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 #include "tm.h"
  25 #include "tm_p.h"
  26
  27 #ifndef ENABLE_BUILD_WITH_CXX
  28 }
  29 #endif
  30
  31 #include "go-c.h"
  32 #include "gogo.h"
  33 #include "types.h"
  34 #include "export.h"
  35 #include "import.h"
  36 #include "statements.h"
  37 #include "lex.h"
  38 #include "expressions.h"
  39
  40 // Class Expression.
  41
  42 Expression::Expression(Expression_classification classification,
  43                        source_location location)
  44   : classification_(classification), location_(location)
  45 {
  46 }
  47
  48 Expression::~Expression()
  49 {
  50 }
  51
  52 // If this expression has a constant integer value, return it.
  53
  54 bool
  55 Expression::integer_constant_value(bool iota_is_constant, mpz_t val,
  56                                    Type** ptype) const
  57 {
  58   *ptype = NULL;
  59   return this->do_integer_constant_value(iota_is_constant, val, ptype);
  60 }
  61
  62 // If this expression has a constant floating point value, return it.
  63
  64 bool
  65 Expression::float_constant_value(mpfr_t val, Type** ptype) const
  66 {
  67   *ptype = NULL;
  68   if (this->do_float_constant_value(val, ptype))
  69     return true;
  70   mpz_t ival;
  71   mpz_init(ival);
  72   Type* t;
  73   bool ret;
  74   if (!this->do_integer_constant_value(false, ival, &t))
  75     ret = false;
  76   else
  77     {
  78       mpfr_set_z(val, ival, GMP_RNDN);
  79       ret = true;
  80     }
  81   mpz_clear(ival);
  82   return ret;
  83 }
  84
  85 // If this expression has a constant complex value, return it.
  86
  87 bool
  88 Expression::complex_constant_value(mpfr_t real, mpfr_t imag,
  89                                    Type** ptype) const
  90 {
  91   *ptype = NULL;
  92   if (this->do_complex_constant_value(real, imag, ptype))
  93     return true;
  94   Type *t;
  95   if (this->float_constant_value(real, &t))
  96     {
  97       mpfr_set_ui(imag, 0, GMP_RNDN);
  98       return true;
  99     }
 100   return false;
 101 }
 102
 103 // Traverse the expressions.
 104
 105 int
 106 Expression::traverse(Expression** pexpr, Traverse* traverse)
 107 {
 108   Expression* expr = *pexpr;
 109   if ((traverse->traverse_mask() & Traverse::traverse_expressions) != 0)
 110     {
 111       int t = traverse->expression(pexpr);
 112       if (t == TRAVERSE_EXIT)
 113         return TRAVERSE_EXIT;
 114       else if (t == TRAVERSE_SKIP_COMPONENTS)
 115         return TRAVERSE_CONTINUE;
 116     }
 117   return expr->do_traverse(traverse);
 118 }
 119
 120 // Traverse subexpressions of this expression.
 121
 122 int
 123 Expression::traverse_subexpressions(Traverse* traverse)
 124 {
 125   return this->do_traverse(traverse);
 126 }
 127
 128 // Default implementation for do_traverse for child classes.
 129
 130 int
 131 Expression::do_traverse(Traverse*)
 132 {
 133   return TRAVERSE_CONTINUE;
 134 }
 135
 136 // This virtual function is called by the parser if the value of this
 137 // expression is being discarded.  By default, we warn.  Expressions
 138 // with side effects override.
 139
 140 void
 141 Expression::do_discarding_value()
 142 {
 143   this->warn_about_unused_value();
 144 }
 145
 146 // This virtual function is called to export expressions.  This will
 147 // only be used by expressions which may be constant.
 148
 149 void
 150 Expression::do_export(Export*) const
 151 {
 152   gcc_unreachable();
 153 }
 154
 155 // Warn that the value of the expression is not used.
 156
 157 void
 158 Expression::warn_about_unused_value()
 159 {
 160   warning_at(this->location(), OPT_Wunused_value, "value computed is not used");
 161 }
 162
 163 // Note that this expression is an error.  This is called by children
 164 // when they discover an error.
 165
 166 void
 167 Expression::set_is_error()
 168 {
 169   this->classification_ = EXPRESSION_ERROR;
 170 }
 171
 172 // For children to call to report an error conveniently.
 173
 174 void
 175 Expression::report_error(const char* msg)
 176 {
 177   error_at(this->location_, "%s", msg);
 178   this->set_is_error();
 179 }
 180
 181 // Set types of variables and constants.  This is implemented by the
 182 // child class.
 183
 184 void
 185 Expression::determine_type(const Type_context* context)
 186 {
 187   this->do_determine_type(context);
 188 }
 189
 190 // Set types when there is no context.
 191
 192 void
 193 Expression::determine_type_no_context()
 194 {
 195   Type_context context;
 196   this->do_determine_type(&context);
 197 }
 198
 199 // Return a tree handling any conversions which must be done during
 200 // assignment.
 201
 202 tree
 203 Expression::convert_for_assignment(Translate_context* context, Type* lhs_type,
 204                                    Type* rhs_type, tree rhs_tree,
 205                                    source_location location)
 206 {
 207   if (lhs_type == rhs_type)
 208     return rhs_tree;
 209
 210   if (lhs_type->is_error_type() || rhs_type->is_error_type())
 211     return error_mark_node;
 212
 213   if (lhs_type->is_undefined() || rhs_type->is_undefined())
 214     {
 215       // Make sure we report the error.
 216       lhs_type->base();
 217       rhs_type->base();
 218       return error_mark_node;
 219     }
 220
 221   if (rhs_tree == error_mark_node || TREE_TYPE(rhs_tree) == error_mark_node)
 222     return error_mark_node;
 223
 224   Gogo* gogo = context->gogo();
 225
 226   tree lhs_type_tree = lhs_type->get_tree(gogo);
 227   if (lhs_type_tree == error_mark_node)
 228     return error_mark_node;
 229
 230   if (lhs_type->interface_type() != NULL)
 231     {
 232       if (rhs_type->interface_type() == NULL)
 233         return Expression::convert_type_to_interface(context, lhs_type,
 234                                                      rhs_type, rhs_tree,
 235                                                      location);
 236       else
 237         return Expression::convert_interface_to_interface(context, lhs_type,
 238                                                           rhs_type, rhs_tree,
 239                                                           false, location);
 240     }
 241   else if (rhs_type->interface_type() != NULL)
 242     return Expression::convert_interface_to_type(context, lhs_type, rhs_type,
 243                                                  rhs_tree, location);
 244   else if (lhs_type->is_open_array_type()
 245            && rhs_type->is_nil_type())
 246     {
 247       // Assigning nil to an open array.
 248       gcc_assert(TREE_CODE(lhs_type_tree) == RECORD_TYPE);
 249
 250       VEC(constructor_elt,gc)* init = VEC_alloc(constructor_elt, gc, 3);
 251
 252       constructor_elt* elt = VEC_quick_push(constructor_elt, init, NULL);
 253       tree field = TYPE_FIELDS(lhs_type_tree);
 254       gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)),
 255                         "__values") == 0);
 256       elt->index = field;
 257       elt->value = fold_convert(TREE_TYPE(field), null_pointer_node);
 258
 259       elt = VEC_quick_push(constructor_elt, init, NULL);
 260       field = DECL_CHAIN(field);
 261       gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)),
 262                         "__count") == 0);
 263       elt->index = field;
 264       elt->value = fold_convert(TREE_TYPE(field), integer_zero_node);
 265
 266       elt = VEC_quick_push(constructor_elt, init, NULL);
 267       field = DECL_CHAIN(field);
 268       gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)),
 269                         "__capacity") == 0);
 270       elt->index = field;
 271       elt->value = fold_convert(TREE_TYPE(field), integer_zero_node);
 272
 273       tree val = build_constructor(lhs_type_tree, init);
 274       TREE_CONSTANT(val) = 1;
 275
 276       return val;
 277     }
 278   else if (rhs_type->is_nil_type())
 279     {
 280       // The left hand side should be a pointer type at the tree
 281       // level.
 282       gcc_assert(POINTER_TYPE_P(lhs_type_tree));
 283       return fold_convert(lhs_type_tree, null_pointer_node);
 284     }
 285   else if (lhs_type_tree == TREE_TYPE(rhs_tree))
 286     {
 287       // No conversion is needed.
 288       return rhs_tree;
 289     }
 290   else if (POINTER_TYPE_P(lhs_type_tree)
 291            || INTEGRAL_TYPE_P(lhs_type_tree)
 292            || SCALAR_FLOAT_TYPE_P(lhs_type_tree)
 293            || COMPLEX_FLOAT_TYPE_P(lhs_type_tree))
 294     return fold_convert_loc(location, lhs_type_tree, rhs_tree);
 295   else if (TREE_CODE(lhs_type_tree) == RECORD_TYPE
 296            && TREE_CODE(TREE_TYPE(rhs_tree)) == RECORD_TYPE)
 297     {
 298       // This conversion must be permitted by Go, or we wouldn't have
 299       // gotten here.
 300       gcc_assert(int_size_in_bytes(lhs_type_tree)
 301                  == int_size_in_bytes(TREE_TYPE(rhs_tree)));
 302       return fold_build1_loc(location, VIEW_CONVERT_EXPR, lhs_type_tree,
 303                              rhs_tree);
 304     }
 305   else
 306     {
 307       gcc_assert(useless_type_conversion_p(lhs_type_tree, TREE_TYPE(rhs_tree)));
 308       return rhs_tree;
 309     }
 310 }
 311
 312 // Return a tree for a conversion from a non-interface type to an
 313 // interface type.
 314
 315 tree
 316 Expression::convert_type_to_interface(Translate_context* context,
 317                                       Type* lhs_type, Type* rhs_type,
 318                                       tree rhs_tree, source_location location)
 319 {
 320   Gogo* gogo = context->gogo();
 321   Interface_type* lhs_interface_type = lhs_type->interface_type();
 322   bool lhs_is_empty = lhs_interface_type->is_empty();
 323
 324   // Since RHS_TYPE is a static type, we can create the interface
 325   // method table at compile time.
 326
 327   // When setting an interface to nil, we just set both fields to
 328   // NULL.
 329   if (rhs_type->is_nil_type())
 330     return lhs_type->get_init_tree(gogo, false);
 331
 332   // This should have been checked already.
 333   gcc_assert(lhs_interface_type->implements_interface(rhs_type, NULL));
 334
 335   tree lhs_type_tree = lhs_type->get_tree(gogo);
 336   if (lhs_type_tree == error_mark_node)
 337     return error_mark_node;
 338
 339   // An interface is a tuple.  If LHS_TYPE is an empty interface type,
 340   // then the first field is the type descriptor for RHS_TYPE.
 341   // Otherwise it is the interface method table for RHS_TYPE.
 342   tree first_field_value;
 343   if (lhs_is_empty)
 344     first_field_value = rhs_type->type_descriptor_pointer(gogo);
 345   else
 346     {
 347       // Build the interface method table for this interface and this
 348       // object type: a list of function pointers for each interface
 349       // method.
 350       Named_type* rhs_named_type = rhs_type->named_type();
 351       bool is_pointer = false;
 352       if (rhs_named_type == NULL)
 353         {
 354           rhs_named_type = rhs_type->deref()->named_type();
 355           is_pointer = true;
 356         }
 357       tree method_table;
 358       if (rhs_named_type == NULL)
 359         method_table = null_pointer_node;
 360       else
 361         method_table =
 362           rhs_named_type->interface_method_table(gogo, lhs_interface_type,
 363                                                  is_pointer);
 364       first_field_value = fold_convert_loc(location, const_ptr_type_node,
 365                                            method_table);
 366     }
 367
 368   // Start building a constructor for the value we will return.
 369
 370   VEC(constructor_elt,gc)* init = VEC_alloc(constructor_elt, gc, 2);
 371
 372   constructor_elt* elt = VEC_quick_push(constructor_elt, init, NULL);
 373   tree field = TYPE_FIELDS(lhs_type_tree);
 374   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)),
 375                     (lhs_is_empty ? "__type_descriptor" : "__methods")) == 0);
 376   elt->index = field;
 377   elt->value = fold_convert_loc(location, TREE_TYPE(field), first_field_value);
 378
 379   elt = VEC_quick_push(constructor_elt, init, NULL);
 380   field = DECL_CHAIN(field);
 381   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__object") == 0);
 382   elt->index = field;
 383
 384   if (rhs_type->points_to() != NULL)
 385     {
 386       //  We are assigning a pointer to the interface; the interface
 387       // holds the pointer itself.
 388       elt->value = rhs_tree;
 389       return build_constructor(lhs_type_tree, init);
 390     }
 391
 392   // We are assigning a non-pointer value to the interface; the
 393   // interface gets a copy of the value in the heap.
 394
 395   tree object_size = TYPE_SIZE_UNIT(TREE_TYPE(rhs_tree));
 396
 397   tree space = gogo->allocate_memory(rhs_type, object_size, location);
 398   space = fold_convert_loc(location, build_pointer_type(TREE_TYPE(rhs_tree)),
 399                            space);
 400   space = save_expr(space);
 401
 402   tree ref = build_fold_indirect_ref_loc(location, space);
 403   TREE_THIS_NOTRAP(ref) = 1;
 404   tree set = fold_build2_loc(location, MODIFY_EXPR, void_type_node,
 405                              ref, rhs_tree);
 406
 407   elt->value = fold_convert_loc(location, TREE_TYPE(field), space);
 408
 409   return build2(COMPOUND_EXPR, lhs_type_tree, set,
 410                 build_constructor(lhs_type_tree, init));
 411 }
 412
 413 // Return a tree for the type descriptor of RHS_TREE, which has
 414 // interface type RHS_TYPE.  If RHS_TREE is nil the result will be
 415 // NULL.
 416
 417 tree
 418 Expression::get_interface_type_descriptor(Translate_context*,
 419                                           Type* rhs_type, tree rhs_tree,
 420                                           source_location location)
 421 {
 422   tree rhs_type_tree = TREE_TYPE(rhs_tree);
 423   gcc_assert(TREE_CODE(rhs_type_tree) == RECORD_TYPE);
 424   tree rhs_field = TYPE_FIELDS(rhs_type_tree);
 425   tree v = build3(COMPONENT_REF, TREE_TYPE(rhs_field), rhs_tree, rhs_field,
 426                   NULL_TREE);
 427   if (rhs_type->interface_type()->is_empty())
 428     {
 429       gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(rhs_field)),
 430                         "__type_descriptor") == 0);
 431       return v;
 432     }
 433
 434   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(rhs_field)), "__methods")
 435              == 0);
 436   gcc_assert(POINTER_TYPE_P(TREE_TYPE(v)));
 437   v = save_expr(v);
 438   tree v1 = build_fold_indirect_ref_loc(location, v);
 439   gcc_assert(TREE_CODE(TREE_TYPE(v1)) == RECORD_TYPE);
 440   tree f = TYPE_FIELDS(TREE_TYPE(v1));
 441   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(f)), "__type_descriptor")
 442              == 0);
 443   v1 = build3(COMPONENT_REF, TREE_TYPE(f), v1, f, NULL_TREE);
 444
 445   tree eq = fold_build2_loc(location, EQ_EXPR, boolean_type_node, v,
 446                             fold_convert_loc(location, TREE_TYPE(v),
 447                                              null_pointer_node));
 448   tree n = fold_convert_loc(location, TREE_TYPE(v1), null_pointer_node);
 449   return fold_build3_loc(location, COND_EXPR, TREE_TYPE(v1),
 450                          eq, n, v1);
 451 }
 452
 453 // Return a tree for the conversion of an interface type to an
 454 // interface type.
 455
 456 tree
 457 Expression::convert_interface_to_interface(Translate_context* context,
 458                                            Type *lhs_type, Type *rhs_type,
 459                                            tree rhs_tree, bool for_type_guard,
 460                                            source_location location)
 461 {
 462   Gogo* gogo = context->gogo();
 463   Interface_type* lhs_interface_type = lhs_type->interface_type();
 464   bool lhs_is_empty = lhs_interface_type->is_empty();
 465
 466   tree lhs_type_tree = lhs_type->get_tree(gogo);
 467   if (lhs_type_tree == error_mark_node)
 468     return error_mark_node;
 469
 470   // In the general case this requires runtime examination of the type
 471   // method table to match it up with the interface methods.
 472
 473   // FIXME: If all of the methods in the right hand side interface
 474   // also appear in the left hand side interface, then we don't need
 475   // to do a runtime check, although we still need to build a new
 476   // method table.
 477
 478   // Get the type descriptor for the right hand side.  This will be
 479   // NULL for a nil interface.
 480
 481   if (!DECL_P(rhs_tree))
 482     rhs_tree = save_expr(rhs_tree);
 483
 484   tree rhs_type_descriptor =
 485     Expression::get_interface_type_descriptor(context, rhs_type, rhs_tree,
 486                                               location);
 487
 488   // The result is going to be a two element constructor.
 489
 490   VEC(constructor_elt,gc)* init = VEC_alloc(constructor_elt, gc, 2);
 491
 492   constructor_elt* elt = VEC_quick_push(constructor_elt, init, NULL);
 493   tree field = TYPE_FIELDS(lhs_type_tree);
 494   elt->index = field;
 495
 496   if (for_type_guard)
 497     {
 498       // A type assertion fails when converting a nil interface.
 499       tree lhs_type_descriptor = lhs_type->type_descriptor_pointer(gogo);
 500       static tree assert_interface_decl;
 501       tree call = Gogo::call_builtin(&assert_interface_decl,
 502                                      location,
 503                                      "__go_assert_interface",
 504                                      2,
 505                                      ptr_type_node,
 506                                      TREE_TYPE(lhs_type_descriptor),
 507                                      lhs_type_descriptor,
 508                                      TREE_TYPE(rhs_type_descriptor),
 509                                      rhs_type_descriptor);
 510       // This will panic if the interface conversion fails.
 511       TREE_NOTHROW(assert_interface_decl) = 0;
 512       elt->value = fold_convert_loc(location, TREE_TYPE(field), call);
 513     }
 514   else if (lhs_is_empty)
 515     {
 516       // A convertion to an empty interface always succeeds, and the
 517       // first field is just the type descriptor of the object.
 518       gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)),
 519                         "__type_descriptor") == 0);
 520       gcc_assert(TREE_TYPE(field) == TREE_TYPE(rhs_type_descriptor));
 521       elt->value = rhs_type_descriptor;
 522     }
 523   else
 524     {
 525       // A conversion to a non-empty interface may fail, but unlike a
 526       // type assertion converting nil will always succeed.
 527       gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__methods")
 528                  == 0);
 529       tree lhs_type_descriptor = lhs_type->type_descriptor_pointer(gogo);
 530       static tree convert_interface_decl;
 531       tree call = Gogo::call_builtin(&convert_interface_decl,
 532                                      location,
 533                                      "__go_convert_interface",
 534                                      2,
 535                                      ptr_type_node,
 536                                      TREE_TYPE(lhs_type_descriptor),
 537                                      lhs_type_descriptor,
 538                                      TREE_TYPE(rhs_type_descriptor),
 539                                      rhs_type_descriptor);
 540       // This will panic if the interface conversion fails.
 541       TREE_NOTHROW(convert_interface_decl) = 0;
 542       elt->value = fold_convert_loc(location, TREE_TYPE(field), call);
 543     }
 544
 545   // The second field is simply the object pointer.
 546
 547   elt = VEC_quick_push(constructor_elt, init, NULL);
 548   field = DECL_CHAIN(field);
 549   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__object") == 0);
 550   elt->index = field;
 551
 552   tree rhs_type_tree = TREE_TYPE(rhs_tree);
 553   gcc_assert(TREE_CODE(rhs_type_tree) == RECORD_TYPE);
 554   tree rhs_field = DECL_CHAIN(TYPE_FIELDS(rhs_type_tree));
 555   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(rhs_field)), "__object") == 0);
 556   elt->value = build3(COMPONENT_REF, TREE_TYPE(rhs_field), rhs_tree, rhs_field,
 557                       NULL_TREE);
 558
 559   return build_constructor(lhs_type_tree, init);
 560 }
 561
 562 // Return a tree for the conversion of an interface type to a
 563 // non-interface type.
 564
 565 tree
 566 Expression::convert_interface_to_type(Translate_context* context,
 567                                       Type *lhs_type, Type* rhs_type,
 568                                       tree rhs_tree, source_location location)
 569 {
 570   Gogo* gogo = context->gogo();
 571   tree rhs_type_tree = TREE_TYPE(rhs_tree);
 572
 573   tree lhs_type_tree = lhs_type->get_tree(gogo);
 574   if (lhs_type_tree == error_mark_node)
 575     return error_mark_node;
 576
 577   // Call a function to check that the type is valid.  The function
 578   // will panic with an appropriate runtime type error if the type is
 579   // not valid.
 580
 581   tree lhs_type_descriptor = lhs_type->type_descriptor_pointer(gogo);
 582
 583   if (!DECL_P(rhs_tree))
 584     rhs_tree = save_expr(rhs_tree);
 585
 586   tree rhs_type_descriptor =
 587     Expression::get_interface_type_descriptor(context, rhs_type, rhs_tree,
 588                                               location);
 589
 590   tree rhs_inter_descriptor = rhs_type->type_descriptor_pointer(gogo);
 591
 592   static tree check_interface_type_decl;
 593   tree call = Gogo::call_builtin(&check_interface_type_decl,
 594                                  location,
 595                                  "__go_check_interface_type",
 596                                  3,
 597                                  void_type_node,
 598                                  TREE_TYPE(lhs_type_descriptor),
 599                                  lhs_type_descriptor,
 600                                  TREE_TYPE(rhs_type_descriptor),
 601                                  rhs_type_descriptor,
 602                                  TREE_TYPE(rhs_inter_descriptor),
 603                                  rhs_inter_descriptor);
 604   // This call will panic if the conversion is invalid.
 605   TREE_NOTHROW(check_interface_type_decl) = 0;
 606
 607   // If the call succeeds, pull out the value.
 608   gcc_assert(TREE_CODE(rhs_type_tree) == RECORD_TYPE);
 609   tree rhs_field = DECL_CHAIN(TYPE_FIELDS(rhs_type_tree));
 610   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(rhs_field)), "__object") == 0);
 611   tree val = build3(COMPONENT_REF, TREE_TYPE(rhs_field), rhs_tree, rhs_field,
 612                     NULL_TREE);
 613
 614   // If the value is a pointer, then it is the value we want.
 615   // Otherwise it points to the value.
 616   if (lhs_type->points_to() == NULL)
 617     {
 618       val = fold_convert_loc(location, build_pointer_type(lhs_type_tree), val);
 619       val = build_fold_indirect_ref_loc(location, val);
 620     }
 621
 622   return build2(COMPOUND_EXPR, lhs_type_tree, call,
 623                 fold_convert_loc(location, lhs_type_tree, val));
 624 }
 625
 626 // Convert an expression to a tree.  This is implemented by the child
 627 // class.  Not that it is not in general safe to call this multiple
 628 // times for a single expression, but that we don't catch such errors.
 629
 630 tree
 631 Expression::get_tree(Translate_context* context)
 632 {
 633   // The child may have marked this expression as having an error.
 634   if (this->classification_ == EXPRESSION_ERROR)
 635     return error_mark_node;
 636
 637   return this->do_get_tree(context);
 638 }
 639
 640 // Return a tree for VAL in TYPE.
 641
 642 tree
 643 Expression::integer_constant_tree(mpz_t val, tree type)
 644 {
 645   if (type == error_mark_node)
 646     return error_mark_node;
 647   else if (TREE_CODE(type) == INTEGER_TYPE)
 648     return double_int_to_tree(type,
 649                               mpz_get_double_int(type, val, true));
 650   else if (TREE_CODE(type) == REAL_TYPE)
 651     {
 652       mpfr_t fval;
 653       mpfr_init_set_z(fval, val, GMP_RNDN);
 654       tree ret = Expression::float_constant_tree(fval, type);
 655       mpfr_clear(fval);
 656       return ret;
 657     }
 658   else if (TREE_CODE(type) == COMPLEX_TYPE)
 659     {
 660       mpfr_t fval;
 661       mpfr_init_set_z(fval, val, GMP_RNDN);
 662       tree real = Expression::float_constant_tree(fval, TREE_TYPE(type));
 663       mpfr_clear(fval);
 664       tree imag = build_real_from_int_cst(TREE_TYPE(type),
 665                                           integer_zero_node);
 666       return build_complex(type, real, imag);
 667     }
 668   else
 669     gcc_unreachable();
 670 }
 671
 672 // Return a tree for VAL in TYPE.
 673
 674 tree
 675 Expression::float_constant_tree(mpfr_t val, tree type)
 676 {
 677   if (type == error_mark_node)
 678     return error_mark_node;
 679   else if (TREE_CODE(type) == INTEGER_TYPE)
 680     {
 681       mpz_t ival;
 682       mpz_init(ival);
 683       mpfr_get_z(ival, val, GMP_RNDN);
 684       tree ret = Expression::integer_constant_tree(ival, type);
 685       mpz_clear(ival);
 686       return ret;
 687     }
 688   else if (TREE_CODE(type) == REAL_TYPE)
 689     {
 690       REAL_VALUE_TYPE r1;
 691       real_from_mpfr(&r1, val, type, GMP_RNDN);
 692       REAL_VALUE_TYPE r2;
 693       real_convert(&r2, TYPE_MODE(type), &r1);
 694       return build_real(type, r2);
 695     }
 696   else if (TREE_CODE(type) == COMPLEX_TYPE)
 697     {
 698       REAL_VALUE_TYPE r1;
 699       real_from_mpfr(&r1, val, TREE_TYPE(type), GMP_RNDN);
 700       REAL_VALUE_TYPE r2;
 701       real_convert(&r2, TYPE_MODE(TREE_TYPE(type)), &r1);
 702       tree imag = build_real_from_int_cst(TREE_TYPE(type),
 703                                           integer_zero_node);
 704       return build_complex(type, build_real(TREE_TYPE(type), r2), imag);
 705     }
 706   else
 707     gcc_unreachable();
 708 }
 709
 710 // Return a tree for REAL/IMAG in TYPE.
 711
 712 tree
 713 Expression::complex_constant_tree(mpfr_t real, mpfr_t imag, tree type)
 714 {
 715   if (TREE_CODE(type) == COMPLEX_TYPE)
 716     {
 717       REAL_VALUE_TYPE r1;
 718       real_from_mpfr(&r1, real, TREE_TYPE(type), GMP_RNDN);
 719       REAL_VALUE_TYPE r2;
 720       real_convert(&r2, TYPE_MODE(TREE_TYPE(type)), &r1);
 721
 722       REAL_VALUE_TYPE r3;
 723       real_from_mpfr(&r3, imag, TREE_TYPE(type), GMP_RNDN);
 724       REAL_VALUE_TYPE r4;
 725       real_convert(&r4, TYPE_MODE(TREE_TYPE(type)), &r3);
 726
 727       return build_complex(type, build_real(TREE_TYPE(type), r2),
 728                            build_real(TREE_TYPE(type), r4));
 729     }
 730   else
 731     gcc_unreachable();
 732 }
 733
 734 // Return a tree which evaluates to true if VAL, of arbitrary integer
 735 // type, is negative or is more than the maximum value of BOUND_TYPE.
 736 // If SOFAR is not NULL, it is or'red into the result.  The return
 737 // value may be NULL if SOFAR is NULL.
 738
 739 tree
 740 Expression::check_bounds(tree val, tree bound_type, tree sofar,
 741                          source_location loc)
 742 {
 743   tree val_type = TREE_TYPE(val);
 744   tree ret = NULL_TREE;
 745
 746   if (!TYPE_UNSIGNED(val_type))
 747     {
 748       ret = fold_build2_loc(loc, LT_EXPR, boolean_type_node, val,
 749                             build_int_cst(val_type, 0));
 750       if (ret == boolean_false_node)
 751         ret = NULL_TREE;
 752     }
 753
 754   if ((TYPE_UNSIGNED(val_type) && !TYPE_UNSIGNED(bound_type))
 755       || TYPE_SIZE(val_type) > TYPE_SIZE(bound_type))
 756     {
 757       tree max = TYPE_MAX_VALUE(bound_type);
 758       tree big = fold_build2_loc(loc, GT_EXPR, boolean_type_node, val,
 759                                  fold_convert_loc(loc, val_type, max));
 760       if (big == boolean_false_node)
 761         ;
 762       else if (ret == NULL_TREE)
 763         ret = big;
 764       else
 765         ret = fold_build2_loc(loc, TRUTH_OR_EXPR, boolean_type_node,
 766                               ret, big);
 767     }
 768
 769   if (ret == NULL_TREE)
 770     return sofar;
 771   else if (sofar == NULL_TREE)
 772     return ret;
 773   else
 774     return fold_build2_loc(loc, TRUTH_OR_EXPR, boolean_type_node,
 775                            sofar, ret);
 776 }
 777
 778 // Error expressions.  This are used to avoid cascading errors.
 779
 780 class Error_expression : public Expression
 781 {
 782  public:
 783   Error_expression(source_location location)
 784     : Expression(EXPRESSION_ERROR, location)
 785   { }
 786
 787  protected:
 788   bool
 789   do_is_constant() const
 790   { return true; }
 791
 792   bool
 793   do_integer_constant_value(bool, mpz_t val, Type**) const
 794   {
 795     mpz_set_ui(val, 0);
 796     return true;
 797   }
 798
 799   bool
 800   do_float_constant_value(mpfr_t val, Type**) const
 801   {
 802     mpfr_set_ui(val, 0, GMP_RNDN);
 803     return true;
 804   }
 805
 806   bool
 807   do_complex_constant_value(mpfr_t real, mpfr_t imag, Type**) const
 808   {
 809     mpfr_set_ui(real, 0, GMP_RNDN);
 810     mpfr_set_ui(imag, 0, GMP_RNDN);
 811     return true;
 812   }
 813
 814   void
 815   do_discarding_value()
 816   { }
 817
 818   Type*
 819   do_type()
 820   { return Type::make_error_type(); }
 821
 822   void
 823   do_determine_type(const Type_context*)
 824   { }
 825
 826   Expression*
 827   do_copy()
 828   { return this; }
 829
 830   bool
 831   do_is_addressable() const
 832   { return true; }
 833
 834   tree
 835   do_get_tree(Translate_context*)
 836   { return error_mark_node; }
 837 };
 838
 839 Expression*
 840 Expression::make_error(source_location location)
 841 {
 842   return new Error_expression(location);
 843 }
 844
 845 // An expression which is really a type.  This is used during parsing.
 846 // It is an error if these survive after lowering.
 847
 848 class
 849 Type_expression : public Expression
 850 {
 851  public:
 852   Type_expression(Type* type, source_location location)
 853     : Expression(EXPRESSION_TYPE, location),
 854       type_(type)
 855   { }
 856
 857  protected:
 858   int
 859   do_traverse(Traverse* traverse)
 860   { return Type::traverse(this->type_, traverse); }
 861
 862   Type*
 863   do_type()
 864   { return this->type_; }
 865
 866   void
 867   do_determine_type(const Type_context*)
 868   { }
 869
 870   void
 871   do_check_types(Gogo*)
 872   { this->report_error(_("invalid use of type")); }
 873
 874   Expression*
 875   do_copy()
 876   { return this; }
 877
 878   tree
 879   do_get_tree(Translate_context*)
 880   { gcc_unreachable(); }
 881
 882  private:
 883   // The type which we are representing as an expression.
 884   Type* type_;
 885 };
 886
 887 Expression*
 888 Expression::make_type(Type* type, source_location location)
 889 {
 890   return new Type_expression(type, location);
 891 }
 892
 893 // Class Var_expression.
 894
 895 // Lower a variable expression.  Here we just make sure that the
 896 // initialization expression of the variable has been lowered.  This
 897 // ensures that we will be able to determine the type of the variable
 898 // if necessary.
 899
 900 Expression*
 901 Var_expression::do_lower(Gogo* gogo, Named_object* function, int)
 902 {
 903   if (this->variable_->is_variable())
 904     {
 905       Variable* var = this->variable_->var_value();
 906       // This is either a local variable or a global variable.  A
 907       // reference to a variable which is local to an enclosing
 908       // function will be a reference to a field in a closure.
 909       if (var->is_global())
 910         function = NULL;
 911       var->lower_init_expression(gogo, function);
 912     }
 913   return this;
 914 }
 915
 916 // Return the name of the variable.
 917
 918 const std::string&
 919 Var_expression::name() const
 920 {
 921   return this->variable_->name();
 922 }
 923
 924 // Return the type of a reference to a variable.
 925
 926 Type*
 927 Var_expression::do_type()
 928 {
 929   if (this->variable_->is_variable())
 930     return this->variable_->var_value()->type();
 931   else if (this->variable_->is_result_variable())
 932     return this->variable_->result_var_value()->type();
 933   else
 934     gcc_unreachable();
 935 }
 936
 937 // Something takes the address of this variable.  This means that we
 938 // may want to move the variable onto the heap.
 939
 940 void
 941 Var_expression::do_address_taken(bool escapes)
 942 {
 943   if (!escapes)
 944     ;
 945   else if (this->variable_->is_variable())
 946     this->variable_->var_value()->set_address_taken();
 947   else if (this->variable_->is_result_variable())
 948     this->variable_->result_var_value()->set_address_taken();
 949   else
 950     gcc_unreachable();
 951 }
 952
 953 // Get the tree for a reference to a variable.
 954
 955 tree
 956 Var_expression::do_get_tree(Translate_context* context)
 957 {
 958   return this->variable_->get_tree(context->gogo(), context->function());
 959 }
 960
 961 // Make a reference to a variable in an expression.
 962
 963 Expression*
 964 Expression::make_var_reference(Named_object* var, source_location location)
 965 {
 966   if (var->is_sink())
 967     return Expression::make_sink(location);
 968
 969   // FIXME: Creating a new object for each reference to a variable is
 970   // wasteful.
 971   return new Var_expression(var, location);
 972 }
 973
 974 // Class Temporary_reference_expression.
 975
 976 // The type.
 977
 978 Type*
 979 Temporary_reference_expression::do_type()
 980 {
 981   return this->statement_->type();
 982 }
 983
 984 // Called if something takes the address of this temporary variable.
 985 // We never have to move temporary variables to the heap, but we do
 986 // need to know that they must live in the stack rather than in a
 987 // register.
 988
 989 void
 990 Temporary_reference_expression::do_address_taken(bool)
 991 {
 992   this->statement_->set_is_address_taken();
 993 }
 994
 995 // Get a tree referring to the variable.
 996
 997 tree
 998 Temporary_reference_expression::do_get_tree(Translate_context*)
 999 {
1000   return this->statement_->get_decl();
1001 }
1002
1003 // Make a reference to a temporary variable.
1004
1005 Expression*
1006 Expression::make_temporary_reference(Temporary_statement* statement,
1007                                      source_location location)
1008 {
1009   return new Temporary_reference_expression(statement, location);
1010 }
1011
1012 // A sink expression--a use of the blank identifier _.
1013
1014 class Sink_expression : public Expression
1015 {
1016  public:
1017   Sink_expression(source_location location)
1018     : Expression(EXPRESSION_SINK, location),
1019       type_(NULL), var_(NULL_TREE)
1020   { }
1021
1022  protected:
1023   void
1024   do_discarding_value()
1025   { }
1026
1027   Type*
1028   do_type();
1029
1030   void
1031   do_determine_type(const Type_context*);
1032
1033   Expression*
1034   do_copy()
1035   { return new Sink_expression(this->location()); }
1036
1037   tree
1038   do_get_tree(Translate_context*);
1039
1040  private:
1041   // The type of this sink variable.
1042   Type* type_;
1043   // The temporary variable we generate.
1044   tree var_;
1045 };
1046
1047 // Return the type of a sink expression.
1048
1049 Type*
1050 Sink_expression::do_type()
1051 {
1052   if (this->type_ == NULL)
1053     return Type::make_sink_type();
1054   return this->type_;
1055 }
1056
1057 // Determine the type of a sink expression.
1058
1059 void
1060 Sink_expression::do_determine_type(const Type_context* context)
1061 {
1062   if (context->type != NULL)
1063     this->type_ = context->type;
1064 }
1065
1066 // Return a temporary variable for a sink expression.  This will
1067 // presumably be a write-only variable which the middle-end will drop.
1068
1069 tree
1070 Sink_expression::do_get_tree(Translate_context* context)
1071 {
1072   if (this->var_ == NULL_TREE)
1073     {
1074       gcc_assert(this->type_ != NULL && !this->type_->is_sink_type());
1075       this->var_ = create_tmp_var(this->type_->get_tree(context->gogo()),
1076                                   "blank");
1077     }
1078   return this->var_;
1079 }
1080
1081 // Make a sink expression.
1082
1083 Expression*
1084 Expression::make_sink(source_location location)
1085 {
1086   return new Sink_expression(location);
1087 }
1088
1089 // Class Func_expression.
1090
1091 // FIXME: Can a function expression appear in a constant expression?
1092 // The value is unchanging.  Initializing a constant to the address of
1093 // a function seems like it could work, though there might be little
1094 // point to it.
1095
1096 // Return the name of the function.
1097
1098 const std::string&
1099 Func_expression::name() const
1100 {
1101   return this->function_->name();
1102 }
1103
1104 // Traversal.
1105
1106 int
1107 Func_expression::do_traverse(Traverse* traverse)
1108 {
1109   return (this->closure_ == NULL
1110           ? TRAVERSE_CONTINUE
1111           : Expression::traverse(&this->closure_, traverse));
1112 }
1113
1114 // Return the type of a function expression.
1115
1116 Type*
1117 Func_expression::do_type()
1118 {
1119   if (this->function_->is_function())
1120     return this->function_->func_value()->type();
1121   else if (this->function_->is_function_declaration())
1122     return this->function_->func_declaration_value()->type();
1123   else
1124     gcc_unreachable();
1125 }
1126
1127 // Get the tree for a function expression without evaluating the
1128 // closure.
1129
1130 tree
1131 Func_expression::get_tree_without_closure(Gogo* gogo)
1132 {
1133   Function_type* fntype;
1134   if (this->function_->is_function())
1135     fntype = this->function_->func_value()->type();
1136   else if (this->function_->is_function_declaration())
1137     fntype = this->function_->func_declaration_value()->type();
1138   else
1139     gcc_unreachable();
1140
1141   // Builtin functions are handled specially by Call_expression.  We
1142   // can't take their address.
1143   if (fntype->is_builtin())
1144     {
1145       error_at(this->location(), "invalid use of special builtin function %qs",
1146                this->function_->name().c_str());
1147       return error_mark_node;
1148     }
1149
1150   Named_object* no = this->function_;
1151   tree id = this->function_->get_id(gogo);
1152   tree fndecl;
1153   if (no->is_function())
1154     fndecl = no->func_value()->get_or_make_decl(gogo, no, id);
1155   else if (no->is_function_declaration())
1156     fndecl = no->func_declaration_value()->get_or_make_decl(gogo, no, id);
1157   else
1158     gcc_unreachable();
1159
1160   return build_fold_addr_expr_loc(this->location(), fndecl);
1161 }
1162
1163 // Get the tree for a function expression.  This is used when we take
1164 // the address of a function rather than simply calling it.  If the
1165 // function has a closure, we must use a trampoline.
1166
1167 tree
1168 Func_expression::do_get_tree(Translate_context* context)
1169 {
1170   Gogo* gogo = context->gogo();
1171
1172   tree fnaddr = this->get_tree_without_closure(gogo);
1173   if (fnaddr == error_mark_node)
1174     return error_mark_node;
1175
1176   gcc_assert(TREE_CODE(fnaddr) == ADDR_EXPR
1177              && TREE_CODE(TREE_OPERAND(fnaddr, 0)) == FUNCTION_DECL);
1178   TREE_ADDRESSABLE(TREE_OPERAND(fnaddr, 0)) = 1;
1179
1180   // For a normal non-nested function call, that is all we have to do.
1181   if (!this->function_->is_function()
1182       || this->function_->func_value()->enclosing() == NULL)
1183     {
1184       gcc_assert(this->closure_ == NULL);
1185       return fnaddr;
1186     }
1187
1188   // For a nested function call, we have to always allocate a
1189   // trampoline.  If we don't always allocate, then closures will not
1190   // be reliably distinct.
1191   Expression* closure = this->closure_;
1192   tree closure_tree;
1193   if (closure == NULL)
1194     closure_tree = null_pointer_node;
1195   else
1196     {
1197       // Get the value of the closure.  This will be a pointer to
1198       // space allocated on the heap.
1199       closure_tree = closure->get_tree(context);
1200       if (closure_tree == error_mark_node)
1201         return error_mark_node;
1202       gcc_assert(POINTER_TYPE_P(TREE_TYPE(closure_tree)));
1203     }
1204
1205   // Now we need to build some code on the heap.  This code will load
1206   // the static chain pointer with the closure and then jump to the
1207   // body of the function.  The normal gcc approach is to build the
1208   // code on the stack.  Unfortunately we can not do that, as Go
1209   // permits us to return the function pointer.
1210
1211   return gogo->make_trampoline(fnaddr, closure_tree, this->location());
1212 }
1213
1214 // Make a reference to a function in an expression.
1215
1216 Expression*
1217 Expression::make_func_reference(Named_object* function, Expression* closure,
1218                                 source_location location)
1219 {
1220   return new Func_expression(function, closure, location);
1221 }
1222
1223 // Class Unknown_expression.
1224
1225 // Return the name of an unknown expression.
1226
1227 const std::string&
1228 Unknown_expression::name() const
1229 {
1230   return this->named_object_->name();
1231 }
1232
1233 // Lower a reference to an unknown name.
1234
1235 Expression*
1236 Unknown_expression::do_lower(Gogo*, Named_object*, int)
1237 {
1238   source_location location = this->location();
1239   Named_object* no = this->named_object_;
1240   Named_object* real = no->unknown_value()->real_named_object();
1241   if (real == NULL)
1242     {
1243       if (this->is_composite_literal_key_)
1244         return this;
1245       error_at(location, "reference to undefined name %qs",
1246                this->named_object_->message_name().c_str());
1247       return Expression::make_error(location);
1248     }
1249   switch (real->classification())
1250     {
1251     case Named_object::NAMED_OBJECT_CONST:
1252       return Expression::make_const_reference(real, location);
1253     case Named_object::NAMED_OBJECT_TYPE:
1254       return Expression::make_type(real->type_value(), location);
1255     case Named_object::NAMED_OBJECT_TYPE_DECLARATION:
1256       if (this->is_composite_literal_key_)
1257         return this;
1258       error_at(location, "reference to undefined type %qs",
1259                real->message_name().c_str());
1260       return Expression::make_error(location);
1261     case Named_object::NAMED_OBJECT_VAR:
1262       return Expression::make_var_reference(real, location);
1263     case Named_object::NAMED_OBJECT_FUNC:
1264     case Named_object::NAMED_OBJECT_FUNC_DECLARATION:
1265       return Expression::make_func_reference(real, NULL, location);
1266     case Named_object::NAMED_OBJECT_PACKAGE:
1267       if (this->is_composite_literal_key_)
1268         return this;
1269       error_at(location, "unexpected reference to package");
1270       return Expression::make_error(location);
1271     default:
1272       gcc_unreachable();
1273     }
1274 }
1275
1276 // Make a reference to an unknown name.
1277
1278 Expression*
1279 Expression::make_unknown_reference(Named_object* no, source_location location)
1280 {
1281   gcc_assert(no->resolve()->is_unknown());
1282   return new Unknown_expression(no, location);
1283 }
1284
1285 // A boolean expression.
1286
1287 class Boolean_expression : public Expression
1288 {
1289  public:
1290   Boolean_expression(bool val, source_location location)
1291     : Expression(EXPRESSION_BOOLEAN, location),
1292       val_(val), type_(NULL)
1293   { }
1294
1295   static Expression*
1296   do_import(Import*);
1297
1298  protected:
1299   bool
1300   do_is_constant() const
1301   { return true; }
1302
1303   Type*
1304   do_type();
1305
1306   void
1307   do_determine_type(const Type_context*);
1308
1309   Expression*
1310   do_copy()
1311   { return this; }
1312
1313   tree
1314   do_get_tree(Translate_context*)
1315   { return this->val_ ? boolean_true_node : boolean_false_node; }
1316
1317   void
1318   do_export(Export* exp) const
1319   { exp->write_c_string(this->val_ ? "true" : "false"); }
1320
1321  private:
1322   // The constant.
1323   bool val_;
1324   // The type as determined by context.
1325   Type* type_;
1326 };
1327
1328 // Get the type.
1329
1330 Type*
1331 Boolean_expression::do_type()
1332 {
1333   if (this->type_ == NULL)
1334     this->type_ = Type::make_boolean_type();
1335   return this->type_;
1336 }
1337
1338 // Set the type from the context.
1339
1340 void
1341 Boolean_expression::do_determine_type(const Type_context* context)
1342 {
1343   if (this->type_ != NULL && !this->type_->is_abstract())
1344     ;
1345   else if (context->type != NULL && context->type->is_boolean_type())
1346     this->type_ = context->type;
1347   else if (!context->may_be_abstract)
1348     this->type_ = Type::lookup_bool_type();
1349 }
1350
1351 // Import a boolean constant.
1352
1353 Expression*
1354 Boolean_expression::do_import(Import* imp)
1355 {
1356   if (imp->peek_char() == 't')
1357     {
1358       imp->require_c_string("true");
1359       return Expression::make_boolean(true, imp->location());
1360     }
1361   else
1362     {
1363       imp->require_c_string("false");
1364       return Expression::make_boolean(false, imp->location());
1365     }
1366 }
1367
1368 // Make a boolean expression.
1369
1370 Expression*
1371 Expression::make_boolean(bool val, source_location location)
1372 {
1373   return new Boolean_expression(val, location);
1374 }
1375
1376 // Class String_expression.
1377
1378 // Get the type.
1379
1380 Type*
1381 String_expression::do_type()
1382 {
1383   if (this->type_ == NULL)
1384     this->type_ = Type::make_string_type();
1385   return this->type_;
1386 }
1387
1388 // Set the type from the context.
1389
1390 void
1391 String_expression::do_determine_type(const Type_context* context)
1392 {
1393   if (this->type_ != NULL && !this->type_->is_abstract())
1394     ;
1395   else if (context->type != NULL && context->type->is_string_type())
1396     this->type_ = context->type;
1397   else if (!context->may_be_abstract)
1398     this->type_ = Type::lookup_string_type();
1399 }
1400
1401 // Build a string constant.
1402
1403 tree
1404 String_expression::do_get_tree(Translate_context* context)
1405 {
1406   return context->gogo()->go_string_constant_tree(this->val_);
1407 }
1408
1409 // Export a string expression.
1410
1411 void
1412 String_expression::do_export(Export* exp) const
1413 {
1414   std::string s;
1415   s.reserve(this->val_.length() * 4 + 2);
1416   s += '"';
1417   for (std::string::const_iterator p = this->val_.begin();
1418        p != this->val_.end();
1419        ++p)
1420     {
1421       if (*p == '\\' || *p == '"')
1422         {
1423           s += '\\';
1424           s += *p;
1425         }
1426       else if (*p >= 0x20 && *p < 0x7f)
1427         s += *p;
1428       else if (*p == '\n')
1429         s += "\\n";
1430       else if (*p == '\t')
1431         s += "\\t";
1432       else
1433         {
1434           s += "\\x";
1435           unsigned char c = *p;
1436           unsigned int dig = c >> 4;
1437           s += dig < 10 ? '0' + dig : 'A' + dig - 10;
1438           dig = c & 0xf;
1439           s += dig < 10 ? '0' + dig : 'A' + dig - 10;
1440         }
1441     }
1442   s += '"';
1443   exp->write_string(s);
1444 }
1445
1446 // Import a string expression.
1447
1448 Expression*
1449 String_expression::do_import(Import* imp)
1450 {
1451   imp->require_c_string("\"");
1452   std::string val;
1453   while (true)
1454     {
1455       int c = imp->get_char();
1456       if (c == '"' || c == -1)
1457         break;
1458       if (c != '\\')
1459         val += static_cast<char>(c);
1460       else
1461         {
1462           c = imp->get_char();
1463           if (c == '\\' || c == '"')
1464             val += static_cast<char>(c);
1465           else if (c == 'n')
1466             val += '\n';
1467           else if (c == 't')
1468             val += '\t';
1469           else if (c == 'x')
1470             {
1471               c = imp->get_char();
1472               unsigned int vh = c >= '0' && c <= '9' ? c - '0' : c - 'A' + 10;
1473               c = imp->get_char();
1474               unsigned int vl = c >= '0' && c <= '9' ? c - '0' : c - 'A' + 10;
1475               char v = (vh << 4) | vl;
1476               val += v;
1477             }
1478           else
1479             {
1480               error_at(imp->location(), "bad string constant");
1481               return Expression::make_error(imp->location());
1482             }
1483         }
1484     }
1485   return Expression::make_string(val, imp->location());
1486 }
1487
1488 // Make a string expression.
1489
1490 Expression*
1491 Expression::make_string(const std::string& val, source_location location)
1492 {
1493   return new String_expression(val, location);
1494 }
1495
1496 // Make an integer expression.
1497
1498 class Integer_expression : public Expression
1499 {
1500  public:
1501   Integer_expression(const mpz_t* val, Type* type, source_location location)
1502     : Expression(EXPRESSION_INTEGER, location),
1503       type_(type)
1504   { mpz_init_set(this->val_, *val); }
1505
1506   static Expression*
1507   do_import(Import*);
1508
1509   // Return whether VAL fits in the type.
1510   static bool
1511   check_constant(mpz_t val, Type*, source_location);
1512
1513   // Write VAL to export data.
1514   static void
1515   export_integer(Export* exp, const mpz_t val);
1516
1517  protected:
1518   bool
1519   do_is_constant() const
1520   { return true; }
1521
1522   bool
1523   do_integer_constant_value(bool, mpz_t val, Type** ptype) const;
1524
1525   Type*
1526   do_type();
1527
1528   void
1529   do_determine_type(const Type_context* context);
1530
1531   void
1532   do_check_types(Gogo*);
1533
1534   tree
1535   do_get_tree(Translate_context*);
1536
1537   Expression*
1538   do_copy()
1539   { return Expression::make_integer(&this->val_, this->type_,
1540                                     this->location()); }
1541
1542   void
1543   do_export(Export*) const;
1544
1545  private:
1546   // The integer value.
1547   mpz_t val_;
1548   // The type so far.
1549   Type* type_;
1550 };
1551
1552 // Return an integer constant value.
1553
1554 bool
1555 Integer_expression::do_integer_constant_value(bool, mpz_t val,
1556                                               Type** ptype) const
1557 {
1558   if (this->type_ != NULL)
1559     *ptype = this->type_;
1560   mpz_set(val, this->val_);
1561   return true;
1562 }
1563
1564 // Return the current type.  If we haven't set the type yet, we return
1565 // an abstract integer type.
1566
1567 Type*
1568 Integer_expression::do_type()
1569 {
1570   if (this->type_ == NULL)
1571     this->type_ = Type::make_abstract_integer_type();
1572   return this->type_;
1573 }
1574
1575 // Set the type of the integer value.  Here we may switch from an
1576 // abstract type to a real type.
1577
1578 void
1579 Integer_expression::do_determine_type(const Type_context* context)
1580 {
1581   if (this->type_ != NULL && !this->type_->is_abstract())
1582     ;
1583   else if (context->type != NULL
1584            && (context->type->integer_type() != NULL
1585                || context->type->float_type() != NULL
1586                || context->type->complex_type() != NULL))
1587     this->type_ = context->type;
1588   else if (!context->may_be_abstract)
1589     this->type_ = Type::lookup_integer_type("int");
1590 }
1591
1592 // Return true if the integer VAL fits in the range of the type TYPE.
1593 // Otherwise give an error and return false.  TYPE may be NULL.
1594
1595 bool
1596 Integer_expression::check_constant(mpz_t val, Type* type,
1597                                    source_location location)
1598 {
1599   if (type == NULL)
1600     return true;
1601   Integer_type* itype = type->integer_type();
1602   if (itype == NULL || itype->is_abstract())
1603     return true;
1604
1605   int bits = mpz_sizeinbase(val, 2);
1606
1607   if (itype->is_unsigned())
1608     {
1609       // For an unsigned type we can only accept a nonnegative number,
1610       // and we must be able to represent at least BITS.
1611       if (mpz_sgn(val) >= 0
1612           && bits <= itype->bits())
1613         return true;
1614     }
1615   else
1616     {
1617       // For a signed type we need an extra bit to indicate the sign.
1618       // We have to handle the most negative integer specially.
1619       if (bits + 1 <= itype->bits()
1620           || (bits <= itype->bits()
1621               && mpz_sgn(val) < 0
1622               && (mpz_scan1(val, 0)
1623                   == static_cast<unsigned long>(itype->bits() - 1))
1624               && mpz_scan0(val, itype->bits()) == ULONG_MAX))
1625         return true;
1626     }
1627
1628   error_at(location, "integer constant overflow");
1629   return false;
1630 }
1631
1632 // Check the type of an integer constant.
1633
1634 void
1635 Integer_expression::do_check_types(Gogo*)
1636 {
1637   if (this->type_ == NULL)
1638     return;
1639   if (!Integer_expression::check_constant(this->val_, this->type_,
1640                                           this->location()))
1641     this->set_is_error();
1642 }
1643
1644 // Get a tree for an integer constant.
1645
1646 tree
1647 Integer_expression::do_get_tree(Translate_context* context)
1648 {
1649   Gogo* gogo = context->gogo();
1650   tree type;
1651   if (this->type_ != NULL && !this->type_->is_abstract())
1652     type = this->type_->get_tree(gogo);
1653   else if (this->type_ != NULL && this->type_->float_type() != NULL)
1654     {
1655       // We are converting to an abstract floating point type.
1656       type = Type::lookup_float_type("float64")->get_tree(gogo);
1657     }
1658   else if (this->type_ != NULL && this->type_->complex_type() != NULL)
1659     {
1660       // We are converting to an abstract complex type.
1661       type = Type::lookup_complex_type("complex128")->get_tree(gogo);
1662     }
1663   else
1664     {
1665       // If we still have an abstract type here, then this is being
1666       // used in a constant expression which didn't get reduced for
1667       // some reason.  Use a type which will fit the value.  We use <,
1668       // not <=, because we need an extra bit for the sign bit.
1669       int bits = mpz_sizeinbase(this->val_, 2);
1670       if (bits < INT_TYPE_SIZE)
1671         type = Type::lookup_integer_type("int")->get_tree(gogo);
1672       else if (bits < 64)
1673         type = Type::lookup_integer_type("int64")->get_tree(gogo);
1674       else
1675         type = long_long_integer_type_node;
1676     }
1677   return Expression::integer_constant_tree(this->val_, type);
1678 }
1679
1680 // Write VAL to export data.
1681
1682 void
1683 Integer_expression::export_integer(Export* exp, const mpz_t val)
1684 {
1685   char* s = mpz_get_str(NULL, 10, val);
1686   exp->write_c_string(s);
1687   free(s);
1688 }
1689
1690 // Export an integer in a constant expression.
1691
1692 void
1693 Integer_expression::do_export(Export* exp) const
1694 {
1695   Integer_expression::export_integer(exp, this->val_);
1696   // A trailing space lets us reliably identify the end of the number.
1697   exp->write_c_string(" ");
1698 }
1699
1700 // Import an integer, floating point, or complex value.  This handles
1701 // all these types because they all start with digits.
1702
1703 Expression*
1704 Integer_expression::do_import(Import* imp)
1705 {
1706   std::string num = imp->read_identifier();
1707   imp->require_c_string(" ");
1708   if (!num.empty() && num[num.length() - 1] == 'i')
1709     {
1710       mpfr_t real;
1711       size_t plus_pos = num.find('+', 1);
1712       size_t minus_pos = num.find('-', 1);
1713       size_t pos;
1714       if (plus_pos == std::string::npos)
1715         pos = minus_pos;
1716       else if (minus_pos == std::string::npos)
1717         pos = plus_pos;
1718       else
1719         {
1720           error_at(imp->location(), "bad number in import data: %qs",
1721                    num.c_str());
1722           return Expression::make_error(imp->location());
1723         }
1724       if (pos == std::string::npos)
1725         mpfr_set_ui(real, 0, GMP_RNDN);
1726       else
1727         {
1728           std::string real_str = num.substr(0, pos);
1729           if (mpfr_init_set_str(real, real_str.c_str(), 10, GMP_RNDN) != 0)
1730             {
1731               error_at(imp->location(), "bad number in import data: %qs",
1732                        real_str.c_str());
1733               return Expression::make_error(imp->location());
1734             }
1735         }
1736
1737       std::string imag_str;
1738       if (pos == std::string::npos)
1739         imag_str = num;
1740       else
1741         imag_str = num.substr(pos);
1742       imag_str = imag_str.substr(0, imag_str.size() - 1);
1743       mpfr_t imag;
1744       if (mpfr_init_set_str(imag, imag_str.c_str(), 10, GMP_RNDN) != 0)
1745         {
1746           error_at(imp->location(), "bad number in import data: %qs",
1747                    imag_str.c_str());
1748           return Expression::make_error(imp->location());
1749         }
1750       Expression* ret = Expression::make_complex(&real, &imag, NULL,
1751                                                  imp->location());
1752       mpfr_clear(real);
1753       mpfr_clear(imag);
1754       return ret;
1755     }
1756   else if (num.find('.') == std::string::npos
1757            && num.find('E') == std::string::npos)
1758     {
1759       mpz_t val;
1760       if (mpz_init_set_str(val, num.c_str(), 10) != 0)
1761         {
1762           error_at(imp->location(), "bad number in import data: %qs",
1763                    num.c_str());
1764           return Expression::make_error(imp->location());
1765         }
1766       Expression* ret = Expression::make_integer(&val, NULL, imp->location());
1767       mpz_clear(val);
1768       return ret;
1769     }
1770   else
1771     {
1772       mpfr_t val;
1773       if (mpfr_init_set_str(val, num.c_str(), 10, GMP_RNDN) != 0)
1774         {
1775           error_at(imp->location(), "bad number in import data: %qs",
1776                    num.c_str());
1777           return Expression::make_error(imp->location());
1778         }
1779       Expression* ret = Expression::make_float(&val, NULL, imp->location());
1780       mpfr_clear(val);
1781       return ret;
1782     }
1783 }
1784
1785 // Build a new integer value.
1786
1787 Expression*
1788 Expression::make_integer(const mpz_t* val, Type* type,
1789                          source_location location)
1790 {
1791   return new Integer_expression(val, type, location);
1792 }
1793
1794 // Floats.
1795
1796 class Float_expression : public Expression
1797 {
1798  public:
1799   Float_expression(const mpfr_t* val, Type* type, source_location location)
1800     : Expression(EXPRESSION_FLOAT, location),
1801       type_(type)
1802   {
1803     mpfr_init_set(this->val_, *val, GMP_RNDN);
1804   }
1805
1806   // Constrain VAL to fit into TYPE.
1807   static void
1808   constrain_float(mpfr_t val, Type* type);
1809
1810   // Return whether VAL fits in the type.
1811   static bool
1812   check_constant(mpfr_t val, Type*, source_location);
1813
1814   // Write VAL to export data.
1815   static void
1816   export_float(Export* exp, const mpfr_t val);
1817
1818  protected:
1819   bool
1820   do_is_constant() const
1821   { return true; }
1822
1823   bool
1824   do_float_constant_value(mpfr_t val, Type**) const;
1825
1826   Type*
1827   do_type();
1828
1829   void
1830   do_determine_type(const Type_context*);
1831
1832   void
1833   do_check_types(Gogo*);
1834
1835   Expression*
1836   do_copy()
1837   { return Expression::make_float(&this->val_, this->type_,
1838                                   this->location()); }
1839
1840   tree
1841   do_get_tree(Translate_context*);
1842
1843   void
1844   do_export(Export*) const;
1845
1846  private:
1847   // The floating point value.
1848   mpfr_t val_;
1849   // The type so far.
1850   Type* type_;
1851 };
1852
1853 // Constrain VAL to fit into TYPE.
1854
1855 void
1856 Float_expression::constrain_float(mpfr_t val, Type* type)
1857 {
1858   Float_type* ftype = type->float_type();
1859   if (ftype != NULL && !ftype->is_abstract())
1860     {
1861       tree type_tree = ftype->type_tree();
1862       REAL_VALUE_TYPE rvt;
1863       real_from_mpfr(&rvt, val, type_tree, GMP_RNDN);
1864       real_convert(&rvt, TYPE_MODE(type_tree), &rvt);
1865       mpfr_from_real(val, &rvt, GMP_RNDN);
1866     }
1867 }
1868
1869 // Return a floating point constant value.
1870
1871 bool
1872 Float_expression::do_float_constant_value(mpfr_t val, Type** ptype) const
1873 {
1874   if (this->type_ != NULL)
1875     *ptype = this->type_;
1876   mpfr_set(val, this->val_, GMP_RNDN);
1877   return true;
1878 }
1879
1880 // Return the current type.  If we haven't set the type yet, we return
1881 // an abstract float type.
1882
1883 Type*
1884 Float_expression::do_type()
1885 {
1886   if (this->type_ == NULL)
1887     this->type_ = Type::make_abstract_float_type();
1888   return this->type_;
1889 }
1890
1891 // Set the type of the float value.  Here we may switch from an
1892 // abstract type to a real type.
1893
1894 void
1895 Float_expression::do_determine_type(const Type_context* context)
1896 {
1897   if (this->type_ != NULL && !this->type_->is_abstract())
1898     ;
1899   else if (context->type != NULL
1900            && (context->type->integer_type() != NULL
1901                || context->type->float_type() != NULL
1902                || context->type->complex_type() != NULL))
1903     this->type_ = context->type;
1904   else if (!context->may_be_abstract)
1905     this->type_ = Type::lookup_float_type("float");
1906 }
1907
1908 // Return true if the floating point value VAL fits in the range of
1909 // the type TYPE.  Otherwise give an error and return false.  TYPE may
1910 // be NULL.
1911
1912 bool
1913 Float_expression::check_constant(mpfr_t val, Type* type,
1914                                  source_location location)
1915 {
1916   if (type == NULL)
1917     return true;
1918   Float_type* ftype = type->float_type();
1919   if (ftype == NULL || ftype->is_abstract())
1920     return true;
1921
1922   // A NaN or Infinity always fits in the range of the type.
1923   if (mpfr_nan_p(val) || mpfr_inf_p(val) || mpfr_zero_p(val))
1924     return true;
1925
1926   mp_exp_t exp = mpfr_get_exp(val);
1927   mp_exp_t max_exp;
1928   switch (ftype->bits())
1929     {
1930     case 32:
1931       max_exp = 128;
1932       break;
1933     case 64:
1934       max_exp = 1024;
1935       break;
1936     default:
1937       gcc_unreachable();
1938     }
1939   if (exp > max_exp)
1940     {
1941       error_at(location, "floating point constant overflow");
1942       return false;
1943     }
1944   return true;
1945 }
1946
1947 // Check the type of a float value.
1948
1949 void
1950 Float_expression::do_check_types(Gogo*)
1951 {
1952   if (this->type_ == NULL)
1953     return;
1954
1955   if (!Float_expression::check_constant(this->val_, this->type_,
1956                                         this->location()))
1957     this->set_is_error();
1958
1959   Integer_type* integer_type = this->type_->integer_type();
1960   if (integer_type != NULL)
1961     {
1962       if (!mpfr_integer_p(this->val_))
1963         this->report_error(_("floating point constant truncated to integer"));
1964       else
1965         {
1966           gcc_assert(!integer_type->is_abstract());
1967           mpz_t ival;
1968           mpz_init(ival);
1969           mpfr_get_z(ival, this->val_, GMP_RNDN);
1970           Integer_expression::check_constant(ival, integer_type,
1971                                              this->location());
1972           mpz_clear(ival);
1973         }
1974     }
1975 }
1976
1977 // Get a tree for a float constant.
1978
1979 tree
1980 Float_expression::do_get_tree(Translate_context* context)
1981 {
1982   Gogo* gogo = context->gogo();
1983   tree type;
1984   if (this->type_ != NULL && !this->type_->is_abstract())
1985     type = this->type_->get_tree(gogo);
1986   else if (this->type_ != NULL && this->type_->integer_type() != NULL)
1987     {
1988       // We have an abstract integer type.  We just hope for the best.
1989       type = Type::lookup_integer_type("int")->get_tree(gogo);
1990     }
1991   else
1992     {
1993       // If we still have an abstract type here, then this is being
1994       // used in a constant expression which didn't get reduced.  We
1995       // just use float64 and hope for the best.
1996       type = Type::lookup_float_type("float64")->get_tree(gogo);
1997     }
1998   return Expression::float_constant_tree(this->val_, type);
1999 }
2000
2001 // Write a floating point number to export data.
2002
2003 void
2004 Float_expression::export_float(Export *exp, const mpfr_t val)
2005 {
2006   mp_exp_t exponent;
2007   char* s = mpfr_get_str(NULL, &exponent, 10, 0, val, GMP_RNDN);
2008   if (*s == '-')
2009     exp->write_c_string("-");
2010   exp->write_c_string("0.");
2011   exp->write_c_string(*s == '-' ? s + 1 : s);
2012   mpfr_free_str(s);
2013   char buf[30];
2014   snprintf(buf, sizeof buf, "E%ld", exponent);
2015   exp->write_c_string(buf);
2016 }
2017
2018 // Export a floating point number in a constant expression.
2019
2020 void
2021 Float_expression::do_export(Export* exp) const
2022 {
2023   Float_expression::export_float(exp, this->val_);
2024   // A trailing space lets us reliably identify the end of the number.
2025   exp->write_c_string(" ");
2026 }
2027
2028 // Make a float expression.
2029
2030 Expression*
2031 Expression::make_float(const mpfr_t* val, Type* type, source_location location)
2032 {
2033   return new Float_expression(val, type, location);
2034 }
2035
2036 // Complex numbers.
2037
2038 class Complex_expression : public Expression
2039 {
2040  public:
2041   Complex_expression(const mpfr_t* real, const mpfr_t* imag, Type* type,
2042                      source_location location)
2043     : Expression(EXPRESSION_COMPLEX, location),
2044       type_(type)
2045   {
2046     mpfr_init_set(this->real_, *real, GMP_RNDN);
2047     mpfr_init_set(this->imag_, *imag, GMP_RNDN);
2048   }
2049
2050   // Constrain REAL/IMAG to fit into TYPE.
2051   static void
2052   constrain_complex(mpfr_t real, mpfr_t imag, Type* type);
2053
2054   // Return whether REAL/IMAG fits in the type.
2055   static bool
2056   check_constant(mpfr_t real, mpfr_t imag, Type*, source_location);
2057
2058   // Write REAL/IMAG to export data.
2059   static void
2060   export_complex(Export* exp, const mpfr_t real, const mpfr_t val);
2061
2062  protected:
2063   bool
2064   do_is_constant() const
2065   { return true; }
2066
2067   bool
2068   do_complex_constant_value(mpfr_t real, mpfr_t imag, Type**) const;
2069
2070   Type*
2071   do_type();
2072
2073   void
2074   do_determine_type(const Type_context*);
2075
2076   void
2077   do_check_types(Gogo*);
2078
2079   Expression*
2080   do_copy()
2081   {
2082     return Expression::make_complex(&this->real_, &this->imag_, this->type_,
2083                                     this->location());
2084   }
2085
2086   tree
2087   do_get_tree(Translate_context*);
2088
2089   void
2090   do_export(Export*) const;
2091
2092  private:
2093   // The real part.
2094   mpfr_t real_;
2095   // The imaginary part;
2096   mpfr_t imag_;
2097   // The type if known.
2098   Type* type_;
2099 };
2100
2101 // Constrain REAL/IMAG to fit into TYPE.
2102
2103 void
2104 Complex_expression::constrain_complex(mpfr_t real, mpfr_t imag, Type* type)
2105 {
2106   Complex_type* ctype = type->complex_type();
2107   if (ctype != NULL && !ctype->is_abstract())
2108     {
2109       tree type_tree = ctype->type_tree();
2110
2111       REAL_VALUE_TYPE rvt;
2112       real_from_mpfr(&rvt, real, TREE_TYPE(type_tree), GMP_RNDN);
2113       real_convert(&rvt, TYPE_MODE(TREE_TYPE(type_tree)), &rvt);
2114       mpfr_from_real(real, &rvt, GMP_RNDN);
2115
2116       real_from_mpfr(&rvt, imag, TREE_TYPE(type_tree), GMP_RNDN);
2117       real_convert(&rvt, TYPE_MODE(TREE_TYPE(type_tree)), &rvt);
2118       mpfr_from_real(imag, &rvt, GMP_RNDN);
2119     }
2120 }
2121
2122 // Return a complex constant value.
2123
2124 bool
2125 Complex_expression::do_complex_constant_value(mpfr_t real, mpfr_t imag,
2126                                               Type** ptype) const
2127 {
2128   if (this->type_ != NULL)
2129     *ptype = this->type_;
2130   mpfr_set(real, this->real_, GMP_RNDN);
2131   mpfr_set(imag, this->imag_, GMP_RNDN);
2132   return true;
2133 }
2134
2135 // Return the current type.  If we haven't set the type yet, we return
2136 // an abstract complex type.
2137
2138 Type*
2139 Complex_expression::do_type()
2140 {
2141   if (this->type_ == NULL)
2142     this->type_ = Type::make_abstract_complex_type();
2143   return this->type_;
2144 }
2145
2146 // Set the type of the complex value.  Here we may switch from an
2147 // abstract type to a real type.
2148
2149 void
2150 Complex_expression::do_determine_type(const Type_context* context)
2151 {
2152   if (this->type_ != NULL && !this->type_->is_abstract())
2153     ;
2154   else if (context->type != NULL
2155            && context->type->complex_type() != NULL)
2156     this->type_ = context->type;
2157   else if (!context->may_be_abstract)
2158     this->type_ = Type::lookup_complex_type("complex");
2159 }
2160
2161 // Return true if the complex value REAL/IMAG fits in the range of the
2162 // type TYPE.  Otherwise give an error and return false.  TYPE may be
2163 // NULL.
2164
2165 bool
2166 Complex_expression::check_constant(mpfr_t real, mpfr_t imag, Type* type,
2167                                    source_location location)
2168 {
2169   if (type == NULL)
2170     return true;
2171   Complex_type* ctype = type->complex_type();
2172   if (ctype == NULL || ctype->is_abstract())
2173     return true;
2174
2175   mp_exp_t max_exp;
2176   switch (ctype->bits())
2177     {
2178     case 64:
2179       max_exp = 128;
2180       break;
2181     case 128:
2182       max_exp = 1024;
2183       break;
2184     default:
2185       gcc_unreachable();
2186     }
2187
2188   // A NaN or Infinity always fits in the range of the type.
2189   if (!mpfr_nan_p(real) && !mpfr_inf_p(real) && !mpfr_zero_p(real))
2190     {
2191       if (mpfr_get_exp(real) > max_exp)
2192         {
2193           error_at(location, "complex real part constant overflow");
2194           return false;
2195         }
2196     }
2197
2198   if (!mpfr_nan_p(imag) && !mpfr_inf_p(imag) && !mpfr_zero_p(imag))
2199     {
2200       if (mpfr_get_exp(imag) > max_exp)
2201         {
2202           error_at(location, "complex imaginary part constant overflow");
2203           return false;
2204         }
2205     }
2206
2207   return true;
2208 }
2209
2210 // Check the type of a complex value.
2211
2212 void
2213 Complex_expression::do_check_types(Gogo*)
2214 {
2215   if (this->type_ == NULL)
2216     return;
2217
2218   if (!Complex_expression::check_constant(this->real_, this->imag_,
2219                                           this->type_, this->location()))
2220     this->set_is_error();
2221 }
2222
2223 // Get a tree for a complex constant.
2224
2225 tree
2226 Complex_expression::do_get_tree(Translate_context* context)
2227 {
2228   Gogo* gogo = context->gogo();
2229   tree type;
2230   if (this->type_ != NULL && !this->type_->is_abstract())
2231     type = this->type_->get_tree(gogo);
2232   else
2233     {
2234       // If we still have an abstract type here, this this is being
2235       // used in a constant expression which didn't get reduced.  We
2236       // just use complex128 and hope for the best.
2237       type = Type::lookup_complex_type("complex128")->get_tree(gogo);
2238     }
2239   return Expression::complex_constant_tree(this->real_, this->imag_, type);
2240 }
2241
2242 // Write REAL/IMAG to export data.
2243
2244 void
2245 Complex_expression::export_complex(Export* exp, const mpfr_t real,
2246                                    const mpfr_t imag)
2247 {
2248   if (!mpfr_zero_p(real))
2249     {
2250       Float_expression::export_float(exp, real);
2251       if (mpfr_sgn(imag) > 0)
2252         exp->write_c_string("+");
2253     }
2254   Float_expression::export_float(exp, imag);
2255   exp->write_c_string("i");
2256 }
2257
2258 // Export a complex number in a constant expression.
2259
2260 void
2261 Complex_expression::do_export(Export* exp) const
2262 {
2263   Complex_expression::export_complex(exp, this->real_, this->imag_);
2264   // A trailing space lets us reliably identify the end of the number.
2265   exp->write_c_string(" ");
2266 }
2267
2268 // Make a complex expression.
2269
2270 Expression*
2271 Expression::make_complex(const mpfr_t* real, const mpfr_t* imag, Type* type,
2272                          source_location location)
2273 {
2274   return new Complex_expression(real, imag, type, location);
2275 }
2276
2277 // A reference to a const in an expression.
2278
2279 class Const_expression : public Expression
2280 {
2281  public:
2282   Const_expression(Named_object* constant, source_location location)
2283     : Expression(EXPRESSION_CONST_REFERENCE, location),
2284       constant_(constant), type_(NULL)
2285   { }
2286
2287   const std::string&
2288   name() const
2289   { return this->constant_->name(); }
2290
2291  protected:
2292   Expression*
2293   do_lower(Gogo*, Named_object*, int);
2294
2295   bool
2296   do_is_constant() const
2297   { return true; }
2298
2299   bool
2300   do_integer_constant_value(bool, mpz_t val, Type**) const;
2301
2302   bool
2303   do_float_constant_value(mpfr_t val, Type**) const;
2304
2305   bool
2306   do_complex_constant_value(mpfr_t real, mpfr_t imag, Type**) const;
2307
2308   bool
2309   do_string_constant_value(std::string* val) const
2310   { return this->constant_->const_value()->expr()->string_constant_value(val); }
2311
2312   Type*
2313   do_type();
2314
2315   // The type of a const is set by the declaration, not the use.
2316   void
2317   do_determine_type(const Type_context*);
2318
2319   void
2320   do_check_types(Gogo*);
2321
2322   Expression*
2323   do_copy()
2324   { return this; }
2325
2326   tree
2327   do_get_tree(Translate_context* context);
2328
2329   // When exporting a reference to a const as part of a const
2330   // expression, we export the value.  We ignore the fact that it has
2331   // a name.
2332   void
2333   do_export(Export* exp) const
2334   { this->constant_->const_value()->expr()->export_expression(exp); }
2335
2336  private:
2337   // The constant.
2338   Named_object* constant_;
2339   // The type of this reference.  This is used if the constant has an
2340   // abstract type.
2341   Type* type_;
2342 };
2343
2344 // Lower a constant expression.  This is where we convert the
2345 // predeclared constant iota into an integer value.
2346
2347 Expression*
2348 Const_expression::do_lower(Gogo* gogo, Named_object*, int iota_value)
2349 {
2350   if (this->constant_->const_value()->expr()->classification()
2351       == EXPRESSION_IOTA)
2352     {
2353       if (iota_value == -1)
2354         {
2355           error_at(this->location(),
2356                    "iota is only defined in const declarations");
2357           iota_value = 0;
2358         }
2359       mpz_t val;
2360       mpz_init_set_ui(val, static_cast<unsigned long>(iota_value));
2361       Expression* ret = Expression::make_integer(&val, NULL,
2362                                                  this->location());
2363       mpz_clear(val);
2364       return ret;
2365     }
2366
2367   // Make sure that the constant itself has been lowered.
2368   gogo->lower_constant(this->constant_);
2369
2370   return this;
2371 }
2372
2373 // Return an integer constant value.
2374
2375 bool
2376 Const_expression::do_integer_constant_value(bool iota_is_constant, mpz_t val,
2377                                             Type** ptype) const
2378 {
2379   Type* ctype;
2380   if (this->type_ != NULL)
2381     ctype = this->type_;
2382   else
2383     ctype = this->constant_->const_value()->type();
2384   if (ctype != NULL && ctype->integer_type() == NULL)
2385     return false;
2386
2387   Expression* e = this->constant_->const_value()->expr();
2388   Type* t;
2389   bool r = e->integer_constant_value(iota_is_constant, val, &t);
2390
2391   if (r
2392       && ctype != NULL
2393       && !Integer_expression::check_constant(val, ctype, this->location()))
2394     return false;
2395
2396   *ptype = ctype != NULL ? ctype : t;
2397   return r;
2398 }
2399
2400 // Return a floating point constant value.
2401
2402 bool
2403 Const_expression::do_float_constant_value(mpfr_t val, Type** ptype) const
2404 {
2405   Type* ctype;
2406   if (this->type_ != NULL)
2407     ctype = this->type_;
2408   else
2409     ctype = this->constant_->const_value()->type();
2410   if (ctype != NULL && ctype->float_type() == NULL)
2411     return false;
2412
2413   Type* t;
2414   bool r = this->constant_->const_value()->expr()->float_constant_value(val,
2415                                                                         &t);
2416   if (r && ctype != NULL)
2417     {
2418       if (!Float_expression::check_constant(val, ctype, this->location()))
2419         return false;
2420       Float_expression::constrain_float(val, ctype);
2421     }
2422   *ptype = ctype != NULL ? ctype : t;
2423   return r;
2424 }
2425
2426 // Return a complex constant value.
2427
2428 bool
2429 Const_expression::do_complex_constant_value(mpfr_t real, mpfr_t imag,
2430                                             Type **ptype) const
2431 {
2432   Type* ctype;
2433   if (this->type_ != NULL)
2434     ctype = this->type_;
2435   else
2436     ctype = this->constant_->const_value()->type();
2437   if (ctype != NULL && ctype->complex_type() == NULL)
2438     return false;
2439
2440   Type *t;
2441   bool r = this->constant_->const_value()->expr()->complex_constant_value(real,
2442                                                                           imag,
2443                                                                           &t);
2444   if (r && ctype != NULL)
2445     {
2446       if (!Complex_expression::check_constant(real, imag, ctype,
2447                                               this->location()))
2448         return false;
2449       Complex_expression::constrain_complex(real, imag, ctype);
2450     }
2451   *ptype = ctype != NULL ? ctype : t;
2452   return r;
2453 }
2454
2455 // Return the type of the const reference.
2456
2457 Type*
2458 Const_expression::do_type()
2459 {
2460   if (this->type_ != NULL)
2461     return this->type_;
2462   Named_constant* nc = this->constant_->const_value();
2463   Type* ret = nc->type();
2464   if (ret != NULL)
2465     return ret;
2466   // During parsing, a named constant may have a NULL type, but we
2467   // must not return a NULL type here.
2468   return nc->expr()->type();
2469 }
2470
2471 // Set the type of the const reference.
2472
2473 void
2474 Const_expression::do_determine_type(const Type_context* context)
2475 {
2476   Type* ctype = this->constant_->const_value()->type();
2477   Type* cetype = (ctype != NULL
2478                   ? ctype
2479                   : this->constant_->const_value()->expr()->type());
2480   if (ctype != NULL && !ctype->is_abstract())
2481     ;
2482   else if (context->type != NULL
2483            && (context->type->integer_type() != NULL
2484                || context->type->float_type() != NULL
2485                || context->type->complex_type() != NULL)
2486            && (cetype->integer_type() != NULL
2487                || cetype->float_type() != NULL
2488                || cetype->complex_type() != NULL))
2489     this->type_ = context->type;
2490   else if (context->type != NULL
2491            && context->type->is_string_type()
2492            && cetype->is_string_type())
2493     this->type_ = context->type;
2494   else if (context->type != NULL
2495            && context->type->is_boolean_type()
2496            && cetype->is_boolean_type())
2497     this->type_ = context->type;
2498   else if (!context->may_be_abstract)
2499     {
2500       if (cetype->is_abstract())
2501         cetype = cetype->make_non_abstract_type();
2502       this->type_ = cetype;
2503     }
2504 }
2505
2506 // Check types of a const reference.
2507
2508 void
2509 Const_expression::do_check_types(Gogo*)
2510 {
2511   if (this->type_ == NULL || this->type_->is_abstract())
2512     return;
2513
2514   // Check for integer overflow.
2515   if (this->type_->integer_type() != NULL)
2516     {
2517       mpz_t ival;
2518       mpz_init(ival);
2519       Type* dummy;
2520       if (!this->integer_constant_value(true, ival, &dummy))
2521         {
2522           mpfr_t fval;
2523           mpfr_init(fval);
2524           Expression* cexpr = this->constant_->const_value()->expr();
2525           if (cexpr->float_constant_value(fval, &dummy))
2526             {
2527               if (!mpfr_integer_p(fval))
2528                 this->report_error(_("floating point constant "
2529                                      "truncated to integer"));
2530               else
2531                 {
2532                   mpfr_get_z(ival, fval, GMP_RNDN);
2533                   Integer_expression::check_constant(ival, this->type_,
2534                                                      this->location());
2535                 }
2536             }
2537           mpfr_clear(fval);
2538         }
2539       mpz_clear(ival);
2540     }
2541 }
2542
2543 // Return a tree for the const reference.
2544
2545 tree
2546 Const_expression::do_get_tree(Translate_context* context)
2547 {
2548   Gogo* gogo = context->gogo();
2549   tree type_tree;
2550   if (this->type_ == NULL)
2551     type_tree = NULL_TREE;
2552   else
2553     {
2554       type_tree = this->type_->get_tree(gogo);
2555       if (type_tree == error_mark_node)
2556         return error_mark_node;
2557     }
2558
2559   // If the type has been set for this expression, but the underlying
2560   // object is an abstract int or float, we try to get the abstract
2561   // value.  Otherwise we may lose something in the conversion.
2562   if (this->type_ != NULL
2563       && this->constant_->const_value()->type()->is_abstract())
2564     {
2565       Expression* expr = this->constant_->const_value()->expr();
2566       mpz_t ival;
2567       mpz_init(ival);
2568       Type* t;
2569       if (expr->integer_constant_value(true, ival, &t))
2570         {
2571           tree ret = Expression::integer_constant_tree(ival, type_tree);
2572           mpz_clear(ival);
2573           return ret;
2574         }
2575       mpz_clear(ival);
2576
2577       mpfr_t fval;
2578       mpfr_init(fval);
2579       if (expr->float_constant_value(fval, &t))
2580         {
2581           tree ret = Expression::float_constant_tree(fval, type_tree);
2582           mpfr_clear(fval);
2583           return ret;
2584         }
2585
2586       mpfr_t imag;
2587       mpfr_init(imag);
2588       if (expr->complex_constant_value(fval, imag, &t))
2589         {
2590           tree ret = Expression::complex_constant_tree(fval, imag, type_tree);
2591           mpfr_clear(fval);
2592           mpfr_clear(imag);
2593           return ret;
2594         }
2595       mpfr_clear(imag);
2596       mpfr_clear(fval);
2597     }
2598
2599   tree const_tree = this->constant_->get_tree(gogo, context->function());
2600   if (this->type_ == NULL
2601       || const_tree == error_mark_node
2602       || TREE_TYPE(const_tree) == error_mark_node)
2603     return const_tree;
2604
2605   tree ret;
2606   if (TYPE_MAIN_VARIANT(type_tree) == TYPE_MAIN_VARIANT(TREE_TYPE(const_tree)))
2607     ret = fold_convert(type_tree, const_tree);
2608   else if (TREE_CODE(type_tree) == INTEGER_TYPE)
2609     ret = fold(convert_to_integer(type_tree, const_tree));
2610   else if (TREE_CODE(type_tree) == REAL_TYPE)
2611     ret = fold(convert_to_real(type_tree, const_tree));
2612   else if (TREE_CODE(type_tree) == COMPLEX_TYPE)
2613     ret = fold(convert_to_complex(type_tree, const_tree));
2614   else
2615     gcc_unreachable();
2616   return ret;
2617 }
2618
2619 // Make a reference to a constant in an expression.
2620
2621 Expression*
2622 Expression::make_const_reference(Named_object* constant,
2623                                  source_location location)
2624 {
2625   return new Const_expression(constant, location);
2626 }
2627
2628 // The nil value.
2629
2630 class Nil_expression : public Expression
2631 {
2632  public:
2633   Nil_expression(source_location location)
2634     : Expression(EXPRESSION_NIL, location)
2635   { }
2636
2637   static Expression*
2638   do_import(Import*);
2639
2640  protected:
2641   bool
2642   do_is_constant() const
2643   { return true; }
2644
2645   Type*
2646   do_type()
2647   { return Type::make_nil_type(); }
2648
2649   void
2650   do_determine_type(const Type_context*)
2651   { }
2652
2653   Expression*
2654   do_copy()
2655   { return this; }
2656
2657   tree
2658   do_get_tree(Translate_context*)
2659   { return null_pointer_node; }
2660
2661   void
2662   do_export(Export* exp) const
2663   { exp->write_c_string("nil"); }
2664 };
2665
2666 // Import a nil expression.
2667
2668 Expression*
2669 Nil_expression::do_import(Import* imp)
2670 {
2671   imp->require_c_string("nil");
2672   return Expression::make_nil(imp->location());
2673 }
2674
2675 // Make a nil expression.
2676
2677 Expression*
2678 Expression::make_nil(source_location location)
2679 {
2680   return new Nil_expression(location);
2681 }
2682
2683 // The value of the predeclared constant iota.  This is little more
2684 // than a marker.  This will be lowered to an integer in
2685 // Const_expression::do_lower, which is where we know the value that
2686 // it should have.
2687
2688 class Iota_expression : public Parser_expression
2689 {
2690  public:
2691   Iota_expression(source_location location)
2692     : Parser_expression(EXPRESSION_IOTA, location)
2693   { }
2694
2695  protected:
2696   Expression*
2697   do_lower(Gogo*, Named_object*, int)
2698   { gcc_unreachable(); }
2699
2700   // There should only ever be one of these.
2701   Expression*
2702   do_copy()
2703   { gcc_unreachable(); }
2704 };
2705
2706 // Make an iota expression.  This is only called for one case: the
2707 // value of the predeclared constant iota.
2708
2709 Expression*
2710 Expression::make_iota()
2711 {
2712   static Iota_expression iota_expression(UNKNOWN_LOCATION);
2713   return &iota_expression;
2714 }
2715
2716 // A type conversion expression.
2717
2718 class Type_conversion_expression : public Expression
2719 {
2720  public:
2721   Type_conversion_expression(Type* type, Expression* expr,
2722                              source_location location)
2723     : Expression(EXPRESSION_CONVERSION, location),
2724       type_(type), expr_(expr), may_convert_function_types_(false)
2725   { }
2726
2727   // Return the type to which we are converting.
2728   Type*
2729   type() const
2730   { return this->type_; }
2731
2732   // Return the expression which we are converting.
2733   Expression*
2734   expr() const
2735   { return this->expr_; }
2736
2737   // Permit converting from one function type to another.  This is
2738   // used internally for method expressions.
2739   void
2740   set_may_convert_function_types()
2741   {
2742     this->may_convert_function_types_ = true;
2743   }
2744
2745   // Import a type conversion expression.
2746   static Expression*
2747   do_import(Import*);
2748
2749  protected:
2750   int
2751   do_traverse(Traverse* traverse);
2752
2753   Expression*
2754   do_lower(Gogo*, Named_object*, int);
2755
2756   bool
2757   do_is_constant() const
2758   { return this->expr_->is_constant(); }
2759
2760   bool
2761   do_integer_constant_value(bool, mpz_t, Type**) const;
2762
2763   bool
2764   do_float_constant_value(mpfr_t, Type**) const;
2765
2766   bool
2767   do_complex_constant_value(mpfr_t, mpfr_t, Type**) const;
2768
2769   bool
2770   do_string_constant_value(std::string*) const;
2771
2772   Type*
2773   do_type()
2774   { return this->type_; }
2775
2776   void
2777   do_determine_type(const Type_context*)
2778   {
2779     Type_context subcontext(this->type_, false);
2780     this->expr_->determine_type(&subcontext);
2781   }
2782
2783   void
2784   do_check_types(Gogo*);
2785
2786   Expression*
2787   do_copy()
2788   {
2789     return new Type_conversion_expression(this->type_, this->expr_->copy(),
2790                                           this->location());
2791   }
2792
2793   tree
2794   do_get_tree(Translate_context* context);
2795
2796   void
2797   do_export(Export*) const;
2798
2799  private:
2800   // The type to convert to.
2801   Type* type_;
2802   // The expression to convert.
2803   Expression* expr_;
2804   // True if this is permitted to convert function types.  This is
2805   // used internally for method expressions.
2806   bool may_convert_function_types_;
2807 };
2808
2809 // Traversal.
2810
2811 int
2812 Type_conversion_expression::do_traverse(Traverse* traverse)
2813 {
2814   if (Expression::traverse(&this->expr_, traverse) == TRAVERSE_EXIT
2815       || Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
2816     return TRAVERSE_EXIT;
2817   return TRAVERSE_CONTINUE;
2818 }
2819
2820 // Convert to a constant at lowering time.
2821
2822 Expression*
2823 Type_conversion_expression::do_lower(Gogo*, Named_object*, int)
2824 {
2825   Type* type = this->type_;
2826   Expression* val = this->expr_;
2827   source_location location = this->location();
2828
2829   if (type->integer_type() != NULL)
2830     {
2831       mpz_t ival;
2832       mpz_init(ival);
2833       Type* dummy;
2834       if (val->integer_constant_value(false, ival, &dummy))
2835         {
2836           if (!Integer_expression::check_constant(ival, type, location))
2837             mpz_set_ui(ival, 0);
2838           Expression* ret = Expression::make_integer(&ival, type, location);
2839           mpz_clear(ival);
2840           return ret;
2841         }
2842
2843       mpfr_t fval;
2844       mpfr_init(fval);
2845       if (val->float_constant_value(fval, &dummy))
2846         {
2847           if (!mpfr_integer_p(fval))
2848             {
2849               error_at(location,
2850                        "floating point constant truncated to integer");
2851               return Expression::make_error(location);
2852             }
2853           mpfr_get_z(ival, fval, GMP_RNDN);
2854           if (!Integer_expression::check_constant(ival, type, location))
2855             mpz_set_ui(ival, 0);
2856           Expression* ret = Expression::make_integer(&ival, type, location);
2857           mpfr_clear(fval);
2858           mpz_clear(ival);
2859           return ret;
2860         }
2861       mpfr_clear(fval);
2862       mpz_clear(ival);
2863     }
2864
2865   if (type->float_type() != NULL)
2866     {
2867       mpfr_t fval;
2868       mpfr_init(fval);
2869       Type* dummy;
2870       if (val->float_constant_value(fval, &dummy))
2871         {
2872           if (!Float_expression::check_constant(fval, type, location))
2873             mpfr_set_ui(fval, 0, GMP_RNDN);
2874           Float_expression::constrain_float(fval, type);
2875           Expression *ret = Expression::make_float(&fval, type, location);
2876           mpfr_clear(fval);
2877           return ret;
2878         }
2879       mpfr_clear(fval);
2880     }
2881
2882   if (type->complex_type() != NULL)
2883     {
2884       mpfr_t real;
2885       mpfr_t imag;
2886       mpfr_init(real);
2887       mpfr_init(imag);
2888       Type* dummy;
2889       if (val->complex_constant_value(real, imag, &dummy))
2890         {
2891           if (!Complex_expression::check_constant(real, imag, type, location))
2892             {
2893               mpfr_set_ui(real, 0, GMP_RNDN);
2894               mpfr_set_ui(imag, 0, GMP_RNDN);
2895             }
2896           Complex_expression::constrain_complex(real, imag, type);
2897           Expression* ret = Expression::make_complex(&real, &imag, type,
2898                                                      location);
2899           mpfr_clear(real);
2900           mpfr_clear(imag);
2901           return ret;
2902         }
2903       mpfr_clear(real);
2904       mpfr_clear(imag);
2905     }
2906
2907   if (type->is_open_array_type() && type->named_type() == NULL)
2908     {
2909       Type* element_type = type->array_type()->element_type()->forwarded();
2910       bool is_byte = element_type == Type::lookup_integer_type("uint8");
2911       bool is_int = element_type == Type::lookup_integer_type("int");
2912       if (is_byte || is_int)
2913         {
2914           std::string s;
2915           if (val->string_constant_value(&s))
2916             {
2917               Expression_list* vals = new Expression_list();
2918               if (is_byte)
2919                 {
2920                   for (std::string::const_iterator p = s.begin();
2921                        p != s.end();
2922                        p++)
2923                     {
2924                       mpz_t val;
2925                       mpz_init_set_ui(val, static_cast<unsigned char>(*p));
2926                       Expression* v = Expression::make_integer(&val,
2927                                                                element_type,
2928                                                                location);
2929                       vals->push_back(v);
2930                       mpz_clear(val);
2931                     }
2932                 }
2933               else
2934                 {
2935                   const char *p = s.data();
2936                   const char *pend = s.data() + s.length();
2937                   while (p < pend)
2938                     {
2939                       unsigned int c;
2940                       int adv = Lex::fetch_char(p, &c);
2941                       if (adv == 0)
2942                         {
2943                           warning_at(this->location(), 0,
2944                                      "invalid UTF-8 encoding");
2945                           adv = 1;
2946                         }
2947                       p += adv;
2948                       mpz_t val;
2949                       mpz_init_set_ui(val, c);
2950                       Expression* v = Expression::make_integer(&val,
2951                                                                element_type,
2952                                                                location);
2953                       vals->push_back(v);
2954                       mpz_clear(val);
2955                     }
2956                 }
2957
2958               return Expression::make_slice_composite_literal(type, vals,
2959                                                               location);
2960             }
2961         }
2962     }
2963
2964   return this;
2965 }
2966
2967 // Return the constant integer value if there is one.
2968
2969 bool
2970 Type_conversion_expression::do_integer_constant_value(bool iota_is_constant,
2971                                                       mpz_t val,
2972                                                       Type** ptype) const
2973 {
2974   if (this->type_->integer_type() == NULL)
2975     return false;
2976
2977   mpz_t ival;
2978   mpz_init(ival);
2979   Type* dummy;
2980   if (this->expr_->integer_constant_value(iota_is_constant, ival, &dummy))
2981     {
2982       if (!Integer_expression::check_constant(ival, this->type_,
2983                                               this->location()))
2984         {
2985           mpz_clear(ival);
2986           return false;
2987         }
2988       mpz_set(val, ival);
2989       mpz_clear(ival);
2990       *ptype = this->type_;
2991       return true;
2992     }
2993   mpz_clear(ival);
2994
2995   mpfr_t fval;
2996   mpfr_init(fval);
2997   if (this->expr_->float_constant_value(fval, &dummy))
2998     {
2999       mpfr_get_z(val, fval, GMP_RNDN);
3000       mpfr_clear(fval);
3001       if (!Integer_expression::check_constant(val, this->type_,
3002                                               this->location()))
3003         return false;
3004       *ptype = this->type_;
3005       return true;
3006     }
3007   mpfr_clear(fval);
3008
3009   return false;
3010 }
3011
3012 // Return the constant floating point value if there is one.
3013
3014 bool
3015 Type_conversion_expression::do_float_constant_value(mpfr_t val,
3016                                                     Type** ptype) const
3017 {
3018   if (this->type_->float_type() == NULL)
3019     return false;
3020
3021   mpfr_t fval;
3022   mpfr_init(fval);
3023   Type* dummy;
3024   if (this->expr_->float_constant_value(fval, &dummy))
3025     {
3026       if (!Float_expression::check_constant(fval, this->type_,
3027                                             this->location()))
3028         {
3029           mpfr_clear(fval);
3030           return false;
3031         }
3032       mpfr_set(val, fval, GMP_RNDN);
3033       mpfr_clear(fval);
3034       Float_expression::constrain_float(val, this->type_);
3035       *ptype = this->type_;
3036       return true;
3037     }
3038   mpfr_clear(fval);
3039
3040   return false;
3041 }
3042
3043 // Return the constant complex value if there is one.
3044
3045 bool
3046 Type_conversion_expression::do_complex_constant_value(mpfr_t real,
3047                                                       mpfr_t imag,
3048                                                       Type **ptype) const
3049 {
3050   if (this->type_->complex_type() == NULL)
3051     return false;
3052
3053   mpfr_t rval;
3054   mpfr_t ival;
3055   mpfr_init(rval);
3056   mpfr_init(ival);
3057   Type* dummy;
3058   if (this->expr_->complex_constant_value(rval, ival, &dummy))
3059     {
3060       if (!Complex_expression::check_constant(rval, ival, this->type_,
3061                                               this->location()))
3062         {
3063           mpfr_clear(rval);
3064           mpfr_clear(ival);
3065           return false;
3066         }
3067       mpfr_set(real, rval, GMP_RNDN);
3068       mpfr_set(imag, ival, GMP_RNDN);
3069       mpfr_clear(rval);
3070       mpfr_clear(ival);
3071       Complex_expression::constrain_complex(real, imag, this->type_);
3072       *ptype = this->type_;
3073       return true;
3074     }
3075   mpfr_clear(rval);
3076   mpfr_clear(ival);
3077
3078   return false;
3079 }
3080
3081 // Return the constant string value if there is one.
3082
3083 bool
3084 Type_conversion_expression::do_string_constant_value(std::string* val) const
3085 {
3086   if (this->type_->is_string_type()
3087       && this->expr_->type()->integer_type() != NULL)
3088     {
3089       mpz_t ival;
3090       mpz_init(ival);
3091       Type* dummy;
3092       if (this->expr_->integer_constant_value(false, ival, &dummy))
3093         {
3094           unsigned long ulval = mpz_get_ui(ival);
3095           if (mpz_cmp_ui(ival, ulval) == 0)
3096             {
3097               Lex::append_char(ulval, true, val, this->location());
3098               mpz_clear(ival);
3099               return true;
3100             }
3101         }
3102       mpz_clear(ival);
3103     }
3104
3105   // FIXME: Could handle conversion from const []int here.
3106
3107   return false;
3108 }
3109
3110 // Check that types are convertible.
3111
3112 void
3113 Type_conversion_expression::do_check_types(Gogo*)
3114 {
3115   Type* type = this->type_;
3116   Type* expr_type = this->expr_->type();
3117   std::string reason;
3118
3119   if (this->may_convert_function_types_
3120       && type->function_type() != NULL
3121       && expr_type->function_type() != NULL)
3122     return;
3123
3124   if (Type::are_convertible(type, expr_type, &reason))
3125     return;
3126
3127   error_at(this->location(), "%s", reason.c_str());
3128   this->set_is_error();
3129 }
3130
3131 // Get a tree for a type conversion.
3132
3133 tree
3134 Type_conversion_expression::do_get_tree(Translate_context* context)
3135 {
3136   Gogo* gogo = context->gogo();
3137   tree type_tree = this->type_->get_tree(gogo);
3138   tree expr_tree = this->expr_->get_tree(context);
3139
3140   if (type_tree == error_mark_node
3141       || expr_tree == error_mark_node
3142       || TREE_TYPE(expr_tree) == error_mark_node)
3143     return error_mark_node;
3144
3145   if (TYPE_MAIN_VARIANT(type_tree) == TYPE_MAIN_VARIANT(TREE_TYPE(expr_tree)))
3146     return fold_convert(type_tree, expr_tree);
3147
3148   Type* type = this->type_;
3149   Type* expr_type = this->expr_->type();
3150   tree ret;
3151   if (type->interface_type() != NULL || expr_type->interface_type() != NULL)
3152     ret = Expression::convert_for_assignment(context, type, expr_type,
3153                                              expr_tree, this->location());
3154   else if (type->integer_type() != NULL)
3155     {
3156       if (expr_type->integer_type() != NULL
3157           || expr_type->float_type() != NULL
3158           || expr_type->is_unsafe_pointer_type())
3159         ret = fold(convert_to_integer(type_tree, expr_tree));
3160       else
3161         gcc_unreachable();
3162     }
3163   else if (type->float_type() != NULL)
3164     {
3165       if (expr_type->integer_type() != NULL
3166           || expr_type->float_type() != NULL)
3167         ret = fold(convert_to_real(type_tree, expr_tree));
3168       else
3169         gcc_unreachable();
3170     }
3171   else if (type->complex_type() != NULL)
3172     {
3173       if (expr_type->complex_type() != NULL)
3174         ret = fold(convert_to_complex(type_tree, expr_tree));
3175       else
3176         gcc_unreachable();
3177     }
3178   else if (type->is_string_type()
3179            && expr_type->integer_type() != NULL)
3180     {
3181       expr_tree = fold_convert(integer_type_node, expr_tree);
3182       if (host_integerp(expr_tree, 0))
3183         {
3184           HOST_WIDE_INT intval = tree_low_cst(expr_tree, 0);
3185           std::string s;
3186           Lex::append_char(intval, true, &s, this->location());
3187           Expression* se = Expression::make_string(s, this->location());
3188           return se->get_tree(context);
3189         }
3190
3191       static tree int_to_string_fndecl;
3192       ret = Gogo::call_builtin(&int_to_string_fndecl,
3193                                this->location(),
3194                                "__go_int_to_string",
3195                                1,
3196                                type_tree,
3197                                integer_type_node,
3198                                fold_convert(integer_type_node, expr_tree));
3199     }
3200   else if (type->is_string_type()
3201            && (expr_type->array_type() != NULL
3202                || (expr_type->points_to() != NULL
3203                    && expr_type->points_to()->array_type() != NULL)))
3204     {
3205       Type* t = expr_type;
3206       if (t->points_to() != NULL)
3207         {
3208           t = t->points_to();
3209           expr_tree = build_fold_indirect_ref(expr_tree);
3210         }
3211       if (!DECL_P(expr_tree))
3212         expr_tree = save_expr(expr_tree);
3213       Array_type* a = t->array_type();
3214       Type* e = a->element_type()->forwarded();
3215       gcc_assert(e->integer_type() != NULL);
3216       tree valptr = fold_convert(const_ptr_type_node,
3217                                  a->value_pointer_tree(gogo, expr_tree));
3218       tree len = a->length_tree(gogo, expr_tree);
3219       len = fold_convert_loc(this->location(), size_type_node, len);
3220       if (e->integer_type()->is_unsigned()
3221           && e->integer_type()->bits() == 8)
3222         {
3223           static tree byte_array_to_string_fndecl;
3224           ret = Gogo::call_builtin(&byte_array_to_string_fndecl,
3225                                    this->location(),
3226                                    "__go_byte_array_to_string",
3227                                    2,
3228                                    type_tree,
3229                                    const_ptr_type_node,
3230                                    valptr,
3231                                    size_type_node,
3232                                    len);
3233         }
3234       else
3235         {
3236           gcc_assert(e == Type::lookup_integer_type("int"));
3237           static tree int_array_to_string_fndecl;
3238           ret = Gogo::call_builtin(&int_array_to_string_fndecl,
3239                                    this->location(),
3240                                    "__go_int_array_to_string",
3241                                    2,
3242                                    type_tree,
3243                                    const_ptr_type_node,
3244                                    valptr,
3245                                    size_type_node,
3246                                    len);
3247         }
3248     }
3249   else if (type->is_open_array_type() && expr_type->is_string_type())
3250     {
3251       Type* e = type->array_type()->element_type()->forwarded();
3252       gcc_assert(e->integer_type() != NULL);
3253       if (e->integer_type()->is_unsigned()
3254           && e->integer_type()->bits() == 8)
3255         {
3256           static tree string_to_byte_array_fndecl;
3257           ret = Gogo::call_builtin(&string_to_byte_array_fndecl,
3258                                    this->location(),
3259                                    "__go_string_to_byte_array",
3260                                    1,
3261                                    type_tree,
3262                                    TREE_TYPE(expr_tree),
3263                                    expr_tree);
3264         }
3265       else
3266         {
3267           gcc_assert(e == Type::lookup_integer_type("int"));
3268           static tree string_to_int_array_fndecl;
3269           ret = Gogo::call_builtin(&string_to_int_array_fndecl,
3270                                    this->location(),
3271                                    "__go_string_to_int_array",
3272                                    1,
3273                                    type_tree,
3274                                    TREE_TYPE(expr_tree),
3275                                    expr_tree);
3276         }
3277     }
3278   else if ((type->is_unsafe_pointer_type()
3279             && expr_type->points_to() != NULL)
3280            || (expr_type->is_unsafe_pointer_type()
3281                && type->points_to() != NULL))
3282     ret = fold_convert(type_tree, expr_tree);
3283   else if (type->is_unsafe_pointer_type()
3284            && expr_type->integer_type() != NULL)
3285     ret = convert_to_pointer(type_tree, expr_tree);
3286   else if (this->may_convert_function_types_
3287            && type->function_type() != NULL
3288            && expr_type->function_type() != NULL)
3289     ret = fold_convert_loc(this->location(), type_tree, expr_tree);
3290   else
3291     ret = Expression::convert_for_assignment(context, type, expr_type,
3292                                              expr_tree, this->location());
3293
3294   return ret;
3295 }
3296
3297 // Output a type conversion in a constant expression.
3298
3299 void
3300 Type_conversion_expression::do_export(Export* exp) const
3301 {
3302   exp->write_c_string("convert(");
3303   exp->write_type(this->type_);
3304   exp->write_c_string(", ");
3305   this->expr_->export_expression(exp);
3306   exp->write_c_string(")");
3307 }
3308
3309 // Import a type conversion or a struct construction.
3310
3311 Expression*
3312 Type_conversion_expression::do_import(Import* imp)
3313 {
3314   imp->require_c_string("convert(");
3315   Type* type = imp->read_type();
3316   imp->require_c_string(", ");
3317   Expression* val = Expression::import_expression(imp);
3318   imp->require_c_string(")");
3319   return Expression::make_cast(type, val, imp->location());
3320 }
3321
3322 // Make a type cast expression.
3323
3324 Expression*
3325 Expression::make_cast(Type* type, Expression* val, source_location location)
3326 {
3327   if (type->is_error_type() || val->is_error_expression())
3328     return Expression::make_error(location);
3329   return new Type_conversion_expression(type, val, location);
3330 }
3331
3332 // Unary expressions.
3333
3334 class Unary_expression : public Expression
3335 {
3336  public:
3337   Unary_expression(Operator op, Expression* expr, source_location location)
3338     : Expression(EXPRESSION_UNARY, location),
3339       op_(op), escapes_(true), expr_(expr)
3340   { }
3341
3342   // Return the operator.
3343   Operator
3344   op() const
3345   { return this->op_; }
3346
3347   // Return the operand.
3348   Expression*
3349   operand() const
3350   { return this->expr_; }
3351
3352   // Record that an address expression does not escape.
3353   void
3354   set_does_not_escape()
3355   {
3356     gcc_assert(this->op_ == OPERATOR_AND);
3357     this->escapes_ = false;
3358   }
3359
3360   // Apply unary opcode OP to UVAL, setting VAL.  Return true if this
3361   // could be done, false if not.
3362   static bool
3363   eval_integer(Operator op, Type* utype, mpz_t uval, mpz_t val,
3364                source_location);
3365
3366   // Apply unary opcode OP to UVAL, setting VAL.  Return true if this
3367   // could be done, false if not.
3368   static bool
3369   eval_float(Operator op, mpfr_t uval, mpfr_t val);
3370
3371   // Apply unary opcode OP to UREAL/UIMAG, setting REAL/IMAG.  Return
3372   // true if this could be done, false if not.
3373   static bool
3374   eval_complex(Operator op, mpfr_t ureal, mpfr_t uimag, mpfr_t real,
3375                mpfr_t imag);
3376
3377   static Expression*
3378   do_import(Import*);
3379
3380  protected:
3381   int
3382   do_traverse(Traverse* traverse)
3383   { return Expression::traverse(&this->expr_, traverse); }
3384
3385   Expression*
3386   do_lower(Gogo*, Named_object*, int);
3387
3388   bool
3389   do_is_constant() const;
3390
3391   bool
3392   do_integer_constant_value(bool, mpz_t, Type**) const;
3393
3394   bool
3395   do_float_constant_value(mpfr_t, Type**) const;
3396
3397   bool
3398   do_complex_constant_value(mpfr_t, mpfr_t, Type**) const;
3399
3400   Type*
3401   do_type();
3402
3403   void
3404   do_determine_type(const Type_context*);
3405
3406   void
3407   do_check_types(Gogo*);
3408
3409   Expression*
3410   do_copy()
3411   {
3412     return Expression::make_unary(this->op_, this->expr_->copy(),
3413                                   this->location());
3414   }
3415
3416   bool
3417   do_is_addressable() const
3418   { return this->op_ == OPERATOR_MULT; }
3419
3420   tree
3421   do_get_tree(Translate_context*);
3422
3423   void
3424   do_export(Export*) const;
3425
3426  private:
3427   // The unary operator to apply.
3428   Operator op_;
3429   // Normally true.  False if this is an address expression which does
3430   // not escape the current function.
3431   bool escapes_;
3432   // The operand.
3433   Expression* expr_;
3434 };
3435
3436 // If we are taking the address of a composite literal, and the
3437 // contents are not constant, then we want to make a heap composite
3438 // instead.
3439
3440 Expression*
3441 Unary_expression::do_lower(Gogo*, Named_object*, int)
3442 {
3443   source_location loc = this->location();
3444   Operator op = this->op_;
3445   Expression* expr = this->expr_;
3446
3447   if (op == OPERATOR_MULT && expr->is_type_expression())
3448     return Expression::make_type(Type::make_pointer_type(expr->type()), loc);
3449
3450   // *&x simplifies to x.  *(*T)(unsafe.Pointer)(&x) does not require
3451   // moving x to the heap.  FIXME: Is it worth doing a real escape
3452   // analysis here?  This case is found in math/unsafe.go and is
3453   // therefore worth special casing.
3454   if (op == OPERATOR_MULT)
3455     {
3456       Expression* e = expr;
3457       while (e->classification() == EXPRESSION_CONVERSION)
3458         {
3459           Type_conversion_expression* te
3460             = static_cast<Type_conversion_expression*>(e);
3461           e = te->expr();
3462         }
3463
3464       if (e->classification() == EXPRESSION_UNARY)
3465         {
3466           Unary_expression* ue = static_cast<Unary_expression*>(e);
3467           if (ue->op_ == OPERATOR_AND)
3468             {
3469               if (e == expr)
3470                 {
3471                   // *&x == x.
3472                   return ue->expr_;
3473                 }
3474               ue->set_does_not_escape();
3475             }
3476         }
3477     }
3478
3479   if (op == OPERATOR_PLUS || op == OPERATOR_MINUS
3480       || op == OPERATOR_NOT || op == OPERATOR_XOR)
3481     {
3482       Expression* ret = NULL;
3483
3484       mpz_t eval;
3485       mpz_init(eval);
3486       Type* etype;
3487       if (expr->integer_constant_value(false, eval, &etype))
3488         {
3489           mpz_t val;
3490           mpz_init(val);
3491           if (Unary_expression::eval_integer(op, etype, eval, val, loc))
3492             ret = Expression::make_integer(&val, etype, loc);
3493           mpz_clear(val);
3494         }
3495       mpz_clear(eval);
3496       if (ret != NULL)
3497         return ret;
3498
3499       if (op == OPERATOR_PLUS || op == OPERATOR_MINUS)
3500         {
3501           mpfr_t fval;
3502           mpfr_init(fval);
3503           Type* ftype;
3504           if (expr->float_constant_value(fval, &ftype))
3505             {
3506               mpfr_t val;
3507               mpfr_init(val);
3508               if (Unary_expression::eval_float(op, fval, val))
3509                 ret = Expression::make_float(&val, ftype, loc);
3510               mpfr_clear(val);
3511             }
3512           if (ret != NULL)
3513             {
3514               mpfr_clear(fval);
3515               return ret;
3516             }
3517
3518           mpfr_t ival;
3519           mpfr_init(ival);
3520           if (expr->complex_constant_value(fval, ival, &ftype))
3521             {
3522               mpfr_t real;
3523               mpfr_t imag;
3524               mpfr_init(real);
3525               mpfr_init(imag);
3526               if (Unary_expression::eval_complex(op, fval, ival, real, imag))
3527                 ret = Expression::make_complex(&real, &imag, ftype, loc);
3528               mpfr_clear(real);
3529               mpfr_clear(imag);
3530             }
3531           mpfr_clear(ival);
3532           mpfr_clear(fval);
3533           if (ret != NULL)
3534             return ret;
3535         }
3536     }
3537
3538   return this;
3539 }
3540
3541 // Return whether a unary expression is a constant.
3542
3543 bool
3544 Unary_expression::do_is_constant() const
3545 {
3546   if (this->op_ == OPERATOR_MULT)
3547     {
3548       // Indirecting through a pointer is only constant if the object
3549       // to which the expression points is constant, but we currently
3550       // have no way to determine that.
3551       return false;
3552     }
3553   else if (this->op_ == OPERATOR_AND)
3554     {
3555       // Taking the address of a variable is constant if it is a
3556       // global variable, not constant otherwise.  In other cases
3557       // taking the address is probably not a constant.
3558       Var_expression* ve = this->expr_->var_expression();
3559       if (ve != NULL)
3560         {
3561           Named_object* no = ve->named_object();
3562           return no->is_variable() && no->var_value()->is_global();
3563         }
3564       return false;
3565     }
3566   else
3567     return this->expr_->is_constant();
3568 }
3569
3570 // Apply unary opcode OP to UVAL, setting VAL.  UTYPE is the type of
3571 // UVAL, if known; it may be NULL.  Return true if this could be done,
3572 // false if not.
3573
3574 bool
3575 Unary_expression::eval_integer(Operator op, Type* utype, mpz_t uval, mpz_t val,
3576                                source_location location)
3577 {
3578   switch (op)
3579     {
3580     case OPERATOR_PLUS:
3581       mpz_set(val, uval);
3582       return true;
3583     case OPERATOR_MINUS:
3584       mpz_neg(val, uval);
3585       return Integer_expression::check_constant(val, utype, location);
3586     case OPERATOR_NOT:
3587       mpz_set_ui(val, mpz_cmp_si(uval, 0) == 0 ? 1 : 0);
3588       return true;
3589     case OPERATOR_XOR:
3590       if (utype == NULL
3591           || utype->integer_type() == NULL
3592           || utype->integer_type()->is_abstract())
3593         mpz_com(val, uval);
3594       else
3595         {
3596           // The number of HOST_WIDE_INTs that it takes to represent
3597           // UVAL.
3598           size_t count = ((mpz_sizeinbase(uval, 2)
3599                            + HOST_BITS_PER_WIDE_INT
3600                            - 1)
3601                           / HOST_BITS_PER_WIDE_INT);
3602
3603           unsigned HOST_WIDE_INT* phwi = new unsigned HOST_WIDE_INT[count];
3604           memset(phwi, 0, count * sizeof(HOST_WIDE_INT));
3605
3606           size_t ecount;
3607           mpz_export(phwi, &ecount, -1, sizeof(HOST_WIDE_INT), 0, 0, uval);
3608           gcc_assert(ecount <= count);
3609
3610           // Trim down to the number of words required by the type.
3611           size_t obits = utype->integer_type()->bits();
3612           if (!utype->integer_type()->is_unsigned())
3613             ++obits;
3614           size_t ocount = ((obits + HOST_BITS_PER_WIDE_INT - 1)
3615                            / HOST_BITS_PER_WIDE_INT);
3616           gcc_assert(ocount <= ocount);
3617
3618           for (size_t i = 0; i < ocount; ++i)
3619             phwi[i] = ~phwi[i];
3620
3621           size_t clearbits = ocount * HOST_BITS_PER_WIDE_INT - obits;
3622           if (clearbits != 0)
3623             phwi[ocount - 1] &= (((unsigned HOST_WIDE_INT) (HOST_WIDE_INT) -1)
3624                                  >> clearbits);
3625
3626           mpz_import(val, ocount, -1, sizeof(HOST_WIDE_INT), 0, 0, phwi);
3627
3628           delete[] phwi;
3629         }
3630       return Integer_expression::check_constant(val, utype, location);
3631     case OPERATOR_AND:
3632     case OPERATOR_MULT:
3633       return false;
3634     default:
3635       gcc_unreachable();
3636     }
3637 }
3638
3639 // Apply unary opcode OP to UVAL, setting VAL.  Return true if this
3640 // could be done, false if not.
3641
3642 bool
3643 Unary_expression::eval_float(Operator op, mpfr_t uval, mpfr_t val)
3644 {
3645   switch (op)
3646     {
3647     case OPERATOR_PLUS:
3648       mpfr_set(val, uval, GMP_RNDN);
3649       return true;
3650     case OPERATOR_MINUS:
3651       mpfr_neg(val, uval, GMP_RNDN);
3652       return true;
3653     case OPERATOR_NOT:
3654     case OPERATOR_XOR:
3655     case OPERATOR_AND:
3656     case OPERATOR_MULT:
3657       return false;
3658     default:
3659       gcc_unreachable();
3660     }
3661 }
3662
3663 // Apply unary opcode OP to RVAL/IVAL, setting REAL/IMAG.  Return true
3664 // if this could be done, false if not.
3665
3666 bool
3667 Unary_expression::eval_complex(Operator op, mpfr_t rval, mpfr_t ival,
3668                                mpfr_t real, mpfr_t imag)
3669 {
3670   switch (op)
3671     {
3672     case OPERATOR_PLUS:
3673       mpfr_set(real, rval, GMP_RNDN);
3674       mpfr_set(imag, ival, GMP_RNDN);
3675       return true;
3676     case OPERATOR_MINUS:
3677       mpfr_neg(real, rval, GMP_RNDN);
3678       mpfr_neg(imag, ival, GMP_RNDN);
3679       return true;
3680     case OPERATOR_NOT:
3681     case OPERATOR_XOR:
3682     case OPERATOR_AND:
3683     case OPERATOR_MULT:
3684       return false;
3685     default:
3686       gcc_unreachable();
3687     }
3688 }
3689
3690 // Return the integral constant value of a unary expression, if it has one.
3691
3692 bool
3693 Unary_expression::do_integer_constant_value(bool iota_is_constant, mpz_t val,
3694                                             Type** ptype) const
3695 {
3696   mpz_t uval;
3697   mpz_init(uval);
3698   bool ret;
3699   if (!this->expr_->integer_constant_value(iota_is_constant, uval, ptype))
3700     ret = false;
3701   else
3702     ret = Unary_expression::eval_integer(this->op_, *ptype, uval, val,
3703                                          this->location());
3704   mpz_clear(uval);
3705   return ret;
3706 }
3707
3708 // Return the floating point constant value of a unary expression, if
3709 // it has one.
3710
3711 bool
3712 Unary_expression::do_float_constant_value(mpfr_t val, Type** ptype) const
3713 {
3714   mpfr_t uval;
3715   mpfr_init(uval);
3716   bool ret;
3717   if (!this->expr_->float_constant_value(uval, ptype))
3718     ret = false;
3719   else
3720     ret = Unary_expression::eval_float(this->op_, uval, val);
3721   mpfr_clear(uval);
3722   return ret;
3723 }
3724
3725 // Return the complex constant value of a unary expression, if it has
3726 // one.
3727
3728 bool
3729 Unary_expression::do_complex_constant_value(mpfr_t real, mpfr_t imag,
3730                                             Type** ptype) const
3731 {
3732   mpfr_t rval;
3733   mpfr_t ival;
3734   mpfr_init(rval);
3735   mpfr_init(ival);
3736   bool ret;
3737   if (!this->expr_->complex_constant_value(rval, ival, ptype))
3738     ret = false;
3739   else
3740     ret = Unary_expression::eval_complex(this->op_, rval, ival, real, imag);
3741   mpfr_clear(rval);
3742   mpfr_clear(ival);
3743   return ret;
3744 }
3745
3746 // Return the type of a unary expression.
3747
3748 Type*
3749 Unary_expression::do_type()
3750 {
3751   switch (this->op_)
3752     {
3753     case OPERATOR_PLUS:
3754     case OPERATOR_MINUS:
3755     case OPERATOR_NOT:
3756     case OPERATOR_XOR:
3757       return this->expr_->type();
3758
3759     case OPERATOR_AND:
3760       return Type::make_pointer_type(this->expr_->type());
3761
3762     case OPERATOR_MULT:
3763       {
3764         Type* subtype = this->expr_->type();
3765         Type* points_to = subtype->points_to();
3766         if (points_to == NULL)
3767           return Type::make_error_type();
3768         return points_to;
3769       }
3770
3771     default:
3772       gcc_unreachable();
3773     }
3774 }
3775
3776 // Determine abstract types for a unary expression.
3777
3778 void
3779 Unary_expression::do_determine_type(const Type_context* context)
3780 {
3781   switch (this->op_)
3782     {
3783     case OPERATOR_PLUS:
3784     case OPERATOR_MINUS:
3785     case OPERATOR_NOT:
3786     case OPERATOR_XOR:
3787       this->expr_->determine_type(context);
3788       break;
3789
3790     case OPERATOR_AND:
3791       // Taking the address of something.
3792       {
3793         Type* subtype = (context->type == NULL
3794                          ? NULL
3795                          : context->type->points_to());
3796         Type_context subcontext(subtype, false);
3797         this->expr_->determine_type(&subcontext);
3798       }
3799       break;
3800
3801     case OPERATOR_MULT:
3802       // Indirecting through a pointer.
3803       {
3804         Type* subtype = (context->type == NULL
3805                          ? NULL
3806                          : Type::make_pointer_type(context->type));
3807         Type_context subcontext(subtype, false);
3808         this->expr_->determine_type(&subcontext);
3809       }
3810       break;
3811
3812     default:
3813       gcc_unreachable();
3814     }
3815 }
3816
3817 // Check types for a unary expression.
3818
3819 void
3820 Unary_expression::do_check_types(Gogo*)
3821 {
3822   switch (this->op_)
3823     {
3824     case OPERATOR_PLUS:
3825     case OPERATOR_MINUS:
3826       {
3827         Type* type = this->expr_->type();
3828         if (type->integer_type() == NULL
3829             && type->float_type() == NULL
3830             && type->complex_type() == NULL
3831             && !type->is_error_type())
3832           this->report_error(_("expected numeric type"));
3833       }
3834       break;
3835
3836     case OPERATOR_NOT:
3837     case OPERATOR_XOR:
3838       {
3839         Type* type = this->expr_->type();
3840         if (type->integer_type() == NULL
3841             && !type->is_boolean_type()
3842             && !type->is_error_type())
3843           this->report_error(_("expected integer or boolean type"));
3844       }
3845       break;
3846
3847     case OPERATOR_AND:
3848       if (!this->expr_->is_addressable())
3849         this->report_error(_("invalid operand for unary %<&%>"));
3850       else
3851         this->expr_->address_taken(this->escapes_);
3852       break;
3853
3854     case OPERATOR_MULT:
3855       // Indirecting through a pointer.
3856       {
3857         Type* type = this->expr_->type();
3858         if (type->points_to() == NULL
3859             && !type->is_error_type())
3860           this->report_error(_("expected pointer"));
3861       }
3862       break;
3863
3864     default:
3865       gcc_unreachable();
3866     }
3867 }
3868
3869 // Get a tree for a unary expression.
3870
3871 tree
3872 Unary_expression::do_get_tree(Translate_context* context)
3873 {
3874   tree expr = this->expr_->get_tree(context);
3875   if (expr == error_mark_node)
3876     return error_mark_node;
3877
3878   source_location loc = this->location();
3879   switch (this->op_)
3880     {
3881     case OPERATOR_PLUS:
3882       return expr;
3883
3884     case OPERATOR_MINUS:
3885       {
3886         tree type = TREE_TYPE(expr);
3887         tree compute_type = excess_precision_type(type);
3888         if (compute_type != NULL_TREE)
3889           expr = ::convert(compute_type, expr);
3890         tree ret = fold_build1_loc(loc, NEGATE_EXPR,
3891                                    (compute_type != NULL_TREE
3892                                     ? compute_type
3893                                     : type),
3894                                    expr);
3895         if (compute_type != NULL_TREE)
3896           ret = ::convert(type, ret);
3897         return ret;
3898       }
3899
3900     case OPERATOR_NOT:
3901       if (TREE_CODE(TREE_TYPE(expr)) == BOOLEAN_TYPE)
3902         return fold_build1_loc(loc, TRUTH_NOT_EXPR, TREE_TYPE(expr), expr);
3903       else
3904         return fold_build2_loc(loc, NE_EXPR, boolean_type_node, expr,
3905                                build_int_cst(TREE_TYPE(expr), 0));
3906
3907     case OPERATOR_XOR:
3908       return fold_build1_loc(loc, BIT_NOT_EXPR, TREE_TYPE(expr), expr);
3909
3910     case OPERATOR_AND:
3911       // We should not see a non-constant constructor here; cases
3912       // where we would see one should have been moved onto the heap
3913       // at parse time.  Taking the address of a nonconstant
3914       // constructor will not do what the programmer expects.
3915       gcc_assert(TREE_CODE(expr) != CONSTRUCTOR || TREE_CONSTANT(expr));
3916       gcc_assert(TREE_CODE(expr) != ADDR_EXPR);
3917
3918       // Build a decl for a constant constructor.
3919       if (TREE_CODE(expr) == CONSTRUCTOR && TREE_CONSTANT(expr))
3920         {
3921           tree decl = build_decl(this->location(), VAR_DECL,
3922                                  create_tmp_var_name("C"), TREE_TYPE(expr));
3923           DECL_EXTERNAL(decl) = 0;
3924           TREE_PUBLIC(decl) = 0;
3925           TREE_READONLY(decl) = 1;
3926           TREE_CONSTANT(decl) = 1;
3927           TREE_STATIC(decl) = 1;
3928           TREE_ADDRESSABLE(decl) = 1;
3929           DECL_ARTIFICIAL(decl) = 1;
3930           DECL_INITIAL(decl) = expr;
3931           rest_of_decl_compilation(decl, 1, 0);
3932           expr = decl;
3933         }
3934
3935       return build_fold_addr_expr_loc(loc, expr);
3936
3937     case OPERATOR_MULT:
3938       {
3939         gcc_assert(POINTER_TYPE_P(TREE_TYPE(expr)));
3940
3941         // If we are dereferencing the pointer to a large struct, we
3942         // need to check for nil.  We don't bother to check for small
3943         // structs because we expect the system to crash on a nil
3944         // pointer dereference.
3945         HOST_WIDE_INT s = int_size_in_bytes(TREE_TYPE(TREE_TYPE(expr)));
3946         if (s == -1 || s >= 4096)
3947           {
3948             if (!DECL_P(expr))
3949               expr = save_expr(expr);
3950             tree compare = fold_build2_loc(loc, EQ_EXPR, boolean_type_node,
3951                                            expr,
3952                                            fold_convert(TREE_TYPE(expr),
3953                                                         null_pointer_node));
3954             tree crash = Gogo::runtime_error(RUNTIME_ERROR_NIL_DEREFERENCE,
3955                                              loc);
3956             expr = fold_build2_loc(loc, COMPOUND_EXPR, TREE_TYPE(expr),
3957                                    build3(COND_EXPR, void_type_node,
3958                                           compare, crash, NULL_TREE),
3959                                    expr);
3960           }
3961
3962         // If the type of EXPR is a recursive pointer type, then we
3963         // need to insert a cast before indirecting.
3964         if (TREE_TYPE(TREE_TYPE(expr)) == ptr_type_node)
3965           {
3966             Type* pt = this->expr_->type()->points_to();
3967             tree ind = pt->get_tree(context->gogo());
3968             expr = fold_convert_loc(loc, build_pointer_type(ind), expr);
3969           }
3970
3971         return build_fold_indirect_ref_loc(loc, expr);
3972       }
3973
3974     default:
3975       gcc_unreachable();
3976     }
3977 }
3978
3979 // Export a unary expression.
3980
3981 void
3982 Unary_expression::do_export(Export* exp) const
3983 {
3984   switch (this->op_)
3985     {
3986     case OPERATOR_PLUS:
3987       exp->write_c_string("+ ");
3988       break;
3989     case OPERATOR_MINUS:
3990       exp->write_c_string("- ");
3991       break;
3992     case OPERATOR_NOT:
3993       exp->write_c_string("! ");
3994       break;
3995     case OPERATOR_XOR:
3996       exp->write_c_string("^ ");
3997       break;
3998     case OPERATOR_AND:
3999     case OPERATOR_MULT:
4000     default:
4001       gcc_unreachable();
4002     }
4003   this->expr_->export_expression(exp);
4004 }
4005
4006 // Import a unary expression.
4007
4008 Expression*
4009 Unary_expression::do_import(Import* imp)
4010 {
4011   Operator op;
4012   switch (imp->get_char())
4013     {
4014     case '+':
4015       op = OPERATOR_PLUS;
4016       break;
4017     case '-':
4018       op = OPERATOR_MINUS;
4019       break;
4020     case '!':
4021       op = OPERATOR_NOT;
4022       break;
4023     case '^':
4024       op = OPERATOR_XOR;
4025       break;
4026     default:
4027       gcc_unreachable();
4028     }
4029   imp->require_c_string(" ");
4030   Expression* expr = Expression::import_expression(imp);
4031   return Expression::make_unary(op, expr, imp->location());
4032 }
4033
4034 // Make a unary expression.
4035
4036 Expression*
4037 Expression::make_unary(Operator op, Expression* expr, source_location location)
4038 {
4039   return new Unary_expression(op, expr, location);
4040 }
4041
4042 // If this is an indirection through a pointer, return the expression
4043 // being pointed through.  Otherwise return this.
4044
4045 Expression*
4046 Expression::deref()
4047 {
4048   if (this->classification_ == EXPRESSION_UNARY)
4049     {
4050       Unary_expression* ue = static_cast<Unary_expression*>(this);
4051       if (ue->op() == OPERATOR_MULT)
4052         return ue->operand();
4053     }
4054   return this;
4055 }
4056
4057 // Class Binary_expression.
4058
4059 // Traversal.
4060
4061 int
4062 Binary_expression::do_traverse(Traverse* traverse)
4063 {
4064   int t = Expression::traverse(&this->left_, traverse);
4065   if (t == TRAVERSE_EXIT)
4066     return TRAVERSE_EXIT;
4067   return Expression::traverse(&this->right_, traverse);
4068 }
4069
4070 // Compare integer constants according to OP.
4071
4072 bool
4073 Binary_expression::compare_integer(Operator op, mpz_t left_val,
4074                                    mpz_t right_val)
4075 {
4076   int i = mpz_cmp(left_val, right_val);
4077   switch (op)
4078     {
4079     case OPERATOR_EQEQ:
4080       return i == 0;
4081     case OPERATOR_NOTEQ:
4082       return i != 0;
4083     case OPERATOR_LT:
4084       return i < 0;
4085     case OPERATOR_LE:
4086       return i <= 0;
4087     case OPERATOR_GT:
4088       return i > 0;
4089     case OPERATOR_GE:
4090       return i >= 0;
4091     default:
4092       gcc_unreachable();
4093     }
4094 }
4095
4096 // Compare floating point constants according to OP.
4097
4098 bool
4099 Binary_expression::compare_float(Operator op, Type* type, mpfr_t left_val,
4100                                  mpfr_t right_val)
4101 {
4102   int i;
4103   if (type == NULL)
4104     i = mpfr_cmp(left_val, right_val);
4105   else
4106     {
4107       mpfr_t lv;
4108       mpfr_init_set(lv, left_val, GMP_RNDN);
4109       mpfr_t rv;
4110       mpfr_init_set(rv, right_val, GMP_RNDN);
4111       Float_expression::constrain_float(lv, type);
4112       Float_expression::constrain_float(rv, type);
4113       i = mpfr_cmp(lv, rv);
4114       mpfr_clear(lv);
4115       mpfr_clear(rv);
4116     }
4117   switch (op)
4118     {
4119     case OPERATOR_EQEQ:
4120       return i == 0;
4121     case OPERATOR_NOTEQ:
4122       return i != 0;
4123     case OPERATOR_LT:
4124       return i < 0;
4125     case OPERATOR_LE:
4126       return i <= 0;
4127     case OPERATOR_GT:
4128       return i > 0;
4129     case OPERATOR_GE:
4130       return i >= 0;
4131     default:
4132       gcc_unreachable();
4133     }
4134 }
4135
4136 // Compare complex constants according to OP.  Complex numbers may
4137 // only be compared for equality.
4138
4139 bool
4140 Binary_expression::compare_complex(Operator op, Type* type,
4141                                    mpfr_t left_real, mpfr_t left_imag,
4142                                    mpfr_t right_real, mpfr_t right_imag)
4143 {
4144   bool is_equal;
4145   if (type == NULL)
4146     is_equal = (mpfr_cmp(left_real, right_real) == 0
4147                 && mpfr_cmp(left_imag, right_imag) == 0);
4148   else
4149     {
4150       mpfr_t lr;
4151       mpfr_t li;
4152       mpfr_init_set(lr, left_real, GMP_RNDN);
4153       mpfr_init_set(li, left_imag, GMP_RNDN);
4154       mpfr_t rr;
4155       mpfr_t ri;
4156       mpfr_init_set(rr, right_real, GMP_RNDN);
4157       mpfr_init_set(ri, right_imag, GMP_RNDN);
4158       Complex_expression::constrain_complex(lr, li, type);
4159       Complex_expression::constrain_complex(rr, ri, type);
4160       is_equal = mpfr_cmp(lr, rr) == 0 && mpfr_cmp(li, ri) == 0;
4161       mpfr_clear(lr);
4162       mpfr_clear(li);
4163       mpfr_clear(rr);
4164       mpfr_clear(ri);
4165     }
4166   switch (op)
4167     {
4168     case OPERATOR_EQEQ:
4169       return is_equal;
4170     case OPERATOR_NOTEQ:
4171       return !is_equal;
4172     default:
4173       gcc_unreachable();
4174     }
4175 }
4176
4177 // Apply binary opcode OP to LEFT_VAL and RIGHT_VAL, setting VAL.
4178 // LEFT_TYPE is the type of LEFT_VAL, RIGHT_TYPE is the type of
4179 // RIGHT_VAL; LEFT_TYPE and/or RIGHT_TYPE may be NULL.  Return true if
4180 // this could be done, false if not.
4181
4182 bool
4183 Binary_expression::eval_integer(Operator op, Type* left_type, mpz_t left_val,
4184                                 Type* right_type, mpz_t right_val,
4185                                 source_location location, mpz_t val)
4186 {
4187   bool is_shift_op = false;
4188   switch (op)
4189     {
4190     case OPERATOR_OROR:
4191     case OPERATOR_ANDAND:
4192     case OPERATOR_EQEQ:
4193     case OPERATOR_NOTEQ:
4194     case OPERATOR_LT:
4195     case OPERATOR_LE:
4196     case OPERATOR_GT:
4197     case OPERATOR_GE:
4198       // These return boolean values.  We should probably handle them
4199       // anyhow in case a type conversion is used on the result.
4200       return false;
4201     case OPERATOR_PLUS:
4202       mpz_add(val, left_val, right_val);
4203       break;
4204     case OPERATOR_MINUS:
4205       mpz_sub(val, left_val, right_val);
4206       break;
4207     case OPERATOR_OR:
4208       mpz_ior(val, left_val, right_val);
4209       break;
4210     case OPERATOR_XOR:
4211       mpz_xor(val, left_val, right_val);
4212       break;
4213     case OPERATOR_MULT:
4214       mpz_mul(val, left_val, right_val);
4215       break;
4216     case OPERATOR_DIV:
4217       if (mpz_sgn(right_val) != 0)
4218         mpz_tdiv_q(val, left_val, right_val);
4219       else
4220         {
4221           error_at(location, "division by zero");
4222           mpz_set_ui(val, 0);
4223           return true;
4224         }
4225       break;
4226     case OPERATOR_MOD:
4227       if (mpz_sgn(right_val) != 0)
4228         mpz_tdiv_r(val, left_val, right_val);
4229       else
4230         {
4231           error_at(location, "division by zero");
4232           mpz_set_ui(val, 0);
4233           return true;
4234         }
4235       break;
4236     case OPERATOR_LSHIFT:
4237       {
4238         unsigned long shift = mpz_get_ui(right_val);
4239         if (mpz_cmp_ui(right_val, shift) != 0)
4240           {
4241             error_at(location, "shift count overflow");
4242             mpz_set_ui(val, 0);
4243             return true;
4244           }
4245         mpz_mul_2exp(val, left_val, shift);
4246         is_shift_op = true;
4247         break;
4248       }
4249       break;
4250     case OPERATOR_RSHIFT:
4251       {
4252         unsigned long shift = mpz_get_ui(right_val);
4253         if (mpz_cmp_ui(right_val, shift) != 0)
4254           {
4255             error_at(location, "shift count overflow");
4256             mpz_set_ui(val, 0);
4257             return true;
4258           }
4259         if (mpz_cmp_ui(left_val, 0) >= 0)
4260           mpz_tdiv_q_2exp(val, left_val, shift);
4261         else
4262           mpz_fdiv_q_2exp(val, left_val, shift);
4263         is_shift_op = true;
4264         break;
4265       }
4266       break;
4267     case OPERATOR_AND:
4268       mpz_and(val, left_val, right_val);
4269       break;
4270     case OPERATOR_BITCLEAR:
4271       {
4272         mpz_t tval;
4273         mpz_init(tval);
4274         mpz_com(tval, right_val);
4275         mpz_and(val, left_val, tval);
4276         mpz_clear(tval);
4277       }
4278       break;
4279     default:
4280       gcc_unreachable();
4281     }
4282
4283   Type* type = left_type;
4284   if (!is_shift_op)
4285     {
4286       if (type == NULL)
4287         type = right_type;
4288       else if (type != right_type && right_type != NULL)
4289         {
4290           if (type->is_abstract())
4291             type = right_type;
4292           else if (!right_type->is_abstract())
4293             {
4294               // This look like a type error which should be diagnosed
4295               // elsewhere.  Don't do anything here, to avoid an
4296               // unhelpful chain of error messages.
4297               return true;
4298             }
4299         }
4300     }
4301
4302   if (type != NULL && !type->is_abstract())
4303     {
4304       // We have to check the operands too, as we have implicitly
4305       // coerced them to TYPE.
4306       if ((type != left_type
4307            && !Integer_expression::check_constant(left_val, type, location))
4308           || (!is_shift_op
4309               && type != right_type
4310               && !Integer_expression::check_constant(right_val, type,
4311                                                      location))
4312           || !Integer_expression::check_constant(val, type, location))
4313         mpz_set_ui(val, 0);
4314     }
4315
4316   return true;
4317 }
4318
4319 // Apply binary opcode OP to LEFT_VAL and RIGHT_VAL, setting VAL.
4320 // Return true if this could be done, false if not.
4321
4322 bool
4323 Binary_expression::eval_float(Operator op, Type* left_type, mpfr_t left_val,
4324                               Type* right_type, mpfr_t right_val,
4325                               mpfr_t val, source_location location)
4326 {
4327   switch (op)
4328     {
4329     case OPERATOR_OROR:
4330     case OPERATOR_ANDAND:
4331     case OPERATOR_EQEQ:
4332     case OPERATOR_NOTEQ:
4333     case OPERATOR_LT:
4334     case OPERATOR_LE:
4335     case OPERATOR_GT:
4336     case OPERATOR_GE:
4337       // These return boolean values.  We should probably handle them
4338       // anyhow in case a type conversion is used on the result.
4339       return false;
4340     case OPERATOR_PLUS:
4341       mpfr_add(val, left_val, right_val, GMP_RNDN);
4342       break;
4343     case OPERATOR_MINUS:
4344       mpfr_sub(val, left_val, right_val, GMP_RNDN);
4345       break;
4346     case OPERATOR_OR:
4347     case OPERATOR_XOR:
4348     case OPERATOR_AND:
4349     case OPERATOR_BITCLEAR:
4350       return false;
4351     case OPERATOR_MULT:
4352       mpfr_mul(val, left_val, right_val, GMP_RNDN);
4353       break;
4354     case OPERATOR_DIV:
4355       if (mpfr_zero_p(right_val))
4356         error_at(location, "division by zero");
4357       mpfr_div(val, left_val, right_val, GMP_RNDN);
4358       break;
4359     case OPERATOR_MOD:
4360       return false;
4361     case OPERATOR_LSHIFT:
4362     case OPERATOR_RSHIFT:
4363       return false;
4364     default:
4365       gcc_unreachable();
4366     }
4367
4368   Type* type = left_type;
4369   if (type == NULL)
4370     type = right_type;
4371   else if (type != right_type && right_type != NULL)
4372     {
4373       if (type->is_abstract())
4374         type = right_type;
4375       else if (!right_type->is_abstract())
4376         {
4377           // This looks like a type error which should be diagnosed
4378           // elsewhere.  Don't do anything here, to avoid an unhelpful
4379           // chain of error messages.
4380           return true;
4381         }
4382     }
4383
4384   if (type != NULL && !type->is_abstract())
4385     {
4386       if ((type != left_type
4387            && !Float_expression::check_constant(left_val, type, location))
4388           || (type != right_type
4389               && !Float_expression::check_constant(right_val, type,
4390                                                    location))
4391           || !Float_expression::check_constant(val, type, location))
4392         mpfr_set_ui(val, 0, GMP_RNDN);
4393     }
4394
4395   return true;
4396 }
4397
4398 // Apply binary opcode OP to LEFT_REAL/LEFT_IMAG and
4399 // RIGHT_REAL/RIGHT_IMAG, setting REAL/IMAG.  Return true if this
4400 // could be done, false if not.
4401
4402 bool
4403 Binary_expression::eval_complex(Operator op, Type* left_type,
4404                                 mpfr_t left_real, mpfr_t left_imag,
4405                                 Type *right_type,
4406                                 mpfr_t right_real, mpfr_t right_imag,
4407                                 mpfr_t real, mpfr_t imag,
4408                                 source_location location)
4409 {
4410   switch (op)
4411     {
4412     case OPERATOR_OROR:
4413     case OPERATOR_ANDAND:
4414     case OPERATOR_EQEQ:
4415     case OPERATOR_NOTEQ:
4416     case OPERATOR_LT:
4417     case OPERATOR_LE:
4418     case OPERATOR_GT:
4419     case OPERATOR_GE:
4420       // These return boolean values and must be handled differently.
4421       return false;
4422     case OPERATOR_PLUS:
4423       mpfr_add(real, left_real, right_real, GMP_RNDN);
4424       mpfr_add(imag, left_imag, right_imag, GMP_RNDN);
4425       break;
4426     case OPERATOR_MINUS:
4427       mpfr_sub(real, left_real, right_real, GMP_RNDN);
4428       mpfr_sub(imag, left_imag, right_imag, GMP_RNDN);
4429       break;
4430     case OPERATOR_OR:
4431     case OPERATOR_XOR:
4432     case OPERATOR_AND:
4433     case OPERATOR_BITCLEAR:
4434       return false;
4435     case OPERATOR_MULT:
4436       {
4437         // You might think that multiplying two complex numbers would
4438         // be simple, and you would be right, until you start to think
4439         // about getting the right answer for infinity.  If one
4440         // operand here is infinity and the other is anything other
4441         // than zero or NaN, then we are going to wind up subtracting
4442         // two infinity values.  That will give us a NaN, but the
4443         // correct answer is infinity.
4444
4445         mpfr_t lrrr;
4446         mpfr_init(lrrr);
4447         mpfr_mul(lrrr, left_real, right_real, GMP_RNDN);
4448
4449         mpfr_t lrri;
4450         mpfr_init(lrri);
4451         mpfr_mul(lrri, left_real, right_imag, GMP_RNDN);
4452
4453         mpfr_t lirr;
4454         mpfr_init(lirr);
4455         mpfr_mul(lirr, left_imag, right_real, GMP_RNDN);
4456
4457         mpfr_t liri;
4458         mpfr_init(liri);
4459         mpfr_mul(liri, left_imag, right_imag, GMP_RNDN);
4460
4461         mpfr_sub(real, lrrr, liri, GMP_RNDN);
4462         mpfr_add(imag, lrri, lirr, GMP_RNDN);
4463
4464         // If we get NaN on both sides, check whether it should really
4465         // be infinity.  The rule is that if either side of the
4466         // complex number is infinity, then the whole value is
4467         // infinity, even if the other side is NaN.  So the only case
4468         // we have to fix is the one in which both sides are NaN.
4469         if (mpfr_nan_p(real) && mpfr_nan_p(imag)
4470             && (!mpfr_nan_p(left_real) || !mpfr_nan_p(left_imag))
4471             && (!mpfr_nan_p(right_real) || !mpfr_nan_p(right_imag)))
4472           {
4473             bool is_infinity = false;
4474
4475             mpfr_t lr;
4476             mpfr_t li;
4477             mpfr_init_set(lr, left_real, GMP_RNDN);
4478             mpfr_init_set(li, left_imag, GMP_RNDN);
4479
4480             mpfr_t rr;
4481             mpfr_t ri;
4482             mpfr_init_set(rr, right_real, GMP_RNDN);
4483             mpfr_init_set(ri, right_imag, GMP_RNDN);
4484
4485             // If the left side is infinity, then the result is
4486             // infinity.
4487             if (mpfr_inf_p(lr) || mpfr_inf_p(li))
4488               {
4489                 mpfr_set_ui(lr, mpfr_inf_p(lr) ? 1 : 0, GMP_RNDN);
4490                 mpfr_copysign(lr, lr, left_real, GMP_RNDN);
4491                 mpfr_set_ui(li, mpfr_inf_p(li) ? 1 : 0, GMP_RNDN);
4492                 mpfr_copysign(li, li, left_imag, GMP_RNDN);
4493                 if (mpfr_nan_p(rr))
4494                   {
4495                     mpfr_set_ui(rr, 0, GMP_RNDN);
4496                     mpfr_copysign(rr, rr, right_real, GMP_RNDN);
4497                   }
4498                 if (mpfr_nan_p(ri))
4499                   {
4500                     mpfr_set_ui(ri, 0, GMP_RNDN);
4501                     mpfr_copysign(ri, ri, right_imag, GMP_RNDN);
4502                   }
4503                 is_infinity = true;
4504               }
4505
4506             // If the right side is infinity, then the result is
4507             // infinity.
4508             if (mpfr_inf_p(rr) || mpfr_inf_p(ri))
4509               {
4510                 mpfr_set_ui(rr, mpfr_inf_p(rr) ? 1 : 0, GMP_RNDN);
4511                 mpfr_copysign(rr, rr, right_real, GMP_RNDN);
4512                 mpfr_set_ui(ri, mpfr_inf_p(ri) ? 1 : 0, GMP_RNDN);
4513                 mpfr_copysign(ri, ri, right_imag, GMP_RNDN);
4514                 if (mpfr_nan_p(lr))
4515                   {
4516                     mpfr_set_ui(lr, 0, GMP_RNDN);
4517                     mpfr_copysign(lr, lr, left_real, GMP_RNDN);
4518                   }
4519                 if (mpfr_nan_p(li))
4520                   {
4521                     mpfr_set_ui(li, 0, GMP_RNDN);
4522                     mpfr_copysign(li, li, left_imag, GMP_RNDN);
4523                   }
4524                 is_infinity = true;
4525               }
4526
4527             // If we got an overflow in the intermediate computations,
4528             // then the result is infinity.
4529             if (!is_infinity
4530                 && (mpfr_inf_p(lrrr) || mpfr_inf_p(lrri)
4531                     || mpfr_inf_p(lirr) || mpfr_inf_p(liri)))
4532               {
4533                 if (mpfr_nan_p(lr))
4534                   {
4535                     mpfr_set_ui(lr, 0, GMP_RNDN);
4536                     mpfr_copysign(lr, lr, left_real, GMP_RNDN);
4537                   }
4538                 if (mpfr_nan_p(li))
4539                   {
4540                     mpfr_set_ui(li, 0, GMP_RNDN);
4541                     mpfr_copysign(li, li, left_imag, GMP_RNDN);
4542                   }
4543                 if (mpfr_nan_p(rr))
4544                   {
4545                     mpfr_set_ui(rr, 0, GMP_RNDN);
4546                     mpfr_copysign(rr, rr, right_real, GMP_RNDN);
4547                   }
4548                 if (mpfr_nan_p(ri))
4549                   {
4550                     mpfr_set_ui(ri, 0, GMP_RNDN);
4551                     mpfr_copysign(ri, ri, right_imag, GMP_RNDN);
4552                   }
4553                 is_infinity = true;
4554               }
4555
4556             if (is_infinity)
4557               {
4558                 mpfr_mul(lrrr, lr, rr, GMP_RNDN);
4559                 mpfr_mul(lrri, lr, ri, GMP_RNDN);
4560                 mpfr_mul(lirr, li, rr, GMP_RNDN);
4561                 mpfr_mul(liri, li, ri, GMP_RNDN);
4562                 mpfr_sub(real, lrrr, liri, GMP_RNDN);
4563                 mpfr_add(imag, lrri, lirr, GMP_RNDN);
4564                 mpfr_set_inf(real, mpfr_sgn(real));
4565                 mpfr_set_inf(imag, mpfr_sgn(imag));
4566               }
4567
4568             mpfr_clear(lr);
4569             mpfr_clear(li);
4570             mpfr_clear(rr);
4571             mpfr_clear(ri);
4572           }
4573
4574         mpfr_clear(lrrr);
4575         mpfr_clear(lrri);
4576         mpfr_clear(lirr);
4577         mpfr_clear(liri);
4578       }
4579       break;
4580     case OPERATOR_DIV:
4581       {
4582         // For complex division we want to avoid having an
4583         // intermediate overflow turn the whole result in a NaN.  We
4584         // scale the values to try to avoid this.
4585
4586         if (mpfr_zero_p(right_real) && mpfr_zero_p(right_imag))
4587           error_at(location, "division by zero");
4588
4589         mpfr_t rra;
4590         mpfr_t ria;
4591         mpfr_init(rra);
4592         mpfr_init(ria);
4593         mpfr_abs(rra, right_real, GMP_RNDN);
4594         mpfr_abs(ria, right_imag, GMP_RNDN);
4595         mpfr_t t;
4596         mpfr_init(t);
4597         mpfr_max(t, rra, ria, GMP_RNDN);
4598
4599         mpfr_t rr;
4600         mpfr_t ri;
4601         mpfr_init_set(rr, right_real, GMP_RNDN);
4602         mpfr_init_set(ri, right_imag, GMP_RNDN);
4603         long ilogbw = 0;
4604         if (!mpfr_inf_p(t) && !mpfr_nan_p(t) && !mpfr_zero_p(t))
4605           {
4606             ilogbw = mpfr_get_exp(t);
4607             mpfr_mul_2si(rr, rr, - ilogbw, GMP_RNDN);
4608             mpfr_mul_2si(ri, ri, - ilogbw, GMP_RNDN);
4609           }
4610
4611         mpfr_t denom;
4612         mpfr_init(denom);
4613         mpfr_mul(denom, rr, rr, GMP_RNDN);
4614         mpfr_mul(t, ri, ri, GMP_RNDN);
4615         mpfr_add(denom, denom, t, GMP_RNDN);
4616
4617         mpfr_mul(real, left_real, rr, GMP_RNDN);
4618         mpfr_mul(t, left_imag, ri, GMP_RNDN);
4619         mpfr_add(real, real, t, GMP_RNDN);
4620         mpfr_div(real, real, denom, GMP_RNDN);
4621         mpfr_mul_2si(real, real, - ilogbw, GMP_RNDN);
4622
4623         mpfr_mul(imag, left_imag, rr, GMP_RNDN);
4624         mpfr_mul(t, left_real, ri, GMP_RNDN);
4625         mpfr_sub(imag, imag, t, GMP_RNDN);
4626         mpfr_div(imag, imag, denom, GMP_RNDN);
4627         mpfr_mul_2si(imag, imag, - ilogbw, GMP_RNDN);
4628
4629         // If we wind up with NaN on both sides, check whether we
4630         // should really have infinity.  The rule is that if either
4631         // side of the complex number is infinity, then the whole
4632         // value is infinity, even if the other side is NaN.  So the
4633         // only case we have to fix is the one in which both sides are
4634         // NaN.
4635         if (mpfr_nan_p(real) && mpfr_nan_p(imag)
4636             && (!mpfr_nan_p(left_real) || !mpfr_nan_p(left_imag))
4637             && (!mpfr_nan_p(right_real) || !mpfr_nan_p(right_imag)))
4638           {
4639             if (mpfr_zero_p(denom))
4640               {
4641                 mpfr_set_inf(real, mpfr_sgn(rr));
4642                 mpfr_mul(real, real, left_real, GMP_RNDN);
4643                 mpfr_set_inf(imag, mpfr_sgn(rr));
4644                 mpfr_mul(imag, imag, left_imag, GMP_RNDN);
4645               }
4646             else if ((mpfr_inf_p(left_real) || mpfr_inf_p(left_imag))
4647                      && mpfr_number_p(rr) && mpfr_number_p(ri))
4648               {
4649                 mpfr_set_ui(t, mpfr_inf_p(left_real) ? 1 : 0, GMP_RNDN);
4650                 mpfr_copysign(t, t, left_real, GMP_RNDN);
4651
4652                 mpfr_t t2;
4653                 mpfr_init_set_ui(t2, mpfr_inf_p(left_imag) ? 1 : 0, GMP_RNDN);
4654                 mpfr_copysign(t2, t2, left_imag, GMP_RNDN);
4655
4656                 mpfr_t t3;
4657                 mpfr_init(t3);
4658                 mpfr_mul(t3, t, rr, GMP_RNDN);
4659
4660                 mpfr_t t4;
4661                 mpfr_init(t4);
4662                 mpfr_mul(t4, t2, ri, GMP_RNDN);
4663
4664                 mpfr_add(t3, t3, t4, GMP_RNDN);
4665                 mpfr_set_inf(real, mpfr_sgn(t3));
4666
4667                 mpfr_mul(t3, t2, rr, GMP_RNDN);
4668                 mpfr_mul(t4, t, ri, GMP_RNDN);
4669                 mpfr_sub(t3, t3, t4, GMP_RNDN);
4670                 mpfr_set_inf(imag, mpfr_sgn(t3));
4671
4672                 mpfr_clear(t2);
4673                 mpfr_clear(t3);
4674                 mpfr_clear(t4);
4675               }
4676             else if ((mpfr_inf_p(right_real) || mpfr_inf_p(right_imag))
4677                      && mpfr_number_p(left_real) && mpfr_number_p(left_imag))
4678               {
4679                 mpfr_set_ui(t, mpfr_inf_p(rr) ? 1 : 0, GMP_RNDN);
4680                 mpfr_copysign(t, t, rr, GMP_RNDN);
4681
4682                 mpfr_t t2;
4683                 mpfr_init_set_ui(t2, mpfr_inf_p(ri) ? 1 : 0, GMP_RNDN);
4684                 mpfr_copysign(t2, t2, ri, GMP_RNDN);
4685
4686                 mpfr_t t3;
4687                 mpfr_init(t3);
4688                 mpfr_mul(t3, left_real, t, GMP_RNDN);
4689
4690                 mpfr_t t4;
4691                 mpfr_init(t4);
4692                 mpfr_mul(t4, left_imag, t2, GMP_RNDN);
4693
4694                 mpfr_add(t3, t3, t4, GMP_RNDN);
4695                 mpfr_set_ui(real, 0, GMP_RNDN);
4696                 mpfr_mul(real, real, t3, GMP_RNDN);
4697
4698                 mpfr_mul(t3, left_imag, t, GMP_RNDN);
4699                 mpfr_mul(t4, left_real, t2, GMP_RNDN);
4700                 mpfr_sub(t3, t3, t4, GMP_RNDN);
4701                 mpfr_set_ui(imag, 0, GMP_RNDN);
4702                 mpfr_mul(imag, imag, t3, GMP_RNDN);
4703
4704                 mpfr_clear(t2);
4705                 mpfr_clear(t3);
4706                 mpfr_clear(t4);
4707               }
4708           }
4709
4710         mpfr_clear(denom);
4711         mpfr_clear(rr);
4712         mpfr_clear(ri);
4713         mpfr_clear(t);
4714         mpfr_clear(rra);
4715         mpfr_clear(ria);
4716       }
4717       break;
4718     case OPERATOR_MOD:
4719       return false;
4720     case OPERATOR_LSHIFT:
4721     case OPERATOR_RSHIFT:
4722       return false;
4723     default:
4724       gcc_unreachable();
4725     }
4726
4727   Type* type = left_type;
4728   if (type == NULL)
4729     type = right_type;
4730   else if (type != right_type && right_type != NULL)
4731     {
4732       if (type->is_abstract())
4733         type = right_type;
4734       else if (!right_type->is_abstract())
4735         {
4736           // This looks like a type error which should be diagnosed
4737           // elsewhere.  Don't do anything here, to avoid an unhelpful
4738           // chain of error messages.
4739           return true;
4740         }
4741     }
4742
4743   if (type != NULL && !type->is_abstract())
4744     {
4745       if ((type != left_type
4746            && !Complex_expression::check_constant(left_real, left_imag,
4747                                                   type, location))
4748           || (type != right_type
4749               && !Complex_expression::check_constant(right_real, right_imag,
4750                                                      type, location))
4751           || !Complex_expression::check_constant(real, imag, type,
4752                                                  location))
4753         {
4754           mpfr_set_ui(real, 0, GMP_RNDN);
4755           mpfr_set_ui(imag, 0, GMP_RNDN);
4756         }
4757     }
4758
4759   return true;
4760 }
4761
4762 // Lower a binary expression.  We have to evaluate constant
4763 // expressions now, in order to implement Go's unlimited precision
4764 // constants.
4765
4766 Expression*
4767 Binary_expression::do_lower(Gogo*, Named_object*, int)
4768 {
4769   source_location location = this->location();
4770   Operator op = this->op_;
4771   Expression* left = this->left_;
4772   Expression* right = this->right_;
4773
4774   const bool is_comparison = (op == OPERATOR_EQEQ
4775                               || op == OPERATOR_NOTEQ
4776                               || op == OPERATOR_LT
4777                               || op == OPERATOR_LE
4778                               || op == OPERATOR_GT
4779                               || op == OPERATOR_GE);
4780
4781   // Integer constant expressions.
4782   {
4783     mpz_t left_val;
4784     mpz_init(left_val);
4785     Type* left_type;
4786     mpz_t right_val;
4787     mpz_init(right_val);
4788     Type* right_type;
4789     if (left->integer_constant_value(false, left_val, &left_type)
4790         && right->integer_constant_value(false, right_val, &right_type))
4791       {
4792         Expression* ret = NULL;
4793         if (left_type != right_type
4794             && left_type != NULL
4795             && right_type != NULL
4796             && left_type->base() != right_type->base()
4797             && op != OPERATOR_LSHIFT
4798             && op != OPERATOR_RSHIFT)
4799           {
4800             // May be a type error--let it be diagnosed later.
4801           }
4802         else if (is_comparison)
4803           {
4804             bool b = Binary_expression::compare_integer(op, left_val,
4805                                                         right_val);
4806             ret = Expression::make_cast(Type::lookup_bool_type(),
4807                                         Expression::make_boolean(b, location),
4808                                         location);
4809           }
4810         else
4811           {
4812             mpz_t val;
4813             mpz_init(val);
4814
4815             if (Binary_expression::eval_integer(op, left_type, left_val,
4816                                                 right_type, right_val,
4817                                                 location, val))
4818               {
4819                 gcc_assert(op != OPERATOR_OROR && op != OPERATOR_ANDAND);
4820                 Type* type;
4821                 if (op == OPERATOR_LSHIFT || op == OPERATOR_RSHIFT)
4822                   type = left_type;
4823                 else if (left_type == NULL)
4824                   type = right_type;
4825                 else if (right_type == NULL)
4826                   type = left_type;
4827                 else if (!left_type->is_abstract()
4828                          && left_type->named_type() != NULL)
4829                   type = left_type;
4830                 else if (!right_type->is_abstract()
4831                          && right_type->named_type() != NULL)
4832                   type = right_type;
4833                 else if (!left_type->is_abstract())
4834                   type = left_type;
4835                 else if (!right_type->is_abstract())
4836                   type = right_type;
4837                 else if (left_type->float_type() != NULL)
4838                   type = left_type;
4839                 else if (right_type->float_type() != NULL)
4840                   type = right_type;
4841                 else if (left_type->complex_type() != NULL)
4842                   type = left_type;
4843                 else if (right_type->complex_type() != NULL)
4844                   type = right_type;
4845                 else
4846                   type = left_type;
4847                 ret = Expression::make_integer(&val, type, location);
4848               }
4849
4850             mpz_clear(val);
4851           }
4852
4853         if (ret != NULL)
4854           {
4855             mpz_clear(right_val);
4856             mpz_clear(left_val);
4857             return ret;
4858           }
4859       }
4860     mpz_clear(right_val);
4861     mpz_clear(left_val);
4862   }
4863
4864   // Floating point constant expressions.
4865   {
4866     mpfr_t left_val;
4867     mpfr_init(left_val);
4868     Type* left_type;
4869     mpfr_t right_val;
4870     mpfr_init(right_val);
4871     Type* right_type;
4872     if (left->float_constant_value(left_val, &left_type)
4873         && right->float_constant_value(right_val, &right_type))
4874       {
4875         Expression* ret = NULL;
4876         if (left_type != right_type
4877             && left_type != NULL
4878             && right_type != NULL
4879             && left_type->base() != right_type->base()
4880             && op != OPERATOR_LSHIFT
4881             && op != OPERATOR_RSHIFT)
4882           {
4883             // May be a type error--let it be diagnosed later.
4884           }
4885         else if (is_comparison)
4886           {
4887             bool b = Binary_expression::compare_float(op,
4888                                                       (left_type != NULL
4889                                                        ? left_type
4890                                                        : right_type),
4891                                                       left_val, right_val);
4892             ret = Expression::make_boolean(b, location);
4893           }
4894         else
4895           {
4896             mpfr_t val;
4897             mpfr_init(val);
4898
4899             if (Binary_expression::eval_float(op, left_type, left_val,
4900                                               right_type, right_val, val,
4901                                               location))
4902               {
4903                 gcc_assert(op != OPERATOR_OROR && op != OPERATOR_ANDAND
4904                            && op != OPERATOR_LSHIFT && op != OPERATOR_RSHIFT);
4905                 Type* type;
4906                 if (left_type == NULL)
4907                   type = right_type;
4908                 else if (right_type == NULL)
4909                   type = left_type;
4910                 else if (!left_type->is_abstract()
4911                          && left_type->named_type() != NULL)
4912                   type = left_type;
4913                 else if (!right_type->is_abstract()
4914                          && right_type->named_type() != NULL)
4915                   type = right_type;
4916                 else if (!left_type->is_abstract())
4917                   type = left_type;
4918                 else if (!right_type->is_abstract())
4919                   type = right_type;
4920                 else if (left_type->float_type() != NULL)
4921                   type = left_type;
4922                 else if (right_type->float_type() != NULL)
4923                   type = right_type;
4924                 else
4925                   type = left_type;
4926                 ret = Expression::make_float(&val, type, location);
4927               }
4928
4929             mpfr_clear(val);
4930           }
4931
4932         if (ret != NULL)
4933           {
4934             mpfr_clear(right_val);
4935             mpfr_clear(left_val);
4936             return ret;
4937           }
4938       }
4939     mpfr_clear(right_val);
4940     mpfr_clear(left_val);
4941   }
4942
4943   // Complex constant expressions.
4944   {
4945     mpfr_t left_real;
4946     mpfr_t left_imag;
4947     mpfr_init(left_real);
4948     mpfr_init(left_imag);
4949     Type* left_type;
4950
4951     mpfr_t right_real;
4952     mpfr_t right_imag;
4953     mpfr_init(right_real);
4954     mpfr_init(right_imag);
4955     Type* right_type;
4956
4957     if (left->complex_constant_value(left_real, left_imag, &left_type)
4958         && right->complex_constant_value(right_real, right_imag, &right_type))
4959       {
4960         Expression* ret = NULL;
4961         if (left_type != right_type
4962             && left_type != NULL
4963             && right_type != NULL
4964             && left_type->base() != right_type->base())
4965           {
4966             // May be a type error--let it be diagnosed later.
4967           }
4968         else if (is_comparison)
4969           {
4970             bool b = Binary_expression::compare_complex(op,
4971                                                         (left_type != NULL
4972                                                          ? left_type
4973                                                          : right_type),
4974                                                         left_real,
4975                                                         left_imag,
4976                                                         right_real,
4977                                                         right_imag);
4978             ret = Expression::make_boolean(b, location);
4979           }
4980         else
4981           {
4982             mpfr_t real;
4983             mpfr_t imag;
4984             mpfr_init(real);
4985             mpfr_init(imag);
4986
4987             if (Binary_expression::eval_complex(op, left_type,
4988                                                 left_real, left_imag,
4989                                                 right_type,
4990                                                 right_real, right_imag,
4991                                                 real, imag,
4992                                                 location))
4993               {
4994                 gcc_assert(op != OPERATOR_OROR && op != OPERATOR_ANDAND
4995                            && op != OPERATOR_LSHIFT && op != OPERATOR_RSHIFT);
4996                 Type* type;
4997                 if (left_type == NULL)
4998                   type = right_type;
4999                 else if (right_type == NULL)
5000                   type = left_type;
5001                 else if (!left_type->is_abstract()
5002                          && left_type->named_type() != NULL)
5003                   type = left_type;
5004                 else if (!right_type->is_abstract()
5005                          && right_type->named_type() != NULL)
5006                   type = right_type;
5007                 else if (!left_type->is_abstract())
5008                   type = left_type;
5009                 else if (!right_type->is_abstract())
5010                   type = right_type;
5011                 else if (left_type->complex_type() != NULL)
5012                   type = left_type;
5013                 else if (right_type->complex_type() != NULL)
5014                   type = right_type;
5015                 else
5016                   type = left_type;
5017                 ret = Expression::make_complex(&real, &imag, type,
5018                                                location);
5019               }
5020             mpfr_clear(real);
5021             mpfr_clear(imag);
5022           }
5023
5024         if (ret != NULL)
5025           {
5026             mpfr_clear(left_real);
5027             mpfr_clear(left_imag);
5028             mpfr_clear(right_real);
5029             mpfr_clear(right_imag);
5030             return ret;
5031           }
5032       }
5033
5034     mpfr_clear(left_real);
5035     mpfr_clear(left_imag);
5036     mpfr_clear(right_real);
5037     mpfr_clear(right_imag);
5038   }
5039
5040   // String constant expressions.
5041   if (op == OPERATOR_PLUS
5042       && left->type()->is_string_type()
5043       && right->type()->is_string_type())
5044     {
5045       std::string left_string;
5046       std::string right_string;
5047       if (left->string_constant_value(&left_string)
5048           && right->string_constant_value(&right_string))
5049         return Expression::make_string(left_string + right_string, location);
5050     }
5051
5052   return this;
5053 }
5054
5055 // Return the integer constant value, if it has one.
5056
5057 bool
5058 Binary_expression::do_integer_constant_value(bool iota_is_constant, mpz_t val,
5059                                              Type** ptype) const
5060 {
5061   mpz_t left_val;
5062   mpz_init(left_val);
5063   Type* left_type;
5064   if (!this->left_->integer_constant_value(iota_is_constant, left_val,
5065                                            &left_type))
5066     {
5067       mpz_clear(left_val);
5068       return false;
5069     }
5070
5071   mpz_t right_val;
5072   mpz_init(right_val);
5073   Type* right_type;
5074   if (!this->right_->integer_constant_value(iota_is_constant, right_val,
5075                                             &right_type))
5076     {
5077       mpz_clear(right_val);
5078       mpz_clear(left_val);
5079       return false;
5080     }
5081
5082   bool ret;
5083   if (left_type != right_type
5084       && left_type != NULL
5085       && right_type != NULL
5086       && left_type->base() != right_type->base()
5087       && this->op_ != OPERATOR_RSHIFT
5088       && this->op_ != OPERATOR_LSHIFT)
5089     ret = false;
5090   else
5091     ret = Binary_expression::eval_integer(this->op_, left_type, left_val,
5092                                           right_type, right_val,
5093                                           this->location(), val);
5094
5095   mpz_clear(right_val);
5096   mpz_clear(left_val);
5097
5098   if (ret)
5099     *ptype = left_type;
5100
5101   return ret;
5102 }
5103
5104 // Return the floating point constant value, if it has one.
5105
5106 bool
5107 Binary_expression::do_float_constant_value(mpfr_t val, Type** ptype) const
5108 {
5109   mpfr_t left_val;
5110   mpfr_init(left_val);
5111   Type* left_type;
5112   if (!this->left_->float_constant_value(left_val, &left_type))
5113     {
5114       mpfr_clear(left_val);
5115       return false;
5116     }
5117
5118   mpfr_t right_val;
5119   mpfr_init(right_val);
5120   Type* right_type;
5121   if (!this->right_->float_constant_value(right_val, &right_type))
5122     {
5123       mpfr_clear(right_val);
5124       mpfr_clear(left_val);
5125       return false;
5126     }
5127
5128   bool ret;
5129   if (left_type != right_type
5130       && left_type != NULL
5131       && right_type != NULL
5132       && left_type->base() != right_type->base())
5133     ret = false;
5134   else
5135     ret = Binary_expression::eval_float(this->op_, left_type, left_val,
5136                                         right_type, right_val,
5137                                         val, this->location());
5138
5139   mpfr_clear(left_val);
5140   mpfr_clear(right_val);
5141
5142   if (ret)
5143     *ptype = left_type;
5144
5145   return ret;
5146 }
5147
5148 // Return the complex constant value, if it has one.
5149
5150 bool
5151 Binary_expression::do_complex_constant_value(mpfr_t real, mpfr_t imag,
5152                                              Type** ptype) const
5153 {
5154   mpfr_t left_real;
5155   mpfr_t left_imag;
5156   mpfr_init(left_real);
5157   mpfr_init(left_imag);
5158   Type* left_type;
5159   if (!this->left_->complex_constant_value(left_real, left_imag, &left_type))
5160     {
5161       mpfr_clear(left_real);
5162       mpfr_clear(left_imag);
5163       return false;
5164     }
5165
5166   mpfr_t right_real;
5167   mpfr_t right_imag;
5168   mpfr_init(right_real);
5169   mpfr_init(right_imag);
5170   Type* right_type;
5171   if (!this->right_->complex_constant_value(right_real, right_imag,
5172                                             &right_type))
5173     {
5174       mpfr_clear(left_real);
5175       mpfr_clear(left_imag);
5176       mpfr_clear(right_real);
5177       mpfr_clear(right_imag);
5178       return false;
5179     }
5180
5181   bool ret;
5182   if (left_type != right_type
5183       && left_type != NULL
5184       && right_type != NULL
5185       && left_type->base() != right_type->base())
5186     ret = false;
5187   else
5188     ret = Binary_expression::eval_complex(this->op_, left_type,
5189                                           left_real, left_imag,
5190                                           right_type,
5191                                           right_real, right_imag,
5192                                           real, imag,
5193                                           this->location());
5194   mpfr_clear(left_real);
5195   mpfr_clear(left_imag);
5196   mpfr_clear(right_real);
5197   mpfr_clear(right_imag);
5198
5199   if (ret)
5200     *ptype = left_type;
5201
5202   return ret;
5203 }
5204
5205 // Note that the value is being discarded.
5206
5207 void
5208 Binary_expression::do_discarding_value()
5209 {
5210   if (this->op_ == OPERATOR_OROR || this->op_ == OPERATOR_ANDAND)
5211     this->right_->discarding_value();
5212   else
5213     this->warn_about_unused_value();
5214 }
5215
5216 // Get type.
5217
5218 Type*
5219 Binary_expression::do_type()
5220 {
5221   switch (this->op_)
5222     {
5223     case OPERATOR_OROR:
5224     case OPERATOR_ANDAND:
5225     case OPERATOR_EQEQ:
5226     case OPERATOR_NOTEQ:
5227     case OPERATOR_LT:
5228     case OPERATOR_LE:
5229     case OPERATOR_GT:
5230     case OPERATOR_GE:
5231       return Type::lookup_bool_type();
5232
5233     case OPERATOR_PLUS:
5234     case OPERATOR_MINUS:
5235     case OPERATOR_OR:
5236     case OPERATOR_XOR:
5237     case OPERATOR_MULT:
5238     case OPERATOR_DIV:
5239     case OPERATOR_MOD:
5240     case OPERATOR_AND:
5241     case OPERATOR_BITCLEAR:
5242       {
5243         Type* left_type = this->left_->type();
5244         Type* right_type = this->right_->type();
5245         if (!left_type->is_abstract() && left_type->named_type() != NULL)
5246           return left_type;
5247         else if (!right_type->is_abstract() && right_type->named_type() != NULL)
5248           return right_type;
5249         else if (!left_type->is_abstract())
5250           return left_type;
5251         else if (!right_type->is_abstract())
5252           return right_type;
5253         else if (left_type->complex_type() != NULL)
5254           return left_type;
5255         else if (right_type->complex_type() != NULL)
5256           return right_type;
5257         else if (left_type->float_type() != NULL)
5258           return left_type;
5259         else if (right_type->float_type() != NULL)
5260           return right_type;
5261         else
5262           return left_type;
5263       }
5264
5265     case OPERATOR_LSHIFT:
5266     case OPERATOR_RSHIFT:
5267       return this->left_->type();
5268
5269     default:
5270       gcc_unreachable();
5271     }
5272 }
5273
5274 // Set type for a binary expression.
5275
5276 void
5277 Binary_expression::do_determine_type(const Type_context* context)
5278 {
5279   Type* tleft = this->left_->type();
5280   Type* tright = this->right_->type();
5281
5282   // Both sides should have the same type, except for the shift
5283   // operations.  For a comparison, we should ignore the incoming
5284   // type.
5285
5286   bool is_shift_op = (this->op_ == OPERATOR_LSHIFT
5287                       || this->op_ == OPERATOR_RSHIFT);
5288
5289   bool is_comparison = (this->op_ == OPERATOR_EQEQ
5290                         || this->op_ == OPERATOR_NOTEQ
5291                         || this->op_ == OPERATOR_LT
5292                         || this->op_ == OPERATOR_LE
5293                         || this->op_ == OPERATOR_GT
5294                         || this->op_ == OPERATOR_GE);
5295
5296   Type_context subcontext(*context);
5297
5298   if (is_comparison)
5299     {
5300       // In a comparison, the context does not determine the types of
5301       // the operands.
5302       subcontext.type = NULL;
5303     }
5304
5305   // Set the context for the left hand operand.
5306   if (is_shift_op)
5307     {
5308       // The right hand operand plays no role in determining the type
5309       // of the left hand operand.  A shift of an abstract integer in
5310       // a string context gets special treatment, which may be a
5311       // language bug.
5312       if (subcontext.type != NULL
5313           && subcontext.type->is_string_type()
5314           && tleft->is_abstract())
5315         error_at(this->location(), "shift of non-integer operand");
5316     }
5317   else if (!tleft->is_abstract())
5318     subcontext.type = tleft;
5319   else if (!tright->is_abstract())
5320     subcontext.type = tright;
5321   else if (subcontext.type == NULL)
5322     {
5323       if ((tleft->integer_type() != NULL && tright->integer_type() != NULL)
5324           || (tleft->float_type() != NULL && tright->float_type() != NULL)
5325           || (tleft->complex_type() != NULL && tright->complex_type() != NULL))
5326         {
5327           // Both sides have an abstract integer, abstract float, or
5328           // abstract complex type.  Just let CONTEXT determine
5329           // whether they may remain abstract or not.
5330         }
5331       else if (tleft->complex_type() != NULL)
5332         subcontext.type = tleft;
5333       else if (tright->complex_type() != NULL)
5334         subcontext.type = tright;
5335       else if (tleft->float_type() != NULL)
5336         subcontext.type = tleft;
5337       else if (tright->float_type() != NULL)
5338         subcontext.type = tright;
5339       else
5340         subcontext.type = tleft;
5341     }
5342
5343   this->left_->determine_type(&subcontext);
5344
5345   // The context for the right hand operand is the same as for the
5346   // left hand operand, except for a shift operator.
5347   if (is_shift_op)
5348     {
5349       subcontext.type = Type::lookup_integer_type("uint");
5350       subcontext.may_be_abstract = false;
5351     }
5352
5353   this->right_->determine_type(&subcontext);
5354 }
5355
5356 // Report an error if the binary operator OP does not support TYPE.
5357 // Return whether the operation is OK.  This should not be used for
5358 // shift.
5359
5360 bool
5361 Binary_expression::check_operator_type(Operator op, Type* type,
5362                                        source_location location)
5363 {
5364   switch (op)
5365     {
5366     case OPERATOR_OROR:
5367     case OPERATOR_ANDAND:
5368       if (!type->is_boolean_type())
5369         {
5370           error_at(location, "expected boolean type");
5371           return false;
5372         }
5373       break;
5374
5375     case OPERATOR_EQEQ:
5376     case OPERATOR_NOTEQ:
5377       if (type->integer_type() == NULL
5378           && type->float_type() == NULL
5379           && type->complex_type() == NULL
5380           && !type->is_string_type()
5381           && type->points_to() == NULL
5382           && !type->is_nil_type()
5383           && !type->is_boolean_type()
5384           && type->interface_type() == NULL
5385           && (type->array_type() == NULL
5386               || type->array_type()->length() != NULL)
5387           && type->map_type() == NULL
5388           && type->channel_type() == NULL
5389           && type->function_type() == NULL)
5390         {
5391           error_at(location,
5392                    ("expected integer, floating, complex, string, pointer, "
5393                     "boolean, interface, slice, map, channel, "
5394                     "or function type"));
5395           return false;
5396         }
5397       break;
5398
5399     case OPERATOR_LT:
5400     case OPERATOR_LE:
5401     case OPERATOR_GT:
5402     case OPERATOR_GE:
5403       if (type->integer_type() == NULL
5404           && type->float_type() == NULL
5405           && !type->is_string_type())
5406         {
5407           error_at(location, "expected integer, floating, or string type");
5408           return false;
5409         }
5410       break;
5411
5412     case OPERATOR_PLUS:
5413     case OPERATOR_PLUSEQ:
5414       if (type->integer_type() == NULL
5415           && type->float_type() == NULL
5416           && type->complex_type() == NULL
5417           && !type->is_string_type())
5418         {
5419           error_at(location,
5420                    "expected integer, floating, complex, or string type");
5421           return false;
5422         }
5423       break;
5424
5425     case OPERATOR_MINUS:
5426     case OPERATOR_MINUSEQ:
5427     case OPERATOR_MULT:
5428     case OPERATOR_MULTEQ:
5429     case OPERATOR_DIV:
5430     case OPERATOR_DIVEQ:
5431       if (type->integer_type() == NULL
5432           && type->float_type() == NULL
5433           && type->complex_type() == NULL)
5434         {
5435           error_at(location, "expected integer, floating, or complex type");
5436           return false;
5437         }
5438       break;
5439
5440     case OPERATOR_MOD:
5441     case OPERATOR_MODEQ:
5442     case OPERATOR_OR:
5443     case OPERATOR_OREQ:
5444     case OPERATOR_AND:
5445     case OPERATOR_ANDEQ:
5446     case OPERATOR_XOR:
5447     case OPERATOR_XOREQ:
5448     case OPERATOR_BITCLEAR:
5449     case OPERATOR_BITCLEAREQ:
5450       if (type->integer_type() == NULL)
5451         {
5452           error_at(location, "expected integer type");
5453           return false;
5454         }
5455       break;
5456
5457     default:
5458       gcc_unreachable();
5459     }
5460
5461   return true;
5462 }
5463
5464 // Check types.
5465
5466 void
5467 Binary_expression::do_check_types(Gogo*)
5468 {
5469   Type* left_type = this->left_->type();
5470   Type* right_type = this->right_->type();
5471   if (left_type->is_error_type() || right_type->is_error_type())
5472     return;
5473
5474   if (this->op_ == OPERATOR_EQEQ
5475       || this->op_ == OPERATOR_NOTEQ
5476       || this->op_ == OPERATOR_LT
5477       || this->op_ == OPERATOR_LE
5478       || this->op_ == OPERATOR_GT
5479       || this->op_ == OPERATOR_GE)
5480     {
5481       if (!Type::are_assignable(left_type, right_type, NULL)
5482           && !Type::are_assignable(right_type, left_type, NULL))
5483         {
5484           this->report_error(_("incompatible types in binary expression"));
5485           return;
5486         }
5487       if (!Binary_expression::check_operator_type(this->op_, left_type,
5488                                                   this->location())
5489           || !Binary_expression::check_operator_type(this->op_, right_type,
5490                                                      this->location()))
5491         {
5492           this->set_is_error();
5493           return;
5494         }
5495     }
5496   else if (this->op_ != OPERATOR_LSHIFT && this->op_ != OPERATOR_RSHIFT)
5497     {
5498       if (!Type::are_compatible_for_binop(left_type, right_type))
5499         {
5500           this->report_error(_("incompatible types in binary expression"));
5501           return;
5502         }
5503       if (!Binary_expression::check_operator_type(this->op_, left_type,
5504                                                   this->location()))
5505         {
5506           this->set_is_error();
5507           return;
5508         }
5509     }
5510   else
5511     {
5512       if (left_type->integer_type() == NULL)
5513         this->report_error(_("shift of non-integer operand"));
5514
5515       if (!right_type->is_abstract()
5516           && (right_type->integer_type() == NULL
5517               || !right_type->integer_type()->is_unsigned()))
5518         this->report_error(_("shift count not unsigned integer"));
5519       else
5520         {
5521           mpz_t val;
5522           mpz_init(val);
5523           Type* type;
5524           if (this->right_->integer_constant_value(true, val, &type))
5525             {
5526               if (mpz_sgn(val) < 0)
5527                 this->report_error(_("negative shift count"));
5528             }
5529           mpz_clear(val);
5530         }
5531     }
5532 }
5533
5534 // Get a tree for a binary expression.
5535
5536 tree
5537 Binary_expression::do_get_tree(Translate_context* context)
5538 {
5539   tree left = this->left_->get_tree(context);
5540   tree right = this->right_->get_tree(context);
5541
5542   if (left == error_mark_node || right == error_mark_node)
5543     return error_mark_node;
5544
5545   enum tree_code code;
5546   bool use_left_type = true;
5547   bool is_shift_op = false;
5548   switch (this->op_)
5549     {
5550     case OPERATOR_EQEQ:
5551     case OPERATOR_NOTEQ:
5552     case OPERATOR_LT:
5553     case OPERATOR_LE:
5554     case OPERATOR_GT:
5555     case OPERATOR_GE:
5556       return Expression::comparison_tree(context, this->op_,
5557                                          this->left_->type(), left,
5558                                          this->right_->type(), right,
5559                                          this->location());
5560
5561     case OPERATOR_OROR:
5562       code = TRUTH_ORIF_EXPR;
5563       use_left_type = false;
5564       break;
5565     case OPERATOR_ANDAND:
5566       code = TRUTH_ANDIF_EXPR;
5567       use_left_type = false;
5568       break;
5569     case OPERATOR_PLUS:
5570       code = PLUS_EXPR;
5571       break;
5572     case OPERATOR_MINUS:
5573       code = MINUS_EXPR;
5574       break;
5575     case OPERATOR_OR:
5576       code = BIT_IOR_EXPR;
5577       break;
5578     case OPERATOR_XOR:
5579       code = BIT_XOR_EXPR;
5580       break;
5581     case OPERATOR_MULT:
5582       code = MULT_EXPR;
5583       break;
5584     case OPERATOR_DIV:
5585       {
5586         Type *t = this->left_->type();
5587         if (t->float_type() != NULL || t->complex_type() != NULL)
5588           code = RDIV_EXPR;
5589         else
5590           code = TRUNC_DIV_EXPR;
5591       }
5592       break;
5593     case OPERATOR_MOD:
5594       code = TRUNC_MOD_EXPR;
5595       break;
5596     case OPERATOR_LSHIFT:
5597       code = LSHIFT_EXPR;
5598       is_shift_op = true;
5599       break;
5600     case OPERATOR_RSHIFT:
5601       code = RSHIFT_EXPR;
5602       is_shift_op = true;
5603       break;
5604     case OPERATOR_AND:
5605       code = BIT_AND_EXPR;
5606       break;
5607     case OPERATOR_BITCLEAR:
5608       right = fold_build1(BIT_NOT_EXPR, TREE_TYPE(right), right);
5609       code = BIT_AND_EXPR;
5610       break;
5611     default:
5612       gcc_unreachable();
5613     }
5614
5615   tree type = use_left_type ? TREE_TYPE(left) : TREE_TYPE(right);
5616
5617   if (this->left_->type()->is_string_type())
5618     {
5619       gcc_assert(this->op_ == OPERATOR_PLUS);
5620       tree string_type = Type::make_string_type()->get_tree(context->gogo());
5621       static tree string_plus_decl;
5622       return Gogo::call_builtin(&string_plus_decl,
5623                                 this->location(),
5624                                 "__go_string_plus",
5625                                 2,
5626                                 string_type,
5627                                 string_type,
5628                                 left,
5629                                 string_type,
5630                                 right);
5631     }
5632
5633   tree compute_type = excess_precision_type(type);
5634   if (compute_type != NULL_TREE)
5635     {
5636       left = ::convert(compute_type, left);
5637       right = ::convert(compute_type, right);
5638     }
5639
5640   tree eval_saved = NULL_TREE;
5641   if (is_shift_op)
5642     {
5643       if (!DECL_P(left))
5644         left = save_expr(left);
5645       if (!DECL_P(right))
5646         right = save_expr(right);
5647       // Make sure the values are evaluated.
5648       eval_saved = fold_build2_loc(this->location(), COMPOUND_EXPR,
5649                                    void_type_node, left, right);
5650     }
5651
5652   tree ret = fold_build2_loc(this->location(),
5653                              code,
5654                              compute_type != NULL_TREE ? compute_type : type,
5655                              left, right);
5656
5657   if (compute_type != NULL_TREE)
5658     ret = ::convert(type, ret);
5659
5660   // In Go, a shift larger than the size of the type is well-defined.
5661   // This is not true in GENERIC, so we need to insert a conditional.
5662   if (is_shift_op)
5663     {
5664       gcc_assert(INTEGRAL_TYPE_P(TREE_TYPE(left)));
5665       gcc_assert(this->left_->type()->integer_type() != NULL);
5666       int bits = TYPE_PRECISION(TREE_TYPE(left));
5667
5668       tree compare = fold_build2(LT_EXPR, boolean_type_node, right,
5669                                  build_int_cst_type(TREE_TYPE(right), bits));
5670
5671       tree overflow_result = fold_convert_loc(this->location(),
5672                                               TREE_TYPE(left),
5673                                               integer_zero_node);
5674       if (this->op_ == OPERATOR_RSHIFT
5675           && !this->left_->type()->integer_type()->is_unsigned())
5676         {
5677           tree neg = fold_build2_loc(this->location(), LT_EXPR,
5678                                      boolean_type_node, left,
5679                                      fold_convert_loc(this->location(),
5680                                                       TREE_TYPE(left),
5681                                                       integer_zero_node));
5682           tree neg_one = fold_build2_loc(this->location(),
5683                                          MINUS_EXPR, TREE_TYPE(left),
5684                                          fold_convert_loc(this->location(),
5685                                                           TREE_TYPE(left),
5686                                                           integer_zero_node),
5687                                          fold_convert_loc(this->location(),
5688                                                           TREE_TYPE(left),
5689                                                           integer_one_node));
5690           overflow_result = fold_build3_loc(this->location(), COND_EXPR,
5691                                             TREE_TYPE(left), neg, neg_one,
5692                                             overflow_result);
5693         }
5694
5695       ret = fold_build3_loc(this->location(), COND_EXPR, TREE_TYPE(left),
5696                             compare, ret, overflow_result);
5697
5698       ret = fold_build2_loc(this->location(), COMPOUND_EXPR,
5699                             TREE_TYPE(ret), eval_saved, ret);
5700     }
5701
5702   return ret;
5703 }
5704
5705 // Export a binary expression.
5706
5707 void
5708 Binary_expression::do_export(Export* exp) const
5709 {
5710   exp->write_c_string("(");
5711   this->left_->export_expression(exp);
5712   switch (this->op_)
5713     {
5714     case OPERATOR_OROR:
5715       exp->write_c_string(" || ");
5716       break;
5717     case OPERATOR_ANDAND:
5718       exp->write_c_string(" && ");
5719       break;
5720     case OPERATOR_EQEQ:
5721       exp->write_c_string(" == ");
5722       break;
5723     case OPERATOR_NOTEQ:
5724       exp->write_c_string(" != ");
5725       break;
5726     case OPERATOR_LT:
5727       exp->write_c_string(" < ");
5728       break;
5729     case OPERATOR_LE:
5730       exp->write_c_string(" <= ");
5731       break;
5732     case OPERATOR_GT:
5733       exp->write_c_string(" > ");
5734       break;
5735     case OPERATOR_GE:
5736       exp->write_c_string(" >= ");
5737       break;
5738     case OPERATOR_PLUS:
5739       exp->write_c_string(" + ");
5740       break;
5741     case OPERATOR_MINUS:
5742       exp->write_c_string(" - ");
5743       break;
5744     case OPERATOR_OR:
5745       exp->write_c_string(" | ");
5746       break;
5747     case OPERATOR_XOR:
5748       exp->write_c_string(" ^ ");
5749       break;
5750     case OPERATOR_MULT:
5751       exp->write_c_string(" * ");
5752       break;
5753     case OPERATOR_DIV:
5754       exp->write_c_string(" / ");
5755       break;
5756     case OPERATOR_MOD:
5757       exp->write_c_string(" % ");
5758       break;
5759     case OPERATOR_LSHIFT:
5760       exp->write_c_string(" << ");
5761       break;
5762     case OPERATOR_RSHIFT:
5763       exp->write_c_string(" >> ");
5764       break;
5765     case OPERATOR_AND:
5766       exp->write_c_string(" & ");
5767       break;
5768     case OPERATOR_BITCLEAR:
5769       exp->write_c_string(" &^ ");
5770       break;
5771     default:
5772       gcc_unreachable();
5773     }
5774   this->right_->export_expression(exp);
5775   exp->write_c_string(")");
5776 }
5777
5778 // Import a binary expression.
5779
5780 Expression*
5781 Binary_expression::do_import(Import* imp)
5782 {
5783   imp->require_c_string("(");
5784
5785   Expression* left = Expression::import_expression(imp);
5786
5787   Operator op;
5788   if (imp->match_c_string(" || "))
5789     {
5790       op = OPERATOR_OROR;
5791       imp->advance(4);
5792     }
5793   else if (imp->match_c_string(" && "))
5794     {
5795       op = OPERATOR_ANDAND;
5796       imp->advance(4);
5797     }
5798   else if (imp->match_c_string(" == "))
5799     {
5800       op = OPERATOR_EQEQ;
5801       imp->advance(4);
5802     }
5803   else if (imp->match_c_string(" != "))
5804     {
5805       op = OPERATOR_NOTEQ;
5806       imp->advance(4);
5807     }
5808   else if (imp->match_c_string(" < "))
5809     {
5810       op = OPERATOR_LT;
5811       imp->advance(3);
5812     }
5813   else if (imp->match_c_string(" <= "))
5814     {
5815       op = OPERATOR_LE;
5816       imp->advance(4);
5817     }
5818   else if (imp->match_c_string(" > "))
5819     {
5820       op = OPERATOR_GT;
5821       imp->advance(3);
5822     }
5823   else if (imp->match_c_string(" >= "))
5824     {
5825       op = OPERATOR_GE;
5826       imp->advance(4);
5827     }
5828   else if (imp->match_c_string(" + "))
5829     {
5830       op = OPERATOR_PLUS;
5831       imp->advance(3);
5832     }
5833   else if (imp->match_c_string(" - "))
5834     {
5835       op = OPERATOR_MINUS;
5836       imp->advance(3);
5837     }
5838   else if (imp->match_c_string(" | "))
5839     {
5840       op = OPERATOR_OR;
5841       imp->advance(3);
5842     }
5843   else if (imp->match_c_string(" ^ "))
5844     {
5845       op = OPERATOR_XOR;
5846       imp->advance(3);
5847     }
5848   else if (imp->match_c_string(" * "))
5849     {
5850       op = OPERATOR_MULT;
5851       imp->advance(3);
5852     }
5853   else if (imp->match_c_string(" / "))
5854     {
5855       op = OPERATOR_DIV;
5856       imp->advance(3);
5857     }
5858   else if (imp->match_c_string(" % "))
5859     {
5860       op = OPERATOR_MOD;
5861       imp->advance(3);
5862     }
5863   else if (imp->match_c_string(" << "))
5864     {
5865       op = OPERATOR_LSHIFT;
5866       imp->advance(4);
5867     }
5868   else if (imp->match_c_string(" >> "))
5869     {
5870       op = OPERATOR_RSHIFT;
5871       imp->advance(4);
5872     }
5873   else if (imp->match_c_string(" & "))
5874     {
5875       op = OPERATOR_AND;
5876       imp->advance(3);
5877     }
5878   else if (imp->match_c_string(" &^ "))
5879     {
5880       op = OPERATOR_BITCLEAR;
5881       imp->advance(4);
5882     }
5883   else
5884     {
5885       error_at(imp->location(), "unrecognized binary operator");
5886       return Expression::make_error(imp->location());
5887     }
5888
5889   Expression* right = Expression::import_expression(imp);
5890
5891   imp->require_c_string(")");
5892
5893   return Expression::make_binary(op, left, right, imp->location());
5894 }
5895
5896 // Make a binary expression.
5897
5898 Expression*
5899 Expression::make_binary(Operator op, Expression* left, Expression* right,
5900                         source_location location)
5901 {
5902   return new Binary_expression(op, left, right, location);
5903 }
5904
5905 // Implement a comparison.
5906
5907 tree
5908 Expression::comparison_tree(Translate_context* context, Operator op,
5909                             Type* left_type, tree left_tree,
5910                             Type* right_type, tree right_tree,
5911                             source_location location)
5912 {
5913   enum tree_code code;
5914   switch (op)
5915     {
5916     case OPERATOR_EQEQ:
5917       code = EQ_EXPR;
5918       break;
5919     case OPERATOR_NOTEQ:
5920       code = NE_EXPR;
5921       break;
5922     case OPERATOR_LT:
5923       code = LT_EXPR;
5924       break;
5925     case OPERATOR_LE:
5926       code = LE_EXPR;
5927       break;
5928     case OPERATOR_GT:
5929       code = GT_EXPR;
5930       break;
5931     case OPERATOR_GE:
5932       code = GE_EXPR;
5933       break;
5934     default:
5935       gcc_unreachable();
5936     }
5937
5938   if (left_type->is_string_type())
5939     {
5940       gcc_assert(right_type->is_string_type());
5941       tree string_type = Type::make_string_type()->get_tree(context->gogo());
5942       static tree string_compare_decl;
5943       left_tree = Gogo::call_builtin(&string_compare_decl,
5944                                      location,
5945                                      "__go_strcmp",
5946                                      2,
5947                                      integer_type_node,
5948                                      string_type,
5949                                      left_tree,
5950                                      string_type,
5951                                      right_tree);
5952       right_tree = build_int_cst_type(integer_type_node, 0);
5953     }
5954
5955   if ((left_type->interface_type() != NULL
5956        && right_type->interface_type() == NULL
5957        && !right_type->is_nil_type())
5958       || (left_type->interface_type() == NULL
5959           && !left_type->is_nil_type()
5960           && right_type->interface_type() != NULL))
5961     {
5962       // Comparing an interface value to a non-interface value.
5963       if (left_type->interface_type() == NULL)
5964         {
5965           std::swap(left_type, right_type);
5966           std::swap(left_tree, right_tree);
5967         }
5968
5969       // The right operand is not an interface.  We need to take its
5970       // address if it is not a pointer.
5971       tree make_tmp;
5972       tree arg;
5973       if (right_type->points_to() != NULL)
5974         {
5975           make_tmp = NULL_TREE;
5976           arg = right_tree;
5977         }
5978       else if (TREE_ADDRESSABLE(TREE_TYPE(right_tree)) || DECL_P(right_tree))
5979         {
5980           make_tmp = NULL_TREE;
5981           arg = build_fold_addr_expr_loc(location, right_tree);
5982           if (DECL_P(right_tree))
5983             TREE_ADDRESSABLE(right_tree) = 1;
5984         }
5985       else
5986         {
5987           tree tmp = create_tmp_var(TREE_TYPE(right_tree),
5988                                     get_name(right_tree));
5989           DECL_IGNORED_P(tmp) = 0;
5990           DECL_INITIAL(tmp) = right_tree;
5991           TREE_ADDRESSABLE(tmp) = 1;
5992           make_tmp = build1(DECL_EXPR, void_type_node, tmp);
5993           SET_EXPR_LOCATION(make_tmp, location);
5994           arg = build_fold_addr_expr_loc(location, tmp);
5995         }
5996       arg = fold_convert_loc(location, ptr_type_node, arg);
5997
5998       tree descriptor = right_type->type_descriptor_pointer(context->gogo());
5999
6000       if (left_type->interface_type()->is_empty())
6001         {
6002           static tree empty_interface_value_compare_decl;
6003           left_tree = Gogo::call_builtin(&empty_interface_value_compare_decl,
6004                                          location,
6005                                          "__go_empty_interface_value_compare",
6006                                          3,
6007                                          integer_type_node,
6008                                          TREE_TYPE(left_tree),
6009                                          left_tree,
6010                                          TREE_TYPE(descriptor),
6011                                          descriptor,
6012                                          ptr_type_node,
6013                                          arg);
6014           // This can panic if the type is not comparable.
6015           TREE_NOTHROW(empty_interface_value_compare_decl) = 0;
6016         }
6017       else
6018         {
6019           static tree interface_value_compare_decl;
6020           left_tree = Gogo::call_builtin(&interface_value_compare_decl,
6021                                          location,
6022                                          "__go_interface_value_compare",
6023                                          3,
6024                                          integer_type_node,
6025                                          TREE_TYPE(left_tree),
6026                                          left_tree,
6027                                          TREE_TYPE(descriptor),
6028                                          descriptor,
6029                                          ptr_type_node,
6030                                          arg);
6031           // This can panic if the type is not comparable.
6032           TREE_NOTHROW(interface_value_compare_decl) = 0;
6033         }
6034       right_tree = build_int_cst_type(integer_type_node, 0);
6035
6036       if (make_tmp != NULL_TREE)
6037         left_tree = build2(COMPOUND_EXPR, TREE_TYPE(left_tree), make_tmp,
6038                            left_tree);
6039     }
6040   else if (left_type->interface_type() != NULL
6041            && right_type->interface_type() != NULL)
6042     {
6043       if (left_type->interface_type()->is_empty())
6044         {
6045           gcc_assert(right_type->interface_type()->is_empty());
6046           static tree empty_interface_compare_decl;
6047           left_tree = Gogo::call_builtin(&empty_interface_compare_decl,
6048                                          location,
6049                                          "__go_empty_interface_compare",
6050                                          2,
6051                                          integer_type_node,
6052                                          TREE_TYPE(left_tree),
6053                                          left_tree,
6054                                          TREE_TYPE(right_tree),
6055                                          right_tree);
6056           // This can panic if the type is uncomparable.
6057           TREE_NOTHROW(empty_interface_compare_decl) = 0;
6058         }
6059       else
6060         {
6061           gcc_assert(!right_type->interface_type()->is_empty());
6062           static tree interface_compare_decl;
6063           left_tree = Gogo::call_builtin(&interface_compare_decl,
6064                                          location,
6065                                          "__go_interface_compare",
6066                                          2,
6067                                          integer_type_node,
6068                                          TREE_TYPE(left_tree),
6069                                          left_tree,
6070                                          TREE_TYPE(right_tree),
6071                                          right_tree);
6072           // This can panic if the type is uncomparable.
6073           TREE_NOTHROW(interface_compare_decl) = 0;
6074         }
6075       right_tree = build_int_cst_type(integer_type_node, 0);
6076     }
6077
6078   if (left_type->is_nil_type()
6079       && (op == OPERATOR_EQEQ || op == OPERATOR_NOTEQ))
6080     {
6081       std::swap(left_type, right_type);
6082       std::swap(left_tree, right_tree);
6083     }
6084
6085   if (right_type->is_nil_type())
6086     {
6087       if (left_type->array_type() != NULL
6088           && left_type->array_type()->length() == NULL)
6089         {
6090           Array_type* at = left_type->array_type();
6091           left_tree = at->value_pointer_tree(context->gogo(), left_tree);
6092           right_tree = fold_convert(TREE_TYPE(left_tree), null_pointer_node);
6093         }
6094       else if (left_type->interface_type() != NULL)
6095         {
6096           // An interface is nil if the first field is nil.
6097           tree left_type_tree = TREE_TYPE(left_tree);
6098           gcc_assert(TREE_CODE(left_type_tree) == RECORD_TYPE);
6099           tree field = TYPE_FIELDS(left_type_tree);
6100           left_tree = build3(COMPONENT_REF, TREE_TYPE(field), left_tree,
6101                              field, NULL_TREE);
6102           right_tree = fold_convert(TREE_TYPE(left_tree), null_pointer_node);
6103         }
6104       else
6105         {
6106           gcc_assert(POINTER_TYPE_P(TREE_TYPE(left_tree)));
6107           right_tree = fold_convert(TREE_TYPE(left_tree), null_pointer_node);
6108         }
6109     }
6110
6111   tree ret = fold_build2(code, boolean_type_node, left_tree, right_tree);
6112   if (CAN_HAVE_LOCATION_P(ret))
6113     SET_EXPR_LOCATION(ret, location);
6114   return ret;
6115 }
6116
6117 // Class Bound_method_expression.
6118
6119 // Traversal.
6120
6121 int
6122 Bound_method_expression::do_traverse(Traverse* traverse)
6123 {
6124   if (Expression::traverse(&this->expr_, traverse) == TRAVERSE_EXIT)
6125     return TRAVERSE_EXIT;
6126   return Expression::traverse(&this->method_, traverse);
6127 }
6128
6129 // Return the type of a bound method expression.  The type of this
6130 // object is really the type of the method with no receiver.  We
6131 // should be able to get away with just returning the type of the
6132 // method.
6133
6134 Type*
6135 Bound_method_expression::do_type()
6136 {
6137   return this->method_->type();
6138 }
6139
6140 // Determine the types of a method expression.
6141
6142 void
6143 Bound_method_expression::do_determine_type(const Type_context*)
6144 {
6145   this->method_->determine_type_no_context();
6146   Type* mtype = this->method_->type();
6147   Function_type* fntype = mtype == NULL ? NULL : mtype->function_type();
6148   if (fntype == NULL || !fntype->is_method())
6149     this->expr_->determine_type_no_context();
6150   else
6151     {
6152       Type_context subcontext(fntype->receiver()->type(), false);
6153       this->expr_->determine_type(&subcontext);
6154     }
6155 }
6156
6157 // Check the types of a method expression.
6158
6159 void
6160 Bound_method_expression::do_check_types(Gogo*)
6161 {
6162   Type* type = this->method_->type()->deref();
6163   if (type == NULL
6164       || type->function_type() == NULL
6165       || !type->function_type()->is_method())
6166     this->report_error(_("object is not a method"));
6167   else
6168     {
6169       Type* rtype = type->function_type()->receiver()->type()->deref();
6170       Type* etype = (this->expr_type_ != NULL
6171                      ? this->expr_type_
6172                      : this->expr_->type());
6173       etype = etype->deref();
6174       if (!Type::are_identical(rtype, etype, NULL))
6175         this->report_error(_("method type does not match object type"));
6176     }
6177 }
6178
6179 // Get the tree for a method expression.  There is no standard tree
6180 // representation for this.  The only places it may currently be used
6181 // are in a Call_expression or a Go_statement, which will take it
6182 // apart directly.  So this has nothing to do at present.
6183
6184 tree
6185 Bound_method_expression::do_get_tree(Translate_context*)
6186 {
6187   gcc_unreachable();
6188 }
6189
6190 // Make a method expression.
6191
6192 Bound_method_expression*
6193 Expression::make_bound_method(Expression* expr, Expression* method,
6194                               source_location location)
6195 {
6196   return new Bound_method_expression(expr, method, location);
6197 }
6198
6199 // Class Builtin_call_expression.  This is used for a call to a
6200 // builtin function.
6201
6202 class Builtin_call_expression : public Call_expression
6203 {
6204  public:
6205   Builtin_call_expression(Gogo* gogo, Expression* fn, Expression_list* args,
6206                           bool is_varargs, source_location location);
6207
6208  protected:
6209   // This overrides Call_expression::do_lower.
6210   Expression*
6211   do_lower(Gogo*, Named_object*, int);
6212
6213   bool
6214   do_is_constant() const;
6215
6216   bool
6217   do_integer_constant_value(bool, mpz_t, Type**) const;
6218
6219   bool
6220   do_float_constant_value(mpfr_t, Type**) const;
6221
6222   bool
6223   do_complex_constant_value(mpfr_t, mpfr_t, Type**) const;
6224
6225   Type*
6226   do_type();
6227
6228   void
6229   do_determine_type(const Type_context*);
6230
6231   void
6232   do_check_types(Gogo*);
6233
6234   Expression*
6235   do_copy()
6236   {
6237     return new Builtin_call_expression(this->gogo_, this->fn()->copy(),
6238                                        this->args()->copy(),
6239                                        this->is_varargs(),
6240                                        this->location());
6241   }
6242
6243   tree
6244   do_get_tree(Translate_context*);
6245
6246   void
6247   do_export(Export*) const;
6248
6249   virtual bool
6250   do_is_recover_call() const;
6251
6252   virtual void
6253   do_set_recover_arg(Expression*);
6254
6255  private:
6256   // The builtin functions.
6257   enum Builtin_function_code
6258     {
6259       BUILTIN_INVALID,
6260
6261       // Predeclared builtin functions.
6262       BUILTIN_APPEND,
6263       BUILTIN_CAP,
6264       BUILTIN_CLOSE,
6265       BUILTIN_CLOSED,
6266       BUILTIN_CMPLX,
6267       BUILTIN_COPY,
6268       BUILTIN_IMAG,
6269       BUILTIN_LEN,
6270       BUILTIN_MAKE,
6271       BUILTIN_NEW,
6272       BUILTIN_PANIC,
6273       BUILTIN_PRINT,
6274       BUILTIN_PRINTLN,
6275       BUILTIN_REAL,
6276       BUILTIN_RECOVER,
6277
6278       // Builtin functions from the unsafe package.
6279       BUILTIN_ALIGNOF,
6280       BUILTIN_OFFSETOF,
6281       BUILTIN_SIZEOF
6282     };
6283
6284   Expression*
6285   one_arg() const;
6286
6287   bool
6288   check_one_arg();
6289
6290   static Type*
6291   real_imag_type(Type*);
6292
6293   static Type*
6294   cmplx_type(Type*);
6295
6296   // A pointer back to the general IR structure.  This avoids a global
6297   // variable, or passing it around everywhere.
6298   Gogo* gogo_;
6299   // The builtin function being called.
6300   Builtin_function_code code_;
6301 };
6302
6303 Builtin_call_expression::Builtin_call_expression(Gogo* gogo,
6304                                                  Expression* fn,
6305                                                  Expression_list* args,
6306                                                  bool is_varargs,
6307                                                  source_location location)
6308   : Call_expression(fn, args, is_varargs, location),
6309     gogo_(gogo), code_(BUILTIN_INVALID)
6310 {
6311   Func_expression* fnexp = this->fn()->func_expression();
6312   gcc_assert(fnexp != NULL);
6313   const std::string& name(fnexp->named_object()->name());
6314   if (name == "append")
6315     this->code_ = BUILTIN_APPEND;
6316   else if (name == "cap")
6317     this->code_ = BUILTIN_CAP;
6318   else if (name == "close")
6319     this->code_ = BUILTIN_CLOSE;
6320   else if (name == "closed")
6321     this->code_ = BUILTIN_CLOSED;
6322   else if (name == "cmplx")
6323     this->code_ = BUILTIN_CMPLX;
6324   else if (name == "copy")
6325     this->code_ = BUILTIN_COPY;
6326   else if (name == "imag")
6327     this->code_ = BUILTIN_IMAG;
6328   else if (name == "len")
6329     this->code_ = BUILTIN_LEN;
6330   else if (name == "make")
6331     this->code_ = BUILTIN_MAKE;
6332   else if (name == "new")
6333     this->code_ = BUILTIN_NEW;
6334   else if (name == "panic")
6335     this->code_ = BUILTIN_PANIC;
6336   else if (name == "print")
6337     this->code_ = BUILTIN_PRINT;
6338   else if (name == "println")
6339     this->code_ = BUILTIN_PRINTLN;
6340   else if (name == "real")
6341     this->code_ = BUILTIN_REAL;
6342   else if (name == "recover")
6343     this->code_ = BUILTIN_RECOVER;
6344   else if (name == "Alignof")
6345     this->code_ = BUILTIN_ALIGNOF;
6346   else if (name == "Offsetof")
6347     this->code_ = BUILTIN_OFFSETOF;
6348   else if (name == "Sizeof")
6349     this->code_ = BUILTIN_SIZEOF;
6350   else
6351     gcc_unreachable();
6352 }
6353
6354 // Return whether this is a call to recover.  This is a virtual
6355 // function called from the parent class.
6356
6357 bool
6358 Builtin_call_expression::do_is_recover_call() const
6359 {
6360   if (this->classification() == EXPRESSION_ERROR)
6361     return false;
6362   return this->code_ == BUILTIN_RECOVER;
6363 }
6364
6365 // Set the argument for a call to recover.
6366
6367 void
6368 Builtin_call_expression::do_set_recover_arg(Expression* arg)
6369 {
6370   const Expression_list* args = this->args();
6371   gcc_assert(args == NULL || args->empty());
6372   Expression_list* new_args = new Expression_list();
6373   new_args->push_back(arg);
6374   this->set_args(new_args);
6375 }
6376
6377 // A traversal class which looks for a call expression.
6378
6379 class Find_call_expression : public Traverse
6380 {
6381  public:
6382   Find_call_expression()
6383     : Traverse(traverse_expressions),
6384       found_(false)
6385   { }
6386
6387   int
6388   expression(Expression**);
6389
6390   bool
6391   found()
6392   { return this->found_; }
6393
6394  private:
6395   bool found_;
6396 };
6397
6398 int
6399 Find_call_expression::expression(Expression** pexpr)
6400 {
6401   if ((*pexpr)->call_expression() != NULL)
6402     {
6403       this->found_ = true;
6404       return TRAVERSE_EXIT;
6405     }
6406   return TRAVERSE_CONTINUE;
6407 }
6408
6409 // Lower a builtin call expression.  This turns new and make into
6410 // specific expressions.  We also convert to a constant if we can.
6411
6412 Expression*
6413 Builtin_call_expression::do_lower(Gogo* gogo, Named_object* function, int)
6414 {
6415   if (this->code_ == BUILTIN_NEW)
6416     {
6417       const Expression_list* args = this->args();
6418       if (args == NULL || args->size() < 1)
6419         this->report_error(_("not enough arguments"));
6420       else if (args->size() > 1)
6421         this->report_error(_("too many arguments"));
6422       else
6423         {
6424           Expression* arg = args->front();
6425           if (!arg->is_type_expression())
6426             {
6427               error_at(arg->location(), "expected type");
6428               this->set_is_error();
6429             }
6430           else
6431             return Expression::make_allocation(arg->type(), this->location());
6432         }
6433     }
6434   else if (this->code_ == BUILTIN_MAKE)
6435     {
6436       const Expression_list* args = this->args();
6437       if (args == NULL || args->size() < 1)
6438         this->report_error(_("not enough arguments"));
6439       else
6440         {
6441           Expression* arg = args->front();
6442           if (!arg->is_type_expression())
6443             {
6444               error_at(arg->location(), "expected type");
6445               this->set_is_error();
6446             }
6447           else
6448             {
6449               Expression_list* newargs;
6450               if (args->size() == 1)
6451                 newargs = NULL;
6452               else
6453                 {
6454                   newargs = new Expression_list();
6455                   Expression_list::const_iterator p = args->begin();
6456                   ++p;
6457                   for (; p != args->end(); ++p)
6458                     newargs->push_back(*p);
6459                 }
6460               return Expression::make_make(arg->type(), newargs,
6461                                            this->location());
6462             }
6463         }
6464     }
6465   else if (this->is_constant())
6466     {
6467       // We can only lower len and cap if there are no function calls
6468       // in the arguments.  Otherwise we have to make the call.
6469       if (this->code_ == BUILTIN_LEN || this->code_ == BUILTIN_CAP)
6470         {
6471           Expression* arg = this->one_arg();
6472           if (!arg->is_constant())
6473             {
6474               Find_call_expression find_call;
6475               Expression::traverse(&arg, &find_call);
6476               if (find_call.found())
6477                 return this;
6478             }
6479         }
6480
6481       mpz_t ival;
6482       mpz_init(ival);
6483       Type* type;
6484       if (this->integer_constant_value(true, ival, &type))
6485         {
6486           Expression* ret = Expression::make_integer(&ival, type,
6487                                                      this->location());
6488           mpz_clear(ival);
6489           return ret;
6490         }
6491       mpz_clear(ival);
6492
6493       mpfr_t rval;
6494       mpfr_init(rval);
6495       if (this->float_constant_value(rval, &type))
6496         {
6497           Expression* ret = Expression::make_float(&rval, type,
6498                                                    this->location());
6499           mpfr_clear(rval);
6500           return ret;
6501         }
6502
6503       mpfr_t imag;
6504       mpfr_init(imag);
6505       if (this->complex_constant_value(rval, imag, &type))
6506         {
6507           Expression* ret = Expression::make_complex(&rval, &imag, type,
6508                                                      this->location());
6509           mpfr_clear(rval);
6510           mpfr_clear(imag);
6511           return ret;
6512         }
6513       mpfr_clear(rval);
6514       mpfr_clear(imag);
6515     }
6516   else if (this->code_ == BUILTIN_RECOVER)
6517     {
6518       if (function != NULL)
6519         function->func_value()->set_calls_recover();
6520       else
6521         {
6522           // Calling recover outside of a function always returns the
6523           // nil empty interface.
6524           Type* eface = Type::make_interface_type(NULL, this->location());
6525           return Expression::make_cast(eface,
6526                                        Expression::make_nil(this->location()),
6527                                        this->location());
6528         }
6529     }
6530   else if (this->code_ == BUILTIN_APPEND)
6531     {
6532       // Lower the varargs.
6533       const Expression_list* args = this->args();
6534       if (args == NULL || args->empty())
6535         return this;
6536       Type* slice_type = args->front()->type();
6537       if (!slice_type->is_open_array_type())
6538         {
6539           error_at(args->front()->location(), "argument 1 must be a slice");
6540           this->set_is_error();
6541           return this;
6542         }
6543       return this->lower_varargs(gogo, function, slice_type, 2);
6544     }
6545
6546   return this;
6547 }
6548
6549 // Return the type of the real or imag functions, given the type of
6550 // the argument.  We need to map complex to float, complex64 to
6551 // float32, and complex128 to float64, so it has to be done by name.
6552 // This returns NULL if it can't figure out the type.
6553
6554 Type*
6555 Builtin_call_expression::real_imag_type(Type* arg_type)
6556 {
6557   if (arg_type == NULL || arg_type->is_abstract())
6558     return NULL;
6559   Named_type* nt = arg_type->named_type();
6560   if (nt == NULL)
6561     return NULL;
6562   while (nt->real_type()->named_type() != NULL)
6563     nt = nt->real_type()->named_type();
6564   if (nt->name() == "complex")
6565     return Type::lookup_float_type("float");
6566   else if (nt->name() == "complex64")
6567     return Type::lookup_float_type("float32");
6568   else if (nt->name() == "complex128")
6569     return Type::lookup_float_type("float64");
6570   else
6571     return NULL;
6572 }
6573
6574 // Return the type of the cmplx function, given the type of one of the
6575 // argments.  Like real_imag_type, we have to map by name.
6576
6577 Type*
6578 Builtin_call_expression::cmplx_type(Type* arg_type)
6579 {
6580   if (arg_type == NULL || arg_type->is_abstract())
6581     return NULL;
6582   Named_type* nt = arg_type->named_type();
6583   if (nt == NULL)
6584     return NULL;
6585   while (nt->real_type()->named_type() != NULL)
6586     nt = nt->real_type()->named_type();
6587   if (nt->name() == "float")
6588     return Type::lookup_complex_type("complex");
6589   else if (nt->name() == "float32")
6590     return Type::lookup_complex_type("complex64");
6591   else if (nt->name() == "float64")
6592     return Type::lookup_complex_type("complex128");
6593   else
6594     return NULL;
6595 }
6596
6597 // Return a single argument, or NULL if there isn't one.
6598
6599 Expression*
6600 Builtin_call_expression::one_arg() const
6601 {
6602   const Expression_list* args = this->args();
6603   if (args->size() != 1)
6604     return NULL;
6605   return args->front();
6606 }
6607
6608 // Return whether this is constant: len of a string, or len or cap of
6609 // a fixed array, or unsafe.Sizeof, unsafe.Offsetof, unsafe.Alignof.
6610
6611 bool
6612 Builtin_call_expression::do_is_constant() const
6613 {
6614   switch (this->code_)
6615     {
6616     case BUILTIN_LEN:
6617     case BUILTIN_CAP:
6618       {
6619         Expression* arg = this->one_arg();
6620         if (arg == NULL)
6621           return false;
6622         Type* arg_type = arg->type();
6623
6624         if (arg_type->points_to() != NULL
6625             && arg_type->points_to()->array_type() != NULL
6626             && !arg_type->points_to()->is_open_array_type())
6627           arg_type = arg_type->points_to();
6628
6629         if (arg_type->array_type() != NULL
6630             && arg_type->array_type()->length() != NULL)
6631           return arg_type->array_type()->length()->is_constant();
6632
6633         if (this->code_ == BUILTIN_LEN && arg_type->is_string_type())
6634           return arg->is_constant();
6635       }
6636       break;
6637
6638     case BUILTIN_SIZEOF:
6639     case BUILTIN_ALIGNOF:
6640       return this->one_arg() != NULL;
6641
6642     case BUILTIN_OFFSETOF:
6643       {
6644         Expression* arg = this->one_arg();
6645         if (arg == NULL)
6646           return false;
6647         return arg->field_reference_expression() != NULL;
6648       }
6649
6650     case BUILTIN_CMPLX:
6651       {
6652         const Expression_list* args = this->args();
6653         if (args != NULL && args->size() == 2)
6654           return args->front()->is_constant() && args->back()->is_constant();
6655       }
6656       break;
6657
6658     case BUILTIN_REAL:
6659     case BUILTIN_IMAG:
6660       {
6661         Expression* arg = this->one_arg();
6662         return arg != NULL && arg->is_constant();
6663       }
6664
6665     default:
6666       break;
6667     }
6668
6669   return false;
6670 }
6671
6672 // Return an integer constant value if possible.
6673
6674 bool
6675 Builtin_call_expression::do_integer_constant_value(bool iota_is_constant,
6676                                                    mpz_t val,
6677                                                    Type** ptype) const
6678 {
6679   if (this->code_ == BUILTIN_LEN
6680       || this->code_ == BUILTIN_CAP)
6681     {
6682       Expression* arg = this->one_arg();
6683       if (arg == NULL)
6684         return false;
6685       Type* arg_type = arg->type();
6686
6687       if (this->code_ == BUILTIN_LEN && arg_type->is_string_type())
6688         {
6689           std::string sval;
6690           if (arg->string_constant_value(&sval))
6691             {
6692               mpz_set_ui(val, sval.length());
6693               *ptype = Type::lookup_integer_type("int");
6694               return true;
6695             }
6696         }
6697
6698       if (arg_type->points_to() != NULL
6699           && arg_type->points_to()->array_type() != NULL
6700           && !arg_type->points_to()->is_open_array_type())
6701         arg_type = arg_type->points_to();
6702
6703       if (arg_type->array_type() != NULL
6704           && arg_type->array_type()->length() != NULL)
6705         {
6706           Expression* e = arg_type->array_type()->length();
6707           if (e->integer_constant_value(iota_is_constant, val, ptype))
6708             {
6709               *ptype = Type::lookup_integer_type("int");
6710               return true;
6711             }
6712         }
6713     }
6714   else if (this->code_ == BUILTIN_SIZEOF
6715            || this->code_ == BUILTIN_ALIGNOF)
6716     {
6717       Expression* arg = this->one_arg();
6718       if (arg == NULL)
6719         return false;
6720       Type* arg_type = arg->type();
6721       if (arg_type->is_error_type())
6722         return false;
6723       if (arg_type->is_abstract())
6724         return false;
6725       tree arg_type_tree = arg_type->get_tree(this->gogo_);
6726       unsigned long val_long;
6727       if (this->code_ == BUILTIN_SIZEOF)
6728         {
6729           tree type_size = TYPE_SIZE_UNIT(arg_type_tree);
6730           gcc_assert(TREE_CODE(type_size) == INTEGER_CST);
6731           if (TREE_INT_CST_HIGH(type_size) != 0)
6732             return false;
6733           unsigned HOST_WIDE_INT val_wide = TREE_INT_CST_LOW(type_size);
6734           val_long = static_cast<unsigned long>(val_wide);
6735           if (val_long != val_wide)
6736             return false;
6737         }
6738       else if (this->code_ == BUILTIN_ALIGNOF)
6739         {
6740           val_long = TYPE_ALIGN(arg_type_tree);
6741           if (arg->field_reference_expression() != NULL)
6742             {
6743               // Calling unsafe.Alignof(s.f) returns the alignment of
6744               // the type of f when it is used as a field in a struct.
6745 #ifdef BIGGEST_FIELD_ALIGNMENT
6746               if (val_long > BIGGEST_FIELD_ALIGNMENT)
6747                 val_long = BIGGEST_FIELD_ALIGNMENT;
6748 #endif
6749 #ifdef ADJUST_FIELD_ALIGN
6750               // A separate declaration avoids a warning promoted to
6751               // an error if ADJUST_FIELD_ALIGN ignores FIELD.
6752               tree field;
6753               field = build_decl(UNKNOWN_LOCATION, FIELD_DECL, NULL,
6754                                       arg_type_tree);
6755               val_long = ADJUST_FIELD_ALIGN(field, val_long);
6756 #endif
6757             }
6758           val_long /= BITS_PER_UNIT;
6759         }
6760       else
6761         gcc_unreachable();
6762       mpz_set_ui(val, val_long);
6763       *ptype = NULL;
6764       return true;
6765     }
6766   else if (this->code_ == BUILTIN_OFFSETOF)
6767     {
6768       Expression* arg = this->one_arg();
6769       if (arg == NULL)
6770         return false;
6771       Field_reference_expression* farg = arg->field_reference_expression();
6772       if (farg == NULL)
6773         return false;
6774       Expression* struct_expr = farg->expr();
6775       Type* st = struct_expr->type();
6776       if (st->struct_type() == NULL)
6777         return false;
6778       tree struct_tree = st->get_tree(this->gogo_);
6779       gcc_assert(TREE_CODE(struct_tree) == RECORD_TYPE);
6780       tree field = TYPE_FIELDS(struct_tree);
6781       for (unsigned int index = farg->field_index(); index > 0; --index)
6782         {
6783           field = DECL_CHAIN(field);
6784           gcc_assert(field != NULL_TREE);
6785         }
6786       HOST_WIDE_INT offset_wide = int_byte_position (field);
6787       if (offset_wide < 0)
6788         return false;
6789       unsigned long offset_long = static_cast<unsigned long>(offset_wide);
6790       if (offset_long != static_cast<unsigned HOST_WIDE_INT>(offset_wide))
6791         return false;
6792       mpz_set_ui(val, offset_long);
6793       return true;
6794     }
6795   return false;
6796 }
6797
6798 // Return a floating point constant value if possible.
6799
6800 bool
6801 Builtin_call_expression::do_float_constant_value(mpfr_t val,
6802                                                  Type** ptype) const
6803 {
6804   if (this->code_ == BUILTIN_REAL || this->code_ == BUILTIN_IMAG)
6805     {
6806       Expression* arg = this->one_arg();
6807       if (arg == NULL)
6808         return false;
6809
6810       mpfr_t real;
6811       mpfr_t imag;
6812       mpfr_init(real);
6813       mpfr_init(imag);
6814
6815       bool ret = false;
6816       Type* type;
6817       if (arg->complex_constant_value(real, imag, &type))
6818         {
6819           if (this->code_ == BUILTIN_REAL)
6820             mpfr_set(val, real, GMP_RNDN);
6821           else
6822             mpfr_set(val, imag, GMP_RNDN);
6823           *ptype = Builtin_call_expression::real_imag_type(type);
6824           ret = true;
6825         }
6826
6827       mpfr_clear(real);
6828       mpfr_clear(imag);
6829       return ret;
6830     }
6831
6832   return false;
6833 }
6834
6835 // Return a complex constant value if possible.
6836
6837 bool
6838 Builtin_call_expression::do_complex_constant_value(mpfr_t real, mpfr_t imag,
6839                                                    Type** ptype) const
6840 {
6841   if (this->code_ == BUILTIN_CMPLX)
6842     {
6843       const Expression_list* args = this->args();
6844       if (args == NULL || args->size() != 2)
6845         return false;
6846
6847       mpfr_t r;
6848       mpfr_init(r);
6849       Type* rtype;
6850       if (!args->front()->float_constant_value(r, &rtype))
6851         {
6852           mpfr_clear(r);
6853           return false;
6854         }
6855
6856       mpfr_t i;
6857       mpfr_init(i);
6858
6859       bool ret = false;
6860       Type* itype;
6861       if (args->back()->float_constant_value(i, &itype)
6862           && Type::are_identical(rtype, itype, NULL))
6863         {
6864           mpfr_set(real, r, GMP_RNDN);
6865           mpfr_set(imag, i, GMP_RNDN);
6866           *ptype = Builtin_call_expression::cmplx_type(rtype);
6867           ret = true;
6868         }
6869
6870       mpfr_clear(r);
6871       mpfr_clear(i);
6872
6873       return ret;
6874     }
6875
6876   return false;
6877 }
6878
6879 // Return the type.
6880
6881 Type*
6882 Builtin_call_expression::do_type()
6883 {
6884   switch (this->code_)
6885     {
6886     case BUILTIN_INVALID:
6887     default:
6888       gcc_unreachable();
6889
6890     case BUILTIN_NEW:
6891     case BUILTIN_MAKE:
6892       {
6893         const Expression_list* args = this->args();
6894         if (args == NULL || args->empty())
6895           return Type::make_error_type();
6896         return Type::make_pointer_type(args->front()->type());
6897       }
6898
6899     case BUILTIN_CAP:
6900     case BUILTIN_COPY:
6901     case BUILTIN_LEN:
6902     case BUILTIN_ALIGNOF:
6903     case BUILTIN_OFFSETOF:
6904     case BUILTIN_SIZEOF:
6905       return Type::lookup_integer_type("int");
6906
6907     case BUILTIN_CLOSE:
6908     case BUILTIN_PANIC:
6909     case BUILTIN_PRINT:
6910     case BUILTIN_PRINTLN:
6911       return Type::make_void_type();
6912
6913     case BUILTIN_CLOSED:
6914       return Type::lookup_bool_type();
6915
6916     case BUILTIN_RECOVER:
6917       return Type::make_interface_type(NULL, BUILTINS_LOCATION);
6918
6919     case BUILTIN_APPEND:
6920       {
6921         const Expression_list* args = this->args();
6922         if (args == NULL || args->empty())
6923           return Type::make_error_type();
6924         return args->front()->type();
6925       }
6926
6927     case BUILTIN_REAL:
6928     case BUILTIN_IMAG:
6929       {
6930         Expression* arg = this->one_arg();
6931         if (arg == NULL)
6932           return Type::make_error_type();
6933         Type* t = arg->type();
6934         if (t->is_abstract())
6935           t = t->make_non_abstract_type();
6936         t = Builtin_call_expression::real_imag_type(t);
6937         if (t == NULL)
6938           t = Type::make_error_type();
6939         return t;
6940       }
6941
6942     case BUILTIN_CMPLX:
6943       {
6944         const Expression_list* args = this->args();
6945         if (args == NULL || args->size() != 2)
6946           return Type::make_error_type();
6947         Type* t = args->front()->type();
6948         if (t->is_abstract())
6949           {
6950             t = args->back()->type();
6951             if (t->is_abstract())
6952               t = t->make_non_abstract_type();
6953           }
6954         t = Builtin_call_expression::cmplx_type(t);
6955         if (t == NULL)
6956           t = Type::make_error_type();
6957         return t;
6958       }
6959     }
6960 }
6961
6962 // Determine the type.
6963
6964 void
6965 Builtin_call_expression::do_determine_type(const Type_context* context)
6966 {
6967   this->fn()->determine_type_no_context();
6968
6969   const Expression_list* args = this->args();
6970
6971   bool is_print;
6972   Type* arg_type = NULL;
6973   switch (this->code_)
6974     {
6975     case BUILTIN_PRINT:
6976     case BUILTIN_PRINTLN:
6977       // Do not force a large integer constant to "int".
6978       is_print = true;
6979       break;
6980
6981     case BUILTIN_REAL:
6982     case BUILTIN_IMAG:
6983       arg_type = Builtin_call_expression::cmplx_type(context->type);
6984       is_print = false;
6985       break;
6986
6987     case BUILTIN_CMPLX:
6988       {
6989         // For the cmplx function the type of one operand can
6990         // determine the type of the other, as in a binary expression.
6991         arg_type = Builtin_call_expression::real_imag_type(context->type);
6992         if (args != NULL && args->size() == 2)
6993           {
6994             Type* t1 = args->front()->type();
6995             Type* t2 = args->front()->type();
6996             if (!t1->is_abstract())
6997               arg_type = t1;
6998             else if (!t2->is_abstract())
6999               arg_type = t2;
7000           }
7001         is_print = false;
7002       }
7003       break;
7004
7005     default:
7006       is_print = false;
7007       break;
7008     }
7009
7010   if (args != NULL)
7011     {
7012       for (Expression_list::const_iterator pa = args->begin();
7013            pa != args->end();
7014            ++pa)
7015         {
7016           Type_context subcontext;
7017           subcontext.type = arg_type;
7018
7019           if (is_print)
7020             {
7021               // We want to print large constants, we so can't just
7022               // use the appropriate nonabstract type.  Use uint64 for
7023               // an integer if we know it is nonnegative, otherwise
7024               // use int64 for a integer, otherwise use float64 for a
7025               // float or complex128 for a complex.
7026               Type* want_type = NULL;
7027               Type* atype = (*pa)->type();
7028               if (atype->is_abstract())
7029                 {
7030                   if (atype->integer_type() != NULL)
7031                     {
7032                       mpz_t val;
7033                       mpz_init(val);
7034                       Type* dummy;
7035                       if (this->integer_constant_value(true, val, &dummy)
7036                           && mpz_sgn(val) >= 0)
7037                         want_type = Type::lookup_integer_type("uint64");
7038                       else
7039                         want_type = Type::lookup_integer_type("int64");
7040                       mpz_clear(val);
7041                     }
7042                   else if (atype->float_type() != NULL)
7043                     want_type = Type::lookup_float_type("float64");
7044                   else if (atype->complex_type() != NULL)
7045                     want_type = Type::lookup_complex_type("complex128");
7046                   else if (atype->is_abstract_string_type())
7047                     want_type = Type::lookup_string_type();
7048                   else if (atype->is_abstract_boolean_type())
7049                     want_type = Type::lookup_bool_type();
7050                   else
7051                     gcc_unreachable();
7052                   subcontext.type = want_type;
7053                 }
7054             }
7055
7056           (*pa)->determine_type(&subcontext);
7057         }
7058     }
7059 }
7060
7061 // If there is exactly one argument, return true.  Otherwise give an
7062 // error message and return false.
7063
7064 bool
7065 Builtin_call_expression::check_one_arg()
7066 {
7067   const Expression_list* args = this->args();
7068   if (args == NULL || args->size() < 1)
7069     {
7070       this->report_error(_("not enough arguments"));
7071       return false;
7072     }
7073   else if (args->size() > 1)
7074     {
7075       this->report_error(_("too many arguments"));
7076       return false;
7077     }
7078   if (args->front()->is_error_expression()
7079       || args->front()->type()->is_error_type())
7080     {
7081       this->set_is_error();
7082       return false;
7083     }
7084   return true;
7085 }
7086
7087 // Check argument types for a builtin function.
7088
7089 void
7090 Builtin_call_expression::do_check_types(Gogo*)
7091 {
7092   switch (this->code_)
7093     {
7094     case BUILTIN_INVALID:
7095     case BUILTIN_NEW:
7096     case BUILTIN_MAKE:
7097       return;
7098
7099     case BUILTIN_LEN:
7100     case BUILTIN_CAP:
7101       {
7102         // The single argument may be either a string or an array or a
7103         // map or a channel, or a pointer to a closed array.
7104         if (this->check_one_arg())
7105           {
7106             Type* arg_type = this->one_arg()->type();
7107             if (arg_type->points_to() != NULL
7108                 && arg_type->points_to()->array_type() != NULL
7109                 && !arg_type->points_to()->is_open_array_type())
7110               arg_type = arg_type->points_to();
7111             if (this->code_ == BUILTIN_CAP)
7112               {
7113                 if (!arg_type->is_error_type()
7114                     && arg_type->array_type() == NULL
7115                     && arg_type->channel_type() == NULL)
7116                   this->report_error(_("argument must be array or slice "
7117                                        "or channel"));
7118               }
7119             else
7120               {
7121                 if (!arg_type->is_error_type()
7122                     && !arg_type->is_string_type()
7123                     && arg_type->array_type() == NULL
7124                     && arg_type->map_type() == NULL
7125                     && arg_type->channel_type() == NULL)
7126                   this->report_error(_("argument must be string or "
7127                                        "array or slice or map or channel"));
7128               }
7129           }
7130       }
7131       break;
7132
7133     case BUILTIN_PRINT:
7134     case BUILTIN_PRINTLN:
7135       {
7136         const Expression_list* args = this->args();
7137         if (args == NULL)
7138           {
7139             if (this->code_ == BUILTIN_PRINT)
7140               warning_at(this->location(), 0,
7141                          "no arguments for builtin function %<%s%>",
7142                          (this->code_ == BUILTIN_PRINT
7143                           ? "print"
7144                           : "println"));
7145           }
7146         else
7147           {
7148             for (Expression_list::const_iterator p = args->begin();
7149                  p != args->end();
7150                  ++p)
7151               {
7152                 Type* type = (*p)->type();
7153                 if (type->is_error_type()
7154                     || type->is_string_type()
7155                     || type->integer_type() != NULL
7156                     || type->float_type() != NULL
7157                     || type->complex_type() != NULL
7158                     || type->is_boolean_type()
7159                     || type->points_to() != NULL
7160                     || type->interface_type() != NULL
7161                     || type->channel_type() != NULL
7162                     || type->map_type() != NULL
7163                     || type->function_type() != NULL
7164                     || type->is_open_array_type())
7165                   ;
7166                 else
7167                   this->report_error(_("unsupported argument type to "
7168                                        "builtin function"));
7169               }
7170           }
7171       }
7172       break;
7173
7174     case BUILTIN_CLOSE:
7175     case BUILTIN_CLOSED:
7176       if (this->check_one_arg())
7177         {
7178           if (this->one_arg()->type()->channel_type() == NULL)
7179             this->report_error(_("argument must be channel"));
7180         }
7181       break;
7182
7183     case BUILTIN_PANIC:
7184     case BUILTIN_SIZEOF:
7185     case BUILTIN_ALIGNOF:
7186       this->check_one_arg();
7187       break;
7188
7189     case BUILTIN_RECOVER:
7190       if (this->args() != NULL && !this->args()->empty())
7191         this->report_error(_("too many arguments"));
7192       break;
7193
7194     case BUILTIN_OFFSETOF:
7195       if (this->check_one_arg())
7196         {
7197           Expression* arg = this->one_arg();
7198           if (arg->field_reference_expression() == NULL)
7199             this->report_error(_("argument must be a field reference"));
7200         }
7201       break;
7202
7203     case BUILTIN_COPY:
7204       {
7205         const Expression_list* args = this->args();
7206         if (args == NULL || args->size() < 2)
7207           {
7208             this->report_error(_("not enough arguments"));
7209             break;
7210           }
7211         else if (args->size() > 2)
7212           {
7213             this->report_error(_("too many arguments"));
7214             break;
7215           }
7216         Type* arg1_type = args->front()->type();
7217         Type* arg2_type = args->back()->type();
7218         if (arg1_type->is_error_type() || arg2_type->is_error_type())
7219           break;
7220
7221         Type* e1;
7222         if (arg1_type->is_open_array_type())
7223           e1 = arg1_type->array_type()->element_type();
7224         else
7225           {
7226             this->report_error(_("left argument must be a slice"));
7227             break;
7228           }
7229
7230         Type* e2;
7231         if (arg2_type->is_open_array_type())
7232           e2 = arg2_type->array_type()->element_type();
7233         else if (arg2_type->is_string_type())
7234           e2 = Type::lookup_integer_type("uint8");
7235         else
7236           {
7237             this->report_error(_("right argument must be a slice or a string"));
7238             break;
7239           }
7240
7241         if (!Type::are_identical(e1, e2, NULL))
7242           this->report_error(_("element types must be the same"));
7243       }
7244       break;
7245
7246     case BUILTIN_APPEND:
7247       {
7248         const Expression_list* args = this->args();
7249         if (args == NULL || args->empty())
7250           {
7251             this->report_error(_("not enough arguments"));
7252             break;
7253           }
7254         /* Lowering varargs should have left us with 2 arguments.  */
7255         gcc_assert(args->size() == 2);
7256         std::string reason;
7257         if (!Type::are_assignable(args->front()->type(), args->back()->type(),
7258                                   &reason))
7259           {
7260             if (reason.empty())
7261               this->report_error(_("arguments 1 and 2 have different types"));
7262             else
7263               {
7264                 error_at(this->location(),
7265                          "arguments 1 and 2 have different types (%s)",
7266                          reason.c_str());
7267                 this->set_is_error();
7268               }
7269           }
7270         break;
7271       }
7272
7273     case BUILTIN_REAL:
7274     case BUILTIN_IMAG:
7275       if (this->check_one_arg())
7276         {
7277           if (this->one_arg()->type()->complex_type() == NULL)
7278             this->report_error(_("argument must have complex type"));
7279         }
7280       break;
7281
7282     case BUILTIN_CMPLX:
7283       {
7284         const Expression_list* args = this->args();
7285         if (args == NULL || args->size() < 2)
7286           this->report_error(_("not enough arguments"));
7287         else if (args->size() > 2)
7288           this->report_error(_("too many arguments"));
7289         else if (args->front()->is_error_expression()
7290                  || args->front()->type()->is_error_type()
7291                  || args->back()->is_error_expression()
7292                  || args->back()->type()->is_error_type())
7293           this->set_is_error();
7294         else if (!Type::are_identical(args->front()->type(),
7295                                       args->back()->type(), NULL))
7296           this->report_error(_("cmplx arguments must have identical types"));
7297         else if (args->front()->type()->float_type() == NULL)
7298           this->report_error(_("cmplx arguments must have "
7299                                "floating-point type"));
7300       }
7301       break;
7302
7303     default:
7304       gcc_unreachable();
7305     }
7306 }
7307
7308 // Return the tree for a builtin function.
7309
7310 tree
7311 Builtin_call_expression::do_get_tree(Translate_context* context)
7312 {
7313   Gogo* gogo = context->gogo();
7314   source_location location = this->location();
7315   switch (this->code_)
7316     {
7317     case BUILTIN_INVALID:
7318     case BUILTIN_NEW:
7319     case BUILTIN_MAKE:
7320       gcc_unreachable();
7321
7322     case BUILTIN_LEN:
7323     case BUILTIN_CAP:
7324       {
7325         const Expression_list* args = this->args();
7326         gcc_assert(args != NULL && args->size() == 1);
7327         Expression* arg = *args->begin();
7328         Type* arg_type = arg->type();
7329         tree arg_tree = arg->get_tree(context);
7330         if (arg_tree == error_mark_node)
7331           return error_mark_node;
7332
7333         if (arg_type->points_to() != NULL)
7334           {
7335             arg_type = arg_type->points_to();
7336             gcc_assert(arg_type->array_type() != NULL
7337                        && !arg_type->is_open_array_type());
7338             gcc_assert(POINTER_TYPE_P(TREE_TYPE(arg_tree)));
7339             arg_tree = build_fold_indirect_ref(arg_tree);
7340           }
7341
7342         tree val_tree;
7343         if (this->code_ == BUILTIN_LEN)
7344           {
7345             if (arg_type->is_string_type())
7346               val_tree = String_type::length_tree(gogo, arg_tree);
7347             else if (arg_type->array_type() != NULL)
7348               val_tree = arg_type->array_type()->length_tree(gogo, arg_tree);
7349             else if (arg_type->map_type() != NULL)
7350               {
7351                 static tree map_len_fndecl;
7352                 val_tree = Gogo::call_builtin(&map_len_fndecl,
7353                                               location,
7354                                               "__go_map_len",
7355                                               1,
7356                                               sizetype,
7357                                               arg_type->get_tree(gogo),
7358                                               arg_tree);
7359               }
7360             else if (arg_type->channel_type() != NULL)
7361               {
7362                 static tree chan_len_fndecl;
7363                 val_tree = Gogo::call_builtin(&chan_len_fndecl,
7364                                               location,
7365                                               "__go_chan_len",
7366                                               1,
7367                                               sizetype,
7368                                               arg_type->get_tree(gogo),
7369                                               arg_tree);
7370               }
7371             else
7372               gcc_unreachable();
7373           }
7374         else
7375           {
7376             if (arg_type->array_type() != NULL)
7377               val_tree = arg_type->array_type()->capacity_tree(gogo, arg_tree);
7378             else if (arg_type->channel_type() != NULL)
7379               {
7380                 static tree chan_cap_fndecl;
7381                 val_tree = Gogo::call_builtin(&chan_cap_fndecl,
7382                                               location,
7383                                               "__go_chan_cap",
7384                                               1,
7385                                               sizetype,
7386                                               arg_type->get_tree(gogo),
7387                                               arg_tree);
7388               }
7389             else
7390               gcc_unreachable();
7391           }
7392
7393         tree type_tree = Type::lookup_integer_type("int")->get_tree(gogo);
7394         if (type_tree == TREE_TYPE(val_tree))
7395           return val_tree;
7396         else
7397           return fold(convert_to_integer(type_tree, val_tree));
7398       }
7399
7400     case BUILTIN_PRINT:
7401     case BUILTIN_PRINTLN:
7402       {
7403         const bool is_ln = this->code_ == BUILTIN_PRINTLN;
7404         tree stmt_list = NULL_TREE;
7405
7406         const Expression_list* call_args = this->args();
7407         if (call_args != NULL)
7408           {
7409             for (Expression_list::const_iterator p = call_args->begin();
7410                  p != call_args->end();
7411                  ++p)
7412               {
7413                 if (is_ln && p != call_args->begin())
7414                   {
7415                     static tree print_space_fndecl;
7416                     tree call = Gogo::call_builtin(&print_space_fndecl,
7417                                                    location,
7418                                                    "__go_print_space",
7419                                                    0,
7420                                                    void_type_node);
7421                     append_to_statement_list(call, &stmt_list);
7422                   }
7423
7424                 Type* type = (*p)->type();
7425
7426                 tree arg = (*p)->get_tree(context);
7427                 if (arg == error_mark_node)
7428                   return error_mark_node;
7429
7430                 tree* pfndecl;
7431                 const char* fnname;
7432                 if (type->is_string_type())
7433                   {
7434                     static tree print_string_fndecl;
7435                     pfndecl = &print_string_fndecl;
7436                     fnname = "__go_print_string";
7437                   }
7438                 else if (type->integer_type() != NULL
7439                          && type->integer_type()->is_unsigned())
7440                   {
7441                     static tree print_uint64_fndecl;
7442                     pfndecl = &print_uint64_fndecl;
7443                     fnname = "__go_print_uint64";
7444                     Type* itype = Type::lookup_integer_type("uint64");
7445                     arg = fold_convert_loc(location, itype->get_tree(gogo),
7446                                            arg);
7447                   }
7448                 else if (type->integer_type() != NULL)
7449                   {
7450                     static tree print_int64_fndecl;
7451                     pfndecl = &print_int64_fndecl;
7452                     fnname = "__go_print_int64";
7453                     Type* itype = Type::lookup_integer_type("int64");
7454                     arg = fold_convert_loc(location, itype->get_tree(gogo),
7455                                            arg);
7456                   }
7457                 else if (type->float_type() != NULL)
7458                   {
7459                     static tree print_double_fndecl;
7460                     pfndecl = &print_double_fndecl;
7461                     fnname = "__go_print_double";
7462                     arg = fold_convert_loc(location, double_type_node, arg);
7463                   }
7464                 else if (type->complex_type() != NULL)
7465                   {
7466                     static tree print_complex_fndecl;
7467                     pfndecl = &print_complex_fndecl;
7468                     fnname = "__go_print_complex";
7469                     arg = fold_convert_loc(location, complex_double_type_node,
7470                                            arg);
7471                   }
7472                 else if (type->is_boolean_type())
7473                   {
7474                     static tree print_bool_fndecl;
7475                     pfndecl = &print_bool_fndecl;
7476                     fnname = "__go_print_bool";
7477                   }
7478                 else if (type->points_to() != NULL
7479                          || type->channel_type() != NULL
7480                          || type->map_type() != NULL
7481                          || type->function_type() != NULL)
7482                   {
7483                     static tree print_pointer_fndecl;
7484                     pfndecl = &print_pointer_fndecl;
7485                     fnname = "__go_print_pointer";
7486                     arg = fold_convert_loc(location, ptr_type_node, arg);
7487                   }
7488                 else if (type->interface_type() != NULL)
7489                   {
7490                     if (type->interface_type()->is_empty())
7491                       {
7492                         static tree print_empty_interface_fndecl;
7493                         pfndecl = &print_empty_interface_fndecl;
7494                         fnname = "__go_print_empty_interface";
7495                       }
7496                     else
7497                       {
7498                         static tree print_interface_fndecl;
7499                         pfndecl = &print_interface_fndecl;
7500                         fnname = "__go_print_interface";
7501                       }
7502                   }
7503                 else if (type->is_open_array_type())
7504                   {
7505                     static tree print_slice_fndecl;
7506                     pfndecl = &print_slice_fndecl;
7507                     fnname = "__go_print_slice";
7508                   }
7509                 else
7510                   gcc_unreachable();
7511
7512                 tree call = Gogo::call_builtin(pfndecl,
7513                                                location,
7514                                                fnname,
7515                                                1,
7516                                                void_type_node,
7517                                                TREE_TYPE(arg),
7518                                                arg);
7519                 append_to_statement_list(call, &stmt_list);
7520               }
7521           }
7522
7523         if (is_ln)
7524           {
7525             static tree print_nl_fndecl;
7526             tree call = Gogo::call_builtin(&print_nl_fndecl,
7527                                            location,
7528                                            "__go_print_nl",
7529                                            0,
7530                                            void_type_node);
7531             append_to_statement_list(call, &stmt_list);
7532           }
7533
7534         return stmt_list;
7535       }
7536
7537     case BUILTIN_PANIC:
7538       {
7539         const Expression_list* args = this->args();
7540         gcc_assert(args != NULL && args->size() == 1);
7541         Expression* arg = args->front();
7542         tree arg_tree = arg->get_tree(context);
7543         if (arg_tree == error_mark_node)
7544           return error_mark_node;
7545         Type *empty = Type::make_interface_type(NULL, BUILTINS_LOCATION);
7546         arg_tree = Expression::convert_for_assignment(context, empty,
7547                                                       arg->type(),
7548                                                       arg_tree, location);
7549         static tree panic_fndecl;
7550         tree call = Gogo::call_builtin(&panic_fndecl,
7551                                        location,
7552                                        "__go_panic",
7553                                        1,
7554                                        void_type_node,
7555                                        TREE_TYPE(arg_tree),
7556                                        arg_tree);
7557         // This function will throw an exception.
7558         TREE_NOTHROW(panic_fndecl) = 0;
7559         // This function will not return.
7560         TREE_THIS_VOLATILE(panic_fndecl) = 1;
7561         return call;
7562       }
7563
7564     case BUILTIN_RECOVER:
7565       {
7566         // The argument is set when building recover thunks.  It's a
7567         // boolean value which is true if we can recover a value now.
7568         const Expression_list* args = this->args();
7569         gcc_assert(args != NULL && args->size() == 1);
7570         Expression* arg = args->front();
7571         tree arg_tree = arg->get_tree(context);
7572         if (arg_tree == error_mark_node)
7573           return error_mark_node;
7574
7575         Type *empty = Type::make_interface_type(NULL, BUILTINS_LOCATION);
7576         tree empty_tree = empty->get_tree(context->gogo());
7577
7578         Type* nil_type = Type::make_nil_type();
7579         Expression* nil = Expression::make_nil(location);
7580         tree nil_tree = nil->get_tree(context);
7581         tree empty_nil_tree = Expression::convert_for_assignment(context,
7582                                                                  empty,
7583                                                                  nil_type,
7584                                                                  nil_tree,
7585                                                                  location);
7586
7587         // We need to handle a deferred call to recover specially,
7588         // because it changes whether it can recover a panic or not.
7589         // See test7 in test/recover1.go.
7590         tree call;
7591         if (this->is_deferred())
7592           {
7593             static tree deferred_recover_fndecl;
7594             call = Gogo::call_builtin(&deferred_recover_fndecl,
7595                                       location,
7596                                       "__go_deferred_recover",
7597                                       0,
7598                                       empty_tree);
7599           }
7600         else
7601           {
7602             static tree recover_fndecl;
7603             call = Gogo::call_builtin(&recover_fndecl,
7604                                       location,
7605                                       "__go_recover",
7606                                       0,
7607                                       empty_tree);
7608           }
7609         return fold_build3_loc(location, COND_EXPR, empty_tree, arg_tree,
7610                                call, empty_nil_tree);
7611       }
7612
7613     case BUILTIN_CLOSE:
7614     case BUILTIN_CLOSED:
7615       {
7616         const Expression_list* args = this->args();
7617         gcc_assert(args != NULL && args->size() == 1);
7618         Expression* arg = args->front();
7619         tree arg_tree = arg->get_tree(context);
7620         if (arg_tree == error_mark_node)
7621           return error_mark_node;
7622         if (this->code_ == BUILTIN_CLOSE)
7623           {
7624             static tree close_fndecl;
7625             return Gogo::call_builtin(&close_fndecl,
7626                                       location,
7627                                       "__go_builtin_close",
7628                                       1,
7629                                       void_type_node,
7630                                       TREE_TYPE(arg_tree),
7631                                       arg_tree);
7632           }
7633         else
7634           {
7635             static tree closed_fndecl;
7636             return Gogo::call_builtin(&closed_fndecl,
7637                                       location,
7638                                       "__go_builtin_closed",
7639                                       1,
7640                                       boolean_type_node,
7641                                       TREE_TYPE(arg_tree),
7642                                       arg_tree);
7643           }
7644       }
7645
7646     case BUILTIN_SIZEOF:
7647     case BUILTIN_OFFSETOF:
7648     case BUILTIN_ALIGNOF:
7649       {
7650         mpz_t val;
7651         mpz_init(val);
7652         Type* dummy;
7653         bool b = this->integer_constant_value(true, val, &dummy);
7654         gcc_assert(b);
7655         tree type = Type::lookup_integer_type("int")->get_tree(gogo);
7656         tree ret = Expression::integer_constant_tree(val, type);
7657         mpz_clear(val);
7658         return ret;
7659       }
7660
7661     case BUILTIN_COPY:
7662       {
7663         const Expression_list* args = this->args();
7664         gcc_assert(args != NULL && args->size() == 2);
7665         Expression* arg1 = args->front();
7666         Expression* arg2 = args->back();
7667
7668         tree arg1_tree = arg1->get_tree(context);
7669         tree arg2_tree = arg2->get_tree(context);
7670         if (arg1_tree == error_mark_node || arg2_tree == error_mark_node)
7671           return error_mark_node;
7672
7673         Type* arg1_type = arg1->type();
7674         Array_type* at = arg1_type->array_type();
7675         arg1_tree = save_expr(arg1_tree);
7676         tree arg1_val = at->value_pointer_tree(gogo, arg1_tree);
7677         tree arg1_len = at->length_tree(gogo, arg1_tree);
7678
7679         Type* arg2_type = arg2->type();
7680         tree arg2_val;
7681         tree arg2_len;
7682         if (arg2_type->is_open_array_type())
7683           {
7684             at = arg2_type->array_type();
7685             arg2_tree = save_expr(arg2_tree);
7686             arg2_val = at->value_pointer_tree(gogo, arg2_tree);
7687             arg2_len = at->length_tree(gogo, arg2_tree);
7688           }
7689         else
7690           {
7691             arg2_tree = save_expr(arg2_tree);
7692             arg2_val = String_type::bytes_tree(gogo, arg2_tree);
7693             arg2_len = String_type::length_tree(gogo, arg2_tree);
7694           }
7695
7696         arg1_len = save_expr(arg1_len);
7697         arg2_len = save_expr(arg2_len);
7698         tree len = fold_build3_loc(location, COND_EXPR, TREE_TYPE(arg1_len),
7699                                    fold_build2_loc(location, LT_EXPR,
7700                                                    boolean_type_node,
7701                                                    arg1_len, arg2_len),
7702                                    arg1_len, arg2_len);
7703         len = save_expr(len);
7704
7705         Type* element_type = at->element_type();
7706         tree element_type_tree = element_type->get_tree(gogo);
7707         tree element_size = TYPE_SIZE_UNIT(element_type_tree);
7708         tree bytecount = fold_convert_loc(location, TREE_TYPE(element_size),
7709                                           len);
7710         bytecount = fold_build2_loc(location, MULT_EXPR,
7711                                     TREE_TYPE(element_size),
7712                                     bytecount, element_size);
7713         bytecount = fold_convert_loc(location, size_type_node, bytecount);
7714
7715         tree call = build_call_expr_loc(location,
7716                                         built_in_decls[BUILT_IN_MEMMOVE],
7717                                         3, arg1_val, arg2_val, bytecount);
7718
7719         return fold_build2_loc(location, COMPOUND_EXPR, TREE_TYPE(len),
7720                                call, len);
7721       }
7722
7723     case BUILTIN_APPEND:
7724       {
7725         const Expression_list* args = this->args();
7726         gcc_assert(args != NULL && args->size() == 2);
7727         Expression* arg1 = args->front();
7728         Expression* arg2 = args->back();
7729
7730         tree arg1_tree = arg1->get_tree(context);
7731         tree arg2_tree = arg2->get_tree(context);
7732         if (arg1_tree == error_mark_node || arg2_tree == error_mark_node)
7733           return error_mark_node;
7734
7735         tree descriptor_tree = arg1->type()->type_descriptor_pointer(gogo);
7736
7737         // We rebuild the decl each time since the slice types may
7738         // change.
7739         tree append_fndecl = NULL_TREE;
7740         return Gogo::call_builtin(&append_fndecl,
7741                                   location,
7742                                   "__go_append",
7743                                   3,
7744                                   TREE_TYPE(arg1_tree),
7745                                   TREE_TYPE(descriptor_tree),
7746                                   descriptor_tree,
7747                                   TREE_TYPE(arg1_tree),
7748                                   arg1_tree,
7749                                   TREE_TYPE(arg2_tree),
7750                                   arg2_tree);
7751       }
7752
7753     case BUILTIN_REAL:
7754     case BUILTIN_IMAG:
7755       {
7756         const Expression_list* args = this->args();
7757         gcc_assert(args != NULL && args->size() == 1);
7758         Expression* arg = args->front();
7759         tree arg_tree = arg->get_tree(context);
7760         if (arg_tree == error_mark_node)
7761           return error_mark_node;
7762         gcc_assert(COMPLEX_FLOAT_TYPE_P(TREE_TYPE(arg_tree)));
7763         if (this->code_ == BUILTIN_REAL)
7764           return fold_build1_loc(location, REALPART_EXPR,
7765                                  TREE_TYPE(TREE_TYPE(arg_tree)),
7766                                  arg_tree);
7767         else
7768           return fold_build1_loc(location, IMAGPART_EXPR,
7769                                  TREE_TYPE(TREE_TYPE(arg_tree)),
7770                                  arg_tree);
7771       }
7772
7773     case BUILTIN_CMPLX:
7774       {
7775         const Expression_list* args = this->args();
7776         gcc_assert(args != NULL && args->size() == 2);
7777         tree r = args->front()->get_tree(context);
7778         tree i = args->back()->get_tree(context);
7779         if (r == error_mark_node || i == error_mark_node)
7780           return error_mark_node;
7781         gcc_assert(TYPE_MAIN_VARIANT(TREE_TYPE(r))
7782                    == TYPE_MAIN_VARIANT(TREE_TYPE(i)));
7783         gcc_assert(SCALAR_FLOAT_TYPE_P(TREE_TYPE(r)));
7784         return fold_build2_loc(location, COMPLEX_EXPR,
7785                                build_complex_type(TREE_TYPE(r)),
7786                                r, i);
7787       }
7788
7789     default:
7790       gcc_unreachable();
7791     }
7792 }
7793
7794 // We have to support exporting a builtin call expression, because
7795 // code can set a constant to the result of a builtin expression.
7796
7797 void
7798 Builtin_call_expression::do_export(Export* exp) const
7799 {
7800   bool ok = false;
7801
7802   mpz_t val;
7803   mpz_init(val);
7804   Type* dummy;
7805   if (this->integer_constant_value(true, val, &dummy))
7806     {
7807       Integer_expression::export_integer(exp, val);
7808       ok = true;
7809     }
7810   mpz_clear(val);
7811
7812   if (!ok)
7813     {
7814       mpfr_t fval;
7815       mpfr_init(fval);
7816       if (this->float_constant_value(fval, &dummy))
7817         {
7818           Float_expression::export_float(exp, fval);
7819           ok = true;
7820         }
7821       mpfr_clear(fval);
7822     }
7823
7824   if (!ok)
7825     {
7826       mpfr_t real;
7827       mpfr_t imag;
7828       mpfr_init(real);
7829       mpfr_init(imag);
7830       if (this->complex_constant_value(real, imag, &dummy))
7831         {
7832           Complex_expression::export_complex(exp, real, imag);
7833           ok = true;
7834         }
7835       mpfr_clear(real);
7836       mpfr_clear(imag);
7837     }
7838
7839   if (!ok)
7840     {
7841       error_at(this->location(), "value is not constant");
7842       return;
7843     }
7844
7845   // A trailing space lets us reliably identify the end of the number.
7846   exp->write_c_string(" ");
7847 }
7848
7849 // Class Call_expression.
7850
7851 // Traversal.
7852
7853 int
7854 Call_expression::do_traverse(Traverse* traverse)
7855 {
7856   if (Expression::traverse(&this->fn_, traverse) == TRAVERSE_EXIT)
7857     return TRAVERSE_EXIT;
7858   if (this->args_ != NULL)
7859     {
7860       if (this->args_->traverse(traverse) == TRAVERSE_EXIT)
7861         return TRAVERSE_EXIT;
7862     }
7863   return TRAVERSE_CONTINUE;
7864 }
7865
7866 // Lower a call statement.
7867
7868 Expression*
7869 Call_expression::do_lower(Gogo* gogo, Named_object* function, int)
7870 {
7871   // A type case can look like a function call.
7872   if (this->fn_->is_type_expression()
7873       && this->args_ != NULL
7874       && this->args_->size() == 1)
7875     return Expression::make_cast(this->fn_->type(), this->args_->front(),
7876                                  this->location());
7877
7878   // Recognize a call to a builtin function.
7879   Func_expression* fne = this->fn_->func_expression();
7880   if (fne != NULL
7881       && fne->named_object()->is_function_declaration()
7882       && fne->named_object()->func_declaration_value()->type()->is_builtin())
7883     return new Builtin_call_expression(gogo, this->fn_, this->args_,
7884                                        this->is_varargs_, this->location());
7885
7886   // Handle an argument which is a call to a function which returns
7887   // multiple results.
7888   if (this->args_ != NULL
7889       && this->args_->size() == 1
7890       && this->args_->front()->call_expression() != NULL
7891       && this->fn_->type()->function_type() != NULL)
7892     {
7893       Function_type* fntype = this->fn_->type()->function_type();
7894       size_t rc = this->args_->front()->call_expression()->result_count();
7895       if (rc > 1
7896           && fntype->parameters() != NULL
7897           && (fntype->parameters()->size() == rc
7898               || (fntype->is_varargs()
7899                   && fntype->parameters()->size() - 1 <= rc)))
7900         {
7901           Call_expression* call = this->args_->front()->call_expression();
7902           Expression_list* args = new Expression_list;
7903           for (size_t i = 0; i < rc; ++i)
7904             args->push_back(Expression::make_call_result(call, i));
7905           // We can't return a new call expression here, because this
7906           // one may be referenced by Call_result expressions.  FIXME.
7907           delete this->args_;
7908           this->args_ = args;
7909         }
7910     }
7911
7912   // Handle a call to a varargs function by packaging up the extra
7913   // parameters.
7914   if (this->fn_->type()->function_type() != NULL
7915       && this->fn_->type()->function_type()->is_varargs())
7916     {
7917       Function_type* fntype = this->fn_->type()->function_type();
7918       const Typed_identifier_list* parameters = fntype->parameters();
7919       gcc_assert(parameters != NULL && !parameters->empty());
7920       Type* varargs_type = parameters->back().type();
7921       return this->lower_varargs(gogo, function, varargs_type,
7922                                  parameters->size());
7923     }
7924
7925   return this;
7926 }
7927
7928 // Lower a call to a varargs function.  FUNCTION is the function in
7929 // which the call occurs--it's not the function we are calling.
7930 // VARARGS_TYPE is the type of the varargs parameter, a slice type.
7931 // PARAM_COUNT is the number of parameters of the function we are
7932 // calling; the last of these parameters will be the varargs
7933 // parameter.
7934
7935 Expression*
7936 Call_expression::lower_varargs(Gogo* gogo, Named_object* function,
7937                                Type* varargs_type, size_t param_count)
7938 {
7939   if (this->varargs_are_lowered_)
7940     return this;
7941
7942   source_location loc = this->location();
7943
7944   gcc_assert(param_count > 0);
7945   gcc_assert(varargs_type->is_open_array_type());
7946
7947   size_t arg_count = this->args_ == NULL ? 0 : this->args_->size();
7948   if (arg_count < param_count - 1)
7949     {
7950       // Not enough arguments; will be caught in check_types.
7951       return this;
7952     }
7953
7954   Expression_list* old_args = this->args_;
7955   Expression_list* new_args = new Expression_list();
7956   bool push_empty_arg = false;
7957   if (old_args == NULL || old_args->empty())
7958     {
7959       gcc_assert(param_count == 1);
7960       push_empty_arg = true;
7961     }
7962   else
7963     {
7964       Expression_list::const_iterator pa;
7965       int i = 1;
7966       for (pa = old_args->begin(); pa != old_args->end(); ++pa, ++i)
7967         {
7968           if (static_cast<size_t>(i) == param_count)
7969             break;
7970           new_args->push_back(*pa);
7971         }
7972
7973       // We have reached the varargs parameter.
7974
7975       bool issued_error = false;
7976       if (pa == old_args->end())
7977         push_empty_arg = true;
7978       else if (pa + 1 == old_args->end() && this->is_varargs_)
7979         new_args->push_back(*pa);
7980       else if (this->is_varargs_)
7981         {
7982           this->report_error(_("too many arguments"));
7983           return this;
7984         }
7985       else if (pa + 1 == old_args->end()
7986                && this->is_compatible_varargs_argument(function, *pa,
7987                                                        varargs_type,
7988                                                        &issued_error))
7989         new_args->push_back(*pa);
7990       else
7991         {
7992           Type* element_type = varargs_type->array_type()->element_type();
7993           Expression_list* vals = new Expression_list;
7994           for (; pa != old_args->end(); ++pa, ++i)
7995             {
7996               // Check types here so that we get a better message.
7997               Type* patype = (*pa)->type();
7998               source_location paloc = (*pa)->location();
7999               if (!this->check_argument_type(i, element_type, patype,
8000                                              paloc, issued_error))
8001                 continue;
8002               vals->push_back(*pa);
8003             }
8004           Expression* val =
8005             Expression::make_slice_composite_literal(varargs_type, vals, loc);
8006           new_args->push_back(val);
8007         }
8008     }
8009
8010   if (push_empty_arg)
8011     new_args->push_back(Expression::make_nil(loc));
8012
8013   // We can't return a new call expression here, because this one may
8014   // be referenced by Call_result expressions.  FIXME.
8015   if (old_args != NULL)
8016     delete old_args;
8017   this->args_ = new_args;
8018   this->varargs_are_lowered_ = true;
8019
8020   // Lower all the new subexpressions.
8021   Expression* ret = this;
8022   gogo->lower_expression(function, &ret);
8023   gcc_assert(ret == this);
8024   return ret;
8025 }
8026
8027 // Return true if ARG is a varargs argment which should be passed to
8028 // the varargs parameter of type PARAM_TYPE without wrapping.  ARG
8029 // will be the last argument passed in the call, and PARAM_TYPE will
8030 // be the type of the last parameter of the varargs function being
8031 // called.
8032
8033 bool
8034 Call_expression::is_compatible_varargs_argument(Named_object* function,
8035                                                 Expression* arg,
8036                                                 Type* param_type,
8037                                                 bool* issued_error)
8038 {
8039   *issued_error = false;
8040
8041   Type* var_type = NULL;
8042
8043   // The simple case is passing the varargs parameter of the caller.
8044   Var_expression* ve = arg->var_expression();
8045   if (ve != NULL && ve->named_object()->is_variable())
8046     {
8047       Variable* var = ve->named_object()->var_value();
8048       if (var->is_varargs_parameter())
8049         var_type = var->type();
8050     }
8051
8052   // The complex case is passing the varargs parameter of some
8053   // enclosing function.  This will look like passing down *c.f where
8054   // c is the closure variable and f is a field in the closure.
8055   if (function != NULL
8056       && function->func_value()->needs_closure()
8057       && arg->classification() == EXPRESSION_UNARY)
8058     {
8059       Unary_expression* ue = static_cast<Unary_expression*>(arg);
8060       if (ue->op() == OPERATOR_MULT)
8061         {
8062           Field_reference_expression* fre =
8063             ue->operand()->deref()->field_reference_expression();
8064           if (fre != NULL)
8065             {
8066               Var_expression* ve = fre->expr()->deref()->var_expression();
8067               if (ve != NULL)
8068                 {
8069                   Named_object* no = ve->named_object();
8070                   Function* f = function->func_value();
8071                   if (no == f->closure_var())
8072                     {
8073                       // At this point we know that this indeed a
8074                       // reference to some enclosing variable.  Now we
8075                       // need to figure out whether that variable is a
8076                       // varargs parameter.
8077                       Named_object* enclosing =
8078                         f->enclosing_var(fre->field_index());
8079                       Variable* var = enclosing->var_value();
8080                       if (var->is_varargs_parameter())
8081                         var_type = var->type();
8082                     }
8083                 }
8084             }
8085         }
8086     }
8087
8088   if (var_type == NULL)
8089     return false;
8090
8091   // We only match if the parameter is the same, with an identical
8092   // type.
8093   Array_type* var_at = var_type->array_type();
8094   gcc_assert(var_at != NULL);
8095   Array_type* param_at = param_type->array_type();
8096   if (param_at != NULL
8097       && Type::are_identical(var_at->element_type(),
8098                              param_at->element_type(), NULL))
8099     return true;
8100   error_at(arg->location(), "... mismatch: passing ...T as ...");
8101   *issued_error = true;
8102   return false;
8103 }
8104
8105 // Get the function type.  Returns NULL if we don't know the type.  If
8106 // this returns NULL, and if_ERROR is true, issues an error.
8107
8108 Function_type*
8109 Call_expression::get_function_type() const
8110 {
8111   return this->fn_->type()->function_type();
8112 }
8113
8114 // Return the number of values which this call will return.
8115
8116 size_t
8117 Call_expression::result_count() const
8118 {
8119   const Function_type* fntype = this->get_function_type();
8120   if (fntype == NULL)
8121     return 0;
8122   if (fntype->results() == NULL)
8123     return 0;
8124   return fntype->results()->size();
8125 }
8126
8127 // Return whether this is a call to the predeclared function recover.
8128
8129 bool
8130 Call_expression::is_recover_call() const
8131 {
8132   return this->do_is_recover_call();
8133 }
8134
8135 // Set the argument to the recover function.
8136
8137 void
8138 Call_expression::set_recover_arg(Expression* arg)
8139 {
8140   this->do_set_recover_arg(arg);
8141 }
8142
8143 // Virtual functions also implemented by Builtin_call_expression.
8144
8145 bool
8146 Call_expression::do_is_recover_call() const
8147 {
8148   return false;
8149 }
8150
8151 void
8152 Call_expression::do_set_recover_arg(Expression*)
8153 {
8154   gcc_unreachable();
8155 }
8156
8157 // Get the type.
8158
8159 Type*
8160 Call_expression::do_type()
8161 {
8162   if (this->type_ != NULL)
8163     return this->type_;
8164
8165   Type* ret;
8166   Function_type* fntype = this->get_function_type();
8167   if (fntype == NULL)
8168     return Type::make_error_type();
8169
8170   const Typed_identifier_list* results = fntype->results();
8171   if (results == NULL)
8172     ret = Type::make_void_type();
8173   else if (results->size() == 1)
8174     ret = results->begin()->type();
8175   else
8176     ret = Type::make_call_multiple_result_type(this);
8177
8178   this->type_ = ret;
8179
8180   return this->type_;
8181 }
8182
8183 // Determine types for a call expression.  We can use the function
8184 // parameter types to set the types of the arguments.
8185
8186 void
8187 Call_expression::do_determine_type(const Type_context*)
8188 {
8189   this->fn_->determine_type_no_context();
8190   Function_type* fntype = this->get_function_type();
8191   const Typed_identifier_list* parameters = NULL;
8192   if (fntype != NULL)
8193     parameters = fntype->parameters();
8194   if (this->args_ != NULL)
8195     {
8196       Typed_identifier_list::const_iterator pt;
8197       if (parameters != NULL)
8198         pt = parameters->begin();
8199       for (Expression_list::const_iterator pa = this->args_->begin();
8200            pa != this->args_->end();
8201            ++pa)
8202         {
8203           if (parameters != NULL && pt != parameters->end())
8204             {
8205               Type_context subcontext(pt->type(), false);
8206               (*pa)->determine_type(&subcontext);
8207               ++pt;
8208             }
8209           else
8210             (*pa)->determine_type_no_context();
8211         }
8212     }
8213 }
8214
8215 // Check types for parameter I.
8216
8217 bool
8218 Call_expression::check_argument_type(int i, const Type* parameter_type,
8219                                      const Type* argument_type,
8220                                      source_location argument_location,
8221                                      bool issued_error)
8222 {
8223   std::string reason;
8224   if (!Type::are_assignable(parameter_type, argument_type, &reason))
8225     {
8226       if (!issued_error)
8227         {
8228           if (reason.empty())
8229             error_at(argument_location, "argument %d has incompatible type", i);
8230           else
8231             error_at(argument_location,
8232                      "argument %d has incompatible type (%s)",
8233                      i, reason.c_str());
8234         }
8235       this->set_is_error();
8236       return false;
8237     }
8238   return true;
8239 }
8240
8241 // Check types.
8242
8243 void
8244 Call_expression::do_check_types(Gogo*)
8245 {
8246   Function_type* fntype = this->get_function_type();
8247   if (fntype == NULL)
8248     {
8249       if (!this->fn_->type()->is_error_type())
8250         this->report_error(_("expected function"));
8251       return;
8252     }
8253
8254   if (fntype->is_method())
8255     {
8256       // We don't support pointers to methods, so the function has to
8257       // be a bound method expression.
8258       Bound_method_expression* bme = this->fn_->bound_method_expression();
8259       if (bme == NULL)
8260         {
8261           this->report_error(_("method call without object"));
8262           return;
8263         }
8264       Type* first_arg_type = bme->first_argument()->type();
8265       if (first_arg_type->points_to() == NULL)
8266         {
8267           // When passing a value, we need to check that we are
8268           // permitted to copy it.
8269           std::string reason;
8270           if (!Type::are_assignable(fntype->receiver()->type(),
8271                                     first_arg_type, &reason))
8272             {
8273               if (reason.empty())
8274                 this->report_error(_("incompatible type for receiver"));
8275               else
8276                 {
8277                   error_at(this->location(),
8278                            "incompatible type for receiver (%s)",
8279                            reason.c_str());
8280                   this->set_is_error();
8281                 }
8282             }
8283         }
8284     }
8285
8286   // Note that varargs was handled by the lower_varargs() method, so
8287   // we don't have to worry about it here.
8288
8289   const Typed_identifier_list* parameters = fntype->parameters();
8290   if (this->args_ == NULL)
8291     {
8292       if (parameters != NULL && !parameters->empty())
8293         this->report_error(_("not enough arguments"));
8294     }
8295   else if (parameters == NULL)
8296     this->report_error(_("too many arguments"));
8297   else
8298     {
8299       int i = 0;
8300       Typed_identifier_list::const_iterator pt = parameters->begin();
8301       for (Expression_list::const_iterator pa = this->args_->begin();
8302            pa != this->args_->end();
8303            ++pa, ++pt, ++i)
8304         {
8305           if (pt == parameters->end())
8306             {
8307               this->report_error(_("too many arguments"));
8308               return;
8309             }
8310           this->check_argument_type(i + 1, pt->type(), (*pa)->type(),
8311                                     (*pa)->location(), false);
8312         }
8313       if (pt != parameters->end())
8314         this->report_error(_("not enough arguments"));
8315     }
8316 }
8317
8318 // Return whether we have to use a temporary variable to ensure that
8319 // we evaluate this call expression in order.  If the call returns no
8320 // results then it will inevitably be executed last.  If the call
8321 // returns more than one result then it will be used with Call_result
8322 // expressions.  So we only have to use a temporary variable if the
8323 // call returns exactly one result.
8324
8325 bool
8326 Call_expression::do_must_eval_in_order() const
8327 {
8328   return this->result_count() == 1;
8329 }
8330
8331 // Get the function and the first argument to use when calling a bound
8332 // method.
8333
8334 tree
8335 Call_expression::bound_method_function(Translate_context* context,
8336                                        Bound_method_expression* bound_method,
8337                                        tree* first_arg_ptr)
8338 {
8339   Expression* first_argument = bound_method->first_argument();
8340   tree first_arg = first_argument->get_tree(context);
8341   if (first_arg == error_mark_node)
8342     return error_mark_node;
8343
8344   // We always pass a pointer to the first argument when calling a
8345   // method.
8346   if (first_argument->type()->points_to() == NULL)
8347     {
8348       tree pointer_to_arg_type = build_pointer_type(TREE_TYPE(first_arg));
8349       if (TREE_ADDRESSABLE(TREE_TYPE(first_arg))
8350           || DECL_P(first_arg)
8351           || TREE_CODE(first_arg) == INDIRECT_REF
8352           || TREE_CODE(first_arg) == COMPONENT_REF)
8353         {
8354           first_arg = build_fold_addr_expr(first_arg);
8355           if (DECL_P(first_arg))
8356             TREE_ADDRESSABLE(first_arg) = 1;
8357         }
8358       else
8359         {
8360           tree tmp = create_tmp_var(TREE_TYPE(first_arg),
8361                                     get_name(first_arg));
8362           DECL_IGNORED_P(tmp) = 0;
8363           DECL_INITIAL(tmp) = first_arg;
8364           first_arg = build2(COMPOUND_EXPR, pointer_to_arg_type,
8365                              build1(DECL_EXPR, void_type_node, tmp),
8366                              build_fold_addr_expr(tmp));
8367           TREE_ADDRESSABLE(tmp) = 1;
8368         }
8369       if (first_arg == error_mark_node)
8370         return error_mark_node;
8371     }
8372
8373   Type* fatype = bound_method->first_argument_type();
8374   if (fatype != NULL)
8375     {
8376       if (fatype->points_to() == NULL)
8377         fatype = Type::make_pointer_type(fatype);
8378       first_arg = fold_convert(fatype->get_tree(context->gogo()), first_arg);
8379       if (first_arg == error_mark_node
8380           || TREE_TYPE(first_arg) == error_mark_node)
8381         return error_mark_node;
8382     }
8383
8384   *first_arg_ptr = first_arg;
8385
8386   return bound_method->method()->get_tree(context);
8387 }
8388
8389 // Get the function and the first argument to use when calling an
8390 // interface method.
8391
8392 tree
8393 Call_expression::interface_method_function(
8394     Translate_context* context,
8395     Interface_field_reference_expression* interface_method,
8396     tree* first_arg_ptr)
8397 {
8398   tree expr = interface_method->expr()->get_tree(context);
8399   if (expr == error_mark_node)
8400     return error_mark_node;
8401   expr = save_expr(expr);
8402   tree first_arg = interface_method->get_underlying_object_tree(context, expr);
8403   if (first_arg == error_mark_node)
8404     return error_mark_node;
8405   *first_arg_ptr = first_arg;
8406   return interface_method->get_function_tree(context, expr);
8407 }
8408
8409 // Build the call expression.
8410
8411 tree
8412 Call_expression::do_get_tree(Translate_context* context)
8413 {
8414   if (this->tree_ != NULL_TREE)
8415     return this->tree_;
8416
8417   Function_type* fntype = this->get_function_type();
8418   if (fntype == NULL)
8419     return error_mark_node;
8420
8421   if (this->fn_->is_error_expression())
8422     return error_mark_node;
8423
8424   Gogo* gogo = context->gogo();
8425   source_location location = this->location();
8426
8427   Func_expression* func = this->fn_->func_expression();
8428   Bound_method_expression* bound_method = this->fn_->bound_method_expression();
8429   Interface_field_reference_expression* interface_method =
8430     this->fn_->interface_field_reference_expression();
8431   const bool has_closure = func != NULL && func->closure() != NULL;
8432   const bool is_method = bound_method != NULL || interface_method != NULL;
8433   gcc_assert(!fntype->is_method() || is_method);
8434
8435   int nargs;
8436   tree* args;
8437   if (this->args_ == NULL || this->args_->empty())
8438     {
8439       nargs = is_method ? 1 : 0;
8440       args = nargs == 0 ? NULL : new tree[nargs];
8441     }
8442   else
8443     {
8444       const Typed_identifier_list* params = fntype->parameters();
8445       gcc_assert(params != NULL);
8446
8447       nargs = this->args_->size();
8448       int i = is_method ? 1 : 0;
8449       nargs += i;
8450       args = new tree[nargs];
8451
8452       Typed_identifier_list::const_iterator pp = params->begin();
8453       Expression_list::const_iterator pe;
8454       for (pe = this->args_->begin();
8455            pe != this->args_->end();
8456            ++pe, ++pp, ++i)
8457         {
8458           tree arg_val = (*pe)->get_tree(context);
8459           args[i] = Expression::convert_for_assignment(context,
8460                                                        pp->type(),
8461                                                        (*pe)->type(),
8462                                                        arg_val,
8463                                                        location);
8464           if (args[i] == error_mark_node)
8465             return error_mark_node;
8466         }
8467       gcc_assert(pp == params->end());
8468       gcc_assert(i == nargs);
8469     }
8470
8471   tree rettype = TREE_TYPE(TREE_TYPE(fntype->get_tree(gogo)));
8472   if (rettype == error_mark_node)
8473     return error_mark_node;
8474
8475   tree fn;
8476   if (has_closure)
8477     fn = func->get_tree_without_closure(gogo);
8478   else if (!is_method)
8479     fn = this->fn_->get_tree(context);
8480   else if (bound_method != NULL)
8481     fn = this->bound_method_function(context, bound_method, &args[0]);
8482   else if (interface_method != NULL)
8483     fn = this->interface_method_function(context, interface_method, &args[0]);
8484   else
8485     gcc_unreachable();
8486
8487   if (fn == error_mark_node || TREE_TYPE(fn) == error_mark_node)
8488     return error_mark_node;
8489
8490   // This is to support builtin math functions when using 80387 math.
8491   tree fndecl = fn;
8492   if (TREE_CODE(fndecl) == ADDR_EXPR)
8493     fndecl = TREE_OPERAND(fndecl, 0);
8494   tree excess_type = NULL_TREE;
8495   if (DECL_P(fndecl)
8496       && DECL_IS_BUILTIN(fndecl)
8497       && DECL_BUILT_IN_CLASS(fndecl) == BUILT_IN_NORMAL
8498       && nargs > 0
8499       && ((SCALAR_FLOAT_TYPE_P(rettype)
8500            && SCALAR_FLOAT_TYPE_P(TREE_TYPE(args[0])))
8501           || (COMPLEX_FLOAT_TYPE_P(rettype)
8502               && COMPLEX_FLOAT_TYPE_P(TREE_TYPE(args[0])))))
8503     {
8504       excess_type = excess_precision_type(TREE_TYPE(args[0]));
8505       if (excess_type != NULL_TREE)
8506         {
8507           tree excess_fndecl = mathfn_built_in(excess_type,
8508                                                DECL_FUNCTION_CODE(fndecl));
8509           if (excess_fndecl == NULL_TREE)
8510             excess_type = NULL_TREE;
8511           else
8512             {
8513               fn = build_fold_addr_expr_loc(location, excess_fndecl);
8514               for (int i = 0; i < nargs; ++i)
8515                 args[i] = ::convert(excess_type, args[i]);
8516             }
8517         }
8518     }
8519
8520   tree ret = build_call_array(excess_type != NULL_TREE ? excess_type : rettype,
8521                               fn, nargs, args);
8522   delete[] args;
8523
8524   SET_EXPR_LOCATION(ret, location);
8525
8526   if (has_closure)
8527     {
8528       tree closure_tree = func->closure()->get_tree(context);
8529       if (closure_tree != error_mark_node)
8530         CALL_EXPR_STATIC_CHAIN(ret) = closure_tree;
8531     }
8532
8533   // If this is a recursive function type which returns itself, as in
8534   //   type F func() F
8535   // we have used ptr_type_node for the return type.  Add a cast here
8536   // to the correct type.
8537   if (TREE_TYPE(ret) == ptr_type_node)
8538     {
8539       tree t = this->type()->get_tree(gogo);
8540       ret = fold_convert_loc(location, t, ret);
8541     }
8542
8543   if (excess_type != NULL_TREE)
8544     {
8545       // Calling convert here can undo our excess precision change.
8546       // That may or may not be a bug in convert_to_real.
8547       ret = build1(NOP_EXPR, rettype, ret);
8548     }
8549
8550   // If there is more than one result, we will refer to the call
8551   // multiple times.
8552   if (fntype->results() != NULL && fntype->results()->size() > 1)
8553     ret = save_expr(ret);
8554
8555   this->tree_ = ret;
8556
8557   return ret;
8558 }
8559
8560 // Make a call expression.
8561
8562 Call_expression*
8563 Expression::make_call(Expression* fn, Expression_list* args, bool is_varargs,
8564                       source_location location)
8565 {
8566   return new Call_expression(fn, args, is_varargs, location);
8567 }
8568
8569 // A single result from a call which returns multiple results.
8570
8571 class Call_result_expression : public Expression
8572 {
8573  public:
8574   Call_result_expression(Call_expression* call, unsigned int index)
8575     : Expression(EXPRESSION_CALL_RESULT, call->location()),
8576       call_(call), index_(index)
8577   { }
8578
8579  protected:
8580   int
8581   do_traverse(Traverse*);
8582
8583   Type*
8584   do_type();
8585
8586   void
8587   do_determine_type(const Type_context*);
8588
8589   void
8590   do_check_types(Gogo*);
8591
8592   Expression*
8593   do_copy()
8594   {
8595     return new Call_result_expression(this->call_->call_expression(),
8596                                       this->index_);
8597   }
8598
8599   bool
8600   do_must_eval_in_order() const
8601   { return true; }
8602
8603   tree
8604   do_get_tree(Translate_context*);
8605
8606  private:
8607   // The underlying call expression.
8608   Expression* call_;
8609   // Which result we want.
8610   unsigned int index_;
8611 };
8612
8613 // Traverse a call result.
8614
8615 int
8616 Call_result_expression::do_traverse(Traverse* traverse)
8617 {
8618   if (traverse->remember_expression(this->call_))
8619     {
8620       // We have already traversed the call expression.
8621       return TRAVERSE_CONTINUE;
8622     }
8623   return Expression::traverse(&this->call_, traverse);
8624 }
8625
8626 // Get the type.
8627
8628 Type*
8629 Call_result_expression::do_type()
8630 {
8631   // THIS->CALL_ can be replaced with a temporary reference due to
8632   // Call_expression::do_must_eval_in_order when there is an error.
8633   Call_expression* ce = this->call_->call_expression();
8634   if (ce == NULL)
8635     return Type::make_error_type();
8636   Function_type* fntype = ce->get_function_type();
8637   if (fntype == NULL)
8638     return Type::make_error_type();
8639   const Typed_identifier_list* results = fntype->results();
8640   Typed_identifier_list::const_iterator pr = results->begin();
8641   for (unsigned int i = 0; i < this->index_; ++i)
8642     {
8643       if (pr == results->end())
8644         return Type::make_error_type();
8645       ++pr;
8646     }
8647   if (pr == results->end())
8648     return Type::make_error_type();
8649   return pr->type();
8650 }
8651
8652 // Check the type.  This is where we give an error if we're trying to
8653 // extract too many values from a call.
8654
8655 void
8656 Call_result_expression::do_check_types(Gogo*)
8657 {
8658   bool ok = true;
8659   Call_expression* ce = this->call_->call_expression();
8660   if (ce != NULL)
8661     ok = this->index_ < ce->result_count();
8662   else
8663     {
8664       // This can happen when the call returns a single value but we
8665       // are asking for the second result.
8666       if (this->call_->is_error_expression())
8667         return;
8668       ok = false;
8669     }
8670   if (!ok)
8671     error_at(this->location(),
8672              "number of results does not match number of values");
8673 }
8674
8675 // Determine the type.  We have nothing to do here, but the 0 result
8676 // needs to pass down to the caller.
8677
8678 void
8679 Call_result_expression::do_determine_type(const Type_context*)
8680 {
8681   if (this->index_ == 0)
8682     this->call_->determine_type_no_context();
8683 }
8684
8685 // Return the tree.
8686
8687 tree
8688 Call_result_expression::do_get_tree(Translate_context* context)
8689 {
8690   tree call_tree = this->call_->get_tree(context);
8691   if (call_tree == error_mark_node)
8692     return error_mark_node;
8693   gcc_assert(TREE_CODE(TREE_TYPE(call_tree)) == RECORD_TYPE);
8694   tree field = TYPE_FIELDS(TREE_TYPE(call_tree));
8695   for (unsigned int i = 0; i < this->index_; ++i)
8696     {
8697       gcc_assert(field != NULL_TREE);
8698       field = DECL_CHAIN(field);
8699     }
8700   gcc_assert(field != NULL_TREE);
8701   return build3(COMPONENT_REF, TREE_TYPE(field), call_tree, field, NULL_TREE);
8702 }
8703
8704 // Make a reference to a single result of a call which returns
8705 // multiple results.
8706
8707 Expression*
8708 Expression::make_call_result(Call_expression* call, unsigned int index)
8709 {
8710   return new Call_result_expression(call, index);
8711 }
8712
8713 // Class Index_expression.
8714
8715 // Traversal.
8716
8717 int
8718 Index_expression::do_traverse(Traverse* traverse)
8719 {
8720   if (Expression::traverse(&this->left_, traverse) == TRAVERSE_EXIT
8721       || Expression::traverse(&this->start_, traverse) == TRAVERSE_EXIT
8722       || (this->end_ != NULL
8723           && Expression::traverse(&this->end_, traverse) == TRAVERSE_EXIT))
8724     return TRAVERSE_EXIT;
8725   return TRAVERSE_CONTINUE;
8726 }
8727
8728 // Lower an index expression.  This converts the generic index
8729 // expression into an array index, a string index, or a map index.
8730
8731 Expression*
8732 Index_expression::do_lower(Gogo*, Named_object*, int)
8733 {
8734   source_location location = this->location();
8735   Expression* left = this->left_;
8736   Expression* start = this->start_;
8737   Expression* end = this->end_;
8738
8739   Type* type = left->type();
8740   if (type->is_error_type())
8741     return Expression::make_error(location);
8742   else if (type->array_type() != NULL)
8743     return Expression::make_array_index(left, start, end, location);
8744   else if (type->points_to() != NULL
8745            && type->points_to()->array_type() != NULL
8746            && !type->points_to()->is_open_array_type())
8747     {
8748       Expression* deref = Expression::make_unary(OPERATOR_MULT, left,
8749                                                  location);
8750       return Expression::make_array_index(deref, start, end, location);
8751     }
8752   else if (type->is_string_type())
8753     return Expression::make_string_index(left, start, end, location);
8754   else if (type->map_type() != NULL)
8755     {
8756       if (end != NULL)
8757         {
8758           error_at(location, "invalid slice of map");
8759           return Expression::make_error(location);
8760         }
8761       Map_index_expression* ret= Expression::make_map_index(left, start,
8762                                                             location);
8763       if (this->is_lvalue_)
8764         ret->set_is_lvalue();
8765       return ret;
8766     }
8767   else
8768     {
8769       error_at(location,
8770                "attempt to index object which is not array, string, or map");
8771       return Expression::make_error(location);
8772     }
8773 }
8774
8775 // Make an index expression.
8776
8777 Expression*
8778 Expression::make_index(Expression* left, Expression* start, Expression* end,
8779                        source_location location)
8780 {
8781   return new Index_expression(left, start, end, location);
8782 }
8783
8784 // An array index.  This is used for both indexing and slicing.
8785
8786 class Array_index_expression : public Expression
8787 {
8788  public:
8789   Array_index_expression(Expression* array, Expression* start,
8790                          Expression* end, source_location location)
8791     : Expression(EXPRESSION_ARRAY_INDEX, location),
8792       array_(array), start_(start), end_(end), type_(NULL)
8793   { }
8794
8795  protected:
8796   int
8797   do_traverse(Traverse*);
8798
8799   Type*
8800   do_type();
8801
8802   void
8803   do_determine_type(const Type_context*);
8804
8805   void
8806   do_check_types(Gogo*);
8807
8808   Expression*
8809   do_copy()
8810   {
8811     return Expression::make_array_index(this->array_->copy(),
8812                                         this->start_->copy(),
8813                                         (this->end_ == NULL
8814                                          ? NULL
8815                                          : this->end_->copy()),
8816                                         this->location());
8817   }
8818
8819   bool
8820   do_is_addressable() const;
8821
8822   void
8823   do_address_taken(bool escapes)
8824   { this->array_->address_taken(escapes); }
8825
8826   tree
8827   do_get_tree(Translate_context*);
8828
8829  private:
8830   // The array we are getting a value from.
8831   Expression* array_;
8832   // The start or only index.
8833   Expression* start_;
8834   // The end index of a slice.  This may be NULL for a simple array
8835   // index, or it may be a nil expression for the length of the array.
8836   Expression* end_;
8837   // The type of the expression.
8838   Type* type_;
8839 };
8840
8841 // Array index traversal.
8842
8843 int
8844 Array_index_expression::do_traverse(Traverse* traverse)
8845 {
8846   if (Expression::traverse(&this->array_, traverse) == TRAVERSE_EXIT)
8847     return TRAVERSE_EXIT;
8848   if (Expression::traverse(&this->start_, traverse) == TRAVERSE_EXIT)
8849     return TRAVERSE_EXIT;
8850   if (this->end_ != NULL)
8851     {
8852       if (Expression::traverse(&this->end_, traverse) == TRAVERSE_EXIT)
8853         return TRAVERSE_EXIT;
8854     }
8855   return TRAVERSE_CONTINUE;
8856 }
8857
8858 // Return the type of an array index.
8859
8860 Type*
8861 Array_index_expression::do_type()
8862 {
8863   if (this->type_ == NULL)
8864     {
8865      Array_type* type = this->array_->type()->array_type();
8866       if (type == NULL)
8867         this->type_ = Type::make_error_type();
8868       else if (this->end_ == NULL)
8869         this->type_ = type->element_type();
8870       else if (type->is_open_array_type())
8871         {
8872           // A slice of a slice has the same type as the original
8873           // slice.
8874           this->type_ = this->array_->type()->deref();
8875         }
8876       else
8877         {
8878           // A slice of an array is a slice.
8879           this->type_ = Type::make_array_type(type->element_type(), NULL);
8880         }
8881     }
8882   return this->type_;
8883 }
8884
8885 // Set the type of an array index.
8886
8887 void
8888 Array_index_expression::do_determine_type(const Type_context*)
8889 {
8890   this->array_->determine_type_no_context();
8891   Type_context subcontext(NULL, true);
8892   this->start_->determine_type(&subcontext);
8893   if (this->end_ != NULL)
8894     this->end_->determine_type(&subcontext);
8895 }
8896
8897 // Check types of an array index.
8898
8899 void
8900 Array_index_expression::do_check_types(Gogo*)
8901 {
8902   if (this->start_->type()->integer_type() == NULL)
8903     this->report_error(_("index must be integer"));
8904   if (this->end_ != NULL
8905       && this->end_->type()->integer_type() == NULL
8906       && !this->end_->is_nil_expression())
8907     this->report_error(_("slice end must be integer"));
8908
8909   Array_type* array_type = this->array_->type()->array_type();
8910   gcc_assert(array_type != NULL);
8911
8912   unsigned int int_bits =
8913     Type::lookup_integer_type("int")->integer_type()->bits();
8914
8915   Type* dummy;
8916   mpz_t lval;
8917   mpz_init(lval);
8918   bool lval_valid = (array_type->length() != NULL
8919                      && array_type->length()->integer_constant_value(true,
8920                                                                      lval,
8921                                                                      &dummy));
8922   mpz_t ival;
8923   mpz_init(ival);
8924   if (this->start_->integer_constant_value(true, ival, &dummy))
8925     {
8926       if (mpz_sgn(ival) < 0
8927           || mpz_sizeinbase(ival, 2) >= int_bits
8928           || (lval_valid
8929               && (this->end_ == NULL
8930                   ? mpz_cmp(ival, lval) >= 0
8931                   : mpz_cmp(ival, lval) > 0)))
8932         {
8933           error_at(this->start_->location(), "array index out of bounds");
8934           this->set_is_error();
8935         }
8936     }
8937   if (this->end_ != NULL && !this->end_->is_nil_expression())
8938     {
8939       if (this->end_->integer_constant_value(true, ival, &dummy))
8940         {
8941           if (mpz_sgn(ival) < 0
8942               || mpz_sizeinbase(ival, 2) >= int_bits
8943               || (lval_valid && mpz_cmp(ival, lval) > 0))
8944             {
8945               error_at(this->end_->location(), "array index out of bounds");
8946               this->set_is_error();
8947             }
8948         }
8949     }
8950   mpz_clear(ival);
8951   mpz_clear(lval);
8952
8953   // A slice of an array requires an addressable array.  A slice of a
8954   // slice is always possible.
8955   if (this->end_ != NULL
8956       && !array_type->is_open_array_type()
8957       && !this->array_->is_addressable())
8958     this->report_error(_("array is not addressable"));
8959 }
8960
8961 // Return whether this expression is addressable.
8962
8963 bool
8964 Array_index_expression::do_is_addressable() const
8965 {
8966   // A slice expression is not addressable.
8967   if (this->end_ != NULL)
8968     return false;
8969
8970   // An index into a slice is addressable.
8971   if (this->array_->type()->is_open_array_type())
8972     return true;
8973
8974   // An index into an array is addressable if the array is
8975   // addressable.
8976   return this->array_->is_addressable();
8977 }
8978
8979 // Get a tree for an array index.
8980
8981 tree
8982 Array_index_expression::do_get_tree(Translate_context* context)
8983 {
8984   Gogo* gogo = context->gogo();
8985   source_location loc = this->location();
8986
8987   Array_type* array_type = this->array_->type()->array_type();
8988   gcc_assert(array_type != NULL);
8989
8990   tree type_tree = array_type->get_tree(gogo);
8991
8992   tree array_tree = this->array_->get_tree(context);
8993   if (array_tree == error_mark_node)
8994     return error_mark_node;
8995
8996   if (array_type->length() == NULL && !DECL_P(array_tree))
8997     array_tree = save_expr(array_tree);
8998   tree length_tree = array_type->length_tree(gogo, array_tree);
8999   length_tree = save_expr(length_tree);
9000   tree length_type = TREE_TYPE(length_tree);
9001
9002   tree bad_index = boolean_false_node;
9003
9004   tree start_tree = this->start_->get_tree(context);
9005   if (start_tree == error_mark_node)
9006     return error_mark_node;
9007   if (!DECL_P(start_tree))
9008     start_tree = save_expr(start_tree);
9009   if (!INTEGRAL_TYPE_P(TREE_TYPE(start_tree)))
9010     start_tree = convert_to_integer(length_type, start_tree);
9011
9012   bad_index = Expression::check_bounds(start_tree, length_type, bad_index,
9013                                        loc);
9014
9015   start_tree = fold_convert_loc(loc, length_type, start_tree);
9016   bad_index = fold_build2_loc(loc, TRUTH_OR_EXPR, boolean_type_node, bad_index,
9017                               fold_build2_loc(loc,
9018                                               (this->end_ == NULL
9019                                                ? GE_EXPR
9020                                                : GT_EXPR),
9021                                               boolean_type_node, start_tree,
9022                                               length_tree));
9023
9024   int code = (array_type->length() != NULL
9025               ? (this->end_ == NULL
9026                  ? RUNTIME_ERROR_ARRAY_INDEX_OUT_OF_BOUNDS
9027                  : RUNTIME_ERROR_ARRAY_SLICE_OUT_OF_BOUNDS)
9028               : (this->end_ == NULL
9029                  ? RUNTIME_ERROR_SLICE_INDEX_OUT_OF_BOUNDS
9030                  : RUNTIME_ERROR_SLICE_SLICE_OUT_OF_BOUNDS));
9031   tree crash = Gogo::runtime_error(code, loc);
9032
9033   if (this->end_ == NULL)
9034     {
9035       // Simple array indexing.  This has to return an l-value, so
9036       // wrap the index check into START_TREE.
9037       start_tree = build2(COMPOUND_EXPR, TREE_TYPE(start_tree),
9038                           build3(COND_EXPR, void_type_node,
9039                                  bad_index, crash, NULL_TREE),
9040                           start_tree);
9041       start_tree = fold_convert_loc(loc, sizetype, start_tree);
9042
9043       if (array_type->length() != NULL)
9044         {
9045           // Fixed array.
9046           return build4(ARRAY_REF, TREE_TYPE(type_tree), array_tree,
9047                         start_tree, NULL_TREE, NULL_TREE);
9048         }
9049       else
9050         {
9051           // Open array.
9052           tree values = array_type->value_pointer_tree(gogo, array_tree);
9053           tree element_type_tree = array_type->element_type()->get_tree(gogo);
9054           tree element_size = TYPE_SIZE_UNIT(element_type_tree);
9055           tree offset = fold_build2_loc(loc, MULT_EXPR, sizetype,
9056                                         start_tree, element_size);
9057           tree ptr = fold_build2_loc(loc, POINTER_PLUS_EXPR,
9058                                      TREE_TYPE(values), values, offset);
9059           return build_fold_indirect_ref(ptr);
9060         }
9061     }
9062
9063   // Array slice.
9064
9065   tree capacity_tree = array_type->capacity_tree(gogo, array_tree);
9066   capacity_tree = fold_convert_loc(loc, length_type, capacity_tree);
9067
9068   tree end_tree;
9069   if (this->end_->is_nil_expression())
9070     end_tree = length_tree;
9071   else
9072     {
9073       end_tree = this->end_->get_tree(context);
9074       if (end_tree == error_mark_node)
9075         return error_mark_node;
9076       if (!DECL_P(end_tree))
9077         end_tree = save_expr(end_tree);
9078       if (!INTEGRAL_TYPE_P(TREE_TYPE(end_tree)))
9079         end_tree = convert_to_integer(length_type, end_tree);
9080
9081       bad_index = Expression::check_bounds(end_tree, length_type, bad_index,
9082                                            loc);
9083
9084       end_tree = fold_convert_loc(loc, length_type, end_tree);
9085
9086       capacity_tree = save_expr(capacity_tree);
9087       tree bad_end = fold_build2_loc(loc, TRUTH_OR_EXPR, boolean_type_node,
9088                                      fold_build2_loc(loc, LT_EXPR,
9089                                                      boolean_type_node,
9090                                                      end_tree, start_tree),
9091                                      fold_build2_loc(loc, GT_EXPR,
9092                                                      boolean_type_node,
9093                                                      end_tree, capacity_tree));
9094       bad_index = fold_build2_loc(loc, TRUTH_OR_EXPR, boolean_type_node,
9095                                   bad_index, bad_end);
9096     }
9097
9098   tree element_type_tree = array_type->element_type()->get_tree(gogo);
9099   tree element_size = TYPE_SIZE_UNIT(element_type_tree);
9100
9101   tree offset = fold_build2_loc(loc, MULT_EXPR, sizetype,
9102                                 fold_convert_loc(loc, sizetype, start_tree),
9103                                 element_size);
9104
9105   tree value_pointer = array_type->value_pointer_tree(gogo, array_tree);
9106
9107   value_pointer = fold_build2_loc(loc, POINTER_PLUS_EXPR,
9108                                   TREE_TYPE(value_pointer),
9109                                   value_pointer, offset);
9110
9111   tree result_length_tree = fold_build2_loc(loc, MINUS_EXPR, length_type,
9112                                             end_tree, start_tree);
9113
9114   tree result_capacity_tree = fold_build2_loc(loc, MINUS_EXPR, length_type,
9115                                               capacity_tree, start_tree);
9116
9117   tree struct_tree = this->type()->get_tree(gogo);
9118   gcc_assert(TREE_CODE(struct_tree) == RECORD_TYPE);
9119
9120   VEC(constructor_elt,gc)* init = VEC_alloc(constructor_elt, gc, 3);
9121
9122   constructor_elt* elt = VEC_quick_push(constructor_elt, init, NULL);
9123   tree field = TYPE_FIELDS(struct_tree);
9124   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__values") == 0);
9125   elt->index = field;
9126   elt->value = value_pointer;
9127
9128   elt = VEC_quick_push(constructor_elt, init, NULL);
9129   field = DECL_CHAIN(field);
9130   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__count") == 0);
9131   elt->index = field;
9132   elt->value = fold_convert_loc(loc, TREE_TYPE(field), result_length_tree);
9133
9134   elt = VEC_quick_push(constructor_elt, init, NULL);
9135   field = DECL_CHAIN(field);
9136   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__capacity") == 0);
9137   elt->index = field;
9138   elt->value = fold_convert_loc(loc, TREE_TYPE(field), result_capacity_tree);
9139
9140   tree constructor = build_constructor(struct_tree, init);
9141
9142   if (TREE_CONSTANT(value_pointer)
9143       && TREE_CONSTANT(result_length_tree)
9144       && TREE_CONSTANT(result_capacity_tree))
9145     TREE_CONSTANT(constructor) = 1;
9146
9147   return fold_build2_loc(loc, COMPOUND_EXPR, TREE_TYPE(constructor),
9148                          build3(COND_EXPR, void_type_node,
9149                                 bad_index, crash, NULL_TREE),
9150                          constructor);
9151 }
9152
9153 // Make an array index expression.  END may be NULL.
9154
9155 Expression*
9156 Expression::make_array_index(Expression* array, Expression* start,
9157                              Expression* end, source_location location)
9158 {
9159   // Taking a slice of a composite literal requires moving the literal
9160   // onto the heap.
9161   if (end != NULL && array->is_composite_literal())
9162     {
9163       array = Expression::make_heap_composite(array, location);
9164       array = Expression::make_unary(OPERATOR_MULT, array, location);
9165     }
9166   return new Array_index_expression(array, start, end, location);
9167 }
9168
9169 // A string index.  This is used for both indexing and slicing.
9170
9171 class String_index_expression : public Expression
9172 {
9173  public:
9174   String_index_expression(Expression* string, Expression* start,
9175                           Expression* end, source_location location)
9176     : Expression(EXPRESSION_STRING_INDEX, location),
9177       string_(string), start_(start), end_(end)
9178   { }
9179
9180  protected:
9181   int
9182   do_traverse(Traverse*);
9183
9184   Type*
9185   do_type();
9186
9187   void
9188   do_determine_type(const Type_context*);
9189
9190   void
9191   do_check_types(Gogo*);
9192
9193   Expression*
9194   do_copy()
9195   {
9196     return Expression::make_string_index(this->string_->copy(),
9197                                          this->start_->copy(),
9198                                          (this->end_ == NULL
9199                                           ? NULL
9200                                           : this->end_->copy()),
9201                                          this->location());
9202   }
9203
9204   tree
9205   do_get_tree(Translate_context*);
9206
9207  private:
9208   // The string we are getting a value from.
9209   Expression* string_;
9210   // The start or only index.
9211   Expression* start_;
9212   // The end index of a slice.  This may be NULL for a single index,
9213   // or it may be a nil expression for the length of the string.
9214   Expression* end_;
9215 };
9216
9217 // String index traversal.
9218
9219 int
9220 String_index_expression::do_traverse(Traverse* traverse)
9221 {
9222   if (Expression::traverse(&this->string_, traverse) == TRAVERSE_EXIT)
9223     return TRAVERSE_EXIT;
9224   if (Expression::traverse(&this->start_, traverse) == TRAVERSE_EXIT)
9225     return TRAVERSE_EXIT;
9226   if (this->end_ != NULL)
9227     {
9228       if (Expression::traverse(&this->end_, traverse) == TRAVERSE_EXIT)
9229         return TRAVERSE_EXIT;
9230     }
9231   return TRAVERSE_CONTINUE;
9232 }
9233
9234 // Return the type of a string index.
9235
9236 Type*
9237 String_index_expression::do_type()
9238 {
9239   if (this->end_ == NULL)
9240     return Type::lookup_integer_type("uint8");
9241   else
9242     return Type::make_string_type();
9243 }
9244
9245 // Determine the type of a string index.
9246
9247 void
9248 String_index_expression::do_determine_type(const Type_context*)
9249 {
9250   this->string_->determine_type_no_context();
9251   Type_context subcontext(NULL, true);
9252   this->start_->determine_type(&subcontext);
9253   if (this->end_ != NULL)
9254     this->end_->determine_type(&subcontext);
9255 }
9256
9257 // Check types of a string index.
9258
9259 void
9260 String_index_expression::do_check_types(Gogo*)
9261 {
9262   if (this->start_->type()->integer_type() == NULL)
9263     this->report_error(_("index must be integer"));
9264   if (this->end_ != NULL
9265       && this->end_->type()->integer_type() == NULL
9266       && !this->end_->is_nil_expression())
9267     this->report_error(_("slice end must be integer"));
9268
9269   std::string sval;
9270   bool sval_valid = this->string_->string_constant_value(&sval);
9271
9272   mpz_t ival;
9273   mpz_init(ival);
9274   Type* dummy;
9275   if (this->start_->integer_constant_value(true, ival, &dummy))
9276     {
9277       if (mpz_sgn(ival) < 0
9278           || (sval_valid && mpz_cmp_ui(ival, sval.length()) >= 0))
9279         {
9280           error_at(this->start_->location(), "string index out of bounds");
9281           this->set_is_error();
9282         }
9283     }
9284   if (this->end_ != NULL && !this->end_->is_nil_expression())
9285     {
9286       if (this->end_->integer_constant_value(true, ival, &dummy))
9287         {
9288           if (mpz_sgn(ival) < 0
9289               || (sval_valid && mpz_cmp_ui(ival, sval.length()) > 0))
9290             {
9291               error_at(this->end_->location(), "string index out of bounds");
9292               this->set_is_error();
9293             }
9294         }
9295     }
9296   mpz_clear(ival);
9297 }
9298
9299 // Get a tree for a string index.
9300
9301 tree
9302 String_index_expression::do_get_tree(Translate_context* context)
9303 {
9304   source_location loc = this->location();
9305
9306   tree string_tree = this->string_->get_tree(context);
9307   if (string_tree == error_mark_node)
9308     return error_mark_node;
9309
9310   if (this->string_->type()->points_to() != NULL)
9311     string_tree = build_fold_indirect_ref(string_tree);
9312   if (!DECL_P(string_tree))
9313     string_tree = save_expr(string_tree);
9314   tree string_type = TREE_TYPE(string_tree);
9315
9316   tree length_tree = String_type::length_tree(context->gogo(), string_tree);
9317   length_tree = save_expr(length_tree);
9318   tree length_type = TREE_TYPE(length_tree);
9319
9320   tree bad_index = boolean_false_node;
9321
9322   tree start_tree = this->start_->get_tree(context);
9323   if (start_tree == error_mark_node)
9324     return error_mark_node;
9325   if (!DECL_P(start_tree))
9326     start_tree = save_expr(start_tree);
9327   if (!INTEGRAL_TYPE_P(TREE_TYPE(start_tree)))
9328     start_tree = convert_to_integer(length_type, start_tree);
9329
9330   bad_index = Expression::check_bounds(start_tree, length_type, bad_index,
9331                                        loc);
9332
9333   start_tree = fold_convert_loc(loc, length_type, start_tree);
9334
9335   int code = (this->end_ == NULL
9336               ? RUNTIME_ERROR_STRING_INDEX_OUT_OF_BOUNDS
9337               : RUNTIME_ERROR_STRING_SLICE_OUT_OF_BOUNDS);
9338   tree crash = Gogo::runtime_error(code, loc);
9339
9340   if (this->end_ == NULL)
9341     {
9342       bad_index = fold_build2_loc(loc, TRUTH_OR_EXPR, boolean_type_node,
9343                                   bad_index,
9344                                   fold_build2_loc(loc, GE_EXPR,
9345                                                   boolean_type_node,
9346                                                   start_tree, length_tree));
9347
9348       tree bytes_tree = String_type::bytes_tree(context->gogo(), string_tree);
9349       tree ptr = fold_build2_loc(loc, POINTER_PLUS_EXPR, TREE_TYPE(bytes_tree),
9350                                  bytes_tree,
9351                                  fold_convert_loc(loc, sizetype, start_tree));
9352       tree index = build_fold_indirect_ref_loc(loc, ptr);
9353
9354       return build2(COMPOUND_EXPR, TREE_TYPE(index),
9355                     build3(COND_EXPR, void_type_node,
9356                            bad_index, crash, NULL_TREE),
9357                     index);
9358     }
9359   else
9360     {
9361       tree end_tree;
9362       if (this->end_->is_nil_expression())
9363         end_tree = build_int_cst(length_type, -1);
9364       else
9365         {
9366           end_tree = this->end_->get_tree(context);
9367           if (end_tree == error_mark_node)
9368             return error_mark_node;
9369           if (!DECL_P(end_tree))
9370             end_tree = save_expr(end_tree);
9371           if (!INTEGRAL_TYPE_P(TREE_TYPE(end_tree)))
9372             end_tree = convert_to_integer(length_type, end_tree);
9373
9374           bad_index = Expression::check_bounds(end_tree, length_type,
9375                                                bad_index, loc);
9376
9377           end_tree = fold_convert_loc(loc, length_type, end_tree);
9378         }
9379
9380       static tree strslice_fndecl;
9381       tree ret = Gogo::call_builtin(&strslice_fndecl,
9382                                     loc,
9383                                     "__go_string_slice",
9384                                     3,
9385                                     string_type,
9386                                     string_type,
9387                                     string_tree,
9388                                     length_type,
9389                                     start_tree,
9390                                     length_type,
9391                                     end_tree);
9392       // This will panic if the bounds are out of range for the
9393       // string.
9394       TREE_NOTHROW(strslice_fndecl) = 0;
9395
9396       if (bad_index == boolean_false_node)
9397         return ret;
9398       else
9399         return build2(COMPOUND_EXPR, TREE_TYPE(ret),
9400                       build3(COND_EXPR, void_type_node,
9401                              bad_index, crash, NULL_TREE),
9402                       ret);
9403     }
9404 }
9405
9406 // Make a string index expression.  END may be NULL.
9407
9408 Expression*
9409 Expression::make_string_index(Expression* string, Expression* start,
9410                               Expression* end, source_location location)
9411 {
9412   return new String_index_expression(string, start, end, location);
9413 }
9414
9415 // Class Map_index.
9416
9417 // Get the type of the map.
9418
9419 Map_type*
9420 Map_index_expression::get_map_type() const
9421 {
9422   Map_type* mt = this->map_->type()->deref()->map_type();
9423   gcc_assert(mt != NULL);
9424   return mt;
9425 }
9426
9427 // Map index traversal.
9428
9429 int
9430 Map_index_expression::do_traverse(Traverse* traverse)
9431 {
9432   if (Expression::traverse(&this->map_, traverse) == TRAVERSE_EXIT)
9433     return TRAVERSE_EXIT;
9434   return Expression::traverse(&this->index_, traverse);
9435 }
9436
9437 // Return the type of a map index.
9438
9439 Type*
9440 Map_index_expression::do_type()
9441 {
9442   Type* type = this->get_map_type()->val_type();
9443   // If this map index is in a tuple assignment, we actually return a
9444   // pointer to the value type.  Tuple_map_assignment_statement is
9445   // responsible for handling this correctly.  We need to get the type
9446   // right in case this gets assigned to a temporary variable.
9447   if (this->is_in_tuple_assignment_)
9448     type = Type::make_pointer_type(type);
9449   return type;
9450 }
9451
9452 // Fix the type of a map index.
9453
9454 void
9455 Map_index_expression::do_determine_type(const Type_context*)
9456 {
9457   this->map_->determine_type_no_context();
9458   Type_context subcontext(this->get_map_type()->key_type(), false);
9459   this->index_->determine_type(&subcontext);
9460 }
9461
9462 // Check types of a map index.
9463
9464 void
9465 Map_index_expression::do_check_types(Gogo*)
9466 {
9467   std::string reason;
9468   if (!Type::are_assignable(this->get_map_type()->key_type(),
9469                             this->index_->type(), &reason))
9470     {
9471       if (reason.empty())
9472         this->report_error(_("incompatible type for map index"));
9473       else
9474         {
9475           error_at(this->location(), "incompatible type for map index (%s)",
9476                    reason.c_str());
9477           this->set_is_error();
9478         }
9479     }
9480 }
9481
9482 // Get a tree for a map index.
9483
9484 tree
9485 Map_index_expression::do_get_tree(Translate_context* context)
9486 {
9487   Map_type* type = this->get_map_type();
9488
9489   tree valptr = this->get_value_pointer(context, this->is_lvalue_);
9490   if (valptr == error_mark_node)
9491     return error_mark_node;
9492   valptr = save_expr(valptr);
9493
9494   tree val_type_tree = TREE_TYPE(TREE_TYPE(valptr));
9495
9496   if (this->is_lvalue_)
9497     return build_fold_indirect_ref(valptr);
9498   else if (this->is_in_tuple_assignment_)
9499     {
9500       // Tuple_map_assignment_statement is responsible for using this
9501       // appropriately.
9502       return valptr;
9503     }
9504   else
9505     {
9506       return fold_build3(COND_EXPR, val_type_tree,
9507                          fold_build2(EQ_EXPR, boolean_type_node, valptr,
9508                                      fold_convert(TREE_TYPE(valptr),
9509                                                   null_pointer_node)),
9510                          type->val_type()->get_init_tree(context->gogo(),
9511                                                          false),
9512                          build_fold_indirect_ref(valptr));
9513     }
9514 }
9515
9516 // Get a tree for the map index.  This returns a tree which evaluates
9517 // to a pointer to a value.  The pointer will be NULL if the key is
9518 // not in the map.
9519
9520 tree
9521 Map_index_expression::get_value_pointer(Translate_context* context,
9522                                         bool insert)
9523 {
9524   Map_type* type = this->get_map_type();
9525
9526   tree map_tree = this->map_->get_tree(context);
9527   tree index_tree = this->index_->get_tree(context);
9528   index_tree = Expression::convert_for_assignment(context, type->key_type(),
9529                                                   this->index_->type(),
9530                                                   index_tree,
9531                                                   this->location());
9532   if (map_tree == error_mark_node || index_tree == error_mark_node)
9533     return error_mark_node;
9534
9535   if (this->map_->type()->points_to() != NULL)
9536     map_tree = build_fold_indirect_ref(map_tree);
9537
9538   // We need to pass in a pointer to the key, so stuff it into a
9539   // variable.
9540   tree tmp = create_tmp_var(TREE_TYPE(index_tree), get_name(index_tree));
9541   DECL_IGNORED_P(tmp) = 0;
9542   DECL_INITIAL(tmp) = index_tree;
9543   tree make_tmp = build1(DECL_EXPR, void_type_node, tmp);
9544   tree tmpref = fold_convert(const_ptr_type_node, build_fold_addr_expr(tmp));
9545   TREE_ADDRESSABLE(tmp) = 1;
9546
9547   static tree map_index_fndecl;
9548   tree call = Gogo::call_builtin(&map_index_fndecl,
9549                                  this->location(),
9550                                  "__go_map_index",
9551                                  3,
9552                                  const_ptr_type_node,
9553                                  TREE_TYPE(map_tree),
9554                                  map_tree,
9555                                  const_ptr_type_node,
9556                                  tmpref,
9557                                  boolean_type_node,
9558                                  (insert
9559                                   ? boolean_true_node
9560                                   : boolean_false_node));
9561   // This can panic on a map of interface type if the interface holds
9562   // an uncomparable or unhashable type.
9563   TREE_NOTHROW(map_index_fndecl) = 0;
9564
9565   tree val_type_tree = type->val_type()->get_tree(context->gogo());
9566   if (val_type_tree == error_mark_node)
9567     return error_mark_node;
9568   tree ptr_val_type_tree = build_pointer_type(val_type_tree);
9569
9570   return build2(COMPOUND_EXPR, ptr_val_type_tree,
9571                 make_tmp,
9572                 fold_convert(ptr_val_type_tree, call));
9573 }
9574
9575 // Make a map index expression.
9576
9577 Map_index_expression*
9578 Expression::make_map_index(Expression* map, Expression* index,
9579                            source_location location)
9580 {
9581   return new Map_index_expression(map, index, location);
9582 }
9583
9584 // Class Field_reference_expression.
9585
9586 // Return the type of a field reference.
9587
9588 Type*
9589 Field_reference_expression::do_type()
9590 {
9591   Struct_type* struct_type = this->expr_->type()->struct_type();
9592   gcc_assert(struct_type != NULL);
9593   return struct_type->field(this->field_index_)->type();
9594 }
9595
9596 // Check the types for a field reference.
9597
9598 void
9599 Field_reference_expression::do_check_types(Gogo*)
9600 {
9601   Struct_type* struct_type = this->expr_->type()->struct_type();
9602   gcc_assert(struct_type != NULL);
9603   gcc_assert(struct_type->field(this->field_index_) != NULL);
9604 }
9605
9606 // Get a tree for a field reference.
9607
9608 tree
9609 Field_reference_expression::do_get_tree(Translate_context* context)
9610 {
9611   tree struct_tree = this->expr_->get_tree(context);
9612   if (struct_tree == error_mark_node
9613       || TREE_TYPE(struct_tree) == error_mark_node)
9614     return error_mark_node;
9615   gcc_assert(TREE_CODE(TREE_TYPE(struct_tree)) == RECORD_TYPE);
9616   tree field = TYPE_FIELDS(TREE_TYPE(struct_tree));
9617   gcc_assert(field != NULL_TREE);
9618   for (unsigned int i = this->field_index_; i > 0; --i)
9619     {
9620       field = DECL_CHAIN(field);
9621       gcc_assert(field != NULL_TREE);
9622     }
9623   return build3(COMPONENT_REF, TREE_TYPE(field), struct_tree, field,
9624                 NULL_TREE);
9625 }
9626
9627 // Make a reference to a qualified identifier in an expression.
9628
9629 Field_reference_expression*
9630 Expression::make_field_reference(Expression* expr, unsigned int field_index,
9631                                  source_location location)
9632 {
9633   return new Field_reference_expression(expr, field_index, location);
9634 }
9635
9636 // Class Interface_field_reference_expression.
9637
9638 // Return a tree for the pointer to the function to call.
9639
9640 tree
9641 Interface_field_reference_expression::get_function_tree(Translate_context*,
9642                                                         tree expr)
9643 {
9644   if (this->expr_->type()->points_to() != NULL)
9645     expr = build_fold_indirect_ref(expr);
9646
9647   tree expr_type = TREE_TYPE(expr);
9648   gcc_assert(TREE_CODE(expr_type) == RECORD_TYPE);
9649
9650   tree field = TYPE_FIELDS(expr_type);
9651   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__methods") == 0);
9652
9653   tree table = build3(COMPONENT_REF, TREE_TYPE(field), expr, field, NULL_TREE);
9654   gcc_assert(POINTER_TYPE_P(TREE_TYPE(table)));
9655
9656   table = build_fold_indirect_ref(table);
9657   gcc_assert(TREE_CODE(TREE_TYPE(table)) == RECORD_TYPE);
9658
9659   std::string name = Gogo::unpack_hidden_name(this->name_);
9660   for (field = DECL_CHAIN(TYPE_FIELDS(TREE_TYPE(table)));
9661        field != NULL_TREE;
9662        field = DECL_CHAIN(field))
9663     {
9664       if (name == IDENTIFIER_POINTER(DECL_NAME(field)))
9665         break;
9666     }
9667   gcc_assert(field != NULL_TREE);
9668
9669   return build3(COMPONENT_REF, TREE_TYPE(field), table, field, NULL_TREE);
9670 }
9671
9672 // Return a tree for the first argument to pass to the interface
9673 // function.
9674
9675 tree
9676 Interface_field_reference_expression::get_underlying_object_tree(
9677     Translate_context*,
9678     tree expr)
9679 {
9680   if (this->expr_->type()->points_to() != NULL)
9681     expr = build_fold_indirect_ref(expr);
9682
9683   tree expr_type = TREE_TYPE(expr);
9684   gcc_assert(TREE_CODE(expr_type) == RECORD_TYPE);
9685
9686   tree field = DECL_CHAIN(TYPE_FIELDS(expr_type));
9687   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__object") == 0);
9688
9689   return build3(COMPONENT_REF, TREE_TYPE(field), expr, field, NULL_TREE);
9690 }
9691
9692 // Traversal.
9693
9694 int
9695 Interface_field_reference_expression::do_traverse(Traverse* traverse)
9696 {
9697   return Expression::traverse(&this->expr_, traverse);
9698 }
9699
9700 // Return the type of an interface field reference.
9701
9702 Type*
9703 Interface_field_reference_expression::do_type()
9704 {
9705   Type* expr_type = this->expr_->type();
9706
9707   Type* points_to = expr_type->points_to();
9708   if (points_to != NULL)
9709     expr_type = points_to;
9710
9711   Interface_type* interface_type = expr_type->interface_type();
9712   if (interface_type == NULL)
9713     return Type::make_error_type();
9714
9715   const Typed_identifier* method = interface_type->find_method(this->name_);
9716   if (method == NULL)
9717     return Type::make_error_type();
9718
9719   return method->type();
9720 }
9721
9722 // Determine types.
9723
9724 void
9725 Interface_field_reference_expression::do_determine_type(const Type_context*)
9726 {
9727   this->expr_->determine_type_no_context();
9728 }
9729
9730 // Check the types for an interface field reference.
9731
9732 void
9733 Interface_field_reference_expression::do_check_types(Gogo*)
9734 {
9735   Type* type = this->expr_->type();
9736
9737   Type* points_to = type->points_to();
9738   if (points_to != NULL)
9739     type = points_to;
9740
9741   Interface_type* interface_type = type->interface_type();
9742   if (interface_type == NULL)
9743     this->report_error(_("expected interface or pointer to interface"));
9744   else
9745     {
9746       const Typed_identifier* method =
9747         interface_type->find_method(this->name_);
9748       if (method == NULL)
9749         {
9750           error_at(this->location(), "method %qs not in interface",
9751                    Gogo::message_name(this->name_).c_str());
9752           this->set_is_error();
9753         }
9754     }
9755 }
9756
9757 // Get a tree for a reference to a field in an interface.  There is no
9758 // standard tree type representation for this: it's a function
9759 // attached to its first argument, like a Bound_method_expression.
9760 // The only places it may currently be used are in a Call_expression
9761 // or a Go_statement, which will take it apart directly.  So this has
9762 // nothing to do at present.
9763
9764 tree
9765 Interface_field_reference_expression::do_get_tree(Translate_context*)
9766 {
9767   gcc_unreachable();
9768 }
9769
9770 // Make a reference to a field in an interface.
9771
9772 Expression*
9773 Expression::make_interface_field_reference(Expression* expr,
9774                                            const std::string& field,
9775                                            source_location location)
9776 {
9777   return new Interface_field_reference_expression(expr, field, location);
9778 }
9779
9780 // A general selector.  This is a Parser_expression for LEFT.NAME.  It
9781 // is lowered after we know the type of the left hand side.
9782
9783 class Selector_expression : public Parser_expression
9784 {
9785  public:
9786   Selector_expression(Expression* left, const std::string& name,
9787                       source_location location)
9788     : Parser_expression(EXPRESSION_SELECTOR, location),
9789       left_(left), name_(name)
9790   { }
9791
9792  protected:
9793   int
9794   do_traverse(Traverse* traverse)
9795   { return Expression::traverse(&this->left_, traverse); }
9796
9797   Expression*
9798   do_lower(Gogo*, Named_object*, int);
9799
9800   Expression*
9801   do_copy()
9802   {
9803     return new Selector_expression(this->left_->copy(), this->name_,
9804                                    this->location());
9805   }
9806
9807  private:
9808   Expression*
9809   lower_method_expression(Gogo*);
9810
9811   // The expression on the left hand side.
9812   Expression* left_;
9813   // The name on the right hand side.
9814   std::string name_;
9815 };
9816
9817 // Lower a selector expression once we know the real type of the left
9818 // hand side.
9819
9820 Expression*
9821 Selector_expression::do_lower(Gogo* gogo, Named_object*, int)
9822 {
9823   Expression* left = this->left_;
9824   if (left->is_type_expression())
9825     return this->lower_method_expression(gogo);
9826   return Type::bind_field_or_method(gogo, left->type(), left, this->name_,
9827                                     this->location());
9828 }
9829
9830 // Lower a method expression T.M or (*T).M.  We turn this into a
9831 // function literal.
9832
9833 Expression*
9834 Selector_expression::lower_method_expression(Gogo* gogo)
9835 {
9836   source_location location = this->location();
9837   Type* type = this->left_->type();
9838   const std::string& name(this->name_);
9839
9840   bool is_pointer;
9841   if (type->points_to() == NULL)
9842     is_pointer = false;
9843   else
9844     {
9845       is_pointer = true;
9846       type = type->points_to();
9847     }
9848   Named_type* nt = type->named_type();
9849   if (nt == NULL)
9850     {
9851       error_at(location,
9852                ("method expression requires named type or "
9853                 "pointer to named type"));
9854       return Expression::make_error(location);
9855     }
9856
9857   bool is_ambiguous;
9858   Method* method = nt->method_function(name, &is_ambiguous);
9859   if (method == NULL)
9860     {
9861       if (!is_ambiguous)
9862         error_at(location, "type %<%s%> has no method %<%s%>",
9863                  nt->message_name().c_str(),
9864                  Gogo::message_name(name).c_str());
9865       else
9866         error_at(location, "method %<%s%> is ambiguous in type %<%s%>",
9867                  Gogo::message_name(name).c_str(),
9868                  nt->message_name().c_str());
9869       return Expression::make_error(location);
9870     }
9871
9872   if (!is_pointer && !method->is_value_method())
9873     {
9874       error_at(location, "method requires pointer (use %<(*%s).%s)%>",
9875                nt->message_name().c_str(),
9876                Gogo::message_name(name).c_str());
9877       return Expression::make_error(location);
9878     }
9879
9880   // Build a new function type in which the receiver becomes the first
9881   // argument.
9882   Function_type* method_type = method->type();
9883   gcc_assert(method_type->is_method());
9884
9885   const char* const receiver_name = "$this";
9886   Typed_identifier_list* parameters = new Typed_identifier_list();
9887   parameters->push_back(Typed_identifier(receiver_name, this->left_->type(),
9888                                          location));
9889
9890   const Typed_identifier_list* method_parameters = method_type->parameters();
9891   if (method_parameters != NULL)
9892     {
9893       for (Typed_identifier_list::const_iterator p = method_parameters->begin();
9894            p != method_parameters->end();
9895            ++p)
9896         parameters->push_back(*p);
9897     }
9898
9899   const Typed_identifier_list* method_results = method_type->results();
9900   Typed_identifier_list* results;
9901   if (method_results == NULL)
9902     results = NULL;
9903   else
9904     {
9905       results = new Typed_identifier_list();
9906       for (Typed_identifier_list::const_iterator p = method_results->begin();
9907            p != method_results->end();
9908            ++p)
9909         results->push_back(*p);
9910     }
9911
9912   Function_type* fntype = Type::make_function_type(NULL, parameters, results,
9913                                                    location);
9914   if (method_type->is_varargs())
9915     fntype->set_is_varargs();
9916
9917   // We generate methods which always takes a pointer to the receiver
9918   // as their first argument.  If this is for a pointer type, we can
9919   // simply reuse the existing function.  We use an internal hack to
9920   // get the right type.
9921
9922   if (is_pointer)
9923     {
9924       Named_object* mno = (method->needs_stub_method()
9925                            ? method->stub_object()
9926                            : method->named_object());
9927       Expression* f = Expression::make_func_reference(mno, NULL, location);
9928       f = Expression::make_cast(fntype, f, location);
9929       Type_conversion_expression* tce =
9930         static_cast<Type_conversion_expression*>(f);
9931       tce->set_may_convert_function_types();
9932       return f;
9933     }
9934
9935   Named_object* no = gogo->start_function(Gogo::thunk_name(), fntype, false,
9936                                           location);
9937
9938   Named_object* vno = gogo->lookup(receiver_name, NULL);
9939   gcc_assert(vno != NULL);
9940   Expression* ve = Expression::make_var_reference(vno, location);
9941   Expression* bm = Type::bind_field_or_method(gogo, nt, ve, name, location);
9942   gcc_assert(bm != NULL && !bm->is_error_expression());
9943
9944   Expression_list* args;
9945   if (method_parameters == NULL)
9946     args = NULL;
9947   else
9948     {
9949       args = new Expression_list();
9950       for (Typed_identifier_list::const_iterator p = method_parameters->begin();
9951            p != method_parameters->end();
9952            ++p)
9953         {
9954           vno = gogo->lookup(p->name(), NULL);
9955           gcc_assert(vno != NULL);
9956           args->push_back(Expression::make_var_reference(vno, location));
9957         }
9958     }
9959
9960   Call_expression* call = Expression::make_call(bm, args,
9961                                                 method_type->is_varargs(),
9962                                                 location);
9963
9964   size_t count = call->result_count();
9965   Statement* s;
9966   if (count == 0)
9967     s = Statement::make_statement(call);
9968   else
9969     {
9970       Expression_list* retvals = new Expression_list();
9971       if (count <= 1)
9972         retvals->push_back(call);
9973       else
9974         {
9975           for (size_t i = 0; i < count; ++i)
9976             retvals->push_back(Expression::make_call_result(call, i));
9977         }
9978       s = Statement::make_return_statement(no->func_value()->type()->results(),
9979                                            retvals, location);
9980     }
9981   gogo->add_statement(s);
9982
9983   gogo->finish_function(location);
9984
9985   return Expression::make_func_reference(no, NULL, location);
9986 }
9987
9988 // Make a selector expression.
9989
9990 Expression*
9991 Expression::make_selector(Expression* left, const std::string& name,
9992                           source_location location)
9993 {
9994   return new Selector_expression(left, name, location);
9995 }
9996
9997 // Implement the builtin function new.
9998
9999 class Allocation_expression : public Expression
10000 {
10001  public:
10002   Allocation_expression(Type* type, source_location location)
10003     : Expression(EXPRESSION_ALLOCATION, location),
10004       type_(type)
10005   { }
10006
10007  protected:
10008   int
10009   do_traverse(Traverse* traverse)
10010   { return Type::traverse(this->type_, traverse); }
10011
10012   Type*
10013   do_type()
10014   { return Type::make_pointer_type(this->type_); }
10015
10016   void
10017   do_determine_type(const Type_context*)
10018   { }
10019
10020   void
10021   do_check_types(Gogo*);
10022
10023   Expression*
10024   do_copy()
10025   { return new Allocation_expression(this->type_, this->location()); }
10026
10027   tree
10028   do_get_tree(Translate_context*);
10029
10030  private:
10031   // The type we are allocating.
10032   Type* type_;
10033 };
10034
10035 // Check the type of an allocation expression.
10036
10037 void
10038 Allocation_expression::do_check_types(Gogo*)
10039 {
10040   if (this->type_->function_type() != NULL)
10041     this->report_error(_("invalid new of function type"));
10042 }
10043
10044 // Return a tree for an allocation expression.
10045
10046 tree
10047 Allocation_expression::do_get_tree(Translate_context* context)
10048 {
10049   tree type_tree = this->type_->get_tree(context->gogo());
10050   tree size_tree = TYPE_SIZE_UNIT(type_tree);
10051   tree space = context->gogo()->allocate_memory(this->type_, size_tree,
10052                                                 this->location());
10053   return fold_convert(build_pointer_type(type_tree), space);
10054 }
10055
10056 // Make an allocation expression.
10057
10058 Expression*
10059 Expression::make_allocation(Type* type, source_location location)
10060 {
10061   return new Allocation_expression(type, location);
10062 }
10063
10064 // Implement the builtin function make.
10065
10066 class Make_expression : public Expression
10067 {
10068  public:
10069   Make_expression(Type* type, Expression_list* args, source_location location)
10070     : Expression(EXPRESSION_MAKE, location),
10071       type_(type), args_(args)
10072   { }
10073
10074  protected:
10075   int
10076   do_traverse(Traverse* traverse);
10077
10078   Type*
10079   do_type()
10080   { return this->type_; }
10081
10082   void
10083   do_determine_type(const Type_context*);
10084
10085   void
10086   do_check_types(Gogo*);
10087
10088   Expression*
10089   do_copy()
10090   {
10091     return new Make_expression(this->type_, this->args_->copy(),
10092                                this->location());
10093   }
10094
10095   tree
10096   do_get_tree(Translate_context*);
10097
10098  private:
10099   // The type we are making.
10100   Type* type_;
10101   // The arguments to pass to the make routine.
10102   Expression_list* args_;
10103 };
10104
10105 // Traversal.
10106
10107 int
10108 Make_expression::do_traverse(Traverse* traverse)
10109 {
10110   if (this->args_ != NULL
10111       && this->args_->traverse(traverse) == TRAVERSE_EXIT)
10112     return TRAVERSE_EXIT;
10113   if (Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
10114     return TRAVERSE_EXIT;
10115   return TRAVERSE_CONTINUE;
10116 }
10117
10118 // Set types of arguments.
10119
10120 void
10121 Make_expression::do_determine_type(const Type_context*)
10122 {
10123   if (this->args_ != NULL)
10124     {
10125       Type_context context(Type::lookup_integer_type("int"), false);
10126       for (Expression_list::const_iterator pe = this->args_->begin();
10127            pe != this->args_->end();
10128            ++pe)
10129         (*pe)->determine_type(&context);
10130     }
10131 }
10132
10133 // Check types for a make expression.
10134
10135 void
10136 Make_expression::do_check_types(Gogo*)
10137 {
10138   if (this->type_->channel_type() == NULL
10139       && this->type_->map_type() == NULL
10140       && (this->type_->array_type() == NULL
10141           || this->type_->array_type()->length() != NULL))
10142     this->report_error(_("invalid type for make function"));
10143   else if (!this->type_->check_make_expression(this->args_, this->location()))
10144     this->set_is_error();
10145 }
10146
10147 // Return a tree for a make expression.
10148
10149 tree
10150 Make_expression::do_get_tree(Translate_context* context)
10151 {
10152   return this->type_->make_expression_tree(context, this->args_,
10153                                            this->location());
10154 }
10155
10156 // Make a make expression.
10157
10158 Expression*
10159 Expression::make_make(Type* type, Expression_list* args,
10160                       source_location location)
10161 {
10162   return new Make_expression(type, args, location);
10163 }
10164
10165 // Construct a struct.
10166
10167 class Struct_construction_expression : public Expression
10168 {
10169  public:
10170   Struct_construction_expression(Type* type, Expression_list* vals,
10171                                  source_location location)
10172     : Expression(EXPRESSION_STRUCT_CONSTRUCTION, location),
10173       type_(type), vals_(vals)
10174   { }
10175
10176   // Return whether this is a constant initializer.
10177   bool
10178   is_constant_struct() const;
10179
10180  protected:
10181   int
10182   do_traverse(Traverse* traverse);
10183
10184   Type*
10185   do_type()
10186   { return this->type_; }
10187
10188   void
10189   do_determine_type(const Type_context*);
10190
10191   void
10192   do_check_types(Gogo*);
10193
10194   Expression*
10195   do_copy()
10196   {
10197     return new Struct_construction_expression(this->type_, this->vals_->copy(),
10198                                               this->location());
10199   }
10200
10201   bool
10202   do_is_addressable() const
10203   { return true; }
10204
10205   tree
10206   do_get_tree(Translate_context*);
10207
10208   void
10209   do_export(Export*) const;
10210
10211  private:
10212   // The type of the struct to construct.
10213   Type* type_;
10214   // The list of values, in order of the fields in the struct.  A NULL
10215   // entry means that the field should be zero-initialized.
10216   Expression_list* vals_;
10217 };
10218
10219 // Traversal.
10220
10221 int
10222 Struct_construction_expression::do_traverse(Traverse* traverse)
10223 {
10224   if (this->vals_ != NULL
10225       && this->vals_->traverse(traverse) == TRAVERSE_EXIT)
10226     return TRAVERSE_EXIT;
10227   if (Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
10228     return TRAVERSE_EXIT;
10229   return TRAVERSE_CONTINUE;
10230 }
10231
10232 // Return whether this is a constant initializer.
10233
10234 bool
10235 Struct_construction_expression::is_constant_struct() const
10236 {
10237   if (this->vals_ == NULL)
10238     return true;
10239   for (Expression_list::const_iterator pv = this->vals_->begin();
10240        pv != this->vals_->end();
10241        ++pv)
10242     {
10243       if (*pv != NULL
10244           && !(*pv)->is_constant()
10245           && (!(*pv)->is_composite_literal()
10246               || (*pv)->is_nonconstant_composite_literal()))
10247         return false;
10248     }
10249
10250   const Struct_field_list* fields = this->type_->struct_type()->fields();
10251   for (Struct_field_list::const_iterator pf = fields->begin();
10252        pf != fields->end();
10253        ++pf)
10254     {
10255       // There are no constant constructors for interfaces.
10256       if (pf->type()->interface_type() != NULL)
10257         return false;
10258     }
10259
10260   return true;
10261 }
10262
10263 // Final type determination.
10264
10265 void
10266 Struct_construction_expression::do_determine_type(const Type_context*)
10267 {
10268   if (this->vals_ == NULL)
10269     return;
10270   const Struct_field_list* fields = this->type_->struct_type()->fields();
10271   Expression_list::const_iterator pv = this->vals_->begin();
10272   for (Struct_field_list::const_iterator pf = fields->begin();
10273        pf != fields->end();
10274        ++pf, ++pv)
10275     {
10276       if (pv == this->vals_->end())
10277         return;
10278       if (*pv != NULL)
10279         {
10280           Type_context subcontext(pf->type(), false);
10281           (*pv)->determine_type(&subcontext);
10282         }
10283     }
10284 }
10285
10286 // Check types.
10287
10288 void
10289 Struct_construction_expression::do_check_types(Gogo*)
10290 {
10291   if (this->vals_ == NULL)
10292     return;
10293
10294   Struct_type* st = this->type_->struct_type();
10295   if (this->vals_->size() > st->field_count())
10296     {
10297       this->report_error(_("too many expressions for struct"));
10298       return;
10299     }
10300
10301   const Struct_field_list* fields = st->fields();
10302   Expression_list::const_iterator pv = this->vals_->begin();
10303   int i = 0;
10304   for (Struct_field_list::const_iterator pf = fields->begin();
10305        pf != fields->end();
10306        ++pf, ++pv, ++i)
10307     {
10308       if (pv == this->vals_->end())
10309         {
10310           this->report_error(_("too few expressions for struct"));
10311           break;
10312         }
10313
10314       if (*pv == NULL)
10315         continue;
10316
10317       std::string reason;
10318       if (!Type::are_assignable(pf->type(), (*pv)->type(), &reason))
10319         {
10320           if (reason.empty())
10321             error_at((*pv)->location(),
10322                      "incompatible type for field %d in struct construction",
10323                      i + 1);
10324           else
10325             error_at((*pv)->location(),
10326                      ("incompatible type for field %d in "
10327                       "struct construction (%s)"),
10328                      i + 1, reason.c_str());
10329           this->set_is_error();
10330         }
10331     }
10332   gcc_assert(pv == this->vals_->end());
10333 }
10334
10335 // Return a tree for constructing a struct.
10336
10337 tree
10338 Struct_construction_expression::do_get_tree(Translate_context* context)
10339 {
10340   Gogo* gogo = context->gogo();
10341
10342   if (this->vals_ == NULL)
10343     return this->type_->get_init_tree(gogo, false);
10344
10345   tree type_tree = this->type_->get_tree(gogo);
10346   if (type_tree == error_mark_node)
10347     return error_mark_node;
10348   gcc_assert(TREE_CODE(type_tree) == RECORD_TYPE);
10349
10350   bool is_constant = true;
10351   const Struct_field_list* fields = this->type_->struct_type()->fields();
10352   VEC(constructor_elt,gc)* elts = VEC_alloc(constructor_elt, gc,
10353                                             fields->size());
10354   Struct_field_list::const_iterator pf = fields->begin();
10355   Expression_list::const_iterator pv = this->vals_->begin();
10356   for (tree field = TYPE_FIELDS(type_tree);
10357        field != NULL_TREE;
10358        field = DECL_CHAIN(field), ++pf)
10359     {
10360       gcc_assert(pf != fields->end());
10361
10362       tree val;
10363       if (pv == this->vals_->end())
10364         val = pf->type()->get_init_tree(gogo, false);
10365       else if (*pv == NULL)
10366         {
10367           val = pf->type()->get_init_tree(gogo, false);
10368           ++pv;
10369         }
10370       else
10371         {
10372           val = Expression::convert_for_assignment(context, pf->type(),
10373                                                    (*pv)->type(),
10374                                                    (*pv)->get_tree(context),
10375                                                    this->location());
10376           ++pv;
10377         }
10378
10379       if (val == error_mark_node || TREE_TYPE(val) == error_mark_node)
10380         return error_mark_node;
10381
10382       constructor_elt* elt = VEC_quick_push(constructor_elt, elts, NULL);
10383       elt->index = field;
10384       elt->value = val;
10385       if (!TREE_CONSTANT(val))
10386         is_constant = false;
10387     }
10388   gcc_assert(pf == fields->end());
10389
10390   tree ret = build_constructor(type_tree, elts);
10391   if (is_constant)
10392     TREE_CONSTANT(ret) = 1;
10393   return ret;
10394 }
10395
10396 // Export a struct construction.
10397
10398 void
10399 Struct_construction_expression::do_export(Export* exp) const
10400 {
10401   exp->write_c_string("convert(");
10402   exp->write_type(this->type_);
10403   for (Expression_list::const_iterator pv = this->vals_->begin();
10404        pv != this->vals_->end();
10405        ++pv)
10406     {
10407       exp->write_c_string(", ");
10408       if (*pv != NULL)
10409         (*pv)->export_expression(exp);
10410     }
10411   exp->write_c_string(")");
10412 }
10413
10414 // Make a struct composite literal.  This used by the thunk code.
10415
10416 Expression*
10417 Expression::make_struct_composite_literal(Type* type, Expression_list* vals,
10418                                           source_location location)
10419 {
10420   gcc_assert(type->struct_type() != NULL);
10421   return new Struct_construction_expression(type, vals, location);
10422 }
10423
10424 // Construct an array.  This class is not used directly; instead we
10425 // use the child classes, Fixed_array_construction_expression and
10426 // Open_array_construction_expression.
10427
10428 class Array_construction_expression : public Expression
10429 {
10430  protected:
10431   Array_construction_expression(Expression_classification classification,
10432                                 Type* type, Expression_list* vals,
10433                                 source_location location)
10434     : Expression(classification, location),
10435       type_(type), vals_(vals)
10436   { }
10437
10438  public:
10439   // Return whether this is a constant initializer.
10440   bool
10441   is_constant_array() const;
10442
10443   // Return the number of elements.
10444   size_t
10445   element_count() const
10446   { return this->vals_ == NULL ? 0 : this->vals_->size(); }
10447
10448 protected:
10449   int
10450   do_traverse(Traverse* traverse);
10451
10452   Type*
10453   do_type()
10454   { return this->type_; }
10455
10456   void
10457   do_determine_type(const Type_context*);
10458
10459   void
10460   do_check_types(Gogo*);
10461
10462   bool
10463   do_is_addressable() const
10464   { return true; }
10465
10466   void
10467   do_export(Export*) const;
10468
10469   // The list of values.
10470   Expression_list*
10471   vals()
10472   { return this->vals_; }
10473
10474   // Get a constructor tree for the array values.
10475   tree
10476   get_constructor_tree(Translate_context* context, tree type_tree);
10477
10478  private:
10479   // The type of the array to construct.
10480   Type* type_;
10481   // The list of values.
10482   Expression_list* vals_;
10483 };
10484
10485 // Traversal.
10486
10487 int
10488 Array_construction_expression::do_traverse(Traverse* traverse)
10489 {
10490   if (this->vals_ != NULL
10491       && this->vals_->traverse(traverse) == TRAVERSE_EXIT)
10492     return TRAVERSE_EXIT;
10493   if (Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
10494     return TRAVERSE_EXIT;
10495   return TRAVERSE_CONTINUE;
10496 }
10497
10498 // Return whether this is a constant initializer.
10499
10500 bool
10501 Array_construction_expression::is_constant_array() const
10502 {
10503   if (this->vals_ == NULL)
10504     return true;
10505
10506   // There are no constant constructors for interfaces.
10507   if (this->type_->array_type()->element_type()->interface_type() != NULL)
10508     return false;
10509
10510   for (Expression_list::const_iterator pv = this->vals_->begin();
10511        pv != this->vals_->end();
10512        ++pv)
10513     {
10514       if (*pv != NULL
10515           && !(*pv)->is_constant()
10516           && (!(*pv)->is_composite_literal()
10517               || (*pv)->is_nonconstant_composite_literal()))
10518         return false;
10519     }
10520   return true;
10521 }
10522
10523 // Final type determination.
10524
10525 void
10526 Array_construction_expression::do_determine_type(const Type_context*)
10527 {
10528   if (this->vals_ == NULL)
10529     return;
10530   Type_context subcontext(this->type_->array_type()->element_type(), false);
10531   for (Expression_list::const_iterator pv = this->vals_->begin();
10532        pv != this->vals_->end();
10533        ++pv)
10534     {
10535       if (*pv != NULL)
10536         (*pv)->determine_type(&subcontext);
10537     }
10538 }
10539
10540 // Check types.
10541
10542 void
10543 Array_construction_expression::do_check_types(Gogo*)
10544 {
10545   if (this->vals_ == NULL)
10546     return;
10547
10548   Array_type* at = this->type_->array_type();
10549   int i = 0;
10550   Type* element_type = at->element_type();
10551   for (Expression_list::const_iterator pv = this->vals_->begin();
10552        pv != this->vals_->end();
10553        ++pv, ++i)
10554     {
10555       if (*pv != NULL
10556           && !Type::are_assignable(element_type, (*pv)->type(), NULL))
10557         {
10558           error_at((*pv)->location(),
10559                    "incompatible type for element %d in composite literal",
10560                    i + 1);
10561           this->set_is_error();
10562         }
10563     }
10564
10565   Expression* length = at->length();
10566   if (length != NULL)
10567     {
10568       mpz_t val;
10569       mpz_init(val);
10570       Type* type;
10571       if (at->length()->integer_constant_value(true, val, &type))
10572         {
10573           if (this->vals_->size() > mpz_get_ui(val))
10574             this->report_error(_("too many elements in composite literal"));
10575         }
10576       mpz_clear(val);
10577     }
10578 }
10579
10580 // Get a constructor tree for the array values.
10581
10582 tree
10583 Array_construction_expression::get_constructor_tree(Translate_context* context,
10584                                                     tree type_tree)
10585 {
10586   VEC(constructor_elt,gc)* values = VEC_alloc(constructor_elt, gc,
10587                                               (this->vals_ == NULL
10588                                                ? 0
10589                                                : this->vals_->size()));
10590   Type* element_type = this->type_->array_type()->element_type();
10591   bool is_constant = true;
10592   if (this->vals_ != NULL)
10593     {
10594       size_t i = 0;
10595       for (Expression_list::const_iterator pv = this->vals_->begin();
10596            pv != this->vals_->end();
10597            ++pv, ++i)
10598         {
10599           constructor_elt* elt = VEC_quick_push(constructor_elt, values, NULL);
10600           elt->index = size_int(i);
10601           if (*pv == NULL)
10602             elt->value = element_type->get_init_tree(context->gogo(), false);
10603           else
10604             {
10605               tree value_tree = (*pv)->get_tree(context);
10606               elt->value = Expression::convert_for_assignment(context,
10607                                                               element_type,
10608                                                               (*pv)->type(),
10609                                                               value_tree,
10610                                                               this->location());
10611             }
10612           if (elt->value == error_mark_node)
10613             return error_mark_node;
10614           if (!TREE_CONSTANT(elt->value))
10615             is_constant = false;
10616         }
10617     }
10618
10619   tree ret = build_constructor(type_tree, values);
10620   if (is_constant)
10621     TREE_CONSTANT(ret) = 1;
10622   return ret;
10623 }
10624
10625 // Export an array construction.
10626
10627 void
10628 Array_construction_expression::do_export(Export* exp) const
10629 {
10630   exp->write_c_string("convert(");
10631   exp->write_type(this->type_);
10632   if (this->vals_ != NULL)
10633     {
10634       for (Expression_list::const_iterator pv = this->vals_->begin();
10635            pv != this->vals_->end();
10636            ++pv)
10637         {
10638           exp->write_c_string(", ");
10639           if (*pv != NULL)
10640             (*pv)->export_expression(exp);
10641         }
10642     }
10643   exp->write_c_string(")");
10644 }
10645
10646 // Construct a fixed array.
10647
10648 class Fixed_array_construction_expression :
10649   public Array_construction_expression
10650 {
10651  public:
10652   Fixed_array_construction_expression(Type* type, Expression_list* vals,
10653                                       source_location location)
10654     : Array_construction_expression(EXPRESSION_FIXED_ARRAY_CONSTRUCTION,
10655                                     type, vals, location)
10656   {
10657     gcc_assert(type->array_type() != NULL
10658                && type->array_type()->length() != NULL);
10659   }
10660
10661  protected:
10662   Expression*
10663   do_copy()
10664   {
10665     return new Fixed_array_construction_expression(this->type(),
10666                                                    (this->vals() == NULL
10667                                                     ? NULL
10668                                                     : this->vals()->copy()),
10669                                                    this->location());
10670   }
10671
10672   tree
10673   do_get_tree(Translate_context*);
10674 };
10675
10676 // Return a tree for constructing a fixed array.
10677
10678 tree
10679 Fixed_array_construction_expression::do_get_tree(Translate_context* context)
10680 {
10681   return this->get_constructor_tree(context,
10682                                     this->type()->get_tree(context->gogo()));
10683 }
10684
10685 // Construct an open array.
10686
10687 class Open_array_construction_expression : public Array_construction_expression
10688 {
10689  public:
10690   Open_array_construction_expression(Type* type, Expression_list* vals,
10691                                      source_location location)
10692     : Array_construction_expression(EXPRESSION_OPEN_ARRAY_CONSTRUCTION,
10693                                     type, vals, location)
10694   {
10695     gcc_assert(type->array_type() != NULL
10696                && type->array_type()->length() == NULL);
10697   }
10698
10699  protected:
10700   // Note that taking the address of an open array literal is invalid.
10701
10702   Expression*
10703   do_copy()
10704   {
10705     return new Open_array_construction_expression(this->type(),
10706                                                   (this->vals() == NULL
10707                                                    ? NULL
10708                                                    : this->vals()->copy()),
10709                                                   this->location());
10710   }
10711
10712   tree
10713   do_get_tree(Translate_context*);
10714 };
10715
10716 // Return a tree for constructing an open array.
10717
10718 tree
10719 Open_array_construction_expression::do_get_tree(Translate_context* context)
10720 {
10721   Type* element_type = this->type()->array_type()->element_type();
10722   tree element_type_tree = element_type->get_tree(context->gogo());
10723   tree values;
10724   tree length_tree;
10725   if (this->vals() == NULL || this->vals()->empty())
10726     {
10727       // We need to create a unique value.
10728       tree max = size_int(0);
10729       tree constructor_type = build_array_type(element_type_tree,
10730                                                build_index_type(max));
10731       if (constructor_type == error_mark_node)
10732         return error_mark_node;
10733       VEC(constructor_elt,gc)* vec = VEC_alloc(constructor_elt, gc, 1);
10734       constructor_elt* elt = VEC_quick_push(constructor_elt, vec, NULL);
10735       elt->index = size_int(0);
10736       elt->value = element_type->get_init_tree(context->gogo(), false);
10737       values = build_constructor(constructor_type, vec);
10738       if (TREE_CONSTANT(elt->value))
10739         TREE_CONSTANT(values) = 1;
10740       length_tree = size_int(0);
10741     }
10742   else
10743     {
10744       tree max = size_int(this->vals()->size() - 1);
10745       tree constructor_type = build_array_type(element_type_tree,
10746                                                build_index_type(max));
10747       if (constructor_type == error_mark_node)
10748         return error_mark_node;
10749       values = this->get_constructor_tree(context, constructor_type);
10750       length_tree = size_int(this->vals()->size());
10751     }
10752
10753   if (values == error_mark_node)
10754     return error_mark_node;
10755
10756   bool is_constant_initializer = TREE_CONSTANT(values);
10757   bool is_in_function = context->function() != NULL;
10758
10759   if (is_constant_initializer)
10760     {
10761       tree tmp = build_decl(this->location(), VAR_DECL,
10762                             create_tmp_var_name("C"), TREE_TYPE(values));
10763       DECL_EXTERNAL(tmp) = 0;
10764       TREE_PUBLIC(tmp) = 0;
10765       TREE_STATIC(tmp) = 1;
10766       DECL_ARTIFICIAL(tmp) = 1;
10767       if (is_in_function)
10768         {
10769           // If this is not a function, we will only initialize the
10770           // value once, so we can use this directly rather than
10771           // copying it.  In that case we can't make it read-only,
10772           // because the program is permitted to change it.
10773           TREE_READONLY(tmp) = 1;
10774           TREE_CONSTANT(tmp) = 1;
10775         }
10776       DECL_INITIAL(tmp) = values;
10777       rest_of_decl_compilation(tmp, 1, 0);
10778       values = tmp;
10779     }
10780
10781   tree space;
10782   tree set;
10783   if (!is_in_function && is_constant_initializer)
10784     {
10785       // Outside of a function, we know the initializer will only run
10786       // once.
10787       space = build_fold_addr_expr(values);
10788       set = NULL_TREE;
10789     }
10790   else
10791     {
10792       tree memsize = TYPE_SIZE_UNIT(TREE_TYPE(values));
10793       space = context->gogo()->allocate_memory(element_type, memsize,
10794                                                this->location());
10795       space = save_expr(space);
10796
10797       tree s = fold_convert(build_pointer_type(TREE_TYPE(values)), space);
10798       tree ref = build_fold_indirect_ref_loc(this->location(), s);
10799       TREE_THIS_NOTRAP(ref) = 1;
10800       set = build2(MODIFY_EXPR, void_type_node, ref, values);
10801     }
10802
10803   // Build a constructor for the open array.
10804
10805   tree type_tree = this->type()->get_tree(context->gogo());
10806   gcc_assert(TREE_CODE(type_tree) == RECORD_TYPE);
10807
10808   VEC(constructor_elt,gc)* init = VEC_alloc(constructor_elt, gc, 3);
10809
10810   constructor_elt* elt = VEC_quick_push(constructor_elt, init, NULL);
10811   tree field = TYPE_FIELDS(type_tree);
10812   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__values") == 0);
10813   elt->index = field;
10814   elt->value = fold_convert(TREE_TYPE(field), space);
10815
10816   elt = VEC_quick_push(constructor_elt, init, NULL);
10817   field = DECL_CHAIN(field);
10818   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__count") == 0);
10819   elt->index = field;
10820   elt->value = fold_convert(TREE_TYPE(field), length_tree);
10821
10822   elt = VEC_quick_push(constructor_elt, init, NULL);
10823   field = DECL_CHAIN(field);
10824   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)),"__capacity") == 0);
10825   elt->index = field;
10826   elt->value = fold_convert(TREE_TYPE(field), length_tree);
10827
10828   tree constructor = build_constructor(type_tree, init);
10829   if (!is_in_function && is_constant_initializer)
10830     TREE_CONSTANT(constructor) = 1;
10831
10832   if (set == NULL_TREE)
10833     return constructor;
10834   else
10835     return build2(COMPOUND_EXPR, type_tree, set, constructor);
10836 }
10837
10838 // Make a slice composite literal.  This is used by the type
10839 // descriptor code.
10840
10841 Expression*
10842 Expression::make_slice_composite_literal(Type* type, Expression_list* vals,
10843                                          source_location location)
10844 {
10845   gcc_assert(type->is_open_array_type());
10846   return new Open_array_construction_expression(type, vals, location);
10847 }
10848
10849 // Construct a map.
10850
10851 class Map_construction_expression : public Expression
10852 {
10853  public:
10854   Map_construction_expression(Type* type, Expression_list* vals,
10855                               source_location location)
10856     : Expression(EXPRESSION_MAP_CONSTRUCTION, location),
10857       type_(type), vals_(vals)
10858   { gcc_assert(vals == NULL || vals->size() % 2 == 0); }
10859
10860  protected:
10861   int
10862   do_traverse(Traverse* traverse);
10863
10864   Type*
10865   do_type()
10866   { return this->type_; }
10867
10868   void
10869   do_determine_type(const Type_context*);
10870
10871   void
10872   do_check_types(Gogo*);
10873
10874   Expression*
10875   do_copy()
10876   {
10877     return new Map_construction_expression(this->type_, this->vals_->copy(),
10878                                            this->location());
10879   }
10880
10881   tree
10882   do_get_tree(Translate_context*);
10883
10884   void
10885   do_export(Export*) const;
10886
10887  private:
10888   // The type of the map to construct.
10889   Type* type_;
10890   // The list of values.
10891   Expression_list* vals_;
10892 };
10893
10894 // Traversal.
10895
10896 int
10897 Map_construction_expression::do_traverse(Traverse* traverse)
10898 {
10899   if (this->vals_ != NULL
10900       && this->vals_->traverse(traverse) == TRAVERSE_EXIT)
10901     return TRAVERSE_EXIT;
10902   if (Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
10903     return TRAVERSE_EXIT;
10904   return TRAVERSE_CONTINUE;
10905 }
10906
10907 // Final type determination.
10908
10909 void
10910 Map_construction_expression::do_determine_type(const Type_context*)
10911 {
10912   if (this->vals_ == NULL)
10913     return;
10914
10915   Map_type* mt = this->type_->map_type();
10916   Type_context key_context(mt->key_type(), false);
10917   Type_context val_context(mt->val_type(), false);
10918   for (Expression_list::const_iterator pv = this->vals_->begin();
10919        pv != this->vals_->end();
10920        ++pv)
10921     {
10922       (*pv)->determine_type(&key_context);
10923       ++pv;
10924       (*pv)->determine_type(&val_context);
10925     }
10926 }
10927
10928 // Check types.
10929
10930 void
10931 Map_construction_expression::do_check_types(Gogo*)
10932 {
10933   if (this->vals_ == NULL)
10934     return;
10935
10936   Map_type* mt = this->type_->map_type();
10937   int i = 0;
10938   Type* key_type = mt->key_type();
10939   Type* val_type = mt->val_type();
10940   for (Expression_list::const_iterator pv = this->vals_->begin();
10941        pv != this->vals_->end();
10942        ++pv, ++i)
10943     {
10944       if (!Type::are_assignable(key_type, (*pv)->type(), NULL))
10945         {
10946           error_at((*pv)->location(),
10947                    "incompatible type for element %d key in map construction",
10948                    i + 1);
10949           this->set_is_error();
10950         }
10951       ++pv;
10952       if (!Type::are_assignable(val_type, (*pv)->type(), NULL))
10953         {
10954           error_at((*pv)->location(),
10955                    ("incompatible type for element %d value "
10956                     "in map construction"),
10957                    i + 1);
10958           this->set_is_error();
10959         }
10960     }
10961 }
10962
10963 // Return a tree for constructing a map.
10964
10965 tree
10966 Map_construction_expression::do_get_tree(Translate_context* context)
10967 {
10968   Gogo* gogo = context->gogo();
10969   source_location loc = this->location();
10970
10971   Map_type* mt = this->type_->map_type();
10972
10973   // Build a struct to hold the key and value.
10974   tree struct_type = make_node(RECORD_TYPE);
10975
10976   Type* key_type = mt->key_type();
10977   tree id = get_identifier("__key");
10978   tree key_field = build_decl(loc, FIELD_DECL, id, key_type->get_tree(gogo));
10979   DECL_CONTEXT(key_field) = struct_type;
10980   TYPE_FIELDS(struct_type) = key_field;
10981
10982   Type* val_type = mt->val_type();
10983   id = get_identifier("__val");
10984   tree val_field = build_decl(loc, FIELD_DECL, id, val_type->get_tree(gogo));
10985   DECL_CONTEXT(val_field) = struct_type;
10986   DECL_CHAIN(key_field) = val_field;
10987
10988   layout_type(struct_type);
10989
10990   bool is_constant = true;
10991   size_t i = 0;
10992   tree valaddr;
10993   tree make_tmp;
10994
10995   if (this->vals_ == NULL || this->vals_->empty())
10996     {
10997       valaddr = null_pointer_node;
10998       make_tmp = NULL_TREE;
10999     }
11000   else
11001     {
11002       VEC(constructor_elt,gc)* values = VEC_alloc(constructor_elt, gc,
11003                                                   this->vals_->size() / 2);
11004
11005       for (Expression_list::const_iterator pv = this->vals_->begin();
11006            pv != this->vals_->end();
11007            ++pv, ++i)
11008         {
11009           bool one_is_constant = true;
11010
11011           VEC(constructor_elt,gc)* one = VEC_alloc(constructor_elt, gc, 2);
11012
11013           constructor_elt* elt = VEC_quick_push(constructor_elt, one, NULL);
11014           elt->index = key_field;
11015           tree val_tree = (*pv)->get_tree(context);
11016           elt->value = Expression::convert_for_assignment(context, key_type,
11017                                                           (*pv)->type(),
11018                                                           val_tree, loc);
11019           if (elt->value == error_mark_node)
11020             return error_mark_node;
11021           if (!TREE_CONSTANT(elt->value))
11022             one_is_constant = false;
11023
11024           ++pv;
11025
11026           elt = VEC_quick_push(constructor_elt, one, NULL);
11027           elt->index = val_field;
11028           val_tree = (*pv)->get_tree(context);
11029           elt->value = Expression::convert_for_assignment(context, val_type,
11030                                                           (*pv)->type(),
11031                                                           val_tree, loc);
11032           if (elt->value == error_mark_node)
11033             return error_mark_node;
11034           if (!TREE_CONSTANT(elt->value))
11035             one_is_constant = false;
11036
11037           elt = VEC_quick_push(constructor_elt, values, NULL);
11038           elt->index = size_int(i);
11039           elt->value = build_constructor(struct_type, one);
11040           if (one_is_constant)
11041             TREE_CONSTANT(elt->value) = 1;
11042           else
11043             is_constant = false;
11044         }
11045
11046       tree index_type = build_index_type(size_int(i - 1));
11047       tree array_type = build_array_type(struct_type, index_type);
11048       tree init = build_constructor(array_type, values);
11049       if (is_constant)
11050         TREE_CONSTANT(init) = 1;
11051       tree tmp;
11052       if (current_function_decl != NULL)
11053         {
11054           tmp = create_tmp_var(array_type, get_name(array_type));
11055           DECL_INITIAL(tmp) = init;
11056           make_tmp = fold_build1_loc(loc, DECL_EXPR, void_type_node, tmp);
11057           TREE_ADDRESSABLE(tmp) = 1;
11058         }
11059       else
11060         {
11061           tmp = build_decl(loc, VAR_DECL, create_tmp_var_name("M"), array_type);
11062           DECL_EXTERNAL(tmp) = 0;
11063           TREE_PUBLIC(tmp) = 0;
11064           TREE_STATIC(tmp) = 1;
11065           DECL_ARTIFICIAL(tmp) = 1;
11066           if (!TREE_CONSTANT(init))
11067             make_tmp = fold_build2_loc(loc, INIT_EXPR, void_type_node, tmp,
11068                                        init);
11069           else
11070             {
11071               TREE_READONLY(tmp) = 1;
11072               TREE_CONSTANT(tmp) = 1;
11073               DECL_INITIAL(tmp) = init;
11074               make_tmp = NULL_TREE;
11075             }
11076           rest_of_decl_compilation(tmp, 1, 0);
11077         }
11078
11079       valaddr = build_fold_addr_expr(tmp);
11080     }
11081
11082   tree descriptor = gogo->map_descriptor(mt);
11083
11084   tree type_tree = this->type_->get_tree(gogo);
11085
11086   static tree construct_map_fndecl;
11087   tree call = Gogo::call_builtin(&construct_map_fndecl,
11088                                  loc,
11089                                  "__go_construct_map",
11090                                  6,
11091                                  type_tree,
11092                                  TREE_TYPE(descriptor),
11093                                  descriptor,
11094                                  sizetype,
11095                                  size_int(i),
11096                                  sizetype,
11097                                  TYPE_SIZE_UNIT(struct_type),
11098                                  sizetype,
11099                                  byte_position(val_field),
11100                                  sizetype,
11101                                  TYPE_SIZE_UNIT(TREE_TYPE(val_field)),
11102                                  const_ptr_type_node,
11103                                  fold_convert(const_ptr_type_node, valaddr));
11104
11105   tree ret;
11106   if (make_tmp == NULL)
11107     ret = call;
11108   else
11109     ret = fold_build2_loc(loc, COMPOUND_EXPR, type_tree, make_tmp, call);
11110   return ret;
11111 }
11112
11113 // Export an array construction.
11114
11115 void
11116 Map_construction_expression::do_export(Export* exp) const
11117 {
11118   exp->write_c_string("convert(");
11119   exp->write_type(this->type_);
11120   for (Expression_list::const_iterator pv = this->vals_->begin();
11121        pv != this->vals_->end();
11122        ++pv)
11123     {
11124       exp->write_c_string(", ");
11125       (*pv)->export_expression(exp);
11126     }
11127   exp->write_c_string(")");
11128 }
11129
11130 // A general composite literal.  This is lowered to a type specific
11131 // version.
11132
11133 class Composite_literal_expression : public Parser_expression
11134 {
11135  public:
11136   Composite_literal_expression(Type* type, int depth, bool has_keys,
11137                                Expression_list* vals, source_location location)
11138     : Parser_expression(EXPRESSION_COMPOSITE_LITERAL, location),
11139       type_(type), depth_(depth), vals_(vals), has_keys_(has_keys)
11140   { }
11141
11142  protected:
11143   int
11144   do_traverse(Traverse* traverse);
11145
11146   Expression*
11147   do_lower(Gogo*, Named_object*, int);
11148
11149   Expression*
11150   do_copy()
11151   {
11152     return new Composite_literal_expression(this->type_, this->depth_,
11153                                             this->has_keys_,
11154                                             (this->vals_ == NULL
11155                                              ? NULL
11156                                              : this->vals_->copy()),
11157                                             this->location());
11158   }
11159
11160  private:
11161   Expression*
11162   lower_struct(Type*);
11163
11164   Expression*
11165   lower_array(Type*);
11166
11167   Expression*
11168   make_array(Type*, Expression_list*);
11169
11170   Expression*
11171   lower_map(Type*);
11172
11173   // The type of the composite literal.
11174   Type* type_;
11175   // The depth within a list of composite literals within a composite
11176   // literal, when the type is omitted.
11177   int depth_;
11178   // The values to put in the composite literal.
11179   Expression_list* vals_;
11180   // If this is true, then VALS_ is a list of pairs: a key and a
11181   // value.  In an array initializer, a missing key will be NULL.
11182   bool has_keys_;
11183 };
11184
11185 // Traversal.
11186
11187 int
11188 Composite_literal_expression::do_traverse(Traverse* traverse)
11189 {
11190   if (this->vals_ != NULL
11191       && this->vals_->traverse(traverse) == TRAVERSE_EXIT)
11192     return TRAVERSE_EXIT;
11193   return Type::traverse(this->type_, traverse);
11194 }
11195
11196 // Lower a generic composite literal into a specific version based on
11197 // the type.
11198
11199 Expression*
11200 Composite_literal_expression::do_lower(Gogo*, Named_object*, int)
11201 {
11202   Type* type = this->type_;
11203
11204   for (int depth = this->depth_; depth > 0; --depth)
11205     {
11206       if (type->array_type() != NULL)
11207         type = type->array_type()->element_type();
11208       else if (type->map_type() != NULL)
11209         type = type->map_type()->val_type();
11210       else
11211         {
11212           if (!type->is_error_type())
11213             error_at(this->location(),
11214                      ("may only omit types within composite literals "
11215                       "of slice, array, or map type"));
11216           return Expression::make_error(this->location());
11217         }
11218     }
11219
11220   if (type->is_error_type())
11221     return Expression::make_error(this->location());
11222   else if (type->struct_type() != NULL)
11223     return this->lower_struct(type);
11224   else if (type->array_type() != NULL)
11225     return this->lower_array(type);
11226   else if (type->map_type() != NULL)
11227     return this->lower_map(type);
11228   else
11229     {
11230       error_at(this->location(),
11231                ("expected struct, slice, array, or map type "
11232                 "for composite literal"));
11233       return Expression::make_error(this->location());
11234     }
11235 }
11236
11237 // Lower a struct composite literal.
11238
11239 Expression*
11240 Composite_literal_expression::lower_struct(Type* type)
11241 {
11242   source_location location = this->location();
11243   Struct_type* st = type->struct_type();
11244   if (this->vals_ == NULL || !this->has_keys_)
11245     return new Struct_construction_expression(type, this->vals_, location);
11246
11247   size_t field_count = st->field_count();
11248   std::vector<Expression*> vals(field_count);
11249   Expression_list::const_iterator p = this->vals_->begin();
11250   while (p != this->vals_->end())
11251     {
11252       Expression* name_expr = *p;
11253
11254       ++p;
11255       gcc_assert(p != this->vals_->end());
11256       Expression* val = *p;
11257
11258       ++p;
11259
11260       if (name_expr == NULL)
11261         {
11262           error_at(val->location(), "mixture of field and value initializers");
11263           return Expression::make_error(location);
11264         }
11265
11266       bool bad_key = false;
11267       std::string name;
11268       switch (name_expr->classification())
11269         {
11270         case EXPRESSION_UNKNOWN_REFERENCE:
11271           name = name_expr->unknown_expression()->name();
11272           break;
11273
11274         case EXPRESSION_CONST_REFERENCE:
11275           name = static_cast<Const_expression*>(name_expr)->name();
11276           break;
11277
11278         case EXPRESSION_TYPE:
11279           {
11280             Type* t = name_expr->type();
11281             Named_type* nt = t->named_type();
11282             if (nt == NULL)
11283               bad_key = true;
11284             else
11285               name = nt->name();
11286           }
11287           break;
11288
11289         case EXPRESSION_VAR_REFERENCE:
11290           name = name_expr->var_expression()->name();
11291           break;
11292
11293         case EXPRESSION_FUNC_REFERENCE:
11294           name = name_expr->func_expression()->name();
11295           break;
11296
11297         case EXPRESSION_UNARY:
11298           // If there is a local variable around with the same name as
11299           // the field, and this occurs in the closure, then the
11300           // parser may turn the field reference into an indirection
11301           // through the closure.  FIXME: This is a mess.
11302           {
11303             bad_key = true;
11304             Unary_expression* ue = static_cast<Unary_expression*>(name_expr);
11305             if (ue->op() == OPERATOR_MULT)
11306               {
11307                 Field_reference_expression* fre =
11308                   ue->operand()->field_reference_expression();
11309                 if (fre != NULL)
11310                   {
11311                     Struct_type* st =
11312                       fre->expr()->type()->deref()->struct_type();
11313                     if (st != NULL)
11314                       {
11315                         const Struct_field* sf = st->field(fre->field_index());
11316                         name = sf->field_name();
11317                         char buf[20];
11318                         snprintf(buf, sizeof buf, "%u", fre->field_index());
11319                         size_t buflen = strlen(buf);
11320                         if (name.compare(name.length() - buflen, buflen, buf)
11321                             == 0)
11322                           {
11323                             name = name.substr(0, name.length() - buflen);
11324                             bad_key = false;
11325                           }
11326                       }
11327                   }
11328               }
11329           }
11330           break;
11331
11332         default:
11333           bad_key = true;
11334           break;
11335         }
11336       if (bad_key)
11337         {
11338           error_at(name_expr->location(), "expected struct field name");
11339           return Expression::make_error(location);
11340         }
11341
11342       unsigned int index;
11343       const Struct_field* sf = st->find_local_field(name, &index);
11344       if (sf == NULL)
11345         {
11346           error_at(name_expr->location(), "unknown field %qs in %qs",
11347                    Gogo::message_name(name).c_str(),
11348                    (type->named_type() != NULL
11349                     ? type->named_type()->message_name().c_str()
11350                     : "unnamed struct"));
11351           return Expression::make_error(location);
11352         }
11353       if (vals[index] != NULL)
11354         {
11355           error_at(name_expr->location(),
11356                    "duplicate value for field %qs in %qs",
11357                    Gogo::message_name(name).c_str(),
11358                    (type->named_type() != NULL
11359                     ? type->named_type()->message_name().c_str()
11360                     : "unnamed struct"));
11361           return Expression::make_error(location);
11362         }
11363
11364       vals[index] = val;
11365     }
11366
11367   Expression_list* list = new Expression_list;
11368   list->reserve(field_count);
11369   for (size_t i = 0; i < field_count; ++i)
11370     list->push_back(vals[i]);
11371
11372   return new Struct_construction_expression(type, list, location);
11373 }
11374
11375 // Lower an array composite literal.
11376
11377 Expression*
11378 Composite_literal_expression::lower_array(Type* type)
11379 {
11380   source_location location = this->location();
11381   if (this->vals_ == NULL || !this->has_keys_)
11382     return this->make_array(type, this->vals_);
11383
11384   std::vector<Expression*> vals;
11385   vals.reserve(this->vals_->size());
11386   unsigned long index = 0;
11387   Expression_list::const_iterator p = this->vals_->begin();
11388   while (p != this->vals_->end())
11389     {
11390       Expression* index_expr = *p;
11391
11392       ++p;
11393       gcc_assert(p != this->vals_->end());
11394       Expression* val = *p;
11395
11396       ++p;
11397
11398       if (index_expr != NULL)
11399         {
11400           mpz_t ival;
11401           mpz_init(ival);
11402           Type* dummy;
11403           if (!index_expr->integer_constant_value(true, ival, &dummy))
11404             {
11405               mpz_clear(ival);
11406               error_at(index_expr->location(),
11407                        "index expression is not integer constant");
11408               return Expression::make_error(location);
11409             }
11410           if (mpz_sgn(ival) < 0)
11411             {
11412               mpz_clear(ival);
11413               error_at(index_expr->location(), "index expression is negative");
11414               return Expression::make_error(location);
11415             }
11416           index = mpz_get_ui(ival);
11417           if (mpz_cmp_ui(ival, index) != 0)
11418             {
11419               mpz_clear(ival);
11420               error_at(index_expr->location(), "index value overflow");
11421               return Expression::make_error(location);
11422             }
11423           mpz_clear(ival);
11424         }
11425
11426       if (index == vals.size())
11427         vals.push_back(val);
11428       else
11429         {
11430           if (index > vals.size())
11431             {
11432               vals.reserve(index + 32);
11433               vals.resize(index + 1, static_cast<Expression*>(NULL));
11434             }
11435           if (vals[index] != NULL)
11436             {
11437               error_at((index_expr != NULL
11438                         ? index_expr->location()
11439                         : val->location()),
11440                        "duplicate value for index %lu",
11441                        index);
11442               return Expression::make_error(location);
11443             }
11444           vals[index] = val;
11445         }
11446
11447       ++index;
11448     }
11449
11450   size_t size = vals.size();
11451   Expression_list* list = new Expression_list;
11452   list->reserve(size);
11453   for (size_t i = 0; i < size; ++i)
11454     list->push_back(vals[i]);
11455
11456   return this->make_array(type, list);
11457 }
11458
11459 // Actually build the array composite literal. This handles
11460 // [...]{...}.
11461
11462 Expression*
11463 Composite_literal_expression::make_array(Type* type, Expression_list* vals)
11464 {
11465   source_location location = this->location();
11466   Array_type* at = type->array_type();
11467   if (at->length() != NULL && at->length()->is_nil_expression())
11468     {
11469       size_t size = vals == NULL ? 0 : vals->size();
11470       mpz_t vlen;
11471       mpz_init_set_ui(vlen, size);
11472       Expression* elen = Expression::make_integer(&vlen, NULL, location);
11473       mpz_clear(vlen);
11474       at = Type::make_array_type(at->element_type(), elen);
11475       type = at;
11476     }
11477   if (at->length() != NULL)
11478     return new Fixed_array_construction_expression(type, vals, location);
11479   else
11480     return new Open_array_construction_expression(type, vals, location);
11481 }
11482
11483 // Lower a map composite literal.
11484
11485 Expression*
11486 Composite_literal_expression::lower_map(Type* type)
11487 {
11488   source_location location = this->location();
11489   if (this->vals_ != NULL)
11490     {
11491       if (!this->has_keys_)
11492         {
11493           error_at(location, "map composite literal must have keys");
11494           return Expression::make_error(location);
11495         }
11496
11497       for (Expression_list::const_iterator p = this->vals_->begin();
11498            p != this->vals_->end();
11499            p += 2)
11500         {
11501           if (*p == NULL)
11502             {
11503               ++p;
11504               error_at((*p)->location(),
11505                        "map composite literal must have keys for every value");
11506               return Expression::make_error(location);
11507             }
11508         }
11509     }
11510
11511   return new Map_construction_expression(type, this->vals_, location);
11512 }
11513
11514 // Make a composite literal expression.
11515
11516 Expression*
11517 Expression::make_composite_literal(Type* type, int depth, bool has_keys,
11518                                    Expression_list* vals,
11519                                    source_location location)
11520 {
11521   return new Composite_literal_expression(type, depth, has_keys, vals,
11522                                           location);
11523 }
11524
11525 // Return whether this expression is a composite literal.
11526
11527 bool
11528 Expression::is_composite_literal() const
11529 {
11530   switch (this->classification_)
11531     {
11532     case EXPRESSION_COMPOSITE_LITERAL:
11533     case EXPRESSION_STRUCT_CONSTRUCTION:
11534     case EXPRESSION_FIXED_ARRAY_CONSTRUCTION:
11535     case EXPRESSION_OPEN_ARRAY_CONSTRUCTION:
11536     case EXPRESSION_MAP_CONSTRUCTION:
11537       return true;
11538     default:
11539       return false;
11540     }
11541 }
11542
11543 // Return whether this expression is a composite literal which is not
11544 // constant.
11545
11546 bool
11547 Expression::is_nonconstant_composite_literal() const
11548 {
11549   switch (this->classification_)
11550     {
11551     case EXPRESSION_STRUCT_CONSTRUCTION:
11552       {
11553         const Struct_construction_expression *psce =
11554           static_cast<const Struct_construction_expression*>(this);
11555         return !psce->is_constant_struct();
11556       }
11557     case EXPRESSION_FIXED_ARRAY_CONSTRUCTION:
11558       {
11559         const Fixed_array_construction_expression *pace =
11560           static_cast<const Fixed_array_construction_expression*>(this);
11561         return !pace->is_constant_array();
11562       }
11563     case EXPRESSION_OPEN_ARRAY_CONSTRUCTION:
11564       {
11565         const Open_array_construction_expression *pace =
11566           static_cast<const Open_array_construction_expression*>(this);
11567         return !pace->is_constant_array();
11568       }
11569     case EXPRESSION_MAP_CONSTRUCTION:
11570       return true;
11571     default:
11572       return false;
11573     }
11574 }
11575
11576 // Return true if this is a reference to a local variable.
11577
11578 bool
11579 Expression::is_local_variable() const
11580 {
11581   const Var_expression* ve = this->var_expression();
11582   if (ve == NULL)
11583     return false;
11584   const Named_object* no = ve->named_object();
11585   return (no->is_result_variable()
11586           || (no->is_variable() && !no->var_value()->is_global()));
11587 }
11588
11589 // Class Type_guard_expression.
11590
11591 // Traversal.
11592
11593 int
11594 Type_guard_expression::do_traverse(Traverse* traverse)
11595 {
11596   if (Expression::traverse(&this->expr_, traverse) == TRAVERSE_EXIT
11597       || Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
11598     return TRAVERSE_EXIT;
11599   return TRAVERSE_CONTINUE;
11600 }
11601
11602 // Check types of a type guard expression.  The expression must have
11603 // an interface type, but the actual type conversion is checked at run
11604 // time.
11605
11606 void
11607 Type_guard_expression::do_check_types(Gogo*)
11608 {
11609   // 6g permits using a type guard with unsafe.pointer; we are
11610   // compatible.
11611   Type* expr_type = this->expr_->type();
11612   if (expr_type->is_unsafe_pointer_type())
11613     {
11614       if (this->type_->points_to() == NULL
11615           && (this->type_->integer_type() == NULL
11616               || (this->type_->forwarded()
11617                   != Type::lookup_integer_type("uintptr"))))
11618         this->report_error(_("invalid unsafe.Pointer conversion"));
11619     }
11620   else if (this->type_->is_unsafe_pointer_type())
11621     {
11622       if (expr_type->points_to() == NULL
11623           && (expr_type->integer_type() == NULL
11624               || (expr_type->forwarded()
11625                   != Type::lookup_integer_type("uintptr"))))
11626         this->report_error(_("invalid unsafe.Pointer conversion"));
11627     }
11628   else if (expr_type->interface_type() == NULL)
11629     this->report_error(_("type assertion only valid for interface types"));
11630   else if (this->type_->interface_type() == NULL)
11631     {
11632       std::string reason;
11633       if (!expr_type->interface_type()->implements_interface(this->type_,
11634                                                              &reason))
11635         {
11636           if (reason.empty())
11637             this->report_error(_("impossible type assertion: "
11638                                  "type does not implement interface"));
11639           else
11640             {
11641               error_at(this->location(),
11642                        ("impossible type assertion: "
11643                         "type does not implement interface (%s)"),
11644                        reason.c_str());
11645               this->set_is_error();
11646             }
11647         }
11648     }
11649 }
11650
11651 // Return a tree for a type guard expression.
11652
11653 tree
11654 Type_guard_expression::do_get_tree(Translate_context* context)
11655 {
11656   Gogo* gogo = context->gogo();
11657   tree expr_tree = this->expr_->get_tree(context);
11658   if (expr_tree == error_mark_node)
11659     return error_mark_node;
11660   Type* expr_type = this->expr_->type();
11661   if ((this->type_->is_unsafe_pointer_type()
11662        && (expr_type->points_to() != NULL
11663            || expr_type->integer_type() != NULL))
11664       || (expr_type->is_unsafe_pointer_type()
11665           && this->type_->points_to() != NULL))
11666     return convert_to_pointer(this->type_->get_tree(gogo), expr_tree);
11667   else if (expr_type->is_unsafe_pointer_type()
11668            && this->type_->integer_type() != NULL)
11669     return convert_to_integer(this->type_->get_tree(gogo), expr_tree);
11670   else if (this->type_->interface_type() != NULL)
11671     return Expression::convert_interface_to_interface(context, this->type_,
11672                                                       this->expr_->type(),
11673                                                       expr_tree, true,
11674                                                       this->location());
11675   else
11676     return Expression::convert_for_assignment(context, this->type_,
11677                                               this->expr_->type(), expr_tree,
11678                                               this->location());
11679 }
11680
11681 // Make a type guard expression.
11682
11683 Expression*
11684 Expression::make_type_guard(Expression* expr, Type* type,
11685                             source_location location)
11686 {
11687   return new Type_guard_expression(expr, type, location);
11688 }
11689
11690 // Class Heap_composite_expression.
11691
11692 // When you take the address of a composite literal, it is allocated
11693 // on the heap.  This class implements that.
11694
11695 class Heap_composite_expression : public Expression
11696 {
11697  public:
11698   Heap_composite_expression(Expression* expr, source_location location)
11699     : Expression(EXPRESSION_HEAP_COMPOSITE, location),
11700       expr_(expr)
11701   { }
11702
11703  protected:
11704   int
11705   do_traverse(Traverse* traverse)
11706   { return Expression::traverse(&this->expr_, traverse); }
11707
11708   Type*
11709   do_type()
11710   { return Type::make_pointer_type(this->expr_->type()); }
11711
11712   void
11713   do_determine_type(const Type_context*)
11714   { this->expr_->determine_type_no_context(); }
11715
11716   Expression*
11717   do_copy()
11718   {
11719     return Expression::make_heap_composite(this->expr_->copy(),
11720                                            this->location());
11721   }
11722
11723   tree
11724   do_get_tree(Translate_context*);
11725
11726   // We only export global objects, and the parser does not generate
11727   // this in global scope.
11728   void
11729   do_export(Export*) const
11730   { gcc_unreachable(); }
11731
11732  private:
11733   // The composite literal which is being put on the heap.
11734   Expression* expr_;
11735 };
11736
11737 // Return a tree which allocates a composite literal on the heap.
11738
11739 tree
11740 Heap_composite_expression::do_get_tree(Translate_context* context)
11741 {
11742   tree expr_tree = this->expr_->get_tree(context);
11743   if (expr_tree == error_mark_node)
11744     return error_mark_node;
11745   tree expr_size = TYPE_SIZE_UNIT(TREE_TYPE(expr_tree));
11746   gcc_assert(TREE_CODE(expr_size) == INTEGER_CST);
11747   tree space = context->gogo()->allocate_memory(this->expr_->type(),
11748                                                 expr_size, this->location());
11749   space = fold_convert(build_pointer_type(TREE_TYPE(expr_tree)), space);
11750   space = save_expr(space);
11751   tree ref = build_fold_indirect_ref_loc(this->location(), space);
11752   TREE_THIS_NOTRAP(ref) = 1;
11753   tree ret = build2(COMPOUND_EXPR, TREE_TYPE(space),
11754                     build2(MODIFY_EXPR, void_type_node, ref, expr_tree),
11755                     space);
11756   SET_EXPR_LOCATION(ret, this->location());
11757   return ret;
11758 }
11759
11760 // Allocate a composite literal on the heap.
11761
11762 Expression*
11763 Expression::make_heap_composite(Expression* expr, source_location location)
11764 {
11765   return new Heap_composite_expression(expr, location);
11766 }
11767
11768 // Class Receive_expression.
11769
11770 // Return the type of a receive expression.
11771
11772 Type*
11773 Receive_expression::do_type()
11774 {
11775   Channel_type* channel_type = this->channel_->type()->channel_type();
11776   if (channel_type == NULL)
11777     return Type::make_error_type();
11778   return channel_type->element_type();
11779 }
11780
11781 // Check types for a receive expression.
11782
11783 void
11784 Receive_expression::do_check_types(Gogo*)
11785 {
11786   Type* type = this->channel_->type();
11787   if (type->is_error_type())
11788     {
11789       this->set_is_error();
11790       return;
11791     }
11792   if (type->channel_type() == NULL)
11793     {
11794       this->report_error(_("expected channel"));
11795       return;
11796     }
11797   if (!type->channel_type()->may_receive())
11798     {
11799       this->report_error(_("invalid receive on send-only channel"));
11800       return;
11801     }
11802 }
11803
11804 // Get a tree for a receive expression.
11805
11806 tree
11807 Receive_expression::do_get_tree(Translate_context* context)
11808 {
11809   Channel_type* channel_type = this->channel_->type()->channel_type();
11810   gcc_assert(channel_type != NULL);
11811   Type* element_type = channel_type->element_type();
11812   tree element_type_tree = element_type->get_tree(context->gogo());
11813
11814   tree channel = this->channel_->get_tree(context);
11815   if (element_type_tree == error_mark_node || channel == error_mark_node)
11816     return error_mark_node;
11817
11818   return Gogo::receive_from_channel(element_type_tree, channel,
11819                                     this->for_select_, this->location());
11820 }
11821
11822 // Make a receive expression.
11823
11824 Receive_expression*
11825 Expression::make_receive(Expression* channel, source_location location)
11826 {
11827   return new Receive_expression(channel, location);
11828 }
11829
11830 // Class Send_expression.
11831
11832 // Traversal.
11833
11834 int
11835 Send_expression::do_traverse(Traverse* traverse)
11836 {
11837   if (Expression::traverse(&this->channel_, traverse) == TRAVERSE_EXIT)
11838     return TRAVERSE_EXIT;
11839   return Expression::traverse(&this->val_, traverse);
11840 }
11841
11842 // Get the type.
11843
11844 Type*
11845 Send_expression::do_type()
11846 {
11847   return Type::lookup_bool_type();
11848 }
11849
11850 // Set types.
11851
11852 void
11853 Send_expression::do_determine_type(const Type_context*)
11854 {
11855   this->channel_->determine_type_no_context();
11856
11857   Type* type = this->channel_->type();
11858   Type_context subcontext;
11859   if (type->channel_type() != NULL)
11860     subcontext.type = type->channel_type()->element_type();
11861   this->val_->determine_type(&subcontext);
11862 }
11863
11864 // Check types.
11865
11866 void
11867 Send_expression::do_check_types(Gogo*)
11868 {
11869   Type* type = this->channel_->type();
11870   if (type->is_error_type())
11871     {
11872       this->set_is_error();
11873       return;
11874     }
11875   Channel_type* channel_type = type->channel_type();
11876   if (channel_type == NULL)
11877     {
11878       error_at(this->location(), "left operand of %<<-%> must be channel");
11879       this->set_is_error();
11880       return;
11881     }
11882   Type* element_type = channel_type->element_type();
11883   if (element_type != NULL
11884       && !Type::are_assignable(element_type, this->val_->type(), NULL))
11885     {
11886       this->report_error(_("incompatible types in send"));
11887       return;
11888     }
11889   if (!channel_type->may_send())
11890     {
11891       this->report_error(_("invalid send on receive-only channel"));
11892       return;
11893     }
11894 }
11895
11896 // Get a tree for a send expression.
11897
11898 tree
11899 Send_expression::do_get_tree(Translate_context* context)
11900 {
11901   tree channel = this->channel_->get_tree(context);
11902   tree val = this->val_->get_tree(context);
11903   if (channel == error_mark_node || val == error_mark_node)
11904     return error_mark_node;
11905   Channel_type* channel_type = this->channel_->type()->channel_type();
11906   val = Expression::convert_for_assignment(context,
11907                                            channel_type->element_type(),
11908                                            this->val_->type(),
11909                                            val,
11910                                            this->location());
11911   return Gogo::send_on_channel(channel, val, this->is_value_discarded_,
11912                                this->for_select_, this->location());
11913 }
11914
11915 // Make a send expression
11916
11917 Send_expression*
11918 Expression::make_send(Expression* channel, Expression* val,
11919                       source_location location)
11920 {
11921   return new Send_expression(channel, val, location);
11922 }
11923
11924 // An expression which evaluates to a pointer to the type descriptor
11925 // of a type.
11926
11927 class Type_descriptor_expression : public Expression
11928 {
11929  public:
11930   Type_descriptor_expression(Type* type, source_location location)
11931     : Expression(EXPRESSION_TYPE_DESCRIPTOR, location),
11932       type_(type)
11933   { }
11934
11935  protected:
11936   Type*
11937   do_type()
11938   { return Type::make_type_descriptor_ptr_type(); }
11939
11940   void
11941   do_determine_type(const Type_context*)
11942   { }
11943
11944   Expression*
11945   do_copy()
11946   { return this; }
11947
11948   tree
11949   do_get_tree(Translate_context* context)
11950   { return this->type_->type_descriptor_pointer(context->gogo()); }
11951
11952  private:
11953   // The type for which this is the descriptor.
11954   Type* type_;
11955 };
11956
11957 // Make a type descriptor expression.
11958
11959 Expression*
11960 Expression::make_type_descriptor(Type* type, source_location location)
11961 {
11962   return new Type_descriptor_expression(type, location);
11963 }
11964
11965 // An expression which evaluates to some characteristic of a type.
11966 // This is only used to initialize fields of a type descriptor.  Using
11967 // a new expression class is slightly inefficient but gives us a good
11968 // separation between the frontend and the middle-end with regard to
11969 // how types are laid out.
11970
11971 class Type_info_expression : public Expression
11972 {
11973  public:
11974   Type_info_expression(Type* type, Type_info type_info)
11975     : Expression(EXPRESSION_TYPE_INFO, BUILTINS_LOCATION),
11976       type_(type), type_info_(type_info)
11977   { }
11978
11979  protected:
11980   Type*
11981   do_type();
11982
11983   void
11984   do_determine_type(const Type_context*)
11985   { }
11986
11987   Expression*
11988   do_copy()
11989   { return this; }
11990
11991   tree
11992   do_get_tree(Translate_context* context);
11993
11994  private:
11995   // The type for which we are getting information.
11996   Type* type_;
11997   // What information we want.
11998   Type_info type_info_;
11999 };
12000
12001 // The type is chosen to match what the type descriptor struct
12002 // expects.
12003
12004 Type*
12005 Type_info_expression::do_type()
12006 {
12007   switch (this->type_info_)
12008     {
12009     case TYPE_INFO_SIZE:
12010       return Type::lookup_integer_type("uintptr");
12011     case TYPE_INFO_ALIGNMENT:
12012     case TYPE_INFO_FIELD_ALIGNMENT:
12013       return Type::lookup_integer_type("uint8");
12014     default:
12015       gcc_unreachable();
12016     }
12017 }
12018
12019 // Return type information in GENERIC.
12020
12021 tree
12022 Type_info_expression::do_get_tree(Translate_context* context)
12023 {
12024   tree type_tree = this->type_->get_tree(context->gogo());
12025   if (type_tree == error_mark_node)
12026     return error_mark_node;
12027
12028   tree val_type_tree = this->type()->get_tree(context->gogo());
12029   gcc_assert(val_type_tree != error_mark_node);
12030
12031   if (this->type_info_ == TYPE_INFO_SIZE)
12032     return fold_convert_loc(BUILTINS_LOCATION, val_type_tree,
12033                             TYPE_SIZE_UNIT(type_tree));
12034   else
12035     {
12036       unsigned HOST_WIDE_INT val;
12037       if (this->type_info_ == TYPE_INFO_ALIGNMENT)
12038         val = TYPE_ALIGN_UNIT(type_tree);
12039       else
12040         {
12041           gcc_assert(this->type_info_ == TYPE_INFO_FIELD_ALIGNMENT);
12042           val = TYPE_ALIGN(type_tree);
12043 #ifdef BIGGEST_FIELD_ALIGMENT
12044           if (val > BIGGEST_FIELD_ALIGNMENT)
12045             val = BIGGEST_FIELD_ALIGNMENT;
12046 #endif
12047 #ifdef ADJUST_FIELD_ALIGN
12048           {
12049             tree f = build_decl(UNKNOWN_LOCATION, FIELD_DECL, NULL, type_tree);
12050             val = ADJUST_FIELD_ALIGN(f, val);
12051           }
12052 #endif
12053           val /= BITS_PER_UNIT;
12054         }
12055
12056       return build_int_cstu(val_type_tree, val);
12057     }
12058 }
12059
12060 // Make a type info expression.
12061
12062 Expression*
12063 Expression::make_type_info(Type* type, Type_info type_info)
12064 {
12065   return new Type_info_expression(type, type_info);
12066 }
12067
12068 // An expression which evaluates to the offset of a field within a
12069 // struct.  This, like Type_info_expression, q.v., is only used to
12070 // initialize fields of a type descriptor.
12071
12072 class Struct_field_offset_expression : public Expression
12073 {
12074  public:
12075   Struct_field_offset_expression(Struct_type* type, const Struct_field* field)
12076     : Expression(EXPRESSION_STRUCT_FIELD_OFFSET, BUILTINS_LOCATION),
12077       type_(type), field_(field)
12078   { }
12079
12080  protected:
12081   Type*
12082   do_type()
12083   { return Type::lookup_integer_type("uintptr"); }
12084
12085   void
12086   do_determine_type(const Type_context*)
12087   { }
12088
12089   Expression*
12090   do_copy()
12091   { return this; }
12092
12093   tree
12094   do_get_tree(Translate_context* context);
12095
12096  private:
12097   // The type of the struct.
12098   Struct_type* type_;
12099   // The field.
12100   const Struct_field* field_;
12101 };
12102
12103 // Return a struct field offset in GENERIC.
12104
12105 tree
12106 Struct_field_offset_expression::do_get_tree(Translate_context* context)
12107 {
12108   tree type_tree = this->type_->get_tree(context->gogo());
12109   if (type_tree == error_mark_node)
12110     return error_mark_node;
12111
12112   tree val_type_tree = this->type()->get_tree(context->gogo());
12113   gcc_assert(val_type_tree != error_mark_node);
12114
12115   const Struct_field_list* fields = this->type_->fields();
12116   tree struct_field_tree = TYPE_FIELDS(type_tree);
12117   Struct_field_list::const_iterator p;
12118   for (p = fields->begin();
12119        p != fields->end();
12120        ++p, struct_field_tree = DECL_CHAIN(struct_field_tree))
12121     {
12122       gcc_assert(struct_field_tree != NULL_TREE);
12123       if (&*p == this->field_)
12124         break;
12125     }
12126   gcc_assert(&*p == this->field_);
12127
12128   return fold_convert_loc(BUILTINS_LOCATION, val_type_tree,
12129                           byte_position(struct_field_tree));
12130 }
12131
12132 // Make an expression for a struct field offset.
12133
12134 Expression*
12135 Expression::make_struct_field_offset(Struct_type* type,
12136                                      const Struct_field* field)
12137 {
12138   return new Struct_field_offset_expression(type, field);
12139 }
12140
12141 // An expression which evaluates to the address of an unnamed label.
12142
12143 class Label_addr_expression : public Expression
12144 {
12145  public:
12146   Label_addr_expression(Label* label, source_location location)
12147     : Expression(EXPRESSION_LABEL_ADDR, location),
12148       label_(label)
12149   { }
12150
12151  protected:
12152   Type*
12153   do_type()
12154   { return Type::make_pointer_type(Type::make_void_type()); }
12155
12156   void
12157   do_determine_type(const Type_context*)
12158   { }
12159
12160   Expression*
12161   do_copy()
12162   { return new Label_addr_expression(this->label_, this->location()); }
12163
12164   tree
12165   do_get_tree(Translate_context*)
12166   { return this->label_->get_addr(this->location()); }
12167
12168  private:
12169   // The label whose address we are taking.
12170   Label* label_;
12171 };
12172
12173 // Make an expression for the address of an unnamed label.
12174
12175 Expression*
12176 Expression::make_label_addr(Label* label, source_location location)
12177 {
12178   return new Label_addr_expression(label, location);
12179 }
12180
12181 // Import an expression.  This comes at the end in order to see the
12182 // various class definitions.
12183
12184 Expression*
12185 Expression::import_expression(Import* imp)
12186 {
12187   int c = imp->peek_char();
12188   if (imp->match_c_string("- ")
12189       || imp->match_c_string("! ")
12190       || imp->match_c_string("^ "))
12191     return Unary_expression::do_import(imp);
12192   else if (c == '(')
12193     return Binary_expression::do_import(imp);
12194   else if (imp->match_c_string("true")
12195            || imp->match_c_string("false"))
12196     return Boolean_expression::do_import(imp);
12197   else if (c == '"')
12198     return String_expression::do_import(imp);
12199   else if (c == '-' || (c >= '0' && c <= '9'))
12200     {
12201       // This handles integers, floats and complex constants.
12202       return Integer_expression::do_import(imp);
12203     }
12204   else if (imp->match_c_string("nil"))
12205     return Nil_expression::do_import(imp);
12206   else if (imp->match_c_string("convert"))
12207     return Type_conversion_expression::do_import(imp);
12208   else
12209     {
12210       error_at(imp->location(), "import error: expected expression");
12211       return Expression::make_error(imp->location());
12212     }
12213 }
12214
12215 // Class Expression_list.
12216
12217 // Traverse the list.
12218
12219 int
12220 Expression_list::traverse(Traverse* traverse)
12221 {
12222   for (Expression_list::iterator p = this->begin();
12223        p != this->end();
12224        ++p)
12225     {
12226       if (*p != NULL)
12227         {
12228           if (Expression::traverse(&*p, traverse) == TRAVERSE_EXIT)
12229             return TRAVERSE_EXIT;
12230         }
12231     }
12232   return TRAVERSE_CONTINUE;
12233 }
12234
12235 // Copy the list.
12236
12237 Expression_list*
12238 Expression_list::copy()
12239 {
12240   Expression_list* ret = new Expression_list();
12241   for (Expression_list::iterator p = this->begin();
12242        p != this->end();
12243        ++p)
12244     {
12245       if (*p == NULL)
12246         ret->push_back(NULL);
12247       else
12248         ret->push_back((*p)->copy());
12249     }
12250   return ret;
12251 }
12252
12253 // Return whether an expression list has an error expression.
12254
12255 bool
12256 Expression_list::contains_error() const
12257 {
12258   for (Expression_list::const_iterator p = this->begin();
12259        p != this->end();
12260        ++p)
12261     if (*p != NULL && (*p)->is_error_expression())
12262       return true;
12263   return false;
12264 }