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   bool have_big_args = false;
7748   Type* uintptr_type = Type::lookup_integer_type("uintptr");
7749   int uintptr_bits = uintptr_type->integer_type()->bits();
7750
7751   ++parg;
7752   Expression* len_arg;
7753   if (parg == args->end())
7754     {
7755       if (is_slice)
7756         {
7757           this->report_error(_("length required when allocating a slice"));
7758           return Expression::make_error(this->location());
7759         }
7760
7761       mpz_t zval;
7762       mpz_init_set_ui(zval, 0);
7763       len_arg = Expression::make_integer(&zval, NULL, loc);
7764       mpz_clear(zval);
7765     }
7766   else
7767     {
7768       len_arg = *parg;
7769       if (!this->check_int_value(len_arg))
7770         {
7771           this->report_error(_("bad size for make"));
7772           return Expression::make_error(this->location());
7773         }
7774       if (len_arg->type()->integer_type() != NULL
7775           && len_arg->type()->integer_type()->bits() > uintptr_bits)
7776         have_big_args = true;
7777       ++parg;
7778     }
7779
7780   Expression* cap_arg = NULL;
7781   if (is_slice && parg != args->end())
7782     {
7783       cap_arg = *parg;
7784       if (!this->check_int_value(cap_arg))
7785         {
7786           this->report_error(_("bad capacity when making slice"));
7787           return Expression::make_error(this->location());
7788         }
7789       if (cap_arg->type()->integer_type() != NULL
7790           && cap_arg->type()->integer_type()->bits() > uintptr_bits)
7791         have_big_args = true;
7792       ++parg;
7793     }
7794
7795   if (parg != args->end())
7796     {
7797       this->report_error(_("too many arguments to make"));
7798       return Expression::make_error(this->location());
7799     }
7800
7801   Location type_loc = first_arg->location();
7802   Expression* type_arg;
7803   if (is_slice || is_chan)
7804     type_arg = Expression::make_type_descriptor(type, type_loc);
7805   else if (is_map)
7806     type_arg = Expression::make_map_descriptor(type->map_type(), type_loc);
7807   else
7808     go_unreachable();
7809
7810   Expression* call;
7811   if (is_slice)
7812     {
7813       if (cap_arg == NULL)
7814         call = Runtime::make_call((have_big_args
7815                                    ? Runtime::MAKESLICE1BIG
7816                                    : Runtime::MAKESLICE1),
7817                                   loc, 2, type_arg, len_arg);
7818       else
7819         call = Runtime::make_call((have_big_args
7820                                    ? Runtime::MAKESLICE2BIG
7821                                    : Runtime::MAKESLICE2),
7822                                   loc, 3, type_arg, len_arg, cap_arg);
7823     }
7824   else if (is_map)
7825     call = Runtime::make_call((have_big_args
7826                                ? Runtime::MAKEMAPBIG
7827                                : Runtime::MAKEMAP),
7828                               loc, 2, type_arg, len_arg);
7829   else if (is_chan)
7830     call = Runtime::make_call((have_big_args
7831                                ? Runtime::MAKECHANBIG
7832                                : Runtime::MAKECHAN),
7833                               loc, 2, type_arg, len_arg);
7834   else
7835     go_unreachable();
7836
7837   return Expression::make_unsafe_cast(type, call, loc);
7838 }
7839
7840 // Return whether an expression has an integer value.  Report an error
7841 // if not.  This is used when handling calls to the predeclared make
7842 // function.
7843
7844 bool
7845 Builtin_call_expression::check_int_value(Expression* e)
7846 {
7847   if (e->type()->integer_type() != NULL)
7848     return true;
7849
7850   // Check for a floating point constant with integer value.
7851   mpfr_t fval;
7852   mpfr_init(fval);
7853
7854   Type* dummy;
7855   if (e->float_constant_value(fval, &dummy) && mpfr_integer_p(fval))
7856     {
7857       mpz_t ival;
7858       mpz_init(ival);
7859
7860       bool ok = false;
7861
7862       mpfr_clear_overflow();
7863       mpfr_clear_erangeflag();
7864       mpfr_get_z(ival, fval, GMP_RNDN);
7865       if (!mpfr_overflow_p()
7866           && !mpfr_erangeflag_p()
7867           && mpz_sgn(ival) >= 0)
7868         {
7869           Named_type* ntype = Type::lookup_integer_type("int");
7870           Integer_type* inttype = ntype->integer_type();
7871           mpz_t max;
7872           mpz_init_set_ui(max, 1);
7873           mpz_mul_2exp(max, max, inttype->bits() - 1);
7874           ok = mpz_cmp(ival, max) < 0;
7875           mpz_clear(max);
7876         }
7877       mpz_clear(ival);
7878
7879       if (ok)
7880         {
7881           mpfr_clear(fval);
7882           return true;
7883         }
7884     }
7885
7886   mpfr_clear(fval);
7887
7888   return false;
7889 }
7890
7891 // Return the type of the real or imag functions, given the type of
7892 // the argument.  We need to map complex to float, complex64 to
7893 // float32, and complex128 to float64, so it has to be done by name.
7894 // This returns NULL if it can't figure out the type.
7895
7896 Type*
7897 Builtin_call_expression::real_imag_type(Type* arg_type)
7898 {
7899   if (arg_type == NULL || arg_type->is_abstract())
7900     return NULL;
7901   Named_type* nt = arg_type->named_type();
7902   if (nt == NULL)
7903     return NULL;
7904   while (nt->real_type()->named_type() != NULL)
7905     nt = nt->real_type()->named_type();
7906   if (nt->name() == "complex64")
7907     return Type::lookup_float_type("float32");
7908   else if (nt->name() == "complex128")
7909     return Type::lookup_float_type("float64");
7910   else
7911     return NULL;
7912 }
7913
7914 // Return the type of the complex function, given the type of one of the
7915 // argments.  Like real_imag_type, we have to map by name.
7916
7917 Type*
7918 Builtin_call_expression::complex_type(Type* arg_type)
7919 {
7920   if (arg_type == NULL || arg_type->is_abstract())
7921     return NULL;
7922   Named_type* nt = arg_type->named_type();
7923   if (nt == NULL)
7924     return NULL;
7925   while (nt->real_type()->named_type() != NULL)
7926     nt = nt->real_type()->named_type();
7927   if (nt->name() == "float32")
7928     return Type::lookup_complex_type("complex64");
7929   else if (nt->name() == "float64")
7930     return Type::lookup_complex_type("complex128");
7931   else
7932     return NULL;
7933 }
7934
7935 // Return a single argument, or NULL if there isn't one.
7936
7937 Expression*
7938 Builtin_call_expression::one_arg() const
7939 {
7940   const Expression_list* args = this->args();
7941   if (args->size() != 1)
7942     return NULL;
7943   return args->front();
7944 }
7945
7946 // Return whether this is constant: len of a string, or len or cap of
7947 // a fixed array, or unsafe.Sizeof, unsafe.Offsetof, unsafe.Alignof.
7948
7949 bool
7950 Builtin_call_expression::do_is_constant() const
7951 {
7952   switch (this->code_)
7953     {
7954     case BUILTIN_LEN:
7955     case BUILTIN_CAP:
7956       {
7957         if (this->seen_)
7958           return false;
7959
7960         Expression* arg = this->one_arg();
7961         if (arg == NULL)
7962           return false;
7963         Type* arg_type = arg->type();
7964
7965         if (arg_type->points_to() != NULL
7966             && arg_type->points_to()->array_type() != NULL
7967             && !arg_type->points_to()->is_slice_type())
7968           arg_type = arg_type->points_to();
7969
7970         if (arg_type->array_type() != NULL
7971             && arg_type->array_type()->length() != NULL)
7972           return true;
7973
7974         if (this->code_ == BUILTIN_LEN && arg_type->is_string_type())
7975           {
7976             this->seen_ = true;
7977             bool ret = arg->is_constant();
7978             this->seen_ = false;
7979             return ret;
7980           }
7981       }
7982       break;
7983
7984     case BUILTIN_SIZEOF:
7985     case BUILTIN_ALIGNOF:
7986       return this->one_arg() != NULL;
7987
7988     case BUILTIN_OFFSETOF:
7989       {
7990         Expression* arg = this->one_arg();
7991         if (arg == NULL)
7992           return false;
7993         return arg->field_reference_expression() != NULL;
7994       }
7995
7996     case BUILTIN_COMPLEX:
7997       {
7998         const Expression_list* args = this->args();
7999         if (args != NULL && args->size() == 2)
8000           return args->front()->is_constant() && args->back()->is_constant();
8001       }
8002       break;
8003
8004     case BUILTIN_REAL:
8005     case BUILTIN_IMAG:
8006       {
8007         Expression* arg = this->one_arg();
8008         return arg != NULL && arg->is_constant();
8009       }
8010
8011     default:
8012       break;
8013     }
8014
8015   return false;
8016 }
8017
8018 // Return an integer constant value if possible.
8019
8020 bool
8021 Builtin_call_expression::do_integer_constant_value(bool iota_is_constant,
8022                                                    mpz_t val,
8023                                                    Type** ptype) const
8024 {
8025   if (this->code_ == BUILTIN_LEN
8026       || this->code_ == BUILTIN_CAP)
8027     {
8028       Expression* arg = this->one_arg();
8029       if (arg == NULL)
8030         return false;
8031       Type* arg_type = arg->type();
8032
8033       if (this->code_ == BUILTIN_LEN && arg_type->is_string_type())
8034         {
8035           std::string sval;
8036           if (arg->string_constant_value(&sval))
8037             {
8038               mpz_set_ui(val, sval.length());
8039               *ptype = Type::lookup_integer_type("int");
8040               return true;
8041             }
8042         }
8043
8044       if (arg_type->points_to() != NULL
8045           && arg_type->points_to()->array_type() != NULL
8046           && !arg_type->points_to()->is_slice_type())
8047         arg_type = arg_type->points_to();
8048
8049       if (arg_type->array_type() != NULL
8050           && arg_type->array_type()->length() != NULL)
8051         {
8052           if (this->seen_)
8053             return false;
8054           Expression* e = arg_type->array_type()->length();
8055           this->seen_ = true;
8056           bool r = e->integer_constant_value(iota_is_constant, val, ptype);
8057           this->seen_ = false;
8058           if (r)
8059             {
8060               *ptype = Type::lookup_integer_type("int");
8061               return true;
8062             }
8063         }
8064     }
8065   else if (this->code_ == BUILTIN_SIZEOF
8066            || this->code_ == BUILTIN_ALIGNOF)
8067     {
8068       Expression* arg = this->one_arg();
8069       if (arg == NULL)
8070         return false;
8071       Type* arg_type = arg->type();
8072       if (arg_type->is_error())
8073         return false;
8074       if (arg_type->is_abstract())
8075         return false;
8076       if (arg_type->named_type() != NULL)
8077         arg_type->named_type()->convert(this->gogo_);
8078
8079       unsigned int ret;
8080       if (this->code_ == BUILTIN_SIZEOF)
8081         {
8082           if (!arg_type->backend_type_size(this->gogo_, &ret))
8083             return false;
8084         }
8085       else if (this->code_ == BUILTIN_ALIGNOF)
8086         {
8087           if (arg->field_reference_expression() == NULL)
8088             {
8089               if (!arg_type->backend_type_align(this->gogo_, &ret))
8090                 return false;
8091             }
8092           else
8093             {
8094               // Calling unsafe.Alignof(s.f) returns the alignment of
8095               // the type of f when it is used as a field in a struct.
8096               if (!arg_type->backend_type_field_align(this->gogo_, &ret))
8097                 return false;
8098             }
8099         }
8100       else
8101         go_unreachable();
8102
8103       mpz_set_ui(val, ret);
8104       *ptype = NULL;
8105       return true;
8106     }
8107   else if (this->code_ == BUILTIN_OFFSETOF)
8108     {
8109       Expression* arg = this->one_arg();
8110       if (arg == NULL)
8111         return false;
8112       Field_reference_expression* farg = arg->field_reference_expression();
8113       if (farg == NULL)
8114         return false;
8115       Expression* struct_expr = farg->expr();
8116       Type* st = struct_expr->type();
8117       if (st->struct_type() == NULL)
8118         return false;
8119       if (st->named_type() != NULL)
8120         st->named_type()->convert(this->gogo_);
8121       unsigned int offset;
8122       if (!st->struct_type()->backend_field_offset(this->gogo_,
8123                                                    farg->field_index(),
8124                                                    &offset))
8125         return false;
8126       mpz_set_ui(val, offset);
8127       return true;
8128     }
8129   return false;
8130 }
8131
8132 // Return a floating point constant value if possible.
8133
8134 bool
8135 Builtin_call_expression::do_float_constant_value(mpfr_t val,
8136                                                  Type** ptype) const
8137 {
8138   if (this->code_ == BUILTIN_REAL || this->code_ == BUILTIN_IMAG)
8139     {
8140       Expression* arg = this->one_arg();
8141       if (arg == NULL)
8142         return false;
8143
8144       mpfr_t real;
8145       mpfr_t imag;
8146       mpfr_init(real);
8147       mpfr_init(imag);
8148
8149       bool ret = false;
8150       Type* type;
8151       if (arg->complex_constant_value(real, imag, &type))
8152         {
8153           if (this->code_ == BUILTIN_REAL)
8154             mpfr_set(val, real, GMP_RNDN);
8155           else
8156             mpfr_set(val, imag, GMP_RNDN);
8157           *ptype = Builtin_call_expression::real_imag_type(type);
8158           ret = true;
8159         }
8160
8161       mpfr_clear(real);
8162       mpfr_clear(imag);
8163       return ret;
8164     }
8165
8166   return false;
8167 }
8168
8169 // Return a complex constant value if possible.
8170
8171 bool
8172 Builtin_call_expression::do_complex_constant_value(mpfr_t real, mpfr_t imag,
8173                                                    Type** ptype) const
8174 {
8175   if (this->code_ == BUILTIN_COMPLEX)
8176     {
8177       const Expression_list* args = this->args();
8178       if (args == NULL || args->size() != 2)
8179         return false;
8180
8181       mpfr_t r;
8182       mpfr_init(r);
8183       Type* rtype;
8184       if (!args->front()->float_constant_value(r, &rtype))
8185         {
8186           mpfr_clear(r);
8187           return false;
8188         }
8189
8190       mpfr_t i;
8191       mpfr_init(i);
8192
8193       bool ret = false;
8194       Type* itype;
8195       if (args->back()->float_constant_value(i, &itype)
8196           && Type::are_identical(rtype, itype, false, NULL))
8197         {
8198           mpfr_set(real, r, GMP_RNDN);
8199           mpfr_set(imag, i, GMP_RNDN);
8200           *ptype = Builtin_call_expression::complex_type(rtype);
8201           ret = true;
8202         }
8203
8204       mpfr_clear(r);
8205       mpfr_clear(i);
8206
8207       return ret;
8208     }
8209
8210   return false;
8211 }
8212
8213 // Give an error if we are discarding the value of an expression which
8214 // should not normally be discarded.  We don't give an error for
8215 // discarding the value of an ordinary function call, but we do for
8216 // builtin functions, purely for consistency with the gc compiler.
8217
8218 void
8219 Builtin_call_expression::do_discarding_value()
8220 {
8221   switch (this->code_)
8222     {
8223     case BUILTIN_INVALID:
8224     default:
8225       go_unreachable();
8226
8227     case BUILTIN_APPEND:
8228     case BUILTIN_CAP:
8229     case BUILTIN_COMPLEX:
8230     case BUILTIN_IMAG:
8231     case BUILTIN_LEN:
8232     case BUILTIN_MAKE:
8233     case BUILTIN_NEW:
8234     case BUILTIN_REAL:
8235     case BUILTIN_ALIGNOF:
8236     case BUILTIN_OFFSETOF:
8237     case BUILTIN_SIZEOF:
8238       this->unused_value_error();
8239       break;
8240
8241     case BUILTIN_CLOSE:
8242     case BUILTIN_COPY:
8243     case BUILTIN_DELETE:
8244     case BUILTIN_PANIC:
8245     case BUILTIN_PRINT:
8246     case BUILTIN_PRINTLN:
8247     case BUILTIN_RECOVER:
8248       break;
8249     }
8250 }
8251
8252 // Return the type.
8253
8254 Type*
8255 Builtin_call_expression::do_type()
8256 {
8257   switch (this->code_)
8258     {
8259     case BUILTIN_INVALID:
8260     default:
8261       go_unreachable();
8262
8263     case BUILTIN_NEW:
8264     case BUILTIN_MAKE:
8265       {
8266         const Expression_list* args = this->args();
8267         if (args == NULL || args->empty())
8268           return Type::make_error_type();
8269         return Type::make_pointer_type(args->front()->type());
8270       }
8271
8272     case BUILTIN_CAP:
8273     case BUILTIN_COPY:
8274     case BUILTIN_LEN:
8275     case BUILTIN_ALIGNOF:
8276     case BUILTIN_OFFSETOF:
8277     case BUILTIN_SIZEOF:
8278       return Type::lookup_integer_type("int");
8279
8280     case BUILTIN_CLOSE:
8281     case BUILTIN_DELETE:
8282     case BUILTIN_PANIC:
8283     case BUILTIN_PRINT:
8284     case BUILTIN_PRINTLN:
8285       return Type::make_void_type();
8286
8287     case BUILTIN_RECOVER:
8288       return Type::make_empty_interface_type(Linemap::predeclared_location());
8289
8290     case BUILTIN_APPEND:
8291       {
8292         const Expression_list* args = this->args();
8293         if (args == NULL || args->empty())
8294           return Type::make_error_type();
8295         return args->front()->type();
8296       }
8297
8298     case BUILTIN_REAL:
8299     case BUILTIN_IMAG:
8300       {
8301         Expression* arg = this->one_arg();
8302         if (arg == NULL)
8303           return Type::make_error_type();
8304         Type* t = arg->type();
8305         if (t->is_abstract())
8306           t = t->make_non_abstract_type();
8307         t = Builtin_call_expression::real_imag_type(t);
8308         if (t == NULL)
8309           t = Type::make_error_type();
8310         return t;
8311       }
8312
8313     case BUILTIN_COMPLEX:
8314       {
8315         const Expression_list* args = this->args();
8316         if (args == NULL || args->size() != 2)
8317           return Type::make_error_type();
8318         Type* t = args->front()->type();
8319         if (t->is_abstract())
8320           {
8321             t = args->back()->type();
8322             if (t->is_abstract())
8323               t = t->make_non_abstract_type();
8324           }
8325         t = Builtin_call_expression::complex_type(t);
8326         if (t == NULL)
8327           t = Type::make_error_type();
8328         return t;
8329       }
8330     }
8331 }
8332
8333 // Determine the type.
8334
8335 void
8336 Builtin_call_expression::do_determine_type(const Type_context* context)
8337 {
8338   if (!this->determining_types())
8339     return;
8340
8341   this->fn()->determine_type_no_context();
8342
8343   const Expression_list* args = this->args();
8344
8345   bool is_print;
8346   Type* arg_type = NULL;
8347   switch (this->code_)
8348     {
8349     case BUILTIN_PRINT:
8350     case BUILTIN_PRINTLN:
8351       // Do not force a large integer constant to "int".
8352       is_print = true;
8353       break;
8354
8355     case BUILTIN_REAL:
8356     case BUILTIN_IMAG:
8357       arg_type = Builtin_call_expression::complex_type(context->type);
8358       is_print = false;
8359       break;
8360
8361     case BUILTIN_COMPLEX:
8362       {
8363         // For the complex function the type of one operand can
8364         // determine the type of the other, as in a binary expression.
8365         arg_type = Builtin_call_expression::real_imag_type(context->type);
8366         if (args != NULL && args->size() == 2)
8367           {
8368             Type* t1 = args->front()->type();
8369             Type* t2 = args->front()->type();
8370             if (!t1->is_abstract())
8371               arg_type = t1;
8372             else if (!t2->is_abstract())
8373               arg_type = t2;
8374           }
8375         is_print = false;
8376       }
8377       break;
8378
8379     default:
8380       is_print = false;
8381       break;
8382     }
8383
8384   if (args != NULL)
8385     {
8386       for (Expression_list::const_iterator pa = args->begin();
8387            pa != args->end();
8388            ++pa)
8389         {
8390           Type_context subcontext;
8391           subcontext.type = arg_type;
8392
8393           if (is_print)
8394             {
8395               // We want to print large constants, we so can't just
8396               // use the appropriate nonabstract type.  Use uint64 for
8397               // an integer if we know it is nonnegative, otherwise
8398               // use int64 for a integer, otherwise use float64 for a
8399               // float or complex128 for a complex.
8400               Type* want_type = NULL;
8401               Type* atype = (*pa)->type();
8402               if (atype->is_abstract())
8403                 {
8404                   if (atype->integer_type() != NULL)
8405                     {
8406                       mpz_t val;
8407                       mpz_init(val);
8408                       Type* dummy;
8409                       if (this->integer_constant_value(true, val, &dummy)
8410                           && mpz_sgn(val) >= 0)
8411                         want_type = Type::lookup_integer_type("uint64");
8412                       else
8413                         want_type = Type::lookup_integer_type("int64");
8414                       mpz_clear(val);
8415                     }
8416                   else if (atype->float_type() != NULL)
8417                     want_type = Type::lookup_float_type("float64");
8418                   else if (atype->complex_type() != NULL)
8419                     want_type = Type::lookup_complex_type("complex128");
8420                   else if (atype->is_abstract_string_type())
8421                     want_type = Type::lookup_string_type();
8422                   else if (atype->is_abstract_boolean_type())
8423                     want_type = Type::lookup_bool_type();
8424                   else
8425                     go_unreachable();
8426                   subcontext.type = want_type;
8427                 }
8428             }
8429
8430           (*pa)->determine_type(&subcontext);
8431         }
8432     }
8433 }
8434
8435 // If there is exactly one argument, return true.  Otherwise give an
8436 // error message and return false.
8437
8438 bool
8439 Builtin_call_expression::check_one_arg()
8440 {
8441   const Expression_list* args = this->args();
8442   if (args == NULL || args->size() < 1)
8443     {
8444       this->report_error(_("not enough arguments"));
8445       return false;
8446     }
8447   else if (args->size() > 1)
8448     {
8449       this->report_error(_("too many arguments"));
8450       return false;
8451     }
8452   if (args->front()->is_error_expression()
8453       || args->front()->type()->is_error())
8454     {
8455       this->set_is_error();
8456       return false;
8457     }
8458   return true;
8459 }
8460
8461 // Check argument types for a builtin function.
8462
8463 void
8464 Builtin_call_expression::do_check_types(Gogo*)
8465 {
8466   switch (this->code_)
8467     {
8468     case BUILTIN_INVALID:
8469     case BUILTIN_NEW:
8470     case BUILTIN_MAKE:
8471       return;
8472
8473     case BUILTIN_LEN:
8474     case BUILTIN_CAP:
8475       {
8476         // The single argument may be either a string or an array or a
8477         // map or a channel, or a pointer to a closed array.
8478         if (this->check_one_arg())
8479           {
8480             Type* arg_type = this->one_arg()->type();
8481             if (arg_type->points_to() != NULL
8482                 && arg_type->points_to()->array_type() != NULL
8483                 && !arg_type->points_to()->is_slice_type())
8484               arg_type = arg_type->points_to();
8485             if (this->code_ == BUILTIN_CAP)
8486               {
8487                 if (!arg_type->is_error()
8488                     && arg_type->array_type() == NULL
8489                     && arg_type->channel_type() == NULL)
8490                   this->report_error(_("argument must be array or slice "
8491                                        "or channel"));
8492               }
8493             else
8494               {
8495                 if (!arg_type->is_error()
8496                     && !arg_type->is_string_type()
8497                     && arg_type->array_type() == NULL
8498                     && arg_type->map_type() == NULL
8499                     && arg_type->channel_type() == NULL)
8500                   this->report_error(_("argument must be string or "
8501                                        "array or slice or map or channel"));
8502               }
8503           }
8504       }
8505       break;
8506
8507     case BUILTIN_PRINT:
8508     case BUILTIN_PRINTLN:
8509       {
8510         const Expression_list* args = this->args();
8511         if (args == NULL)
8512           {
8513             if (this->code_ == BUILTIN_PRINT)
8514               warning_at(this->location(), 0,
8515                          "no arguments for builtin function %<%s%>",
8516                          (this->code_ == BUILTIN_PRINT
8517                           ? "print"
8518                           : "println"));
8519           }
8520         else
8521           {
8522             for (Expression_list::const_iterator p = args->begin();
8523                  p != args->end();
8524                  ++p)
8525               {
8526                 Type* type = (*p)->type();
8527                 if (type->is_error()
8528                     || type->is_string_type()
8529                     || type->integer_type() != NULL
8530                     || type->float_type() != NULL
8531                     || type->complex_type() != NULL
8532                     || type->is_boolean_type()
8533                     || type->points_to() != NULL
8534                     || type->interface_type() != NULL
8535                     || type->channel_type() != NULL
8536                     || type->map_type() != NULL
8537                     || type->function_type() != NULL
8538                     || type->is_slice_type())
8539                   ;
8540                 else if ((*p)->is_type_expression())
8541                   {
8542                     // If this is a type expression it's going to give
8543                     // an error anyhow, so we don't need one here.
8544                   }
8545                 else
8546                   this->report_error(_("unsupported argument type to "
8547                                        "builtin function"));
8548               }
8549           }
8550       }
8551       break;
8552
8553     case BUILTIN_CLOSE:
8554       if (this->check_one_arg())
8555         {
8556           if (this->one_arg()->type()->channel_type() == NULL)
8557             this->report_error(_("argument must be channel"));
8558           else if (!this->one_arg()->type()->channel_type()->may_send())
8559             this->report_error(_("cannot close receive-only channel"));
8560         }
8561       break;
8562
8563     case BUILTIN_PANIC:
8564     case BUILTIN_SIZEOF:
8565     case BUILTIN_ALIGNOF:
8566       this->check_one_arg();
8567       break;
8568
8569     case BUILTIN_RECOVER:
8570       if (this->args() != NULL && !this->args()->empty())
8571         this->report_error(_("too many arguments"));
8572       break;
8573
8574     case BUILTIN_OFFSETOF:
8575       if (this->check_one_arg())
8576         {
8577           Expression* arg = this->one_arg();
8578           if (arg->field_reference_expression() == NULL)
8579             this->report_error(_("argument must be a field reference"));
8580         }
8581       break;
8582
8583     case BUILTIN_COPY:
8584       {
8585         const Expression_list* args = this->args();
8586         if (args == NULL || args->size() < 2)
8587           {
8588             this->report_error(_("not enough arguments"));
8589             break;
8590           }
8591         else if (args->size() > 2)
8592           {
8593             this->report_error(_("too many arguments"));
8594             break;
8595           }
8596         Type* arg1_type = args->front()->type();
8597         Type* arg2_type = args->back()->type();
8598         if (arg1_type->is_error() || arg2_type->is_error())
8599           break;
8600
8601         Type* e1;
8602         if (arg1_type->is_slice_type())
8603           e1 = arg1_type->array_type()->element_type();
8604         else
8605           {
8606             this->report_error(_("left argument must be a slice"));
8607             break;
8608           }
8609
8610         if (arg2_type->is_slice_type())
8611           {
8612             Type* e2 = arg2_type->array_type()->element_type();
8613             if (!Type::are_identical(e1, e2, true, NULL))
8614               this->report_error(_("element types must be the same"));
8615           }
8616         else if (arg2_type->is_string_type())
8617           {
8618             if (e1->integer_type() == NULL || !e1->integer_type()->is_byte())
8619               this->report_error(_("first argument must be []byte"));
8620           }
8621         else
8622             this->report_error(_("second argument must be slice or string"));
8623       }
8624       break;
8625
8626     case BUILTIN_APPEND:
8627       {
8628         const Expression_list* args = this->args();
8629         if (args == NULL || args->size() < 2)
8630           {
8631             this->report_error(_("not enough arguments"));
8632             break;
8633           }
8634         if (args->size() > 2)
8635           {
8636             this->report_error(_("too many arguments"));
8637             break;
8638           }
8639
8640         // The language permits appending a string to a []byte, as a
8641         // special case.
8642         if (args->back()->type()->is_string_type())
8643           {
8644             const Array_type* at = args->front()->type()->array_type();
8645             const Type* e = at->element_type()->forwarded();
8646             if (e->integer_type() != NULL && e->integer_type()->is_byte())
8647               break;
8648           }
8649
8650         // The language says that the second argument must be
8651         // assignable to a slice of the element type of the first
8652         // argument.  We already know the first argument is a slice
8653         // type.
8654         Array_type* at = args->front()->type()->array_type();
8655         Type* arg2_type = Type::make_array_type(at->element_type(), NULL);
8656         std::string reason;
8657         if (!Type::are_assignable(arg2_type, args->back()->type(), &reason))
8658           {
8659             if (reason.empty())
8660               this->report_error(_("argument 2 has invalid type"));
8661             else
8662               {
8663                 error_at(this->location(), "argument 2 has invalid type (%s)",
8664                          reason.c_str());
8665                 this->set_is_error();
8666               }
8667           }
8668         break;
8669       }
8670
8671     case BUILTIN_REAL:
8672     case BUILTIN_IMAG:
8673       if (this->check_one_arg())
8674         {
8675           if (this->one_arg()->type()->complex_type() == NULL)
8676             this->report_error(_("argument must have complex type"));
8677         }
8678       break;
8679
8680     case BUILTIN_COMPLEX:
8681       {
8682         const Expression_list* args = this->args();
8683         if (args == NULL || args->size() < 2)
8684           this->report_error(_("not enough arguments"));
8685         else if (args->size() > 2)
8686           this->report_error(_("too many arguments"));
8687         else if (args->front()->is_error_expression()
8688                  || args->front()->type()->is_error()
8689                  || args->back()->is_error_expression()
8690                  || args->back()->type()->is_error())
8691           this->set_is_error();
8692         else if (!Type::are_identical(args->front()->type(),
8693                                       args->back()->type(), true, NULL))
8694           this->report_error(_("complex arguments must have identical types"));
8695         else if (args->front()->type()->float_type() == NULL)
8696           this->report_error(_("complex arguments must have "
8697                                "floating-point type"));
8698       }
8699       break;
8700
8701     default:
8702       go_unreachable();
8703     }
8704 }
8705
8706 // Return the tree for a builtin function.
8707
8708 tree
8709 Builtin_call_expression::do_get_tree(Translate_context* context)
8710 {
8711   Gogo* gogo = context->gogo();
8712   Location location = this->location();
8713   switch (this->code_)
8714     {
8715     case BUILTIN_INVALID:
8716     case BUILTIN_NEW:
8717     case BUILTIN_MAKE:
8718       go_unreachable();
8719
8720     case BUILTIN_LEN:
8721     case BUILTIN_CAP:
8722       {
8723         const Expression_list* args = this->args();
8724         go_assert(args != NULL && args->size() == 1);
8725         Expression* arg = *args->begin();
8726         Type* arg_type = arg->type();
8727
8728         if (this->seen_)
8729           {
8730             go_assert(saw_errors());
8731             return error_mark_node;
8732           }
8733         this->seen_ = true;
8734
8735         tree arg_tree = arg->get_tree(context);
8736
8737         this->seen_ = false;
8738
8739         if (arg_tree == error_mark_node)
8740           return error_mark_node;
8741
8742         if (arg_type->points_to() != NULL)
8743           {
8744             arg_type = arg_type->points_to();
8745             go_assert(arg_type->array_type() != NULL
8746                        && !arg_type->is_slice_type());
8747             go_assert(POINTER_TYPE_P(TREE_TYPE(arg_tree)));
8748             arg_tree = build_fold_indirect_ref(arg_tree);
8749           }
8750
8751         tree val_tree;
8752         if (this->code_ == BUILTIN_LEN)
8753           {
8754             if (arg_type->is_string_type())
8755               val_tree = String_type::length_tree(gogo, arg_tree);
8756             else if (arg_type->array_type() != NULL)
8757               {
8758                 if (this->seen_)
8759                   {
8760                     go_assert(saw_errors());
8761                     return error_mark_node;
8762                   }
8763                 this->seen_ = true;
8764                 val_tree = arg_type->array_type()->length_tree(gogo, arg_tree);
8765                 this->seen_ = false;
8766               }
8767             else if (arg_type->map_type() != NULL)
8768               {
8769                 tree arg_type_tree = type_to_tree(arg_type->get_backend(gogo));
8770                 static tree map_len_fndecl;
8771                 val_tree = Gogo::call_builtin(&map_len_fndecl,
8772                                               location,
8773                                               "__go_map_len",
8774                                               1,
8775                                               integer_type_node,
8776                                               arg_type_tree,
8777                                               arg_tree);
8778               }
8779             else if (arg_type->channel_type() != NULL)
8780               {
8781                 tree arg_type_tree = type_to_tree(arg_type->get_backend(gogo));
8782                 static tree chan_len_fndecl;
8783                 val_tree = Gogo::call_builtin(&chan_len_fndecl,
8784                                               location,
8785                                               "__go_chan_len",
8786                                               1,
8787                                               integer_type_node,
8788                                               arg_type_tree,
8789                                               arg_tree);
8790               }
8791             else
8792               go_unreachable();
8793           }
8794         else
8795           {
8796             if (arg_type->array_type() != NULL)
8797               {
8798                 if (this->seen_)
8799                   {
8800                     go_assert(saw_errors());
8801                     return error_mark_node;
8802                   }
8803                 this->seen_ = true;
8804                 val_tree = arg_type->array_type()->capacity_tree(gogo,
8805                                                                  arg_tree);
8806                 this->seen_ = false;
8807               }
8808             else if (arg_type->channel_type() != NULL)
8809               {
8810                 tree arg_type_tree = type_to_tree(arg_type->get_backend(gogo));
8811                 static tree chan_cap_fndecl;
8812                 val_tree = Gogo::call_builtin(&chan_cap_fndecl,
8813                                               location,
8814                                               "__go_chan_cap",
8815                                               1,
8816                                               integer_type_node,
8817                                               arg_type_tree,
8818                                               arg_tree);
8819               }
8820             else
8821               go_unreachable();
8822           }
8823
8824         if (val_tree == error_mark_node)
8825           return error_mark_node;
8826
8827         Type* int_type = Type::lookup_integer_type("int");
8828         tree type_tree = type_to_tree(int_type->get_backend(gogo));
8829         if (type_tree == TREE_TYPE(val_tree))
8830           return val_tree;
8831         else
8832           return fold(convert_to_integer(type_tree, val_tree));
8833       }
8834
8835     case BUILTIN_PRINT:
8836     case BUILTIN_PRINTLN:
8837       {
8838         const bool is_ln = this->code_ == BUILTIN_PRINTLN;
8839         tree stmt_list = NULL_TREE;
8840
8841         const Expression_list* call_args = this->args();
8842         if (call_args != NULL)
8843           {
8844             for (Expression_list::const_iterator p = call_args->begin();
8845                  p != call_args->end();
8846                  ++p)
8847               {
8848                 if (is_ln && p != call_args->begin())
8849                   {
8850                     static tree print_space_fndecl;
8851                     tree call = Gogo::call_builtin(&print_space_fndecl,
8852                                                    location,
8853                                                    "__go_print_space",
8854                                                    0,
8855                                                    void_type_node);
8856                     if (call == error_mark_node)
8857                       return error_mark_node;
8858                     append_to_statement_list(call, &stmt_list);
8859                   }
8860
8861                 Type* type = (*p)->type();
8862
8863                 tree arg = (*p)->get_tree(context);
8864                 if (arg == error_mark_node)
8865                   return error_mark_node;
8866
8867                 tree* pfndecl;
8868                 const char* fnname;
8869                 if (type->is_string_type())
8870                   {
8871                     static tree print_string_fndecl;
8872                     pfndecl = &print_string_fndecl;
8873                     fnname = "__go_print_string";
8874                   }
8875                 else if (type->integer_type() != NULL
8876                          && type->integer_type()->is_unsigned())
8877                   {
8878                     static tree print_uint64_fndecl;
8879                     pfndecl = &print_uint64_fndecl;
8880                     fnname = "__go_print_uint64";
8881                     Type* itype = Type::lookup_integer_type("uint64");
8882                     Btype* bitype = itype->get_backend(gogo);
8883                     arg = fold_convert_loc(location.gcc_location(),
8884                                            type_to_tree(bitype), arg);
8885                   }
8886                 else if (type->integer_type() != NULL)
8887                   {
8888                     static tree print_int64_fndecl;
8889                     pfndecl = &print_int64_fndecl;
8890                     fnname = "__go_print_int64";
8891                     Type* itype = Type::lookup_integer_type("int64");
8892                     Btype* bitype = itype->get_backend(gogo);
8893                     arg = fold_convert_loc(location.gcc_location(),
8894                                            type_to_tree(bitype), arg);
8895                   }
8896                 else if (type->float_type() != NULL)
8897                   {
8898                     static tree print_double_fndecl;
8899                     pfndecl = &print_double_fndecl;
8900                     fnname = "__go_print_double";
8901                     arg = fold_convert_loc(location.gcc_location(),
8902                                            double_type_node, arg);
8903                   }
8904                 else if (type->complex_type() != NULL)
8905                   {
8906                     static tree print_complex_fndecl;
8907                     pfndecl = &print_complex_fndecl;
8908                     fnname = "__go_print_complex";
8909                     arg = fold_convert_loc(location.gcc_location(),
8910                                            complex_double_type_node, arg);
8911                   }
8912                 else if (type->is_boolean_type())
8913                   {
8914                     static tree print_bool_fndecl;
8915                     pfndecl = &print_bool_fndecl;
8916                     fnname = "__go_print_bool";
8917                   }
8918                 else if (type->points_to() != NULL
8919                          || type->channel_type() != NULL
8920                          || type->map_type() != NULL
8921                          || type->function_type() != NULL)
8922                   {
8923                     static tree print_pointer_fndecl;
8924                     pfndecl = &print_pointer_fndecl;
8925                     fnname = "__go_print_pointer";
8926                     arg = fold_convert_loc(location.gcc_location(),
8927                                            ptr_type_node, arg);
8928                   }
8929                 else if (type->interface_type() != NULL)
8930                   {
8931                     if (type->interface_type()->is_empty())
8932                       {
8933                         static tree print_empty_interface_fndecl;
8934                         pfndecl = &print_empty_interface_fndecl;
8935                         fnname = "__go_print_empty_interface";
8936                       }
8937                     else
8938                       {
8939                         static tree print_interface_fndecl;
8940                         pfndecl = &print_interface_fndecl;
8941                         fnname = "__go_print_interface";
8942                       }
8943                   }
8944                 else if (type->is_slice_type())
8945                   {
8946                     static tree print_slice_fndecl;
8947                     pfndecl = &print_slice_fndecl;
8948                     fnname = "__go_print_slice";
8949                   }
8950                 else
8951                   go_unreachable();
8952
8953                 tree call = Gogo::call_builtin(pfndecl,
8954                                                location,
8955                                                fnname,
8956                                                1,
8957                                                void_type_node,
8958                                                TREE_TYPE(arg),
8959                                                arg);
8960                 if (call == error_mark_node)
8961                   return error_mark_node;
8962                 append_to_statement_list(call, &stmt_list);
8963               }
8964           }
8965
8966         if (is_ln)
8967           {
8968             static tree print_nl_fndecl;
8969             tree call = Gogo::call_builtin(&print_nl_fndecl,
8970                                            location,
8971                                            "__go_print_nl",
8972                                            0,
8973                                            void_type_node);
8974             if (call == error_mark_node)
8975               return error_mark_node;
8976             append_to_statement_list(call, &stmt_list);
8977           }
8978
8979         return stmt_list;
8980       }
8981
8982     case BUILTIN_PANIC:
8983       {
8984         const Expression_list* args = this->args();
8985         go_assert(args != NULL && args->size() == 1);
8986         Expression* arg = args->front();
8987         tree arg_tree = arg->get_tree(context);
8988         if (arg_tree == error_mark_node)
8989           return error_mark_node;
8990         Type *empty =
8991           Type::make_empty_interface_type(Linemap::predeclared_location());
8992         arg_tree = Expression::convert_for_assignment(context, empty,
8993                                                       arg->type(),
8994                                                       arg_tree, location);
8995         static tree panic_fndecl;
8996         tree call = Gogo::call_builtin(&panic_fndecl,
8997                                        location,
8998                                        "__go_panic",
8999                                        1,
9000                                        void_type_node,
9001                                        TREE_TYPE(arg_tree),
9002                                        arg_tree);
9003         if (call == error_mark_node)
9004           return error_mark_node;
9005         // This function will throw an exception.
9006         TREE_NOTHROW(panic_fndecl) = 0;
9007         // This function will not return.
9008         TREE_THIS_VOLATILE(panic_fndecl) = 1;
9009         return call;
9010       }
9011
9012     case BUILTIN_RECOVER:
9013       {
9014         // The argument is set when building recover thunks.  It's a
9015         // boolean value which is true if we can recover a value now.
9016         const Expression_list* args = this->args();
9017         go_assert(args != NULL && args->size() == 1);
9018         Expression* arg = args->front();
9019         tree arg_tree = arg->get_tree(context);
9020         if (arg_tree == error_mark_node)
9021           return error_mark_node;
9022
9023         Type *empty =
9024           Type::make_empty_interface_type(Linemap::predeclared_location());
9025         tree empty_tree = type_to_tree(empty->get_backend(context->gogo()));
9026
9027         Type* nil_type = Type::make_nil_type();
9028         Expression* nil = Expression::make_nil(location);
9029         tree nil_tree = nil->get_tree(context);
9030         tree empty_nil_tree = Expression::convert_for_assignment(context,
9031                                                                  empty,
9032                                                                  nil_type,
9033                                                                  nil_tree,
9034                                                                  location);
9035
9036         // We need to handle a deferred call to recover specially,
9037         // because it changes whether it can recover a panic or not.
9038         // See test7 in test/recover1.go.
9039         tree call;
9040         if (this->is_deferred())
9041           {
9042             static tree deferred_recover_fndecl;
9043             call = Gogo::call_builtin(&deferred_recover_fndecl,
9044                                       location,
9045                                       "__go_deferred_recover",
9046                                       0,
9047                                       empty_tree);
9048           }
9049         else
9050           {
9051             static tree recover_fndecl;
9052             call = Gogo::call_builtin(&recover_fndecl,
9053                                       location,
9054                                       "__go_recover",
9055                                       0,
9056                                       empty_tree);
9057           }
9058         if (call == error_mark_node)
9059           return error_mark_node;
9060         return fold_build3_loc(location.gcc_location(), COND_EXPR, empty_tree,
9061                                arg_tree, call, empty_nil_tree);
9062       }
9063
9064     case BUILTIN_CLOSE:
9065       {
9066         const Expression_list* args = this->args();
9067         go_assert(args != NULL && args->size() == 1);
9068         Expression* arg = args->front();
9069         tree arg_tree = arg->get_tree(context);
9070         if (arg_tree == error_mark_node)
9071           return error_mark_node;
9072         static tree close_fndecl;
9073         return Gogo::call_builtin(&close_fndecl,
9074                                   location,
9075                                   "__go_builtin_close",
9076                                   1,
9077                                   void_type_node,
9078                                   TREE_TYPE(arg_tree),
9079                                   arg_tree);
9080       }
9081
9082     case BUILTIN_SIZEOF:
9083     case BUILTIN_OFFSETOF:
9084     case BUILTIN_ALIGNOF:
9085       {
9086         mpz_t val;
9087         mpz_init(val);
9088         Type* dummy;
9089         bool b = this->integer_constant_value(true, val, &dummy);
9090         if (!b)
9091           {
9092             go_assert(saw_errors());
9093             return error_mark_node;
9094           }
9095         Type* int_type = Type::lookup_integer_type("int");
9096         tree type = type_to_tree(int_type->get_backend(gogo));
9097         tree ret = Expression::integer_constant_tree(val, type);
9098         mpz_clear(val);
9099         return ret;
9100       }
9101
9102     case BUILTIN_COPY:
9103       {
9104         const Expression_list* args = this->args();
9105         go_assert(args != NULL && args->size() == 2);
9106         Expression* arg1 = args->front();
9107         Expression* arg2 = args->back();
9108
9109         tree arg1_tree = arg1->get_tree(context);
9110         tree arg2_tree = arg2->get_tree(context);
9111         if (arg1_tree == error_mark_node || arg2_tree == error_mark_node)
9112           return error_mark_node;
9113
9114         Type* arg1_type = arg1->type();
9115         Array_type* at = arg1_type->array_type();
9116         arg1_tree = save_expr(arg1_tree);
9117         tree arg1_val = at->value_pointer_tree(gogo, arg1_tree);
9118         tree arg1_len = at->length_tree(gogo, arg1_tree);
9119         if (arg1_val == error_mark_node || arg1_len == error_mark_node)
9120           return error_mark_node;
9121
9122         Type* arg2_type = arg2->type();
9123         tree arg2_val;
9124         tree arg2_len;
9125         if (arg2_type->is_slice_type())
9126           {
9127             at = arg2_type->array_type();
9128             arg2_tree = save_expr(arg2_tree);
9129             arg2_val = at->value_pointer_tree(gogo, arg2_tree);
9130             arg2_len = at->length_tree(gogo, arg2_tree);
9131           }
9132         else
9133           {
9134             arg2_tree = save_expr(arg2_tree);
9135             arg2_val = String_type::bytes_tree(gogo, arg2_tree);
9136             arg2_len = String_type::length_tree(gogo, arg2_tree);
9137           }
9138         if (arg2_val == error_mark_node || arg2_len == error_mark_node)
9139           return error_mark_node;
9140
9141         arg1_len = save_expr(arg1_len);
9142         arg2_len = save_expr(arg2_len);
9143         tree len = fold_build3_loc(location.gcc_location(), COND_EXPR,
9144                                    TREE_TYPE(arg1_len),
9145                                    fold_build2_loc(location.gcc_location(),
9146                                                    LT_EXPR, boolean_type_node,
9147                                                    arg1_len, arg2_len),
9148                                    arg1_len, arg2_len);
9149         len = save_expr(len);
9150
9151         Type* element_type = at->element_type();
9152         Btype* element_btype = element_type->get_backend(gogo);
9153         tree element_type_tree = type_to_tree(element_btype);
9154         if (element_type_tree == error_mark_node)
9155           return error_mark_node;
9156         tree element_size = TYPE_SIZE_UNIT(element_type_tree);
9157         tree bytecount = fold_convert_loc(location.gcc_location(),
9158                                           TREE_TYPE(element_size), len);
9159         bytecount = fold_build2_loc(location.gcc_location(), MULT_EXPR,
9160                                     TREE_TYPE(element_size),
9161                                     bytecount, element_size);
9162         bytecount = fold_convert_loc(location.gcc_location(), size_type_node,
9163                                      bytecount);
9164
9165         arg1_val = fold_convert_loc(location.gcc_location(), ptr_type_node,
9166                                     arg1_val);
9167         arg2_val = fold_convert_loc(location.gcc_location(), ptr_type_node,
9168                                     arg2_val);
9169
9170         static tree copy_fndecl;
9171         tree call = Gogo::call_builtin(&copy_fndecl,
9172                                        location,
9173                                        "__go_copy",
9174                                        3,
9175                                        void_type_node,
9176                                        ptr_type_node,
9177                                        arg1_val,
9178                                        ptr_type_node,
9179                                        arg2_val,
9180                                        size_type_node,
9181                                        bytecount);
9182         if (call == error_mark_node)
9183           return error_mark_node;
9184
9185         return fold_build2_loc(location.gcc_location(), COMPOUND_EXPR,
9186                                TREE_TYPE(len), call, len);
9187       }
9188
9189     case BUILTIN_APPEND:
9190       {
9191         const Expression_list* args = this->args();
9192         go_assert(args != NULL && args->size() == 2);
9193         Expression* arg1 = args->front();
9194         Expression* arg2 = args->back();
9195
9196         tree arg1_tree = arg1->get_tree(context);
9197         tree arg2_tree = arg2->get_tree(context);
9198         if (arg1_tree == error_mark_node || arg2_tree == error_mark_node)
9199           return error_mark_node;
9200
9201         Array_type* at = arg1->type()->array_type();
9202         Type* element_type = at->element_type()->forwarded();
9203
9204         tree arg2_val;
9205         tree arg2_len;
9206         tree element_size;
9207         if (arg2->type()->is_string_type()
9208             && element_type->integer_type() != NULL
9209             && element_type->integer_type()->is_byte())
9210           {
9211             arg2_tree = save_expr(arg2_tree);
9212             arg2_val = String_type::bytes_tree(gogo, arg2_tree);
9213             arg2_len = String_type::length_tree(gogo, arg2_tree);
9214             element_size = size_int(1);
9215           }
9216         else
9217           {
9218             arg2_tree = Expression::convert_for_assignment(context, at,
9219                                                            arg2->type(),
9220                                                            arg2_tree,
9221                                                            location);
9222             if (arg2_tree == error_mark_node)
9223               return error_mark_node;
9224
9225             arg2_tree = save_expr(arg2_tree);
9226
9227              arg2_val = at->value_pointer_tree(gogo, arg2_tree);
9228              arg2_len = at->length_tree(gogo, arg2_tree);
9229
9230              Btype* element_btype = element_type->get_backend(gogo);
9231              tree element_type_tree = type_to_tree(element_btype);
9232              if (element_type_tree == error_mark_node)
9233                return error_mark_node;
9234              element_size = TYPE_SIZE_UNIT(element_type_tree);
9235           }
9236
9237         arg2_val = fold_convert_loc(location.gcc_location(), ptr_type_node,
9238                                     arg2_val);
9239         arg2_len = fold_convert_loc(location.gcc_location(), size_type_node,
9240                                     arg2_len);
9241         element_size = fold_convert_loc(location.gcc_location(), size_type_node,
9242                                         element_size);
9243
9244         if (arg2_val == error_mark_node
9245             || arg2_len == error_mark_node
9246             || element_size == error_mark_node)
9247           return error_mark_node;
9248
9249         // We rebuild the decl each time since the slice types may
9250         // change.
9251         tree append_fndecl = NULL_TREE;
9252         return Gogo::call_builtin(&append_fndecl,
9253                                   location,
9254                                   "__go_append",
9255                                   4,
9256                                   TREE_TYPE(arg1_tree),
9257                                   TREE_TYPE(arg1_tree),
9258                                   arg1_tree,
9259                                   ptr_type_node,
9260                                   arg2_val,
9261                                   size_type_node,
9262                                   arg2_len,
9263                                   size_type_node,
9264                                   element_size);
9265       }
9266
9267     case BUILTIN_REAL:
9268     case BUILTIN_IMAG:
9269       {
9270         const Expression_list* args = this->args();
9271         go_assert(args != NULL && args->size() == 1);
9272         Expression* arg = args->front();
9273         tree arg_tree = arg->get_tree(context);
9274         if (arg_tree == error_mark_node)
9275           return error_mark_node;
9276         go_assert(COMPLEX_FLOAT_TYPE_P(TREE_TYPE(arg_tree)));
9277         if (this->code_ == BUILTIN_REAL)
9278           return fold_build1_loc(location.gcc_location(), REALPART_EXPR,
9279                                  TREE_TYPE(TREE_TYPE(arg_tree)),
9280                                  arg_tree);
9281         else
9282           return fold_build1_loc(location.gcc_location(), IMAGPART_EXPR,
9283                                  TREE_TYPE(TREE_TYPE(arg_tree)),
9284                                  arg_tree);
9285       }
9286
9287     case BUILTIN_COMPLEX:
9288       {
9289         const Expression_list* args = this->args();
9290         go_assert(args != NULL && args->size() == 2);
9291         tree r = args->front()->get_tree(context);
9292         tree i = args->back()->get_tree(context);
9293         if (r == error_mark_node || i == error_mark_node)
9294           return error_mark_node;
9295         go_assert(TYPE_MAIN_VARIANT(TREE_TYPE(r))
9296                    == TYPE_MAIN_VARIANT(TREE_TYPE(i)));
9297         go_assert(SCALAR_FLOAT_TYPE_P(TREE_TYPE(r)));
9298         return fold_build2_loc(location.gcc_location(), COMPLEX_EXPR,
9299                                build_complex_type(TREE_TYPE(r)),
9300                                r, i);
9301       }
9302
9303     default:
9304       go_unreachable();
9305     }
9306 }
9307
9308 // We have to support exporting a builtin call expression, because
9309 // code can set a constant to the result of a builtin expression.
9310
9311 void
9312 Builtin_call_expression::do_export(Export* exp) const
9313 {
9314   bool ok = false;
9315
9316   mpz_t val;
9317   mpz_init(val);
9318   Type* dummy;
9319   if (this->integer_constant_value(true, val, &dummy))
9320     {
9321       Integer_expression::export_integer(exp, val);
9322       ok = true;
9323     }
9324   mpz_clear(val);
9325
9326   if (!ok)
9327     {
9328       mpfr_t fval;
9329       mpfr_init(fval);
9330       if (this->float_constant_value(fval, &dummy))
9331         {
9332           Float_expression::export_float(exp, fval);
9333           ok = true;
9334         }
9335       mpfr_clear(fval);
9336     }
9337
9338   if (!ok)
9339     {
9340       mpfr_t real;
9341       mpfr_t imag;
9342       mpfr_init(real);
9343       mpfr_init(imag);
9344       if (this->complex_constant_value(real, imag, &dummy))
9345         {
9346           Complex_expression::export_complex(exp, real, imag);
9347           ok = true;
9348         }
9349       mpfr_clear(real);
9350       mpfr_clear(imag);
9351     }
9352
9353   if (!ok)
9354     {
9355       error_at(this->location(), "value is not constant");
9356       return;
9357     }
9358
9359   // A trailing space lets us reliably identify the end of the number.
9360   exp->write_c_string(" ");
9361 }
9362
9363 // Class Call_expression.
9364
9365 // Traversal.
9366
9367 int
9368 Call_expression::do_traverse(Traverse* traverse)
9369 {
9370   if (Expression::traverse(&this->fn_, traverse) == TRAVERSE_EXIT)
9371     return TRAVERSE_EXIT;
9372   if (this->args_ != NULL)
9373     {
9374       if (this->args_->traverse(traverse) == TRAVERSE_EXIT)
9375         return TRAVERSE_EXIT;
9376     }
9377   return TRAVERSE_CONTINUE;
9378 }
9379
9380 // Lower a call statement.
9381
9382 Expression*
9383 Call_expression::do_lower(Gogo* gogo, Named_object* function,
9384                           Statement_inserter* inserter, int)
9385 {
9386   Location loc = this->location();
9387
9388   // A type cast can look like a function call.
9389   if (this->fn_->is_type_expression()
9390       && this->args_ != NULL
9391       && this->args_->size() == 1)
9392     return Expression::make_cast(this->fn_->type(), this->args_->front(),
9393                                  loc);
9394
9395   // Recognize a call to a builtin function.
9396   Func_expression* fne = this->fn_->func_expression();
9397   if (fne != NULL
9398       && fne->named_object()->is_function_declaration()
9399       && fne->named_object()->func_declaration_value()->type()->is_builtin())
9400     return new Builtin_call_expression(gogo, this->fn_, this->args_,
9401                                        this->is_varargs_, loc);
9402
9403   // Handle an argument which is a call to a function which returns
9404   // multiple results.
9405   if (this->args_ != NULL
9406       && this->args_->size() == 1
9407       && this->args_->front()->call_expression() != NULL
9408       && this->fn_->type()->function_type() != NULL)
9409     {
9410       Function_type* fntype = this->fn_->type()->function_type();
9411       size_t rc = this->args_->front()->call_expression()->result_count();
9412       if (rc > 1
9413           && fntype->parameters() != NULL
9414           && (fntype->parameters()->size() == rc
9415               || (fntype->is_varargs()
9416                   && fntype->parameters()->size() - 1 <= rc)))
9417         {
9418           Call_expression* call = this->args_->front()->call_expression();
9419           Expression_list* args = new Expression_list;
9420           for (size_t i = 0; i < rc; ++i)
9421             args->push_back(Expression::make_call_result(call, i));
9422           // We can't return a new call expression here, because this
9423           // one may be referenced by Call_result expressions.  We
9424           // also can't delete the old arguments, because we may still
9425           // traverse them somewhere up the call stack.  FIXME.
9426           this->args_ = args;
9427         }
9428     }
9429
9430   // If this call returns multiple results, create a temporary
9431   // variable for each result.
9432   size_t rc = this->result_count();
9433   if (rc > 1 && this->results_ == NULL)
9434     {
9435       std::vector<Temporary_statement*>* temps =
9436         new std::vector<Temporary_statement*>;
9437       temps->reserve(rc);
9438       const Typed_identifier_list* results =
9439         this->fn_->type()->function_type()->results();
9440       for (Typed_identifier_list::const_iterator p = results->begin();
9441            p != results->end();
9442            ++p)
9443         {
9444           Temporary_statement* temp = Statement::make_temporary(p->type(),
9445                                                                 NULL, loc);
9446           inserter->insert(temp);
9447           temps->push_back(temp);
9448         }
9449       this->results_ = temps;
9450     }
9451
9452   // Handle a call to a varargs function by packaging up the extra
9453   // parameters.
9454   if (this->fn_->type()->function_type() != NULL
9455       && this->fn_->type()->function_type()->is_varargs())
9456     {
9457       Function_type* fntype = this->fn_->type()->function_type();
9458       const Typed_identifier_list* parameters = fntype->parameters();
9459       go_assert(parameters != NULL && !parameters->empty());
9460       Type* varargs_type = parameters->back().type();
9461       this->lower_varargs(gogo, function, inserter, varargs_type,
9462                           parameters->size());
9463     }
9464
9465   // If this is call to a method, call the method directly passing the
9466   // object as the first parameter.
9467   Bound_method_expression* bme = this->fn_->bound_method_expression();
9468   if (bme != NULL)
9469     {
9470       Named_object* method = bme->method();
9471       Expression* first_arg = bme->first_argument();
9472
9473       // We always pass a pointer when calling a method.
9474       if (first_arg->type()->points_to() == NULL
9475           && !first_arg->type()->is_error())
9476         {
9477           first_arg = Expression::make_unary(OPERATOR_AND, first_arg, loc);
9478           // We may need to create a temporary variable so that we can
9479           // take the address.  We can't do that here because it will
9480           // mess up the order of evaluation.
9481           Unary_expression* ue = static_cast<Unary_expression*>(first_arg);
9482           ue->set_create_temp();
9483         }
9484
9485       // If we are calling a method which was inherited from an
9486       // embedded struct, and the method did not get a stub, then the
9487       // first type may be wrong.
9488       Type* fatype = bme->first_argument_type();
9489       if (fatype != NULL)
9490         {
9491           if (fatype->points_to() == NULL)
9492             fatype = Type::make_pointer_type(fatype);
9493           first_arg = Expression::make_unsafe_cast(fatype, first_arg, loc);
9494         }
9495
9496       Expression_list* new_args = new Expression_list();
9497       new_args->push_back(first_arg);
9498       if (this->args_ != NULL)
9499         {
9500           for (Expression_list::const_iterator p = this->args_->begin();
9501                p != this->args_->end();
9502                ++p)
9503             new_args->push_back(*p);
9504         }
9505
9506       // We have to change in place because this structure may be
9507       // referenced by Call_result_expressions.  We can't delete the
9508       // old arguments, because we may be traversing them up in some
9509       // caller.  FIXME.
9510       this->args_ = new_args;
9511       this->fn_ = Expression::make_func_reference(method, NULL,
9512                                                   bme->location());
9513     }
9514
9515   return this;
9516 }
9517
9518 // Lower a call to a varargs function.  FUNCTION is the function in
9519 // which the call occurs--it's not the function we are calling.
9520 // VARARGS_TYPE is the type of the varargs parameter, a slice type.
9521 // PARAM_COUNT is the number of parameters of the function we are
9522 // calling; the last of these parameters will be the varargs
9523 // parameter.
9524
9525 void
9526 Call_expression::lower_varargs(Gogo* gogo, Named_object* function,
9527                                Statement_inserter* inserter,
9528                                Type* varargs_type, size_t param_count)
9529 {
9530   if (this->varargs_are_lowered_)
9531     return;
9532
9533   Location loc = this->location();
9534
9535   go_assert(param_count > 0);
9536   go_assert(varargs_type->is_slice_type());
9537
9538   size_t arg_count = this->args_ == NULL ? 0 : this->args_->size();
9539   if (arg_count < param_count - 1)
9540     {
9541       // Not enough arguments; will be caught in check_types.
9542       return;
9543     }
9544
9545   Expression_list* old_args = this->args_;
9546   Expression_list* new_args = new Expression_list();
9547   bool push_empty_arg = false;
9548   if (old_args == NULL || old_args->empty())
9549     {
9550       go_assert(param_count == 1);
9551       push_empty_arg = true;
9552     }
9553   else
9554     {
9555       Expression_list::const_iterator pa;
9556       int i = 1;
9557       for (pa = old_args->begin(); pa != old_args->end(); ++pa, ++i)
9558         {
9559           if (static_cast<size_t>(i) == param_count)
9560             break;
9561           new_args->push_back(*pa);
9562         }
9563
9564       // We have reached the varargs parameter.
9565
9566       bool issued_error = false;
9567       if (pa == old_args->end())
9568         push_empty_arg = true;
9569       else if (pa + 1 == old_args->end() && this->is_varargs_)
9570         new_args->push_back(*pa);
9571       else if (this->is_varargs_)
9572         {
9573           this->report_error(_("too many arguments"));
9574           return;
9575         }
9576       else
9577         {
9578           Type* element_type = varargs_type->array_type()->element_type();
9579           Expression_list* vals = new Expression_list;
9580           for (; pa != old_args->end(); ++pa, ++i)
9581             {
9582               // Check types here so that we get a better message.
9583               Type* patype = (*pa)->type();
9584               Location paloc = (*pa)->location();
9585               if (!this->check_argument_type(i, element_type, patype,
9586                                              paloc, issued_error))
9587                 continue;
9588               vals->push_back(*pa);
9589             }
9590           Expression* val =
9591             Expression::make_slice_composite_literal(varargs_type, vals, loc);
9592           gogo->lower_expression(function, inserter, &val);
9593           new_args->push_back(val);
9594         }
9595     }
9596
9597   if (push_empty_arg)
9598     new_args->push_back(Expression::make_nil(loc));
9599
9600   // We can't return a new call expression here, because this one may
9601   // be referenced by Call_result expressions.  FIXME.  We can't
9602   // delete OLD_ARGS because we may have both a Call_expression and a
9603   // Builtin_call_expression which refer to them.  FIXME.
9604   this->args_ = new_args;
9605   this->varargs_are_lowered_ = true;
9606 }
9607
9608 // Get the function type.  This can return NULL in error cases.
9609
9610 Function_type*
9611 Call_expression::get_function_type() const
9612 {
9613   return this->fn_->type()->function_type();
9614 }
9615
9616 // Return the number of values which this call will return.
9617
9618 size_t
9619 Call_expression::result_count() const
9620 {
9621   const Function_type* fntype = this->get_function_type();
9622   if (fntype == NULL)
9623     return 0;
9624   if (fntype->results() == NULL)
9625     return 0;
9626   return fntype->results()->size();
9627 }
9628
9629 // Return the temporary which holds a result.
9630
9631 Temporary_statement*
9632 Call_expression::result(size_t i) const
9633 {
9634   go_assert(this->results_ != NULL
9635             && this->results_->size() > i);
9636   return (*this->results_)[i];
9637 }
9638
9639 // Return whether this is a call to the predeclared function recover.
9640
9641 bool
9642 Call_expression::is_recover_call() const
9643 {
9644   return this->do_is_recover_call();
9645 }
9646
9647 // Set the argument to the recover function.
9648
9649 void
9650 Call_expression::set_recover_arg(Expression* arg)
9651 {
9652   this->do_set_recover_arg(arg);
9653 }
9654
9655 // Virtual functions also implemented by Builtin_call_expression.
9656
9657 bool
9658 Call_expression::do_is_recover_call() const
9659 {
9660   return false;
9661 }
9662
9663 void
9664 Call_expression::do_set_recover_arg(Expression*)
9665 {
9666   go_unreachable();
9667 }
9668
9669 // We have found an error with this call expression; return true if
9670 // we should report it.
9671
9672 bool
9673 Call_expression::issue_error()
9674 {
9675   if (this->issued_error_)
9676     return false;
9677   else
9678     {
9679       this->issued_error_ = true;
9680       return true;
9681     }
9682 }
9683
9684 // Get the type.
9685
9686 Type*
9687 Call_expression::do_type()
9688 {
9689   if (this->type_ != NULL)
9690     return this->type_;
9691
9692   Type* ret;
9693   Function_type* fntype = this->get_function_type();
9694   if (fntype == NULL)
9695     return Type::make_error_type();
9696
9697   const Typed_identifier_list* results = fntype->results();
9698   if (results == NULL)
9699     ret = Type::make_void_type();
9700   else if (results->size() == 1)
9701     ret = results->begin()->type();
9702   else
9703     ret = Type::make_call_multiple_result_type(this);
9704
9705   this->type_ = ret;
9706
9707   return this->type_;
9708 }
9709
9710 // Determine types for a call expression.  We can use the function
9711 // parameter types to set the types of the arguments.
9712
9713 void
9714 Call_expression::do_determine_type(const Type_context*)
9715 {
9716   if (!this->determining_types())
9717     return;
9718
9719   this->fn_->determine_type_no_context();
9720   Function_type* fntype = this->get_function_type();
9721   const Typed_identifier_list* parameters = NULL;
9722   if (fntype != NULL)
9723     parameters = fntype->parameters();
9724   if (this->args_ != NULL)
9725     {
9726       Typed_identifier_list::const_iterator pt;
9727       if (parameters != NULL)
9728         pt = parameters->begin();
9729       bool first = true;
9730       for (Expression_list::const_iterator pa = this->args_->begin();
9731            pa != this->args_->end();
9732            ++pa)
9733         {
9734           if (first)
9735             {
9736               first = false;
9737               // If this is a method, the first argument is the
9738               // receiver.
9739               if (fntype != NULL && fntype->is_method())
9740                 {
9741                   Type* rtype = fntype->receiver()->type();
9742                   // The receiver is always passed as a pointer.
9743                   if (rtype->points_to() == NULL)
9744                     rtype = Type::make_pointer_type(rtype);
9745                   Type_context subcontext(rtype, false);
9746                   (*pa)->determine_type(&subcontext);
9747                   continue;
9748                 }
9749             }
9750
9751           if (parameters != NULL && pt != parameters->end())
9752             {
9753               Type_context subcontext(pt->type(), false);
9754               (*pa)->determine_type(&subcontext);
9755               ++pt;
9756             }
9757           else
9758             (*pa)->determine_type_no_context();
9759         }
9760     }
9761 }
9762
9763 // Called when determining types for a Call_expression.  Return true
9764 // if we should go ahead, false if they have already been determined.
9765
9766 bool
9767 Call_expression::determining_types()
9768 {
9769   if (this->types_are_determined_)
9770     return false;
9771   else
9772     {
9773       this->types_are_determined_ = true;
9774       return true;
9775     }
9776 }
9777
9778 // Check types for parameter I.
9779
9780 bool
9781 Call_expression::check_argument_type(int i, const Type* parameter_type,
9782                                      const Type* argument_type,
9783                                      Location argument_location,
9784                                      bool issued_error)
9785 {
9786   std::string reason;
9787   bool ok;
9788   if (this->are_hidden_fields_ok_)
9789     ok = Type::are_assignable_hidden_ok(parameter_type, argument_type,
9790                                         &reason);
9791   else
9792     ok = Type::are_assignable(parameter_type, argument_type, &reason);
9793   if (!ok)
9794     {
9795       if (!issued_error)
9796         {
9797           if (reason.empty())
9798             error_at(argument_location, "argument %d has incompatible type", i);
9799           else
9800             error_at(argument_location,
9801                      "argument %d has incompatible type (%s)",
9802                      i, reason.c_str());
9803         }
9804       this->set_is_error();
9805       return false;
9806     }
9807   return true;
9808 }
9809
9810 // Check types.
9811
9812 void
9813 Call_expression::do_check_types(Gogo*)
9814 {
9815   Function_type* fntype = this->get_function_type();
9816   if (fntype == NULL)
9817     {
9818       if (!this->fn_->type()->is_error())
9819         this->report_error(_("expected function"));
9820       return;
9821     }
9822
9823   bool is_method = fntype->is_method();
9824   if (is_method)
9825     {
9826       go_assert(this->args_ != NULL && !this->args_->empty());
9827       Type* rtype = fntype->receiver()->type();
9828       Expression* first_arg = this->args_->front();
9829       // The language permits copying hidden fields for a method
9830       // receiver.  We dereference the values since receivers are
9831       // always passed as pointers.
9832       std::string reason;
9833       if (!Type::are_assignable_hidden_ok(rtype->deref(),
9834                                           first_arg->type()->deref(),
9835                                           &reason))
9836         {
9837           if (reason.empty())
9838             this->report_error(_("incompatible type for receiver"));
9839           else
9840             {
9841               error_at(this->location(),
9842                        "incompatible type for receiver (%s)",
9843                        reason.c_str());
9844               this->set_is_error();
9845             }
9846         }
9847     }
9848
9849   // Note that varargs was handled by the lower_varargs() method, so
9850   // we don't have to worry about it here.
9851
9852   const Typed_identifier_list* parameters = fntype->parameters();
9853   if (this->args_ == NULL)
9854     {
9855       if (parameters != NULL && !parameters->empty())
9856         this->report_error(_("not enough arguments"));
9857     }
9858   else if (parameters == NULL)
9859     {
9860       if (!is_method || this->args_->size() > 1)
9861         this->report_error(_("too many arguments"));
9862     }
9863   else
9864     {
9865       int i = 0;
9866       Expression_list::const_iterator pa = this->args_->begin();
9867       if (is_method)
9868         ++pa;
9869       for (Typed_identifier_list::const_iterator pt = parameters->begin();
9870            pt != parameters->end();
9871            ++pt, ++pa, ++i)
9872         {
9873           if (pa == this->args_->end())
9874             {
9875               this->report_error(_("not enough arguments"));
9876               return;
9877             }
9878           this->check_argument_type(i + 1, pt->type(), (*pa)->type(),
9879                                     (*pa)->location(), false);
9880         }
9881       if (pa != this->args_->end())
9882         this->report_error(_("too many arguments"));
9883     }
9884 }
9885
9886 // Return whether we have to use a temporary variable to ensure that
9887 // we evaluate this call expression in order.  If the call returns no
9888 // results then it will inevitably be executed last.
9889
9890 bool
9891 Call_expression::do_must_eval_in_order() const
9892 {
9893   return this->result_count() > 0;
9894 }
9895
9896 // Get the function and the first argument to use when calling an
9897 // interface method.
9898
9899 tree
9900 Call_expression::interface_method_function(
9901     Translate_context* context,
9902     Interface_field_reference_expression* interface_method,
9903     tree* first_arg_ptr)
9904 {
9905   tree expr = interface_method->expr()->get_tree(context);
9906   if (expr == error_mark_node)
9907     return error_mark_node;
9908   expr = save_expr(expr);
9909   tree first_arg = interface_method->get_underlying_object_tree(context, expr);
9910   if (first_arg == error_mark_node)
9911     return error_mark_node;
9912   *first_arg_ptr = first_arg;
9913   return interface_method->get_function_tree(context, expr);
9914 }
9915
9916 // Build the call expression.
9917
9918 tree
9919 Call_expression::do_get_tree(Translate_context* context)
9920 {
9921   if (this->tree_ != NULL_TREE)
9922     return this->tree_;
9923
9924   Function_type* fntype = this->get_function_type();
9925   if (fntype == NULL)
9926     return error_mark_node;
9927
9928   if (this->fn_->is_error_expression())
9929     return error_mark_node;
9930
9931   Gogo* gogo = context->gogo();
9932   Location location = this->location();
9933
9934   Func_expression* func = this->fn_->func_expression();
9935   Interface_field_reference_expression* interface_method =
9936     this->fn_->interface_field_reference_expression();
9937   const bool has_closure = func != NULL && func->closure() != NULL;
9938   const bool is_interface_method = interface_method != NULL;
9939
9940   int nargs;
9941   tree* args;
9942   if (this->args_ == NULL || this->args_->empty())
9943     {
9944       nargs = is_interface_method ? 1 : 0;
9945       args = nargs == 0 ? NULL : new tree[nargs];
9946     }
9947   else if (fntype->parameters() == NULL || fntype->parameters()->empty())
9948     {
9949       // Passing a receiver parameter.
9950       go_assert(!is_interface_method
9951                 && fntype->is_method()
9952                 && this->args_->size() == 1);
9953       nargs = 1;
9954       args = new tree[nargs];
9955       args[0] = this->args_->front()->get_tree(context);
9956     }
9957   else
9958     {
9959       const Typed_identifier_list* params = fntype->parameters();
9960
9961       nargs = this->args_->size();
9962       int i = is_interface_method ? 1 : 0;
9963       nargs += i;
9964       args = new tree[nargs];
9965
9966       Typed_identifier_list::const_iterator pp = params->begin();
9967       Expression_list::const_iterator pe = this->args_->begin();
9968       if (!is_interface_method && fntype->is_method())
9969         {
9970           args[i] = (*pe)->get_tree(context);
9971           ++pe;
9972           ++i;
9973         }
9974       for (; pe != this->args_->end(); ++pe, ++pp, ++i)
9975         {
9976           go_assert(pp != params->end());
9977           tree arg_val = (*pe)->get_tree(context);
9978           args[i] = Expression::convert_for_assignment(context,
9979                                                        pp->type(),
9980                                                        (*pe)->type(),
9981                                                        arg_val,
9982                                                        location);
9983           if (args[i] == error_mark_node)
9984             {
9985               delete[] args;
9986               return error_mark_node;
9987             }
9988         }
9989       go_assert(pp == params->end());
9990       go_assert(i == nargs);
9991     }
9992
9993   tree rettype = TREE_TYPE(TREE_TYPE(type_to_tree(fntype->get_backend(gogo))));
9994   if (rettype == error_mark_node)
9995     {
9996       delete[] args;
9997       return error_mark_node;
9998     }
9999
10000   tree fn;
10001   if (has_closure)
10002     fn = func->get_tree_without_closure(gogo);
10003   else if (!is_interface_method)
10004     fn = this->fn_->get_tree(context);
10005   else
10006     fn = this->interface_method_function(context, interface_method, &args[0]);
10007
10008   if (fn == error_mark_node || TREE_TYPE(fn) == error_mark_node)
10009     {
10010       delete[] args;
10011       return error_mark_node;
10012     }
10013
10014   tree fndecl = fn;
10015   if (TREE_CODE(fndecl) == ADDR_EXPR)
10016     fndecl = TREE_OPERAND(fndecl, 0);
10017
10018   // Add a type cast in case the type of the function is a recursive
10019   // type which refers to itself.
10020   if (!DECL_P(fndecl) || !DECL_IS_BUILTIN(fndecl))
10021     {
10022       tree fnt = type_to_tree(fntype->get_backend(gogo));
10023       if (fnt == error_mark_node)
10024         return error_mark_node;
10025       fn = fold_convert_loc(location.gcc_location(), fnt, fn);
10026     }
10027
10028   // This is to support builtin math functions when using 80387 math.
10029   tree excess_type = NULL_TREE;
10030   if (TREE_CODE(fndecl) == FUNCTION_DECL
10031       && DECL_IS_BUILTIN(fndecl)
10032       && DECL_BUILT_IN_CLASS(fndecl) == BUILT_IN_NORMAL
10033       && nargs > 0
10034       && ((SCALAR_FLOAT_TYPE_P(rettype)
10035            && SCALAR_FLOAT_TYPE_P(TREE_TYPE(args[0])))
10036           || (COMPLEX_FLOAT_TYPE_P(rettype)
10037               && COMPLEX_FLOAT_TYPE_P(TREE_TYPE(args[0])))))
10038     {
10039       excess_type = excess_precision_type(TREE_TYPE(args[0]));
10040       if (excess_type != NULL_TREE)
10041         {
10042           tree excess_fndecl = mathfn_built_in(excess_type,
10043                                                DECL_FUNCTION_CODE(fndecl));
10044           if (excess_fndecl == NULL_TREE)
10045             excess_type = NULL_TREE;
10046           else
10047             {
10048               fn = build_fold_addr_expr_loc(location.gcc_location(),
10049                                             excess_fndecl);
10050               for (int i = 0; i < nargs; ++i)
10051                 {
10052                   if (SCALAR_FLOAT_TYPE_P(TREE_TYPE(args[i]))
10053                       || COMPLEX_FLOAT_TYPE_P(TREE_TYPE(args[i])))
10054                     args[i] = ::convert(excess_type, args[i]);
10055                 }
10056             }
10057         }
10058     }
10059
10060   tree ret = build_call_array(excess_type != NULL_TREE ? excess_type : rettype,
10061                               fn, nargs, args);
10062   delete[] args;
10063
10064   SET_EXPR_LOCATION(ret, location.gcc_location());
10065
10066   if (has_closure)
10067     {
10068       tree closure_tree = func->closure()->get_tree(context);
10069       if (closure_tree != error_mark_node)
10070         CALL_EXPR_STATIC_CHAIN(ret) = closure_tree;
10071     }
10072
10073   // If this is a recursive function type which returns itself, as in
10074   //   type F func() F
10075   // we have used ptr_type_node for the return type.  Add a cast here
10076   // to the correct type.
10077   if (TREE_TYPE(ret) == ptr_type_node)
10078     {
10079       tree t = type_to_tree(this->type()->base()->get_backend(gogo));
10080       ret = fold_convert_loc(location.gcc_location(), t, ret);
10081     }
10082
10083   if (excess_type != NULL_TREE)
10084     {
10085       // Calling convert here can undo our excess precision change.
10086       // That may or may not be a bug in convert_to_real.
10087       ret = build1(NOP_EXPR, rettype, ret);
10088     }
10089
10090   if (this->results_ != NULL)
10091     ret = this->set_results(context, ret);
10092
10093   this->tree_ = ret;
10094
10095   return ret;
10096 }
10097
10098 // Set the result variables if this call returns multiple results.
10099
10100 tree
10101 Call_expression::set_results(Translate_context* context, tree call_tree)
10102 {
10103   tree stmt_list = NULL_TREE;
10104
10105   call_tree = save_expr(call_tree);
10106
10107   if (TREE_CODE(TREE_TYPE(call_tree)) != RECORD_TYPE)
10108     {
10109       go_assert(saw_errors());
10110       return call_tree;
10111     }
10112
10113   Location loc = this->location();
10114   tree field = TYPE_FIELDS(TREE_TYPE(call_tree));
10115   size_t rc = this->result_count();
10116   for (size_t i = 0; i < rc; ++i, field = DECL_CHAIN(field))
10117     {
10118       go_assert(field != NULL_TREE);
10119
10120       Temporary_statement* temp = this->result(i);
10121       Temporary_reference_expression* ref =
10122         Expression::make_temporary_reference(temp, loc);
10123       ref->set_is_lvalue();
10124       tree temp_tree = ref->get_tree(context);
10125       if (temp_tree == error_mark_node)
10126         continue;
10127
10128       tree val_tree = build3_loc(loc.gcc_location(), COMPONENT_REF,
10129                                  TREE_TYPE(field), call_tree, field, NULL_TREE);
10130       tree set_tree = build2_loc(loc.gcc_location(), MODIFY_EXPR,
10131                                  void_type_node, temp_tree, val_tree);
10132
10133       append_to_statement_list(set_tree, &stmt_list);
10134     }
10135   go_assert(field == NULL_TREE);
10136
10137   return save_expr(stmt_list);
10138 }
10139
10140 // Dump ast representation for a call expressin.
10141
10142 void
10143 Call_expression::do_dump_expression(Ast_dump_context* ast_dump_context) const
10144 {
10145   this->fn_->dump_expression(ast_dump_context);
10146   ast_dump_context->ostream() << "(";
10147   if (args_ != NULL)
10148     ast_dump_context->dump_expression_list(this->args_);
10149
10150   ast_dump_context->ostream() << ") ";
10151 }
10152
10153 // Make a call expression.
10154
10155 Call_expression*
10156 Expression::make_call(Expression* fn, Expression_list* args, bool is_varargs,
10157                       Location location)
10158 {
10159   return new Call_expression(fn, args, is_varargs, location);
10160 }
10161
10162 // A single result from a call which returns multiple results.
10163
10164 class Call_result_expression : public Expression
10165 {
10166  public:
10167   Call_result_expression(Call_expression* call, unsigned int index)
10168     : Expression(EXPRESSION_CALL_RESULT, call->location()),
10169       call_(call), index_(index)
10170   { }
10171
10172  protected:
10173   int
10174   do_traverse(Traverse*);
10175
10176   Type*
10177   do_type();
10178
10179   void
10180   do_determine_type(const Type_context*);
10181
10182   void
10183   do_check_types(Gogo*);
10184
10185   Expression*
10186   do_copy()
10187   {
10188     return new Call_result_expression(this->call_->call_expression(),
10189                                       this->index_);
10190   }
10191
10192   bool
10193   do_must_eval_in_order() const
10194   { return true; }
10195
10196   tree
10197   do_get_tree(Translate_context*);
10198
10199   void
10200   do_dump_expression(Ast_dump_context*) const;
10201
10202  private:
10203   // The underlying call expression.
10204   Expression* call_;
10205   // Which result we want.
10206   unsigned int index_;
10207 };
10208
10209 // Traverse a call result.
10210
10211 int
10212 Call_result_expression::do_traverse(Traverse* traverse)
10213 {
10214   if (traverse->remember_expression(this->call_))
10215     {
10216       // We have already traversed the call expression.
10217       return TRAVERSE_CONTINUE;
10218     }
10219   return Expression::traverse(&this->call_, traverse);
10220 }
10221
10222 // Get the type.
10223
10224 Type*
10225 Call_result_expression::do_type()
10226 {
10227   if (this->classification() == EXPRESSION_ERROR)
10228     return Type::make_error_type();
10229
10230   // THIS->CALL_ can be replaced with a temporary reference due to
10231   // Call_expression::do_must_eval_in_order when there is an error.
10232   Call_expression* ce = this->call_->call_expression();
10233   if (ce == NULL)
10234     {
10235       this->set_is_error();
10236       return Type::make_error_type();
10237     }
10238   Function_type* fntype = ce->get_function_type();
10239   if (fntype == NULL)
10240     {
10241       if (ce->issue_error())
10242         {
10243           if (!ce->fn()->type()->is_error())
10244             this->report_error(_("expected function"));
10245         }
10246       this->set_is_error();
10247       return Type::make_error_type();
10248     }
10249   const Typed_identifier_list* results = fntype->results();
10250   if (results == NULL || results->size() < 2)
10251     {
10252       if (ce->issue_error())
10253         this->report_error(_("number of results does not match "
10254                              "number of values"));
10255       return Type::make_error_type();
10256     }
10257   Typed_identifier_list::const_iterator pr = results->begin();
10258   for (unsigned int i = 0; i < this->index_; ++i)
10259     {
10260       if (pr == results->end())
10261         break;
10262       ++pr;
10263     }
10264   if (pr == results->end())
10265     {
10266       if (ce->issue_error())
10267         this->report_error(_("number of results does not match "
10268                              "number of values"));
10269       return Type::make_error_type();
10270     }
10271   return pr->type();
10272 }
10273
10274 // Check the type.  Just make sure that we trigger the warning in
10275 // do_type.
10276
10277 void
10278 Call_result_expression::do_check_types(Gogo*)
10279 {
10280   this->type();
10281 }
10282
10283 // Determine the type.  We have nothing to do here, but the 0 result
10284 // needs to pass down to the caller.
10285
10286 void
10287 Call_result_expression::do_determine_type(const Type_context*)
10288 {
10289   this->call_->determine_type_no_context();
10290 }
10291
10292 // Return the tree.  We just refer to the temporary set by the call
10293 // expression.  We don't do this at lowering time because it makes it
10294 // hard to evaluate the call at the right time.
10295
10296 tree
10297 Call_result_expression::do_get_tree(Translate_context* context)
10298 {
10299   Call_expression* ce = this->call_->call_expression();
10300   go_assert(ce != NULL);
10301   Temporary_statement* ts = ce->result(this->index_);
10302   Expression* ref = Expression::make_temporary_reference(ts, this->location());
10303   return ref->get_tree(context);
10304 }
10305
10306 // Dump ast representation for a call result expression.
10307
10308 void
10309 Call_result_expression::do_dump_expression(Ast_dump_context* ast_dump_context)
10310     const
10311 {
10312   // FIXME: Wouldn't it be better if the call is assigned to a temporary
10313   // (struct) and the fields are referenced instead.
10314   ast_dump_context->ostream() << this->index_ << "@(";
10315   ast_dump_context->dump_expression(this->call_);
10316   ast_dump_context->ostream() << ")";
10317 }
10318
10319 // Make a reference to a single result of a call which returns
10320 // multiple results.
10321
10322 Expression*
10323 Expression::make_call_result(Call_expression* call, unsigned int index)
10324 {
10325   return new Call_result_expression(call, index);
10326 }
10327
10328 // Class Index_expression.
10329
10330 // Traversal.
10331
10332 int
10333 Index_expression::do_traverse(Traverse* traverse)
10334 {
10335   if (Expression::traverse(&this->left_, traverse) == TRAVERSE_EXIT
10336       || Expression::traverse(&this->start_, traverse) == TRAVERSE_EXIT
10337       || (this->end_ != NULL
10338           && Expression::traverse(&this->end_, traverse) == TRAVERSE_EXIT))
10339     return TRAVERSE_EXIT;
10340   return TRAVERSE_CONTINUE;
10341 }
10342
10343 // Lower an index expression.  This converts the generic index
10344 // expression into an array index, a string index, or a map index.
10345
10346 Expression*
10347 Index_expression::do_lower(Gogo*, Named_object*, Statement_inserter*, int)
10348 {
10349   Location location = this->location();
10350   Expression* left = this->left_;
10351   Expression* start = this->start_;
10352   Expression* end = this->end_;
10353
10354   Type* type = left->type();
10355   if (type->is_error())
10356     return Expression::make_error(location);
10357   else if (left->is_type_expression())
10358     {
10359       error_at(location, "attempt to index type expression");
10360       return Expression::make_error(location);
10361     }
10362   else if (type->array_type() != NULL)
10363     return Expression::make_array_index(left, start, end, location);
10364   else if (type->points_to() != NULL
10365            && type->points_to()->array_type() != NULL
10366            && !type->points_to()->is_slice_type())
10367     {
10368       Expression* deref = Expression::make_unary(OPERATOR_MULT, left,
10369                                                  location);
10370       return Expression::make_array_index(deref, start, end, location);
10371     }
10372   else if (type->is_string_type())
10373     return Expression::make_string_index(left, start, end, location);
10374   else if (type->map_type() != NULL)
10375     {
10376       if (end != NULL)
10377         {
10378           error_at(location, "invalid slice of map");
10379           return Expression::make_error(location);
10380         }
10381       Map_index_expression* ret = Expression::make_map_index(left, start,
10382                                                              location);
10383       if (this->is_lvalue_)
10384         ret->set_is_lvalue();
10385       return ret;
10386     }
10387   else
10388     {
10389       error_at(location,
10390                "attempt to index object which is not array, string, or map");
10391       return Expression::make_error(location);
10392     }
10393 }
10394
10395 // Write an indexed expression (expr[expr:expr] or expr[expr]) to a
10396 // dump context
10397
10398 void
10399 Index_expression::dump_index_expression(Ast_dump_context* ast_dump_context,
10400                                         const Expression* expr,
10401                                         const Expression* start,
10402                                         const Expression* end)
10403 {
10404   expr->dump_expression(ast_dump_context);
10405   ast_dump_context->ostream() << "[";
10406   start->dump_expression(ast_dump_context);
10407   if (end != NULL)
10408     {
10409       ast_dump_context->ostream() << ":";
10410       end->dump_expression(ast_dump_context);
10411     }
10412   ast_dump_context->ostream() << "]";
10413 }
10414
10415 // Dump ast representation for an index expression.
10416
10417 void
10418 Index_expression::do_dump_expression(Ast_dump_context* ast_dump_context)
10419     const
10420 {
10421   Index_expression::dump_index_expression(ast_dump_context, this->left_,
10422                                           this->start_, this->end_);
10423 }
10424
10425 // Make an index expression.
10426
10427 Expression*
10428 Expression::make_index(Expression* left, Expression* start, Expression* end,
10429                        Location location)
10430 {
10431   return new Index_expression(left, start, end, location);
10432 }
10433
10434 // An array index.  This is used for both indexing and slicing.
10435
10436 class Array_index_expression : public Expression
10437 {
10438  public:
10439   Array_index_expression(Expression* array, Expression* start,
10440                          Expression* end, Location location)
10441     : Expression(EXPRESSION_ARRAY_INDEX, location),
10442       array_(array), start_(start), end_(end), type_(NULL)
10443   { }
10444
10445  protected:
10446   int
10447   do_traverse(Traverse*);
10448
10449   Type*
10450   do_type();
10451
10452   void
10453   do_determine_type(const Type_context*);
10454
10455   void
10456   do_check_types(Gogo*);
10457
10458   Expression*
10459   do_copy()
10460   {
10461     return Expression::make_array_index(this->array_->copy(),
10462                                         this->start_->copy(),
10463                                         (this->end_ == NULL
10464                                          ? NULL
10465                                          : this->end_->copy()),
10466                                         this->location());
10467   }
10468
10469   bool
10470   do_must_eval_subexpressions_in_order(int* skip) const
10471   {
10472     *skip = 1;
10473     return true;
10474   }
10475
10476   bool
10477   do_is_addressable() const;
10478
10479   void
10480   do_address_taken(bool escapes)
10481   { this->array_->address_taken(escapes); }
10482
10483   tree
10484   do_get_tree(Translate_context*);
10485
10486   void
10487   do_dump_expression(Ast_dump_context*) const;
10488
10489  private:
10490   // The array we are getting a value from.
10491   Expression* array_;
10492   // The start or only index.
10493   Expression* start_;
10494   // The end index of a slice.  This may be NULL for a simple array
10495   // index, or it may be a nil expression for the length of the array.
10496   Expression* end_;
10497   // The type of the expression.
10498   Type* type_;
10499 };
10500
10501 // Array index traversal.
10502
10503 int
10504 Array_index_expression::do_traverse(Traverse* traverse)
10505 {
10506   if (Expression::traverse(&this->array_, traverse) == TRAVERSE_EXIT)
10507     return TRAVERSE_EXIT;
10508   if (Expression::traverse(&this->start_, traverse) == TRAVERSE_EXIT)
10509     return TRAVERSE_EXIT;
10510   if (this->end_ != NULL)
10511     {
10512       if (Expression::traverse(&this->end_, traverse) == TRAVERSE_EXIT)
10513         return TRAVERSE_EXIT;
10514     }
10515   return TRAVERSE_CONTINUE;
10516 }
10517
10518 // Return the type of an array index.
10519
10520 Type*
10521 Array_index_expression::do_type()
10522 {
10523   if (this->type_ == NULL)
10524     {
10525      Array_type* type = this->array_->type()->array_type();
10526       if (type == NULL)
10527         this->type_ = Type::make_error_type();
10528       else if (this->end_ == NULL)
10529         this->type_ = type->element_type();
10530       else if (type->is_slice_type())
10531         {
10532           // A slice of a slice has the same type as the original
10533           // slice.
10534           this->type_ = this->array_->type()->deref();
10535         }
10536       else
10537         {
10538           // A slice of an array is a slice.
10539           this->type_ = Type::make_array_type(type->element_type(), NULL);
10540         }
10541     }
10542   return this->type_;
10543 }
10544
10545 // Set the type of an array index.
10546
10547 void
10548 Array_index_expression::do_determine_type(const Type_context*)
10549 {
10550   this->array_->determine_type_no_context();
10551   this->start_->determine_type_no_context();
10552   if (this->end_ != NULL)
10553     this->end_->determine_type_no_context();
10554 }
10555
10556 // Check types of an array index.
10557
10558 void
10559 Array_index_expression::do_check_types(Gogo*)
10560 {
10561   if (this->start_->type()->integer_type() == NULL)
10562     this->report_error(_("index must be integer"));
10563   if (this->end_ != NULL
10564       && this->end_->type()->integer_type() == NULL
10565       && !this->end_->type()->is_error()
10566       && !this->end_->is_nil_expression()
10567       && !this->end_->is_error_expression())
10568     this->report_error(_("slice end must be integer"));
10569
10570   Array_type* array_type = this->array_->type()->array_type();
10571   if (array_type == NULL)
10572     {
10573       go_assert(this->array_->type()->is_error());
10574       return;
10575     }
10576
10577   unsigned int int_bits =
10578     Type::lookup_integer_type("int")->integer_type()->bits();
10579
10580   Type* dummy;
10581   mpz_t lval;
10582   mpz_init(lval);
10583   bool lval_valid = (array_type->length() != NULL
10584                      && array_type->length()->integer_constant_value(true,
10585                                                                      lval,
10586                                                                      &dummy));
10587   mpz_t ival;
10588   mpz_init(ival);
10589   if (this->start_->integer_constant_value(true, ival, &dummy))
10590     {
10591       if (mpz_sgn(ival) < 0
10592           || mpz_sizeinbase(ival, 2) >= int_bits
10593           || (lval_valid
10594               && (this->end_ == NULL
10595                   ? mpz_cmp(ival, lval) >= 0
10596                   : mpz_cmp(ival, lval) > 0)))
10597         {
10598           error_at(this->start_->location(), "array index out of bounds");
10599           this->set_is_error();
10600         }
10601     }
10602   if (this->end_ != NULL && !this->end_->is_nil_expression())
10603     {
10604       if (this->end_->integer_constant_value(true, ival, &dummy))
10605         {
10606           if (mpz_sgn(ival) < 0
10607               || mpz_sizeinbase(ival, 2) >= int_bits
10608               || (lval_valid && mpz_cmp(ival, lval) > 0))
10609             {
10610               error_at(this->end_->location(), "array index out of bounds");
10611               this->set_is_error();
10612             }
10613         }
10614     }
10615   mpz_clear(ival);
10616   mpz_clear(lval);
10617
10618   // A slice of an array requires an addressable array.  A slice of a
10619   // slice is always possible.
10620   if (this->end_ != NULL && !array_type->is_slice_type())
10621     {
10622       if (!this->array_->is_addressable())
10623         this->report_error(_("slice of unaddressable value"));
10624       else
10625         this->array_->address_taken(true);
10626     }
10627 }
10628
10629 // Return whether this expression is addressable.
10630
10631 bool
10632 Array_index_expression::do_is_addressable() const
10633 {
10634   // A slice expression is not addressable.
10635   if (this->end_ != NULL)
10636     return false;
10637
10638   // An index into a slice is addressable.
10639   if (this->array_->type()->is_slice_type())
10640     return true;
10641
10642   // An index into an array is addressable if the array is
10643   // addressable.
10644   return this->array_->is_addressable();
10645 }
10646
10647 // Get a tree for an array index.
10648
10649 tree
10650 Array_index_expression::do_get_tree(Translate_context* context)
10651 {
10652   Gogo* gogo = context->gogo();
10653   Location loc = this->location();
10654
10655   Array_type* array_type = this->array_->type()->array_type();
10656   if (array_type == NULL)
10657     {
10658       go_assert(this->array_->type()->is_error());
10659       return error_mark_node;
10660     }
10661
10662   tree type_tree = type_to_tree(array_type->get_backend(gogo));
10663   if (type_tree == error_mark_node)
10664     return error_mark_node;
10665
10666   tree array_tree = this->array_->get_tree(context);
10667   if (array_tree == error_mark_node)
10668     return error_mark_node;
10669
10670   if (array_type->length() == NULL && !DECL_P(array_tree))
10671     array_tree = save_expr(array_tree);
10672
10673   tree length_tree = NULL_TREE;
10674   if (this->end_ == NULL || this->end_->is_nil_expression())
10675     {
10676       length_tree = array_type->length_tree(gogo, array_tree);
10677       if (length_tree == error_mark_node)
10678         return error_mark_node;
10679       length_tree = save_expr(length_tree);
10680     }
10681
10682   tree capacity_tree = NULL_TREE;
10683   if (this->end_ != NULL)
10684     {
10685       capacity_tree = array_type->capacity_tree(gogo, array_tree);
10686       if (capacity_tree == error_mark_node)
10687         return error_mark_node;
10688       capacity_tree = save_expr(capacity_tree);
10689     }
10690
10691   tree length_type = (length_tree != NULL_TREE
10692                       ? TREE_TYPE(length_tree)
10693                       : TREE_TYPE(capacity_tree));
10694
10695   tree bad_index = boolean_false_node;
10696
10697   tree start_tree = this->start_->get_tree(context);
10698   if (start_tree == error_mark_node)
10699     return error_mark_node;
10700   if (!DECL_P(start_tree))
10701     start_tree = save_expr(start_tree);
10702   if (!INTEGRAL_TYPE_P(TREE_TYPE(start_tree)))
10703     start_tree = convert_to_integer(length_type, start_tree);
10704
10705   bad_index = Expression::check_bounds(start_tree, length_type, bad_index,
10706                                        loc);
10707
10708   start_tree = fold_convert_loc(loc.gcc_location(), length_type, start_tree);
10709   bad_index = fold_build2_loc(loc.gcc_location(), TRUTH_OR_EXPR,
10710                               boolean_type_node, bad_index,
10711                               fold_build2_loc(loc.gcc_location(),
10712                                               (this->end_ == NULL
10713                                                ? GE_EXPR
10714                                                : GT_EXPR),
10715                                               boolean_type_node, start_tree,
10716                                               (this->end_ == NULL
10717                                                ? length_tree
10718                                                : capacity_tree)));
10719
10720   int code = (array_type->length() != NULL
10721               ? (this->end_ == NULL
10722                  ? RUNTIME_ERROR_ARRAY_INDEX_OUT_OF_BOUNDS
10723                  : RUNTIME_ERROR_ARRAY_SLICE_OUT_OF_BOUNDS)
10724               : (this->end_ == NULL
10725                  ? RUNTIME_ERROR_SLICE_INDEX_OUT_OF_BOUNDS
10726                  : RUNTIME_ERROR_SLICE_SLICE_OUT_OF_BOUNDS));
10727   tree crash = Gogo::runtime_error(code, loc);
10728
10729   if (this->end_ == NULL)
10730     {
10731       // Simple array indexing.  This has to return an l-value, so
10732       // wrap the index check into START_TREE.
10733       start_tree = build2(COMPOUND_EXPR, TREE_TYPE(start_tree),
10734                           build3(COND_EXPR, void_type_node,
10735                                  bad_index, crash, NULL_TREE),
10736                           start_tree);
10737       start_tree = fold_convert_loc(loc.gcc_location(), sizetype, start_tree);
10738
10739       if (array_type->length() != NULL)
10740         {
10741           // Fixed array.
10742           return build4(ARRAY_REF, TREE_TYPE(type_tree), array_tree,
10743                         start_tree, NULL_TREE, NULL_TREE);
10744         }
10745       else
10746         {
10747           // Open array.
10748           tree values = array_type->value_pointer_tree(gogo, array_tree);
10749           Type* element_type = array_type->element_type();
10750           Btype* belement_type = element_type->get_backend(gogo);
10751           tree element_type_tree = type_to_tree(belement_type);
10752           if (element_type_tree == error_mark_node)
10753             return error_mark_node;
10754           tree element_size = TYPE_SIZE_UNIT(element_type_tree);
10755           tree offset = fold_build2_loc(loc.gcc_location(), MULT_EXPR, sizetype,
10756                                         start_tree, element_size);
10757           tree ptr = fold_build2_loc(loc.gcc_location(), POINTER_PLUS_EXPR,
10758                                      TREE_TYPE(values), values, offset);
10759           return build_fold_indirect_ref(ptr);
10760         }
10761     }
10762
10763   // Array slice.
10764
10765   tree end_tree;
10766   if (this->end_->is_nil_expression())
10767     end_tree = length_tree;
10768   else
10769     {
10770       end_tree = this->end_->get_tree(context);
10771       if (end_tree == error_mark_node)
10772         return error_mark_node;
10773       if (!DECL_P(end_tree))
10774         end_tree = save_expr(end_tree);
10775       if (!INTEGRAL_TYPE_P(TREE_TYPE(end_tree)))
10776         end_tree = convert_to_integer(length_type, end_tree);
10777
10778       bad_index = Expression::check_bounds(end_tree, length_type, bad_index,
10779                                            loc);
10780
10781       end_tree = fold_convert_loc(loc.gcc_location(), length_type, end_tree);
10782
10783       tree bad_end = fold_build2_loc(loc.gcc_location(), TRUTH_OR_EXPR,
10784                                      boolean_type_node,
10785                                      fold_build2_loc(loc.gcc_location(),
10786                                                      LT_EXPR, boolean_type_node,
10787                                                      end_tree, start_tree),
10788                                      fold_build2_loc(loc.gcc_location(),
10789                                                      GT_EXPR, boolean_type_node,
10790                                                      end_tree, capacity_tree));
10791       bad_index = fold_build2_loc(loc.gcc_location(), TRUTH_OR_EXPR,
10792                                   boolean_type_node, bad_index, bad_end);
10793     }
10794
10795   Type* element_type = array_type->element_type();
10796   tree element_type_tree = type_to_tree(element_type->get_backend(gogo));
10797   if (element_type_tree == error_mark_node)
10798     return error_mark_node;
10799   tree element_size = TYPE_SIZE_UNIT(element_type_tree);
10800
10801   tree offset = fold_build2_loc(loc.gcc_location(), MULT_EXPR, sizetype,
10802                                 fold_convert_loc(loc.gcc_location(), sizetype,
10803                                                  start_tree),
10804                                 element_size);
10805
10806   tree value_pointer = array_type->value_pointer_tree(gogo, array_tree);
10807   if (value_pointer == error_mark_node)
10808     return error_mark_node;
10809
10810   value_pointer = fold_build2_loc(loc.gcc_location(), POINTER_PLUS_EXPR,
10811                                   TREE_TYPE(value_pointer),
10812                                   value_pointer, offset);
10813
10814   tree result_length_tree = fold_build2_loc(loc.gcc_location(), MINUS_EXPR,
10815                                             length_type, end_tree, start_tree);
10816
10817   tree result_capacity_tree = fold_build2_loc(loc.gcc_location(), MINUS_EXPR,
10818                                               length_type, capacity_tree,
10819                                               start_tree);
10820
10821   tree struct_tree = type_to_tree(this->type()->get_backend(gogo));
10822   go_assert(TREE_CODE(struct_tree) == RECORD_TYPE);
10823
10824   VEC(constructor_elt,gc)* init = VEC_alloc(constructor_elt, gc, 3);
10825
10826   constructor_elt* elt = VEC_quick_push(constructor_elt, init, NULL);
10827   tree field = TYPE_FIELDS(struct_tree);
10828   go_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__values") == 0);
10829   elt->index = field;
10830   elt->value = value_pointer;
10831
10832   elt = VEC_quick_push(constructor_elt, init, NULL);
10833   field = DECL_CHAIN(field);
10834   go_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__count") == 0);
10835   elt->index = field;
10836   elt->value = fold_convert_loc(loc.gcc_location(), TREE_TYPE(field),
10837                                 result_length_tree);
10838
10839   elt = VEC_quick_push(constructor_elt, init, NULL);
10840   field = DECL_CHAIN(field);
10841   go_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__capacity") == 0);
10842   elt->index = field;
10843   elt->value = fold_convert_loc(loc.gcc_location(), TREE_TYPE(field),
10844                                 result_capacity_tree);
10845
10846   tree constructor = build_constructor(struct_tree, init);
10847
10848   if (TREE_CONSTANT(value_pointer)
10849       && TREE_CONSTANT(result_length_tree)
10850       && TREE_CONSTANT(result_capacity_tree))
10851     TREE_CONSTANT(constructor) = 1;
10852
10853   return fold_build2_loc(loc.gcc_location(), COMPOUND_EXPR,
10854                          TREE_TYPE(constructor),
10855                          build3(COND_EXPR, void_type_node,
10856                                 bad_index, crash, NULL_TREE),
10857                          constructor);
10858 }
10859
10860 // Dump ast representation for an array index expression.
10861
10862 void
10863 Array_index_expression::do_dump_expression(Ast_dump_context* ast_dump_context)
10864     const
10865 {
10866   Index_expression::dump_index_expression(ast_dump_context, this->array_,
10867                                           this->start_, this->end_);
10868 }
10869
10870 // Make an array index expression.  END may be NULL.
10871
10872 Expression*
10873 Expression::make_array_index(Expression* array, Expression* start,
10874                              Expression* end, Location location)
10875 {
10876   return new Array_index_expression(array, start, end, location);
10877 }
10878
10879 // A string index.  This is used for both indexing and slicing.
10880
10881 class String_index_expression : public Expression
10882 {
10883  public:
10884   String_index_expression(Expression* string, Expression* start,
10885                           Expression* end, Location location)
10886     : Expression(EXPRESSION_STRING_INDEX, location),
10887       string_(string), start_(start), end_(end)
10888   { }
10889
10890  protected:
10891   int
10892   do_traverse(Traverse*);
10893
10894   Type*
10895   do_type();
10896
10897   void
10898   do_determine_type(const Type_context*);
10899
10900   void
10901   do_check_types(Gogo*);
10902
10903   Expression*
10904   do_copy()
10905   {
10906     return Expression::make_string_index(this->string_->copy(),
10907                                          this->start_->copy(),
10908                                          (this->end_ == NULL
10909                                           ? NULL
10910                                           : this->end_->copy()),
10911                                          this->location());
10912   }
10913
10914   bool
10915   do_must_eval_subexpressions_in_order(int* skip) const
10916   {
10917     *skip = 1;
10918     return true;
10919   }
10920
10921   tree
10922   do_get_tree(Translate_context*);
10923
10924   void
10925   do_dump_expression(Ast_dump_context*) const;
10926
10927  private:
10928   // The string we are getting a value from.
10929   Expression* string_;
10930   // The start or only index.
10931   Expression* start_;
10932   // The end index of a slice.  This may be NULL for a single index,
10933   // or it may be a nil expression for the length of the string.
10934   Expression* end_;
10935 };
10936
10937 // String index traversal.
10938
10939 int
10940 String_index_expression::do_traverse(Traverse* traverse)
10941 {
10942   if (Expression::traverse(&this->string_, traverse) == TRAVERSE_EXIT)
10943     return TRAVERSE_EXIT;
10944   if (Expression::traverse(&this->start_, traverse) == TRAVERSE_EXIT)
10945     return TRAVERSE_EXIT;
10946   if (this->end_ != NULL)
10947     {
10948       if (Expression::traverse(&this->end_, traverse) == TRAVERSE_EXIT)
10949         return TRAVERSE_EXIT;
10950     }
10951   return TRAVERSE_CONTINUE;
10952 }
10953
10954 // Return the type of a string index.
10955
10956 Type*
10957 String_index_expression::do_type()
10958 {
10959   if (this->end_ == NULL)
10960     return Type::lookup_integer_type("uint8");
10961   else
10962     return this->string_->type();
10963 }
10964
10965 // Determine the type of a string index.
10966
10967 void
10968 String_index_expression::do_determine_type(const Type_context*)
10969 {
10970   this->string_->determine_type_no_context();
10971   this->start_->determine_type_no_context();
10972   if (this->end_ != NULL)
10973     this->end_->determine_type_no_context();
10974 }
10975
10976 // Check types of a string index.
10977
10978 void
10979 String_index_expression::do_check_types(Gogo*)
10980 {
10981   if (this->start_->type()->integer_type() == NULL)
10982     this->report_error(_("index must be integer"));
10983   if (this->end_ != NULL
10984       && this->end_->type()->integer_type() == NULL
10985       && !this->end_->is_nil_expression())
10986     this->report_error(_("slice end must be integer"));
10987
10988   std::string sval;
10989   bool sval_valid = this->string_->string_constant_value(&sval);
10990
10991   mpz_t ival;
10992   mpz_init(ival);
10993   Type* dummy;
10994   if (this->start_->integer_constant_value(true, ival, &dummy))
10995     {
10996       if (mpz_sgn(ival) < 0
10997           || (sval_valid && mpz_cmp_ui(ival, sval.length()) >= 0))
10998         {
10999           error_at(this->start_->location(), "string index out of bounds");
11000           this->set_is_error();
11001         }
11002     }
11003   if (this->end_ != NULL && !this->end_->is_nil_expression())
11004     {
11005       if (this->end_->integer_constant_value(true, ival, &dummy))
11006         {
11007           if (mpz_sgn(ival) < 0
11008               || (sval_valid && mpz_cmp_ui(ival, sval.length()) > 0))
11009             {
11010               error_at(this->end_->location(), "string index out of bounds");
11011               this->set_is_error();
11012             }
11013         }
11014     }
11015   mpz_clear(ival);
11016 }
11017
11018 // Get a tree for a string index.
11019
11020 tree
11021 String_index_expression::do_get_tree(Translate_context* context)
11022 {
11023   Location loc = this->location();
11024
11025   tree string_tree = this->string_->get_tree(context);
11026   if (string_tree == error_mark_node)
11027     return error_mark_node;
11028
11029   if (this->string_->type()->points_to() != NULL)
11030     string_tree = build_fold_indirect_ref(string_tree);
11031   if (!DECL_P(string_tree))
11032     string_tree = save_expr(string_tree);
11033   tree string_type = TREE_TYPE(string_tree);
11034
11035   tree length_tree = String_type::length_tree(context->gogo(), string_tree);
11036   length_tree = save_expr(length_tree);
11037   tree length_type = TREE_TYPE(length_tree);
11038
11039   tree bad_index = boolean_false_node;
11040
11041   tree start_tree = this->start_->get_tree(context);
11042   if (start_tree == error_mark_node)
11043     return error_mark_node;
11044   if (!DECL_P(start_tree))
11045     start_tree = save_expr(start_tree);
11046   if (!INTEGRAL_TYPE_P(TREE_TYPE(start_tree)))
11047     start_tree = convert_to_integer(length_type, start_tree);
11048
11049   bad_index = Expression::check_bounds(start_tree, length_type, bad_index,
11050                                        loc);
11051
11052   start_tree = fold_convert_loc(loc.gcc_location(), length_type, start_tree);
11053
11054   int code = (this->end_ == NULL
11055               ? RUNTIME_ERROR_STRING_INDEX_OUT_OF_BOUNDS
11056               : RUNTIME_ERROR_STRING_SLICE_OUT_OF_BOUNDS);
11057   tree crash = Gogo::runtime_error(code, loc);
11058
11059   if (this->end_ == NULL)
11060     {
11061       bad_index = fold_build2_loc(loc.gcc_location(), TRUTH_OR_EXPR,
11062                                   boolean_type_node, bad_index,
11063                                   fold_build2_loc(loc.gcc_location(), GE_EXPR,
11064                                                   boolean_type_node,
11065                                                   start_tree, length_tree));
11066
11067       tree bytes_tree = String_type::bytes_tree(context->gogo(), string_tree);
11068       tree ptr = fold_build2_loc(loc.gcc_location(), POINTER_PLUS_EXPR,
11069                                  TREE_TYPE(bytes_tree),
11070                                  bytes_tree,
11071                                  fold_convert_loc(loc.gcc_location(), sizetype,
11072                                                   start_tree));
11073       tree index = build_fold_indirect_ref_loc(loc.gcc_location(), ptr);
11074
11075       return build2(COMPOUND_EXPR, TREE_TYPE(index),
11076                     build3(COND_EXPR, void_type_node,
11077                            bad_index, crash, NULL_TREE),
11078                     index);
11079     }
11080   else
11081     {
11082       tree end_tree;
11083       if (this->end_->is_nil_expression())
11084         end_tree = build_int_cst(length_type, -1);
11085       else
11086         {
11087           end_tree = this->end_->get_tree(context);
11088           if (end_tree == error_mark_node)
11089             return error_mark_node;
11090           if (!DECL_P(end_tree))
11091             end_tree = save_expr(end_tree);
11092           if (!INTEGRAL_TYPE_P(TREE_TYPE(end_tree)))
11093             end_tree = convert_to_integer(length_type, end_tree);
11094
11095           bad_index = Expression::check_bounds(end_tree, length_type,
11096                                                bad_index, loc);
11097
11098           end_tree = fold_convert_loc(loc.gcc_location(), length_type,
11099                                       end_tree);
11100         }
11101
11102       static tree strslice_fndecl;
11103       tree ret = Gogo::call_builtin(&strslice_fndecl,
11104                                     loc,
11105                                     "__go_string_slice",
11106                                     3,
11107                                     string_type,
11108                                     string_type,
11109                                     string_tree,
11110                                     length_type,
11111                                     start_tree,
11112                                     length_type,
11113                                     end_tree);
11114       if (ret == error_mark_node)
11115         return error_mark_node;
11116       // This will panic if the bounds are out of range for the
11117       // string.
11118       TREE_NOTHROW(strslice_fndecl) = 0;
11119
11120       if (bad_index == boolean_false_node)
11121         return ret;
11122       else
11123         return build2(COMPOUND_EXPR, TREE_TYPE(ret),
11124                       build3(COND_EXPR, void_type_node,
11125                              bad_index, crash, NULL_TREE),
11126                       ret);
11127     }
11128 }
11129
11130 // Dump ast representation for a string index expression.
11131
11132 void
11133 String_index_expression::do_dump_expression(Ast_dump_context* ast_dump_context)
11134     const
11135 {
11136   Index_expression::dump_index_expression(ast_dump_context, this->string_,
11137                                           this->start_, this->end_);
11138 }
11139
11140 // Make a string index expression.  END may be NULL.
11141
11142 Expression*
11143 Expression::make_string_index(Expression* string, Expression* start,
11144                               Expression* end, Location location)
11145 {
11146   return new String_index_expression(string, start, end, location);
11147 }
11148
11149 // Class Map_index.
11150
11151 // Get the type of the map.
11152
11153 Map_type*
11154 Map_index_expression::get_map_type() const
11155 {
11156   Map_type* mt = this->map_->type()->deref()->map_type();
11157   if (mt == NULL)
11158     go_assert(saw_errors());
11159   return mt;
11160 }
11161
11162 // Map index traversal.
11163
11164 int
11165 Map_index_expression::do_traverse(Traverse* traverse)
11166 {
11167   if (Expression::traverse(&this->map_, traverse) == TRAVERSE_EXIT)
11168     return TRAVERSE_EXIT;
11169   return Expression::traverse(&this->index_, traverse);
11170 }
11171
11172 // Return the type of a map index.
11173
11174 Type*
11175 Map_index_expression::do_type()
11176 {
11177   Map_type* mt = this->get_map_type();
11178   if (mt == NULL)
11179     return Type::make_error_type();
11180   Type* type = mt->val_type();
11181   // If this map index is in a tuple assignment, we actually return a
11182   // pointer to the value type.  Tuple_map_assignment_statement is
11183   // responsible for handling this correctly.  We need to get the type
11184   // right in case this gets assigned to a temporary variable.
11185   if (this->is_in_tuple_assignment_)
11186     type = Type::make_pointer_type(type);
11187   return type;
11188 }
11189
11190 // Fix the type of a map index.
11191
11192 void
11193 Map_index_expression::do_determine_type(const Type_context*)
11194 {
11195   this->map_->determine_type_no_context();
11196   Map_type* mt = this->get_map_type();
11197   Type* key_type = mt == NULL ? NULL : mt->key_type();
11198   Type_context subcontext(key_type, false);
11199   this->index_->determine_type(&subcontext);
11200 }
11201
11202 // Check types of a map index.
11203
11204 void
11205 Map_index_expression::do_check_types(Gogo*)
11206 {
11207   std::string reason;
11208   Map_type* mt = this->get_map_type();
11209   if (mt == NULL)
11210     return;
11211   if (!Type::are_assignable(mt->key_type(), this->index_->type(), &reason))
11212     {
11213       if (reason.empty())
11214         this->report_error(_("incompatible type for map index"));
11215       else
11216         {
11217           error_at(this->location(), "incompatible type for map index (%s)",
11218                    reason.c_str());
11219           this->set_is_error();
11220         }
11221     }
11222 }
11223
11224 // Get a tree for a map index.
11225
11226 tree
11227 Map_index_expression::do_get_tree(Translate_context* context)
11228 {
11229   Map_type* type = this->get_map_type();
11230   if (type == NULL)
11231     return error_mark_node;
11232
11233   tree valptr = this->get_value_pointer(context, this->is_lvalue_);
11234   if (valptr == error_mark_node)
11235     return error_mark_node;
11236   valptr = save_expr(valptr);
11237
11238   tree val_type_tree = TREE_TYPE(TREE_TYPE(valptr));
11239
11240   if (this->is_lvalue_)
11241     return build_fold_indirect_ref(valptr);
11242   else if (this->is_in_tuple_assignment_)
11243     {
11244       // Tuple_map_assignment_statement is responsible for using this
11245       // appropriately.
11246       return valptr;
11247     }
11248   else
11249     {
11250       Gogo* gogo = context->gogo();
11251       Btype* val_btype = type->val_type()->get_backend(gogo);
11252       Bexpression* val_zero = gogo->backend()->zero_expression(val_btype);
11253       return fold_build3(COND_EXPR, val_type_tree,
11254                          fold_build2(EQ_EXPR, boolean_type_node, valptr,
11255                                      fold_convert(TREE_TYPE(valptr),
11256                                                   null_pointer_node)),
11257                          expr_to_tree(val_zero),
11258                          build_fold_indirect_ref(valptr));
11259     }
11260 }
11261
11262 // Get a tree for the map index.  This returns a tree which evaluates
11263 // to a pointer to a value.  The pointer will be NULL if the key is
11264 // not in the map.
11265
11266 tree
11267 Map_index_expression::get_value_pointer(Translate_context* context,
11268                                         bool insert)
11269 {
11270   Map_type* type = this->get_map_type();
11271   if (type == NULL)
11272     return error_mark_node;
11273
11274   tree map_tree = this->map_->get_tree(context);
11275   tree index_tree = this->index_->get_tree(context);
11276   index_tree = Expression::convert_for_assignment(context, type->key_type(),
11277                                                   this->index_->type(),
11278                                                   index_tree,
11279                                                   this->location());
11280   if (map_tree == error_mark_node || index_tree == error_mark_node)
11281     return error_mark_node;
11282
11283   if (this->map_->type()->points_to() != NULL)
11284     map_tree = build_fold_indirect_ref(map_tree);
11285
11286   // We need to pass in a pointer to the key, so stuff it into a
11287   // variable.
11288   tree tmp;
11289   tree make_tmp;
11290   if (current_function_decl != NULL)
11291     {
11292       tmp = create_tmp_var(TREE_TYPE(index_tree), get_name(index_tree));
11293       DECL_IGNORED_P(tmp) = 0;
11294       DECL_INITIAL(tmp) = index_tree;
11295       make_tmp = build1(DECL_EXPR, void_type_node, tmp);
11296       TREE_ADDRESSABLE(tmp) = 1;
11297     }
11298   else
11299     {
11300       tmp = build_decl(this->location().gcc_location(), VAR_DECL,
11301                        create_tmp_var_name("M"),
11302                        TREE_TYPE(index_tree));
11303       DECL_EXTERNAL(tmp) = 0;
11304       TREE_PUBLIC(tmp) = 0;
11305       TREE_STATIC(tmp) = 1;
11306       DECL_ARTIFICIAL(tmp) = 1;
11307       if (!TREE_CONSTANT(index_tree))
11308         make_tmp = fold_build2_loc(this->location().gcc_location(),
11309                                    INIT_EXPR, void_type_node,
11310                                    tmp, index_tree);
11311       else
11312         {
11313           TREE_READONLY(tmp) = 1;
11314           TREE_CONSTANT(tmp) = 1;
11315           DECL_INITIAL(tmp) = index_tree;
11316           make_tmp = NULL_TREE;
11317         }
11318       rest_of_decl_compilation(tmp, 1, 0);
11319     }
11320   tree tmpref =
11321     fold_convert_loc(this->location().gcc_location(), const_ptr_type_node,
11322                      build_fold_addr_expr_loc(this->location().gcc_location(),
11323                                               tmp));
11324
11325   static tree map_index_fndecl;
11326   tree call = Gogo::call_builtin(&map_index_fndecl,
11327                                  this->location(),
11328                                  "__go_map_index",
11329                                  3,
11330                                  const_ptr_type_node,
11331                                  TREE_TYPE(map_tree),
11332                                  map_tree,
11333                                  const_ptr_type_node,
11334                                  tmpref,
11335                                  boolean_type_node,
11336                                  (insert
11337                                   ? boolean_true_node
11338                                   : boolean_false_node));
11339   if (call == error_mark_node)
11340     return error_mark_node;
11341   // This can panic on a map of interface type if the interface holds
11342   // an uncomparable or unhashable type.
11343   TREE_NOTHROW(map_index_fndecl) = 0;
11344
11345   Type* val_type = type->val_type();
11346   tree val_type_tree = type_to_tree(val_type->get_backend(context->gogo()));
11347   if (val_type_tree == error_mark_node)
11348     return error_mark_node;
11349   tree ptr_val_type_tree = build_pointer_type(val_type_tree);
11350
11351   tree ret = fold_convert_loc(this->location().gcc_location(),
11352                               ptr_val_type_tree, call);
11353   if (make_tmp != NULL_TREE)
11354     ret = build2(COMPOUND_EXPR, ptr_val_type_tree, make_tmp, ret);
11355   return ret;
11356 }
11357
11358 // Dump ast representation for a map index expression
11359
11360 void
11361 Map_index_expression::do_dump_expression(Ast_dump_context* ast_dump_context)
11362     const
11363 {
11364   Index_expression::dump_index_expression(ast_dump_context,
11365                                           this->map_, this->index_, NULL);
11366 }
11367
11368 // Make a map index expression.
11369
11370 Map_index_expression*
11371 Expression::make_map_index(Expression* map, Expression* index,
11372                            Location location)
11373 {
11374   return new Map_index_expression(map, index, location);
11375 }
11376
11377 // Class Field_reference_expression.
11378
11379 // Return the type of a field reference.
11380
11381 Type*
11382 Field_reference_expression::do_type()
11383 {
11384   Type* type = this->expr_->type();
11385   if (type->is_error())
11386     return type;
11387   Struct_type* struct_type = type->struct_type();
11388   go_assert(struct_type != NULL);
11389   return struct_type->field(this->field_index_)->type();
11390 }
11391
11392 // Check the types for a field reference.
11393
11394 void
11395 Field_reference_expression::do_check_types(Gogo*)
11396 {
11397   Type* type = this->expr_->type();
11398   if (type->is_error())
11399     return;
11400   Struct_type* struct_type = type->struct_type();
11401   go_assert(struct_type != NULL);
11402   go_assert(struct_type->field(this->field_index_) != NULL);
11403 }
11404
11405 // Get a tree for a field reference.
11406
11407 tree
11408 Field_reference_expression::do_get_tree(Translate_context* context)
11409 {
11410   tree struct_tree = this->expr_->get_tree(context);
11411   if (struct_tree == error_mark_node
11412       || TREE_TYPE(struct_tree) == error_mark_node)
11413     return error_mark_node;
11414   go_assert(TREE_CODE(TREE_TYPE(struct_tree)) == RECORD_TYPE);
11415   tree field = TYPE_FIELDS(TREE_TYPE(struct_tree));
11416   if (field == NULL_TREE)
11417     {
11418       // This can happen for a type which refers to itself indirectly
11419       // and then turns out to be erroneous.
11420       go_assert(saw_errors());
11421       return error_mark_node;
11422     }
11423   for (unsigned int i = this->field_index_; i > 0; --i)
11424     {
11425       field = DECL_CHAIN(field);
11426       go_assert(field != NULL_TREE);
11427     }
11428   if (TREE_TYPE(field) == error_mark_node)
11429     return error_mark_node;
11430   return build3(COMPONENT_REF, TREE_TYPE(field), struct_tree, field,
11431                 NULL_TREE);
11432 }
11433
11434 // Dump ast representation for a field reference expression.
11435
11436 void
11437 Field_reference_expression::do_dump_expression(
11438     Ast_dump_context* ast_dump_context) const
11439 {
11440   this->expr_->dump_expression(ast_dump_context);
11441   ast_dump_context->ostream() << "." <<  this->field_index_;
11442 }
11443
11444 // Make a reference to a qualified identifier in an expression.
11445
11446 Field_reference_expression*
11447 Expression::make_field_reference(Expression* expr, unsigned int field_index,
11448                                  Location location)
11449 {
11450   return new Field_reference_expression(expr, field_index, location);
11451 }
11452
11453 // Class Interface_field_reference_expression.
11454
11455 // Return a tree for the pointer to the function to call.
11456
11457 tree
11458 Interface_field_reference_expression::get_function_tree(Translate_context*,
11459                                                         tree expr)
11460 {
11461   if (this->expr_->type()->points_to() != NULL)
11462     expr = build_fold_indirect_ref(expr);
11463
11464   tree expr_type = TREE_TYPE(expr);
11465   go_assert(TREE_CODE(expr_type) == RECORD_TYPE);
11466
11467   tree field = TYPE_FIELDS(expr_type);
11468   go_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__methods") == 0);
11469
11470   tree table = build3(COMPONENT_REF, TREE_TYPE(field), expr, field, NULL_TREE);
11471   go_assert(POINTER_TYPE_P(TREE_TYPE(table)));
11472
11473   table = build_fold_indirect_ref(table);
11474   go_assert(TREE_CODE(TREE_TYPE(table)) == RECORD_TYPE);
11475
11476   std::string name = Gogo::unpack_hidden_name(this->name_);
11477   for (field = DECL_CHAIN(TYPE_FIELDS(TREE_TYPE(table)));
11478        field != NULL_TREE;
11479        field = DECL_CHAIN(field))
11480     {
11481       if (name == IDENTIFIER_POINTER(DECL_NAME(field)))
11482         break;
11483     }
11484   go_assert(field != NULL_TREE);
11485
11486   return build3(COMPONENT_REF, TREE_TYPE(field), table, field, NULL_TREE);
11487 }
11488
11489 // Return a tree for the first argument to pass to the interface
11490 // function.
11491
11492 tree
11493 Interface_field_reference_expression::get_underlying_object_tree(
11494     Translate_context*,
11495     tree expr)
11496 {
11497   if (this->expr_->type()->points_to() != NULL)
11498     expr = build_fold_indirect_ref(expr);
11499
11500   tree expr_type = TREE_TYPE(expr);
11501   go_assert(TREE_CODE(expr_type) == RECORD_TYPE);
11502
11503   tree field = DECL_CHAIN(TYPE_FIELDS(expr_type));
11504   go_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__object") == 0);
11505
11506   return build3(COMPONENT_REF, TREE_TYPE(field), expr, field, NULL_TREE);
11507 }
11508
11509 // Traversal.
11510
11511 int
11512 Interface_field_reference_expression::do_traverse(Traverse* traverse)
11513 {
11514   return Expression::traverse(&this->expr_, traverse);
11515 }
11516
11517 // Return the type of an interface field reference.
11518
11519 Type*
11520 Interface_field_reference_expression::do_type()
11521 {
11522   Type* expr_type = this->expr_->type();
11523
11524   Type* points_to = expr_type->points_to();
11525   if (points_to != NULL)
11526     expr_type = points_to;
11527
11528   Interface_type* interface_type = expr_type->interface_type();
11529   if (interface_type == NULL)
11530     return Type::make_error_type();
11531
11532   const Typed_identifier* method = interface_type->find_method(this->name_);
11533   if (method == NULL)
11534     return Type::make_error_type();
11535
11536   return method->type();
11537 }
11538
11539 // Determine types.
11540
11541 void
11542 Interface_field_reference_expression::do_determine_type(const Type_context*)
11543 {
11544   this->expr_->determine_type_no_context();
11545 }
11546
11547 // Check the types for an interface field reference.
11548
11549 void
11550 Interface_field_reference_expression::do_check_types(Gogo*)
11551 {
11552   Type* type = this->expr_->type();
11553
11554   Type* points_to = type->points_to();
11555   if (points_to != NULL)
11556     type = points_to;
11557
11558   Interface_type* interface_type = type->interface_type();
11559   if (interface_type == NULL)
11560     {
11561       if (!type->is_error_type())
11562         this->report_error(_("expected interface or pointer to interface"));
11563     }
11564   else
11565     {
11566       const Typed_identifier* method =
11567         interface_type->find_method(this->name_);
11568       if (method == NULL)
11569         {
11570           error_at(this->location(), "method %qs not in interface",
11571                    Gogo::message_name(this->name_).c_str());
11572           this->set_is_error();
11573         }
11574     }
11575 }
11576
11577 // Get a tree for a reference to a field in an interface.  There is no
11578 // standard tree type representation for this: it's a function
11579 // attached to its first argument, like a Bound_method_expression.
11580 // The only places it may currently be used are in a Call_expression
11581 // or a Go_statement, which will take it apart directly.  So this has
11582 // nothing to do at present.
11583
11584 tree
11585 Interface_field_reference_expression::do_get_tree(Translate_context*)
11586 {
11587   go_unreachable();
11588 }
11589
11590 // Dump ast representation for an interface field reference.
11591
11592 void
11593 Interface_field_reference_expression::do_dump_expression(
11594     Ast_dump_context* ast_dump_context) const
11595 {
11596   this->expr_->dump_expression(ast_dump_context);
11597   ast_dump_context->ostream() << "." << this->name_;
11598 }
11599
11600 // Make a reference to a field in an interface.
11601
11602 Expression*
11603 Expression::make_interface_field_reference(Expression* expr,
11604                                            const std::string& field,
11605                                            Location location)
11606 {
11607   return new Interface_field_reference_expression(expr, field, location);
11608 }
11609
11610 // A general selector.  This is a Parser_expression for LEFT.NAME.  It
11611 // is lowered after we know the type of the left hand side.
11612
11613 class Selector_expression : public Parser_expression
11614 {
11615  public:
11616   Selector_expression(Expression* left, const std::string& name,
11617                       Location location)
11618     : Parser_expression(EXPRESSION_SELECTOR, location),
11619       left_(left), name_(name)
11620   { }
11621
11622  protected:
11623   int
11624   do_traverse(Traverse* traverse)
11625   { return Expression::traverse(&this->left_, traverse); }
11626
11627   Expression*
11628   do_lower(Gogo*, Named_object*, Statement_inserter*, int);
11629
11630   Expression*
11631   do_copy()
11632   {
11633     return new Selector_expression(this->left_->copy(), this->name_,
11634                                    this->location());
11635   }
11636
11637   void
11638   do_dump_expression(Ast_dump_context* ast_dump_context) const;
11639
11640  private:
11641   Expression*
11642   lower_method_expression(Gogo*);
11643
11644   // The expression on the left hand side.
11645   Expression* left_;
11646   // The name on the right hand side.
11647   std::string name_;
11648 };
11649
11650 // Lower a selector expression once we know the real type of the left
11651 // hand side.
11652
11653 Expression*
11654 Selector_expression::do_lower(Gogo* gogo, Named_object*, Statement_inserter*,
11655                               int)
11656 {
11657   Expression* left = this->left_;
11658   if (left->is_type_expression())
11659     return this->lower_method_expression(gogo);
11660   return Type::bind_field_or_method(gogo, left->type(), left, this->name_,
11661                                     this->location());
11662 }
11663
11664 // Lower a method expression T.M or (*T).M.  We turn this into a
11665 // function literal.
11666
11667 Expression*
11668 Selector_expression::lower_method_expression(Gogo* gogo)
11669 {
11670   Location location = this->location();
11671   Type* type = this->left_->type();
11672   const std::string& name(this->name_);
11673
11674   bool is_pointer;
11675   if (type->points_to() == NULL)
11676     is_pointer = false;
11677   else
11678     {
11679       is_pointer = true;
11680       type = type->points_to();
11681     }
11682   Named_type* nt = type->named_type();
11683   if (nt == NULL)
11684     {
11685       error_at(location,
11686                ("method expression requires named type or "
11687                 "pointer to named type"));
11688       return Expression::make_error(location);
11689     }
11690
11691   bool is_ambiguous;
11692   Method* method = nt->method_function(name, &is_ambiguous);
11693   const Typed_identifier* imethod = NULL;
11694   if (method == NULL && !is_pointer)
11695     {
11696       Interface_type* it = nt->interface_type();
11697       if (it != NULL)
11698         imethod = it->find_method(name);
11699     }
11700
11701   if (method == NULL && imethod == NULL)
11702     {
11703       if (!is_ambiguous)
11704         error_at(location, "type %<%s%s%> has no method %<%s%>",
11705                  is_pointer ? "*" : "",
11706                  nt->message_name().c_str(),
11707                  Gogo::message_name(name).c_str());
11708       else
11709         error_at(location, "method %<%s%s%> is ambiguous in type %<%s%>",
11710                  Gogo::message_name(name).c_str(),
11711                  is_pointer ? "*" : "",
11712                  nt->message_name().c_str());
11713       return Expression::make_error(location);
11714     }
11715
11716   if (method != NULL && !is_pointer && !method->is_value_method())
11717     {
11718       error_at(location, "method requires pointer (use %<(*%s).%s)%>",
11719                nt->message_name().c_str(),
11720                Gogo::message_name(name).c_str());
11721       return Expression::make_error(location);
11722     }
11723
11724   // Build a new function type in which the receiver becomes the first
11725   // argument.
11726   Function_type* method_type;
11727   if (method != NULL)
11728     {
11729       method_type = method->type();
11730       go_assert(method_type->is_method());
11731     }
11732   else
11733     {
11734       method_type = imethod->type()->function_type();
11735       go_assert(method_type != NULL && !method_type->is_method());
11736     }
11737
11738   const char* const receiver_name = "$this";
11739   Typed_identifier_list* parameters = new Typed_identifier_list();
11740   parameters->push_back(Typed_identifier(receiver_name, this->left_->type(),
11741                                          location));
11742
11743   const Typed_identifier_list* method_parameters = method_type->parameters();
11744   if (method_parameters != NULL)
11745     {
11746       int i = 0;
11747       for (Typed_identifier_list::const_iterator p = method_parameters->begin();
11748            p != method_parameters->end();
11749            ++p, ++i)
11750         {
11751           if (!p->name().empty() && p->name() != Import::import_marker)
11752             parameters->push_back(*p);
11753           else
11754             {
11755               char buf[20];
11756               snprintf(buf, sizeof buf, "$param%d", i);
11757               parameters->push_back(Typed_identifier(buf, p->type(),
11758                                                      p->location()));
11759             }
11760         }
11761     }
11762
11763   const Typed_identifier_list* method_results = method_type->results();
11764   Typed_identifier_list* results;
11765   if (method_results == NULL)
11766     results = NULL;
11767   else
11768     {
11769       results = new Typed_identifier_list();
11770       for (Typed_identifier_list::const_iterator p = method_results->begin();
11771            p != method_results->end();
11772            ++p)
11773         results->push_back(*p);
11774     }
11775
11776   Function_type* fntype = Type::make_function_type(NULL, parameters, results,
11777                                                    location);
11778   if (method_type->is_varargs())
11779     fntype->set_is_varargs();
11780
11781   // We generate methods which always takes a pointer to the receiver
11782   // as their first argument.  If this is for a pointer type, we can
11783   // simply reuse the existing function.  We use an internal hack to
11784   // get the right type.
11785
11786   if (method != NULL && is_pointer)
11787     {
11788       Named_object* mno = (method->needs_stub_method()
11789                            ? method->stub_object()
11790                            : method->named_object());
11791       Expression* f = Expression::make_func_reference(mno, NULL, location);
11792       f = Expression::make_cast(fntype, f, location);
11793       Type_conversion_expression* tce =
11794         static_cast<Type_conversion_expression*>(f);
11795       tce->set_may_convert_function_types();
11796       return f;
11797     }
11798
11799   Named_object* no = gogo->start_function(Gogo::thunk_name(), fntype, false,
11800                                           location);
11801
11802   Named_object* vno = gogo->lookup(receiver_name, NULL);
11803   go_assert(vno != NULL);
11804   Expression* ve = Expression::make_var_reference(vno, location);
11805   Expression* bm;
11806   if (method != NULL)
11807     bm = Type::bind_field_or_method(gogo, nt, ve, name, location);
11808   else
11809     bm = Expression::make_interface_field_reference(ve, name, location);
11810
11811   // Even though we found the method above, if it has an error type we
11812   // may see an error here.
11813   if (bm->is_error_expression())
11814     {
11815       gogo->finish_function(location);
11816       return bm;
11817     }
11818
11819   Expression_list* args;
11820   if (parameters->size() <= 1)
11821     args = NULL;
11822   else
11823     {
11824       args = new Expression_list();
11825       Typed_identifier_list::const_iterator p = parameters->begin();
11826       ++p;
11827       for (; p != parameters->end(); ++p)
11828         {
11829           vno = gogo->lookup(p->name(), NULL);
11830           go_assert(vno != NULL);
11831           args->push_back(Expression::make_var_reference(vno, location));
11832         }
11833     }
11834
11835   gogo->start_block(location);
11836
11837   Call_expression* call = Expression::make_call(bm, args,
11838                                                 method_type->is_varargs(),
11839                                                 location);
11840
11841   size_t count = call->result_count();
11842   Statement* s;
11843   if (count == 0)
11844     s = Statement::make_statement(call, true);
11845   else
11846     {
11847       Expression_list* retvals = new Expression_list();
11848       if (count <= 1)
11849         retvals->push_back(call);
11850       else
11851         {
11852           for (size_t i = 0; i < count; ++i)
11853             retvals->push_back(Expression::make_call_result(call, i));
11854         }
11855       s = Statement::make_return_statement(retvals, location);
11856     }
11857   gogo->add_statement(s);
11858
11859   Block* b = gogo->finish_block(location);
11860
11861   gogo->add_block(b, location);
11862
11863   // Lower the call in case there are multiple results.
11864   gogo->lower_block(no, b);
11865
11866   gogo->finish_function(location);
11867
11868   return Expression::make_func_reference(no, NULL, location);
11869 }
11870
11871 // Dump the ast for a selector expression.
11872
11873 void
11874 Selector_expression::do_dump_expression(Ast_dump_context* ast_dump_context)
11875     const
11876 {
11877   ast_dump_context->dump_expression(this->left_);
11878   ast_dump_context->ostream() << ".";
11879   ast_dump_context->ostream() << this->name_;
11880 }
11881
11882 // Make a selector expression.
11883
11884 Expression*
11885 Expression::make_selector(Expression* left, const std::string& name,
11886                           Location location)
11887 {
11888   return new Selector_expression(left, name, location);
11889 }
11890
11891 // Implement the builtin function new.
11892
11893 class Allocation_expression : public Expression
11894 {
11895  public:
11896   Allocation_expression(Type* type, Location location)
11897     : Expression(EXPRESSION_ALLOCATION, location),
11898       type_(type)
11899   { }
11900
11901  protected:
11902   int
11903   do_traverse(Traverse* traverse)
11904   { return Type::traverse(this->type_, traverse); }
11905
11906   Type*
11907   do_type()
11908   { return Type::make_pointer_type(this->type_); }
11909
11910   void
11911   do_determine_type(const Type_context*)
11912   { }
11913
11914   Expression*
11915   do_copy()
11916   { return new Allocation_expression(this->type_, this->location()); }
11917
11918   tree
11919   do_get_tree(Translate_context*);
11920
11921   void
11922   do_dump_expression(Ast_dump_context*) const;
11923
11924  private:
11925   // The type we are allocating.
11926   Type* type_;
11927 };
11928
11929 // Return a tree for an allocation expression.
11930
11931 tree
11932 Allocation_expression::do_get_tree(Translate_context* context)
11933 {
11934   tree type_tree = type_to_tree(this->type_->get_backend(context->gogo()));
11935   if (type_tree == error_mark_node)
11936     return error_mark_node;
11937   tree size_tree = TYPE_SIZE_UNIT(type_tree);
11938   tree space = context->gogo()->allocate_memory(this->type_, size_tree,
11939                                                 this->location());
11940   if (space == error_mark_node)
11941     return error_mark_node;
11942   return fold_convert(build_pointer_type(type_tree), space);
11943 }
11944
11945 // Dump ast representation for an allocation expression.
11946
11947 void
11948 Allocation_expression::do_dump_expression(Ast_dump_context* ast_dump_context)
11949     const
11950 {
11951   ast_dump_context->ostream() << "new(";
11952   ast_dump_context->dump_type(this->type_);
11953   ast_dump_context->ostream() << ")";
11954 }
11955
11956 // Make an allocation expression.
11957
11958 Expression*
11959 Expression::make_allocation(Type* type, Location location)
11960 {
11961   return new Allocation_expression(type, location);
11962 }
11963
11964 // Construct a struct.
11965
11966 class Struct_construction_expression : public Expression
11967 {
11968  public:
11969   Struct_construction_expression(Type* type, Expression_list* vals,
11970                                  Location location)
11971     : Expression(EXPRESSION_STRUCT_CONSTRUCTION, location),
11972       type_(type), vals_(vals)
11973   { }
11974
11975   // Return whether this is a constant initializer.
11976   bool
11977   is_constant_struct() const;
11978
11979  protected:
11980   int
11981   do_traverse(Traverse* traverse);
11982
11983   Type*
11984   do_type()
11985   { return this->type_; }
11986
11987   void
11988   do_determine_type(const Type_context*);
11989
11990   void
11991   do_check_types(Gogo*);
11992
11993   Expression*
11994   do_copy()
11995   {
11996     return new Struct_construction_expression(this->type_, this->vals_->copy(),
11997                                               this->location());
11998   }
11999
12000   tree
12001   do_get_tree(Translate_context*);
12002
12003   void
12004   do_export(Export*) const;
12005
12006   void
12007   do_dump_expression(Ast_dump_context*) const;
12008
12009  private:
12010   // The type of the struct to construct.
12011   Type* type_;
12012   // The list of values, in order of the fields in the struct.  A NULL
12013   // entry means that the field should be zero-initialized.
12014   Expression_list* vals_;
12015 };
12016
12017 // Traversal.
12018
12019 int
12020 Struct_construction_expression::do_traverse(Traverse* traverse)
12021 {
12022   if (this->vals_ != NULL
12023       && this->vals_->traverse(traverse) == TRAVERSE_EXIT)
12024     return TRAVERSE_EXIT;
12025   if (Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
12026     return TRAVERSE_EXIT;
12027   return TRAVERSE_CONTINUE;
12028 }
12029
12030 // Return whether this is a constant initializer.
12031
12032 bool
12033 Struct_construction_expression::is_constant_struct() const
12034 {
12035   if (this->vals_ == NULL)
12036     return true;
12037   for (Expression_list::const_iterator pv = this->vals_->begin();
12038        pv != this->vals_->end();
12039        ++pv)
12040     {
12041       if (*pv != NULL
12042           && !(*pv)->is_constant()
12043           && (!(*pv)->is_composite_literal()
12044               || (*pv)->is_nonconstant_composite_literal()))
12045         return false;
12046     }
12047
12048   const Struct_field_list* fields = this->type_->struct_type()->fields();
12049   for (Struct_field_list::const_iterator pf = fields->begin();
12050        pf != fields->end();
12051        ++pf)
12052     {
12053       // There are no constant constructors for interfaces.
12054       if (pf->type()->interface_type() != NULL)
12055         return false;
12056     }
12057
12058   return true;
12059 }
12060
12061 // Final type determination.
12062
12063 void
12064 Struct_construction_expression::do_determine_type(const Type_context*)
12065 {
12066   if (this->vals_ == NULL)
12067     return;
12068   const Struct_field_list* fields = this->type_->struct_type()->fields();
12069   Expression_list::const_iterator pv = this->vals_->begin();
12070   for (Struct_field_list::const_iterator pf = fields->begin();
12071        pf != fields->end();
12072        ++pf, ++pv)
12073     {
12074       if (pv == this->vals_->end())
12075         return;
12076       if (*pv != NULL)
12077         {
12078           Type_context subcontext(pf->type(), false);
12079           (*pv)->determine_type(&subcontext);
12080         }
12081     }
12082   // Extra values are an error we will report elsewhere; we still want
12083   // to determine the type to avoid knockon errors.
12084   for (; pv != this->vals_->end(); ++pv)
12085     (*pv)->determine_type_no_context();
12086 }
12087
12088 // Check types.
12089
12090 void
12091 Struct_construction_expression::do_check_types(Gogo*)
12092 {
12093   if (this->vals_ == NULL)
12094     return;
12095
12096   Struct_type* st = this->type_->struct_type();
12097   if (this->vals_->size() > st->field_count())
12098     {
12099       this->report_error(_("too many expressions for struct"));
12100       return;
12101     }
12102
12103   const Struct_field_list* fields = st->fields();
12104   Expression_list::const_iterator pv = this->vals_->begin();
12105   int i = 0;
12106   for (Struct_field_list::const_iterator pf = fields->begin();
12107        pf != fields->end();
12108        ++pf, ++pv, ++i)
12109     {
12110       if (pv == this->vals_->end())
12111         {
12112           this->report_error(_("too few expressions for struct"));
12113           break;
12114         }
12115
12116       if (*pv == NULL)
12117         continue;
12118
12119       std::string reason;
12120       if (!Type::are_assignable(pf->type(), (*pv)->type(), &reason))
12121         {
12122           if (reason.empty())
12123             error_at((*pv)->location(),
12124                      "incompatible type for field %d in struct construction",
12125                      i + 1);
12126           else
12127             error_at((*pv)->location(),
12128                      ("incompatible type for field %d in "
12129                       "struct construction (%s)"),
12130                      i + 1, reason.c_str());
12131           this->set_is_error();
12132         }
12133     }
12134   go_assert(pv == this->vals_->end());
12135 }
12136
12137 // Return a tree for constructing a struct.
12138
12139 tree
12140 Struct_construction_expression::do_get_tree(Translate_context* context)
12141 {
12142   Gogo* gogo = context->gogo();
12143
12144   if (this->vals_ == NULL)
12145     {
12146       Btype* btype = this->type_->get_backend(gogo);
12147       return expr_to_tree(gogo->backend()->zero_expression(btype));
12148     }
12149
12150   tree type_tree = type_to_tree(this->type_->get_backend(gogo));
12151   if (type_tree == error_mark_node)
12152     return error_mark_node;
12153   go_assert(TREE_CODE(type_tree) == RECORD_TYPE);
12154
12155   bool is_constant = true;
12156   const Struct_field_list* fields = this->type_->struct_type()->fields();
12157   VEC(constructor_elt,gc)* elts = VEC_alloc(constructor_elt, gc,
12158                                             fields->size());
12159   Struct_field_list::const_iterator pf = fields->begin();
12160   Expression_list::const_iterator pv = this->vals_->begin();
12161   for (tree field = TYPE_FIELDS(type_tree);
12162        field != NULL_TREE;
12163        field = DECL_CHAIN(field), ++pf)
12164     {
12165       go_assert(pf != fields->end());
12166
12167       Btype* fbtype = pf->type()->get_backend(gogo);
12168
12169       tree val;
12170       if (pv == this->vals_->end())
12171         val = expr_to_tree(gogo->backend()->zero_expression(fbtype));
12172       else if (*pv == NULL)
12173         {
12174           val = expr_to_tree(gogo->backend()->zero_expression(fbtype));
12175           ++pv;
12176         }
12177       else
12178         {
12179           val = Expression::convert_for_assignment(context, pf->type(),
12180                                                    (*pv)->type(),
12181                                                    (*pv)->get_tree(context),
12182                                                    this->location());
12183           ++pv;
12184         }
12185
12186       if (val == error_mark_node || TREE_TYPE(val) == error_mark_node)
12187         return error_mark_node;
12188
12189       constructor_elt* elt = VEC_quick_push(constructor_elt, elts, NULL);
12190       elt->index = field;
12191       elt->value = val;
12192       if (!TREE_CONSTANT(val))
12193         is_constant = false;
12194     }
12195   go_assert(pf == fields->end());
12196
12197   tree ret = build_constructor(type_tree, elts);
12198   if (is_constant)
12199     TREE_CONSTANT(ret) = 1;
12200   return ret;
12201 }
12202
12203 // Export a struct construction.
12204
12205 void
12206 Struct_construction_expression::do_export(Export* exp) const
12207 {
12208   exp->write_c_string("convert(");
12209   exp->write_type(this->type_);
12210   for (Expression_list::const_iterator pv = this->vals_->begin();
12211        pv != this->vals_->end();
12212        ++pv)
12213     {
12214       exp->write_c_string(", ");
12215       if (*pv != NULL)
12216         (*pv)->export_expression(exp);
12217     }
12218   exp->write_c_string(")");
12219 }
12220
12221 // Dump ast representation of a struct construction expression.
12222
12223 void
12224 Struct_construction_expression::do_dump_expression(
12225     Ast_dump_context* ast_dump_context) const
12226 {
12227   ast_dump_context->dump_type(this->type_);
12228   ast_dump_context->ostream() << "{";
12229   ast_dump_context->dump_expression_list(this->vals_);
12230   ast_dump_context->ostream() << "}";
12231 }
12232
12233 // Make a struct composite literal.  This used by the thunk code.
12234
12235 Expression*
12236 Expression::make_struct_composite_literal(Type* type, Expression_list* vals,
12237                                           Location location)
12238 {
12239   go_assert(type->struct_type() != NULL);
12240   return new Struct_construction_expression(type, vals, location);
12241 }
12242
12243 // Construct an array.  This class is not used directly; instead we
12244 // use the child classes, Fixed_array_construction_expression and
12245 // Open_array_construction_expression.
12246
12247 class Array_construction_expression : public Expression
12248 {
12249  protected:
12250   Array_construction_expression(Expression_classification classification,
12251                                 Type* type, Expression_list* vals,
12252                                 Location location)
12253     : Expression(classification, location),
12254       type_(type), vals_(vals)
12255   { }
12256
12257  public:
12258   // Return whether this is a constant initializer.
12259   bool
12260   is_constant_array() const;
12261
12262   // Return the number of elements.
12263   size_t
12264   element_count() const
12265   { return this->vals_ == NULL ? 0 : this->vals_->size(); }
12266
12267 protected:
12268   int
12269   do_traverse(Traverse* traverse);
12270
12271   Type*
12272   do_type()
12273   { return this->type_; }
12274
12275   void
12276   do_determine_type(const Type_context*);
12277
12278   void
12279   do_check_types(Gogo*);
12280
12281   void
12282   do_export(Export*) const;
12283
12284   // The list of values.
12285   Expression_list*
12286   vals()
12287   { return this->vals_; }
12288
12289   // Get a constructor tree for the array values.
12290   tree
12291   get_constructor_tree(Translate_context* context, tree type_tree);
12292
12293   void
12294   do_dump_expression(Ast_dump_context*) const;
12295
12296  private:
12297   // The type of the array to construct.
12298   Type* type_;
12299   // The list of values.
12300   Expression_list* vals_;
12301 };
12302
12303 // Traversal.
12304
12305 int
12306 Array_construction_expression::do_traverse(Traverse* traverse)
12307 {
12308   if (this->vals_ != NULL
12309       && this->vals_->traverse(traverse) == TRAVERSE_EXIT)
12310     return TRAVERSE_EXIT;
12311   if (Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
12312     return TRAVERSE_EXIT;
12313   return TRAVERSE_CONTINUE;
12314 }
12315
12316 // Return whether this is a constant initializer.
12317
12318 bool
12319 Array_construction_expression::is_constant_array() const
12320 {
12321   if (this->vals_ == NULL)
12322     return true;
12323
12324   // There are no constant constructors for interfaces.
12325   if (this->type_->array_type()->element_type()->interface_type() != NULL)
12326     return false;
12327
12328   for (Expression_list::const_iterator pv = this->vals_->begin();
12329        pv != this->vals_->end();
12330        ++pv)
12331     {
12332       if (*pv != NULL
12333           && !(*pv)->is_constant()
12334           && (!(*pv)->is_composite_literal()
12335               || (*pv)->is_nonconstant_composite_literal()))
12336         return false;
12337     }
12338   return true;
12339 }
12340
12341 // Final type determination.
12342
12343 void
12344 Array_construction_expression::do_determine_type(const Type_context*)
12345 {
12346   if (this->vals_ == NULL)
12347     return;
12348   Type_context subcontext(this->type_->array_type()->element_type(), false);
12349   for (Expression_list::const_iterator pv = this->vals_->begin();
12350        pv != this->vals_->end();
12351        ++pv)
12352     {
12353       if (*pv != NULL)
12354         (*pv)->determine_type(&subcontext);
12355     }
12356 }
12357
12358 // Check types.
12359
12360 void
12361 Array_construction_expression::do_check_types(Gogo*)
12362 {
12363   if (this->vals_ == NULL)
12364     return;
12365
12366   Array_type* at = this->type_->array_type();
12367   int i = 0;
12368   Type* element_type = at->element_type();
12369   for (Expression_list::const_iterator pv = this->vals_->begin();
12370        pv != this->vals_->end();
12371        ++pv, ++i)
12372     {
12373       if (*pv != NULL
12374           && !Type::are_assignable(element_type, (*pv)->type(), NULL))
12375         {
12376           error_at((*pv)->location(),
12377                    "incompatible type for element %d in composite literal",
12378                    i + 1);
12379           this->set_is_error();
12380         }
12381     }
12382
12383   Expression* length = at->length();
12384   if (length != NULL && !length->is_error_expression())
12385     {
12386       mpz_t val;
12387       mpz_init(val);
12388       Type* type;
12389       if (at->length()->integer_constant_value(true, val, &type))
12390         {
12391           if (this->vals_->size() > mpz_get_ui(val))
12392             this->report_error(_("too many elements in composite literal"));
12393         }
12394       mpz_clear(val);
12395     }
12396 }
12397
12398 // Get a constructor tree for the array values.
12399
12400 tree
12401 Array_construction_expression::get_constructor_tree(Translate_context* context,
12402                                                     tree type_tree)
12403 {
12404   VEC(constructor_elt,gc)* values = VEC_alloc(constructor_elt, gc,
12405                                               (this->vals_ == NULL
12406                                                ? 0
12407                                                : this->vals_->size()));
12408   Type* element_type = this->type_->array_type()->element_type();
12409   bool is_constant = true;
12410   if (this->vals_ != NULL)
12411     {
12412       size_t i = 0;
12413       for (Expression_list::const_iterator pv = this->vals_->begin();
12414            pv != this->vals_->end();
12415            ++pv, ++i)
12416         {
12417           constructor_elt* elt = VEC_quick_push(constructor_elt, values, NULL);
12418           elt->index = size_int(i);
12419           if (*pv == NULL)
12420             {
12421               Gogo* gogo = context->gogo();
12422               Btype* ebtype = element_type->get_backend(gogo);
12423               Bexpression *zv = gogo->backend()->zero_expression(ebtype);
12424               elt->value = expr_to_tree(zv);
12425             }
12426           else
12427             {
12428               tree value_tree = (*pv)->get_tree(context);
12429               elt->value = Expression::convert_for_assignment(context,
12430                                                               element_type,
12431                                                               (*pv)->type(),
12432                                                               value_tree,
12433                                                               this->location());
12434             }
12435           if (elt->value == error_mark_node)
12436             return error_mark_node;
12437           if (!TREE_CONSTANT(elt->value))
12438             is_constant = false;
12439         }
12440     }
12441
12442   tree ret = build_constructor(type_tree, values);
12443   if (is_constant)
12444     TREE_CONSTANT(ret) = 1;
12445   return ret;
12446 }
12447
12448 // Export an array construction.
12449
12450 void
12451 Array_construction_expression::do_export(Export* exp) const
12452 {
12453   exp->write_c_string("convert(");
12454   exp->write_type(this->type_);
12455   if (this->vals_ != NULL)
12456     {
12457       for (Expression_list::const_iterator pv = this->vals_->begin();
12458            pv != this->vals_->end();
12459            ++pv)
12460         {
12461           exp->write_c_string(", ");
12462           if (*pv != NULL)
12463             (*pv)->export_expression(exp);
12464         }
12465     }
12466   exp->write_c_string(")");
12467 }
12468
12469 // Dump ast representation of an array construction expressin.
12470
12471 void
12472 Array_construction_expression::do_dump_expression(
12473     Ast_dump_context* ast_dump_context) const
12474 {
12475   Expression* length = this->type_->array_type() != NULL ?
12476                          this->type_->array_type()->length() : NULL;
12477
12478   ast_dump_context->ostream() << "[" ;
12479   if (length != NULL)
12480     {
12481       ast_dump_context->dump_expression(length);
12482     }
12483   ast_dump_context->ostream() << "]" ;
12484   ast_dump_context->dump_type(this->type_);
12485   ast_dump_context->ostream() << "{" ;
12486   ast_dump_context->dump_expression_list(this->vals_);
12487   ast_dump_context->ostream() << "}" ;
12488
12489 }
12490
12491 // Construct a fixed array.
12492
12493 class Fixed_array_construction_expression :
12494   public Array_construction_expression
12495 {
12496  public:
12497   Fixed_array_construction_expression(Type* type, Expression_list* vals,
12498                                       Location location)
12499     : Array_construction_expression(EXPRESSION_FIXED_ARRAY_CONSTRUCTION,
12500                                     type, vals, location)
12501   {
12502     go_assert(type->array_type() != NULL
12503                && type->array_type()->length() != NULL);
12504   }
12505
12506  protected:
12507   Expression*
12508   do_copy()
12509   {
12510     return new Fixed_array_construction_expression(this->type(),
12511                                                    (this->vals() == NULL
12512                                                     ? NULL
12513                                                     : this->vals()->copy()),
12514                                                    this->location());
12515   }
12516
12517   tree
12518   do_get_tree(Translate_context*);
12519
12520   void
12521   do_dump_expression(Ast_dump_context*);
12522 };
12523
12524 // Return a tree for constructing a fixed array.
12525
12526 tree
12527 Fixed_array_construction_expression::do_get_tree(Translate_context* context)
12528 {
12529   Type* type = this->type();
12530   Btype* btype = type->get_backend(context->gogo());
12531   return this->get_constructor_tree(context, type_to_tree(btype));
12532 }
12533
12534 // Dump ast representation of an array construction expressin.
12535
12536 void
12537 Fixed_array_construction_expression::do_dump_expression(
12538     Ast_dump_context* ast_dump_context)
12539 {
12540
12541   ast_dump_context->ostream() << "[";
12542   ast_dump_context->dump_expression (this->type()->array_type()->length());
12543   ast_dump_context->ostream() << "]";
12544   ast_dump_context->dump_type(this->type());
12545   ast_dump_context->ostream() << "{";
12546   ast_dump_context->dump_expression_list(this->vals());
12547   ast_dump_context->ostream() << "}";
12548
12549 }
12550 // Construct an open array.
12551
12552 class Open_array_construction_expression : public Array_construction_expression
12553 {
12554  public:
12555   Open_array_construction_expression(Type* type, Expression_list* vals,
12556                                      Location location)
12557     : Array_construction_expression(EXPRESSION_OPEN_ARRAY_CONSTRUCTION,
12558                                     type, vals, location)
12559   {
12560     go_assert(type->array_type() != NULL
12561                && type->array_type()->length() == NULL);
12562   }
12563
12564  protected:
12565   // Note that taking the address of an open array literal is invalid.
12566
12567   Expression*
12568   do_copy()
12569   {
12570     return new Open_array_construction_expression(this->type(),
12571                                                   (this->vals() == NULL
12572                                                    ? NULL
12573                                                    : this->vals()->copy()),
12574                                                   this->location());
12575   }
12576
12577   tree
12578   do_get_tree(Translate_context*);
12579 };
12580
12581 // Return a tree for constructing an open array.
12582
12583 tree
12584 Open_array_construction_expression::do_get_tree(Translate_context* context)
12585 {
12586   Array_type* array_type = this->type()->array_type();
12587   if (array_type == NULL)
12588     {
12589       go_assert(this->type()->is_error());
12590       return error_mark_node;
12591     }
12592
12593   Type* element_type = array_type->element_type();
12594   Btype* belement_type = element_type->get_backend(context->gogo());
12595   tree element_type_tree = type_to_tree(belement_type);
12596   if (element_type_tree == error_mark_node)
12597     return error_mark_node;
12598
12599   tree values;
12600   tree length_tree;
12601   if (this->vals() == NULL || this->vals()->empty())
12602     {
12603       // We need to create a unique value.
12604       tree max = size_int(0);
12605       tree constructor_type = build_array_type(element_type_tree,
12606                                                build_index_type(max));
12607       if (constructor_type == error_mark_node)
12608         return error_mark_node;
12609       VEC(constructor_elt,gc)* vec = VEC_alloc(constructor_elt, gc, 1);
12610       constructor_elt* elt = VEC_quick_push(constructor_elt, vec, NULL);
12611       elt->index = size_int(0);
12612       Gogo* gogo = context->gogo();
12613       Btype* btype = element_type->get_backend(gogo);
12614       elt->value = expr_to_tree(gogo->backend()->zero_expression(btype));
12615       values = build_constructor(constructor_type, vec);
12616       if (TREE_CONSTANT(elt->value))
12617         TREE_CONSTANT(values) = 1;
12618       length_tree = size_int(0);
12619     }
12620   else
12621     {
12622       tree max = size_int(this->vals()->size() - 1);
12623       tree constructor_type = build_array_type(element_type_tree,
12624                                                build_index_type(max));
12625       if (constructor_type == error_mark_node)
12626         return error_mark_node;
12627       values = this->get_constructor_tree(context, constructor_type);
12628       length_tree = size_int(this->vals()->size());
12629     }
12630
12631   if (values == error_mark_node)
12632     return error_mark_node;
12633
12634   bool is_constant_initializer = TREE_CONSTANT(values);
12635
12636   // We have to copy the initial values into heap memory if we are in
12637   // a function or if the values are not constants.  We also have to
12638   // copy them if they may contain pointers in a non-constant context,
12639   // as otherwise the garbage collector won't see them.
12640   bool copy_to_heap = (context->function() != NULL
12641                        || !is_constant_initializer
12642                        || (element_type->has_pointer()
12643                            && !context->is_const()));
12644
12645   if (is_constant_initializer)
12646     {
12647       tree tmp = build_decl(this->location().gcc_location(), VAR_DECL,
12648                             create_tmp_var_name("C"), TREE_TYPE(values));
12649       DECL_EXTERNAL(tmp) = 0;
12650       TREE_PUBLIC(tmp) = 0;
12651       TREE_STATIC(tmp) = 1;
12652       DECL_ARTIFICIAL(tmp) = 1;
12653       if (copy_to_heap)
12654         {
12655           // If we are not copying the value to the heap, we will only
12656           // initialize the value once, so we can use this directly
12657           // rather than copying it.  In that case we can't make it
12658           // read-only, because the program is permitted to change it.
12659           TREE_READONLY(tmp) = 1;
12660           TREE_CONSTANT(tmp) = 1;
12661         }
12662       DECL_INITIAL(tmp) = values;
12663       rest_of_decl_compilation(tmp, 1, 0);
12664       values = tmp;
12665     }
12666
12667   tree space;
12668   tree set;
12669   if (!copy_to_heap)
12670     {
12671       // the initializer will only run once.
12672       space = build_fold_addr_expr(values);
12673       set = NULL_TREE;
12674     }
12675   else
12676     {
12677       tree memsize = TYPE_SIZE_UNIT(TREE_TYPE(values));
12678       space = context->gogo()->allocate_memory(element_type, memsize,
12679                                                this->location());
12680       space = save_expr(space);
12681
12682       tree s = fold_convert(build_pointer_type(TREE_TYPE(values)), space);
12683       tree ref = build_fold_indirect_ref_loc(this->location().gcc_location(),
12684                                              s);
12685       TREE_THIS_NOTRAP(ref) = 1;
12686       set = build2(MODIFY_EXPR, void_type_node, ref, values);
12687     }
12688
12689   // Build a constructor for the open array.
12690
12691   tree type_tree = type_to_tree(this->type()->get_backend(context->gogo()));
12692   if (type_tree == error_mark_node)
12693     return error_mark_node;
12694   go_assert(TREE_CODE(type_tree) == RECORD_TYPE);
12695
12696   VEC(constructor_elt,gc)* init = VEC_alloc(constructor_elt, gc, 3);
12697
12698   constructor_elt* elt = VEC_quick_push(constructor_elt, init, NULL);
12699   tree field = TYPE_FIELDS(type_tree);
12700   go_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__values") == 0);
12701   elt->index = field;
12702   elt->value = fold_convert(TREE_TYPE(field), space);
12703
12704   elt = VEC_quick_push(constructor_elt, init, NULL);
12705   field = DECL_CHAIN(field);
12706   go_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__count") == 0);
12707   elt->index = field;
12708   elt->value = fold_convert(TREE_TYPE(field), length_tree);
12709
12710   elt = VEC_quick_push(constructor_elt, init, NULL);
12711   field = DECL_CHAIN(field);
12712   go_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)),"__capacity") == 0);
12713   elt->index = field;
12714   elt->value = fold_convert(TREE_TYPE(field), length_tree);
12715
12716   tree constructor = build_constructor(type_tree, init);
12717   if (constructor == error_mark_node)
12718     return error_mark_node;
12719   if (!copy_to_heap)
12720     TREE_CONSTANT(constructor) = 1;
12721
12722   if (set == NULL_TREE)
12723     return constructor;
12724   else
12725     return build2(COMPOUND_EXPR, type_tree, set, constructor);
12726 }
12727
12728 // Make a slice composite literal.  This is used by the type
12729 // descriptor code.
12730
12731 Expression*
12732 Expression::make_slice_composite_literal(Type* type, Expression_list* vals,
12733                                          Location location)
12734 {
12735   go_assert(type->is_slice_type());
12736   return new Open_array_construction_expression(type, vals, location);
12737 }
12738
12739 // Construct a map.
12740
12741 class Map_construction_expression : public Expression
12742 {
12743  public:
12744   Map_construction_expression(Type* type, Expression_list* vals,
12745                               Location location)
12746     : Expression(EXPRESSION_MAP_CONSTRUCTION, location),
12747       type_(type), vals_(vals)
12748   { go_assert(vals == NULL || vals->size() % 2 == 0); }
12749
12750  protected:
12751   int
12752   do_traverse(Traverse* traverse);
12753
12754   Type*
12755   do_type()
12756   { return this->type_; }
12757
12758   void
12759   do_determine_type(const Type_context*);
12760
12761   void
12762   do_check_types(Gogo*);
12763
12764   Expression*
12765   do_copy()
12766   {
12767     return new Map_construction_expression(this->type_, this->vals_->copy(),
12768                                            this->location());
12769   }
12770
12771   tree
12772   do_get_tree(Translate_context*);
12773
12774   void
12775   do_export(Export*) const;
12776
12777   void
12778   do_dump_expression(Ast_dump_context*) const;
12779
12780  private:
12781   // The type of the map to construct.
12782   Type* type_;
12783   // The list of values.
12784   Expression_list* vals_;
12785 };
12786
12787 // Traversal.
12788
12789 int
12790 Map_construction_expression::do_traverse(Traverse* traverse)
12791 {
12792   if (this->vals_ != NULL
12793       && this->vals_->traverse(traverse) == TRAVERSE_EXIT)
12794     return TRAVERSE_EXIT;
12795   if (Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
12796     return TRAVERSE_EXIT;
12797   return TRAVERSE_CONTINUE;
12798 }
12799
12800 // Final type determination.
12801
12802 void
12803 Map_construction_expression::do_determine_type(const Type_context*)
12804 {
12805   if (this->vals_ == NULL)
12806     return;
12807
12808   Map_type* mt = this->type_->map_type();
12809   Type_context key_context(mt->key_type(), false);
12810   Type_context val_context(mt->val_type(), false);
12811   for (Expression_list::const_iterator pv = this->vals_->begin();
12812        pv != this->vals_->end();
12813        ++pv)
12814     {
12815       (*pv)->determine_type(&key_context);
12816       ++pv;
12817       (*pv)->determine_type(&val_context);
12818     }
12819 }
12820
12821 // Check types.
12822
12823 void
12824 Map_construction_expression::do_check_types(Gogo*)
12825 {
12826   if (this->vals_ == NULL)
12827     return;
12828
12829   Map_type* mt = this->type_->map_type();
12830   int i = 0;
12831   Type* key_type = mt->key_type();
12832   Type* val_type = mt->val_type();
12833   for (Expression_list::const_iterator pv = this->vals_->begin();
12834        pv != this->vals_->end();
12835        ++pv, ++i)
12836     {
12837       if (!Type::are_assignable(key_type, (*pv)->type(), NULL))
12838         {
12839           error_at((*pv)->location(),
12840                    "incompatible type for element %d key in map construction",
12841                    i + 1);
12842           this->set_is_error();
12843         }
12844       ++pv;
12845       if (!Type::are_assignable(val_type, (*pv)->type(), NULL))
12846         {
12847           error_at((*pv)->location(),
12848                    ("incompatible type for element %d value "
12849                     "in map construction"),
12850                    i + 1);
12851           this->set_is_error();
12852         }
12853     }
12854 }
12855
12856 // Return a tree for constructing a map.
12857
12858 tree
12859 Map_construction_expression::do_get_tree(Translate_context* context)
12860 {
12861   Gogo* gogo = context->gogo();
12862   Location loc = this->location();
12863
12864   Map_type* mt = this->type_->map_type();
12865
12866   // Build a struct to hold the key and value.
12867   tree struct_type = make_node(RECORD_TYPE);
12868
12869   Type* key_type = mt->key_type();
12870   tree id = get_identifier("__key");
12871   tree key_type_tree = type_to_tree(key_type->get_backend(gogo));
12872   if (key_type_tree == error_mark_node)
12873     return error_mark_node;
12874   tree key_field = build_decl(loc.gcc_location(), FIELD_DECL, id,
12875                               key_type_tree);
12876   DECL_CONTEXT(key_field) = struct_type;
12877   TYPE_FIELDS(struct_type) = key_field;
12878
12879   Type* val_type = mt->val_type();
12880   id = get_identifier("__val");
12881   tree val_type_tree = type_to_tree(val_type->get_backend(gogo));
12882   if (val_type_tree == error_mark_node)
12883     return error_mark_node;
12884   tree val_field = build_decl(loc.gcc_location(), FIELD_DECL, id,
12885                               val_type_tree);
12886   DECL_CONTEXT(val_field) = struct_type;
12887   DECL_CHAIN(key_field) = val_field;
12888
12889   layout_type(struct_type);
12890
12891   bool is_constant = true;
12892   size_t i = 0;
12893   tree valaddr;
12894   tree make_tmp;
12895
12896   if (this->vals_ == NULL || this->vals_->empty())
12897     {
12898       valaddr = null_pointer_node;
12899       make_tmp = NULL_TREE;
12900     }
12901   else
12902     {
12903       VEC(constructor_elt,gc)* values = VEC_alloc(constructor_elt, gc,
12904                                                   this->vals_->size() / 2);
12905
12906       for (Expression_list::const_iterator pv = this->vals_->begin();
12907            pv != this->vals_->end();
12908            ++pv, ++i)
12909         {
12910           bool one_is_constant = true;
12911
12912           VEC(constructor_elt,gc)* one = VEC_alloc(constructor_elt, gc, 2);
12913
12914           constructor_elt* elt = VEC_quick_push(constructor_elt, one, NULL);
12915           elt->index = key_field;
12916           tree val_tree = (*pv)->get_tree(context);
12917           elt->value = Expression::convert_for_assignment(context, key_type,
12918                                                           (*pv)->type(),
12919                                                           val_tree, loc);
12920           if (elt->value == error_mark_node)
12921             return error_mark_node;
12922           if (!TREE_CONSTANT(elt->value))
12923             one_is_constant = false;
12924
12925           ++pv;
12926
12927           elt = VEC_quick_push(constructor_elt, one, NULL);
12928           elt->index = val_field;
12929           val_tree = (*pv)->get_tree(context);
12930           elt->value = Expression::convert_for_assignment(context, val_type,
12931                                                           (*pv)->type(),
12932                                                           val_tree, loc);
12933           if (elt->value == error_mark_node)
12934             return error_mark_node;
12935           if (!TREE_CONSTANT(elt->value))
12936             one_is_constant = false;
12937
12938           elt = VEC_quick_push(constructor_elt, values, NULL);
12939           elt->index = size_int(i);
12940           elt->value = build_constructor(struct_type, one);
12941           if (one_is_constant)
12942             TREE_CONSTANT(elt->value) = 1;
12943           else
12944             is_constant = false;
12945         }
12946
12947       tree index_type = build_index_type(size_int(i - 1));
12948       tree array_type = build_array_type(struct_type, index_type);
12949       tree init = build_constructor(array_type, values);
12950       if (is_constant)
12951         TREE_CONSTANT(init) = 1;
12952       tree tmp;
12953       if (current_function_decl != NULL)
12954         {
12955           tmp = create_tmp_var(array_type, get_name(array_type));
12956           DECL_INITIAL(tmp) = init;
12957           make_tmp = fold_build1_loc(loc.gcc_location(), DECL_EXPR,
12958                                      void_type_node, tmp);
12959           TREE_ADDRESSABLE(tmp) = 1;
12960         }
12961       else
12962         {
12963           tmp = build_decl(loc.gcc_location(), VAR_DECL,
12964                            create_tmp_var_name("M"), array_type);
12965           DECL_EXTERNAL(tmp) = 0;
12966           TREE_PUBLIC(tmp) = 0;
12967           TREE_STATIC(tmp) = 1;
12968           DECL_ARTIFICIAL(tmp) = 1;
12969           if (!TREE_CONSTANT(init))
12970             make_tmp = fold_build2_loc(loc.gcc_location(), INIT_EXPR,
12971                                        void_type_node, tmp, init);
12972           else
12973             {
12974               TREE_READONLY(tmp) = 1;
12975               TREE_CONSTANT(tmp) = 1;
12976               DECL_INITIAL(tmp) = init;
12977               make_tmp = NULL_TREE;
12978             }
12979           rest_of_decl_compilation(tmp, 1, 0);
12980         }
12981
12982       valaddr = build_fold_addr_expr(tmp);
12983     }
12984
12985   tree descriptor = mt->map_descriptor_pointer(gogo, loc);
12986
12987   tree type_tree = type_to_tree(this->type_->get_backend(gogo));
12988   if (type_tree == error_mark_node)
12989     return error_mark_node;
12990
12991   static tree construct_map_fndecl;
12992   tree call = Gogo::call_builtin(&construct_map_fndecl,
12993                                  loc,
12994                                  "__go_construct_map",
12995                                  6,
12996                                  type_tree,
12997                                  TREE_TYPE(descriptor),
12998                                  descriptor,
12999                                  sizetype,
13000                                  size_int(i),
13001                                  sizetype,
13002                                  TYPE_SIZE_UNIT(struct_type),
13003                                  sizetype,
13004                                  byte_position(val_field),
13005                                  sizetype,
13006                                  TYPE_SIZE_UNIT(TREE_TYPE(val_field)),
13007                                  const_ptr_type_node,
13008                                  fold_convert(const_ptr_type_node, valaddr));
13009   if (call == error_mark_node)
13010     return error_mark_node;
13011
13012   tree ret;
13013   if (make_tmp == NULL)
13014     ret = call;
13015   else
13016     ret = fold_build2_loc(loc.gcc_location(), COMPOUND_EXPR, type_tree,
13017                           make_tmp, call);
13018   return ret;
13019 }
13020
13021 // Export an array construction.
13022
13023 void
13024 Map_construction_expression::do_export(Export* exp) const
13025 {
13026   exp->write_c_string("convert(");
13027   exp->write_type(this->type_);
13028   for (Expression_list::const_iterator pv = this->vals_->begin();
13029        pv != this->vals_->end();
13030        ++pv)
13031     {
13032       exp->write_c_string(", ");
13033       (*pv)->export_expression(exp);
13034     }
13035   exp->write_c_string(")");
13036 }
13037
13038 // Dump ast representation for a map construction expression.
13039
13040 void
13041 Map_construction_expression::do_dump_expression(
13042     Ast_dump_context* ast_dump_context) const
13043 {
13044   ast_dump_context->ostream() << "{" ;
13045   ast_dump_context->dump_expression_list(this->vals_, true);
13046   ast_dump_context->ostream() << "}";
13047 }
13048
13049 // A general composite literal.  This is lowered to a type specific
13050 // version.
13051
13052 class Composite_literal_expression : public Parser_expression
13053 {
13054  public:
13055   Composite_literal_expression(Type* type, int depth, bool has_keys,
13056                                Expression_list* vals, Location location)
13057     : Parser_expression(EXPRESSION_COMPOSITE_LITERAL, location),
13058       type_(type), depth_(depth), vals_(vals), has_keys_(has_keys)
13059   { }
13060
13061  protected:
13062   int
13063   do_traverse(Traverse* traverse);
13064
13065   Expression*
13066   do_lower(Gogo*, Named_object*, Statement_inserter*, int);
13067
13068   Expression*
13069   do_copy()
13070   {
13071     return new Composite_literal_expression(this->type_, this->depth_,
13072                                             this->has_keys_,
13073                                             (this->vals_ == NULL
13074                                              ? NULL
13075                                              : this->vals_->copy()),
13076                                             this->location());
13077   }
13078
13079   void
13080   do_dump_expression(Ast_dump_context*) const;
13081
13082  private:
13083   Expression*
13084   lower_struct(Gogo*, Type*);
13085
13086   Expression*
13087   lower_array(Type*);
13088
13089   Expression*
13090   make_array(Type*, Expression_list*);
13091
13092   Expression*
13093   lower_map(Gogo*, Named_object*, Statement_inserter*, Type*);
13094
13095   // The type of the composite literal.
13096   Type* type_;
13097   // The depth within a list of composite literals within a composite
13098   // literal, when the type is omitted.
13099   int depth_;
13100   // The values to put in the composite literal.
13101   Expression_list* vals_;
13102   // If this is true, then VALS_ is a list of pairs: a key and a
13103   // value.  In an array initializer, a missing key will be NULL.
13104   bool has_keys_;
13105 };
13106
13107 // Traversal.
13108
13109 int
13110 Composite_literal_expression::do_traverse(Traverse* traverse)
13111 {
13112   if (this->vals_ != NULL
13113       && this->vals_->traverse(traverse) == TRAVERSE_EXIT)
13114     return TRAVERSE_EXIT;
13115   return Type::traverse(this->type_, traverse);
13116 }
13117
13118 // Lower a generic composite literal into a specific version based on
13119 // the type.
13120
13121 Expression*
13122 Composite_literal_expression::do_lower(Gogo* gogo, Named_object* function,
13123                                        Statement_inserter* inserter, int)
13124 {
13125   Type* type = this->type_;
13126
13127   for (int depth = this->depth_; depth > 0; --depth)
13128     {
13129       if (type->array_type() != NULL)
13130         type = type->array_type()->element_type();
13131       else if (type->map_type() != NULL)
13132         type = type->map_type()->val_type();
13133       else
13134         {
13135           if (!type->is_error())
13136             error_at(this->location(),
13137                      ("may only omit types within composite literals "
13138                       "of slice, array, or map type"));
13139           return Expression::make_error(this->location());
13140         }
13141     }
13142
13143   Type *pt = type->points_to();
13144   bool is_pointer = false;
13145   if (pt != NULL)
13146     {
13147       is_pointer = true;
13148       type = pt;
13149     }
13150
13151   Expression* ret;
13152   if (type->is_error())
13153     return Expression::make_error(this->location());
13154   else if (type->struct_type() != NULL)
13155     ret = this->lower_struct(gogo, type);
13156   else if (type->array_type() != NULL)
13157     ret = this->lower_array(type);
13158   else if (type->map_type() != NULL)
13159     ret = this->lower_map(gogo, function, inserter, type);
13160   else
13161     {
13162       error_at(this->location(),
13163                ("expected struct, slice, array, or map type "
13164                 "for composite literal"));
13165       return Expression::make_error(this->location());
13166     }
13167
13168   if (is_pointer)
13169     ret = Expression::make_heap_composite(ret, this->location());
13170
13171   return ret;
13172 }
13173
13174 // Lower a struct composite literal.
13175
13176 Expression*
13177 Composite_literal_expression::lower_struct(Gogo* gogo, Type* type)
13178 {
13179   Location location = this->location();
13180   Struct_type* st = type->struct_type();
13181   if (this->vals_ == NULL || !this->has_keys_)
13182     {
13183       if (this->vals_ != NULL
13184           && !this->vals_->empty()
13185           && type->named_type() != NULL
13186           && type->named_type()->named_object()->package() != NULL)
13187         {
13188           for (Struct_field_list::const_iterator pf = st->fields()->begin();
13189                pf != st->fields()->end();
13190                ++pf)
13191             {
13192               if (Gogo::is_hidden_name(pf->field_name()))
13193                 error_at(this->location(),
13194                          "assignment of unexported field %qs in %qs literal",
13195                          Gogo::message_name(pf->field_name()).c_str(),
13196                          type->named_type()->message_name().c_str());
13197             }
13198         }
13199
13200       return new Struct_construction_expression(type, this->vals_, location);
13201     }
13202
13203   size_t field_count = st->field_count();
13204   std::vector<Expression*> vals(field_count);
13205   Expression_list::const_iterator p = this->vals_->begin();
13206   while (p != this->vals_->end())
13207     {
13208       Expression* name_expr = *p;
13209
13210       ++p;
13211       go_assert(p != this->vals_->end());
13212       Expression* val = *p;
13213
13214       ++p;
13215
13216       if (name_expr == NULL)
13217         {
13218           error_at(val->location(), "mixture of field and value initializers");
13219           return Expression::make_error(location);
13220         }
13221
13222       bool bad_key = false;
13223       std::string name;
13224       const Named_object* no = NULL;
13225       switch (name_expr->classification())
13226         {
13227         case EXPRESSION_UNKNOWN_REFERENCE:
13228           name = name_expr->unknown_expression()->name();
13229           break;
13230
13231         case EXPRESSION_CONST_REFERENCE:
13232           no = static_cast<Const_expression*>(name_expr)->named_object();
13233           break;
13234
13235         case EXPRESSION_TYPE:
13236           {
13237             Type* t = name_expr->type();
13238             Named_type* nt = t->named_type();
13239             if (nt == NULL)
13240               bad_key = true;
13241             else
13242               no = nt->named_object();
13243           }
13244           break;
13245
13246         case EXPRESSION_VAR_REFERENCE:
13247           no = name_expr->var_expression()->named_object();
13248           break;
13249
13250         case EXPRESSION_FUNC_REFERENCE:
13251           no = name_expr->func_expression()->named_object();
13252           break;
13253
13254         case EXPRESSION_UNARY:
13255           // If there is a local variable around with the same name as
13256           // the field, and this occurs in the closure, then the
13257           // parser may turn the field reference into an indirection
13258           // through the closure.  FIXME: This is a mess.
13259           {
13260             bad_key = true;
13261             Unary_expression* ue = static_cast<Unary_expression*>(name_expr);
13262             if (ue->op() == OPERATOR_MULT)
13263               {
13264                 Field_reference_expression* fre =
13265                   ue->operand()->field_reference_expression();
13266                 if (fre != NULL)
13267                   {
13268                     Struct_type* st =
13269                       fre->expr()->type()->deref()->struct_type();
13270                     if (st != NULL)
13271                       {
13272                         const Struct_field* sf = st->field(fre->field_index());
13273                         name = sf->field_name();
13274
13275                         // See below.  FIXME.
13276                         if (!Gogo::is_hidden_name(name)
13277                             && name[0] >= 'a'
13278                             && name[0] <= 'z')
13279                           {
13280                             if (gogo->lookup_global(name.c_str()) != NULL)
13281                               name = gogo->pack_hidden_name(name, false);
13282                           }
13283
13284                         char buf[20];
13285                         snprintf(buf, sizeof buf, "%u", fre->field_index());
13286                         size_t buflen = strlen(buf);
13287                         if (name.compare(name.length() - buflen, buflen, buf)
13288                             == 0)
13289                           {
13290                             name = name.substr(0, name.length() - buflen);
13291                             bad_key = false;
13292                           }
13293                       }
13294                   }
13295               }
13296           }
13297           break;
13298
13299         default:
13300           bad_key = true;
13301           break;
13302         }
13303       if (bad_key)
13304         {
13305           error_at(name_expr->location(), "expected struct field name");
13306           return Expression::make_error(location);
13307         }
13308
13309       if (no != NULL)
13310         {
13311           name = no->name();
13312
13313           // A predefined name won't be packed.  If it starts with a
13314           // lower case letter we need to check for that case, because
13315           // the field name will be packed.  FIXME.
13316           if (!Gogo::is_hidden_name(name)
13317               && name[0] >= 'a'
13318               && name[0] <= 'z')
13319             {
13320               Named_object* gno = gogo->lookup_global(name.c_str());
13321               if (gno == no)
13322                 name = gogo->pack_hidden_name(name, false);
13323             }
13324         }
13325
13326       unsigned int index;
13327       const Struct_field* sf = st->find_local_field(name, &index);
13328       if (sf == NULL)
13329         {
13330           error_at(name_expr->location(), "unknown field %qs in %qs",
13331                    Gogo::message_name(name).c_str(),
13332                    (type->named_type() != NULL
13333                     ? type->named_type()->message_name().c_str()
13334                     : "unnamed struct"));
13335           return Expression::make_error(location);
13336         }
13337       if (vals[index] != NULL)
13338         {
13339           error_at(name_expr->location(),
13340                    "duplicate value for field %qs in %qs",
13341                    Gogo::message_name(name).c_str(),
13342                    (type->named_type() != NULL
13343                     ? type->named_type()->message_name().c_str()
13344                     : "unnamed struct"));
13345           return Expression::make_error(location);
13346         }
13347
13348       if (type->named_type() != NULL
13349           && type->named_type()->named_object()->package() != NULL
13350           && Gogo::is_hidden_name(sf->field_name()))
13351         error_at(name_expr->location(),
13352                  "assignment of unexported field %qs in %qs literal",
13353                  Gogo::message_name(sf->field_name()).c_str(),
13354                  type->named_type()->message_name().c_str());
13355
13356       vals[index] = val;
13357     }
13358
13359   Expression_list* list = new Expression_list;
13360   list->reserve(field_count);
13361   for (size_t i = 0; i < field_count; ++i)
13362     list->push_back(vals[i]);
13363
13364   return new Struct_construction_expression(type, list, location);
13365 }
13366
13367 // Lower an array composite literal.
13368
13369 Expression*
13370 Composite_literal_expression::lower_array(Type* type)
13371 {
13372   Location location = this->location();
13373   if (this->vals_ == NULL || !this->has_keys_)
13374     return this->make_array(type, this->vals_);
13375
13376   std::vector<Expression*> vals;
13377   vals.reserve(this->vals_->size());
13378   unsigned long index = 0;
13379   Expression_list::const_iterator p = this->vals_->begin();
13380   while (p != this->vals_->end())
13381     {
13382       Expression* index_expr = *p;
13383
13384       ++p;
13385       go_assert(p != this->vals_->end());
13386       Expression* val = *p;
13387
13388       ++p;
13389
13390       if (index_expr != NULL)
13391         {
13392           mpz_t ival;
13393           mpz_init(ival);
13394
13395           Type* dummy;
13396           if (!index_expr->integer_constant_value(true, ival, &dummy))
13397             {
13398               mpz_clear(ival);
13399               error_at(index_expr->location(),
13400                        "index expression is not integer constant");
13401               return Expression::make_error(location);
13402             }
13403
13404           if (mpz_sgn(ival) < 0)
13405             {
13406               mpz_clear(ival);
13407               error_at(index_expr->location(), "index expression is negative");
13408               return Expression::make_error(location);
13409             }
13410
13411           index = mpz_get_ui(ival);
13412           if (mpz_cmp_ui(ival, index) != 0)
13413             {
13414               mpz_clear(ival);
13415               error_at(index_expr->location(), "index value overflow");
13416               return Expression::make_error(location);
13417             }
13418
13419           Named_type* ntype = Type::lookup_integer_type("int");
13420           Integer_type* inttype = ntype->integer_type();
13421           mpz_t max;
13422           mpz_init_set_ui(max, 1);
13423           mpz_mul_2exp(max, max, inttype->bits() - 1);
13424           bool ok = mpz_cmp(ival, max) < 0;
13425           mpz_clear(max);
13426           if (!ok)
13427             {
13428               mpz_clear(ival);
13429               error_at(index_expr->location(), "index value overflow");
13430               return Expression::make_error(location);
13431             }
13432
13433           mpz_clear(ival);
13434
13435           // FIXME: Our representation isn't very good; this avoids
13436           // thrashing.
13437           if (index > 0x1000000)
13438             {
13439               error_at(index_expr->location(), "index too large for compiler");
13440               return Expression::make_error(location);
13441             }
13442         }
13443
13444       if (index == vals.size())
13445         vals.push_back(val);
13446       else
13447         {
13448           if (index > vals.size())
13449             {
13450               vals.reserve(index + 32);
13451               vals.resize(index + 1, static_cast<Expression*>(NULL));
13452             }
13453           if (vals[index] != NULL)
13454             {
13455               error_at((index_expr != NULL
13456                         ? index_expr->location()
13457                         : val->location()),
13458                        "duplicate value for index %lu",
13459                        index);
13460               return Expression::make_error(location);
13461             }
13462           vals[index] = val;
13463         }
13464
13465       ++index;
13466     }
13467
13468   size_t size = vals.size();
13469   Expression_list* list = new Expression_list;
13470   list->reserve(size);
13471   for (size_t i = 0; i < size; ++i)
13472     list->push_back(vals[i]);
13473
13474   return this->make_array(type, list);
13475 }
13476
13477 // Actually build the array composite literal. This handles
13478 // [...]{...}.
13479
13480 Expression*
13481 Composite_literal_expression::make_array(Type* type, Expression_list* vals)
13482 {
13483   Location location = this->location();
13484   Array_type* at = type->array_type();
13485   if (at->length() != NULL && at->length()->is_nil_expression())
13486     {
13487       size_t size = vals == NULL ? 0 : vals->size();
13488       mpz_t vlen;
13489       mpz_init_set_ui(vlen, size);
13490       Expression* elen = Expression::make_integer(&vlen, NULL, location);
13491       mpz_clear(vlen);
13492       at = Type::make_array_type(at->element_type(), elen);
13493       type = at;
13494     }
13495   if (at->length() != NULL)
13496     return new Fixed_array_construction_expression(type, vals, location);
13497   else
13498     return new Open_array_construction_expression(type, vals, location);
13499 }
13500
13501 // Lower a map composite literal.
13502
13503 Expression*
13504 Composite_literal_expression::lower_map(Gogo* gogo, Named_object* function,
13505                                         Statement_inserter* inserter,
13506                                         Type* type)
13507 {
13508   Location location = this->location();
13509   if (this->vals_ != NULL)
13510     {
13511       if (!this->has_keys_)
13512         {
13513           error_at(location, "map composite literal must have keys");
13514           return Expression::make_error(location);
13515         }
13516
13517       for (Expression_list::iterator p = this->vals_->begin();
13518            p != this->vals_->end();
13519            p += 2)
13520         {
13521           if (*p == NULL)
13522             {
13523               ++p;
13524               error_at((*p)->location(),
13525                        "map composite literal must have keys for every value");
13526               return Expression::make_error(location);
13527             }
13528           // Make sure we have lowered the key; it may not have been
13529           // lowered in order to handle keys for struct composite
13530           // literals.  Lower it now to get the right error message.
13531           if ((*p)->unknown_expression() != NULL)
13532             {
13533               (*p)->unknown_expression()->clear_is_composite_literal_key();
13534               gogo->lower_expression(function, inserter, &*p);
13535               go_assert((*p)->is_error_expression());
13536               return Expression::make_error(location);
13537             }
13538         }
13539     }
13540
13541   return new Map_construction_expression(type, this->vals_, location);
13542 }
13543
13544 // Dump ast representation for a composite literal expression.
13545
13546 void
13547 Composite_literal_expression::do_dump_expression(
13548                                Ast_dump_context* ast_dump_context) const
13549 {
13550   ast_dump_context->ostream() << "composite(";
13551   ast_dump_context->dump_type(this->type_);
13552   ast_dump_context->ostream() << ", {";
13553   ast_dump_context->dump_expression_list(this->vals_, this->has_keys_);
13554   ast_dump_context->ostream() << "})";
13555 }
13556
13557 // Make a composite literal expression.
13558
13559 Expression*
13560 Expression::make_composite_literal(Type* type, int depth, bool has_keys,
13561                                    Expression_list* vals,
13562                                    Location location)
13563 {
13564   return new Composite_literal_expression(type, depth, has_keys, vals,
13565                                           location);
13566 }
13567
13568 // Return whether this expression is a composite literal.
13569
13570 bool
13571 Expression::is_composite_literal() const
13572 {
13573   switch (this->classification_)
13574     {
13575     case EXPRESSION_COMPOSITE_LITERAL:
13576     case EXPRESSION_STRUCT_CONSTRUCTION:
13577     case EXPRESSION_FIXED_ARRAY_CONSTRUCTION:
13578     case EXPRESSION_OPEN_ARRAY_CONSTRUCTION:
13579     case EXPRESSION_MAP_CONSTRUCTION:
13580       return true;
13581     default:
13582       return false;
13583     }
13584 }
13585
13586 // Return whether this expression is a composite literal which is not
13587 // constant.
13588
13589 bool
13590 Expression::is_nonconstant_composite_literal() const
13591 {
13592   switch (this->classification_)
13593     {
13594     case EXPRESSION_STRUCT_CONSTRUCTION:
13595       {
13596         const Struct_construction_expression *psce =
13597           static_cast<const Struct_construction_expression*>(this);
13598         return !psce->is_constant_struct();
13599       }
13600     case EXPRESSION_FIXED_ARRAY_CONSTRUCTION:
13601       {
13602         const Fixed_array_construction_expression *pace =
13603           static_cast<const Fixed_array_construction_expression*>(this);
13604         return !pace->is_constant_array();
13605       }
13606     case EXPRESSION_OPEN_ARRAY_CONSTRUCTION:
13607       {
13608         const Open_array_construction_expression *pace =
13609           static_cast<const Open_array_construction_expression*>(this);
13610         return !pace->is_constant_array();
13611       }
13612     case EXPRESSION_MAP_CONSTRUCTION:
13613       return true;
13614     default:
13615       return false;
13616     }
13617 }
13618
13619 // Return true if this is a reference to a local variable.
13620
13621 bool
13622 Expression::is_local_variable() const
13623 {
13624   const Var_expression* ve = this->var_expression();
13625   if (ve == NULL)
13626     return false;
13627   const Named_object* no = ve->named_object();
13628   return (no->is_result_variable()
13629           || (no->is_variable() && !no->var_value()->is_global()));
13630 }
13631
13632 // Class Type_guard_expression.
13633
13634 // Traversal.
13635
13636 int
13637 Type_guard_expression::do_traverse(Traverse* traverse)
13638 {
13639   if (Expression::traverse(&this->expr_, traverse) == TRAVERSE_EXIT
13640       || Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
13641     return TRAVERSE_EXIT;
13642   return TRAVERSE_CONTINUE;
13643 }
13644
13645 // Check types of a type guard expression.  The expression must have
13646 // an interface type, but the actual type conversion is checked at run
13647 // time.
13648
13649 void
13650 Type_guard_expression::do_check_types(Gogo*)
13651 {
13652   // 6g permits using a type guard with unsafe.pointer; we are
13653   // compatible.
13654   Type* expr_type = this->expr_->type();
13655   if (expr_type->is_unsafe_pointer_type())
13656     {
13657       if (this->type_->points_to() == NULL
13658           && (this->type_->integer_type() == NULL
13659               || (this->type_->forwarded()
13660                   != Type::lookup_integer_type("uintptr"))))
13661         this->report_error(_("invalid unsafe.Pointer conversion"));
13662     }
13663   else if (this->type_->is_unsafe_pointer_type())
13664     {
13665       if (expr_type->points_to() == NULL
13666           && (expr_type->integer_type() == NULL
13667               || (expr_type->forwarded()
13668                   != Type::lookup_integer_type("uintptr"))))
13669         this->report_error(_("invalid unsafe.Pointer conversion"));
13670     }
13671   else if (expr_type->interface_type() == NULL)
13672     {
13673       if (!expr_type->is_error() && !this->type_->is_error())
13674         this->report_error(_("type assertion only valid for interface types"));
13675       this->set_is_error();
13676     }
13677   else if (this->type_->interface_type() == NULL)
13678     {
13679       std::string reason;
13680       if (!expr_type->interface_type()->implements_interface(this->type_,
13681                                                              &reason))
13682         {
13683           if (!this->type_->is_error())
13684             {
13685               if (reason.empty())
13686                 this->report_error(_("impossible type assertion: "
13687                                      "type does not implement interface"));
13688               else
13689                 error_at(this->location(),
13690                          ("impossible type assertion: "
13691                           "type does not implement interface (%s)"),
13692                          reason.c_str());
13693             }
13694           this->set_is_error();
13695         }
13696     }
13697 }
13698
13699 // Return a tree for a type guard expression.
13700
13701 tree
13702 Type_guard_expression::do_get_tree(Translate_context* context)
13703 {
13704   Gogo* gogo = context->gogo();
13705   tree expr_tree = this->expr_->get_tree(context);
13706   if (expr_tree == error_mark_node)
13707     return error_mark_node;
13708   Type* expr_type = this->expr_->type();
13709   if ((this->type_->is_unsafe_pointer_type()
13710        && (expr_type->points_to() != NULL
13711            || expr_type->integer_type() != NULL))
13712       || (expr_type->is_unsafe_pointer_type()
13713           && this->type_->points_to() != NULL))
13714     return convert_to_pointer(type_to_tree(this->type_->get_backend(gogo)),
13715                               expr_tree);
13716   else if (expr_type->is_unsafe_pointer_type()
13717            && this->type_->integer_type() != NULL)
13718     return convert_to_integer(type_to_tree(this->type_->get_backend(gogo)),
13719                               expr_tree);
13720   else if (this->type_->interface_type() != NULL)
13721     return Expression::convert_interface_to_interface(context, this->type_,
13722                                                       this->expr_->type(),
13723                                                       expr_tree, true,
13724                                                       this->location());
13725   else
13726     return Expression::convert_for_assignment(context, this->type_,
13727                                               this->expr_->type(), expr_tree,
13728                                               this->location());
13729 }
13730
13731 // Dump ast representation for a type guard expression.
13732
13733 void
13734 Type_guard_expression::do_dump_expression(Ast_dump_context* ast_dump_context)
13735     const
13736 {
13737   this->expr_->dump_expression(ast_dump_context);
13738   ast_dump_context->ostream() <<  ".";
13739   ast_dump_context->dump_type(this->type_);
13740 }
13741
13742 // Make a type guard expression.
13743
13744 Expression*
13745 Expression::make_type_guard(Expression* expr, Type* type,
13746                             Location location)
13747 {
13748   return new Type_guard_expression(expr, type, location);
13749 }
13750
13751 // Class Heap_composite_expression.
13752
13753 // When you take the address of a composite literal, it is allocated
13754 // on the heap.  This class implements that.
13755
13756 class Heap_composite_expression : public Expression
13757 {
13758  public:
13759   Heap_composite_expression(Expression* expr, Location location)
13760     : Expression(EXPRESSION_HEAP_COMPOSITE, location),
13761       expr_(expr)
13762   { }
13763
13764  protected:
13765   int
13766   do_traverse(Traverse* traverse)
13767   { return Expression::traverse(&this->expr_, traverse); }
13768
13769   Type*
13770   do_type()
13771   { return Type::make_pointer_type(this->expr_->type()); }
13772
13773   void
13774   do_determine_type(const Type_context*)
13775   { this->expr_->determine_type_no_context(); }
13776
13777   Expression*
13778   do_copy()
13779   {
13780     return Expression::make_heap_composite(this->expr_->copy(),
13781                                            this->location());
13782   }
13783
13784   tree
13785   do_get_tree(Translate_context*);
13786
13787   // We only export global objects, and the parser does not generate
13788   // this in global scope.
13789   void
13790   do_export(Export*) const
13791   { go_unreachable(); }
13792
13793   void
13794   do_dump_expression(Ast_dump_context*) const;
13795
13796  private:
13797   // The composite literal which is being put on the heap.
13798   Expression* expr_;
13799 };
13800
13801 // Return a tree which allocates a composite literal on the heap.
13802
13803 tree
13804 Heap_composite_expression::do_get_tree(Translate_context* context)
13805 {
13806   tree expr_tree = this->expr_->get_tree(context);
13807   if (expr_tree == error_mark_node)
13808     return error_mark_node;
13809   tree expr_size = TYPE_SIZE_UNIT(TREE_TYPE(expr_tree));
13810   go_assert(TREE_CODE(expr_size) == INTEGER_CST);
13811   tree space = context->gogo()->allocate_memory(this->expr_->type(),
13812                                                 expr_size, this->location());
13813   space = fold_convert(build_pointer_type(TREE_TYPE(expr_tree)), space);
13814   space = save_expr(space);
13815   tree ref = build_fold_indirect_ref_loc(this->location().gcc_location(),
13816                                          space);
13817   TREE_THIS_NOTRAP(ref) = 1;
13818   tree ret = build2(COMPOUND_EXPR, TREE_TYPE(space),
13819                     build2(MODIFY_EXPR, void_type_node, ref, expr_tree),
13820                     space);
13821   SET_EXPR_LOCATION(ret, this->location().gcc_location());
13822   return ret;
13823 }
13824
13825 // Dump ast representation for a heap composite expression.
13826
13827 void
13828 Heap_composite_expression::do_dump_expression(
13829     Ast_dump_context* ast_dump_context) const
13830 {
13831   ast_dump_context->ostream() << "&(";
13832   ast_dump_context->dump_expression(this->expr_);
13833   ast_dump_context->ostream() << ")";
13834 }
13835
13836 // Allocate a composite literal on the heap.
13837
13838 Expression*
13839 Expression::make_heap_composite(Expression* expr, Location location)
13840 {
13841   return new Heap_composite_expression(expr, location);
13842 }
13843
13844 // Class Receive_expression.
13845
13846 // Return the type of a receive expression.
13847
13848 Type*
13849 Receive_expression::do_type()
13850 {
13851   Channel_type* channel_type = this->channel_->type()->channel_type();
13852   if (channel_type == NULL)
13853     return Type::make_error_type();
13854   return channel_type->element_type();
13855 }
13856
13857 // Check types for a receive expression.
13858
13859 void
13860 Receive_expression::do_check_types(Gogo*)
13861 {
13862   Type* type = this->channel_->type();
13863   if (type->is_error())
13864     {
13865       this->set_is_error();
13866       return;
13867     }
13868   if (type->channel_type() == NULL)
13869     {
13870       this->report_error(_("expected channel"));
13871       return;
13872     }
13873   if (!type->channel_type()->may_receive())
13874     {
13875       this->report_error(_("invalid receive on send-only channel"));
13876       return;
13877     }
13878 }
13879
13880 // Get a tree for a receive expression.
13881
13882 tree
13883 Receive_expression::do_get_tree(Translate_context* context)
13884 {
13885   Location loc = this->location();
13886
13887   Channel_type* channel_type = this->channel_->type()->channel_type();
13888   if (channel_type == NULL)
13889     {
13890       go_assert(this->channel_->type()->is_error());
13891       return error_mark_node;
13892     }
13893
13894   Expression* td = Expression::make_type_descriptor(channel_type, loc);
13895   tree td_tree = td->get_tree(context);
13896
13897   Type* element_type = channel_type->element_type();
13898   Btype* element_type_btype = element_type->get_backend(context->gogo());
13899   tree element_type_tree = type_to_tree(element_type_btype);
13900
13901   tree channel = this->channel_->get_tree(context);
13902   if (element_type_tree == error_mark_node || channel == error_mark_node)
13903     return error_mark_node;
13904
13905   return Gogo::receive_from_channel(element_type_tree, td_tree, channel, loc);
13906 }
13907
13908 // Dump ast representation for a receive expression.
13909
13910 void
13911 Receive_expression::do_dump_expression(Ast_dump_context* ast_dump_context) const
13912 {
13913   ast_dump_context->ostream() << " <- " ;
13914   ast_dump_context->dump_expression(channel_);
13915 }
13916
13917 // Make a receive expression.
13918
13919 Receive_expression*
13920 Expression::make_receive(Expression* channel, Location location)
13921 {
13922   return new Receive_expression(channel, location);
13923 }
13924
13925 // An expression which evaluates to a pointer to the type descriptor
13926 // of a type.
13927
13928 class Type_descriptor_expression : public Expression
13929 {
13930  public:
13931   Type_descriptor_expression(Type* type, Location location)
13932     : Expression(EXPRESSION_TYPE_DESCRIPTOR, location),
13933       type_(type)
13934   { }
13935
13936  protected:
13937   Type*
13938   do_type()
13939   { return Type::make_type_descriptor_ptr_type(); }
13940
13941   void
13942   do_determine_type(const Type_context*)
13943   { }
13944
13945   Expression*
13946   do_copy()
13947   { return this; }
13948
13949   tree
13950   do_get_tree(Translate_context* context)
13951   {
13952     return this->type_->type_descriptor_pointer(context->gogo(),
13953                                                 this->location());
13954   }
13955
13956   void
13957   do_dump_expression(Ast_dump_context*) const;
13958
13959  private:
13960   // The type for which this is the descriptor.
13961   Type* type_;
13962 };
13963
13964 // Dump ast representation for a type descriptor expression.
13965
13966 void
13967 Type_descriptor_expression::do_dump_expression(
13968     Ast_dump_context* ast_dump_context) const
13969 {
13970   ast_dump_context->dump_type(this->type_);
13971 }
13972
13973 // Make a type descriptor expression.
13974
13975 Expression*
13976 Expression::make_type_descriptor(Type* type, Location location)
13977 {
13978   return new Type_descriptor_expression(type, location);
13979 }
13980
13981 // An expression which evaluates to some characteristic of a type.
13982 // This is only used to initialize fields of a type descriptor.  Using
13983 // a new expression class is slightly inefficient but gives us a good
13984 // separation between the frontend and the middle-end with regard to
13985 // how types are laid out.
13986
13987 class Type_info_expression : public Expression
13988 {
13989  public:
13990   Type_info_expression(Type* type, Type_info type_info)
13991     : Expression(EXPRESSION_TYPE_INFO, Linemap::predeclared_location()),
13992       type_(type), type_info_(type_info)
13993   { }
13994
13995  protected:
13996   Type*
13997   do_type();
13998
13999   void
14000   do_determine_type(const Type_context*)
14001   { }
14002
14003   Expression*
14004   do_copy()
14005   { return this; }
14006
14007   tree
14008   do_get_tree(Translate_context* context);
14009
14010   void
14011   do_dump_expression(Ast_dump_context*) const;
14012
14013  private:
14014   // The type for which we are getting information.
14015   Type* type_;
14016   // What information we want.
14017   Type_info type_info_;
14018 };
14019
14020 // The type is chosen to match what the type descriptor struct
14021 // expects.
14022
14023 Type*
14024 Type_info_expression::do_type()
14025 {
14026   switch (this->type_info_)
14027     {
14028     case TYPE_INFO_SIZE:
14029       return Type::lookup_integer_type("uintptr");
14030     case TYPE_INFO_ALIGNMENT:
14031     case TYPE_INFO_FIELD_ALIGNMENT:
14032       return Type::lookup_integer_type("uint8");
14033     default:
14034       go_unreachable();
14035     }
14036 }
14037
14038 // Return type information in GENERIC.
14039
14040 tree
14041 Type_info_expression::do_get_tree(Translate_context* context)
14042 {
14043   Btype* btype = this->type_->get_backend(context->gogo());
14044   Gogo* gogo = context->gogo();
14045   size_t val;
14046   switch (this->type_info_)
14047     {
14048     case TYPE_INFO_SIZE:
14049       val = gogo->backend()->type_size(btype);
14050       break;
14051     case TYPE_INFO_ALIGNMENT:
14052       val = gogo->backend()->type_alignment(btype);
14053       break;
14054     case TYPE_INFO_FIELD_ALIGNMENT:
14055       val = gogo->backend()->type_field_alignment(btype);
14056       break;
14057     default:
14058       go_unreachable();
14059     }
14060   tree val_type_tree = type_to_tree(this->type()->get_backend(gogo));
14061   go_assert(val_type_tree != error_mark_node);
14062   return build_int_cstu(val_type_tree, val);
14063 }
14064
14065 // Dump ast representation for a type info expression.
14066
14067 void
14068 Type_info_expression::do_dump_expression(
14069     Ast_dump_context* ast_dump_context) const
14070 {
14071   ast_dump_context->ostream() << "typeinfo(";
14072   ast_dump_context->dump_type(this->type_);
14073   ast_dump_context->ostream() << ",";
14074   ast_dump_context->ostream() <<
14075     (this->type_info_ == TYPE_INFO_ALIGNMENT ? "alignment"
14076     : this->type_info_ == TYPE_INFO_FIELD_ALIGNMENT ? "field alignment"
14077     : this->type_info_ == TYPE_INFO_SIZE ? "size "
14078     : "unknown");
14079   ast_dump_context->ostream() << ")";
14080 }
14081
14082 // Make a type info expression.
14083
14084 Expression*
14085 Expression::make_type_info(Type* type, Type_info type_info)
14086 {
14087   return new Type_info_expression(type, type_info);
14088 }
14089
14090 // An expression which evaluates to the offset of a field within a
14091 // struct.  This, like Type_info_expression, q.v., is only used to
14092 // initialize fields of a type descriptor.
14093
14094 class Struct_field_offset_expression : public Expression
14095 {
14096  public:
14097   Struct_field_offset_expression(Struct_type* type, const Struct_field* field)
14098     : Expression(EXPRESSION_STRUCT_FIELD_OFFSET,
14099                  Linemap::predeclared_location()),
14100       type_(type), field_(field)
14101   { }
14102
14103  protected:
14104   Type*
14105   do_type()
14106   { return Type::lookup_integer_type("uintptr"); }
14107
14108   void
14109   do_determine_type(const Type_context*)
14110   { }
14111
14112   Expression*
14113   do_copy()
14114   { return this; }
14115
14116   tree
14117   do_get_tree(Translate_context* context);
14118
14119   void
14120   do_dump_expression(Ast_dump_context*) const;
14121
14122  private:
14123   // The type of the struct.
14124   Struct_type* type_;
14125   // The field.
14126   const Struct_field* field_;
14127 };
14128
14129 // Return a struct field offset in GENERIC.
14130
14131 tree
14132 Struct_field_offset_expression::do_get_tree(Translate_context* context)
14133 {
14134   tree type_tree = type_to_tree(this->type_->get_backend(context->gogo()));
14135   if (type_tree == error_mark_node)
14136     return error_mark_node;
14137
14138   tree val_type_tree = type_to_tree(this->type()->get_backend(context->gogo()));
14139   go_assert(val_type_tree != error_mark_node);
14140
14141   const Struct_field_list* fields = this->type_->fields();
14142   tree struct_field_tree = TYPE_FIELDS(type_tree);
14143   Struct_field_list::const_iterator p;
14144   for (p = fields->begin();
14145        p != fields->end();
14146        ++p, struct_field_tree = DECL_CHAIN(struct_field_tree))
14147     {
14148       go_assert(struct_field_tree != NULL_TREE);
14149       if (&*p == this->field_)
14150         break;
14151     }
14152   go_assert(&*p == this->field_);
14153
14154   return fold_convert_loc(BUILTINS_LOCATION, val_type_tree,
14155                           byte_position(struct_field_tree));
14156 }
14157
14158 // Dump ast representation for a struct field offset expression.
14159
14160 void
14161 Struct_field_offset_expression::do_dump_expression(
14162     Ast_dump_context* ast_dump_context) const
14163 {
14164   ast_dump_context->ostream() <<  "unsafe.Offsetof(";
14165   ast_dump_context->dump_type(this->type_);
14166   ast_dump_context->ostream() << '.';
14167   ast_dump_context->ostream() <<
14168     Gogo::message_name(this->field_->field_name());
14169   ast_dump_context->ostream() << ")";
14170 }
14171
14172 // Make an expression for a struct field offset.
14173
14174 Expression*
14175 Expression::make_struct_field_offset(Struct_type* type,
14176                                      const Struct_field* field)
14177 {
14178   return new Struct_field_offset_expression(type, field);
14179 }
14180
14181 // An expression which evaluates to a pointer to the map descriptor of
14182 // a map type.
14183
14184 class Map_descriptor_expression : public Expression
14185 {
14186  public:
14187   Map_descriptor_expression(Map_type* type, Location location)
14188     : Expression(EXPRESSION_MAP_DESCRIPTOR, location),
14189       type_(type)
14190   { }
14191
14192  protected:
14193   Type*
14194   do_type()
14195   { return Type::make_pointer_type(Map_type::make_map_descriptor_type()); }
14196
14197   void
14198   do_determine_type(const Type_context*)
14199   { }
14200
14201   Expression*
14202   do_copy()
14203   { return this; }
14204
14205   tree
14206   do_get_tree(Translate_context* context)
14207   {
14208     return this->type_->map_descriptor_pointer(context->gogo(),
14209                                                this->location());
14210   }
14211
14212   void
14213   do_dump_expression(Ast_dump_context*) const;
14214
14215  private:
14216   // The type for which this is the descriptor.
14217   Map_type* type_;
14218 };
14219
14220 // Dump ast representation for a map descriptor expression.
14221
14222 void
14223 Map_descriptor_expression::do_dump_expression(
14224     Ast_dump_context* ast_dump_context) const
14225 {
14226   ast_dump_context->ostream() << "map_descriptor(";
14227   ast_dump_context->dump_type(this->type_);
14228   ast_dump_context->ostream() << ")";
14229 }
14230
14231 // Make a map descriptor expression.
14232
14233 Expression*
14234 Expression::make_map_descriptor(Map_type* type, Location location)
14235 {
14236   return new Map_descriptor_expression(type, location);
14237 }
14238
14239 // An expression which evaluates to the address of an unnamed label.
14240
14241 class Label_addr_expression : public Expression
14242 {
14243  public:
14244   Label_addr_expression(Label* label, Location location)
14245     : Expression(EXPRESSION_LABEL_ADDR, location),
14246       label_(label)
14247   { }
14248
14249  protected:
14250   Type*
14251   do_type()
14252   { return Type::make_pointer_type(Type::make_void_type()); }
14253
14254   void
14255   do_determine_type(const Type_context*)
14256   { }
14257
14258   Expression*
14259   do_copy()
14260   { return new Label_addr_expression(this->label_, this->location()); }
14261
14262   tree
14263   do_get_tree(Translate_context* context)
14264   {
14265     return expr_to_tree(this->label_->get_addr(context, this->location()));
14266   }
14267
14268   void
14269   do_dump_expression(Ast_dump_context* ast_dump_context) const
14270   { ast_dump_context->ostream() << this->label_->name(); }
14271
14272  private:
14273   // The label whose address we are taking.
14274   Label* label_;
14275 };
14276
14277 // Make an expression for the address of an unnamed label.
14278
14279 Expression*
14280 Expression::make_label_addr(Label* label, Location location)
14281 {
14282   return new Label_addr_expression(label, location);
14283 }
14284
14285 // Import an expression.  This comes at the end in order to see the
14286 // various class definitions.
14287
14288 Expression*
14289 Expression::import_expression(Import* imp)
14290 {
14291   int c = imp->peek_char();
14292   if (imp->match_c_string("- ")
14293       || imp->match_c_string("! ")
14294       || imp->match_c_string("^ "))
14295     return Unary_expression::do_import(imp);
14296   else if (c == '(')
14297     return Binary_expression::do_import(imp);
14298   else if (imp->match_c_string("true")
14299            || imp->match_c_string("false"))
14300     return Boolean_expression::do_import(imp);
14301   else if (c == '"')
14302     return String_expression::do_import(imp);
14303   else if (c == '-' || (c >= '0' && c <= '9'))
14304     {
14305       // This handles integers, floats and complex constants.
14306       return Integer_expression::do_import(imp);
14307     }
14308   else if (imp->match_c_string("nil"))
14309     return Nil_expression::do_import(imp);
14310   else if (imp->match_c_string("convert"))
14311     return Type_conversion_expression::do_import(imp);
14312   else
14313     {
14314       error_at(imp->location(), "import error: expected expression");
14315       return Expression::make_error(imp->location());
14316     }
14317 }
14318
14319 // Class Expression_list.
14320
14321 // Traverse the list.
14322
14323 int
14324 Expression_list::traverse(Traverse* traverse)
14325 {
14326   for (Expression_list::iterator p = this->begin();
14327        p != this->end();
14328        ++p)
14329     {
14330       if (*p != NULL)
14331         {
14332           if (Expression::traverse(&*p, traverse) == TRAVERSE_EXIT)
14333             return TRAVERSE_EXIT;
14334         }
14335     }
14336   return TRAVERSE_CONTINUE;
14337 }
14338
14339 // Copy the list.
14340
14341 Expression_list*
14342 Expression_list::copy()
14343 {
14344   Expression_list* ret = new Expression_list();
14345   for (Expression_list::iterator p = this->begin();
14346        p != this->end();
14347        ++p)
14348     {
14349       if (*p == NULL)
14350         ret->push_back(NULL);
14351       else
14352         ret->push_back((*p)->copy());
14353     }
14354   return ret;
14355 }
14356
14357 // Return whether an expression list has an error expression.
14358
14359 bool
14360 Expression_list::contains_error() const
14361 {
14362   for (Expression_list::const_iterator p = this->begin();
14363        p != this->end();
14364        ++p)
14365     if (*p != NULL && (*p)->is_error_expression())
14366       return true;
14367   return false;
14368 }