NIL_DEREFERENCE,
4704                                              loc);
4705             expr = fold_build2_loc(loc.gcc_location(), COMPOUND_EXPR,
4706                                    TREE_TYPE(expr), build3(COND_EXPR,
4707                                                            void_type_node,
4708                                                            compare, crash,
4709                                                            NULL_TREE),
4710                                    expr);
4711           }
4712
4713         // If the type of EXPR is a recursive pointer type, then we
4714         // need to insert a cast before indirecting.
4715         if (TREE_TYPE(TREE_TYPE(expr)) == ptr_type_node)
4716           {
4717             Type* pt = this->expr_->type()->points_to();
4718             tree ind = type_to_tree(pt->get_backend(context->gogo()));
4719             expr = fold_convert_loc(loc.gcc_location(),
4720                                     build_pointer_type(ind), expr);
4721           }
4722
4723         return build_fold_indirect_ref_loc(loc.gcc_location(), expr);
4724       }
4725
4726     default:
4727       go_unreachable();
4728     }
4729 }
4730
4731 // Export a unary expression.
4732
4733 void
4734 Unary_expression::do_export(Export* exp) const
4735 {
4736   switch (this->op_)
4737     {
4738     case OPERATOR_PLUS:
4739       exp->write_c_string("+ ");
4740       break;
4741     case OPERATOR_MINUS:
4742       exp->write_c_string("- ");
4743       break;
4744     case OPERATOR_NOT:
4745       exp->write_c_string("! ");
4746       break;
4747     case OPERATOR_XOR:
4748       exp->write_c_string("^ ");
4749       break;
4750     case OPERATOR_AND:
4751     case OPERATOR_MULT:
4752     default:
4753       go_unreachable();
4754     }
4755   this->expr_->export_expression(exp);
4756 }
4757
4758 // Import a unary expression.
4759
4760 Expression*
4761 Unary_expression::do_import(Import* imp)
4762 {
4763   Operator op;
4764   switch (imp->get_char())
4765     {
4766     case '+':
4767       op = OPERATOR_PLUS;
4768       break;
4769     case '-':
4770       op = OPERATOR_MINUS;
4771       break;
4772     case '!':
4773       op = OPERATOR_NOT;
4774       break;
4775     case '^':
4776       op = OPERATOR_XOR;
4777       break;
4778     default:
4779       go_unreachable();
4780     }
4781   imp->require_c_string(" ");
4782   Expression* expr = Expression::import_expression(imp);
4783   return Expression::make_unary(op, expr, imp->location());
4784 }
4785
4786 // Dump ast representation of an unary expression.
4787
4788 void
4789 Unary_expression::do_dump_expression(Ast_dump_context* ast_dump_context) const
4790 {
4791   ast_dump_context->dump_operator(this->op_);
4792   ast_dump_context->ostream() << "(";
4793   ast_dump_context->dump_expression(this->expr_);
4794   ast_dump_context->ostream() << ") ";
4795 }
4796
4797 // Make a unary expression.
4798
4799 Expression*
4800 Expression::make_unary(Operator op, Expression* expr, Location location)
4801 {
4802   return new Unary_expression(op, expr, location);
4803 }
4804
4805 // If this is an indirection through a pointer, return the expression
4806 // being pointed through.  Otherwise return this.
4807
4808 Expression*
4809 Expression::deref()
4810 {
4811   if (this->classification_ == EXPRESSION_UNARY)
4812     {
4813       Unary_expression* ue = static_cast<Unary_expression*>(this);
4814       if (ue->op() == OPERATOR_MULT)
4815         return ue->operand();
4816     }
4817   return this;
4818 }
4819
4820 // Class Binary_expression.
4821
4822 // Traversal.
4823
4824 int
4825 Binary_expression::do_traverse(Traverse* traverse)
4826 {
4827   int t = Expression::traverse(&this->left_, traverse);
4828   if (t == TRAVERSE_EXIT)
4829     return TRAVERSE_EXIT;
4830   return Expression::traverse(&this->right_, traverse);
4831 }
4832
4833 // Compare integer constants according to OP.
4834
4835 bool
4836 Binary_expression::compare_integer(Operator op, mpz_t left_val,
4837                                    mpz_t right_val)
4838 {
4839   int i = mpz_cmp(left_val, right_val);
4840   switch (op)
4841     {
4842     case OPERATOR_EQEQ:
4843       return i == 0;
4844     case OPERATOR_NOTEQ:
4845       return i != 0;
4846     case OPERATOR_LT:
4847       return i < 0;
4848     case OPERATOR_LE:
4849       return i <= 0;
4850     case OPERATOR_GT:
4851       return i > 0;
4852     case OPERATOR_GE:
4853       return i >= 0;
4854     default:
4855       go_unreachable();
4856     }
4857 }
4858
4859 // Compare floating point constants according to OP.
4860
4861 bool
4862 Binary_expression::compare_float(Operator op, Type* type, mpfr_t left_val,
4863                                  mpfr_t right_val)
4864 {
4865   int i;
4866   if (type == NULL)
4867     i = mpfr_cmp(left_val, right_val);
4868   else
4869     {
4870       mpfr_t lv;
4871       mpfr_init_set(lv, left_val, GMP_RNDN);
4872       mpfr_t rv;
4873       mpfr_init_set(rv, right_val, GMP_RNDN);
4874       Float_expression::constrain_float(lv, type);
4875       Float_expression::constrain_float(rv, type);
4876       i = mpfr_cmp(lv, rv);
4877       mpfr_clear(lv);
4878       mpfr_clear(rv);
4879     }
4880   switch (op)
4881     {
4882     case OPERATOR_EQEQ:
4883       return i == 0;
4884     case OPERATOR_NOTEQ:
4885       return i != 0;
4886     case OPERATOR_LT:
4887       return i < 0;
4888     case OPERATOR_LE:
4889       return i <= 0;
4890     case OPERATOR_GT:
4891       return i > 0;
4892     case OPERATOR_GE:
4893       return i >= 0;
4894     default:
4895       go_unreachable();
4896     }
4897 }
4898
4899 // Compare complex constants according to OP.  Complex numbers may
4900 // only be compared for equality.
4901
4902 bool
4903 Binary_expression::compare_complex(Operator op, Type* type,
4904                                    mpfr_t left_real, mpfr_t left_imag,
4905                                    mpfr_t right_real, mpfr_t right_imag)
4906 {
4907   bool is_equal;
4908   if (type == NULL)
4909     is_equal = (mpfr_cmp(left_real, right_real) == 0
4910                 && mpfr_cmp(left_imag, right_imag) == 0);
4911   else
4912     {
4913       mpfr_t lr;
4914       mpfr_t li;
4915       mpfr_init_set(lr, left_real, GMP_RNDN);
4916       mpfr_init_set(li, left_imag, GMP_RNDN);
4917       mpfr_t rr;
4918       mpfr_t ri;
4919       mpfr_init_set(rr, right_real, GMP_RNDN);
4920       mpfr_init_set(ri, right_imag, GMP_RNDN);
4921       Complex_expression::constrain_complex(lr, li, type);
4922       Complex_expression::constrain_complex(rr, ri, type);
4923       is_equal = mpfr_cmp(lr, rr) == 0 && mpfr_cmp(li, ri) == 0;
4924       mpfr_clear(lr);
4925       mpfr_clear(li);
4926       mpfr_clear(rr);
4927       mpfr_clear(ri);
4928     }
4929   switch (op)
4930     {
4931     case OPERATOR_EQEQ:
4932       return is_equal;
4933     case OPERATOR_NOTEQ:
4934       return !is_equal;
4935     default:
4936       go_unreachable();
4937     }
4938 }
4939
4940 // Apply binary opcode OP to LEFT_VAL and RIGHT_VAL, setting VAL.
4941 // LEFT_TYPE is the type of LEFT_VAL, RIGHT_TYPE is the type of
4942 // RIGHT_VAL; LEFT_TYPE and/or RIGHT_TYPE may be NULL.  Return true if
4943 // this could be done, false if not.
4944
4945 bool
4946 Binary_expression::eval_integer(Operator op, Type* left_type, mpz_t left_val,
4947                                 Type* right_type, mpz_t right_val,
4948                                 Location location, mpz_t val)
4949 {
4950   bool is_shift_op = false;
4951   switch (op)
4952     {
4953     case OPERATOR_OROR:
4954     case OPERATOR_ANDAND:
4955     case OPERATOR_EQEQ:
4956     case OPERATOR_NOTEQ:
4957     case OPERATOR_LT:
4958     case OPERATOR_LE:
4959     case OPERATOR_GT:
4960     case OPERATOR_GE:
4961       // These return boolean values.  We should probably handle them
4962       // anyhow in case a type conversion is used on the result.
4963       return false;
4964     case OPERATOR_PLUS:
4965       mpz_add(val, left_val, right_val);
4966       break;
4967     case OPERATOR_MINUS:
4968       mpz_sub(val, left_val, right_val);
4969       break;
4970     case OPERATOR_OR:
4971       mpz_ior(val, left_val, right_val);
4972       break;
4973     case OPERATOR_XOR:
4974       mpz_xor(val, left_val, right_val);
4975       break;
4976     case OPERATOR_MULT:
4977       mpz_mul(val, left_val, right_val);
4978       break;
4979     case OPERATOR_DIV:
4980       if (mpz_sgn(right_val) != 0)
4981         mpz_tdiv_q(val, left_val, right_val);
4982       else
4983         {
4984           error_at(location, "division by zero");
4985           mpz_set_ui(val, 0);
4986           return true;
4987         }
4988       break;
4989     case OPERATOR_MOD:
4990       if (mpz_sgn(right_val) != 0)
4991         mpz_tdiv_r(val, left_val, right_val);
4992       else
4993         {
4994           error_at(location, "division by zero");
4995           mpz_set_ui(val, 0);
4996           return true;
4997         }
4998       break;
4999     case OPERATOR_LSHIFT:
5000       {
5001         unsigned long shift = mpz_get_ui(right_val);
5002         if (mpz_cmp_ui(right_val, shift) != 0 || shift > 0x100000)
5003           {
5004             error_at(location, "shift count overflow");
5005             mpz_set_ui(val, 0);
5006             return true;
5007           }
5008         mpz_mul_2exp(val, left_val, shift);
5009         is_shift_op = true;
5010         break;
5011       }
5012       break;
5013     case OPERATOR_RSHIFT:
5014       {
5015         unsigned long shift = mpz_get_ui(right_val);
5016         if (mpz_cmp_ui(right_val, shift) != 0)
5017           {
5018             error_at(location, "shift count overflow");
5019             mpz_set_ui(val, 0);
5020             return true;
5021           }
5022         if (mpz_cmp_ui(left_val, 0) >= 0)
5023           mpz_tdiv_q_2exp(val, left_val, shift);
5024         else
5025           mpz_fdiv_q_2exp(val, left_val, shift);
5026         is_shift_op = true;
5027         break;
5028       }
5029       break;
5030     case OPERATOR_AND:
5031       mpz_and(val, left_val, right_val);
5032       break;
5033     case OPERATOR_BITCLEAR:
5034       {
5035         mpz_t tval;
5036         mpz_init(tval);
5037         mpz_com(tval, right_val);
5038         mpz_and(val, left_val, tval);
5039         mpz_clear(tval);
5040       }
5041       break;
5042     default:
5043       go_unreachable();
5044     }
5045
5046   Type* type = left_type;
5047   if (!is_shift_op)
5048     {
5049       if (type == NULL)
5050         type = right_type;
5051       else if (type != right_type && right_type != NULL)
5052         {
5053           if (type->is_abstract())
5054             type = right_type;
5055           else if (!right_type->is_abstract())
5056             {
5057               // This look like a type error which should be diagnosed
5058               // elsewhere.  Don't do anything here, to avoid an
5059               // unhelpful chain of error messages.
5060               return true;
5061             }
5062         }
5063     }
5064
5065   if (type != NULL && !type->is_abstract())
5066     {
5067       // We have to check the operands too, as we have implicitly
5068       // coerced them to TYPE.
5069       if ((type != left_type
5070            && !Integer_expression::check_constant(left_val, type, location))
5071           || (!is_shift_op
5072               && type != right_type
5073               && !Integer_expression::check_constant(right_val, type,
5074                                                      location))
5075           || !Integer_expression::check_constant(val, type, location))
5076         mpz_set_ui(val, 0);
5077     }
5078
5079   return true;
5080 }
5081
5082 // Apply binary opcode OP to LEFT_VAL and RIGHT_VAL, setting VAL.
5083 // Return true if this could be done, false if not.
5084
5085 bool
5086 Binary_expression::eval_float(Operator op, Type* left_type, mpfr_t left_val,
5087                               Type* right_type, mpfr_t right_val,
5088                               mpfr_t val, Location location)
5089 {
5090   switch (op)
5091     {
5092     case OPERATOR_OROR:
5093     case OPERATOR_ANDAND:
5094     case OPERATOR_EQEQ:
5095     case OPERATOR_NOTEQ:
5096     case OPERATOR_LT:
5097     case OPERATOR_LE:
5098     case OPERATOR_GT:
5099     case OPERATOR_GE:
5100       // These return boolean values.  We should probably handle them
5101       // anyhow in case a type conversion is used on the result.
5102       return false;
5103     case OPERATOR_PLUS:
5104       mpfr_add(val, left_val, right_val, GMP_RNDN);
5105       break;
5106     case OPERATOR_MINUS:
5107       mpfr_sub(val, left_val, right_val, GMP_RNDN);
5108       break;
5109     case OPERATOR_OR:
5110     case OPERATOR_XOR:
5111     case OPERATOR_AND:
5112     case OPERATOR_BITCLEAR:
5113       return false;
5114     case OPERATOR_MULT:
5115       mpfr_mul(val, left_val, right_val, GMP_RNDN);
5116       break;
5117     case OPERATOR_DIV:
5118       if (mpfr_zero_p(right_val))
5119         error_at(location, "division by zero");
5120       mpfr_div(val, left_val, right_val, GMP_RNDN);
5121       break;
5122     case OPERATOR_MOD:
5123       return false;
5124     case OPERATOR_LSHIFT:
5125     case OPERATOR_RSHIFT:
5126       return false;
5127     default:
5128       go_unreachable();
5129     }
5130
5131   Type* type = left_type;
5132   if (type == NULL)
5133     type = right_type;
5134   else if (type != right_type && right_type != NULL)
5135     {
5136       if (type->is_abstract())
5137         type = right_type;
5138       else if (!right_type->is_abstract())
5139         {
5140           // This looks like a type error which should be diagnosed
5141           // elsewhere.  Don't do anything here, to avoid an unhelpful
5142           // chain of error messages.
5143           return true;
5144         }
5145     }
5146
5147   if (type != NULL && !type->is_abstract())
5148     {
5149       if ((type != left_type
5150            && !Float_expression::check_constant(left_val, type, location))
5151           || (type != right_type
5152               && !Float_expression::check_constant(right_val, type,
5153                                                    location))
5154           || !Float_expression::check_constant(val, type, location))
5155         mpfr_set_ui(val, 0, GMP_RNDN);
5156     }
5157
5158   return true;
5159 }
5160
5161 // Apply binary opcode OP to LEFT_REAL/LEFT_IMAG and
5162 // RIGHT_REAL/RIGHT_IMAG, setting REAL/IMAG.  Return true if this
5163 // could be done, false if not.
5164
5165 bool
5166 Binary_expression::eval_complex(Operator op, Type* left_type,
5167                                 mpfr_t left_real, mpfr_t left_imag,
5168                                 Type *right_type,
5169                                 mpfr_t right_real, mpfr_t right_imag,
5170                                 mpfr_t real, mpfr_t imag,
5171                                 Location location)
5172 {
5173   switch (op)
5174     {
5175     case OPERATOR_OROR:
5176     case OPERATOR_ANDAND:
5177     case OPERATOR_EQEQ:
5178     case OPERATOR_NOTEQ:
5179     case OPERATOR_LT:
5180     case OPERATOR_LE:
5181     case OPERATOR_GT:
5182     case OPERATOR_GE:
5183       // These return boolean values and must be handled differently.
5184       return false;
5185     case OPERATOR_PLUS:
5186       mpfr_add(real, left_real, right_real, GMP_RNDN);
5187       mpfr_add(imag, left_imag, right_imag, GMP_RNDN);
5188       break;
5189     case OPERATOR_MINUS:
5190       mpfr_sub(real, left_real, right_real, GMP_RNDN);
5191       mpfr_sub(imag, left_imag, right_imag, GMP_RNDN);
5192       break;
5193     case OPERATOR_OR:
5194     case OPERATOR_XOR:
5195     case OPERATOR_AND:
5196     case OPERATOR_BITCLEAR:
5197       return false;
5198     case OPERATOR_MULT:
5199       {
5200         // You might think that multiplying two complex numbers would
5201         // be simple, and you would be right, until you start to think
5202         // about getting the right answer for infinity.  If one
5203         // operand here is infinity and the other is anything other
5204         // than zero or NaN, then we are going to wind up subtracting
5205         // two infinity values.  That will give us a NaN, but the
5206         // correct answer is infinity.
5207
5208         mpfr_t lrrr;
5209         mpfr_init(lrrr);
5210         mpfr_mul(lrrr, left_real, right_real, GMP_RNDN);
5211
5212         mpfr_t lrri;
5213         mpfr_init(lrri);
5214         mpfr_mul(lrri, left_real, right_imag, GMP_RNDN);
5215
5216         mpfr_t lirr;
5217         mpfr_init(lirr);
5218         mpfr_mul(lirr, left_imag, right_real, GMP_RNDN);
5219
5220         mpfr_t liri;
5221         mpfr_init(liri);
5222         mpfr_mul(liri, left_imag, right_imag, GMP_RNDN);
5223
5224         mpfr_sub(real, lrrr, liri, GMP_RNDN);
5225         mpfr_add(imag, lrri, lirr, GMP_RNDN);
5226
5227         // If we get NaN on both sides, check whether it should really
5228         // be infinity.  The rule is that if either side of the
5229         // complex number is infinity, then the whole value is
5230         // infinity, even if the other side is NaN.  So the only case
5231         // we have to fix is the one in which both sides are NaN.
5232         if (mpfr_nan_p(real) && mpfr_nan_p(imag)
5233             && (!mpfr_nan_p(left_real) || !mpfr_nan_p(left_imag))
5234             && (!mpfr_nan_p(right_real) || !mpfr_nan_p(right_imag)))
5235           {
5236             bool is_infinity = false;
5237
5238             mpfr_t lr;
5239             mpfr_t li;
5240             mpfr_init_set(lr, left_real, GMP_RNDN);
5241             mpfr_init_set(li, left_imag, GMP_RNDN);
5242
5243             mpfr_t rr;
5244             mpfr_t ri;
5245             mpfr_init_set(rr, right_real, GMP_RNDN);
5246             mpfr_init_set(ri, right_imag, GMP_RNDN);
5247
5248             // If the left side is infinity, then the result is
5249             // infinity.
5250             if (mpfr_inf_p(lr) || mpfr_inf_p(li))
5251               {
5252                 mpfr_set_ui(lr, mpfr_inf_p(lr) ? 1 : 0, GMP_RNDN);
5253                 mpfr_copysign(lr, lr, left_real, GMP_RNDN);
5254                 mpfr_set_ui(li, mpfr_inf_p(li) ? 1 : 0, GMP_RNDN);
5255                 mpfr_copysign(li, li, left_imag, GMP_RNDN);
5256                 if (mpfr_nan_p(rr))
5257                   {
5258                     mpfr_set_ui(rr, 0, GMP_RNDN);
5259                     mpfr_copysign(rr, rr, right_real, GMP_RNDN);
5260                   }
5261                 if (mpfr_nan_p(ri))
5262                   {
5263                     mpfr_set_ui(ri, 0, GMP_RNDN);
5264                     mpfr_copysign(ri, ri, right_imag, GMP_RNDN);
5265                   }
5266                 is_infinity = true;
5267               }
5268
5269             // If the right side is infinity, then the result is
5270             // infinity.
5271             if (mpfr_inf_p(rr) || mpfr_inf_p(ri))
5272               {
5273                 mpfr_set_ui(rr, mpfr_inf_p(rr) ? 1 : 0, GMP_RNDN);
5274                 mpfr_copysign(rr, rr, right_real, GMP_RNDN);
5275                 mpfr_set_ui(ri, mpfr_inf_p(ri) ? 1 : 0, GMP_RNDN);
5276                 mpfr_copysign(ri, ri, right_imag, GMP_RNDN);
5277                 if (mpfr_nan_p(lr))
5278                   {
5279                     mpfr_set_ui(lr, 0, GMP_RNDN);
5280                     mpfr_copysign(lr, lr, left_real, GMP_RNDN);
5281                   }
5282                 if (mpfr_nan_p(li))
5283                   {
5284                     mpfr_set_ui(li, 0, GMP_RNDN);
5285                     mpfr_copysign(li, li, left_imag, GMP_RNDN);
5286                   }
5287                 is_infinity = true;
5288               }
5289
5290             // If we got an overflow in the intermediate computations,
5291             // then the result is infinity.
5292             if (!is_infinity
5293                 && (mpfr_inf_p(lrrr) || mpfr_inf_p(lrri)
5294                     || mpfr_inf_p(lirr) || mpfr_inf_p(liri)))
5295               {
5296                 if (mpfr_nan_p(lr))
5297                   {
5298                     mpfr_set_ui(lr, 0, GMP_RNDN);
5299                     mpfr_copysign(lr, lr, left_real, GMP_RNDN);
5300                   }
5301                 if (mpfr_nan_p(li))
5302                   {
5303                     mpfr_set_ui(li, 0, GMP_RNDN);
5304                     mpfr_copysign(li, li, left_imag, GMP_RNDN);
5305                   }
5306                 if (mpfr_nan_p(rr))
5307                   {
5308                     mpfr_set_ui(rr, 0, GMP_RNDN);
5309                     mpfr_copysign(rr, rr, right_real, GMP_RNDN);
5310                   }
5311                 if (mpfr_nan_p(ri))
5312                   {
5313                     mpfr_set_ui(ri, 0, GMP_RNDN);
5314                     mpfr_copysign(ri, ri, right_imag, GMP_RNDN);
5315                   }
5316                 is_infinity = true;
5317               }
5318
5319             if (is_infinity)
5320               {
5321                 mpfr_mul(lrrr, lr, rr, GMP_RNDN);
5322                 mpfr_mul(lrri, lr, ri, GMP_RNDN);
5323                 mpfr_mul(lirr, li, rr, GMP_RNDN);
5324                 mpfr_mul(liri, li, ri, GMP_RNDN);
5325                 mpfr_sub(real, lrrr, liri, GMP_RNDN);
5326                 mpfr_add(imag, lrri, lirr, GMP_RNDN);
5327                 mpfr_set_inf(real, mpfr_sgn(real));
5328                 mpfr_set_inf(imag, mpfr_sgn(imag));
5329               }
5330
5331             mpfr_clear(lr);
5332             mpfr_clear(li);
5333             mpfr_clear(rr);
5334             mpfr_clear(ri);
5335           }
5336
5337         mpfr_clear(lrrr);
5338         mpfr_clear(lrri);
5339         mpfr_clear(lirr);
5340         mpfr_clear(liri);
5341       }
5342       break;
5343     case OPERATOR_DIV:
5344       {
5345         // For complex division we want to avoid having an
5346         // intermediate overflow turn the whole result in a NaN.  We
5347         // scale the values to try to avoid this.
5348
5349         if (mpfr_zero_p(right_real) && mpfr_zero_p(right_imag))
5350           error_at(location, "division by zero");
5351
5352         mpfr_t rra;
5353         mpfr_t ria;
5354         mpfr_init(rra);
5355         mpfr_init(ria);
5356         mpfr_abs(rra, right_real, GMP_RNDN);
5357         mpfr_abs(ria, right_imag, GMP_RNDN);
5358         mpfr_t t;
5359         mpfr_init(t);
5360         mpfr_max(t, rra, ria, GMP_RNDN);
5361
5362         mpfr_t rr;
5363         mpfr_t ri;
5364         mpfr_init_set(rr, right_real, GMP_RNDN);
5365         mpfr_init_set(ri, right_imag, GMP_RNDN);
5366         long ilogbw = 0;
5367         if (!mpfr_inf_p(t) && !mpfr_nan_p(t) && !mpfr_zero_p(t))
5368           {
5369             ilogbw = mpfr_get_exp(t);
5370             mpfr_mul_2si(rr, rr, - ilogbw, GMP_RNDN);
5371             mpfr_mul_2si(ri, ri, - ilogbw, GMP_RNDN);
5372           }
5373
5374         mpfr_t denom;
5375         mpfr_init(denom);
5376         mpfr_mul(denom, rr, rr, GMP_RNDN);
5377         mpfr_mul(t, ri, ri, GMP_RNDN);
5378         mpfr_add(denom, denom, t, GMP_RNDN);
5379
5380         mpfr_mul(real, left_real, rr, GMP_RNDN);
5381         mpfr_mul(t, left_imag, ri, GMP_RNDN);
5382         mpfr_add(real, real, t, GMP_RNDN);
5383         mpfr_div(real, real, denom, GMP_RNDN);
5384         mpfr_mul_2si(real, real, - ilogbw, GMP_RNDN);
5385
5386         mpfr_mul(imag, left_imag, rr, GMP_RNDN);
5387         mpfr_mul(t, left_real, ri, GMP_RNDN);
5388         mpfr_sub(imag, imag, t, GMP_RNDN);
5389         mpfr_div(imag, imag, denom, GMP_RNDN);
5390         mpfr_mul_2si(imag, imag, - ilogbw, GMP_RNDN);
5391
5392         // If we wind up with NaN on both sides, check whether we
5393         // should really have infinity.  The rule is that if either
5394         // side of the complex number is infinity, then the whole
5395         // value is infinity, even if the other side is NaN.  So the
5396         // only case we have to fix is the one in which both sides are
5397         // NaN.
5398         if (mpfr_nan_p(real) && mpfr_nan_p(imag)
5399             && (!mpfr_nan_p(left_real) || !mpfr_nan_p(left_imag))
5400             && (!mpfr_nan_p(right_real) || !mpfr_nan_p(right_imag)))
5401           {
5402             if (mpfr_zero_p(denom))
5403               {
5404                 mpfr_set_inf(real, mpfr_sgn(rr));
5405                 mpfr_mul(real, real, left_real, GMP_RNDN);
5406                 mpfr_set_inf(imag, mpfr_sgn(rr));
5407                 mpfr_mul(imag, imag, left_imag, GMP_RNDN);
5408               }
5409             else if ((mpfr_inf_p(left_real) || mpfr_inf_p(left_imag))
5410                      && mpfr_number_p(rr) && mpfr_number_p(ri))
5411               {
5412                 mpfr_set_ui(t, mpfr_inf_p(left_real) ? 1 : 0, GMP_RNDN);
5413                 mpfr_copysign(t, t, left_real, GMP_RNDN);
5414
5415                 mpfr_t t2;
5416                 mpfr_init_set_ui(t2, mpfr_inf_p(left_imag) ? 1 : 0, GMP_RNDN);
5417                 mpfr_copysign(t2, t2, left_imag, GMP_RNDN);
5418
5419                 mpfr_t t3;
5420                 mpfr_init(t3);
5421                 mpfr_mul(t3, t, rr, GMP_RNDN);
5422
5423                 mpfr_t t4;
5424                 mpfr_init(t4);
5425                 mpfr_mul(t4, t2, ri, GMP_RNDN);
5426
5427                 mpfr_add(t3, t3, t4, GMP_RNDN);
5428                 mpfr_set_inf(real, mpfr_sgn(t3));
5429
5430                 mpfr_mul(t3, t2, rr, GMP_RNDN);
5431                 mpfr_mul(t4, t, ri, GMP_RNDN);
5432                 mpfr_sub(t3, t3, t4, GMP_RNDN);
5433                 mpfr_set_inf(imag, mpfr_sgn(t3));
5434
5435                 mpfr_clear(t2);
5436                 mpfr_clear(t3);
5437                 mpfr_clear(t4);
5438               }
5439             else if ((mpfr_inf_p(right_real) || mpfr_inf_p(right_imag))
5440                      && mpfr_number_p(left_real) && mpfr_number_p(left_imag))
5441               {
5442                 mpfr_set_ui(t, mpfr_inf_p(rr) ? 1 : 0, GMP_RNDN);
5443                 mpfr_copysign(t, t, rr, GMP_RNDN);
5444
5445                 mpfr_t t2;
5446                 mpfr_init_set_ui(t2, mpfr_inf_p(ri) ? 1 : 0, GMP_RNDN);
5447                 mpfr_copysign(t2, t2, ri, GMP_RNDN);
5448
5449                 mpfr_t t3;
5450                 mpfr_init(t3);
5451                 mpfr_mul(t3, left_real, t, GMP_RNDN);
5452
5453                 mpfr_t t4;
5454                 mpfr_init(t4);
5455                 mpfr_mul(t4, left_imag, t2, GMP_RNDN);
5456
5457                 mpfr_add(t3, t3, t4, GMP_RNDN);
5458                 mpfr_set_ui(real, 0, GMP_RNDN);
5459                 mpfr_mul(real, real, t3, GMP_RNDN);
5460
5461                 mpfr_mul(t3, left_imag, t, GMP_RNDN);
5462                 mpfr_mul(t4, left_real, t2, GMP_RNDN);
5463                 mpfr_sub(t3, t3, t4, GMP_RNDN);
5464                 mpfr_set_ui(imag, 0, GMP_RNDN);
5465                 mpfr_mul(imag, imag, t3, GMP_RNDN);
5466
5467                 mpfr_clear(t2);
5468                 mpfr_clear(t3);
5469                 mpfr_clear(t4);
5470               }
5471           }
5472
5473         mpfr_clear(denom);
5474         mpfr_clear(rr);
5475         mpfr_clear(ri);
5476         mpfr_clear(t);
5477         mpfr_clear(rra);
5478         mpfr_clear(ria);
5479       }
5480       break;
5481     case OPERATOR_MOD:
5482       return false;
5483     case OPERATOR_LSHIFT:
5484     case OPERATOR_RSHIFT:
5485       return false;
5486     default:
5487       go_unreachable();
5488     }
5489
5490   Type* type = left_type;
5491   if (type == NULL)
5492     type = right_type;
5493   else if (type != right_type && right_type != NULL)
5494     {
5495       if (type->is_abstract())
5496         type = right_type;
5497       else if (!right_type->is_abstract())
5498         {
5499           // This looks like a type error which should be diagnosed
5500           // elsewhere.  Don't do anything here, to avoid an unhelpful
5501           // chain of error messages.
5502           return true;
5503         }
5504     }
5505
5506   if (type != NULL && !type->is_abstract())
5507     {
5508       if ((type != left_type
5509            && !Complex_expression::check_constant(left_real, left_imag,
5510                                                   type, location))
5511           || (type != right_type
5512               && !Complex_expression::check_constant(right_real, right_imag,
5513                                                      type, location))
5514           || !Complex_expression::check_constant(real, imag, type,
5515                                                  location))
5516         {
5517           mpfr_set_ui(real, 0, GMP_RNDN);
5518           mpfr_set_ui(imag, 0, GMP_RNDN);
5519         }
5520     }
5521
5522   return true;
5523 }
5524
5525 // Lower a binary expression.  We have to evaluate constant
5526 // expressions now, in order to implement Go's unlimited precision
5527 // constants.
5528
5529 Expression*
5530 Binary_expression::do_lower(Gogo* gogo, Named_object*,
5531                             Statement_inserter* inserter, int)
5532 {
5533   Location location = this->location();
5534   Operator op = this->op_;
5535   Expression* left = this->left_;
5536   Expression* right = this->right_;
5537
5538   const bool is_comparison = (op == OPERATOR_EQEQ
5539                               || op == OPERATOR_NOTEQ
5540                               || op == OPERATOR_LT
5541                               || op == OPERATOR_LE
5542                               || op == OPERATOR_GT
5543                               || op == OPERATOR_GE);
5544
5545   // Integer constant expressions.
5546   {
5547     mpz_t left_val;
5548     mpz_init(left_val);
5549     Type* left_type;
5550     mpz_t right_val;
5551     mpz_init(right_val);
5552     Type* right_type;
5553     if (left->integer_constant_value(false, left_val, &left_type)
5554         && right->integer_constant_value(false, right_val, &right_type))
5555       {
5556         Expression* ret = NULL;
5557         if (left_type != right_type
5558             && left_type != NULL
5559             && !left_type->is_abstract()
5560             && right_type != NULL
5561             && !right_type->is_abstract()
5562             && left_type->base() != right_type->base()
5563             && op != OPERATOR_LSHIFT
5564             && op != OPERATOR_RSHIFT)
5565           {
5566             // May be a type error--let it be diagnosed later.
5567             return this;
5568           }
5569         else if (is_comparison)
5570           {
5571             bool b = Binary_expression::compare_integer(op, left_val,
5572                                                         right_val);
5573             ret = Expression::make_cast(Type::lookup_bool_type(),
5574                                         Expression::make_boolean(b, location),
5575                                         location);
5576           }
5577         else
5578           {
5579             mpz_t val;
5580             mpz_init(val);
5581
5582             if (Binary_expression::eval_integer(op, left_type, left_val,
5583                                                 right_type, right_val,
5584                                                 location, val))
5585               {
5586                 go_assert(op != OPERATOR_OROR && op != OPERATOR_ANDAND);
5587                 Type* type;
5588                 if (op == OPERATOR_LSHIFT || op == OPERATOR_RSHIFT)
5589                   type = left_type;
5590                 else if (left_type == NULL)
5591                   type = right_type;
5592                 else if (right_type == NULL)
5593                   type = left_type;
5594                 else if (!left_type->is_abstract()
5595                          && left_type->named_type() != NULL)
5596                   type = left_type;
5597                 else if (!right_type->is_abstract()
5598                          && right_type->named_type() != NULL)
5599                   type = right_type;
5600                 else if (!left_type->is_abstract())
5601                   type = left_type;
5602                 else if (!right_type->is_abstract())
5603                   type = right_type;
5604                 else if (left_type->float_type() != NULL)
5605                   type = left_type;
5606                 else if (right_type->float_type() != NULL)
5607                   type = right_type;
5608                 else if (left_type->complex_type() != NULL)
5609                   type = left_type;
5610                 else if (right_type->complex_type() != NULL)
5611                   type = right_type;
5612                 else
5613                   type = left_type;
5614
5615                 bool is_character = false;
5616                 if (type == NULL)
5617                   {
5618                     Type* t = this->left_->type();
5619                     if (t->integer_type() != NULL
5620                         && t->integer_type()->is_rune())
5621                       is_character = true;
5622                     else if (op != OPERATOR_LSHIFT && op != OPERATOR_RSHIFT)
5623                       {
5624                         t = this->right_->type();
5625                         if (t->integer_type() != NULL
5626                             && t->integer_type()->is_rune())
5627                           is_character = true;
5628                       }
5629                   }
5630
5631                 if (is_character)
5632                   ret = Expression::make_character(&val, type, location);
5633                 else
5634                   ret = Expression::make_integer(&val, type, location);
5635               }
5636
5637             mpz_clear(val);
5638           }
5639
5640         if (ret != NULL)
5641           {
5642             mpz_clear(right_val);
5643             mpz_clear(left_val);
5644             return ret;
5645           }
5646       }
5647     mpz_clear(right_val);
5648     mpz_clear(left_val);
5649   }
5650
5651   // Floating point constant expressions.
5652   {
5653     mpfr_t left_val;
5654     mpfr_init(left_val);
5655     Type* left_type;
5656     mpfr_t right_val;
5657     mpfr_init(right_val);
5658     Type* right_type;
5659     if (left->float_constant_value(left_val, &left_type)
5660         && right->float_constant_value(right_val, &right_type))
5661       {
5662         Expression* ret = NULL;
5663         if (left_type != right_type
5664             && left_type != NULL
5665             && right_type != NULL
5666             && left_type->base() != right_type->base()
5667             && op != OPERATOR_LSHIFT
5668             && op != OPERATOR_RSHIFT)
5669           {
5670             // May be a type error--let it be diagnosed later.
5671             return this;
5672           }
5673         else if (is_comparison)
5674           {
5675             bool b = Binary_expression::compare_float(op,
5676                                                       (left_type != NULL
5677                                                        ? left_type
5678                                                        : right_type),
5679                                                       left_val, right_val);
5680             ret = Expression::make_boolean(b, location);
5681           }
5682         else
5683           {
5684             mpfr_t val;
5685             mpfr_init(val);
5686
5687             if (Binary_expression::eval_float(op, left_type, left_val,
5688                                               right_type, right_val, val,
5689                                               location))
5690               {
5691                 go_assert(op != OPERATOR_OROR && op != OPERATOR_ANDAND
5692                            && op != OPERATOR_LSHIFT && op != OPERATOR_RSHIFT);
5693                 Type* type;
5694                 if (left_type == NULL)
5695                   type = right_type;
5696                 else if (right_type == NULL)
5697                   type = left_type;
5698                 else if (!left_type->is_abstract()
5699                          && left_type->named_type() != NULL)
5700                   type = left_type;
5701                 else if (!right_type->is_abstract()
5702                          && right_type->named_type() != NULL)
5703                   type = right_type;
5704                 else if (!left_type->is_abstract())
5705                   type = left_type;
5706                 else if (!right_type->is_abstract())
5707                   type = right_type;
5708                 else if (left_type->float_type() != NULL)
5709                   type = left_type;
5710                 else if (right_type->float_type() != NULL)
5711                   type = right_type;
5712                 else
5713                   type = left_type;
5714                 ret = Expression::make_float(&val, type, location);
5715               }
5716
5717             mpfr_clear(val);
5718           }
5719
5720         if (ret != NULL)
5721           {
5722             mpfr_clear(right_val);
5723             mpfr_clear(left_val);
5724             return ret;
5725           }
5726       }
5727     mpfr_clear(right_val);
5728     mpfr_clear(left_val);
5729   }
5730
5731   // Complex constant expressions.
5732   {
5733     mpfr_t left_real;
5734     mpfr_t left_imag;
5735     mpfr_init(left_real);
5736     mpfr_init(left_imag);
5737     Type* left_type;
5738
5739     mpfr_t right_real;
5740     mpfr_t right_imag;
5741     mpfr_init(right_real);
5742     mpfr_init(right_imag);
5743     Type* right_type;
5744
5745     if (left->complex_constant_value(left_real, left_imag, &left_type)
5746         && right->complex_constant_value(right_real, right_imag, &right_type))
5747       {
5748         Expression* ret = NULL;
5749         if (left_type != right_type
5750             && left_type != NULL
5751             && right_type != NULL
5752             && left_type->base() != right_type->base())
5753           {
5754             // May be a type error--let it be diagnosed later.
5755             return this;
5756           }
5757         else if (op == OPERATOR_EQEQ || op == OPERATOR_NOTEQ)
5758           {
5759             bool b = Binary_expression::compare_complex(op,
5760                                                         (left_type != NULL
5761                                                          ? left_type
5762                                                          : right_type),
5763                                                         left_real,
5764                                                         left_imag,
5765                                                         right_real,
5766                                                         right_imag);
5767             ret = Expression::make_boolean(b, location);
5768           }
5769         else
5770           {
5771             mpfr_t real;
5772             mpfr_t imag;
5773             mpfr_init(real);
5774             mpfr_init(imag);
5775
5776             if (Binary_expression::eval_complex(op, left_type,
5777                                                 left_real, left_imag,
5778                                                 right_type,
5779                                                 right_real, right_imag,
5780                                                 real, imag,
5781                                                 location))
5782               {
5783                 go_assert(op != OPERATOR_OROR && op != OPERATOR_ANDAND
5784                            && op != OPERATOR_LSHIFT && op != OPERATOR_RSHIFT);
5785                 Type* type;
5786                 if (left_type == NULL)
5787                   type = right_type;
5788                 else if (right_type == NULL)
5789                   type = left_type;
5790                 else if (!left_type->is_abstract()
5791                          && left_type->named_type() != NULL)
5792                   type = left_type;
5793                 else if (!right_type->is_abstract()
5794                          && right_type->named_type() != NULL)
5795                   type = right_type;
5796                 else if (!left_type->is_abstract())
5797                   type = left_type;
5798                 else if (!right_type->is_abstract())
5799                   type = right_type;
5800                 else if (left_type->complex_type() != NULL)
5801                   type = left_type;
5802                 else if (right_type->complex_type() != NULL)
5803                   type = right_type;
5804                 else
5805                   type = left_type;
5806                 ret = Expression::make_complex(&real, &imag, type,
5807                                                location);
5808               }
5809             mpfr_clear(real);
5810             mpfr_clear(imag);
5811           }
5812
5813         if (ret != NULL)
5814           {
5815             mpfr_clear(left_real);
5816             mpfr_clear(left_imag);
5817             mpfr_clear(right_real);
5818             mpfr_clear(right_imag);
5819             return ret;
5820           }
5821       }
5822
5823     mpfr_clear(left_real);
5824     mpfr_clear(left_imag);
5825     mpfr_clear(right_real);
5826     mpfr_clear(right_imag);
5827   }
5828
5829   // String constant expressions.
5830   if (left->type()->is_string_type() && right->type()->is_string_type())
5831     {
5832       std::string left_string;
5833       std::string right_string;
5834       if (left->string_constant_value(&left_string)
5835           && right->string_constant_value(&right_string))
5836         {
5837           if (op == OPERATOR_PLUS)
5838             return Expression::make_string(left_string + right_string,
5839                                            location);
5840           else if (is_comparison)
5841             {
5842               int cmp = left_string.compare(right_string);
5843               bool r;
5844               switch (op)
5845                 {
5846                 case OPERATOR_EQEQ:
5847                   r = cmp == 0;
5848                   break;
5849                 case OPERATOR_NOTEQ:
5850                   r = cmp != 0;
5851                   break;
5852                 case OPERATOR_LT:
5853                   r = cmp < 0;
5854                   break;
5855                 case OPERATOR_LE:
5856                   r = cmp <= 0;
5857                   break;
5858                 case OPERATOR_GT:
5859                   r = cmp > 0;
5860                   break;
5861                 case OPERATOR_GE:
5862                   r = cmp >= 0;
5863                   break;
5864                 default:
5865                   go_unreachable();
5866                 }
5867               return Expression::make_boolean(r, location);
5868             }
5869         }
5870     }
5871
5872   // Special case for shift of a floating point constant.
5873   if (op == OPERATOR_LSHIFT || op == OPERATOR_RSHIFT)
5874     {
5875       mpfr_t left_val;
5876       mpfr_init(left_val);
5877       Type* left_type;
5878       mpz_t right_val;
5879       mpz_init(right_val);
5880       Type* right_type;
5881       if (left->float_constant_value(left_val, &left_type)
5882           && right->integer_constant_value(false, right_val, &right_type)
5883           && mpfr_integer_p(left_val)
5884           && (left_type == NULL
5885               || left_type->is_abstract()
5886               || left_type->integer_type() != NULL))
5887         {
5888           mpz_t left_int;
5889           mpz_init(left_int);
5890           mpfr_get_z(left_int, left_val, GMP_RNDN);
5891
5892           mpz_t val;
5893           mpz_init(val);
5894
5895           Expression* ret = NULL;
5896           if (Binary_expression::eval_integer(op, left_type, left_int,
5897                                               right_type, right_val,
5898                                               location, val))
5899             ret = Expression::make_integer(&val, left_type, location);
5900
5901           mpz_clear(left_int);
5902           mpz_clear(val);
5903
5904           if (ret != NULL)
5905             {
5906               mpfr_clear(left_val);
5907               mpz_clear(right_val);
5908               return ret;
5909             }
5910         }
5911
5912       mpfr_clear(left_val);
5913       mpz_clear(right_val);
5914     }
5915
5916   // Lower struct and array comparisons.
5917   if (op == OPERATOR_EQEQ || op == OPERATOR_NOTEQ)
5918     {
5919       if (left->type()->struct_type() != NULL)
5920         return this->lower_struct_comparison(gogo, inserter);
5921       else if (left->type()->array_type() != NULL
5922                && !left->type()->is_slice_type())
5923         return this->lower_array_comparison(gogo, inserter);
5924     }
5925
5926   return this;
5927 }
5928
5929 // Lower a struct comparison.
5930
5931 Expression*
5932 Binary_expression::lower_struct_comparison(Gogo* gogo,
5933                                            Statement_inserter* inserter)
5934 {
5935   Struct_type* st = this->left_->type()->struct_type();
5936   Struct_type* st2 = this->right_->type()->struct_type();
5937   if (st2 == NULL)
5938     return this;
5939   if (st != st2 && !Type::are_identical(st, st2, false, NULL))
5940     return this;
5941   if (!Type::are_compatible_for_comparison(true, this->left_->type(),
5942                                            this->right_->type(), NULL))
5943     return this;
5944
5945   // See if we can compare using memcmp.  As a heuristic, we use
5946   // memcmp rather than field references and comparisons if there are
5947   // more than two fields.
5948   if (st->compare_is_identity(gogo) && st->total_field_count() > 2)
5949     return this->lower_compare_to_memcmp(gogo, inserter);
5950
5951   Location loc = this->location();
5952
5953   Expression* left = this->left_;
5954   Temporary_statement* left_temp = NULL;
5955   if (left->var_expression() == NULL
5956       && left->temporary_reference_expression() == NULL)
5957     {
5958       left_temp = Statement::make_temporary(left->type(), NULL, loc);
5959       inserter->insert(left_temp);
5960       left = Expression::make_set_and_use_temporary(left_temp, left, loc);
5961     }
5962
5963   Expression* right = this->right_;
5964   Temporary_statement* right_temp = NULL;
5965   if (right->var_expression() == NULL
5966       && right->temporary_reference_expression() == NULL)
5967     {
5968       right_temp = Statement::make_temporary(right->type(), NULL, loc);
5969       inserter->insert(right_temp);
5970       right = Expression::make_set_and_use_temporary(right_temp, right, loc);
5971     }
5972
5973   Expression* ret = Expression::make_boolean(true, loc);
5974   const Struct_field_list* fields = st->fields();
5975   unsigned int field_index = 0;
5976   for (Struct_field_list::const_iterator pf = fields->begin();
5977        pf != fields->end();
5978        ++pf, ++field_index)
5979     {
5980       if (field_index > 0)
5981         {
5982           if (left_temp == NULL)
5983             left = left->copy();
5984           else
5985             left = Expression::make_temporary_reference(left_temp, loc);
5986           if (right_temp == NULL)
5987             right = right->copy();
5988           else
5989             right = Expression::make_temporary_reference(right_temp, loc);
5990         }
5991       Expression* f1 = Expression::make_field_reference(left, field_index,
5992                                                         loc);
5993       Expression* f2 = Expression::make_field_reference(right, field_index,
5994                                                         loc);
5995       Expression* cond = Expression::make_binary(OPERATOR_EQEQ, f1, f2, loc);
5996       ret = Expression::make_binary(OPERATOR_ANDAND, ret, cond, loc);
5997     }
5998
5999   if (this->op_ == OPERATOR_NOTEQ)
6000     ret = Expression::make_unary(OPERATOR_NOT, ret, loc);
6001
6002   return ret;
6003 }
6004
6005 // Lower an array comparison.
6006
6007 Expression*
6008 Binary_expression::lower_array_comparison(Gogo* gogo,
6009                                           Statement_inserter* inserter)
6010 {
6011   Array_type* at = this->left_->type()->array_type();
6012   Array_type* at2 = this->right_->type()->array_type();
6013   if (at2 == NULL)
6014     return this;
6015   if (at != at2 && !Type::are_identical(at, at2, false, NULL))
6016     return this;
6017   if (!Type::are_compatible_for_comparison(true, this->left_->type(),
6018                                            this->right_->type(), NULL))
6019     return this;
6020
6021   // Call memcmp directly if possible.  This may let the middle-end
6022   // optimize the call.
6023   if (at->compare_is_identity(gogo))
6024     return this->lower_compare_to_memcmp(gogo, inserter);
6025
6026   // Call the array comparison function.
6027   Named_object* hash_fn;
6028   Named_object* equal_fn;
6029   at->type_functions(gogo, this->left_->type()->named_type(), NULL, NULL,
6030                      &hash_fn, &equal_fn);
6031
6032   Location loc = this->location();
6033
6034   Expression* func = Expression::make_func_reference(equal_fn, NULL, loc);
6035
6036   Expression_list* args = new Expression_list();
6037   args->push_back(this->operand_address(inserter, this->left_));
6038   args->push_back(this->operand_address(inserter, this->right_));
6039   args->push_back(Expression::make_type_info(at, TYPE_INFO_SIZE));
6040
6041   Expression* ret = Expression::make_call(func, args, false, loc);
6042
6043   if (this->op_ == OPERATOR_NOTEQ)
6044     ret = Expression::make_unary(OPERATOR_NOT, ret, loc);
6045
6046   return ret;
6047 }
6048
6049 // Lower a struct or array comparison to a call to memcmp.
6050
6051 Expression*
6052 Binary_expression::lower_compare_to_memcmp(Gogo*, Statement_inserter* inserter)
6053 {
6054   Location loc = this->location();
6055
6056   Expression* a1 = this->operand_address(inserter, this->left_);
6057   Expression* a2 = this->operand_address(inserter, this->right_);
6058   Expression* len = Expression::make_type_info(this->left_->type(),
6059                                                TYPE_INFO_SIZE);
6060
6061   Expression* call = Runtime::make_call(Runtime::MEMCMP, loc, 3, a1, a2, len);
6062
6063   mpz_t zval;
6064   mpz_init_set_ui(zval, 0);
6065   Expression* zero = Expression::make_integer(&zval, NULL, loc);
6066   mpz_clear(zval);
6067
6068   return Expression::make_binary(this->op_, call, zero, loc);
6069 }
6070
6071 // Return the address of EXPR, cast to unsafe.Pointer.
6072
6073 Expression*
6074 Binary_expression::operand_address(Statement_inserter* inserter,
6075                                    Expression* expr)
6076 {
6077   Location loc = this->location();
6078
6079   if (!expr->is_addressable())
6080     {
6081       Temporary_statement* temp = Statement::make_temporary(expr->type(), NULL,
6082                                                             loc);
6083       inserter->insert(temp);
6084       expr = Expression::make_set_and_use_temporary(temp, expr, loc);
6085     }
6086   expr = Expression::make_unary(OPERATOR_AND, expr, loc);
6087   static_cast<Unary_expression*>(expr)->set_does_not_escape();
6088   Type* void_type = Type::make_void_type();
6089   Type* unsafe_pointer_type = Type::make_pointer_type(void_type);
6090   return Expression::make_cast(unsafe_pointer_type, expr, loc);
6091 }
6092
6093 // Return the integer constant value, if it has one.
6094
6095 bool
6096 Binary_expression::do_integer_constant_value(bool iota_is_constant, mpz_t val,
6097                                              Type** ptype) const
6098 {
6099   mpz_t left_val;
6100   mpz_init(left_val);
6101   Type* left_type;
6102   if (!this->left_->integer_constant_value(iota_is_constant, left_val,
6103                                            &left_type))
6104     {
6105       mpz_clear(left_val);
6106       return false;
6107     }
6108
6109   mpz_t right_val;
6110   mpz_init(right_val);
6111   Type* right_type;
6112   if (!this->right_->integer_constant_value(iota_is_constant, right_val,
6113                                             &right_type))
6114     {
6115       mpz_clear(right_val);
6116       mpz_clear(left_val);
6117       return false;
6118     }
6119
6120   bool ret;
6121   if (left_type != right_type
6122       && left_type != NULL
6123       && right_type != NULL
6124       && left_type->base() != right_type->base()
6125       && this->op_ != OPERATOR_RSHIFT
6126       && this->op_ != OPERATOR_LSHIFT)
6127     ret = false;
6128   else
6129     ret = Binary_expression::eval_integer(this->op_, left_type, left_val,
6130                                           right_type, right_val,
6131                                           this->location(), val);
6132
6133   mpz_clear(right_val);
6134   mpz_clear(left_val);
6135
6136   if (ret)
6137     *ptype = left_type;
6138
6139   return ret;
6140 }
6141
6142 // Return the floating point constant value, if it has one.
6143
6144 bool
6145 Binary_expression::do_float_constant_value(mpfr_t val, Type** ptype) const
6146 {
6147   mpfr_t left_val;
6148   mpfr_init(left_val);
6149   Type* left_type;
6150   if (!this->left_->float_constant_value(left_val, &left_type))
6151     {
6152       mpfr_clear(left_val);
6153       return false;
6154     }
6155
6156   mpfr_t right_val;
6157   mpfr_init(right_val);
6158   Type* right_type;
6159   if (!this->right_->float_constant_value(right_val, &right_type))
6160     {
6161       mpfr_clear(right_val);
6162       mpfr_clear(left_val);
6163       return false;
6164     }
6165
6166   bool ret;
6167   if (left_type != right_type
6168       && left_type != NULL
6169       && right_type != NULL
6170       && left_type->base() != right_type->base())
6171     ret = false;
6172   else
6173     ret = Binary_expression::eval_float(this->op_, left_type, left_val,
6174                                         right_type, right_val,
6175                                         val, this->location());
6176
6177   mpfr_clear(left_val);
6178   mpfr_clear(right_val);
6179
6180   if (ret)
6181     *ptype = left_type;
6182
6183   return ret;
6184 }
6185
6186 // Return the complex constant value, if it has one.
6187
6188 bool
6189 Binary_expression::do_complex_constant_value(mpfr_t real, mpfr_t imag,
6190                                              Type** ptype) const
6191 {
6192   mpfr_t left_real;
6193   mpfr_t left_imag;
6194   mpfr_init(left_real);
6195   mpfr_init(left_imag);
6196   Type* left_type;
6197   if (!this->left_->complex_constant_value(left_real, left_imag, &left_type))
6198     {
6199       mpfr_clear(left_real);
6200       mpfr_clear(left_imag);
6201       return false;
6202     }
6203
6204   mpfr_t right_real;
6205   mpfr_t right_imag;
6206   mpfr_init(right_real);
6207   mpfr_init(right_imag);
6208   Type* right_type;
6209   if (!this->right_->complex_constant_value(right_real, right_imag,
6210                                             &right_type))
6211     {
6212       mpfr_clear(left_real);
6213       mpfr_clear(left_imag);
6214       mpfr_clear(right_real);
6215       mpfr_clear(right_imag);
6216       return false;
6217     }
6218
6219   bool ret;
6220   if (left_type != right_type
6221       && left_type != NULL
6222       && right_type != NULL
6223       && left_type->base() != right_type->base())
6224     ret = false;
6225   else
6226     ret = Binary_expression::eval_complex(this->op_, left_type,
6227                                           left_real, left_imag,
6228                                           right_type,
6229                                           right_real, right_imag,
6230                                           real, imag,
6231                                           this->location());
6232   mpfr_clear(left_real);
6233   mpfr_clear(left_imag);
6234   mpfr_clear(right_real);
6235   mpfr_clear(right_imag);
6236
6237   if (ret)
6238     *ptype = left_type;
6239
6240   return ret;
6241 }
6242
6243 // Note that the value is being discarded.
6244
6245 void
6246 Binary_expression::do_discarding_value()
6247 {
6248   if (this->op_ == OPERATOR_OROR || this->op_ == OPERATOR_ANDAND)
6249     this->right_->discarding_value();
6250   else
6251     this->unused_value_error();
6252 }
6253
6254 // Get type.
6255
6256 Type*
6257 Binary_expression::do_type()
6258 {
6259   if (this->classification() == EXPRESSION_ERROR)
6260     return Type::make_error_type();
6261
6262   switch (this->op_)
6263     {
6264     case OPERATOR_OROR:
6265     case OPERATOR_ANDAND:
6266     case OPERATOR_EQEQ:
6267     case OPERATOR_NOTEQ:
6268     case OPERATOR_LT:
6269     case OPERATOR_LE:
6270     case OPERATOR_GT:
6271     case OPERATOR_GE:
6272       return Type::lookup_bool_type();
6273
6274     case OPERATOR_PLUS:
6275     case OPERATOR_MINUS:
6276     case OPERATOR_OR:
6277     case OPERATOR_XOR:
6278     case OPERATOR_MULT:
6279     case OPERATOR_DIV:
6280     case OPERATOR_MOD:
6281     case OPERATOR_AND:
6282     case OPERATOR_BITCLEAR:
6283       {
6284         Type* left_type = this->left_->type();
6285         Type* right_type = this->right_->type();
6286         if (left_type->is_error())
6287           return left_type;
6288         else if (right_type->is_error())
6289           return right_type;
6290         else if (!Type::are_compatible_for_binop(left_type, right_type))
6291           {
6292             this->report_error(_("incompatible types in binary expression"));
6293             return Type::make_error_type();
6294           }
6295         else if (!left_type->is_abstract() && left_type->named_type() != NULL)
6296           return left_type;
6297         else if (!right_type->is_abstract() && right_type->named_type() != NULL)
6298           return right_type;
6299         else if (!left_type->is_abstract())
6300           return left_type;
6301         else if (!right_type->is_abstract())
6302           return right_type;
6303         else if (left_type->complex_type() != NULL)
6304           return left_type;
6305         else if (right_type->complex_type() != NULL)
6306           return right_type;
6307         else if (left_type->float_type() != NULL)
6308           return left_type;
6309         else if (right_type->float_type() != NULL)
6310           return right_type;
6311         else if (left_type->integer_type() != NULL
6312                  && left_type->integer_type()->is_rune())
6313           return left_type;
6314         else if (right_type->integer_type() != NULL
6315                  && right_type->integer_type()->is_rune())
6316           return right_type;
6317         else
6318           return left_type;
6319       }
6320
6321     case OPERATOR_LSHIFT:
6322     case OPERATOR_RSHIFT:
6323       return this->left_->type();
6324
6325     default:
6326       go_unreachable();
6327     }
6328 }
6329
6330 // Set type for a binary expression.
6331
6332 void
6333 Binary_expression::do_determine_type(const Type_context* context)
6334 {
6335   Type* tleft = this->left_->type();
6336   Type* tright = this->right_->type();
6337
6338   // Both sides should have the same type, except for the shift
6339   // operations.  For a comparison, we should ignore the incoming
6340   // type.
6341
6342   bool is_shift_op = (this->op_ == OPERATOR_LSHIFT
6343                       || this->op_ == OPERATOR_RSHIFT);
6344
6345   bool is_comparison = (this->op_ == OPERATOR_EQEQ
6346                         || this->op_ == OPERATOR_NOTEQ
6347                         || this->op_ == OPERATOR_LT
6348                         || this->op_ == OPERATOR_LE
6349                         || this->op_ == OPERATOR_GT
6350                         || this->op_ == OPERATOR_GE);
6351
6352   Type_context subcontext(*context);
6353
6354   if (is_comparison)
6355     {
6356       // In a comparison, the context does not determine the types of
6357       // the operands.
6358       subcontext.type = NULL;
6359     }
6360
6361   // Set the context for the left hand operand.
6362   if (is_shift_op)
6363     {
6364       // The right hand operand of a shift plays no role in
6365       // determining the type of the left hand operand.
6366     }
6367   else if (!tleft->is_abstract())
6368     subcontext.type = tleft;
6369   else if (!tright->is_abstract())
6370     subcontext.type = tright;
6371   else if (subcontext.type == NULL)
6372     {
6373       if ((tleft->integer_type() != NULL && tright->integer_type() != NULL)
6374           || (tleft->float_type() != NULL && tright->float_type() != NULL)
6375           || (tleft->complex_type() != NULL && tright->complex_type() != NULL))
6376         {
6377           // Both sides have an abstract integer, abstract float, or
6378           // abstract complex type.  Just let CONTEXT determine
6379           // whether they may remain abstract or not.
6380         }
6381       else if (tleft->complex_type() != NULL)
6382         subcontext.type = tleft;
6383       else if (tright->complex_type() != NULL)
6384         subcontext.type = tright;
6385       else if (tleft->float_type() != NULL)
6386         subcontext.type = tleft;
6387       else if (tright->float_type() != NULL)
6388         subcontext.type = tright;
6389       else
6390         subcontext.type = tleft;
6391
6392       if (subcontext.type != NULL && !context->may_be_abstract)
6393         subcontext.type = subcontext.type->make_non_abstract_type();
6394     }
6395
6396   this->left_->determine_type(&subcontext);
6397
6398   if (is_shift_op)
6399     {
6400       // We may have inherited an unusable type for the shift operand.
6401       // Give a useful error if that happened.
6402       if (tleft->is_abstract()
6403           && subcontext.type != NULL
6404           && (this->left_->type()->integer_type() == NULL
6405               || (subcontext.type->integer_type() == NULL
6406                   && subcontext.type->float_type() == NULL
6407                   && subcontext.type->complex_type() == NULL)))
6408         this->report_error(("invalid context-determined non-integer type "
6409                             "for shift operand"));
6410
6411       // The context for the right hand operand is the same as for the
6412       // left hand operand, except for a shift operator.
6413       subcontext.type = Type::lookup_integer_type("uint");
6414       subcontext.may_be_abstract = false;
6415     }
6416
6417   this->right_->determine_type(&subcontext);
6418 }
6419
6420 // Report an error if the binary operator OP does not support TYPE.
6421 // OTYPE is the type of the other operand.  Return whether the
6422 // operation is OK.  This should not be used for shift.
6423
6424 bool
6425 Binary_expression::check_operator_type(Operator op, Type* type, Type* otype,
6426                                        Location location)
6427 {
6428   switch (op)
6429     {
6430     case OPERATOR_OROR:
6431     case OPERATOR_ANDAND:
6432       if (!type->is_boolean_type())
6433         {
6434           error_at(location, "expected boolean type");
6435           return false;
6436         }
6437       break;
6438
6439     case OPERATOR_EQEQ:
6440     case OPERATOR_NOTEQ:
6441       {
6442         std::string reason;
6443         if (!Type::are_compatible_for_comparison(true, type, otype, &reason))
6444           {
6445             error_at(location, "%s", reason.c_str());
6446             return false;
6447           }
6448       }
6449       break;
6450
6451     case OPERATOR_LT:
6452     case OPERATOR_LE:
6453     case OPERATOR_GT:
6454     case OPERATOR_GE:
6455       {
6456         std::string reason;
6457         if (!Type::are_compatible_for_comparison(false, type, otype, &reason))
6458           {
6459             error_at(location, "%s", reason.c_str());
6460             return false;
6461           }
6462       }
6463       break;
6464
6465     case OPERATOR_PLUS:
6466     case OPERATOR_PLUSEQ:
6467       if (type->integer_type() == NULL
6468           && type->float_type() == NULL
6469           && type->complex_type() == NULL
6470           && !type->is_string_type())
6471         {
6472           error_at(location,
6473                    "expected integer, floating, complex, or string type");
6474           return false;
6475         }
6476       break;
6477
6478     case OPERATOR_MINUS:
6479     case OPERATOR_MINUSEQ:
6480     case OPERATOR_MULT:
6481     case OPERATOR_MULTEQ:
6482     case OPERATOR_DIV:
6483     case OPERATOR_DIVEQ:
6484       if (type->integer_type() == NULL
6485           && type->float_type() == NULL
6486           && type->complex_type() == NULL)
6487         {
6488           error_at(location, "expected integer, floating, or complex type");
6489           return false;
6490         }
6491       break;
6492
6493     case OPERATOR_MOD:
6494     case OPERATOR_MODEQ:
6495     case OPERATOR_OR:
6496     case OPERATOR_OREQ:
6497     case OPERATOR_AND:
6498     case OPERATOR_ANDEQ:
6499     case OPERATOR_XOR:
6500     case OPERATOR_XOREQ:
6501     case OPERATOR_BITCLEAR:
6502     case OPERATOR_BITCLEAREQ:
6503       if (type->integer_type() == NULL)
6504         {
6505           error_at(location, "expected integer type");
6506           return false;
6507         }
6508       break;
6509
6510     default:
6511       go_unreachable();
6512     }
6513
6514   return true;
6515 }
6516
6517 // Check types.
6518
6519 void
6520 Binary_expression::do_check_types(Gogo*)
6521 {
6522   if (this->classification() == EXPRESSION_ERROR)
6523     return;
6524
6525   Type* left_type = this->left_->type();
6526   Type* right_type = this->right_->type();
6527   if (left_type->is_error() || right_type->is_error())
6528     {
6529       this->set_is_error();
6530       return;
6531     }
6532
6533   if (this->op_ == OPERATOR_EQEQ
6534       || this->op_ == OPERATOR_NOTEQ
6535       || this->op_ == OPERATOR_LT
6536       || this->op_ == OPERATOR_LE
6537       || this->op_ == OPERATOR_GT
6538       || this->op_ == OPERATOR_GE)
6539     {
6540       if (!Type::are_assignable(left_type, right_type, NULL)
6541           && !Type::are_assignable(right_type, left_type, NULL))
6542         {
6543           this->report_error(_("incompatible types in binary expression"));
6544           return;
6545         }
6546       if (!Binary_expression::check_operator_type(this->op_, left_type,
6547                                                   right_type,
6548                                                   this->location())
6549           || !Binary_expression::check_operator_type(this->op_, right_type,
6550                                                      left_type,
6551                                                      this->location()))
6552         {
6553           this->set_is_error();
6554           return;
6555         }
6556     }
6557   else if (this->op_ != OPERATOR_LSHIFT && this->op_ != OPERATOR_RSHIFT)
6558     {
6559       if (!Type::are_compatible_for_binop(left_type, right_type))
6560         {
6561           this->report_error(_("incompatible types in binary expression"));
6562           return;
6563         }
6564       if (!Binary_expression::check_operator_type(this->op_, left_type,
6565                                                   right_type,
6566                                                   this->location()))
6567         {
6568           this->set_is_error();
6569           return;
6570         }
6571     }
6572   else
6573     {
6574       if (left_type->integer_type() == NULL)
6575         this->report_error(_("shift of non-integer operand"));
6576
6577       if (!right_type->is_abstract()
6578           && (right_type->integer_type() == NULL
6579               || !right_type->integer_type()->is_unsigned()))
6580         this->report_error(_("shift count not unsigned integer"));
6581       else
6582         {
6583           mpz_t val;
6584           mpz_init(val);
6585           Type* type;
6586           if (this->right_->integer_constant_value(true, val, &type))
6587             {
6588               if (mpz_sgn(val) < 0)
6589                 {
6590                   this->report_error(_("negative shift count"));
6591                   mpz_set_ui(val, 0);
6592                   Location rloc = this->right_->location();
6593                   this->right_ = Expression::make_integer(&val, right_type,
6594                                                           rloc);
6595                 }
6596             }
6597           mpz_clear(val);
6598         }
6599     }
6600 }
6601
6602 // Get a tree for a binary expression.
6603
6604 tree
6605 Binary_expression::do_get_tree(Translate_context* context)
6606 {
6607   tree left = this->left_->get_tree(context);
6608   tree right = this->right_->get_tree(context);
6609
6610   if (left == error_mark_node || right == error_mark_node)
6611     return error_mark_node;
6612
6613   enum tree_code code;
6614   bool use_left_type = true;
6615   bool is_shift_op = false;
6616   switch (this->op_)
6617     {
6618     case OPERATOR_EQEQ:
6619     case OPERATOR_NOTEQ:
6620     case OPERATOR_LT:
6621     case OPERATOR_LE:
6622     case OPERATOR_GT:
6623     case OPERATOR_GE:
6624       return Expression::comparison_tree(context, this->op_,
6625                                          this->left_->type(), left,
6626                                          this->right_->type(), right,
6627                                          this->location());
6628
6629     case OPERATOR_OROR:
6630       code = TRUTH_ORIF_EXPR;
6631       use_left_type = false;
6632       break;
6633     case OPERATOR_ANDAND:
6634       code = TRUTH_ANDIF_EXPR;
6635       use_left_type = false;
6636       break;
6637     case OPERATOR_PLUS:
6638       code = PLUS_EXPR;
6639       break;
6640     case OPERATOR_MINUS:
6641       code = MINUS_EXPR;
6642       break;
6643     case OPERATOR_OR:
6644       code = BIT_IOR_EXPR;
6645       break;
6646     case OPERATOR_XOR:
6647       code = BIT_XOR_EXPR;
6648       break;
6649     case OPERATOR_MULT:
6650       code = MULT_EXPR;
6651       break;
6652     case OPERATOR_DIV:
6653       {
6654         Type *t = this->left_->type();
6655         if (t->float_type() != NULL || t->complex_type() != NULL)
6656           code = RDIV_EXPR;
6657         else
6658           code = TRUNC_DIV_EXPR;
6659       }
6660       break;
6661     case OPERATOR_MOD:
6662       code = TRUNC_MOD_EXPR;
6663       break;
6664     case OPERATOR_LSHIFT:
6665       code = LSHIFT_EXPR;
6666       is_shift_op = true;
6667       break;
6668     case OPERATOR_RSHIFT:
6669       code = RSHIFT_EXPR;
6670       is_shift_op = true;
6671       break;
6672     case OPERATOR_AND:
6673       code = BIT_AND_EXPR;
6674       break;
6675     case OPERATOR_BITCLEAR:
6676       right = fold_build1(BIT_NOT_EXPR, TREE_TYPE(right), right);
6677       code = BIT_AND_EXPR;
6678       break;
6679     default:
6680       go_unreachable();
6681     }
6682
6683   tree type = use_left_type ? TREE_TYPE(left) : TREE_TYPE(right);
6684
6685   if (this->left_->type()->is_string_type())
6686     {
6687       go_assert(this->op_ == OPERATOR_PLUS);
6688       Type* st = Type::make_string_type();
6689       tree string_type = type_to_tree(st->get_backend(context->gogo()));
6690       static tree string_plus_decl;
6691       return Gogo::call_builtin(&string_plus_decl,
6692                                 this->location(),
6693                                 "__go_string_plus",
6694                                 2,
6695                                 string_type,
6696                                 string_type,
6697                                 left,
6698                                 string_type,
6699                                 right);
6700     }
6701
6702   tree compute_type = excess_precision_type(type);
6703   if (compute_type != NULL_TREE)
6704     {
6705       left = ::convert(compute_type, left);
6706       right = ::convert(compute_type, right);
6707     }
6708
6709   tree eval_saved = NULL_TREE;
6710   if (is_shift_op)
6711     {
6712       // Make sure the values are evaluated.
6713       if (!DECL_P(left) && TREE_SIDE_EFFECTS(left))
6714         {
6715           left = save_expr(left);
6716           eval_saved = left;
6717         }
6718       if (!DECL_P(right) && TREE_SIDE_EFFECTS(right))
6719         {
6720           right = save_expr(right);
6721           if (eval_saved == NULL_TREE)
6722             eval_saved = right;
6723           else
6724             eval_saved = fold_build2_loc(this->location().gcc_location(),
6725                                          COMPOUND_EXPR,
6726                                          void_type_node, eval_saved, right);
6727         }
6728     }
6729
6730   tree ret = fold_build2_loc(this->location().gcc_location(),
6731                              code,
6732                              compute_type != NULL_TREE ? compute_type : type,
6733                              left, right);
6734
6735   if (compute_type != NULL_TREE)
6736     ret = ::convert(type, ret);
6737
6738   // In Go, a shift larger than the size of the type is well-defined.
6739   // This is not true in GENERIC, so we need to insert a conditional.
6740   if (is_shift_op)
6741     {
6742       go_assert(INTEGRAL_TYPE_P(TREE_TYPE(left)));
6743       go_assert(this->left_->type()->integer_type() != NULL);
6744       int bits = TYPE_PRECISION(TREE_TYPE(left));
6745
6746       tree compare = fold_build2(LT_EXPR, boolean_type_node, right,
6747                                  build_int_cst_type(TREE_TYPE(right), bits));
6748
6749       tree overflow_result = fold_convert_loc(this->location().gcc_location(),
6750                                               TREE_TYPE(left),
6751                                               integer_zero_node);
6752       if (this->op_ == OPERATOR_RSHIFT
6753           && !this->left_->type()->integer_type()->is_unsigned())
6754         {
6755           tree neg =
6756             fold_build2_loc(this->location().gcc_location(), LT_EXPR,
6757                             boolean_type_node, left,
6758                             fold_convert_loc(this->location().gcc_location(),
6759                                              TREE_TYPE(left),
6760                                              integer_zero_node));
6761           tree neg_one =
6762             fold_build2_loc(this->location().gcc_location(),
6763                             MINUS_EXPR, TREE_TYPE(left),
6764                             fold_convert_loc(this->location().gcc_location(),
6765                                              TREE_TYPE(left),
6766                                              integer_zero_node),
6767                             fold_convert_loc(this->location().gcc_location(),
6768                                              TREE_TYPE(left),
6769                                              integer_one_node));
6770           overflow_result =
6771             fold_build3_loc(this->location().gcc_location(), COND_EXPR,
6772                             TREE_TYPE(left), neg, neg_one,
6773                             overflow_result);
6774         }
6775
6776       ret = fold_build3_loc(this->location().gcc_location(), COND_EXPR,
6777                             TREE_TYPE(left), compare, ret, overflow_result);
6778
6779       if (eval_saved != NULL_TREE)
6780         ret = fold_build2_loc(this->location().gcc_location(), COMPOUND_EXPR,
6781                               TREE_TYPE(ret), eval_saved, ret);
6782     }
6783
6784   return ret;
6785 }
6786
6787 // Export a binary expression.
6788
6789 void
6790 Binary_expression::do_export(Export* exp) const
6791 {
6792   exp->write_c_string("(");
6793   this->left_->export_expression(exp);
6794   switch (this->op_)
6795     {
6796     case OPERATOR_OROR:
6797       exp->write_c_string(" || ");
6798       break;
6799     case OPERATOR_ANDAND:
6800       exp->write_c_string(" && ");
6801       break;
6802     case OPERATOR_EQEQ:
6803       exp->write_c_string(" == ");
6804       break;
6805     case OPERATOR_NOTEQ:
6806       exp->write_c_string(" != ");
6807       break;
6808     case OPERATOR_LT:
6809       exp->write_c_string(" < ");
6810       break;
6811     case OPERATOR_LE:
6812       exp->write_c_string(" <= ");
6813       break;
6814     case OPERATOR_GT:
6815       exp->write_c_string(" > ");
6816       break;
6817     case OPERATOR_GE:
6818       exp->write_c_string(" >= ");
6819       break;
6820     case OPERATOR_PLUS:
6821       exp->write_c_string(" + ");
6822       break;
6823     case OPERATOR_MINUS:
6824       exp->write_c_string(" - ");
6825       break;
6826     case OPERATOR_OR:
6827       exp->write_c_string(" | ");
6828       break;
6829     case OPERATOR_XOR:
6830       exp->write_c_string(" ^ ");
6831       break;
6832     case OPERATOR_MULT:
6833       exp->write_c_string(" * ");
6834       break;
6835     case OPERATOR_DIV:
6836       exp->write_c_string(" / ");
6837       break;
6838     case OPERATOR_MOD:
6839       exp->write_c_string(" % ");
6840       break;
6841     case OPERATOR_LSHIFT:
6842       exp->write_c_string(" << ");
6843       break;
6844     case OPERATOR_RSHIFT:
6845       exp->write_c_string(" >> ");
6846       break;
6847     case OPERATOR_AND:
6848       exp->write_c_string(" & ");
6849       break;
6850     case OPERATOR_BITCLEAR:
6851       exp->write_c_string(" &^ ");
6852       break;
6853     default:
6854       go_unreachable();
6855     }
6856   this->right_->export_expression(exp);
6857   exp->write_c_string(")");
6858 }
6859
6860 // Import a binary expression.
6861
6862 Expression*
6863 Binary_expression::do_import(Import* imp)
6864 {
6865   imp->require_c_string("(");
6866
6867   Expression* left = Expression::import_expression(imp);
6868
6869   Operator op;
6870   if (imp->match_c_string(" || "))
6871     {
6872       op = OPERATOR_OROR;
6873       imp->advance(4);
6874     }
6875   else if (imp->match_c_string(" && "))
6876     {
6877       op = OPERATOR_ANDAND;
6878       imp->advance(4);
6879     }
6880   else if (imp->match_c_string(" == "))
6881     {
6882       op = OPERATOR_EQEQ;
6883       imp->advance(4);
6884     }
6885   else if (imp->match_c_string(" != "))
6886     {
6887       op = OPERATOR_NOTEQ;
6888       imp->advance(4);
6889     }
6890   else if (imp->match_c_string(" < "))
6891     {
6892       op = OPERATOR_LT;
6893       imp->advance(3);
6894     }
6895   else if (imp->match_c_string(" <= "))
6896     {
6897       op = OPERATOR_LE;
6898       imp->advance(4);
6899     }
6900   else if (imp->match_c_string(" > "))
6901     {
6902       op = OPERATOR_GT;
6903       imp->advance(3);
6904     }
6905   else if (imp->match_c_string(" >= "))
6906     {
6907       op = OPERATOR_GE;
6908       imp->advance(4);
6909     }
6910   else if (imp->match_c_string(" + "))
6911     {
6912       op = OPERATOR_PLUS;
6913       imp->advance(3);
6914     }
6915   else if (imp->match_c_string(" - "))
6916     {
6917       op = OPERATOR_MINUS;
6918       imp->advance(3);
6919     }
6920   else if (imp->match_c_string(" | "))
6921     {
6922       op = OPERATOR_OR;
6923       imp->advance(3);
6924     }
6925   else if (imp->match_c_string(" ^ "))
6926     {
6927       op = OPERATOR_XOR;
6928       imp->advance(3);
6929     }
6930   else if (imp->match_c_string(" * "))
6931     {
6932       op = OPERATOR_MULT;
6933       imp->advance(3);
6934     }
6935   else if (imp->match_c_string(" / "))
6936     {
6937       op = OPERATOR_DIV;
6938       imp->advance(3);
6939     }
6940   else if (imp->match_c_string(" % "))
6941     {
6942       op = OPERATOR_MOD;
6943       imp->advance(3);
6944     }
6945   else if (imp->match_c_string(" << "))
6946     {
6947       op = OPERATOR_LSHIFT;
6948       imp->advance(4);
6949     }
6950   else if (imp->match_c_string(" >> "))
6951     {
6952       op = OPERATOR_RSHIFT;
6953       imp->advance(4);
6954     }
6955   else if (imp->match_c_string(" & "))
6956     {
6957       op = OPERATOR_AND;
6958       imp->advance(3);
6959     }
6960   else if (imp->match_c_string(" &^ "))
6961     {
6962       op = OPERATOR_BITCLEAR;
6963       imp->advance(4);
6964     }
6965   else
6966     {
6967       error_at(imp->location(), "unrecognized binary operator");
6968       return Expression::make_error(imp->location());
6969     }
6970
6971   Expression* right = Expression::import_expression(imp);
6972
6973   imp->require_c_string(")");
6974
6975   return Expression::make_binary(op, left, right, imp->location());
6976 }
6977
6978 // Dump ast representation of a binary expression.
6979
6980 void
6981 Binary_expression::do_dump_expression(Ast_dump_context* ast_dump_context) const
6982 {
6983   ast_dump_context->ostream() << "(";
6984   ast_dump_context->dump_expression(this->left_);
6985   ast_dump_context->ostream() << " ";
6986   ast_dump_context->dump_operator(this->op_);
6987   ast_dump_context->ostream() << " ";
6988   ast_dump_context->dump_expression(this->right_);
6989   ast_dump_context->ostream() << ") ";
6990 }
6991
6992 // Make a binary expression.
6993
6994 Expression*
6995 Expression::make_binary(Operator op, Expression* left, Expression* right,
6996                         Location location)
6997 {
6998   return new Binary_expression(op, left, right, location);
6999 }
7000
7001 // Implement a comparison.
7002
7003 tree
7004 Expression::comparison_tree(Translate_context* context, Operator op,
7005                             Type* left_type, tree left_tree,
7006                             Type* right_type, tree right_tree,
7007                             Location location)
7008 {
7009   enum tree_code code;
7010   switch (op)
7011     {
7012     case OPERATOR_EQEQ:
7013       code = EQ_EXPR;
7014       break;
7015     case OPERATOR_NOTEQ:
7016       code = NE_EXPR;
7017       break;
7018     case OPERATOR_LT:
7019       code = LT_EXPR;
7020       break;
7021     case OPERATOR_LE:
7022       code = LE_EXPR;
7023       break;
7024     case OPERATOR_GT:
7025       code = GT_EXPR;
7026       break;
7027     case OPERATOR_GE:
7028       code = GE_EXPR;
7029       break;
7030     default:
7031       go_unreachable();
7032     }
7033
7034   if (left_type->is_string_type() && right_type->is_string_type())
7035     {
7036       Type* st = Type::make_string_type();
7037       tree string_type = type_to_tree(st->get_backend(context->gogo()));
7038       static tree string_compare_decl;
7039       left_tree = Gogo::call_builtin(&string_compare_decl,
7040                                      location,
7041                                      "__go_strcmp",
7042                                      2,
7043                                      integer_type_node,
7044                                      string_type,
7045                                      left_tree,
7046                                      string_type,
7047                                      right_tree);
7048       right_tree = build_int_cst_type(integer_type_node, 0);
7049     }
7050   else if ((left_type->interface_type() != NULL
7051             && right_type->interface_type() == NULL
7052             && !right_type->is_nil_type())
7053            || (left_type->interface_type() == NULL
7054                && !left_type->is_nil_type()
7055                && right_type->interface_type() != NULL))
7056     {
7057       // Comparing an interface value to a non-interface value.
7058       if (left_type->interface_type() == NULL)
7059         {
7060           std::swap(left_type, right_type);
7061           std::swap(left_tree, right_tree);
7062         }
7063
7064       // The right operand is not an interface.  We need to take its
7065       // address if it is not a pointer.
7066       tree make_tmp;
7067       tree arg;
7068       if (right_type->points_to() != NULL)
7069         {
7070           make_tmp = NULL_TREE;
7071           arg = right_tree;
7072         }
7073       else if (TREE_ADDRESSABLE(TREE_TYPE(right_tree)) || DECL_P(right_tree))
7074         {
7075           make_tmp = NULL_TREE;
7076           arg = build_fold_addr_expr_loc(location.gcc_location(), right_tree);
7077           if (DECL_P(right_tree))
7078             TREE_ADDRESSABLE(right_tree) = 1;
7079         }
7080       else
7081         {
7082           tree tmp = create_tmp_var(TREE_TYPE(right_tree),
7083                                     get_name(right_tree));
7084           DECL_IGNORED_P(tmp) = 0;
7085           DECL_INITIAL(tmp) = right_tree;
7086           TREE_ADDRESSABLE(tmp) = 1;
7087           make_tmp = build1(DECL_EXPR, void_type_node, tmp);
7088           SET_EXPR_LOCATION(make_tmp, location.gcc_location());
7089           arg = build_fold_addr_expr_loc(location.gcc_location(), tmp);
7090         }
7091       arg = fold_convert_loc(location.gcc_location(), ptr_type_node, arg);
7092
7093       tree descriptor = right_type->type_descriptor_pointer(context->gogo(),
7094                                                             location);
7095
7096       if (left_type->interface_type()->is_empty())
7097         {
7098           static tree empty_interface_value_compare_decl;
7099           left_tree = Gogo::call_builtin(&empty_interface_value_compare_decl,
7100                                          location,
7101                                          "__go_empty_interface_value_compare",
7102                                          3,
7103                                          integer_type_node,
7104                                          TREE_TYPE(left_tree),
7105                                          left_tree,
7106                                          TREE_TYPE(descriptor),
7107                                          descriptor,
7108                                          ptr_type_node,
7109                                          arg);
7110           if (left_tree == error_mark_node)
7111             return error_mark_node;
7112           // This can panic if the type is not comparable.
7113           TREE_NOTHROW(empty_interface_value_compare_decl) = 0;
7114         }
7115       else
7116         {
7117           static tree interface_value_compare_decl;
7118           left_tree = Gogo::call_builtin(&interface_value_compare_decl,
7119                                          location,
7120                                          "__go_interface_value_compare",
7121                                          3,
7122                                          integer_type_node,
7123                                          TREE_TYPE(left_tree),
7124                                          left_tree,
7125                                          TREE_TYPE(descriptor),
7126                                          descriptor,
7127                                          ptr_type_node,
7128                                          arg);
7129           if (left_tree == error_mark_node)
7130             return error_mark_node;
7131           // This can panic if the type is not comparable.
7132           TREE_NOTHROW(interface_value_compare_decl) = 0;
7133         }
7134       right_tree = build_int_cst_type(integer_type_node, 0);
7135
7136       if (make_tmp != NULL_TREE)
7137         left_tree = build2(COMPOUND_EXPR, TREE_TYPE(left_tree), make_tmp,
7138                            left_tree);
7139     }
7140   else if (left_type->interface_type() != NULL
7141            && right_type->interface_type() != NULL)
7142     {
7143       if (left_type->interface_type()->is_empty()
7144           && right_type->interface_type()->is_empty())
7145         {
7146           static tree empty_interface_compare_decl;
7147           left_tree = Gogo::call_builtin(&empty_interface_compare_decl,
7148                                          location,
7149                                          "__go_empty_interface_compare",
7150                                          2,
7151                                          integer_type_node,
7152                                          TREE_TYPE(left_tree),
7153                                          left_tree,
7154                                          TREE_TYPE(right_tree),
7155                                          right_tree);
7156           if (left_tree == error_mark_node)
7157             return error_mark_node;
7158           // This can panic if the type is uncomparable.
7159           TREE_NOTHROW(empty_interface_compare_decl) = 0;
7160         }
7161       else if (!left_type->interface_type()->is_empty()
7162                && !right_type->interface_type()->is_empty())
7163         {
7164           static tree interface_compare_decl;
7165           left_tree = Gogo::call_builtin(&interface_compare_decl,
7166                                          location,
7167                                          "__go_interface_compare",
7168                                          2,
7169                                          integer_type_node,
7170                                          TREE_TYPE(left_tree),
7171                                          left_tree,
7172                                          TREE_TYPE(right_tree),
7173                                          right_tree);
7174           if (left_tree == error_mark_node)
7175             return error_mark_node;
7176           // This can panic if the type is uncomparable.
7177           TREE_NOTHROW(interface_compare_decl) = 0;
7178         }
7179       else
7180         {
7181           if (left_type->interface_type()->is_empty())
7182             {
7183               go_assert(op == OPERATOR_EQEQ || op == OPERATOR_NOTEQ);
7184               std::swap(left_type, right_type);
7185               std::swap(left_tree, right_tree);
7186             }
7187           go_assert(!left_type->interface_type()->is_empty());
7188           go_assert(right_type->interface_type()->is_empty());
7189           static tree interface_empty_compare_decl;
7190           left_tree = Gogo::call_builtin(&interface_empty_compare_decl,
7191                                          location,
7192                                          "__go_interface_empty_compare",
7193                                          2,
7194                                          integer_type_node,
7195                                          TREE_TYPE(left_tree),
7196                                          left_tree,
7197                                          TREE_TYPE(right_tree),
7198                                          right_tree);
7199           if (left_tree == error_mark_node)
7200             return error_mark_node;
7201           // This can panic if the type is uncomparable.
7202           TREE_NOTHROW(interface_empty_compare_decl) = 0;
7203         }
7204
7205       right_tree = build_int_cst_type(integer_type_node, 0);
7206     }
7207
7208   if (left_type->is_nil_type()
7209       && (op == OPERATOR_EQEQ || op == OPERATOR_NOTEQ))
7210     {
7211       std::swap(left_type, right_type);
7212       std::swap(left_tree, right_tree);
7213     }
7214
7215   if (right_type->is_nil_type())
7216     {
7217       if (left_type->array_type() != NULL
7218           && left_type->array_type()->length() == NULL)
7219         {
7220           Array_type* at = left_type->array_type();
7221           left_tree = at->value_pointer_tree(context->gogo(), left_tree);
7222           right_tree = fold_convert(TREE_TYPE(left_tree), null_pointer_node);
7223         }
7224       else if (left_type->interface_type() != NULL)
7225         {
7226           // An interface is nil if the first field is nil.
7227           tree left_type_tree = TREE_TYPE(left_tree);
7228           go_assert(TREE_CODE(left_type_tree) == RECORD_TYPE);
7229           tree field = TYPE_FIELDS(left_type_tree);
7230           left_tree = build3(COMPONENT_REF, TREE_TYPE(field), left_tree,
7231                              field, NULL_TREE);
7232           right_tree = fold_convert(TREE_TYPE(left_tree), null_pointer_node);
7233         }
7234       else
7235         {
7236           go_assert(POINTER_TYPE_P(TREE_TYPE(left_tree)));
7237           right_tree = fold_convert(TREE_TYPE(left_tree), null_pointer_node);
7238         }
7239     }
7240
7241   if (left_tree == error_mark_node || right_tree == error_mark_node)
7242     return error_mark_node;
7243
7244   tree ret = fold_build2(code, boolean_type_node, left_tree, right_tree);
7245   if (CAN_HAVE_LOCATION_P(ret))
7246     SET_EXPR_LOCATION(ret, location.gcc_location());
7247   return ret;
7248 }
7249
7250 // Class Bound_method_expression.
7251
7252 // Traversal.
7253
7254 int
7255 Bound_method_expression::do_traverse(Traverse* traverse)
7256 {
7257   return Expression::traverse(&this->expr_, traverse);
7258 }
7259
7260 // Return the type of a bound method expression.  The type of this
7261 // object is really the type of the method with no receiver.  We
7262 // should be able to get away with just returning the type of the
7263 // method.
7264
7265 Type*
7266 Bound_method_expression::do_type()
7267 {
7268   if (this->method_->is_function())
7269     return this->method_->func_value()->type();
7270   else if (this->method_->is_function_declaration())
7271     return this->method_->func_declaration_value()->type();
7272   else
7273     return Type::make_error_type();
7274 }
7275
7276 // Determine the types of a method expression.
7277
7278 void
7279 Bound_method_expression::do_determine_type(const Type_context*)
7280 {
7281   Function_type* fntype = this->type()->function_type();
7282   if (fntype == NULL || !fntype->is_method())
7283     this->expr_->determine_type_no_context();
7284   else
7285     {
7286       Type_context subcontext(fntype->receiver()->type(), false);
7287       this->expr_->determine_type(&subcontext);
7288     }
7289 }
7290
7291 // Check the types of a method expression.
7292
7293 void
7294 Bound_method_expression::do_check_types(Gogo*)
7295 {
7296   if (!this->method_->is_function()
7297       && !this->method_->is_function_declaration())
7298     this->report_error(_("object is not a method"));
7299   else
7300     {
7301       Type* rtype = this->type()->function_type()->receiver()->type()->deref();
7302       Type* etype = (this->expr_type_ != NULL
7303                      ? this->expr_type_
7304                      : this->expr_->type());
7305       etype = etype->deref();
7306       if (!Type::are_identical(rtype, etype, true, NULL))
7307         this->report_error(_("method type does not match object type"));
7308     }
7309 }
7310
7311 // Get the tree for a method expression.  There is no standard tree
7312 // representation for this.  The only places it may currently be used
7313 // are in a Call_expression or a Go_statement, which will take it
7314 // apart directly.  So this has nothing to do at present.
7315
7316 tree
7317 Bound_method_expression::do_get_tree(Translate_context*)
7318 {
7319   error_at(this->location(), "reference to method other than calling it");
7320   return error_mark_node;
7321 }
7322
7323 // Dump ast representation of a bound method expression.
7324
7325 void
7326 Bound_method_expression::do_dump_expression(Ast_dump_context* ast_dump_context)
7327     const
7328 {
7329   if (this->expr_type_ != NULL)
7330     ast_dump_context->ostream() << "(";
7331   ast_dump_context->dump_expression(this->expr_);
7332   if (this->expr_type_ != NULL)
7333     {
7334       ast_dump_context->ostream() << ":";
7335       ast_dump_context->dump_type(this->expr_type_);
7336       ast_dump_context->ostream() << ")";
7337     }
7338
7339   ast_dump_context->ostream() << "." << this->method_->name();
7340 }
7341
7342 // Make a method expression.
7343
7344 Bound_method_expression*
7345 Expression::make_bound_method(Expression* expr, Named_object* method,
7346                               Location location)
7347 {
7348   return new Bound_method_expression(expr, method, location);
7349 }
7350
7351 // Class Builtin_call_expression.  This is used for a call to a
7352 // builtin function.
7353
7354 class Builtin_call_expression : public Call_expression
7355 {
7356  public:
7357   Builtin_call_expression(Gogo* gogo, Expression* fn, Expression_list* args,
7358                           bool is_varargs, Location location);
7359
7360  protected:
7361   // This overrides Call_expression::do_lower.
7362   Expression*
7363   do_lower(Gogo*, Named_object*, Statement_inserter*, int);
7364
7365   bool
7366   do_is_constant() const;
7367
7368   bool
7369   do_integer_constant_value(bool, mpz_t, Type**) const;
7370
7371   bool
7372   do_float_constant_value(mpfr_t, Type**) const;
7373
7374   bool
7375   do_complex_constant_value(mpfr_t, mpfr_t, Type**) const;
7376
7377   void
7378   do_discarding_value();
7379
7380   Type*
7381   do_type();
7382
7383   void
7384   do_determine_type(const Type_context*);
7385
7386   void
7387   do_check_types(Gogo*);
7388
7389   Expression*
7390   do_copy()
7391   {
7392     return new Builtin_call_expression(this->gogo_, this->fn()->copy(),
7393                                        this->args()->copy(),
7394                                        this->is_varargs(),
7395                                        this->location());
7396   }
7397
7398   tree
7399   do_get_tree(Translate_context*);
7400
7401   void
7402   do_export(Export*) const;
7403
7404   virtual bool
7405   do_is_recover_call() const;
7406
7407   virtual void
7408   do_set_recover_arg(Expression*);
7409
7410  private:
7411   // The builtin functions.
7412   enum Builtin_function_code
7413     {
7414       BUILTIN_INVALID,
7415
7416       // Predeclared builtin functions.
7417       BUILTIN_APPEND,
7418       BUILTIN_CAP,
7419       BUILTIN_CLOSE,
7420       BUILTIN_COMPLEX,
7421       BUILTIN_COPY,
7422       BUILTIN_DELETE,
7423       BUILTIN_IMAG,
7424       BUILTIN_LEN,
7425       BUILTIN_MAKE,
7426       BUILTIN_NEW,
7427       BUILTIN_PANIC,
7428       BUILTIN_PRINT,
7429       BUILTIN_PRINTLN,
7430       BUILTIN_REAL,
7431       BUILTIN_RECOVER,
7432
7433       // Builtin functions from the unsafe package.
7434       BUILTIN_ALIGNOF,
7435       BUILTIN_OFFSETOF,
7436       BUILTIN_SIZEOF
7437     };
7438
7439   Expression*
7440   one_arg() const;
7441
7442   bool
7443   check_one_arg();
7444
7445   static Type*
7446   real_imag_type(Type*);
7447
7448   static Type*
7449   complex_type(Type*);
7450
7451   Expression*
7452   lower_make();
7453
7454   bool
7455   check_int_value(Expression*);
7456
7457   // A pointer back to the general IR structure.  This avoids a global
7458   // variable, or passing it around everywhere.
7459   Gogo* gogo_;
7460   // The builtin function being called.
7461   Builtin_function_code code_;
7462   // Used to stop endless loops when the length of an array uses len
7463   // or cap of the array itself.
7464   mutable bool seen_;
7465 };
7466
7467 Builtin_call_expression::Builtin_call_expression(Gogo* gogo,
7468                                                  Expression* fn,
7469                                                  Expression_list* args,
7470                                                  bool is_varargs,
7471                                                  Location location)
7472   : Call_expression(fn, args, is_varargs, location),
7473     gogo_(gogo), code_(BUILTIN_INVALID), seen_(false)
7474 {
7475   Func_expression* fnexp = this->fn()->func_expression();
7476   go_assert(fnexp != NULL);
7477   const std::string& name(fnexp->named_object()->name());
7478   if (name == "append")
7479     this->code_ = BUILTIN_APPEND;
7480   else if (name == "cap")
7481     this->code_ = BUILTIN_CAP;
7482   else if (name == "close")
7483     this->code_ = BUILTIN_CLOSE;
7484   else if (name == "complex")
7485     this->code_ = BUILTIN_COMPLEX;
7486   else if (name == "copy")
7487     this->code_ = BUILTIN_COPY;
7488   else if (name == "delete")
7489     this->code_ = BUILTIN_DELETE;
7490   else if (name == "imag")
7491     this->code_ = BUILTIN_IMAG;
7492   else if (name == "len")
7493     this->code_ = BUILTIN_LEN;
7494   else if (name == "make")
7495     this->code_ = BUILTIN_MAKE;
7496   else if (name == "new")
7497     this->code_ = BUILTIN_NEW;
7498   else if (name == "panic")
7499     this->code_ = BUILTIN_PANIC;
7500   else if (name == "print")
7501     this->code_ = BUILTIN_PRINT;
7502   else if (name == "println")
7503     this->code_ = BUILTIN_PRINTLN;
7504   else if (name == "real")
7505     this->code_ = BUILTIN_REAL;
7506   else if (name == "recover")
7507     this->code_ = BUILTIN_RECOVER;
7508   else if (name == "Alignof")
7509     this->code_ = BUILTIN_ALIGNOF;
7510   else if (name == "Offsetof")
7511     this->code_ = BUILTIN_OFFSETOF;
7512   else if (name == "Sizeof")
7513     this->code_ = BUILTIN_SIZEOF;
7514   else
7515     go_unreachable();
7516 }
7517
7518 // Return whether this is a call to recover.  This is a virtual
7519 // function called from the parent class.
7520
7521 bool
7522 Builtin_call_expression::do_is_recover_call() const
7523 {
7524   if (this->classification() == EXPRESSION_ERROR)
7525     return false;
7526   return this->code_ == BUILTIN_RECOVER;
7527 }
7528
7529 // Set the argument for a call to recover.
7530
7531 void
7532 Builtin_call_expression::do_set_recover_arg(Expression* arg)
7533 {
7534   const Expression_list* args = this->args();
7535   go_assert(args == NULL || args->empty());
7536   Expression_list* new_args = new Expression_list();
7537   new_args->push_back(arg);
7538   this->set_args(new_args);
7539 }
7540
7541 // A traversal class which looks for a call expression.
7542
7543 class Find_call_expression : public Traverse
7544 {
7545  public:
7546   Find_call_expression()
7547     : Traverse(traverse_expressions),
7548       found_(false)
7549   { }
7550
7551   int
7552   expression(Expression**);
7553
7554   bool
7555   found()
7556   { return this->found_; }
7557
7558  private:
7559   bool found_;
7560 };
7561
7562 int
7563 Find_call_expression::expression(Expression** pexpr)
7564 {
7565   if ((*pexpr)->call_expression() != NULL)
7566     {
7567       this->found_ = true;
7568       return TRAVERSE_EXIT;
7569     }
7570   return TRAVERSE_CONTINUE;
7571 }
7572
7573 // Lower a builtin call expression.  This turns new and make into
7574 // specific expressions.  We also convert to a constant if we can.
7575
7576 Expression*
7577 Builtin_call_expression::do_lower(Gogo* gogo, Named_object* function,
7578                                   Statement_inserter* inserter, int)
7579 {
7580   if (this->classification() == EXPRESSION_ERROR)
7581     return this;
7582
7583   Location loc = this->location();
7584
7585   if (this->is_varargs() && this->code_ != BUILTIN_APPEND)
7586     {
7587       this->report_error(_("invalid use of %<...%> with builtin function"));
7588       return Expression::make_error(loc);
7589     }
7590
7591   if (this->is_constant())
7592     {
7593       // We can only lower len and cap if there are no function calls
7594       // in the arguments.  Otherwise we have to make the call.
7595       if (this->code_ == BUILTIN_LEN || this->code_ == BUILTIN_CAP)
7596         {
7597           Expression* arg = this->one_arg();
7598           if (!arg->is_constant())
7599             {
7600               Find_call_expression find_call;
7601               Expression::traverse(&arg, &find_call);
7602               if (find_call.found())
7603                 return this;
7604             }
7605         }
7606
7607       mpz_t ival;
7608       mpz_init(ival);
7609       Type* type;
7610       if (this->integer_constant_value(true, ival, &type))
7611         {
7612           Expression* ret = Expression::make_integer(&ival, type, loc);
7613           mpz_clear(ival);
7614           return ret;
7615         }
7616       mpz_clear(ival);
7617
7618       mpfr_t rval;
7619       mpfr_init(rval);
7620       if (this->float_constant_value(rval, &type))
7621         {
7622           Expression* ret = Expression::make_float(&rval, type, loc);
7623           mpfr_clear(rval);
7624           return ret;
7625         }
7626
7627       mpfr_t imag;
7628       mpfr_init(imag);
7629       if (this->complex_constant_value(rval, imag, &type))
7630         {
7631           Expression* ret = Expression::make_complex(&rval, &imag, type, loc);
7632           mpfr_clear(rval);
7633           mpfr_clear(imag);
7634           return ret;
7635         }
7636       mpfr_clear(rval);
7637       mpfr_clear(imag);
7638     }
7639
7640   switch (this->code_)
7641     {
7642     default:
7643       break;
7644
7645     case BUILTIN_NEW:
7646       {
7647         const Expression_list* args = this->args();
7648         if (args == NULL || args->size() < 1)
7649           this->report_error(_("not enough arguments"));
7650         else if (args->size() > 1)
7651           this->report_error(_("too many arguments"));
7652         else
7653           {
7654             Expression* arg = args->front();
7655             if (!arg->is_type_expression())
7656               {
7657                 error_at(arg->location(), "expected type");
7658                 this->set_is_error();
7659               }
7660             else
7661               return Expression::make_allocation(arg->type(), loc);
7662           }
7663       }
7664       break;
7665
7666     case BUILTIN_MAKE:
7667       return this->lower_make();
7668
7669     case BUILTIN_RECOVER:
7670       if (function != NULL)
7671         function->func_value()->set_calls_recover();
7672       else
7673         {
7674           // Calling recover outside of a function always returns the
7675           // nil empty interface.
7676           Type* eface = Type::make_empty_interface_type(loc);
7677           return Expression::make_cast(eface, Expression::make_nil(loc), loc);
7678         }
7679       break;
7680
7681     case BUILTIN_APPEND:
7682       {
7683         // Lower the varargs.
7684         const Expression_list* args = this->args();
7685         if (args == NULL || args->empty())
7686           return this;
7687         Type* slice_type = args->front()->type();
7688         if (!slice_type->is_slice_type())
7689           {
7690             error_at(args->front()->location(), "argument 1 must be a slice");
7691             this->set_is_error();
7692             return this;
7693           }
7694         Type* element_type = slice_type->array_type()->element_type();
7695         this->lower_varargs(gogo, function, inserter,
7696                             Type::make_array_type(element_type, NULL),
7697                             2);
7698       }
7699       break;
7700
7701     case BUILTIN_DELETE:
7702       {
7703         // Lower to a runtime function call.
7704         const Expression_list* args = this->args();
7705         if (args == NULL || args->size() < 2)
7706           this->report_error(_("not enough arguments"));
7707         else if (args->size() > 2)
7708           this->report_error(_("too many arguments"));
7709         else if (args->front()->type()->map_type() == NULL)
7710           this->report_error(_("argument 1 must be a map"));
7711         else
7712           {
7713             // Since this function returns no value it must appear in
7714             // a statement by itself, so we don't have to worry about
7715             // order of evaluation of values around it.  Evaluate the
7716             // map first to get order of evaluation right.
7717             Map_type* mt = args->front()->type()->map_type();
7718             Temporary_statement* map_temp =
7719               Statement::make_temporary(mt, args->front(), loc);
7720             inserter->insert(map_temp);
7721
7722             Temporary_statement* key_temp =
7723               Statement::make_temporary(mt->key_type(), args->back(), loc);
7724             inserter->insert(key_temp);
7725
7726             Expression* e1 = Expression::make_temporary_reference(map_temp,
7727                                                                   loc);
7728             Expression* e2 = Expression::make_temporary_reference(key_temp,
7729                                                                   loc);
7730             e2 = Expression::make_unary(OPERATOR_AND, e2, loc);
7731             return Runtime::make_call(Runtime::MAPDELETE, this->location(),
7732                                       2, e1, e2);
7733           }
7734       }
7735       break;
7736     }
7737
7738   return this;
7739 }
7740
7741 // Lower a make expression.
7742
7743 Expression*
7744 Builtin_call_expression::lower_make()
7745 {
7746   Location loc = this->location();
7747
7748   const Expression_list* args = this->args();
7749   if (args == NULL || args->size() < 1)
7750     {
7751       this->report_error(_("not enough arguments"));
7752       return Expression::make_error(this->location());
7753     }
7754
7755   Expression_list::const_iterator parg = args->begin();
7756
7757   Expression* first_arg = *parg;
7758   if (!first_arg->is_type_expression())
7759     {
7760       error_at(first_arg->location(), "expected type");
7761       this->set_is_error();
7762       return Expression::make_error(this->location());
7763     }
7764   Type* type = first_arg->type();
7765
7766   bool is_slice = false;
7767   bool is_map = false;
7768   bool is_chan = false;
7769   if (type->is_slice_type())
7770     is_slice = true;
7771   else if (type->map_type() != NULL)
7772     is_map = true;
7773   else if (type->channel_type() != NULL)
7774     is_chan = true;
7775   else
7776     {
7777       this->report_error(_("invalid type for make function"));
7778       return Expression::make_error(this->location());
7779     }
7780
7781   bool have_big_args = false;
7782   Type* uintptr_type = Type::lookup_integer_type("uintptr");
7783   int uintptr_bits = uintptr_type->integer_type()->bits();
7784
7785   ++parg;
7786   Expression* len_arg;
7787   if (parg == args->end())
7788     {
7789       if (is_slice)
7790         {
7791           this->report_error(_("length required when allocating a slice"));
7792           return Expression::make_error(this->location());
7793         }
7794
7795       mpz_t zval;
7796       mpz_init_set_ui(zval, 0);
7797       len_arg = Expression::make_integer(&zval, NULL, loc);
7798       mpz_clear(zval);
7799     }
7800   else
7801     {
7802       len_arg = *parg;
7803       if (!this->check_int_value(len_arg))
7804         {
7805           this->report_error(_("bad size for make"));
7806           return Expression::make_error(this->location());
7807         }
7808       if (len_arg->type()->integer_type() != NULL
7809           && len_arg->type()->integer_type()->bits() > uintptr_bits)
7810         have_big_args = true;
7811       ++parg;
7812     }
7813
7814   Expression* cap_arg = NULL;
7815   if (is_slice && parg != args->end())
7816     {
7817       cap_arg = *parg;
7818       if (!this->check_int_value(cap_arg))
7819         {
7820           this->report_error(_("bad capacity when making slice"));
7821           return Expression::make_error(this->location());
7822         }
7823       if (cap_arg->type()->integer_type() != NULL
7824           && cap_arg->type()->integer_type()->bits() > uintptr_bits)
7825         have_big_args = true;
7826       ++parg;
7827     }
7828
7829   if (parg != args->end())
7830     {
7831       this->report_error(_("too many arguments to make"));
7832       return Expression::make_error(this->location());
7833     }
7834
7835   Location type_loc = first_arg->location();
7836   Expression* type_arg;
7837   if (is_slice || is_chan)
7838     type_arg = Expression::make_type_descriptor(type, type_loc);
7839   else if (is_map)
7840     type_arg = Expression::make_map_descriptor(type->map_type(), type_loc);
7841   else
7842     go_unreachable();
7843
7844   Expression* call;
7845   if (is_slice)
7846     {
7847       if (cap_arg == NULL)
7848         call = Runtime::make_call((have_big_args
7849                                    ? Runtime::MAKESLICE1BIG
7850                                    : Runtime::MAKESLICE1),
7851                                   loc, 2, type_arg, len_arg);
7852       else
7853         call = Runtime::make_call((have_big_args
7854                                    ? Runtime::MAKESLICE2BIG
7855                                    : Runtime::MAKESLICE2),
7856                                   loc, 3, type_arg, len_arg, cap_arg);
7857     }
7858   else if (is_map)
7859     call = Runtime::make_call((have_big_args
7860                                ? Runtime::MAKEMAPBIG
7861                                : Runtime::MAKEMAP),
7862                               loc, 2, type_arg, len_arg);
7863   else if (is_chan)
7864     call = Runtime::make_call((have_big_args
7865                                ? Runtime::MAKECHANBIG
7866                                : Runtime::MAKECHAN),
7867                               loc, 2, type_arg, len_arg);
7868   else
7869     go_unreachable();
7870
7871   return Expression::make_unsafe_cast(type, call, loc);
7872 }
7873
7874 // Return whether an expression has an integer value.  Report an error
7875 // if not.  This is used when handling calls to the predeclared make
7876 // function.
7877
7878 bool
7879 Builtin_call_expression::check_int_value(Expression* e)
7880 {
7881   if (e->type()->integer_type() != NULL)
7882     return true;
7883
7884   // Check for a floating point constant with integer value.
7885   mpfr_t fval;
7886   mpfr_init(fval);
7887
7888   Type* dummy;
7889   if (e->float_constant_value(fval, &dummy) && mpfr_integer_p(fval))
7890     {
7891       mpz_t ival;
7892       mpz_init(ival);
7893
7894       bool ok = false;
7895
7896       mpfr_clear_overflow();
7897       mpfr_clear_erangeflag();
7898       mpfr_get_z(ival, fval, GMP_RNDN);
7899       if (!mpfr_overflow_p()
7900           && !mpfr_erangeflag_p()
7901           && mpz_sgn(ival) >= 0)
7902         {
7903           Named_type* ntype = Type::lookup_integer_type("int");
7904           Integer_type* inttype = ntype->integer_type();
7905           mpz_t max;
7906           mpz_init_set_ui(max, 1);
7907           mpz_mul_2exp(max, max, inttype->bits() - 1);
7908           ok = mpz_cmp(ival, max) < 0;
7909           mpz_clear(max);
7910         }
7911       mpz_clear(ival);
7912
7913       if (ok)
7914         {
7915           mpfr_clear(fval);
7916           return true;
7917         }
7918     }
7919
7920   mpfr_clear(fval);
7921
7922   return false;
7923 }
7924
7925 // Return the type of the real or imag functions, given the type of
7926 // the argument.  We need to map complex to float, complex64 to
7927 // float32, and complex128 to float64, so it has to be done by name.
7928 // This returns NULL if it can't figure out the type.
7929
7930 Type*
7931 Builtin_call_expression::real_imag_type(Type* arg_type)
7932 {
7933   if (arg_type == NULL || arg_type->is_abstract())
7934     return NULL;
7935   Named_type* nt = arg_type->named_type();
7936   if (nt == NULL)
7937     return NULL;
7938   while (nt->real_type()->named_type() != NULL)
7939     nt = nt->real_type()->named_type();
7940   if (nt->name() == "complex64")
7941     return Type::lookup_float_type("float32");
7942   else if (nt->name() == "complex128")
7943     return Type::lookup_float_type("float64");
7944   else
7945     return NULL;
7946 }
7947
7948 // Return the type of the complex function, given the type of one of the
7949 // argments.  Like real_imag_type, we have to map by name.
7950
7951 Type*
7952 Builtin_call_expression::complex_type(Type* arg_type)
7953 {
7954   if (arg_type == NULL || arg_type->is_abstract())
7955     return NULL;
7956   Named_type* nt = arg_type->named_type();
7957   if (nt == NULL)
7958     return NULL;
7959   while (nt->real_type()->named_type() != NULL)
7960     nt = nt->real_type()->named_type();
7961   if (nt->name() == "float32")
7962     return Type::lookup_complex_type("complex64");
7963   else if (nt->name() == "float64")
7964     return Type::lookup_complex_type("complex128");
7965   else
7966     return NULL;
7967 }
7968
7969 // Return a single argument, or NULL if there isn't one.
7970
7971 Expression*
7972 Builtin_call_expression::one_arg() const
7973 {
7974   const Expression_list* args = this->args();
7975   if (args->size() != 1)
7976     return NULL;
7977   return args->front();
7978 }
7979
7980 // Return whether this is constant: len of a string, or len or cap of
7981 // a fixed array, or unsafe.Sizeof, unsafe.Offsetof, unsafe.Alignof.
7982
7983 bool
7984 Builtin_call_expression::do_is_constant() const
7985 {
7986   switch (this->code_)
7987     {
7988     case BUILTIN_LEN:
7989     case BUILTIN_CAP:
7990       {
7991         if (this->seen_)
7992           return false;
7993
7994         Expression* arg = this->one_arg();
7995         if (arg == NULL)
7996           return false;
7997         Type* arg_type = arg->type();
7998
7999         if (arg_type->points_to() != NULL
8000             && arg_type->points_to()->array_type() != NULL
8001             && !arg_type->points_to()->is_slice_type())
8002           arg_type = arg_type->points_to();
8003
8004         if (arg_type->array_type() != NULL
8005             && arg_type->array_type()->length() != NULL)
8006           return true;
8007
8008         if (this->code_ == BUILTIN_LEN && arg_type->is_string_type())
8009           {
8010             this->seen_ = true;
8011             bool ret = arg->is_constant();
8012             this->seen_ = false;
8013             return ret;
8014           }
8015       }
8016       break;
8017
8018     case BUILTIN_SIZEOF:
8019     case BUILTIN_ALIGNOF:
8020       return this->one_arg() != NULL;
8021
8022     case BUILTIN_OFFSETOF:
8023       {
8024         Expression* arg = this->one_arg();
8025         if (arg == NULL)
8026           return false;
8027         return arg->field_reference_expression() != NULL;
8028       }
8029
8030     case BUILTIN_COMPLEX:
8031       {
8032         const Expression_list* args = this->args();
8033         if (args != NULL && args->size() == 2)
8034           return args->front()->is_constant() && args->back()->is_constant();
8035       }
8036       break;
8037
8038     case BUILTIN_REAL:
8039     case BUILTIN_IMAG:
8040       {
8041         Expression* arg = this->one_arg();
8042         return arg != NULL && arg->is_constant();
8043       }
8044
8045     default:
8046       break;
8047     }
8048
8049   return false;
8050 }
8051
8052 // Return an integer constant value if possible.
8053
8054 bool
8055 Builtin_call_expression::do_integer_constant_value(bool iota_is_constant,
8056                                                    mpz_t val,
8057                                                    Type** ptype) const
8058 {
8059   if (this->code_ == BUILTIN_LEN
8060       || this->code_ == BUILTIN_CAP)
8061     {
8062       Expression* arg = this->one_arg();
8063       if (arg == NULL)
8064         return false;
8065       Type* arg_type = arg->type();
8066
8067       if (this->code_ == BUILTIN_LEN && arg_type->is_string_type())
8068         {
8069           std::string sval;
8070           if (arg->string_constant_value(&sval))
8071             {
8072               mpz_set_ui(val, sval.length());
8073               *ptype = Type::lookup_integer_type("int");
8074               return true;
8075             }
8076         }
8077
8078       if (arg_type->points_to() != NULL
8079           && arg_type->points_to()->array_type() != NULL
8080           && !arg_type->points_to()->is_slice_type())
8081         arg_type = arg_type->points_to();
8082
8083       if (arg_type->array_type() != NULL
8084           && arg_type->array_type()->length() != NULL)
8085         {
8086           if (this->seen_)
8087             return false;
8088           Expression* e = arg_type->array_type()->length();
8089           this->seen_ = true;
8090           bool r = e->integer_constant_value(iota_is_constant, val, ptype);
8091           this->seen_ = false;
8092           if (r)
8093             {
8094               *ptype = Type::lookup_integer_type("int");
8095               return true;
8096             }
8097         }
8098     }
8099   else if (this->code_ == BUILTIN_SIZEOF
8100            || this->code_ == BUILTIN_ALIGNOF)
8101     {
8102       Expression* arg = this->one_arg();
8103       if (arg == NULL)
8104         return false;
8105       Type* arg_type = arg->type();
8106       if (arg_type->is_error())
8107         return false;
8108       if (arg_type->is_abstract())
8109         return false;
8110       if (arg_type->named_type() != NULL)
8111         arg_type->named_type()->convert(this->gogo_);
8112
8113       unsigned int ret;
8114       if (this->code_ == BUILTIN_SIZEOF)
8115         {
8116           if (!arg_type->backend_type_size(this->gogo_, &ret))
8117             return false;
8118         }
8119       else if (this->code_ == BUILTIN_ALIGNOF)
8120         {
8121           if (arg->field_reference_expression() == NULL)
8122             {
8123               if (!arg_type->backend_type_align(this->gogo_, &ret))
8124                 return false;
8125             }
8126           else
8127             {
8128               // Calling unsafe.Alignof(s.f) returns the alignment of
8129               // the type of f when it is used as a field in a struct.
8130               if (!arg_type->backend_type_field_align(this->gogo_, &ret))
8131                 return false;
8132             }
8133         }
8134       else
8135         go_unreachable();
8136
8137       mpz_set_ui(val, ret);
8138       *ptype = NULL;
8139       return true;
8140     }
8141   else if (this->code_ == BUILTIN_OFFSETOF)
8142     {
8143       Expression* arg = this->one_arg();
8144       if (arg == NULL)
8145         return false;
8146       Field_reference_expression* farg = arg->field_reference_expression();
8147       if (farg == NULL)
8148         return false;
8149       Expression* struct_expr = farg->expr();
8150       Type* st = struct_expr->type();
8151       if (st->struct_type() == NULL)
8152         return false;
8153       if (st->named_type() != NULL)
8154         st->named_type()->convert(this->gogo_);
8155       unsigned int offset;
8156       if (!st->struct_type()->backend_field_offset(this->gogo_,
8157                                                    farg->field_index(),
8158                                                    &offset))
8159         return false;
8160       mpz_set_ui(val, offset);
8161       return true;
8162     }
8163   return false;
8164 }
8165
8166 // Return a floating point constant value if possible.
8167
8168 bool
8169 Builtin_call_expression::do_float_constant_value(mpfr_t val,
8170                                                  Type** ptype) const
8171 {
8172   if (this->code_ == BUILTIN_REAL || this->code_ == BUILTIN_IMAG)
8173     {
8174       Expression* arg = this->one_arg();
8175       if (arg == NULL)
8176         return false;
8177
8178       mpfr_t real;
8179       mpfr_t imag;
8180       mpfr_init(real);
8181       mpfr_init(imag);
8182
8183       bool ret = false;
8184       Type* type;
8185       if (arg->complex_constant_value(real, imag, &type))
8186         {
8187           if (this->code_ == BUILTIN_REAL)
8188             mpfr_set(val, real, GMP_RNDN);
8189           else
8190             mpfr_set(val, imag, GMP_RNDN);
8191           *ptype = Builtin_call_expression::real_imag_type(type);
8192           ret = true;
8193         }
8194
8195       mpfr_clear(real);
8196       mpfr_clear(imag);
8197       return ret;
8198     }
8199
8200   return false;
8201 }
8202
8203 // Return a complex constant value if possible.
8204
8205 bool
8206 Builtin_call_expression::do_complex_constant_value(mpfr_t real, mpfr_t imag,
8207                                                    Type** ptype) const
8208 {
8209   if (this->code_ == BUILTIN_COMPLEX)
8210     {
8211       const Expression_list* args = this->args();
8212       if (args == NULL || args->size() != 2)
8213         return false;
8214
8215       mpfr_t r;
8216       mpfr_init(r);
8217       Type* rtype;
8218       if (!args->front()->float_constant_value(r, &rtype))
8219         {
8220           mpfr_clear(r);
8221           return false;
8222         }
8223
8224       mpfr_t i;
8225       mpfr_init(i);
8226
8227       bool ret = false;
8228       Type* itype;
8229       if (args->back()->float_constant_value(i, &itype)
8230           && Type::are_identical(rtype, itype, false, NULL))
8231         {
8232           mpfr_set(real, r, GMP_RNDN);
8233           mpfr_set(imag, i, GMP_RNDN);
8234           *ptype = Builtin_call_expression::complex_type(rtype);
8235           ret = true;
8236         }
8237
8238       mpfr_clear(r);
8239       mpfr_clear(i);
8240
8241       return ret;
8242     }
8243
8244   return false;
8245 }
8246
8247 // Give an error if we are discarding the value of an expression which
8248 // should not normally be discarded.  We don't give an error for
8249 // discarding the value of an ordinary function call, but we do for
8250 // builtin functions, purely for consistency with the gc compiler.
8251
8252 void
8253 Builtin_call_expression::do_discarding_value()
8254 {
8255   switch (this->code_)
8256     {
8257     case BUILTIN_INVALID:
8258     default:
8259       go_unreachable();
8260
8261     case BUILTIN_APPEND:
8262     case BUILTIN_CAP:
8263     case BUILTIN_COMPLEX:
8264     case BUILTIN_IMAG:
8265     case BUILTIN_LEN:
8266     case BUILTIN_MAKE:
8267     case BUILTIN_NEW:
8268     case BUILTIN_REAL:
8269     case BUILTIN_ALIGNOF:
8270     case BUILTIN_OFFSETOF:
8271     case BUILTIN_SIZEOF:
8272       this->unused_value_error();
8273       break;
8274
8275     case BUILTIN_CLOSE:
8276     case BUILTIN_COPY:
8277     case BUILTIN_DELETE:
8278     case BUILTIN_PANIC:
8279     case BUILTIN_PRINT:
8280     case BUILTIN_PRINTLN:
8281     case BUILTIN_RECOVER:
8282       break;
8283     }
8284 }
8285
8286 // Return the type.
8287
8288 Type*
8289 Builtin_call_expression::do_type()
8290 {
8291   switch (this->code_)
8292     {
8293     case BUILTIN_INVALID:
8294     default:
8295       go_unreachable();
8296
8297     case BUILTIN_NEW:
8298     case BUILTIN_MAKE:
8299       {
8300         const Expression_list* args = this->args();
8301         if (args == NULL || args->empty())
8302           return Type::make_error_type();
8303         return Type::make_pointer_type(args->front()->type());
8304       }
8305
8306     case BUILTIN_CAP:
8307     case BUILTIN_COPY:
8308     case BUILTIN_LEN:
8309     case BUILTIN_ALIGNOF:
8310     case BUILTIN_OFFSETOF:
8311     case BUILTIN_SIZEOF:
8312       return Type::lookup_integer_type("int");
8313
8314     case BUILTIN_CLOSE:
8315     case BUILTIN_DELETE:
8316     case BUILTIN_PANIC:
8317     case BUILTIN_PRINT:
8318     case BUILTIN_PRINTLN:
8319       return Type::make_void_type();
8320
8321     case BUILTIN_RECOVER:
8322       return Type::make_empty_interface_type(Linemap::predeclared_location());
8323
8324     case BUILTIN_APPEND:
8325       {
8326         const Expression_list* args = this->args();
8327         if (args == NULL || args->empty())
8328           return Type::make_error_type();
8329         return args->front()->type();
8330       }
8331
8332     case BUILTIN_REAL:
8333     case BUILTIN_IMAG:
8334       {
8335         Expression* arg = this->one_arg();
8336         if (arg == NULL)
8337           return Type::make_error_type();
8338         Type* t = arg->type();
8339         if (t->is_abstract())
8340           t = t->make_non_abstract_type();
8341         t = Builtin_call_expression::real_imag_type(t);
8342         if (t == NULL)
8343           t = Type::make_error_type();
8344         return t;
8345       }
8346
8347     case BUILTIN_COMPLEX:
8348       {
8349         const Expression_list* args = this->args();
8350         if (args == NULL || args->size() != 2)
8351           return Type::make_error_type();
8352         Type* t = args->front()->type();
8353         if (t->is_abstract())
8354           {
8355             t = args->back()->type();
8356             if (t->is_abstract())
8357               t = t->make_non_abstract_type();
8358           }
8359         t = Builtin_call_expression::complex_type(t);
8360         if (t == NULL)
8361           t = Type::make_error_type();
8362         return t;
8363       }
8364     }
8365 }
8366
8367 // Determine the type.
8368
8369 void
8370 Builtin_call_expression::do_determine_type(const Type_context* context)
8371 {
8372   if (!this->determining_types())
8373     return;
8374
8375   this->fn()->determine_type_no_context();
8376
8377   const Expression_list* args = this->args();
8378
8379   bool is_print;
8380   Type* arg_type = NULL;
8381   switch (this->code_)
8382     {
8383     case BUILTIN_PRINT:
8384     case BUILTIN_PRINTLN:
8385       // Do not force a large integer constant to "int".
8386       is_print = true;
8387       break;
8388
8389     case BUILTIN_REAL:
8390     case BUILTIN_IMAG:
8391       arg_type = Builtin_call_expression::complex_type(context->type);
8392       is_print = false;
8393       break;
8394
8395     case BUILTIN_COMPLEX:
8396       {
8397         // For the complex function the type of one operand can
8398         // determine the type of the other, as in a binary expression.
8399         arg_type = Builtin_call_expression::real_imag_type(context->type);
8400         if (args != NULL && args->size() == 2)
8401           {
8402             Type* t1 = args->front()->type();
8403             Type* t2 = args->front()->type();
8404             if (!t1->is_abstract())
8405               arg_type = t1;
8406             else if (!t2->is_abstract())
8407               arg_type = t2;
8408           }
8409         is_print = false;
8410       }
8411       break;
8412
8413     default:
8414       is_print = false;
8415       break;
8416     }
8417
8418   if (args != NULL)
8419     {
8420       for (Expression_list::const_iterator pa = args->begin();
8421            pa != args->end();
8422            ++pa)
8423         {
8424           Type_context subcontext;
8425           subcontext.type = arg_type;
8426
8427           if (is_print)
8428             {
8429               // We want to print large constants, we so can't just
8430               // use the appropriate nonabstract type.  Use uint64 for
8431               // an integer if we know it is nonnegative, otherwise
8432               // use int64 for a integer, otherwise use float64 for a
8433               // float or complex128 for a complex.
8434               Type* want_type = NULL;
8435               Type* atype = (*pa)->type();
8436               if (atype->is_abstract())
8437                 {
8438                   if (atype->integer_type() != NULL)
8439                     {
8440                       mpz_t val;
8441                       mpz_init(val);
8442                       Type* dummy;
8443                       if (this->integer_constant_value(true, val, &dummy)
8444                           && mpz_sgn(val) >= 0)
8445                         want_type = Type::lookup_integer_type("uint64");
8446                       else
8447                         want_type = Type::lookup_integer_type("int64");
8448                       mpz_clear(val);
8449                     }
8450                   else if (atype->float_type() != NULL)
8451                     want_type = Type::lookup_float_type("float64");
8452                   else if (atype->complex_type() != NULL)
8453                     want_type = Type::lookup_complex_type("complex128");
8454                   else if (atype->is_abstract_string_type())
8455                     want_type = Type::lookup_string_type();
8456                   else if (atype->is_abstract_boolean_type())
8457                     want_type = Type::lookup_bool_type();
8458                   else
8459                     go_unreachable();
8460                   subcontext.type = want_type;
8461                 }
8462             }
8463
8464           (*pa)->determine_type(&subcontext);
8465         }
8466     }
8467 }
8468
8469 // If there is exactly one argument, return true.  Otherwise give an
8470 // error message and return false.
8471
8472 bool
8473 Builtin_call_expression::check_one_arg()
8474 {
8475   const Expression_list* args = this->args();
8476   if (args == NULL || args->size() < 1)
8477     {
8478       this->report_error(_("not enough arguments"));
8479       return false;
8480     }
8481   else if (args->size() > 1)
8482     {
8483       this->report_error(_("too many arguments"));
8484       return false;
8485     }
8486   if (args->front()->is_error_expression()
8487       || args->front()->type()->is_error())
8488     {
8489       this->set_is_error();
8490       return false;
8491     }
8492   return true;
8493 }
8494
8495 // Check argument types for a builtin function.
8496
8497 void
8498 Builtin_call_expression::do_check_types(Gogo*)
8499 {
8500   switch (this->code_)
8501     {
8502     case BUILTIN_INVALID:
8503     case BUILTIN_NEW:
8504     case BUILTIN_MAKE:
8505       return;
8506
8507     case BUILTIN_LEN:
8508     case BUILTIN_CAP:
8509       {
8510         // The single argument may be either a string or an array or a
8511         // map or a channel, or a pointer to a closed array.
8512         if (this->check_one_arg())
8513           {
8514             Type* arg_type = this->one_arg()->type();
8515             if (arg_type->points_to() != NULL
8516                 && arg_type->points_to()->array_type() != NULL
8517                 && !arg_type->points_to()->is_slice_type())
8518               arg_type = arg_type->points_to();
8519             if (this->code_ == BUILTIN_CAP)
8520               {
8521                 if (!arg_type->is_error()
8522                     && arg_type->array_type() == NULL
8523                     && arg_type->channel_type() == NULL)
8524                   this->report_error(_("argument must be array or slice "
8525                                        "or channel"));
8526               }
8527             else
8528               {
8529                 if (!arg_type->is_error()
8530                     && !arg_type->is_string_type()
8531                     && arg_type->array_type() == NULL
8532                     && arg_type->map_type() == NULL
8533                     && arg_type->channel_type() == NULL)
8534                   this->report_error(_("argument must be string or "
8535                                        "array or slice or map or channel"));
8536               }
8537           }
8538       }
8539       break;
8540
8541     case BUILTIN_PRINT:
8542     case BUILTIN_PRINTLN:
8543       {
8544         const Expression_list* args = this->args();
8545         if (args == NULL)
8546           {
8547             if (this->code_ == BUILTIN_PRINT)
8548               warning_at(this->location(), 0,
8549                          "no arguments for builtin function %<%s%>",
8550                          (this->code_ == BUILTIN_PRINT
8551                           ? "print"
8552                           : "println"));
8553           }
8554         else
8555           {
8556             for (Expression_list::const_iterator p = args->begin();
8557                  p != args->end();
8558                  ++p)
8559               {
8560                 Type* type = (*p)->type();
8561                 if (type->is_error()
8562                     || type->is_string_type()
8563                     || type->integer_type() != NULL
8564                     || type->float_type() != NULL
8565                     || type->complex_type() != NULL
8566                     || type->is_boolean_type()
8567                     || type->points_to() != NULL
8568                     || type->interface_type() != NULL
8569                     || type->channel_type() != NULL
8570                     || type->map_type() != NULL
8571                     || type->function_type() != NULL
8572                     || type->is_slice_type())
8573                   ;
8574                 else if ((*p)->is_type_expression())
8575                   {
8576                     // If this is a type expression it's going to give
8577                     // an error anyhow, so we don't need one here.
8578                   }
8579                 else
8580                   this->report_error(_("unsupported argument type to "
8581                                        "builtin function"));
8582               }
8583           }
8584       }
8585       break;
8586
8587     case BUILTIN_CLOSE:
8588       if (this->check_one_arg())
8589         {
8590           if (this->one_arg()->type()->channel_type() == NULL)
8591             this->report_error(_("argument must be channel"));
8592           else if (!this->one_arg()->type()->channel_type()->may_send())
8593             this->report_error(_("cannot close receive-only channel"));
8594         }
8595       break;
8596
8597     case BUILTIN_PANIC:
8598     case BUILTIN_SIZEOF:
8599     case BUILTIN_ALIGNOF:
8600       this->check_one_arg();
8601       break;
8602
8603     case BUILTIN_RECOVER:
8604       if (this->args() != NULL && !this->args()->empty())
8605         this->report_error(_("too many arguments"));
8606       break;
8607
8608     case BUILTIN_OFFSETOF:
8609       if (this->check_one_arg())
8610         {
8611           Expression* arg = this->one_arg();
8612           if (arg->field_reference_expression() == NULL)
8613             this->report_error(_("argument must be a field reference"));
8614         }
8615       break;
8616
8617     case BUILTIN_COPY:
8618       {
8619         const Expression_list* args = this->args();
8620         if (args == NULL || args->size() < 2)
8621           {
8622             this->report_error(_("not enough arguments"));
8623             break;
8624           }
8625         else if (args->size() > 2)
8626           {
8627             this->report_error(_("too many arguments"));
8628             break;
8629           }
8630         Type* arg1_type = args->front()->type();
8631         Type* arg2_type = args->back()->type();
8632         if (arg1_type->is_error() || arg2_type->is_error())
8633           break;
8634
8635         Type* e1;
8636         if (arg1_type->is_slice_type())
8637           e1 = arg1_type->array_type()->element_type();
8638         else
8639           {
8640             this->report_error(_("left argument must be a slice"));
8641             break;
8642           }
8643
8644         if (arg2_type->is_slice_type())
8645           {
8646             Type* e2 = arg2_type->array_type()->element_type();
8647             if (!Type::are_identical(e1, e2, true, NULL))
8648               this->report_error(_("element types must be the same"));
8649           }
8650         else if (arg2_type->is_string_type())
8651           {
8652             if (e1->integer_type() == NULL || !e1->integer_type()->is_byte())
8653               this->report_error(_("first argument must be []byte"));
8654           }
8655         else
8656             this->report_error(_("second argument must be slice or string"));
8657       }
8658       break;
8659
8660     case BUILTIN_APPEND:
8661       {
8662         const Expression_list* args = this->args();
8663         if (args == NULL || args->size() < 2)
8664           {
8665             this->report_error(_("not enough arguments"));
8666             break;
8667           }
8668         if (args->size() > 2)
8669           {
8670             this->report_error(_("too many arguments"));
8671             break;
8672           }
8673
8674         // The language permits appending a string to a []byte, as a
8675         // special case.
8676         if (args->back()->type()->is_string_type())
8677           {
8678             const Array_type* at = args->front()->type()->array_type();
8679             const Type* e = at->element_type()->forwarded();
8680             if (e->integer_type() != NULL && e->integer_type()->is_byte())
8681               break;
8682           }
8683
8684         // The language says that the second argument must be
8685         // assignable to a slice of the element type of the first
8686         // argument.  We already know the first argument is a slice
8687         // type.
8688         Array_type* at = args->front()->type()->array_type();
8689         Type* arg2_type = Type::make_array_type(at->element_type(), NULL);
8690         std::string reason;
8691         if (!Type::are_assignable(arg2_type, args->back()->type(), &reason))
8692           {
8693             if (reason.empty())
8694               this->report_error(_("argument 2 has invalid type"));
8695             else
8696               {
8697                 error_at(this->location(), "argument 2 has invalid type (%s)",
8698                          reason.c_str());
8699                 this->set_is_error();
8700               }
8701           }
8702         break;
8703       }
8704
8705     case BUILTIN_REAL:
8706     case BUILTIN_IMAG:
8707       if (this->check_one_arg())
8708         {
8709           if (this->one_arg()->type()->complex_type() == NULL)
8710             this->report_error(_("argument must have complex type"));
8711         }
8712       break;
8713
8714     case BUILTIN_COMPLEX:
8715       {
8716         const Expression_list* args = this->args();
8717         if (args == NULL || args->size() < 2)
8718           this->report_error(_("not enough arguments"));
8719         else if (args->size() > 2)
8720           this->report_error(_("too many arguments"));
8721         else if (args->front()->is_error_expression()
8722                  || args->front()->type()->is_error()
8723                  || args->back()->is_error_expression()
8724                  || args->back()->type()->is_error())
8725           this->set_is_error();
8726         else if (!Type::are_identical(args->front()->type(),
8727                                       args->back()->type(), true, NULL))
8728           this->report_error(_("complex arguments must have identical types"));
8729         else if (args->front()->type()->float_type() == NULL)
8730           this->report_error(_("complex arguments must have "
8731                                "floating-point type"));
8732       }
8733       break;
8734
8735     default:
8736       go_unreachable();
8737     }
8738 }
8739
8740 // Return the tree for a builtin function.
8741
8742 tree
8743 Builtin_call_expression::do_get_tree(Translate_context* context)
8744 {
8745   Gogo* gogo = context->gogo();
8746   Location location = this->location();
8747   switch (this->code_)
8748     {
8749     case BUILTIN_INVALID:
8750     case BUILTIN_NEW:
8751     case BUILTIN_MAKE:
8752       go_unreachable();
8753
8754     case BUILTIN_LEN:
8755     case BUILTIN_CAP:
8756       {
8757         const Expression_list* args = this->args();
8758         go_assert(args != NULL && args->size() == 1);
8759         Expression* arg = *args->begin();
8760         Type* arg_type = arg->type();
8761
8762         if (this->seen_)
8763           {
8764             go_assert(saw_errors());
8765             return error_mark_node;
8766           }
8767         this->seen_ = true;
8768
8769         tree arg_tree = arg->get_tree(context);
8770
8771         this->seen_ = false;
8772
8773         if (arg_tree == error_mark_node)
8774           return error_mark_node;
8775
8776         if (arg_type->points_to() != NULL)
8777           {
8778             arg_type = arg_type->points_to();
8779             go_assert(arg_type->array_type() != NULL
8780                        && !arg_type->is_slice_type());
8781             go_assert(POINTER_TYPE_P(TREE_TYPE(arg_tree)));
8782             arg_tree = build_fold_indirect_ref(arg_tree);
8783           }
8784
8785         tree val_tree;
8786         if (this->code_ == BUILTIN_LEN)
8787           {
8788             if (arg_type->is_string_type())
8789               val_tree = String_type::length_tree(gogo, arg_tree);
8790             else if (arg_type->array_type() != NULL)
8791               {
8792                 if (this->seen_)
8793                   {
8794                     go_assert(saw_errors());
8795                     return error_mark_node;
8796                   }
8797                 this->seen_ = true;
8798                 val_tree = arg_type->array_type()->length_tree(gogo, arg_tree);
8799                 this->seen_ = false;
8800               }
8801             else if (arg_type->map_type() != NULL)
8802               {
8803                 tree arg_type_tree = type_to_tree(arg_type->get_backend(gogo));
8804                 static tree map_len_fndecl;
8805                 val_tree = Gogo::call_builtin(&map_len_fndecl,
8806                                               location,
8807                                               "__go_map_len",
8808                                               1,
8809                                               integer_type_node,
8810                                               arg_type_tree,
8811                                               arg_tree);
8812               }
8813             else if (arg_type->channel_type() != NULL)
8814               {
8815                 tree arg_type_tree = type_to_tree(arg_type->get_backend(gogo));
8816                 static tree chan_len_fndecl;
8817                 val_tree = Gogo::call_builtin(&chan_len_fndecl,
8818                                               location,
8819                                               "__go_chan_len",
8820                                               1,
8821                                               integer_type_node,
8822                                               arg_type_tree,
8823                                               arg_tree);
8824               }
8825             else
8826               go_unreachable();
8827           }
8828         else
8829           {
8830             if (arg_type->array_type() != NULL)
8831               {
8832                 if (this->seen_)
8833                   {
8834                     go_assert(saw_errors());
8835                     return error_mark_node;
8836                   }
8837                 this->seen_ = true;
8838                 val_tree = arg_type->array_type()->capacity_tree(gogo,
8839                                                                  arg_tree);
8840                 this->seen_ = false;
8841               }
8842             else if (arg_type->channel_type() != NULL)
8843               {
8844                 tree arg_type_tree = type_to_tree(arg_type->get_backend(gogo));
8845                 static tree chan_cap_fndecl;
8846                 val_tree = Gogo::call_builtin(&chan_cap_fndecl,
8847                                               location,
8848                                               "__go_chan_cap",
8849                                               1,
8850                                               integer_type_node,
8851                                               arg_type_tree,
8852                                               arg_tree);
8853               }
8854             else
8855               go_unreachable();
8856           }
8857
8858         if (val_tree == error_mark_node)
8859           return error_mark_node;
8860
8861         Type* int_type = Type::lookup_integer_type("int");
8862         tree type_tree = type_to_tree(int_type->get_backend(gogo));
8863         if (type_tree == TREE_TYPE(val_tree))
8864           return val_tree;
8865         else
8866           return fold(convert_to_integer(type_tree, val_tree));
8867       }
8868
8869     case BUILTIN_PRINT:
8870     case BUILTIN_PRINTLN:
8871       {
8872         const bool is_ln = this->code_ == BUILTIN_PRINTLN;
8873         tree stmt_list = NULL_TREE;
8874
8875         const Expression_list* call_args = this->args();
8876         if (call_args != NULL)
8877           {
8878             for (Expression_list::const_iterator p = call_args->begin();
8879                  p != call_args->end();
8880                  ++p)
8881               {
8882                 if (is_ln && p != call_args->begin())
8883                   {
8884                     static tree print_space_fndecl;
8885                     tree call = Gogo::call_builtin(&print_space_fndecl,
8886                                                    location,
8887                                                    "__go_print_space",
8888                                                    0,
8889                                                    void_type_node);
8890                     if (call == error_mark_node)
8891                       return error_mark_node;
8892                     append_to_statement_list(call, &stmt_list);
8893                   }
8894
8895                 Type* type = (*p)->type();
8896
8897                 tree arg = (*p)->get_tree(context);
8898                 if (arg == error_mark_node)
8899                   return error_mark_node;
8900
8901                 tree* pfndecl;
8902                 const char* fnname;
8903                 if (type->is_string_type())
8904                   {
8905                     static tree print_string_fndecl;
8906                     pfndecl = &print_string_fndecl;
8907                     fnname = "__go_print_string";
8908                   }
8909                 else if (type->integer_type() != NULL
8910                          && type->integer_type()->is_unsigned())
8911                   {
8912                     static tree print_uint64_fndecl;
8913                     pfndecl = &print_uint64_fndecl;
8914                     fnname = "__go_print_uint64";
8915                     Type* itype = Type::lookup_integer_type("uint64");
8916                     Btype* bitype = itype->get_backend(gogo);
8917                     arg = fold_convert_loc(location.gcc_location(),
8918                                            type_to_tree(bitype), arg);
8919                   }
8920                 else if (type->integer_type() != NULL)
8921                   {
8922                     static tree print_int64_fndecl;
8923                     pfndecl = &print_int64_fndecl;
8924                     fnname = "__go_print_int64";
8925                     Type* itype = Type::lookup_integer_type("int64");
8926                     Btype* bitype = itype->get_backend(gogo);
8927                     arg = fold_convert_loc(location.gcc_location(),
8928                                            type_to_tree(bitype), arg);
8929                   }
8930                 else if (type->float_type() != NULL)
8931                   {
8932                     static tree print_double_fndecl;
8933                     pfndecl = &print_double_fndecl;
8934                     fnname = "__go_print_double";
8935                     arg = fold_convert_loc(location.gcc_location(),
8936                                            double_type_node, arg);
8937                   }
8938                 else if (type->complex_type() != NULL)
8939                   {
8940                     static tree print_complex_fndecl;
8941                     pfndecl = &print_complex_fndecl;
8942                     fnname = "__go_print_complex";
8943                     arg = fold_convert_loc(location.gcc_location(),
8944                                            complex_double_type_node, arg);
8945                   }
8946                 else if (type->is_boolean_type())
8947                   {
8948                     static tree print_bool_fndecl;
8949                     pfndecl = &print_bool_fndecl;
8950                     fnname = "__go_print_bool";
8951                   }
8952                 else if (type->points_to() != NULL
8953                          || type->channel_type() != NULL
8954                          || type->map_type() != NULL
8955                          || type->function_type() != NULL)
8956                   {
8957                     static tree print_pointer_fndecl;
8958                     pfndecl = &print_pointer_fndecl;
8959                     fnname = "__go_print_pointer";
8960                     arg = fold_convert_loc(location.gcc_location(),
8961                                            ptr_type_node, arg);
8962                   }
8963                 else if (type->interface_type() != NULL)
8964                   {
8965                     if (type->interface_type()->is_empty())
8966                       {
8967                         static tree print_empty_interface_fndecl;
8968                         pfndecl = &print_empty_interface_fndecl;
8969                         fnname = "__go_print_empty_interface";
8970                       }
8971                     else
8972                       {
8973                         static tree print_interface_fndecl;
8974                         pfndecl = &print_interface_fndecl;
8975                         fnname = "__go_print_interface";
8976                       }
8977                   }
8978                 else if (type->is_slice_type())
8979                   {
8980                     static tree print_slice_fndecl;
8981                     pfndecl = &print_slice_fndecl;
8982                     fnname = "__go_print_slice";
8983                   }
8984                 else
8985                   go_unreachable();
8986
8987                 tree call = Gogo::call_builtin(pfndecl,
8988                                                location,
8989                                                fnname,
8990                                                1,
8991                                                void_type_node,
8992                                                TREE_TYPE(arg),
8993                                                arg);
8994                 if (call == error_mark_node)
8995                   return error_mark_node;
8996                 append_to_statement_list(call, &stmt_list);
8997               }
8998           }
8999
9000         if (is_ln)
9001           {
9002             static tree print_nl_fndecl;
9003             tree call = Gogo::call_builtin(&print_nl_fndecl,
9004                                            location,
9005                                            "__go_print_nl",
9006                                            0,
9007                                            void_type_node);
9008             if (call == error_mark_node)
9009               return error_mark_node;
9010             append_to_statement_list(call, &stmt_list);
9011           }
9012
9013         return stmt_list;
9014       }
9015
9016     case BUILTIN_PANIC:
9017       {
9018         const Expression_list* args = this->args();
9019         go_assert(args != NULL && args->size() == 1);
9020         Expression* arg = args->front();
9021         tree arg_tree = arg->get_tree(context);
9022         if (arg_tree == error_mark_node)
9023           return error_mark_node;
9024         Type *empty =
9025           Type::make_empty_interface_type(Linemap::predeclared_location());
9026         arg_tree = Expression::convert_for_assignment(context, empty,
9027                                                       arg->type(),
9028                                                       arg_tree, location);
9029         static tree panic_fndecl;
9030         tree call = Gogo::call_builtin(&panic_fndecl,
9031                                        location,
9032                                        "__go_panic",
9033                                        1,
9034                                        void_type_node,
9035                                        TREE_TYPE(arg_tree),
9036                                        arg_tree);
9037         if (call == error_mark_node)
9038           return error_mark_node;
9039         // This function will throw an exception.
9040         TREE_NOTHROW(panic_fndecl) = 0;
9041         // This function will not return.
9042         TREE_THIS_VOLATILE(panic_fndecl) = 1;
9043         return call;
9044       }
9045
9046     case BUILTIN_RECOVER:
9047       {
9048         // The argument is set when building recover thunks.  It's a
9049         // boolean value which is true if we can recover a value now.
9050         const Expression_list* args = this->args();
9051         go_assert(args != NULL && args->size() == 1);
9052         Expression* arg = args->front();
9053         tree arg_tree = arg->get_tree(context);
9054         if (arg_tree == error_mark_node)
9055           return error_mark_node;
9056
9057         Type *empty =
9058           Type::make_empty_interface_type(Linemap::predeclared_location());
9059         tree empty_tree = type_to_tree(empty->get_backend(context->gogo()));
9060
9061         Type* nil_type = Type::make_nil_type();
9062         Expression* nil = Expression::make_nil(location);
9063         tree nil_tree = nil->get_tree(context);
9064         tree empty_nil_tree = Expression::convert_for_assignment(context,
9065                                                                  empty,
9066                                                                  nil_type,
9067                                                                  nil_tree,
9068                                                                  location);
9069
9070         // We need to handle a deferred call to recover specially,
9071         // because it changes whether it can recover a panic or not.
9072         // See test7 in test/recover1.go.
9073         tree call;
9074         if (this->is_deferred())
9075           {
9076             static tree deferred_recover_fndecl;
9077             call = Gogo::call_builtin(&deferred_recover_fndecl,
9078                                       location,
9079                                       "__go_deferred_recover",
9080                                       0,
9081                                       empty_tree);
9082           }
9083         else
9084           {
9085             static tree recover_fndecl;
9086             call = Gogo::call_builtin(&recover_fndecl,
9087                                       location,
9088                                       "__go_recover",
9089                                       0,
9090                                       empty_tree);
9091           }
9092         if (call == error_mark_node)
9093           return error_mark_node;
9094         return fold_build3_loc(location.gcc_location(), COND_EXPR, empty_tree,
9095                                arg_tree, call, empty_nil_tree);
9096       }
9097
9098     case BUILTIN_CLOSE:
9099       {
9100         const Expression_list* args = this->args();
9101         go_assert(args != NULL && args->size() == 1);
9102         Expression* arg = args->front();
9103         tree arg_tree = arg->get_tree(context);
9104         if (arg_tree == error_mark_node)
9105           return error_mark_node;
9106         static tree close_fndecl;
9107         return Gogo::call_builtin(&close_fndecl,
9108                                   location,
9109                                   "__go_builtin_close",
9110                                   1,
9111                                   void_type_node,
9112                                   TREE_TYPE(arg_tree),
9113                                   arg_tree);
9114       }
9115
9116     case BUILTIN_SIZEOF:
9117     case BUILTIN_OFFSETOF:
9118     case BUILTIN_ALIGNOF:
9119       {
9120         mpz_t val;
9121         mpz_init(val);
9122         Type* dummy;
9123         bool b = this->integer_constant_value(true, val, &dummy);
9124         if (!b)
9125           {
9126             go_assert(saw_errors());
9127             return error_mark_node;
9128           }
9129         Type* int_type = Type::lookup_integer_type("int");
9130         tree type = type_to_tree(int_type->get_backend(gogo));
9131         tree ret = Expression::integer_constant_tree(val, type);
9132         mpz_clear(val);
9133         return ret;
9134       }
9135
9136     case BUILTIN_COPY:
9137       {
9138         const Expression_list* args = this->args();
9139         go_assert(args != NULL && args->size() == 2);
9140         Expression* arg1 = args->front();
9141         Expression* arg2 = args->back();
9142
9143         tree arg1_tree = arg1->get_tree(context);
9144         tree arg2_tree = arg2->get_tree(context);
9145         if (arg1_tree == error_mark_node || arg2_tree == error_mark_node)
9146           return error_mark_node;
9147
9148         Type* arg1_type = arg1->type();
9149         Array_type* at = arg1_type->array_type();
9150         arg1_tree = save_expr(arg1_tree);
9151         tree arg1_val = at->value_pointer_tree(gogo, arg1_tree);
9152         tree arg1_len = at->length_tree(gogo, arg1_tree);
9153         if (arg1_val == error_mark_node || arg1_len == error_mark_node)
9154           return error_mark_node;
9155
9156         Type* arg2_type = arg2->type();
9157         tree arg2_val;
9158         tree arg2_len;
9159         if (arg2_type->is_slice_type())
9160           {
9161             at = arg2_type->array_type();
9162             arg2_tree = save_expr(arg2_tree);
9163             arg2_val = at->value_pointer_tree(gogo, arg2_tree);
9164             arg2_len = at->length_tree(gogo, arg2_tree);
9165           }
9166         else
9167           {
9168             arg2_tree = save_expr(arg2_tree);
9169             arg2_val = String_type::bytes_tree(gogo, arg2_tree);
9170             arg2_len = String_type::length_tree(gogo, arg2_tree);
9171           }
9172         if (arg2_val == error_mark_node || arg2_len == error_mark_node)
9173           return error_mark_node;
9174
9175         arg1_len = save_expr(arg1_len);
9176         arg2_len = save_expr(arg2_len);
9177         tree len = fold_build3_loc(location.gcc_location(), COND_EXPR,
9178                                    TREE_TYPE(arg1_len),
9179                                    fold_build2_loc(location.gcc_location(),
9180                                                    LT_EXPR, boolean_type_node,
9181                                                    arg1_len, arg2_len),
9182                                    arg1_len, arg2_len);
9183         len = save_expr(len);
9184
9185         Type* element_type = at->element_type();
9186         Btype* element_btype = element_type->get_backend(gogo);
9187         tree element_type_tree = type_to_tree(element_btype);
9188         if (element_type_tree == error_mark_node)
9189           return error_mark_node;
9190         tree element_size = TYPE_SIZE_UNIT(element_type_tree);
9191         tree bytecount = fold_convert_loc(location.gcc_location(),
9192                                           TREE_TYPE(element_size), len);
9193         bytecount = fold_build2_loc(location.gcc_location(), MULT_EXPR,
9194                                     TREE_TYPE(element_size),
9195                                     bytecount, element_size);
9196         bytecount = fold_convert_loc(location.gcc_location(), size_type_node,
9197                                      bytecount);
9198
9199         arg1_val = fold_convert_loc(location.gcc_location(), ptr_type_node,
9200                                     arg1_val);
9201         arg2_val = fold_convert_loc(location.gcc_location(), ptr_type_node,
9202                                     arg2_val);
9203
9204         static tree copy_fndecl;
9205         tree call = Gogo::call_builtin(&copy_fndecl,
9206                                        location,
9207                                        "__go_copy",
9208                                        3,
9209                                        void_type_node,
9210                                        ptr_type_node,
9211                                        arg1_val,
9212                                        ptr_type_node,
9213                                        arg2_val,
9214                                        size_type_node,
9215                                        bytecount);
9216         if (call == error_mark_node)
9217           return error_mark_node;
9218
9219         return fold_build2_loc(location.gcc_location(), COMPOUND_EXPR,
9220                                TREE_TYPE(len), call, len);
9221       }
9222
9223     case BUILTIN_APPEND:
9224       {
9225         const Expression_list* args = this->args();
9226         go_assert(args != NULL && args->size() == 2);
9227         Expression* arg1 = args->front();
9228         Expression* arg2 = args->back();
9229
9230         tree arg1_tree = arg1->get_tree(context);
9231         tree arg2_tree = arg2->get_tree(context);
9232         if (arg1_tree == error_mark_node || arg2_tree == error_mark_node)
9233           return error_mark_node;
9234
9235         Array_type* at = arg1->type()->array_type();
9236         Type* element_type = at->element_type()->forwarded();
9237
9238         tree arg2_val;
9239         tree arg2_len;
9240         tree element_size;
9241         if (arg2->type()->is_string_type()
9242             && element_type->integer_type() != NULL
9243             && element_type->integer_type()->is_byte())
9244           {
9245             arg2_tree = save_expr(arg2_tree);
9246             arg2_val = String_type::bytes_tree(gogo, arg2_tree);
9247             arg2_len = String_type::length_tree(gogo, arg2_tree);
9248             element_size = size_int(1);
9249           }
9250         else
9251           {
9252             arg2_tree = Expression::convert_for_assignment(context, at,
9253                                                            arg2->type(),
9254                                                            arg2_tree,
9255                                                            location);
9256             if (arg2_tree == error_mark_node)
9257               return error_mark_node;
9258
9259             arg2_tree = save_expr(arg2_tree);
9260
9261              arg2_val = at->value_pointer_tree(gogo, arg2_tree);
9262              arg2_len = at->length_tree(gogo, arg2_tree);
9263
9264              Btype* element_btype = element_type->get_backend(gogo);
9265              tree element_type_tree = type_to_tree(element_btype);
9266              if (element_type_tree == error_mark_node)
9267                return error_mark_node;
9268              element_size = TYPE_SIZE_UNIT(element_type_tree);
9269           }
9270
9271         arg2_val = fold_convert_loc(location.gcc_location(), ptr_type_node,
9272                                     arg2_val);
9273         arg2_len = fold_convert_loc(location.gcc_location(), size_type_node,
9274                                     arg2_len);
9275         element_size = fold_convert_loc(location.gcc_location(), size_type_node,
9276                                         element_size);
9277
9278         if (arg2_val == error_mark_node
9279             || arg2_len == error_mark_node
9280             || element_size == error_mark_node)
9281           return error_mark_node;
9282
9283         // We rebuild the decl each time since the slice types may
9284         // change.
9285         tree append_fndecl = NULL_TREE;
9286         return Gogo::call_builtin(&append_fndecl,
9287                                   location,
9288                                   "__go_append",
9289                                   4,
9290                                   TREE_TYPE(arg1_tree),
9291                                   TREE_TYPE(arg1_tree),
9292                                   arg1_tree,
9293                                   ptr_type_node,
9294                                   arg2_val,
9295                                   size_type_node,
9296                                   arg2_len,
9297                                   size_type_node,
9298                                   element_size);
9299       }
9300
9301     case BUILTIN_REAL:
9302     case BUILTIN_IMAG:
9303       {
9304         const Expression_list* args = this->args();
9305         go_assert(args != NULL && args->size() == 1);
9306         Expression* arg = args->front();
9307         tree arg_tree = arg->get_tree(context);
9308         if (arg_tree == error_mark_node)
9309           return error_mark_node;
9310         go_assert(COMPLEX_FLOAT_TYPE_P(TREE_TYPE(arg_tree)));
9311         if (this->code_ == BUILTIN_REAL)
9312           return fold_build1_loc(location.gcc_location(), REALPART_EXPR,
9313                                  TREE_TYPE(TREE_TYPE(arg_tree)),
9314                                  arg_tree);
9315         else
9316           return fold_build1_loc(location.gcc_location(), IMAGPART_EXPR,
9317                                  TREE_TYPE(TREE_TYPE(arg_tree)),
9318                                  arg_tree);
9319       }
9320
9321     case BUILTIN_COMPLEX:
9322       {
9323         const Expression_list* args = this->args();
9324         go_assert(args != NULL && args->size() == 2);
9325         tree r = args->front()->get_tree(context);
9326         tree i = args->back()->get_tree(context);
9327         if (r == error_mark_node || i == error_mark_node)
9328           return error_mark_node;
9329         go_assert(TYPE_MAIN_VARIANT(TREE_TYPE(r))
9330                    == TYPE_MAIN_VARIANT(TREE_TYPE(i)));
9331         go_assert(SCALAR_FLOAT_TYPE_P(TREE_TYPE(r)));
9332         return fold_build2_loc(location.gcc_location(), COMPLEX_EXPR,
9333                                build_complex_type(TREE_TYPE(r)),
9334                                r, i);
9335       }
9336
9337     default:
9338       go_unreachable();
9339     }
9340 }
9341
9342 // We have to support exporting a builtin call expression, because
9343 // code can set a constant to the result of a builtin expression.
9344
9345 void
9346 Builtin_call_expression::do_export(Export* exp) const
9347 {
9348   bool ok = false;
9349
9350   mpz_t val;
9351   mpz_init(val);
9352   Type* dummy;
9353   if (this->integer_constant_value(true, val, &dummy))
9354     {
9355       Integer_expression::export_integer(exp, val);
9356       ok = true;
9357     }
9358   mpz_clear(val);
9359
9360   if (!ok)
9361     {
9362       mpfr_t fval;
9363       mpfr_init(fval);
9364       if (this->float_constant_value(fval, &dummy))
9365         {
9366           Float_expression::export_float(exp, fval);
9367           ok = true;
9368         }
9369       mpfr_clear(fval);
9370     }
9371
9372   if (!ok)
9373     {
9374       mpfr_t real;
9375       mpfr_t imag;
9376       mpfr_init(real);
9377       mpfr_init(imag);
9378       if (this->complex_constant_value(real, imag, &dummy))
9379         {
9380           Complex_expression::export_complex(exp, real, imag);
9381           ok = true;
9382         }
9383       mpfr_clear(real);
9384       mpfr_clear(imag);
9385     }
9386
9387   if (!ok)
9388     {
9389       error_at(this->location(), "value is not constant");
9390       return;
9391     }
9392
9393   // A trailing space lets us reliably identify the end of the number.
9394   exp->write_c_string(" ");
9395 }
9396
9397 // Class Call_expression.
9398
9399 // Traversal.
9400
9401 int
9402 Call_expression::do_traverse(Traverse* traverse)
9403 {
9404   if (Expression::traverse(&this->fn_, traverse) == TRAVERSE_EXIT)
9405     return TRAVERSE_EXIT;
9406   if (this->args_ != NULL)
9407     {
9408       if (this->args_->traverse(traverse) == TRAVERSE_EXIT)
9409         return TRAVERSE_EXIT;
9410     }
9411   return TRAVERSE_CONTINUE;
9412 }
9413
9414 // Lower a call statement.
9415
9416 Expression*
9417 Call_expression::do_lower(Gogo* gogo, Named_object* function,
9418                           Statement_inserter* inserter, int)
9419 {
9420   Location loc = this->location();
9421
9422   // A type cast can look like a function call.
9423   if (this->fn_->is_type_expression()
9424       && this->args_ != NULL
9425       && this->args_->size() == 1)
9426     return Expression::make_cast(this->fn_->type(), this->args_->front(),
9427                                  loc);
9428
9429   // Recognize a call to a builtin function.
9430   Func_expression* fne = this->fn_->func_expression();
9431   if (fne != NULL
9432       && fne->named_object()->is_function_declaration()
9433       && fne->named_object()->func_declaration_value()->type()->is_builtin())
9434     return new Builtin_call_expression(gogo, this->fn_, this->args_,
9435                                        this->is_varargs_, loc);
9436
9437   // Handle an argument which is a call to a function which returns
9438   // multiple results.
9439   if (this->args_ != NULL
9440       && this->args_->size() == 1
9441       && this->args_->front()->call_expression() != NULL
9442       && this->fn_->type()->function_type() != NULL)
9443     {
9444       Function_type* fntype = this->fn_->type()->function_type();
9445       size_t rc = this->args_->front()->call_expression()->result_count();
9446       if (rc > 1
9447           && fntype->parameters() != NULL
9448           && (fntype->parameters()->size() == rc
9449               || (fntype->is_varargs()
9450                   && fntype->parameters()->size() - 1 <= rc)))
9451         {
9452           Call_expression* call = this->args_->front()->call_expression();
9453           Expression_list* args = new Expression_list;
9454           for (size_t i = 0; i < rc; ++i)
9455             args->push_back(Expression::make_call_result(call, i));
9456           // We can't return a new call expression here, because this
9457           // one may be referenced by Call_result expressions.  We
9458           // also can't delete the old arguments, because we may still
9459           // traverse them somewhere up the call stack.  FIXME.
9460           this->args_ = args;
9461         }
9462     }
9463
9464   // If this call returns multiple results, create a temporary
9465   // variable for each result.
9466   size_t rc = this->result_count();
9467   if (rc > 1 && this->results_ == NULL)
9468     {
9469       std::vector<Temporary_statement*>* temps =
9470         new std::vector<Temporary_statement*>;
9471       temps->reserve(rc);
9472       const Typed_identifier_list* results =
9473         this->fn_->type()->function_type()->results();
9474       for (Typed_identifier_list::const_iterator p = results->begin();
9475            p != results->end();
9476            ++p)
9477         {
9478           Temporary_statement* temp = Statement::make_temporary(p->type(),
9479                                                                 NULL, loc);
9480           inserter->insert(temp);
9481           temps->push_back(temp);
9482         }
9483       this->results_ = temps;
9484     }
9485
9486   // Handle a call to a varargs function by packaging up the extra
9487   // parameters.
9488   if (this->fn_->type()->function_type() != NULL
9489       && this->fn_->type()->function_type()->is_varargs())
9490     {
9491       Function_type* fntype = this->fn_->type()->function_type();
9492       const Typed_identifier_list* parameters = fntype->parameters();
9493       go_assert(parameters != NULL && !parameters->empty());
9494       Type* varargs_type = parameters->back().type();
9495       this->lower_varargs(gogo, function, inserter, varargs_type,
9496                           parameters->size());
9497     }
9498
9499   // If this is call to a method, call the method directly passing the
9500   // object as the first parameter.
9501   Bound_method_expression* bme = this->fn_->bound_method_expression();
9502   if (bme != NULL)
9503     {
9504       Named_object* method = bme->method();
9505       Expression* first_arg = bme->first_argument();
9506
9507       // We always pass a pointer when calling a method.
9508       if (first_arg->type()->points_to() == NULL
9509           && !first_arg->type()->is_error())
9510         {
9511           first_arg = Expression::make_unary(OPERATOR_AND, first_arg, loc);
9512           // We may need to create a temporary variable so that we can
9513           // take the address.  We can't do that here because it will
9514           // mess up the order of evaluation.
9515           Unary_expression* ue = static_cast<Unary_expression*>(first_arg);
9516           ue->set_create_temp();
9517         }
9518
9519       // If we are calling a method which was inherited from an
9520       // embedded struct, and the method did not get a stub, then the
9521       // first type may be wrong.
9522       Type* fatype = bme->first_argument_type();
9523       if (fatype != NULL)
9524         {
9525           if (fatype->points_to() == NULL)
9526             fatype = Type::make_pointer_type(fatype);
9527           first_arg = Expression::make_unsafe_cast(fatype, first_arg, loc);
9528         }
9529
9530       Expression_list* new_args = new Expression_list();
9531       new_args->push_back(first_arg);
9532       if (this->args_ != NULL)
9533         {
9534           for (Expression_list::const_iterator p = this->args_->begin();
9535                p != this->args_->end();
9536                ++p)
9537             new_args->push_back(*p);
9538         }
9539
9540       // We have to change in place because this structure may be
9541       // referenced by Call_result_expressions.  We can't delete the
9542       // old arguments, because we may be traversing them up in some
9543       // caller.  FIXME.
9544       this->args_ = new_args;
9545       this->fn_ = Expression::make_func_reference(method, NULL,
9546                                                   bme->location());
9547     }
9548
9549   return this;
9550 }
9551
9552 // Lower a call to a varargs function.  FUNCTION is the function in
9553 // which the call occurs--it's not the function we are calling.
9554 // VARARGS_TYPE is the type of the varargs parameter, a slice type.
9555 // PARAM_COUNT is the number of parameters of the function we are
9556 // calling; the last of these parameters will be the varargs
9557 // parameter.
9558
9559 void
9560 Call_expression::lower_varargs(Gogo* gogo, Named_object* function,
9561                                Statement_inserter* inserter,
9562                                Type* varargs_type, size_t param_count)
9563 {
9564   if (this->varargs_are_lowered_)
9565     return;
9566
9567   Location loc = this->location();
9568
9569   go_assert(param_count > 0);
9570   go_assert(varargs_type->is_slice_type());
9571
9572   size_t arg_count = this->args_ == NULL ? 0 : this->args_->size();
9573   if (arg_count < param_count - 1)
9574     {
9575       // Not enough arguments; will be caught in check_types.
9576       return;
9577     }
9578
9579   Expression_list* old_args = this->args_;
9580   Expression_list* new_args = new Expression_list();
9581   bool push_empty_arg = false;
9582   if (old_args == NULL || old_args->empty())
9583     {
9584       go_assert(param_count == 1);
9585       push_empty_arg = true;
9586     }
9587   else
9588     {
9589       Expression_list::const_iterator pa;
9590       int i = 1;
9591       for (pa = old_args->begin(); pa != old_args->end(); ++pa, ++i)
9592         {
9593           if (static_cast<size_t>(i) == param_count)
9594             break;
9595           new_args->push_back(*pa);
9596         }
9597
9598       // We have reached the varargs parameter.
9599
9600       bool issued_error = false;
9601       if (pa == old_args->end())
9602         push_empty_arg = true;
9603       else if (pa + 1 == old_args->end() && this->is_varargs_)
9604         new_args->push_back(*pa);
9605       else if (this->is_varargs_)
9606         {
9607           this->report_error(_("too many arguments"));
9608           return;
9609         }
9610       else
9611         {
9612           Type* element_type = varargs_type->array_type()->element_type();
9613           Expression_list* vals = new Expression_list;
9614           for (; pa != old_args->end(); ++pa, ++i)
9615             {
9616               // Check types here so that we get a better message.
9617               Type* patype = (*pa)->type();
9618               Location paloc = (*pa)->location();
9619               if (!this->check_argument_type(i, element_type, patype,
9620                                              paloc, issued_error))
9621                 continue;
9622               vals->push_back(*pa);
9623             }
9624           Expression* val =
9625             Expression::make_slice_composite_literal(varargs_type, vals, loc);
9626           gogo->lower_expression(function, inserter, &val);
9627           new_args->push_back(val);
9628         }
9629     }
9630
9631   if (push_empty_arg)
9632     new_args->push_back(Expression::make_nil(loc));
9633
9634   // We can't return a new call expression here, because this one may
9635   // be referenced by Call_result expressions.  FIXME.  We can't
9636   // delete OLD_ARGS because we may have both a Call_expression and a
9637   // Builtin_call_expression which refer to them.  FIXME.
9638   this->args_ = new_args;
9639   this->varargs_are_lowered_ = true;
9640 }
9641
9642 // Get the function type.  This can return NULL in error cases.
9643
9644 Function_type*
9645 Call_expression::get_function_type() const
9646 {
9647   return this->fn_->type()->function_type();
9648 }
9649
9650 // Return the number of values which this call will return.
9651
9652 size_t
9653 Call_expression::result_count() const
9654 {
9655   const Function_type* fntype = this->get_function_type();
9656   if (fntype == NULL)
9657     return 0;
9658   if (fntype->results() == NULL)
9659     return 0;
9660   return fntype->results()->size();
9661 }
9662
9663 // Return the temporary which holds a result.
9664
9665 Temporary_statement*
9666 Call_expression::result(size_t i) const
9667 {
9668   go_assert(this->results_ != NULL
9669             && this->results_->size() > i);
9670   return (*this->results_)[i];
9671 }
9672
9673 // Return whether this is a call to the predeclared function recover.
9674
9675 bool
9676 Call_expression::is_recover_call() const
9677 {
9678   return this->do_is_recover_call();
9679 }
9680
9681 // Set the argument to the recover function.
9682
9683 void
9684 Call_expression::set_recover_arg(Expression* arg)
9685 {
9686   this->do_set_recover_arg(arg);
9687 }
9688
9689 // Virtual functions also implemented by Builtin_call_expression.
9690
9691 bool
9692 Call_expression::do_is_recover_call() const
9693 {
9694   return false;
9695 }
9696
9697 void
9698 Call_expression::do_set_recover_arg(Expression*)
9699 {
9700   go_unreachable();
9701 }
9702
9703 // We have found an error with this call expression; return true if
9704 // we should report it.
9705
9706 bool
9707 Call_expression::issue_error()
9708 {
9709   if (this->issued_error_)
9710     return false;
9711   else
9712     {
9713       this->issued_error_ = true;
9714       return true;
9715     }
9716 }
9717
9718 // Get the type.
9719
9720 Type*
9721 Call_expression::do_type()
9722 {
9723   if (this->type_ != NULL)
9724     return this->type_;
9725
9726   Type* ret;
9727   Function_type* fntype = this->get_function_type();
9728   if (fntype == NULL)
9729     return Type::make_error_type();
9730
9731   const Typed_identifier_list* results = fntype->results();
9732   if (results == NULL)
9733     ret = Type::make_void_type();
9734   else if (results->size() == 1)
9735     ret = results->begin()->type();
9736   else
9737     ret = Type::make_call_multiple_result_type(this);
9738
9739   this->type_ = ret;
9740
9741   return this->type_;
9742 }
9743
9744 // Determine types for a call expression.  We can use the function
9745 // parameter types to set the types of the arguments.
9746
9747 void
9748 Call_expression::do_determine_type(const Type_context*)
9749 {
9750   if (!this->determining_types())
9751     return;
9752
9753   this->fn_->determine_type_no_context();
9754   Function_type* fntype = this->get_function_type();
9755   const Typed_identifier_list* parameters = NULL;
9756   if (fntype != NULL)
9757     parameters = fntype->parameters();
9758   if (this->args_ != NULL)
9759     {
9760       Typed_identifier_list::const_iterator pt;
9761       if (parameters != NULL)
9762         pt = parameters->begin();
9763       bool first = true;
9764       for (Expression_list::const_iterator pa = this->args_->begin();
9765            pa != this->args_->end();
9766            ++pa)
9767         {
9768           if (first)
9769             {
9770               first = false;
9771               // If this is a method, the first argument is the
9772               // receiver.
9773               if (fntype != NULL && fntype->is_method())
9774                 {
9775                   Type* rtype = fntype->receiver()->type();
9776                   // The receiver is always passed as a pointer.
9777                   if (rtype->points_to() == NULL)
9778                     rtype = Type::make_pointer_type(rtype);
9779                   Type_context subcontext(rtype, false);
9780                   (*pa)->determine_type(&subcontext);
9781                   continue;
9782                 }
9783             }
9784
9785           if (parameters != NULL && pt != parameters->end())
9786             {
9787               Type_context subcontext(pt->type(), false);
9788               (*pa)->determine_type(&subcontext);
9789               ++pt;
9790             }
9791           else
9792             (*pa)->determine_type_no_context();
9793         }
9794     }
9795 }
9796
9797 // Called when determining types for a Call_expression.  Return true
9798 // if we should go ahead, false if they have already been determined.
9799
9800 bool
9801 Call_expression::determining_types()
9802 {
9803   if (this->types_are_determined_)
9804     return false;
9805   else
9806     {
9807       this->types_are_determined_ = true;
9808       return true;
9809     }
9810 }
9811
9812 // Check types for parameter I.
9813
9814 bool
9815 Call_expression::check_argument_type(int i, const Type* parameter_type,
9816                                      const Type* argument_type,
9817                                      Location argument_location,
9818                                      bool issued_error)
9819 {
9820   std::string reason;
9821   bool ok;
9822   if (this->are_hidden_fields_ok_)
9823     ok = Type::are_assignable_hidden_ok(parameter_type, argument_type,
9824                                         &reason);
9825   else
9826     ok = Type::are_assignable(parameter_type, argument_type, &reason);
9827   if (!ok)
9828     {
9829       if (!issued_error)
9830         {
9831           if (reason.empty())
9832             error_at(argument_location, "argument %d has incompatible type", i);
9833           else
9834             error_at(argument_location,
9835                      "argument %d has incompatible type (%s)",
9836                      i, reason.c_str());
9837         }
9838       this->set_is_error();
9839       return false;
9840     }
9841   return true;
9842 }
9843
9844 // Check types.
9845
9846 void
9847 Call_expression::do_check_types(Gogo*)
9848 {
9849   Function_type* fntype = this->get_function_type();
9850   if (fntype == NULL)
9851     {
9852       if (!this->fn_->type()->is_error())
9853         this->report_error(_("expected function"));
9854       return;
9855     }
9856
9857   bool is_method = fntype->is_method();
9858   if (is_method)
9859     {
9860       go_assert(this->args_ != NULL && !this->args_->empty());
9861       Type* rtype = fntype->receiver()->type();
9862       Expression* first_arg = this->args_->front();
9863       // The language permits copying hidden fields for a method
9864       // receiver.  We dereference the values since receivers are
9865       // always passed as pointers.
9866       std::string reason;
9867       if (!Type::are_assignable_hidden_ok(rtype->deref(),
9868                                           first_arg->type()->deref(),
9869                                           &reason))
9870         {
9871           if (reason.empty())
9872             this->report_error(_("incompatible type for receiver"));
9873           else
9874             {
9875               error_at(this->location(),
9876                        "incompatible type for receiver (%s)",
9877                        reason.c_str());
9878               this->set_is_error();
9879             }
9880         }
9881     }
9882
9883   // Note that varargs was handled by the lower_varargs() method, so
9884   // we don't have to worry about it here.
9885
9886   const Typed_identifier_list* parameters = fntype->parameters();
9887   if (this->args_ == NULL)
9888     {
9889       if (parameters != NULL && !parameters->empty())
9890         this->report_error(_("not enough arguments"));
9891     }
9892   else if (parameters == NULL)
9893     {
9894       if (!is_method || this->args_->size() > 1)
9895         this->report_error(_("too many arguments"));
9896     }
9897   else
9898     {
9899       int i = 0;
9900       Expression_list::const_iterator pa = this->args_->begin();
9901       if (is_method)
9902         ++pa;
9903       for (Typed_identifier_list::const_iterator pt = parameters->begin();
9904            pt != parameters->end();
9905            ++pt, ++pa, ++i)
9906         {
9907           if (pa == this->args_->end())
9908             {
9909               this->report_error(_("not enough arguments"));
9910               return;
9911             }
9912           this->check_argument_type(i + 1, pt->type(), (*pa)->type(),
9913                                     (*pa)->location(), false);
9914         }
9915       if (pa != this->args_->end())
9916         this->report_error(_("too many arguments"));
9917     }
9918 }
9919
9920 // Return whether we have to use a temporary variable to ensure that
9921 // we evaluate this call expression in order.  If the call returns no
9922 // results then it will inevitably be executed last.
9923
9924 bool
9925 Call_expression::do_must_eval_in_order() const
9926 {
9927   return this->result_count() > 0;
9928 }
9929
9930 // Get the function and the first argument to use when calling an
9931 // interface method.
9932
9933 tree
9934 Call_expression::interface_method_function(
9935     Translate_context* context,
9936     Interface_field_reference_expression* interface_method,
9937     tree* first_arg_ptr)
9938 {
9939   tree expr = interface_method->expr()->get_tree(context);
9940   if (expr == error_mark_node)
9941     return error_mark_node;
9942   expr = save_expr(expr);
9943   tree first_arg = interface_method->get_underlying_object_tree(context, expr);
9944   if (first_arg == error_mark_node)
9945     return error_mark_node;
9946   *first_arg_ptr = first_arg;
9947   return interface_method->get_function_tree(context, expr);
9948 }
9949
9950 // Build the call expression.
9951
9952 tree
9953 Call_expression::do_get_tree(Translate_context* context)
9954 {
9955   if (this->tree_ != NULL_TREE)
9956     return this->tree_;
9957
9958   Function_type* fntype = this->get_function_type();
9959   if (fntype == NULL)
9960     return error_mark_node;
9961
9962   if (this->fn_->is_error_expression())
9963     return error_mark_node;
9964
9965   Gogo* gogo = context->gogo();
9966   Location location = this->location();
9967
9968   Func_expression* func = this->fn_->func_expression();
9969   Interface_field_reference_expression* interface_method =
9970     this->fn_->interface_field_reference_expression();
9971   const bool has_closure = func != NULL && func->closure() != NULL;
9972   const bool is_interface_method = interface_method != NULL;
9973
9974   int nargs;
9975   tree* args;
9976   if (this->args_ == NULL || this->args_->empty())
9977     {
9978       nargs = is_interface_method ? 1 : 0;
9979       args = nargs == 0 ? NULL : new tree[nargs];
9980     }
9981   else if (fntype->parameters() == NULL || fntype->parameters()->empty())
9982     {
9983       // Passing a receiver parameter.
9984       go_assert(!is_interface_method
9985                 && fntype->is_method()
9986                 && this->args_->size() == 1);
9987       nargs = 1;
9988       args = new tree[nargs];
9989       args[0] = this->args_->front()->get_tree(context);
9990     }
9991   else
9992     {
9993       const Typed_identifier_list* params = fntype->parameters();
9994
9995       nargs = this->args_->size();
9996       int i = is_interface_method ? 1 : 0;
9997       nargs += i;
9998       args = new tree[nargs];
9999
10000       Typed_identifier_list::const_iterator pp = params->begin();
10001       Expression_list::const_iterator pe = this->args_->begin();
10002       if (!is_interface_method && fntype->is_method())
10003         {
10004           args[i] = (*pe)->get_tree(context);
10005           ++pe;
10006           ++i;
10007         }
10008       for (; pe != this->args_->end(); ++pe, ++pp, ++i)
10009         {
10010           go_assert(pp != params->end());
10011           tree arg_val = (*pe)->get_tree(context);
10012           args[i] = Expression::convert_for_assignment(context,
10013                                                        pp->type(),
10014                                                        (*pe)->type(),
10015                                                        arg_val,
10016                                                        location);
10017           if (args[i] == error_mark_node)
10018             {
10019               delete[] args;
10020               return error_mark_node;
10021             }
10022         }
10023       go_assert(pp == params->end());
10024       go_assert(i == nargs);
10025     }
10026
10027   tree rettype = TREE_TYPE(TREE_TYPE(type_to_tree(fntype->get_backend(gogo))));
10028   if (rettype == error_mark_node)
10029     {
10030       delete[] args;
10031       return error_mark_node;
10032     }
10033
10034   tree fn;
10035   if (has_closure)
10036     fn = func->get_tree_without_closure(gogo);
10037   else if (!is_interface_method)
10038     fn = this->fn_->get_tree(context);
10039   else
10040     fn = this->interface_method_function(context, interface_method, &args[0]);
10041
10042   if (fn == error_mark_node || TREE_TYPE(fn) == error_mark_node)
10043     {
10044       delete[] args;
10045       return error_mark_node;
10046     }
10047
10048   tree fndecl = fn;
10049   if (TREE_CODE(fndecl) == ADDR_EXPR)
10050     fndecl = TREE_OPERAND(fndecl, 0);
10051
10052   // Add a type cast in case the type of the function is a recursive
10053   // type which refers to itself.
10054   if (!DECL_P(fndecl) || !DECL_IS_BUILTIN(fndecl))
10055     {
10056       tree fnt = type_to_tree(fntype->get_backend(gogo));
10057       if (fnt == error_mark_node)
10058         return error_mark_node;
10059       fn = fold_convert_loc(location.gcc_location(), fnt, fn);
10060     }
10061
10062   // This is to support builtin math functions when using 80387 math.
10063   tree excess_type = NULL_TREE;
10064   if (optimize
10065       && TREE_CODE(fndecl) == FUNCTION_DECL
10066       && DECL_IS_BUILTIN(fndecl)
10067       && DECL_BUILT_IN_CLASS(fndecl) == BUILT_IN_NORMAL
10068       && nargs > 0
10069       && ((SCALAR_FLOAT_TYPE_P(rettype)
10070            && SCALAR_FLOAT_TYPE_P(TREE_TYPE(args[0])))
10071           || (COMPLEX_FLOAT_TYPE_P(rettype)
10072               && COMPLEX_FLOAT_TYPE_P(TREE_TYPE(args[0])))))
10073     {
10074       excess_type = excess_precision_type(TREE_TYPE(args[0]));
10075       if (excess_type != NULL_TREE)
10076         {
10077           tree excess_fndecl = mathfn_built_in(excess_type,
10078                                                DECL_FUNCTION_CODE(fndecl));
10079           if (excess_fndecl == NULL_TREE)
10080             excess_type = NULL_TREE;
10081           else
10082             {
10083               fn = build_fold_addr_expr_loc(location.gcc_location(),
10084                                             excess_fndecl);
10085               for (int i = 0; i < nargs; ++i)
10086                 {
10087                   if (SCALAR_FLOAT_TYPE_P(TREE_TYPE(args[i]))
10088                       || COMPLEX_FLOAT_TYPE_P(TREE_TYPE(args[i])))
10089                     args[i] = ::convert(excess_type, args[i]);
10090                 }
10091             }
10092         }
10093     }
10094
10095   tree ret = build_call_array(excess_type != NULL_TREE ? excess_type : rettype,
10096                               fn, nargs, args);
10097   delete[] args;
10098
10099   SET_EXPR_LOCATION(ret, location.gcc_location());
10100
10101   if (has_closure)
10102     {
10103       tree closure_tree = func->closure()->get_tree(context);
10104       if (closure_tree != error_mark_node)
10105         CALL_EXPR_STATIC_CHAIN(ret) = closure_tree;
10106     }
10107
10108   // If this is a recursive function type which returns itself, as in
10109   //   type F func() F
10110   // we have used ptr_type_node for the return type.  Add a cast here
10111   // to the correct type.
10112   if (TREE_TYPE(ret) == ptr_type_node)
10113     {
10114       tree t = type_to_tree(this->type()->base()->get_backend(gogo));
10115       ret = fold_convert_loc(location.gcc_location(), t, ret);
10116     }
10117
10118   if (excess_type != NULL_TREE)
10119     {
10120       // Calling convert here can undo our excess precision change.
10121       // That may or may not be a bug in convert_to_real.
10122       ret = build1(NOP_EXPR, rettype, ret);
10123     }
10124
10125   if (this->results_ != NULL)
10126     ret = this->set_results(context, ret);
10127
10128   this->tree_ = ret;
10129
10130   return ret;
10131 }
10132
10133 // Set the result variables if this call returns multiple results.
10134
10135 tree
10136 Call_expression::set_results(Translate_context* context, tree call_tree)
10137 {
10138   tree stmt_list = NULL_TREE;
10139
10140   call_tree = save_expr(call_tree);
10141
10142   if (TREE_CODE(TREE_TYPE(call_tree)) != RECORD_TYPE)
10143     {
10144       go_assert(saw_errors());
10145       return call_tree;
10146     }
10147
10148   Location loc = this->location();
10149   tree field = TYPE_FIELDS(TREE_TYPE(call_tree));
10150   size_t rc = this->result_count();
10151   for (size_t i = 0; i < rc; ++i, field = DECL_CHAIN(field))
10152     {
10153       go_assert(field != NULL_TREE);
10154
10155       Temporary_statement* temp = this->result(i);
10156       Temporary_reference_expression* ref =
10157         Expression::make_temporary_reference(temp, loc);
10158       ref->set_is_lvalue();
10159       tree temp_tree = ref->get_tree(context);
10160       if (temp_tree == error_mark_node)
10161         continue;
10162
10163       tree val_tree = build3_loc(loc.gcc_location(), COMPONENT_REF,
10164                                  TREE_TYPE(field), call_tree, field, NULL_TREE);
10165       tree set_tree = build2_loc(loc.gcc_location(), MODIFY_EXPR,
10166                                  void_type_node, temp_tree, val_tree);
10167
10168       append_to_statement_list(set_tree, &stmt_list);
10169     }
10170   go_assert(field == NULL_TREE);
10171
10172   return save_expr(stmt_list);
10173 }
10174
10175 // Dump ast representation for a call expressin.
10176
10177 void
10178 Call_expression::do_dump_expression(Ast_dump_context* ast_dump_context) const
10179 {
10180   this->fn_->dump_expression(ast_dump_context);
10181   ast_dump_context->ostream() << "(";
10182   if (args_ != NULL)
10183     ast_dump_context->dump_expression_list(this->args_);
10184
10185   ast_dump_context->ostream() << ") ";
10186 }
10187
10188 // Make a call expression.
10189
10190 Call_expression*
10191 Expression::make_call(Expression* fn, Expression_list* args, bool is_varargs,
10192                       Location location)
10193 {
10194   return new Call_expression(fn, args, is_varargs, location);
10195 }
10196
10197 // A single result from a call which returns multiple results.
10198
10199 class Call_result_expression : public Expression
10200 {
10201  public:
10202   Call_result_expression(Call_expression* call, unsigned int index)
10203     : Expression(EXPRESSION_CALL_RESULT, call->location()),
10204       call_(call), index_(index)
10205   { }
10206
10207  protected:
10208   int
10209   do_traverse(Traverse*);
10210
10211   Type*
10212   do_type();
10213
10214   void
10215   do_determine_type(const Type_context*);
10216
10217   void
10218   do_check_types(Gogo*);
10219
10220   Expression*
10221   do_copy()
10222   {
10223     return new Call_result_expression(this->call_->call_expression(),
10224                                       this->index_);
10225   }
10226
10227   bool
10228   do_must_eval_in_order() const
10229   { return true; }
10230
10231   tree
10232   do_get_tree(Translate_context*);
10233
10234   void
10235   do_dump_expression(Ast_dump_context*) const;
10236
10237  private:
10238   // The underlying call expression.
10239   Expression* call_;
10240   // Which result we want.
10241   unsigned int index_;
10242 };
10243
10244 // Traverse a call result.
10245
10246 int
10247 Call_result_expression::do_traverse(Traverse* traverse)
10248 {
10249   if (traverse->remember_expression(this->call_))
10250     {
10251       // We have already traversed the call expression.
10252       return TRAVERSE_CONTINUE;
10253     }
10254   return Expression::traverse(&this->call_, traverse);
10255 }
10256
10257 // Get the type.
10258
10259 Type*
10260 Call_result_expression::do_type()
10261 {
10262   if (this->classification() == EXPRESSION_ERROR)
10263     return Type::make_error_type();
10264
10265   // THIS->CALL_ can be replaced with a temporary reference due to
10266   // Call_expression::do_must_eval_in_order when there is an error.
10267   Call_expression* ce = this->call_->call_expression();
10268   if (ce == NULL)
10269     {
10270       this->set_is_error();
10271       return Type::make_error_type();
10272     }
10273   Function_type* fntype = ce->get_function_type();
10274   if (fntype == NULL)
10275     {
10276       if (ce->issue_error())
10277         {
10278           if (!ce->fn()->type()->is_error())
10279             this->report_error(_("expected function"));
10280         }
10281       this->set_is_error();
10282       return Type::make_error_type();
10283     }
10284   const Typed_identifier_list* results = fntype->results();
10285   if (results == NULL || results->size() < 2)
10286     {
10287       if (ce->issue_error())
10288         this->report_error(_("number of results does not match "
10289                              "number of values"));
10290       return Type::make_error_type();
10291     }
10292   Typed_identifier_list::const_iterator pr = results->begin();
10293   for (unsigned int i = 0; i < this->index_; ++i)
10294     {
10295       if (pr == results->end())
10296         break;
10297       ++pr;
10298     }
10299   if (pr == results->end())
10300     {
10301       if (ce->issue_error())
10302         this->report_error(_("number of results does not match "
10303                              "number of values"));
10304       return Type::make_error_type();
10305     }
10306   return pr->type();
10307 }
10308
10309 // Check the type.  Just make sure that we trigger the warning in
10310 // do_type.
10311
10312 void
10313 Call_result_expression::do_check_types(Gogo*)
10314 {
10315   this->type();
10316 }
10317
10318 // Determine the type.  We have nothing to do here, but the 0 result
10319 // needs to pass down to the caller.
10320
10321 void
10322 Call_result_expression::do_determine_type(const Type_context*)
10323 {
10324   this->call_->determine_type_no_context();
10325 }
10326
10327 // Return the tree.  We just refer to the temporary set by the call
10328 // expression.  We don't do this at lowering time because it makes it
10329 // hard to evaluate the call at the right time.
10330
10331 tree
10332 Call_result_expression::do_get_tree(Translate_context* context)
10333 {
10334   Call_expression* ce = this->call_->call_expression();
10335   go_assert(ce != NULL);
10336   Temporary_statement* ts = ce->result(this->index_);
10337   Expression* ref = Expression::make_temporary_reference(ts, this->location());
10338   return ref->get_tree(context);
10339 }
10340
10341 // Dump ast representation for a call result expression.
10342
10343 void
10344 Call_result_expression::do_dump_expression(Ast_dump_context* ast_dump_context)
10345     const
10346 {
10347   // FIXME: Wouldn't it be better if the call is assigned to a temporary
10348   // (struct) and the fields are referenced instead.
10349   ast_dump_context->ostream() << this->index_ << "@(";
10350   ast_dump_context->dump_expression(this->call_);
10351   ast_dump_context->ostream() << ")";
10352 }
10353
10354 // Make a reference to a single result of a call which returns
10355 // multiple results.
10356
10357 Expression*
10358 Expression::make_call_result(Call_expression* call, unsigned int index)
10359 {
10360   return new Call_result_expression(call, index);
10361 }
10362
10363 // Class Index_expression.
10364
10365 // Traversal.
10366
10367 int
10368 Index_expression::do_traverse(Traverse* traverse)
10369 {
10370   if (Expression::traverse(&this->left_, traverse) == TRAVERSE_EXIT
10371       || Expression::traverse(&this->start_, traverse) == TRAVERSE_EXIT
10372       || (this->end_ != NULL
10373           && Expression::traverse(&this->end_, traverse) == TRAVERSE_EXIT))
10374     return TRAVERSE_EXIT;
10375   return TRAVERSE_CONTINUE;
10376 }
10377
10378 // Lower an index expression.  This converts the generic index
10379 // expression into an array index, a string index, or a map index.
10380
10381 Expression*
10382 Index_expression::do_lower(Gogo*, Named_object*, Statement_inserter*, int)
10383 {
10384   Location location = this->location();
10385   Expression* left = this->left_;
10386   Expression* start = this->start_;
10387   Expression* end = this->end_;
10388
10389   Type* type = left->type();
10390   if (type->is_error())
10391     return Expression::make_error(location);
10392   else if (left->is_type_expression())
10393     {
10394       error_at(location, "attempt to index type expression");
10395       return Expression::make_error(location);
10396     }
10397   else if (type->array_type() != NULL)
10398     return Expression::make_array_index(left, start, end, location);
10399   else if (type->points_to() != NULL
10400            && type->points_to()->array_type() != NULL
10401            && !type->points_to()->is_slice_type())
10402     {
10403       Expression* deref = Expression::make_unary(OPERATOR_MULT, left,
10404                                                  location);
10405       return Expression::make_array_index(deref, start, end, location);
10406     }
10407   else if (type->is_string_type())
10408     return Expression::make_string_index(left, start, end, location);
10409   else if (type->map_type() != NULL)
10410     {
10411       if (end != NULL)
10412         {
10413           error_at(location, "invalid slice of map");
10414           return Expression::make_error(location);
10415         }
10416       Map_index_expression* ret = Expression::make_map_index(left, start,
10417                                                              location);
10418       if (this->is_lvalue_)
10419         ret->set_is_lvalue();
10420       return ret;
10421     }
10422   else
10423     {
10424       error_at(location,
10425                "attempt to index object which is not array, string, or map");
10426       return Expression::make_error(location);
10427     }
10428 }
10429
10430 // Write an indexed expression (expr[expr:expr] or expr[expr]) to a
10431 // dump context
10432
10433 void
10434 Index_expression::dump_index_expression(Ast_dump_context* ast_dump_context,
10435                                         const Expression* expr,
10436                                         const Expression* start,
10437                                         const Expression* end)
10438 {
10439   expr->dump_expression(ast_dump_context);
10440   ast_dump_context->ostream() << "[";
10441   start->dump_expression(ast_dump_context);
10442   if (end != NULL)
10443     {
10444       ast_dump_context->ostream() << ":";
10445       end->dump_expression(ast_dump_context);
10446     }
10447   ast_dump_context->ostream() << "]";
10448 }
10449
10450 // Dump ast representation for an index expression.
10451
10452 void
10453 Index_expression::do_dump_expression(Ast_dump_context* ast_dump_context)
10454     const
10455 {
10456   Index_expression::dump_index_expression(ast_dump_context, this->left_,
10457                                           this->start_, this->end_);
10458 }
10459
10460 // Make an index expression.
10461
10462 Expression*
10463 Expression::make_index(Expression* left, Expression* start, Expression* end,
10464                        Location location)
10465 {
10466   return new Index_expression(left, start, end, location);
10467 }
10468
10469 // An array index.  This is used for both indexing and slicing.
10470
10471 class Array_index_expression : public Expression
10472 {
10473  public:
10474   Array_index_expression(Expression* array, Expression* start,
10475                          Expression* end, Location location)
10476     : Expression(EXPRESSION_ARRAY_INDEX, location),
10477       array_(array), start_(start), end_(end), type_(NULL)
10478   { }
10479
10480  protected:
10481   int
10482   do_traverse(Traverse*);
10483
10484   Type*
10485   do_type();
10486
10487   void
10488   do_determine_type(const Type_context*);
10489
10490   void
10491   do_check_types(Gogo*);
10492
10493   Expression*
10494   do_copy()
10495   {
10496     return Expression::make_array_index(this->array_->copy(),
10497                                         this->start_->copy(),
10498                                         (this->end_ == NULL
10499                                          ? NULL
10500                                          : this->end_->copy()),
10501                                         this->location());
10502   }
10503
10504   bool
10505   do_must_eval_subexpressions_in_order(int* skip) const
10506   {
10507     *skip = 1;
10508     return true;
10509   }
10510
10511   bool
10512   do_is_addressable() const;
10513
10514   void
10515   do_address_taken(bool escapes)
10516   { this->array_->address_taken(escapes); }
10517
10518   tree
10519   do_get_tree(Translate_context*);
10520
10521   void
10522   do_dump_expression(Ast_dump_context*) const;
10523
10524  private:
10525   // The array we are getting a value from.
10526   Expression* array_;
10527   // The start or only index.
10528   Expression* start_;
10529   // The end index of a slice.  This may be NULL for a simple array
10530   // index, or it may be a nil expression for the length of the array.
10531   Expression* end_;
10532   // The type of the expression.
10533   Type* type_;
10534 };
10535
10536 // Array index traversal.
10537
10538 int
10539 Array_index_expression::do_traverse(Traverse* traverse)
10540 {
10541   if (Expression::traverse(&this->array_, traverse) == TRAVERSE_EXIT)
10542     return TRAVERSE_EXIT;
10543   if (Expression::traverse(&this->start_, traverse) == TRAVERSE_EXIT)
10544     return TRAVERSE_EXIT;
10545   if (this->end_ != NULL)
10546     {
10547       if (Expression::traverse(&this->end_, traverse) == TRAVERSE_EXIT)
10548         return TRAVERSE_EXIT;
10549     }
10550   return TRAVERSE_CONTINUE;
10551 }
10552
10553 // Return the type of an array index.
10554
10555 Type*
10556 Array_index_expression::do_type()
10557 {
10558   if (this->type_ == NULL)
10559     {
10560      Array_type* type = this->array_->type()->array_type();
10561       if (type == NULL)
10562         this->type_ = Type::make_error_type();
10563       else if (this->end_ == NULL)
10564         this->type_ = type->element_type();
10565       else if (type->is_slice_type())
10566         {
10567           // A slice of a slice has the same type as the original
10568           // slice.
10569           this->type_ = this->array_->type()->deref();
10570         }
10571       else
10572         {
10573           // A slice of an array is a slice.
10574           this->type_ = Type::make_array_type(type->element_type(), NULL);
10575         }
10576     }
10577   return this->type_;
10578 }
10579
10580 // Set the type of an array index.
10581
10582 void
10583 Array_index_expression::do_determine_type(const Type_context*)
10584 {
10585   this->array_->determine_type_no_context();
10586   this->start_->determine_type_no_context();
10587   if (this->end_ != NULL)
10588     this->end_->determine_type_no_context();
10589 }
10590
10591 // Check types of an array index.
10592
10593 void
10594 Array_index_expression::do_check_types(Gogo*)
10595 {
10596   if (this->start_->type()->integer_type() == NULL)
10597     this->report_error(_("index must be integer"));
10598   if (this->end_ != NULL
10599       && this->end_->type()->integer_type() == NULL
10600       && !this->end_->type()->is_error()
10601       && !this->end_->is_nil_expression()
10602       && !this->end_->is_error_expression())
10603     this->report_error(_("slice end must be integer"));
10604
10605   Array_type* array_type = this->array_->type()->array_type();
10606   if (array_type == NULL)
10607     {
10608       go_assert(this->array_->type()->is_error());
10609       return;
10610     }
10611
10612   unsigned int int_bits =
10613     Type::lookup_integer_type("int")->integer_type()->bits();
10614
10615   Type* dummy;
10616   mpz_t lval;
10617   mpz_init(lval);
10618   bool lval_valid = (array_type->length() != NULL
10619                      && array_type->length()->integer_constant_value(true,
10620                                                                      lval,
10621                                                                      &dummy));
10622   mpz_t ival;
10623   mpz_init(ival);
10624   if (this->start_->integer_constant_value(true, ival, &dummy))
10625     {
10626       if (mpz_sgn(ival) < 0
10627           || mpz_sizeinbase(ival, 2) >= int_bits
10628           || (lval_valid
10629               && (this->end_ == NULL
10630                   ? mpz_cmp(ival, lval) >= 0
10631                   : mpz_cmp(ival, lval) > 0)))
10632         {
10633           error_at(this->start_->location(), "array index out of bounds");
10634           this->set_is_error();
10635         }
10636     }
10637   if (this->end_ != NULL && !this->end_->is_nil_expression())
10638     {
10639       if (this->end_->integer_constant_value(true, ival, &dummy))
10640         {
10641           if (mpz_sgn(ival) < 0
10642               || mpz_sizeinbase(ival, 2) >= int_bits
10643               || (lval_valid && mpz_cmp(ival, lval) > 0))
10644             {
10645               error_at(this->end_->location(), "array index out of bounds");
10646               this->set_is_error();
10647             }
10648         }
10649     }
10650   mpz_clear(ival);
10651   mpz_clear(lval);
10652
10653   // A slice of an array requires an addressable array.  A slice of a
10654   // slice is always possible.
10655   if (this->end_ != NULL && !array_type->is_slice_type())
10656     {
10657       if (!this->array_->is_addressable())
10658         this->report_error(_("slice of unaddressable value"));
10659       else
10660         this->array_->address_taken(true);
10661     }
10662 }
10663
10664 // Return whether this expression is addressable.
10665
10666 bool
10667 Array_index_expression::do_is_addressable() const
10668 {
10669   // A slice expression is not addressable.
10670   if (this->end_ != NULL)
10671     return false;
10672
10673   // An index into a slice is addressable.
10674   if (this->array_->type()->is_slice_type())
10675     return true;
10676
10677   // An index into an array is addressable if the array is
10678   // addressable.
10679   return this->array_->is_addressable();
10680 }
10681
10682 // Get a tree for an array index.
10683
10684 tree
10685 Array_index_expression::do_get_tree(Translate_context* context)
10686 {
10687   Gogo* gogo = context->gogo();
10688   Location loc = this->location();
10689
10690   Array_type* array_type = this->array_->type()->array_type();
10691   if (array_type == NULL)
10692     {
10693       go_assert(this->array_->type()->is_error());
10694       return error_mark_node;
10695     }
10696
10697   tree type_tree = type_to_tree(array_type->get_backend(gogo));
10698   if (type_tree == error_mark_node)
10699     return error_mark_node;
10700
10701   tree array_tree = this->array_->get_tree(context);
10702   if (array_tree == error_mark_node)
10703     return error_mark_node;
10704
10705   if (array_type->length() == NULL && !DECL_P(array_tree))
10706     array_tree = save_expr(array_tree);
10707
10708   tree length_tree = NULL_TREE;
10709   if (this->end_ == NULL || this->end_->is_nil_expression())
10710     {
10711       length_tree = array_type->length_tree(gogo, array_tree);
10712       if (length_tree == error_mark_node)
10713         return error_mark_node;
10714       length_tree = save_expr(length_tree);
10715     }
10716
10717   tree capacity_tree = NULL_TREE;
10718   if (this->end_ != NULL)
10719     {
10720       capacity_tree = array_type->capacity_tree(gogo, array_tree);
10721       if (capacity_tree == error_mark_node)
10722         return error_mark_node;
10723       capacity_tree = save_expr(capacity_tree);
10724     }
10725
10726   tree length_type = (length_tree != NULL_TREE
10727                       ? TREE_TYPE(length_tree)
10728                       : TREE_TYPE(capacity_tree));
10729
10730   tree bad_index = boolean_false_node;
10731
10732   tree start_tree = this->start_->get_tree(context);
10733   if (start_tree == error_mark_node)
10734     return error_mark_node;
10735   if (!DECL_P(start_tree))
10736     start_tree = save_expr(start_tree);
10737   if (!INTEGRAL_TYPE_P(TREE_TYPE(start_tree)))
10738     start_tree = convert_to_integer(length_type, start_tree);
10739
10740   bad_index = Expression::check_bounds(start_tree, length_type, bad_index,
10741                                        loc);
10742
10743   start_tree = fold_convert_loc(loc.gcc_location(), length_type, start_tree);
10744   bad_index = fold_build2_loc(loc.gcc_location(), TRUTH_OR_EXPR,
10745                               boolean_type_node, bad_index,
10746                               fold_build2_loc(loc.gcc_location(),
10747                                               (this->end_ == NULL
10748                                                ? GE_EXPR
10749                                                : GT_EXPR),
10750                                               boolean_type_node, start_tree,
10751                                               (this->end_ == NULL
10752                                                ? length_tree
10753                                                : capacity_tree)));
10754
10755   int code = (array_type->length() != NULL
10756               ? (this->end_ == NULL
10757                  ? RUNTIME_ERROR_ARRAY_INDEX_OUT_OF_BOUNDS
10758                  : RUNTIME_ERROR_ARRAY_SLICE_OUT_OF_BOUNDS)
10759               : (this->end_ == NULL
10760                  ? RUNTIME_ERROR_SLICE_INDEX_OUT_OF_BOUNDS
10761                  : RUNTIME_ERROR_SLICE_SLICE_OUT_OF_BOUNDS));
10762   tree crash = Gogo::runtime_error(code, loc);
10763
10764   if (this->end_ == NULL)
10765     {
10766       // Simple array indexing.  This has to return an l-value, so
10767       // wrap the index check into START_TREE.
10768       start_tree = build2(COMPOUND_EXPR, TREE_TYPE(start_tree),
10769                           build3(COND_EXPR, void_type_node,
10770                                  bad_index, crash, NULL_TREE),
10771                           start_tree);
10772       start_tree = fold_convert_loc(loc.gcc_location(), sizetype, start_tree);
10773
10774       if (array_type->length() != NULL)
10775         {
10776           // Fixed array.
10777           return build4(ARRAY_REF, TREE_TYPE(type_tree), array_tree,
10778                         start_tree, NULL_TREE, NULL_TREE);
10779         }
10780       else
10781         {
10782           // Open array.
10783           tree values = array_type->value_pointer_tree(gogo, array_tree);
10784           Type* element_type = array_type->element_type();
10785           Btype* belement_type = element_type->get_backend(gogo);
10786           tree element_type_tree = type_to_tree(belement_type);
10787           if (element_type_tree == error_mark_node)
10788             return error_mark_node;
10789           tree element_size = TYPE_SIZE_UNIT(element_type_tree);
10790           tree offset = fold_build2_loc(loc.gcc_location(), MULT_EXPR, sizetype,
10791                                         start_tree, element_size);
10792           tree ptr = fold_build2_loc(loc.gcc_location(), POINTER_PLUS_EXPR,
10793                                      TREE_TYPE(values), values, offset);
10794           return build_fold_indirect_ref(ptr);
10795         }
10796     }
10797
10798   // Array slice.
10799
10800   tree end_tree;
10801   if (this->end_->is_nil_expression())
10802     end_tree = length_tree;
10803   else
10804     {
10805       end_tree = this->end_->get_tree(context);
10806       if (end_tree == error_mark_node)
10807         return error_mark_node;
10808       if (!DECL_P(end_tree))
10809         end_tree = save_expr(end_tree);
10810       if (!INTEGRAL_TYPE_P(TREE_TYPE(end_tree)))
10811         end_tree = convert_to_integer(length_type, end_tree);
10812
10813       bad_index = Expression::check_bounds(end_tree, length_type, bad_index,
10814                                            loc);
10815
10816       end_tree = fold_convert_loc(loc.gcc_location(), length_type, end_tree);
10817
10818       tree bad_end = fold_build2_loc(loc.gcc_location(), TRUTH_OR_EXPR,
10819                                      boolean_type_node,
10820                                      fold_build2_loc(loc.gcc_location(),
10821                                                      LT_EXPR, boolean_type_node,
10822                                                      end_tree, start_tree),
10823                                      fold_build2_loc(loc.gcc_location(),
10824                                                      GT_EXPR, boolean_type_node,
10825                                                      end_tree, capacity_tree));
10826       bad_index = fold_build2_loc(loc.gcc_location(), TRUTH_OR_EXPR,
10827                                   boolean_type_node, bad_index, bad_end);
10828     }
10829
10830   Type* element_type = array_type->element_type();
10831   tree element_type_tree = type_to_tree(element_type->get_backend(gogo));
10832   if (element_type_tree == error_mark_node)
10833     return error_mark_node;
10834   tree element_size = TYPE_SIZE_UNIT(element_type_tree);
10835
10836   tree offset = fold_build2_loc(loc.gcc_location(), MULT_EXPR, sizetype,
10837                                 fold_convert_loc(loc.gcc_location(), sizetype,
10838                                                  start_tree),
10839                                 element_size);
10840
10841   tree value_pointer = array_type->value_pointer_tree(gogo, array_tree);
10842   if (value_pointer == error_mark_node)
10843     return error_mark_node;
10844
10845   value_pointer = fold_build2_loc(loc.gcc_location(), POINTER_PLUS_EXPR,
10846                                   TREE_TYPE(value_pointer),
10847                                   value_pointer, offset);
10848
10849   tree result_length_tree = fold_build2_loc(loc.gcc_location(), MINUS_EXPR,
10850                                             length_type, end_tree, start_tree);
10851
10852   tree result_capacity_tree = fold_build2_loc(loc.gcc_location(), MINUS_EXPR,
10853                                               length_type, capacity_tree,
10854                                               start_tree);
10855
10856   tree struct_tree = type_to_tree(this->type()->get_backend(gogo));
10857   go_assert(TREE_CODE(struct_tree) == RECORD_TYPE);
10858
10859   VEC(constructor_elt,gc)* init = VEC_alloc(constructor_elt, gc, 3);
10860
10861   constructor_elt* elt = VEC_quick_push(constructor_elt, init, NULL);
10862   tree field = TYPE_FIELDS(struct_tree);
10863   go_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__values") == 0);
10864   elt->index = field;
10865   elt->value = value_pointer;
10866
10867   elt = VEC_quick_push(constructor_elt, init, NULL);
10868   field = DECL_CHAIN(field);
10869   go_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__count") == 0);
10870   elt->index = field;
10871   elt->value = fold_convert_loc(loc.gcc_location(), TREE_TYPE(field),
10872                                 result_length_tree);
10873
10874   elt = VEC_quick_push(constructor_elt, init, NULL);
10875   field = DECL_CHAIN(field);
10876   go_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__capacity") == 0);
10877   elt->index = field;
10878   elt->value = fold_convert_loc(loc.gcc_location(), TREE_TYPE(field),
10879                                 result_capacity_tree);
10880
10881   tree constructor = build_constructor(struct_tree, init);
10882
10883   if (TREE_CONSTANT(value_pointer)
10884       && TREE_CONSTANT(result_length_tree)
10885       && TREE_CONSTANT(result_capacity_tree))
10886     TREE_CONSTANT(constructor) = 1;
10887
10888   return fold_build2_loc(loc.gcc_location(), COMPOUND_EXPR,
10889                          TREE_TYPE(constructor),
10890                          build3(COND_EXPR, void_type_node,
10891                                 bad_index, crash, NULL_TREE),
10892                          constructor);
10893 }
10894
10895 // Dump ast representation for an array index expression.
10896
10897 void
10898 Array_index_expression::do_dump_expression(Ast_dump_context* ast_dump_context)
10899     const
10900 {
10901   Index_expression::dump_index_expression(ast_dump_context, this->array_,
10902                                           this->start_, this->end_);
10903 }
10904
10905 // Make an array index expression.  END may be NULL.
10906
10907 Expression*
10908 Expression::make_array_index(Expression* array, Expression* start,
10909                              Expression* end, Location location)
10910 {
10911   return new Array_index_expression(array, start, end, location);
10912 }
10913
10914 // A string index.  This is used for both indexing and slicing.
10915
10916 class String_index_expression : public Expression
10917 {
10918  public:
10919   String_index_expression(Expression* string, Expression* start,
10920                           Expression* end, Location location)
10921     : Expression(EXPRESSION_STRING_INDEX, location),
10922       string_(string), start_(start), end_(end)
10923   { }
10924
10925  protected:
10926   int
10927   do_traverse(Traverse*);
10928
10929   Type*
10930   do_type();
10931
10932   void
10933   do_determine_type(const Type_context*);
10934
10935   void
10936   do_check_types(Gogo*);
10937
10938   Expression*
10939   do_copy()
10940   {
10941     return Expression::make_string_index(this->string_->copy(),
10942                                          this->start_->copy(),
10943                                          (this->end_ == NULL
10944                                           ? NULL
10945                                           : this->end_->copy()),
10946                                          this->location());
10947   }
10948
10949   bool
10950   do_must_eval_subexpressions_in_order(int* skip) const
10951   {
10952     *skip = 1;
10953     return true;
10954   }
10955
10956   tree
10957   do_get_tree(Translate_context*);
10958
10959   void
10960   do_dump_expression(Ast_dump_context*) const;
10961
10962  private:
10963   // The string we are getting a value from.
10964   Expression* string_;
10965   // The start or only index.
10966   Expression* start_;
10967   // The end index of a slice.  This may be NULL for a single index,
10968   // or it may be a nil expression for the length of the string.
10969   Expression* end_;
10970 };
10971
10972 // String index traversal.
10973
10974 int
10975 String_index_expression::do_traverse(Traverse* traverse)
10976 {
10977   if (Expression::traverse(&this->string_, traverse) == TRAVERSE_EXIT)
10978     return TRAVERSE_EXIT;
10979   if (Expression::traverse(&this->start_, traverse) == TRAVERSE_EXIT)
10980     return TRAVERSE_EXIT;
10981   if (this->end_ != NULL)
10982     {
10983       if (Expression::traverse(&this->end_, traverse) == TRAVERSE_EXIT)
10984         return TRAVERSE_EXIT;
10985     }
10986   return TRAVERSE_CONTINUE;
10987 }
10988
10989 // Return the type of a string index.
10990
10991 Type*
10992 String_index_expression::do_type()
10993 {
10994   if (this->end_ == NULL)
10995     return Type::lookup_integer_type("uint8");
10996   else
10997     return this->string_->type();
10998 }
10999
11000 // Determine the type of a string index.
11001
11002 void
11003 String_index_expression::do_determine_type(const Type_context*)
11004 {
11005   this->string_->determine_type_no_context();
11006   this->start_->determine_type_no_context();
11007   if (this->end_ != NULL)
11008     this->end_->determine_type_no_context();
11009 }
11010
11011 // Check types of a string index.
11012
11013 void
11014 String_index_expression::do_check_types(Gogo*)
11015 {
11016   if (this->start_->type()->integer_type() == NULL)
11017     this->report_error(_("index must be integer"));
11018   if (this->end_ != NULL
11019       && this->end_->type()->integer_type() == NULL
11020       && !this->end_->is_nil_expression())
11021     this->report_error(_("slice end must be integer"));
11022
11023   std::string sval;
11024   bool sval_valid = this->string_->string_constant_value(&sval);
11025
11026   mpz_t ival;
11027   mpz_init(ival);
11028   Type* dummy;
11029   if (this->start_->integer_constant_value(true, ival, &dummy))
11030     {
11031       if (mpz_sgn(ival) < 0
11032           || (sval_valid && mpz_cmp_ui(ival, sval.length()) >= 0))
11033         {
11034           error_at(this->start_->location(), "string index out of bounds");
11035           this->set_is_error();
11036         }
11037     }
11038   if (this->end_ != NULL && !this->end_->is_nil_expression())
11039     {
11040       if (this->end_->integer_constant_value(true, ival, &dummy))
11041         {
11042           if (mpz_sgn(ival) < 0
11043               || (sval_valid && mpz_cmp_ui(ival, sval.length()) > 0))
11044             {
11045               error_at(this->end_->location(), "string index out of bounds");
11046               this->set_is_error();
11047             }
11048         }
11049     }
11050   mpz_clear(ival);
11051 }
11052
11053 // Get a tree for a string index.
11054
11055 tree
11056 String_index_expression::do_get_tree(Translate_context* context)
11057 {
11058   Location loc = this->location();
11059
11060   tree string_tree = this->string_->get_tree(context);
11061   if (string_tree == error_mark_node)
11062     return error_mark_node;
11063
11064   if (this->string_->type()->points_to() != NULL)
11065     string_tree = build_fold_indirect_ref(string_tree);
11066   if (!DECL_P(string_tree))
11067     string_tree = save_expr(string_tree);
11068   tree string_type = TREE_TYPE(string_tree);
11069
11070   tree length_tree = String_type::length_tree(context->gogo(), string_tree);
11071   length_tree = save_expr(length_tree);
11072   tree length_type = TREE_TYPE(length_tree);
11073
11074   tree bad_index = boolean_false_node;
11075
11076   tree start_tree = this->start_->get_tree(context);
11077   if (start_tree == error_mark_node)
11078     return error_mark_node;
11079   if (!DECL_P(start_tree))
11080     start_tree = save_expr(start_tree);
11081   if (!INTEGRAL_TYPE_P(TREE_TYPE(start_tree)))
11082     start_tree = convert_to_integer(length_type, start_tree);
11083
11084   bad_index = Expression::check_bounds(start_tree, length_type, bad_index,
11085                                        loc);
11086
11087   start_tree = fold_convert_loc(loc.gcc_location(), length_type, start_tree);
11088
11089   int code = (this->end_ == NULL
11090               ? RUNTIME_ERROR_STRING_INDEX_OUT_OF_BOUNDS
11091               : RUNTIME_ERROR_STRING_SLICE_OUT_OF_BOUNDS);
11092   tree crash = Gogo::runtime_error(code, loc);
11093
11094   if (this->end_ == NULL)
11095     {
11096       bad_index = fold_build2_loc(loc.gcc_location(), TRUTH_OR_EXPR,
11097                                   boolean_type_node, bad_index,
11098                                   fold_build2_loc(loc.gcc_location(), GE_EXPR,
11099                                                   boolean_type_node,
11100                                                   start_tree, length_tree));
11101
11102       tree bytes_tree = String_type::bytes_tree(context->gogo(), string_tree);
11103       tree ptr = fold_build2_loc(loc.gcc_location(), POINTER_PLUS_EXPR,
11104                                  TREE_TYPE(bytes_tree),
11105                                  bytes_tree,
11106                                  fold_convert_loc(loc.gcc_location(), sizetype,
11107                                                   start_tree));
11108       tree index = build_fold_indirect_ref_loc(loc.gcc_location(), ptr);
11109
11110       return build2(COMPOUND_EXPR, TREE_TYPE(index),
11111                     build3(COND_EXPR, void_type_node,
11112                            bad_index, crash, NULL_TREE),
11113                     index);
11114     }
11115   else
11116     {
11117       tree end_tree;
11118       if (this->end_->is_nil_expression())
11119         end_tree = build_int_cst(length_type, -1);
11120       else
11121         {
11122           end_tree = this->end_->get_tree(context);
11123           if (end_tree == error_mark_node)
11124             return error_mark_node;
11125           if (!DECL_P(end_tree))
11126             end_tree = save_expr(end_tree);
11127           if (!INTEGRAL_TYPE_P(TREE_TYPE(end_tree)))
11128             end_tree = convert_to_integer(length_type, end_tree);
11129
11130           bad_index = Expression::check_bounds(end_tree, length_type,
11131                                                bad_index, loc);
11132
11133           end_tree = fold_convert_loc(loc.gcc_location(), length_type,
11134                                       end_tree);
11135         }
11136
11137       static tree strslice_fndecl;
11138       tree ret = Gogo::call_builtin(&strslice_fndecl,
11139                                     loc,
11140                                     "__go_string_slice",
11141                                     3,
11142                                     string_type,
11143                                     string_type,
11144                                     string_tree,
11145                                     length_type,
11146                                     start_tree,
11147                                     length_type,
11148                                     end_tree);
11149       if (ret == error_mark_node)
11150         return error_mark_node;
11151       // This will panic if the bounds are out of range for the
11152       // string.
11153       TREE_NOTHROW(strslice_fndecl) = 0;
11154
11155       if (bad_index == boolean_false_node)
11156         return ret;
11157       else
11158         return build2(COMPOUND_EXPR, TREE_TYPE(ret),
11159                       build3(COND_EXPR, void_type_node,
11160                              bad_index, crash, NULL_TREE),
11161                       ret);
11162     }
11163 }
11164
11165 // Dump ast representation for a string index expression.
11166
11167 void
11168 String_index_expression::do_dump_expression(Ast_dump_context* ast_dump_context)
11169     const
11170 {
11171   Index_expression::dump_index_expression(ast_dump_context, this->string_,
11172                                           this->start_, this->end_);
11173 }
11174
11175 // Make a string index expression.  END may be NULL.
11176
11177 Expression*
11178 Expression::make_string_index(Expression* string, Expression* start,
11179                               Expression* end, Location location)
11180 {
11181   return new String_index_expression(string, start, end, location);
11182 }
11183
11184 // Class Map_index.
11185
11186 // Get the type of the map.
11187
11188 Map_type*
11189 Map_index_expression::get_map_type() const
11190 {
11191   Map_type* mt = this->map_->type()->deref()->map_type();
11192   if (mt == NULL)
11193     go_assert(saw_errors());
11194   return mt;
11195 }
11196
11197 // Map index traversal.
11198
11199 int
11200 Map_index_expression::do_traverse(Traverse* traverse)
11201 {
11202   if (Expression::traverse(&this->map_, traverse) == TRAVERSE_EXIT)
11203     return TRAVERSE_EXIT;
11204   return Expression::traverse(&this->index_, traverse);
11205 }
11206
11207 // Return the type of a map index.
11208
11209 Type*
11210 Map_index_expression::do_type()
11211 {
11212   Map_type* mt = this->get_map_type();
11213   if (mt == NULL)
11214     return Type::make_error_type();
11215   Type* type = mt->val_type();
11216   // If this map index is in a tuple assignment, we actually return a
11217   // pointer to the value type.  Tuple_map_assignment_statement is
11218   // responsible for handling this correctly.  We need to get the type
11219   // right in case this gets assigned to a temporary variable.
11220   if (this->is_in_tuple_assignment_)
11221     type = Type::make_pointer_type(type);
11222   return type;
11223 }
11224
11225 // Fix the type of a map index.
11226
11227 void
11228 Map_index_expression::do_determine_type(const Type_context*)
11229 {
11230   this->map_->determine_type_no_context();
11231   Map_type* mt = this->get_map_type();
11232   Type* key_type = mt == NULL ? NULL : mt->key_type();
11233   Type_context subcontext(key_type, false);
11234   this->index_->determine_type(&subcontext);
11235 }
11236
11237 // Check types of a map index.
11238
11239 void
11240 Map_index_expression::do_check_types(Gogo*)
11241 {
11242   std::string reason;
11243   Map_type* mt = this->get_map_type();
11244   if (mt == NULL)
11245     return;
11246   if (!Type::are_assignable(mt->key_type(), this->index_->type(), &reason))
11247     {
11248       if (reason.empty())
11249         this->report_error(_("incompatible type for map index"));
11250       else
11251         {
11252           error_at(this->location(), "incompatible type for map index (%s)",
11253                    reason.c_str());
11254           this->set_is_error();
11255         }
11256     }
11257 }
11258
11259 // Get a tree for a map index.
11260
11261 tree
11262 Map_index_expression::do_get_tree(Translate_context* context)
11263 {
11264   Map_type* type = this->get_map_type();
11265   if (type == NULL)
11266     return error_mark_node;
11267
11268   tree valptr = this->get_value_pointer(context, this->is_lvalue_);
11269   if (valptr == error_mark_node)
11270     return error_mark_node;
11271   valptr = save_expr(valptr);
11272
11273   tree val_type_tree = TREE_TYPE(TREE_TYPE(valptr));
11274
11275   if (this->is_lvalue_)
11276     return build_fold_indirect_ref(valptr);
11277   else if (this->is_in_tuple_assignment_)
11278     {
11279       // Tuple_map_assignment_statement is responsible for using this
11280       // appropriately.
11281       return valptr;
11282     }
11283   else
11284     {
11285       Gogo* gogo = context->gogo();
11286       Btype* val_btype = type->val_type()->get_backend(gogo);
11287       Bexpression* val_zero = gogo->backend()->zero_expression(val_btype);
11288       return fold_build3(COND_EXPR, val_type_tree,
11289                          fold_build2(EQ_EXPR, boolean_type_node, valptr,
11290                                      fold_convert(TREE_TYPE(valptr),
11291                                                   null_pointer_node)),
11292                          expr_to_tree(val_zero),
11293                          build_fold_indirect_ref(valptr));
11294     }
11295 }
11296
11297 // Get a tree for the map index.  This returns a tree which evaluates
11298 // to a pointer to a value.  The pointer will be NULL if the key is
11299 // not in the map.
11300
11301 tree
11302 Map_index_expression::get_value_pointer(Translate_context* context,
11303                                         bool insert)
11304 {
11305   Map_type* type = this->get_map_type();
11306   if (type == NULL)
11307     return error_mark_node;
11308
11309   tree map_tree = this->map_->get_tree(context);
11310   tree index_tree = this->index_->get_tree(context);
11311   index_tree = Expression::convert_for_assignment(context, type->key_type(),
11312                                                   this->index_->type(),
11313                                                   index_tree,
11314                                                   this->location());
11315   if (map_tree == error_mark_node || index_tree == error_mark_node)
11316     return error_mark_node;
11317
11318   if (this->map_->type()->points_to() != NULL)
11319     map_tree = build_fold_indirect_ref(map_tree);
11320
11321   // We need to pass in a pointer to the key, so stuff it into a
11322   // variable.
11323   tree tmp;
11324   tree make_tmp;
11325   if (current_function_decl != NULL)
11326     {
11327       tmp = create_tmp_var(TREE_TYPE(index_tree), get_name(index_tree));
11328       DECL_IGNORED_P(tmp) = 0;
11329       DECL_INITIAL(tmp) = index_tree;
11330       make_tmp = build1(DECL_EXPR, void_type_node, tmp);
11331       TREE_ADDRESSABLE(tmp) = 1;
11332     }
11333   else
11334     {
11335       tmp = build_decl(this->location().gcc_location(), VAR_DECL,
11336                        create_tmp_var_name("M"),
11337                        TREE_TYPE(index_tree));
11338       DECL_EXTERNAL(tmp) = 0;
11339       TREE_PUBLIC(tmp) = 0;
11340       TREE_STATIC(tmp) = 1;
11341       DECL_ARTIFICIAL(tmp) = 1;
11342       if (!TREE_CONSTANT(index_tree))
11343         make_tmp = fold_build2_loc(this->location().gcc_location(),
11344                                    INIT_EXPR, void_type_node,
11345                                    tmp, index_tree);
11346       else
11347         {
11348           TREE_READONLY(tmp) = 1;
11349           TREE_CONSTANT(tmp) = 1;
11350           DECL_INITIAL(tmp) = index_tree;
11351           make_tmp = NULL_TREE;
11352         }
11353       rest_of_decl_compilation(tmp, 1, 0);
11354     }
11355   tree tmpref =
11356     fold_convert_loc(this->location().gcc_location(), const_ptr_type_node,
11357                      build_fold_addr_expr_loc(this->location().gcc_location(),
11358                                               tmp));
11359
11360   static tree map_index_fndecl;
11361   tree call = Gogo::call_builtin(&map_index_fndecl,
11362                                  this->location(),
11363                                  "__go_map_index",
11364                                  3,
11365                                  const_ptr_type_node,
11366                                  TREE_TYPE(map_tree),
11367                                  map_tree,
11368                                  const_ptr_type_node,
11369                                  tmpref,
11370                                  boolean_type_node,
11371                                  (insert
11372                                   ? boolean_true_node
11373                                   : boolean_false_node));
11374   if (call == error_mark_node)
11375     return error_mark_node;
11376   // This can panic on a map of interface type if the interface holds
11377   // an uncomparable or unhashable type.
11378   TREE_NOTHROW(map_index_fndecl) = 0;
11379
11380   Type* val_type = type->val_type();
11381   tree val_type_tree = type_to_tree(val_type->get_backend(context->gogo()));
11382   if (val_type_tree == error_mark_node)
11383     return error_mark_node;
11384   tree ptr_val_type_tree = build_pointer_type(val_type_tree);
11385
11386   tree ret = fold_convert_loc(this->location().gcc_location(),
11387                               ptr_val_type_tree, call);
11388   if (make_tmp != NULL_TREE)
11389     ret = build2(COMPOUND_EXPR, ptr_val_type_tree, make_tmp, ret);
11390   return ret;
11391 }
11392
11393 // Dump ast representation for a map index expression
11394
11395 void
11396 Map_index_expression::do_dump_expression(Ast_dump_context* ast_dump_context)
11397     const
11398 {
11399   Index_expression::dump_index_expression(ast_dump_context,
11400                                           this->map_, this->index_, NULL);
11401 }
11402
11403 // Make a map index expression.
11404
11405 Map_index_expression*
11406 Expression::make_map_index(Expression* map, Expression* index,
11407                            Location location)
11408 {
11409   return new Map_index_expression(map, index, location);
11410 }
11411
11412 // Class Field_reference_expression.
11413
11414 // Return the type of a field reference.
11415
11416 Type*
11417 Field_reference_expression::do_type()
11418 {
11419   Type* type = this->expr_->type();
11420   if (type->is_error())
11421     return type;
11422   Struct_type* struct_type = type->struct_type();
11423   go_assert(struct_type != NULL);
11424   return struct_type->field(this->field_index_)->type();
11425 }
11426
11427 // Check the types for a field reference.
11428
11429 void
11430 Field_reference_expression::do_check_types(Gogo*)
11431 {
11432   Type* type = this->expr_->type();
11433   if (type->is_error())
11434     return;
11435   Struct_type* struct_type = type->struct_type();
11436   go_assert(struct_type != NULL);
11437   go_assert(struct_type->field(this->field_index_) != NULL);
11438 }
11439
11440 // Get a tree for a field reference.
11441
11442 tree
11443 Field_reference_expression::do_get_tree(Translate_context* context)
11444 {
11445   tree struct_tree = this->expr_->get_tree(context);
11446   if (struct_tree == error_mark_node
11447       || TREE_TYPE(struct_tree) == error_mark_node)
11448     return error_mark_node;
11449   go_assert(TREE_CODE(TREE_TYPE(struct_tree)) == RECORD_TYPE);
11450   tree field = TYPE_FIELDS(TREE_TYPE(struct_tree));
11451   if (field == NULL_TREE)
11452     {
11453       // This can happen for a type which refers to itself indirectly
11454       // and then turns out to be erroneous.
11455       go_assert(saw_errors());
11456       return error_mark_node;
11457     }
11458   for (unsigned int i = this->field_index_; i > 0; --i)
11459     {
11460       field = DECL_CHAIN(field);
11461       go_assert(field != NULL_TREE);
11462     }
11463   if (TREE_TYPE(field) == error_mark_node)
11464     return error_mark_node;
11465   return build3(COMPONENT_REF, TREE_TYPE(field), struct_tree, field,
11466                 NULL_TREE);
11467 }
11468
11469 // Dump ast representation for a field reference expression.
11470
11471 void
11472 Field_reference_expression::do_dump_expression(
11473     Ast_dump_context* ast_dump_context) const
11474 {
11475   this->expr_->dump_expression(ast_dump_context);
11476   ast_dump_context->ostream() << "." <<  this->field_index_;
11477 }
11478
11479 // Make a reference to a qualified identifier in an expression.
11480
11481 Field_reference_expression*
11482 Expression::make_field_reference(Expression* expr, unsigned int field_index,
11483                                  Location location)
11484 {
11485   return new Field_reference_expression(expr, field_index, location);
11486 }
11487
11488 // Class Interface_field_reference_expression.
11489
11490 // Return a tree for the pointer to the function to call.
11491
11492 tree
11493 Interface_field_reference_expression::get_function_tree(Translate_context*,
11494                                                         tree expr)
11495 {
11496   if (this->expr_->type()->points_to() != NULL)
11497     expr = build_fold_indirect_ref(expr);
11498
11499   tree expr_type = TREE_TYPE(expr);
11500   go_assert(TREE_CODE(expr_type) == RECORD_TYPE);
11501
11502   tree field = TYPE_FIELDS(expr_type);
11503   go_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__methods") == 0);
11504
11505   tree table = build3(COMPONENT_REF, TREE_TYPE(field), expr, field, NULL_TREE);
11506   go_assert(POINTER_TYPE_P(TREE_TYPE(table)));
11507
11508   table = build_fold_indirect_ref(table);
11509   go_assert(TREE_CODE(TREE_TYPE(table)) == RECORD_TYPE);
11510
11511   std::string name = Gogo::unpack_hidden_name(this->name_);
11512   for (field = DECL_CHAIN(TYPE_FIELDS(TREE_TYPE(table)));
11513        field != NULL_TREE;
11514        field = DECL_CHAIN(field))
11515     {
11516       if (name == IDENTIFIER_POINTER(DECL_NAME(field)))
11517         break;
11518     }
11519   go_assert(field != NULL_TREE);
11520
11521   return build3(COMPONENT_REF, TREE_TYPE(field), table, field, NULL_TREE);
11522 }
11523
11524 // Return a tree for the first argument to pass to the interface
11525 // function.
11526
11527 tree
11528 Interface_field_reference_expression::get_underlying_object_tree(
11529     Translate_context*,
11530     tree expr)
11531 {
11532   if (this->expr_->type()->points_to() != NULL)
11533     expr = build_fold_indirect_ref(expr);
11534
11535   tree expr_type = TREE_TYPE(expr);
11536   go_assert(TREE_CODE(expr_type) == RECORD_TYPE);
11537
11538   tree field = DECL_CHAIN(TYPE_FIELDS(expr_type));
11539   go_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__object") == 0);
11540
11541   return build3(COMPONENT_REF, TREE_TYPE(field), expr, field, NULL_TREE);
11542 }
11543
11544 // Traversal.
11545
11546 int
11547 Interface_field_reference_expression::do_traverse(Traverse* traverse)
11548 {
11549   return Expression::traverse(&this->expr_, traverse);
11550 }
11551
11552 // Return the type of an interface field reference.
11553
11554 Type*
11555 Interface_field_reference_expression::do_type()
11556 {
11557   Type* expr_type = this->expr_->type();
11558
11559   Type* points_to = expr_type->points_to();
11560   if (points_to != NULL)
11561     expr_type = points_to;
11562
11563   Interface_type* interface_type = expr_type->interface_type();
11564   if (interface_type == NULL)
11565     return Type::make_error_type();
11566
11567   const Typed_identifier* method = interface_type->find_method(this->name_);
11568   if (method == NULL)
11569     return Type::make_error_type();
11570
11571   return method->type();
11572 }
11573
11574 // Determine types.
11575
11576 void
11577 Interface_field_reference_expression::do_determine_type(const Type_context*)
11578 {
11579   this->expr_->determine_type_no_context();
11580 }
11581
11582 // Check the types for an interface field reference.
11583
11584 void
11585 Interface_field_reference_expression::do_check_types(Gogo*)
11586 {
11587   Type* type = this->expr_->type();
11588
11589   Type* points_to = type->points_to();
11590   if (points_to != NULL)
11591     type = points_to;
11592
11593   Interface_type* interface_type = type->interface_type();
11594   if (interface_type == NULL)
11595     {
11596       if (!type->is_error_type())
11597         this->report_error(_("expected interface or pointer to interface"));
11598     }
11599   else
11600     {
11601       const Typed_identifier* method =
11602         interface_type->find_method(this->name_);
11603       if (method == NULL)
11604         {
11605           error_at(this->location(), "method %qs not in interface",
11606                    Gogo::message_name(this->name_).c_str());
11607           this->set_is_error();
11608         }
11609     }
11610 }
11611
11612 // Get a tree for a reference to a field in an interface.  There is no
11613 // standard tree type representation for this: it's a function
11614 // attached to its first argument, like a Bound_method_expression.
11615 // The only places it may currently be used are in a Call_expression
11616 // or a Go_statement, which will take it apart directly.  So this has
11617 // nothing to do at present.
11618
11619 tree
11620 Interface_field_reference_expression::do_get_tree(Translate_context*)
11621 {
11622   go_unreachable();
11623 }
11624
11625 // Dump ast representation for an interface field reference.
11626
11627 void
11628 Interface_field_reference_expression::do_dump_expression(
11629     Ast_dump_context* ast_dump_context) const
11630 {
11631   this->expr_->dump_expression(ast_dump_context);
11632   ast_dump_context->ostream() << "." << this->name_;
11633 }
11634
11635 // Make a reference to a field in an interface.
11636
11637 Expression*
11638 Expression::make_interface_field_reference(Expression* expr,
11639                                            const std::string& field,
11640                                            Location location)
11641 {
11642   return new Interface_field_reference_expression(expr, field, location);
11643 }
11644
11645 // A general selector.  This is a Parser_expression for LEFT.NAME.  It
11646 // is lowered after we know the type of the left hand side.
11647
11648 class Selector_expression : public Parser_expression
11649 {
11650  public:
11651   Selector_expression(Expression* left, const std::string& name,
11652                       Location location)
11653     : Parser_expression(EXPRESSION_SELECTOR, location),
11654       left_(left), name_(name)
11655   { }
11656
11657  protected:
11658   int
11659   do_traverse(Traverse* traverse)
11660   { return Expression::traverse(&this->left_, traverse); }
11661
11662   Expression*
11663   do_lower(Gogo*, Named_object*, Statement_inserter*, int);
11664
11665   Expression*
11666   do_copy()
11667   {
11668     return new Selector_expression(this->left_->copy(), this->name_,
11669                                    this->location());
11670   }
11671
11672   void
11673   do_dump_expression(Ast_dump_context* ast_dump_context) const;
11674
11675  private:
11676   Expression*
11677   lower_method_expression(Gogo*);
11678
11679   // The expression on the left hand side.
11680   Expression* left_;
11681   // The name on the right hand side.
11682   std::string name_;
11683 };
11684
11685 // Lower a selector expression once we know the real type of the left
11686 // hand side.
11687
11688 Expression*
11689 Selector_expression::do_lower(Gogo* gogo, Named_object*, Statement_inserter*,
11690                               int)
11691 {
11692   Expression* left = this->left_;
11693   if (left->is_type_expression())
11694     return this->lower_method_expression(gogo);
11695   return Type::bind_field_or_method(gogo, left->type(), left, this->name_,
11696                                     this->location());
11697 }
11698
11699 // Lower a method expression T.M or (*T).M.  We turn this into a
11700 // function literal.
11701
11702 Expression*
11703 Selector_expression::lower_method_expression(Gogo* gogo)
11704 {
11705   Location location = this->location();
11706   Type* type = this->left_->type();
11707   const std::string& name(this->name_);
11708
11709   bool is_pointer;
11710   if (type->points_to() == NULL)
11711     is_pointer = false;
11712   else
11713     {
11714       is_pointer = true;
11715       type = type->points_to();
11716     }
11717   Named_type* nt = type->named_type();
11718   if (nt == NULL)
11719     {
11720       error_at(location,
11721                ("method expression requires named type or "
11722                 "pointer to named type"));
11723       return Expression::make_error(location);
11724     }
11725
11726   bool is_ambiguous;
11727   Method* method = nt->method_function(name, &is_ambiguous);
11728   const Typed_identifier* imethod = NULL;
11729   if (method == NULL && !is_pointer)
11730     {
11731       Interface_type* it = nt->interface_type();
11732       if (it != NULL)
11733         imethod = it->find_method(name);
11734     }
11735
11736   if (method == NULL && imethod == NULL)
11737     {
11738       if (!is_ambiguous)
11739         error_at(location, "type %<%s%s%> has no method %<%s%>",
11740                  is_pointer ? "*" : "",
11741                  nt->message_name().c_str(),
11742                  Gogo::message_name(name).c_str());
11743       else
11744         error_at(location, "method %<%s%s%> is ambiguous in type %<%s%>",
11745                  Gogo::message_name(name).c_str(),
11746                  is_pointer ? "*" : "",
11747                  nt->message_name().c_str());
11748       return Expression::make_error(location);
11749     }
11750
11751   if (method != NULL && !is_pointer && !method->is_value_method())
11752     {
11753       error_at(location, "method requires pointer (use %<(*%s).%s)%>",
11754                nt->message_name().c_str(),
11755                Gogo::message_name(name).c_str());
11756       return Expression::make_error(location);
11757     }
11758
11759   // Build a new function type in which the receiver becomes the first
11760   // argument.
11761   Function_type* method_type;
11762   if (method != NULL)
11763     {
11764       method_type = method->type();
11765       go_assert(method_type->is_method());
11766     }
11767   else
11768     {
11769       method_type = imethod->type()->function_type();
11770       go_assert(method_type != NULL && !method_type->is_method());
11771     }
11772
11773   const char* const receiver_name = "$this";
11774   Typed_identifier_list* parameters = new Typed_identifier_list();
11775   parameters->push_back(Typed_identifier(receiver_name, this->left_->type(),
11776                                          location));
11777
11778   const Typed_identifier_list* method_parameters = method_type->parameters();
11779   if (method_parameters != NULL)
11780     {
11781       int i = 0;
11782       for (Typed_identifier_list::const_iterator p = method_parameters->begin();
11783            p != method_parameters->end();
11784            ++p, ++i)
11785         {
11786           if (!p->name().empty())
11787             parameters->push_back(*p);
11788           else
11789             {
11790               char buf[20];
11791               snprintf(buf, sizeof buf, "$param%d", i);
11792               parameters->push_back(Typed_identifier(buf, p->type(),
11793                                                      p->location()));
11794             }
11795         }
11796     }
11797
11798   const Typed_identifier_list* method_results = method_type->results();
11799   Typed_identifier_list* results;
11800   if (method_results == NULL)
11801     results = NULL;
11802   else
11803     {
11804       results = new Typed_identifier_list();
11805       for (Typed_identifier_list::const_iterator p = method_results->begin();
11806            p != method_results->end();
11807            ++p)
11808         results->push_back(*p);
11809     }
11810
11811   Function_type* fntype = Type::make_function_type(NULL, parameters, results,
11812                                                    location);
11813   if (method_type->is_varargs())
11814     fntype->set_is_varargs();
11815
11816   // We generate methods which always takes a pointer to the receiver
11817   // as their first argument.  If this is for a pointer type, we can
11818   // simply reuse the existing function.  We use an internal hack to
11819   // get the right type.
11820
11821   if (method != NULL && is_pointer)
11822     {
11823       Named_object* mno = (method->needs_stub_method()
11824                            ? method->stub_object()
11825                            : method->named_object());
11826       Expression* f = Expression::make_func_reference(mno, NULL, location);
11827       f = Expression::make_cast(fntype, f, location);
11828       Type_conversion_expression* tce =
11829         static_cast<Type_conversion_expression*>(f);
11830       tce->set_may_convert_function_types();
11831       return f;
11832     }
11833
11834   Named_object* no = gogo->start_function(Gogo::thunk_name(), fntype, false,
11835                                           location);
11836
11837   Named_object* vno = gogo->lookup(receiver_name, NULL);
11838   go_assert(vno != NULL);
11839   Expression* ve = Expression::make_var_reference(vno, location);
11840   Expression* bm;
11841   if (method != NULL)
11842     bm = Type::bind_field_or_method(gogo, nt, ve, name, location);
11843   else
11844     bm = Expression::make_interface_field_reference(ve, name, location);
11845
11846   // Even though we found the method above, if it has an error type we
11847   // may see an error here.
11848   if (bm->is_error_expression())
11849     {
11850       gogo->finish_function(location);
11851       return bm;
11852     }
11853
11854   Expression_list* args;
11855   if (parameters->size() <= 1)
11856     args = NULL;
11857   else
11858     {
11859       args = new Expression_list();
11860       Typed_identifier_list::const_iterator p = parameters->begin();
11861       ++p;
11862       for (; p != parameters->end(); ++p)
11863         {
11864           vno = gogo->lookup(p->name(), NULL);
11865           go_assert(vno != NULL);
11866           args->push_back(Expression::make_var_reference(vno, location));
11867         }
11868     }
11869
11870   gogo->start_block(location);
11871
11872   Call_expression* call = Expression::make_call(bm, args,
11873                                                 method_type->is_varargs(),
11874                                                 location);
11875
11876   size_t count = call->result_count();
11877   Statement* s;
11878   if (count == 0)
11879     s = Statement::make_statement(call, true);
11880   else
11881     {
11882       Expression_list* retvals = new Expression_list();
11883       if (count <= 1)
11884         retvals->push_back(call);
11885       else
11886         {
11887           for (size_t i = 0; i < count; ++i)
11888             retvals->push_back(Expression::make_call_result(call, i));
11889         }
11890       s = Statement::make_return_statement(retvals, location);
11891     }
11892   gogo->add_statement(s);
11893
11894   Block* b = gogo->finish_block(location);
11895
11896   gogo->add_block(b, location);
11897
11898   // Lower the call in case there are multiple results.
11899   gogo->lower_block(no, b);
11900
11901   gogo->finish_function(location);
11902
11903   return Expression::make_func_reference(no, NULL, location);
11904 }
11905
11906 // Dump the ast for a selector expression.
11907
11908 void
11909 Selector_expression::do_dump_expression(Ast_dump_context* ast_dump_context)
11910     const
11911 {
11912   ast_dump_context->dump_expression(this->left_);
11913   ast_dump_context->ostream() << ".";
11914   ast_dump_context->ostream() << this->name_;
11915 }
11916
11917 // Make a selector expression.
11918
11919 Expression*
11920 Expression::make_selector(Expression* left, const std::string& name,
11921                           Location location)
11922 {
11923   return new Selector_expression(left, name, location);
11924 }
11925
11926 // Implement the builtin function new.
11927
11928 class Allocation_expression : public Expression
11929 {
11930  public:
11931   Allocation_expression(Type* type, Location location)
11932     : Expression(EXPRESSION_ALLOCATION, location),
11933       type_(type)
11934   { }
11935
11936  protected:
11937   int
11938   do_traverse(Traverse* traverse)
11939   { return Type::traverse(this->type_, traverse); }
11940
11941   Type*
11942   do_type()
11943   { return Type::make_pointer_type(this->type_); }
11944
11945   void
11946   do_determine_type(const Type_context*)
11947   { }
11948
11949   Expression*
11950   do_copy()
11951   { return new Allocation_expression(this->type_, this->location()); }
11952
11953   tree
11954   do_get_tree(Translate_context*);
11955
11956   void
11957   do_dump_expression(Ast_dump_context*) const;
11958
11959  private:
11960   // The type we are allocating.
11961   Type* type_;
11962 };
11963
11964 // Return a tree for an allocation expression.
11965
11966 tree
11967 Allocation_expression::do_get_tree(Translate_context* context)
11968 {
11969   tree type_tree = type_to_tree(this->type_->get_backend(context->gogo()));
11970   if (type_tree == error_mark_node)
11971     return error_mark_node;
11972   tree size_tree = TYPE_SIZE_UNIT(type_tree);
11973   tree space = context->gogo()->allocate_memory(this->type_, size_tree,
11974                                                 this->location());
11975   if (space == error_mark_node)
11976     return error_mark_node;
11977   return fold_convert(build_pointer_type(type_tree), space);
11978 }
11979
11980 // Dump ast representation for an allocation expression.
11981
11982 void
11983 Allocation_expression::do_dump_expression(Ast_dump_context* ast_dump_context)
11984     const
11985 {
11986   ast_dump_context->ostream() << "new(";
11987   ast_dump_context->dump_type(this->type_);
11988   ast_dump_context->ostream() << ")";
11989 }
11990
11991 // Make an allocation expression.
11992
11993 Expression*
11994 Expression::make_allocation(Type* type, Location location)
11995 {
11996   return new Allocation_expression(type, location);
11997 }
11998
11999 // Construct a struct.
12000
12001 class Struct_construction_expression : public Expression
12002 {
12003  public:
12004   Struct_construction_expression(Type* type, Expression_list* vals,
12005                                  Location location)
12006     : Expression(EXPRESSION_STRUCT_CONSTRUCTION, location),
12007       type_(type), vals_(vals)
12008   { }
12009
12010   // Return whether this is a constant initializer.
12011   bool
12012   is_constant_struct() const;
12013
12014  protected:
12015   int
12016   do_traverse(Traverse* traverse);
12017
12018   Type*
12019   do_type()
12020   { return this->type_; }
12021
12022   void
12023   do_determine_type(const Type_context*);
12024
12025   void
12026   do_check_types(Gogo*);
12027
12028   Expression*
12029   do_copy()
12030   {
12031     return new Struct_construction_expression(this->type_, this->vals_->copy(),
12032                                               this->location());
12033   }
12034
12035   tree
12036   do_get_tree(Translate_context*);
12037
12038   void
12039   do_export(Export*) const;
12040
12041   void
12042   do_dump_expression(Ast_dump_context*) const;
12043
12044  private:
12045   // The type of the struct to construct.
12046   Type* type_;
12047   // The list of values, in order of the fields in the struct.  A NULL
12048   // entry means that the field should be zero-initialized.
12049   Expression_list* vals_;
12050 };
12051
12052 // Traversal.
12053
12054 int
12055 Struct_construction_expression::do_traverse(Traverse* traverse)
12056 {
12057   if (this->vals_ != NULL
12058       && this->vals_->traverse(traverse) == TRAVERSE_EXIT)
12059     return TRAVERSE_EXIT;
12060   if (Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
12061     return TRAVERSE_EXIT;
12062   return TRAVERSE_CONTINUE;
12063 }
12064
12065 // Return whether this is a constant initializer.
12066
12067 bool
12068 Struct_construction_expression::is_constant_struct() const
12069 {
12070   if (this->vals_ == NULL)
12071     return true;
12072   for (Expression_list::const_iterator pv = this->vals_->begin();
12073        pv != this->vals_->end();
12074        ++pv)
12075     {
12076       if (*pv != NULL
12077           && !(*pv)->is_constant()
12078           && (!(*pv)->is_composite_literal()
12079               || (*pv)->is_nonconstant_composite_literal()))
12080         return false;
12081     }
12082
12083   const Struct_field_list* fields = this->type_->struct_type()->fields();
12084   for (Struct_field_list::const_iterator pf = fields->begin();
12085        pf != fields->end();
12086        ++pf)
12087     {
12088       // There are no constant constructors for interfaces.
12089       if (pf->type()->interface_type() != NULL)
12090         return false;
12091     }
12092
12093   return true;
12094 }
12095
12096 // Final type determination.
12097
12098 void
12099 Struct_construction_expression::do_determine_type(const Type_context*)
12100 {
12101   if (this->vals_ == NULL)
12102     return;
12103   const Struct_field_list* fields = this->type_->struct_type()->fields();
12104   Expression_list::const_iterator pv = this->vals_->begin();
12105   for (Struct_field_list::const_iterator pf = fields->begin();
12106        pf != fields->end();
12107        ++pf, ++pv)
12108     {
12109       if (pv == this->vals_->end())
12110         return;
12111       if (*pv != NULL)
12112         {
12113           Type_context subcontext(pf->type(), false);
12114           (*pv)->determine_type(&subcontext);
12115         }
12116     }
12117   // Extra values are an error we will report elsewhere; we still want
12118   // to determine the type to avoid knockon errors.
12119   for (; pv != this->vals_->end(); ++pv)
12120     (*pv)->determine_type_no_context();
12121 }
12122
12123 // Check types.
12124
12125 void
12126 Struct_construction_expression::do_check_types(Gogo*)
12127 {
12128   if (this->vals_ == NULL)
12129     return;
12130
12131   Struct_type* st = this->type_->struct_type();
12132   if (this->vals_->size() > st->field_count())
12133     {
12134       this->report_error(_("too many expressions for struct"));
12135       return;
12136     }
12137
12138   const Struct_field_list* fields = st->fields();
12139   Expression_list::const_iterator pv = this->vals_->begin();
12140   int i = 0;
12141   for (Struct_field_list::const_iterator pf = fields->begin();
12142        pf != fields->end();
12143        ++pf, ++pv, ++i)
12144     {
12145       if (pv == this->vals_->end())
12146         {
12147           this->report_error(_("too few expressions for struct"));
12148           break;
12149         }
12150
12151       if (*pv == NULL)
12152         continue;
12153
12154       std::string reason;
12155       if (!Type::are_assignable(pf->type(), (*pv)->type(), &reason))
12156         {
12157           if (reason.empty())
12158             error_at((*pv)->location(),
12159                      "incompatible type for field %d in struct construction",
12160                      i + 1);
12161           else
12162             error_at((*pv)->location(),
12163                      ("incompatible type for field %d in "
12164                       "struct construction (%s)"),
12165                      i + 1, reason.c_str());
12166           this->set_is_error();
12167         }
12168     }
12169   go_assert(pv == this->vals_->end());
12170 }
12171
12172 // Return a tree for constructing a struct.
12173
12174 tree
12175 Struct_construction_expression::do_get_tree(Translate_context* context)
12176 {
12177   Gogo* gogo = context->gogo();
12178
12179   if (this->vals_ == NULL)
12180     {
12181       Btype* btype = this->type_->get_backend(gogo);
12182       return expr_to_tree(gogo->backend()->zero_expression(btype));
12183     }
12184
12185   tree type_tree = type_to_tree(this->type_->get_backend(gogo));
12186   if (type_tree == error_mark_node)
12187     return error_mark_node;
12188   go_assert(TREE_CODE(type_tree) == RECORD_TYPE);
12189
12190   bool is_constant = true;
12191   const Struct_field_list* fields = this->type_->struct_type()->fields();
12192   VEC(constructor_elt,gc)* elts = VEC_alloc(constructor_elt, gc,
12193                                             fields->size());
12194   Struct_field_list::const_iterator pf = fields->begin();
12195   Expression_list::const_iterator pv = this->vals_->begin();
12196   for (tree field = TYPE_FIELDS(type_tree);
12197        field != NULL_TREE;
12198        field = DECL_CHAIN(field), ++pf)
12199     {
12200       go_assert(pf != fields->end());
12201
12202       Btype* fbtype = pf->type()->get_backend(gogo);
12203
12204       tree val;
12205       if (pv == this->vals_->end())
12206         val = expr_to_tree(gogo->backend()->zero_expression(fbtype));
12207       else if (*pv == NULL)
12208         {
12209           val = expr_to_tree(gogo->backend()->zero_expression(fbtype));
12210           ++pv;
12211         }
12212       else
12213         {
12214           val = Expression::convert_for_assignment(context, pf->type(),
12215                                                    (*pv)->type(),
12216                                                    (*pv)->get_tree(context),
12217                                                    this->location());
12218           ++pv;
12219         }
12220
12221       if (val == error_mark_node || TREE_TYPE(val) == error_mark_node)
12222         return error_mark_node;
12223
12224       constructor_elt* elt = VEC_quick_push(constructor_elt, elts, NULL);
12225       elt->index = field;
12226       elt->value = val;
12227       if (!TREE_CONSTANT(val))
12228         is_constant = false;
12229     }
12230   go_assert(pf == fields->end());
12231
12232   tree ret = build_constructor(type_tree, elts);
12233   if (is_constant)
12234     TREE_CONSTANT(ret) = 1;
12235   return ret;
12236 }
12237
12238 // Export a struct construction.
12239
12240 void
12241 Struct_construction_expression::do_export(Export* exp) const
12242 {
12243   exp->write_c_string("convert(");
12244   exp->write_type(this->type_);
12245   for (Expression_list::const_iterator pv = this->vals_->begin();
12246        pv != this->vals_->end();
12247        ++pv)
12248     {
12249       exp->write_c_string(", ");
12250       if (*pv != NULL)
12251         (*pv)->export_expression(exp);
12252     }
12253   exp->write_c_string(")");
12254 }
12255
12256 // Dump ast representation of a struct construction expression.
12257
12258 void
12259 Struct_construction_expression::do_dump_expression(
12260     Ast_dump_context* ast_dump_context) const
12261 {
12262   ast_dump_context->dump_type(this->type_);
12263   ast_dump_context->ostream() << "{";
12264   ast_dump_context->dump_expression_list(this->vals_);
12265   ast_dump_context->ostream() << "}";
12266 }
12267
12268 // Make a struct composite literal.  This used by the thunk code.
12269
12270 Expression*
12271 Expression::make_struct_composite_literal(Type* type, Expression_list* vals,
12272                                           Location location)
12273 {
12274   go_assert(type->struct_type() != NULL);
12275   return new Struct_construction_expression(type, vals, location);
12276 }
12277
12278 // Construct an array.  This class is not used directly; instead we
12279 // use the child classes, Fixed_array_construction_expression and
12280 // Open_array_construction_expression.
12281
12282 class Array_construction_expression : public Expression
12283 {
12284  protected:
12285   Array_construction_expression(Expression_classification classification,
12286                                 Type* type, Expression_list* vals,
12287                                 Location location)
12288     : Expression(classification, location),
12289       type_(type), vals_(vals)
12290   { }
12291
12292  public:
12293   // Return whether this is a constant initializer.
12294   bool
12295   is_constant_array() const;
12296
12297   // Return the number of elements.
12298   size_t
12299   element_count() const
12300   { return this->vals_ == NULL ? 0 : this->vals_->size(); }
12301
12302 protected:
12303   int
12304   do_traverse(Traverse* traverse);
12305
12306   Type*
12307   do_type()
12308   { return this->type_; }
12309
12310   void
12311   do_determine_type(const Type_context*);
12312
12313   void
12314   do_check_types(Gogo*);
12315
12316   void
12317   do_export(Export*) const;
12318
12319   // The list of values.
12320   Expression_list*
12321   vals()
12322   { return this->vals_; }
12323
12324   // Get a constructor tree for the array values.
12325   tree
12326   get_constructor_tree(Translate_context* context, tree type_tree);
12327
12328   void
12329   do_dump_expression(Ast_dump_context*) const;
12330
12331  private:
12332   // The type of the array to construct.
12333   Type* type_;
12334   // The list of values.
12335   Expression_list* vals_;
12336 };
12337
12338 // Traversal.
12339
12340 int
12341 Array_construction_expression::do_traverse(Traverse* traverse)
12342 {
12343   if (this->vals_ != NULL
12344       && this->vals_->traverse(traverse) == TRAVERSE_EXIT)
12345     return TRAVERSE_EXIT;
12346   if (Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
12347     return TRAVERSE_EXIT;
12348   return TRAVERSE_CONTINUE;
12349 }
12350
12351 // Return whether this is a constant initializer.
12352
12353 bool
12354 Array_construction_expression::is_constant_array() const
12355 {
12356   if (this->vals_ == NULL)
12357     return true;
12358
12359   // There are no constant constructors for interfaces.
12360   if (this->type_->array_type()->element_type()->interface_type() != NULL)
12361     return false;
12362
12363   for (Expression_list::const_iterator pv = this->vals_->begin();
12364        pv != this->vals_->end();
12365        ++pv)
12366     {
12367       if (*pv != NULL
12368           && !(*pv)->is_constant()
12369           && (!(*pv)->is_composite_literal()
12370               || (*pv)->is_nonconstant_composite_literal()))
12371         return false;
12372     }
12373   return true;
12374 }
12375
12376 // Final type determination.
12377
12378 void
12379 Array_construction_expression::do_determine_type(const Type_context*)
12380 {
12381   if (this->vals_ == NULL)
12382     return;
12383   Type_context subcontext(this->type_->array_type()->element_type(), false);
12384   for (Expression_list::const_iterator pv = this->vals_->begin();
12385        pv != this->vals_->end();
12386        ++pv)
12387     {
12388       if (*pv != NULL)
12389         (*pv)->determine_type(&subcontext);
12390     }
12391 }
12392
12393 // Check types.
12394
12395 void
12396 Array_construction_expression::do_check_types(Gogo*)
12397 {
12398   if (this->vals_ == NULL)
12399     return;
12400
12401   Array_type* at = this->type_->array_type();
12402   int i = 0;
12403   Type* element_type = at->element_type();
12404   for (Expression_list::const_iterator pv = this->vals_->begin();
12405        pv != this->vals_->end();
12406        ++pv, ++i)
12407     {
12408       if (*pv != NULL
12409           && !Type::are_assignable(element_type, (*pv)->type(), NULL))
12410         {
12411           error_at((*pv)->location(),
12412                    "incompatible type for element %d in composite literal",
12413                    i + 1);
12414           this->set_is_error();
12415         }
12416     }
12417
12418   Expression* length = at->length();
12419   if (length != NULL && !length->is_error_expression())
12420     {
12421       mpz_t val;
12422       mpz_init(val);
12423       Type* type;
12424       if (at->length()->integer_constant_value(true, val, &type))
12425         {
12426           if (this->vals_->size() > mpz_get_ui(val))
12427             this->report_error(_("too many elements in composite literal"));
12428         }
12429       mpz_clear(val);
12430     }
12431 }
12432
12433 // Get a constructor tree for the array values.
12434
12435 tree
12436 Array_construction_expression::get_constructor_tree(Translate_context* context,
12437                                                     tree type_tree)
12438 {
12439   VEC(constructor_elt,gc)* values = VEC_alloc(constructor_elt, gc,
12440                                               (this->vals_ == NULL
12441                                                ? 0
12442                                                : this->vals_->size()));
12443   Type* element_type = this->type_->array_type()->element_type();
12444   bool is_constant = true;
12445   if (this->vals_ != NULL)
12446     {
12447       size_t i = 0;
12448       for (Expression_list::const_iterator pv = this->vals_->begin();
12449            pv != this->vals_->end();
12450            ++pv, ++i)
12451         {
12452           constructor_elt* elt = VEC_quick_push(constructor_elt, values, NULL);
12453           elt->index = size_int(i);
12454           if (*pv == NULL)
12455             {
12456               Gogo* gogo = context->gogo();
12457               Btype* ebtype = element_type->get_backend(gogo);
12458               Bexpression *zv = gogo->backend()->zero_expression(ebtype);
12459               elt->value = expr_to_tree(zv);
12460             }
12461           else
12462             {
12463               tree value_tree = (*pv)->get_tree(context);
12464               elt->value = Expression::convert_for_assignment(context,
12465                                                               element_type,
12466                                                               (*pv)->type(),
12467                                                               value_tree,
12468                                                               this->location());
12469             }
12470           if (elt->value == error_mark_node)
12471             return error_mark_node;
12472           if (!TREE_CONSTANT(elt->value))
12473             is_constant = false;
12474         }
12475     }
12476
12477   tree ret = build_constructor(type_tree, values);
12478   if (is_constant)
12479     TREE_CONSTANT(ret) = 1;
12480   return ret;
12481 }
12482
12483 // Export an array construction.
12484
12485 void
12486 Array_construction_expression::do_export(Export* exp) const
12487 {
12488   exp->write_c_string("convert(");
12489   exp->write_type(this->type_);
12490   if (this->vals_ != NULL)
12491     {
12492       for (Expression_list::const_iterator pv = this->vals_->begin();
12493            pv != this->vals_->end();
12494            ++pv)
12495         {
12496           exp->write_c_string(", ");
12497           if (*pv != NULL)
12498             (*pv)->export_expression(exp);
12499         }
12500     }
12501   exp->write_c_string(")");
12502 }
12503
12504 // Dump ast representation of an array construction expressin.
12505
12506 void
12507 Array_construction_expression::do_dump_expression(
12508     Ast_dump_context* ast_dump_context) const
12509 {
12510   Expression* length = this->type_->array_type() != NULL ?
12511                          this->type_->array_type()->length() : NULL;
12512
12513   ast_dump_context->ostream() << "[" ;
12514   if (length != NULL)
12515     {
12516       ast_dump_context->dump_expression(length);
12517     }
12518   ast_dump_context->ostream() << "]" ;
12519   ast_dump_context->dump_type(this->type_);
12520   ast_dump_context->ostream() << "{" ;
12521   ast_dump_context->dump_expression_list(this->vals_);
12522   ast_dump_context->ostream() << "}" ;
12523
12524 }
12525
12526 // Construct a fixed array.
12527
12528 class Fixed_array_construction_expression :
12529   public Array_construction_expression
12530 {
12531  public:
12532   Fixed_array_construction_expression(Type* type, Expression_list* vals,
12533                                       Location location)
12534     : Array_construction_expression(EXPRESSION_FIXED_ARRAY_CONSTRUCTION,
12535                                     type, vals, location)
12536   {
12537     go_assert(type->array_type() != NULL
12538                && type->array_type()->length() != NULL);
12539   }
12540
12541  protected:
12542   Expression*
12543   do_copy()
12544   {
12545     return new Fixed_array_construction_expression(this->type(),
12546                                                    (this->vals() == NULL
12547                                                     ? NULL
12548                                                     : this->vals()->copy()),
12549                                                    this->location());
12550   }
12551
12552   tree
12553   do_get_tree(Translate_context*);
12554
12555   void
12556   do_dump_expression(Ast_dump_context*);
12557 };
12558
12559 // Return a tree for constructing a fixed array.
12560
12561 tree
12562 Fixed_array_construction_expression::do_get_tree(Translate_context* context)
12563 {
12564   Type* type = this->type();
12565   Btype* btype = type->get_backend(context->gogo());
12566   return this->get_constructor_tree(context, type_to_tree(btype));
12567 }
12568
12569 // Dump ast representation of an array construction expressin.
12570
12571 void
12572 Fixed_array_construction_expression::do_dump_expression(
12573     Ast_dump_context* ast_dump_context)
12574 {
12575
12576   ast_dump_context->ostream() << "[";
12577   ast_dump_context->dump_expression (this->type()->array_type()->length());
12578   ast_dump_context->ostream() << "]";
12579   ast_dump_context->dump_type(this->type());
12580   ast_dump_context->ostream() << "{";
12581   ast_dump_context->dump_expression_list(this->vals());
12582   ast_dump_context->ostream() << "}";
12583
12584 }
12585 // Construct an open array.
12586
12587 class Open_array_construction_expression : public Array_construction_expression
12588 {
12589  public:
12590   Open_array_construction_expression(Type* type, Expression_list* vals,
12591                                      Location location)
12592     : Array_construction_expression(EXPRESSION_OPEN_ARRAY_CONSTRUCTION,
12593                                     type, vals, location)
12594   {
12595     go_assert(type->array_type() != NULL
12596                && type->array_type()->length() == NULL);
12597   }
12598
12599  protected:
12600   // Note that taking the address of an open array literal is invalid.
12601
12602   Expression*
12603   do_copy()
12604   {
12605     return new Open_array_construction_expression(this->type(),
12606                                                   (this->vals() == NULL
12607                                                    ? NULL
12608                                                    : this->vals()->copy()),
12609                                                   this->location());
12610   }
12611
12612   tree
12613   do_get_tree(Translate_context*);
12614 };
12615
12616 // Return a tree for constructing an open array.
12617
12618 tree
12619 Open_array_construction_expression::do_get_tree(Translate_context* context)
12620 {
12621   Array_type* array_type = this->type()->array_type();
12622   if (array_type == NULL)
12623     {
12624       go_assert(this->type()->is_error());
12625       return error_mark_node;
12626     }
12627
12628   Type* element_type = array_type->element_type();
12629   Btype* belement_type = element_type->get_backend(context->gogo());
12630   tree element_type_tree = type_to_tree(belement_type);
12631   if (element_type_tree == error_mark_node)
12632     return error_mark_node;
12633
12634   tree values;
12635   tree length_tree;
12636   if (this->vals() == NULL || this->vals()->empty())
12637     {
12638       // We need to create a unique value.
12639       tree max = size_int(0);
12640       tree constructor_type = build_array_type(element_type_tree,
12641                                                build_index_type(max));
12642       if (constructor_type == error_mark_node)
12643         return error_mark_node;
12644       VEC(constructor_elt,gc)* vec = VEC_alloc(constructor_elt, gc, 1);
12645       constructor_elt* elt = VEC_quick_push(constructor_elt, vec, NULL);
12646       elt->index = size_int(0);
12647       Gogo* gogo = context->gogo();
12648       Btype* btype = element_type->get_backend(gogo);
12649       elt->value = expr_to_tree(gogo->backend()->zero_expression(btype));
12650       values = build_constructor(constructor_type, vec);
12651       if (TREE_CONSTANT(elt->value))
12652         TREE_CONSTANT(values) = 1;
12653       length_tree = size_int(0);
12654     }
12655   else
12656     {
12657       tree max = size_int(this->vals()->size() - 1);
12658       tree constructor_type = build_array_type(element_type_tree,
12659                                                build_index_type(max));
12660       if (constructor_type == error_mark_node)
12661         return error_mark_node;
12662       values = this->get_constructor_tree(context, constructor_type);
12663       length_tree = size_int(this->vals()->size());
12664     }
12665
12666   if (values == error_mark_node)
12667     return error_mark_node;
12668
12669   bool is_constant_initializer = TREE_CONSTANT(values);
12670
12671   // We have to copy the initial values into heap memory if we are in
12672   // a function or if the values are not constants.  We also have to
12673   // copy them if they may contain pointers in a non-constant context,
12674   // as otherwise the garbage collector won't see them.
12675   bool copy_to_heap = (context->function() != NULL
12676                        || !is_constant_initializer
12677                        || (element_type->has_pointer()
12678                            && !context->is_const()));
12679
12680   if (is_constant_initializer)
12681     {
12682       tree tmp = build_decl(this->location().gcc_location(), VAR_DECL,
12683                             create_tmp_var_name("C"), TREE_TYPE(values));
12684       DECL_EXTERNAL(tmp) = 0;
12685       TREE_PUBLIC(tmp) = 0;
12686       TREE_STATIC(tmp) = 1;
12687       DECL_ARTIFICIAL(tmp) = 1;
12688       if (copy_to_heap)
12689         {
12690           // If we are not copying the value to the heap, we will only
12691           // initialize the value once, so we can use this directly
12692           // rather than copying it.  In that case we can't make it
12693           // read-only, because the program is permitted to change it.
12694           TREE_READONLY(tmp) = 1;
12695           TREE_CONSTANT(tmp) = 1;
12696         }
12697       DECL_INITIAL(tmp) = values;
12698       rest_of_decl_compilation(tmp, 1, 0);
12699       values = tmp;
12700     }
12701
12702   tree space;
12703   tree set;
12704   if (!copy_to_heap)
12705     {
12706       // the initializer will only run once.
12707       space = build_fold_addr_expr(values);
12708       set = NULL_TREE;
12709     }
12710   else
12711     {
12712       tree memsize = TYPE_SIZE_UNIT(TREE_TYPE(values));
12713       space = context->gogo()->allocate_memory(element_type, memsize,
12714                                                this->location());
12715       space = save_expr(space);
12716
12717       tree s = fold_convert(build_pointer_type(TREE_TYPE(values)), space);
12718       tree ref = build_fold_indirect_ref_loc(this->location().gcc_location(),
12719                                              s);
12720       TREE_THIS_NOTRAP(ref) = 1;
12721       set = build2(MODIFY_EXPR, void_type_node, ref, values);
12722     }
12723
12724   // Build a constructor for the open array.
12725
12726   tree type_tree = type_to_tree(this->type()->get_backend(context->gogo()));
12727   if (type_tree == error_mark_node)
12728     return error_mark_node;
12729   go_assert(TREE_CODE(type_tree) == RECORD_TYPE);
12730
12731   VEC(constructor_elt,gc)* init = VEC_alloc(constructor_elt, gc, 3);
12732
12733   constructor_elt* elt = VEC_quick_push(constructor_elt, init, NULL);
12734   tree field = TYPE_FIELDS(type_tree);
12735   go_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__values") == 0);
12736   elt->index = field;
12737   elt->value = fold_convert(TREE_TYPE(field), space);
12738
12739   elt = VEC_quick_push(constructor_elt, init, NULL);
12740   field = DECL_CHAIN(field);
12741   go_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__count") == 0);
12742   elt->index = field;
12743   elt->value = fold_convert(TREE_TYPE(field), length_tree);
12744
12745   elt = VEC_quick_push(constructor_elt, init, NULL);
12746   field = DECL_CHAIN(field);
12747   go_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)),"__capacity") == 0);
12748   elt->index = field;
12749   elt->value = fold_convert(TREE_TYPE(field), length_tree);
12750
12751   tree constructor = build_constructor(type_tree, init);
12752   if (constructor == error_mark_node)
12753     return error_mark_node;
12754   if (!copy_to_heap)
12755     TREE_CONSTANT(constructor) = 1;
12756
12757   if (set == NULL_TREE)
12758     return constructor;
12759   else
12760     return build2(COMPOUND_EXPR, type_tree, set, constructor);
12761 }
12762
12763 // Make a slice composite literal.  This is used by the type
12764 // descriptor code.
12765
12766 Expression*
12767 Expression::make_slice_composite_literal(Type* type, Expression_list* vals,
12768                                          Location location)
12769 {
12770   go_assert(type->is_slice_type());
12771   return new Open_array_construction_expression(type, vals, location);
12772 }
12773
12774 // Construct a map.
12775
12776 class Map_construction_expression : public Expression
12777 {
12778  public:
12779   Map_construction_expression(Type* type, Expression_list* vals,
12780                               Location location)
12781     : Expression(EXPRESSION_MAP_CONSTRUCTION, location),
12782       type_(type), vals_(vals)
12783   { go_assert(vals == NULL || vals->size() % 2 == 0); }
12784
12785  protected:
12786   int
12787   do_traverse(Traverse* traverse);
12788
12789   Type*
12790   do_type()
12791   { return this->type_; }
12792
12793   void
12794   do_determine_type(const Type_context*);
12795
12796   void
12797   do_check_types(Gogo*);
12798
12799   Expression*
12800   do_copy()
12801   {
12802     return new Map_construction_expression(this->type_, this->vals_->copy(),
12803                                            this->location());
12804   }
12805
12806   tree
12807   do_get_tree(Translate_context*);
12808
12809   void
12810   do_export(Export*) const;
12811
12812   void
12813   do_dump_expression(Ast_dump_context*) const;
12814
12815  private:
12816   // The type of the map to construct.
12817   Type* type_;
12818   // The list of values.
12819   Expression_list* vals_;
12820 };
12821
12822 // Traversal.
12823
12824 int
12825 Map_construction_expression::do_traverse(Traverse* traverse)
12826 {
12827   if (this->vals_ != NULL
12828       && this->vals_->traverse(traverse) == TRAVERSE_EXIT)
12829     return TRAVERSE_EXIT;
12830   if (Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
12831     return TRAVERSE_EXIT;
12832   return TRAVERSE_CONTINUE;
12833 }
12834
12835 // Final type determination.
12836
12837 void
12838 Map_construction_expression::do_determine_type(const Type_context*)
12839 {
12840   if (this->vals_ == NULL)
12841     return;
12842
12843   Map_type* mt = this->type_->map_type();
12844   Type_context key_context(mt->key_type(), false);
12845   Type_context val_context(mt->val_type(), false);
12846   for (Expression_list::const_iterator pv = this->vals_->begin();
12847        pv != this->vals_->end();
12848        ++pv)
12849     {
12850       (*pv)->determine_type(&key_context);
12851       ++pv;
12852       (*pv)->determine_type(&val_context);
12853     }
12854 }
12855
12856 // Check types.
12857
12858 void
12859 Map_construction_expression::do_check_types(Gogo*)
12860 {
12861   if (this->vals_ == NULL)
12862     return;
12863
12864   Map_type* mt = this->type_->map_type();
12865   int i = 0;
12866   Type* key_type = mt->key_type();
12867   Type* val_type = mt->val_type();
12868   for (Expression_list::const_iterator pv = this->vals_->begin();
12869        pv != this->vals_->end();
12870        ++pv, ++i)
12871     {
12872       if (!Type::are_assignable(key_type, (*pv)->type(), NULL))
12873         {
12874           error_at((*pv)->location(),
12875                    "incompatible type for element %d key in map construction",
12876                    i + 1);
12877           this->set_is_error();
12878         }
12879       ++pv;
12880       if (!Type::are_assignable(val_type, (*pv)->type(), NULL))
12881         {
12882           error_at((*pv)->location(),
12883                    ("incompatible type for element %d value "
12884                     "in map construction"),
12885                    i + 1);
12886           this->set_is_error();
12887         }
12888     }
12889 }
12890
12891 // Return a tree for constructing a map.
12892
12893 tree
12894 Map_construction_expression::do_get_tree(Translate_context* context)
12895 {
12896   Gogo* gogo = context->gogo();
12897   Location loc = this->location();
12898
12899   Map_type* mt = this->type_->map_type();
12900
12901   // Build a struct to hold the key and value.
12902   tree struct_type = make_node(RECORD_TYPE);
12903
12904   Type* key_type = mt->key_type();
12905   tree id = get_identifier("__key");
12906   tree key_type_tree = type_to_tree(key_type->get_backend(gogo));
12907   if (key_type_tree == error_mark_node)
12908     return error_mark_node;
12909   tree key_field = build_decl(loc.gcc_location(), FIELD_DECL, id,
12910                               key_type_tree);
12911   DECL_CONTEXT(key_field) = struct_type;
12912   TYPE_FIELDS(struct_type) = key_field;
12913
12914   Type* val_type = mt->val_type();
12915   id = get_identifier("__val");
12916   tree val_type_tree = type_to_tree(val_type->get_backend(gogo));
12917   if (val_type_tree == error_mark_node)
12918     return error_mark_node;
12919   tree val_field = build_decl(loc.gcc_location(), FIELD_DECL, id,
12920                               val_type_tree);
12921   DECL_CONTEXT(val_field) = struct_type;
12922   DECL_CHAIN(key_field) = val_field;
12923
12924   layout_type(struct_type);
12925
12926   bool is_constant = true;
12927   size_t i = 0;
12928   tree valaddr;
12929   tree make_tmp;
12930
12931   if (this->vals_ == NULL || this->vals_->empty())
12932     {
12933       valaddr = null_pointer_node;
12934       make_tmp = NULL_TREE;
12935     }
12936   else
12937     {
12938       VEC(constructor_elt,gc)* values = VEC_alloc(constructor_elt, gc,
12939                                                   this->vals_->size() / 2);
12940
12941       for (Expression_list::const_iterator pv = this->vals_->begin();
12942            pv != this->vals_->end();
12943            ++pv, ++i)
12944         {
12945           bool one_is_constant = true;
12946
12947           VEC(constructor_elt,gc)* one = VEC_alloc(constructor_elt, gc, 2);
12948
12949           constructor_elt* elt = VEC_quick_push(constructor_elt, one, NULL);
12950           elt->index = key_field;
12951           tree val_tree = (*pv)->get_tree(context);
12952           elt->value = Expression::convert_for_assignment(context, key_type,
12953                                                           (*pv)->type(),
12954                                                           val_tree, loc);
12955           if (elt->value == error_mark_node)
12956             return error_mark_node;
12957           if (!TREE_CONSTANT(elt->value))
12958             one_is_constant = false;
12959
12960           ++pv;
12961
12962           elt = VEC_quick_push(constructor_elt, one, NULL);
12963           elt->index = val_field;
12964           val_tree = (*pv)->get_tree(context);
12965           elt->value = Expression::convert_for_assignment(context, val_type,
12966                                                           (*pv)->type(),
12967                                                           val_tree, loc);
12968           if (elt->value == error_mark_node)
12969             return error_mark_node;
12970           if (!TREE_CONSTANT(elt->value))
12971             one_is_constant = false;
12972
12973           elt = VEC_quick_push(constructor_elt, values, NULL);
12974           elt->index = size_int(i);
12975           elt->value = build_constructor(struct_type, one);
12976           if (one_is_constant)
12977             TREE_CONSTANT(elt->value) = 1;
12978           else
12979             is_constant = false;
12980         }
12981
12982       tree index_type = build_index_type(size_int(i - 1));
12983       tree array_type = build_array_type(struct_type, index_type);
12984       tree init = build_constructor(array_type, values);
12985       if (is_constant)
12986         TREE_CONSTANT(init) = 1;
12987       tree tmp;
12988       if (current_function_decl != NULL)
12989         {
12990           tmp = create_tmp_var(array_type, get_name(array_type));
12991           DECL_INITIAL(tmp) = init;
12992           make_tmp = fold_build1_loc(loc.gcc_location(), DECL_EXPR,
12993                                      void_type_node, tmp);
12994           TREE_ADDRESSABLE(tmp) = 1;
12995         }
12996       else
12997         {
12998           tmp = build_decl(loc.gcc_location(), VAR_DECL,
12999                            create_tmp_var_name("M"), array_type);
13000           DECL_EXTERNAL(tmp) = 0;
13001           TREE_PUBLIC(tmp) = 0;
13002           TREE_STATIC(tmp) = 1;
13003           DECL_ARTIFICIAL(tmp) = 1;
13004           if (!TREE_CONSTANT(init))
13005             make_tmp = fold_build2_loc(loc.gcc_location(), INIT_EXPR,
13006                                        void_type_node, tmp, init);
13007           else
13008             {
13009               TREE_READONLY(tmp) = 1;
13010               TREE_CONSTANT(tmp) = 1;
13011               DECL_INITIAL(tmp) = init;
13012               make_tmp = NULL_TREE;
13013             }
13014           rest_of_decl_compilation(tmp, 1, 0);
13015         }
13016
13017       valaddr = build_fold_addr_expr(tmp);
13018     }
13019
13020   tree descriptor = mt->map_descriptor_pointer(gogo, loc);
13021
13022   tree type_tree = type_to_tree(this->type_->get_backend(gogo));
13023   if (type_tree == error_mark_node)
13024     return error_mark_node;
13025
13026   static tree construct_map_fndecl;
13027   tree call = Gogo::call_builtin(&construct_map_fndecl,
13028                                  loc,
13029                                  "__go_construct_map",
13030                                  6,
13031                                  type_tree,
13032                                  TREE_TYPE(descriptor),
13033                                  descriptor,
13034                                  sizetype,
13035                                  size_int(i),
13036                                  sizetype,
13037                                  TYPE_SIZE_UNIT(struct_type),
13038                                  sizetype,
13039                                  byte_position(val_field),
13040                                  sizetype,
13041                                  TYPE_SIZE_UNIT(TREE_TYPE(val_field)),
13042                                  const_ptr_type_node,
13043                                  fold_convert(const_ptr_type_node, valaddr));
13044   if (call == error_mark_node)
13045     return error_mark_node;
13046
13047   tree ret;
13048   if (make_tmp == NULL)
13049     ret = call;
13050   else
13051     ret = fold_build2_loc(loc.gcc_location(), COMPOUND_EXPR, type_tree,
13052                           make_tmp, call);
13053   return ret;
13054 }
13055
13056 // Export an array construction.
13057
13058 void
13059 Map_construction_expression::do_export(Export* exp) const
13060 {
13061   exp->write_c_string("convert(");
13062   exp->write_type(this->type_);
13063   for (Expression_list::const_iterator pv = this->vals_->begin();
13064        pv != this->vals_->end();
13065        ++pv)
13066     {
13067       exp->write_c_string(", ");
13068       (*pv)->export_expression(exp);
13069     }
13070   exp->write_c_string(")");
13071 }
13072
13073 // Dump ast representation for a map construction expression.
13074
13075 void
13076 Map_construction_expression::do_dump_expression(
13077     Ast_dump_context* ast_dump_context) const
13078 {
13079   ast_dump_context->ostream() << "{" ;
13080   ast_dump_context->dump_expression_list(this->vals_, true);
13081   ast_dump_context->ostream() << "}";
13082 }
13083
13084 // A general composite literal.  This is lowered to a type specific
13085 // version.
13086
13087 class Composite_literal_expression : public Parser_expression
13088 {
13089  public:
13090   Composite_literal_expression(Type* type, int depth, bool has_keys,
13091                                Expression_list* vals, Location location)
13092     : Parser_expression(EXPRESSION_COMPOSITE_LITERAL, location),
13093       type_(type), depth_(depth), vals_(vals), has_keys_(has_keys)
13094   { }
13095
13096  protected:
13097   int
13098   do_traverse(Traverse* traverse);
13099
13100   Expression*
13101   do_lower(Gogo*, Named_object*, Statement_inserter*, int);
13102
13103   Expression*
13104   do_copy()
13105   {
13106     return new Composite_literal_expression(this->type_, this->depth_,
13107                                             this->has_keys_,
13108                                             (this->vals_ == NULL
13109                                              ? NULL
13110                                              : this->vals_->copy()),
13111                                             this->location());
13112   }
13113
13114   void
13115   do_dump_expression(Ast_dump_context*) const;
13116
13117  private:
13118   Expression*
13119   lower_struct(Gogo*, Type*);
13120
13121   Expression*
13122   lower_array(Type*);
13123
13124   Expression*
13125   make_array(Type*, Expression_list*);
13126
13127   Expression*
13128   lower_map(Gogo*, Named_object*, Statement_inserter*, Type*);
13129
13130   // The type of the composite literal.
13131   Type* type_;
13132   // The depth within a list of composite literals within a composite
13133   // literal, when the type is omitted.
13134   int depth_;
13135   // The values to put in the composite literal.
13136   Expression_list* vals_;
13137   // If this is true, then VALS_ is a list of pairs: a key and a
13138   // value.  In an array initializer, a missing key will be NULL.
13139   bool has_keys_;
13140 };
13141
13142 // Traversal.
13143
13144 int
13145 Composite_literal_expression::do_traverse(Traverse* traverse)
13146 {
13147   if (this->vals_ != NULL
13148       && this->vals_->traverse(traverse) == TRAVERSE_EXIT)
13149     return TRAVERSE_EXIT;
13150   return Type::traverse(this->type_, traverse);
13151 }
13152
13153 // Lower a generic composite literal into a specific version based on
13154 // the type.
13155
13156 Expression*
13157 Composite_literal_expression::do_lower(Gogo* gogo, Named_object* function,
13158                                        Statement_inserter* inserter, int)
13159 {
13160   Type* type = this->type_;
13161
13162   for (int depth = this->depth_; depth > 0; --depth)
13163     {
13164       if (type->array_type() != NULL)
13165         type = type->array_type()->element_type();
13166       else if (type->map_type() != NULL)
13167         type = type->map_type()->val_type();
13168       else
13169         {
13170           if (!type->is_error())
13171             error_at(this->location(),
13172                      ("may only omit types within composite literals "
13173                       "of slice, array, or map type"));
13174           return Expression::make_error(this->location());
13175         }
13176     }
13177
13178   Type *pt = type->points_to();
13179   bool is_pointer = false;
13180   if (pt != NULL)
13181     {
13182       is_pointer = true;
13183       type = pt;
13184     }
13185
13186   Expression* ret;
13187   if (type->is_error())
13188     return Expression::make_error(this->location());
13189   else if (type->struct_type() != NULL)
13190     ret = this->lower_struct(gogo, type);
13191   else if (type->array_type() != NULL)
13192     ret = this->lower_array(type);
13193   else if (type->map_type() != NULL)
13194     ret = this->lower_map(gogo, function, inserter, type);
13195   else
13196     {
13197       error_at(this->location(),
13198                ("expected struct, slice, array, or map type "
13199                 "for composite literal"));
13200       return Expression::make_error(this->location());
13201     }
13202
13203   if (is_pointer)
13204     ret = Expression::make_heap_composite(ret, this->location());
13205
13206   return ret;
13207 }
13208
13209 // Lower a struct composite literal.
13210
13211 Expression*
13212 Composite_literal_expression::lower_struct(Gogo* gogo, Type* type)
13213 {
13214   Location location = this->location();
13215   Struct_type* st = type->struct_type();
13216   if (this->vals_ == NULL || !this->has_keys_)
13217     {
13218       if (this->vals_ != NULL
13219           && !this->vals_->empty()
13220           && type->named_type() != NULL
13221           && type->named_type()->named_object()->package() != NULL)
13222         {
13223           for (Struct_field_list::const_iterator pf = st->fields()->begin();
13224                pf != st->fields()->end();
13225                ++pf)
13226             {
13227               if (Gogo::is_hidden_name(pf->field_name()))
13228                 error_at(this->location(),
13229                          "assignment of unexported field %qs in %qs literal",
13230                          Gogo::message_name(pf->field_name()).c_str(),
13231                          type->named_type()->message_name().c_str());
13232             }
13233         }
13234
13235       return new Struct_construction_expression(type, this->vals_, location);
13236     }
13237
13238   size_t field_count = st->field_count();
13239   std::vector<Expression*> vals(field_count);
13240   Expression_list::const_iterator p = this->vals_->begin();
13241   while (p != this->vals_->end())
13242     {
13243       Expression* name_expr = *p;
13244
13245       ++p;
13246       go_assert(p != this->vals_->end());
13247       Expression* val = *p;
13248
13249       ++p;
13250
13251       if (name_expr == NULL)
13252         {
13253           error_at(val->location(), "mixture of field and value initializers");
13254           return Expression::make_error(location);
13255         }
13256
13257       bool bad_key = false;
13258       std::string name;
13259       const Named_object* no = NULL;
13260       switch (name_expr->classification())
13261         {
13262         case EXPRESSION_UNKNOWN_REFERENCE:
13263           name = name_expr->unknown_expression()->name();
13264           break;
13265
13266         case EXPRESSION_CONST_REFERENCE:
13267           no = static_cast<Const_expression*>(name_expr)->named_object();
13268           break;
13269
13270         case EXPRESSION_TYPE:
13271           {
13272             Type* t = name_expr->type();
13273             Named_type* nt = t->named_type();
13274             if (nt == NULL)
13275               bad_key = true;
13276             else
13277               no = nt->named_object();
13278           }
13279           break;
13280
13281         case EXPRESSION_VAR_REFERENCE:
13282           no = name_expr->var_expression()->named_object();
13283           break;
13284
13285         case EXPRESSION_FUNC_REFERENCE:
13286           no = name_expr->func_expression()->named_object();
13287           break;
13288
13289         case EXPRESSION_UNARY:
13290           // If there is a local variable around with the same name as
13291           // the field, and this occurs in the closure, then the
13292           // parser may turn the field reference into an indirection
13293           // through the closure.  FIXME: This is a mess.
13294           {
13295             bad_key = true;
13296             Unary_expression* ue = static_cast<Unary_expression*>(name_expr);
13297             if (ue->op() == OPERATOR_MULT)
13298               {
13299                 Field_reference_expression* fre =
13300                   ue->operand()->field_reference_expression();
13301                 if (fre != NULL)
13302                   {
13303                     Struct_type* st =
13304                       fre->expr()->type()->deref()->struct_type();
13305                     if (st != NULL)
13306                       {
13307                         const Struct_field* sf = st->field(fre->field_index());
13308                         name = sf->field_name();
13309
13310                         // See below.  FIXME.
13311                         if (!Gogo::is_hidden_name(name)
13312                             && name[0] >= 'a'
13313                             && name[0] <= 'z')
13314                           {
13315                             if (gogo->lookup_global(name.c_str()) != NULL)
13316                               name = gogo->pack_hidden_name(name, false);
13317                           }
13318
13319                         char buf[20];
13320                         snprintf(buf, sizeof buf, "%u", fre->field_index());
13321                         size_t buflen = strlen(buf);
13322                         if (name.compare(name.length() - buflen, buflen, buf)
13323                             == 0)
13324                           {
13325                             name = name.substr(0, name.length() - buflen);
13326                             bad_key = false;
13327                           }
13328                       }
13329                   }
13330               }
13331           }
13332           break;
13333
13334         default:
13335           bad_key = true;
13336           break;
13337         }
13338       if (bad_key)
13339         {
13340           error_at(name_expr->location(), "expected struct field name");
13341           return Expression::make_error(location);
13342         }
13343
13344       if (no != NULL)
13345         {
13346           name = no->name();
13347
13348           // A predefined name won't be packed.  If it starts with a
13349           // lower case letter we need to check for that case, because
13350           // the field name will be packed.  FIXME.
13351           if (!Gogo::is_hidden_name(name)
13352               && name[0] >= 'a'
13353               && name[0] <= 'z')
13354             {
13355               Named_object* gno = gogo->lookup_global(name.c_str());
13356               if (gno == no)
13357                 name = gogo->pack_hidden_name(name, false);
13358             }
13359         }
13360
13361       unsigned int index;
13362       const Struct_field* sf = st->find_local_field(name, &index);
13363       if (sf == NULL)
13364         {
13365           error_at(name_expr->location(), "unknown field %qs in %qs",
13366                    Gogo::message_name(name).c_str(),
13367                    (type->named_type() != NULL
13368                     ? type->named_type()->message_name().c_str()
13369                     : "unnamed struct"));
13370           return Expression::make_error(location);
13371         }
13372       if (vals[index] != NULL)
13373         {
13374           error_at(name_expr->location(),
13375                    "duplicate value for field %qs in %qs",
13376                    Gogo::message_name(name).c_str(),
13377                    (type->named_type() != NULL
13378                     ? type->named_type()->message_name().c_str()
13379                     : "unnamed struct"));
13380           return Expression::make_error(location);
13381         }
13382
13383       if (type->named_type() != NULL
13384           && type->named_type()->named_object()->package() != NULL
13385           && Gogo::is_hidden_name(sf->field_name()))
13386         error_at(name_expr->location(),
13387                  "assignment of unexported field %qs in %qs literal",
13388                  Gogo::message_name(sf->field_name()).c_str(),
13389                  type->named_type()->message_name().c_str());
13390
13391       vals[index] = val;
13392     }
13393
13394   Expression_list* list = new Expression_list;
13395   list->reserve(field_count);
13396   for (size_t i = 0; i < field_count; ++i)
13397     list->push_back(vals[i]);
13398
13399   return new Struct_construction_expression(type, list, location);
13400 }
13401
13402 // Lower an array composite literal.
13403
13404 Expression*
13405 Composite_literal_expression::lower_array(Type* type)
13406 {
13407   Location location = this->location();
13408   if (this->vals_ == NULL || !this->has_keys_)
13409     return this->make_array(type, this->vals_);
13410
13411   std::vector<Expression*> vals;
13412   vals.reserve(this->vals_->size());
13413   unsigned long index = 0;
13414   Expression_list::const_iterator p = this->vals_->begin();
13415   while (p != this->vals_->end())
13416     {
13417       Expression* index_expr = *p;
13418
13419       ++p;
13420       go_assert(p != this->vals_->end());
13421       Expression* val = *p;
13422
13423       ++p;
13424
13425       if (index_expr != NULL)
13426         {
13427           mpz_t ival;
13428           mpz_init(ival);
13429
13430           Type* dummy;
13431           if (!index_expr->integer_constant_value(true, ival, &dummy))
13432             {
13433               mpz_clear(ival);
13434               error_at(index_expr->location(),
13435                        "index expression is not integer constant");
13436               return Expression::make_error(location);
13437             }
13438
13439           if (mpz_sgn(ival) < 0)
13440             {
13441               mpz_clear(ival);
13442               error_at(index_expr->location(), "index expression is negative");
13443               return Expression::make_error(location);
13444             }
13445
13446           index = mpz_get_ui(ival);
13447           if (mpz_cmp_ui(ival, index) != 0)
13448             {
13449               mpz_clear(ival);
13450               error_at(index_expr->location(), "index value overflow");
13451               return Expression::make_error(location);
13452             }
13453
13454           Named_type* ntype = Type::lookup_integer_type("int");
13455           Integer_type* inttype = ntype->integer_type();
13456           mpz_t max;
13457           mpz_init_set_ui(max, 1);
13458           mpz_mul_2exp(max, max, inttype->bits() - 1);
13459           bool ok = mpz_cmp(ival, max) < 0;
13460           mpz_clear(max);
13461           if (!ok)
13462             {
13463               mpz_clear(ival);
13464               error_at(index_expr->location(), "index value overflow");
13465               return Expression::make_error(location);
13466             }
13467
13468           mpz_clear(ival);
13469
13470           // FIXME: Our representation isn't very good; this avoids
13471           // thrashing.
13472           if (index > 0x1000000)
13473             {
13474               error_at(index_expr->location(), "index too large for compiler");
13475               return Expression::make_error(location);
13476             }
13477         }
13478
13479       if (index == vals.size())
13480         vals.push_back(val);
13481       else
13482         {
13483           if (index > vals.size())
13484             {
13485               vals.reserve(index + 32);
13486               vals.resize(index + 1, static_cast<Expression*>(NULL));
13487             }
13488           if (vals[index] != NULL)
13489             {
13490               error_at((index_expr != NULL
13491                         ? index_expr->location()
13492                         : val->location()),
13493                        "duplicate value for index %lu",
13494                        index);
13495               return Expression::make_error(location);
13496             }
13497           vals[index] = val;
13498         }
13499
13500       ++index;
13501     }
13502
13503   size_t size = vals.size();
13504   Expression_list* list = new Expression_list;
13505   list->reserve(size);
13506   for (size_t i = 0; i < size; ++i)
13507     list->push_back(vals[i]);
13508
13509   return this->make_array(type, list);
13510 }
13511
13512 // Actually build the array composite literal. This handles
13513 // [...]{...}.
13514
13515 Expression*
13516 Composite_literal_expression::make_array(Type* type, Expression_list* vals)
13517 {
13518   Location location = this->location();
13519   Array_type* at = type->array_type();
13520   if (at->length() != NULL && at->length()->is_nil_expression())
13521     {
13522       size_t size = vals == NULL ? 0 : vals->size();
13523       mpz_t vlen;
13524       mpz_init_set_ui(vlen, size);
13525       Expression* elen = Expression::make_integer(&vlen, NULL, location);
13526       mpz_clear(vlen);
13527       at = Type::make_array_type(at->element_type(), elen);
13528       type = at;
13529     }
13530   if (at->length() != NULL)
13531     return new Fixed_array_construction_expression(type, vals, location);
13532   else
13533     return new Open_array_construction_expression(type, vals, location);
13534 }
13535
13536 // Lower a map composite literal.
13537
13538 Expression*
13539 Composite_literal_expression::lower_map(Gogo* gogo, Named_object* function,
13540                                         Statement_inserter* inserter,
13541                                         Type* type)
13542 {
13543   Location location = this->location();
13544   if (this->vals_ != NULL)
13545     {
13546       if (!this->has_keys_)
13547         {
13548           error_at(location, "map composite literal must have keys");
13549           return Expression::make_error(location);
13550         }
13551
13552       for (Expression_list::iterator p = this->vals_->begin();
13553            p != this->vals_->end();
13554            p += 2)
13555         {
13556           if (*p == NULL)
13557             {
13558               ++p;
13559               error_at((*p)->location(),
13560                        "map composite literal must have keys for every value");
13561               return Expression::make_error(location);
13562             }
13563           // Make sure we have lowered the key; it may not have been
13564           // lowered in order to handle keys for struct composite
13565           // literals.  Lower it now to get the right error message.
13566           if ((*p)->unknown_expression() != NULL)
13567             {
13568               (*p)->unknown_expression()->clear_is_composite_literal_key();
13569               gogo->lower_expression(function, inserter, &*p);
13570               go_assert((*p)->is_error_expression());
13571               return Expression::make_error(location);
13572             }
13573         }
13574     }
13575
13576   return new Map_construction_expression(type, this->vals_, location);
13577 }
13578
13579 // Dump ast representation for a composite literal expression.
13580
13581 void
13582 Composite_literal_expression::do_dump_expression(
13583                                Ast_dump_context* ast_dump_context) const
13584 {
13585   ast_dump_context->ostream() << "composite(";
13586   ast_dump_context->dump_type(this->type_);
13587   ast_dump_context->ostream() << ", {";
13588   ast_dump_context->dump_expression_list(this->vals_, this->has_keys_);
13589   ast_dump_context->ostream() << "})";
13590 }
13591
13592 // Make a composite literal expression.
13593
13594 Expression*
13595 Expression::make_composite_literal(Type* type, int depth, bool has_keys,
13596                                    Expression_list* vals,
13597                                    Location location)
13598 {
13599   return new Composite_literal_expression(type, depth, has_keys, vals,
13600                                           location);
13601 }
13602
13603 // Return whether this expression is a composite literal.
13604
13605 bool
13606 Expression::is_composite_literal() const
13607 {
13608   switch (this->classification_)
13609     {
13610     case EXPRESSION_COMPOSITE_LITERAL:
13611     case EXPRESSION_STRUCT_CONSTRUCTION:
13612     case EXPRESSION_FIXED_ARRAY_CONSTRUCTION:
13613     case EXPRESSION_OPEN_ARRAY_CONSTRUCTION:
13614     case EXPRESSION_MAP_CONSTRUCTION:
13615       return true;
13616     default:
13617       return false;
13618     }
13619 }
13620
13621 // Return whether this expression is a composite literal which is not
13622 // constant.
13623
13624 bool
13625 Expression::is_nonconstant_composite_literal() const
13626 {
13627   switch (this->classification_)
13628     {
13629     case EXPRESSION_STRUCT_CONSTRUCTION:
13630       {
13631         const Struct_construction_expression *psce =
13632           static_cast<const Struct_construction_expression*>(this);
13633         return !psce->is_constant_struct();
13634       }
13635     case EXPRESSION_FIXED_ARRAY_CONSTRUCTION:
13636       {
13637         const Fixed_array_construction_expression *pace =
13638           static_cast<const Fixed_array_construction_expression*>(this);
13639         return !pace->is_constant_array();
13640       }
13641     case EXPRESSION_OPEN_ARRAY_CONSTRUCTION:
13642       {
13643         const Open_array_construction_expression *pace =
13644           static_cast<const Open_array_construction_expression*>(this);
13645         return !pace->is_constant_array();
13646       }
13647     case EXPRESSION_MAP_CONSTRUCTION:
13648       return true;
13649     default:
13650       return false;
13651     }
13652 }
13653
13654 // Return true if this is a reference to a local variable.
13655
13656 bool
13657 Expression::is_local_variable() const
13658 {
13659   const Var_expression* ve = this->var_expression();
13660   if (ve == NULL)
13661     return false;
13662   const Named_object* no = ve->named_object();
13663   return (no->is_result_variable()
13664           || (no->is_variable() && !no->var_value()->is_global()));
13665 }
13666
13667 // Class Type_guard_expression.
13668
13669 // Traversal.
13670
13671 int
13672 Type_guard_expression::do_traverse(Traverse* traverse)
13673 {
13674   if (Expression::traverse(&this->expr_, traverse) == TRAVERSE_EXIT
13675       || Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
13676     return TRAVERSE_EXIT;
13677   return TRAVERSE_CONTINUE;
13678 }
13679
13680 // Check types of a type guard expression.  The expression must have
13681 // an interface type, but the actual type conversion is checked at run
13682 // time.
13683
13684 void
13685 Type_guard_expression::do_check_types(Gogo*)
13686 {
13687   // 6g permits using a type guard with unsafe.pointer; we are
13688   // compatible.
13689   Type* expr_type = this->expr_->type();
13690   if (expr_type->is_unsafe_pointer_type())
13691     {
13692       if (this->type_->points_to() == NULL
13693           && (this->type_->integer_type() == NULL
13694               || (this->type_->forwarded()
13695                   != Type::lookup_integer_type("uintptr"))))
13696         this->report_error(_("invalid unsafe.Pointer conversion"));
13697     }
13698   else if (this->type_->is_unsafe_pointer_type())
13699     {
13700       if (expr_type->points_to() == NULL
13701           && (expr_type->integer_type() == NULL
13702               || (expr_type->forwarded()
13703                   != Type::lookup_integer_type("uintptr"))))
13704         this->report_error(_("invalid unsafe.Pointer conversion"));
13705     }
13706   else if (expr_type->interface_type() == NULL)
13707     {
13708       if (!expr_type->is_error() && !this->type_->is_error())
13709         this->report_error(_("type assertion only valid for interface types"));
13710       this->set_is_error();
13711     }
13712   else if (this->type_->interface_type() == NULL)
13713     {
13714       std::string reason;
13715       if (!expr_type->interface_type()->implements_interface(this->type_,
13716                                                              &reason))
13717         {
13718           if (!this->type_->is_error())
13719             {
13720               if (reason.empty())
13721                 this->report_error(_("impossible type assertion: "
13722                                      "type does not implement interface"));
13723               else
13724                 error_at(this->location(),
13725                          ("impossible type assertion: "
13726                           "type does not implement interface (%s)"),
13727                          reason.c_str());
13728             }
13729           this->set_is_error();
13730         }
13731     }
13732 }
13733
13734 // Return a tree for a type guard expression.
13735
13736 tree
13737 Type_guard_expression::do_get_tree(Translate_context* context)
13738 {
13739   Gogo* gogo = context->gogo();
13740   tree expr_tree = this->expr_->get_tree(context);
13741   if (expr_tree == error_mark_node)
13742     return error_mark_node;
13743   Type* expr_type = this->expr_->type();
13744   if ((this->type_->is_unsafe_pointer_type()
13745        && (expr_type->points_to() != NULL
13746            || expr_type->integer_type() != NULL))
13747       || (expr_type->is_unsafe_pointer_type()
13748           && this->type_->points_to() != NULL))
13749     return convert_to_pointer(type_to_tree(this->type_->get_backend(gogo)),
13750                               expr_tree);
13751   else if (expr_type->is_unsafe_pointer_type()
13752            && this->type_->integer_type() != NULL)
13753     return convert_to_integer(type_to_tree(this->type_->get_backend(gogo)),
13754                               expr_tree);
13755   else if (this->type_->interface_type() != NULL)
13756     return Expression::convert_interface_to_interface(context, this->type_,
13757                                                       this->expr_->type(),
13758                                                       expr_tree, true,
13759                                                       this->location());
13760   else
13761     return Expression::convert_for_assignment(context, this->type_,
13762                                               this->expr_->type(), expr_tree,
13763                                               this->location());
13764 }
13765
13766 // Dump ast representation for a type guard expression.
13767
13768 void
13769 Type_guard_expression::do_dump_expression(Ast_dump_context* ast_dump_context)
13770     const
13771 {
13772   this->expr_->dump_expression(ast_dump_context);
13773   ast_dump_context->ostream() <<  ".";
13774   ast_dump_context->dump_type(this->type_);
13775 }
13776
13777 // Make a type guard expression.
13778
13779 Expression*
13780 Expression::make_type_guard(Expression* expr, Type* type,
13781                             Location location)
13782 {
13783   return new Type_guard_expression(expr, type, location);
13784 }
13785
13786 // Class Heap_composite_expression.
13787
13788 // When you take the address of a composite literal, it is allocated
13789 // on the heap.  This class implements that.
13790
13791 class Heap_composite_expression : public Expression
13792 {
13793  public:
13794   Heap_composite_expression(Expression* expr, Location location)
13795     : Expression(EXPRESSION_HEAP_COMPOSITE, location),
13796       expr_(expr)
13797   { }
13798
13799  protected:
13800   int
13801   do_traverse(Traverse* traverse)
13802   { return Expression::traverse(&this->expr_, traverse); }
13803
13804   Type*
13805   do_type()
13806   { return Type::make_pointer_type(this->expr_->type()); }
13807
13808   void
13809   do_determine_type(const Type_context*)
13810   { this->expr_->determine_type_no_context(); }
13811
13812   Expression*
13813   do_copy()
13814   {
13815     return Expression::make_heap_composite(this->expr_->copy(),
13816                                            this->location());
13817   }
13818
13819   tree
13820   do_get_tree(Translate_context*);
13821
13822   // We only export global objects, and the parser does not generate
13823   // this in global scope.
13824   void
13825   do_export(Export*) const
13826   { go_unreachable(); }
13827
13828   void
13829   do_dump_expression(Ast_dump_context*) const;
13830
13831  private:
13832   // The composite literal which is being put on the heap.
13833   Expression* expr_;
13834 };
13835
13836 // Return a tree which allocates a composite literal on the heap.
13837
13838 tree
13839 Heap_composite_expression::do_get_tree(Translate_context* context)
13840 {
13841   tree expr_tree = this->expr_->get_tree(context);
13842   if (expr_tree == error_mark_node)
13843     return error_mark_node;
13844   tree expr_size = TYPE_SIZE_UNIT(TREE_TYPE(expr_tree));
13845   go_assert(TREE_CODE(expr_size) == INTEGER_CST);
13846   tree space = context->gogo()->allocate_memory(this->expr_->type(),
13847                                                 expr_size, this->location());
13848   space = fold_convert(build_pointer_type(TREE_TYPE(expr_tree)), space);
13849   space = save_expr(space);
13850   tree ref = build_fold_indirect_ref_loc(this->location().gcc_location(),
13851                                          space);
13852   TREE_THIS_NOTRAP(ref) = 1;
13853   tree ret = build2(COMPOUND_EXPR, TREE_TYPE(space),
13854                     build2(MODIFY_EXPR, void_type_node, ref, expr_tree),
13855                     space);
13856   SET_EXPR_LOCATION(ret, this->location().gcc_location());
13857   return ret;
13858 }
13859
13860 // Dump ast representation for a heap composite expression.
13861
13862 void
13863 Heap_composite_expression::do_dump_expression(
13864     Ast_dump_context* ast_dump_context) const
13865 {
13866   ast_dump_context->ostream() << "&(";
13867   ast_dump_context->dump_expression(this->expr_);
13868   ast_dump_context->ostream() << ")";
13869 }
13870
13871 // Allocate a composite literal on the heap.
13872
13873 Expression*
13874 Expression::make_heap_composite(Expression* expr, Location location)
13875 {
13876   return new Heap_composite_expression(expr, location);
13877 }
13878
13879 // Class Receive_expression.
13880
13881 // Return the type of a receive expression.
13882
13883 Type*
13884 Receive_expression::do_type()
13885 {
13886   Channel_type* channel_type = this->channel_->type()->channel_type();
13887   if (channel_type == NULL)
13888     return Type::make_error_type();
13889   return channel_type->element_type();
13890 }
13891
13892 // Check types for a receive expression.
13893
13894 void
13895 Receive_expression::do_check_types(Gogo*)
13896 {
13897   Type* type = this->channel_->type();
13898   if (type->is_error())
13899     {
13900       this->set_is_error();
13901       return;
13902     }
13903   if (type->channel_type() == NULL)
13904     {
13905       this->report_error(_("expected channel"));
13906       return;
13907     }
13908   if (!type->channel_type()->may_receive())
13909     {
13910       this->report_error(_("invalid receive on send-only channel"));
13911       return;
13912     }
13913 }
13914
13915 // Get a tree for a receive expression.
13916
13917 tree
13918 Receive_expression::do_get_tree(Translate_context* context)
13919 {
13920   Location loc = this->location();
13921
13922   Channel_type* channel_type = this->channel_->type()->channel_type();
13923   if (channel_type == NULL)
13924     {
13925       go_assert(this->channel_->type()->is_error());
13926       return error_mark_node;
13927     }
13928
13929   Expression* td = Expression::make_type_descriptor(channel_type, loc);
13930   tree td_tree = td->get_tree(context);
13931
13932   Type* element_type = channel_type->element_type();
13933   Btype* element_type_btype = element_type->get_backend(context->gogo());
13934   tree element_type_tree = type_to_tree(element_type_btype);
13935
13936   tree channel = this->channel_->get_tree(context);
13937   if (element_type_tree == error_mark_node || channel == error_mark_node)
13938     return error_mark_node;
13939
13940   return Gogo::receive_from_channel(element_type_tree, td_tree, channel, loc);
13941 }
13942
13943 // Dump ast representation for a receive expression.
13944
13945 void
13946 Receive_expression::do_dump_expression(Ast_dump_context* ast_dump_context) const
13947 {
13948   ast_dump_context->ostream() << " <- " ;
13949   ast_dump_context->dump_expression(channel_);
13950 }
13951
13952 // Make a receive expression.
13953
13954 Receive_expression*
13955 Expression::make_receive(Expression* channel, Location location)
13956 {
13957   return new Receive_expression(channel, location);
13958 }
13959
13960 // An expression which evaluates to a pointer to the type descriptor
13961 // of a type.
13962
13963 class Type_descriptor_expression : public Expression
13964 {
13965  public:
13966   Type_descriptor_expression(Type* type, Location location)
13967     : Expression(EXPRESSION_TYPE_DESCRIPTOR, location),
13968       type_(type)
13969   { }
13970
13971  protected:
13972   Type*
13973   do_type()
13974   { return Type::make_type_descriptor_ptr_type(); }
13975
13976   void
13977   do_determine_type(const Type_context*)
13978   { }
13979
13980   Expression*
13981   do_copy()
13982   { return this; }
13983
13984   tree
13985   do_get_tree(Translate_context* context)
13986   {
13987     return this->type_->type_descriptor_pointer(context->gogo(),
13988                                                 this->location());
13989   }
13990
13991   void
13992   do_dump_expression(Ast_dump_context*) const;
13993
13994  private:
13995   // The type for which this is the descriptor.
13996   Type* type_;
13997 };
13998
13999 // Dump ast representation for a type descriptor expression.
14000
14001 void
14002 Type_descriptor_expression::do_dump_expression(
14003     Ast_dump_context* ast_dump_context) const
14004 {
14005   ast_dump_context->dump_type(this->type_);
14006 }
14007
14008 // Make a type descriptor expression.
14009
14010 Expression*
14011 Expression::make_type_descriptor(Type* type, Location location)
14012 {
14013   return new Type_descriptor_expression(type, location);
14014 }
14015
14016 // An expression which evaluates to some characteristic of a type.
14017 // This is only used to initialize fields of a type descriptor.  Using
14018 // a new expression class is slightly inefficient but gives us a good
14019 // separation between the frontend and the middle-end with regard to
14020 // how types are laid out.
14021
14022 class Type_info_expression : public Expression
14023 {
14024  public:
14025   Type_info_expression(Type* type, Type_info type_info)
14026     : Expression(EXPRESSION_TYPE_INFO, Linemap::predeclared_location()),
14027       type_(type), type_info_(type_info)
14028   { }
14029
14030  protected:
14031   Type*
14032   do_type();
14033
14034   void
14035   do_determine_type(const Type_context*)
14036   { }
14037
14038   Expression*
14039   do_copy()
14040   { return this; }
14041
14042   tree
14043   do_get_tree(Translate_context* context);
14044
14045   void
14046   do_dump_expression(Ast_dump_context*) const;
14047
14048  private:
14049   // The type for which we are getting information.
14050   Type* type_;
14051   // What information we want.
14052   Type_info type_info_;
14053 };
14054
14055 // The type is chosen to match what the type descriptor struct
14056 // expects.
14057
14058 Type*
14059 Type_info_expression::do_type()
14060 {
14061   switch (this->type_info_)
14062     {
14063     case TYPE_INFO_SIZE:
14064       return Type::lookup_integer_type("uintptr");
14065     case TYPE_INFO_ALIGNMENT:
14066     case TYPE_INFO_FIELD_ALIGNMENT:
14067       return Type::lookup_integer_type("uint8");
14068     default:
14069       go_unreachable();
14070     }
14071 }
14072
14073 // Return type information in GENERIC.
14074
14075 tree
14076 Type_info_expression::do_get_tree(Translate_context* context)
14077 {
14078   Btype* btype = this->type_->get_backend(context->gogo());
14079   Gogo* gogo = context->gogo();
14080   size_t val;
14081   switch (this->type_info_)
14082     {
14083     case TYPE_INFO_SIZE:
14084       val = gogo->backend()->type_size(btype);
14085       break;
14086     case TYPE_INFO_ALIGNMENT:
14087       val = gogo->backend()->type_alignment(btype);
14088       break;
14089     case TYPE_INFO_FIELD_ALIGNMENT:
14090       val = gogo->backend()->type_field_alignment(btype);
14091       break;
14092     default:
14093       go_unreachable();
14094     }
14095   tree val_type_tree = type_to_tree(this->type()->get_backend(gogo));
14096   go_assert(val_type_tree != error_mark_node);
14097   return build_int_cstu(val_type_tree, val);
14098 }
14099
14100 // Dump ast representation for a type info expression.
14101
14102 void
14103 Type_info_expression::do_dump_expression(
14104     Ast_dump_context* ast_dump_context) const
14105 {
14106   ast_dump_context->ostream() << "typeinfo(";
14107   ast_dump_context->dump_type(this->type_);
14108   ast_dump_context->ostream() << ",";
14109   ast_dump_context->ostream() <<
14110     (this->type_info_ == TYPE_INFO_ALIGNMENT ? "alignment"
14111     : this->type_info_ == TYPE_INFO_FIELD_ALIGNMENT ? "field alignment"
14112     : this->type_info_ == TYPE_INFO_SIZE ? "size "
14113     : "unknown");
14114   ast_dump_context->ostream() << ")";
14115 }
14116
14117 // Make a type info expression.
14118
14119 Expression*
14120 Expression::make_type_info(Type* type, Type_info type_info)
14121 {
14122   return new Type_info_expression(type, type_info);
14123 }
14124
14125 // An expression which evaluates to the offset of a field within a
14126 // struct.  This, like Type_info_expression, q.v., is only used to
14127 // initialize fields of a type descriptor.
14128
14129 class Struct_field_offset_expression : public Expression
14130 {
14131  public:
14132   Struct_field_offset_expression(Struct_type* type, const Struct_field* field)
14133     : Expression(EXPRESSION_STRUCT_FIELD_OFFSET,
14134                  Linemap::predeclared_location()),
14135       type_(type), field_(field)
14136   { }
14137
14138  protected:
14139   Type*
14140   do_type()
14141   { return Type::lookup_integer_type("uintptr"); }
14142
14143   void
14144   do_determine_type(const Type_context*)
14145   { }
14146
14147   Expression*
14148   do_copy()
14149   { return this; }
14150
14151   tree
14152   do_get_tree(Translate_context* context);
14153
14154   void
14155   do_dump_expression(Ast_dump_context*) const;
14156
14157  private:
14158   // The type of the struct.
14159   Struct_type* type_;
14160   // The field.
14161   const Struct_field* field_;
14162 };
14163
14164 // Return a struct field offset in GENERIC.
14165
14166 tree
14167 Struct_field_offset_expression::do_get_tree(Translate_context* context)
14168 {
14169   tree type_tree = type_to_tree(this->type_->get_backend(context->gogo()));
14170   if (type_tree == error_mark_node)
14171     return error_mark_node;
14172
14173   tree val_type_tree = type_to_tree(this->type()->get_backend(context->gogo()));
14174   go_assert(val_type_tree != error_mark_node);
14175
14176   const Struct_field_list* fields = this->type_->fields();
14177   tree struct_field_tree = TYPE_FIELDS(type_tree);
14178   Struct_field_list::const_iterator p;
14179   for (p = fields->begin();
14180        p != fields->end();
14181        ++p, struct_field_tree = DECL_CHAIN(struct_field_tree))
14182     {
14183       go_assert(struct_field_tree != NULL_TREE);
14184       if (&*p == this->field_)
14185         break;
14186     }
14187   go_assert(&*p == this->field_);
14188
14189   return fold_convert_loc(BUILTINS_LOCATION, val_type_tree,
14190                           byte_position(struct_field_tree));
14191 }
14192
14193 // Dump ast representation for a struct field offset expression.
14194
14195 void
14196 Struct_field_offset_expression::do_dump_expression(
14197     Ast_dump_context* ast_dump_context) const
14198 {
14199   ast_dump_context->ostream() <<  "unsafe.Offsetof(";
14200   ast_dump_context->dump_type(this->type_);
14201   ast_dump_context->ostream() << '.';
14202   ast_dump_context->ostream() <<
14203     Gogo::message_name(this->field_->field_name());
14204   ast_dump_context->ostream() << ")";
14205 }
14206
14207 // Make an expression for a struct field offset.
14208
14209 Expression*
14210 Expression::make_struct_field_offset(Struct_type* type,
14211                                      const Struct_field* field)
14212 {
14213   return new Struct_field_offset_expression(type, field);
14214 }
14215
14216 // An expression which evaluates to a pointer to the map descriptor of
14217 // a map type.
14218
14219 class Map_descriptor_expression : public Expression
14220 {
14221  public:
14222   Map_descriptor_expression(Map_type* type, Location location)
14223     : Expression(EXPRESSION_MAP_DESCRIPTOR, location),
14224       type_(type)
14225   { }
14226
14227  protected:
14228   Type*
14229   do_type()
14230   { return Type::make_pointer_type(Map_type::make_map_descriptor_type()); }
14231
14232   void
14233   do_determine_type(const Type_context*)
14234   { }
14235
14236   Expression*
14237   do_copy()
14238   { return this; }
14239
14240   tree
14241   do_get_tree(Translate_context* context)
14242   {
14243     return this->type_->map_descriptor_pointer(context->gogo(),
14244                                                this->location());
14245   }
14246
14247   void
14248   do_dump_expression(Ast_dump_context*) const;
14249
14250  private:
14251   // The type for which this is the descriptor.
14252   Map_type* type_;
14253 };
14254
14255 // Dump ast representation for a map descriptor expression.
14256
14257 void
14258 Map_descriptor_expression::do_dump_expression(
14259     Ast_dump_context* ast_dump_context) const
14260 {
14261   ast_dump_context->ostream() << "map_descriptor(";
14262   ast_dump_context->dump_type(this->type_);
14263   ast_dump_context->ostream() << ")";
14264 }
14265
14266 // Make a map descriptor expression.
14267
14268 Expression*
14269 Expression::make_map_descriptor(Map_type* type, Location location)
14270 {
14271   return new Map_descriptor_expression(type, location);
14272 }
14273
14274 // An expression which evaluates to the address of an unnamed label.
14275
14276 class Label_addr_expression : public Expression
14277 {
14278  public:
14279   Label_addr_expression(Label* label, Location location)
14280     : Expression(EXPRESSION_LABEL_ADDR, location),
14281       label_(label)
14282   { }
14283
14284  protected:
14285   Type*
14286   do_type()
14287   { return Type::make_pointer_type(Type::make_void_type()); }
14288
14289   void
14290   do_determine_type(const Type_context*)
14291   { }
14292
14293   Expression*
14294   do_copy()
14295   { return new Label_addr_expression(this->label_, this->location()); }
14296
14297   tree
14298   do_get_tree(Translate_context* context)
14299   {
14300     return expr_to_tree(this->label_->get_addr(context, this->location()));
14301   }
14302
14303   void
14304   do_dump_expression(Ast_dump_context* ast_dump_context) const
14305   { ast_dump_context->ostream() << this->label_->name(); }
14306
14307  private:
14308   // The label whose address we are taking.
14309   Label* label_;
14310 };
14311
14312 // Make an expression for the address of an unnamed label.
14313
14314 Expression*
14315 Expression::make_label_addr(Label* label, Location location)
14316 {
14317   return new Label_addr_expression(label, location);
14318 }
14319
14320 // Import an expression.  This comes at the end in order to see the
14321 // various class definitions.
14322
14323 Expression*
14324 Expression::import_expression(Import* imp)
14325 {
14326   int c = imp->peek_char();
14327   if (imp->match_c_string("- ")
14328       || imp->match_c_string("! ")
14329       || imp->match_c_string("^ "))
14330     return Unary_expression::do_import(imp);
14331   else if (c == '(')
14332     return Binary_expression::do_import(imp);
14333   else if (imp->match_c_string("true")
14334            || imp->match_c_string("false"))
14335     return Boolean_expression::do_import(imp);
14336   else if (c == '"')
14337     return String_expression::do_import(imp);
14338   else if (c == '-' || (c >= '0' && c <= '9'))
14339     {
14340       // This handles integers, floats and complex constants.
14341       return Integer_expression::do_import(imp);
14342     }
14343   else if (imp->match_c_string("nil"))
14344     return Nil_expression::do_import(imp);
14345   else if (imp->match_c_string("convert"))
14346     return Type_conversion_expression::do_import(imp);
14347   else
14348     {
14349       error_at(imp->location(), "import error: expected expression");
14350       return Expression::make_error(imp->location());
14351     }
14352 }
14353
14354 // Class Expression_list.
14355
14356 // Traverse the list.
14357
14358 int
14359 Expression_list::traverse(Traverse* traverse)
14360 {
14361   for (Expression_list::iterator p = this->begin();
14362        p != this->end();
14363        ++p)
14364     {
14365       if (*p != NULL)
14366         {
14367           if (Expression::traverse(&*p, traverse) == TRAVERSE_EXIT)
14368             return TRAVERSE_EXIT;
14369         }
14370     }
14371   return TRAVERSE_CONTINUE;
14372 }
14373
14374 // Copy the list.
14375
14376 Expression_list*
14377 Expression_list::copy()
14378 {
14379   Expression_list* ret = new Expression_list();
14380   for (Expression_list::iterator p = this->begin();
14381        p != this->end();
14382        ++p)
14383     {
14384       if (*p == NULL)
14385         ret->push_back(NULL);
14386       else
14387         ret->push_back((*p)->copy());
14388     }
14389   return ret;
14390 }
14391
14392 // Return whether an expression list has an error expression.
14393
14394 bool
14395 Expression_list::contains_error() const
14396 {
14397   for (Expression_list::const_iterator p = this->begin();
14398        p != this->end();
14399        ++p)
14400     if (*p != NULL && (*p)->is_error_expression())
14401       return true;
14402   return false;
14403 }