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       go_assert(TREE_TYPE(field) == TREE_TYPE(rhs_type_descriptor));
 526       elt->value = 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           }
5568         else if (is_comparison)
5569           {
5570             bool b = Binary_expression::compare_integer(op, left_val,
5571                                                         right_val);
5572             ret = Expression::make_cast(Type::lookup_bool_type(),
5573                                         Expression::make_boolean(b, location),
5574                                         location);
5575           }
5576         else
5577           {
5578             mpz_t val;
5579             mpz_init(val);
5580
5581             if (Binary_expression::eval_integer(op, left_type, left_val,
5582                                                 right_type, right_val,
5583                                                 location, val))
5584               {
5585                 go_assert(op != OPERATOR_OROR && op != OPERATOR_ANDAND);
5586                 Type* type;
5587                 if (op == OPERATOR_LSHIFT || op == OPERATOR_RSHIFT)
5588                   type = left_type;
5589                 else if (left_type == NULL)
5590                   type = right_type;
5591                 else if (right_type == NULL)
5592                   type = left_type;
5593                 else if (!left_type->is_abstract()
5594                          && left_type->named_type() != NULL)
5595                   type = left_type;
5596                 else if (!right_type->is_abstract()
5597                          && right_type->named_type() != NULL)
5598                   type = right_type;
5599                 else if (!left_type->is_abstract())
5600                   type = left_type;
5601                 else if (!right_type->is_abstract())
5602                   type = right_type;
5603                 else if (left_type->float_type() != NULL)
5604                   type = left_type;
5605                 else if (right_type->float_type() != NULL)
5606                   type = right_type;
5607                 else if (left_type->complex_type() != NULL)
5608                   type = left_type;
5609                 else if (right_type->complex_type() != NULL)
5610                   type = right_type;
5611                 else
5612                   type = left_type;
5613
5614                 bool is_character = false;
5615                 if (type == NULL)
5616                   {
5617                     Type* t = this->left_->type();
5618                     if (t->integer_type() != NULL
5619                         && t->integer_type()->is_rune())
5620                       is_character = true;
5621                     else if (op != OPERATOR_LSHIFT && op != OPERATOR_RSHIFT)
5622                       {
5623                         t = this->right_->type();
5624                         if (t->integer_type() != NULL
5625                             && t->integer_type()->is_rune())
5626                           is_character = true;
5627                       }
5628                   }
5629
5630                 if (is_character)
5631                   ret = Expression::make_character(&val, type, location);
5632                 else
5633                   ret = Expression::make_integer(&val, type, location);
5634               }
5635
5636             mpz_clear(val);
5637           }
5638
5639         if (ret != NULL)
5640           {
5641             mpz_clear(right_val);
5642             mpz_clear(left_val);
5643             return ret;
5644           }
5645       }
5646     mpz_clear(right_val);
5647     mpz_clear(left_val);
5648   }
5649
5650   // Floating point constant expressions.
5651   {
5652     mpfr_t left_val;
5653     mpfr_init(left_val);
5654     Type* left_type;
5655     mpfr_t right_val;
5656     mpfr_init(right_val);
5657     Type* right_type;
5658     if (left->float_constant_value(left_val, &left_type)
5659         && right->float_constant_value(right_val, &right_type))
5660       {
5661         Expression* ret = NULL;
5662         if (left_type != right_type
5663             && left_type != NULL
5664             && right_type != NULL
5665             && left_type->base() != right_type->base()
5666             && op != OPERATOR_LSHIFT
5667             && op != OPERATOR_RSHIFT)
5668           {
5669             // May be a type error--let it be diagnosed later.
5670           }
5671         else if (is_comparison)
5672           {
5673             bool b = Binary_expression::compare_float(op,
5674                                                       (left_type != NULL
5675                                                        ? left_type
5676                                                        : right_type),
5677                                                       left_val, right_val);
5678             ret = Expression::make_boolean(b, location);
5679           }
5680         else
5681           {
5682             mpfr_t val;
5683             mpfr_init(val);
5684
5685             if (Binary_expression::eval_float(op, left_type, left_val,
5686                                               right_type, right_val, val,
5687                                               location))
5688               {
5689                 go_assert(op != OPERATOR_OROR && op != OPERATOR_ANDAND
5690                            && op != OPERATOR_LSHIFT && op != OPERATOR_RSHIFT);
5691                 Type* type;
5692                 if (left_type == NULL)
5693                   type = right_type;
5694                 else if (right_type == NULL)
5695                   type = left_type;
5696                 else if (!left_type->is_abstract()
5697                          && left_type->named_type() != NULL)
5698                   type = left_type;
5699                 else if (!right_type->is_abstract()
5700                          && right_type->named_type() != NULL)
5701                   type = right_type;
5702                 else if (!left_type->is_abstract())
5703                   type = left_type;
5704                 else if (!right_type->is_abstract())
5705                   type = right_type;
5706                 else if (left_type->float_type() != NULL)
5707                   type = left_type;
5708                 else if (right_type->float_type() != NULL)
5709                   type = right_type;
5710                 else
5711                   type = left_type;
5712                 ret = Expression::make_float(&val, type, location);
5713               }
5714
5715             mpfr_clear(val);
5716           }
5717
5718         if (ret != NULL)
5719           {
5720             mpfr_clear(right_val);
5721             mpfr_clear(left_val);
5722             return ret;
5723           }
5724       }
5725     mpfr_clear(right_val);
5726     mpfr_clear(left_val);
5727   }
5728
5729   // Complex constant expressions.
5730   {
5731     mpfr_t left_real;
5732     mpfr_t left_imag;
5733     mpfr_init(left_real);
5734     mpfr_init(left_imag);
5735     Type* left_type;
5736
5737     mpfr_t right_real;
5738     mpfr_t right_imag;
5739     mpfr_init(right_real);
5740     mpfr_init(right_imag);
5741     Type* right_type;
5742
5743     if (left->complex_constant_value(left_real, left_imag, &left_type)
5744         && right->complex_constant_value(right_real, right_imag, &right_type))
5745       {
5746         Expression* ret = NULL;
5747         if (left_type != right_type
5748             && left_type != NULL
5749             && right_type != NULL
5750             && left_type->base() != right_type->base())
5751           {
5752             // May be a type error--let it be diagnosed later.
5753           }
5754         else if (op == OPERATOR_EQEQ || op == OPERATOR_NOTEQ)
5755           {
5756             bool b = Binary_expression::compare_complex(op,
5757                                                         (left_type != NULL
5758                                                          ? left_type
5759                                                          : right_type),
5760                                                         left_real,
5761                                                         left_imag,
5762                                                         right_real,
5763                                                         right_imag);
5764             ret = Expression::make_boolean(b, location);
5765           }
5766         else
5767           {
5768             mpfr_t real;
5769             mpfr_t imag;
5770             mpfr_init(real);
5771             mpfr_init(imag);
5772
5773             if (Binary_expression::eval_complex(op, left_type,
5774                                                 left_real, left_imag,
5775                                                 right_type,
5776                                                 right_real, right_imag,
5777                                                 real, imag,
5778                                                 location))
5779               {
5780                 go_assert(op != OPERATOR_OROR && op != OPERATOR_ANDAND
5781                            && op != OPERATOR_LSHIFT && op != OPERATOR_RSHIFT);
5782                 Type* type;
5783                 if (left_type == NULL)
5784                   type = right_type;
5785                 else if (right_type == NULL)
5786                   type = left_type;
5787                 else if (!left_type->is_abstract()
5788                          && left_type->named_type() != NULL)
5789                   type = left_type;
5790                 else if (!right_type->is_abstract()
5791                          && right_type->named_type() != NULL)
5792                   type = right_type;
5793                 else if (!left_type->is_abstract())
5794                   type = left_type;
5795                 else if (!right_type->is_abstract())
5796                   type = right_type;
5797                 else if (left_type->complex_type() != NULL)
5798                   type = left_type;
5799                 else if (right_type->complex_type() != NULL)
5800                   type = right_type;
5801                 else
5802                   type = left_type;
5803                 ret = Expression::make_complex(&real, &imag, type,
5804                                                location);
5805               }
5806             mpfr_clear(real);
5807             mpfr_clear(imag);
5808           }
5809
5810         if (ret != NULL)
5811           {
5812             mpfr_clear(left_real);
5813             mpfr_clear(left_imag);
5814             mpfr_clear(right_real);
5815             mpfr_clear(right_imag);
5816             return ret;
5817           }
5818       }
5819
5820     mpfr_clear(left_real);
5821     mpfr_clear(left_imag);
5822     mpfr_clear(right_real);
5823     mpfr_clear(right_imag);
5824   }
5825
5826   // String constant expressions.
5827   if (op == OPERATOR_PLUS
5828       && left->type()->is_string_type()
5829       && right->type()->is_string_type())
5830     {
5831       std::string left_string;
5832       std::string right_string;
5833       if (left->string_constant_value(&left_string)
5834           && right->string_constant_value(&right_string))
5835         return Expression::make_string(left_string + right_string, location);
5836     }
5837
5838   // Special case for shift of a floating point constant.
5839   if (op == OPERATOR_LSHIFT || op == OPERATOR_RSHIFT)
5840     {
5841       mpfr_t left_val;
5842       mpfr_init(left_val);
5843       Type* left_type;
5844       mpz_t right_val;
5845       mpz_init(right_val);
5846       Type* right_type;
5847       if (left->float_constant_value(left_val, &left_type)
5848           && right->integer_constant_value(false, right_val, &right_type)
5849           && mpfr_integer_p(left_val)
5850           && (left_type == NULL
5851               || left_type->is_abstract()
5852               || left_type->integer_type() != NULL))
5853         {
5854           mpz_t left_int;
5855           mpz_init(left_int);
5856           mpfr_get_z(left_int, left_val, GMP_RNDN);
5857
5858           mpz_t val;
5859           mpz_init(val);
5860
5861           Expression* ret = NULL;
5862           if (Binary_expression::eval_integer(op, left_type, left_int,
5863                                               right_type, right_val,
5864                                               location, val))
5865             ret = Expression::make_integer(&val, left_type, location);
5866
5867           mpz_clear(left_int);
5868           mpz_clear(val);
5869
5870           if (ret != NULL)
5871             {
5872               mpfr_clear(left_val);
5873               mpz_clear(right_val);
5874               return ret;
5875             }
5876         }
5877
5878       mpfr_clear(left_val);
5879       mpz_clear(right_val);
5880     }
5881
5882   // Lower struct and array comparisons.
5883   if (op == OPERATOR_EQEQ || op == OPERATOR_NOTEQ)
5884     {
5885       if (left->type()->struct_type() != NULL)
5886         return this->lower_struct_comparison(gogo, inserter);
5887       else if (left->type()->array_type() != NULL
5888                && !left->type()->is_slice_type())
5889         return this->lower_array_comparison(gogo, inserter);
5890     }
5891
5892   return this;
5893 }
5894
5895 // Lower a struct comparison.
5896
5897 Expression*
5898 Binary_expression::lower_struct_comparison(Gogo* gogo,
5899                                            Statement_inserter* inserter)
5900 {
5901   Struct_type* st = this->left_->type()->struct_type();
5902   Struct_type* st2 = this->right_->type()->struct_type();
5903   if (st2 == NULL)
5904     return this;
5905   if (st != st2 && !Type::are_identical(st, st2, false, NULL))
5906     return this;
5907   if (!Type::are_compatible_for_comparison(true, this->left_->type(),
5908                                            this->right_->type(), NULL))
5909     return this;
5910
5911   // See if we can compare using memcmp.  As a heuristic, we use
5912   // memcmp rather than field references and comparisons if there are
5913   // more than two fields.
5914   if (st->compare_is_identity(gogo) && st->total_field_count() > 2)
5915     return this->lower_compare_to_memcmp(gogo, inserter);
5916
5917   Location loc = this->location();
5918
5919   Expression* left = this->left_;
5920   Temporary_statement* left_temp = NULL;
5921   if (left->var_expression() == NULL
5922       && left->temporary_reference_expression() == NULL)
5923     {
5924       left_temp = Statement::make_temporary(left->type(), NULL, loc);
5925       inserter->insert(left_temp);
5926       left = Expression::make_set_and_use_temporary(left_temp, left, loc);
5927     }
5928
5929   Expression* right = this->right_;
5930   Temporary_statement* right_temp = NULL;
5931   if (right->var_expression() == NULL
5932       && right->temporary_reference_expression() == NULL)
5933     {
5934       right_temp = Statement::make_temporary(right->type(), NULL, loc);
5935       inserter->insert(right_temp);
5936       right = Expression::make_set_and_use_temporary(right_temp, right, loc);
5937     }
5938
5939   Expression* ret = Expression::make_boolean(true, loc);
5940   const Struct_field_list* fields = st->fields();
5941   unsigned int field_index = 0;
5942   for (Struct_field_list::const_iterator pf = fields->begin();
5943        pf != fields->end();
5944        ++pf, ++field_index)
5945     {
5946       if (field_index > 0)
5947         {
5948           if (left_temp == NULL)
5949             left = left->copy();
5950           else
5951             left = Expression::make_temporary_reference(left_temp, loc);
5952           if (right_temp == NULL)
5953             right = right->copy();
5954           else
5955             right = Expression::make_temporary_reference(right_temp, loc);
5956         }
5957       Expression* f1 = Expression::make_field_reference(left, field_index,
5958                                                         loc);
5959       Expression* f2 = Expression::make_field_reference(right, field_index,
5960                                                         loc);
5961       Expression* cond = Expression::make_binary(OPERATOR_EQEQ, f1, f2, loc);
5962       ret = Expression::make_binary(OPERATOR_ANDAND, ret, cond, loc);
5963     }
5964
5965   if (this->op_ == OPERATOR_NOTEQ)
5966     ret = Expression::make_unary(OPERATOR_NOT, ret, loc);
5967
5968   return ret;
5969 }
5970
5971 // Lower an array comparison.
5972
5973 Expression*
5974 Binary_expression::lower_array_comparison(Gogo* gogo,
5975                                           Statement_inserter* inserter)
5976 {
5977   Array_type* at = this->left_->type()->array_type();
5978   Array_type* at2 = this->right_->type()->array_type();
5979   if (at2 == NULL)
5980     return this;
5981   if (at != at2 && !Type::are_identical(at, at2, false, NULL))
5982     return this;
5983   if (!Type::are_compatible_for_comparison(true, this->left_->type(),
5984                                            this->right_->type(), NULL))
5985     return this;
5986
5987   // Call memcmp directly if possible.  This may let the middle-end
5988   // optimize the call.
5989   if (at->compare_is_identity(gogo))
5990     return this->lower_compare_to_memcmp(gogo, inserter);
5991
5992   // Call the array comparison function.
5993   Named_object* hash_fn;
5994   Named_object* equal_fn;
5995   at->type_functions(gogo, this->left_->type()->named_type(), NULL, NULL,
5996                      &hash_fn, &equal_fn);
5997
5998   Location loc = this->location();
5999
6000   Expression* func = Expression::make_func_reference(equal_fn, NULL, loc);
6001
6002   Expression_list* args = new Expression_list();
6003   args->push_back(this->operand_address(inserter, this->left_));
6004   args->push_back(this->operand_address(inserter, this->right_));
6005   args->push_back(Expression::make_type_info(at, TYPE_INFO_SIZE));
6006
6007   Expression* ret = Expression::make_call(func, args, false, loc);
6008
6009   if (this->op_ == OPERATOR_NOTEQ)
6010     ret = Expression::make_unary(OPERATOR_NOT, ret, loc);
6011
6012   return ret;
6013 }
6014
6015 // Lower a struct or array comparison to a call to memcmp.
6016
6017 Expression*
6018 Binary_expression::lower_compare_to_memcmp(Gogo*, Statement_inserter* inserter)
6019 {
6020   Location loc = this->location();
6021
6022   Expression* a1 = this->operand_address(inserter, this->left_);
6023   Expression* a2 = this->operand_address(inserter, this->right_);
6024   Expression* len = Expression::make_type_info(this->left_->type(),
6025                                                TYPE_INFO_SIZE);
6026
6027   Expression* call = Runtime::make_call(Runtime::MEMCMP, loc, 3, a1, a2, len);
6028
6029   mpz_t zval;
6030   mpz_init_set_ui(zval, 0);
6031   Expression* zero = Expression::make_integer(&zval, NULL, loc);
6032   mpz_clear(zval);
6033
6034   return Expression::make_binary(this->op_, call, zero, loc);
6035 }
6036
6037 // Return the address of EXPR, cast to unsafe.Pointer.
6038
6039 Expression*
6040 Binary_expression::operand_address(Statement_inserter* inserter,
6041                                    Expression* expr)
6042 {
6043   Location loc = this->location();
6044
6045   if (!expr->is_addressable())
6046     {
6047       Temporary_statement* temp = Statement::make_temporary(expr->type(), NULL,
6048                                                             loc);
6049       inserter->insert(temp);
6050       expr = Expression::make_set_and_use_temporary(temp, expr, loc);
6051     }
6052   expr = Expression::make_unary(OPERATOR_AND, expr, loc);
6053   static_cast<Unary_expression*>(expr)->set_does_not_escape();
6054   Type* void_type = Type::make_void_type();
6055   Type* unsafe_pointer_type = Type::make_pointer_type(void_type);
6056   return Expression::make_cast(unsafe_pointer_type, expr, loc);
6057 }
6058
6059 // Return the integer constant value, if it has one.
6060
6061 bool
6062 Binary_expression::do_integer_constant_value(bool iota_is_constant, mpz_t val,
6063                                              Type** ptype) const
6064 {
6065   mpz_t left_val;
6066   mpz_init(left_val);
6067   Type* left_type;
6068   if (!this->left_->integer_constant_value(iota_is_constant, left_val,
6069                                            &left_type))
6070     {
6071       mpz_clear(left_val);
6072       return false;
6073     }
6074
6075   mpz_t right_val;
6076   mpz_init(right_val);
6077   Type* right_type;
6078   if (!this->right_->integer_constant_value(iota_is_constant, right_val,
6079                                             &right_type))
6080     {
6081       mpz_clear(right_val);
6082       mpz_clear(left_val);
6083       return false;
6084     }
6085
6086   bool ret;
6087   if (left_type != right_type
6088       && left_type != NULL
6089       && right_type != NULL
6090       && left_type->base() != right_type->base()
6091       && this->op_ != OPERATOR_RSHIFT
6092       && this->op_ != OPERATOR_LSHIFT)
6093     ret = false;
6094   else
6095     ret = Binary_expression::eval_integer(this->op_, left_type, left_val,
6096                                           right_type, right_val,
6097                                           this->location(), val);
6098
6099   mpz_clear(right_val);
6100   mpz_clear(left_val);
6101
6102   if (ret)
6103     *ptype = left_type;
6104
6105   return ret;
6106 }
6107
6108 // Return the floating point constant value, if it has one.
6109
6110 bool
6111 Binary_expression::do_float_constant_value(mpfr_t val, Type** ptype) const
6112 {
6113   mpfr_t left_val;
6114   mpfr_init(left_val);
6115   Type* left_type;
6116   if (!this->left_->float_constant_value(left_val, &left_type))
6117     {
6118       mpfr_clear(left_val);
6119       return false;
6120     }
6121
6122   mpfr_t right_val;
6123   mpfr_init(right_val);
6124   Type* right_type;
6125   if (!this->right_->float_constant_value(right_val, &right_type))
6126     {
6127       mpfr_clear(right_val);
6128       mpfr_clear(left_val);
6129       return false;
6130     }
6131
6132   bool ret;
6133   if (left_type != right_type
6134       && left_type != NULL
6135       && right_type != NULL
6136       && left_type->base() != right_type->base())
6137     ret = false;
6138   else
6139     ret = Binary_expression::eval_float(this->op_, left_type, left_val,
6140                                         right_type, right_val,
6141                                         val, this->location());
6142
6143   mpfr_clear(left_val);
6144   mpfr_clear(right_val);
6145
6146   if (ret)
6147     *ptype = left_type;
6148
6149   return ret;
6150 }
6151
6152 // Return the complex constant value, if it has one.
6153
6154 bool
6155 Binary_expression::do_complex_constant_value(mpfr_t real, mpfr_t imag,
6156                                              Type** ptype) const
6157 {
6158   mpfr_t left_real;
6159   mpfr_t left_imag;
6160   mpfr_init(left_real);
6161   mpfr_init(left_imag);
6162   Type* left_type;
6163   if (!this->left_->complex_constant_value(left_real, left_imag, &left_type))
6164     {
6165       mpfr_clear(left_real);
6166       mpfr_clear(left_imag);
6167       return false;
6168     }
6169
6170   mpfr_t right_real;
6171   mpfr_t right_imag;
6172   mpfr_init(right_real);
6173   mpfr_init(right_imag);
6174   Type* right_type;
6175   if (!this->right_->complex_constant_value(right_real, right_imag,
6176                                             &right_type))
6177     {
6178       mpfr_clear(left_real);
6179       mpfr_clear(left_imag);
6180       mpfr_clear(right_real);
6181       mpfr_clear(right_imag);
6182       return false;
6183     }
6184
6185   bool ret;
6186   if (left_type != right_type
6187       && left_type != NULL
6188       && right_type != NULL
6189       && left_type->base() != right_type->base())
6190     ret = false;
6191   else
6192     ret = Binary_expression::eval_complex(this->op_, left_type,
6193                                           left_real, left_imag,
6194                                           right_type,
6195                                           right_real, right_imag,
6196                                           real, imag,
6197                                           this->location());
6198   mpfr_clear(left_real);
6199   mpfr_clear(left_imag);
6200   mpfr_clear(right_real);
6201   mpfr_clear(right_imag);
6202
6203   if (ret)
6204     *ptype = left_type;
6205
6206   return ret;
6207 }
6208
6209 // Note that the value is being discarded.
6210
6211 void
6212 Binary_expression::do_discarding_value()
6213 {
6214   if (this->op_ == OPERATOR_OROR || this->op_ == OPERATOR_ANDAND)
6215     this->right_->discarding_value();
6216   else
6217     this->unused_value_error();
6218 }
6219
6220 // Get type.
6221
6222 Type*
6223 Binary_expression::do_type()
6224 {
6225   if (this->classification() == EXPRESSION_ERROR)
6226     return Type::make_error_type();
6227
6228   switch (this->op_)
6229     {
6230     case OPERATOR_OROR:
6231     case OPERATOR_ANDAND:
6232     case OPERATOR_EQEQ:
6233     case OPERATOR_NOTEQ:
6234     case OPERATOR_LT:
6235     case OPERATOR_LE:
6236     case OPERATOR_GT:
6237     case OPERATOR_GE:
6238       return Type::lookup_bool_type();
6239
6240     case OPERATOR_PLUS:
6241     case OPERATOR_MINUS:
6242     case OPERATOR_OR:
6243     case OPERATOR_XOR:
6244     case OPERATOR_MULT:
6245     case OPERATOR_DIV:
6246     case OPERATOR_MOD:
6247     case OPERATOR_AND:
6248     case OPERATOR_BITCLEAR:
6249       {
6250         Type* left_type = this->left_->type();
6251         Type* right_type = this->right_->type();
6252         if (left_type->is_error())
6253           return left_type;
6254         else if (right_type->is_error())
6255           return right_type;
6256         else if (!Type::are_compatible_for_binop(left_type, right_type))
6257           {
6258             this->report_error(_("incompatible types in binary expression"));
6259             return Type::make_error_type();
6260           }
6261         else if (!left_type->is_abstract() && left_type->named_type() != NULL)
6262           return left_type;
6263         else if (!right_type->is_abstract() && right_type->named_type() != NULL)
6264           return right_type;
6265         else if (!left_type->is_abstract())
6266           return left_type;
6267         else if (!right_type->is_abstract())
6268           return right_type;
6269         else if (left_type->complex_type() != NULL)
6270           return left_type;
6271         else if (right_type->complex_type() != NULL)
6272           return right_type;
6273         else if (left_type->float_type() != NULL)
6274           return left_type;
6275         else if (right_type->float_type() != NULL)
6276           return right_type;
6277         else if (left_type->integer_type() != NULL
6278                  && left_type->integer_type()->is_rune())
6279           return left_type;
6280         else if (right_type->integer_type() != NULL
6281                  && right_type->integer_type()->is_rune())
6282           return right_type;
6283         else
6284           return left_type;
6285       }
6286
6287     case OPERATOR_LSHIFT:
6288     case OPERATOR_RSHIFT:
6289       return this->left_->type();
6290
6291     default:
6292       go_unreachable();
6293     }
6294 }
6295
6296 // Set type for a binary expression.
6297
6298 void
6299 Binary_expression::do_determine_type(const Type_context* context)
6300 {
6301   Type* tleft = this->left_->type();
6302   Type* tright = this->right_->type();
6303
6304   // Both sides should have the same type, except for the shift
6305   // operations.  For a comparison, we should ignore the incoming
6306   // type.
6307
6308   bool is_shift_op = (this->op_ == OPERATOR_LSHIFT
6309                       || this->op_ == OPERATOR_RSHIFT);
6310
6311   bool is_comparison = (this->op_ == OPERATOR_EQEQ
6312                         || this->op_ == OPERATOR_NOTEQ
6313                         || this->op_ == OPERATOR_LT
6314                         || this->op_ == OPERATOR_LE
6315                         || this->op_ == OPERATOR_GT
6316                         || this->op_ == OPERATOR_GE);
6317
6318   Type_context subcontext(*context);
6319
6320   if (is_comparison)
6321     {
6322       // In a comparison, the context does not determine the types of
6323       // the operands.
6324       subcontext.type = NULL;
6325     }
6326
6327   // Set the context for the left hand operand.
6328   if (is_shift_op)
6329     {
6330       // The right hand operand of a shift plays no role in
6331       // determining the type of the left hand operand.
6332     }
6333   else if (!tleft->is_abstract())
6334     subcontext.type = tleft;
6335   else if (!tright->is_abstract())
6336     subcontext.type = tright;
6337   else if (subcontext.type == NULL)
6338     {
6339       if ((tleft->integer_type() != NULL && tright->integer_type() != NULL)
6340           || (tleft->float_type() != NULL && tright->float_type() != NULL)
6341           || (tleft->complex_type() != NULL && tright->complex_type() != NULL))
6342         {
6343           // Both sides have an abstract integer, abstract float, or
6344           // abstract complex type.  Just let CONTEXT determine
6345           // whether they may remain abstract or not.
6346         }
6347       else if (tleft->complex_type() != NULL)
6348         subcontext.type = tleft;
6349       else if (tright->complex_type() != NULL)
6350         subcontext.type = tright;
6351       else if (tleft->float_type() != NULL)
6352         subcontext.type = tleft;
6353       else if (tright->float_type() != NULL)
6354         subcontext.type = tright;
6355       else
6356         subcontext.type = tleft;
6357
6358       if (subcontext.type != NULL && !context->may_be_abstract)
6359         subcontext.type = subcontext.type->make_non_abstract_type();
6360     }
6361
6362   this->left_->determine_type(&subcontext);
6363
6364   if (is_shift_op)
6365     {
6366       // We may have inherited an unusable type for the shift operand.
6367       // Give a useful error if that happened.
6368       if (tleft->is_abstract()
6369           && subcontext.type != NULL
6370           && (this->left_->type()->integer_type() == NULL
6371               || (subcontext.type->integer_type() == NULL
6372                   && subcontext.type->float_type() == NULL
6373                   && subcontext.type->complex_type() == NULL)))
6374         this->report_error(("invalid context-determined non-integer type "
6375                             "for shift operand"));
6376
6377       // The context for the right hand operand is the same as for the
6378       // left hand operand, except for a shift operator.
6379       subcontext.type = Type::lookup_integer_type("uint");
6380       subcontext.may_be_abstract = false;
6381     }
6382
6383   this->right_->determine_type(&subcontext);
6384 }
6385
6386 // Report an error if the binary operator OP does not support TYPE.
6387 // OTYPE is the type of the other operand.  Return whether the
6388 // operation is OK.  This should not be used for shift.
6389
6390 bool
6391 Binary_expression::check_operator_type(Operator op, Type* type, Type* otype,
6392                                        Location location)
6393 {
6394   switch (op)
6395     {
6396     case OPERATOR_OROR:
6397     case OPERATOR_ANDAND:
6398       if (!type->is_boolean_type())
6399         {
6400           error_at(location, "expected boolean type");
6401           return false;
6402         }
6403       break;
6404
6405     case OPERATOR_EQEQ:
6406     case OPERATOR_NOTEQ:
6407       {
6408         std::string reason;
6409         if (!Type::are_compatible_for_comparison(true, type, otype, &reason))
6410           {
6411             error_at(location, "%s", reason.c_str());
6412             return false;
6413           }
6414       }
6415       break;
6416
6417     case OPERATOR_LT:
6418     case OPERATOR_LE:
6419     case OPERATOR_GT:
6420     case OPERATOR_GE:
6421       {
6422         std::string reason;
6423         if (!Type::are_compatible_for_comparison(false, type, otype, &reason))
6424           {
6425             error_at(location, "%s", reason.c_str());
6426             return false;
6427           }
6428       }
6429       break;
6430
6431     case OPERATOR_PLUS:
6432     case OPERATOR_PLUSEQ:
6433       if (type->integer_type() == NULL
6434           && type->float_type() == NULL
6435           && type->complex_type() == NULL
6436           && !type->is_string_type())
6437         {
6438           error_at(location,
6439                    "expected integer, floating, complex, or string type");
6440           return false;
6441         }
6442       break;
6443
6444     case OPERATOR_MINUS:
6445     case OPERATOR_MINUSEQ:
6446     case OPERATOR_MULT:
6447     case OPERATOR_MULTEQ:
6448     case OPERATOR_DIV:
6449     case OPERATOR_DIVEQ:
6450       if (type->integer_type() == NULL
6451           && type->float_type() == NULL
6452           && type->complex_type() == NULL)
6453         {
6454           error_at(location, "expected integer, floating, or complex type");
6455           return false;
6456         }
6457       break;
6458
6459     case OPERATOR_MOD:
6460     case OPERATOR_MODEQ:
6461     case OPERATOR_OR:
6462     case OPERATOR_OREQ:
6463     case OPERATOR_AND:
6464     case OPERATOR_ANDEQ:
6465     case OPERATOR_XOR:
6466     case OPERATOR_XOREQ:
6467     case OPERATOR_BITCLEAR:
6468     case OPERATOR_BITCLEAREQ:
6469       if (type->integer_type() == NULL)
6470         {
6471           error_at(location, "expected integer type");
6472           return false;
6473         }
6474       break;
6475
6476     default:
6477       go_unreachable();
6478     }
6479
6480   return true;
6481 }
6482
6483 // Check types.
6484
6485 void
6486 Binary_expression::do_check_types(Gogo*)
6487 {
6488   if (this->classification() == EXPRESSION_ERROR)
6489     return;
6490
6491   Type* left_type = this->left_->type();
6492   Type* right_type = this->right_->type();
6493   if (left_type->is_error() || right_type->is_error())
6494     {
6495       this->set_is_error();
6496       return;
6497     }
6498
6499   if (this->op_ == OPERATOR_EQEQ
6500       || this->op_ == OPERATOR_NOTEQ
6501       || this->op_ == OPERATOR_LT
6502       || this->op_ == OPERATOR_LE
6503       || this->op_ == OPERATOR_GT
6504       || this->op_ == OPERATOR_GE)
6505     {
6506       if (!Type::are_assignable(left_type, right_type, NULL)
6507           && !Type::are_assignable(right_type, left_type, NULL))
6508         {
6509           this->report_error(_("incompatible types in binary expression"));
6510           return;
6511         }
6512       if (!Binary_expression::check_operator_type(this->op_, left_type,
6513                                                   right_type,
6514                                                   this->location())
6515           || !Binary_expression::check_operator_type(this->op_, right_type,
6516                                                      left_type,
6517                                                      this->location()))
6518         {
6519           this->set_is_error();
6520           return;
6521         }
6522     }
6523   else if (this->op_ != OPERATOR_LSHIFT && this->op_ != OPERATOR_RSHIFT)
6524     {
6525       if (!Type::are_compatible_for_binop(left_type, right_type))
6526         {
6527           this->report_error(_("incompatible types in binary expression"));
6528           return;
6529         }
6530       if (!Binary_expression::check_operator_type(this->op_, left_type,
6531                                                   right_type,
6532                                                   this->location()))
6533         {
6534           this->set_is_error();
6535           return;
6536         }
6537     }
6538   else
6539     {
6540       if (left_type->integer_type() == NULL)
6541         this->report_error(_("shift of non-integer operand"));
6542
6543       if (!right_type->is_abstract()
6544           && (right_type->integer_type() == NULL
6545               || !right_type->integer_type()->is_unsigned()))
6546         this->report_error(_("shift count not unsigned integer"));
6547       else
6548         {
6549           mpz_t val;
6550           mpz_init(val);
6551           Type* type;
6552           if (this->right_->integer_constant_value(true, val, &type))
6553             {
6554               if (mpz_sgn(val) < 0)
6555                 {
6556                   this->report_error(_("negative shift count"));
6557                   mpz_set_ui(val, 0);
6558                   Location rloc = this->right_->location();
6559                   this->right_ = Expression::make_integer(&val, right_type,
6560                                                           rloc);
6561                 }
6562             }
6563           mpz_clear(val);
6564         }
6565     }
6566 }
6567
6568 // Get a tree for a binary expression.
6569
6570 tree
6571 Binary_expression::do_get_tree(Translate_context* context)
6572 {
6573   tree left = this->left_->get_tree(context);
6574   tree right = this->right_->get_tree(context);
6575
6576   if (left == error_mark_node || right == error_mark_node)
6577     return error_mark_node;
6578
6579   enum tree_code code;
6580   bool use_left_type = true;
6581   bool is_shift_op = false;
6582   switch (this->op_)
6583     {
6584     case OPERATOR_EQEQ:
6585     case OPERATOR_NOTEQ:
6586     case OPERATOR_LT:
6587     case OPERATOR_LE:
6588     case OPERATOR_GT:
6589     case OPERATOR_GE:
6590       return Expression::comparison_tree(context, this->op_,
6591                                          this->left_->type(), left,
6592                                          this->right_->type(), right,
6593                                          this->location());
6594
6595     case OPERATOR_OROR:
6596       code = TRUTH_ORIF_EXPR;
6597       use_left_type = false;
6598       break;
6599     case OPERATOR_ANDAND:
6600       code = TRUTH_ANDIF_EXPR;
6601       use_left_type = false;
6602       break;
6603     case OPERATOR_PLUS:
6604       code = PLUS_EXPR;
6605       break;
6606     case OPERATOR_MINUS:
6607       code = MINUS_EXPR;
6608       break;
6609     case OPERATOR_OR:
6610       code = BIT_IOR_EXPR;
6611       break;
6612     case OPERATOR_XOR:
6613       code = BIT_XOR_EXPR;
6614       break;
6615     case OPERATOR_MULT:
6616       code = MULT_EXPR;
6617       break;
6618     case OPERATOR_DIV:
6619       {
6620         Type *t = this->left_->type();
6621         if (t->float_type() != NULL || t->complex_type() != NULL)
6622           code = RDIV_EXPR;
6623         else
6624           code = TRUNC_DIV_EXPR;
6625       }
6626       break;
6627     case OPERATOR_MOD:
6628       code = TRUNC_MOD_EXPR;
6629       break;
6630     case OPERATOR_LSHIFT:
6631       code = LSHIFT_EXPR;
6632       is_shift_op = true;
6633       break;
6634     case OPERATOR_RSHIFT:
6635       code = RSHIFT_EXPR;
6636       is_shift_op = true;
6637       break;
6638     case OPERATOR_AND:
6639       code = BIT_AND_EXPR;
6640       break;
6641     case OPERATOR_BITCLEAR:
6642       right = fold_build1(BIT_NOT_EXPR, TREE_TYPE(right), right);
6643       code = BIT_AND_EXPR;
6644       break;
6645     default:
6646       go_unreachable();
6647     }
6648
6649   tree type = use_left_type ? TREE_TYPE(left) : TREE_TYPE(right);
6650
6651   if (this->left_->type()->is_string_type())
6652     {
6653       go_assert(this->op_ == OPERATOR_PLUS);
6654       Type* st = Type::make_string_type();
6655       tree string_type = type_to_tree(st->get_backend(context->gogo()));
6656       static tree string_plus_decl;
6657       return Gogo::call_builtin(&string_plus_decl,
6658                                 this->location(),
6659                                 "__go_string_plus",
6660                                 2,
6661                                 string_type,
6662                                 string_type,
6663                                 left,
6664                                 string_type,
6665                                 right);
6666     }
6667
6668   tree compute_type = excess_precision_type(type);
6669   if (compute_type != NULL_TREE)
6670     {
6671       left = ::convert(compute_type, left);
6672       right = ::convert(compute_type, right);
6673     }
6674
6675   tree eval_saved = NULL_TREE;
6676   if (is_shift_op)
6677     {
6678       // Make sure the values are evaluated.
6679       if (!DECL_P(left) && TREE_SIDE_EFFECTS(left))
6680         {
6681           left = save_expr(left);
6682           eval_saved = left;
6683         }
6684       if (!DECL_P(right) && TREE_SIDE_EFFECTS(right))
6685         {
6686           right = save_expr(right);
6687           if (eval_saved == NULL_TREE)
6688             eval_saved = right;
6689           else
6690             eval_saved = fold_build2_loc(this->location().gcc_location(),
6691                                          COMPOUND_EXPR,
6692                                          void_type_node, eval_saved, right);
6693         }
6694     }
6695
6696   tree ret = fold_build2_loc(this->location().gcc_location(),
6697                              code,
6698                              compute_type != NULL_TREE ? compute_type : type,
6699                              left, right);
6700
6701   if (compute_type != NULL_TREE)
6702     ret = ::convert(type, ret);
6703
6704   // In Go, a shift larger than the size of the type is well-defined.
6705   // This is not true in GENERIC, so we need to insert a conditional.
6706   if (is_shift_op)
6707     {
6708       go_assert(INTEGRAL_TYPE_P(TREE_TYPE(left)));
6709       go_assert(this->left_->type()->integer_type() != NULL);
6710       int bits = TYPE_PRECISION(TREE_TYPE(left));
6711
6712       tree compare = fold_build2(LT_EXPR, boolean_type_node, right,
6713                                  build_int_cst_type(TREE_TYPE(right), bits));
6714
6715       tree overflow_result = fold_convert_loc(this->location().gcc_location(),
6716                                               TREE_TYPE(left),
6717                                               integer_zero_node);
6718       if (this->op_ == OPERATOR_RSHIFT
6719           && !this->left_->type()->integer_type()->is_unsigned())
6720         {
6721           tree neg =
6722             fold_build2_loc(this->location().gcc_location(), LT_EXPR,
6723                             boolean_type_node, left,
6724                             fold_convert_loc(this->location().gcc_location(),
6725                                              TREE_TYPE(left),
6726                                              integer_zero_node));
6727           tree neg_one =
6728             fold_build2_loc(this->location().gcc_location(),
6729                             MINUS_EXPR, TREE_TYPE(left),
6730                             fold_convert_loc(this->location().gcc_location(),
6731                                              TREE_TYPE(left),
6732                                              integer_zero_node),
6733                             fold_convert_loc(this->location().gcc_location(),
6734                                              TREE_TYPE(left),
6735                                              integer_one_node));
6736           overflow_result =
6737             fold_build3_loc(this->location().gcc_location(), COND_EXPR,
6738                             TREE_TYPE(left), neg, neg_one,
6739                             overflow_result);
6740         }
6741
6742       ret = fold_build3_loc(this->location().gcc_location(), COND_EXPR,
6743                             TREE_TYPE(left), compare, ret, overflow_result);
6744
6745       if (eval_saved != NULL_TREE)
6746         ret = fold_build2_loc(this->location().gcc_location(), COMPOUND_EXPR,
6747                               TREE_TYPE(ret), eval_saved, ret);
6748     }
6749
6750   return ret;
6751 }
6752
6753 // Export a binary expression.
6754
6755 void
6756 Binary_expression::do_export(Export* exp) const
6757 {
6758   exp->write_c_string("(");
6759   this->left_->export_expression(exp);
6760   switch (this->op_)
6761     {
6762     case OPERATOR_OROR:
6763       exp->write_c_string(" || ");
6764       break;
6765     case OPERATOR_ANDAND:
6766       exp->write_c_string(" && ");
6767       break;
6768     case OPERATOR_EQEQ:
6769       exp->write_c_string(" == ");
6770       break;
6771     case OPERATOR_NOTEQ:
6772       exp->write_c_string(" != ");
6773       break;
6774     case OPERATOR_LT:
6775       exp->write_c_string(" < ");
6776       break;
6777     case OPERATOR_LE:
6778       exp->write_c_string(" <= ");
6779       break;
6780     case OPERATOR_GT:
6781       exp->write_c_string(" > ");
6782       break;
6783     case OPERATOR_GE:
6784       exp->write_c_string(" >= ");
6785       break;
6786     case OPERATOR_PLUS:
6787       exp->write_c_string(" + ");
6788       break;
6789     case OPERATOR_MINUS:
6790       exp->write_c_string(" - ");
6791       break;
6792     case OPERATOR_OR:
6793       exp->write_c_string(" | ");
6794       break;
6795     case OPERATOR_XOR:
6796       exp->write_c_string(" ^ ");
6797       break;
6798     case OPERATOR_MULT:
6799       exp->write_c_string(" * ");
6800       break;
6801     case OPERATOR_DIV:
6802       exp->write_c_string(" / ");
6803       break;
6804     case OPERATOR_MOD:
6805       exp->write_c_string(" % ");
6806       break;
6807     case OPERATOR_LSHIFT:
6808       exp->write_c_string(" << ");
6809       break;
6810     case OPERATOR_RSHIFT:
6811       exp->write_c_string(" >> ");
6812       break;
6813     case OPERATOR_AND:
6814       exp->write_c_string(" & ");
6815       break;
6816     case OPERATOR_BITCLEAR:
6817       exp->write_c_string(" &^ ");
6818       break;
6819     default:
6820       go_unreachable();
6821     }
6822   this->right_->export_expression(exp);
6823   exp->write_c_string(")");
6824 }
6825
6826 // Import a binary expression.
6827
6828 Expression*
6829 Binary_expression::do_import(Import* imp)
6830 {
6831   imp->require_c_string("(");
6832
6833   Expression* left = Expression::import_expression(imp);
6834
6835   Operator op;
6836   if (imp->match_c_string(" || "))
6837     {
6838       op = OPERATOR_OROR;
6839       imp->advance(4);
6840     }
6841   else if (imp->match_c_string(" && "))
6842     {
6843       op = OPERATOR_ANDAND;
6844       imp->advance(4);
6845     }
6846   else if (imp->match_c_string(" == "))
6847     {
6848       op = OPERATOR_EQEQ;
6849       imp->advance(4);
6850     }
6851   else if (imp->match_c_string(" != "))
6852     {
6853       op = OPERATOR_NOTEQ;
6854       imp->advance(4);
6855     }
6856   else if (imp->match_c_string(" < "))
6857     {
6858       op = OPERATOR_LT;
6859       imp->advance(3);
6860     }
6861   else if (imp->match_c_string(" <= "))
6862     {
6863       op = OPERATOR_LE;
6864       imp->advance(4);
6865     }
6866   else if (imp->match_c_string(" > "))
6867     {
6868       op = OPERATOR_GT;
6869       imp->advance(3);
6870     }
6871   else if (imp->match_c_string(" >= "))
6872     {
6873       op = OPERATOR_GE;
6874       imp->advance(4);
6875     }
6876   else if (imp->match_c_string(" + "))
6877     {
6878       op = OPERATOR_PLUS;
6879       imp->advance(3);
6880     }
6881   else if (imp->match_c_string(" - "))
6882     {
6883       op = OPERATOR_MINUS;
6884       imp->advance(3);
6885     }
6886   else if (imp->match_c_string(" | "))
6887     {
6888       op = OPERATOR_OR;
6889       imp->advance(3);
6890     }
6891   else if (imp->match_c_string(" ^ "))
6892     {
6893       op = OPERATOR_XOR;
6894       imp->advance(3);
6895     }
6896   else if (imp->match_c_string(" * "))
6897     {
6898       op = OPERATOR_MULT;
6899       imp->advance(3);
6900     }
6901   else if (imp->match_c_string(" / "))
6902     {
6903       op = OPERATOR_DIV;
6904       imp->advance(3);
6905     }
6906   else if (imp->match_c_string(" % "))
6907     {
6908       op = OPERATOR_MOD;
6909       imp->advance(3);
6910     }
6911   else if (imp->match_c_string(" << "))
6912     {
6913       op = OPERATOR_LSHIFT;
6914       imp->advance(4);
6915     }
6916   else if (imp->match_c_string(" >> "))
6917     {
6918       op = OPERATOR_RSHIFT;
6919       imp->advance(4);
6920     }
6921   else if (imp->match_c_string(" & "))
6922     {
6923       op = OPERATOR_AND;
6924       imp->advance(3);
6925     }
6926   else if (imp->match_c_string(" &^ "))
6927     {
6928       op = OPERATOR_BITCLEAR;
6929       imp->advance(4);
6930     }
6931   else
6932     {
6933       error_at(imp->location(), "unrecognized binary operator");
6934       return Expression::make_error(imp->location());
6935     }
6936
6937   Expression* right = Expression::import_expression(imp);
6938
6939   imp->require_c_string(")");
6940
6941   return Expression::make_binary(op, left, right, imp->location());
6942 }
6943
6944 // Dump ast representation of a binary expression.
6945
6946 void
6947 Binary_expression::do_dump_expression(Ast_dump_context* ast_dump_context) const
6948 {
6949   ast_dump_context->ostream() << "(";
6950   ast_dump_context->dump_expression(this->left_);
6951   ast_dump_context->ostream() << " ";
6952   ast_dump_context->dump_operator(this->op_);
6953   ast_dump_context->ostream() << " ";
6954   ast_dump_context->dump_expression(this->right_);
6955   ast_dump_context->ostream() << ") ";
6956 }
6957
6958 // Make a binary expression.
6959
6960 Expression*
6961 Expression::make_binary(Operator op, Expression* left, Expression* right,
6962                         Location location)
6963 {
6964   return new Binary_expression(op, left, right, location);
6965 }
6966
6967 // Implement a comparison.
6968
6969 tree
6970 Expression::comparison_tree(Translate_context* context, Operator op,
6971                             Type* left_type, tree left_tree,
6972                             Type* right_type, tree right_tree,
6973                             Location location)
6974 {
6975   enum tree_code code;
6976   switch (op)
6977     {
6978     case OPERATOR_EQEQ:
6979       code = EQ_EXPR;
6980       break;
6981     case OPERATOR_NOTEQ:
6982       code = NE_EXPR;
6983       break;
6984     case OPERATOR_LT:
6985       code = LT_EXPR;
6986       break;
6987     case OPERATOR_LE:
6988       code = LE_EXPR;
6989       break;
6990     case OPERATOR_GT:
6991       code = GT_EXPR;
6992       break;
6993     case OPERATOR_GE:
6994       code = GE_EXPR;
6995       break;
6996     default:
6997       go_unreachable();
6998     }
6999
7000   if (left_type->is_string_type() && right_type->is_string_type())
7001     {
7002       Type* st = Type::make_string_type();
7003       tree string_type = type_to_tree(st->get_backend(context->gogo()));
7004       static tree string_compare_decl;
7005       left_tree = Gogo::call_builtin(&string_compare_decl,
7006                                      location,
7007                                      "__go_strcmp",
7008                                      2,
7009                                      integer_type_node,
7010                                      string_type,
7011                                      left_tree,
7012                                      string_type,
7013                                      right_tree);
7014       right_tree = build_int_cst_type(integer_type_node, 0);
7015     }
7016   else if ((left_type->interface_type() != NULL
7017             && right_type->interface_type() == NULL
7018             && !right_type->is_nil_type())
7019            || (left_type->interface_type() == NULL
7020                && !left_type->is_nil_type()
7021                && right_type->interface_type() != NULL))
7022     {
7023       // Comparing an interface value to a non-interface value.
7024       if (left_type->interface_type() == NULL)
7025         {
7026           std::swap(left_type, right_type);
7027           std::swap(left_tree, right_tree);
7028         }
7029
7030       // The right operand is not an interface.  We need to take its
7031       // address if it is not a pointer.
7032       tree make_tmp;
7033       tree arg;
7034       if (right_type->points_to() != NULL)
7035         {
7036           make_tmp = NULL_TREE;
7037           arg = right_tree;
7038         }
7039       else if (TREE_ADDRESSABLE(TREE_TYPE(right_tree)) || DECL_P(right_tree))
7040         {
7041           make_tmp = NULL_TREE;
7042           arg = build_fold_addr_expr_loc(location.gcc_location(), right_tree);
7043           if (DECL_P(right_tree))
7044             TREE_ADDRESSABLE(right_tree) = 1;
7045         }
7046       else
7047         {
7048           tree tmp = create_tmp_var(TREE_TYPE(right_tree),
7049                                     get_name(right_tree));
7050           DECL_IGNORED_P(tmp) = 0;
7051           DECL_INITIAL(tmp) = right_tree;
7052           TREE_ADDRESSABLE(tmp) = 1;
7053           make_tmp = build1(DECL_EXPR, void_type_node, tmp);
7054           SET_EXPR_LOCATION(make_tmp, location.gcc_location());
7055           arg = build_fold_addr_expr_loc(location.gcc_location(), tmp);
7056         }
7057       arg = fold_convert_loc(location.gcc_location(), ptr_type_node, arg);
7058
7059       tree descriptor = right_type->type_descriptor_pointer(context->gogo(),
7060                                                             location);
7061
7062       if (left_type->interface_type()->is_empty())
7063         {
7064           static tree empty_interface_value_compare_decl;
7065           left_tree = Gogo::call_builtin(&empty_interface_value_compare_decl,
7066                                          location,
7067                                          "__go_empty_interface_value_compare",
7068                                          3,
7069                                          integer_type_node,
7070                                          TREE_TYPE(left_tree),
7071                                          left_tree,
7072                                          TREE_TYPE(descriptor),
7073                                          descriptor,
7074                                          ptr_type_node,
7075                                          arg);
7076           if (left_tree == error_mark_node)
7077             return error_mark_node;
7078           // This can panic if the type is not comparable.
7079           TREE_NOTHROW(empty_interface_value_compare_decl) = 0;
7080         }
7081       else
7082         {
7083           static tree interface_value_compare_decl;
7084           left_tree = Gogo::call_builtin(&interface_value_compare_decl,
7085                                          location,
7086                                          "__go_interface_value_compare",
7087                                          3,
7088                                          integer_type_node,
7089                                          TREE_TYPE(left_tree),
7090                                          left_tree,
7091                                          TREE_TYPE(descriptor),
7092                                          descriptor,
7093                                          ptr_type_node,
7094                                          arg);
7095           if (left_tree == error_mark_node)
7096             return error_mark_node;
7097           // This can panic if the type is not comparable.
7098           TREE_NOTHROW(interface_value_compare_decl) = 0;
7099         }
7100       right_tree = build_int_cst_type(integer_type_node, 0);
7101
7102       if (make_tmp != NULL_TREE)
7103         left_tree = build2(COMPOUND_EXPR, TREE_TYPE(left_tree), make_tmp,
7104                            left_tree);
7105     }
7106   else if (left_type->interface_type() != NULL
7107            && right_type->interface_type() != NULL)
7108     {
7109       if (left_type->interface_type()->is_empty()
7110           && right_type->interface_type()->is_empty())
7111         {
7112           static tree empty_interface_compare_decl;
7113           left_tree = Gogo::call_builtin(&empty_interface_compare_decl,
7114                                          location,
7115                                          "__go_empty_interface_compare",
7116                                          2,
7117                                          integer_type_node,
7118                                          TREE_TYPE(left_tree),
7119                                          left_tree,
7120                                          TREE_TYPE(right_tree),
7121                                          right_tree);
7122           if (left_tree == error_mark_node)
7123             return error_mark_node;
7124           // This can panic if the type is uncomparable.
7125           TREE_NOTHROW(empty_interface_compare_decl) = 0;
7126         }
7127       else if (!left_type->interface_type()->is_empty()
7128                && !right_type->interface_type()->is_empty())
7129         {
7130           static tree interface_compare_decl;
7131           left_tree = Gogo::call_builtin(&interface_compare_decl,
7132                                          location,
7133                                          "__go_interface_compare",
7134                                          2,
7135                                          integer_type_node,
7136                                          TREE_TYPE(left_tree),
7137                                          left_tree,
7138                                          TREE_TYPE(right_tree),
7139                                          right_tree);
7140           if (left_tree == error_mark_node)
7141             return error_mark_node;
7142           // This can panic if the type is uncomparable.
7143           TREE_NOTHROW(interface_compare_decl) = 0;
7144         }
7145       else
7146         {
7147           if (left_type->interface_type()->is_empty())
7148             {
7149               go_assert(op == OPERATOR_EQEQ || op == OPERATOR_NOTEQ);
7150               std::swap(left_type, right_type);
7151               std::swap(left_tree, right_tree);
7152             }
7153           go_assert(!left_type->interface_type()->is_empty());
7154           go_assert(right_type->interface_type()->is_empty());
7155           static tree interface_empty_compare_decl;
7156           left_tree = Gogo::call_builtin(&interface_empty_compare_decl,
7157                                          location,
7158                                          "__go_interface_empty_compare",
7159                                          2,
7160                                          integer_type_node,
7161                                          TREE_TYPE(left_tree),
7162                                          left_tree,
7163                                          TREE_TYPE(right_tree),
7164                                          right_tree);
7165           if (left_tree == error_mark_node)
7166             return error_mark_node;
7167           // This can panic if the type is uncomparable.
7168           TREE_NOTHROW(interface_empty_compare_decl) = 0;
7169         }
7170
7171       right_tree = build_int_cst_type(integer_type_node, 0);
7172     }
7173
7174   if (left_type->is_nil_type()
7175       && (op == OPERATOR_EQEQ || op == OPERATOR_NOTEQ))
7176     {
7177       std::swap(left_type, right_type);
7178       std::swap(left_tree, right_tree);
7179     }
7180
7181   if (right_type->is_nil_type())
7182     {
7183       if (left_type->array_type() != NULL
7184           && left_type->array_type()->length() == NULL)
7185         {
7186           Array_type* at = left_type->array_type();
7187           left_tree = at->value_pointer_tree(context->gogo(), left_tree);
7188           right_tree = fold_convert(TREE_TYPE(left_tree), null_pointer_node);
7189         }
7190       else if (left_type->interface_type() != NULL)
7191         {
7192           // An interface is nil if the first field is nil.
7193           tree left_type_tree = TREE_TYPE(left_tree);
7194           go_assert(TREE_CODE(left_type_tree) == RECORD_TYPE);
7195           tree field = TYPE_FIELDS(left_type_tree);
7196           left_tree = build3(COMPONENT_REF, TREE_TYPE(field), left_tree,
7197                              field, NULL_TREE);
7198           right_tree = fold_convert(TREE_TYPE(left_tree), null_pointer_node);
7199         }
7200       else
7201         {
7202           go_assert(POINTER_TYPE_P(TREE_TYPE(left_tree)));
7203           right_tree = fold_convert(TREE_TYPE(left_tree), null_pointer_node);
7204         }
7205     }
7206
7207   if (left_tree == error_mark_node || right_tree == error_mark_node)
7208     return error_mark_node;
7209
7210   tree ret = fold_build2(code, boolean_type_node, left_tree, right_tree);
7211   if (CAN_HAVE_LOCATION_P(ret))
7212     SET_EXPR_LOCATION(ret, location.gcc_location());
7213   return ret;
7214 }
7215
7216 // Class Bound_method_expression.
7217
7218 // Traversal.
7219
7220 int
7221 Bound_method_expression::do_traverse(Traverse* traverse)
7222 {
7223   return Expression::traverse(&this->expr_, traverse);
7224 }
7225
7226 // Return the type of a bound method expression.  The type of this
7227 // object is really the type of the method with no receiver.  We
7228 // should be able to get away with just returning the type of the
7229 // method.
7230
7231 Type*
7232 Bound_method_expression::do_type()
7233 {
7234   if (this->method_->is_function())
7235     return this->method_->func_value()->type();
7236   else if (this->method_->is_function_declaration())
7237     return this->method_->func_declaration_value()->type();
7238   else
7239     return Type::make_error_type();
7240 }
7241
7242 // Determine the types of a method expression.
7243
7244 void
7245 Bound_method_expression::do_determine_type(const Type_context*)
7246 {
7247   Function_type* fntype = this->type()->function_type();
7248   if (fntype == NULL || !fntype->is_method())
7249     this->expr_->determine_type_no_context();
7250   else
7251     {
7252       Type_context subcontext(fntype->receiver()->type(), false);
7253       this->expr_->determine_type(&subcontext);
7254     }
7255 }
7256
7257 // Check the types of a method expression.
7258
7259 void
7260 Bound_method_expression::do_check_types(Gogo*)
7261 {
7262   if (!this->method_->is_function()
7263       && !this->method_->is_function_declaration())
7264     this->report_error(_("object is not a method"));
7265   else
7266     {
7267       Type* rtype = this->type()->function_type()->receiver()->type()->deref();
7268       Type* etype = (this->expr_type_ != NULL
7269                      ? this->expr_type_
7270                      : this->expr_->type());
7271       etype = etype->deref();
7272       if (!Type::are_identical(rtype, etype, true, NULL))
7273         this->report_error(_("method type does not match object type"));
7274     }
7275 }
7276
7277 // Get the tree for a method expression.  There is no standard tree
7278 // representation for this.  The only places it may currently be used
7279 // are in a Call_expression or a Go_statement, which will take it
7280 // apart directly.  So this has nothing to do at present.
7281
7282 tree
7283 Bound_method_expression::do_get_tree(Translate_context*)
7284 {
7285   error_at(this->location(), "reference to method other than calling it");
7286   return error_mark_node;
7287 }
7288
7289 // Dump ast representation of a bound method expression.
7290
7291 void
7292 Bound_method_expression::do_dump_expression(Ast_dump_context* ast_dump_context)
7293     const
7294 {
7295   if (this->expr_type_ != NULL)
7296     ast_dump_context->ostream() << "(";
7297   ast_dump_context->dump_expression(this->expr_);
7298   if (this->expr_type_ != NULL)
7299     {
7300       ast_dump_context->ostream() << ":";
7301       ast_dump_context->dump_type(this->expr_type_);
7302       ast_dump_context->ostream() << ")";
7303     }
7304
7305   ast_dump_context->ostream() << "." << this->method_->name();
7306 }
7307
7308 // Make a method expression.
7309
7310 Bound_method_expression*
7311 Expression::make_bound_method(Expression* expr, Named_object* method,
7312                               Location location)
7313 {
7314   return new Bound_method_expression(expr, method, location);
7315 }
7316
7317 // Class Builtin_call_expression.  This is used for a call to a
7318 // builtin function.
7319
7320 class Builtin_call_expression : public Call_expression
7321 {
7322  public:
7323   Builtin_call_expression(Gogo* gogo, Expression* fn, Expression_list* args,
7324                           bool is_varargs, Location location);
7325
7326  protected:
7327   // This overrides Call_expression::do_lower.
7328   Expression*
7329   do_lower(Gogo*, Named_object*, Statement_inserter*, int);
7330
7331   bool
7332   do_is_constant() const;
7333
7334   bool
7335   do_integer_constant_value(bool, mpz_t, Type**) const;
7336
7337   bool
7338   do_float_constant_value(mpfr_t, Type**) const;
7339
7340   bool
7341   do_complex_constant_value(mpfr_t, mpfr_t, Type**) const;
7342
7343   void
7344   do_discarding_value();
7345
7346   Type*
7347   do_type();
7348
7349   void
7350   do_determine_type(const Type_context*);
7351
7352   void
7353   do_check_types(Gogo*);
7354
7355   Expression*
7356   do_copy()
7357   {
7358     return new Builtin_call_expression(this->gogo_, this->fn()->copy(),
7359                                        this->args()->copy(),
7360                                        this->is_varargs(),
7361                                        this->location());
7362   }
7363
7364   tree
7365   do_get_tree(Translate_context*);
7366
7367   void
7368   do_export(Export*) const;
7369
7370   virtual bool
7371   do_is_recover_call() const;
7372
7373   virtual void
7374   do_set_recover_arg(Expression*);
7375
7376  private:
7377   // The builtin functions.
7378   enum Builtin_function_code
7379     {
7380       BUILTIN_INVALID,
7381
7382       // Predeclared builtin functions.
7383       BUILTIN_APPEND,
7384       BUILTIN_CAP,
7385       BUILTIN_CLOSE,
7386       BUILTIN_COMPLEX,
7387       BUILTIN_COPY,
7388       BUILTIN_DELETE,
7389       BUILTIN_IMAG,
7390       BUILTIN_LEN,
7391       BUILTIN_MAKE,
7392       BUILTIN_NEW,
7393       BUILTIN_PANIC,
7394       BUILTIN_PRINT,
7395       BUILTIN_PRINTLN,
7396       BUILTIN_REAL,
7397       BUILTIN_RECOVER,
7398
7399       // Builtin functions from the unsafe package.
7400       BUILTIN_ALIGNOF,
7401       BUILTIN_OFFSETOF,
7402       BUILTIN_SIZEOF
7403     };
7404
7405   Expression*
7406   one_arg() const;
7407
7408   bool
7409   check_one_arg();
7410
7411   static Type*
7412   real_imag_type(Type*);
7413
7414   static Type*
7415   complex_type(Type*);
7416
7417   Expression*
7418   lower_make();
7419
7420   bool
7421   check_int_value(Expression*);
7422
7423   // A pointer back to the general IR structure.  This avoids a global
7424   // variable, or passing it around everywhere.
7425   Gogo* gogo_;
7426   // The builtin function being called.
7427   Builtin_function_code code_;
7428   // Used to stop endless loops when the length of an array uses len
7429   // or cap of the array itself.
7430   mutable bool seen_;
7431 };
7432
7433 Builtin_call_expression::Builtin_call_expression(Gogo* gogo,
7434                                                  Expression* fn,
7435                                                  Expression_list* args,
7436                                                  bool is_varargs,
7437                                                  Location location)
7438   : Call_expression(fn, args, is_varargs, location),
7439     gogo_(gogo), code_(BUILTIN_INVALID), seen_(false)
7440 {
7441   Func_expression* fnexp = this->fn()->func_expression();
7442   go_assert(fnexp != NULL);
7443   const std::string& name(fnexp->named_object()->name());
7444   if (name == "append")
7445     this->code_ = BUILTIN_APPEND;
7446   else if (name == "cap")
7447     this->code_ = BUILTIN_CAP;
7448   else if (name == "close")
7449     this->code_ = BUILTIN_CLOSE;
7450   else if (name == "complex")
7451     this->code_ = BUILTIN_COMPLEX;
7452   else if (name == "copy")
7453     this->code_ = BUILTIN_COPY;
7454   else if (name == "delete")
7455     this->code_ = BUILTIN_DELETE;
7456   else if (name == "imag")
7457     this->code_ = BUILTIN_IMAG;
7458   else if (name == "len")
7459     this->code_ = BUILTIN_LEN;
7460   else if (name == "make")
7461     this->code_ = BUILTIN_MAKE;
7462   else if (name == "new")
7463     this->code_ = BUILTIN_NEW;
7464   else if (name == "panic")
7465     this->code_ = BUILTIN_PANIC;
7466   else if (name == "print")
7467     this->code_ = BUILTIN_PRINT;
7468   else if (name == "println")
7469     this->code_ = BUILTIN_PRINTLN;
7470   else if (name == "real")
7471     this->code_ = BUILTIN_REAL;
7472   else if (name == "recover")
7473     this->code_ = BUILTIN_RECOVER;
7474   else if (name == "Alignof")
7475     this->code_ = BUILTIN_ALIGNOF;
7476   else if (name == "Offsetof")
7477     this->code_ = BUILTIN_OFFSETOF;
7478   else if (name == "Sizeof")
7479     this->code_ = BUILTIN_SIZEOF;
7480   else
7481     go_unreachable();
7482 }
7483
7484 // Return whether this is a call to recover.  This is a virtual
7485 // function called from the parent class.
7486
7487 bool
7488 Builtin_call_expression::do_is_recover_call() const
7489 {
7490   if (this->classification() == EXPRESSION_ERROR)
7491     return false;
7492   return this->code_ == BUILTIN_RECOVER;
7493 }
7494
7495 // Set the argument for a call to recover.
7496
7497 void
7498 Builtin_call_expression::do_set_recover_arg(Expression* arg)
7499 {
7500   const Expression_list* args = this->args();
7501   go_assert(args == NULL || args->empty());
7502   Expression_list* new_args = new Expression_list();
7503   new_args->push_back(arg);
7504   this->set_args(new_args);
7505 }
7506
7507 // A traversal class which looks for a call expression.
7508
7509 class Find_call_expression : public Traverse
7510 {
7511  public:
7512   Find_call_expression()
7513     : Traverse(traverse_expressions),
7514       found_(false)
7515   { }
7516
7517   int
7518   expression(Expression**);
7519
7520   bool
7521   found()
7522   { return this->found_; }
7523
7524  private:
7525   bool found_;
7526 };
7527
7528 int
7529 Find_call_expression::expression(Expression** pexpr)
7530 {
7531   if ((*pexpr)->call_expression() != NULL)
7532     {
7533       this->found_ = true;
7534       return TRAVERSE_EXIT;
7535     }
7536   return TRAVERSE_CONTINUE;
7537 }
7538
7539 // Lower a builtin call expression.  This turns new and make into
7540 // specific expressions.  We also convert to a constant if we can.
7541
7542 Expression*
7543 Builtin_call_expression::do_lower(Gogo* gogo, Named_object* function,
7544                                   Statement_inserter* inserter, int)
7545 {
7546   if (this->classification() == EXPRESSION_ERROR)
7547     return this;
7548
7549   Location loc = this->location();
7550
7551   if (this->is_varargs() && this->code_ != BUILTIN_APPEND)
7552     {
7553       this->report_error(_("invalid use of %<...%> with builtin function"));
7554       return Expression::make_error(loc);
7555     }
7556
7557   if (this->is_constant())
7558     {
7559       // We can only lower len and cap if there are no function calls
7560       // in the arguments.  Otherwise we have to make the call.
7561       if (this->code_ == BUILTIN_LEN || this->code_ == BUILTIN_CAP)
7562         {
7563           Expression* arg = this->one_arg();
7564           if (!arg->is_constant())
7565             {
7566               Find_call_expression find_call;
7567               Expression::traverse(&arg, &find_call);
7568               if (find_call.found())
7569                 return this;
7570             }
7571         }
7572
7573       mpz_t ival;
7574       mpz_init(ival);
7575       Type* type;
7576       if (this->integer_constant_value(true, ival, &type))
7577         {
7578           Expression* ret = Expression::make_integer(&ival, type, loc);
7579           mpz_clear(ival);
7580           return ret;
7581         }
7582       mpz_clear(ival);
7583
7584       mpfr_t rval;
7585       mpfr_init(rval);
7586       if (this->float_constant_value(rval, &type))
7587         {
7588           Expression* ret = Expression::make_float(&rval, type, loc);
7589           mpfr_clear(rval);
7590           return ret;
7591         }
7592
7593       mpfr_t imag;
7594       mpfr_init(imag);
7595       if (this->complex_constant_value(rval, imag, &type))
7596         {
7597           Expression* ret = Expression::make_complex(&rval, &imag, type, loc);
7598           mpfr_clear(rval);
7599           mpfr_clear(imag);
7600           return ret;
7601         }
7602       mpfr_clear(rval);
7603       mpfr_clear(imag);
7604     }
7605
7606   switch (this->code_)
7607     {
7608     default:
7609       break;
7610
7611     case BUILTIN_NEW:
7612       {
7613         const Expression_list* args = this->args();
7614         if (args == NULL || args->size() < 1)
7615           this->report_error(_("not enough arguments"));
7616         else if (args->size() > 1)
7617           this->report_error(_("too many arguments"));
7618         else
7619           {
7620             Expression* arg = args->front();
7621             if (!arg->is_type_expression())
7622               {
7623                 error_at(arg->location(), "expected type");
7624                 this->set_is_error();
7625               }
7626             else
7627               return Expression::make_allocation(arg->type(), loc);
7628           }
7629       }
7630       break;
7631
7632     case BUILTIN_MAKE:
7633       return this->lower_make();
7634
7635     case BUILTIN_RECOVER:
7636       if (function != NULL)
7637         function->func_value()->set_calls_recover();
7638       else
7639         {
7640           // Calling recover outside of a function always returns the
7641           // nil empty interface.
7642           Type* eface = Type::make_empty_interface_type(loc);
7643           return Expression::make_cast(eface, Expression::make_nil(loc), loc);
7644         }
7645       break;
7646
7647     case BUILTIN_APPEND:
7648       {
7649         // Lower the varargs.
7650         const Expression_list* args = this->args();
7651         if (args == NULL || args->empty())
7652           return this;
7653         Type* slice_type = args->front()->type();
7654         if (!slice_type->is_slice_type())
7655           {
7656             error_at(args->front()->location(), "argument 1 must be a slice");
7657             this->set_is_error();
7658             return this;
7659           }
7660         Type* element_type = slice_type->array_type()->element_type();
7661         this->lower_varargs(gogo, function, inserter,
7662                             Type::make_array_type(element_type, NULL),
7663                             2);
7664       }
7665       break;
7666
7667     case BUILTIN_DELETE:
7668       {
7669         // Lower to a runtime function call.
7670         const Expression_list* args = this->args();
7671         if (args == NULL || args->size() < 2)
7672           this->report_error(_("not enough arguments"));
7673         else if (args->size() > 2)
7674           this->report_error(_("too many arguments"));
7675         else if (args->front()->type()->map_type() == NULL)
7676           this->report_error(_("argument 1 must be a map"));
7677         else
7678           {
7679             // Since this function returns no value it must appear in
7680             // a statement by itself, so we don't have to worry about
7681             // order of evaluation of values around it.  Evaluate the
7682             // map first to get order of evaluation right.
7683             Map_type* mt = args->front()->type()->map_type();
7684             Temporary_statement* map_temp =
7685               Statement::make_temporary(mt, args->front(), loc);
7686             inserter->insert(map_temp);
7687
7688             Temporary_statement* key_temp =
7689               Statement::make_temporary(mt->key_type(), args->back(), loc);
7690             inserter->insert(key_temp);
7691
7692             Expression* e1 = Expression::make_temporary_reference(map_temp,
7693                                                                   loc);
7694             Expression* e2 = Expression::make_temporary_reference(key_temp,
7695                                                                   loc);
7696             e2 = Expression::make_unary(OPERATOR_AND, e2, loc);
7697             return Runtime::make_call(Runtime::MAPDELETE, this->location(),
7698                                       2, e1, e2);
7699           }
7700       }
7701       break;
7702     }
7703
7704   return this;
7705 }
7706
7707 // Lower a make expression.
7708
7709 Expression*
7710 Builtin_call_expression::lower_make()
7711 {
7712   Location loc = this->location();
7713
7714   const Expression_list* args = this->args();
7715   if (args == NULL || args->size() < 1)
7716     {
7717       this->report_error(_("not enough arguments"));
7718       return Expression::make_error(this->location());
7719     }
7720
7721   Expression_list::const_iterator parg = args->begin();
7722
7723   Expression* first_arg = *parg;
7724   if (!first_arg->is_type_expression())
7725     {
7726       error_at(first_arg->location(), "expected type");
7727       this->set_is_error();
7728       return Expression::make_error(this->location());
7729     }
7730   Type* type = first_arg->type();
7731
7732   bool is_slice = false;
7733   bool is_map = false;
7734   bool is_chan = false;
7735   if (type->is_slice_type())
7736     is_slice = true;
7737   else if (type->map_type() != NULL)
7738     is_map = true;
7739   else if (type->channel_type() != NULL)
7740     is_chan = true;
7741   else
7742     {
7743       this->report_error(_("invalid type for make function"));
7744       return Expression::make_error(this->location());
7745     }
7746
7747   ++parg;
7748   Expression* len_arg;
7749   if (parg == args->end())
7750     {
7751       if (is_slice)
7752         {
7753           this->report_error(_("length required when allocating a slice"));
7754           return Expression::make_error(this->location());
7755         }
7756
7757       mpz_t zval;
7758       mpz_init_set_ui(zval, 0);
7759       len_arg = Expression::make_integer(&zval, NULL, loc);
7760       mpz_clear(zval);
7761     }
7762   else
7763     {
7764       len_arg = *parg;
7765       if (!this->check_int_value(len_arg))
7766         {
7767           this->report_error(_("bad size for make"));
7768           return Expression::make_error(this->location());
7769         }
7770       ++parg;
7771     }
7772
7773   Expression* cap_arg = NULL;
7774   if (is_slice && parg != args->end())
7775     {
7776       cap_arg = *parg;
7777       if (!this->check_int_value(cap_arg))
7778         {
7779           this->report_error(_("bad capacity when making slice"));
7780           return Expression::make_error(this->location());
7781         }
7782       ++parg;
7783     }
7784
7785   if (parg != args->end())
7786     {
7787       this->report_error(_("too many arguments to make"));
7788       return Expression::make_error(this->location());
7789     }
7790
7791   Location type_loc = first_arg->location();
7792   Expression* type_arg;
7793   if (is_slice || is_chan)
7794     type_arg = Expression::make_type_descriptor(type, type_loc);
7795   else if (is_map)
7796     type_arg = Expression::make_map_descriptor(type->map_type(), type_loc);
7797   else
7798     go_unreachable();
7799
7800   Expression* call;
7801   if (is_slice)
7802     {
7803       if (cap_arg == NULL)
7804         call = Runtime::make_call(Runtime::MAKESLICE1, loc, 2, type_arg,
7805                                   len_arg);
7806       else
7807         call = Runtime::make_call(Runtime::MAKESLICE2, loc, 3, type_arg,
7808                                   len_arg, cap_arg);
7809     }
7810   else if (is_map)
7811     call = Runtime::make_call(Runtime::MAKEMAP, loc, 2, type_arg, len_arg);
7812   else if (is_chan)
7813     call = Runtime::make_call(Runtime::MAKECHAN, loc, 2, type_arg, len_arg);
7814   else
7815     go_unreachable();
7816
7817   return Expression::make_unsafe_cast(type, call, loc);
7818 }
7819
7820 // Return whether an expression has an integer value.  Report an error
7821 // if not.  This is used when handling calls to the predeclared make
7822 // function.
7823
7824 bool
7825 Builtin_call_expression::check_int_value(Expression* e)
7826 {
7827   if (e->type()->integer_type() != NULL)
7828     return true;
7829
7830   // Check for a floating point constant with integer value.
7831   mpfr_t fval;
7832   mpfr_init(fval);
7833
7834   Type* dummy;
7835   if (e->float_constant_value(fval, &dummy) && mpfr_integer_p(fval))
7836     {
7837       mpz_t ival;
7838       mpz_init(ival);
7839
7840       bool ok = false;
7841
7842       mpfr_clear_overflow();
7843       mpfr_clear_erangeflag();
7844       mpfr_get_z(ival, fval, GMP_RNDN);
7845       if (!mpfr_overflow_p()
7846           && !mpfr_erangeflag_p()
7847           && mpz_sgn(ival) >= 0)
7848         {
7849           Named_type* ntype = Type::lookup_integer_type("int");
7850           Integer_type* inttype = ntype->integer_type();
7851           mpz_t max;
7852           mpz_init_set_ui(max, 1);
7853           mpz_mul_2exp(max, max, inttype->bits() - 1);
7854           ok = mpz_cmp(ival, max) < 0;
7855           mpz_clear(max);
7856         }
7857       mpz_clear(ival);
7858
7859       if (ok)
7860         {
7861           mpfr_clear(fval);
7862           return true;
7863         }
7864     }
7865
7866   mpfr_clear(fval);
7867
7868   return false;
7869 }
7870
7871 // Return the type of the real or imag functions, given the type of
7872 // the argument.  We need to map complex to float, complex64 to
7873 // float32, and complex128 to float64, so it has to be done by name.
7874 // This returns NULL if it can't figure out the type.
7875
7876 Type*
7877 Builtin_call_expression::real_imag_type(Type* arg_type)
7878 {
7879   if (arg_type == NULL || arg_type->is_abstract())
7880     return NULL;
7881   Named_type* nt = arg_type->named_type();
7882   if (nt == NULL)
7883     return NULL;
7884   while (nt->real_type()->named_type() != NULL)
7885     nt = nt->real_type()->named_type();
7886   if (nt->name() == "complex64")
7887     return Type::lookup_float_type("float32");
7888   else if (nt->name() == "complex128")
7889     return Type::lookup_float_type("float64");
7890   else
7891     return NULL;
7892 }
7893
7894 // Return the type of the complex function, given the type of one of the
7895 // argments.  Like real_imag_type, we have to map by name.
7896
7897 Type*
7898 Builtin_call_expression::complex_type(Type* arg_type)
7899 {
7900   if (arg_type == NULL || arg_type->is_abstract())
7901     return NULL;
7902   Named_type* nt = arg_type->named_type();
7903   if (nt == NULL)
7904     return NULL;
7905   while (nt->real_type()->named_type() != NULL)
7906     nt = nt->real_type()->named_type();
7907   if (nt->name() == "float32")
7908     return Type::lookup_complex_type("complex64");
7909   else if (nt->name() == "float64")
7910     return Type::lookup_complex_type("complex128");
7911   else
7912     return NULL;
7913 }
7914
7915 // Return a single argument, or NULL if there isn't one.
7916
7917 Expression*
7918 Builtin_call_expression::one_arg() const
7919 {
7920   const Expression_list* args = this->args();
7921   if (args->size() != 1)
7922     return NULL;
7923   return args->front();
7924 }
7925
7926 // Return whether this is constant: len of a string, or len or cap of
7927 // a fixed array, or unsafe.Sizeof, unsafe.Offsetof, unsafe.Alignof.
7928
7929 bool
7930 Builtin_call_expression::do_is_constant() const
7931 {
7932   switch (this->code_)
7933     {
7934     case BUILTIN_LEN:
7935     case BUILTIN_CAP:
7936       {
7937         if (this->seen_)
7938           return false;
7939
7940         Expression* arg = this->one_arg();
7941         if (arg == NULL)
7942           return false;
7943         Type* arg_type = arg->type();
7944
7945         if (arg_type->points_to() != NULL
7946             && arg_type->points_to()->array_type() != NULL
7947             && !arg_type->points_to()->is_slice_type())
7948           arg_type = arg_type->points_to();
7949
7950         if (arg_type->array_type() != NULL
7951             && arg_type->array_type()->length() != NULL)
7952           return true;
7953
7954         if (this->code_ == BUILTIN_LEN && arg_type->is_string_type())
7955           {
7956             this->seen_ = true;
7957             bool ret = arg->is_constant();
7958             this->seen_ = false;
7959             return ret;
7960           }
7961       }
7962       break;
7963
7964     case BUILTIN_SIZEOF:
7965     case BUILTIN_ALIGNOF:
7966       return this->one_arg() != NULL;
7967
7968     case BUILTIN_OFFSETOF:
7969       {
7970         Expression* arg = this->one_arg();
7971         if (arg == NULL)
7972           return false;
7973         return arg->field_reference_expression() != NULL;
7974       }
7975
7976     case BUILTIN_COMPLEX:
7977       {
7978         const Expression_list* args = this->args();
7979         if (args != NULL && args->size() == 2)
7980           return args->front()->is_constant() && args->back()->is_constant();
7981       }
7982       break;
7983
7984     case BUILTIN_REAL:
7985     case BUILTIN_IMAG:
7986       {
7987         Expression* arg = this->one_arg();
7988         return arg != NULL && arg->is_constant();
7989       }
7990
7991     default:
7992       break;
7993     }
7994
7995   return false;
7996 }
7997
7998 // Return an integer constant value if possible.
7999
8000 bool
8001 Builtin_call_expression::do_integer_constant_value(bool iota_is_constant,
8002                                                    mpz_t val,
8003                                                    Type** ptype) const
8004 {
8005   if (this->code_ == BUILTIN_LEN
8006       || this->code_ == BUILTIN_CAP)
8007     {
8008       Expression* arg = this->one_arg();
8009       if (arg == NULL)
8010         return false;
8011       Type* arg_type = arg->type();
8012
8013       if (this->code_ == BUILTIN_LEN && arg_type->is_string_type())
8014         {
8015           std::string sval;
8016           if (arg->string_constant_value(&sval))
8017             {
8018               mpz_set_ui(val, sval.length());
8019               *ptype = Type::lookup_integer_type("int");
8020               return true;
8021             }
8022         }
8023
8024       if (arg_type->points_to() != NULL
8025           && arg_type->points_to()->array_type() != NULL
8026           && !arg_type->points_to()->is_slice_type())
8027         arg_type = arg_type->points_to();
8028
8029       if (arg_type->array_type() != NULL
8030           && arg_type->array_type()->length() != NULL)
8031         {
8032           if (this->seen_)
8033             return false;
8034           Expression* e = arg_type->array_type()->length();
8035           this->seen_ = true;
8036           bool r = e->integer_constant_value(iota_is_constant, val, ptype);
8037           this->seen_ = false;
8038           if (r)
8039             {
8040               *ptype = Type::lookup_integer_type("int");
8041               return true;
8042             }
8043         }
8044     }
8045   else if (this->code_ == BUILTIN_SIZEOF
8046            || this->code_ == BUILTIN_ALIGNOF)
8047     {
8048       Expression* arg = this->one_arg();
8049       if (arg == NULL)
8050         return false;
8051       Type* arg_type = arg->type();
8052       if (arg_type->is_error())
8053         return false;
8054       if (arg_type->is_abstract())
8055         return false;
8056       if (arg_type->named_type() != NULL)
8057         arg_type->named_type()->convert(this->gogo_);
8058
8059       unsigned int ret;
8060       if (this->code_ == BUILTIN_SIZEOF)
8061         {
8062           if (!arg_type->backend_type_size(this->gogo_, &ret))
8063             return false;
8064         }
8065       else if (this->code_ == BUILTIN_ALIGNOF)
8066         {
8067           if (arg->field_reference_expression() == NULL)
8068             {
8069               if (!arg_type->backend_type_align(this->gogo_, &ret))
8070                 return false;
8071             }
8072           else
8073             {
8074               // Calling unsafe.Alignof(s.f) returns the alignment of
8075               // the type of f when it is used as a field in a struct.
8076               if (!arg_type->backend_type_field_align(this->gogo_, &ret))
8077                 return false;
8078             }
8079         }
8080       else
8081         go_unreachable();
8082
8083       mpz_set_ui(val, ret);
8084       *ptype = NULL;
8085       return true;
8086     }
8087   else if (this->code_ == BUILTIN_OFFSETOF)
8088     {
8089       Expression* arg = this->one_arg();
8090       if (arg == NULL)
8091         return false;
8092       Field_reference_expression* farg = arg->field_reference_expression();
8093       if (farg == NULL)
8094         return false;
8095       Expression* struct_expr = farg->expr();
8096       Type* st = struct_expr->type();
8097       if (st->struct_type() == NULL)
8098         return false;
8099       if (st->named_type() != NULL)
8100         st->named_type()->convert(this->gogo_);
8101       unsigned int offset;
8102       if (!st->struct_type()->backend_field_offset(this->gogo_,
8103                                                    farg->field_index(),
8104                                                    &offset))
8105         return false;
8106       mpz_set_ui(val, offset);
8107       return true;
8108     }
8109   return false;
8110 }
8111
8112 // Return a floating point constant value if possible.
8113
8114 bool
8115 Builtin_call_expression::do_float_constant_value(mpfr_t val,
8116                                                  Type** ptype) const
8117 {
8118   if (this->code_ == BUILTIN_REAL || this->code_ == BUILTIN_IMAG)
8119     {
8120       Expression* arg = this->one_arg();
8121       if (arg == NULL)
8122         return false;
8123
8124       mpfr_t real;
8125       mpfr_t imag;
8126       mpfr_init(real);
8127       mpfr_init(imag);
8128
8129       bool ret = false;
8130       Type* type;
8131       if (arg->complex_constant_value(real, imag, &type))
8132         {
8133           if (this->code_ == BUILTIN_REAL)
8134             mpfr_set(val, real, GMP_RNDN);
8135           else
8136             mpfr_set(val, imag, GMP_RNDN);
8137           *ptype = Builtin_call_expression::real_imag_type(type);
8138           ret = true;
8139         }
8140
8141       mpfr_clear(real);
8142       mpfr_clear(imag);
8143       return ret;
8144     }
8145
8146   return false;
8147 }
8148
8149 // Return a complex constant value if possible.
8150
8151 bool
8152 Builtin_call_expression::do_complex_constant_value(mpfr_t real, mpfr_t imag,
8153                                                    Type** ptype) const
8154 {
8155   if (this->code_ == BUILTIN_COMPLEX)
8156     {
8157       const Expression_list* args = this->args();
8158       if (args == NULL || args->size() != 2)
8159         return false;
8160
8161       mpfr_t r;
8162       mpfr_init(r);
8163       Type* rtype;
8164       if (!args->front()->float_constant_value(r, &rtype))
8165         {
8166           mpfr_clear(r);
8167           return false;
8168         }
8169
8170       mpfr_t i;
8171       mpfr_init(i);
8172
8173       bool ret = false;
8174       Type* itype;
8175       if (args->back()->float_constant_value(i, &itype)
8176           && Type::are_identical(rtype, itype, false, NULL))
8177         {
8178           mpfr_set(real, r, GMP_RNDN);
8179           mpfr_set(imag, i, GMP_RNDN);
8180           *ptype = Builtin_call_expression::complex_type(rtype);
8181           ret = true;
8182         }
8183
8184       mpfr_clear(r);
8185       mpfr_clear(i);
8186
8187       return ret;
8188     }
8189
8190   return false;
8191 }
8192
8193 // Give an error if we are discarding the value of an expression which
8194 // should not normally be discarded.  We don't give an error for
8195 // discarding the value of an ordinary function call, but we do for
8196 // builtin functions, purely for consistency with the gc compiler.
8197
8198 void
8199 Builtin_call_expression::do_discarding_value()
8200 {
8201   switch (this->code_)
8202     {
8203     case BUILTIN_INVALID:
8204     default:
8205       go_unreachable();
8206
8207     case BUILTIN_APPEND:
8208     case BUILTIN_CAP:
8209     case BUILTIN_COMPLEX:
8210     case BUILTIN_IMAG:
8211     case BUILTIN_LEN:
8212     case BUILTIN_MAKE:
8213     case BUILTIN_NEW:
8214     case BUILTIN_REAL:
8215     case BUILTIN_ALIGNOF:
8216     case BUILTIN_OFFSETOF:
8217     case BUILTIN_SIZEOF:
8218       this->unused_value_error();
8219       break;
8220
8221     case BUILTIN_CLOSE:
8222     case BUILTIN_COPY:
8223     case BUILTIN_DELETE:
8224     case BUILTIN_PANIC:
8225     case BUILTIN_PRINT:
8226     case BUILTIN_PRINTLN:
8227     case BUILTIN_RECOVER:
8228       break;
8229     }
8230 }
8231
8232 // Return the type.
8233
8234 Type*
8235 Builtin_call_expression::do_type()
8236 {
8237   switch (this->code_)
8238     {
8239     case BUILTIN_INVALID:
8240     default:
8241       go_unreachable();
8242
8243     case BUILTIN_NEW:
8244     case BUILTIN_MAKE:
8245       {
8246         const Expression_list* args = this->args();
8247         if (args == NULL || args->empty())
8248           return Type::make_error_type();
8249         return Type::make_pointer_type(args->front()->type());
8250       }
8251
8252     case BUILTIN_CAP:
8253     case BUILTIN_COPY:
8254     case BUILTIN_LEN:
8255     case BUILTIN_ALIGNOF:
8256     case BUILTIN_OFFSETOF:
8257     case BUILTIN_SIZEOF:
8258       return Type::lookup_integer_type("int");
8259
8260     case BUILTIN_CLOSE:
8261     case BUILTIN_DELETE:
8262     case BUILTIN_PANIC:
8263     case BUILTIN_PRINT:
8264     case BUILTIN_PRINTLN:
8265       return Type::make_void_type();
8266
8267     case BUILTIN_RECOVER:
8268       return Type::make_empty_interface_type(Linemap::predeclared_location());
8269
8270     case BUILTIN_APPEND:
8271       {
8272         const Expression_list* args = this->args();
8273         if (args == NULL || args->empty())
8274           return Type::make_error_type();
8275         return args->front()->type();
8276       }
8277
8278     case BUILTIN_REAL:
8279     case BUILTIN_IMAG:
8280       {
8281         Expression* arg = this->one_arg();
8282         if (arg == NULL)
8283           return Type::make_error_type();
8284         Type* t = arg->type();
8285         if (t->is_abstract())
8286           t = t->make_non_abstract_type();
8287         t = Builtin_call_expression::real_imag_type(t);
8288         if (t == NULL)
8289           t = Type::make_error_type();
8290         return t;
8291       }
8292
8293     case BUILTIN_COMPLEX:
8294       {
8295         const Expression_list* args = this->args();
8296         if (args == NULL || args->size() != 2)
8297           return Type::make_error_type();
8298         Type* t = args->front()->type();
8299         if (t->is_abstract())
8300           {
8301             t = args->back()->type();
8302             if (t->is_abstract())
8303               t = t->make_non_abstract_type();
8304           }
8305         t = Builtin_call_expression::complex_type(t);
8306         if (t == NULL)
8307           t = Type::make_error_type();
8308         return t;
8309       }
8310     }
8311 }
8312
8313 // Determine the type.
8314
8315 void
8316 Builtin_call_expression::do_determine_type(const Type_context* context)
8317 {
8318   if (!this->determining_types())
8319     return;
8320
8321   this->fn()->determine_type_no_context();
8322
8323   const Expression_list* args = this->args();
8324
8325   bool is_print;
8326   Type* arg_type = NULL;
8327   switch (this->code_)
8328     {
8329     case BUILTIN_PRINT:
8330     case BUILTIN_PRINTLN:
8331       // Do not force a large integer constant to "int".
8332       is_print = true;
8333       break;
8334
8335     case BUILTIN_REAL:
8336     case BUILTIN_IMAG:
8337       arg_type = Builtin_call_expression::complex_type(context->type);
8338       is_print = false;
8339       break;
8340
8341     case BUILTIN_COMPLEX:
8342       {
8343         // For the complex function the type of one operand can
8344         // determine the type of the other, as in a binary expression.
8345         arg_type = Builtin_call_expression::real_imag_type(context->type);
8346         if (args != NULL && args->size() == 2)
8347           {
8348             Type* t1 = args->front()->type();
8349             Type* t2 = args->front()->type();
8350             if (!t1->is_abstract())
8351               arg_type = t1;
8352             else if (!t2->is_abstract())
8353               arg_type = t2;
8354           }
8355         is_print = false;
8356       }
8357       break;
8358
8359     default:
8360       is_print = false;
8361       break;
8362     }
8363
8364   if (args != NULL)
8365     {
8366       for (Expression_list::const_iterator pa = args->begin();
8367            pa != args->end();
8368            ++pa)
8369         {
8370           Type_context subcontext;
8371           subcontext.type = arg_type;
8372
8373           if (is_print)
8374             {
8375               // We want to print large constants, we so can't just
8376               // use the appropriate nonabstract type.  Use uint64 for
8377               // an integer if we know it is nonnegative, otherwise
8378               // use int64 for a integer, otherwise use float64 for a
8379               // float or complex128 for a complex.
8380               Type* want_type = NULL;
8381               Type* atype = (*pa)->type();
8382               if (atype->is_abstract())
8383                 {
8384                   if (atype->integer_type() != NULL)
8385                     {
8386                       mpz_t val;
8387                       mpz_init(val);
8388                       Type* dummy;
8389                       if (this->integer_constant_value(true, val, &dummy)
8390                           && mpz_sgn(val) >= 0)
8391                         want_type = Type::lookup_integer_type("uint64");
8392                       else
8393                         want_type = Type::lookup_integer_type("int64");
8394                       mpz_clear(val);
8395                     }
8396                   else if (atype->float_type() != NULL)
8397                     want_type = Type::lookup_float_type("float64");
8398                   else if (atype->complex_type() != NULL)
8399                     want_type = Type::lookup_complex_type("complex128");
8400                   else if (atype->is_abstract_string_type())
8401                     want_type = Type::lookup_string_type();
8402                   else if (atype->is_abstract_boolean_type())
8403                     want_type = Type::lookup_bool_type();
8404                   else
8405                     go_unreachable();
8406                   subcontext.type = want_type;
8407                 }
8408             }
8409
8410           (*pa)->determine_type(&subcontext);
8411         }
8412     }
8413 }
8414
8415 // If there is exactly one argument, return true.  Otherwise give an
8416 // error message and return false.
8417
8418 bool
8419 Builtin_call_expression::check_one_arg()
8420 {
8421   const Expression_list* args = this->args();
8422   if (args == NULL || args->size() < 1)
8423     {
8424       this->report_error(_("not enough arguments"));
8425       return false;
8426     }
8427   else if (args->size() > 1)
8428     {
8429       this->report_error(_("too many arguments"));
8430       return false;
8431     }
8432   if (args->front()->is_error_expression()
8433       || args->front()->type()->is_error())
8434     {
8435       this->set_is_error();
8436       return false;
8437     }
8438   return true;
8439 }
8440
8441 // Check argument types for a builtin function.
8442
8443 void
8444 Builtin_call_expression::do_check_types(Gogo*)
8445 {
8446   switch (this->code_)
8447     {
8448     case BUILTIN_INVALID:
8449     case BUILTIN_NEW:
8450     case BUILTIN_MAKE:
8451       return;
8452
8453     case BUILTIN_LEN:
8454     case BUILTIN_CAP:
8455       {
8456         // The single argument may be either a string or an array or a
8457         // map or a channel, or a pointer to a closed array.
8458         if (this->check_one_arg())
8459           {
8460             Type* arg_type = this->one_arg()->type();
8461             if (arg_type->points_to() != NULL
8462                 && arg_type->points_to()->array_type() != NULL
8463                 && !arg_type->points_to()->is_slice_type())
8464               arg_type = arg_type->points_to();
8465             if (this->code_ == BUILTIN_CAP)
8466               {
8467                 if (!arg_type->is_error()
8468                     && arg_type->array_type() == NULL
8469                     && arg_type->channel_type() == NULL)
8470                   this->report_error(_("argument must be array or slice "
8471                                        "or channel"));
8472               }
8473             else
8474               {
8475                 if (!arg_type->is_error()
8476                     && !arg_type->is_string_type()
8477                     && arg_type->array_type() == NULL
8478                     && arg_type->map_type() == NULL
8479                     && arg_type->channel_type() == NULL)
8480                   this->report_error(_("argument must be string or "
8481                                        "array or slice or map or channel"));
8482               }
8483           }
8484       }
8485       break;
8486
8487     case BUILTIN_PRINT:
8488     case BUILTIN_PRINTLN:
8489       {
8490         const Expression_list* args = this->args();
8491         if (args == NULL)
8492           {
8493             if (this->code_ == BUILTIN_PRINT)
8494               warning_at(this->location(), 0,
8495                          "no arguments for builtin function %<%s%>",
8496                          (this->code_ == BUILTIN_PRINT
8497                           ? "print"
8498                           : "println"));
8499           }
8500         else
8501           {
8502             for (Expression_list::const_iterator p = args->begin();
8503                  p != args->end();
8504                  ++p)
8505               {
8506                 Type* type = (*p)->type();
8507                 if (type->is_error()
8508                     || type->is_string_type()
8509                     || type->integer_type() != NULL
8510                     || type->float_type() != NULL
8511                     || type->complex_type() != NULL
8512                     || type->is_boolean_type()
8513                     || type->points_to() != NULL
8514                     || type->interface_type() != NULL
8515                     || type->channel_type() != NULL
8516                     || type->map_type() != NULL
8517                     || type->function_type() != NULL
8518                     || type->is_slice_type())
8519                   ;
8520                 else if ((*p)->is_type_expression())
8521                   {
8522                     // If this is a type expression it's going to give
8523                     // an error anyhow, so we don't need one here.
8524                   }
8525                 else
8526                   this->report_error(_("unsupported argument type to "
8527                                        "builtin function"));
8528               }
8529           }
8530       }
8531       break;
8532
8533     case BUILTIN_CLOSE:
8534       if (this->check_one_arg())
8535         {
8536           if (this->one_arg()->type()->channel_type() == NULL)
8537             this->report_error(_("argument must be channel"));
8538           else if (!this->one_arg()->type()->channel_type()->may_send())
8539             this->report_error(_("cannot close receive-only channel"));
8540         }
8541       break;
8542
8543     case BUILTIN_PANIC:
8544     case BUILTIN_SIZEOF:
8545     case BUILTIN_ALIGNOF:
8546       this->check_one_arg();
8547       break;
8548
8549     case BUILTIN_RECOVER:
8550       if (this->args() != NULL && !this->args()->empty())
8551         this->report_error(_("too many arguments"));
8552       break;
8553
8554     case BUILTIN_OFFSETOF:
8555       if (this->check_one_arg())
8556         {
8557           Expression* arg = this->one_arg();
8558           if (arg->field_reference_expression() == NULL)
8559             this->report_error(_("argument must be a field reference"));
8560         }
8561       break;
8562
8563     case BUILTIN_COPY:
8564       {
8565         const Expression_list* args = this->args();
8566         if (args == NULL || args->size() < 2)
8567           {
8568             this->report_error(_("not enough arguments"));
8569             break;
8570           }
8571         else if (args->size() > 2)
8572           {
8573             this->report_error(_("too many arguments"));
8574             break;
8575           }
8576         Type* arg1_type = args->front()->type();
8577         Type* arg2_type = args->back()->type();
8578         if (arg1_type->is_error() || arg2_type->is_error())
8579           break;
8580
8581         Type* e1;
8582         if (arg1_type->is_slice_type())
8583           e1 = arg1_type->array_type()->element_type();
8584         else
8585           {
8586             this->report_error(_("left argument must be a slice"));
8587             break;
8588           }
8589
8590         if (arg2_type->is_slice_type())
8591           {
8592             Type* e2 = arg2_type->array_type()->element_type();
8593             if (!Type::are_identical(e1, e2, true, NULL))
8594               this->report_error(_("element types must be the same"));
8595           }
8596         else if (arg2_type->is_string_type())
8597           {
8598             if (e1->integer_type() == NULL || !e1->integer_type()->is_byte())
8599               this->report_error(_("first argument must be []byte"));
8600           }
8601         else
8602             this->report_error(_("second argument must be slice or string"));
8603       }
8604       break;
8605
8606     case BUILTIN_APPEND:
8607       {
8608         const Expression_list* args = this->args();
8609         if (args == NULL || args->size() < 2)
8610           {
8611             this->report_error(_("not enough arguments"));
8612             break;
8613           }
8614         if (args->size() > 2)
8615           {
8616             this->report_error(_("too many arguments"));
8617             break;
8618           }
8619
8620         // The language permits appending a string to a []byte, as a
8621         // special case.
8622         if (args->back()->type()->is_string_type())
8623           {
8624             const Array_type* at = args->front()->type()->array_type();
8625             const Type* e = at->element_type()->forwarded();
8626             if (e->integer_type() != NULL && e->integer_type()->is_byte())
8627               break;
8628           }
8629
8630         // The language says that the second argument must be
8631         // assignable to a slice of the element type of the first
8632         // argument.  We already know the first argument is a slice
8633         // type.
8634         Array_type* at = args->front()->type()->array_type();
8635         Type* arg2_type = Type::make_array_type(at->element_type(), NULL);
8636         std::string reason;
8637         if (!Type::are_assignable(arg2_type, args->back()->type(), &reason))
8638           {
8639             if (reason.empty())
8640               this->report_error(_("argument 2 has invalid type"));
8641             else
8642               {
8643                 error_at(this->location(), "argument 2 has invalid type (%s)",
8644                          reason.c_str());
8645                 this->set_is_error();
8646               }
8647           }
8648         break;
8649       }
8650
8651     case BUILTIN_REAL:
8652     case BUILTIN_IMAG:
8653       if (this->check_one_arg())
8654         {
8655           if (this->one_arg()->type()->complex_type() == NULL)
8656             this->report_error(_("argument must have complex type"));
8657         }
8658       break;
8659
8660     case BUILTIN_COMPLEX:
8661       {
8662         const Expression_list* args = this->args();
8663         if (args == NULL || args->size() < 2)
8664           this->report_error(_("not enough arguments"));
8665         else if (args->size() > 2)
8666           this->report_error(_("too many arguments"));
8667         else if (args->front()->is_error_expression()
8668                  || args->front()->type()->is_error()
8669                  || args->back()->is_error_expression()
8670                  || args->back()->type()->is_error())
8671           this->set_is_error();
8672         else if (!Type::are_identical(args->front()->type(),
8673                                       args->back()->type(), true, NULL))
8674           this->report_error(_("complex arguments must have identical types"));
8675         else if (args->front()->type()->float_type() == NULL)
8676           this->report_error(_("complex arguments must have "
8677                                "floating-point type"));
8678       }
8679       break;
8680
8681     default:
8682       go_unreachable();
8683     }
8684 }
8685
8686 // Return the tree for a builtin function.
8687
8688 tree
8689 Builtin_call_expression::do_get_tree(Translate_context* context)
8690 {
8691   Gogo* gogo = context->gogo();
8692   Location location = this->location();
8693   switch (this->code_)
8694     {
8695     case BUILTIN_INVALID:
8696     case BUILTIN_NEW:
8697     case BUILTIN_MAKE:
8698       go_unreachable();
8699
8700     case BUILTIN_LEN:
8701     case BUILTIN_CAP:
8702       {
8703         const Expression_list* args = this->args();
8704         go_assert(args != NULL && args->size() == 1);
8705         Expression* arg = *args->begin();
8706         Type* arg_type = arg->type();
8707
8708         if (this->seen_)
8709           {
8710             go_assert(saw_errors());
8711             return error_mark_node;
8712           }
8713         this->seen_ = true;
8714
8715         tree arg_tree = arg->get_tree(context);
8716
8717         this->seen_ = false;
8718
8719         if (arg_tree == error_mark_node)
8720           return error_mark_node;
8721
8722         if (arg_type->points_to() != NULL)
8723           {
8724             arg_type = arg_type->points_to();
8725             go_assert(arg_type->array_type() != NULL
8726                        && !arg_type->is_slice_type());
8727             go_assert(POINTER_TYPE_P(TREE_TYPE(arg_tree)));
8728             arg_tree = build_fold_indirect_ref(arg_tree);
8729           }
8730
8731         tree val_tree;
8732         if (this->code_ == BUILTIN_LEN)
8733           {
8734             if (arg_type->is_string_type())
8735               val_tree = String_type::length_tree(gogo, arg_tree);
8736             else if (arg_type->array_type() != NULL)
8737               {
8738                 if (this->seen_)
8739                   {
8740                     go_assert(saw_errors());
8741                     return error_mark_node;
8742                   }
8743                 this->seen_ = true;
8744                 val_tree = arg_type->array_type()->length_tree(gogo, arg_tree);
8745                 this->seen_ = false;
8746               }
8747             else if (arg_type->map_type() != NULL)
8748               {
8749                 tree arg_type_tree = type_to_tree(arg_type->get_backend(gogo));
8750                 static tree map_len_fndecl;
8751                 val_tree = Gogo::call_builtin(&map_len_fndecl,
8752                                               location,
8753                                               "__go_map_len",
8754                                               1,
8755                                               integer_type_node,
8756                                               arg_type_tree,
8757                                               arg_tree);
8758               }
8759             else if (arg_type->channel_type() != NULL)
8760               {
8761                 tree arg_type_tree = type_to_tree(arg_type->get_backend(gogo));
8762                 static tree chan_len_fndecl;
8763                 val_tree = Gogo::call_builtin(&chan_len_fndecl,
8764                                               location,
8765                                               "__go_chan_len",
8766                                               1,
8767                                               integer_type_node,
8768                                               arg_type_tree,
8769                                               arg_tree);
8770               }
8771             else
8772               go_unreachable();
8773           }
8774         else
8775           {
8776             if (arg_type->array_type() != NULL)
8777               {
8778                 if (this->seen_)
8779                   {
8780                     go_assert(saw_errors());
8781                     return error_mark_node;
8782                   }
8783                 this->seen_ = true;
8784                 val_tree = arg_type->array_type()->capacity_tree(gogo,
8785                                                                  arg_tree);
8786                 this->seen_ = false;
8787               }
8788             else if (arg_type->channel_type() != NULL)
8789               {
8790                 tree arg_type_tree = type_to_tree(arg_type->get_backend(gogo));
8791                 static tree chan_cap_fndecl;
8792                 val_tree = Gogo::call_builtin(&chan_cap_fndecl,
8793                                               location,
8794                                               "__go_chan_cap",
8795                                               1,
8796                                               integer_type_node,
8797                                               arg_type_tree,
8798                                               arg_tree);
8799               }
8800             else
8801               go_unreachable();
8802           }
8803
8804         if (val_tree == error_mark_node)
8805           return error_mark_node;
8806
8807         Type* int_type = Type::lookup_integer_type("int");
8808         tree type_tree = type_to_tree(int_type->get_backend(gogo));
8809         if (type_tree == TREE_TYPE(val_tree))
8810           return val_tree;
8811         else
8812           return fold(convert_to_integer(type_tree, val_tree));
8813       }
8814
8815     case BUILTIN_PRINT:
8816     case BUILTIN_PRINTLN:
8817       {
8818         const bool is_ln = this->code_ == BUILTIN_PRINTLN;
8819         tree stmt_list = NULL_TREE;
8820
8821         const Expression_list* call_args = this->args();
8822         if (call_args != NULL)
8823           {
8824             for (Expression_list::const_iterator p = call_args->begin();
8825                  p != call_args->end();
8826                  ++p)
8827               {
8828                 if (is_ln && p != call_args->begin())
8829                   {
8830                     static tree print_space_fndecl;
8831                     tree call = Gogo::call_builtin(&print_space_fndecl,
8832                                                    location,
8833                                                    "__go_print_space",
8834                                                    0,
8835                                                    void_type_node);
8836                     if (call == error_mark_node)
8837                       return error_mark_node;
8838                     append_to_statement_list(call, &stmt_list);
8839                   }
8840
8841                 Type* type = (*p)->type();
8842
8843                 tree arg = (*p)->get_tree(context);
8844                 if (arg == error_mark_node)
8845                   return error_mark_node;
8846
8847                 tree* pfndecl;
8848                 const char* fnname;
8849                 if (type->is_string_type())
8850                   {
8851                     static tree print_string_fndecl;
8852                     pfndecl = &print_string_fndecl;
8853                     fnname = "__go_print_string";
8854                   }
8855                 else if (type->integer_type() != NULL
8856                          && type->integer_type()->is_unsigned())
8857                   {
8858                     static tree print_uint64_fndecl;
8859                     pfndecl = &print_uint64_fndecl;
8860                     fnname = "__go_print_uint64";
8861                     Type* itype = Type::lookup_integer_type("uint64");
8862                     Btype* bitype = itype->get_backend(gogo);
8863                     arg = fold_convert_loc(location.gcc_location(),
8864                                            type_to_tree(bitype), arg);
8865                   }
8866                 else if (type->integer_type() != NULL)
8867                   {
8868                     static tree print_int64_fndecl;
8869                     pfndecl = &print_int64_fndecl;
8870                     fnname = "__go_print_int64";
8871                     Type* itype = Type::lookup_integer_type("int64");
8872                     Btype* bitype = itype->get_backend(gogo);
8873                     arg = fold_convert_loc(location.gcc_location(),
8874                                            type_to_tree(bitype), arg);
8875                   }
8876                 else if (type->float_type() != NULL)
8877                   {
8878                     static tree print_double_fndecl;
8879                     pfndecl = &print_double_fndecl;
8880                     fnname = "__go_print_double";
8881                     arg = fold_convert_loc(location.gcc_location(),
8882                                            double_type_node, arg);
8883                   }
8884                 else if (type->complex_type() != NULL)
8885                   {
8886                     static tree print_complex_fndecl;
8887                     pfndecl = &print_complex_fndecl;
8888                     fnname = "__go_print_complex";
8889                     arg = fold_convert_loc(location.gcc_location(),
8890                                            complex_double_type_node, arg);
8891                   }
8892                 else if (type->is_boolean_type())
8893                   {
8894                     static tree print_bool_fndecl;
8895                     pfndecl = &print_bool_fndecl;
8896                     fnname = "__go_print_bool";
8897                   }
8898                 else if (type->points_to() != NULL
8899                          || type->channel_type() != NULL
8900                          || type->map_type() != NULL
8901                          || type->function_type() != NULL)
8902                   {
8903                     static tree print_pointer_fndecl;
8904                     pfndecl = &print_pointer_fndecl;
8905                     fnname = "__go_print_pointer";
8906                     arg = fold_convert_loc(location.gcc_location(),
8907                                            ptr_type_node, arg);
8908                   }
8909                 else if (type->interface_type() != NULL)
8910                   {
8911                     if (type->interface_type()->is_empty())
8912                       {
8913                         static tree print_empty_interface_fndecl;
8914                         pfndecl = &print_empty_interface_fndecl;
8915                         fnname = "__go_print_empty_interface";
8916                       }
8917                     else
8918                       {
8919                         static tree print_interface_fndecl;
8920                         pfndecl = &print_interface_fndecl;
8921                         fnname = "__go_print_interface";
8922                       }
8923                   }
8924                 else if (type->is_slice_type())
8925                   {
8926                     static tree print_slice_fndecl;
8927                     pfndecl = &print_slice_fndecl;
8928                     fnname = "__go_print_slice";
8929                   }
8930                 else
8931                   go_unreachable();
8932
8933                 tree call = Gogo::call_builtin(pfndecl,
8934                                                location,
8935                                                fnname,
8936                                                1,
8937                                                void_type_node,
8938                                                TREE_TYPE(arg),
8939                                                arg);
8940                 if (call == error_mark_node)
8941                   return error_mark_node;
8942                 append_to_statement_list(call, &stmt_list);
8943               }
8944           }
8945
8946         if (is_ln)
8947           {
8948             static tree print_nl_fndecl;
8949             tree call = Gogo::call_builtin(&print_nl_fndecl,
8950                                            location,
8951                                            "__go_print_nl",
8952                                            0,
8953                                            void_type_node);
8954             if (call == error_mark_node)
8955               return error_mark_node;
8956             append_to_statement_list(call, &stmt_list);
8957           }
8958
8959         return stmt_list;
8960       }
8961
8962     case BUILTIN_PANIC:
8963       {
8964         const Expression_list* args = this->args();
8965         go_assert(args != NULL && args->size() == 1);
8966         Expression* arg = args->front();
8967         tree arg_tree = arg->get_tree(context);
8968         if (arg_tree == error_mark_node)
8969           return error_mark_node;
8970         Type *empty =
8971           Type::make_empty_interface_type(Linemap::predeclared_location());
8972         arg_tree = Expression::convert_for_assignment(context, empty,
8973                                                       arg->type(),
8974                                                       arg_tree, location);
8975         static tree panic_fndecl;
8976         tree call = Gogo::call_builtin(&panic_fndecl,
8977                                        location,
8978                                        "__go_panic",
8979                                        1,
8980                                        void_type_node,
8981                                        TREE_TYPE(arg_tree),
8982                                        arg_tree);
8983         if (call == error_mark_node)
8984           return error_mark_node;
8985         // This function will throw an exception.
8986         TREE_NOTHROW(panic_fndecl) = 0;
8987         // This function will not return.
8988         TREE_THIS_VOLATILE(panic_fndecl) = 1;
8989         return call;
8990       }
8991
8992     case BUILTIN_RECOVER:
8993       {
8994         // The argument is set when building recover thunks.  It's a
8995         // boolean value which is true if we can recover a value now.
8996         const Expression_list* args = this->args();
8997         go_assert(args != NULL && args->size() == 1);
8998         Expression* arg = args->front();
8999         tree arg_tree = arg->get_tree(context);
9000         if (arg_tree == error_mark_node)
9001           return error_mark_node;
9002
9003         Type *empty =
9004           Type::make_empty_interface_type(Linemap::predeclared_location());
9005         tree empty_tree = type_to_tree(empty->get_backend(context->gogo()));
9006
9007         Type* nil_type = Type::make_nil_type();
9008         Expression* nil = Expression::make_nil(location);
9009         tree nil_tree = nil->get_tree(context);
9010         tree empty_nil_tree = Expression::convert_for_assignment(context,
9011                                                                  empty,
9012                                                                  nil_type,
9013                                                                  nil_tree,
9014                                                                  location);
9015
9016         // We need to handle a deferred call to recover specially,
9017         // because it changes whether it can recover a panic or not.
9018         // See test7 in test/recover1.go.
9019         tree call;
9020         if (this->is_deferred())
9021           {
9022             static tree deferred_recover_fndecl;
9023             call = Gogo::call_builtin(&deferred_recover_fndecl,
9024                                       location,
9025                                       "__go_deferred_recover",
9026                                       0,
9027                                       empty_tree);
9028           }
9029         else
9030           {
9031             static tree recover_fndecl;
9032             call = Gogo::call_builtin(&recover_fndecl,
9033                                       location,
9034                                       "__go_recover",
9035                                       0,
9036                                       empty_tree);
9037           }
9038         if (call == error_mark_node)
9039           return error_mark_node;
9040         return fold_build3_loc(location.gcc_location(), COND_EXPR, empty_tree,
9041                                arg_tree, call, empty_nil_tree);
9042       }
9043
9044     case BUILTIN_CLOSE:
9045       {
9046         const Expression_list* args = this->args();
9047         go_assert(args != NULL && args->size() == 1);
9048         Expression* arg = args->front();
9049         tree arg_tree = arg->get_tree(context);
9050         if (arg_tree == error_mark_node)
9051           return error_mark_node;
9052         static tree close_fndecl;
9053         return Gogo::call_builtin(&close_fndecl,
9054                                   location,
9055                                   "__go_builtin_close",
9056                                   1,
9057                                   void_type_node,
9058                                   TREE_TYPE(arg_tree),
9059                                   arg_tree);
9060       }
9061
9062     case BUILTIN_SIZEOF:
9063     case BUILTIN_OFFSETOF:
9064     case BUILTIN_ALIGNOF:
9065       {
9066         mpz_t val;
9067         mpz_init(val);
9068         Type* dummy;
9069         bool b = this->integer_constant_value(true, val, &dummy);
9070         if (!b)
9071           {
9072             go_assert(saw_errors());
9073             return error_mark_node;
9074           }
9075         Type* int_type = Type::lookup_integer_type("int");
9076         tree type = type_to_tree(int_type->get_backend(gogo));
9077         tree ret = Expression::integer_constant_tree(val, type);
9078         mpz_clear(val);
9079         return ret;
9080       }
9081
9082     case BUILTIN_COPY:
9083       {
9084         const Expression_list* args = this->args();
9085         go_assert(args != NULL && args->size() == 2);
9086         Expression* arg1 = args->front();
9087         Expression* arg2 = args->back();
9088
9089         tree arg1_tree = arg1->get_tree(context);
9090         tree arg2_tree = arg2->get_tree(context);
9091         if (arg1_tree == error_mark_node || arg2_tree == error_mark_node)
9092           return error_mark_node;
9093
9094         Type* arg1_type = arg1->type();
9095         Array_type* at = arg1_type->array_type();
9096         arg1_tree = save_expr(arg1_tree);
9097         tree arg1_val = at->value_pointer_tree(gogo, arg1_tree);
9098         tree arg1_len = at->length_tree(gogo, arg1_tree);
9099         if (arg1_val == error_mark_node || arg1_len == error_mark_node)
9100           return error_mark_node;
9101
9102         Type* arg2_type = arg2->type();
9103         tree arg2_val;
9104         tree arg2_len;
9105         if (arg2_type->is_slice_type())
9106           {
9107             at = arg2_type->array_type();
9108             arg2_tree = save_expr(arg2_tree);
9109             arg2_val = at->value_pointer_tree(gogo, arg2_tree);
9110             arg2_len = at->length_tree(gogo, arg2_tree);
9111           }
9112         else
9113           {
9114             arg2_tree = save_expr(arg2_tree);
9115             arg2_val = String_type::bytes_tree(gogo, arg2_tree);
9116             arg2_len = String_type::length_tree(gogo, arg2_tree);
9117           }
9118         if (arg2_val == error_mark_node || arg2_len == error_mark_node)
9119           return error_mark_node;
9120
9121         arg1_len = save_expr(arg1_len);
9122         arg2_len = save_expr(arg2_len);
9123         tree len = fold_build3_loc(location.gcc_location(), COND_EXPR,
9124                                    TREE_TYPE(arg1_len),
9125                                    fold_build2_loc(location.gcc_location(),
9126                                                    LT_EXPR, boolean_type_node,
9127                                                    arg1_len, arg2_len),
9128                                    arg1_len, arg2_len);
9129         len = save_expr(len);
9130
9131         Type* element_type = at->element_type();
9132         Btype* element_btype = element_type->get_backend(gogo);
9133         tree element_type_tree = type_to_tree(element_btype);
9134         if (element_type_tree == error_mark_node)
9135           return error_mark_node;
9136         tree element_size = TYPE_SIZE_UNIT(element_type_tree);
9137         tree bytecount = fold_convert_loc(location.gcc_location(),
9138                                           TREE_TYPE(element_size), len);
9139         bytecount = fold_build2_loc(location.gcc_location(), MULT_EXPR,
9140                                     TREE_TYPE(element_size),
9141                                     bytecount, element_size);
9142         bytecount = fold_convert_loc(location.gcc_location(), size_type_node,
9143                                      bytecount);
9144
9145         arg1_val = fold_convert_loc(location.gcc_location(), ptr_type_node,
9146                                     arg1_val);
9147         arg2_val = fold_convert_loc(location.gcc_location(), ptr_type_node,
9148                                     arg2_val);
9149
9150         static tree copy_fndecl;
9151         tree call = Gogo::call_builtin(&copy_fndecl,
9152                                        location,
9153                                        "__go_copy",
9154                                        3,
9155                                        void_type_node,
9156                                        ptr_type_node,
9157                                        arg1_val,
9158                                        ptr_type_node,
9159                                        arg2_val,
9160                                        size_type_node,
9161                                        bytecount);
9162         if (call == error_mark_node)
9163           return error_mark_node;
9164
9165         return fold_build2_loc(location.gcc_location(), COMPOUND_EXPR,
9166                                TREE_TYPE(len), call, len);
9167       }
9168
9169     case BUILTIN_APPEND:
9170       {
9171         const Expression_list* args = this->args();
9172         go_assert(args != NULL && args->size() == 2);
9173         Expression* arg1 = args->front();
9174         Expression* arg2 = args->back();
9175
9176         tree arg1_tree = arg1->get_tree(context);
9177         tree arg2_tree = arg2->get_tree(context);
9178         if (arg1_tree == error_mark_node || arg2_tree == error_mark_node)
9179           return error_mark_node;
9180
9181         Array_type* at = arg1->type()->array_type();
9182         Type* element_type = at->element_type()->forwarded();
9183
9184         tree arg2_val;
9185         tree arg2_len;
9186         tree element_size;
9187         if (arg2->type()->is_string_type()
9188             && element_type->integer_type() != NULL
9189             && element_type->integer_type()->is_byte())
9190           {
9191             arg2_tree = save_expr(arg2_tree);
9192             arg2_val = String_type::bytes_tree(gogo, arg2_tree);
9193             arg2_len = String_type::length_tree(gogo, arg2_tree);
9194             element_size = size_int(1);
9195           }
9196         else
9197           {
9198             arg2_tree = Expression::convert_for_assignment(context, at,
9199                                                            arg2->type(),
9200                                                            arg2_tree,
9201                                                            location);
9202             if (arg2_tree == error_mark_node)
9203               return error_mark_node;
9204
9205             arg2_tree = save_expr(arg2_tree);
9206
9207              arg2_val = at->value_pointer_tree(gogo, arg2_tree);
9208              arg2_len = at->length_tree(gogo, arg2_tree);
9209
9210              Btype* element_btype = element_type->get_backend(gogo);
9211              tree element_type_tree = type_to_tree(element_btype);
9212              if (element_type_tree == error_mark_node)
9213                return error_mark_node;
9214              element_size = TYPE_SIZE_UNIT(element_type_tree);
9215           }
9216
9217         arg2_val = fold_convert_loc(location.gcc_location(), ptr_type_node,
9218                                     arg2_val);
9219         arg2_len = fold_convert_loc(location.gcc_location(), size_type_node,
9220                                     arg2_len);
9221         element_size = fold_convert_loc(location.gcc_location(), size_type_node,
9222                                         element_size);
9223
9224         if (arg2_val == error_mark_node
9225             || arg2_len == error_mark_node
9226             || element_size == error_mark_node)
9227           return error_mark_node;
9228
9229         // We rebuild the decl each time since the slice types may
9230         // change.
9231         tree append_fndecl = NULL_TREE;
9232         return Gogo::call_builtin(&append_fndecl,
9233                                   location,
9234                                   "__go_append",
9235                                   4,
9236                                   TREE_TYPE(arg1_tree),
9237                                   TREE_TYPE(arg1_tree),
9238                                   arg1_tree,
9239                                   ptr_type_node,
9240                                   arg2_val,
9241                                   size_type_node,
9242                                   arg2_len,
9243                                   size_type_node,
9244                                   element_size);
9245       }
9246
9247     case BUILTIN_REAL:
9248     case BUILTIN_IMAG:
9249       {
9250         const Expression_list* args = this->args();
9251         go_assert(args != NULL && args->size() == 1);
9252         Expression* arg = args->front();
9253         tree arg_tree = arg->get_tree(context);
9254         if (arg_tree == error_mark_node)
9255           return error_mark_node;
9256         go_assert(COMPLEX_FLOAT_TYPE_P(TREE_TYPE(arg_tree)));
9257         if (this->code_ == BUILTIN_REAL)
9258           return fold_build1_loc(location.gcc_location(), REALPART_EXPR,
9259                                  TREE_TYPE(TREE_TYPE(arg_tree)),
9260                                  arg_tree);
9261         else
9262           return fold_build1_loc(location.gcc_location(), IMAGPART_EXPR,
9263                                  TREE_TYPE(TREE_TYPE(arg_tree)),
9264                                  arg_tree);
9265       }
9266
9267     case BUILTIN_COMPLEX:
9268       {
9269         const Expression_list* args = this->args();
9270         go_assert(args != NULL && args->size() == 2);
9271         tree r = args->front()->get_tree(context);
9272         tree i = args->back()->get_tree(context);
9273         if (r == error_mark_node || i == error_mark_node)
9274           return error_mark_node;
9275         go_assert(TYPE_MAIN_VARIANT(TREE_TYPE(r))
9276                    == TYPE_MAIN_VARIANT(TREE_TYPE(i)));
9277         go_assert(SCALAR_FLOAT_TYPE_P(TREE_TYPE(r)));
9278         return fold_build2_loc(location.gcc_location(), COMPLEX_EXPR,
9279                                build_complex_type(TREE_TYPE(r)),
9280                                r, i);
9281       }
9282
9283     default:
9284       go_unreachable();
9285     }
9286 }
9287
9288 // We have to support exporting a builtin call expression, because
9289 // code can set a constant to the result of a builtin expression.
9290
9291 void
9292 Builtin_call_expression::do_export(Export* exp) const
9293 {
9294   bool ok = false;
9295
9296   mpz_t val;
9297   mpz_init(val);
9298   Type* dummy;
9299   if (this->integer_constant_value(true, val, &dummy))
9300     {
9301       Integer_expression::export_integer(exp, val);
9302       ok = true;
9303     }
9304   mpz_clear(val);
9305
9306   if (!ok)
9307     {
9308       mpfr_t fval;
9309       mpfr_init(fval);
9310       if (this->float_constant_value(fval, &dummy))
9311         {
9312           Float_expression::export_float(exp, fval);
9313           ok = true;
9314         }
9315       mpfr_clear(fval);
9316     }
9317
9318   if (!ok)
9319     {
9320       mpfr_t real;
9321       mpfr_t imag;
9322       mpfr_init(real);
9323       mpfr_init(imag);
9324       if (this->complex_constant_value(real, imag, &dummy))
9325         {
9326           Complex_expression::export_complex(exp, real, imag);
9327           ok = true;
9328         }
9329       mpfr_clear(real);
9330       mpfr_clear(imag);
9331     }
9332
9333   if (!ok)
9334     {
9335       error_at(this->location(), "value is not constant");
9336       return;
9337     }
9338
9339   // A trailing space lets us reliably identify the end of the number.
9340   exp->write_c_string(" ");
9341 }
9342
9343 // Class Call_expression.
9344
9345 // Traversal.
9346
9347 int
9348 Call_expression::do_traverse(Traverse* traverse)
9349 {
9350   if (Expression::traverse(&this->fn_, traverse) == TRAVERSE_EXIT)
9351     return TRAVERSE_EXIT;
9352   if (this->args_ != NULL)
9353     {
9354       if (this->args_->traverse(traverse) == TRAVERSE_EXIT)
9355         return TRAVERSE_EXIT;
9356     }
9357   return TRAVERSE_CONTINUE;
9358 }
9359
9360 // Lower a call statement.
9361
9362 Expression*
9363 Call_expression::do_lower(Gogo* gogo, Named_object* function,
9364                           Statement_inserter* inserter, int)
9365 {
9366   Location loc = this->location();
9367
9368   // A type cast can look like a function call.
9369   if (this->fn_->is_type_expression()
9370       && this->args_ != NULL
9371       && this->args_->size() == 1)
9372     return Expression::make_cast(this->fn_->type(), this->args_->front(),
9373                                  loc);
9374
9375   // Recognize a call to a builtin function.
9376   Func_expression* fne = this->fn_->func_expression();
9377   if (fne != NULL
9378       && fne->named_object()->is_function_declaration()
9379       && fne->named_object()->func_declaration_value()->type()->is_builtin())
9380     return new Builtin_call_expression(gogo, this->fn_, this->args_,
9381                                        this->is_varargs_, loc);
9382
9383   // Handle an argument which is a call to a function which returns
9384   // multiple results.
9385   if (this->args_ != NULL
9386       && this->args_->size() == 1
9387       && this->args_->front()->call_expression() != NULL
9388       && this->fn_->type()->function_type() != NULL)
9389     {
9390       Function_type* fntype = this->fn_->type()->function_type();
9391       size_t rc = this->args_->front()->call_expression()->result_count();
9392       if (rc > 1
9393           && fntype->parameters() != NULL
9394           && (fntype->parameters()->size() == rc
9395               || (fntype->is_varargs()
9396                   && fntype->parameters()->size() - 1 <= rc)))
9397         {
9398           Call_expression* call = this->args_->front()->call_expression();
9399           Expression_list* args = new Expression_list;
9400           for (size_t i = 0; i < rc; ++i)
9401             args->push_back(Expression::make_call_result(call, i));
9402           // We can't return a new call expression here, because this
9403           // one may be referenced by Call_result expressions.  We
9404           // also can't delete the old arguments, because we may still
9405           // traverse them somewhere up the call stack.  FIXME.
9406           this->args_ = args;
9407         }
9408     }
9409
9410   // If this call returns multiple results, create a temporary
9411   // variable for each result.
9412   size_t rc = this->result_count();
9413   if (rc > 1 && this->results_ == NULL)
9414     {
9415       std::vector<Temporary_statement*>* temps =
9416         new std::vector<Temporary_statement*>;
9417       temps->reserve(rc);
9418       const Typed_identifier_list* results =
9419         this->fn_->type()->function_type()->results();
9420       for (Typed_identifier_list::const_iterator p = results->begin();
9421            p != results->end();
9422            ++p)
9423         {
9424           Temporary_statement* temp = Statement::make_temporary(p->type(),
9425                                                                 NULL, loc);
9426           inserter->insert(temp);
9427           temps->push_back(temp);
9428         }
9429       this->results_ = temps;
9430     }
9431
9432   // Handle a call to a varargs function by packaging up the extra
9433   // parameters.
9434   if (this->fn_->type()->function_type() != NULL
9435       && this->fn_->type()->function_type()->is_varargs())
9436     {
9437       Function_type* fntype = this->fn_->type()->function_type();
9438       const Typed_identifier_list* parameters = fntype->parameters();
9439       go_assert(parameters != NULL && !parameters->empty());
9440       Type* varargs_type = parameters->back().type();
9441       this->lower_varargs(gogo, function, inserter, varargs_type,
9442                           parameters->size());
9443     }
9444
9445   // If this is call to a method, call the method directly passing the
9446   // object as the first parameter.
9447   Bound_method_expression* bme = this->fn_->bound_method_expression();
9448   if (bme != NULL)
9449     {
9450       Named_object* method = bme->method();
9451       Expression* first_arg = bme->first_argument();
9452
9453       // We always pass a pointer when calling a method.
9454       if (first_arg->type()->points_to() == NULL
9455           && !first_arg->type()->is_error())
9456         {
9457           first_arg = Expression::make_unary(OPERATOR_AND, first_arg, loc);
9458           // We may need to create a temporary variable so that we can
9459           // take the address.  We can't do that here because it will
9460           // mess up the order of evaluation.
9461           Unary_expression* ue = static_cast<Unary_expression*>(first_arg);
9462           ue->set_create_temp();
9463         }
9464
9465       // If we are calling a method which was inherited from an
9466       // embedded struct, and the method did not get a stub, then the
9467       // first type may be wrong.
9468       Type* fatype = bme->first_argument_type();
9469       if (fatype != NULL)
9470         {
9471           if (fatype->points_to() == NULL)
9472             fatype = Type::make_pointer_type(fatype);
9473           first_arg = Expression::make_unsafe_cast(fatype, first_arg, loc);
9474         }
9475
9476       Expression_list* new_args = new Expression_list();
9477       new_args->push_back(first_arg);
9478       if (this->args_ != NULL)
9479         {
9480           for (Expression_list::const_iterator p = this->args_->begin();
9481                p != this->args_->end();
9482                ++p)
9483             new_args->push_back(*p);
9484         }
9485
9486       // We have to change in place because this structure may be
9487       // referenced by Call_result_expressions.  We can't delete the
9488       // old arguments, because we may be traversing them up in some
9489       // caller.  FIXME.
9490       this->args_ = new_args;
9491       this->fn_ = Expression::make_func_reference(method, NULL,
9492                                                   bme->location());
9493     }
9494
9495   return this;
9496 }
9497
9498 // Lower a call to a varargs function.  FUNCTION is the function in
9499 // which the call occurs--it's not the function we are calling.
9500 // VARARGS_TYPE is the type of the varargs parameter, a slice type.
9501 // PARAM_COUNT is the number of parameters of the function we are
9502 // calling; the last of these parameters will be the varargs
9503 // parameter.
9504
9505 void
9506 Call_expression::lower_varargs(Gogo* gogo, Named_object* function,
9507                                Statement_inserter* inserter,
9508                                Type* varargs_type, size_t param_count)
9509 {
9510   if (this->varargs_are_lowered_)
9511     return;
9512
9513   Location loc = this->location();
9514
9515   go_assert(param_count > 0);
9516   go_assert(varargs_type->is_slice_type());
9517
9518   size_t arg_count = this->args_ == NULL ? 0 : this->args_->size();
9519   if (arg_count < param_count - 1)
9520     {
9521       // Not enough arguments; will be caught in check_types.
9522       return;
9523     }
9524
9525   Expression_list* old_args = this->args_;
9526   Expression_list* new_args = new Expression_list();
9527   bool push_empty_arg = false;
9528   if (old_args == NULL || old_args->empty())
9529     {
9530       go_assert(param_count == 1);
9531       push_empty_arg = true;
9532     }
9533   else
9534     {
9535       Expression_list::const_iterator pa;
9536       int i = 1;
9537       for (pa = old_args->begin(); pa != old_args->end(); ++pa, ++i)
9538         {
9539           if (static_cast<size_t>(i) == param_count)
9540             break;
9541           new_args->push_back(*pa);
9542         }
9543
9544       // We have reached the varargs parameter.
9545
9546       bool issued_error = false;
9547       if (pa == old_args->end())
9548         push_empty_arg = true;
9549       else if (pa + 1 == old_args->end() && this->is_varargs_)
9550         new_args->push_back(*pa);
9551       else if (this->is_varargs_)
9552         {
9553           this->report_error(_("too many arguments"));
9554           return;
9555         }
9556       else
9557         {
9558           Type* element_type = varargs_type->array_type()->element_type();
9559           Expression_list* vals = new Expression_list;
9560           for (; pa != old_args->end(); ++pa, ++i)
9561             {
9562               // Check types here so that we get a better message.
9563               Type* patype = (*pa)->type();
9564               Location paloc = (*pa)->location();
9565               if (!this->check_argument_type(i, element_type, patype,
9566                                              paloc, issued_error))
9567                 continue;
9568               vals->push_back(*pa);
9569             }
9570           Expression* val =
9571             Expression::make_slice_composite_literal(varargs_type, vals, loc);
9572           gogo->lower_expression(function, inserter, &val);
9573           new_args->push_back(val);
9574         }
9575     }
9576
9577   if (push_empty_arg)
9578     new_args->push_back(Expression::make_nil(loc));
9579
9580   // We can't return a new call expression here, because this one may
9581   // be referenced by Call_result expressions.  FIXME.  We can't
9582   // delete OLD_ARGS because we may have both a Call_expression and a
9583   // Builtin_call_expression which refer to them.  FIXME.
9584   this->args_ = new_args;
9585   this->varargs_are_lowered_ = true;
9586 }
9587
9588 // Get the function type.  This can return NULL in error cases.
9589
9590 Function_type*
9591 Call_expression::get_function_type() const
9592 {
9593   return this->fn_->type()->function_type();
9594 }
9595
9596 // Return the number of values which this call will return.
9597
9598 size_t
9599 Call_expression::result_count() const
9600 {
9601   const Function_type* fntype = this->get_function_type();
9602   if (fntype == NULL)
9603     return 0;
9604   if (fntype->results() == NULL)
9605     return 0;
9606   return fntype->results()->size();
9607 }
9608
9609 // Return the temporary which holds a result.
9610
9611 Temporary_statement*
9612 Call_expression::result(size_t i) const
9613 {
9614   go_assert(this->results_ != NULL
9615             && this->results_->size() > i);
9616   return (*this->results_)[i];
9617 }
9618
9619 // Return whether this is a call to the predeclared function recover.
9620
9621 bool
9622 Call_expression::is_recover_call() const
9623 {
9624   return this->do_is_recover_call();
9625 }
9626
9627 // Set the argument to the recover function.
9628
9629 void
9630 Call_expression::set_recover_arg(Expression* arg)
9631 {
9632   this->do_set_recover_arg(arg);
9633 }
9634
9635 // Virtual functions also implemented by Builtin_call_expression.
9636
9637 bool
9638 Call_expression::do_is_recover_call() const
9639 {
9640   return false;
9641 }
9642
9643 void
9644 Call_expression::do_set_recover_arg(Expression*)
9645 {
9646   go_unreachable();
9647 }
9648
9649 // We have found an error with this call expression; return true if
9650 // we should report it.
9651
9652 bool
9653 Call_expression::issue_error()
9654 {
9655   if (this->issued_error_)
9656     return false;
9657   else
9658     {
9659       this->issued_error_ = true;
9660       return true;
9661     }
9662 }
9663
9664 // Get the type.
9665
9666 Type*
9667 Call_expression::do_type()
9668 {
9669   if (this->type_ != NULL)
9670     return this->type_;
9671
9672   Type* ret;
9673   Function_type* fntype = this->get_function_type();
9674   if (fntype == NULL)
9675     return Type::make_error_type();
9676
9677   const Typed_identifier_list* results = fntype->results();
9678   if (results == NULL)
9679     ret = Type::make_void_type();
9680   else if (results->size() == 1)
9681     ret = results->begin()->type();
9682   else
9683     ret = Type::make_call_multiple_result_type(this);
9684
9685   this->type_ = ret;
9686
9687   return this->type_;
9688 }
9689
9690 // Determine types for a call expression.  We can use the function
9691 // parameter types to set the types of the arguments.
9692
9693 void
9694 Call_expression::do_determine_type(const Type_context*)
9695 {
9696   if (!this->determining_types())
9697     return;
9698
9699   this->fn_->determine_type_no_context();
9700   Function_type* fntype = this->get_function_type();
9701   const Typed_identifier_list* parameters = NULL;
9702   if (fntype != NULL)
9703     parameters = fntype->parameters();
9704   if (this->args_ != NULL)
9705     {
9706       Typed_identifier_list::const_iterator pt;
9707       if (parameters != NULL)
9708         pt = parameters->begin();
9709       bool first = true;
9710       for (Expression_list::const_iterator pa = this->args_->begin();
9711            pa != this->args_->end();
9712            ++pa)
9713         {
9714           if (first)
9715             {
9716               first = false;
9717               // If this is a method, the first argument is the
9718               // receiver.
9719               if (fntype != NULL && fntype->is_method())
9720                 {
9721                   Type* rtype = fntype->receiver()->type();
9722                   // The receiver is always passed as a pointer.
9723                   if (rtype->points_to() == NULL)
9724                     rtype = Type::make_pointer_type(rtype);
9725                   Type_context subcontext(rtype, false);
9726                   (*pa)->determine_type(&subcontext);
9727                   continue;
9728                 }
9729             }
9730
9731           if (parameters != NULL && pt != parameters->end())
9732             {
9733               Type_context subcontext(pt->type(), false);
9734               (*pa)->determine_type(&subcontext);
9735               ++pt;
9736             }
9737           else
9738             (*pa)->determine_type_no_context();
9739         }
9740     }
9741 }
9742
9743 // Called when determining types for a Call_expression.  Return true
9744 // if we should go ahead, false if they have already been determined.
9745
9746 bool
9747 Call_expression::determining_types()
9748 {
9749   if (this->types_are_determined_)
9750     return false;
9751   else
9752     {
9753       this->types_are_determined_ = true;
9754       return true;
9755     }
9756 }
9757
9758 // Check types for parameter I.
9759
9760 bool
9761 Call_expression::check_argument_type(int i, const Type* parameter_type,
9762                                      const Type* argument_type,
9763                                      Location argument_location,
9764                                      bool issued_error)
9765 {
9766   std::string reason;
9767   bool ok;
9768   if (this->are_hidden_fields_ok_)
9769     ok = Type::are_assignable_hidden_ok(parameter_type, argument_type,
9770                                         &reason);
9771   else
9772     ok = Type::are_assignable(parameter_type, argument_type, &reason);
9773   if (!ok)
9774     {
9775       if (!issued_error)
9776         {
9777           if (reason.empty())
9778             error_at(argument_location, "argument %d has incompatible type", i);
9779           else
9780             error_at(argument_location,
9781                      "argument %d has incompatible type (%s)",
9782                      i, reason.c_str());
9783         }
9784       this->set_is_error();
9785       return false;
9786     }
9787   return true;
9788 }
9789
9790 // Check types.
9791
9792 void
9793 Call_expression::do_check_types(Gogo*)
9794 {
9795   Function_type* fntype = this->get_function_type();
9796   if (fntype == NULL)
9797     {
9798       if (!this->fn_->type()->is_error())
9799         this->report_error(_("expected function"));
9800       return;
9801     }
9802
9803   bool is_method = fntype->is_method();
9804   if (is_method)
9805     {
9806       go_assert(this->args_ != NULL && !this->args_->empty());
9807       Type* rtype = fntype->receiver()->type();
9808       Expression* first_arg = this->args_->front();
9809       // The language permits copying hidden fields for a method
9810       // receiver.  We dereference the values since receivers are
9811       // always passed as pointers.
9812       std::string reason;
9813       if (!Type::are_assignable_hidden_ok(rtype->deref(),
9814                                           first_arg->type()->deref(),
9815                                           &reason))
9816         {
9817           if (reason.empty())
9818             this->report_error(_("incompatible type for receiver"));
9819           else
9820             {
9821               error_at(this->location(),
9822                        "incompatible type for receiver (%s)",
9823                        reason.c_str());
9824               this->set_is_error();
9825             }
9826         }
9827     }
9828
9829   // Note that varargs was handled by the lower_varargs() method, so
9830   // we don't have to worry about it here.
9831
9832   const Typed_identifier_list* parameters = fntype->parameters();
9833   if (this->args_ == NULL)
9834     {
9835       if (parameters != NULL && !parameters->empty())
9836         this->report_error(_("not enough arguments"));
9837     }
9838   else if (parameters == NULL)
9839     {
9840       if (!is_method || this->args_->size() > 1)
9841         this->report_error(_("too many arguments"));
9842     }
9843   else
9844     {
9845       int i = 0;
9846       Expression_list::const_iterator pa = this->args_->begin();
9847       if (is_method)
9848         ++pa;
9849       for (Typed_identifier_list::const_iterator pt = parameters->begin();
9850            pt != parameters->end();
9851            ++pt, ++pa, ++i)
9852         {
9853           if (pa == this->args_->end())
9854             {
9855               this->report_error(_("not enough arguments"));
9856               return;
9857             }
9858           this->check_argument_type(i + 1, pt->type(), (*pa)->type(),
9859                                     (*pa)->location(), false);
9860         }
9861       if (pa != this->args_->end())
9862         this->report_error(_("too many arguments"));
9863     }
9864 }
9865
9866 // Return whether we have to use a temporary variable to ensure that
9867 // we evaluate this call expression in order.  If the call returns no
9868 // results then it will inevitably be executed last.
9869
9870 bool
9871 Call_expression::do_must_eval_in_order() const
9872 {
9873   return this->result_count() > 0;
9874 }
9875
9876 // Get the function and the first argument to use when calling an
9877 // interface method.
9878
9879 tree
9880 Call_expression::interface_method_function(
9881     Translate_context* context,
9882     Interface_field_reference_expression* interface_method,
9883     tree* first_arg_ptr)
9884 {
9885   tree expr = interface_method->expr()->get_tree(context);
9886   if (expr == error_mark_node)
9887     return error_mark_node;
9888   expr = save_expr(expr);
9889   tree first_arg = interface_method->get_underlying_object_tree(context, expr);
9890   if (first_arg == error_mark_node)
9891     return error_mark_node;
9892   *first_arg_ptr = first_arg;
9893   return interface_method->get_function_tree(context, expr);
9894 }
9895
9896 // Build the call expression.
9897
9898 tree
9899 Call_expression::do_get_tree(Translate_context* context)
9900 {
9901   if (this->tree_ != NULL_TREE)
9902     return this->tree_;
9903
9904   Function_type* fntype = this->get_function_type();
9905   if (fntype == NULL)
9906     return error_mark_node;
9907
9908   if (this->fn_->is_error_expression())
9909     return error_mark_node;
9910
9911   Gogo* gogo = context->gogo();
9912   Location location = this->location();
9913
9914   Func_expression* func = this->fn_->func_expression();
9915   Interface_field_reference_expression* interface_method =
9916     this->fn_->interface_field_reference_expression();
9917   const bool has_closure = func != NULL && func->closure() != NULL;
9918   const bool is_interface_method = interface_method != NULL;
9919
9920   int nargs;
9921   tree* args;
9922   if (this->args_ == NULL || this->args_->empty())
9923     {
9924       nargs = is_interface_method ? 1 : 0;
9925       args = nargs == 0 ? NULL : new tree[nargs];
9926     }
9927   else if (fntype->parameters() == NULL || fntype->parameters()->empty())
9928     {
9929       // Passing a receiver parameter.
9930       go_assert(!is_interface_method
9931                 && fntype->is_method()
9932                 && this->args_->size() == 1);
9933       nargs = 1;
9934       args = new tree[nargs];
9935       args[0] = this->args_->front()->get_tree(context);
9936     }
9937   else
9938     {
9939       const Typed_identifier_list* params = fntype->parameters();
9940
9941       nargs = this->args_->size();
9942       int i = is_interface_method ? 1 : 0;
9943       nargs += i;
9944       args = new tree[nargs];
9945
9946       Typed_identifier_list::const_iterator pp = params->begin();
9947       Expression_list::const_iterator pe = this->args_->begin();
9948       if (!is_interface_method && fntype->is_method())
9949         {
9950           args[i] = (*pe)->get_tree(context);
9951           ++pe;
9952           ++i;
9953         }
9954       for (; pe != this->args_->end(); ++pe, ++pp, ++i)
9955         {
9956           go_assert(pp != params->end());
9957           tree arg_val = (*pe)->get_tree(context);
9958           args[i] = Expression::convert_for_assignment(context,
9959                                                        pp->type(),
9960                                                        (*pe)->type(),
9961                                                        arg_val,
9962                                                        location);
9963           if (args[i] == error_mark_node)
9964             {
9965               delete[] args;
9966               return error_mark_node;
9967             }
9968         }
9969       go_assert(pp == params->end());
9970       go_assert(i == nargs);
9971     }
9972
9973   tree rettype = TREE_TYPE(TREE_TYPE(type_to_tree(fntype->get_backend(gogo))));
9974   if (rettype == error_mark_node)
9975     {
9976       delete[] args;
9977       return error_mark_node;
9978     }
9979
9980   tree fn;
9981   if (has_closure)
9982     fn = func->get_tree_without_closure(gogo);
9983   else if (!is_interface_method)
9984     fn = this->fn_->get_tree(context);
9985   else
9986     fn = this->interface_method_function(context, interface_method, &args[0]);
9987
9988   if (fn == error_mark_node || TREE_TYPE(fn) == error_mark_node)
9989     {
9990       delete[] args;
9991       return error_mark_node;
9992     }
9993
9994   tree fndecl = fn;
9995   if (TREE_CODE(fndecl) == ADDR_EXPR)
9996     fndecl = TREE_OPERAND(fndecl, 0);
9997
9998   // Add a type cast in case the type of the function is a recursive
9999   // type which refers to itself.
10000   if (!DECL_P(fndecl) || !DECL_IS_BUILTIN(fndecl))
10001     {
10002       tree fnt = type_to_tree(fntype->get_backend(gogo));
10003       if (fnt == error_mark_node)
10004         return error_mark_node;
10005       fn = fold_convert_loc(location.gcc_location(), fnt, fn);
10006     }
10007
10008   // This is to support builtin math functions when using 80387 math.
10009   tree excess_type = NULL_TREE;
10010   if (TREE_CODE(fndecl) == FUNCTION_DECL
10011       && DECL_IS_BUILTIN(fndecl)
10012       && DECL_BUILT_IN_CLASS(fndecl) == BUILT_IN_NORMAL
10013       && nargs > 0
10014       && ((SCALAR_FLOAT_TYPE_P(rettype)
10015            && SCALAR_FLOAT_TYPE_P(TREE_TYPE(args[0])))
10016           || (COMPLEX_FLOAT_TYPE_P(rettype)
10017               && COMPLEX_FLOAT_TYPE_P(TREE_TYPE(args[0])))))
10018     {
10019       excess_type = excess_precision_type(TREE_TYPE(args[0]));
10020       if (excess_type != NULL_TREE)
10021         {
10022           tree excess_fndecl = mathfn_built_in(excess_type,
10023                                                DECL_FUNCTION_CODE(fndecl));
10024           if (excess_fndecl == NULL_TREE)
10025             excess_type = NULL_TREE;
10026           else
10027             {
10028               fn = build_fold_addr_expr_loc(location.gcc_location(),
10029                                             excess_fndecl);
10030               for (int i = 0; i < nargs; ++i)
10031                 {
10032                   if (SCALAR_FLOAT_TYPE_P(TREE_TYPE(args[i]))
10033                       || COMPLEX_FLOAT_TYPE_P(TREE_TYPE(args[i])))
10034                     args[i] = ::convert(excess_type, args[i]);
10035                 }
10036             }
10037         }
10038     }
10039
10040   tree ret = build_call_array(excess_type != NULL_TREE ? excess_type : rettype,
10041                               fn, nargs, args);
10042   delete[] args;
10043
10044   SET_EXPR_LOCATION(ret, location.gcc_location());
10045
10046   if (has_closure)
10047     {
10048       tree closure_tree = func->closure()->get_tree(context);
10049       if (closure_tree != error_mark_node)
10050         CALL_EXPR_STATIC_CHAIN(ret) = closure_tree;
10051     }
10052
10053   // If this is a recursive function type which returns itself, as in
10054   //   type F func() F
10055   // we have used ptr_type_node for the return type.  Add a cast here
10056   // to the correct type.
10057   if (TREE_TYPE(ret) == ptr_type_node)
10058     {
10059       tree t = type_to_tree(this->type()->base()->get_backend(gogo));
10060       ret = fold_convert_loc(location.gcc_location(), t, ret);
10061     }
10062
10063   if (excess_type != NULL_TREE)
10064     {
10065       // Calling convert here can undo our excess precision change.
10066       // That may or may not be a bug in convert_to_real.
10067       ret = build1(NOP_EXPR, rettype, ret);
10068     }
10069
10070   if (this->results_ != NULL)
10071     ret = this->set_results(context, ret);
10072
10073   this->tree_ = ret;
10074
10075   return ret;
10076 }
10077
10078 // Set the result variables if this call returns multiple results.
10079
10080 tree
10081 Call_expression::set_results(Translate_context* context, tree call_tree)
10082 {
10083   tree stmt_list = NULL_TREE;
10084
10085   call_tree = save_expr(call_tree);
10086
10087   if (TREE_CODE(TREE_TYPE(call_tree)) != RECORD_TYPE)
10088     {
10089       go_assert(saw_errors());
10090       return call_tree;
10091     }
10092
10093   Location loc = this->location();
10094   tree field = TYPE_FIELDS(TREE_TYPE(call_tree));
10095   size_t rc = this->result_count();
10096   for (size_t i = 0; i < rc; ++i, field = DECL_CHAIN(field))
10097     {
10098       go_assert(field != NULL_TREE);
10099
10100       Temporary_statement* temp = this->result(i);
10101       Temporary_reference_expression* ref =
10102         Expression::make_temporary_reference(temp, loc);
10103       ref->set_is_lvalue();
10104       tree temp_tree = ref->get_tree(context);
10105       if (temp_tree == error_mark_node)
10106         continue;
10107
10108       tree val_tree = build3_loc(loc.gcc_location(), COMPONENT_REF,
10109                                  TREE_TYPE(field), call_tree, field, NULL_TREE);
10110       tree set_tree = build2_loc(loc.gcc_location(), MODIFY_EXPR,
10111                                  void_type_node, temp_tree, val_tree);
10112
10113       append_to_statement_list(set_tree, &stmt_list);
10114     }
10115   go_assert(field == NULL_TREE);
10116
10117   return save_expr(stmt_list);
10118 }
10119
10120 // Dump ast representation for a call expressin.
10121
10122 void
10123 Call_expression::do_dump_expression(Ast_dump_context* ast_dump_context) const
10124 {
10125   this->fn_->dump_expression(ast_dump_context);
10126   ast_dump_context->ostream() << "(";
10127   if (args_ != NULL)
10128     ast_dump_context->dump_expression_list(this->args_);
10129
10130   ast_dump_context->ostream() << ") ";
10131 }
10132
10133 // Make a call expression.
10134
10135 Call_expression*
10136 Expression::make_call(Expression* fn, Expression_list* args, bool is_varargs,
10137                       Location location)
10138 {
10139   return new Call_expression(fn, args, is_varargs, location);
10140 }
10141
10142 // A single result from a call which returns multiple results.
10143
10144 class Call_result_expression : public Expression
10145 {
10146  public:
10147   Call_result_expression(Call_expression* call, unsigned int index)
10148     : Expression(EXPRESSION_CALL_RESULT, call->location()),
10149       call_(call), index_(index)
10150   { }
10151
10152  protected:
10153   int
10154   do_traverse(Traverse*);
10155
10156   Type*
10157   do_type();
10158
10159   void
10160   do_determine_type(const Type_context*);
10161
10162   void
10163   do_check_types(Gogo*);
10164
10165   Expression*
10166   do_copy()
10167   {
10168     return new Call_result_expression(this->call_->call_expression(),
10169                                       this->index_);
10170   }
10171
10172   bool
10173   do_must_eval_in_order() const
10174   { return true; }
10175
10176   tree
10177   do_get_tree(Translate_context*);
10178
10179   void
10180   do_dump_expression(Ast_dump_context*) const;
10181
10182  private:
10183   // The underlying call expression.
10184   Expression* call_;
10185   // Which result we want.
10186   unsigned int index_;
10187 };
10188
10189 // Traverse a call result.
10190
10191 int
10192 Call_result_expression::do_traverse(Traverse* traverse)
10193 {
10194   if (traverse->remember_expression(this->call_))
10195     {
10196       // We have already traversed the call expression.
10197       return TRAVERSE_CONTINUE;
10198     }
10199   return Expression::traverse(&this->call_, traverse);
10200 }
10201
10202 // Get the type.
10203
10204 Type*
10205 Call_result_expression::do_type()
10206 {
10207   if (this->classification() == EXPRESSION_ERROR)
10208     return Type::make_error_type();
10209
10210   // THIS->CALL_ can be replaced with a temporary reference due to
10211   // Call_expression::do_must_eval_in_order when there is an error.
10212   Call_expression* ce = this->call_->call_expression();
10213   if (ce == NULL)
10214     {
10215       this->set_is_error();
10216       return Type::make_error_type();
10217     }
10218   Function_type* fntype = ce->get_function_type();
10219   if (fntype == NULL)
10220     {
10221       if (ce->issue_error())
10222         {
10223           if (!ce->fn()->type()->is_error())
10224             this->report_error(_("expected function"));
10225         }
10226       this->set_is_error();
10227       return Type::make_error_type();
10228     }
10229   const Typed_identifier_list* results = fntype->results();
10230   if (results == NULL || results->size() < 2)
10231     {
10232       if (ce->issue_error())
10233         this->report_error(_("number of results does not match "
10234                              "number of values"));
10235       return Type::make_error_type();
10236     }
10237   Typed_identifier_list::const_iterator pr = results->begin();
10238   for (unsigned int i = 0; i < this->index_; ++i)
10239     {
10240       if (pr == results->end())
10241         break;
10242       ++pr;
10243     }
10244   if (pr == results->end())
10245     {
10246       if (ce->issue_error())
10247         this->report_error(_("number of results does not match "
10248                              "number of values"));
10249       return Type::make_error_type();
10250     }
10251   return pr->type();
10252 }
10253
10254 // Check the type.  Just make sure that we trigger the warning in
10255 // do_type.
10256
10257 void
10258 Call_result_expression::do_check_types(Gogo*)
10259 {
10260   this->type();
10261 }
10262
10263 // Determine the type.  We have nothing to do here, but the 0 result
10264 // needs to pass down to the caller.
10265
10266 void
10267 Call_result_expression::do_determine_type(const Type_context*)
10268 {
10269   this->call_->determine_type_no_context();
10270 }
10271
10272 // Return the tree.  We just refer to the temporary set by the call
10273 // expression.  We don't do this at lowering time because it makes it
10274 // hard to evaluate the call at the right time.
10275
10276 tree
10277 Call_result_expression::do_get_tree(Translate_context* context)
10278 {
10279   Call_expression* ce = this->call_->call_expression();
10280   go_assert(ce != NULL);
10281   Temporary_statement* ts = ce->result(this->index_);
10282   Expression* ref = Expression::make_temporary_reference(ts, this->location());
10283   return ref->get_tree(context);
10284 }
10285
10286 // Dump ast representation for a call result expression.
10287
10288 void
10289 Call_result_expression::do_dump_expression(Ast_dump_context* ast_dump_context)
10290     const
10291 {
10292   // FIXME: Wouldn't it be better if the call is assigned to a temporary
10293   // (struct) and the fields are referenced instead.
10294   ast_dump_context->ostream() << this->index_ << "@(";
10295   ast_dump_context->dump_expression(this->call_);
10296   ast_dump_context->ostream() << ")";
10297 }
10298
10299 // Make a reference to a single result of a call which returns
10300 // multiple results.
10301
10302 Expression*
10303 Expression::make_call_result(Call_expression* call, unsigned int index)
10304 {
10305   return new Call_result_expression(call, index);
10306 }
10307
10308 // Class Index_expression.
10309
10310 // Traversal.
10311
10312 int
10313 Index_expression::do_traverse(Traverse* traverse)
10314 {
10315   if (Expression::traverse(&this->left_, traverse) == TRAVERSE_EXIT
10316       || Expression::traverse(&this->start_, traverse) == TRAVERSE_EXIT
10317       || (this->end_ != NULL
10318           && Expression::traverse(&this->end_, traverse) == TRAVERSE_EXIT))
10319     return TRAVERSE_EXIT;
10320   return TRAVERSE_CONTINUE;
10321 }
10322
10323 // Lower an index expression.  This converts the generic index
10324 // expression into an array index, a string index, or a map index.
10325
10326 Expression*
10327 Index_expression::do_lower(Gogo*, Named_object*, Statement_inserter*, int)
10328 {
10329   Location location = this->location();
10330   Expression* left = this->left_;
10331   Expression* start = this->start_;
10332   Expression* end = this->end_;
10333
10334   Type* type = left->type();
10335   if (type->is_error())
10336     return Expression::make_error(location);
10337   else if (left->is_type_expression())
10338     {
10339       error_at(location, "attempt to index type expression");
10340       return Expression::make_error(location);
10341     }
10342   else if (type->array_type() != NULL)
10343     return Expression::make_array_index(left, start, end, location);
10344   else if (type->points_to() != NULL
10345            && type->points_to()->array_type() != NULL
10346            && !type->points_to()->is_slice_type())
10347     {
10348       Expression* deref = Expression::make_unary(OPERATOR_MULT, left,
10349                                                  location);
10350       return Expression::make_array_index(deref, start, end, location);
10351     }
10352   else if (type->is_string_type())
10353     return Expression::make_string_index(left, start, end, location);
10354   else if (type->map_type() != NULL)
10355     {
10356       if (end != NULL)
10357         {
10358           error_at(location, "invalid slice of map");
10359           return Expression::make_error(location);
10360         }
10361       Map_index_expression* ret = Expression::make_map_index(left, start,
10362                                                              location);
10363       if (this->is_lvalue_)
10364         ret->set_is_lvalue();
10365       return ret;
10366     }
10367   else
10368     {
10369       error_at(location,
10370                "attempt to index object which is not array, string, or map");
10371       return Expression::make_error(location);
10372     }
10373 }
10374
10375 // Write an indexed expression (expr[expr:expr] or expr[expr]) to a
10376 // dump context
10377
10378 void
10379 Index_expression::dump_index_expression(Ast_dump_context* ast_dump_context,
10380                                         const Expression* expr,
10381                                         const Expression* start,
10382                                         const Expression* end)
10383 {
10384   expr->dump_expression(ast_dump_context);
10385   ast_dump_context->ostream() << "[";
10386   start->dump_expression(ast_dump_context);
10387   if (end != NULL)
10388     {
10389       ast_dump_context->ostream() << ":";
10390       end->dump_expression(ast_dump_context);
10391     }
10392   ast_dump_context->ostream() << "]";
10393 }
10394
10395 // Dump ast representation for an index expression.
10396
10397 void
10398 Index_expression::do_dump_expression(Ast_dump_context* ast_dump_context)
10399     const
10400 {
10401   Index_expression::dump_index_expression(ast_dump_context, this->left_,
10402                                           this->start_, this->end_);
10403 }
10404
10405 // Make an index expression.
10406
10407 Expression*
10408 Expression::make_index(Expression* left, Expression* start, Expression* end,
10409                        Location location)
10410 {
10411   return new Index_expression(left, start, end, location);
10412 }
10413
10414 // An array index.  This is used for both indexing and slicing.
10415
10416 class Array_index_expression : public Expression
10417 {
10418  public:
10419   Array_index_expression(Expression* array, Expression* start,
10420                          Expression* end, Location location)
10421     : Expression(EXPRESSION_ARRAY_INDEX, location),
10422       array_(array), start_(start), end_(end), type_(NULL)
10423   { }
10424
10425  protected:
10426   int
10427   do_traverse(Traverse*);
10428
10429   Type*
10430   do_type();
10431
10432   void
10433   do_determine_type(const Type_context*);
10434
10435   void
10436   do_check_types(Gogo*);
10437
10438   Expression*
10439   do_copy()
10440   {
10441     return Expression::make_array_index(this->array_->copy(),
10442                                         this->start_->copy(),
10443                                         (this->end_ == NULL
10444                                          ? NULL
10445                                          : this->end_->copy()),
10446                                         this->location());
10447   }
10448
10449   bool
10450   do_must_eval_subexpressions_in_order(int* skip) const
10451   {
10452     *skip = 1;
10453     return true;
10454   }
10455
10456   bool
10457   do_is_addressable() const;
10458
10459   void
10460   do_address_taken(bool escapes)
10461   { this->array_->address_taken(escapes); }
10462
10463   tree
10464   do_get_tree(Translate_context*);
10465
10466   void
10467   do_dump_expression(Ast_dump_context*) const;
10468
10469  private:
10470   // The array we are getting a value from.
10471   Expression* array_;
10472   // The start or only index.
10473   Expression* start_;
10474   // The end index of a slice.  This may be NULL for a simple array
10475   // index, or it may be a nil expression for the length of the array.
10476   Expression* end_;
10477   // The type of the expression.
10478   Type* type_;
10479 };
10480
10481 // Array index traversal.
10482
10483 int
10484 Array_index_expression::do_traverse(Traverse* traverse)
10485 {
10486   if (Expression::traverse(&this->array_, traverse) == TRAVERSE_EXIT)
10487     return TRAVERSE_EXIT;
10488   if (Expression::traverse(&this->start_, traverse) == TRAVERSE_EXIT)
10489     return TRAVERSE_EXIT;
10490   if (this->end_ != NULL)
10491     {
10492       if (Expression::traverse(&this->end_, traverse) == TRAVERSE_EXIT)
10493         return TRAVERSE_EXIT;
10494     }
10495   return TRAVERSE_CONTINUE;
10496 }
10497
10498 // Return the type of an array index.
10499
10500 Type*
10501 Array_index_expression::do_type()
10502 {
10503   if (this->type_ == NULL)
10504     {
10505      Array_type* type = this->array_->type()->array_type();
10506       if (type == NULL)
10507         this->type_ = Type::make_error_type();
10508       else if (this->end_ == NULL)
10509         this->type_ = type->element_type();
10510       else if (type->is_slice_type())
10511         {
10512           // A slice of a slice has the same type as the original
10513           // slice.
10514           this->type_ = this->array_->type()->deref();
10515         }
10516       else
10517         {
10518           // A slice of an array is a slice.
10519           this->type_ = Type::make_array_type(type->element_type(), NULL);
10520         }
10521     }
10522   return this->type_;
10523 }
10524
10525 // Set the type of an array index.
10526
10527 void
10528 Array_index_expression::do_determine_type(const Type_context*)
10529 {
10530   this->array_->determine_type_no_context();
10531   this->start_->determine_type_no_context();
10532   if (this->end_ != NULL)
10533     this->end_->determine_type_no_context();
10534 }
10535
10536 // Check types of an array index.
10537
10538 void
10539 Array_index_expression::do_check_types(Gogo*)
10540 {
10541   if (this->start_->type()->integer_type() == NULL)
10542     this->report_error(_("index must be integer"));
10543   if (this->end_ != NULL
10544       && this->end_->type()->integer_type() == NULL
10545       && !this->end_->type()->is_error()
10546       && !this->end_->is_nil_expression()
10547       && !this->end_->is_error_expression())
10548     this->report_error(_("slice end must be integer"));
10549
10550   Array_type* array_type = this->array_->type()->array_type();
10551   if (array_type == NULL)
10552     {
10553       go_assert(this->array_->type()->is_error());
10554       return;
10555     }
10556
10557   unsigned int int_bits =
10558     Type::lookup_integer_type("int")->integer_type()->bits();
10559
10560   Type* dummy;
10561   mpz_t lval;
10562   mpz_init(lval);
10563   bool lval_valid = (array_type->length() != NULL
10564                      && array_type->length()->integer_constant_value(true,
10565                                                                      lval,
10566                                                                      &dummy));
10567   mpz_t ival;
10568   mpz_init(ival);
10569   if (this->start_->integer_constant_value(true, ival, &dummy))
10570     {
10571       if (mpz_sgn(ival) < 0
10572           || mpz_sizeinbase(ival, 2) >= int_bits
10573           || (lval_valid
10574               && (this->end_ == NULL
10575                   ? mpz_cmp(ival, lval) >= 0
10576                   : mpz_cmp(ival, lval) > 0)))
10577         {
10578           error_at(this->start_->location(), "array index out of bounds");
10579           this->set_is_error();
10580         }
10581     }
10582   if (this->end_ != NULL && !this->end_->is_nil_expression())
10583     {
10584       if (this->end_->integer_constant_value(true, ival, &dummy))
10585         {
10586           if (mpz_sgn(ival) < 0
10587               || mpz_sizeinbase(ival, 2) >= int_bits
10588               || (lval_valid && mpz_cmp(ival, lval) > 0))
10589             {
10590               error_at(this->end_->location(), "array index out of bounds");
10591               this->set_is_error();
10592             }
10593         }
10594     }
10595   mpz_clear(ival);
10596   mpz_clear(lval);
10597
10598   // A slice of an array requires an addressable array.  A slice of a
10599   // slice is always possible.
10600   if (this->end_ != NULL && !array_type->is_slice_type())
10601     {
10602       if (!this->array_->is_addressable())
10603         this->report_error(_("slice of unaddressable value"));
10604       else
10605         this->array_->address_taken(true);
10606     }
10607 }
10608
10609 // Return whether this expression is addressable.
10610
10611 bool
10612 Array_index_expression::do_is_addressable() const
10613 {
10614   // A slice expression is not addressable.
10615   if (this->end_ != NULL)
10616     return false;
10617
10618   // An index into a slice is addressable.
10619   if (this->array_->type()->is_slice_type())
10620     return true;
10621
10622   // An index into an array is addressable if the array is
10623   // addressable.
10624   return this->array_->is_addressable();
10625 }
10626
10627 // Get a tree for an array index.
10628
10629 tree
10630 Array_index_expression::do_get_tree(Translate_context* context)
10631 {
10632   Gogo* gogo = context->gogo();
10633   Location loc = this->location();
10634
10635   Array_type* array_type = this->array_->type()->array_type();
10636   if (array_type == NULL)
10637     {
10638       go_assert(this->array_->type()->is_error());
10639       return error_mark_node;
10640     }
10641
10642   tree type_tree = type_to_tree(array_type->get_backend(gogo));
10643   if (type_tree == error_mark_node)
10644     return error_mark_node;
10645
10646   tree array_tree = this->array_->get_tree(context);
10647   if (array_tree == error_mark_node)
10648     return error_mark_node;
10649
10650   if (array_type->length() == NULL && !DECL_P(array_tree))
10651     array_tree = save_expr(array_tree);
10652   tree length_tree = array_type->length_tree(gogo, array_tree);
10653   if (length_tree == error_mark_node)
10654     return error_mark_node;
10655   length_tree = save_expr(length_tree);
10656   tree length_type = TREE_TYPE(length_tree);
10657
10658   tree bad_index = boolean_false_node;
10659
10660   tree start_tree = this->start_->get_tree(context);
10661   if (start_tree == error_mark_node)
10662     return error_mark_node;
10663   if (!DECL_P(start_tree))
10664     start_tree = save_expr(start_tree);
10665   if (!INTEGRAL_TYPE_P(TREE_TYPE(start_tree)))
10666     start_tree = convert_to_integer(length_type, start_tree);
10667
10668   bad_index = Expression::check_bounds(start_tree, length_type, bad_index,
10669                                        loc);
10670
10671   start_tree = fold_convert_loc(loc.gcc_location(), length_type, start_tree);
10672   bad_index = fold_build2_loc(loc.gcc_location(), TRUTH_OR_EXPR,
10673                               boolean_type_node, bad_index,
10674                               fold_build2_loc(loc.gcc_location(),
10675                                               (this->end_ == NULL
10676                                                ? GE_EXPR
10677                                                : GT_EXPR),
10678                                               boolean_type_node, start_tree,
10679                                               length_tree));
10680
10681   int code = (array_type->length() != NULL
10682               ? (this->end_ == NULL
10683                  ? RUNTIME_ERROR_ARRAY_INDEX_OUT_OF_BOUNDS
10684                  : RUNTIME_ERROR_ARRAY_SLICE_OUT_OF_BOUNDS)
10685               : (this->end_ == NULL
10686                  ? RUNTIME_ERROR_SLICE_INDEX_OUT_OF_BOUNDS
10687                  : RUNTIME_ERROR_SLICE_SLICE_OUT_OF_BOUNDS));
10688   tree crash = Gogo::runtime_error(code, loc);
10689
10690   if (this->end_ == NULL)
10691     {
10692       // Simple array indexing.  This has to return an l-value, so
10693       // wrap the index check into START_TREE.
10694       start_tree = build2(COMPOUND_EXPR, TREE_TYPE(start_tree),
10695                           build3(COND_EXPR, void_type_node,
10696                                  bad_index, crash, NULL_TREE),
10697                           start_tree);
10698       start_tree = fold_convert_loc(loc.gcc_location(), sizetype, start_tree);
10699
10700       if (array_type->length() != NULL)
10701         {
10702           // Fixed array.
10703           return build4(ARRAY_REF, TREE_TYPE(type_tree), array_tree,
10704                         start_tree, NULL_TREE, NULL_TREE);
10705         }
10706       else
10707         {
10708           // Open array.
10709           tree values = array_type->value_pointer_tree(gogo, array_tree);
10710           Type* element_type = array_type->element_type();
10711           Btype* belement_type = element_type->get_backend(gogo);
10712           tree element_type_tree = type_to_tree(belement_type);
10713           if (element_type_tree == error_mark_node)
10714             return error_mark_node;
10715           tree element_size = TYPE_SIZE_UNIT(element_type_tree);
10716           tree offset = fold_build2_loc(loc.gcc_location(), MULT_EXPR, sizetype,
10717                                         start_tree, element_size);
10718           tree ptr = fold_build2_loc(loc.gcc_location(), POINTER_PLUS_EXPR,
10719                                      TREE_TYPE(values), values, offset);
10720           return build_fold_indirect_ref(ptr);
10721         }
10722     }
10723
10724   // Array slice.
10725
10726   tree capacity_tree = array_type->capacity_tree(gogo, array_tree);
10727   if (capacity_tree == error_mark_node)
10728     return error_mark_node;
10729   capacity_tree = fold_convert_loc(loc.gcc_location(), length_type,
10730                                    capacity_tree);
10731
10732   tree end_tree;
10733   if (this->end_->is_nil_expression())
10734     end_tree = length_tree;
10735   else
10736     {
10737       end_tree = this->end_->get_tree(context);
10738       if (end_tree == error_mark_node)
10739         return error_mark_node;
10740       if (!DECL_P(end_tree))
10741         end_tree = save_expr(end_tree);
10742       if (!INTEGRAL_TYPE_P(TREE_TYPE(end_tree)))
10743         end_tree = convert_to_integer(length_type, end_tree);
10744
10745       bad_index = Expression::check_bounds(end_tree, length_type, bad_index,
10746                                            loc);
10747
10748       end_tree = fold_convert_loc(loc.gcc_location(), length_type, end_tree);
10749
10750       capacity_tree = save_expr(capacity_tree);
10751       tree bad_end = fold_build2_loc(loc.gcc_location(), TRUTH_OR_EXPR,
10752                                      boolean_type_node,
10753                                      fold_build2_loc(loc.gcc_location(),
10754                                                      LT_EXPR, boolean_type_node,
10755                                                      end_tree, start_tree),
10756                                      fold_build2_loc(loc.gcc_location(),
10757                                                      GT_EXPR, boolean_type_node,
10758                                                      end_tree, capacity_tree));
10759       bad_index = fold_build2_loc(loc.gcc_location(), TRUTH_OR_EXPR,
10760                                   boolean_type_node, bad_index, bad_end);
10761     }
10762
10763   Type* element_type = array_type->element_type();
10764   tree element_type_tree = type_to_tree(element_type->get_backend(gogo));
10765   if (element_type_tree == error_mark_node)
10766     return error_mark_node;
10767   tree element_size = TYPE_SIZE_UNIT(element_type_tree);
10768
10769   tree offset = fold_build2_loc(loc.gcc_location(), MULT_EXPR, sizetype,
10770                                 fold_convert_loc(loc.gcc_location(), sizetype,
10771                                                  start_tree),
10772                                 element_size);
10773
10774   tree value_pointer = array_type->value_pointer_tree(gogo, array_tree);
10775   if (value_pointer == error_mark_node)
10776     return error_mark_node;
10777
10778   value_pointer = fold_build2_loc(loc.gcc_location(), POINTER_PLUS_EXPR,
10779                                   TREE_TYPE(value_pointer),
10780                                   value_pointer, offset);
10781
10782   tree result_length_tree = fold_build2_loc(loc.gcc_location(), MINUS_EXPR,
10783                                             length_type, end_tree, start_tree);
10784
10785   tree result_capacity_tree = fold_build2_loc(loc.gcc_location(), MINUS_EXPR,
10786                                               length_type, capacity_tree,
10787                                               start_tree);
10788
10789   tree struct_tree = type_to_tree(this->type()->get_backend(gogo));
10790   go_assert(TREE_CODE(struct_tree) == RECORD_TYPE);
10791
10792   VEC(constructor_elt,gc)* init = VEC_alloc(constructor_elt, gc, 3);
10793
10794   constructor_elt* elt = VEC_quick_push(constructor_elt, init, NULL);
10795   tree field = TYPE_FIELDS(struct_tree);
10796   go_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__values") == 0);
10797   elt->index = field;
10798   elt->value = value_pointer;
10799
10800   elt = VEC_quick_push(constructor_elt, init, NULL);
10801   field = DECL_CHAIN(field);
10802   go_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__count") == 0);
10803   elt->index = field;
10804   elt->value = fold_convert_loc(loc.gcc_location(), TREE_TYPE(field),
10805                                 result_length_tree);
10806
10807   elt = VEC_quick_push(constructor_elt, init, NULL);
10808   field = DECL_CHAIN(field);
10809   go_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__capacity") == 0);
10810   elt->index = field;
10811   elt->value = fold_convert_loc(loc.gcc_location(), TREE_TYPE(field),
10812                                 result_capacity_tree);
10813
10814   tree constructor = build_constructor(struct_tree, init);
10815
10816   if (TREE_CONSTANT(value_pointer)
10817       && TREE_CONSTANT(result_length_tree)
10818       && TREE_CONSTANT(result_capacity_tree))
10819     TREE_CONSTANT(constructor) = 1;
10820
10821   return fold_build2_loc(loc.gcc_location(), COMPOUND_EXPR,
10822                          TREE_TYPE(constructor),
10823                          build3(COND_EXPR, void_type_node,
10824                                 bad_index, crash, NULL_TREE),
10825                          constructor);
10826 }
10827
10828 // Dump ast representation for an array index expression.
10829
10830 void
10831 Array_index_expression::do_dump_expression(Ast_dump_context* ast_dump_context)
10832     const
10833 {
10834   Index_expression::dump_index_expression(ast_dump_context, this->array_,
10835                                           this->start_, this->end_);
10836 }
10837
10838 // Make an array index expression.  END may be NULL.
10839
10840 Expression*
10841 Expression::make_array_index(Expression* array, Expression* start,
10842                              Expression* end, Location location)
10843 {
10844   return new Array_index_expression(array, start, end, location);
10845 }
10846
10847 // A string index.  This is used for both indexing and slicing.
10848
10849 class String_index_expression : public Expression
10850 {
10851  public:
10852   String_index_expression(Expression* string, Expression* start,
10853                           Expression* end, Location location)
10854     : Expression(EXPRESSION_STRING_INDEX, location),
10855       string_(string), start_(start), end_(end)
10856   { }
10857
10858  protected:
10859   int
10860   do_traverse(Traverse*);
10861
10862   Type*
10863   do_type();
10864
10865   void
10866   do_determine_type(const Type_context*);
10867
10868   void
10869   do_check_types(Gogo*);
10870
10871   Expression*
10872   do_copy()
10873   {
10874     return Expression::make_string_index(this->string_->copy(),
10875                                          this->start_->copy(),
10876                                          (this->end_ == NULL
10877                                           ? NULL
10878                                           : this->end_->copy()),
10879                                          this->location());
10880   }
10881
10882   bool
10883   do_must_eval_subexpressions_in_order(int* skip) const
10884   {
10885     *skip = 1;
10886     return true;
10887   }
10888
10889   tree
10890   do_get_tree(Translate_context*);
10891
10892   void
10893   do_dump_expression(Ast_dump_context*) const;
10894
10895  private:
10896   // The string we are getting a value from.
10897   Expression* string_;
10898   // The start or only index.
10899   Expression* start_;
10900   // The end index of a slice.  This may be NULL for a single index,
10901   // or it may be a nil expression for the length of the string.
10902   Expression* end_;
10903 };
10904
10905 // String index traversal.
10906
10907 int
10908 String_index_expression::do_traverse(Traverse* traverse)
10909 {
10910   if (Expression::traverse(&this->string_, traverse) == TRAVERSE_EXIT)
10911     return TRAVERSE_EXIT;
10912   if (Expression::traverse(&this->start_, traverse) == TRAVERSE_EXIT)
10913     return TRAVERSE_EXIT;
10914   if (this->end_ != NULL)
10915     {
10916       if (Expression::traverse(&this->end_, traverse) == TRAVERSE_EXIT)
10917         return TRAVERSE_EXIT;
10918     }
10919   return TRAVERSE_CONTINUE;
10920 }
10921
10922 // Return the type of a string index.
10923
10924 Type*
10925 String_index_expression::do_type()
10926 {
10927   if (this->end_ == NULL)
10928     return Type::lookup_integer_type("uint8");
10929   else
10930     return this->string_->type();
10931 }
10932
10933 // Determine the type of a string index.
10934
10935 void
10936 String_index_expression::do_determine_type(const Type_context*)
10937 {
10938   this->string_->determine_type_no_context();
10939   this->start_->determine_type_no_context();
10940   if (this->end_ != NULL)
10941     this->end_->determine_type_no_context();
10942 }
10943
10944 // Check types of a string index.
10945
10946 void
10947 String_index_expression::do_check_types(Gogo*)
10948 {
10949   if (this->start_->type()->integer_type() == NULL)
10950     this->report_error(_("index must be integer"));
10951   if (this->end_ != NULL
10952       && this->end_->type()->integer_type() == NULL
10953       && !this->end_->is_nil_expression())
10954     this->report_error(_("slice end must be integer"));
10955
10956   std::string sval;
10957   bool sval_valid = this->string_->string_constant_value(&sval);
10958
10959   mpz_t ival;
10960   mpz_init(ival);
10961   Type* dummy;
10962   if (this->start_->integer_constant_value(true, ival, &dummy))
10963     {
10964       if (mpz_sgn(ival) < 0
10965           || (sval_valid && mpz_cmp_ui(ival, sval.length()) >= 0))
10966         {
10967           error_at(this->start_->location(), "string index out of bounds");
10968           this->set_is_error();
10969         }
10970     }
10971   if (this->end_ != NULL && !this->end_->is_nil_expression())
10972     {
10973       if (this->end_->integer_constant_value(true, ival, &dummy))
10974         {
10975           if (mpz_sgn(ival) < 0
10976               || (sval_valid && mpz_cmp_ui(ival, sval.length()) > 0))
10977             {
10978               error_at(this->end_->location(), "string index out of bounds");
10979               this->set_is_error();
10980             }
10981         }
10982     }
10983   mpz_clear(ival);
10984 }
10985
10986 // Get a tree for a string index.
10987
10988 tree
10989 String_index_expression::do_get_tree(Translate_context* context)
10990 {
10991   Location loc = this->location();
10992
10993   tree string_tree = this->string_->get_tree(context);
10994   if (string_tree == error_mark_node)
10995     return error_mark_node;
10996
10997   if (this->string_->type()->points_to() != NULL)
10998     string_tree = build_fold_indirect_ref(string_tree);
10999   if (!DECL_P(string_tree))
11000     string_tree = save_expr(string_tree);
11001   tree string_type = TREE_TYPE(string_tree);
11002
11003   tree length_tree = String_type::length_tree(context->gogo(), string_tree);
11004   length_tree = save_expr(length_tree);
11005   tree length_type = TREE_TYPE(length_tree);
11006
11007   tree bad_index = boolean_false_node;
11008
11009   tree start_tree = this->start_->get_tree(context);
11010   if (start_tree == error_mark_node)
11011     return error_mark_node;
11012   if (!DECL_P(start_tree))
11013     start_tree = save_expr(start_tree);
11014   if (!INTEGRAL_TYPE_P(TREE_TYPE(start_tree)))
11015     start_tree = convert_to_integer(length_type, start_tree);
11016
11017   bad_index = Expression::check_bounds(start_tree, length_type, bad_index,
11018                                        loc);
11019
11020   start_tree = fold_convert_loc(loc.gcc_location(), length_type, start_tree);
11021
11022   int code = (this->end_ == NULL
11023               ? RUNTIME_ERROR_STRING_INDEX_OUT_OF_BOUNDS
11024               : RUNTIME_ERROR_STRING_SLICE_OUT_OF_BOUNDS);
11025   tree crash = Gogo::runtime_error(code, loc);
11026
11027   if (this->end_ == NULL)
11028     {
11029       bad_index = fold_build2_loc(loc.gcc_location(), TRUTH_OR_EXPR,
11030                                   boolean_type_node, bad_index,
11031                                   fold_build2_loc(loc.gcc_location(), GE_EXPR,
11032                                                   boolean_type_node,
11033                                                   start_tree, length_tree));
11034
11035       tree bytes_tree = String_type::bytes_tree(context->gogo(), string_tree);
11036       tree ptr = fold_build2_loc(loc.gcc_location(), POINTER_PLUS_EXPR,
11037                                  TREE_TYPE(bytes_tree),
11038                                  bytes_tree,
11039                                  fold_convert_loc(loc.gcc_location(), sizetype,
11040                                                   start_tree));
11041       tree index = build_fold_indirect_ref_loc(loc.gcc_location(), ptr);
11042
11043       return build2(COMPOUND_EXPR, TREE_TYPE(index),
11044                     build3(COND_EXPR, void_type_node,
11045                            bad_index, crash, NULL_TREE),
11046                     index);
11047     }
11048   else
11049     {
11050       tree end_tree;
11051       if (this->end_->is_nil_expression())
11052         end_tree = build_int_cst(length_type, -1);
11053       else
11054         {
11055           end_tree = this->end_->get_tree(context);
11056           if (end_tree == error_mark_node)
11057             return error_mark_node;
11058           if (!DECL_P(end_tree))
11059             end_tree = save_expr(end_tree);
11060           if (!INTEGRAL_TYPE_P(TREE_TYPE(end_tree)))
11061             end_tree = convert_to_integer(length_type, end_tree);
11062
11063           bad_index = Expression::check_bounds(end_tree, length_type,
11064                                                bad_index, loc);
11065
11066           end_tree = fold_convert_loc(loc.gcc_location(), length_type,
11067                                       end_tree);
11068         }
11069
11070       static tree strslice_fndecl;
11071       tree ret = Gogo::call_builtin(&strslice_fndecl,
11072                                     loc,
11073                                     "__go_string_slice",
11074                                     3,
11075                                     string_type,
11076                                     string_type,
11077                                     string_tree,
11078                                     length_type,
11079                                     start_tree,
11080                                     length_type,
11081                                     end_tree);
11082       if (ret == error_mark_node)
11083         return error_mark_node;
11084       // This will panic if the bounds are out of range for the
11085       // string.
11086       TREE_NOTHROW(strslice_fndecl) = 0;
11087
11088       if (bad_index == boolean_false_node)
11089         return ret;
11090       else
11091         return build2(COMPOUND_EXPR, TREE_TYPE(ret),
11092                       build3(COND_EXPR, void_type_node,
11093                              bad_index, crash, NULL_TREE),
11094                       ret);
11095     }
11096 }
11097
11098 // Dump ast representation for a string index expression.
11099
11100 void
11101 String_index_expression::do_dump_expression(Ast_dump_context* ast_dump_context)
11102     const
11103 {
11104   Index_expression::dump_index_expression(ast_dump_context, this->string_,
11105                                           this->start_, this->end_);
11106 }
11107
11108 // Make a string index expression.  END may be NULL.
11109
11110 Expression*
11111 Expression::make_string_index(Expression* string, Expression* start,
11112                               Expression* end, Location location)
11113 {
11114   return new String_index_expression(string, start, end, location);
11115 }
11116
11117 // Class Map_index.
11118
11119 // Get the type of the map.
11120
11121 Map_type*
11122 Map_index_expression::get_map_type() const
11123 {
11124   Map_type* mt = this->map_->type()->deref()->map_type();
11125   if (mt == NULL)
11126     go_assert(saw_errors());
11127   return mt;
11128 }
11129
11130 // Map index traversal.
11131
11132 int
11133 Map_index_expression::do_traverse(Traverse* traverse)
11134 {
11135   if (Expression::traverse(&this->map_, traverse) == TRAVERSE_EXIT)
11136     return TRAVERSE_EXIT;
11137   return Expression::traverse(&this->index_, traverse);
11138 }
11139
11140 // Return the type of a map index.
11141
11142 Type*
11143 Map_index_expression::do_type()
11144 {
11145   Map_type* mt = this->get_map_type();
11146   if (mt == NULL)
11147     return Type::make_error_type();
11148   Type* type = mt->val_type();
11149   // If this map index is in a tuple assignment, we actually return a
11150   // pointer to the value type.  Tuple_map_assignment_statement is
11151   // responsible for handling this correctly.  We need to get the type
11152   // right in case this gets assigned to a temporary variable.
11153   if (this->is_in_tuple_assignment_)
11154     type = Type::make_pointer_type(type);
11155   return type;
11156 }
11157
11158 // Fix the type of a map index.
11159
11160 void
11161 Map_index_expression::do_determine_type(const Type_context*)
11162 {
11163   this->map_->determine_type_no_context();
11164   Map_type* mt = this->get_map_type();
11165   Type* key_type = mt == NULL ? NULL : mt->key_type();
11166   Type_context subcontext(key_type, false);
11167   this->index_->determine_type(&subcontext);
11168 }
11169
11170 // Check types of a map index.
11171
11172 void
11173 Map_index_expression::do_check_types(Gogo*)
11174 {
11175   std::string reason;
11176   Map_type* mt = this->get_map_type();
11177   if (mt == NULL)
11178     return;
11179   if (!Type::are_assignable(mt->key_type(), this->index_->type(), &reason))
11180     {
11181       if (reason.empty())
11182         this->report_error(_("incompatible type for map index"));
11183       else
11184         {
11185           error_at(this->location(), "incompatible type for map index (%s)",
11186                    reason.c_str());
11187           this->set_is_error();
11188         }
11189     }
11190 }
11191
11192 // Get a tree for a map index.
11193
11194 tree
11195 Map_index_expression::do_get_tree(Translate_context* context)
11196 {
11197   Map_type* type = this->get_map_type();
11198   if (type == NULL)
11199     return error_mark_node;
11200
11201   tree valptr = this->get_value_pointer(context, this->is_lvalue_);
11202   if (valptr == error_mark_node)
11203     return error_mark_node;
11204   valptr = save_expr(valptr);
11205
11206   tree val_type_tree = TREE_TYPE(TREE_TYPE(valptr));
11207
11208   if (this->is_lvalue_)
11209     return build_fold_indirect_ref(valptr);
11210   else if (this->is_in_tuple_assignment_)
11211     {
11212       // Tuple_map_assignment_statement is responsible for using this
11213       // appropriately.
11214       return valptr;
11215     }
11216   else
11217     {
11218       Gogo* gogo = context->gogo();
11219       Btype* val_btype = type->val_type()->get_backend(gogo);
11220       Bexpression* val_zero = gogo->backend()->zero_expression(val_btype);
11221       return fold_build3(COND_EXPR, val_type_tree,
11222                          fold_build2(EQ_EXPR, boolean_type_node, valptr,
11223                                      fold_convert(TREE_TYPE(valptr),
11224                                                   null_pointer_node)),
11225                          expr_to_tree(val_zero),
11226                          build_fold_indirect_ref(valptr));
11227     }
11228 }
11229
11230 // Get a tree for the map index.  This returns a tree which evaluates
11231 // to a pointer to a value.  The pointer will be NULL if the key is
11232 // not in the map.
11233
11234 tree
11235 Map_index_expression::get_value_pointer(Translate_context* context,
11236                                         bool insert)
11237 {
11238   Map_type* type = this->get_map_type();
11239   if (type == NULL)
11240     return error_mark_node;
11241
11242   tree map_tree = this->map_->get_tree(context);
11243   tree index_tree = this->index_->get_tree(context);
11244   index_tree = Expression::convert_for_assignment(context, type->key_type(),
11245                                                   this->index_->type(),
11246                                                   index_tree,
11247                                                   this->location());
11248   if (map_tree == error_mark_node || index_tree == error_mark_node)
11249     return error_mark_node;
11250
11251   if (this->map_->type()->points_to() != NULL)
11252     map_tree = build_fold_indirect_ref(map_tree);
11253
11254   // We need to pass in a pointer to the key, so stuff it into a
11255   // variable.
11256   tree tmp;
11257   tree make_tmp;
11258   if (current_function_decl != NULL)
11259     {
11260       tmp = create_tmp_var(TREE_TYPE(index_tree), get_name(index_tree));
11261       DECL_IGNORED_P(tmp) = 0;
11262       DECL_INITIAL(tmp) = index_tree;
11263       make_tmp = build1(DECL_EXPR, void_type_node, tmp);
11264       TREE_ADDRESSABLE(tmp) = 1;
11265     }
11266   else
11267     {
11268       tmp = build_decl(this->location().gcc_location(), VAR_DECL,
11269                        create_tmp_var_name("M"),
11270                        TREE_TYPE(index_tree));
11271       DECL_EXTERNAL(tmp) = 0;
11272       TREE_PUBLIC(tmp) = 0;
11273       TREE_STATIC(tmp) = 1;
11274       DECL_ARTIFICIAL(tmp) = 1;
11275       if (!TREE_CONSTANT(index_tree))
11276         make_tmp = fold_build2_loc(this->location().gcc_location(),
11277                                    INIT_EXPR, void_type_node,
11278                                    tmp, index_tree);
11279       else
11280         {
11281           TREE_READONLY(tmp) = 1;
11282           TREE_CONSTANT(tmp) = 1;
11283           DECL_INITIAL(tmp) = index_tree;
11284           make_tmp = NULL_TREE;
11285         }
11286       rest_of_decl_compilation(tmp, 1, 0);
11287     }
11288   tree tmpref =
11289     fold_convert_loc(this->location().gcc_location(), const_ptr_type_node,
11290                      build_fold_addr_expr_loc(this->location().gcc_location(),
11291                                               tmp));
11292
11293   static tree map_index_fndecl;
11294   tree call = Gogo::call_builtin(&map_index_fndecl,
11295                                  this->location(),
11296                                  "__go_map_index",
11297                                  3,
11298                                  const_ptr_type_node,
11299                                  TREE_TYPE(map_tree),
11300                                  map_tree,
11301                                  const_ptr_type_node,
11302                                  tmpref,
11303                                  boolean_type_node,
11304                                  (insert
11305                                   ? boolean_true_node
11306                                   : boolean_false_node));
11307   if (call == error_mark_node)
11308     return error_mark_node;
11309   // This can panic on a map of interface type if the interface holds
11310   // an uncomparable or unhashable type.
11311   TREE_NOTHROW(map_index_fndecl) = 0;
11312
11313   Type* val_type = type->val_type();
11314   tree val_type_tree = type_to_tree(val_type->get_backend(context->gogo()));
11315   if (val_type_tree == error_mark_node)
11316     return error_mark_node;
11317   tree ptr_val_type_tree = build_pointer_type(val_type_tree);
11318
11319   tree ret = fold_convert_loc(this->location().gcc_location(),
11320                               ptr_val_type_tree, call);
11321   if (make_tmp != NULL_TREE)
11322     ret = build2(COMPOUND_EXPR, ptr_val_type_tree, make_tmp, ret);
11323   return ret;
11324 }
11325
11326 // Dump ast representation for a map index expression
11327
11328 void
11329 Map_index_expression::do_dump_expression(Ast_dump_context* ast_dump_context)
11330     const
11331 {
11332   Index_expression::dump_index_expression(ast_dump_context,
11333                                           this->map_, this->index_, NULL);
11334 }
11335
11336 // Make a map index expression.
11337
11338 Map_index_expression*
11339 Expression::make_map_index(Expression* map, Expression* index,
11340                            Location location)
11341 {
11342   return new Map_index_expression(map, index, location);
11343 }
11344
11345 // Class Field_reference_expression.
11346
11347 // Return the type of a field reference.
11348
11349 Type*
11350 Field_reference_expression::do_type()
11351 {
11352   Type* type = this->expr_->type();
11353   if (type->is_error())
11354     return type;
11355   Struct_type* struct_type = type->struct_type();
11356   go_assert(struct_type != NULL);
11357   return struct_type->field(this->field_index_)->type();
11358 }
11359
11360 // Check the types for a field reference.
11361
11362 void
11363 Field_reference_expression::do_check_types(Gogo*)
11364 {
11365   Type* type = this->expr_->type();
11366   if (type->is_error())
11367     return;
11368   Struct_type* struct_type = type->struct_type();
11369   go_assert(struct_type != NULL);
11370   go_assert(struct_type->field(this->field_index_) != NULL);
11371 }
11372
11373 // Get a tree for a field reference.
11374
11375 tree
11376 Field_reference_expression::do_get_tree(Translate_context* context)
11377 {
11378   tree struct_tree = this->expr_->get_tree(context);
11379   if (struct_tree == error_mark_node
11380       || TREE_TYPE(struct_tree) == error_mark_node)
11381     return error_mark_node;
11382   go_assert(TREE_CODE(TREE_TYPE(struct_tree)) == RECORD_TYPE);
11383   tree field = TYPE_FIELDS(TREE_TYPE(struct_tree));
11384   if (field == NULL_TREE)
11385     {
11386       // This can happen for a type which refers to itself indirectly
11387       // and then turns out to be erroneous.
11388       go_assert(saw_errors());
11389       return error_mark_node;
11390     }
11391   for (unsigned int i = this->field_index_; i > 0; --i)
11392     {
11393       field = DECL_CHAIN(field);
11394       go_assert(field != NULL_TREE);
11395     }
11396   if (TREE_TYPE(field) == error_mark_node)
11397     return error_mark_node;
11398   return build3(COMPONENT_REF, TREE_TYPE(field), struct_tree, field,
11399                 NULL_TREE);
11400 }
11401
11402 // Dump ast representation for a field reference expression.
11403
11404 void
11405 Field_reference_expression::do_dump_expression(
11406     Ast_dump_context* ast_dump_context) const
11407 {
11408   this->expr_->dump_expression(ast_dump_context);
11409   ast_dump_context->ostream() << "." <<  this->field_index_;
11410 }
11411
11412 // Make a reference to a qualified identifier in an expression.
11413
11414 Field_reference_expression*
11415 Expression::make_field_reference(Expression* expr, unsigned int field_index,
11416                                  Location location)
11417 {
11418   return new Field_reference_expression(expr, field_index, location);
11419 }
11420
11421 // Class Interface_field_reference_expression.
11422
11423 // Return a tree for the pointer to the function to call.
11424
11425 tree
11426 Interface_field_reference_expression::get_function_tree(Translate_context*,
11427                                                         tree expr)
11428 {
11429   if (this->expr_->type()->points_to() != NULL)
11430     expr = build_fold_indirect_ref(expr);
11431
11432   tree expr_type = TREE_TYPE(expr);
11433   go_assert(TREE_CODE(expr_type) == RECORD_TYPE);
11434
11435   tree field = TYPE_FIELDS(expr_type);
11436   go_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__methods") == 0);
11437
11438   tree table = build3(COMPONENT_REF, TREE_TYPE(field), expr, field, NULL_TREE);
11439   go_assert(POINTER_TYPE_P(TREE_TYPE(table)));
11440
11441   table = build_fold_indirect_ref(table);
11442   go_assert(TREE_CODE(TREE_TYPE(table)) == RECORD_TYPE);
11443
11444   std::string name = Gogo::unpack_hidden_name(this->name_);
11445   for (field = DECL_CHAIN(TYPE_FIELDS(TREE_TYPE(table)));
11446        field != NULL_TREE;
11447        field = DECL_CHAIN(field))
11448     {
11449       if (name == IDENTIFIER_POINTER(DECL_NAME(field)))
11450         break;
11451     }
11452   go_assert(field != NULL_TREE);
11453
11454   return build3(COMPONENT_REF, TREE_TYPE(field), table, field, NULL_TREE);
11455 }
11456
11457 // Return a tree for the first argument to pass to the interface
11458 // function.
11459
11460 tree
11461 Interface_field_reference_expression::get_underlying_object_tree(
11462     Translate_context*,
11463     tree expr)
11464 {
11465   if (this->expr_->type()->points_to() != NULL)
11466     expr = build_fold_indirect_ref(expr);
11467
11468   tree expr_type = TREE_TYPE(expr);
11469   go_assert(TREE_CODE(expr_type) == RECORD_TYPE);
11470
11471   tree field = DECL_CHAIN(TYPE_FIELDS(expr_type));
11472   go_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__object") == 0);
11473
11474   return build3(COMPONENT_REF, TREE_TYPE(field), expr, field, NULL_TREE);
11475 }
11476
11477 // Traversal.
11478
11479 int
11480 Interface_field_reference_expression::do_traverse(Traverse* traverse)
11481 {
11482   return Expression::traverse(&this->expr_, traverse);
11483 }
11484
11485 // Return the type of an interface field reference.
11486
11487 Type*
11488 Interface_field_reference_expression::do_type()
11489 {
11490   Type* expr_type = this->expr_->type();
11491
11492   Type* points_to = expr_type->points_to();
11493   if (points_to != NULL)
11494     expr_type = points_to;
11495
11496   Interface_type* interface_type = expr_type->interface_type();
11497   if (interface_type == NULL)
11498     return Type::make_error_type();
11499
11500   const Typed_identifier* method = interface_type->find_method(this->name_);
11501   if (method == NULL)
11502     return Type::make_error_type();
11503
11504   return method->type();
11505 }
11506
11507 // Determine types.
11508
11509 void
11510 Interface_field_reference_expression::do_determine_type(const Type_context*)
11511 {
11512   this->expr_->determine_type_no_context();
11513 }
11514
11515 // Check the types for an interface field reference.
11516
11517 void
11518 Interface_field_reference_expression::do_check_types(Gogo*)
11519 {
11520   Type* type = this->expr_->type();
11521
11522   Type* points_to = type->points_to();
11523   if (points_to != NULL)
11524     type = points_to;
11525
11526   Interface_type* interface_type = type->interface_type();
11527   if (interface_type == NULL)
11528     {
11529       if (!type->is_error_type())
11530         this->report_error(_("expected interface or pointer to interface"));
11531     }
11532   else
11533     {
11534       const Typed_identifier* method =
11535         interface_type->find_method(this->name_);
11536       if (method == NULL)
11537         {
11538           error_at(this->location(), "method %qs not in interface",
11539                    Gogo::message_name(this->name_).c_str());
11540           this->set_is_error();
11541         }
11542     }
11543 }
11544
11545 // Get a tree for a reference to a field in an interface.  There is no
11546 // standard tree type representation for this: it's a function
11547 // attached to its first argument, like a Bound_method_expression.
11548 // The only places it may currently be used are in a Call_expression
11549 // or a Go_statement, which will take it apart directly.  So this has
11550 // nothing to do at present.
11551
11552 tree
11553 Interface_field_reference_expression::do_get_tree(Translate_context*)
11554 {
11555   go_unreachable();
11556 }
11557
11558 // Dump ast representation for an interface field reference.
11559
11560 void
11561 Interface_field_reference_expression::do_dump_expression(
11562     Ast_dump_context* ast_dump_context) const
11563 {
11564   this->expr_->dump_expression(ast_dump_context);
11565   ast_dump_context->ostream() << "." << this->name_;
11566 }
11567
11568 // Make a reference to a field in an interface.
11569
11570 Expression*
11571 Expression::make_interface_field_reference(Expression* expr,
11572                                            const std::string& field,
11573                                            Location location)
11574 {
11575   return new Interface_field_reference_expression(expr, field, location);
11576 }
11577
11578 // A general selector.  This is a Parser_expression for LEFT.NAME.  It
11579 // is lowered after we know the type of the left hand side.
11580
11581 class Selector_expression : public Parser_expression
11582 {
11583  public:
11584   Selector_expression(Expression* left, const std::string& name,
11585                       Location location)
11586     : Parser_expression(EXPRESSION_SELECTOR, location),
11587       left_(left), name_(name)
11588   { }
11589
11590  protected:
11591   int
11592   do_traverse(Traverse* traverse)
11593   { return Expression::traverse(&this->left_, traverse); }
11594
11595   Expression*
11596   do_lower(Gogo*, Named_object*, Statement_inserter*, int);
11597
11598   Expression*
11599   do_copy()
11600   {
11601     return new Selector_expression(this->left_->copy(), this->name_,
11602                                    this->location());
11603   }
11604
11605   void
11606   do_dump_expression(Ast_dump_context* ast_dump_context) const;
11607
11608  private:
11609   Expression*
11610   lower_method_expression(Gogo*);
11611
11612   // The expression on the left hand side.
11613   Expression* left_;
11614   // The name on the right hand side.
11615   std::string name_;
11616 };
11617
11618 // Lower a selector expression once we know the real type of the left
11619 // hand side.
11620
11621 Expression*
11622 Selector_expression::do_lower(Gogo* gogo, Named_object*, Statement_inserter*,
11623                               int)
11624 {
11625   Expression* left = this->left_;
11626   if (left->is_type_expression())
11627     return this->lower_method_expression(gogo);
11628   return Type::bind_field_or_method(gogo, left->type(), left, this->name_,
11629                                     this->location());
11630 }
11631
11632 // Lower a method expression T.M or (*T).M.  We turn this into a
11633 // function literal.
11634
11635 Expression*
11636 Selector_expression::lower_method_expression(Gogo* gogo)
11637 {
11638   Location location = this->location();
11639   Type* type = this->left_->type();
11640   const std::string& name(this->name_);
11641
11642   bool is_pointer;
11643   if (type->points_to() == NULL)
11644     is_pointer = false;
11645   else
11646     {
11647       is_pointer = true;
11648       type = type->points_to();
11649     }
11650   Named_type* nt = type->named_type();
11651   if (nt == NULL)
11652     {
11653       error_at(location,
11654                ("method expression requires named type or "
11655                 "pointer to named type"));
11656       return Expression::make_error(location);
11657     }
11658
11659   bool is_ambiguous;
11660   Method* method = nt->method_function(name, &is_ambiguous);
11661   const Typed_identifier* imethod = NULL;
11662   if (method == NULL && !is_pointer)
11663     {
11664       Interface_type* it = nt->interface_type();
11665       if (it != NULL)
11666         imethod = it->find_method(name);
11667     }
11668
11669   if (method == NULL && imethod == NULL)
11670     {
11671       if (!is_ambiguous)
11672         error_at(location, "type %<%s%s%> has no method %<%s%>",
11673                  is_pointer ? "*" : "",
11674                  nt->message_name().c_str(),
11675                  Gogo::message_name(name).c_str());
11676       else
11677         error_at(location, "method %<%s%s%> is ambiguous in type %<%s%>",
11678                  Gogo::message_name(name).c_str(),
11679                  is_pointer ? "*" : "",
11680                  nt->message_name().c_str());
11681       return Expression::make_error(location);
11682     }
11683
11684   if (method != NULL && !is_pointer && !method->is_value_method())
11685     {
11686       error_at(location, "method requires pointer (use %<(*%s).%s)%>",
11687                nt->message_name().c_str(),
11688                Gogo::message_name(name).c_str());
11689       return Expression::make_error(location);
11690     }
11691
11692   // Build a new function type in which the receiver becomes the first
11693   // argument.
11694   Function_type* method_type;
11695   if (method != NULL)
11696     {
11697       method_type = method->type();
11698       go_assert(method_type->is_method());
11699     }
11700   else
11701     {
11702       method_type = imethod->type()->function_type();
11703       go_assert(method_type != NULL && !method_type->is_method());
11704     }
11705
11706   const char* const receiver_name = "$this";
11707   Typed_identifier_list* parameters = new Typed_identifier_list();
11708   parameters->push_back(Typed_identifier(receiver_name, this->left_->type(),
11709                                          location));
11710
11711   const Typed_identifier_list* method_parameters = method_type->parameters();
11712   if (method_parameters != NULL)
11713     {
11714       int i = 0;
11715       for (Typed_identifier_list::const_iterator p = method_parameters->begin();
11716            p != method_parameters->end();
11717            ++p, ++i)
11718         {
11719           if (!p->name().empty() && p->name() != Import::import_marker)
11720             parameters->push_back(*p);
11721           else
11722             {
11723               char buf[20];
11724               snprintf(buf, sizeof buf, "$param%d", i);
11725               parameters->push_back(Typed_identifier(buf, p->type(),
11726                                                      p->location()));
11727             }
11728         }
11729     }
11730
11731   const Typed_identifier_list* method_results = method_type->results();
11732   Typed_identifier_list* results;
11733   if (method_results == NULL)
11734     results = NULL;
11735   else
11736     {
11737       results = new Typed_identifier_list();
11738       for (Typed_identifier_list::const_iterator p = method_results->begin();
11739            p != method_results->end();
11740            ++p)
11741         results->push_back(*p);
11742     }
11743
11744   Function_type* fntype = Type::make_function_type(NULL, parameters, results,
11745                                                    location);
11746   if (method_type->is_varargs())
11747     fntype->set_is_varargs();
11748
11749   // We generate methods which always takes a pointer to the receiver
11750   // as their first argument.  If this is for a pointer type, we can
11751   // simply reuse the existing function.  We use an internal hack to
11752   // get the right type.
11753
11754   if (method != NULL && is_pointer)
11755     {
11756       Named_object* mno = (method->needs_stub_method()
11757                            ? method->stub_object()
11758                            : method->named_object());
11759       Expression* f = Expression::make_func_reference(mno, NULL, location);
11760       f = Expression::make_cast(fntype, f, location);
11761       Type_conversion_expression* tce =
11762         static_cast<Type_conversion_expression*>(f);
11763       tce->set_may_convert_function_types();
11764       return f;
11765     }
11766
11767   Named_object* no = gogo->start_function(Gogo::thunk_name(), fntype, false,
11768                                           location);
11769
11770   Named_object* vno = gogo->lookup(receiver_name, NULL);
11771   go_assert(vno != NULL);
11772   Expression* ve = Expression::make_var_reference(vno, location);
11773   Expression* bm;
11774   if (method != NULL)
11775     bm = Type::bind_field_or_method(gogo, nt, ve, name, location);
11776   else
11777     bm = Expression::make_interface_field_reference(ve, name, location);
11778
11779   // Even though we found the method above, if it has an error type we
11780   // may see an error here.
11781   if (bm->is_error_expression())
11782     {
11783       gogo->finish_function(location);
11784       return bm;
11785     }
11786
11787   Expression_list* args;
11788   if (parameters->size() <= 1)
11789     args = NULL;
11790   else
11791     {
11792       args = new Expression_list();
11793       Typed_identifier_list::const_iterator p = parameters->begin();
11794       ++p;
11795       for (; p != parameters->end(); ++p)
11796         {
11797           vno = gogo->lookup(p->name(), NULL);
11798           go_assert(vno != NULL);
11799           args->push_back(Expression::make_var_reference(vno, location));
11800         }
11801     }
11802
11803   gogo->start_block(location);
11804
11805   Call_expression* call = Expression::make_call(bm, args,
11806                                                 method_type->is_varargs(),
11807                                                 location);
11808
11809   size_t count = call->result_count();
11810   Statement* s;
11811   if (count == 0)
11812     s = Statement::make_statement(call, true);
11813   else
11814     {
11815       Expression_list* retvals = new Expression_list();
11816       if (count <= 1)
11817         retvals->push_back(call);
11818       else
11819         {
11820           for (size_t i = 0; i < count; ++i)
11821             retvals->push_back(Expression::make_call_result(call, i));
11822         }
11823       s = Statement::make_return_statement(retvals, location);
11824     }
11825   gogo->add_statement(s);
11826
11827   Block* b = gogo->finish_block(location);
11828
11829   gogo->add_block(b, location);
11830
11831   // Lower the call in case there are multiple results.
11832   gogo->lower_block(no, b);
11833
11834   gogo->finish_function(location);
11835
11836   return Expression::make_func_reference(no, NULL, location);
11837 }
11838
11839 // Dump the ast for a selector expression.
11840
11841 void
11842 Selector_expression::do_dump_expression(Ast_dump_context* ast_dump_context)
11843     const
11844 {
11845   ast_dump_context->dump_expression(this->left_);
11846   ast_dump_context->ostream() << ".";
11847   ast_dump_context->ostream() << this->name_;
11848 }
11849
11850 // Make a selector expression.
11851
11852 Expression*
11853 Expression::make_selector(Expression* left, const std::string& name,
11854                           Location location)
11855 {
11856   return new Selector_expression(left, name, location);
11857 }
11858
11859 // Implement the builtin function new.
11860
11861 class Allocation_expression : public Expression
11862 {
11863  public:
11864   Allocation_expression(Type* type, Location location)
11865     : Expression(EXPRESSION_ALLOCATION, location),
11866       type_(type)
11867   { }
11868
11869  protected:
11870   int
11871   do_traverse(Traverse* traverse)
11872   { return Type::traverse(this->type_, traverse); }
11873
11874   Type*
11875   do_type()
11876   { return Type::make_pointer_type(this->type_); }
11877
11878   void
11879   do_determine_type(const Type_context*)
11880   { }
11881
11882   Expression*
11883   do_copy()
11884   { return new Allocation_expression(this->type_, this->location()); }
11885
11886   tree
11887   do_get_tree(Translate_context*);
11888
11889   void
11890   do_dump_expression(Ast_dump_context*) const;
11891
11892  private:
11893   // The type we are allocating.
11894   Type* type_;
11895 };
11896
11897 // Return a tree for an allocation expression.
11898
11899 tree
11900 Allocation_expression::do_get_tree(Translate_context* context)
11901 {
11902   tree type_tree = type_to_tree(this->type_->get_backend(context->gogo()));
11903   if (type_tree == error_mark_node)
11904     return error_mark_node;
11905   tree size_tree = TYPE_SIZE_UNIT(type_tree);
11906   tree space = context->gogo()->allocate_memory(this->type_, size_tree,
11907                                                 this->location());
11908   if (space == error_mark_node)
11909     return error_mark_node;
11910   return fold_convert(build_pointer_type(type_tree), space);
11911 }
11912
11913 // Dump ast representation for an allocation expression.
11914
11915 void
11916 Allocation_expression::do_dump_expression(Ast_dump_context* ast_dump_context)
11917     const
11918 {
11919   ast_dump_context->ostream() << "new(";
11920   ast_dump_context->dump_type(this->type_);
11921   ast_dump_context->ostream() << ")";
11922 }
11923
11924 // Make an allocation expression.
11925
11926 Expression*
11927 Expression::make_allocation(Type* type, Location location)
11928 {
11929   return new Allocation_expression(type, location);
11930 }
11931
11932 // Construct a struct.
11933
11934 class Struct_construction_expression : public Expression
11935 {
11936  public:
11937   Struct_construction_expression(Type* type, Expression_list* vals,
11938                                  Location location)
11939     : Expression(EXPRESSION_STRUCT_CONSTRUCTION, location),
11940       type_(type), vals_(vals)
11941   { }
11942
11943   // Return whether this is a constant initializer.
11944   bool
11945   is_constant_struct() const;
11946
11947  protected:
11948   int
11949   do_traverse(Traverse* traverse);
11950
11951   Type*
11952   do_type()
11953   { return this->type_; }
11954
11955   void
11956   do_determine_type(const Type_context*);
11957
11958   void
11959   do_check_types(Gogo*);
11960
11961   Expression*
11962   do_copy()
11963   {
11964     return new Struct_construction_expression(this->type_, this->vals_->copy(),
11965                                               this->location());
11966   }
11967
11968   tree
11969   do_get_tree(Translate_context*);
11970
11971   void
11972   do_export(Export*) const;
11973
11974   void
11975   do_dump_expression(Ast_dump_context*) const;
11976
11977  private:
11978   // The type of the struct to construct.
11979   Type* type_;
11980   // The list of values, in order of the fields in the struct.  A NULL
11981   // entry means that the field should be zero-initialized.
11982   Expression_list* vals_;
11983 };
11984
11985 // Traversal.
11986
11987 int
11988 Struct_construction_expression::do_traverse(Traverse* traverse)
11989 {
11990   if (this->vals_ != NULL
11991       && this->vals_->traverse(traverse) == TRAVERSE_EXIT)
11992     return TRAVERSE_EXIT;
11993   if (Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
11994     return TRAVERSE_EXIT;
11995   return TRAVERSE_CONTINUE;
11996 }
11997
11998 // Return whether this is a constant initializer.
11999
12000 bool
12001 Struct_construction_expression::is_constant_struct() const
12002 {
12003   if (this->vals_ == NULL)
12004     return true;
12005   for (Expression_list::const_iterator pv = this->vals_->begin();
12006        pv != this->vals_->end();
12007        ++pv)
12008     {
12009       if (*pv != NULL
12010           && !(*pv)->is_constant()
12011           && (!(*pv)->is_composite_literal()
12012               || (*pv)->is_nonconstant_composite_literal()))
12013         return false;
12014     }
12015
12016   const Struct_field_list* fields = this->type_->struct_type()->fields();
12017   for (Struct_field_list::const_iterator pf = fields->begin();
12018        pf != fields->end();
12019        ++pf)
12020     {
12021       // There are no constant constructors for interfaces.
12022       if (pf->type()->interface_type() != NULL)
12023         return false;
12024     }
12025
12026   return true;
12027 }
12028
12029 // Final type determination.
12030
12031 void
12032 Struct_construction_expression::do_determine_type(const Type_context*)
12033 {
12034   if (this->vals_ == NULL)
12035     return;
12036   const Struct_field_list* fields = this->type_->struct_type()->fields();
12037   Expression_list::const_iterator pv = this->vals_->begin();
12038   for (Struct_field_list::const_iterator pf = fields->begin();
12039        pf != fields->end();
12040        ++pf, ++pv)
12041     {
12042       if (pv == this->vals_->end())
12043         return;
12044       if (*pv != NULL)
12045         {
12046           Type_context subcontext(pf->type(), false);
12047           (*pv)->determine_type(&subcontext);
12048         }
12049     }
12050   // Extra values are an error we will report elsewhere; we still want
12051   // to determine the type to avoid knockon errors.
12052   for (; pv != this->vals_->end(); ++pv)
12053     (*pv)->determine_type_no_context();
12054 }
12055
12056 // Check types.
12057
12058 void
12059 Struct_construction_expression::do_check_types(Gogo*)
12060 {
12061   if (this->vals_ == NULL)
12062     return;
12063
12064   Struct_type* st = this->type_->struct_type();
12065   if (this->vals_->size() > st->field_count())
12066     {
12067       this->report_error(_("too many expressions for struct"));
12068       return;
12069     }
12070
12071   const Struct_field_list* fields = st->fields();
12072   Expression_list::const_iterator pv = this->vals_->begin();
12073   int i = 0;
12074   for (Struct_field_list::const_iterator pf = fields->begin();
12075        pf != fields->end();
12076        ++pf, ++pv, ++i)
12077     {
12078       if (pv == this->vals_->end())
12079         {
12080           this->report_error(_("too few expressions for struct"));
12081           break;
12082         }
12083
12084       if (*pv == NULL)
12085         continue;
12086
12087       std::string reason;
12088       if (!Type::are_assignable(pf->type(), (*pv)->type(), &reason))
12089         {
12090           if (reason.empty())
12091             error_at((*pv)->location(),
12092                      "incompatible type for field %d in struct construction",
12093                      i + 1);
12094           else
12095             error_at((*pv)->location(),
12096                      ("incompatible type for field %d in "
12097                       "struct construction (%s)"),
12098                      i + 1, reason.c_str());
12099           this->set_is_error();
12100         }
12101     }
12102   go_assert(pv == this->vals_->end());
12103 }
12104
12105 // Return a tree for constructing a struct.
12106
12107 tree
12108 Struct_construction_expression::do_get_tree(Translate_context* context)
12109 {
12110   Gogo* gogo = context->gogo();
12111
12112   if (this->vals_ == NULL)
12113     {
12114       Btype* btype = this->type_->get_backend(gogo);
12115       return expr_to_tree(gogo->backend()->zero_expression(btype));
12116     }
12117
12118   tree type_tree = type_to_tree(this->type_->get_backend(gogo));
12119   if (type_tree == error_mark_node)
12120     return error_mark_node;
12121   go_assert(TREE_CODE(type_tree) == RECORD_TYPE);
12122
12123   bool is_constant = true;
12124   const Struct_field_list* fields = this->type_->struct_type()->fields();
12125   VEC(constructor_elt,gc)* elts = VEC_alloc(constructor_elt, gc,
12126                                             fields->size());
12127   Struct_field_list::const_iterator pf = fields->begin();
12128   Expression_list::const_iterator pv = this->vals_->begin();
12129   for (tree field = TYPE_FIELDS(type_tree);
12130        field != NULL_TREE;
12131        field = DECL_CHAIN(field), ++pf)
12132     {
12133       go_assert(pf != fields->end());
12134
12135       Btype* fbtype = pf->type()->get_backend(gogo);
12136
12137       tree val;
12138       if (pv == this->vals_->end())
12139         val = expr_to_tree(gogo->backend()->zero_expression(fbtype));
12140       else if (*pv == NULL)
12141         {
12142           val = expr_to_tree(gogo->backend()->zero_expression(fbtype));
12143           ++pv;
12144         }
12145       else
12146         {
12147           val = Expression::convert_for_assignment(context, pf->type(),
12148                                                    (*pv)->type(),
12149                                                    (*pv)->get_tree(context),
12150                                                    this->location());
12151           ++pv;
12152         }
12153
12154       if (val == error_mark_node || TREE_TYPE(val) == error_mark_node)
12155         return error_mark_node;
12156
12157       constructor_elt* elt = VEC_quick_push(constructor_elt, elts, NULL);
12158       elt->index = field;
12159       elt->value = val;
12160       if (!TREE_CONSTANT(val))
12161         is_constant = false;
12162     }
12163   go_assert(pf == fields->end());
12164
12165   tree ret = build_constructor(type_tree, elts);
12166   if (is_constant)
12167     TREE_CONSTANT(ret) = 1;
12168   return ret;
12169 }
12170
12171 // Export a struct construction.
12172
12173 void
12174 Struct_construction_expression::do_export(Export* exp) const
12175 {
12176   exp->write_c_string("convert(");
12177   exp->write_type(this->type_);
12178   for (Expression_list::const_iterator pv = this->vals_->begin();
12179        pv != this->vals_->end();
12180        ++pv)
12181     {
12182       exp->write_c_string(", ");
12183       if (*pv != NULL)
12184         (*pv)->export_expression(exp);
12185     }
12186   exp->write_c_string(")");
12187 }
12188
12189 // Dump ast representation of a struct construction expression.
12190
12191 void
12192 Struct_construction_expression::do_dump_expression(
12193     Ast_dump_context* ast_dump_context) const
12194 {
12195   ast_dump_context->dump_type(this->type_);
12196   ast_dump_context->ostream() << "{";
12197   ast_dump_context->dump_expression_list(this->vals_);
12198   ast_dump_context->ostream() << "}";
12199 }
12200
12201 // Make a struct composite literal.  This used by the thunk code.
12202
12203 Expression*
12204 Expression::make_struct_composite_literal(Type* type, Expression_list* vals,
12205                                           Location location)
12206 {
12207   go_assert(type->struct_type() != NULL);
12208   return new Struct_construction_expression(type, vals, location);
12209 }
12210
12211 // Construct an array.  This class is not used directly; instead we
12212 // use the child classes, Fixed_array_construction_expression and
12213 // Open_array_construction_expression.
12214
12215 class Array_construction_expression : public Expression
12216 {
12217  protected:
12218   Array_construction_expression(Expression_classification classification,
12219                                 Type* type, Expression_list* vals,
12220                                 Location location)
12221     : Expression(classification, location),
12222       type_(type), vals_(vals)
12223   { }
12224
12225  public:
12226   // Return whether this is a constant initializer.
12227   bool
12228   is_constant_array() const;
12229
12230   // Return the number of elements.
12231   size_t
12232   element_count() const
12233   { return this->vals_ == NULL ? 0 : this->vals_->size(); }
12234
12235 protected:
12236   int
12237   do_traverse(Traverse* traverse);
12238
12239   Type*
12240   do_type()
12241   { return this->type_; }
12242
12243   void
12244   do_determine_type(const Type_context*);
12245
12246   void
12247   do_check_types(Gogo*);
12248
12249   void
12250   do_export(Export*) const;
12251
12252   // The list of values.
12253   Expression_list*
12254   vals()
12255   { return this->vals_; }
12256
12257   // Get a constructor tree for the array values.
12258   tree
12259   get_constructor_tree(Translate_context* context, tree type_tree);
12260
12261   void
12262   do_dump_expression(Ast_dump_context*) const;
12263
12264  private:
12265   // The type of the array to construct.
12266   Type* type_;
12267   // The list of values.
12268   Expression_list* vals_;
12269 };
12270
12271 // Traversal.
12272
12273 int
12274 Array_construction_expression::do_traverse(Traverse* traverse)
12275 {
12276   if (this->vals_ != NULL
12277       && this->vals_->traverse(traverse) == TRAVERSE_EXIT)
12278     return TRAVERSE_EXIT;
12279   if (Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
12280     return TRAVERSE_EXIT;
12281   return TRAVERSE_CONTINUE;
12282 }
12283
12284 // Return whether this is a constant initializer.
12285
12286 bool
12287 Array_construction_expression::is_constant_array() const
12288 {
12289   if (this->vals_ == NULL)
12290     return true;
12291
12292   // There are no constant constructors for interfaces.
12293   if (this->type_->array_type()->element_type()->interface_type() != NULL)
12294     return false;
12295
12296   for (Expression_list::const_iterator pv = this->vals_->begin();
12297        pv != this->vals_->end();
12298        ++pv)
12299     {
12300       if (*pv != NULL
12301           && !(*pv)->is_constant()
12302           && (!(*pv)->is_composite_literal()
12303               || (*pv)->is_nonconstant_composite_literal()))
12304         return false;
12305     }
12306   return true;
12307 }
12308
12309 // Final type determination.
12310
12311 void
12312 Array_construction_expression::do_determine_type(const Type_context*)
12313 {
12314   if (this->vals_ == NULL)
12315     return;
12316   Type_context subcontext(this->type_->array_type()->element_type(), false);
12317   for (Expression_list::const_iterator pv = this->vals_->begin();
12318        pv != this->vals_->end();
12319        ++pv)
12320     {
12321       if (*pv != NULL)
12322         (*pv)->determine_type(&subcontext);
12323     }
12324 }
12325
12326 // Check types.
12327
12328 void
12329 Array_construction_expression::do_check_types(Gogo*)
12330 {
12331   if (this->vals_ == NULL)
12332     return;
12333
12334   Array_type* at = this->type_->array_type();
12335   int i = 0;
12336   Type* element_type = at->element_type();
12337   for (Expression_list::const_iterator pv = this->vals_->begin();
12338        pv != this->vals_->end();
12339        ++pv, ++i)
12340     {
12341       if (*pv != NULL
12342           && !Type::are_assignable(element_type, (*pv)->type(), NULL))
12343         {
12344           error_at((*pv)->location(),
12345                    "incompatible type for element %d in composite literal",
12346                    i + 1);
12347           this->set_is_error();
12348         }
12349     }
12350
12351   Expression* length = at->length();
12352   if (length != NULL && !length->is_error_expression())
12353     {
12354       mpz_t val;
12355       mpz_init(val);
12356       Type* type;
12357       if (at->length()->integer_constant_value(true, val, &type))
12358         {
12359           if (this->vals_->size() > mpz_get_ui(val))
12360             this->report_error(_("too many elements in composite literal"));
12361         }
12362       mpz_clear(val);
12363     }
12364 }
12365
12366 // Get a constructor tree for the array values.
12367
12368 tree
12369 Array_construction_expression::get_constructor_tree(Translate_context* context,
12370                                                     tree type_tree)
12371 {
12372   VEC(constructor_elt,gc)* values = VEC_alloc(constructor_elt, gc,
12373                                               (this->vals_ == NULL
12374                                                ? 0
12375                                                : this->vals_->size()));
12376   Type* element_type = this->type_->array_type()->element_type();
12377   bool is_constant = true;
12378   if (this->vals_ != NULL)
12379     {
12380       size_t i = 0;
12381       for (Expression_list::const_iterator pv = this->vals_->begin();
12382            pv != this->vals_->end();
12383            ++pv, ++i)
12384         {
12385           constructor_elt* elt = VEC_quick_push(constructor_elt, values, NULL);
12386           elt->index = size_int(i);
12387           if (*pv == NULL)
12388             {
12389               Gogo* gogo = context->gogo();
12390               Btype* ebtype = element_type->get_backend(gogo);
12391               Bexpression *zv = gogo->backend()->zero_expression(ebtype);
12392               elt->value = expr_to_tree(zv);
12393             }
12394           else
12395             {
12396               tree value_tree = (*pv)->get_tree(context);
12397               elt->value = Expression::convert_for_assignment(context,
12398                                                               element_type,
12399                                                               (*pv)->type(),
12400                                                               value_tree,
12401                                                               this->location());
12402             }
12403           if (elt->value == error_mark_node)
12404             return error_mark_node;
12405           if (!TREE_CONSTANT(elt->value))
12406             is_constant = false;
12407         }
12408     }
12409
12410   tree ret = build_constructor(type_tree, values);
12411   if (is_constant)
12412     TREE_CONSTANT(ret) = 1;
12413   return ret;
12414 }
12415
12416 // Export an array construction.
12417
12418 void
12419 Array_construction_expression::do_export(Export* exp) const
12420 {
12421   exp->write_c_string("convert(");
12422   exp->write_type(this->type_);
12423   if (this->vals_ != NULL)
12424     {
12425       for (Expression_list::const_iterator pv = this->vals_->begin();
12426            pv != this->vals_->end();
12427            ++pv)
12428         {
12429           exp->write_c_string(", ");
12430           if (*pv != NULL)
12431             (*pv)->export_expression(exp);
12432         }
12433     }
12434   exp->write_c_string(")");
12435 }
12436
12437 // Dump ast representation of an array construction expressin.
12438
12439 void
12440 Array_construction_expression::do_dump_expression(
12441     Ast_dump_context* ast_dump_context) const
12442 {
12443   Expression* length = this->type_->array_type() != NULL ?
12444                          this->type_->array_type()->length() : NULL;
12445
12446   ast_dump_context->ostream() << "[" ;
12447   if (length != NULL)
12448     {
12449       ast_dump_context->dump_expression(length);
12450     }
12451   ast_dump_context->ostream() << "]" ;
12452   ast_dump_context->dump_type(this->type_);
12453   ast_dump_context->ostream() << "{" ;
12454   ast_dump_context->dump_expression_list(this->vals_);
12455   ast_dump_context->ostream() << "}" ;
12456
12457 }
12458
12459 // Construct a fixed array.
12460
12461 class Fixed_array_construction_expression :
12462   public Array_construction_expression
12463 {
12464  public:
12465   Fixed_array_construction_expression(Type* type, Expression_list* vals,
12466                                       Location location)
12467     : Array_construction_expression(EXPRESSION_FIXED_ARRAY_CONSTRUCTION,
12468                                     type, vals, location)
12469   {
12470     go_assert(type->array_type() != NULL
12471                && type->array_type()->length() != NULL);
12472   }
12473
12474  protected:
12475   Expression*
12476   do_copy()
12477   {
12478     return new Fixed_array_construction_expression(this->type(),
12479                                                    (this->vals() == NULL
12480                                                     ? NULL
12481                                                     : this->vals()->copy()),
12482                                                    this->location());
12483   }
12484
12485   tree
12486   do_get_tree(Translate_context*);
12487
12488   void
12489   do_dump_expression(Ast_dump_context*);
12490 };
12491
12492 // Return a tree for constructing a fixed array.
12493
12494 tree
12495 Fixed_array_construction_expression::do_get_tree(Translate_context* context)
12496 {
12497   Type* type = this->type();
12498   Btype* btype = type->get_backend(context->gogo());
12499   return this->get_constructor_tree(context, type_to_tree(btype));
12500 }
12501
12502 // Dump ast representation of an array construction expressin.
12503
12504 void
12505 Fixed_array_construction_expression::do_dump_expression(
12506     Ast_dump_context* ast_dump_context)
12507 {
12508
12509   ast_dump_context->ostream() << "[";
12510   ast_dump_context->dump_expression (this->type()->array_type()->length());
12511   ast_dump_context->ostream() << "]";
12512   ast_dump_context->dump_type(this->type());
12513   ast_dump_context->ostream() << "{";
12514   ast_dump_context->dump_expression_list(this->vals());
12515   ast_dump_context->ostream() << "}";
12516
12517 }
12518 // Construct an open array.
12519
12520 class Open_array_construction_expression : public Array_construction_expression
12521 {
12522  public:
12523   Open_array_construction_expression(Type* type, Expression_list* vals,
12524                                      Location location)
12525     : Array_construction_expression(EXPRESSION_OPEN_ARRAY_CONSTRUCTION,
12526                                     type, vals, location)
12527   {
12528     go_assert(type->array_type() != NULL
12529                && type->array_type()->length() == NULL);
12530   }
12531
12532  protected:
12533   // Note that taking the address of an open array literal is invalid.
12534
12535   Expression*
12536   do_copy()
12537   {
12538     return new Open_array_construction_expression(this->type(),
12539                                                   (this->vals() == NULL
12540                                                    ? NULL
12541                                                    : this->vals()->copy()),
12542                                                   this->location());
12543   }
12544
12545   tree
12546   do_get_tree(Translate_context*);
12547 };
12548
12549 // Return a tree for constructing an open array.
12550
12551 tree
12552 Open_array_construction_expression::do_get_tree(Translate_context* context)
12553 {
12554   Array_type* array_type = this->type()->array_type();
12555   if (array_type == NULL)
12556     {
12557       go_assert(this->type()->is_error());
12558       return error_mark_node;
12559     }
12560
12561   Type* element_type = array_type->element_type();
12562   Btype* belement_type = element_type->get_backend(context->gogo());
12563   tree element_type_tree = type_to_tree(belement_type);
12564   if (element_type_tree == error_mark_node)
12565     return error_mark_node;
12566
12567   tree values;
12568   tree length_tree;
12569   if (this->vals() == NULL || this->vals()->empty())
12570     {
12571       // We need to create a unique value.
12572       tree max = size_int(0);
12573       tree constructor_type = build_array_type(element_type_tree,
12574                                                build_index_type(max));
12575       if (constructor_type == error_mark_node)
12576         return error_mark_node;
12577       VEC(constructor_elt,gc)* vec = VEC_alloc(constructor_elt, gc, 1);
12578       constructor_elt* elt = VEC_quick_push(constructor_elt, vec, NULL);
12579       elt->index = size_int(0);
12580       Gogo* gogo = context->gogo();
12581       Btype* btype = element_type->get_backend(gogo);
12582       elt->value = expr_to_tree(gogo->backend()->zero_expression(btype));
12583       values = build_constructor(constructor_type, vec);
12584       if (TREE_CONSTANT(elt->value))
12585         TREE_CONSTANT(values) = 1;
12586       length_tree = size_int(0);
12587     }
12588   else
12589     {
12590       tree max = size_int(this->vals()->size() - 1);
12591       tree constructor_type = build_array_type(element_type_tree,
12592                                                build_index_type(max));
12593       if (constructor_type == error_mark_node)
12594         return error_mark_node;
12595       values = this->get_constructor_tree(context, constructor_type);
12596       length_tree = size_int(this->vals()->size());
12597     }
12598
12599   if (values == error_mark_node)
12600     return error_mark_node;
12601
12602   bool is_constant_initializer = TREE_CONSTANT(values);
12603
12604   // We have to copy the initial values into heap memory if we are in
12605   // a function or if the values are not constants.  We also have to
12606   // copy them if they may contain pointers in a non-constant context,
12607   // as otherwise the garbage collector won't see them.
12608   bool copy_to_heap = (context->function() != NULL
12609                        || !is_constant_initializer
12610                        || (element_type->has_pointer()
12611                            && !context->is_const()));
12612
12613   if (is_constant_initializer)
12614     {
12615       tree tmp = build_decl(this->location().gcc_location(), VAR_DECL,
12616                             create_tmp_var_name("C"), TREE_TYPE(values));
12617       DECL_EXTERNAL(tmp) = 0;
12618       TREE_PUBLIC(tmp) = 0;
12619       TREE_STATIC(tmp) = 1;
12620       DECL_ARTIFICIAL(tmp) = 1;
12621       if (copy_to_heap)
12622         {
12623           // If we are not copying the value to the heap, we will only
12624           // initialize the value once, so we can use this directly
12625           // rather than copying it.  In that case we can't make it
12626           // read-only, because the program is permitted to change it.
12627           TREE_READONLY(tmp) = 1;
12628           TREE_CONSTANT(tmp) = 1;
12629         }
12630       DECL_INITIAL(tmp) = values;
12631       rest_of_decl_compilation(tmp, 1, 0);
12632       values = tmp;
12633     }
12634
12635   tree space;
12636   tree set;
12637   if (!copy_to_heap)
12638     {
12639       // the initializer will only run once.
12640       space = build_fold_addr_expr(values);
12641       set = NULL_TREE;
12642     }
12643   else
12644     {
12645       tree memsize = TYPE_SIZE_UNIT(TREE_TYPE(values));
12646       space = context->gogo()->allocate_memory(element_type, memsize,
12647                                                this->location());
12648       space = save_expr(space);
12649
12650       tree s = fold_convert(build_pointer_type(TREE_TYPE(values)), space);
12651       tree ref = build_fold_indirect_ref_loc(this->location().gcc_location(),
12652                                              s);
12653       TREE_THIS_NOTRAP(ref) = 1;
12654       set = build2(MODIFY_EXPR, void_type_node, ref, values);
12655     }
12656
12657   // Build a constructor for the open array.
12658
12659   tree type_tree = type_to_tree(this->type()->get_backend(context->gogo()));
12660   if (type_tree == error_mark_node)
12661     return error_mark_node;
12662   go_assert(TREE_CODE(type_tree) == RECORD_TYPE);
12663
12664   VEC(constructor_elt,gc)* init = VEC_alloc(constructor_elt, gc, 3);
12665
12666   constructor_elt* elt = VEC_quick_push(constructor_elt, init, NULL);
12667   tree field = TYPE_FIELDS(type_tree);
12668   go_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__values") == 0);
12669   elt->index = field;
12670   elt->value = fold_convert(TREE_TYPE(field), space);
12671
12672   elt = VEC_quick_push(constructor_elt, init, NULL);
12673   field = DECL_CHAIN(field);
12674   go_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__count") == 0);
12675   elt->index = field;
12676   elt->value = fold_convert(TREE_TYPE(field), length_tree);
12677
12678   elt = VEC_quick_push(constructor_elt, init, NULL);
12679   field = DECL_CHAIN(field);
12680   go_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)),"__capacity") == 0);
12681   elt->index = field;
12682   elt->value = fold_convert(TREE_TYPE(field), length_tree);
12683
12684   tree constructor = build_constructor(type_tree, init);
12685   if (constructor == error_mark_node)
12686     return error_mark_node;
12687   if (!copy_to_heap)
12688     TREE_CONSTANT(constructor) = 1;
12689
12690   if (set == NULL_TREE)
12691     return constructor;
12692   else
12693     return build2(COMPOUND_EXPR, type_tree, set, constructor);
12694 }
12695
12696 // Make a slice composite literal.  This is used by the type
12697 // descriptor code.
12698
12699 Expression*
12700 Expression::make_slice_composite_literal(Type* type, Expression_list* vals,
12701                                          Location location)
12702 {
12703   go_assert(type->is_slice_type());
12704   return new Open_array_construction_expression(type, vals, location);
12705 }
12706
12707 // Construct a map.
12708
12709 class Map_construction_expression : public Expression
12710 {
12711  public:
12712   Map_construction_expression(Type* type, Expression_list* vals,
12713                               Location location)
12714     : Expression(EXPRESSION_MAP_CONSTRUCTION, location),
12715       type_(type), vals_(vals)
12716   { go_assert(vals == NULL || vals->size() % 2 == 0); }
12717
12718  protected:
12719   int
12720   do_traverse(Traverse* traverse);
12721
12722   Type*
12723   do_type()
12724   { return this->type_; }
12725
12726   void
12727   do_determine_type(const Type_context*);
12728
12729   void
12730   do_check_types(Gogo*);
12731
12732   Expression*
12733   do_copy()
12734   {
12735     return new Map_construction_expression(this->type_, this->vals_->copy(),
12736                                            this->location());
12737   }
12738
12739   tree
12740   do_get_tree(Translate_context*);
12741
12742   void
12743   do_export(Export*) const;
12744
12745   void
12746   do_dump_expression(Ast_dump_context*) const;
12747
12748  private:
12749   // The type of the map to construct.
12750   Type* type_;
12751   // The list of values.
12752   Expression_list* vals_;
12753 };
12754
12755 // Traversal.
12756
12757 int
12758 Map_construction_expression::do_traverse(Traverse* traverse)
12759 {
12760   if (this->vals_ != NULL
12761       && this->vals_->traverse(traverse) == TRAVERSE_EXIT)
12762     return TRAVERSE_EXIT;
12763   if (Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
12764     return TRAVERSE_EXIT;
12765   return TRAVERSE_CONTINUE;
12766 }
12767
12768 // Final type determination.
12769
12770 void
12771 Map_construction_expression::do_determine_type(const Type_context*)
12772 {
12773   if (this->vals_ == NULL)
12774     return;
12775
12776   Map_type* mt = this->type_->map_type();
12777   Type_context key_context(mt->key_type(), false);
12778   Type_context val_context(mt->val_type(), false);
12779   for (Expression_list::const_iterator pv = this->vals_->begin();
12780        pv != this->vals_->end();
12781        ++pv)
12782     {
12783       (*pv)->determine_type(&key_context);
12784       ++pv;
12785       (*pv)->determine_type(&val_context);
12786     }
12787 }
12788
12789 // Check types.
12790
12791 void
12792 Map_construction_expression::do_check_types(Gogo*)
12793 {
12794   if (this->vals_ == NULL)
12795     return;
12796
12797   Map_type* mt = this->type_->map_type();
12798   int i = 0;
12799   Type* key_type = mt->key_type();
12800   Type* val_type = mt->val_type();
12801   for (Expression_list::const_iterator pv = this->vals_->begin();
12802        pv != this->vals_->end();
12803        ++pv, ++i)
12804     {
12805       if (!Type::are_assignable(key_type, (*pv)->type(), NULL))
12806         {
12807           error_at((*pv)->location(),
12808                    "incompatible type for element %d key in map construction",
12809                    i + 1);
12810           this->set_is_error();
12811         }
12812       ++pv;
12813       if (!Type::are_assignable(val_type, (*pv)->type(), NULL))
12814         {
12815           error_at((*pv)->location(),
12816                    ("incompatible type for element %d value "
12817                     "in map construction"),
12818                    i + 1);
12819           this->set_is_error();
12820         }
12821     }
12822 }
12823
12824 // Return a tree for constructing a map.
12825
12826 tree
12827 Map_construction_expression::do_get_tree(Translate_context* context)
12828 {
12829   Gogo* gogo = context->gogo();
12830   Location loc = this->location();
12831
12832   Map_type* mt = this->type_->map_type();
12833
12834   // Build a struct to hold the key and value.
12835   tree struct_type = make_node(RECORD_TYPE);
12836
12837   Type* key_type = mt->key_type();
12838   tree id = get_identifier("__key");
12839   tree key_type_tree = type_to_tree(key_type->get_backend(gogo));
12840   if (key_type_tree == error_mark_node)
12841     return error_mark_node;
12842   tree key_field = build_decl(loc.gcc_location(), FIELD_DECL, id,
12843                               key_type_tree);
12844   DECL_CONTEXT(key_field) = struct_type;
12845   TYPE_FIELDS(struct_type) = key_field;
12846
12847   Type* val_type = mt->val_type();
12848   id = get_identifier("__val");
12849   tree val_type_tree = type_to_tree(val_type->get_backend(gogo));
12850   if (val_type_tree == error_mark_node)
12851     return error_mark_node;
12852   tree val_field = build_decl(loc.gcc_location(), FIELD_DECL, id,
12853                               val_type_tree);
12854   DECL_CONTEXT(val_field) = struct_type;
12855   DECL_CHAIN(key_field) = val_field;
12856
12857   layout_type(struct_type);
12858
12859   bool is_constant = true;
12860   size_t i = 0;
12861   tree valaddr;
12862   tree make_tmp;
12863
12864   if (this->vals_ == NULL || this->vals_->empty())
12865     {
12866       valaddr = null_pointer_node;
12867       make_tmp = NULL_TREE;
12868     }
12869   else
12870     {
12871       VEC(constructor_elt,gc)* values = VEC_alloc(constructor_elt, gc,
12872                                                   this->vals_->size() / 2);
12873
12874       for (Expression_list::const_iterator pv = this->vals_->begin();
12875            pv != this->vals_->end();
12876            ++pv, ++i)
12877         {
12878           bool one_is_constant = true;
12879
12880           VEC(constructor_elt,gc)* one = VEC_alloc(constructor_elt, gc, 2);
12881
12882           constructor_elt* elt = VEC_quick_push(constructor_elt, one, NULL);
12883           elt->index = key_field;
12884           tree val_tree = (*pv)->get_tree(context);
12885           elt->value = Expression::convert_for_assignment(context, key_type,
12886                                                           (*pv)->type(),
12887                                                           val_tree, loc);
12888           if (elt->value == error_mark_node)
12889             return error_mark_node;
12890           if (!TREE_CONSTANT(elt->value))
12891             one_is_constant = false;
12892
12893           ++pv;
12894
12895           elt = VEC_quick_push(constructor_elt, one, NULL);
12896           elt->index = val_field;
12897           val_tree = (*pv)->get_tree(context);
12898           elt->value = Expression::convert_for_assignment(context, val_type,
12899                                                           (*pv)->type(),
12900                                                           val_tree, loc);
12901           if (elt->value == error_mark_node)
12902             return error_mark_node;
12903           if (!TREE_CONSTANT(elt->value))
12904             one_is_constant = false;
12905
12906           elt = VEC_quick_push(constructor_elt, values, NULL);
12907           elt->index = size_int(i);
12908           elt->value = build_constructor(struct_type, one);
12909           if (one_is_constant)
12910             TREE_CONSTANT(elt->value) = 1;
12911           else
12912             is_constant = false;
12913         }
12914
12915       tree index_type = build_index_type(size_int(i - 1));
12916       tree array_type = build_array_type(struct_type, index_type);
12917       tree init = build_constructor(array_type, values);
12918       if (is_constant)
12919         TREE_CONSTANT(init) = 1;
12920       tree tmp;
12921       if (current_function_decl != NULL)
12922         {
12923           tmp = create_tmp_var(array_type, get_name(array_type));
12924           DECL_INITIAL(tmp) = init;
12925           make_tmp = fold_build1_loc(loc.gcc_location(), DECL_EXPR,
12926                                      void_type_node, tmp);
12927           TREE_ADDRESSABLE(tmp) = 1;
12928         }
12929       else
12930         {
12931           tmp = build_decl(loc.gcc_location(), VAR_DECL,
12932                            create_tmp_var_name("M"), array_type);
12933           DECL_EXTERNAL(tmp) = 0;
12934           TREE_PUBLIC(tmp) = 0;
12935           TREE_STATIC(tmp) = 1;
12936           DECL_ARTIFICIAL(tmp) = 1;
12937           if (!TREE_CONSTANT(init))
12938             make_tmp = fold_build2_loc(loc.gcc_location(), INIT_EXPR,
12939                                        void_type_node, tmp, init);
12940           else
12941             {
12942               TREE_READONLY(tmp) = 1;
12943               TREE_CONSTANT(tmp) = 1;
12944               DECL_INITIAL(tmp) = init;
12945               make_tmp = NULL_TREE;
12946             }
12947           rest_of_decl_compilation(tmp, 1, 0);
12948         }
12949
12950       valaddr = build_fold_addr_expr(tmp);
12951     }
12952
12953   tree descriptor = mt->map_descriptor_pointer(gogo, loc);
12954
12955   tree type_tree = type_to_tree(this->type_->get_backend(gogo));
12956   if (type_tree == error_mark_node)
12957     return error_mark_node;
12958
12959   static tree construct_map_fndecl;
12960   tree call = Gogo::call_builtin(&construct_map_fndecl,
12961                                  loc,
12962                                  "__go_construct_map",
12963                                  6,
12964                                  type_tree,
12965                                  TREE_TYPE(descriptor),
12966                                  descriptor,
12967                                  sizetype,
12968                                  size_int(i),
12969                                  sizetype,
12970                                  TYPE_SIZE_UNIT(struct_type),
12971                                  sizetype,
12972                                  byte_position(val_field),
12973                                  sizetype,
12974                                  TYPE_SIZE_UNIT(TREE_TYPE(val_field)),
12975                                  const_ptr_type_node,
12976                                  fold_convert(const_ptr_type_node, valaddr));
12977   if (call == error_mark_node)
12978     return error_mark_node;
12979
12980   tree ret;
12981   if (make_tmp == NULL)
12982     ret = call;
12983   else
12984     ret = fold_build2_loc(loc.gcc_location(), COMPOUND_EXPR, type_tree,
12985                           make_tmp, call);
12986   return ret;
12987 }
12988
12989 // Export an array construction.
12990
12991 void
12992 Map_construction_expression::do_export(Export* exp) const
12993 {
12994   exp->write_c_string("convert(");
12995   exp->write_type(this->type_);
12996   for (Expression_list::const_iterator pv = this->vals_->begin();
12997        pv != this->vals_->end();
12998        ++pv)
12999     {
13000       exp->write_c_string(", ");
13001       (*pv)->export_expression(exp);
13002     }
13003   exp->write_c_string(")");
13004 }
13005
13006 // Dump ast representation for a map construction expression.
13007
13008 void
13009 Map_construction_expression::do_dump_expression(
13010     Ast_dump_context* ast_dump_context) const
13011 {
13012   ast_dump_context->ostream() << "{" ;
13013   ast_dump_context->dump_expression_list(this->vals_, true);
13014   ast_dump_context->ostream() << "}";
13015 }
13016
13017 // A general composite literal.  This is lowered to a type specific
13018 // version.
13019
13020 class Composite_literal_expression : public Parser_expression
13021 {
13022  public:
13023   Composite_literal_expression(Type* type, int depth, bool has_keys,
13024                                Expression_list* vals, Location location)
13025     : Parser_expression(EXPRESSION_COMPOSITE_LITERAL, location),
13026       type_(type), depth_(depth), vals_(vals), has_keys_(has_keys)
13027   { }
13028
13029  protected:
13030   int
13031   do_traverse(Traverse* traverse);
13032
13033   Expression*
13034   do_lower(Gogo*, Named_object*, Statement_inserter*, int);
13035
13036   Expression*
13037   do_copy()
13038   {
13039     return new Composite_literal_expression(this->type_, this->depth_,
13040                                             this->has_keys_,
13041                                             (this->vals_ == NULL
13042                                              ? NULL
13043                                              : this->vals_->copy()),
13044                                             this->location());
13045   }
13046
13047   void
13048   do_dump_expression(Ast_dump_context*) const;
13049
13050  private:
13051   Expression*
13052   lower_struct(Gogo*, Type*);
13053
13054   Expression*
13055   lower_array(Type*);
13056
13057   Expression*
13058   make_array(Type*, Expression_list*);
13059
13060   Expression*
13061   lower_map(Gogo*, Named_object*, Statement_inserter*, Type*);
13062
13063   // The type of the composite literal.
13064   Type* type_;
13065   // The depth within a list of composite literals within a composite
13066   // literal, when the type is omitted.
13067   int depth_;
13068   // The values to put in the composite literal.
13069   Expression_list* vals_;
13070   // If this is true, then VALS_ is a list of pairs: a key and a
13071   // value.  In an array initializer, a missing key will be NULL.
13072   bool has_keys_;
13073 };
13074
13075 // Traversal.
13076
13077 int
13078 Composite_literal_expression::do_traverse(Traverse* traverse)
13079 {
13080   if (this->vals_ != NULL
13081       && this->vals_->traverse(traverse) == TRAVERSE_EXIT)
13082     return TRAVERSE_EXIT;
13083   return Type::traverse(this->type_, traverse);
13084 }
13085
13086 // Lower a generic composite literal into a specific version based on
13087 // the type.
13088
13089 Expression*
13090 Composite_literal_expression::do_lower(Gogo* gogo, Named_object* function,
13091                                        Statement_inserter* inserter, int)
13092 {
13093   Type* type = this->type_;
13094
13095   for (int depth = this->depth_; depth > 0; --depth)
13096     {
13097       if (type->array_type() != NULL)
13098         type = type->array_type()->element_type();
13099       else if (type->map_type() != NULL)
13100         type = type->map_type()->val_type();
13101       else
13102         {
13103           if (!type->is_error())
13104             error_at(this->location(),
13105                      ("may only omit types within composite literals "
13106                       "of slice, array, or map type"));
13107           return Expression::make_error(this->location());
13108         }
13109     }
13110
13111   Type *pt = type->points_to();
13112   bool is_pointer = false;
13113   if (pt != NULL)
13114     {
13115       is_pointer = true;
13116       type = pt;
13117     }
13118
13119   Expression* ret;
13120   if (type->is_error())
13121     return Expression::make_error(this->location());
13122   else if (type->struct_type() != NULL)
13123     ret = this->lower_struct(gogo, type);
13124   else if (type->array_type() != NULL)
13125     ret = this->lower_array(type);
13126   else if (type->map_type() != NULL)
13127     ret = this->lower_map(gogo, function, inserter, type);
13128   else
13129     {
13130       error_at(this->location(),
13131                ("expected struct, slice, array, or map type "
13132                 "for composite literal"));
13133       return Expression::make_error(this->location());
13134     }
13135
13136   if (is_pointer)
13137     ret = Expression::make_heap_composite(ret, this->location());
13138
13139   return ret;
13140 }
13141
13142 // Lower a struct composite literal.
13143
13144 Expression*
13145 Composite_literal_expression::lower_struct(Gogo* gogo, Type* type)
13146 {
13147   Location location = this->location();
13148   Struct_type* st = type->struct_type();
13149   if (this->vals_ == NULL || !this->has_keys_)
13150     {
13151       if (this->vals_ != NULL
13152           && !this->vals_->empty()
13153           && type->named_type() != NULL
13154           && type->named_type()->named_object()->package() != NULL)
13155         {
13156           for (Struct_field_list::const_iterator pf = st->fields()->begin();
13157                pf != st->fields()->end();
13158                ++pf)
13159             {
13160               if (Gogo::is_hidden_name(pf->field_name()))
13161                 error_at(this->location(),
13162                          "assignment of unexported field %qs in %qs literal",
13163                          Gogo::message_name(pf->field_name()).c_str(),
13164                          type->named_type()->message_name().c_str());
13165             }
13166         }
13167
13168       return new Struct_construction_expression(type, this->vals_, location);
13169     }
13170
13171   size_t field_count = st->field_count();
13172   std::vector<Expression*> vals(field_count);
13173   Expression_list::const_iterator p = this->vals_->begin();
13174   while (p != this->vals_->end())
13175     {
13176       Expression* name_expr = *p;
13177
13178       ++p;
13179       go_assert(p != this->vals_->end());
13180       Expression* val = *p;
13181
13182       ++p;
13183
13184       if (name_expr == NULL)
13185         {
13186           error_at(val->location(), "mixture of field and value initializers");
13187           return Expression::make_error(location);
13188         }
13189
13190       bool bad_key = false;
13191       std::string name;
13192       const Named_object* no = NULL;
13193       switch (name_expr->classification())
13194         {
13195         case EXPRESSION_UNKNOWN_REFERENCE:
13196           name = name_expr->unknown_expression()->name();
13197           break;
13198
13199         case EXPRESSION_CONST_REFERENCE:
13200           no = static_cast<Const_expression*>(name_expr)->named_object();
13201           break;
13202
13203         case EXPRESSION_TYPE:
13204           {
13205             Type* t = name_expr->type();
13206             Named_type* nt = t->named_type();
13207             if (nt == NULL)
13208               bad_key = true;
13209             else
13210               no = nt->named_object();
13211           }
13212           break;
13213
13214         case EXPRESSION_VAR_REFERENCE:
13215           no = name_expr->var_expression()->named_object();
13216           break;
13217
13218         case EXPRESSION_FUNC_REFERENCE:
13219           no = name_expr->func_expression()->named_object();
13220           break;
13221
13222         case EXPRESSION_UNARY:
13223           // If there is a local variable around with the same name as
13224           // the field, and this occurs in the closure, then the
13225           // parser may turn the field reference into an indirection
13226           // through the closure.  FIXME: This is a mess.
13227           {
13228             bad_key = true;
13229             Unary_expression* ue = static_cast<Unary_expression*>(name_expr);
13230             if (ue->op() == OPERATOR_MULT)
13231               {
13232                 Field_reference_expression* fre =
13233                   ue->operand()->field_reference_expression();
13234                 if (fre != NULL)
13235                   {
13236                     Struct_type* st =
13237                       fre->expr()->type()->deref()->struct_type();
13238                     if (st != NULL)
13239                       {
13240                         const Struct_field* sf = st->field(fre->field_index());
13241                         name = sf->field_name();
13242
13243                         // See below.  FIXME.
13244                         if (!Gogo::is_hidden_name(name)
13245                             && name[0] >= 'a'
13246                             && name[0] <= 'z')
13247                           {
13248                             if (gogo->lookup_global(name.c_str()) != NULL)
13249                               name = gogo->pack_hidden_name(name, false);
13250                           }
13251
13252                         char buf[20];
13253                         snprintf(buf, sizeof buf, "%u", fre->field_index());
13254                         size_t buflen = strlen(buf);
13255                         if (name.compare(name.length() - buflen, buflen, buf)
13256                             == 0)
13257                           {
13258                             name = name.substr(0, name.length() - buflen);
13259                             bad_key = false;
13260                           }
13261                       }
13262                   }
13263               }
13264           }
13265           break;
13266
13267         default:
13268           bad_key = true;
13269           break;
13270         }
13271       if (bad_key)
13272         {
13273           error_at(name_expr->location(), "expected struct field name");
13274           return Expression::make_error(location);
13275         }
13276
13277       if (no != NULL)
13278         {
13279           name = no->name();
13280
13281           // A predefined name won't be packed.  If it starts with a
13282           // lower case letter we need to check for that case, because
13283           // the field name will be packed.  FIXME.
13284           if (!Gogo::is_hidden_name(name)
13285               && name[0] >= 'a'
13286               && name[0] <= 'z')
13287             {
13288               Named_object* gno = gogo->lookup_global(name.c_str());
13289               if (gno == no)
13290                 name = gogo->pack_hidden_name(name, false);
13291             }
13292         }
13293
13294       unsigned int index;
13295       const Struct_field* sf = st->find_local_field(name, &index);
13296       if (sf == NULL)
13297         {
13298           error_at(name_expr->location(), "unknown field %qs in %qs",
13299                    Gogo::message_name(name).c_str(),
13300                    (type->named_type() != NULL
13301                     ? type->named_type()->message_name().c_str()
13302                     : "unnamed struct"));
13303           return Expression::make_error(location);
13304         }
13305       if (vals[index] != NULL)
13306         {
13307           error_at(name_expr->location(),
13308                    "duplicate value for field %qs in %qs",
13309                    Gogo::message_name(name).c_str(),
13310                    (type->named_type() != NULL
13311                     ? type->named_type()->message_name().c_str()
13312                     : "unnamed struct"));
13313           return Expression::make_error(location);
13314         }
13315
13316       if (type->named_type() != NULL
13317           && type->named_type()->named_object()->package() != NULL
13318           && Gogo::is_hidden_name(sf->field_name()))
13319         error_at(name_expr->location(),
13320                  "assignment of unexported field %qs in %qs literal",
13321                  Gogo::message_name(sf->field_name()).c_str(),
13322                  type->named_type()->message_name().c_str());
13323
13324       vals[index] = val;
13325     }
13326
13327   Expression_list* list = new Expression_list;
13328   list->reserve(field_count);
13329   for (size_t i = 0; i < field_count; ++i)
13330     list->push_back(vals[i]);
13331
13332   return new Struct_construction_expression(type, list, location);
13333 }
13334
13335 // Lower an array composite literal.
13336
13337 Expression*
13338 Composite_literal_expression::lower_array(Type* type)
13339 {
13340   Location location = this->location();
13341   if (this->vals_ == NULL || !this->has_keys_)
13342     return this->make_array(type, this->vals_);
13343
13344   std::vector<Expression*> vals;
13345   vals.reserve(this->vals_->size());
13346   unsigned long index = 0;
13347   Expression_list::const_iterator p = this->vals_->begin();
13348   while (p != this->vals_->end())
13349     {
13350       Expression* index_expr = *p;
13351
13352       ++p;
13353       go_assert(p != this->vals_->end());
13354       Expression* val = *p;
13355
13356       ++p;
13357
13358       if (index_expr != NULL)
13359         {
13360           mpz_t ival;
13361           mpz_init(ival);
13362
13363           Type* dummy;
13364           if (!index_expr->integer_constant_value(true, ival, &dummy))
13365             {
13366               mpz_clear(ival);
13367               error_at(index_expr->location(),
13368                        "index expression is not integer constant");
13369               return Expression::make_error(location);
13370             }
13371
13372           if (mpz_sgn(ival) < 0)
13373             {
13374               mpz_clear(ival);
13375               error_at(index_expr->location(), "index expression is negative");
13376               return Expression::make_error(location);
13377             }
13378
13379           index = mpz_get_ui(ival);
13380           if (mpz_cmp_ui(ival, index) != 0)
13381             {
13382               mpz_clear(ival);
13383               error_at(index_expr->location(), "index value overflow");
13384               return Expression::make_error(location);
13385             }
13386
13387           Named_type* ntype = Type::lookup_integer_type("int");
13388           Integer_type* inttype = ntype->integer_type();
13389           mpz_t max;
13390           mpz_init_set_ui(max, 1);
13391           mpz_mul_2exp(max, max, inttype->bits() - 1);
13392           bool ok = mpz_cmp(ival, max) < 0;
13393           mpz_clear(max);
13394           if (!ok)
13395             {
13396               mpz_clear(ival);
13397               error_at(index_expr->location(), "index value overflow");
13398               return Expression::make_error(location);
13399             }
13400
13401           mpz_clear(ival);
13402
13403           // FIXME: Our representation isn't very good; this avoids
13404           // thrashing.
13405           if (index > 0x1000000)
13406             {
13407               error_at(index_expr->location(), "index too large for compiler");
13408               return Expression::make_error(location);
13409             }
13410         }
13411
13412       if (index == vals.size())
13413         vals.push_back(val);
13414       else
13415         {
13416           if (index > vals.size())
13417             {
13418               vals.reserve(index + 32);
13419               vals.resize(index + 1, static_cast<Expression*>(NULL));
13420             }
13421           if (vals[index] != NULL)
13422             {
13423               error_at((index_expr != NULL
13424                         ? index_expr->location()
13425                         : val->location()),
13426                        "duplicate value for index %lu",
13427                        index);
13428               return Expression::make_error(location);
13429             }
13430           vals[index] = val;
13431         }
13432
13433       ++index;
13434     }
13435
13436   size_t size = vals.size();
13437   Expression_list* list = new Expression_list;
13438   list->reserve(size);
13439   for (size_t i = 0; i < size; ++i)
13440     list->push_back(vals[i]);
13441
13442   return this->make_array(type, list);
13443 }
13444
13445 // Actually build the array composite literal. This handles
13446 // [...]{...}.
13447
13448 Expression*
13449 Composite_literal_expression::make_array(Type* type, Expression_list* vals)
13450 {
13451   Location location = this->location();
13452   Array_type* at = type->array_type();
13453   if (at->length() != NULL && at->length()->is_nil_expression())
13454     {
13455       size_t size = vals == NULL ? 0 : vals->size();
13456       mpz_t vlen;
13457       mpz_init_set_ui(vlen, size);
13458       Expression* elen = Expression::make_integer(&vlen, NULL, location);
13459       mpz_clear(vlen);
13460       at = Type::make_array_type(at->element_type(), elen);
13461       type = at;
13462     }
13463   if (at->length() != NULL)
13464     return new Fixed_array_construction_expression(type, vals, location);
13465   else
13466     return new Open_array_construction_expression(type, vals, location);
13467 }
13468
13469 // Lower a map composite literal.
13470
13471 Expression*
13472 Composite_literal_expression::lower_map(Gogo* gogo, Named_object* function,
13473                                         Statement_inserter* inserter,
13474                                         Type* type)
13475 {
13476   Location location = this->location();
13477   if (this->vals_ != NULL)
13478     {
13479       if (!this->has_keys_)
13480         {
13481           error_at(location, "map composite literal must have keys");
13482           return Expression::make_error(location);
13483         }
13484
13485       for (Expression_list::iterator p = this->vals_->begin();
13486            p != this->vals_->end();
13487            p += 2)
13488         {
13489           if (*p == NULL)
13490             {
13491               ++p;
13492               error_at((*p)->location(),
13493                        "map composite literal must have keys for every value");
13494               return Expression::make_error(location);
13495             }
13496           // Make sure we have lowered the key; it may not have been
13497           // lowered in order to handle keys for struct composite
13498           // literals.  Lower it now to get the right error message.
13499           if ((*p)->unknown_expression() != NULL)
13500             {
13501               (*p)->unknown_expression()->clear_is_composite_literal_key();
13502               gogo->lower_expression(function, inserter, &*p);
13503               go_assert((*p)->is_error_expression());
13504               return Expression::make_error(location);
13505             }
13506         }
13507     }
13508
13509   return new Map_construction_expression(type, this->vals_, location);
13510 }
13511
13512 // Dump ast representation for a composite literal expression.
13513
13514 void
13515 Composite_literal_expression::do_dump_expression(
13516                                Ast_dump_context* ast_dump_context) const
13517 {
13518   ast_dump_context->ostream() << "composite(";
13519   ast_dump_context->dump_type(this->type_);
13520   ast_dump_context->ostream() << ", {";
13521   ast_dump_context->dump_expression_list(this->vals_, this->has_keys_);
13522   ast_dump_context->ostream() << "})";
13523 }
13524
13525 // Make a composite literal expression.
13526
13527 Expression*
13528 Expression::make_composite_literal(Type* type, int depth, bool has_keys,
13529                                    Expression_list* vals,
13530                                    Location location)
13531 {
13532   return new Composite_literal_expression(type, depth, has_keys, vals,
13533                                           location);
13534 }
13535
13536 // Return whether this expression is a composite literal.
13537
13538 bool
13539 Expression::is_composite_literal() const
13540 {
13541   switch (this->classification_)
13542     {
13543     case EXPRESSION_COMPOSITE_LITERAL:
13544     case EXPRESSION_STRUCT_CONSTRUCTION:
13545     case EXPRESSION_FIXED_ARRAY_CONSTRUCTION:
13546     case EXPRESSION_OPEN_ARRAY_CONSTRUCTION:
13547     case EXPRESSION_MAP_CONSTRUCTION:
13548       return true;
13549     default:
13550       return false;
13551     }
13552 }
13553
13554 // Return whether this expression is a composite literal which is not
13555 // constant.
13556
13557 bool
13558 Expression::is_nonconstant_composite_literal() const
13559 {
13560   switch (this->classification_)
13561     {
13562     case EXPRESSION_STRUCT_CONSTRUCTION:
13563       {
13564         const Struct_construction_expression *psce =
13565           static_cast<const Struct_construction_expression*>(this);
13566         return !psce->is_constant_struct();
13567       }
13568     case EXPRESSION_FIXED_ARRAY_CONSTRUCTION:
13569       {
13570         const Fixed_array_construction_expression *pace =
13571           static_cast<const Fixed_array_construction_expression*>(this);
13572         return !pace->is_constant_array();
13573       }
13574     case EXPRESSION_OPEN_ARRAY_CONSTRUCTION:
13575       {
13576         const Open_array_construction_expression *pace =
13577           static_cast<const Open_array_construction_expression*>(this);
13578         return !pace->is_constant_array();
13579       }
13580     case EXPRESSION_MAP_CONSTRUCTION:
13581       return true;
13582     default:
13583       return false;
13584     }
13585 }
13586
13587 // Return true if this is a reference to a local variable.
13588
13589 bool
13590 Expression::is_local_variable() const
13591 {
13592   const Var_expression* ve = this->var_expression();
13593   if (ve == NULL)
13594     return false;
13595   const Named_object* no = ve->named_object();
13596   return (no->is_result_variable()
13597           || (no->is_variable() && !no->var_value()->is_global()));
13598 }
13599
13600 // Class Type_guard_expression.
13601
13602 // Traversal.
13603
13604 int
13605 Type_guard_expression::do_traverse(Traverse* traverse)
13606 {
13607   if (Expression::traverse(&this->expr_, traverse) == TRAVERSE_EXIT
13608       || Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
13609     return TRAVERSE_EXIT;
13610   return TRAVERSE_CONTINUE;
13611 }
13612
13613 // Check types of a type guard expression.  The expression must have
13614 // an interface type, but the actual type conversion is checked at run
13615 // time.
13616
13617 void
13618 Type_guard_expression::do_check_types(Gogo*)
13619 {
13620   // 6g permits using a type guard with unsafe.pointer; we are
13621   // compatible.
13622   Type* expr_type = this->expr_->type();
13623   if (expr_type->is_unsafe_pointer_type())
13624     {
13625       if (this->type_->points_to() == NULL
13626           && (this->type_->integer_type() == NULL
13627               || (this->type_->forwarded()
13628                   != Type::lookup_integer_type("uintptr"))))
13629         this->report_error(_("invalid unsafe.Pointer conversion"));
13630     }
13631   else if (this->type_->is_unsafe_pointer_type())
13632     {
13633       if (expr_type->points_to() == NULL
13634           && (expr_type->integer_type() == NULL
13635               || (expr_type->forwarded()
13636                   != Type::lookup_integer_type("uintptr"))))
13637         this->report_error(_("invalid unsafe.Pointer conversion"));
13638     }
13639   else if (expr_type->interface_type() == NULL)
13640     {
13641       if (!expr_type->is_error() && !this->type_->is_error())
13642         this->report_error(_("type assertion only valid for interface types"));
13643       this->set_is_error();
13644     }
13645   else if (this->type_->interface_type() == NULL)
13646     {
13647       std::string reason;
13648       if (!expr_type->interface_type()->implements_interface(this->type_,
13649                                                              &reason))
13650         {
13651           if (!this->type_->is_error())
13652             {
13653               if (reason.empty())
13654                 this->report_error(_("impossible type assertion: "
13655                                      "type does not implement interface"));
13656               else
13657                 error_at(this->location(),
13658                          ("impossible type assertion: "
13659                           "type does not implement interface (%s)"),
13660                          reason.c_str());
13661             }
13662           this->set_is_error();
13663         }
13664     }
13665 }
13666
13667 // Return a tree for a type guard expression.
13668
13669 tree
13670 Type_guard_expression::do_get_tree(Translate_context* context)
13671 {
13672   Gogo* gogo = context->gogo();
13673   tree expr_tree = this->expr_->get_tree(context);
13674   if (expr_tree == error_mark_node)
13675     return error_mark_node;
13676   Type* expr_type = this->expr_->type();
13677   if ((this->type_->is_unsafe_pointer_type()
13678        && (expr_type->points_to() != NULL
13679            || expr_type->integer_type() != NULL))
13680       || (expr_type->is_unsafe_pointer_type()
13681           && this->type_->points_to() != NULL))
13682     return convert_to_pointer(type_to_tree(this->type_->get_backend(gogo)),
13683                               expr_tree);
13684   else if (expr_type->is_unsafe_pointer_type()
13685            && this->type_->integer_type() != NULL)
13686     return convert_to_integer(type_to_tree(this->type_->get_backend(gogo)),
13687                               expr_tree);
13688   else if (this->type_->interface_type() != NULL)
13689     return Expression::convert_interface_to_interface(context, this->type_,
13690                                                       this->expr_->type(),
13691                                                       expr_tree, true,
13692                                                       this->location());
13693   else
13694     return Expression::convert_for_assignment(context, this->type_,
13695                                               this->expr_->type(), expr_tree,
13696                                               this->location());
13697 }
13698
13699 // Dump ast representation for a type guard expression.
13700
13701 void
13702 Type_guard_expression::do_dump_expression(Ast_dump_context* ast_dump_context)
13703     const
13704 {
13705   this->expr_->dump_expression(ast_dump_context);
13706   ast_dump_context->ostream() <<  ".";
13707   ast_dump_context->dump_type(this->type_);
13708 }
13709
13710 // Make a type guard expression.
13711
13712 Expression*
13713 Expression::make_type_guard(Expression* expr, Type* type,
13714                             Location location)
13715 {
13716   return new Type_guard_expression(expr, type, location);
13717 }
13718
13719 // Class Heap_composite_expression.
13720
13721 // When you take the address of a composite literal, it is allocated
13722 // on the heap.  This class implements that.
13723
13724 class Heap_composite_expression : public Expression
13725 {
13726  public:
13727   Heap_composite_expression(Expression* expr, Location location)
13728     : Expression(EXPRESSION_HEAP_COMPOSITE, location),
13729       expr_(expr)
13730   { }
13731
13732  protected:
13733   int
13734   do_traverse(Traverse* traverse)
13735   { return Expression::traverse(&this->expr_, traverse); }
13736
13737   Type*
13738   do_type()
13739   { return Type::make_pointer_type(this->expr_->type()); }
13740
13741   void
13742   do_determine_type(const Type_context*)
13743   { this->expr_->determine_type_no_context(); }
13744
13745   Expression*
13746   do_copy()
13747   {
13748     return Expression::make_heap_composite(this->expr_->copy(),
13749                                            this->location());
13750   }
13751
13752   tree
13753   do_get_tree(Translate_context*);
13754
13755   // We only export global objects, and the parser does not generate
13756   // this in global scope.
13757   void
13758   do_export(Export*) const
13759   { go_unreachable(); }
13760
13761   void
13762   do_dump_expression(Ast_dump_context*) const;
13763
13764  private:
13765   // The composite literal which is being put on the heap.
13766   Expression* expr_;
13767 };
13768
13769 // Return a tree which allocates a composite literal on the heap.
13770
13771 tree
13772 Heap_composite_expression::do_get_tree(Translate_context* context)
13773 {
13774   tree expr_tree = this->expr_->get_tree(context);
13775   if (expr_tree == error_mark_node)
13776     return error_mark_node;
13777   tree expr_size = TYPE_SIZE_UNIT(TREE_TYPE(expr_tree));
13778   go_assert(TREE_CODE(expr_size) == INTEGER_CST);
13779   tree space = context->gogo()->allocate_memory(this->expr_->type(),
13780                                                 expr_size, this->location());
13781   space = fold_convert(build_pointer_type(TREE_TYPE(expr_tree)), space);
13782   space = save_expr(space);
13783   tree ref = build_fold_indirect_ref_loc(this->location().gcc_location(),
13784                                          space);
13785   TREE_THIS_NOTRAP(ref) = 1;
13786   tree ret = build2(COMPOUND_EXPR, TREE_TYPE(space),
13787                     build2(MODIFY_EXPR, void_type_node, ref, expr_tree),
13788                     space);
13789   SET_EXPR_LOCATION(ret, this->location().gcc_location());
13790   return ret;
13791 }
13792
13793 // Dump ast representation for a heap composite expression.
13794
13795 void
13796 Heap_composite_expression::do_dump_expression(
13797     Ast_dump_context* ast_dump_context) const
13798 {
13799   ast_dump_context->ostream() << "&(";
13800   ast_dump_context->dump_expression(this->expr_);
13801   ast_dump_context->ostream() << ")";
13802 }
13803
13804 // Allocate a composite literal on the heap.
13805
13806 Expression*
13807 Expression::make_heap_composite(Expression* expr, Location location)
13808 {
13809   return new Heap_composite_expression(expr, location);
13810 }
13811
13812 // Class Receive_expression.
13813
13814 // Return the type of a receive expression.
13815
13816 Type*
13817 Receive_expression::do_type()
13818 {
13819   Channel_type* channel_type = this->channel_->type()->channel_type();
13820   if (channel_type == NULL)
13821     return Type::make_error_type();
13822   return channel_type->element_type();
13823 }
13824
13825 // Check types for a receive expression.
13826
13827 void
13828 Receive_expression::do_check_types(Gogo*)
13829 {
13830   Type* type = this->channel_->type();
13831   if (type->is_error())
13832     {
13833       this->set_is_error();
13834       return;
13835     }
13836   if (type->channel_type() == NULL)
13837     {
13838       this->report_error(_("expected channel"));
13839       return;
13840     }
13841   if (!type->channel_type()->may_receive())
13842     {
13843       this->report_error(_("invalid receive on send-only channel"));
13844       return;
13845     }
13846 }
13847
13848 // Get a tree for a receive expression.
13849
13850 tree
13851 Receive_expression::do_get_tree(Translate_context* context)
13852 {
13853   Location loc = this->location();
13854
13855   Channel_type* channel_type = this->channel_->type()->channel_type();
13856   if (channel_type == NULL)
13857     {
13858       go_assert(this->channel_->type()->is_error());
13859       return error_mark_node;
13860     }
13861
13862   Expression* td = Expression::make_type_descriptor(channel_type, loc);
13863   tree td_tree = td->get_tree(context);
13864
13865   Type* element_type = channel_type->element_type();
13866   Btype* element_type_btype = element_type->get_backend(context->gogo());
13867   tree element_type_tree = type_to_tree(element_type_btype);
13868
13869   tree channel = this->channel_->get_tree(context);
13870   if (element_type_tree == error_mark_node || channel == error_mark_node)
13871     return error_mark_node;
13872
13873   return Gogo::receive_from_channel(element_type_tree, td_tree, channel, loc);
13874 }
13875
13876 // Dump ast representation for a receive expression.
13877
13878 void
13879 Receive_expression::do_dump_expression(Ast_dump_context* ast_dump_context) const
13880 {
13881   ast_dump_context->ostream() << " <- " ;
13882   ast_dump_context->dump_expression(channel_);
13883 }
13884
13885 // Make a receive expression.
13886
13887 Receive_expression*
13888 Expression::make_receive(Expression* channel, Location location)
13889 {
13890   return new Receive_expression(channel, location);
13891 }
13892
13893 // An expression which evaluates to a pointer to the type descriptor
13894 // of a type.
13895
13896 class Type_descriptor_expression : public Expression
13897 {
13898  public:
13899   Type_descriptor_expression(Type* type, Location location)
13900     : Expression(EXPRESSION_TYPE_DESCRIPTOR, location),
13901       type_(type)
13902   { }
13903
13904  protected:
13905   Type*
13906   do_type()
13907   { return Type::make_type_descriptor_ptr_type(); }
13908
13909   void
13910   do_determine_type(const Type_context*)
13911   { }
13912
13913   Expression*
13914   do_copy()
13915   { return this; }
13916
13917   tree
13918   do_get_tree(Translate_context* context)
13919   {
13920     return this->type_->type_descriptor_pointer(context->gogo(),
13921                                                 this->location());
13922   }
13923
13924   void
13925   do_dump_expression(Ast_dump_context*) const;
13926
13927  private:
13928   // The type for which this is the descriptor.
13929   Type* type_;
13930 };
13931
13932 // Dump ast representation for a type descriptor expression.
13933
13934 void
13935 Type_descriptor_expression::do_dump_expression(
13936     Ast_dump_context* ast_dump_context) const
13937 {
13938   ast_dump_context->dump_type(this->type_);
13939 }
13940
13941 // Make a type descriptor expression.
13942
13943 Expression*
13944 Expression::make_type_descriptor(Type* type, Location location)
13945 {
13946   return new Type_descriptor_expression(type, location);
13947 }
13948
13949 // An expression which evaluates to some characteristic of a type.
13950 // This is only used to initialize fields of a type descriptor.  Using
13951 // a new expression class is slightly inefficient but gives us a good
13952 // separation between the frontend and the middle-end with regard to
13953 // how types are laid out.
13954
13955 class Type_info_expression : public Expression
13956 {
13957  public:
13958   Type_info_expression(Type* type, Type_info type_info)
13959     : Expression(EXPRESSION_TYPE_INFO, Linemap::predeclared_location()),
13960       type_(type), type_info_(type_info)
13961   { }
13962
13963  protected:
13964   Type*
13965   do_type();
13966
13967   void
13968   do_determine_type(const Type_context*)
13969   { }
13970
13971   Expression*
13972   do_copy()
13973   { return this; }
13974
13975   tree
13976   do_get_tree(Translate_context* context);
13977
13978   void
13979   do_dump_expression(Ast_dump_context*) const;
13980
13981  private:
13982   // The type for which we are getting information.
13983   Type* type_;
13984   // What information we want.
13985   Type_info type_info_;
13986 };
13987
13988 // The type is chosen to match what the type descriptor struct
13989 // expects.
13990
13991 Type*
13992 Type_info_expression::do_type()
13993 {
13994   switch (this->type_info_)
13995     {
13996     case TYPE_INFO_SIZE:
13997       return Type::lookup_integer_type("uintptr");
13998     case TYPE_INFO_ALIGNMENT:
13999     case TYPE_INFO_FIELD_ALIGNMENT:
14000       return Type::lookup_integer_type("uint8");
14001     default:
14002       go_unreachable();
14003     }
14004 }
14005
14006 // Return type information in GENERIC.
14007
14008 tree
14009 Type_info_expression::do_get_tree(Translate_context* context)
14010 {
14011   Btype* btype = this->type_->get_backend(context->gogo());
14012   Gogo* gogo = context->gogo();
14013   size_t val;
14014   switch (this->type_info_)
14015     {
14016     case TYPE_INFO_SIZE:
14017       val = gogo->backend()->type_size(btype);
14018       break;
14019     case TYPE_INFO_ALIGNMENT:
14020       val = gogo->backend()->type_alignment(btype);
14021       break;
14022     case TYPE_INFO_FIELD_ALIGNMENT:
14023       val = gogo->backend()->type_field_alignment(btype);
14024       break;
14025     default:
14026       go_unreachable();
14027     }
14028   tree val_type_tree = type_to_tree(this->type()->get_backend(gogo));
14029   go_assert(val_type_tree != error_mark_node);
14030   return build_int_cstu(val_type_tree, val);
14031 }
14032
14033 // Dump ast representation for a type info expression.
14034
14035 void
14036 Type_info_expression::do_dump_expression(
14037     Ast_dump_context* ast_dump_context) const
14038 {
14039   ast_dump_context->ostream() << "typeinfo(";
14040   ast_dump_context->dump_type(this->type_);
14041   ast_dump_context->ostream() << ",";
14042   ast_dump_context->ostream() <<
14043     (this->type_info_ == TYPE_INFO_ALIGNMENT ? "alignment"
14044     : this->type_info_ == TYPE_INFO_FIELD_ALIGNMENT ? "field alignment"
14045     : this->type_info_ == TYPE_INFO_SIZE ? "size "
14046     : "unknown");
14047   ast_dump_context->ostream() << ")";
14048 }
14049
14050 // Make a type info expression.
14051
14052 Expression*
14053 Expression::make_type_info(Type* type, Type_info type_info)
14054 {
14055   return new Type_info_expression(type, type_info);
14056 }
14057
14058 // An expression which evaluates to the offset of a field within a
14059 // struct.  This, like Type_info_expression, q.v., is only used to
14060 // initialize fields of a type descriptor.
14061
14062 class Struct_field_offset_expression : public Expression
14063 {
14064  public:
14065   Struct_field_offset_expression(Struct_type* type, const Struct_field* field)
14066     : Expression(EXPRESSION_STRUCT_FIELD_OFFSET,
14067                  Linemap::predeclared_location()),
14068       type_(type), field_(field)
14069   { }
14070
14071  protected:
14072   Type*
14073   do_type()
14074   { return Type::lookup_integer_type("uintptr"); }
14075
14076   void
14077   do_determine_type(const Type_context*)
14078   { }
14079
14080   Expression*
14081   do_copy()
14082   { return this; }
14083
14084   tree
14085   do_get_tree(Translate_context* context);
14086
14087   void
14088   do_dump_expression(Ast_dump_context*) const;
14089
14090  private:
14091   // The type of the struct.
14092   Struct_type* type_;
14093   // The field.
14094   const Struct_field* field_;
14095 };
14096
14097 // Return a struct field offset in GENERIC.
14098
14099 tree
14100 Struct_field_offset_expression::do_get_tree(Translate_context* context)
14101 {
14102   tree type_tree = type_to_tree(this->type_->get_backend(context->gogo()));
14103   if (type_tree == error_mark_node)
14104     return error_mark_node;
14105
14106   tree val_type_tree = type_to_tree(this->type()->get_backend(context->gogo()));
14107   go_assert(val_type_tree != error_mark_node);
14108
14109   const Struct_field_list* fields = this->type_->fields();
14110   tree struct_field_tree = TYPE_FIELDS(type_tree);
14111   Struct_field_list::const_iterator p;
14112   for (p = fields->begin();
14113        p != fields->end();
14114        ++p, struct_field_tree = DECL_CHAIN(struct_field_tree))
14115     {
14116       go_assert(struct_field_tree != NULL_TREE);
14117       if (&*p == this->field_)
14118         break;
14119     }
14120   go_assert(&*p == this->field_);
14121
14122   return fold_convert_loc(BUILTINS_LOCATION, val_type_tree,
14123                           byte_position(struct_field_tree));
14124 }
14125
14126 // Dump ast representation for a struct field offset expression.
14127
14128 void
14129 Struct_field_offset_expression::do_dump_expression(
14130     Ast_dump_context* ast_dump_context) const
14131 {
14132   ast_dump_context->ostream() <<  "unsafe.Offsetof(";
14133   ast_dump_context->dump_type(this->type_);
14134   ast_dump_context->ostream() << '.';
14135   ast_dump_context->ostream() <<
14136     Gogo::message_name(this->field_->field_name());
14137   ast_dump_context->ostream() << ")";
14138 }
14139
14140 // Make an expression for a struct field offset.
14141
14142 Expression*
14143 Expression::make_struct_field_offset(Struct_type* type,
14144                                      const Struct_field* field)
14145 {
14146   return new Struct_field_offset_expression(type, field);
14147 }
14148
14149 // An expression which evaluates to a pointer to the map descriptor of
14150 // a map type.
14151
14152 class Map_descriptor_expression : public Expression
14153 {
14154  public:
14155   Map_descriptor_expression(Map_type* type, Location location)
14156     : Expression(EXPRESSION_MAP_DESCRIPTOR, location),
14157       type_(type)
14158   { }
14159
14160  protected:
14161   Type*
14162   do_type()
14163   { return Type::make_pointer_type(Map_type::make_map_descriptor_type()); }
14164
14165   void
14166   do_determine_type(const Type_context*)
14167   { }
14168
14169   Expression*
14170   do_copy()
14171   { return this; }
14172
14173   tree
14174   do_get_tree(Translate_context* context)
14175   {
14176     return this->type_->map_descriptor_pointer(context->gogo(),
14177                                                this->location());
14178   }
14179
14180   void
14181   do_dump_expression(Ast_dump_context*) const;
14182
14183  private:
14184   // The type for which this is the descriptor.
14185   Map_type* type_;
14186 };
14187
14188 // Dump ast representation for a map descriptor expression.
14189
14190 void
14191 Map_descriptor_expression::do_dump_expression(
14192     Ast_dump_context* ast_dump_context) const
14193 {
14194   ast_dump_context->ostream() << "map_descriptor(";
14195   ast_dump_context->dump_type(this->type_);
14196   ast_dump_context->ostream() << ")";
14197 }
14198
14199 // Make a map descriptor expression.
14200
14201 Expression*
14202 Expression::make_map_descriptor(Map_type* type, Location location)
14203 {
14204   return new Map_descriptor_expression(type, location);
14205 }
14206
14207 // An expression which evaluates to the address of an unnamed label.
14208
14209 class Label_addr_expression : public Expression
14210 {
14211  public:
14212   Label_addr_expression(Label* label, Location location)
14213     : Expression(EXPRESSION_LABEL_ADDR, location),
14214       label_(label)
14215   { }
14216
14217  protected:
14218   Type*
14219   do_type()
14220   { return Type::make_pointer_type(Type::make_void_type()); }
14221
14222   void
14223   do_determine_type(const Type_context*)
14224   { }
14225
14226   Expression*
14227   do_copy()
14228   { return new Label_addr_expression(this->label_, this->location()); }
14229
14230   tree
14231   do_get_tree(Translate_context* context)
14232   {
14233     return expr_to_tree(this->label_->get_addr(context, this->location()));
14234   }
14235
14236   void
14237   do_dump_expression(Ast_dump_context* ast_dump_context) const
14238   { ast_dump_context->ostream() << this->label_->name(); }
14239
14240  private:
14241   // The label whose address we are taking.
14242   Label* label_;
14243 };
14244
14245 // Make an expression for the address of an unnamed label.
14246
14247 Expression*
14248 Expression::make_label_addr(Label* label, Location location)
14249 {
14250   return new Label_addr_expression(label, location);
14251 }
14252
14253 // Import an expression.  This comes at the end in order to see the
14254 // various class definitions.
14255
14256 Expression*
14257 Expression::import_expression(Import* imp)
14258 {
14259   int c = imp->peek_char();
14260   if (imp->match_c_string("- ")
14261       || imp->match_c_string("! ")
14262       || imp->match_c_string("^ "))
14263     return Unary_expression::do_import(imp);
14264   else if (c == '(')
14265     return Binary_expression::do_import(imp);
14266   else if (imp->match_c_string("true")
14267            || imp->match_c_string("false"))
14268     return Boolean_expression::do_import(imp);
14269   else if (c == '"')
14270     return String_expression::do_import(imp);
14271   else if (c == '-' || (c >= '0' && c <= '9'))
14272     {
14273       // This handles integers, floats and complex constants.
14274       return Integer_expression::do_import(imp);
14275     }
14276   else if (imp->match_c_string("nil"))
14277     return Nil_expression::do_import(imp);
14278   else if (imp->match_c_string("convert"))
14279     return Type_conversion_expression::do_import(imp);
14280   else
14281     {
14282       error_at(imp->location(), "import error: expected expression");
14283       return Expression::make_error(imp->location());
14284     }
14285 }
14286
14287 // Class Expression_list.
14288
14289 // Traverse the list.
14290
14291 int
14292 Expression_list::traverse(Traverse* traverse)
14293 {
14294   for (Expression_list::iterator p = this->begin();
14295        p != this->end();
14296        ++p)
14297     {
14298       if (*p != NULL)
14299         {
14300           if (Expression::traverse(&*p, traverse) == TRAVERSE_EXIT)
14301             return TRAVERSE_EXIT;
14302         }
14303     }
14304   return TRAVERSE_CONTINUE;
14305 }
14306
14307 // Copy the list.
14308
14309 Expression_list*
14310 Expression_list::copy()
14311 {
14312   Expression_list* ret = new Expression_list();
14313   for (Expression_list::iterator p = this->begin();
14314        p != this->end();
14315        ++p)
14316     {
14317       if (*p == NULL)
14318         ret->push_back(NULL);
14319       else
14320         ret->push_back((*p)->copy());
14321     }
14322   return ret;
14323 }
14324
14325 // Return whether an expression list has an error expression.
14326
14327 bool
14328 Expression_list::contains_error() const
14329 {
14330   for (Expression_list::const_iterator p = this->begin();
14331        p != this->end();
14332        ++p)
14333     if (*p != NULL && (*p)->is_error_expression())
14334       return true;
14335   return false;
14336 }