gcc/go/gofrontend/expressions.cc

   1 // expressions.cc -- Go frontend expression handling.
   2
   3 // Copyright 2009 The Go Authors. All rights reserved.
   4 // Use of this source code is governed by a BSD-style
   5 // license that can be found in the LICENSE file.
   6
   7 #include "go-system.h"
   8
   9 #include <gmp.h>
  10
  11 #ifndef ENABLE_BUILD_WITH_CXX
  12 extern "C"
  13 {
  14 #endif
  15
  16 #include "toplev.h"
  17 #include "intl.h"
  18 #include "tree.h"
  19 #include "gimple.h"
  20 #include "tree-iterator.h"
  21 #include "convert.h"
  22 #include "real.h"
  23 #include "realmpfr.h"
  24
  25 #ifndef ENABLE_BUILD_WITH_CXX
  26 }
  27 #endif
  28
  29 #include "go-c.h"
  30 #include "gogo.h"
  31 #include "types.h"
  32 #include "export.h"
  33 #include "import.h"
  34 #include "statements.h"
  35 #include "lex.h"
  36 #include "expressions.h"
  37
  38 // Class Expression.
  39
  40 Expression::Expression(Expression_classification classification,
  41                        source_location location)
  42   : classification_(classification), location_(location)
  43 {
  44 }
  45
  46 Expression::~Expression()
  47 {
  48 }
  49
  50 // If this expression has a constant integer value, return it.
  51
  52 bool
  53 Expression::integer_constant_value(bool iota_is_constant, mpz_t val,
  54                                    Type** ptype) const
  55 {
  56   *ptype = NULL;
  57   return this->do_integer_constant_value(iota_is_constant, val, ptype);
  58 }
  59
  60 // If this expression has a constant floating point value, return it.
  61
  62 bool
  63 Expression::float_constant_value(mpfr_t val, Type** ptype) const
  64 {
  65   *ptype = NULL;
  66   if (this->do_float_constant_value(val, ptype))
  67     return true;
  68   mpz_t ival;
  69   mpz_init(ival);
  70   Type* t;
  71   bool ret;
  72   if (!this->do_integer_constant_value(false, ival, &t))
  73     ret = false;
  74   else
  75     {
  76       mpfr_set_z(val, ival, GMP_RNDN);
  77       ret = true;
  78     }
  79   mpz_clear(ival);
  80   return ret;
  81 }
  82
  83 // If this expression has a constant complex value, return it.
  84
  85 bool
  86 Expression::complex_constant_value(mpfr_t real, mpfr_t imag,
  87                                    Type** ptype) const
  88 {
  89   *ptype = NULL;
  90   if (this->do_complex_constant_value(real, imag, ptype))
  91     return true;
  92   Type *t;
  93   if (this->float_constant_value(real, &t))
  94     {
  95       mpfr_set_ui(imag, 0, GMP_RNDN);
  96       return true;
  97     }
  98   return false;
  99 }
 100
 101 // Traverse the expressions.
 102
 103 int
 104 Expression::traverse(Expression** pexpr, Traverse* traverse)
 105 {
 106   Expression* expr = *pexpr;
 107   if ((traverse->traverse_mask() & Traverse::traverse_expressions) != 0)
 108     {
 109       int t = traverse->expression(pexpr);
 110       if (t == TRAVERSE_EXIT)
 111         return TRAVERSE_EXIT;
 112       else if (t == TRAVERSE_SKIP_COMPONENTS)
 113         return TRAVERSE_CONTINUE;
 114     }
 115   return expr->do_traverse(traverse);
 116 }
 117
 118 // Traverse subexpressions of this expression.
 119
 120 int
 121 Expression::traverse_subexpressions(Traverse* traverse)
 122 {
 123   return this->do_traverse(traverse);
 124 }
 125
 126 // Default implementation for do_traverse for child classes.
 127
 128 int
 129 Expression::do_traverse(Traverse*)
 130 {
 131   return TRAVERSE_CONTINUE;
 132 }
 133
 134 // This virtual function is called by the parser if the value of this
 135 // expression is being discarded.  By default, we warn.  Expressions
 136 // with side effects override.
 137
 138 void
 139 Expression::do_discarding_value()
 140 {
 141   this->warn_about_unused_value();
 142 }
 143
 144 // This virtual function is called to export expressions.  This will
 145 // only be used by expressions which may be constant.
 146
 147 void
 148 Expression::do_export(Export*) const
 149 {
 150   gcc_unreachable();
 151 }
 152
 153 // Warn that the value of the expression is not used.
 154
 155 void
 156 Expression::warn_about_unused_value()
 157 {
 158   warning_at(this->location(), OPT_Wunused_value, "value computed is not used");
 159 }
 160
 161 // Note that this expression is an error.  This is called by children
 162 // when they discover an error.
 163
 164 void
 165 Expression::set_is_error()
 166 {
 167   this->classification_ = EXPRESSION_ERROR;
 168 }
 169
 170 // For children to call to report an error conveniently.
 171
 172 void
 173 Expression::report_error(const char* msg)
 174 {
 175   error_at(this->location_, "%s", msg);
 176   this->set_is_error();
 177 }
 178
 179 // Set types of variables and constants.  This is implemented by the
 180 // child class.
 181
 182 void
 183 Expression::determine_type(const Type_context* context)
 184 {
 185   this->do_determine_type(context);
 186 }
 187
 188 // Set types when there is no context.
 189
 190 void
 191 Expression::determine_type_no_context()
 192 {
 193   Type_context context;
 194   this->do_determine_type(&context);
 195 }
 196
 197 // Return a tree handling any conversions which must be done during
 198 // assignment.
 199
 200 tree
 201 Expression::convert_for_assignment(Translate_context* context, Type* lhs_type,
 202                                    Type* rhs_type, tree rhs_tree,
 203                                    source_location location)
 204 {
 205   if (lhs_type == rhs_type)
 206     return rhs_tree;
 207
 208   if (lhs_type->is_error_type() || rhs_type->is_error_type())
 209     return error_mark_node;
 210
 211   if (lhs_type->is_undefined() || rhs_type->is_undefined())
 212     {
 213       // Make sure we report the error.
 214       lhs_type->base();
 215       rhs_type->base();
 216       return error_mark_node;
 217     }
 218
 219   if (rhs_tree == error_mark_node || TREE_TYPE(rhs_tree) == error_mark_node)
 220     return error_mark_node;
 221
 222   Gogo* gogo = context->gogo();
 223
 224   tree lhs_type_tree = lhs_type->get_tree(gogo);
 225   if (lhs_type_tree == error_mark_node)
 226     return error_mark_node;
 227
 228   if (lhs_type->interface_type() != NULL)
 229     {
 230       if (rhs_type->interface_type() == NULL)
 231         return Expression::convert_type_to_interface(context, lhs_type,
 232                                                      rhs_type, rhs_tree,
 233                                                      location);
 234       else
 235         return Expression::convert_interface_to_interface(context, lhs_type,
 236                                                           rhs_type, rhs_tree,
 237                                                           false, location);
 238     }
 239   else if (rhs_type->interface_type() != NULL)
 240     return Expression::convert_interface_to_type(context, lhs_type, rhs_type,
 241                                                  rhs_tree, location);
 242   else if (lhs_type->is_open_array_type()
 243            && rhs_type->is_nil_type())
 244     {
 245       // Assigning nil to an open array.
 246       gcc_assert(TREE_CODE(lhs_type_tree) == RECORD_TYPE);
 247
 248       VEC(constructor_elt,gc)* init = VEC_alloc(constructor_elt, gc, 3);
 249
 250       constructor_elt* elt = VEC_quick_push(constructor_elt, init, NULL);
 251       tree field = TYPE_FIELDS(lhs_type_tree);
 252       gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)),
 253                         "__values") == 0);
 254       elt->index = field;
 255       elt->value = fold_convert(TREE_TYPE(field), null_pointer_node);
 256
 257       elt = VEC_quick_push(constructor_elt, init, NULL);
 258       field = DECL_CHAIN(field);
 259       gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)),
 260                         "__count") == 0);
 261       elt->index = field;
 262       elt->value = fold_convert(TREE_TYPE(field), integer_zero_node);
 263
 264       elt = VEC_quick_push(constructor_elt, init, NULL);
 265       field = DECL_CHAIN(field);
 266       gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)),
 267                         "__capacity") == 0);
 268       elt->index = field;
 269       elt->value = fold_convert(TREE_TYPE(field), integer_zero_node);
 270
 271       tree val = build_constructor(lhs_type_tree, init);
 272       TREE_CONSTANT(val) = 1;
 273
 274       return val;
 275     }
 276   else if (rhs_type->is_nil_type())
 277     {
 278       // The left hand side should be a pointer type at the tree
 279       // level.
 280       gcc_assert(POINTER_TYPE_P(lhs_type_tree));
 281       return fold_convert(lhs_type_tree, null_pointer_node);
 282     }
 283   else if (lhs_type_tree == TREE_TYPE(rhs_tree))
 284     {
 285       // No conversion is needed.
 286       return rhs_tree;
 287     }
 288   else if (POINTER_TYPE_P(lhs_type_tree)
 289            || INTEGRAL_TYPE_P(lhs_type_tree)
 290            || SCALAR_FLOAT_TYPE_P(lhs_type_tree)
 291            || COMPLEX_FLOAT_TYPE_P(lhs_type_tree))
 292     return fold_convert_loc(location, lhs_type_tree, rhs_tree);
 293   else if (TREE_CODE(lhs_type_tree) == RECORD_TYPE
 294            && TREE_CODE(TREE_TYPE(rhs_tree)) == RECORD_TYPE)
 295     {
 296       // This conversion must be permitted by Go, or we wouldn't have
 297       // gotten here.
 298       gcc_assert(int_size_in_bytes(lhs_type_tree)
 299                  == int_size_in_bytes(TREE_TYPE(rhs_tree)));
 300       return fold_build1_loc(location, VIEW_CONVERT_EXPR, lhs_type_tree,
 301                              rhs_tree);
 302     }
 303   else
 304     {
 305       gcc_assert(useless_type_conversion_p(lhs_type_tree, TREE_TYPE(rhs_tree)));
 306       return rhs_tree;
 307     }
 308 }
 309
 310 // Return a tree for a conversion from a non-interface type to an
 311 // interface type.
 312
 313 tree
 314 Expression::convert_type_to_interface(Translate_context* context,
 315                                       Type* lhs_type, Type* rhs_type,
 316                                       tree rhs_tree, source_location location)
 317 {
 318   Gogo* gogo = context->gogo();
 319   Interface_type* lhs_interface_type = lhs_type->interface_type();
 320   bool lhs_is_empty = lhs_interface_type->is_empty();
 321
 322   // Since RHS_TYPE is a static type, we can create the interface
 323   // method table at compile time.
 324
 325   // When setting an interface to nil, we just set both fields to
 326   // NULL.
 327   if (rhs_type->is_nil_type())
 328     return lhs_type->get_init_tree(gogo, false);
 329
 330   // This should have been checked already.
 331   gcc_assert(lhs_interface_type->implements_interface(rhs_type, NULL));
 332
 333   tree lhs_type_tree = lhs_type->get_tree(gogo);
 334   if (lhs_type_tree == error_mark_node)
 335     return error_mark_node;
 336
 337   // An interface is a tuple.  If LHS_TYPE is an empty interface type,
 338   // then the first field is the type descriptor for RHS_TYPE.
 339   // Otherwise it is the interface method table for RHS_TYPE.
 340   tree first_field_value;
 341   if (lhs_is_empty)
 342     first_field_value = rhs_type->type_descriptor_pointer(gogo);
 343   else
 344     {
 345       // Build the interface method table for this interface and this
 346       // object type: a list of function pointers for each interface
 347       // method.
 348       Named_type* rhs_named_type = rhs_type->named_type();
 349       bool is_pointer = false;
 350       if (rhs_named_type == NULL)
 351         {
 352           rhs_named_type = rhs_type->deref()->named_type();
 353           is_pointer = true;
 354         }
 355       tree method_table;
 356       if (rhs_named_type == NULL)
 357         method_table = null_pointer_node;
 358       else
 359         method_table =
 360           rhs_named_type->interface_method_table(gogo, lhs_interface_type,
 361                                                  is_pointer);
 362       first_field_value = fold_convert_loc(location, const_ptr_type_node,
 363                                            method_table);
 364     }
 365
 366   // Start building a constructor for the value we will return.
 367
 368   VEC(constructor_elt,gc)* init = VEC_alloc(constructor_elt, gc, 2);
 369
 370   constructor_elt* elt = VEC_quick_push(constructor_elt, init, NULL);
 371   tree field = TYPE_FIELDS(lhs_type_tree);
 372   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)),
 373                     (lhs_is_empty ? "__type_descriptor" : "__methods")) == 0);
 374   elt->index = field;
 375   elt->value = fold_convert_loc(location, TREE_TYPE(field), first_field_value);
 376
 377   elt = VEC_quick_push(constructor_elt, init, NULL);
 378   field = DECL_CHAIN(field);
 379   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__object") == 0);
 380   elt->index = field;
 381
 382   if (rhs_type->points_to() != NULL)
 383     {
 384       //  We are assigning a pointer to the interface; the interface
 385       // holds the pointer itself.
 386       elt->value = rhs_tree;
 387       return build_constructor(lhs_type_tree, init);
 388     }
 389
 390   // We are assigning a non-pointer value to the interface; the
 391   // interface gets a copy of the value in the heap.
 392
 393   tree object_size = TYPE_SIZE_UNIT(TREE_TYPE(rhs_tree));
 394
 395   tree space = gogo->allocate_memory(rhs_type, object_size, location);
 396   space = fold_convert_loc(location, build_pointer_type(TREE_TYPE(rhs_tree)),
 397                            space);
 398   space = save_expr(space);
 399
 400   tree ref = build_fold_indirect_ref_loc(location, space);
 401   TREE_THIS_NOTRAP(ref) = 1;
 402   tree set = fold_build2_loc(location, MODIFY_EXPR, void_type_node,
 403                              ref, rhs_tree);
 404
 405   elt->value = fold_convert_loc(location, TREE_TYPE(field), space);
 406
 407   return build2(COMPOUND_EXPR, lhs_type_tree, set,
 408                 build_constructor(lhs_type_tree, init));
 409 }
 410
 411 // Return a tree for the type descriptor of RHS_TREE, which has
 412 // interface type RHS_TYPE.  If RHS_TREE is nil the result will be
 413 // NULL.
 414
 415 tree
 416 Expression::get_interface_type_descriptor(Translate_context*,
 417                                           Type* rhs_type, tree rhs_tree,
 418                                           source_location location)
 419 {
 420   tree rhs_type_tree = TREE_TYPE(rhs_tree);
 421   gcc_assert(TREE_CODE(rhs_type_tree) == RECORD_TYPE);
 422   tree rhs_field = TYPE_FIELDS(rhs_type_tree);
 423   tree v = build3(COMPONENT_REF, TREE_TYPE(rhs_field), rhs_tree, rhs_field,
 424                   NULL_TREE);
 425   if (rhs_type->interface_type()->is_empty())
 426     {
 427       gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(rhs_field)),
 428                         "__type_descriptor") == 0);
 429       return v;
 430     }
 431
 432   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(rhs_field)), "__methods")
 433              == 0);
 434   gcc_assert(POINTER_TYPE_P(TREE_TYPE(v)));
 435   v = save_expr(v);
 436   tree v1 = build_fold_indirect_ref_loc(location, v);
 437   gcc_assert(TREE_CODE(TREE_TYPE(v1)) == RECORD_TYPE);
 438   tree f = TYPE_FIELDS(TREE_TYPE(v1));
 439   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(f)), "__type_descriptor")
 440              == 0);
 441   v1 = build3(COMPONENT_REF, TREE_TYPE(f), v1, f, NULL_TREE);
 442
 443   tree eq = fold_build2_loc(location, EQ_EXPR, boolean_type_node, v,
 444                             fold_convert_loc(location, TREE_TYPE(v),
 445                                              null_pointer_node));
 446   tree n = fold_convert_loc(location, TREE_TYPE(v1), null_pointer_node);
 447   return fold_build3_loc(location, COND_EXPR, TREE_TYPE(v1),
 448                          eq, n, v1);
 449 }
 450
 451 // Return a tree for the conversion of an interface type to an
 452 // interface type.
 453
 454 tree
 455 Expression::convert_interface_to_interface(Translate_context* context,
 456                                            Type *lhs_type, Type *rhs_type,
 457                                            tree rhs_tree, bool for_type_guard,
 458                                            source_location location)
 459 {
 460   Gogo* gogo = context->gogo();
 461   Interface_type* lhs_interface_type = lhs_type->interface_type();
 462   bool lhs_is_empty = lhs_interface_type->is_empty();
 463
 464   tree lhs_type_tree = lhs_type->get_tree(gogo);
 465   if (lhs_type_tree == error_mark_node)
 466     return error_mark_node;
 467
 468   // In the general case this requires runtime examination of the type
 469   // method table to match it up with the interface methods.
 470
 471   // FIXME: If all of the methods in the right hand side interface
 472   // also appear in the left hand side interface, then we don't need
 473   // to do a runtime check, although we still need to build a new
 474   // method table.
 475
 476   // Get the type descriptor for the right hand side.  This will be
 477   // NULL for a nil interface.
 478
 479   if (!DECL_P(rhs_tree))
 480     rhs_tree = save_expr(rhs_tree);
 481
 482   tree rhs_type_descriptor =
 483     Expression::get_interface_type_descriptor(context, rhs_type, rhs_tree,
 484                                               location);
 485
 486   // The result is going to be a two element constructor.
 487
 488   VEC(constructor_elt,gc)* init = VEC_alloc(constructor_elt, gc, 2);
 489
 490   constructor_elt* elt = VEC_quick_push(constructor_elt, init, NULL);
 491   tree field = TYPE_FIELDS(lhs_type_tree);
 492   elt->index = field;
 493
 494   if (for_type_guard)
 495     {
 496       // A type assertion fails when converting a nil interface.
 497       tree lhs_type_descriptor = lhs_type->type_descriptor_pointer(gogo);
 498       static tree assert_interface_decl;
 499       tree call = Gogo::call_builtin(&assert_interface_decl,
 500                                      location,
 501                                      "__go_assert_interface",
 502                                      2,
 503                                      ptr_type_node,
 504                                      TREE_TYPE(lhs_type_descriptor),
 505                                      lhs_type_descriptor,
 506                                      TREE_TYPE(rhs_type_descriptor),
 507                                      rhs_type_descriptor);
 508       // This will panic if the interface conversion fails.
 509       TREE_NOTHROW(assert_interface_decl) = 0;
 510       elt->value = fold_convert_loc(location, TREE_TYPE(field), call);
 511     }
 512   else if (lhs_is_empty)
 513     {
 514       // A convertion to an empty interface always succeeds, and the
 515       // first field is just the type descriptor of the object.
 516       gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)),
 517                         "__type_descriptor") == 0);
 518       gcc_assert(TREE_TYPE(field) == TREE_TYPE(rhs_type_descriptor));
 519       elt->value = rhs_type_descriptor;
 520     }
 521   else
 522     {
 523       // A conversion to a non-empty interface may fail, but unlike a
 524       // type assertion converting nil will always succeed.
 525       gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__methods")
 526                  == 0);
 527       tree lhs_type_descriptor = lhs_type->type_descriptor_pointer(gogo);
 528       static tree convert_interface_decl;
 529       tree call = Gogo::call_builtin(&convert_interface_decl,
 530                                      location,
 531                                      "__go_convert_interface",
 532                                      2,
 533                                      ptr_type_node,
 534                                      TREE_TYPE(lhs_type_descriptor),
 535                                      lhs_type_descriptor,
 536                                      TREE_TYPE(rhs_type_descriptor),
 537                                      rhs_type_descriptor);
 538       // This will panic if the interface conversion fails.
 539       TREE_NOTHROW(convert_interface_decl) = 0;
 540       elt->value = fold_convert_loc(location, TREE_TYPE(field), call);
 541     }
 542
 543   // The second field is simply the object pointer.
 544
 545   elt = VEC_quick_push(constructor_elt, init, NULL);
 546   field = DECL_CHAIN(field);
 547   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__object") == 0);
 548   elt->index = field;
 549
 550   tree rhs_type_tree = TREE_TYPE(rhs_tree);
 551   gcc_assert(TREE_CODE(rhs_type_tree) == RECORD_TYPE);
 552   tree rhs_field = DECL_CHAIN(TYPE_FIELDS(rhs_type_tree));
 553   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(rhs_field)), "__object") == 0);
 554   elt->value = build3(COMPONENT_REF, TREE_TYPE(rhs_field), rhs_tree, rhs_field,
 555                       NULL_TREE);
 556
 557   return build_constructor(lhs_type_tree, init);
 558 }
 559
 560 // Return a tree for the conversion of an interface type to a
 561 // non-interface type.
 562
 563 tree
 564 Expression::convert_interface_to_type(Translate_context* context,
 565                                       Type *lhs_type, Type* rhs_type,
 566                                       tree rhs_tree, source_location location)
 567 {
 568   Gogo* gogo = context->gogo();
 569   tree rhs_type_tree = TREE_TYPE(rhs_tree);
 570
 571   tree lhs_type_tree = lhs_type->get_tree(gogo);
 572   if (lhs_type_tree == error_mark_node)
 573     return error_mark_node;
 574
 575   // Call a function to check that the type is valid.  The function
 576   // will panic with an appropriate runtime type error if the type is
 577   // not valid.
 578
 579   tree lhs_type_descriptor = lhs_type->type_descriptor_pointer(gogo);
 580
 581   if (!DECL_P(rhs_tree))
 582     rhs_tree = save_expr(rhs_tree);
 583
 584   tree rhs_type_descriptor =
 585     Expression::get_interface_type_descriptor(context, rhs_type, rhs_tree,
 586                                               location);
 587
 588   tree rhs_inter_descriptor = rhs_type->type_descriptor_pointer(gogo);
 589
 590   static tree check_interface_type_decl;
 591   tree call = Gogo::call_builtin(&check_interface_type_decl,
 592                                  location,
 593                                  "__go_check_interface_type",
 594                                  3,
 595                                  void_type_node,
 596                                  TREE_TYPE(lhs_type_descriptor),
 597                                  lhs_type_descriptor,
 598                                  TREE_TYPE(rhs_type_descriptor),
 599                                  rhs_type_descriptor,
 600                                  TREE_TYPE(rhs_inter_descriptor),
 601                                  rhs_inter_descriptor);
 602   // This call will panic if the conversion is invalid.
 603   TREE_NOTHROW(check_interface_type_decl) = 0;
 604
 605   // If the call succeeds, pull out the value.
 606   gcc_assert(TREE_CODE(rhs_type_tree) == RECORD_TYPE);
 607   tree rhs_field = DECL_CHAIN(TYPE_FIELDS(rhs_type_tree));
 608   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(rhs_field)), "__object") == 0);
 609   tree val = build3(COMPONENT_REF, TREE_TYPE(rhs_field), rhs_tree, rhs_field,
 610                     NULL_TREE);
 611
 612   // If the value is a pointer, then it is the value we want.
 613   // Otherwise it points to the value.
 614   if (lhs_type->points_to() == NULL)
 615     {
 616       val = fold_convert_loc(location, build_pointer_type(lhs_type_tree), val);
 617       val = build_fold_indirect_ref_loc(location, val);
 618     }
 619
 620   return build2(COMPOUND_EXPR, lhs_type_tree, call,
 621                 fold_convert_loc(location, lhs_type_tree, val));
 622 }
 623
 624 // Convert an expression to a tree.  This is implemented by the child
 625 // class.  Not that it is not in general safe to call this multiple
 626 // times for a single expression, but that we don't catch such errors.
 627
 628 tree
 629 Expression::get_tree(Translate_context* context)
 630 {
 631   // The child may have marked this expression as having an error.
 632   if (this->classification_ == EXPRESSION_ERROR)
 633     return error_mark_node;
 634
 635   return this->do_get_tree(context);
 636 }
 637
 638 // Return a tree for VAL in TYPE.
 639
 640 tree
 641 Expression::integer_constant_tree(mpz_t val, tree type)
 642 {
 643   if (type == error_mark_node)
 644     return error_mark_node;
 645   else if (TREE_CODE(type) == INTEGER_TYPE)
 646     return double_int_to_tree(type,
 647                               mpz_get_double_int(type, val, true));
 648   else if (TREE_CODE(type) == REAL_TYPE)
 649     {
 650       mpfr_t fval;
 651       mpfr_init_set_z(fval, val, GMP_RNDN);
 652       tree ret = Expression::float_constant_tree(fval, type);
 653       mpfr_clear(fval);
 654       return ret;
 655     }
 656   else if (TREE_CODE(type) == COMPLEX_TYPE)
 657     {
 658       mpfr_t fval;
 659       mpfr_init_set_z(fval, val, GMP_RNDN);
 660       tree real = Expression::float_constant_tree(fval, TREE_TYPE(type));
 661       mpfr_clear(fval);
 662       tree imag = build_real_from_int_cst(TREE_TYPE(type),
 663                                           integer_zero_node);
 664       return build_complex(type, real, imag);
 665     }
 666   else
 667     gcc_unreachable();
 668 }
 669
 670 // Return a tree for VAL in TYPE.
 671
 672 tree
 673 Expression::float_constant_tree(mpfr_t val, tree type)
 674 {
 675   if (type == error_mark_node)
 676     return error_mark_node;
 677   else if (TREE_CODE(type) == INTEGER_TYPE)
 678     {
 679       mpz_t ival;
 680       mpz_init(ival);
 681       mpfr_get_z(ival, val, GMP_RNDN);
 682       tree ret = Expression::integer_constant_tree(ival, type);
 683       mpz_clear(ival);
 684       return ret;
 685     }
 686   else if (TREE_CODE(type) == REAL_TYPE)
 687     {
 688       REAL_VALUE_TYPE r1;
 689       real_from_mpfr(&r1, val, type, GMP_RNDN);
 690       REAL_VALUE_TYPE r2;
 691       real_convert(&r2, TYPE_MODE(type), &r1);
 692       return build_real(type, r2);
 693     }
 694   else if (TREE_CODE(type) == COMPLEX_TYPE)
 695     {
 696       REAL_VALUE_TYPE r1;
 697       real_from_mpfr(&r1, val, TREE_TYPE(type), GMP_RNDN);
 698       REAL_VALUE_TYPE r2;
 699       real_convert(&r2, TYPE_MODE(TREE_TYPE(type)), &r1);
 700       tree imag = build_real_from_int_cst(TREE_TYPE(type),
 701                                           integer_zero_node);
 702       return build_complex(type, build_real(TREE_TYPE(type), r2), imag);
 703     }
 704   else
 705     gcc_unreachable();
 706 }
 707
 708 // Return a tree for REAL/IMAG in TYPE.
 709
 710 tree
 711 Expression::complex_constant_tree(mpfr_t real, mpfr_t imag, tree type)
 712 {
 713   if (TREE_CODE(type) == COMPLEX_TYPE)
 714     {
 715       REAL_VALUE_TYPE r1;
 716       real_from_mpfr(&r1, real, TREE_TYPE(type), GMP_RNDN);
 717       REAL_VALUE_TYPE r2;
 718       real_convert(&r2, TYPE_MODE(TREE_TYPE(type)), &r1);
 719
 720       REAL_VALUE_TYPE r3;
 721       real_from_mpfr(&r3, imag, TREE_TYPE(type), GMP_RNDN);
 722       REAL_VALUE_TYPE r4;
 723       real_convert(&r4, TYPE_MODE(TREE_TYPE(type)), &r3);
 724
 725       return build_complex(type, build_real(TREE_TYPE(type), r2),
 726                            build_real(TREE_TYPE(type), r4));
 727     }
 728   else
 729     gcc_unreachable();
 730 }
 731
 732 // Return a tree which evaluates to true if VAL, of arbitrary integer
 733 // type, is negative or is more than the maximum value of BOUND_TYPE.
 734 // If SOFAR is not NULL, it is or'red into the result.  The return
 735 // value may be NULL if SOFAR is NULL.
 736
 737 tree
 738 Expression::check_bounds(tree val, tree bound_type, tree sofar,
 739                          source_location loc)
 740 {
 741   tree val_type = TREE_TYPE(val);
 742   tree ret = NULL_TREE;
 743
 744   if (!TYPE_UNSIGNED(val_type))
 745     {
 746       ret = fold_build2_loc(loc, LT_EXPR, boolean_type_node, val,
 747                             build_int_cst(val_type, 0));
 748       if (ret == boolean_false_node)
 749         ret = NULL_TREE;
 750     }
 751
 752   if ((TYPE_UNSIGNED(val_type) && !TYPE_UNSIGNED(bound_type))
 753       || TYPE_SIZE(val_type) > TYPE_SIZE(bound_type))
 754     {
 755       tree max = TYPE_MAX_VALUE(bound_type);
 756       tree big = fold_build2_loc(loc, GT_EXPR, boolean_type_node, val,
 757                                  fold_convert_loc(loc, val_type, max));
 758       if (big == boolean_false_node)
 759         ;
 760       else if (ret == NULL_TREE)
 761         ret = big;
 762       else
 763         ret = fold_build2_loc(loc, TRUTH_OR_EXPR, boolean_type_node,
 764                               ret, big);
 765     }
 766
 767   if (ret == NULL_TREE)
 768     return sofar;
 769   else if (sofar == NULL_TREE)
 770     return ret;
 771   else
 772     return fold_build2_loc(loc, TRUTH_OR_EXPR, boolean_type_node,
 773                            sofar, ret);
 774 }
 775
 776 // Error expressions.  This are used to avoid cascading errors.
 777
 778 class Error_expression : public Expression
 779 {
 780  public:
 781   Error_expression(source_location location)
 782     : Expression(EXPRESSION_ERROR, location)
 783   { }
 784
 785  protected:
 786   bool
 787   do_is_constant() const
 788   { return true; }
 789
 790   bool
 791   do_integer_constant_value(bool, mpz_t val, Type**) const
 792   {
 793     mpz_set_ui(val, 0);
 794     return true;
 795   }
 796
 797   bool
 798   do_float_constant_value(mpfr_t val, Type**) const
 799   {
 800     mpfr_set_ui(val, 0, GMP_RNDN);
 801     return true;
 802   }
 803
 804   bool
 805   do_complex_constant_value(mpfr_t real, mpfr_t imag, Type**) const
 806   {
 807     mpfr_set_ui(real, 0, GMP_RNDN);
 808     mpfr_set_ui(imag, 0, GMP_RNDN);
 809     return true;
 810   }
 811
 812   void
 813   do_discarding_value()
 814   { }
 815
 816   Type*
 817   do_type()
 818   { return Type::make_error_type(); }
 819
 820   void
 821   do_determine_type(const Type_context*)
 822   { }
 823
 824   Expression*
 825   do_copy()
 826   { return this; }
 827
 828   bool
 829   do_is_addressable() const
 830   { return true; }
 831
 832   tree
 833   do_get_tree(Translate_context*)
 834   { return error_mark_node; }
 835 };
 836
 837 Expression*
 838 Expression::make_error(source_location location)
 839 {
 840   return new Error_expression(location);
 841 }
 842
 843 // An expression which is really a type.  This is used during parsing.
 844 // It is an error if these survive after lowering.
 845
 846 class
 847 Type_expression : public Expression
 848 {
 849  public:
 850   Type_expression(Type* type, source_location location)
 851     : Expression(EXPRESSION_TYPE, location),
 852       type_(type)
 853   { }
 854
 855  protected:
 856   int
 857   do_traverse(Traverse* traverse)
 858   { return Type::traverse(this->type_, traverse); }
 859
 860   Type*
 861   do_type()
 862   { return this->type_; }
 863
 864   void
 865   do_determine_type(const Type_context*)
 866   { }
 867
 868   void
 869   do_check_types(Gogo*)
 870   { this->report_error(_("invalid use of type")); }
 871
 872   Expression*
 873   do_copy()
 874   { return this; }
 875
 876   tree
 877   do_get_tree(Translate_context*)
 878   { gcc_unreachable(); }
 879
 880  private:
 881   // The type which we are representing as an expression.
 882   Type* type_;
 883 };
 884
 885 Expression*
 886 Expression::make_type(Type* type, source_location location)
 887 {
 888   return new Type_expression(type, location);
 889 }
 890
 891 // Class Var_expression.
 892
 893 // Lower a variable expression.  Here we just make sure that the
 894 // initialization expression of the variable has been lowered.  This
 895 // ensures that we will be able to determine the type of the variable
 896 // if necessary.
 897
 898 Expression*
 899 Var_expression::do_lower(Gogo* gogo, Named_object* function, int)
 900 {
 901   if (this->variable_->is_variable())
 902     {
 903       Variable* var = this->variable_->var_value();
 904       // This is either a local variable or a global variable.  A
 905       // reference to a variable which is local to an enclosing
 906       // function will be a reference to a field in a closure.
 907       if (var->is_global())
 908         function = NULL;
 909       var->lower_init_expression(gogo, function);
 910     }
 911   return this;
 912 }
 913
 914 // Return the name of the variable.
 915
 916 const std::string&
 917 Var_expression::name() const
 918 {
 919   return this->variable_->name();
 920 }
 921
 922 // Return the type of a reference to a variable.
 923
 924 Type*
 925 Var_expression::do_type()
 926 {
 927   if (this->variable_->is_variable())
 928     return this->variable_->var_value()->type();
 929   else if (this->variable_->is_result_variable())
 930     return this->variable_->result_var_value()->type();
 931   else
 932     gcc_unreachable();
 933 }
 934
 935 // Something takes the address of this variable.  This means that we
 936 // may want to move the variable onto the heap.
 937
 938 void
 939 Var_expression::do_address_taken(bool escapes)
 940 {
 941   if (!escapes)
 942     ;
 943   else if (this->variable_->is_variable())
 944     this->variable_->var_value()->set_address_taken();
 945   else if (this->variable_->is_result_variable())
 946     this->variable_->result_var_value()->set_address_taken();
 947   else
 948     gcc_unreachable();
 949 }
 950
 951 // Get the tree for a reference to a variable.
 952
 953 tree
 954 Var_expression::do_get_tree(Translate_context* context)
 955 {
 956   return this->variable_->get_tree(context->gogo(), context->function());
 957 }
 958
 959 // Make a reference to a variable in an expression.
 960
 961 Expression*
 962 Expression::make_var_reference(Named_object* var, source_location location)
 963 {
 964   if (var->is_sink())
 965     return Expression::make_sink(location);
 966
 967   // FIXME: Creating a new object for each reference to a variable is
 968   // wasteful.
 969   return new Var_expression(var, location);
 970 }
 971
 972 // Class Temporary_reference_expression.
 973
 974 // The type.
 975
 976 Type*
 977 Temporary_reference_expression::do_type()
 978 {
 979   return this->statement_->type();
 980 }
 981
 982 // Called if something takes the address of this temporary variable.
 983 // We never have to move temporary variables to the heap, but we do
 984 // need to know that they must live in the stack rather than in a
 985 // register.
 986
 987 void
 988 Temporary_reference_expression::do_address_taken(bool)
 989 {
 990   this->statement_->set_is_address_taken();
 991 }
 992
 993 // Get a tree referring to the variable.
 994
 995 tree
 996 Temporary_reference_expression::do_get_tree(Translate_context*)
 997 {
 998   return this->statement_->get_decl();
 999 }
1000
1001 // Make a reference to a temporary variable.
1002
1003 Expression*
1004 Expression::make_temporary_reference(Temporary_statement* statement,
1005                                      source_location location)
1006 {
1007   return new Temporary_reference_expression(statement, location);
1008 }
1009
1010 // A sink expression--a use of the blank identifier _.
1011
1012 class Sink_expression : public Expression
1013 {
1014  public:
1015   Sink_expression(source_location location)
1016     : Expression(EXPRESSION_SINK, location),
1017       type_(NULL), var_(NULL_TREE)
1018   { }
1019
1020  protected:
1021   void
1022   do_discarding_value()
1023   { }
1024
1025   Type*
1026   do_type();
1027
1028   void
1029   do_determine_type(const Type_context*);
1030
1031   Expression*
1032   do_copy()
1033   { return new Sink_expression(this->location()); }
1034
1035   tree
1036   do_get_tree(Translate_context*);
1037
1038  private:
1039   // The type of this sink variable.
1040   Type* type_;
1041   // The temporary variable we generate.
1042   tree var_;
1043 };
1044
1045 // Return the type of a sink expression.
1046
1047 Type*
1048 Sink_expression::do_type()
1049 {
1050   if (this->type_ == NULL)
1051     return Type::make_sink_type();
1052   return this->type_;
1053 }
1054
1055 // Determine the type of a sink expression.
1056
1057 void
1058 Sink_expression::do_determine_type(const Type_context* context)
1059 {
1060   if (context->type != NULL)
1061     this->type_ = context->type;
1062 }
1063
1064 // Return a temporary variable for a sink expression.  This will
1065 // presumably be a write-only variable which the middle-end will drop.
1066
1067 tree
1068 Sink_expression::do_get_tree(Translate_context* context)
1069 {
1070   if (this->var_ == NULL_TREE)
1071     {
1072       gcc_assert(this->type_ != NULL && !this->type_->is_sink_type());
1073       this->var_ = create_tmp_var(this->type_->get_tree(context->gogo()),
1074                                   "blank");
1075     }
1076   return this->var_;
1077 }
1078
1079 // Make a sink expression.
1080
1081 Expression*
1082 Expression::make_sink(source_location location)
1083 {
1084   return new Sink_expression(location);
1085 }
1086
1087 // Class Func_expression.
1088
1089 // FIXME: Can a function expression appear in a constant expression?
1090 // The value is unchanging.  Initializing a constant to the address of
1091 // a function seems like it could work, though there might be little
1092 // point to it.
1093
1094 // Return the name of the function.
1095
1096 const std::string&
1097 Func_expression::name() const
1098 {
1099   return this->function_->name();
1100 }
1101
1102 // Traversal.
1103
1104 int
1105 Func_expression::do_traverse(Traverse* traverse)
1106 {
1107   return (this->closure_ == NULL
1108           ? TRAVERSE_CONTINUE
1109           : Expression::traverse(&this->closure_, traverse));
1110 }
1111
1112 // Return the type of a function expression.
1113
1114 Type*
1115 Func_expression::do_type()
1116 {
1117   if (this->function_->is_function())
1118     return this->function_->func_value()->type();
1119   else if (this->function_->is_function_declaration())
1120     return this->function_->func_declaration_value()->type();
1121   else
1122     gcc_unreachable();
1123 }
1124
1125 // Get the tree for a function expression without evaluating the
1126 // closure.
1127
1128 tree
1129 Func_expression::get_tree_without_closure(Gogo* gogo)
1130 {
1131   Function_type* fntype;
1132   if (this->function_->is_function())
1133     fntype = this->function_->func_value()->type();
1134   else if (this->function_->is_function_declaration())
1135     fntype = this->function_->func_declaration_value()->type();
1136   else
1137     gcc_unreachable();
1138
1139   // Builtin functions are handled specially by Call_expression.  We
1140   // can't take their address.
1141   if (fntype->is_builtin())
1142     {
1143       error_at(this->location(), "invalid use of special builtin function %qs",
1144                this->function_->name().c_str());
1145       return error_mark_node;
1146     }
1147
1148   Named_object* no = this->function_;
1149
1150   tree id = no->get_id(gogo);
1151   if (id == error_mark_node)
1152     return error_mark_node;
1153
1154   tree fndecl;
1155   if (no->is_function())
1156     fndecl = no->func_value()->get_or_make_decl(gogo, no, id);
1157   else if (no->is_function_declaration())
1158     fndecl = no->func_declaration_value()->get_or_make_decl(gogo, no, id);
1159   else
1160     gcc_unreachable();
1161
1162   if (fndecl == error_mark_node)
1163     return error_mark_node;
1164
1165   return build_fold_addr_expr_loc(this->location(), fndecl);
1166 }
1167
1168 // Get the tree for a function expression.  This is used when we take
1169 // the address of a function rather than simply calling it.  If the
1170 // function has a closure, we must use a trampoline.
1171
1172 tree
1173 Func_expression::do_get_tree(Translate_context* context)
1174 {
1175   Gogo* gogo = context->gogo();
1176
1177   tree fnaddr = this->get_tree_without_closure(gogo);
1178   if (fnaddr == error_mark_node)
1179     return error_mark_node;
1180
1181   gcc_assert(TREE_CODE(fnaddr) == ADDR_EXPR
1182              && TREE_CODE(TREE_OPERAND(fnaddr, 0)) == FUNCTION_DECL);
1183   TREE_ADDRESSABLE(TREE_OPERAND(fnaddr, 0)) = 1;
1184
1185   // For a normal non-nested function call, that is all we have to do.
1186   if (!this->function_->is_function()
1187       || this->function_->func_value()->enclosing() == NULL)
1188     {
1189       gcc_assert(this->closure_ == NULL);
1190       return fnaddr;
1191     }
1192
1193   // For a nested function call, we have to always allocate a
1194   // trampoline.  If we don't always allocate, then closures will not
1195   // be reliably distinct.
1196   Expression* closure = this->closure_;
1197   tree closure_tree;
1198   if (closure == NULL)
1199     closure_tree = null_pointer_node;
1200   else
1201     {
1202       // Get the value of the closure.  This will be a pointer to
1203       // space allocated on the heap.
1204       closure_tree = closure->get_tree(context);
1205       if (closure_tree == error_mark_node)
1206         return error_mark_node;
1207       gcc_assert(POINTER_TYPE_P(TREE_TYPE(closure_tree)));
1208     }
1209
1210   // Now we need to build some code on the heap.  This code will load
1211   // the static chain pointer with the closure and then jump to the
1212   // body of the function.  The normal gcc approach is to build the
1213   // code on the stack.  Unfortunately we can not do that, as Go
1214   // permits us to return the function pointer.
1215
1216   return gogo->make_trampoline(fnaddr, closure_tree, this->location());
1217 }
1218
1219 // Make a reference to a function in an expression.
1220
1221 Expression*
1222 Expression::make_func_reference(Named_object* function, Expression* closure,
1223                                 source_location location)
1224 {
1225   return new Func_expression(function, closure, location);
1226 }
1227
1228 // Class Unknown_expression.
1229
1230 // Return the name of an unknown expression.
1231
1232 const std::string&
1233 Unknown_expression::name() const
1234 {
1235   return this->named_object_->name();
1236 }
1237
1238 // Lower a reference to an unknown name.
1239
1240 Expression*
1241 Unknown_expression::do_lower(Gogo*, Named_object*, int)
1242 {
1243   source_location location = this->location();
1244   Named_object* no = this->named_object_;
1245   Named_object* real = no->unknown_value()->real_named_object();
1246   if (real == NULL)
1247     {
1248       if (this->is_composite_literal_key_)
1249         return this;
1250       error_at(location, "reference to undefined name %qs",
1251                this->named_object_->message_name().c_str());
1252       return Expression::make_error(location);
1253     }
1254   switch (real->classification())
1255     {
1256     case Named_object::NAMED_OBJECT_CONST:
1257       return Expression::make_const_reference(real, location);
1258     case Named_object::NAMED_OBJECT_TYPE:
1259       return Expression::make_type(real->type_value(), location);
1260     case Named_object::NAMED_OBJECT_TYPE_DECLARATION:
1261       if (this->is_composite_literal_key_)
1262         return this;
1263       error_at(location, "reference to undefined type %qs",
1264                real->message_name().c_str());
1265       return Expression::make_error(location);
1266     case Named_object::NAMED_OBJECT_VAR:
1267       return Expression::make_var_reference(real, location);
1268     case Named_object::NAMED_OBJECT_FUNC:
1269     case Named_object::NAMED_OBJECT_FUNC_DECLARATION:
1270       return Expression::make_func_reference(real, NULL, location);
1271     case Named_object::NAMED_OBJECT_PACKAGE:
1272       if (this->is_composite_literal_key_)
1273         return this;
1274       error_at(location, "unexpected reference to package");
1275       return Expression::make_error(location);
1276     default:
1277       gcc_unreachable();
1278     }
1279 }
1280
1281 // Make a reference to an unknown name.
1282
1283 Expression*
1284 Expression::make_unknown_reference(Named_object* no, source_location location)
1285 {
1286   gcc_assert(no->resolve()->is_unknown());
1287   return new Unknown_expression(no, location);
1288 }
1289
1290 // A boolean expression.
1291
1292 class Boolean_expression : public Expression
1293 {
1294  public:
1295   Boolean_expression(bool val, source_location location)
1296     : Expression(EXPRESSION_BOOLEAN, location),
1297       val_(val), type_(NULL)
1298   { }
1299
1300   static Expression*
1301   do_import(Import*);
1302
1303  protected:
1304   bool
1305   do_is_constant() const
1306   { return true; }
1307
1308   Type*
1309   do_type();
1310
1311   void
1312   do_determine_type(const Type_context*);
1313
1314   Expression*
1315   do_copy()
1316   { return this; }
1317
1318   tree
1319   do_get_tree(Translate_context*)
1320   { return this->val_ ? boolean_true_node : boolean_false_node; }
1321
1322   void
1323   do_export(Export* exp) const
1324   { exp->write_c_string(this->val_ ? "true" : "false"); }
1325
1326  private:
1327   // The constant.
1328   bool val_;
1329   // The type as determined by context.
1330   Type* type_;
1331 };
1332
1333 // Get the type.
1334
1335 Type*
1336 Boolean_expression::do_type()
1337 {
1338   if (this->type_ == NULL)
1339     this->type_ = Type::make_boolean_type();
1340   return this->type_;
1341 }
1342
1343 // Set the type from the context.
1344
1345 void
1346 Boolean_expression::do_determine_type(const Type_context* context)
1347 {
1348   if (this->type_ != NULL && !this->type_->is_abstract())
1349     ;
1350   else if (context->type != NULL && context->type->is_boolean_type())
1351     this->type_ = context->type;
1352   else if (!context->may_be_abstract)
1353     this->type_ = Type::lookup_bool_type();
1354 }
1355
1356 // Import a boolean constant.
1357
1358 Expression*
1359 Boolean_expression::do_import(Import* imp)
1360 {
1361   if (imp->peek_char() == 't')
1362     {
1363       imp->require_c_string("true");
1364       return Expression::make_boolean(true, imp->location());
1365     }
1366   else
1367     {
1368       imp->require_c_string("false");
1369       return Expression::make_boolean(false, imp->location());
1370     }
1371 }
1372
1373 // Make a boolean expression.
1374
1375 Expression*
1376 Expression::make_boolean(bool val, source_location location)
1377 {
1378   return new Boolean_expression(val, location);
1379 }
1380
1381 // Class String_expression.
1382
1383 // Get the type.
1384
1385 Type*
1386 String_expression::do_type()
1387 {
1388   if (this->type_ == NULL)
1389     this->type_ = Type::make_string_type();
1390   return this->type_;
1391 }
1392
1393 // Set the type from the context.
1394
1395 void
1396 String_expression::do_determine_type(const Type_context* context)
1397 {
1398   if (this->type_ != NULL && !this->type_->is_abstract())
1399     ;
1400   else if (context->type != NULL && context->type->is_string_type())
1401     this->type_ = context->type;
1402   else if (!context->may_be_abstract)
1403     this->type_ = Type::lookup_string_type();
1404 }
1405
1406 // Build a string constant.
1407
1408 tree
1409 String_expression::do_get_tree(Translate_context* context)
1410 {
1411   return context->gogo()->go_string_constant_tree(this->val_);
1412 }
1413
1414 // Export a string expression.
1415
1416 void
1417 String_expression::do_export(Export* exp) const
1418 {
1419   std::string s;
1420   s.reserve(this->val_.length() * 4 + 2);
1421   s += '"';
1422   for (std::string::const_iterator p = this->val_.begin();
1423        p != this->val_.end();
1424        ++p)
1425     {
1426       if (*p == '\\' || *p == '"')
1427         {
1428           s += '\\';
1429           s += *p;
1430         }
1431       else if (*p >= 0x20 && *p < 0x7f)
1432         s += *p;
1433       else if (*p == '\n')
1434         s += "\\n";
1435       else if (*p == '\t')
1436         s += "\\t";
1437       else
1438         {
1439           s += "\\x";
1440           unsigned char c = *p;
1441           unsigned int dig = c >> 4;
1442           s += dig < 10 ? '0' + dig : 'A' + dig - 10;
1443           dig = c & 0xf;
1444           s += dig < 10 ? '0' + dig : 'A' + dig - 10;
1445         }
1446     }
1447   s += '"';
1448   exp->write_string(s);
1449 }
1450
1451 // Import a string expression.
1452
1453 Expression*
1454 String_expression::do_import(Import* imp)
1455 {
1456   imp->require_c_string("\"");
1457   std::string val;
1458   while (true)
1459     {
1460       int c = imp->get_char();
1461       if (c == '"' || c == -1)
1462         break;
1463       if (c != '\\')
1464         val += static_cast<char>(c);
1465       else
1466         {
1467           c = imp->get_char();
1468           if (c == '\\' || c == '"')
1469             val += static_cast<char>(c);
1470           else if (c == 'n')
1471             val += '\n';
1472           else if (c == 't')
1473             val += '\t';
1474           else if (c == 'x')
1475             {
1476               c = imp->get_char();
1477               unsigned int vh = c >= '0' && c <= '9' ? c - '0' : c - 'A' + 10;
1478               c = imp->get_char();
1479               unsigned int vl = c >= '0' && c <= '9' ? c - '0' : c - 'A' + 10;
1480               char v = (vh << 4) | vl;
1481               val += v;
1482             }
1483           else
1484             {
1485               error_at(imp->location(), "bad string constant");
1486               return Expression::make_error(imp->location());
1487             }
1488         }
1489     }
1490   return Expression::make_string(val, imp->location());
1491 }
1492
1493 // Make a string expression.
1494
1495 Expression*
1496 Expression::make_string(const std::string& val, source_location location)
1497 {
1498   return new String_expression(val, location);
1499 }
1500
1501 // Make an integer expression.
1502
1503 class Integer_expression : public Expression
1504 {
1505  public:
1506   Integer_expression(const mpz_t* val, Type* type, source_location location)
1507     : Expression(EXPRESSION_INTEGER, location),
1508       type_(type)
1509   { mpz_init_set(this->val_, *val); }
1510
1511   static Expression*
1512   do_import(Import*);
1513
1514   // Return whether VAL fits in the type.
1515   static bool
1516   check_constant(mpz_t val, Type*, source_location);
1517
1518   // Write VAL to export data.
1519   static void
1520   export_integer(Export* exp, const mpz_t val);
1521
1522  protected:
1523   bool
1524   do_is_constant() const
1525   { return true; }
1526
1527   bool
1528   do_integer_constant_value(bool, mpz_t val, Type** ptype) const;
1529
1530   Type*
1531   do_type();
1532
1533   void
1534   do_determine_type(const Type_context* context);
1535
1536   void
1537   do_check_types(Gogo*);
1538
1539   tree
1540   do_get_tree(Translate_context*);
1541
1542   Expression*
1543   do_copy()
1544   { return Expression::make_integer(&this->val_, this->type_,
1545                                     this->location()); }
1546
1547   void
1548   do_export(Export*) const;
1549
1550  private:
1551   // The integer value.
1552   mpz_t val_;
1553   // The type so far.
1554   Type* type_;
1555 };
1556
1557 // Return an integer constant value.
1558
1559 bool
1560 Integer_expression::do_integer_constant_value(bool, mpz_t val,
1561                                               Type** ptype) const
1562 {
1563   if (this->type_ != NULL)
1564     *ptype = this->type_;
1565   mpz_set(val, this->val_);
1566   return true;
1567 }
1568
1569 // Return the current type.  If we haven't set the type yet, we return
1570 // an abstract integer type.
1571
1572 Type*
1573 Integer_expression::do_type()
1574 {
1575   if (this->type_ == NULL)
1576     this->type_ = Type::make_abstract_integer_type();
1577   return this->type_;
1578 }
1579
1580 // Set the type of the integer value.  Here we may switch from an
1581 // abstract type to a real type.
1582
1583 void
1584 Integer_expression::do_determine_type(const Type_context* context)
1585 {
1586   if (this->type_ != NULL && !this->type_->is_abstract())
1587     ;
1588   else if (context->type != NULL
1589            && (context->type->integer_type() != NULL
1590                || context->type->float_type() != NULL
1591                || context->type->complex_type() != NULL))
1592     this->type_ = context->type;
1593   else if (!context->may_be_abstract)
1594     this->type_ = Type::lookup_integer_type("int");
1595 }
1596
1597 // Return true if the integer VAL fits in the range of the type TYPE.
1598 // Otherwise give an error and return false.  TYPE may be NULL.
1599
1600 bool
1601 Integer_expression::check_constant(mpz_t val, Type* type,
1602                                    source_location location)
1603 {
1604   if (type == NULL)
1605     return true;
1606   Integer_type* itype = type->integer_type();
1607   if (itype == NULL || itype->is_abstract())
1608     return true;
1609
1610   int bits = mpz_sizeinbase(val, 2);
1611
1612   if (itype->is_unsigned())
1613     {
1614       // For an unsigned type we can only accept a nonnegative number,
1615       // and we must be able to represent at least BITS.
1616       if (mpz_sgn(val) >= 0
1617           && bits <= itype->bits())
1618         return true;
1619     }
1620   else
1621     {
1622       // For a signed type we need an extra bit to indicate the sign.
1623       // We have to handle the most negative integer specially.
1624       if (bits + 1 <= itype->bits()
1625           || (bits <= itype->bits()
1626               && mpz_sgn(val) < 0
1627               && (mpz_scan1(val, 0)
1628                   == static_cast<unsigned long>(itype->bits() - 1))
1629               && mpz_scan0(val, itype->bits()) == ULONG_MAX))
1630         return true;
1631     }
1632
1633   error_at(location, "integer constant overflow");
1634   return false;
1635 }
1636
1637 // Check the type of an integer constant.
1638
1639 void
1640 Integer_expression::do_check_types(Gogo*)
1641 {
1642   if (this->type_ == NULL)
1643     return;
1644   if (!Integer_expression::check_constant(this->val_, this->type_,
1645                                           this->location()))
1646     this->set_is_error();
1647 }
1648
1649 // Get a tree for an integer constant.
1650
1651 tree
1652 Integer_expression::do_get_tree(Translate_context* context)
1653 {
1654   Gogo* gogo = context->gogo();
1655   tree type;
1656   if (this->type_ != NULL && !this->type_->is_abstract())
1657     type = this->type_->get_tree(gogo);
1658   else if (this->type_ != NULL && this->type_->float_type() != NULL)
1659     {
1660       // We are converting to an abstract floating point type.
1661       type = Type::lookup_float_type("float64")->get_tree(gogo);
1662     }
1663   else if (this->type_ != NULL && this->type_->complex_type() != NULL)
1664     {
1665       // We are converting to an abstract complex type.
1666       type = Type::lookup_complex_type("complex128")->get_tree(gogo);
1667     }
1668   else
1669     {
1670       // If we still have an abstract type here, then this is being
1671       // used in a constant expression which didn't get reduced for
1672       // some reason.  Use a type which will fit the value.  We use <,
1673       // not <=, because we need an extra bit for the sign bit.
1674       int bits = mpz_sizeinbase(this->val_, 2);
1675       if (bits < INT_TYPE_SIZE)
1676         type = Type::lookup_integer_type("int")->get_tree(gogo);
1677       else if (bits < 64)
1678         type = Type::lookup_integer_type("int64")->get_tree(gogo);
1679       else
1680         type = long_long_integer_type_node;
1681     }
1682   return Expression::integer_constant_tree(this->val_, type);
1683 }
1684
1685 // Write VAL to export data.
1686
1687 void
1688 Integer_expression::export_integer(Export* exp, const mpz_t val)
1689 {
1690   char* s = mpz_get_str(NULL, 10, val);
1691   exp->write_c_string(s);
1692   free(s);
1693 }
1694
1695 // Export an integer in a constant expression.
1696
1697 void
1698 Integer_expression::do_export(Export* exp) const
1699 {
1700   Integer_expression::export_integer(exp, this->val_);
1701   // A trailing space lets us reliably identify the end of the number.
1702   exp->write_c_string(" ");
1703 }
1704
1705 // Import an integer, floating point, or complex value.  This handles
1706 // all these types because they all start with digits.
1707
1708 Expression*
1709 Integer_expression::do_import(Import* imp)
1710 {
1711   std::string num = imp->read_identifier();
1712   imp->require_c_string(" ");
1713   if (!num.empty() && num[num.length() - 1] == 'i')
1714     {
1715       mpfr_t real;
1716       size_t plus_pos = num.find('+', 1);
1717       size_t minus_pos = num.find('-', 1);
1718       size_t pos;
1719       if (plus_pos == std::string::npos)
1720         pos = minus_pos;
1721       else if (minus_pos == std::string::npos)
1722         pos = plus_pos;
1723       else
1724         {
1725           error_at(imp->location(), "bad number in import data: %qs",
1726                    num.c_str());
1727           return Expression::make_error(imp->location());
1728         }
1729       if (pos == std::string::npos)
1730         mpfr_set_ui(real, 0, GMP_RNDN);
1731       else
1732         {
1733           std::string real_str = num.substr(0, pos);
1734           if (mpfr_init_set_str(real, real_str.c_str(), 10, GMP_RNDN) != 0)
1735             {
1736               error_at(imp->location(), "bad number in import data: %qs",
1737                        real_str.c_str());
1738               return Expression::make_error(imp->location());
1739             }
1740         }
1741
1742       std::string imag_str;
1743       if (pos == std::string::npos)
1744         imag_str = num;
1745       else
1746         imag_str = num.substr(pos);
1747       imag_str = imag_str.substr(0, imag_str.size() - 1);
1748       mpfr_t imag;
1749       if (mpfr_init_set_str(imag, imag_str.c_str(), 10, GMP_RNDN) != 0)
1750         {
1751           error_at(imp->location(), "bad number in import data: %qs",
1752                    imag_str.c_str());
1753           return Expression::make_error(imp->location());
1754         }
1755       Expression* ret = Expression::make_complex(&real, &imag, NULL,
1756                                                  imp->location());
1757       mpfr_clear(real);
1758       mpfr_clear(imag);
1759       return ret;
1760     }
1761   else if (num.find('.') == std::string::npos
1762            && num.find('E') == std::string::npos)
1763     {
1764       mpz_t val;
1765       if (mpz_init_set_str(val, num.c_str(), 10) != 0)
1766         {
1767           error_at(imp->location(), "bad number in import data: %qs",
1768                    num.c_str());
1769           return Expression::make_error(imp->location());
1770         }
1771       Expression* ret = Expression::make_integer(&val, NULL, imp->location());
1772       mpz_clear(val);
1773       return ret;
1774     }
1775   else
1776     {
1777       mpfr_t val;
1778       if (mpfr_init_set_str(val, num.c_str(), 10, GMP_RNDN) != 0)
1779         {
1780           error_at(imp->location(), "bad number in import data: %qs",
1781                    num.c_str());
1782           return Expression::make_error(imp->location());
1783         }
1784       Expression* ret = Expression::make_float(&val, NULL, imp->location());
1785       mpfr_clear(val);
1786       return ret;
1787     }
1788 }
1789
1790 // Build a new integer value.
1791
1792 Expression*
1793 Expression::make_integer(const mpz_t* val, Type* type,
1794                          source_location location)
1795 {
1796   return new Integer_expression(val, type, location);
1797 }
1798
1799 // Floats.
1800
1801 class Float_expression : public Expression
1802 {
1803  public:
1804   Float_expression(const mpfr_t* val, Type* type, source_location location)
1805     : Expression(EXPRESSION_FLOAT, location),
1806       type_(type)
1807   {
1808     mpfr_init_set(this->val_, *val, GMP_RNDN);
1809   }
1810
1811   // Constrain VAL to fit into TYPE.
1812   static void
1813   constrain_float(mpfr_t val, Type* type);
1814
1815   // Return whether VAL fits in the type.
1816   static bool
1817   check_constant(mpfr_t val, Type*, source_location);
1818
1819   // Write VAL to export data.
1820   static void
1821   export_float(Export* exp, const mpfr_t val);
1822
1823  protected:
1824   bool
1825   do_is_constant() const
1826   { return true; }
1827
1828   bool
1829   do_float_constant_value(mpfr_t val, Type**) const;
1830
1831   Type*
1832   do_type();
1833
1834   void
1835   do_determine_type(const Type_context*);
1836
1837   void
1838   do_check_types(Gogo*);
1839
1840   Expression*
1841   do_copy()
1842   { return Expression::make_float(&this->val_, this->type_,
1843                                   this->location()); }
1844
1845   tree
1846   do_get_tree(Translate_context*);
1847
1848   void
1849   do_export(Export*) const;
1850
1851  private:
1852   // The floating point value.
1853   mpfr_t val_;
1854   // The type so far.
1855   Type* type_;
1856 };
1857
1858 // Constrain VAL to fit into TYPE.
1859
1860 void
1861 Float_expression::constrain_float(mpfr_t val, Type* type)
1862 {
1863   Float_type* ftype = type->float_type();
1864   if (ftype != NULL && !ftype->is_abstract())
1865     {
1866       tree type_tree = ftype->type_tree();
1867       REAL_VALUE_TYPE rvt;
1868       real_from_mpfr(&rvt, val, type_tree, GMP_RNDN);
1869       real_convert(&rvt, TYPE_MODE(type_tree), &rvt);
1870       mpfr_from_real(val, &rvt, GMP_RNDN);
1871     }
1872 }
1873
1874 // Return a floating point constant value.
1875
1876 bool
1877 Float_expression::do_float_constant_value(mpfr_t val, Type** ptype) const
1878 {
1879   if (this->type_ != NULL)
1880     *ptype = this->type_;
1881   mpfr_set(val, this->val_, GMP_RNDN);
1882   return true;
1883 }
1884
1885 // Return the current type.  If we haven't set the type yet, we return
1886 // an abstract float type.
1887
1888 Type*
1889 Float_expression::do_type()
1890 {
1891   if (this->type_ == NULL)
1892     this->type_ = Type::make_abstract_float_type();
1893   return this->type_;
1894 }
1895
1896 // Set the type of the float value.  Here we may switch from an
1897 // abstract type to a real type.
1898
1899 void
1900 Float_expression::do_determine_type(const Type_context* context)
1901 {
1902   if (this->type_ != NULL && !this->type_->is_abstract())
1903     ;
1904   else if (context->type != NULL
1905            && (context->type->integer_type() != NULL
1906                || context->type->float_type() != NULL
1907                || context->type->complex_type() != NULL))
1908     this->type_ = context->type;
1909   else if (!context->may_be_abstract)
1910     this->type_ = Type::lookup_float_type("float");
1911 }
1912
1913 // Return true if the floating point value VAL fits in the range of
1914 // the type TYPE.  Otherwise give an error and return false.  TYPE may
1915 // be NULL.
1916
1917 bool
1918 Float_expression::check_constant(mpfr_t val, Type* type,
1919                                  source_location location)
1920 {
1921   if (type == NULL)
1922     return true;
1923   Float_type* ftype = type->float_type();
1924   if (ftype == NULL || ftype->is_abstract())
1925     return true;
1926
1927   // A NaN or Infinity always fits in the range of the type.
1928   if (mpfr_nan_p(val) || mpfr_inf_p(val) || mpfr_zero_p(val))
1929     return true;
1930
1931   mp_exp_t exp = mpfr_get_exp(val);
1932   mp_exp_t max_exp;
1933   switch (ftype->bits())
1934     {
1935     case 32:
1936       max_exp = 128;
1937       break;
1938     case 64:
1939       max_exp = 1024;
1940       break;
1941     default:
1942       gcc_unreachable();
1943     }
1944   if (exp > max_exp)
1945     {
1946       error_at(location, "floating point constant overflow");
1947       return false;
1948     }
1949   return true;
1950 }
1951
1952 // Check the type of a float value.
1953
1954 void
1955 Float_expression::do_check_types(Gogo*)
1956 {
1957   if (this->type_ == NULL)
1958     return;
1959
1960   if (!Float_expression::check_constant(this->val_, this->type_,
1961                                         this->location()))
1962     this->set_is_error();
1963
1964   Integer_type* integer_type = this->type_->integer_type();
1965   if (integer_type != NULL)
1966     {
1967       if (!mpfr_integer_p(this->val_))
1968         this->report_error(_("floating point constant truncated to integer"));
1969       else
1970         {
1971           gcc_assert(!integer_type->is_abstract());
1972           mpz_t ival;
1973           mpz_init(ival);
1974           mpfr_get_z(ival, this->val_, GMP_RNDN);
1975           Integer_expression::check_constant(ival, integer_type,
1976                                              this->location());
1977           mpz_clear(ival);
1978         }
1979     }
1980 }
1981
1982 // Get a tree for a float constant.
1983
1984 tree
1985 Float_expression::do_get_tree(Translate_context* context)
1986 {
1987   Gogo* gogo = context->gogo();
1988   tree type;
1989   if (this->type_ != NULL && !this->type_->is_abstract())
1990     type = this->type_->get_tree(gogo);
1991   else if (this->type_ != NULL && this->type_->integer_type() != NULL)
1992     {
1993       // We have an abstract integer type.  We just hope for the best.
1994       type = Type::lookup_integer_type("int")->get_tree(gogo);
1995     }
1996   else
1997     {
1998       // If we still have an abstract type here, then this is being
1999       // used in a constant expression which didn't get reduced.  We
2000       // just use float64 and hope for the best.
2001       type = Type::lookup_float_type("float64")->get_tree(gogo);
2002     }
2003   return Expression::float_constant_tree(this->val_, type);
2004 }
2005
2006 // Write a floating point number to export data.
2007
2008 void
2009 Float_expression::export_float(Export *exp, const mpfr_t val)
2010 {
2011   mp_exp_t exponent;
2012   char* s = mpfr_get_str(NULL, &exponent, 10, 0, val, GMP_RNDN);
2013   if (*s == '-')
2014     exp->write_c_string("-");
2015   exp->write_c_string("0.");
2016   exp->write_c_string(*s == '-' ? s + 1 : s);
2017   mpfr_free_str(s);
2018   char buf[30];
2019   snprintf(buf, sizeof buf, "E%ld", exponent);
2020   exp->write_c_string(buf);
2021 }
2022
2023 // Export a floating point number in a constant expression.
2024
2025 void
2026 Float_expression::do_export(Export* exp) const
2027 {
2028   Float_expression::export_float(exp, this->val_);
2029   // A trailing space lets us reliably identify the end of the number.
2030   exp->write_c_string(" ");
2031 }
2032
2033 // Make a float expression.
2034
2035 Expression*
2036 Expression::make_float(const mpfr_t* val, Type* type, source_location location)
2037 {
2038   return new Float_expression(val, type, location);
2039 }
2040
2041 // Complex numbers.
2042
2043 class Complex_expression : public Expression
2044 {
2045  public:
2046   Complex_expression(const mpfr_t* real, const mpfr_t* imag, Type* type,
2047                      source_location location)
2048     : Expression(EXPRESSION_COMPLEX, location),
2049       type_(type)
2050   {
2051     mpfr_init_set(this->real_, *real, GMP_RNDN);
2052     mpfr_init_set(this->imag_, *imag, GMP_RNDN);
2053   }
2054
2055   // Constrain REAL/IMAG to fit into TYPE.
2056   static void
2057   constrain_complex(mpfr_t real, mpfr_t imag, Type* type);
2058
2059   // Return whether REAL/IMAG fits in the type.
2060   static bool
2061   check_constant(mpfr_t real, mpfr_t imag, Type*, source_location);
2062
2063   // Write REAL/IMAG to export data.
2064   static void
2065   export_complex(Export* exp, const mpfr_t real, const mpfr_t val);
2066
2067  protected:
2068   bool
2069   do_is_constant() const
2070   { return true; }
2071
2072   bool
2073   do_complex_constant_value(mpfr_t real, mpfr_t imag, Type**) const;
2074
2075   Type*
2076   do_type();
2077
2078   void
2079   do_determine_type(const Type_context*);
2080
2081   void
2082   do_check_types(Gogo*);
2083
2084   Expression*
2085   do_copy()
2086   {
2087     return Expression::make_complex(&this->real_, &this->imag_, this->type_,
2088                                     this->location());
2089   }
2090
2091   tree
2092   do_get_tree(Translate_context*);
2093
2094   void
2095   do_export(Export*) const;
2096
2097  private:
2098   // The real part.
2099   mpfr_t real_;
2100   // The imaginary part;
2101   mpfr_t imag_;
2102   // The type if known.
2103   Type* type_;
2104 };
2105
2106 // Constrain REAL/IMAG to fit into TYPE.
2107
2108 void
2109 Complex_expression::constrain_complex(mpfr_t real, mpfr_t imag, Type* type)
2110 {
2111   Complex_type* ctype = type->complex_type();
2112   if (ctype != NULL && !ctype->is_abstract())
2113     {
2114       tree type_tree = ctype->type_tree();
2115
2116       REAL_VALUE_TYPE rvt;
2117       real_from_mpfr(&rvt, real, TREE_TYPE(type_tree), GMP_RNDN);
2118       real_convert(&rvt, TYPE_MODE(TREE_TYPE(type_tree)), &rvt);
2119       mpfr_from_real(real, &rvt, GMP_RNDN);
2120
2121       real_from_mpfr(&rvt, imag, TREE_TYPE(type_tree), GMP_RNDN);
2122       real_convert(&rvt, TYPE_MODE(TREE_TYPE(type_tree)), &rvt);
2123       mpfr_from_real(imag, &rvt, GMP_RNDN);
2124     }
2125 }
2126
2127 // Return a complex constant value.
2128
2129 bool
2130 Complex_expression::do_complex_constant_value(mpfr_t real, mpfr_t imag,
2131                                               Type** ptype) const
2132 {
2133   if (this->type_ != NULL)
2134     *ptype = this->type_;
2135   mpfr_set(real, this->real_, GMP_RNDN);
2136   mpfr_set(imag, this->imag_, GMP_RNDN);
2137   return true;
2138 }
2139
2140 // Return the current type.  If we haven't set the type yet, we return
2141 // an abstract complex type.
2142
2143 Type*
2144 Complex_expression::do_type()
2145 {
2146   if (this->type_ == NULL)
2147     this->type_ = Type::make_abstract_complex_type();
2148   return this->type_;
2149 }
2150
2151 // Set the type of the complex value.  Here we may switch from an
2152 // abstract type to a real type.
2153
2154 void
2155 Complex_expression::do_determine_type(const Type_context* context)
2156 {
2157   if (this->type_ != NULL && !this->type_->is_abstract())
2158     ;
2159   else if (context->type != NULL
2160            && context->type->complex_type() != NULL)
2161     this->type_ = context->type;
2162   else if (!context->may_be_abstract)
2163     this->type_ = Type::lookup_complex_type("complex");
2164 }
2165
2166 // Return true if the complex value REAL/IMAG fits in the range of the
2167 // type TYPE.  Otherwise give an error and return false.  TYPE may be
2168 // NULL.
2169
2170 bool
2171 Complex_expression::check_constant(mpfr_t real, mpfr_t imag, Type* type,
2172                                    source_location location)
2173 {
2174   if (type == NULL)
2175     return true;
2176   Complex_type* ctype = type->complex_type();
2177   if (ctype == NULL || ctype->is_abstract())
2178     return true;
2179
2180   mp_exp_t max_exp;
2181   switch (ctype->bits())
2182     {
2183     case 64:
2184       max_exp = 128;
2185       break;
2186     case 128:
2187       max_exp = 1024;
2188       break;
2189     default:
2190       gcc_unreachable();
2191     }
2192
2193   // A NaN or Infinity always fits in the range of the type.
2194   if (!mpfr_nan_p(real) && !mpfr_inf_p(real) && !mpfr_zero_p(real))
2195     {
2196       if (mpfr_get_exp(real) > max_exp)
2197         {
2198           error_at(location, "complex real part constant overflow");
2199           return false;
2200         }
2201     }
2202
2203   if (!mpfr_nan_p(imag) && !mpfr_inf_p(imag) && !mpfr_zero_p(imag))
2204     {
2205       if (mpfr_get_exp(imag) > max_exp)
2206         {
2207           error_at(location, "complex imaginary part constant overflow");
2208           return false;
2209         }
2210     }
2211
2212   return true;
2213 }
2214
2215 // Check the type of a complex value.
2216
2217 void
2218 Complex_expression::do_check_types(Gogo*)
2219 {
2220   if (this->type_ == NULL)
2221     return;
2222
2223   if (!Complex_expression::check_constant(this->real_, this->imag_,
2224                                           this->type_, this->location()))
2225     this->set_is_error();
2226 }
2227
2228 // Get a tree for a complex constant.
2229
2230 tree
2231 Complex_expression::do_get_tree(Translate_context* context)
2232 {
2233   Gogo* gogo = context->gogo();
2234   tree type;
2235   if (this->type_ != NULL && !this->type_->is_abstract())
2236     type = this->type_->get_tree(gogo);
2237   else
2238     {
2239       // If we still have an abstract type here, this this is being
2240       // used in a constant expression which didn't get reduced.  We
2241       // just use complex128 and hope for the best.
2242       type = Type::lookup_complex_type("complex128")->get_tree(gogo);
2243     }
2244   return Expression::complex_constant_tree(this->real_, this->imag_, type);
2245 }
2246
2247 // Write REAL/IMAG to export data.
2248
2249 void
2250 Complex_expression::export_complex(Export* exp, const mpfr_t real,
2251                                    const mpfr_t imag)
2252 {
2253   if (!mpfr_zero_p(real))
2254     {
2255       Float_expression::export_float(exp, real);
2256       if (mpfr_sgn(imag) > 0)
2257         exp->write_c_string("+");
2258     }
2259   Float_expression::export_float(exp, imag);
2260   exp->write_c_string("i");
2261 }
2262
2263 // Export a complex number in a constant expression.
2264
2265 void
2266 Complex_expression::do_export(Export* exp) const
2267 {
2268   Complex_expression::export_complex(exp, this->real_, this->imag_);
2269   // A trailing space lets us reliably identify the end of the number.
2270   exp->write_c_string(" ");
2271 }
2272
2273 // Make a complex expression.
2274
2275 Expression*
2276 Expression::make_complex(const mpfr_t* real, const mpfr_t* imag, Type* type,
2277                          source_location location)
2278 {
2279   return new Complex_expression(real, imag, type, location);
2280 }
2281
2282 // A reference to a const in an expression.
2283
2284 class Const_expression : public Expression
2285 {
2286  public:
2287   Const_expression(Named_object* constant, source_location location)
2288     : Expression(EXPRESSION_CONST_REFERENCE, location),
2289       constant_(constant), type_(NULL)
2290   { }
2291
2292   const std::string&
2293   name() const
2294   { return this->constant_->name(); }
2295
2296  protected:
2297   Expression*
2298   do_lower(Gogo*, Named_object*, int);
2299
2300   bool
2301   do_is_constant() const
2302   { return true; }
2303
2304   bool
2305   do_integer_constant_value(bool, mpz_t val, Type**) const;
2306
2307   bool
2308   do_float_constant_value(mpfr_t val, Type**) const;
2309
2310   bool
2311   do_complex_constant_value(mpfr_t real, mpfr_t imag, Type**) const;
2312
2313   bool
2314   do_string_constant_value(std::string* val) const
2315   { return this->constant_->const_value()->expr()->string_constant_value(val); }
2316
2317   Type*
2318   do_type();
2319
2320   // The type of a const is set by the declaration, not the use.
2321   void
2322   do_determine_type(const Type_context*);
2323
2324   void
2325   do_check_types(Gogo*);
2326
2327   Expression*
2328   do_copy()
2329   { return this; }
2330
2331   tree
2332   do_get_tree(Translate_context* context);
2333
2334   // When exporting a reference to a const as part of a const
2335   // expression, we export the value.  We ignore the fact that it has
2336   // a name.
2337   void
2338   do_export(Export* exp) const
2339   { this->constant_->const_value()->expr()->export_expression(exp); }
2340
2341  private:
2342   // The constant.
2343   Named_object* constant_;
2344   // The type of this reference.  This is used if the constant has an
2345   // abstract type.
2346   Type* type_;
2347 };
2348
2349 // Lower a constant expression.  This is where we convert the
2350 // predeclared constant iota into an integer value.
2351
2352 Expression*
2353 Const_expression::do_lower(Gogo* gogo, Named_object*, int iota_value)
2354 {
2355   if (this->constant_->const_value()->expr()->classification()
2356       == EXPRESSION_IOTA)
2357     {
2358       if (iota_value == -1)
2359         {
2360           error_at(this->location(),
2361                    "iota is only defined in const declarations");
2362           iota_value = 0;
2363         }
2364       mpz_t val;
2365       mpz_init_set_ui(val, static_cast<unsigned long>(iota_value));
2366       Expression* ret = Expression::make_integer(&val, NULL,
2367                                                  this->location());
2368       mpz_clear(val);
2369       return ret;
2370     }
2371
2372   // Make sure that the constant itself has been lowered.
2373   gogo->lower_constant(this->constant_);
2374
2375   return this;
2376 }
2377
2378 // Return an integer constant value.
2379
2380 bool
2381 Const_expression::do_integer_constant_value(bool iota_is_constant, mpz_t val,
2382                                             Type** ptype) const
2383 {
2384   Type* ctype;
2385   if (this->type_ != NULL)
2386     ctype = this->type_;
2387   else
2388     ctype = this->constant_->const_value()->type();
2389   if (ctype != NULL && ctype->integer_type() == NULL)
2390     return false;
2391
2392   Expression* e = this->constant_->const_value()->expr();
2393   Type* t;
2394   bool r = e->integer_constant_value(iota_is_constant, val, &t);
2395
2396   if (r
2397       && ctype != NULL
2398       && !Integer_expression::check_constant(val, ctype, this->location()))
2399     return false;
2400
2401   *ptype = ctype != NULL ? ctype : t;
2402   return r;
2403 }
2404
2405 // Return a floating point constant value.
2406
2407 bool
2408 Const_expression::do_float_constant_value(mpfr_t val, Type** ptype) const
2409 {
2410   Type* ctype;
2411   if (this->type_ != NULL)
2412     ctype = this->type_;
2413   else
2414     ctype = this->constant_->const_value()->type();
2415   if (ctype != NULL && ctype->float_type() == NULL)
2416     return false;
2417
2418   Type* t;
2419   bool r = this->constant_->const_value()->expr()->float_constant_value(val,
2420                                                                         &t);
2421   if (r && ctype != NULL)
2422     {
2423       if (!Float_expression::check_constant(val, ctype, this->location()))
2424         return false;
2425       Float_expression::constrain_float(val, ctype);
2426     }
2427   *ptype = ctype != NULL ? ctype : t;
2428   return r;
2429 }
2430
2431 // Return a complex constant value.
2432
2433 bool
2434 Const_expression::do_complex_constant_value(mpfr_t real, mpfr_t imag,
2435                                             Type **ptype) const
2436 {
2437   Type* ctype;
2438   if (this->type_ != NULL)
2439     ctype = this->type_;
2440   else
2441     ctype = this->constant_->const_value()->type();
2442   if (ctype != NULL && ctype->complex_type() == NULL)
2443     return false;
2444
2445   Type *t;
2446   bool r = this->constant_->const_value()->expr()->complex_constant_value(real,
2447                                                                           imag,
2448                                                                           &t);
2449   if (r && ctype != NULL)
2450     {
2451       if (!Complex_expression::check_constant(real, imag, ctype,
2452                                               this->location()))
2453         return false;
2454       Complex_expression::constrain_complex(real, imag, ctype);
2455     }
2456   *ptype = ctype != NULL ? ctype : t;
2457   return r;
2458 }
2459
2460 // Return the type of the const reference.
2461
2462 Type*
2463 Const_expression::do_type()
2464 {
2465   if (this->type_ != NULL)
2466     return this->type_;
2467   Named_constant* nc = this->constant_->const_value();
2468   Type* ret = nc->type();
2469   if (ret != NULL)
2470     return ret;
2471   // During parsing, a named constant may have a NULL type, but we
2472   // must not return a NULL type here.
2473   return nc->expr()->type();
2474 }
2475
2476 // Set the type of the const reference.
2477
2478 void
2479 Const_expression::do_determine_type(const Type_context* context)
2480 {
2481   Type* ctype = this->constant_->const_value()->type();
2482   Type* cetype = (ctype != NULL
2483                   ? ctype
2484                   : this->constant_->const_value()->expr()->type());
2485   if (ctype != NULL && !ctype->is_abstract())
2486     ;
2487   else if (context->type != NULL
2488            && (context->type->integer_type() != NULL
2489                || context->type->float_type() != NULL
2490                || context->type->complex_type() != NULL)
2491            && (cetype->integer_type() != NULL
2492                || cetype->float_type() != NULL
2493                || cetype->complex_type() != NULL))
2494     this->type_ = context->type;
2495   else if (context->type != NULL
2496            && context->type->is_string_type()
2497            && cetype->is_string_type())
2498     this->type_ = context->type;
2499   else if (context->type != NULL
2500            && context->type->is_boolean_type()
2501            && cetype->is_boolean_type())
2502     this->type_ = context->type;
2503   else if (!context->may_be_abstract)
2504     {
2505       if (cetype->is_abstract())
2506         cetype = cetype->make_non_abstract_type();
2507       this->type_ = cetype;
2508     }
2509 }
2510
2511 // Check types of a const reference.
2512
2513 void
2514 Const_expression::do_check_types(Gogo*)
2515 {
2516   if (this->type_ == NULL || this->type_->is_abstract())
2517     return;
2518
2519   // Check for integer overflow.
2520   if (this->type_->integer_type() != NULL)
2521     {
2522       mpz_t ival;
2523       mpz_init(ival);
2524       Type* dummy;
2525       if (!this->integer_constant_value(true, ival, &dummy))
2526         {
2527           mpfr_t fval;
2528           mpfr_init(fval);
2529           Expression* cexpr = this->constant_->const_value()->expr();
2530           if (cexpr->float_constant_value(fval, &dummy))
2531             {
2532               if (!mpfr_integer_p(fval))
2533                 this->report_error(_("floating point constant "
2534                                      "truncated to integer"));
2535               else
2536                 {
2537                   mpfr_get_z(ival, fval, GMP_RNDN);
2538                   Integer_expression::check_constant(ival, this->type_,
2539                                                      this->location());
2540                 }
2541             }
2542           mpfr_clear(fval);
2543         }
2544       mpz_clear(ival);
2545     }
2546 }
2547
2548 // Return a tree for the const reference.
2549
2550 tree
2551 Const_expression::do_get_tree(Translate_context* context)
2552 {
2553   Gogo* gogo = context->gogo();
2554   tree type_tree;
2555   if (this->type_ == NULL)
2556     type_tree = NULL_TREE;
2557   else
2558     {
2559       type_tree = this->type_->get_tree(gogo);
2560       if (type_tree == error_mark_node)
2561         return error_mark_node;
2562     }
2563
2564   // If the type has been set for this expression, but the underlying
2565   // object is an abstract int or float, we try to get the abstract
2566   // value.  Otherwise we may lose something in the conversion.
2567   if (this->type_ != NULL
2568       && this->constant_->const_value()->type()->is_abstract())
2569     {
2570       Expression* expr = this->constant_->const_value()->expr();
2571       mpz_t ival;
2572       mpz_init(ival);
2573       Type* t;
2574       if (expr->integer_constant_value(true, ival, &t))
2575         {
2576           tree ret = Expression::integer_constant_tree(ival, type_tree);
2577           mpz_clear(ival);
2578           return ret;
2579         }
2580       mpz_clear(ival);
2581
2582       mpfr_t fval;
2583       mpfr_init(fval);
2584       if (expr->float_constant_value(fval, &t))
2585         {
2586           tree ret = Expression::float_constant_tree(fval, type_tree);
2587           mpfr_clear(fval);
2588           return ret;
2589         }
2590
2591       mpfr_t imag;
2592       mpfr_init(imag);
2593       if (expr->complex_constant_value(fval, imag, &t))
2594         {
2595           tree ret = Expression::complex_constant_tree(fval, imag, type_tree);
2596           mpfr_clear(fval);
2597           mpfr_clear(imag);
2598           return ret;
2599         }
2600       mpfr_clear(imag);
2601       mpfr_clear(fval);
2602     }
2603
2604   tree const_tree = this->constant_->get_tree(gogo, context->function());
2605   if (this->type_ == NULL
2606       || const_tree == error_mark_node
2607       || TREE_TYPE(const_tree) == error_mark_node)
2608     return const_tree;
2609
2610   tree ret;
2611   if (TYPE_MAIN_VARIANT(type_tree) == TYPE_MAIN_VARIANT(TREE_TYPE(const_tree)))
2612     ret = fold_convert(type_tree, const_tree);
2613   else if (TREE_CODE(type_tree) == INTEGER_TYPE)
2614     ret = fold(convert_to_integer(type_tree, const_tree));
2615   else if (TREE_CODE(type_tree) == REAL_TYPE)
2616     ret = fold(convert_to_real(type_tree, const_tree));
2617   else if (TREE_CODE(type_tree) == COMPLEX_TYPE)
2618     ret = fold(convert_to_complex(type_tree, const_tree));
2619   else
2620     gcc_unreachable();
2621   return ret;
2622 }
2623
2624 // Make a reference to a constant in an expression.
2625
2626 Expression*
2627 Expression::make_const_reference(Named_object* constant,
2628                                  source_location location)
2629 {
2630   return new Const_expression(constant, location);
2631 }
2632
2633 // The nil value.
2634
2635 class Nil_expression : public Expression
2636 {
2637  public:
2638   Nil_expression(source_location location)
2639     : Expression(EXPRESSION_NIL, location)
2640   { }
2641
2642   static Expression*
2643   do_import(Import*);
2644
2645  protected:
2646   bool
2647   do_is_constant() const
2648   { return true; }
2649
2650   Type*
2651   do_type()
2652   { return Type::make_nil_type(); }
2653
2654   void
2655   do_determine_type(const Type_context*)
2656   { }
2657
2658   Expression*
2659   do_copy()
2660   { return this; }
2661
2662   tree
2663   do_get_tree(Translate_context*)
2664   { return null_pointer_node; }
2665
2666   void
2667   do_export(Export* exp) const
2668   { exp->write_c_string("nil"); }
2669 };
2670
2671 // Import a nil expression.
2672
2673 Expression*
2674 Nil_expression::do_import(Import* imp)
2675 {
2676   imp->require_c_string("nil");
2677   return Expression::make_nil(imp->location());
2678 }
2679
2680 // Make a nil expression.
2681
2682 Expression*
2683 Expression::make_nil(source_location location)
2684 {
2685   return new Nil_expression(location);
2686 }
2687
2688 // The value of the predeclared constant iota.  This is little more
2689 // than a marker.  This will be lowered to an integer in
2690 // Const_expression::do_lower, which is where we know the value that
2691 // it should have.
2692
2693 class Iota_expression : public Parser_expression
2694 {
2695  public:
2696   Iota_expression(source_location location)
2697     : Parser_expression(EXPRESSION_IOTA, location)
2698   { }
2699
2700  protected:
2701   Expression*
2702   do_lower(Gogo*, Named_object*, int)
2703   { gcc_unreachable(); }
2704
2705   // There should only ever be one of these.
2706   Expression*
2707   do_copy()
2708   { gcc_unreachable(); }
2709 };
2710
2711 // Make an iota expression.  This is only called for one case: the
2712 // value of the predeclared constant iota.
2713
2714 Expression*
2715 Expression::make_iota()
2716 {
2717   static Iota_expression iota_expression(UNKNOWN_LOCATION);
2718   return &iota_expression;
2719 }
2720
2721 // A type conversion expression.
2722
2723 class Type_conversion_expression : public Expression
2724 {
2725  public:
2726   Type_conversion_expression(Type* type, Expression* expr,
2727                              source_location location)
2728     : Expression(EXPRESSION_CONVERSION, location),
2729       type_(type), expr_(expr), may_convert_function_types_(false)
2730   { }
2731
2732   // Return the type to which we are converting.
2733   Type*
2734   type() const
2735   { return this->type_; }
2736
2737   // Return the expression which we are converting.
2738   Expression*
2739   expr() const
2740   { return this->expr_; }
2741
2742   // Permit converting from one function type to another.  This is
2743   // used internally for method expressions.
2744   void
2745   set_may_convert_function_types()
2746   {
2747     this->may_convert_function_types_ = true;
2748   }
2749
2750   // Import a type conversion expression.
2751   static Expression*
2752   do_import(Import*);
2753
2754  protected:
2755   int
2756   do_traverse(Traverse* traverse);
2757
2758   Expression*
2759   do_lower(Gogo*, Named_object*, int);
2760
2761   bool
2762   do_is_constant() const
2763   { return this->expr_->is_constant(); }
2764
2765   bool
2766   do_integer_constant_value(bool, mpz_t, Type**) const;
2767
2768   bool
2769   do_float_constant_value(mpfr_t, Type**) const;
2770
2771   bool
2772   do_complex_constant_value(mpfr_t, mpfr_t, Type**) const;
2773
2774   bool
2775   do_string_constant_value(std::string*) const;
2776
2777   Type*
2778   do_type()
2779   { return this->type_; }
2780
2781   void
2782   do_determine_type(const Type_context*)
2783   {
2784     Type_context subcontext(this->type_, false);
2785     this->expr_->determine_type(&subcontext);
2786   }
2787
2788   void
2789   do_check_types(Gogo*);
2790
2791   Expression*
2792   do_copy()
2793   {
2794     return new Type_conversion_expression(this->type_, this->expr_->copy(),
2795                                           this->location());
2796   }
2797
2798   tree
2799   do_get_tree(Translate_context* context);
2800
2801   void
2802   do_export(Export*) const;
2803
2804  private:
2805   // The type to convert to.
2806   Type* type_;
2807   // The expression to convert.
2808   Expression* expr_;
2809   // True if this is permitted to convert function types.  This is
2810   // used internally for method expressions.
2811   bool may_convert_function_types_;
2812 };
2813
2814 // Traversal.
2815
2816 int
2817 Type_conversion_expression::do_traverse(Traverse* traverse)
2818 {
2819   if (Expression::traverse(&this->expr_, traverse) == TRAVERSE_EXIT
2820       || Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
2821     return TRAVERSE_EXIT;
2822   return TRAVERSE_CONTINUE;
2823 }
2824
2825 // Convert to a constant at lowering time.
2826
2827 Expression*
2828 Type_conversion_expression::do_lower(Gogo*, Named_object*, int)
2829 {
2830   Type* type = this->type_;
2831   Expression* val = this->expr_;
2832   source_location location = this->location();
2833
2834   if (type->integer_type() != NULL)
2835     {
2836       mpz_t ival;
2837       mpz_init(ival);
2838       Type* dummy;
2839       if (val->integer_constant_value(false, ival, &dummy))
2840         {
2841           if (!Integer_expression::check_constant(ival, type, location))
2842             mpz_set_ui(ival, 0);
2843           Expression* ret = Expression::make_integer(&ival, type, location);
2844           mpz_clear(ival);
2845           return ret;
2846         }
2847
2848       mpfr_t fval;
2849       mpfr_init(fval);
2850       if (val->float_constant_value(fval, &dummy))
2851         {
2852           if (!mpfr_integer_p(fval))
2853             {
2854               error_at(location,
2855                        "floating point constant truncated to integer");
2856               return Expression::make_error(location);
2857             }
2858           mpfr_get_z(ival, fval, GMP_RNDN);
2859           if (!Integer_expression::check_constant(ival, type, location))
2860             mpz_set_ui(ival, 0);
2861           Expression* ret = Expression::make_integer(&ival, type, location);
2862           mpfr_clear(fval);
2863           mpz_clear(ival);
2864           return ret;
2865         }
2866       mpfr_clear(fval);
2867       mpz_clear(ival);
2868     }
2869
2870   if (type->float_type() != NULL)
2871     {
2872       mpfr_t fval;
2873       mpfr_init(fval);
2874       Type* dummy;
2875       if (val->float_constant_value(fval, &dummy))
2876         {
2877           if (!Float_expression::check_constant(fval, type, location))
2878             mpfr_set_ui(fval, 0, GMP_RNDN);
2879           Float_expression::constrain_float(fval, type);
2880           Expression *ret = Expression::make_float(&fval, type, location);
2881           mpfr_clear(fval);
2882           return ret;
2883         }
2884       mpfr_clear(fval);
2885     }
2886
2887   if (type->complex_type() != NULL)
2888     {
2889       mpfr_t real;
2890       mpfr_t imag;
2891       mpfr_init(real);
2892       mpfr_init(imag);
2893       Type* dummy;
2894       if (val->complex_constant_value(real, imag, &dummy))
2895         {
2896           if (!Complex_expression::check_constant(real, imag, type, location))
2897             {
2898               mpfr_set_ui(real, 0, GMP_RNDN);
2899               mpfr_set_ui(imag, 0, GMP_RNDN);
2900             }
2901           Complex_expression::constrain_complex(real, imag, type);
2902           Expression* ret = Expression::make_complex(&real, &imag, type,
2903                                                      location);
2904           mpfr_clear(real);
2905           mpfr_clear(imag);
2906           return ret;
2907         }
2908       mpfr_clear(real);
2909       mpfr_clear(imag);
2910     }
2911
2912   if (type->is_open_array_type() && type->named_type() == NULL)
2913     {
2914       Type* element_type = type->array_type()->element_type()->forwarded();
2915       bool is_byte = element_type == Type::lookup_integer_type("uint8");
2916       bool is_int = element_type == Type::lookup_integer_type("int");
2917       if (is_byte || is_int)
2918         {
2919           std::string s;
2920           if (val->string_constant_value(&s))
2921             {
2922               Expression_list* vals = new Expression_list();
2923               if (is_byte)
2924                 {
2925                   for (std::string::const_iterator p = s.begin();
2926                        p != s.end();
2927                        p++)
2928                     {
2929                       mpz_t val;
2930                       mpz_init_set_ui(val, static_cast<unsigned char>(*p));
2931                       Expression* v = Expression::make_integer(&val,
2932                                                                element_type,
2933                                                                location);
2934                       vals->push_back(v);
2935                       mpz_clear(val);
2936                     }
2937                 }
2938               else
2939                 {
2940                   const char *p = s.data();
2941                   const char *pend = s.data() + s.length();
2942                   while (p < pend)
2943                     {
2944                       unsigned int c;
2945                       int adv = Lex::fetch_char(p, &c);
2946                       if (adv == 0)
2947                         {
2948                           warning_at(this->location(), 0,
2949                                      "invalid UTF-8 encoding");
2950                           adv = 1;
2951                         }
2952                       p += adv;
2953                       mpz_t val;
2954                       mpz_init_set_ui(val, c);
2955                       Expression* v = Expression::make_integer(&val,
2956                                                                element_type,
2957                                                                location);
2958                       vals->push_back(v);
2959                       mpz_clear(val);
2960                     }
2961                 }
2962
2963               return Expression::make_slice_composite_literal(type, vals,
2964                                                               location);
2965             }
2966         }
2967     }
2968
2969   return this;
2970 }
2971
2972 // Return the constant integer value if there is one.
2973
2974 bool
2975 Type_conversion_expression::do_integer_constant_value(bool iota_is_constant,
2976                                                       mpz_t val,
2977                                                       Type** ptype) const
2978 {
2979   if (this->type_->integer_type() == NULL)
2980     return false;
2981
2982   mpz_t ival;
2983   mpz_init(ival);
2984   Type* dummy;
2985   if (this->expr_->integer_constant_value(iota_is_constant, ival, &dummy))
2986     {
2987       if (!Integer_expression::check_constant(ival, this->type_,
2988                                               this->location()))
2989         {
2990           mpz_clear(ival);
2991           return false;
2992         }
2993       mpz_set(val, ival);
2994       mpz_clear(ival);
2995       *ptype = this->type_;
2996       return true;
2997     }
2998   mpz_clear(ival);
2999
3000   mpfr_t fval;
3001   mpfr_init(fval);
3002   if (this->expr_->float_constant_value(fval, &dummy))
3003     {
3004       mpfr_get_z(val, fval, GMP_RNDN);
3005       mpfr_clear(fval);
3006       if (!Integer_expression::check_constant(val, this->type_,
3007                                               this->location()))
3008         return false;
3009       *ptype = this->type_;
3010       return true;
3011     }
3012   mpfr_clear(fval);
3013
3014   return false;
3015 }
3016
3017 // Return the constant floating point value if there is one.
3018
3019 bool
3020 Type_conversion_expression::do_float_constant_value(mpfr_t val,
3021                                                     Type** ptype) const
3022 {
3023   if (this->type_->float_type() == NULL)
3024     return false;
3025
3026   mpfr_t fval;
3027   mpfr_init(fval);
3028   Type* dummy;
3029   if (this->expr_->float_constant_value(fval, &dummy))
3030     {
3031       if (!Float_expression::check_constant(fval, this->type_,
3032                                             this->location()))
3033         {
3034           mpfr_clear(fval);
3035           return false;
3036         }
3037       mpfr_set(val, fval, GMP_RNDN);
3038       mpfr_clear(fval);
3039       Float_expression::constrain_float(val, this->type_);
3040       *ptype = this->type_;
3041       return true;
3042     }
3043   mpfr_clear(fval);
3044
3045   return false;
3046 }
3047
3048 // Return the constant complex value if there is one.
3049
3050 bool
3051 Type_conversion_expression::do_complex_constant_value(mpfr_t real,
3052                                                       mpfr_t imag,
3053                                                       Type **ptype) const
3054 {
3055   if (this->type_->complex_type() == NULL)
3056     return false;
3057
3058   mpfr_t rval;
3059   mpfr_t ival;
3060   mpfr_init(rval);
3061   mpfr_init(ival);
3062   Type* dummy;
3063   if (this->expr_->complex_constant_value(rval, ival, &dummy))
3064     {
3065       if (!Complex_expression::check_constant(rval, ival, this->type_,
3066                                               this->location()))
3067         {
3068           mpfr_clear(rval);
3069           mpfr_clear(ival);
3070           return false;
3071         }
3072       mpfr_set(real, rval, GMP_RNDN);
3073       mpfr_set(imag, ival, GMP_RNDN);
3074       mpfr_clear(rval);
3075       mpfr_clear(ival);
3076       Complex_expression::constrain_complex(real, imag, this->type_);
3077       *ptype = this->type_;
3078       return true;
3079     }
3080   mpfr_clear(rval);
3081   mpfr_clear(ival);
3082
3083   return false;
3084 }
3085
3086 // Return the constant string value if there is one.
3087
3088 bool
3089 Type_conversion_expression::do_string_constant_value(std::string* val) const
3090 {
3091   if (this->type_->is_string_type()
3092       && this->expr_->type()->integer_type() != NULL)
3093     {
3094       mpz_t ival;
3095       mpz_init(ival);
3096       Type* dummy;
3097       if (this->expr_->integer_constant_value(false, ival, &dummy))
3098         {
3099           unsigned long ulval = mpz_get_ui(ival);
3100           if (mpz_cmp_ui(ival, ulval) == 0)
3101             {
3102               Lex::append_char(ulval, true, val, this->location());
3103               mpz_clear(ival);
3104               return true;
3105             }
3106         }
3107       mpz_clear(ival);
3108     }
3109
3110   // FIXME: Could handle conversion from const []int here.
3111
3112   return false;
3113 }
3114
3115 // Check that types are convertible.
3116
3117 void
3118 Type_conversion_expression::do_check_types(Gogo*)
3119 {
3120   Type* type = this->type_;
3121   Type* expr_type = this->expr_->type();
3122   std::string reason;
3123
3124   if (this->may_convert_function_types_
3125       && type->function_type() != NULL
3126       && expr_type->function_type() != NULL)
3127     return;
3128
3129   if (Type::are_convertible(type, expr_type, &reason))
3130     return;
3131
3132   error_at(this->location(), "%s", reason.c_str());
3133   this->set_is_error();
3134 }
3135
3136 // Get a tree for a type conversion.
3137
3138 tree
3139 Type_conversion_expression::do_get_tree(Translate_context* context)
3140 {
3141   Gogo* gogo = context->gogo();
3142   tree type_tree = this->type_->get_tree(gogo);
3143   tree expr_tree = this->expr_->get_tree(context);
3144
3145   if (type_tree == error_mark_node
3146       || expr_tree == error_mark_node
3147       || TREE_TYPE(expr_tree) == error_mark_node)
3148     return error_mark_node;
3149
3150   if (TYPE_MAIN_VARIANT(type_tree) == TYPE_MAIN_VARIANT(TREE_TYPE(expr_tree)))
3151     return fold_convert(type_tree, expr_tree);
3152
3153   Type* type = this->type_;
3154   Type* expr_type = this->expr_->type();
3155   tree ret;
3156   if (type->interface_type() != NULL || expr_type->interface_type() != NULL)
3157     ret = Expression::convert_for_assignment(context, type, expr_type,
3158                                              expr_tree, this->location());
3159   else if (type->integer_type() != NULL)
3160     {
3161       if (expr_type->integer_type() != NULL
3162           || expr_type->float_type() != NULL
3163           || expr_type->is_unsafe_pointer_type())
3164         ret = fold(convert_to_integer(type_tree, expr_tree));
3165       else
3166         gcc_unreachable();
3167     }
3168   else if (type->float_type() != NULL)
3169     {
3170       if (expr_type->integer_type() != NULL
3171           || expr_type->float_type() != NULL)
3172         ret = fold(convert_to_real(type_tree, expr_tree));
3173       else
3174         gcc_unreachable();
3175     }
3176   else if (type->complex_type() != NULL)
3177     {
3178       if (expr_type->complex_type() != NULL)
3179         ret = fold(convert_to_complex(type_tree, expr_tree));
3180       else
3181         gcc_unreachable();
3182     }
3183   else if (type->is_string_type()
3184            && expr_type->integer_type() != NULL)
3185     {
3186       expr_tree = fold_convert(integer_type_node, expr_tree);
3187       if (host_integerp(expr_tree, 0))
3188         {
3189           HOST_WIDE_INT intval = tree_low_cst(expr_tree, 0);
3190           std::string s;
3191           Lex::append_char(intval, true, &s, this->location());
3192           Expression* se = Expression::make_string(s, this->location());
3193           return se->get_tree(context);
3194         }
3195
3196       static tree int_to_string_fndecl;
3197       ret = Gogo::call_builtin(&int_to_string_fndecl,
3198                                this->location(),
3199                                "__go_int_to_string",
3200                                1,
3201                                type_tree,
3202                                integer_type_node,
3203                                fold_convert(integer_type_node, expr_tree));
3204     }
3205   else if (type->is_string_type()
3206            && (expr_type->array_type() != NULL
3207                || (expr_type->points_to() != NULL
3208                    && expr_type->points_to()->array_type() != NULL)))
3209     {
3210       Type* t = expr_type;
3211       if (t->points_to() != NULL)
3212         {
3213           t = t->points_to();
3214           expr_tree = build_fold_indirect_ref(expr_tree);
3215         }
3216       if (!DECL_P(expr_tree))
3217         expr_tree = save_expr(expr_tree);
3218       Array_type* a = t->array_type();
3219       Type* e = a->element_type()->forwarded();
3220       gcc_assert(e->integer_type() != NULL);
3221       tree valptr = fold_convert(const_ptr_type_node,
3222                                  a->value_pointer_tree(gogo, expr_tree));
3223       tree len = a->length_tree(gogo, expr_tree);
3224       len = fold_convert_loc(this->location(), size_type_node, len);
3225       if (e->integer_type()->is_unsigned()
3226           && e->integer_type()->bits() == 8)
3227         {
3228           static tree byte_array_to_string_fndecl;
3229           ret = Gogo::call_builtin(&byte_array_to_string_fndecl,
3230                                    this->location(),
3231                                    "__go_byte_array_to_string",
3232                                    2,
3233                                    type_tree,
3234                                    const_ptr_type_node,
3235                                    valptr,
3236                                    size_type_node,
3237                                    len);
3238         }
3239       else
3240         {
3241           gcc_assert(e == Type::lookup_integer_type("int"));
3242           static tree int_array_to_string_fndecl;
3243           ret = Gogo::call_builtin(&int_array_to_string_fndecl,
3244                                    this->location(),
3245                                    "__go_int_array_to_string",
3246                                    2,
3247                                    type_tree,
3248                                    const_ptr_type_node,
3249                                    valptr,
3250                                    size_type_node,
3251                                    len);
3252         }
3253     }
3254   else if (type->is_open_array_type() && expr_type->is_string_type())
3255     {
3256       Type* e = type->array_type()->element_type()->forwarded();
3257       gcc_assert(e->integer_type() != NULL);
3258       if (e->integer_type()->is_unsigned()
3259           && e->integer_type()->bits() == 8)
3260         {
3261           static tree string_to_byte_array_fndecl;
3262           ret = Gogo::call_builtin(&string_to_byte_array_fndecl,
3263                                    this->location(),
3264                                    "__go_string_to_byte_array",
3265                                    1,
3266                                    type_tree,
3267                                    TREE_TYPE(expr_tree),
3268                                    expr_tree);
3269         }
3270       else
3271         {
3272           gcc_assert(e == Type::lookup_integer_type("int"));
3273           static tree string_to_int_array_fndecl;
3274           ret = Gogo::call_builtin(&string_to_int_array_fndecl,
3275                                    this->location(),
3276                                    "__go_string_to_int_array",
3277                                    1,
3278                                    type_tree,
3279                                    TREE_TYPE(expr_tree),
3280                                    expr_tree);
3281         }
3282     }
3283   else if ((type->is_unsafe_pointer_type()
3284             && expr_type->points_to() != NULL)
3285            || (expr_type->is_unsafe_pointer_type()
3286                && type->points_to() != NULL))
3287     ret = fold_convert(type_tree, expr_tree);
3288   else if (type->is_unsafe_pointer_type()
3289            && expr_type->integer_type() != NULL)
3290     ret = convert_to_pointer(type_tree, expr_tree);
3291   else if (this->may_convert_function_types_
3292            && type->function_type() != NULL
3293            && expr_type->function_type() != NULL)
3294     ret = fold_convert_loc(this->location(), type_tree, expr_tree);
3295   else
3296     ret = Expression::convert_for_assignment(context, type, expr_type,
3297                                              expr_tree, this->location());
3298
3299   return ret;
3300 }
3301
3302 // Output a type conversion in a constant expression.
3303
3304 void
3305 Type_conversion_expression::do_export(Export* exp) const
3306 {
3307   exp->write_c_string("convert(");
3308   exp->write_type(this->type_);
3309   exp->write_c_string(", ");
3310   this->expr_->export_expression(exp);
3311   exp->write_c_string(")");
3312 }
3313
3314 // Import a type conversion or a struct construction.
3315
3316 Expression*
3317 Type_conversion_expression::do_import(Import* imp)
3318 {
3319   imp->require_c_string("convert(");
3320   Type* type = imp->read_type();
3321   imp->require_c_string(", ");
3322   Expression* val = Expression::import_expression(imp);
3323   imp->require_c_string(")");
3324   return Expression::make_cast(type, val, imp->location());
3325 }
3326
3327 // Make a type cast expression.
3328
3329 Expression*
3330 Expression::make_cast(Type* type, Expression* val, source_location location)
3331 {
3332   if (type->is_error_type() || val->is_error_expression())
3333     return Expression::make_error(location);
3334   return new Type_conversion_expression(type, val, location);
3335 }
3336
3337 // Unary expressions.
3338
3339 class Unary_expression : public Expression
3340 {
3341  public:
3342   Unary_expression(Operator op, Expression* expr, source_location location)
3343     : Expression(EXPRESSION_UNARY, location),
3344       op_(op), escapes_(true), expr_(expr)
3345   { }
3346
3347   // Return the operator.
3348   Operator
3349   op() const
3350   { return this->op_; }
3351
3352   // Return the operand.
3353   Expression*
3354   operand() const
3355   { return this->expr_; }
3356
3357   // Record that an address expression does not escape.
3358   void
3359   set_does_not_escape()
3360   {
3361     gcc_assert(this->op_ == OPERATOR_AND);
3362     this->escapes_ = false;
3363   }
3364
3365   // Apply unary opcode OP to UVAL, setting VAL.  Return true if this
3366   // could be done, false if not.
3367   static bool
3368   eval_integer(Operator op, Type* utype, mpz_t uval, mpz_t val,
3369                source_location);
3370
3371   // Apply unary opcode OP to UVAL, setting VAL.  Return true if this
3372   // could be done, false if not.
3373   static bool
3374   eval_float(Operator op, mpfr_t uval, mpfr_t val);
3375
3376   // Apply unary opcode OP to UREAL/UIMAG, setting REAL/IMAG.  Return
3377   // true if this could be done, false if not.
3378   static bool
3379   eval_complex(Operator op, mpfr_t ureal, mpfr_t uimag, mpfr_t real,
3380                mpfr_t imag);
3381
3382   static Expression*
3383   do_import(Import*);
3384
3385  protected:
3386   int
3387   do_traverse(Traverse* traverse)
3388   { return Expression::traverse(&this->expr_, traverse); }
3389
3390   Expression*
3391   do_lower(Gogo*, Named_object*, int);
3392
3393   bool
3394   do_is_constant() const;
3395
3396   bool
3397   do_integer_constant_value(bool, mpz_t, Type**) const;
3398
3399   bool
3400   do_float_constant_value(mpfr_t, Type**) const;
3401
3402   bool
3403   do_complex_constant_value(mpfr_t, mpfr_t, Type**) const;
3404
3405   Type*
3406   do_type();
3407
3408   void
3409   do_determine_type(const Type_context*);
3410
3411   void
3412   do_check_types(Gogo*);
3413
3414   Expression*
3415   do_copy()
3416   {
3417     return Expression::make_unary(this->op_, this->expr_->copy(),
3418                                   this->location());
3419   }
3420
3421   bool
3422   do_is_addressable() const
3423   { return this->op_ == OPERATOR_MULT; }
3424
3425   tree
3426   do_get_tree(Translate_context*);
3427
3428   void
3429   do_export(Export*) const;
3430
3431  private:
3432   // The unary operator to apply.
3433   Operator op_;
3434   // Normally true.  False if this is an address expression which does
3435   // not escape the current function.
3436   bool escapes_;
3437   // The operand.
3438   Expression* expr_;
3439 };
3440
3441 // If we are taking the address of a composite literal, and the
3442 // contents are not constant, then we want to make a heap composite
3443 // instead.
3444
3445 Expression*
3446 Unary_expression::do_lower(Gogo*, Named_object*, int)
3447 {
3448   source_location loc = this->location();
3449   Operator op = this->op_;
3450   Expression* expr = this->expr_;
3451
3452   if (op == OPERATOR_MULT && expr->is_type_expression())
3453     return Expression::make_type(Type::make_pointer_type(expr->type()), loc);
3454
3455   // *&x simplifies to x.  *(*T)(unsafe.Pointer)(&x) does not require
3456   // moving x to the heap.  FIXME: Is it worth doing a real escape
3457   // analysis here?  This case is found in math/unsafe.go and is
3458   // therefore worth special casing.
3459   if (op == OPERATOR_MULT)
3460     {
3461       Expression* e = expr;
3462       while (e->classification() == EXPRESSION_CONVERSION)
3463         {
3464           Type_conversion_expression* te
3465             = static_cast<Type_conversion_expression*>(e);
3466           e = te->expr();
3467         }
3468
3469       if (e->classification() == EXPRESSION_UNARY)
3470         {
3471           Unary_expression* ue = static_cast<Unary_expression*>(e);
3472           if (ue->op_ == OPERATOR_AND)
3473             {
3474               if (e == expr)
3475                 {
3476                   // *&x == x.
3477                   return ue->expr_;
3478                 }
3479               ue->set_does_not_escape();
3480             }
3481         }
3482     }
3483
3484   if (op == OPERATOR_PLUS || op == OPERATOR_MINUS
3485       || op == OPERATOR_NOT || op == OPERATOR_XOR)
3486     {
3487       Expression* ret = NULL;
3488
3489       mpz_t eval;
3490       mpz_init(eval);
3491       Type* etype;
3492       if (expr->integer_constant_value(false, eval, &etype))
3493         {
3494           mpz_t val;
3495           mpz_init(val);
3496           if (Unary_expression::eval_integer(op, etype, eval, val, loc))
3497             ret = Expression::make_integer(&val, etype, loc);
3498           mpz_clear(val);
3499         }
3500       mpz_clear(eval);
3501       if (ret != NULL)
3502         return ret;
3503
3504       if (op == OPERATOR_PLUS || op == OPERATOR_MINUS)
3505         {
3506           mpfr_t fval;
3507           mpfr_init(fval);
3508           Type* ftype;
3509           if (expr->float_constant_value(fval, &ftype))
3510             {
3511               mpfr_t val;
3512               mpfr_init(val);
3513               if (Unary_expression::eval_float(op, fval, val))
3514                 ret = Expression::make_float(&val, ftype, loc);
3515               mpfr_clear(val);
3516             }
3517           if (ret != NULL)
3518             {
3519               mpfr_clear(fval);
3520               return ret;
3521             }
3522
3523           mpfr_t ival;
3524           mpfr_init(ival);
3525           if (expr->complex_constant_value(fval, ival, &ftype))
3526             {
3527               mpfr_t real;
3528               mpfr_t imag;
3529               mpfr_init(real);
3530               mpfr_init(imag);
3531               if (Unary_expression::eval_complex(op, fval, ival, real, imag))
3532                 ret = Expression::make_complex(&real, &imag, ftype, loc);
3533               mpfr_clear(real);
3534               mpfr_clear(imag);
3535             }
3536           mpfr_clear(ival);
3537           mpfr_clear(fval);
3538           if (ret != NULL)
3539             return ret;
3540         }
3541     }
3542
3543   return this;
3544 }
3545
3546 // Return whether a unary expression is a constant.
3547
3548 bool
3549 Unary_expression::do_is_constant() const
3550 {
3551   if (this->op_ == OPERATOR_MULT)
3552     {
3553       // Indirecting through a pointer is only constant if the object
3554       // to which the expression points is constant, but we currently
3555       // have no way to determine that.
3556       return false;
3557     }
3558   else if (this->op_ == OPERATOR_AND)
3559     {
3560       // Taking the address of a variable is constant if it is a
3561       // global variable, not constant otherwise.  In other cases
3562       // taking the address is probably not a constant.
3563       Var_expression* ve = this->expr_->var_expression();
3564       if (ve != NULL)
3565         {
3566           Named_object* no = ve->named_object();
3567           return no->is_variable() && no->var_value()->is_global();
3568         }
3569       return false;
3570     }
3571   else
3572     return this->expr_->is_constant();
3573 }
3574
3575 // Apply unary opcode OP to UVAL, setting VAL.  UTYPE is the type of
3576 // UVAL, if known; it may be NULL.  Return true if this could be done,
3577 // false if not.
3578
3579 bool
3580 Unary_expression::eval_integer(Operator op, Type* utype, mpz_t uval, mpz_t val,
3581                                source_location location)
3582 {
3583   switch (op)
3584     {
3585     case OPERATOR_PLUS:
3586       mpz_set(val, uval);
3587       return true;
3588     case OPERATOR_MINUS:
3589       mpz_neg(val, uval);
3590       return Integer_expression::check_constant(val, utype, location);
3591     case OPERATOR_NOT:
3592       mpz_set_ui(val, mpz_cmp_si(uval, 0) == 0 ? 1 : 0);
3593       return true;
3594     case OPERATOR_XOR:
3595       if (utype == NULL
3596           || utype->integer_type() == NULL
3597           || utype->integer_type()->is_abstract())
3598         mpz_com(val, uval);
3599       else
3600         {
3601           // The number of HOST_WIDE_INTs that it takes to represent
3602           // UVAL.
3603           size_t count = ((mpz_sizeinbase(uval, 2)
3604                            + HOST_BITS_PER_WIDE_INT
3605                            - 1)
3606                           / HOST_BITS_PER_WIDE_INT);
3607
3608           unsigned HOST_WIDE_INT* phwi = new unsigned HOST_WIDE_INT[count];
3609           memset(phwi, 0, count * sizeof(HOST_WIDE_INT));
3610
3611           size_t ecount;
3612           mpz_export(phwi, &ecount, -1, sizeof(HOST_WIDE_INT), 0, 0, uval);
3613           gcc_assert(ecount <= count);
3614
3615           // Trim down to the number of words required by the type.
3616           size_t obits = utype->integer_type()->bits();
3617           if (!utype->integer_type()->is_unsigned())
3618             ++obits;
3619           size_t ocount = ((obits + HOST_BITS_PER_WIDE_INT - 1)
3620                            / HOST_BITS_PER_WIDE_INT);
3621           gcc_assert(ocount <= ocount);
3622
3623           for (size_t i = 0; i < ocount; ++i)
3624             phwi[i] = ~phwi[i];
3625
3626           size_t clearbits = ocount * HOST_BITS_PER_WIDE_INT - obits;
3627           if (clearbits != 0)
3628             phwi[ocount - 1] &= (((unsigned HOST_WIDE_INT) (HOST_WIDE_INT) -1)
3629                                  >> clearbits);
3630
3631           mpz_import(val, ocount, -1, sizeof(HOST_WIDE_INT), 0, 0, phwi);
3632
3633           delete[] phwi;
3634         }
3635       return Integer_expression::check_constant(val, utype, location);
3636     case OPERATOR_AND:
3637     case OPERATOR_MULT:
3638       return false;
3639     default:
3640       gcc_unreachable();
3641     }
3642 }
3643
3644 // Apply unary opcode OP to UVAL, setting VAL.  Return true if this
3645 // could be done, false if not.
3646
3647 bool
3648 Unary_expression::eval_float(Operator op, mpfr_t uval, mpfr_t val)
3649 {
3650   switch (op)
3651     {
3652     case OPERATOR_PLUS:
3653       mpfr_set(val, uval, GMP_RNDN);
3654       return true;
3655     case OPERATOR_MINUS:
3656       mpfr_neg(val, uval, GMP_RNDN);
3657       return true;
3658     case OPERATOR_NOT:
3659     case OPERATOR_XOR:
3660     case OPERATOR_AND:
3661     case OPERATOR_MULT:
3662       return false;
3663     default:
3664       gcc_unreachable();
3665     }
3666 }
3667
3668 // Apply unary opcode OP to RVAL/IVAL, setting REAL/IMAG.  Return true
3669 // if this could be done, false if not.
3670
3671 bool
3672 Unary_expression::eval_complex(Operator op, mpfr_t rval, mpfr_t ival,
3673                                mpfr_t real, mpfr_t imag)
3674 {
3675   switch (op)
3676     {
3677     case OPERATOR_PLUS:
3678       mpfr_set(real, rval, GMP_RNDN);
3679       mpfr_set(imag, ival, GMP_RNDN);
3680       return true;
3681     case OPERATOR_MINUS:
3682       mpfr_neg(real, rval, GMP_RNDN);
3683       mpfr_neg(imag, ival, GMP_RNDN);
3684       return true;
3685     case OPERATOR_NOT:
3686     case OPERATOR_XOR:
3687     case OPERATOR_AND:
3688     case OPERATOR_MULT:
3689       return false;
3690     default:
3691       gcc_unreachable();
3692     }
3693 }
3694
3695 // Return the integral constant value of a unary expression, if it has one.
3696
3697 bool
3698 Unary_expression::do_integer_constant_value(bool iota_is_constant, mpz_t val,
3699                                             Type** ptype) const
3700 {
3701   mpz_t uval;
3702   mpz_init(uval);
3703   bool ret;
3704   if (!this->expr_->integer_constant_value(iota_is_constant, uval, ptype))
3705     ret = false;
3706   else
3707     ret = Unary_expression::eval_integer(this->op_, *ptype, uval, val,
3708                                          this->location());
3709   mpz_clear(uval);
3710   return ret;
3711 }
3712
3713 // Return the floating point constant value of a unary expression, if
3714 // it has one.
3715
3716 bool
3717 Unary_expression::do_float_constant_value(mpfr_t val, Type** ptype) const
3718 {
3719   mpfr_t uval;
3720   mpfr_init(uval);
3721   bool ret;
3722   if (!this->expr_->float_constant_value(uval, ptype))
3723     ret = false;
3724   else
3725     ret = Unary_expression::eval_float(this->op_, uval, val);
3726   mpfr_clear(uval);
3727   return ret;
3728 }
3729
3730 // Return the complex constant value of a unary expression, if it has
3731 // one.
3732
3733 bool
3734 Unary_expression::do_complex_constant_value(mpfr_t real, mpfr_t imag,
3735                                             Type** ptype) const
3736 {
3737   mpfr_t rval;
3738   mpfr_t ival;
3739   mpfr_init(rval);
3740   mpfr_init(ival);
3741   bool ret;
3742   if (!this->expr_->complex_constant_value(rval, ival, ptype))
3743     ret = false;
3744   else
3745     ret = Unary_expression::eval_complex(this->op_, rval, ival, real, imag);
3746   mpfr_clear(rval);
3747   mpfr_clear(ival);
3748   return ret;
3749 }
3750
3751 // Return the type of a unary expression.
3752
3753 Type*
3754 Unary_expression::do_type()
3755 {
3756   switch (this->op_)
3757     {
3758     case OPERATOR_PLUS:
3759     case OPERATOR_MINUS:
3760     case OPERATOR_NOT:
3761     case OPERATOR_XOR:
3762       return this->expr_->type();
3763
3764     case OPERATOR_AND:
3765       return Type::make_pointer_type(this->expr_->type());
3766
3767     case OPERATOR_MULT:
3768       {
3769         Type* subtype = this->expr_->type();
3770         Type* points_to = subtype->points_to();
3771         if (points_to == NULL)
3772           return Type::make_error_type();
3773         return points_to;
3774       }
3775
3776     default:
3777       gcc_unreachable();
3778     }
3779 }
3780
3781 // Determine abstract types for a unary expression.
3782
3783 void
3784 Unary_expression::do_determine_type(const Type_context* context)
3785 {
3786   switch (this->op_)
3787     {
3788     case OPERATOR_PLUS:
3789     case OPERATOR_MINUS:
3790     case OPERATOR_NOT:
3791     case OPERATOR_XOR:
3792       this->expr_->determine_type(context);
3793       break;
3794
3795     case OPERATOR_AND:
3796       // Taking the address of something.
3797       {
3798         Type* subtype = (context->type == NULL
3799                          ? NULL
3800                          : context->type->points_to());
3801         Type_context subcontext(subtype, false);
3802         this->expr_->determine_type(&subcontext);
3803       }
3804       break;
3805
3806     case OPERATOR_MULT:
3807       // Indirecting through a pointer.
3808       {
3809         Type* subtype = (context->type == NULL
3810                          ? NULL
3811                          : Type::make_pointer_type(context->type));
3812         Type_context subcontext(subtype, false);
3813         this->expr_->determine_type(&subcontext);
3814       }
3815       break;
3816
3817     default:
3818       gcc_unreachable();
3819     }
3820 }
3821
3822 // Check types for a unary expression.
3823
3824 void
3825 Unary_expression::do_check_types(Gogo*)
3826 {
3827   switch (this->op_)
3828     {
3829     case OPERATOR_PLUS:
3830     case OPERATOR_MINUS:
3831       {
3832         Type* type = this->expr_->type();
3833         if (type->integer_type() == NULL
3834             && type->float_type() == NULL
3835             && type->complex_type() == NULL
3836             && !type->is_error_type())
3837           this->report_error(_("expected numeric type"));
3838       }
3839       break;
3840
3841     case OPERATOR_NOT:
3842     case OPERATOR_XOR:
3843       {
3844         Type* type = this->expr_->type();
3845         if (type->integer_type() == NULL
3846             && !type->is_boolean_type()
3847             && !type->is_error_type())
3848           this->report_error(_("expected integer or boolean type"));
3849       }
3850       break;
3851
3852     case OPERATOR_AND:
3853       if (!this->expr_->is_addressable())
3854         this->report_error(_("invalid operand for unary %<&%>"));
3855       else
3856         this->expr_->address_taken(this->escapes_);
3857       break;
3858
3859     case OPERATOR_MULT:
3860       // Indirecting through a pointer.
3861       {
3862         Type* type = this->expr_->type();
3863         if (type->points_to() == NULL
3864             && !type->is_error_type())
3865           this->report_error(_("expected pointer"));
3866       }
3867       break;
3868
3869     default:
3870       gcc_unreachable();
3871     }
3872 }
3873
3874 // Get a tree for a unary expression.
3875
3876 tree
3877 Unary_expression::do_get_tree(Translate_context* context)
3878 {
3879   tree expr = this->expr_->get_tree(context);
3880   if (expr == error_mark_node)
3881     return error_mark_node;
3882
3883   source_location loc = this->location();
3884   switch (this->op_)
3885     {
3886     case OPERATOR_PLUS:
3887       return expr;
3888
3889     case OPERATOR_MINUS:
3890       {
3891         tree type = TREE_TYPE(expr);
3892         tree compute_type = excess_precision_type(type);
3893         if (compute_type != NULL_TREE)
3894           expr = ::convert(compute_type, expr);
3895         tree ret = fold_build1_loc(loc, NEGATE_EXPR,
3896                                    (compute_type != NULL_TREE
3897                                     ? compute_type
3898                                     : type),
3899                                    expr);
3900         if (compute_type != NULL_TREE)
3901           ret = ::convert(type, ret);
3902         return ret;
3903       }
3904
3905     case OPERATOR_NOT:
3906       if (TREE_CODE(TREE_TYPE(expr)) == BOOLEAN_TYPE)
3907         return fold_build1_loc(loc, TRUTH_NOT_EXPR, TREE_TYPE(expr), expr);
3908       else
3909         return fold_build2_loc(loc, NE_EXPR, boolean_type_node, expr,
3910                                build_int_cst(TREE_TYPE(expr), 0));
3911
3912     case OPERATOR_XOR:
3913       return fold_build1_loc(loc, BIT_NOT_EXPR, TREE_TYPE(expr), expr);
3914
3915     case OPERATOR_AND:
3916       // We should not see a non-constant constructor here; cases
3917       // where we would see one should have been moved onto the heap
3918       // at parse time.  Taking the address of a nonconstant
3919       // constructor will not do what the programmer expects.
3920       gcc_assert(TREE_CODE(expr) != CONSTRUCTOR || TREE_CONSTANT(expr));
3921       gcc_assert(TREE_CODE(expr) != ADDR_EXPR);
3922
3923       // Build a decl for a constant constructor.
3924       if (TREE_CODE(expr) == CONSTRUCTOR && TREE_CONSTANT(expr))
3925         {
3926           tree decl = build_decl(this->location(), VAR_DECL,
3927                                  create_tmp_var_name("C"), TREE_TYPE(expr));
3928           DECL_EXTERNAL(decl) = 0;
3929           TREE_PUBLIC(decl) = 0;
3930           TREE_READONLY(decl) = 1;
3931           TREE_CONSTANT(decl) = 1;
3932           TREE_STATIC(decl) = 1;
3933           TREE_ADDRESSABLE(decl) = 1;
3934           DECL_ARTIFICIAL(decl) = 1;
3935           DECL_INITIAL(decl) = expr;
3936           rest_of_decl_compilation(decl, 1, 0);
3937           expr = decl;
3938         }
3939
3940       return build_fold_addr_expr_loc(loc, expr);
3941
3942     case OPERATOR_MULT:
3943       {
3944         gcc_assert(POINTER_TYPE_P(TREE_TYPE(expr)));
3945
3946         // If we are dereferencing the pointer to a large struct, we
3947         // need to check for nil.  We don't bother to check for small
3948         // structs because we expect the system to crash on a nil
3949         // pointer dereference.
3950         HOST_WIDE_INT s = int_size_in_bytes(TREE_TYPE(TREE_TYPE(expr)));
3951         if (s == -1 || s >= 4096)
3952           {
3953             if (!DECL_P(expr))
3954               expr = save_expr(expr);
3955             tree compare = fold_build2_loc(loc, EQ_EXPR, boolean_type_node,
3956                                            expr,
3957                                            fold_convert(TREE_TYPE(expr),
3958                                                         null_pointer_node));
3959             tree crash = Gogo::runtime_error(RUNTIME_ERROR_NIL_DEREFERENCE,
3960                                              loc);
3961             expr = fold_build2_loc(loc, COMPOUND_EXPR, TREE_TYPE(expr),
3962                                    build3(COND_EXPR, void_type_node,
3963                                           compare, crash, NULL_TREE),
3964                                    expr);
3965           }
3966
3967         // If the type of EXPR is a recursive pointer type, then we
3968         // need to insert a cast before indirecting.
3969         if (TREE_TYPE(TREE_TYPE(expr)) == ptr_type_node)
3970           {
3971             Type* pt = this->expr_->type()->points_to();
3972             tree ind = pt->get_tree(context->gogo());
3973             expr = fold_convert_loc(loc, build_pointer_type(ind), expr);
3974           }
3975
3976         return build_fold_indirect_ref_loc(loc, expr);
3977       }
3978
3979     default:
3980       gcc_unreachable();
3981     }
3982 }
3983
3984 // Export a unary expression.
3985
3986 void
3987 Unary_expression::do_export(Export* exp) const
3988 {
3989   switch (this->op_)
3990     {
3991     case OPERATOR_PLUS:
3992       exp->write_c_string("+ ");
3993       break;
3994     case OPERATOR_MINUS:
3995       exp->write_c_string("- ");
3996       break;
3997     case OPERATOR_NOT:
3998       exp->write_c_string("! ");
3999       break;
4000     case OPERATOR_XOR:
4001       exp->write_c_string("^ ");
4002       break;
4003     case OPERATOR_AND:
4004     case OPERATOR_MULT:
4005     default:
4006       gcc_unreachable();
4007     }
4008   this->expr_->export_expression(exp);
4009 }
4010
4011 // Import a unary expression.
4012
4013 Expression*
4014 Unary_expression::do_import(Import* imp)
4015 {
4016   Operator op;
4017   switch (imp->get_char())
4018     {
4019     case '+':
4020       op = OPERATOR_PLUS;
4021       break;
4022     case '-':
4023       op = OPERATOR_MINUS;
4024       break;
4025     case '!':
4026       op = OPERATOR_NOT;
4027       break;
4028     case '^':
4029       op = OPERATOR_XOR;
4030       break;
4031     default:
4032       gcc_unreachable();
4033     }
4034   imp->require_c_string(" ");
4035   Expression* expr = Expression::import_expression(imp);
4036   return Expression::make_unary(op, expr, imp->location());
4037 }
4038
4039 // Make a unary expression.
4040
4041 Expression*
4042 Expression::make_unary(Operator op, Expression* expr, source_location location)
4043 {
4044   return new Unary_expression(op, expr, location);
4045 }
4046
4047 // If this is an indirection through a pointer, return the expression
4048 // being pointed through.  Otherwise return this.
4049
4050 Expression*
4051 Expression::deref()
4052 {
4053   if (this->classification_ == EXPRESSION_UNARY)
4054     {
4055       Unary_expression* ue = static_cast<Unary_expression*>(this);
4056       if (ue->op() == OPERATOR_MULT)
4057         return ue->operand();
4058     }
4059   return this;
4060 }
4061
4062 // Class Binary_expression.
4063
4064 // Traversal.
4065
4066 int
4067 Binary_expression::do_traverse(Traverse* traverse)
4068 {
4069   int t = Expression::traverse(&this->left_, traverse);
4070   if (t == TRAVERSE_EXIT)
4071     return TRAVERSE_EXIT;
4072   return Expression::traverse(&this->right_, traverse);
4073 }
4074
4075 // Compare integer constants according to OP.
4076
4077 bool
4078 Binary_expression::compare_integer(Operator op, mpz_t left_val,
4079                                    mpz_t right_val)
4080 {
4081   int i = mpz_cmp(left_val, right_val);
4082   switch (op)
4083     {
4084     case OPERATOR_EQEQ:
4085       return i == 0;
4086     case OPERATOR_NOTEQ:
4087       return i != 0;
4088     case OPERATOR_LT:
4089       return i < 0;
4090     case OPERATOR_LE:
4091       return i <= 0;
4092     case OPERATOR_GT:
4093       return i > 0;
4094     case OPERATOR_GE:
4095       return i >= 0;
4096     default:
4097       gcc_unreachable();
4098     }
4099 }
4100
4101 // Compare floating point constants according to OP.
4102
4103 bool
4104 Binary_expression::compare_float(Operator op, Type* type, mpfr_t left_val,
4105                                  mpfr_t right_val)
4106 {
4107   int i;
4108   if (type == NULL)
4109     i = mpfr_cmp(left_val, right_val);
4110   else
4111     {
4112       mpfr_t lv;
4113       mpfr_init_set(lv, left_val, GMP_RNDN);
4114       mpfr_t rv;
4115       mpfr_init_set(rv, right_val, GMP_RNDN);
4116       Float_expression::constrain_float(lv, type);
4117       Float_expression::constrain_float(rv, type);
4118       i = mpfr_cmp(lv, rv);
4119       mpfr_clear(lv);
4120       mpfr_clear(rv);
4121     }
4122   switch (op)
4123     {
4124     case OPERATOR_EQEQ:
4125       return i == 0;
4126     case OPERATOR_NOTEQ:
4127       return i != 0;
4128     case OPERATOR_LT:
4129       return i < 0;
4130     case OPERATOR_LE:
4131       return i <= 0;
4132     case OPERATOR_GT:
4133       return i > 0;
4134     case OPERATOR_GE:
4135       return i >= 0;
4136     default:
4137       gcc_unreachable();
4138     }
4139 }
4140
4141 // Compare complex constants according to OP.  Complex numbers may
4142 // only be compared for equality.
4143
4144 bool
4145 Binary_expression::compare_complex(Operator op, Type* type,
4146                                    mpfr_t left_real, mpfr_t left_imag,
4147                                    mpfr_t right_real, mpfr_t right_imag)
4148 {
4149   bool is_equal;
4150   if (type == NULL)
4151     is_equal = (mpfr_cmp(left_real, right_real) == 0
4152                 && mpfr_cmp(left_imag, right_imag) == 0);
4153   else
4154     {
4155       mpfr_t lr;
4156       mpfr_t li;
4157       mpfr_init_set(lr, left_real, GMP_RNDN);
4158       mpfr_init_set(li, left_imag, GMP_RNDN);
4159       mpfr_t rr;
4160       mpfr_t ri;
4161       mpfr_init_set(rr, right_real, GMP_RNDN);
4162       mpfr_init_set(ri, right_imag, GMP_RNDN);
4163       Complex_expression::constrain_complex(lr, li, type);
4164       Complex_expression::constrain_complex(rr, ri, type);
4165       is_equal = mpfr_cmp(lr, rr) == 0 && mpfr_cmp(li, ri) == 0;
4166       mpfr_clear(lr);
4167       mpfr_clear(li);
4168       mpfr_clear(rr);
4169       mpfr_clear(ri);
4170     }
4171   switch (op)
4172     {
4173     case OPERATOR_EQEQ:
4174       return is_equal;
4175     case OPERATOR_NOTEQ:
4176       return !is_equal;
4177     default:
4178       gcc_unreachable();
4179     }
4180 }
4181
4182 // Apply binary opcode OP to LEFT_VAL and RIGHT_VAL, setting VAL.
4183 // LEFT_TYPE is the type of LEFT_VAL, RIGHT_TYPE is the type of
4184 // RIGHT_VAL; LEFT_TYPE and/or RIGHT_TYPE may be NULL.  Return true if
4185 // this could be done, false if not.
4186
4187 bool
4188 Binary_expression::eval_integer(Operator op, Type* left_type, mpz_t left_val,
4189                                 Type* right_type, mpz_t right_val,
4190                                 source_location location, mpz_t val)
4191 {
4192   bool is_shift_op = false;
4193   switch (op)
4194     {
4195     case OPERATOR_OROR:
4196     case OPERATOR_ANDAND:
4197     case OPERATOR_EQEQ:
4198     case OPERATOR_NOTEQ:
4199     case OPERATOR_LT:
4200     case OPERATOR_LE:
4201     case OPERATOR_GT:
4202     case OPERATOR_GE:
4203       // These return boolean values.  We should probably handle them
4204       // anyhow in case a type conversion is used on the result.
4205       return false;
4206     case OPERATOR_PLUS:
4207       mpz_add(val, left_val, right_val);
4208       break;
4209     case OPERATOR_MINUS:
4210       mpz_sub(val, left_val, right_val);
4211       break;
4212     case OPERATOR_OR:
4213       mpz_ior(val, left_val, right_val);
4214       break;
4215     case OPERATOR_XOR:
4216       mpz_xor(val, left_val, right_val);
4217       break;
4218     case OPERATOR_MULT:
4219       mpz_mul(val, left_val, right_val);
4220       break;
4221     case OPERATOR_DIV:
4222       if (mpz_sgn(right_val) != 0)
4223         mpz_tdiv_q(val, left_val, right_val);
4224       else
4225         {
4226           error_at(location, "division by zero");
4227           mpz_set_ui(val, 0);
4228           return true;
4229         }
4230       break;
4231     case OPERATOR_MOD:
4232       if (mpz_sgn(right_val) != 0)
4233         mpz_tdiv_r(val, left_val, right_val);
4234       else
4235         {
4236           error_at(location, "division by zero");
4237           mpz_set_ui(val, 0);
4238           return true;
4239         }
4240       break;
4241     case OPERATOR_LSHIFT:
4242       {
4243         unsigned long shift = mpz_get_ui(right_val);
4244         if (mpz_cmp_ui(right_val, shift) != 0)
4245           {
4246             error_at(location, "shift count overflow");
4247             mpz_set_ui(val, 0);
4248             return true;
4249           }
4250         mpz_mul_2exp(val, left_val, shift);
4251         is_shift_op = true;
4252         break;
4253       }
4254       break;
4255     case OPERATOR_RSHIFT:
4256       {
4257         unsigned long shift = mpz_get_ui(right_val);
4258         if (mpz_cmp_ui(right_val, shift) != 0)
4259           {
4260             error_at(location, "shift count overflow");
4261             mpz_set_ui(val, 0);
4262             return true;
4263           }
4264         if (mpz_cmp_ui(left_val, 0) >= 0)
4265           mpz_tdiv_q_2exp(val, left_val, shift);
4266         else
4267           mpz_fdiv_q_2exp(val, left_val, shift);
4268         is_shift_op = true;
4269         break;
4270       }
4271       break;
4272     case OPERATOR_AND:
4273       mpz_and(val, left_val, right_val);
4274       break;
4275     case OPERATOR_BITCLEAR:
4276       {
4277         mpz_t tval;
4278         mpz_init(tval);
4279         mpz_com(tval, right_val);
4280         mpz_and(val, left_val, tval);
4281         mpz_clear(tval);
4282       }
4283       break;
4284     default:
4285       gcc_unreachable();
4286     }
4287
4288   Type* type = left_type;
4289   if (!is_shift_op)
4290     {
4291       if (type == NULL)
4292         type = right_type;
4293       else if (type != right_type && right_type != NULL)
4294         {
4295           if (type->is_abstract())
4296             type = right_type;
4297           else if (!right_type->is_abstract())
4298             {
4299               // This look like a type error which should be diagnosed
4300               // elsewhere.  Don't do anything here, to avoid an
4301               // unhelpful chain of error messages.
4302               return true;
4303             }
4304         }
4305     }
4306
4307   if (type != NULL && !type->is_abstract())
4308     {
4309       // We have to check the operands too, as we have implicitly
4310       // coerced them to TYPE.
4311       if ((type != left_type
4312            && !Integer_expression::check_constant(left_val, type, location))
4313           || (!is_shift_op
4314               && type != right_type
4315               && !Integer_expression::check_constant(right_val, type,
4316                                                      location))
4317           || !Integer_expression::check_constant(val, type, location))
4318         mpz_set_ui(val, 0);
4319     }
4320
4321   return true;
4322 }
4323
4324 // Apply binary opcode OP to LEFT_VAL and RIGHT_VAL, setting VAL.
4325 // Return true if this could be done, false if not.
4326
4327 bool
4328 Binary_expression::eval_float(Operator op, Type* left_type, mpfr_t left_val,
4329                               Type* right_type, mpfr_t right_val,
4330                               mpfr_t val, source_location location)
4331 {
4332   switch (op)
4333     {
4334     case OPERATOR_OROR:
4335     case OPERATOR_ANDAND:
4336     case OPERATOR_EQEQ:
4337     case OPERATOR_NOTEQ:
4338     case OPERATOR_LT:
4339     case OPERATOR_LE:
4340     case OPERATOR_GT:
4341     case OPERATOR_GE:
4342       // These return boolean values.  We should probably handle them
4343       // anyhow in case a type conversion is used on the result.
4344       return false;
4345     case OPERATOR_PLUS:
4346       mpfr_add(val, left_val, right_val, GMP_RNDN);
4347       break;
4348     case OPERATOR_MINUS:
4349       mpfr_sub(val, left_val, right_val, GMP_RNDN);
4350       break;
4351     case OPERATOR_OR:
4352     case OPERATOR_XOR:
4353     case OPERATOR_AND:
4354     case OPERATOR_BITCLEAR:
4355       return false;
4356     case OPERATOR_MULT:
4357       mpfr_mul(val, left_val, right_val, GMP_RNDN);
4358       break;
4359     case OPERATOR_DIV:
4360       if (mpfr_zero_p(right_val))
4361         error_at(location, "division by zero");
4362       mpfr_div(val, left_val, right_val, GMP_RNDN);
4363       break;
4364     case OPERATOR_MOD:
4365       return false;
4366     case OPERATOR_LSHIFT:
4367     case OPERATOR_RSHIFT:
4368       return false;
4369     default:
4370       gcc_unreachable();
4371     }
4372
4373   Type* type = left_type;
4374   if (type == NULL)
4375     type = right_type;
4376   else if (type != right_type && right_type != NULL)
4377     {
4378       if (type->is_abstract())
4379         type = right_type;
4380       else if (!right_type->is_abstract())
4381         {
4382           // This looks like a type error which should be diagnosed
4383           // elsewhere.  Don't do anything here, to avoid an unhelpful
4384           // chain of error messages.
4385           return true;
4386         }
4387     }
4388
4389   if (type != NULL && !type->is_abstract())
4390     {
4391       if ((type != left_type
4392            && !Float_expression::check_constant(left_val, type, location))
4393           || (type != right_type
4394               && !Float_expression::check_constant(right_val, type,
4395                                                    location))
4396           || !Float_expression::check_constant(val, type, location))
4397         mpfr_set_ui(val, 0, GMP_RNDN);
4398     }
4399
4400   return true;
4401 }
4402
4403 // Apply binary opcode OP to LEFT_REAL/LEFT_IMAG and
4404 // RIGHT_REAL/RIGHT_IMAG, setting REAL/IMAG.  Return true if this
4405 // could be done, false if not.
4406
4407 bool
4408 Binary_expression::eval_complex(Operator op, Type* left_type,
4409                                 mpfr_t left_real, mpfr_t left_imag,
4410                                 Type *right_type,
4411                                 mpfr_t right_real, mpfr_t right_imag,
4412                                 mpfr_t real, mpfr_t imag,
4413                                 source_location location)
4414 {
4415   switch (op)
4416     {
4417     case OPERATOR_OROR:
4418     case OPERATOR_ANDAND:
4419     case OPERATOR_EQEQ:
4420     case OPERATOR_NOTEQ:
4421     case OPERATOR_LT:
4422     case OPERATOR_LE:
4423     case OPERATOR_GT:
4424     case OPERATOR_GE:
4425       // These return boolean values and must be handled differently.
4426       return false;
4427     case OPERATOR_PLUS:
4428       mpfr_add(real, left_real, right_real, GMP_RNDN);
4429       mpfr_add(imag, left_imag, right_imag, GMP_RNDN);
4430       break;
4431     case OPERATOR_MINUS:
4432       mpfr_sub(real, left_real, right_real, GMP_RNDN);
4433       mpfr_sub(imag, left_imag, right_imag, GMP_RNDN);
4434       break;
4435     case OPERATOR_OR:
4436     case OPERATOR_XOR:
4437     case OPERATOR_AND:
4438     case OPERATOR_BITCLEAR:
4439       return false;
4440     case OPERATOR_MULT:
4441       {
4442         // You might think that multiplying two complex numbers would
4443         // be simple, and you would be right, until you start to think
4444         // about getting the right answer for infinity.  If one
4445         // operand here is infinity and the other is anything other
4446         // than zero or NaN, then we are going to wind up subtracting
4447         // two infinity values.  That will give us a NaN, but the
4448         // correct answer is infinity.
4449
4450         mpfr_t lrrr;
4451         mpfr_init(lrrr);
4452         mpfr_mul(lrrr, left_real, right_real, GMP_RNDN);
4453
4454         mpfr_t lrri;
4455         mpfr_init(lrri);
4456         mpfr_mul(lrri, left_real, right_imag, GMP_RNDN);
4457
4458         mpfr_t lirr;
4459         mpfr_init(lirr);
4460         mpfr_mul(lirr, left_imag, right_real, GMP_RNDN);
4461
4462         mpfr_t liri;
4463         mpfr_init(liri);
4464         mpfr_mul(liri, left_imag, right_imag, GMP_RNDN);
4465
4466         mpfr_sub(real, lrrr, liri, GMP_RNDN);
4467         mpfr_add(imag, lrri, lirr, GMP_RNDN);
4468
4469         // If we get NaN on both sides, check whether it should really
4470         // be infinity.  The rule is that if either side of the
4471         // complex number is infinity, then the whole value is
4472         // infinity, even if the other side is NaN.  So the only case
4473         // we have to fix is the one in which both sides are NaN.
4474         if (mpfr_nan_p(real) && mpfr_nan_p(imag)
4475             && (!mpfr_nan_p(left_real) || !mpfr_nan_p(left_imag))
4476             && (!mpfr_nan_p(right_real) || !mpfr_nan_p(right_imag)))
4477           {
4478             bool is_infinity = false;
4479
4480             mpfr_t lr;
4481             mpfr_t li;
4482             mpfr_init_set(lr, left_real, GMP_RNDN);
4483             mpfr_init_set(li, left_imag, GMP_RNDN);
4484
4485             mpfr_t rr;
4486             mpfr_t ri;
4487             mpfr_init_set(rr, right_real, GMP_RNDN);
4488             mpfr_init_set(ri, right_imag, GMP_RNDN);
4489
4490             // If the left side is infinity, then the result is
4491             // infinity.
4492             if (mpfr_inf_p(lr) || mpfr_inf_p(li))
4493               {
4494                 mpfr_set_ui(lr, mpfr_inf_p(lr) ? 1 : 0, GMP_RNDN);
4495                 mpfr_copysign(lr, lr, left_real, GMP_RNDN);
4496                 mpfr_set_ui(li, mpfr_inf_p(li) ? 1 : 0, GMP_RNDN);
4497                 mpfr_copysign(li, li, left_imag, GMP_RNDN);
4498                 if (mpfr_nan_p(rr))
4499                   {
4500                     mpfr_set_ui(rr, 0, GMP_RNDN);
4501                     mpfr_copysign(rr, rr, right_real, GMP_RNDN);
4502                   }
4503                 if (mpfr_nan_p(ri))
4504                   {
4505                     mpfr_set_ui(ri, 0, GMP_RNDN);
4506                     mpfr_copysign(ri, ri, right_imag, GMP_RNDN);
4507                   }
4508                 is_infinity = true;
4509               }
4510
4511             // If the right side is infinity, then the result is
4512             // infinity.
4513             if (mpfr_inf_p(rr) || mpfr_inf_p(ri))
4514               {
4515                 mpfr_set_ui(rr, mpfr_inf_p(rr) ? 1 : 0, GMP_RNDN);
4516                 mpfr_copysign(rr, rr, right_real, GMP_RNDN);
4517                 mpfr_set_ui(ri, mpfr_inf_p(ri) ? 1 : 0, GMP_RNDN);
4518                 mpfr_copysign(ri, ri, right_imag, GMP_RNDN);
4519                 if (mpfr_nan_p(lr))
4520                   {
4521                     mpfr_set_ui(lr, 0, GMP_RNDN);
4522                     mpfr_copysign(lr, lr, left_real, GMP_RNDN);
4523                   }
4524                 if (mpfr_nan_p(li))
4525                   {
4526                     mpfr_set_ui(li, 0, GMP_RNDN);
4527                     mpfr_copysign(li, li, left_imag, GMP_RNDN);
4528                   }
4529                 is_infinity = true;
4530               }
4531
4532             // If we got an overflow in the intermediate computations,
4533             // then the result is infinity.
4534             if (!is_infinity
4535                 && (mpfr_inf_p(lrrr) || mpfr_inf_p(lrri)
4536                     || mpfr_inf_p(lirr) || mpfr_inf_p(liri)))
4537               {
4538                 if (mpfr_nan_p(lr))
4539                   {
4540                     mpfr_set_ui(lr, 0, GMP_RNDN);
4541                     mpfr_copysign(lr, lr, left_real, GMP_RNDN);
4542                   }
4543                 if (mpfr_nan_p(li))
4544                   {
4545                     mpfr_set_ui(li, 0, GMP_RNDN);
4546                     mpfr_copysign(li, li, left_imag, GMP_RNDN);
4547                   }
4548                 if (mpfr_nan_p(rr))
4549                   {
4550                     mpfr_set_ui(rr, 0, GMP_RNDN);
4551                     mpfr_copysign(rr, rr, right_real, GMP_RNDN);
4552                   }
4553                 if (mpfr_nan_p(ri))
4554                   {
4555                     mpfr_set_ui(ri, 0, GMP_RNDN);
4556                     mpfr_copysign(ri, ri, right_imag, GMP_RNDN);
4557                   }
4558                 is_infinity = true;
4559               }
4560
4561             if (is_infinity)
4562               {
4563                 mpfr_mul(lrrr, lr, rr, GMP_RNDN);
4564                 mpfr_mul(lrri, lr, ri, GMP_RNDN);
4565                 mpfr_mul(lirr, li, rr, GMP_RNDN);
4566                 mpfr_mul(liri, li, ri, GMP_RNDN);
4567                 mpfr_sub(real, lrrr, liri, GMP_RNDN);
4568                 mpfr_add(imag, lrri, lirr, GMP_RNDN);
4569                 mpfr_set_inf(real, mpfr_sgn(real));
4570                 mpfr_set_inf(imag, mpfr_sgn(imag));
4571               }
4572
4573             mpfr_clear(lr);
4574             mpfr_clear(li);
4575             mpfr_clear(rr);
4576             mpfr_clear(ri);
4577           }
4578
4579         mpfr_clear(lrrr);
4580         mpfr_clear(lrri);
4581         mpfr_clear(lirr);
4582         mpfr_clear(liri);
4583       }
4584       break;
4585     case OPERATOR_DIV:
4586       {
4587         // For complex division we want to avoid having an
4588         // intermediate overflow turn the whole result in a NaN.  We
4589         // scale the values to try to avoid this.
4590
4591         if (mpfr_zero_p(right_real) && mpfr_zero_p(right_imag))
4592           error_at(location, "division by zero");
4593
4594         mpfr_t rra;
4595         mpfr_t ria;
4596         mpfr_init(rra);
4597         mpfr_init(ria);
4598         mpfr_abs(rra, right_real, GMP_RNDN);
4599         mpfr_abs(ria, right_imag, GMP_RNDN);
4600         mpfr_t t;
4601         mpfr_init(t);
4602         mpfr_max(t, rra, ria, GMP_RNDN);
4603
4604         mpfr_t rr;
4605         mpfr_t ri;
4606         mpfr_init_set(rr, right_real, GMP_RNDN);
4607         mpfr_init_set(ri, right_imag, GMP_RNDN);
4608         long ilogbw = 0;
4609         if (!mpfr_inf_p(t) && !mpfr_nan_p(t) && !mpfr_zero_p(t))
4610           {
4611             ilogbw = mpfr_get_exp(t);
4612             mpfr_mul_2si(rr, rr, - ilogbw, GMP_RNDN);
4613             mpfr_mul_2si(ri, ri, - ilogbw, GMP_RNDN);
4614           }
4615
4616         mpfr_t denom;
4617         mpfr_init(denom);
4618         mpfr_mul(denom, rr, rr, GMP_RNDN);
4619         mpfr_mul(t, ri, ri, GMP_RNDN);
4620         mpfr_add(denom, denom, t, GMP_RNDN);
4621
4622         mpfr_mul(real, left_real, rr, GMP_RNDN);
4623         mpfr_mul(t, left_imag, ri, GMP_RNDN);
4624         mpfr_add(real, real, t, GMP_RNDN);
4625         mpfr_div(real, real, denom, GMP_RNDN);
4626         mpfr_mul_2si(real, real, - ilogbw, GMP_RNDN);
4627
4628         mpfr_mul(imag, left_imag, rr, GMP_RNDN);
4629         mpfr_mul(t, left_real, ri, GMP_RNDN);
4630         mpfr_sub(imag, imag, t, GMP_RNDN);
4631         mpfr_div(imag, imag, denom, GMP_RNDN);
4632         mpfr_mul_2si(imag, imag, - ilogbw, GMP_RNDN);
4633
4634         // If we wind up with NaN on both sides, check whether we
4635         // should really have infinity.  The rule is that if either
4636         // side of the complex number is infinity, then the whole
4637         // value is infinity, even if the other side is NaN.  So the
4638         // only case we have to fix is the one in which both sides are
4639         // NaN.
4640         if (mpfr_nan_p(real) && mpfr_nan_p(imag)
4641             && (!mpfr_nan_p(left_real) || !mpfr_nan_p(left_imag))
4642             && (!mpfr_nan_p(right_real) || !mpfr_nan_p(right_imag)))
4643           {
4644             if (mpfr_zero_p(denom))
4645               {
4646                 mpfr_set_inf(real, mpfr_sgn(rr));
4647                 mpfr_mul(real, real, left_real, GMP_RNDN);
4648                 mpfr_set_inf(imag, mpfr_sgn(rr));
4649                 mpfr_mul(imag, imag, left_imag, GMP_RNDN);
4650               }
4651             else if ((mpfr_inf_p(left_real) || mpfr_inf_p(left_imag))
4652                      && mpfr_number_p(rr) && mpfr_number_p(ri))
4653               {
4654                 mpfr_set_ui(t, mpfr_inf_p(left_real) ? 1 : 0, GMP_RNDN);
4655                 mpfr_copysign(t, t, left_real, GMP_RNDN);
4656
4657                 mpfr_t t2;
4658                 mpfr_init_set_ui(t2, mpfr_inf_p(left_imag) ? 1 : 0, GMP_RNDN);
4659                 mpfr_copysign(t2, t2, left_imag, GMP_RNDN);
4660
4661                 mpfr_t t3;
4662                 mpfr_init(t3);
4663                 mpfr_mul(t3, t, rr, GMP_RNDN);
4664
4665                 mpfr_t t4;
4666                 mpfr_init(t4);
4667                 mpfr_mul(t4, t2, ri, GMP_RNDN);
4668
4669                 mpfr_add(t3, t3, t4, GMP_RNDN);
4670                 mpfr_set_inf(real, mpfr_sgn(t3));
4671
4672                 mpfr_mul(t3, t2, rr, GMP_RNDN);
4673                 mpfr_mul(t4, t, ri, GMP_RNDN);
4674                 mpfr_sub(t3, t3, t4, GMP_RNDN);
4675                 mpfr_set_inf(imag, mpfr_sgn(t3));
4676
4677                 mpfr_clear(t2);
4678                 mpfr_clear(t3);
4679                 mpfr_clear(t4);
4680               }
4681             else if ((mpfr_inf_p(right_real) || mpfr_inf_p(right_imag))
4682                      && mpfr_number_p(left_real) && mpfr_number_p(left_imag))
4683               {
4684                 mpfr_set_ui(t, mpfr_inf_p(rr) ? 1 : 0, GMP_RNDN);
4685                 mpfr_copysign(t, t, rr, GMP_RNDN);
4686
4687                 mpfr_t t2;
4688                 mpfr_init_set_ui(t2, mpfr_inf_p(ri) ? 1 : 0, GMP_RNDN);
4689                 mpfr_copysign(t2, t2, ri, GMP_RNDN);
4690
4691                 mpfr_t t3;
4692                 mpfr_init(t3);
4693                 mpfr_mul(t3, left_real, t, GMP_RNDN);
4694
4695                 mpfr_t t4;
4696                 mpfr_init(t4);
4697                 mpfr_mul(t4, left_imag, t2, GMP_RNDN);
4698
4699                 mpfr_add(t3, t3, t4, GMP_RNDN);
4700                 mpfr_set_ui(real, 0, GMP_RNDN);
4701                 mpfr_mul(real, real, t3, GMP_RNDN);
4702
4703                 mpfr_mul(t3, left_imag, t, GMP_RNDN);
4704                 mpfr_mul(t4, left_real, t2, GMP_RNDN);
4705                 mpfr_sub(t3, t3, t4, GMP_RNDN);
4706                 mpfr_set_ui(imag, 0, GMP_RNDN);
4707                 mpfr_mul(imag, imag, t3, GMP_RNDN);
4708
4709                 mpfr_clear(t2);
4710                 mpfr_clear(t3);
4711                 mpfr_clear(t4);
4712               }
4713           }
4714
4715         mpfr_clear(denom);
4716         mpfr_clear(rr);
4717         mpfr_clear(ri);
4718         mpfr_clear(t);
4719         mpfr_clear(rra);
4720         mpfr_clear(ria);
4721       }
4722       break;
4723     case OPERATOR_MOD:
4724       return false;
4725     case OPERATOR_LSHIFT:
4726     case OPERATOR_RSHIFT:
4727       return false;
4728     default:
4729       gcc_unreachable();
4730     }
4731
4732   Type* type = left_type;
4733   if (type == NULL)
4734     type = right_type;
4735   else if (type != right_type && right_type != NULL)
4736     {
4737       if (type->is_abstract())
4738         type = right_type;
4739       else if (!right_type->is_abstract())
4740         {
4741           // This looks like a type error which should be diagnosed
4742           // elsewhere.  Don't do anything here, to avoid an unhelpful
4743           // chain of error messages.
4744           return true;
4745         }
4746     }
4747
4748   if (type != NULL && !type->is_abstract())
4749     {
4750       if ((type != left_type
4751            && !Complex_expression::check_constant(left_real, left_imag,
4752                                                   type, location))
4753           || (type != right_type
4754               && !Complex_expression::check_constant(right_real, right_imag,
4755                                                      type, location))
4756           || !Complex_expression::check_constant(real, imag, type,
4757                                                  location))
4758         {
4759           mpfr_set_ui(real, 0, GMP_RNDN);
4760           mpfr_set_ui(imag, 0, GMP_RNDN);
4761         }
4762     }
4763
4764   return true;
4765 }
4766
4767 // Lower a binary expression.  We have to evaluate constant
4768 // expressions now, in order to implement Go's unlimited precision
4769 // constants.
4770
4771 Expression*
4772 Binary_expression::do_lower(Gogo*, Named_object*, int)
4773 {
4774   source_location location = this->location();
4775   Operator op = this->op_;
4776   Expression* left = this->left_;
4777   Expression* right = this->right_;
4778
4779   const bool is_comparison = (op == OPERATOR_EQEQ
4780                               || op == OPERATOR_NOTEQ
4781                               || op == OPERATOR_LT
4782                               || op == OPERATOR_LE
4783                               || op == OPERATOR_GT
4784                               || op == OPERATOR_GE);
4785
4786   // Integer constant expressions.
4787   {
4788     mpz_t left_val;
4789     mpz_init(left_val);
4790     Type* left_type;
4791     mpz_t right_val;
4792     mpz_init(right_val);
4793     Type* right_type;
4794     if (left->integer_constant_value(false, left_val, &left_type)
4795         && right->integer_constant_value(false, right_val, &right_type))
4796       {
4797         Expression* ret = NULL;
4798         if (left_type != right_type
4799             && left_type != NULL
4800             && right_type != NULL
4801             && left_type->base() != right_type->base()
4802             && op != OPERATOR_LSHIFT
4803             && op != OPERATOR_RSHIFT)
4804           {
4805             // May be a type error--let it be diagnosed later.
4806           }
4807         else if (is_comparison)
4808           {
4809             bool b = Binary_expression::compare_integer(op, left_val,
4810                                                         right_val);
4811             ret = Expression::make_cast(Type::lookup_bool_type(),
4812                                         Expression::make_boolean(b, location),
4813                                         location);
4814           }
4815         else
4816           {
4817             mpz_t val;
4818             mpz_init(val);
4819
4820             if (Binary_expression::eval_integer(op, left_type, left_val,
4821                                                 right_type, right_val,
4822                                                 location, val))
4823               {
4824                 gcc_assert(op != OPERATOR_OROR && op != OPERATOR_ANDAND);
4825                 Type* type;
4826                 if (op == OPERATOR_LSHIFT || op == OPERATOR_RSHIFT)
4827                   type = left_type;
4828                 else if (left_type == NULL)
4829                   type = right_type;
4830                 else if (right_type == NULL)
4831                   type = left_type;
4832                 else if (!left_type->is_abstract()
4833                          && left_type->named_type() != NULL)
4834                   type = left_type;
4835                 else if (!right_type->is_abstract()
4836                          && right_type->named_type() != NULL)
4837                   type = right_type;
4838                 else if (!left_type->is_abstract())
4839                   type = left_type;
4840                 else if (!right_type->is_abstract())
4841                   type = right_type;
4842                 else if (left_type->float_type() != NULL)
4843                   type = left_type;
4844                 else if (right_type->float_type() != NULL)
4845                   type = right_type;
4846                 else if (left_type->complex_type() != NULL)
4847                   type = left_type;
4848                 else if (right_type->complex_type() != NULL)
4849                   type = right_type;
4850                 else
4851                   type = left_type;
4852                 ret = Expression::make_integer(&val, type, location);
4853               }
4854
4855             mpz_clear(val);
4856           }
4857
4858         if (ret != NULL)
4859           {
4860             mpz_clear(right_val);
4861             mpz_clear(left_val);
4862             return ret;
4863           }
4864       }
4865     mpz_clear(right_val);
4866     mpz_clear(left_val);
4867   }
4868
4869   // Floating point constant expressions.
4870   {
4871     mpfr_t left_val;
4872     mpfr_init(left_val);
4873     Type* left_type;
4874     mpfr_t right_val;
4875     mpfr_init(right_val);
4876     Type* right_type;
4877     if (left->float_constant_value(left_val, &left_type)
4878         && right->float_constant_value(right_val, &right_type))
4879       {
4880         Expression* ret = NULL;
4881         if (left_type != right_type
4882             && left_type != NULL
4883             && right_type != NULL
4884             && left_type->base() != right_type->base()
4885             && op != OPERATOR_LSHIFT
4886             && op != OPERATOR_RSHIFT)
4887           {
4888             // May be a type error--let it be diagnosed later.
4889           }
4890         else if (is_comparison)
4891           {
4892             bool b = Binary_expression::compare_float(op,
4893                                                       (left_type != NULL
4894                                                        ? left_type
4895                                                        : right_type),
4896                                                       left_val, right_val);
4897             ret = Expression::make_boolean(b, location);
4898           }
4899         else
4900           {
4901             mpfr_t val;
4902             mpfr_init(val);
4903
4904             if (Binary_expression::eval_float(op, left_type, left_val,
4905                                               right_type, right_val, val,
4906                                               location))
4907               {
4908                 gcc_assert(op != OPERATOR_OROR && op != OPERATOR_ANDAND
4909                            && op != OPERATOR_LSHIFT && op != OPERATOR_RSHIFT);
4910                 Type* type;
4911                 if (left_type == NULL)
4912                   type = right_type;
4913                 else if (right_type == NULL)
4914                   type = left_type;
4915                 else if (!left_type->is_abstract()
4916                          && left_type->named_type() != NULL)
4917                   type = left_type;
4918                 else if (!right_type->is_abstract()
4919                          && right_type->named_type() != NULL)
4920                   type = right_type;
4921                 else if (!left_type->is_abstract())
4922                   type = left_type;
4923                 else if (!right_type->is_abstract())
4924                   type = right_type;
4925                 else if (left_type->float_type() != NULL)
4926                   type = left_type;
4927                 else if (right_type->float_type() != NULL)
4928                   type = right_type;
4929                 else
4930                   type = left_type;
4931                 ret = Expression::make_float(&val, type, location);
4932               }
4933
4934             mpfr_clear(val);
4935           }
4936
4937         if (ret != NULL)
4938           {
4939             mpfr_clear(right_val);
4940             mpfr_clear(left_val);
4941             return ret;
4942           }
4943       }
4944     mpfr_clear(right_val);
4945     mpfr_clear(left_val);
4946   }
4947
4948   // Complex constant expressions.
4949   {
4950     mpfr_t left_real;
4951     mpfr_t left_imag;
4952     mpfr_init(left_real);
4953     mpfr_init(left_imag);
4954     Type* left_type;
4955
4956     mpfr_t right_real;
4957     mpfr_t right_imag;
4958     mpfr_init(right_real);
4959     mpfr_init(right_imag);
4960     Type* right_type;
4961
4962     if (left->complex_constant_value(left_real, left_imag, &left_type)
4963         && right->complex_constant_value(right_real, right_imag, &right_type))
4964       {
4965         Expression* ret = NULL;
4966         if (left_type != right_type
4967             && left_type != NULL
4968             && right_type != NULL
4969             && left_type->base() != right_type->base())
4970           {
4971             // May be a type error--let it be diagnosed later.
4972           }
4973         else if (is_comparison)
4974           {
4975             bool b = Binary_expression::compare_complex(op,
4976                                                         (left_type != NULL
4977                                                          ? left_type
4978                                                          : right_type),
4979                                                         left_real,
4980                                                         left_imag,
4981                                                         right_real,
4982                                                         right_imag);
4983             ret = Expression::make_boolean(b, location);
4984           }
4985         else
4986           {
4987             mpfr_t real;
4988             mpfr_t imag;
4989             mpfr_init(real);
4990             mpfr_init(imag);
4991
4992             if (Binary_expression::eval_complex(op, left_type,
4993                                                 left_real, left_imag,
4994                                                 right_type,
4995                                                 right_real, right_imag,
4996                                                 real, imag,
4997                                                 location))
4998               {
4999                 gcc_assert(op != OPERATOR_OROR && op != OPERATOR_ANDAND
5000                            && op != OPERATOR_LSHIFT && op != OPERATOR_RSHIFT);
5001                 Type* type;
5002                 if (left_type == NULL)
5003                   type = right_type;
5004                 else if (right_type == NULL)
5005                   type = left_type;
5006                 else if (!left_type->is_abstract()
5007                          && left_type->named_type() != NULL)
5008                   type = left_type;
5009                 else if (!right_type->is_abstract()
5010                          && right_type->named_type() != NULL)
5011                   type = right_type;
5012                 else if (!left_type->is_abstract())
5013                   type = left_type;
5014                 else if (!right_type->is_abstract())
5015                   type = right_type;
5016                 else if (left_type->complex_type() != NULL)
5017                   type = left_type;
5018                 else if (right_type->complex_type() != NULL)
5019                   type = right_type;
5020                 else
5021                   type = left_type;
5022                 ret = Expression::make_complex(&real, &imag, type,
5023                                                location);
5024               }
5025             mpfr_clear(real);
5026             mpfr_clear(imag);
5027           }
5028
5029         if (ret != NULL)
5030           {
5031             mpfr_clear(left_real);
5032             mpfr_clear(left_imag);
5033             mpfr_clear(right_real);
5034             mpfr_clear(right_imag);
5035             return ret;
5036           }
5037       }
5038
5039     mpfr_clear(left_real);
5040     mpfr_clear(left_imag);
5041     mpfr_clear(right_real);
5042     mpfr_clear(right_imag);
5043   }
5044
5045   // String constant expressions.
5046   if (op == OPERATOR_PLUS
5047       && left->type()->is_string_type()
5048       && right->type()->is_string_type())
5049     {
5050       std::string left_string;
5051       std::string right_string;
5052       if (left->string_constant_value(&left_string)
5053           && right->string_constant_value(&right_string))
5054         return Expression::make_string(left_string + right_string, location);
5055     }
5056
5057   return this;
5058 }
5059
5060 // Return the integer constant value, if it has one.
5061
5062 bool
5063 Binary_expression::do_integer_constant_value(bool iota_is_constant, mpz_t val,
5064                                              Type** ptype) const
5065 {
5066   mpz_t left_val;
5067   mpz_init(left_val);
5068   Type* left_type;
5069   if (!this->left_->integer_constant_value(iota_is_constant, left_val,
5070                                            &left_type))
5071     {
5072       mpz_clear(left_val);
5073       return false;
5074     }
5075
5076   mpz_t right_val;
5077   mpz_init(right_val);
5078   Type* right_type;
5079   if (!this->right_->integer_constant_value(iota_is_constant, right_val,
5080                                             &right_type))
5081     {
5082       mpz_clear(right_val);
5083       mpz_clear(left_val);
5084       return false;
5085     }
5086
5087   bool ret;
5088   if (left_type != right_type
5089       && left_type != NULL
5090       && right_type != NULL
5091       && left_type->base() != right_type->base()
5092       && this->op_ != OPERATOR_RSHIFT
5093       && this->op_ != OPERATOR_LSHIFT)
5094     ret = false;
5095   else
5096     ret = Binary_expression::eval_integer(this->op_, left_type, left_val,
5097                                           right_type, right_val,
5098                                           this->location(), val);
5099
5100   mpz_clear(right_val);
5101   mpz_clear(left_val);
5102
5103   if (ret)
5104     *ptype = left_type;
5105
5106   return ret;
5107 }
5108
5109 // Return the floating point constant value, if it has one.
5110
5111 bool
5112 Binary_expression::do_float_constant_value(mpfr_t val, Type** ptype) const
5113 {
5114   mpfr_t left_val;
5115   mpfr_init(left_val);
5116   Type* left_type;
5117   if (!this->left_->float_constant_value(left_val, &left_type))
5118     {
5119       mpfr_clear(left_val);
5120       return false;
5121     }
5122
5123   mpfr_t right_val;
5124   mpfr_init(right_val);
5125   Type* right_type;
5126   if (!this->right_->float_constant_value(right_val, &right_type))
5127     {
5128       mpfr_clear(right_val);
5129       mpfr_clear(left_val);
5130       return false;
5131     }
5132
5133   bool ret;
5134   if (left_type != right_type
5135       && left_type != NULL
5136       && right_type != NULL
5137       && left_type->base() != right_type->base())
5138     ret = false;
5139   else
5140     ret = Binary_expression::eval_float(this->op_, left_type, left_val,
5141                                         right_type, right_val,
5142                                         val, this->location());
5143
5144   mpfr_clear(left_val);
5145   mpfr_clear(right_val);
5146
5147   if (ret)
5148     *ptype = left_type;
5149
5150   return ret;
5151 }
5152
5153 // Return the complex constant value, if it has one.
5154
5155 bool
5156 Binary_expression::do_complex_constant_value(mpfr_t real, mpfr_t imag,
5157                                              Type** ptype) const
5158 {
5159   mpfr_t left_real;
5160   mpfr_t left_imag;
5161   mpfr_init(left_real);
5162   mpfr_init(left_imag);
5163   Type* left_type;
5164   if (!this->left_->complex_constant_value(left_real, left_imag, &left_type))
5165     {
5166       mpfr_clear(left_real);
5167       mpfr_clear(left_imag);
5168       return false;
5169     }
5170
5171   mpfr_t right_real;
5172   mpfr_t right_imag;
5173   mpfr_init(right_real);
5174   mpfr_init(right_imag);
5175   Type* right_type;
5176   if (!this->right_->complex_constant_value(right_real, right_imag,
5177                                             &right_type))
5178     {
5179       mpfr_clear(left_real);
5180       mpfr_clear(left_imag);
5181       mpfr_clear(right_real);
5182       mpfr_clear(right_imag);
5183       return false;
5184     }
5185
5186   bool ret;
5187   if (left_type != right_type
5188       && left_type != NULL
5189       && right_type != NULL
5190       && left_type->base() != right_type->base())
5191     ret = false;
5192   else
5193     ret = Binary_expression::eval_complex(this->op_, left_type,
5194                                           left_real, left_imag,
5195                                           right_type,
5196                                           right_real, right_imag,
5197                                           real, imag,
5198                                           this->location());
5199   mpfr_clear(left_real);
5200   mpfr_clear(left_imag);
5201   mpfr_clear(right_real);
5202   mpfr_clear(right_imag);
5203
5204   if (ret)
5205     *ptype = left_type;
5206
5207   return ret;
5208 }
5209
5210 // Note that the value is being discarded.
5211
5212 void
5213 Binary_expression::do_discarding_value()
5214 {
5215   if (this->op_ == OPERATOR_OROR || this->op_ == OPERATOR_ANDAND)
5216     this->right_->discarding_value();
5217   else
5218     this->warn_about_unused_value();
5219 }
5220
5221 // Get type.
5222
5223 Type*
5224 Binary_expression::do_type()
5225 {
5226   switch (this->op_)
5227     {
5228     case OPERATOR_OROR:
5229     case OPERATOR_ANDAND:
5230     case OPERATOR_EQEQ:
5231     case OPERATOR_NOTEQ:
5232     case OPERATOR_LT:
5233     case OPERATOR_LE:
5234     case OPERATOR_GT:
5235     case OPERATOR_GE:
5236       return Type::lookup_bool_type();
5237
5238     case OPERATOR_PLUS:
5239     case OPERATOR_MINUS:
5240     case OPERATOR_OR:
5241     case OPERATOR_XOR:
5242     case OPERATOR_MULT:
5243     case OPERATOR_DIV:
5244     case OPERATOR_MOD:
5245     case OPERATOR_AND:
5246     case OPERATOR_BITCLEAR:
5247       {
5248         Type* left_type = this->left_->type();
5249         Type* right_type = this->right_->type();
5250         if (!left_type->is_abstract() && left_type->named_type() != NULL)
5251           return left_type;
5252         else if (!right_type->is_abstract() && right_type->named_type() != NULL)
5253           return right_type;
5254         else if (!left_type->is_abstract())
5255           return left_type;
5256         else if (!right_type->is_abstract())
5257           return right_type;
5258         else if (left_type->complex_type() != NULL)
5259           return left_type;
5260         else if (right_type->complex_type() != NULL)
5261           return right_type;
5262         else if (left_type->float_type() != NULL)
5263           return left_type;
5264         else if (right_type->float_type() != NULL)
5265           return right_type;
5266         else
5267           return left_type;
5268       }
5269
5270     case OPERATOR_LSHIFT:
5271     case OPERATOR_RSHIFT:
5272       return this->left_->type();
5273
5274     default:
5275       gcc_unreachable();
5276     }
5277 }
5278
5279 // Set type for a binary expression.
5280
5281 void
5282 Binary_expression::do_determine_type(const Type_context* context)
5283 {
5284   Type* tleft = this->left_->type();
5285   Type* tright = this->right_->type();
5286
5287   // Both sides should have the same type, except for the shift
5288   // operations.  For a comparison, we should ignore the incoming
5289   // type.
5290
5291   bool is_shift_op = (this->op_ == OPERATOR_LSHIFT
5292                       || this->op_ == OPERATOR_RSHIFT);
5293
5294   bool is_comparison = (this->op_ == OPERATOR_EQEQ
5295                         || this->op_ == OPERATOR_NOTEQ
5296                         || this->op_ == OPERATOR_LT
5297                         || this->op_ == OPERATOR_LE
5298                         || this->op_ == OPERATOR_GT
5299                         || this->op_ == OPERATOR_GE);
5300
5301   Type_context subcontext(*context);
5302
5303   if (is_comparison)
5304     {
5305       // In a comparison, the context does not determine the types of
5306       // the operands.
5307       subcontext.type = NULL;
5308     }
5309
5310   // Set the context for the left hand operand.
5311   if (is_shift_op)
5312     {
5313       // The right hand operand plays no role in determining the type
5314       // of the left hand operand.  A shift of an abstract integer in
5315       // a string context gets special treatment, which may be a
5316       // language bug.
5317       if (subcontext.type != NULL
5318           && subcontext.type->is_string_type()
5319           && tleft->is_abstract())
5320         error_at(this->location(), "shift of non-integer operand");
5321     }
5322   else if (!tleft->is_abstract())
5323     subcontext.type = tleft;
5324   else if (!tright->is_abstract())
5325     subcontext.type = tright;
5326   else if (subcontext.type == NULL)
5327     {
5328       if ((tleft->integer_type() != NULL && tright->integer_type() != NULL)
5329           || (tleft->float_type() != NULL && tright->float_type() != NULL)
5330           || (tleft->complex_type() != NULL && tright->complex_type() != NULL))
5331         {
5332           // Both sides have an abstract integer, abstract float, or
5333           // abstract complex type.  Just let CONTEXT determine
5334           // whether they may remain abstract or not.
5335         }
5336       else if (tleft->complex_type() != NULL)
5337         subcontext.type = tleft;
5338       else if (tright->complex_type() != NULL)
5339         subcontext.type = tright;
5340       else if (tleft->float_type() != NULL)
5341         subcontext.type = tleft;
5342       else if (tright->float_type() != NULL)
5343         subcontext.type = tright;
5344       else
5345         subcontext.type = tleft;
5346     }
5347
5348   this->left_->determine_type(&subcontext);
5349
5350   // The context for the right hand operand is the same as for the
5351   // left hand operand, except for a shift operator.
5352   if (is_shift_op)
5353     {
5354       subcontext.type = Type::lookup_integer_type("uint");
5355       subcontext.may_be_abstract = false;
5356     }
5357
5358   this->right_->determine_type(&subcontext);
5359 }
5360
5361 // Report an error if the binary operator OP does not support TYPE.
5362 // Return whether the operation is OK.  This should not be used for
5363 // shift.
5364
5365 bool
5366 Binary_expression::check_operator_type(Operator op, Type* type,
5367                                        source_location location)
5368 {
5369   switch (op)
5370     {
5371     case OPERATOR_OROR:
5372     case OPERATOR_ANDAND:
5373       if (!type->is_boolean_type())
5374         {
5375           error_at(location, "expected boolean type");
5376           return false;
5377         }
5378       break;
5379
5380     case OPERATOR_EQEQ:
5381     case OPERATOR_NOTEQ:
5382       if (type->integer_type() == NULL
5383           && type->float_type() == NULL
5384           && type->complex_type() == NULL
5385           && !type->is_string_type()
5386           && type->points_to() == NULL
5387           && !type->is_nil_type()
5388           && !type->is_boolean_type()
5389           && type->interface_type() == NULL
5390           && (type->array_type() == NULL
5391               || type->array_type()->length() != NULL)
5392           && type->map_type() == NULL
5393           && type->channel_type() == NULL
5394           && type->function_type() == NULL)
5395         {
5396           error_at(location,
5397                    ("expected integer, floating, complex, string, pointer, "
5398                     "boolean, interface, slice, map, channel, "
5399                     "or function type"));
5400           return false;
5401         }
5402       break;
5403
5404     case OPERATOR_LT:
5405     case OPERATOR_LE:
5406     case OPERATOR_GT:
5407     case OPERATOR_GE:
5408       if (type->integer_type() == NULL
5409           && type->float_type() == NULL
5410           && !type->is_string_type())
5411         {
5412           error_at(location, "expected integer, floating, or string type");
5413           return false;
5414         }
5415       break;
5416
5417     case OPERATOR_PLUS:
5418     case OPERATOR_PLUSEQ:
5419       if (type->integer_type() == NULL
5420           && type->float_type() == NULL
5421           && type->complex_type() == NULL
5422           && !type->is_string_type())
5423         {
5424           error_at(location,
5425                    "expected integer, floating, complex, or string type");
5426           return false;
5427         }
5428       break;
5429
5430     case OPERATOR_MINUS:
5431     case OPERATOR_MINUSEQ:
5432     case OPERATOR_MULT:
5433     case OPERATOR_MULTEQ:
5434     case OPERATOR_DIV:
5435     case OPERATOR_DIVEQ:
5436       if (type->integer_type() == NULL
5437           && type->float_type() == NULL
5438           && type->complex_type() == NULL)
5439         {
5440           error_at(location, "expected integer, floating, or complex type");
5441           return false;
5442         }
5443       break;
5444
5445     case OPERATOR_MOD:
5446     case OPERATOR_MODEQ:
5447     case OPERATOR_OR:
5448     case OPERATOR_OREQ:
5449     case OPERATOR_AND:
5450     case OPERATOR_ANDEQ:
5451     case OPERATOR_XOR:
5452     case OPERATOR_XOREQ:
5453     case OPERATOR_BITCLEAR:
5454     case OPERATOR_BITCLEAREQ:
5455       if (type->integer_type() == NULL)
5456         {
5457           error_at(location, "expected integer type");
5458           return false;
5459         }
5460       break;
5461
5462     default:
5463       gcc_unreachable();
5464     }
5465
5466   return true;
5467 }
5468
5469 // Check types.
5470
5471 void
5472 Binary_expression::do_check_types(Gogo*)
5473 {
5474   Type* left_type = this->left_->type();
5475   Type* right_type = this->right_->type();
5476   if (left_type->is_error_type() || right_type->is_error_type())
5477     return;
5478
5479   if (this->op_ == OPERATOR_EQEQ
5480       || this->op_ == OPERATOR_NOTEQ
5481       || this->op_ == OPERATOR_LT
5482       || this->op_ == OPERATOR_LE
5483       || this->op_ == OPERATOR_GT
5484       || this->op_ == OPERATOR_GE)
5485     {
5486       if (!Type::are_assignable(left_type, right_type, NULL)
5487           && !Type::are_assignable(right_type, left_type, NULL))
5488         {
5489           this->report_error(_("incompatible types in binary expression"));
5490           return;
5491         }
5492       if (!Binary_expression::check_operator_type(this->op_, left_type,
5493                                                   this->location())
5494           || !Binary_expression::check_operator_type(this->op_, right_type,
5495                                                      this->location()))
5496         {
5497           this->set_is_error();
5498           return;
5499         }
5500     }
5501   else if (this->op_ != OPERATOR_LSHIFT && this->op_ != OPERATOR_RSHIFT)
5502     {
5503       if (!Type::are_compatible_for_binop(left_type, right_type))
5504         {
5505           this->report_error(_("incompatible types in binary expression"));
5506           return;
5507         }
5508       if (!Binary_expression::check_operator_type(this->op_, left_type,
5509                                                   this->location()))
5510         {
5511           this->set_is_error();
5512           return;
5513         }
5514     }
5515   else
5516     {
5517       if (left_type->integer_type() == NULL)
5518         this->report_error(_("shift of non-integer operand"));
5519
5520       if (!right_type->is_abstract()
5521           && (right_type->integer_type() == NULL
5522               || !right_type->integer_type()->is_unsigned()))
5523         this->report_error(_("shift count not unsigned integer"));
5524       else
5525         {
5526           mpz_t val;
5527           mpz_init(val);
5528           Type* type;
5529           if (this->right_->integer_constant_value(true, val, &type))
5530             {
5531               if (mpz_sgn(val) < 0)
5532                 this->report_error(_("negative shift count"));
5533             }
5534           mpz_clear(val);
5535         }
5536     }
5537 }
5538
5539 // Get a tree for a binary expression.
5540
5541 tree
5542 Binary_expression::do_get_tree(Translate_context* context)
5543 {
5544   tree left = this->left_->get_tree(context);
5545   tree right = this->right_->get_tree(context);
5546
5547   if (left == error_mark_node || right == error_mark_node)
5548     return error_mark_node;
5549
5550   enum tree_code code;
5551   bool use_left_type = true;
5552   bool is_shift_op = false;
5553   switch (this->op_)
5554     {
5555     case OPERATOR_EQEQ:
5556     case OPERATOR_NOTEQ:
5557     case OPERATOR_LT:
5558     case OPERATOR_LE:
5559     case OPERATOR_GT:
5560     case OPERATOR_GE:
5561       return Expression::comparison_tree(context, this->op_,
5562                                          this->left_->type(), left,
5563                                          this->right_->type(), right,
5564                                          this->location());
5565
5566     case OPERATOR_OROR:
5567       code = TRUTH_ORIF_EXPR;
5568       use_left_type = false;
5569       break;
5570     case OPERATOR_ANDAND:
5571       code = TRUTH_ANDIF_EXPR;
5572       use_left_type = false;
5573       break;
5574     case OPERATOR_PLUS:
5575       code = PLUS_EXPR;
5576       break;
5577     case OPERATOR_MINUS:
5578       code = MINUS_EXPR;
5579       break;
5580     case OPERATOR_OR:
5581       code = BIT_IOR_EXPR;
5582       break;
5583     case OPERATOR_XOR:
5584       code = BIT_XOR_EXPR;
5585       break;
5586     case OPERATOR_MULT:
5587       code = MULT_EXPR;
5588       break;
5589     case OPERATOR_DIV:
5590       {
5591         Type *t = this->left_->type();
5592         if (t->float_type() != NULL || t->complex_type() != NULL)
5593           code = RDIV_EXPR;
5594         else
5595           code = TRUNC_DIV_EXPR;
5596       }
5597       break;
5598     case OPERATOR_MOD:
5599       code = TRUNC_MOD_EXPR;
5600       break;
5601     case OPERATOR_LSHIFT:
5602       code = LSHIFT_EXPR;
5603       is_shift_op = true;
5604       break;
5605     case OPERATOR_RSHIFT:
5606       code = RSHIFT_EXPR;
5607       is_shift_op = true;
5608       break;
5609     case OPERATOR_AND:
5610       code = BIT_AND_EXPR;
5611       break;
5612     case OPERATOR_BITCLEAR:
5613       right = fold_build1(BIT_NOT_EXPR, TREE_TYPE(right), right);
5614       code = BIT_AND_EXPR;
5615       break;
5616     default:
5617       gcc_unreachable();
5618     }
5619
5620   tree type = use_left_type ? TREE_TYPE(left) : TREE_TYPE(right);
5621
5622   if (this->left_->type()->is_string_type())
5623     {
5624       gcc_assert(this->op_ == OPERATOR_PLUS);
5625       tree string_type = Type::make_string_type()->get_tree(context->gogo());
5626       static tree string_plus_decl;
5627       return Gogo::call_builtin(&string_plus_decl,
5628                                 this->location(),
5629                                 "__go_string_plus",
5630                                 2,
5631                                 string_type,
5632                                 string_type,
5633                                 left,
5634                                 string_type,
5635                                 right);
5636     }
5637
5638   tree compute_type = excess_precision_type(type);
5639   if (compute_type != NULL_TREE)
5640     {
5641       left = ::convert(compute_type, left);
5642       right = ::convert(compute_type, right);
5643     }
5644
5645   tree eval_saved = NULL_TREE;
5646   if (is_shift_op)
5647     {
5648       if (!DECL_P(left))
5649         left = save_expr(left);
5650       if (!DECL_P(right))
5651         right = save_expr(right);
5652       // Make sure the values are evaluated.
5653       eval_saved = fold_build2_loc(this->location(), COMPOUND_EXPR,
5654                                    void_type_node, left, right);
5655     }
5656
5657   tree ret = fold_build2_loc(this->location(),
5658                              code,
5659                              compute_type != NULL_TREE ? compute_type : type,
5660                              left, right);
5661
5662   if (compute_type != NULL_TREE)
5663     ret = ::convert(type, ret);
5664
5665   // In Go, a shift larger than the size of the type is well-defined.
5666   // This is not true in GENERIC, so we need to insert a conditional.
5667   if (is_shift_op)
5668     {
5669       gcc_assert(INTEGRAL_TYPE_P(TREE_TYPE(left)));
5670       gcc_assert(this->left_->type()->integer_type() != NULL);
5671       int bits = TYPE_PRECISION(TREE_TYPE(left));
5672
5673       tree compare = fold_build2(LT_EXPR, boolean_type_node, right,
5674                                  build_int_cst_type(TREE_TYPE(right), bits));
5675
5676       tree overflow_result = fold_convert_loc(this->location(),
5677                                               TREE_TYPE(left),
5678                                               integer_zero_node);
5679       if (this->op_ == OPERATOR_RSHIFT
5680           && !this->left_->type()->integer_type()->is_unsigned())
5681         {
5682           tree neg = fold_build2_loc(this->location(), LT_EXPR,
5683                                      boolean_type_node, left,
5684                                      fold_convert_loc(this->location(),
5685                                                       TREE_TYPE(left),
5686                                                       integer_zero_node));
5687           tree neg_one = fold_build2_loc(this->location(),
5688                                          MINUS_EXPR, TREE_TYPE(left),
5689                                          fold_convert_loc(this->location(),
5690                                                           TREE_TYPE(left),
5691                                                           integer_zero_node),
5692                                          fold_convert_loc(this->location(),
5693                                                           TREE_TYPE(left),
5694                                                           integer_one_node));
5695           overflow_result = fold_build3_loc(this->location(), COND_EXPR,
5696                                             TREE_TYPE(left), neg, neg_one,
5697                                             overflow_result);
5698         }
5699
5700       ret = fold_build3_loc(this->location(), COND_EXPR, TREE_TYPE(left),
5701                             compare, ret, overflow_result);
5702
5703       ret = fold_build2_loc(this->location(), COMPOUND_EXPR,
5704                             TREE_TYPE(ret), eval_saved, ret);
5705     }
5706
5707   return ret;
5708 }
5709
5710 // Export a binary expression.
5711
5712 void
5713 Binary_expression::do_export(Export* exp) const
5714 {
5715   exp->write_c_string("(");
5716   this->left_->export_expression(exp);
5717   switch (this->op_)
5718     {
5719     case OPERATOR_OROR:
5720       exp->write_c_string(" || ");
5721       break;
5722     case OPERATOR_ANDAND:
5723       exp->write_c_string(" && ");
5724       break;
5725     case OPERATOR_EQEQ:
5726       exp->write_c_string(" == ");
5727       break;
5728     case OPERATOR_NOTEQ:
5729       exp->write_c_string(" != ");
5730       break;
5731     case OPERATOR_LT:
5732       exp->write_c_string(" < ");
5733       break;
5734     case OPERATOR_LE:
5735       exp->write_c_string(" <= ");
5736       break;
5737     case OPERATOR_GT:
5738       exp->write_c_string(" > ");
5739       break;
5740     case OPERATOR_GE:
5741       exp->write_c_string(" >= ");
5742       break;
5743     case OPERATOR_PLUS:
5744       exp->write_c_string(" + ");
5745       break;
5746     case OPERATOR_MINUS:
5747       exp->write_c_string(" - ");
5748       break;
5749     case OPERATOR_OR:
5750       exp->write_c_string(" | ");
5751       break;
5752     case OPERATOR_XOR:
5753       exp->write_c_string(" ^ ");
5754       break;
5755     case OPERATOR_MULT:
5756       exp->write_c_string(" * ");
5757       break;
5758     case OPERATOR_DIV:
5759       exp->write_c_string(" / ");
5760       break;
5761     case OPERATOR_MOD:
5762       exp->write_c_string(" % ");
5763       break;
5764     case OPERATOR_LSHIFT:
5765       exp->write_c_string(" << ");
5766       break;
5767     case OPERATOR_RSHIFT:
5768       exp->write_c_string(" >> ");
5769       break;
5770     case OPERATOR_AND:
5771       exp->write_c_string(" & ");
5772       break;
5773     case OPERATOR_BITCLEAR:
5774       exp->write_c_string(" &^ ");
5775       break;
5776     default:
5777       gcc_unreachable();
5778     }
5779   this->right_->export_expression(exp);
5780   exp->write_c_string(")");
5781 }
5782
5783 // Import a binary expression.
5784
5785 Expression*
5786 Binary_expression::do_import(Import* imp)
5787 {
5788   imp->require_c_string("(");
5789
5790   Expression* left = Expression::import_expression(imp);
5791
5792   Operator op;
5793   if (imp->match_c_string(" || "))
5794     {
5795       op = OPERATOR_OROR;
5796       imp->advance(4);
5797     }
5798   else if (imp->match_c_string(" && "))
5799     {
5800       op = OPERATOR_ANDAND;
5801       imp->advance(4);
5802     }
5803   else if (imp->match_c_string(" == "))
5804     {
5805       op = OPERATOR_EQEQ;
5806       imp->advance(4);
5807     }
5808   else if (imp->match_c_string(" != "))
5809     {
5810       op = OPERATOR_NOTEQ;
5811       imp->advance(4);
5812     }
5813   else if (imp->match_c_string(" < "))
5814     {
5815       op = OPERATOR_LT;
5816       imp->advance(3);
5817     }
5818   else if (imp->match_c_string(" <= "))
5819     {
5820       op = OPERATOR_LE;
5821       imp->advance(4);
5822     }
5823   else if (imp->match_c_string(" > "))
5824     {
5825       op = OPERATOR_GT;
5826       imp->advance(3);
5827     }
5828   else if (imp->match_c_string(" >= "))
5829     {
5830       op = OPERATOR_GE;
5831       imp->advance(4);
5832     }
5833   else if (imp->match_c_string(" + "))
5834     {
5835       op = OPERATOR_PLUS;
5836       imp->advance(3);
5837     }
5838   else if (imp->match_c_string(" - "))
5839     {
5840       op = OPERATOR_MINUS;
5841       imp->advance(3);
5842     }
5843   else if (imp->match_c_string(" | "))
5844     {
5845       op = OPERATOR_OR;
5846       imp->advance(3);
5847     }
5848   else if (imp->match_c_string(" ^ "))
5849     {
5850       op = OPERATOR_XOR;
5851       imp->advance(3);
5852     }
5853   else if (imp->match_c_string(" * "))
5854     {
5855       op = OPERATOR_MULT;
5856       imp->advance(3);
5857     }
5858   else if (imp->match_c_string(" / "))
5859     {
5860       op = OPERATOR_DIV;
5861       imp->advance(3);
5862     }
5863   else if (imp->match_c_string(" % "))
5864     {
5865       op = OPERATOR_MOD;
5866       imp->advance(3);
5867     }
5868   else if (imp->match_c_string(" << "))
5869     {
5870       op = OPERATOR_LSHIFT;
5871       imp->advance(4);
5872     }
5873   else if (imp->match_c_string(" >> "))
5874     {
5875       op = OPERATOR_RSHIFT;
5876       imp->advance(4);
5877     }
5878   else if (imp->match_c_string(" & "))
5879     {
5880       op = OPERATOR_AND;
5881       imp->advance(3);
5882     }
5883   else if (imp->match_c_string(" &^ "))
5884     {
5885       op = OPERATOR_BITCLEAR;
5886       imp->advance(4);
5887     }
5888   else
5889     {
5890       error_at(imp->location(), "unrecognized binary operator");
5891       return Expression::make_error(imp->location());
5892     }
5893
5894   Expression* right = Expression::import_expression(imp);
5895
5896   imp->require_c_string(")");
5897
5898   return Expression::make_binary(op, left, right, imp->location());
5899 }
5900
5901 // Make a binary expression.
5902
5903 Expression*
5904 Expression::make_binary(Operator op, Expression* left, Expression* right,
5905                         source_location location)
5906 {
5907   return new Binary_expression(op, left, right, location);
5908 }
5909
5910 // Implement a comparison.
5911
5912 tree
5913 Expression::comparison_tree(Translate_context* context, Operator op,
5914                             Type* left_type, tree left_tree,
5915                             Type* right_type, tree right_tree,
5916                             source_location location)
5917 {
5918   enum tree_code code;
5919   switch (op)
5920     {
5921     case OPERATOR_EQEQ:
5922       code = EQ_EXPR;
5923       break;
5924     case OPERATOR_NOTEQ:
5925       code = NE_EXPR;
5926       break;
5927     case OPERATOR_LT:
5928       code = LT_EXPR;
5929       break;
5930     case OPERATOR_LE:
5931       code = LE_EXPR;
5932       break;
5933     case OPERATOR_GT:
5934       code = GT_EXPR;
5935       break;
5936     case OPERATOR_GE:
5937       code = GE_EXPR;
5938       break;
5939     default:
5940       gcc_unreachable();
5941     }
5942
5943   if (left_type->is_string_type())
5944     {
5945       gcc_assert(right_type->is_string_type());
5946       tree string_type = Type::make_string_type()->get_tree(context->gogo());
5947       static tree string_compare_decl;
5948       left_tree = Gogo::call_builtin(&string_compare_decl,
5949                                      location,
5950                                      "__go_strcmp",
5951                                      2,
5952                                      integer_type_node,
5953                                      string_type,
5954                                      left_tree,
5955                                      string_type,
5956                                      right_tree);
5957       right_tree = build_int_cst_type(integer_type_node, 0);
5958     }
5959
5960   if ((left_type->interface_type() != NULL
5961        && right_type->interface_type() == NULL
5962        && !right_type->is_nil_type())
5963       || (left_type->interface_type() == NULL
5964           && !left_type->is_nil_type()
5965           && right_type->interface_type() != NULL))
5966     {
5967       // Comparing an interface value to a non-interface value.
5968       if (left_type->interface_type() == NULL)
5969         {
5970           std::swap(left_type, right_type);
5971           std::swap(left_tree, right_tree);
5972         }
5973
5974       // The right operand is not an interface.  We need to take its
5975       // address if it is not a pointer.
5976       tree make_tmp;
5977       tree arg;
5978       if (right_type->points_to() != NULL)
5979         {
5980           make_tmp = NULL_TREE;
5981           arg = right_tree;
5982         }
5983       else if (TREE_ADDRESSABLE(TREE_TYPE(right_tree)) || DECL_P(right_tree))
5984         {
5985           make_tmp = NULL_TREE;
5986           arg = build_fold_addr_expr_loc(location, right_tree);
5987           if (DECL_P(right_tree))
5988             TREE_ADDRESSABLE(right_tree) = 1;
5989         }
5990       else
5991         {
5992           tree tmp = create_tmp_var(TREE_TYPE(right_tree),
5993                                     get_name(right_tree));
5994           DECL_IGNORED_P(tmp) = 0;
5995           DECL_INITIAL(tmp) = right_tree;
5996           TREE_ADDRESSABLE(tmp) = 1;
5997           make_tmp = build1(DECL_EXPR, void_type_node, tmp);
5998           SET_EXPR_LOCATION(make_tmp, location);
5999           arg = build_fold_addr_expr_loc(location, tmp);
6000         }
6001       arg = fold_convert_loc(location, ptr_type_node, arg);
6002
6003       tree descriptor = right_type->type_descriptor_pointer(context->gogo());
6004
6005       if (left_type->interface_type()->is_empty())
6006         {
6007           static tree empty_interface_value_compare_decl;
6008           left_tree = Gogo::call_builtin(&empty_interface_value_compare_decl,
6009                                          location,
6010                                          "__go_empty_interface_value_compare",
6011                                          3,
6012                                          integer_type_node,
6013                                          TREE_TYPE(left_tree),
6014                                          left_tree,
6015                                          TREE_TYPE(descriptor),
6016                                          descriptor,
6017                                          ptr_type_node,
6018                                          arg);
6019           // This can panic if the type is not comparable.
6020           TREE_NOTHROW(empty_interface_value_compare_decl) = 0;
6021         }
6022       else
6023         {
6024           static tree interface_value_compare_decl;
6025           left_tree = Gogo::call_builtin(&interface_value_compare_decl,
6026                                          location,
6027                                          "__go_interface_value_compare",
6028                                          3,
6029                                          integer_type_node,
6030                                          TREE_TYPE(left_tree),
6031                                          left_tree,
6032                                          TREE_TYPE(descriptor),
6033                                          descriptor,
6034                                          ptr_type_node,
6035                                          arg);
6036           // This can panic if the type is not comparable.
6037           TREE_NOTHROW(interface_value_compare_decl) = 0;
6038         }
6039       right_tree = build_int_cst_type(integer_type_node, 0);
6040
6041       if (make_tmp != NULL_TREE)
6042         left_tree = build2(COMPOUND_EXPR, TREE_TYPE(left_tree), make_tmp,
6043                            left_tree);
6044     }
6045   else if (left_type->interface_type() != NULL
6046            && right_type->interface_type() != NULL)
6047     {
6048       if (left_type->interface_type()->is_empty())
6049         {
6050           gcc_assert(right_type->interface_type()->is_empty());
6051           static tree empty_interface_compare_decl;
6052           left_tree = Gogo::call_builtin(&empty_interface_compare_decl,
6053                                          location,
6054                                          "__go_empty_interface_compare",
6055                                          2,
6056                                          integer_type_node,
6057                                          TREE_TYPE(left_tree),
6058                                          left_tree,
6059                                          TREE_TYPE(right_tree),
6060                                          right_tree);
6061           // This can panic if the type is uncomparable.
6062           TREE_NOTHROW(empty_interface_compare_decl) = 0;
6063         }
6064       else
6065         {
6066           gcc_assert(!right_type->interface_type()->is_empty());
6067           static tree interface_compare_decl;
6068           left_tree = Gogo::call_builtin(&interface_compare_decl,
6069                                          location,
6070                                          "__go_interface_compare",
6071                                          2,
6072                                          integer_type_node,
6073                                          TREE_TYPE(left_tree),
6074                                          left_tree,
6075                                          TREE_TYPE(right_tree),
6076                                          right_tree);
6077           // This can panic if the type is uncomparable.
6078           TREE_NOTHROW(interface_compare_decl) = 0;
6079         }
6080       right_tree = build_int_cst_type(integer_type_node, 0);
6081     }
6082
6083   if (left_type->is_nil_type()
6084       && (op == OPERATOR_EQEQ || op == OPERATOR_NOTEQ))
6085     {
6086       std::swap(left_type, right_type);
6087       std::swap(left_tree, right_tree);
6088     }
6089
6090   if (right_type->is_nil_type())
6091     {
6092       if (left_type->array_type() != NULL
6093           && left_type->array_type()->length() == NULL)
6094         {
6095           Array_type* at = left_type->array_type();
6096           left_tree = at->value_pointer_tree(context->gogo(), left_tree);
6097           right_tree = fold_convert(TREE_TYPE(left_tree), null_pointer_node);
6098         }
6099       else if (left_type->interface_type() != NULL)
6100         {
6101           // An interface is nil if the first field is nil.
6102           tree left_type_tree = TREE_TYPE(left_tree);
6103           gcc_assert(TREE_CODE(left_type_tree) == RECORD_TYPE);
6104           tree field = TYPE_FIELDS(left_type_tree);
6105           left_tree = build3(COMPONENT_REF, TREE_TYPE(field), left_tree,
6106                              field, NULL_TREE);
6107           right_tree = fold_convert(TREE_TYPE(left_tree), null_pointer_node);
6108         }
6109       else
6110         {
6111           gcc_assert(POINTER_TYPE_P(TREE_TYPE(left_tree)));
6112           right_tree = fold_convert(TREE_TYPE(left_tree), null_pointer_node);
6113         }
6114     }
6115
6116   tree ret = fold_build2(code, boolean_type_node, left_tree, right_tree);
6117   if (CAN_HAVE_LOCATION_P(ret))
6118     SET_EXPR_LOCATION(ret, location);
6119   return ret;
6120 }
6121
6122 // Class Bound_method_expression.
6123
6124 // Traversal.
6125
6126 int
6127 Bound_method_expression::do_traverse(Traverse* traverse)
6128 {
6129   if (Expression::traverse(&this->expr_, traverse) == TRAVERSE_EXIT)
6130     return TRAVERSE_EXIT;
6131   return Expression::traverse(&this->method_, traverse);
6132 }
6133
6134 // Return the type of a bound method expression.  The type of this
6135 // object is really the type of the method with no receiver.  We
6136 // should be able to get away with just returning the type of the
6137 // method.
6138
6139 Type*
6140 Bound_method_expression::do_type()
6141 {
6142   return this->method_->type();
6143 }
6144
6145 // Determine the types of a method expression.
6146
6147 void
6148 Bound_method_expression::do_determine_type(const Type_context*)
6149 {
6150   this->method_->determine_type_no_context();
6151   Type* mtype = this->method_->type();
6152   Function_type* fntype = mtype == NULL ? NULL : mtype->function_type();
6153   if (fntype == NULL || !fntype->is_method())
6154     this->expr_->determine_type_no_context();
6155   else
6156     {
6157       Type_context subcontext(fntype->receiver()->type(), false);
6158       this->expr_->determine_type(&subcontext);
6159     }
6160 }
6161
6162 // Check the types of a method expression.
6163
6164 void
6165 Bound_method_expression::do_check_types(Gogo*)
6166 {
6167   Type* type = this->method_->type()->deref();
6168   if (type == NULL
6169       || type->function_type() == NULL
6170       || !type->function_type()->is_method())
6171     this->report_error(_("object is not a method"));
6172   else
6173     {
6174       Type* rtype = type->function_type()->receiver()->type()->deref();
6175       Type* etype = (this->expr_type_ != NULL
6176                      ? this->expr_type_
6177                      : this->expr_->type());
6178       etype = etype->deref();
6179       if (!Type::are_identical(rtype, etype, NULL))
6180         this->report_error(_("method type does not match object type"));
6181     }
6182 }
6183
6184 // Get the tree for a method expression.  There is no standard tree
6185 // representation for this.  The only places it may currently be used
6186 // are in a Call_expression or a Go_statement, which will take it
6187 // apart directly.  So this has nothing to do at present.
6188
6189 tree
6190 Bound_method_expression::do_get_tree(Translate_context*)
6191 {
6192   gcc_unreachable();
6193 }
6194
6195 // Make a method expression.
6196
6197 Bound_method_expression*
6198 Expression::make_bound_method(Expression* expr, Expression* method,
6199                               source_location location)
6200 {
6201   return new Bound_method_expression(expr, method, location);
6202 }
6203
6204 // Class Builtin_call_expression.  This is used for a call to a
6205 // builtin function.
6206
6207 class Builtin_call_expression : public Call_expression
6208 {
6209  public:
6210   Builtin_call_expression(Gogo* gogo, Expression* fn, Expression_list* args,
6211                           bool is_varargs, source_location location);
6212
6213  protected:
6214   // This overrides Call_expression::do_lower.
6215   Expression*
6216   do_lower(Gogo*, Named_object*, int);
6217
6218   bool
6219   do_is_constant() const;
6220
6221   bool
6222   do_integer_constant_value(bool, mpz_t, Type**) const;
6223
6224   bool
6225   do_float_constant_value(mpfr_t, Type**) const;
6226
6227   bool
6228   do_complex_constant_value(mpfr_t, mpfr_t, Type**) const;
6229
6230   Type*
6231   do_type();
6232
6233   void
6234   do_determine_type(const Type_context*);
6235
6236   void
6237   do_check_types(Gogo*);
6238
6239   Expression*
6240   do_copy()
6241   {
6242     return new Builtin_call_expression(this->gogo_, this->fn()->copy(),
6243                                        this->args()->copy(),
6244                                        this->is_varargs(),
6245                                        this->location());
6246   }
6247
6248   tree
6249   do_get_tree(Translate_context*);
6250
6251   void
6252   do_export(Export*) const;
6253
6254   virtual bool
6255   do_is_recover_call() const;
6256
6257   virtual void
6258   do_set_recover_arg(Expression*);
6259
6260  private:
6261   // The builtin functions.
6262   enum Builtin_function_code
6263     {
6264       BUILTIN_INVALID,
6265
6266       // Predeclared builtin functions.
6267       BUILTIN_APPEND,
6268       BUILTIN_CAP,
6269       BUILTIN_CLOSE,
6270       BUILTIN_CLOSED,
6271       BUILTIN_CMPLX,
6272       BUILTIN_COPY,
6273       BUILTIN_IMAG,
6274       BUILTIN_LEN,
6275       BUILTIN_MAKE,
6276       BUILTIN_NEW,
6277       BUILTIN_PANIC,
6278       BUILTIN_PRINT,
6279       BUILTIN_PRINTLN,
6280       BUILTIN_REAL,
6281       BUILTIN_RECOVER,
6282
6283       // Builtin functions from the unsafe package.
6284       BUILTIN_ALIGNOF,
6285       BUILTIN_OFFSETOF,
6286       BUILTIN_SIZEOF
6287     };
6288
6289   Expression*
6290   one_arg() const;
6291
6292   bool
6293   check_one_arg();
6294
6295   static Type*
6296   real_imag_type(Type*);
6297
6298   static Type*
6299   cmplx_type(Type*);
6300
6301   // A pointer back to the general IR structure.  This avoids a global
6302   // variable, or passing it around everywhere.
6303   Gogo* gogo_;
6304   // The builtin function being called.
6305   Builtin_function_code code_;
6306 };
6307
6308 Builtin_call_expression::Builtin_call_expression(Gogo* gogo,
6309                                                  Expression* fn,
6310                                                  Expression_list* args,
6311                                                  bool is_varargs,
6312                                                  source_location location)
6313   : Call_expression(fn, args, is_varargs, location),
6314     gogo_(gogo), code_(BUILTIN_INVALID)
6315 {
6316   Func_expression* fnexp = this->fn()->func_expression();
6317   gcc_assert(fnexp != NULL);
6318   const std::string& name(fnexp->named_object()->name());
6319   if (name == "append")
6320     this->code_ = BUILTIN_APPEND;
6321   else if (name == "cap")
6322     this->code_ = BUILTIN_CAP;
6323   else if (name == "close")
6324     this->code_ = BUILTIN_CLOSE;
6325   else if (name == "closed")
6326     this->code_ = BUILTIN_CLOSED;
6327   else if (name == "cmplx")
6328     this->code_ = BUILTIN_CMPLX;
6329   else if (name == "copy")
6330     this->code_ = BUILTIN_COPY;
6331   else if (name == "imag")
6332     this->code_ = BUILTIN_IMAG;
6333   else if (name == "len")
6334     this->code_ = BUILTIN_LEN;
6335   else if (name == "make")
6336     this->code_ = BUILTIN_MAKE;
6337   else if (name == "new")
6338     this->code_ = BUILTIN_NEW;
6339   else if (name == "panic")
6340     this->code_ = BUILTIN_PANIC;
6341   else if (name == "print")
6342     this->code_ = BUILTIN_PRINT;
6343   else if (name == "println")
6344     this->code_ = BUILTIN_PRINTLN;
6345   else if (name == "real")
6346     this->code_ = BUILTIN_REAL;
6347   else if (name == "recover")
6348     this->code_ = BUILTIN_RECOVER;
6349   else if (name == "Alignof")
6350     this->code_ = BUILTIN_ALIGNOF;
6351   else if (name == "Offsetof")
6352     this->code_ = BUILTIN_OFFSETOF;
6353   else if (name == "Sizeof")
6354     this->code_ = BUILTIN_SIZEOF;
6355   else
6356     gcc_unreachable();
6357 }
6358
6359 // Return whether this is a call to recover.  This is a virtual
6360 // function called from the parent class.
6361
6362 bool
6363 Builtin_call_expression::do_is_recover_call() const
6364 {
6365   if (this->classification() == EXPRESSION_ERROR)
6366     return false;
6367   return this->code_ == BUILTIN_RECOVER;
6368 }
6369
6370 // Set the argument for a call to recover.
6371
6372 void
6373 Builtin_call_expression::do_set_recover_arg(Expression* arg)
6374 {
6375   const Expression_list* args = this->args();
6376   gcc_assert(args == NULL || args->empty());
6377   Expression_list* new_args = new Expression_list();
6378   new_args->push_back(arg);
6379   this->set_args(new_args);
6380 }
6381
6382 // A traversal class which looks for a call expression.
6383
6384 class Find_call_expression : public Traverse
6385 {
6386  public:
6387   Find_call_expression()
6388     : Traverse(traverse_expressions),
6389       found_(false)
6390   { }
6391
6392   int
6393   expression(Expression**);
6394
6395   bool
6396   found()
6397   { return this->found_; }
6398
6399  private:
6400   bool found_;
6401 };
6402
6403 int
6404 Find_call_expression::expression(Expression** pexpr)
6405 {
6406   if ((*pexpr)->call_expression() != NULL)
6407     {
6408       this->found_ = true;
6409       return TRAVERSE_EXIT;
6410     }
6411   return TRAVERSE_CONTINUE;
6412 }
6413
6414 // Lower a builtin call expression.  This turns new and make into
6415 // specific expressions.  We also convert to a constant if we can.
6416
6417 Expression*
6418 Builtin_call_expression::do_lower(Gogo* gogo, Named_object* function, int)
6419 {
6420   if (this->code_ == BUILTIN_NEW)
6421     {
6422       const Expression_list* args = this->args();
6423       if (args == NULL || args->size() < 1)
6424         this->report_error(_("not enough arguments"));
6425       else if (args->size() > 1)
6426         this->report_error(_("too many arguments"));
6427       else
6428         {
6429           Expression* arg = args->front();
6430           if (!arg->is_type_expression())
6431             {
6432               error_at(arg->location(), "expected type");
6433               this->set_is_error();
6434             }
6435           else
6436             return Expression::make_allocation(arg->type(), this->location());
6437         }
6438     }
6439   else if (this->code_ == BUILTIN_MAKE)
6440     {
6441       const Expression_list* args = this->args();
6442       if (args == NULL || args->size() < 1)
6443         this->report_error(_("not enough arguments"));
6444       else
6445         {
6446           Expression* arg = args->front();
6447           if (!arg->is_type_expression())
6448             {
6449               error_at(arg->location(), "expected type");
6450               this->set_is_error();
6451             }
6452           else
6453             {
6454               Expression_list* newargs;
6455               if (args->size() == 1)
6456                 newargs = NULL;
6457               else
6458                 {
6459                   newargs = new Expression_list();
6460                   Expression_list::const_iterator p = args->begin();
6461                   ++p;
6462                   for (; p != args->end(); ++p)
6463                     newargs->push_back(*p);
6464                 }
6465               return Expression::make_make(arg->type(), newargs,
6466                                            this->location());
6467             }
6468         }
6469     }
6470   else if (this->is_constant())
6471     {
6472       // We can only lower len and cap if there are no function calls
6473       // in the arguments.  Otherwise we have to make the call.
6474       if (this->code_ == BUILTIN_LEN || this->code_ == BUILTIN_CAP)
6475         {
6476           Expression* arg = this->one_arg();
6477           if (!arg->is_constant())
6478             {
6479               Find_call_expression find_call;
6480               Expression::traverse(&arg, &find_call);
6481               if (find_call.found())
6482                 return this;
6483             }
6484         }
6485
6486       mpz_t ival;
6487       mpz_init(ival);
6488       Type* type;
6489       if (this->integer_constant_value(true, ival, &type))
6490         {
6491           Expression* ret = Expression::make_integer(&ival, type,
6492                                                      this->location());
6493           mpz_clear(ival);
6494           return ret;
6495         }
6496       mpz_clear(ival);
6497
6498       mpfr_t rval;
6499       mpfr_init(rval);
6500       if (this->float_constant_value(rval, &type))
6501         {
6502           Expression* ret = Expression::make_float(&rval, type,
6503                                                    this->location());
6504           mpfr_clear(rval);
6505           return ret;
6506         }
6507
6508       mpfr_t imag;
6509       mpfr_init(imag);
6510       if (this->complex_constant_value(rval, imag, &type))
6511         {
6512           Expression* ret = Expression::make_complex(&rval, &imag, type,
6513                                                      this->location());
6514           mpfr_clear(rval);
6515           mpfr_clear(imag);
6516           return ret;
6517         }
6518       mpfr_clear(rval);
6519       mpfr_clear(imag);
6520     }
6521   else if (this->code_ == BUILTIN_RECOVER)
6522     {
6523       if (function != NULL)
6524         function->func_value()->set_calls_recover();
6525       else
6526         {
6527           // Calling recover outside of a function always returns the
6528           // nil empty interface.
6529           Type* eface = Type::make_interface_type(NULL, this->location());
6530           return Expression::make_cast(eface,
6531                                        Expression::make_nil(this->location()),
6532                                        this->location());
6533         }
6534     }
6535   else if (this->code_ == BUILTIN_APPEND)
6536     {
6537       // Lower the varargs.
6538       const Expression_list* args = this->args();
6539       if (args == NULL || args->empty())
6540         return this;
6541       Type* slice_type = args->front()->type();
6542       if (!slice_type->is_open_array_type())
6543         {
6544           error_at(args->front()->location(), "argument 1 must be a slice");
6545           this->set_is_error();
6546           return this;
6547         }
6548       return this->lower_varargs(gogo, function, slice_type, 2);
6549     }
6550
6551   return this;
6552 }
6553
6554 // Return the type of the real or imag functions, given the type of
6555 // the argument.  We need to map complex to float, complex64 to
6556 // float32, and complex128 to float64, so it has to be done by name.
6557 // This returns NULL if it can't figure out the type.
6558
6559 Type*
6560 Builtin_call_expression::real_imag_type(Type* arg_type)
6561 {
6562   if (arg_type == NULL || arg_type->is_abstract())
6563     return NULL;
6564   Named_type* nt = arg_type->named_type();
6565   if (nt == NULL)
6566     return NULL;
6567   while (nt->real_type()->named_type() != NULL)
6568     nt = nt->real_type()->named_type();
6569   if (nt->name() == "complex")
6570     return Type::lookup_float_type("float");
6571   else if (nt->name() == "complex64")
6572     return Type::lookup_float_type("float32");
6573   else if (nt->name() == "complex128")
6574     return Type::lookup_float_type("float64");
6575   else
6576     return NULL;
6577 }
6578
6579 // Return the type of the cmplx function, given the type of one of the
6580 // argments.  Like real_imag_type, we have to map by name.
6581
6582 Type*
6583 Builtin_call_expression::cmplx_type(Type* arg_type)
6584 {
6585   if (arg_type == NULL || arg_type->is_abstract())
6586     return NULL;
6587   Named_type* nt = arg_type->named_type();
6588   if (nt == NULL)
6589     return NULL;
6590   while (nt->real_type()->named_type() != NULL)
6591     nt = nt->real_type()->named_type();
6592   if (nt->name() == "float")
6593     return Type::lookup_complex_type("complex");
6594   else if (nt->name() == "float32")
6595     return Type::lookup_complex_type("complex64");
6596   else if (nt->name() == "float64")
6597     return Type::lookup_complex_type("complex128");
6598   else
6599     return NULL;
6600 }
6601
6602 // Return a single argument, or NULL if there isn't one.
6603
6604 Expression*
6605 Builtin_call_expression::one_arg() const
6606 {
6607   const Expression_list* args = this->args();
6608   if (args->size() != 1)
6609     return NULL;
6610   return args->front();
6611 }
6612
6613 // Return whether this is constant: len of a string, or len or cap of
6614 // a fixed array, or unsafe.Sizeof, unsafe.Offsetof, unsafe.Alignof.
6615
6616 bool
6617 Builtin_call_expression::do_is_constant() const
6618 {
6619   switch (this->code_)
6620     {
6621     case BUILTIN_LEN:
6622     case BUILTIN_CAP:
6623       {
6624         Expression* arg = this->one_arg();
6625         if (arg == NULL)
6626           return false;
6627         Type* arg_type = arg->type();
6628
6629         if (arg_type->points_to() != NULL
6630             && arg_type->points_to()->array_type() != NULL
6631             && !arg_type->points_to()->is_open_array_type())
6632           arg_type = arg_type->points_to();
6633
6634         if (arg_type->array_type() != NULL
6635             && arg_type->array_type()->length() != NULL)
6636           return arg_type->array_type()->length()->is_constant();
6637
6638         if (this->code_ == BUILTIN_LEN && arg_type->is_string_type())
6639           return arg->is_constant();
6640       }
6641       break;
6642
6643     case BUILTIN_SIZEOF:
6644     case BUILTIN_ALIGNOF:
6645       return this->one_arg() != NULL;
6646
6647     case BUILTIN_OFFSETOF:
6648       {
6649         Expression* arg = this->one_arg();
6650         if (arg == NULL)
6651           return false;
6652         return arg->field_reference_expression() != NULL;
6653       }
6654
6655     case BUILTIN_CMPLX:
6656       {
6657         const Expression_list* args = this->args();
6658         if (args != NULL && args->size() == 2)
6659           return args->front()->is_constant() && args->back()->is_constant();
6660       }
6661       break;
6662
6663     case BUILTIN_REAL:
6664     case BUILTIN_IMAG:
6665       {
6666         Expression* arg = this->one_arg();
6667         return arg != NULL && arg->is_constant();
6668       }
6669
6670     default:
6671       break;
6672     }
6673
6674   return false;
6675 }
6676
6677 // Return an integer constant value if possible.
6678
6679 bool
6680 Builtin_call_expression::do_integer_constant_value(bool iota_is_constant,
6681                                                    mpz_t val,
6682                                                    Type** ptype) const
6683 {
6684   if (this->code_ == BUILTIN_LEN
6685       || this->code_ == BUILTIN_CAP)
6686     {
6687       Expression* arg = this->one_arg();
6688       if (arg == NULL)
6689         return false;
6690       Type* arg_type = arg->type();
6691
6692       if (this->code_ == BUILTIN_LEN && arg_type->is_string_type())
6693         {
6694           std::string sval;
6695           if (arg->string_constant_value(&sval))
6696             {
6697               mpz_set_ui(val, sval.length());
6698               *ptype = Type::lookup_integer_type("int");
6699               return true;
6700             }
6701         }
6702
6703       if (arg_type->points_to() != NULL
6704           && arg_type->points_to()->array_type() != NULL
6705           && !arg_type->points_to()->is_open_array_type())
6706         arg_type = arg_type->points_to();
6707
6708       if (arg_type->array_type() != NULL
6709           && arg_type->array_type()->length() != NULL)
6710         {
6711           Expression* e = arg_type->array_type()->length();
6712           if (e->integer_constant_value(iota_is_constant, val, ptype))
6713             {
6714               *ptype = Type::lookup_integer_type("int");
6715               return true;
6716             }
6717         }
6718     }
6719   else if (this->code_ == BUILTIN_SIZEOF
6720            || this->code_ == BUILTIN_ALIGNOF)
6721     {
6722       Expression* arg = this->one_arg();
6723       if (arg == NULL)
6724         return false;
6725       Type* arg_type = arg->type();
6726       if (arg_type->is_error_type())
6727         return false;
6728       if (arg_type->is_abstract())
6729         return false;
6730       tree arg_type_tree = arg_type->get_tree(this->gogo_);
6731       unsigned long val_long;
6732       if (this->code_ == BUILTIN_SIZEOF)
6733         {
6734           tree type_size = TYPE_SIZE_UNIT(arg_type_tree);
6735           gcc_assert(TREE_CODE(type_size) == INTEGER_CST);
6736           if (TREE_INT_CST_HIGH(type_size) != 0)
6737             return false;
6738           unsigned HOST_WIDE_INT val_wide = TREE_INT_CST_LOW(type_size);
6739           val_long = static_cast<unsigned long>(val_wide);
6740           if (val_long != val_wide)
6741             return false;
6742         }
6743       else if (this->code_ == BUILTIN_ALIGNOF)
6744         {
6745           if (arg->field_reference_expression() == NULL)
6746             val_long = go_type_alignment(arg_type_tree);
6747           else
6748             {
6749               // Calling unsafe.Alignof(s.f) returns the alignment of
6750               // the type of f when it is used as a field in a struct.
6751               val_long = go_field_alignment(arg_type_tree);
6752             }
6753         }
6754       else
6755         gcc_unreachable();
6756       mpz_set_ui(val, val_long);
6757       *ptype = NULL;
6758       return true;
6759     }
6760   else if (this->code_ == BUILTIN_OFFSETOF)
6761     {
6762       Expression* arg = this->one_arg();
6763       if (arg == NULL)
6764         return false;
6765       Field_reference_expression* farg = arg->field_reference_expression();
6766       if (farg == NULL)
6767         return false;
6768       Expression* struct_expr = farg->expr();
6769       Type* st = struct_expr->type();
6770       if (st->struct_type() == NULL)
6771         return false;
6772       tree struct_tree = st->get_tree(this->gogo_);
6773       gcc_assert(TREE_CODE(struct_tree) == RECORD_TYPE);
6774       tree field = TYPE_FIELDS(struct_tree);
6775       for (unsigned int index = farg->field_index(); index > 0; --index)
6776         {
6777           field = DECL_CHAIN(field);
6778           gcc_assert(field != NULL_TREE);
6779         }
6780       HOST_WIDE_INT offset_wide = int_byte_position (field);
6781       if (offset_wide < 0)
6782         return false;
6783       unsigned long offset_long = static_cast<unsigned long>(offset_wide);
6784       if (offset_long != static_cast<unsigned HOST_WIDE_INT>(offset_wide))
6785         return false;
6786       mpz_set_ui(val, offset_long);
6787       return true;
6788     }
6789   return false;
6790 }
6791
6792 // Return a floating point constant value if possible.
6793
6794 bool
6795 Builtin_call_expression::do_float_constant_value(mpfr_t val,
6796                                                  Type** ptype) const
6797 {
6798   if (this->code_ == BUILTIN_REAL || this->code_ == BUILTIN_IMAG)
6799     {
6800       Expression* arg = this->one_arg();
6801       if (arg == NULL)
6802         return false;
6803
6804       mpfr_t real;
6805       mpfr_t imag;
6806       mpfr_init(real);
6807       mpfr_init(imag);
6808
6809       bool ret = false;
6810       Type* type;
6811       if (arg->complex_constant_value(real, imag, &type))
6812         {
6813           if (this->code_ == BUILTIN_REAL)
6814             mpfr_set(val, real, GMP_RNDN);
6815           else
6816             mpfr_set(val, imag, GMP_RNDN);
6817           *ptype = Builtin_call_expression::real_imag_type(type);
6818           ret = true;
6819         }
6820
6821       mpfr_clear(real);
6822       mpfr_clear(imag);
6823       return ret;
6824     }
6825
6826   return false;
6827 }
6828
6829 // Return a complex constant value if possible.
6830
6831 bool
6832 Builtin_call_expression::do_complex_constant_value(mpfr_t real, mpfr_t imag,
6833                                                    Type** ptype) const
6834 {
6835   if (this->code_ == BUILTIN_CMPLX)
6836     {
6837       const Expression_list* args = this->args();
6838       if (args == NULL || args->size() != 2)
6839         return false;
6840
6841       mpfr_t r;
6842       mpfr_init(r);
6843       Type* rtype;
6844       if (!args->front()->float_constant_value(r, &rtype))
6845         {
6846           mpfr_clear(r);
6847           return false;
6848         }
6849
6850       mpfr_t i;
6851       mpfr_init(i);
6852
6853       bool ret = false;
6854       Type* itype;
6855       if (args->back()->float_constant_value(i, &itype)
6856           && Type::are_identical(rtype, itype, NULL))
6857         {
6858           mpfr_set(real, r, GMP_RNDN);
6859           mpfr_set(imag, i, GMP_RNDN);
6860           *ptype = Builtin_call_expression::cmplx_type(rtype);
6861           ret = true;
6862         }
6863
6864       mpfr_clear(r);
6865       mpfr_clear(i);
6866
6867       return ret;
6868     }
6869
6870   return false;
6871 }
6872
6873 // Return the type.
6874
6875 Type*
6876 Builtin_call_expression::do_type()
6877 {
6878   switch (this->code_)
6879     {
6880     case BUILTIN_INVALID:
6881     default:
6882       gcc_unreachable();
6883
6884     case BUILTIN_NEW:
6885     case BUILTIN_MAKE:
6886       {
6887         const Expression_list* args = this->args();
6888         if (args == NULL || args->empty())
6889           return Type::make_error_type();
6890         return Type::make_pointer_type(args->front()->type());
6891       }
6892
6893     case BUILTIN_CAP:
6894     case BUILTIN_COPY:
6895     case BUILTIN_LEN:
6896     case BUILTIN_ALIGNOF:
6897     case BUILTIN_OFFSETOF:
6898     case BUILTIN_SIZEOF:
6899       return Type::lookup_integer_type("int");
6900
6901     case BUILTIN_CLOSE:
6902     case BUILTIN_PANIC:
6903     case BUILTIN_PRINT:
6904     case BUILTIN_PRINTLN:
6905       return Type::make_void_type();
6906
6907     case BUILTIN_CLOSED:
6908       return Type::lookup_bool_type();
6909
6910     case BUILTIN_RECOVER:
6911       return Type::make_interface_type(NULL, BUILTINS_LOCATION);
6912
6913     case BUILTIN_APPEND:
6914       {
6915         const Expression_list* args = this->args();
6916         if (args == NULL || args->empty())
6917           return Type::make_error_type();
6918         return args->front()->type();
6919       }
6920
6921     case BUILTIN_REAL:
6922     case BUILTIN_IMAG:
6923       {
6924         Expression* arg = this->one_arg();
6925         if (arg == NULL)
6926           return Type::make_error_type();
6927         Type* t = arg->type();
6928         if (t->is_abstract())
6929           t = t->make_non_abstract_type();
6930         t = Builtin_call_expression::real_imag_type(t);
6931         if (t == NULL)
6932           t = Type::make_error_type();
6933         return t;
6934       }
6935
6936     case BUILTIN_CMPLX:
6937       {
6938         const Expression_list* args = this->args();
6939         if (args == NULL || args->size() != 2)
6940           return Type::make_error_type();
6941         Type* t = args->front()->type();
6942         if (t->is_abstract())
6943           {
6944             t = args->back()->type();
6945             if (t->is_abstract())
6946               t = t->make_non_abstract_type();
6947           }
6948         t = Builtin_call_expression::cmplx_type(t);
6949         if (t == NULL)
6950           t = Type::make_error_type();
6951         return t;
6952       }
6953     }
6954 }
6955
6956 // Determine the type.
6957
6958 void
6959 Builtin_call_expression::do_determine_type(const Type_context* context)
6960 {
6961   this->fn()->determine_type_no_context();
6962
6963   const Expression_list* args = this->args();
6964
6965   bool is_print;
6966   Type* arg_type = NULL;
6967   switch (this->code_)
6968     {
6969     case BUILTIN_PRINT:
6970     case BUILTIN_PRINTLN:
6971       // Do not force a large integer constant to "int".
6972       is_print = true;
6973       break;
6974
6975     case BUILTIN_REAL:
6976     case BUILTIN_IMAG:
6977       arg_type = Builtin_call_expression::cmplx_type(context->type);
6978       is_print = false;
6979       break;
6980
6981     case BUILTIN_CMPLX:
6982       {
6983         // For the cmplx function the type of one operand can
6984         // determine the type of the other, as in a binary expression.
6985         arg_type = Builtin_call_expression::real_imag_type(context->type);
6986         if (args != NULL && args->size() == 2)
6987           {
6988             Type* t1 = args->front()->type();
6989             Type* t2 = args->front()->type();
6990             if (!t1->is_abstract())
6991               arg_type = t1;
6992             else if (!t2->is_abstract())
6993               arg_type = t2;
6994           }
6995         is_print = false;
6996       }
6997       break;
6998
6999     default:
7000       is_print = false;
7001       break;
7002     }
7003
7004   if (args != NULL)
7005     {
7006       for (Expression_list::const_iterator pa = args->begin();
7007            pa != args->end();
7008            ++pa)
7009         {
7010           Type_context subcontext;
7011           subcontext.type = arg_type;
7012
7013           if (is_print)
7014             {
7015               // We want to print large constants, we so can't just
7016               // use the appropriate nonabstract type.  Use uint64 for
7017               // an integer if we know it is nonnegative, otherwise
7018               // use int64 for a integer, otherwise use float64 for a
7019               // float or complex128 for a complex.
7020               Type* want_type = NULL;
7021               Type* atype = (*pa)->type();
7022               if (atype->is_abstract())
7023                 {
7024                   if (atype->integer_type() != NULL)
7025                     {
7026                       mpz_t val;
7027                       mpz_init(val);
7028                       Type* dummy;
7029                       if (this->integer_constant_value(true, val, &dummy)
7030                           && mpz_sgn(val) >= 0)
7031                         want_type = Type::lookup_integer_type("uint64");
7032                       else
7033                         want_type = Type::lookup_integer_type("int64");
7034                       mpz_clear(val);
7035                     }
7036                   else if (atype->float_type() != NULL)
7037                     want_type = Type::lookup_float_type("float64");
7038                   else if (atype->complex_type() != NULL)
7039                     want_type = Type::lookup_complex_type("complex128");
7040                   else if (atype->is_abstract_string_type())
7041                     want_type = Type::lookup_string_type();
7042                   else if (atype->is_abstract_boolean_type())
7043                     want_type = Type::lookup_bool_type();
7044                   else
7045                     gcc_unreachable();
7046                   subcontext.type = want_type;
7047                 }
7048             }
7049
7050           (*pa)->determine_type(&subcontext);
7051         }
7052     }
7053 }
7054
7055 // If there is exactly one argument, return true.  Otherwise give an
7056 // error message and return false.
7057
7058 bool
7059 Builtin_call_expression::check_one_arg()
7060 {
7061   const Expression_list* args = this->args();
7062   if (args == NULL || args->size() < 1)
7063     {
7064       this->report_error(_("not enough arguments"));
7065       return false;
7066     }
7067   else if (args->size() > 1)
7068     {
7069       this->report_error(_("too many arguments"));
7070       return false;
7071     }
7072   if (args->front()->is_error_expression()
7073       || args->front()->type()->is_error_type())
7074     {
7075       this->set_is_error();
7076       return false;
7077     }
7078   return true;
7079 }
7080
7081 // Check argument types for a builtin function.
7082
7083 void
7084 Builtin_call_expression::do_check_types(Gogo*)
7085 {
7086   switch (this->code_)
7087     {
7088     case BUILTIN_INVALID:
7089     case BUILTIN_NEW:
7090     case BUILTIN_MAKE:
7091       return;
7092
7093     case BUILTIN_LEN:
7094     case BUILTIN_CAP:
7095       {
7096         // The single argument may be either a string or an array or a
7097         // map or a channel, or a pointer to a closed array.
7098         if (this->check_one_arg())
7099           {
7100             Type* arg_type = this->one_arg()->type();
7101             if (arg_type->points_to() != NULL
7102                 && arg_type->points_to()->array_type() != NULL
7103                 && !arg_type->points_to()->is_open_array_type())
7104               arg_type = arg_type->points_to();
7105             if (this->code_ == BUILTIN_CAP)
7106               {
7107                 if (!arg_type->is_error_type()
7108                     && arg_type->array_type() == NULL
7109                     && arg_type->channel_type() == NULL)
7110                   this->report_error(_("argument must be array or slice "
7111                                        "or channel"));
7112               }
7113             else
7114               {
7115                 if (!arg_type->is_error_type()
7116                     && !arg_type->is_string_type()
7117                     && arg_type->array_type() == NULL
7118                     && arg_type->map_type() == NULL
7119                     && arg_type->channel_type() == NULL)
7120                   this->report_error(_("argument must be string or "
7121                                        "array or slice or map or channel"));
7122               }
7123           }
7124       }
7125       break;
7126
7127     case BUILTIN_PRINT:
7128     case BUILTIN_PRINTLN:
7129       {
7130         const Expression_list* args = this->args();
7131         if (args == NULL)
7132           {
7133             if (this->code_ == BUILTIN_PRINT)
7134               warning_at(this->location(), 0,
7135                          "no arguments for builtin function %<%s%>",
7136                          (this->code_ == BUILTIN_PRINT
7137                           ? "print"
7138                           : "println"));
7139           }
7140         else
7141           {
7142             for (Expression_list::const_iterator p = args->begin();
7143                  p != args->end();
7144                  ++p)
7145               {
7146                 Type* type = (*p)->type();
7147                 if (type->is_error_type()
7148                     || type->is_string_type()
7149                     || type->integer_type() != NULL
7150                     || type->float_type() != NULL
7151                     || type->complex_type() != NULL
7152                     || type->is_boolean_type()
7153                     || type->points_to() != NULL
7154                     || type->interface_type() != NULL
7155                     || type->channel_type() != NULL
7156                     || type->map_type() != NULL
7157                     || type->function_type() != NULL
7158                     || type->is_open_array_type())
7159                   ;
7160                 else
7161                   this->report_error(_("unsupported argument type to "
7162                                        "builtin function"));
7163               }
7164           }
7165       }
7166       break;
7167
7168     case BUILTIN_CLOSE:
7169     case BUILTIN_CLOSED:
7170       if (this->check_one_arg())
7171         {
7172           if (this->one_arg()->type()->channel_type() == NULL)
7173             this->report_error(_("argument must be channel"));
7174         }
7175       break;
7176
7177     case BUILTIN_PANIC:
7178     case BUILTIN_SIZEOF:
7179     case BUILTIN_ALIGNOF:
7180       this->check_one_arg();
7181       break;
7182
7183     case BUILTIN_RECOVER:
7184       if (this->args() != NULL && !this->args()->empty())
7185         this->report_error(_("too many arguments"));
7186       break;
7187
7188     case BUILTIN_OFFSETOF:
7189       if (this->check_one_arg())
7190         {
7191           Expression* arg = this->one_arg();
7192           if (arg->field_reference_expression() == NULL)
7193             this->report_error(_("argument must be a field reference"));
7194         }
7195       break;
7196
7197     case BUILTIN_COPY:
7198       {
7199         const Expression_list* args = this->args();
7200         if (args == NULL || args->size() < 2)
7201           {
7202             this->report_error(_("not enough arguments"));
7203             break;
7204           }
7205         else if (args->size() > 2)
7206           {
7207             this->report_error(_("too many arguments"));
7208             break;
7209           }
7210         Type* arg1_type = args->front()->type();
7211         Type* arg2_type = args->back()->type();
7212         if (arg1_type->is_error_type() || arg2_type->is_error_type())
7213           break;
7214
7215         Type* e1;
7216         if (arg1_type->is_open_array_type())
7217           e1 = arg1_type->array_type()->element_type();
7218         else
7219           {
7220             this->report_error(_("left argument must be a slice"));
7221             break;
7222           }
7223
7224         Type* e2;
7225         if (arg2_type->is_open_array_type())
7226           e2 = arg2_type->array_type()->element_type();
7227         else if (arg2_type->is_string_type())
7228           e2 = Type::lookup_integer_type("uint8");
7229         else
7230           {
7231             this->report_error(_("right argument must be a slice or a string"));
7232             break;
7233           }
7234
7235         if (!Type::are_identical(e1, e2, NULL))
7236           this->report_error(_("element types must be the same"));
7237       }
7238       break;
7239
7240     case BUILTIN_APPEND:
7241       {
7242         const Expression_list* args = this->args();
7243         if (args == NULL || args->empty())
7244           {
7245             this->report_error(_("not enough arguments"));
7246             break;
7247           }
7248         /* Lowering varargs should have left us with 2 arguments.  */
7249         gcc_assert(args->size() == 2);
7250         std::string reason;
7251         if (!Type::are_assignable(args->front()->type(), args->back()->type(),
7252                                   &reason))
7253           {
7254             if (reason.empty())
7255               this->report_error(_("arguments 1 and 2 have different types"));
7256             else
7257               {
7258                 error_at(this->location(),
7259                          "arguments 1 and 2 have different types (%s)",
7260                          reason.c_str());
7261                 this->set_is_error();
7262               }
7263           }
7264         break;
7265       }
7266
7267     case BUILTIN_REAL:
7268     case BUILTIN_IMAG:
7269       if (this->check_one_arg())
7270         {
7271           if (this->one_arg()->type()->complex_type() == NULL)
7272             this->report_error(_("argument must have complex type"));
7273         }
7274       break;
7275
7276     case BUILTIN_CMPLX:
7277       {
7278         const Expression_list* args = this->args();
7279         if (args == NULL || args->size() < 2)
7280           this->report_error(_("not enough arguments"));
7281         else if (args->size() > 2)
7282           this->report_error(_("too many arguments"));
7283         else if (args->front()->is_error_expression()
7284                  || args->front()->type()->is_error_type()
7285                  || args->back()->is_error_expression()
7286                  || args->back()->type()->is_error_type())
7287           this->set_is_error();
7288         else if (!Type::are_identical(args->front()->type(),
7289                                       args->back()->type(), NULL))
7290           this->report_error(_("cmplx arguments must have identical types"));
7291         else if (args->front()->type()->float_type() == NULL)
7292           this->report_error(_("cmplx arguments must have "
7293                                "floating-point type"));
7294       }
7295       break;
7296
7297     default:
7298       gcc_unreachable();
7299     }
7300 }
7301
7302 // Return the tree for a builtin function.
7303
7304 tree
7305 Builtin_call_expression::do_get_tree(Translate_context* context)
7306 {
7307   Gogo* gogo = context->gogo();
7308   source_location location = this->location();
7309   switch (this->code_)
7310     {
7311     case BUILTIN_INVALID:
7312     case BUILTIN_NEW:
7313     case BUILTIN_MAKE:
7314       gcc_unreachable();
7315
7316     case BUILTIN_LEN:
7317     case BUILTIN_CAP:
7318       {
7319         const Expression_list* args = this->args();
7320         gcc_assert(args != NULL && args->size() == 1);
7321         Expression* arg = *args->begin();
7322         Type* arg_type = arg->type();
7323         tree arg_tree = arg->get_tree(context);
7324         if (arg_tree == error_mark_node)
7325           return error_mark_node;
7326
7327         if (arg_type->points_to() != NULL)
7328           {
7329             arg_type = arg_type->points_to();
7330             gcc_assert(arg_type->array_type() != NULL
7331                        && !arg_type->is_open_array_type());
7332             gcc_assert(POINTER_TYPE_P(TREE_TYPE(arg_tree)));
7333             arg_tree = build_fold_indirect_ref(arg_tree);
7334           }
7335
7336         tree val_tree;
7337         if (this->code_ == BUILTIN_LEN)
7338           {
7339             if (arg_type->is_string_type())
7340               val_tree = String_type::length_tree(gogo, arg_tree);
7341             else if (arg_type->array_type() != NULL)
7342               val_tree = arg_type->array_type()->length_tree(gogo, arg_tree);
7343             else if (arg_type->map_type() != NULL)
7344               {
7345                 static tree map_len_fndecl;
7346                 val_tree = Gogo::call_builtin(&map_len_fndecl,
7347                                               location,
7348                                               "__go_map_len",
7349                                               1,
7350                                               sizetype,
7351                                               arg_type->get_tree(gogo),
7352                                               arg_tree);
7353               }
7354             else if (arg_type->channel_type() != NULL)
7355               {
7356                 static tree chan_len_fndecl;
7357                 val_tree = Gogo::call_builtin(&chan_len_fndecl,
7358                                               location,
7359                                               "__go_chan_len",
7360                                               1,
7361                                               sizetype,
7362                                               arg_type->get_tree(gogo),
7363                                               arg_tree);
7364               }
7365             else
7366               gcc_unreachable();
7367           }
7368         else
7369           {
7370             if (arg_type->array_type() != NULL)
7371               val_tree = arg_type->array_type()->capacity_tree(gogo, arg_tree);
7372             else if (arg_type->channel_type() != NULL)
7373               {
7374                 static tree chan_cap_fndecl;
7375                 val_tree = Gogo::call_builtin(&chan_cap_fndecl,
7376                                               location,
7377                                               "__go_chan_cap",
7378                                               1,
7379                                               sizetype,
7380                                               arg_type->get_tree(gogo),
7381                                               arg_tree);
7382               }
7383             else
7384               gcc_unreachable();
7385           }
7386
7387         tree type_tree = Type::lookup_integer_type("int")->get_tree(gogo);
7388         if (type_tree == TREE_TYPE(val_tree))
7389           return val_tree;
7390         else
7391           return fold(convert_to_integer(type_tree, val_tree));
7392       }
7393
7394     case BUILTIN_PRINT:
7395     case BUILTIN_PRINTLN:
7396       {
7397         const bool is_ln = this->code_ == BUILTIN_PRINTLN;
7398         tree stmt_list = NULL_TREE;
7399
7400         const Expression_list* call_args = this->args();
7401         if (call_args != NULL)
7402           {
7403             for (Expression_list::const_iterator p = call_args->begin();
7404                  p != call_args->end();
7405                  ++p)
7406               {
7407                 if (is_ln && p != call_args->begin())
7408                   {
7409                     static tree print_space_fndecl;
7410                     tree call = Gogo::call_builtin(&print_space_fndecl,
7411                                                    location,
7412                                                    "__go_print_space",
7413                                                    0,
7414                                                    void_type_node);
7415                     append_to_statement_list(call, &stmt_list);
7416                   }
7417
7418                 Type* type = (*p)->type();
7419
7420                 tree arg = (*p)->get_tree(context);
7421                 if (arg == error_mark_node)
7422                   return error_mark_node;
7423
7424                 tree* pfndecl;
7425                 const char* fnname;
7426                 if (type->is_string_type())
7427                   {
7428                     static tree print_string_fndecl;
7429                     pfndecl = &print_string_fndecl;
7430                     fnname = "__go_print_string";
7431                   }
7432                 else if (type->integer_type() != NULL
7433                          && type->integer_type()->is_unsigned())
7434                   {
7435                     static tree print_uint64_fndecl;
7436                     pfndecl = &print_uint64_fndecl;
7437                     fnname = "__go_print_uint64";
7438                     Type* itype = Type::lookup_integer_type("uint64");
7439                     arg = fold_convert_loc(location, itype->get_tree(gogo),
7440                                            arg);
7441                   }
7442                 else if (type->integer_type() != NULL)
7443                   {
7444                     static tree print_int64_fndecl;
7445                     pfndecl = &print_int64_fndecl;
7446                     fnname = "__go_print_int64";
7447                     Type* itype = Type::lookup_integer_type("int64");
7448                     arg = fold_convert_loc(location, itype->get_tree(gogo),
7449                                            arg);
7450                   }
7451                 else if (type->float_type() != NULL)
7452                   {
7453                     static tree print_double_fndecl;
7454                     pfndecl = &print_double_fndecl;
7455                     fnname = "__go_print_double";
7456                     arg = fold_convert_loc(location, double_type_node, arg);
7457                   }
7458                 else if (type->complex_type() != NULL)
7459                   {
7460                     static tree print_complex_fndecl;
7461                     pfndecl = &print_complex_fndecl;
7462                     fnname = "__go_print_complex";
7463                     arg = fold_convert_loc(location, complex_double_type_node,
7464                                            arg);
7465                   }
7466                 else if (type->is_boolean_type())
7467                   {
7468                     static tree print_bool_fndecl;
7469                     pfndecl = &print_bool_fndecl;
7470                     fnname = "__go_print_bool";
7471                   }
7472                 else if (type->points_to() != NULL
7473                          || type->channel_type() != NULL
7474                          || type->map_type() != NULL
7475                          || type->function_type() != NULL)
7476                   {
7477                     static tree print_pointer_fndecl;
7478                     pfndecl = &print_pointer_fndecl;
7479                     fnname = "__go_print_pointer";
7480                     arg = fold_convert_loc(location, ptr_type_node, arg);
7481                   }
7482                 else if (type->interface_type() != NULL)
7483                   {
7484                     if (type->interface_type()->is_empty())
7485                       {
7486                         static tree print_empty_interface_fndecl;
7487                         pfndecl = &print_empty_interface_fndecl;
7488                         fnname = "__go_print_empty_interface";
7489                       }
7490                     else
7491                       {
7492                         static tree print_interface_fndecl;
7493                         pfndecl = &print_interface_fndecl;
7494                         fnname = "__go_print_interface";
7495                       }
7496                   }
7497                 else if (type->is_open_array_type())
7498                   {
7499                     static tree print_slice_fndecl;
7500                     pfndecl = &print_slice_fndecl;
7501                     fnname = "__go_print_slice";
7502                   }
7503                 else
7504                   gcc_unreachable();
7505
7506                 tree call = Gogo::call_builtin(pfndecl,
7507                                                location,
7508                                                fnname,
7509                                                1,
7510                                                void_type_node,
7511                                                TREE_TYPE(arg),
7512                                                arg);
7513                 append_to_statement_list(call, &stmt_list);
7514               }
7515           }
7516
7517         if (is_ln)
7518           {
7519             static tree print_nl_fndecl;
7520             tree call = Gogo::call_builtin(&print_nl_fndecl,
7521                                            location,
7522                                            "__go_print_nl",
7523                                            0,
7524                                            void_type_node);
7525             append_to_statement_list(call, &stmt_list);
7526           }
7527
7528         return stmt_list;
7529       }
7530
7531     case BUILTIN_PANIC:
7532       {
7533         const Expression_list* args = this->args();
7534         gcc_assert(args != NULL && args->size() == 1);
7535         Expression* arg = args->front();
7536         tree arg_tree = arg->get_tree(context);
7537         if (arg_tree == error_mark_node)
7538           return error_mark_node;
7539         Type *empty = Type::make_interface_type(NULL, BUILTINS_LOCATION);
7540         arg_tree = Expression::convert_for_assignment(context, empty,
7541                                                       arg->type(),
7542                                                       arg_tree, location);
7543         static tree panic_fndecl;
7544         tree call = Gogo::call_builtin(&panic_fndecl,
7545                                        location,
7546                                        "__go_panic",
7547                                        1,
7548                                        void_type_node,
7549                                        TREE_TYPE(arg_tree),
7550                                        arg_tree);
7551         // This function will throw an exception.
7552         TREE_NOTHROW(panic_fndecl) = 0;
7553         // This function will not return.
7554         TREE_THIS_VOLATILE(panic_fndecl) = 1;
7555         return call;
7556       }
7557
7558     case BUILTIN_RECOVER:
7559       {
7560         // The argument is set when building recover thunks.  It's a
7561         // boolean value which is true if we can recover a value now.
7562         const Expression_list* args = this->args();
7563         gcc_assert(args != NULL && args->size() == 1);
7564         Expression* arg = args->front();
7565         tree arg_tree = arg->get_tree(context);
7566         if (arg_tree == error_mark_node)
7567           return error_mark_node;
7568
7569         Type *empty = Type::make_interface_type(NULL, BUILTINS_LOCATION);
7570         tree empty_tree = empty->get_tree(context->gogo());
7571
7572         Type* nil_type = Type::make_nil_type();
7573         Expression* nil = Expression::make_nil(location);
7574         tree nil_tree = nil->get_tree(context);
7575         tree empty_nil_tree = Expression::convert_for_assignment(context,
7576                                                                  empty,
7577                                                                  nil_type,
7578                                                                  nil_tree,
7579                                                                  location);
7580
7581         // We need to handle a deferred call to recover specially,
7582         // because it changes whether it can recover a panic or not.
7583         // See test7 in test/recover1.go.
7584         tree call;
7585         if (this->is_deferred())
7586           {
7587             static tree deferred_recover_fndecl;
7588             call = Gogo::call_builtin(&deferred_recover_fndecl,
7589                                       location,
7590                                       "__go_deferred_recover",
7591                                       0,
7592                                       empty_tree);
7593           }
7594         else
7595           {
7596             static tree recover_fndecl;
7597             call = Gogo::call_builtin(&recover_fndecl,
7598                                       location,
7599                                       "__go_recover",
7600                                       0,
7601                                       empty_tree);
7602           }
7603         return fold_build3_loc(location, COND_EXPR, empty_tree, arg_tree,
7604                                call, empty_nil_tree);
7605       }
7606
7607     case BUILTIN_CLOSE:
7608     case BUILTIN_CLOSED:
7609       {
7610         const Expression_list* args = this->args();
7611         gcc_assert(args != NULL && args->size() == 1);
7612         Expression* arg = args->front();
7613         tree arg_tree = arg->get_tree(context);
7614         if (arg_tree == error_mark_node)
7615           return error_mark_node;
7616         if (this->code_ == BUILTIN_CLOSE)
7617           {
7618             static tree close_fndecl;
7619             return Gogo::call_builtin(&close_fndecl,
7620                                       location,
7621                                       "__go_builtin_close",
7622                                       1,
7623                                       void_type_node,
7624                                       TREE_TYPE(arg_tree),
7625                                       arg_tree);
7626           }
7627         else
7628           {
7629             static tree closed_fndecl;
7630             return Gogo::call_builtin(&closed_fndecl,
7631                                       location,
7632                                       "__go_builtin_closed",
7633                                       1,
7634                                       boolean_type_node,
7635                                       TREE_TYPE(arg_tree),
7636                                       arg_tree);
7637           }
7638       }
7639
7640     case BUILTIN_SIZEOF:
7641     case BUILTIN_OFFSETOF:
7642     case BUILTIN_ALIGNOF:
7643       {
7644         mpz_t val;
7645         mpz_init(val);
7646         Type* dummy;
7647         bool b = this->integer_constant_value(true, val, &dummy);
7648         gcc_assert(b);
7649         tree type = Type::lookup_integer_type("int")->get_tree(gogo);
7650         tree ret = Expression::integer_constant_tree(val, type);
7651         mpz_clear(val);
7652         return ret;
7653       }
7654
7655     case BUILTIN_COPY:
7656       {
7657         const Expression_list* args = this->args();
7658         gcc_assert(args != NULL && args->size() == 2);
7659         Expression* arg1 = args->front();
7660         Expression* arg2 = args->back();
7661
7662         tree arg1_tree = arg1->get_tree(context);
7663         tree arg2_tree = arg2->get_tree(context);
7664         if (arg1_tree == error_mark_node || arg2_tree == error_mark_node)
7665           return error_mark_node;
7666
7667         Type* arg1_type = arg1->type();
7668         Array_type* at = arg1_type->array_type();
7669         arg1_tree = save_expr(arg1_tree);
7670         tree arg1_val = at->value_pointer_tree(gogo, arg1_tree);
7671         tree arg1_len = at->length_tree(gogo, arg1_tree);
7672
7673         Type* arg2_type = arg2->type();
7674         tree arg2_val;
7675         tree arg2_len;
7676         if (arg2_type->is_open_array_type())
7677           {
7678             at = arg2_type->array_type();
7679             arg2_tree = save_expr(arg2_tree);
7680             arg2_val = at->value_pointer_tree(gogo, arg2_tree);
7681             arg2_len = at->length_tree(gogo, arg2_tree);
7682           }
7683         else
7684           {
7685             arg2_tree = save_expr(arg2_tree);
7686             arg2_val = String_type::bytes_tree(gogo, arg2_tree);
7687             arg2_len = String_type::length_tree(gogo, arg2_tree);
7688           }
7689
7690         arg1_len = save_expr(arg1_len);
7691         arg2_len = save_expr(arg2_len);
7692         tree len = fold_build3_loc(location, COND_EXPR, TREE_TYPE(arg1_len),
7693                                    fold_build2_loc(location, LT_EXPR,
7694                                                    boolean_type_node,
7695                                                    arg1_len, arg2_len),
7696                                    arg1_len, arg2_len);
7697         len = save_expr(len);
7698
7699         Type* element_type = at->element_type();
7700         tree element_type_tree = element_type->get_tree(gogo);
7701         tree element_size = TYPE_SIZE_UNIT(element_type_tree);
7702         tree bytecount = fold_convert_loc(location, TREE_TYPE(element_size),
7703                                           len);
7704         bytecount = fold_build2_loc(location, MULT_EXPR,
7705                                     TREE_TYPE(element_size),
7706                                     bytecount, element_size);
7707         bytecount = fold_convert_loc(location, size_type_node, bytecount);
7708
7709         tree call = build_call_expr_loc(location,
7710                                         built_in_decls[BUILT_IN_MEMMOVE],
7711                                         3, arg1_val, arg2_val, bytecount);
7712
7713         return fold_build2_loc(location, COMPOUND_EXPR, TREE_TYPE(len),
7714                                call, len);
7715       }
7716
7717     case BUILTIN_APPEND:
7718       {
7719         const Expression_list* args = this->args();
7720         gcc_assert(args != NULL && args->size() == 2);
7721         Expression* arg1 = args->front();
7722         Expression* arg2 = args->back();
7723
7724         tree arg1_tree = arg1->get_tree(context);
7725         tree arg2_tree = arg2->get_tree(context);
7726         if (arg1_tree == error_mark_node || arg2_tree == error_mark_node)
7727           return error_mark_node;
7728
7729         tree descriptor_tree = arg1->type()->type_descriptor_pointer(gogo);
7730
7731         // We rebuild the decl each time since the slice types may
7732         // change.
7733         tree append_fndecl = NULL_TREE;
7734         return Gogo::call_builtin(&append_fndecl,
7735                                   location,
7736                                   "__go_append",
7737                                   3,
7738                                   TREE_TYPE(arg1_tree),
7739                                   TREE_TYPE(descriptor_tree),
7740                                   descriptor_tree,
7741                                   TREE_TYPE(arg1_tree),
7742                                   arg1_tree,
7743                                   TREE_TYPE(arg2_tree),
7744                                   arg2_tree);
7745       }
7746
7747     case BUILTIN_REAL:
7748     case BUILTIN_IMAG:
7749       {
7750         const Expression_list* args = this->args();
7751         gcc_assert(args != NULL && args->size() == 1);
7752         Expression* arg = args->front();
7753         tree arg_tree = arg->get_tree(context);
7754         if (arg_tree == error_mark_node)
7755           return error_mark_node;
7756         gcc_assert(COMPLEX_FLOAT_TYPE_P(TREE_TYPE(arg_tree)));
7757         if (this->code_ == BUILTIN_REAL)
7758           return fold_build1_loc(location, REALPART_EXPR,
7759                                  TREE_TYPE(TREE_TYPE(arg_tree)),
7760                                  arg_tree);
7761         else
7762           return fold_build1_loc(location, IMAGPART_EXPR,
7763                                  TREE_TYPE(TREE_TYPE(arg_tree)),
7764                                  arg_tree);
7765       }
7766
7767     case BUILTIN_CMPLX:
7768       {
7769         const Expression_list* args = this->args();
7770         gcc_assert(args != NULL && args->size() == 2);
7771         tree r = args->front()->get_tree(context);
7772         tree i = args->back()->get_tree(context);
7773         if (r == error_mark_node || i == error_mark_node)
7774           return error_mark_node;
7775         gcc_assert(TYPE_MAIN_VARIANT(TREE_TYPE(r))
7776                    == TYPE_MAIN_VARIANT(TREE_TYPE(i)));
7777         gcc_assert(SCALAR_FLOAT_TYPE_P(TREE_TYPE(r)));
7778         return fold_build2_loc(location, COMPLEX_EXPR,
7779                                build_complex_type(TREE_TYPE(r)),
7780                                r, i);
7781       }
7782
7783     default:
7784       gcc_unreachable();
7785     }
7786 }
7787
7788 // We have to support exporting a builtin call expression, because
7789 // code can set a constant to the result of a builtin expression.
7790
7791 void
7792 Builtin_call_expression::do_export(Export* exp) const
7793 {
7794   bool ok = false;
7795
7796   mpz_t val;
7797   mpz_init(val);
7798   Type* dummy;
7799   if (this->integer_constant_value(true, val, &dummy))
7800     {
7801       Integer_expression::export_integer(exp, val);
7802       ok = true;
7803     }
7804   mpz_clear(val);
7805
7806   if (!ok)
7807     {
7808       mpfr_t fval;
7809       mpfr_init(fval);
7810       if (this->float_constant_value(fval, &dummy))
7811         {
7812           Float_expression::export_float(exp, fval);
7813           ok = true;
7814         }
7815       mpfr_clear(fval);
7816     }
7817
7818   if (!ok)
7819     {
7820       mpfr_t real;
7821       mpfr_t imag;
7822       mpfr_init(real);
7823       mpfr_init(imag);
7824       if (this->complex_constant_value(real, imag, &dummy))
7825         {
7826           Complex_expression::export_complex(exp, real, imag);
7827           ok = true;
7828         }
7829       mpfr_clear(real);
7830       mpfr_clear(imag);
7831     }
7832
7833   if (!ok)
7834     {
7835       error_at(this->location(), "value is not constant");
7836       return;
7837     }
7838
7839   // A trailing space lets us reliably identify the end of the number.
7840   exp->write_c_string(" ");
7841 }
7842
7843 // Class Call_expression.
7844
7845 // Traversal.
7846
7847 int
7848 Call_expression::do_traverse(Traverse* traverse)
7849 {
7850   if (Expression::traverse(&this->fn_, traverse) == TRAVERSE_EXIT)
7851     return TRAVERSE_EXIT;
7852   if (this->args_ != NULL)
7853     {
7854       if (this->args_->traverse(traverse) == TRAVERSE_EXIT)
7855         return TRAVERSE_EXIT;
7856     }
7857   return TRAVERSE_CONTINUE;
7858 }
7859
7860 // Lower a call statement.
7861
7862 Expression*
7863 Call_expression::do_lower(Gogo* gogo, Named_object* function, int)
7864 {
7865   // A type case can look like a function call.
7866   if (this->fn_->is_type_expression()
7867       && this->args_ != NULL
7868       && this->args_->size() == 1)
7869     return Expression::make_cast(this->fn_->type(), this->args_->front(),
7870                                  this->location());
7871
7872   // Recognize a call to a builtin function.
7873   Func_expression* fne = this->fn_->func_expression();
7874   if (fne != NULL
7875       && fne->named_object()->is_function_declaration()
7876       && fne->named_object()->func_declaration_value()->type()->is_builtin())
7877     return new Builtin_call_expression(gogo, this->fn_, this->args_,
7878                                        this->is_varargs_, this->location());
7879
7880   // Handle an argument which is a call to a function which returns
7881   // multiple results.
7882   if (this->args_ != NULL
7883       && this->args_->size() == 1
7884       && this->args_->front()->call_expression() != NULL
7885       && this->fn_->type()->function_type() != NULL)
7886     {
7887       Function_type* fntype = this->fn_->type()->function_type();
7888       size_t rc = this->args_->front()->call_expression()->result_count();
7889       if (rc > 1
7890           && fntype->parameters() != NULL
7891           && (fntype->parameters()->size() == rc
7892               || (fntype->is_varargs()
7893                   && fntype->parameters()->size() - 1 <= rc)))
7894         {
7895           Call_expression* call = this->args_->front()->call_expression();
7896           Expression_list* args = new Expression_list;
7897           for (size_t i = 0; i < rc; ++i)
7898             args->push_back(Expression::make_call_result(call, i));
7899           // We can't return a new call expression here, because this
7900           // one may be referenced by Call_result expressions.  FIXME.
7901           delete this->args_;
7902           this->args_ = args;
7903         }
7904     }
7905
7906   // Handle a call to a varargs function by packaging up the extra
7907   // parameters.
7908   if (this->fn_->type()->function_type() != NULL
7909       && this->fn_->type()->function_type()->is_varargs())
7910     {
7911       Function_type* fntype = this->fn_->type()->function_type();
7912       const Typed_identifier_list* parameters = fntype->parameters();
7913       gcc_assert(parameters != NULL && !parameters->empty());
7914       Type* varargs_type = parameters->back().type();
7915       return this->lower_varargs(gogo, function, varargs_type,
7916                                  parameters->size());
7917     }
7918
7919   return this;
7920 }
7921
7922 // Lower a call to a varargs function.  FUNCTION is the function in
7923 // which the call occurs--it's not the function we are calling.
7924 // VARARGS_TYPE is the type of the varargs parameter, a slice type.
7925 // PARAM_COUNT is the number of parameters of the function we are
7926 // calling; the last of these parameters will be the varargs
7927 // parameter.
7928
7929 Expression*
7930 Call_expression::lower_varargs(Gogo* gogo, Named_object* function,
7931                                Type* varargs_type, size_t param_count)
7932 {
7933   if (this->varargs_are_lowered_)
7934     return this;
7935
7936   source_location loc = this->location();
7937
7938   gcc_assert(param_count > 0);
7939   gcc_assert(varargs_type->is_open_array_type());
7940
7941   size_t arg_count = this->args_ == NULL ? 0 : this->args_->size();
7942   if (arg_count < param_count - 1)
7943     {
7944       // Not enough arguments; will be caught in check_types.
7945       return this;
7946     }
7947
7948   Expression_list* old_args = this->args_;
7949   Expression_list* new_args = new Expression_list();
7950   bool push_empty_arg = false;
7951   if (old_args == NULL || old_args->empty())
7952     {
7953       gcc_assert(param_count == 1);
7954       push_empty_arg = true;
7955     }
7956   else
7957     {
7958       Expression_list::const_iterator pa;
7959       int i = 1;
7960       for (pa = old_args->begin(); pa != old_args->end(); ++pa, ++i)
7961         {
7962           if (static_cast<size_t>(i) == param_count)
7963             break;
7964           new_args->push_back(*pa);
7965         }
7966
7967       // We have reached the varargs parameter.
7968
7969       bool issued_error = false;
7970       if (pa == old_args->end())
7971         push_empty_arg = true;
7972       else if (pa + 1 == old_args->end() && this->is_varargs_)
7973         new_args->push_back(*pa);
7974       else if (this->is_varargs_)
7975         {
7976           this->report_error(_("too many arguments"));
7977           return this;
7978         }
7979       else if (pa + 1 == old_args->end()
7980                && this->is_compatible_varargs_argument(function, *pa,
7981                                                        varargs_type,
7982                                                        &issued_error))
7983         new_args->push_back(*pa);
7984       else
7985         {
7986           Type* element_type = varargs_type->array_type()->element_type();
7987           Expression_list* vals = new Expression_list;
7988           for (; pa != old_args->end(); ++pa, ++i)
7989             {
7990               // Check types here so that we get a better message.
7991               Type* patype = (*pa)->type();
7992               source_location paloc = (*pa)->location();
7993               if (!this->check_argument_type(i, element_type, patype,
7994                                              paloc, issued_error))
7995                 continue;
7996               vals->push_back(*pa);
7997             }
7998           Expression* val =
7999             Expression::make_slice_composite_literal(varargs_type, vals, loc);
8000           new_args->push_back(val);
8001         }
8002     }
8003
8004   if (push_empty_arg)
8005     new_args->push_back(Expression::make_nil(loc));
8006
8007   // We can't return a new call expression here, because this one may
8008   // be referenced by Call_result expressions.  FIXME.
8009   if (old_args != NULL)
8010     delete old_args;
8011   this->args_ = new_args;
8012   this->varargs_are_lowered_ = true;
8013
8014   // Lower all the new subexpressions.
8015   Expression* ret = this;
8016   gogo->lower_expression(function, &ret);
8017   gcc_assert(ret == this);
8018   return ret;
8019 }
8020
8021 // Return true if ARG is a varargs argment which should be passed to
8022 // the varargs parameter of type PARAM_TYPE without wrapping.  ARG
8023 // will be the last argument passed in the call, and PARAM_TYPE will
8024 // be the type of the last parameter of the varargs function being
8025 // called.
8026
8027 bool
8028 Call_expression::is_compatible_varargs_argument(Named_object* function,
8029                                                 Expression* arg,
8030                                                 Type* param_type,
8031                                                 bool* issued_error)
8032 {
8033   *issued_error = false;
8034
8035   Type* var_type = NULL;
8036
8037   // The simple case is passing the varargs parameter of the caller.
8038   Var_expression* ve = arg->var_expression();
8039   if (ve != NULL && ve->named_object()->is_variable())
8040     {
8041       Variable* var = ve->named_object()->var_value();
8042       if (var->is_varargs_parameter())
8043         var_type = var->type();
8044     }
8045
8046   // The complex case is passing the varargs parameter of some
8047   // enclosing function.  This will look like passing down *c.f where
8048   // c is the closure variable and f is a field in the closure.
8049   if (function != NULL
8050       && function->func_value()->needs_closure()
8051       && arg->classification() == EXPRESSION_UNARY)
8052     {
8053       Unary_expression* ue = static_cast<Unary_expression*>(arg);
8054       if (ue->op() == OPERATOR_MULT)
8055         {
8056           Field_reference_expression* fre =
8057             ue->operand()->deref()->field_reference_expression();
8058           if (fre != NULL)
8059             {
8060               Var_expression* ve = fre->expr()->deref()->var_expression();
8061               if (ve != NULL)
8062                 {
8063                   Named_object* no = ve->named_object();
8064                   Function* f = function->func_value();
8065                   if (no == f->closure_var())
8066                     {
8067                       // At this point we know that this indeed a
8068                       // reference to some enclosing variable.  Now we
8069                       // need to figure out whether that variable is a
8070                       // varargs parameter.
8071                       Named_object* enclosing =
8072                         f->enclosing_var(fre->field_index());
8073                       Variable* var = enclosing->var_value();
8074                       if (var->is_varargs_parameter())
8075                         var_type = var->type();
8076                     }
8077                 }
8078             }
8079         }
8080     }
8081
8082   if (var_type == NULL)
8083     return false;
8084
8085   // We only match if the parameter is the same, with an identical
8086   // type.
8087   Array_type* var_at = var_type->array_type();
8088   gcc_assert(var_at != NULL);
8089   Array_type* param_at = param_type->array_type();
8090   if (param_at != NULL
8091       && Type::are_identical(var_at->element_type(),
8092                              param_at->element_type(), NULL))
8093     return true;
8094   error_at(arg->location(), "... mismatch: passing ...T as ...");
8095   *issued_error = true;
8096   return false;
8097 }
8098
8099 // Get the function type.  Returns NULL if we don't know the type.  If
8100 // this returns NULL, and if_ERROR is true, issues an error.
8101
8102 Function_type*
8103 Call_expression::get_function_type() const
8104 {
8105   return this->fn_->type()->function_type();
8106 }
8107
8108 // Return the number of values which this call will return.
8109
8110 size_t
8111 Call_expression::result_count() const
8112 {
8113   const Function_type* fntype = this->get_function_type();
8114   if (fntype == NULL)
8115     return 0;
8116   if (fntype->results() == NULL)
8117     return 0;
8118   return fntype->results()->size();
8119 }
8120
8121 // Return whether this is a call to the predeclared function recover.
8122
8123 bool
8124 Call_expression::is_recover_call() const
8125 {
8126   return this->do_is_recover_call();
8127 }
8128
8129 // Set the argument to the recover function.
8130
8131 void
8132 Call_expression::set_recover_arg(Expression* arg)
8133 {
8134   this->do_set_recover_arg(arg);
8135 }
8136
8137 // Virtual functions also implemented by Builtin_call_expression.
8138
8139 bool
8140 Call_expression::do_is_recover_call() const
8141 {
8142   return false;
8143 }
8144
8145 void
8146 Call_expression::do_set_recover_arg(Expression*)
8147 {
8148   gcc_unreachable();
8149 }
8150
8151 // Get the type.
8152
8153 Type*
8154 Call_expression::do_type()
8155 {
8156   if (this->type_ != NULL)
8157     return this->type_;
8158
8159   Type* ret;
8160   Function_type* fntype = this->get_function_type();
8161   if (fntype == NULL)
8162     return Type::make_error_type();
8163
8164   const Typed_identifier_list* results = fntype->results();
8165   if (results == NULL)
8166     ret = Type::make_void_type();
8167   else if (results->size() == 1)
8168     ret = results->begin()->type();
8169   else
8170     ret = Type::make_call_multiple_result_type(this);
8171
8172   this->type_ = ret;
8173
8174   return this->type_;
8175 }
8176
8177 // Determine types for a call expression.  We can use the function
8178 // parameter types to set the types of the arguments.
8179
8180 void
8181 Call_expression::do_determine_type(const Type_context*)
8182 {
8183   this->fn_->determine_type_no_context();
8184   Function_type* fntype = this->get_function_type();
8185   const Typed_identifier_list* parameters = NULL;
8186   if (fntype != NULL)
8187     parameters = fntype->parameters();
8188   if (this->args_ != NULL)
8189     {
8190       Typed_identifier_list::const_iterator pt;
8191       if (parameters != NULL)
8192         pt = parameters->begin();
8193       for (Expression_list::const_iterator pa = this->args_->begin();
8194            pa != this->args_->end();
8195            ++pa)
8196         {
8197           if (parameters != NULL && pt != parameters->end())
8198             {
8199               Type_context subcontext(pt->type(), false);
8200               (*pa)->determine_type(&subcontext);
8201               ++pt;
8202             }
8203           else
8204             (*pa)->determine_type_no_context();
8205         }
8206     }
8207 }
8208
8209 // Check types for parameter I.
8210
8211 bool
8212 Call_expression::check_argument_type(int i, const Type* parameter_type,
8213                                      const Type* argument_type,
8214                                      source_location argument_location,
8215                                      bool issued_error)
8216 {
8217   std::string reason;
8218   if (!Type::are_assignable(parameter_type, argument_type, &reason))
8219     {
8220       if (!issued_error)
8221         {
8222           if (reason.empty())
8223             error_at(argument_location, "argument %d has incompatible type", i);
8224           else
8225             error_at(argument_location,
8226                      "argument %d has incompatible type (%s)",
8227                      i, reason.c_str());
8228         }
8229       this->set_is_error();
8230       return false;
8231     }
8232   return true;
8233 }
8234
8235 // Check types.
8236
8237 void
8238 Call_expression::do_check_types(Gogo*)
8239 {
8240   Function_type* fntype = this->get_function_type();
8241   if (fntype == NULL)
8242     {
8243       if (!this->fn_->type()->is_error_type())
8244         this->report_error(_("expected function"));
8245       return;
8246     }
8247
8248   if (fntype->is_method())
8249     {
8250       // We don't support pointers to methods, so the function has to
8251       // be a bound method expression.
8252       Bound_method_expression* bme = this->fn_->bound_method_expression();
8253       if (bme == NULL)
8254         {
8255           this->report_error(_("method call without object"));
8256           return;
8257         }
8258       Type* first_arg_type = bme->first_argument()->type();
8259       if (first_arg_type->points_to() == NULL)
8260         {
8261           // When passing a value, we need to check that we are
8262           // permitted to copy it.
8263           std::string reason;
8264           if (!Type::are_assignable(fntype->receiver()->type(),
8265                                     first_arg_type, &reason))
8266             {
8267               if (reason.empty())
8268                 this->report_error(_("incompatible type for receiver"));
8269               else
8270                 {
8271                   error_at(this->location(),
8272                            "incompatible type for receiver (%s)",
8273                            reason.c_str());
8274                   this->set_is_error();
8275                 }
8276             }
8277         }
8278     }
8279
8280   // Note that varargs was handled by the lower_varargs() method, so
8281   // we don't have to worry about it here.
8282
8283   const Typed_identifier_list* parameters = fntype->parameters();
8284   if (this->args_ == NULL)
8285     {
8286       if (parameters != NULL && !parameters->empty())
8287         this->report_error(_("not enough arguments"));
8288     }
8289   else if (parameters == NULL)
8290     this->report_error(_("too many arguments"));
8291   else
8292     {
8293       int i = 0;
8294       Typed_identifier_list::const_iterator pt = parameters->begin();
8295       for (Expression_list::const_iterator pa = this->args_->begin();
8296            pa != this->args_->end();
8297            ++pa, ++pt, ++i)
8298         {
8299           if (pt == parameters->end())
8300             {
8301               this->report_error(_("too many arguments"));
8302               return;
8303             }
8304           this->check_argument_type(i + 1, pt->type(), (*pa)->type(),
8305                                     (*pa)->location(), false);
8306         }
8307       if (pt != parameters->end())
8308         this->report_error(_("not enough arguments"));
8309     }
8310 }
8311
8312 // Return whether we have to use a temporary variable to ensure that
8313 // we evaluate this call expression in order.  If the call returns no
8314 // results then it will inevitably be executed last.  If the call
8315 // returns more than one result then it will be used with Call_result
8316 // expressions.  So we only have to use a temporary variable if the
8317 // call returns exactly one result.
8318
8319 bool
8320 Call_expression::do_must_eval_in_order() const
8321 {
8322   return this->result_count() == 1;
8323 }
8324
8325 // Get the function and the first argument to use when calling a bound
8326 // method.
8327
8328 tree
8329 Call_expression::bound_method_function(Translate_context* context,
8330                                        Bound_method_expression* bound_method,
8331                                        tree* first_arg_ptr)
8332 {
8333   Expression* first_argument = bound_method->first_argument();
8334   tree first_arg = first_argument->get_tree(context);
8335   if (first_arg == error_mark_node)
8336     return error_mark_node;
8337
8338   // We always pass a pointer to the first argument when calling a
8339   // method.
8340   if (first_argument->type()->points_to() == NULL)
8341     {
8342       tree pointer_to_arg_type = build_pointer_type(TREE_TYPE(first_arg));
8343       if (TREE_ADDRESSABLE(TREE_TYPE(first_arg))
8344           || DECL_P(first_arg)
8345           || TREE_CODE(first_arg) == INDIRECT_REF
8346           || TREE_CODE(first_arg) == COMPONENT_REF)
8347         {
8348           first_arg = build_fold_addr_expr(first_arg);
8349           if (DECL_P(first_arg))
8350             TREE_ADDRESSABLE(first_arg) = 1;
8351         }
8352       else
8353         {
8354           tree tmp = create_tmp_var(TREE_TYPE(first_arg),
8355                                     get_name(first_arg));
8356           DECL_IGNORED_P(tmp) = 0;
8357           DECL_INITIAL(tmp) = first_arg;
8358           first_arg = build2(COMPOUND_EXPR, pointer_to_arg_type,
8359                              build1(DECL_EXPR, void_type_node, tmp),
8360                              build_fold_addr_expr(tmp));
8361           TREE_ADDRESSABLE(tmp) = 1;
8362         }
8363       if (first_arg == error_mark_node)
8364         return error_mark_node;
8365     }
8366
8367   Type* fatype = bound_method->first_argument_type();
8368   if (fatype != NULL)
8369     {
8370       if (fatype->points_to() == NULL)
8371         fatype = Type::make_pointer_type(fatype);
8372       first_arg = fold_convert(fatype->get_tree(context->gogo()), first_arg);
8373       if (first_arg == error_mark_node
8374           || TREE_TYPE(first_arg) == error_mark_node)
8375         return error_mark_node;
8376     }
8377
8378   *first_arg_ptr = first_arg;
8379
8380   return bound_method->method()->get_tree(context);
8381 }
8382
8383 // Get the function and the first argument to use when calling an
8384 // interface method.
8385
8386 tree
8387 Call_expression::interface_method_function(
8388     Translate_context* context,
8389     Interface_field_reference_expression* interface_method,
8390     tree* first_arg_ptr)
8391 {
8392   tree expr = interface_method->expr()->get_tree(context);
8393   if (expr == error_mark_node)
8394     return error_mark_node;
8395   expr = save_expr(expr);
8396   tree first_arg = interface_method->get_underlying_object_tree(context, expr);
8397   if (first_arg == error_mark_node)
8398     return error_mark_node;
8399   *first_arg_ptr = first_arg;
8400   return interface_method->get_function_tree(context, expr);
8401 }
8402
8403 // Build the call expression.
8404
8405 tree
8406 Call_expression::do_get_tree(Translate_context* context)
8407 {
8408   if (this->tree_ != NULL_TREE)
8409     return this->tree_;
8410
8411   Function_type* fntype = this->get_function_type();
8412   if (fntype == NULL)
8413     return error_mark_node;
8414
8415   if (this->fn_->is_error_expression())
8416     return error_mark_node;
8417
8418   Gogo* gogo = context->gogo();
8419   source_location location = this->location();
8420
8421   Func_expression* func = this->fn_->func_expression();
8422   Bound_method_expression* bound_method = this->fn_->bound_method_expression();
8423   Interface_field_reference_expression* interface_method =
8424     this->fn_->interface_field_reference_expression();
8425   const bool has_closure = func != NULL && func->closure() != NULL;
8426   const bool is_method = bound_method != NULL || interface_method != NULL;
8427   gcc_assert(!fntype->is_method() || is_method);
8428
8429   int nargs;
8430   tree* args;
8431   if (this->args_ == NULL || this->args_->empty())
8432     {
8433       nargs = is_method ? 1 : 0;
8434       args = nargs == 0 ? NULL : new tree[nargs];
8435     }
8436   else
8437     {
8438       const Typed_identifier_list* params = fntype->parameters();
8439       gcc_assert(params != NULL);
8440
8441       nargs = this->args_->size();
8442       int i = is_method ? 1 : 0;
8443       nargs += i;
8444       args = new tree[nargs];
8445
8446       Typed_identifier_list::const_iterator pp = params->begin();
8447       Expression_list::const_iterator pe;
8448       for (pe = this->args_->begin();
8449            pe != this->args_->end();
8450            ++pe, ++pp, ++i)
8451         {
8452           tree arg_val = (*pe)->get_tree(context);
8453           args[i] = Expression::convert_for_assignment(context,
8454                                                        pp->type(),
8455                                                        (*pe)->type(),
8456                                                        arg_val,
8457                                                        location);
8458           if (args[i] == error_mark_node)
8459             return error_mark_node;
8460         }
8461       gcc_assert(pp == params->end());
8462       gcc_assert(i == nargs);
8463     }
8464
8465   tree rettype = TREE_TYPE(TREE_TYPE(fntype->get_tree(gogo)));
8466   if (rettype == error_mark_node)
8467     return error_mark_node;
8468
8469   tree fn;
8470   if (has_closure)
8471     fn = func->get_tree_without_closure(gogo);
8472   else if (!is_method)
8473     fn = this->fn_->get_tree(context);
8474   else if (bound_method != NULL)
8475     fn = this->bound_method_function(context, bound_method, &args[0]);
8476   else if (interface_method != NULL)
8477     fn = this->interface_method_function(context, interface_method, &args[0]);
8478   else
8479     gcc_unreachable();
8480
8481   if (fn == error_mark_node || TREE_TYPE(fn) == error_mark_node)
8482     return error_mark_node;
8483
8484   // This is to support builtin math functions when using 80387 math.
8485   tree fndecl = fn;
8486   if (TREE_CODE(fndecl) == ADDR_EXPR)
8487     fndecl = TREE_OPERAND(fndecl, 0);
8488   tree excess_type = NULL_TREE;
8489   if (DECL_P(fndecl)
8490       && DECL_IS_BUILTIN(fndecl)
8491       && DECL_BUILT_IN_CLASS(fndecl) == BUILT_IN_NORMAL
8492       && nargs > 0
8493       && ((SCALAR_FLOAT_TYPE_P(rettype)
8494            && SCALAR_FLOAT_TYPE_P(TREE_TYPE(args[0])))
8495           || (COMPLEX_FLOAT_TYPE_P(rettype)
8496               && COMPLEX_FLOAT_TYPE_P(TREE_TYPE(args[0])))))
8497     {
8498       excess_type = excess_precision_type(TREE_TYPE(args[0]));
8499       if (excess_type != NULL_TREE)
8500         {
8501           tree excess_fndecl = mathfn_built_in(excess_type,
8502                                                DECL_FUNCTION_CODE(fndecl));
8503           if (excess_fndecl == NULL_TREE)
8504             excess_type = NULL_TREE;
8505           else
8506             {
8507               fn = build_fold_addr_expr_loc(location, excess_fndecl);
8508               for (int i = 0; i < nargs; ++i)
8509                 args[i] = ::convert(excess_type, args[i]);
8510             }
8511         }
8512     }
8513
8514   tree ret = build_call_array(excess_type != NULL_TREE ? excess_type : rettype,
8515                               fn, nargs, args);
8516   delete[] args;
8517
8518   SET_EXPR_LOCATION(ret, location);
8519
8520   if (has_closure)
8521     {
8522       tree closure_tree = func->closure()->get_tree(context);
8523       if (closure_tree != error_mark_node)
8524         CALL_EXPR_STATIC_CHAIN(ret) = closure_tree;
8525     }
8526
8527   // If this is a recursive function type which returns itself, as in
8528   //   type F func() F
8529   // we have used ptr_type_node for the return type.  Add a cast here
8530   // to the correct type.
8531   if (TREE_TYPE(ret) == ptr_type_node)
8532     {
8533       tree t = this->type()->get_tree(gogo);
8534       ret = fold_convert_loc(location, t, ret);
8535     }
8536
8537   if (excess_type != NULL_TREE)
8538     {
8539       // Calling convert here can undo our excess precision change.
8540       // That may or may not be a bug in convert_to_real.
8541       ret = build1(NOP_EXPR, rettype, ret);
8542     }
8543
8544   // If there is more than one result, we will refer to the call
8545   // multiple times.
8546   if (fntype->results() != NULL && fntype->results()->size() > 1)
8547     ret = save_expr(ret);
8548
8549   this->tree_ = ret;
8550
8551   return ret;
8552 }
8553
8554 // Make a call expression.
8555
8556 Call_expression*
8557 Expression::make_call(Expression* fn, Expression_list* args, bool is_varargs,
8558                       source_location location)
8559 {
8560   return new Call_expression(fn, args, is_varargs, location);
8561 }
8562
8563 // A single result from a call which returns multiple results.
8564
8565 class Call_result_expression : public Expression
8566 {
8567  public:
8568   Call_result_expression(Call_expression* call, unsigned int index)
8569     : Expression(EXPRESSION_CALL_RESULT, call->location()),
8570       call_(call), index_(index)
8571   { }
8572
8573  protected:
8574   int
8575   do_traverse(Traverse*);
8576
8577   Type*
8578   do_type();
8579
8580   void
8581   do_determine_type(const Type_context*);
8582
8583   void
8584   do_check_types(Gogo*);
8585
8586   Expression*
8587   do_copy()
8588   {
8589     return new Call_result_expression(this->call_->call_expression(),
8590                                       this->index_);
8591   }
8592
8593   bool
8594   do_must_eval_in_order() const
8595   { return true; }
8596
8597   tree
8598   do_get_tree(Translate_context*);
8599
8600  private:
8601   // The underlying call expression.
8602   Expression* call_;
8603   // Which result we want.
8604   unsigned int index_;
8605 };
8606
8607 // Traverse a call result.
8608
8609 int
8610 Call_result_expression::do_traverse(Traverse* traverse)
8611 {
8612   if (traverse->remember_expression(this->call_))
8613     {
8614       // We have already traversed the call expression.
8615       return TRAVERSE_CONTINUE;
8616     }
8617   return Expression::traverse(&this->call_, traverse);
8618 }
8619
8620 // Get the type.
8621
8622 Type*
8623 Call_result_expression::do_type()
8624 {
8625   // THIS->CALL_ can be replaced with a temporary reference due to
8626   // Call_expression::do_must_eval_in_order when there is an error.
8627   Call_expression* ce = this->call_->call_expression();
8628   if (ce == NULL)
8629     return Type::make_error_type();
8630   Function_type* fntype = ce->get_function_type();
8631   if (fntype == NULL)
8632     return Type::make_error_type();
8633   const Typed_identifier_list* results = fntype->results();
8634   Typed_identifier_list::const_iterator pr = results->begin();
8635   for (unsigned int i = 0; i < this->index_; ++i)
8636     {
8637       if (pr == results->end())
8638         return Type::make_error_type();
8639       ++pr;
8640     }
8641   if (pr == results->end())
8642     return Type::make_error_type();
8643   return pr->type();
8644 }
8645
8646 // Check the type.  This is where we give an error if we're trying to
8647 // extract too many values from a call.
8648
8649 void
8650 Call_result_expression::do_check_types(Gogo*)
8651 {
8652   bool ok = true;
8653   Call_expression* ce = this->call_->call_expression();
8654   if (ce != NULL)
8655     ok = this->index_ < ce->result_count();
8656   else
8657     {
8658       // This can happen when the call returns a single value but we
8659       // are asking for the second result.
8660       if (this->call_->is_error_expression())
8661         return;
8662       ok = false;
8663     }
8664   if (!ok)
8665     this->report_error(_("number of results does not match number of values"));
8666 }
8667
8668 // Determine the type.  We have nothing to do here, but the 0 result
8669 // needs to pass down to the caller.
8670
8671 void
8672 Call_result_expression::do_determine_type(const Type_context*)
8673 {
8674   if (this->index_ == 0)
8675     this->call_->determine_type_no_context();
8676 }
8677
8678 // Return the tree.
8679
8680 tree
8681 Call_result_expression::do_get_tree(Translate_context* context)
8682 {
8683   tree call_tree = this->call_->get_tree(context);
8684   if (call_tree == error_mark_node)
8685     return error_mark_node;
8686   gcc_assert(TREE_CODE(TREE_TYPE(call_tree)) == RECORD_TYPE);
8687   tree field = TYPE_FIELDS(TREE_TYPE(call_tree));
8688   for (unsigned int i = 0; i < this->index_; ++i)
8689     {
8690       gcc_assert(field != NULL_TREE);
8691       field = DECL_CHAIN(field);
8692     }
8693   gcc_assert(field != NULL_TREE);
8694   return build3(COMPONENT_REF, TREE_TYPE(field), call_tree, field, NULL_TREE);
8695 }
8696
8697 // Make a reference to a single result of a call which returns
8698 // multiple results.
8699
8700 Expression*
8701 Expression::make_call_result(Call_expression* call, unsigned int index)
8702 {
8703   return new Call_result_expression(call, index);
8704 }
8705
8706 // Class Index_expression.
8707
8708 // Traversal.
8709
8710 int
8711 Index_expression::do_traverse(Traverse* traverse)
8712 {
8713   if (Expression::traverse(&this->left_, traverse) == TRAVERSE_EXIT
8714       || Expression::traverse(&this->start_, traverse) == TRAVERSE_EXIT
8715       || (this->end_ != NULL
8716           && Expression::traverse(&this->end_, traverse) == TRAVERSE_EXIT))
8717     return TRAVERSE_EXIT;
8718   return TRAVERSE_CONTINUE;
8719 }
8720
8721 // Lower an index expression.  This converts the generic index
8722 // expression into an array index, a string index, or a map index.
8723
8724 Expression*
8725 Index_expression::do_lower(Gogo*, Named_object*, int)
8726 {
8727   source_location location = this->location();
8728   Expression* left = this->left_;
8729   Expression* start = this->start_;
8730   Expression* end = this->end_;
8731
8732   Type* type = left->type();
8733   if (type->is_error_type())
8734     return Expression::make_error(location);
8735   else if (type->array_type() != NULL)
8736     return Expression::make_array_index(left, start, end, location);
8737   else if (type->points_to() != NULL
8738            && type->points_to()->array_type() != NULL
8739            && !type->points_to()->is_open_array_type())
8740     {
8741       Expression* deref = Expression::make_unary(OPERATOR_MULT, left,
8742                                                  location);
8743       return Expression::make_array_index(deref, start, end, location);
8744     }
8745   else if (type->is_string_type())
8746     return Expression::make_string_index(left, start, end, location);
8747   else if (type->map_type() != NULL)
8748     {
8749       if (end != NULL)
8750         {
8751           error_at(location, "invalid slice of map");
8752           return Expression::make_error(location);
8753         }
8754       Map_index_expression* ret= Expression::make_map_index(left, start,
8755                                                             location);
8756       if (this->is_lvalue_)
8757         ret->set_is_lvalue();
8758       return ret;
8759     }
8760   else
8761     {
8762       error_at(location,
8763                "attempt to index object which is not array, string, or map");
8764       return Expression::make_error(location);
8765     }
8766 }
8767
8768 // Make an index expression.
8769
8770 Expression*
8771 Expression::make_index(Expression* left, Expression* start, Expression* end,
8772                        source_location location)
8773 {
8774   return new Index_expression(left, start, end, location);
8775 }
8776
8777 // An array index.  This is used for both indexing and slicing.
8778
8779 class Array_index_expression : public Expression
8780 {
8781  public:
8782   Array_index_expression(Expression* array, Expression* start,
8783                          Expression* end, source_location location)
8784     : Expression(EXPRESSION_ARRAY_INDEX, location),
8785       array_(array), start_(start), end_(end), type_(NULL)
8786   { }
8787
8788  protected:
8789   int
8790   do_traverse(Traverse*);
8791
8792   Type*
8793   do_type();
8794
8795   void
8796   do_determine_type(const Type_context*);
8797
8798   void
8799   do_check_types(Gogo*);
8800
8801   Expression*
8802   do_copy()
8803   {
8804     return Expression::make_array_index(this->array_->copy(),
8805                                         this->start_->copy(),
8806                                         (this->end_ == NULL
8807                                          ? NULL
8808                                          : this->end_->copy()),
8809                                         this->location());
8810   }
8811
8812   bool
8813   do_is_addressable() const;
8814
8815   void
8816   do_address_taken(bool escapes)
8817   { this->array_->address_taken(escapes); }
8818
8819   tree
8820   do_get_tree(Translate_context*);
8821
8822  private:
8823   // The array we are getting a value from.
8824   Expression* array_;
8825   // The start or only index.
8826   Expression* start_;
8827   // The end index of a slice.  This may be NULL for a simple array
8828   // index, or it may be a nil expression for the length of the array.
8829   Expression* end_;
8830   // The type of the expression.
8831   Type* type_;
8832 };
8833
8834 // Array index traversal.
8835
8836 int
8837 Array_index_expression::do_traverse(Traverse* traverse)
8838 {
8839   if (Expression::traverse(&this->array_, traverse) == TRAVERSE_EXIT)
8840     return TRAVERSE_EXIT;
8841   if (Expression::traverse(&this->start_, traverse) == TRAVERSE_EXIT)
8842     return TRAVERSE_EXIT;
8843   if (this->end_ != NULL)
8844     {
8845       if (Expression::traverse(&this->end_, traverse) == TRAVERSE_EXIT)
8846         return TRAVERSE_EXIT;
8847     }
8848   return TRAVERSE_CONTINUE;
8849 }
8850
8851 // Return the type of an array index.
8852
8853 Type*
8854 Array_index_expression::do_type()
8855 {
8856   if (this->type_ == NULL)
8857     {
8858      Array_type* type = this->array_->type()->array_type();
8859       if (type == NULL)
8860         this->type_ = Type::make_error_type();
8861       else if (this->end_ == NULL)
8862         this->type_ = type->element_type();
8863       else if (type->is_open_array_type())
8864         {
8865           // A slice of a slice has the same type as the original
8866           // slice.
8867           this->type_ = this->array_->type()->deref();
8868         }
8869       else
8870         {
8871           // A slice of an array is a slice.
8872           this->type_ = Type::make_array_type(type->element_type(), NULL);
8873         }
8874     }
8875   return this->type_;
8876 }
8877
8878 // Set the type of an array index.
8879
8880 void
8881 Array_index_expression::do_determine_type(const Type_context*)
8882 {
8883   this->array_->determine_type_no_context();
8884   Type_context subcontext(NULL, true);
8885   this->start_->determine_type(&subcontext);
8886   if (this->end_ != NULL)
8887     this->end_->determine_type(&subcontext);
8888 }
8889
8890 // Check types of an array index.
8891
8892 void
8893 Array_index_expression::do_check_types(Gogo*)
8894 {
8895   if (this->start_->type()->integer_type() == NULL)
8896     this->report_error(_("index must be integer"));
8897   if (this->end_ != NULL
8898       && this->end_->type()->integer_type() == NULL
8899       && !this->end_->is_nil_expression())
8900     this->report_error(_("slice end must be integer"));
8901
8902   Array_type* array_type = this->array_->type()->array_type();
8903   gcc_assert(array_type != NULL);
8904
8905   unsigned int int_bits =
8906     Type::lookup_integer_type("int")->integer_type()->bits();
8907
8908   Type* dummy;
8909   mpz_t lval;
8910   mpz_init(lval);
8911   bool lval_valid = (array_type->length() != NULL
8912                      && array_type->length()->integer_constant_value(true,
8913                                                                      lval,
8914                                                                      &dummy));
8915   mpz_t ival;
8916   mpz_init(ival);
8917   if (this->start_->integer_constant_value(true, ival, &dummy))
8918     {
8919       if (mpz_sgn(ival) < 0
8920           || mpz_sizeinbase(ival, 2) >= int_bits
8921           || (lval_valid
8922               && (this->end_ == NULL
8923                   ? mpz_cmp(ival, lval) >= 0
8924                   : mpz_cmp(ival, lval) > 0)))
8925         {
8926           error_at(this->start_->location(), "array index out of bounds");
8927           this->set_is_error();
8928         }
8929     }
8930   if (this->end_ != NULL && !this->end_->is_nil_expression())
8931     {
8932       if (this->end_->integer_constant_value(true, ival, &dummy))
8933         {
8934           if (mpz_sgn(ival) < 0
8935               || mpz_sizeinbase(ival, 2) >= int_bits
8936               || (lval_valid && mpz_cmp(ival, lval) > 0))
8937             {
8938               error_at(this->end_->location(), "array index out of bounds");
8939               this->set_is_error();
8940             }
8941         }
8942     }
8943   mpz_clear(ival);
8944   mpz_clear(lval);
8945
8946   // A slice of an array requires an addressable array.  A slice of a
8947   // slice is always possible.
8948   if (this->end_ != NULL
8949       && !array_type->is_open_array_type()
8950       && !this->array_->is_addressable())
8951     this->report_error(_("array is not addressable"));
8952 }
8953
8954 // Return whether this expression is addressable.
8955
8956 bool
8957 Array_index_expression::do_is_addressable() const
8958 {
8959   // A slice expression is not addressable.
8960   if (this->end_ != NULL)
8961     return false;
8962
8963   // An index into a slice is addressable.
8964   if (this->array_->type()->is_open_array_type())
8965     return true;
8966
8967   // An index into an array is addressable if the array is
8968   // addressable.
8969   return this->array_->is_addressable();
8970 }
8971
8972 // Get a tree for an array index.
8973
8974 tree
8975 Array_index_expression::do_get_tree(Translate_context* context)
8976 {
8977   Gogo* gogo = context->gogo();
8978   source_location loc = this->location();
8979
8980   Array_type* array_type = this->array_->type()->array_type();
8981   gcc_assert(array_type != NULL);
8982
8983   tree type_tree = array_type->get_tree(gogo);
8984
8985   tree array_tree = this->array_->get_tree(context);
8986   if (array_tree == error_mark_node)
8987     return error_mark_node;
8988
8989   if (array_type->length() == NULL && !DECL_P(array_tree))
8990     array_tree = save_expr(array_tree);
8991   tree length_tree = array_type->length_tree(gogo, array_tree);
8992   length_tree = save_expr(length_tree);
8993   tree length_type = TREE_TYPE(length_tree);
8994
8995   tree bad_index = boolean_false_node;
8996
8997   tree start_tree = this->start_->get_tree(context);
8998   if (start_tree == error_mark_node)
8999     return error_mark_node;
9000   if (!DECL_P(start_tree))
9001     start_tree = save_expr(start_tree);
9002   if (!INTEGRAL_TYPE_P(TREE_TYPE(start_tree)))
9003     start_tree = convert_to_integer(length_type, start_tree);
9004
9005   bad_index = Expression::check_bounds(start_tree, length_type, bad_index,
9006                                        loc);
9007
9008   start_tree = fold_convert_loc(loc, length_type, start_tree);
9009   bad_index = fold_build2_loc(loc, TRUTH_OR_EXPR, boolean_type_node, bad_index,
9010                               fold_build2_loc(loc,
9011                                               (this->end_ == NULL
9012                                                ? GE_EXPR
9013                                                : GT_EXPR),
9014                                               boolean_type_node, start_tree,
9015                                               length_tree));
9016
9017   int code = (array_type->length() != NULL
9018               ? (this->end_ == NULL
9019                  ? RUNTIME_ERROR_ARRAY_INDEX_OUT_OF_BOUNDS
9020                  : RUNTIME_ERROR_ARRAY_SLICE_OUT_OF_BOUNDS)
9021               : (this->end_ == NULL
9022                  ? RUNTIME_ERROR_SLICE_INDEX_OUT_OF_BOUNDS
9023                  : RUNTIME_ERROR_SLICE_SLICE_OUT_OF_BOUNDS));
9024   tree crash = Gogo::runtime_error(code, loc);
9025
9026   if (this->end_ == NULL)
9027     {
9028       // Simple array indexing.  This has to return an l-value, so
9029       // wrap the index check into START_TREE.
9030       start_tree = build2(COMPOUND_EXPR, TREE_TYPE(start_tree),
9031                           build3(COND_EXPR, void_type_node,
9032                                  bad_index, crash, NULL_TREE),
9033                           start_tree);
9034       start_tree = fold_convert_loc(loc, sizetype, start_tree);
9035
9036       if (array_type->length() != NULL)
9037         {
9038           // Fixed array.
9039           return build4(ARRAY_REF, TREE_TYPE(type_tree), array_tree,
9040                         start_tree, NULL_TREE, NULL_TREE);
9041         }
9042       else
9043         {
9044           // Open array.
9045           tree values = array_type->value_pointer_tree(gogo, array_tree);
9046           tree element_type_tree = array_type->element_type()->get_tree(gogo);
9047           tree element_size = TYPE_SIZE_UNIT(element_type_tree);
9048           tree offset = fold_build2_loc(loc, MULT_EXPR, sizetype,
9049                                         start_tree, element_size);
9050           tree ptr = fold_build2_loc(loc, POINTER_PLUS_EXPR,
9051                                      TREE_TYPE(values), values, offset);
9052           return build_fold_indirect_ref(ptr);
9053         }
9054     }
9055
9056   // Array slice.
9057
9058   tree capacity_tree = array_type->capacity_tree(gogo, array_tree);
9059   capacity_tree = fold_convert_loc(loc, length_type, capacity_tree);
9060
9061   tree end_tree;
9062   if (this->end_->is_nil_expression())
9063     end_tree = length_tree;
9064   else
9065     {
9066       end_tree = this->end_->get_tree(context);
9067       if (end_tree == error_mark_node)
9068         return error_mark_node;
9069       if (!DECL_P(end_tree))
9070         end_tree = save_expr(end_tree);
9071       if (!INTEGRAL_TYPE_P(TREE_TYPE(end_tree)))
9072         end_tree = convert_to_integer(length_type, end_tree);
9073
9074       bad_index = Expression::check_bounds(end_tree, length_type, bad_index,
9075                                            loc);
9076
9077       end_tree = fold_convert_loc(loc, length_type, end_tree);
9078
9079       capacity_tree = save_expr(capacity_tree);
9080       tree bad_end = fold_build2_loc(loc, TRUTH_OR_EXPR, boolean_type_node,
9081                                      fold_build2_loc(loc, LT_EXPR,
9082                                                      boolean_type_node,
9083                                                      end_tree, start_tree),
9084                                      fold_build2_loc(loc, GT_EXPR,
9085                                                      boolean_type_node,
9086                                                      end_tree, capacity_tree));
9087       bad_index = fold_build2_loc(loc, TRUTH_OR_EXPR, boolean_type_node,
9088                                   bad_index, bad_end);
9089     }
9090
9091   tree element_type_tree = array_type->element_type()->get_tree(gogo);
9092   tree element_size = TYPE_SIZE_UNIT(element_type_tree);
9093
9094   tree offset = fold_build2_loc(loc, MULT_EXPR, sizetype,
9095                                 fold_convert_loc(loc, sizetype, start_tree),
9096                                 element_size);
9097
9098   tree value_pointer = array_type->value_pointer_tree(gogo, array_tree);
9099
9100   value_pointer = fold_build2_loc(loc, POINTER_PLUS_EXPR,
9101                                   TREE_TYPE(value_pointer),
9102                                   value_pointer, offset);
9103
9104   tree result_length_tree = fold_build2_loc(loc, MINUS_EXPR, length_type,
9105                                             end_tree, start_tree);
9106
9107   tree result_capacity_tree = fold_build2_loc(loc, MINUS_EXPR, length_type,
9108                                               capacity_tree, start_tree);
9109
9110   tree struct_tree = this->type()->get_tree(gogo);
9111   gcc_assert(TREE_CODE(struct_tree) == RECORD_TYPE);
9112
9113   VEC(constructor_elt,gc)* init = VEC_alloc(constructor_elt, gc, 3);
9114
9115   constructor_elt* elt = VEC_quick_push(constructor_elt, init, NULL);
9116   tree field = TYPE_FIELDS(struct_tree);
9117   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__values") == 0);
9118   elt->index = field;
9119   elt->value = value_pointer;
9120
9121   elt = VEC_quick_push(constructor_elt, init, NULL);
9122   field = DECL_CHAIN(field);
9123   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__count") == 0);
9124   elt->index = field;
9125   elt->value = fold_convert_loc(loc, TREE_TYPE(field), result_length_tree);
9126
9127   elt = VEC_quick_push(constructor_elt, init, NULL);
9128   field = DECL_CHAIN(field);
9129   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__capacity") == 0);
9130   elt->index = field;
9131   elt->value = fold_convert_loc(loc, TREE_TYPE(field), result_capacity_tree);
9132
9133   tree constructor = build_constructor(struct_tree, init);
9134
9135   if (TREE_CONSTANT(value_pointer)
9136       && TREE_CONSTANT(result_length_tree)
9137       && TREE_CONSTANT(result_capacity_tree))
9138     TREE_CONSTANT(constructor) = 1;
9139
9140   return fold_build2_loc(loc, COMPOUND_EXPR, TREE_TYPE(constructor),
9141                          build3(COND_EXPR, void_type_node,
9142                                 bad_index, crash, NULL_TREE),
9143                          constructor);
9144 }
9145
9146 // Make an array index expression.  END may be NULL.
9147
9148 Expression*
9149 Expression::make_array_index(Expression* array, Expression* start,
9150                              Expression* end, source_location location)
9151 {
9152   // Taking a slice of a composite literal requires moving the literal
9153   // onto the heap.
9154   if (end != NULL && array->is_composite_literal())
9155     {
9156       array = Expression::make_heap_composite(array, location);
9157       array = Expression::make_unary(OPERATOR_MULT, array, location);
9158     }
9159   return new Array_index_expression(array, start, end, location);
9160 }
9161
9162 // A string index.  This is used for both indexing and slicing.
9163
9164 class String_index_expression : public Expression
9165 {
9166  public:
9167   String_index_expression(Expression* string, Expression* start,
9168                           Expression* end, source_location location)
9169     : Expression(EXPRESSION_STRING_INDEX, location),
9170       string_(string), start_(start), end_(end)
9171   { }
9172
9173  protected:
9174   int
9175   do_traverse(Traverse*);
9176
9177   Type*
9178   do_type();
9179
9180   void
9181   do_determine_type(const Type_context*);
9182
9183   void
9184   do_check_types(Gogo*);
9185
9186   Expression*
9187   do_copy()
9188   {
9189     return Expression::make_string_index(this->string_->copy(),
9190                                          this->start_->copy(),
9191                                          (this->end_ == NULL
9192                                           ? NULL
9193                                           : this->end_->copy()),
9194                                          this->location());
9195   }
9196
9197   tree
9198   do_get_tree(Translate_context*);
9199
9200  private:
9201   // The string we are getting a value from.
9202   Expression* string_;
9203   // The start or only index.
9204   Expression* start_;
9205   // The end index of a slice.  This may be NULL for a single index,
9206   // or it may be a nil expression for the length of the string.
9207   Expression* end_;
9208 };
9209
9210 // String index traversal.
9211
9212 int
9213 String_index_expression::do_traverse(Traverse* traverse)
9214 {
9215   if (Expression::traverse(&this->string_, traverse) == TRAVERSE_EXIT)
9216     return TRAVERSE_EXIT;
9217   if (Expression::traverse(&this->start_, traverse) == TRAVERSE_EXIT)
9218     return TRAVERSE_EXIT;
9219   if (this->end_ != NULL)
9220     {
9221       if (Expression::traverse(&this->end_, traverse) == TRAVERSE_EXIT)
9222         return TRAVERSE_EXIT;
9223     }
9224   return TRAVERSE_CONTINUE;
9225 }
9226
9227 // Return the type of a string index.
9228
9229 Type*
9230 String_index_expression::do_type()
9231 {
9232   if (this->end_ == NULL)
9233     return Type::lookup_integer_type("uint8");
9234   else
9235     return Type::make_string_type();
9236 }
9237
9238 // Determine the type of a string index.
9239
9240 void
9241 String_index_expression::do_determine_type(const Type_context*)
9242 {
9243   this->string_->determine_type_no_context();
9244   Type_context subcontext(NULL, true);
9245   this->start_->determine_type(&subcontext);
9246   if (this->end_ != NULL)
9247     this->end_->determine_type(&subcontext);
9248 }
9249
9250 // Check types of a string index.
9251
9252 void
9253 String_index_expression::do_check_types(Gogo*)
9254 {
9255   if (this->start_->type()->integer_type() == NULL)
9256     this->report_error(_("index must be integer"));
9257   if (this->end_ != NULL
9258       && this->end_->type()->integer_type() == NULL
9259       && !this->end_->is_nil_expression())
9260     this->report_error(_("slice end must be integer"));
9261
9262   std::string sval;
9263   bool sval_valid = this->string_->string_constant_value(&sval);
9264
9265   mpz_t ival;
9266   mpz_init(ival);
9267   Type* dummy;
9268   if (this->start_->integer_constant_value(true, ival, &dummy))
9269     {
9270       if (mpz_sgn(ival) < 0
9271           || (sval_valid && mpz_cmp_ui(ival, sval.length()) >= 0))
9272         {
9273           error_at(this->start_->location(), "string index out of bounds");
9274           this->set_is_error();
9275         }
9276     }
9277   if (this->end_ != NULL && !this->end_->is_nil_expression())
9278     {
9279       if (this->end_->integer_constant_value(true, ival, &dummy))
9280         {
9281           if (mpz_sgn(ival) < 0
9282               || (sval_valid && mpz_cmp_ui(ival, sval.length()) > 0))
9283             {
9284               error_at(this->end_->location(), "string index out of bounds");
9285               this->set_is_error();
9286             }
9287         }
9288     }
9289   mpz_clear(ival);
9290 }
9291
9292 // Get a tree for a string index.
9293
9294 tree
9295 String_index_expression::do_get_tree(Translate_context* context)
9296 {
9297   source_location loc = this->location();
9298
9299   tree string_tree = this->string_->get_tree(context);
9300   if (string_tree == error_mark_node)
9301     return error_mark_node;
9302
9303   if (this->string_->type()->points_to() != NULL)
9304     string_tree = build_fold_indirect_ref(string_tree);
9305   if (!DECL_P(string_tree))
9306     string_tree = save_expr(string_tree);
9307   tree string_type = TREE_TYPE(string_tree);
9308
9309   tree length_tree = String_type::length_tree(context->gogo(), string_tree);
9310   length_tree = save_expr(length_tree);
9311   tree length_type = TREE_TYPE(length_tree);
9312
9313   tree bad_index = boolean_false_node;
9314
9315   tree start_tree = this->start_->get_tree(context);
9316   if (start_tree == error_mark_node)
9317     return error_mark_node;
9318   if (!DECL_P(start_tree))
9319     start_tree = save_expr(start_tree);
9320   if (!INTEGRAL_TYPE_P(TREE_TYPE(start_tree)))
9321     start_tree = convert_to_integer(length_type, start_tree);
9322
9323   bad_index = Expression::check_bounds(start_tree, length_type, bad_index,
9324                                        loc);
9325
9326   start_tree = fold_convert_loc(loc, length_type, start_tree);
9327
9328   int code = (this->end_ == NULL
9329               ? RUNTIME_ERROR_STRING_INDEX_OUT_OF_BOUNDS
9330               : RUNTIME_ERROR_STRING_SLICE_OUT_OF_BOUNDS);
9331   tree crash = Gogo::runtime_error(code, loc);
9332
9333   if (this->end_ == NULL)
9334     {
9335       bad_index = fold_build2_loc(loc, TRUTH_OR_EXPR, boolean_type_node,
9336                                   bad_index,
9337                                   fold_build2_loc(loc, GE_EXPR,
9338                                                   boolean_type_node,
9339                                                   start_tree, length_tree));
9340
9341       tree bytes_tree = String_type::bytes_tree(context->gogo(), string_tree);
9342       tree ptr = fold_build2_loc(loc, POINTER_PLUS_EXPR, TREE_TYPE(bytes_tree),
9343                                  bytes_tree,
9344                                  fold_convert_loc(loc, sizetype, start_tree));
9345       tree index = build_fold_indirect_ref_loc(loc, ptr);
9346
9347       return build2(COMPOUND_EXPR, TREE_TYPE(index),
9348                     build3(COND_EXPR, void_type_node,
9349                            bad_index, crash, NULL_TREE),
9350                     index);
9351     }
9352   else
9353     {
9354       tree end_tree;
9355       if (this->end_->is_nil_expression())
9356         end_tree = build_int_cst(length_type, -1);
9357       else
9358         {
9359           end_tree = this->end_->get_tree(context);
9360           if (end_tree == error_mark_node)
9361             return error_mark_node;
9362           if (!DECL_P(end_tree))
9363             end_tree = save_expr(end_tree);
9364           if (!INTEGRAL_TYPE_P(TREE_TYPE(end_tree)))
9365             end_tree = convert_to_integer(length_type, end_tree);
9366
9367           bad_index = Expression::check_bounds(end_tree, length_type,
9368                                                bad_index, loc);
9369
9370           end_tree = fold_convert_loc(loc, length_type, end_tree);
9371         }
9372
9373       static tree strslice_fndecl;
9374       tree ret = Gogo::call_builtin(&strslice_fndecl,
9375                                     loc,
9376                                     "__go_string_slice",
9377                                     3,
9378                                     string_type,
9379                                     string_type,
9380                                     string_tree,
9381                                     length_type,
9382                                     start_tree,
9383                                     length_type,
9384                                     end_tree);
9385       // This will panic if the bounds are out of range for the
9386       // string.
9387       TREE_NOTHROW(strslice_fndecl) = 0;
9388
9389       if (bad_index == boolean_false_node)
9390         return ret;
9391       else
9392         return build2(COMPOUND_EXPR, TREE_TYPE(ret),
9393                       build3(COND_EXPR, void_type_node,
9394                              bad_index, crash, NULL_TREE),
9395                       ret);
9396     }
9397 }
9398
9399 // Make a string index expression.  END may be NULL.
9400
9401 Expression*
9402 Expression::make_string_index(Expression* string, Expression* start,
9403                               Expression* end, source_location location)
9404 {
9405   return new String_index_expression(string, start, end, location);
9406 }
9407
9408 // Class Map_index.
9409
9410 // Get the type of the map.
9411
9412 Map_type*
9413 Map_index_expression::get_map_type() const
9414 {
9415   Map_type* mt = this->map_->type()->deref()->map_type();
9416   gcc_assert(mt != NULL);
9417   return mt;
9418 }
9419
9420 // Map index traversal.
9421
9422 int
9423 Map_index_expression::do_traverse(Traverse* traverse)
9424 {
9425   if (Expression::traverse(&this->map_, traverse) == TRAVERSE_EXIT)
9426     return TRAVERSE_EXIT;
9427   return Expression::traverse(&this->index_, traverse);
9428 }
9429
9430 // Return the type of a map index.
9431
9432 Type*
9433 Map_index_expression::do_type()
9434 {
9435   Type* type = this->get_map_type()->val_type();
9436   // If this map index is in a tuple assignment, we actually return a
9437   // pointer to the value type.  Tuple_map_assignment_statement is
9438   // responsible for handling this correctly.  We need to get the type
9439   // right in case this gets assigned to a temporary variable.
9440   if (this->is_in_tuple_assignment_)
9441     type = Type::make_pointer_type(type);
9442   return type;
9443 }
9444
9445 // Fix the type of a map index.
9446
9447 void
9448 Map_index_expression::do_determine_type(const Type_context*)
9449 {
9450   this->map_->determine_type_no_context();
9451   Type_context subcontext(this->get_map_type()->key_type(), false);
9452   this->index_->determine_type(&subcontext);
9453 }
9454
9455 // Check types of a map index.
9456
9457 void
9458 Map_index_expression::do_check_types(Gogo*)
9459 {
9460   std::string reason;
9461   if (!Type::are_assignable(this->get_map_type()->key_type(),
9462                             this->index_->type(), &reason))
9463     {
9464       if (reason.empty())
9465         this->report_error(_("incompatible type for map index"));
9466       else
9467         {
9468           error_at(this->location(), "incompatible type for map index (%s)",
9469                    reason.c_str());
9470           this->set_is_error();
9471         }
9472     }
9473 }
9474
9475 // Get a tree for a map index.
9476
9477 tree
9478 Map_index_expression::do_get_tree(Translate_context* context)
9479 {
9480   Map_type* type = this->get_map_type();
9481
9482   tree valptr = this->get_value_pointer(context, this->is_lvalue_);
9483   if (valptr == error_mark_node)
9484     return error_mark_node;
9485   valptr = save_expr(valptr);
9486
9487   tree val_type_tree = TREE_TYPE(TREE_TYPE(valptr));
9488
9489   if (this->is_lvalue_)
9490     return build_fold_indirect_ref(valptr);
9491   else if (this->is_in_tuple_assignment_)
9492     {
9493       // Tuple_map_assignment_statement is responsible for using this
9494       // appropriately.
9495       return valptr;
9496     }
9497   else
9498     {
9499       return fold_build3(COND_EXPR, val_type_tree,
9500                          fold_build2(EQ_EXPR, boolean_type_node, valptr,
9501                                      fold_convert(TREE_TYPE(valptr),
9502                                                   null_pointer_node)),
9503                          type->val_type()->get_init_tree(context->gogo(),
9504                                                          false),
9505                          build_fold_indirect_ref(valptr));
9506     }
9507 }
9508
9509 // Get a tree for the map index.  This returns a tree which evaluates
9510 // to a pointer to a value.  The pointer will be NULL if the key is
9511 // not in the map.
9512
9513 tree
9514 Map_index_expression::get_value_pointer(Translate_context* context,
9515                                         bool insert)
9516 {
9517   Map_type* type = this->get_map_type();
9518
9519   tree map_tree = this->map_->get_tree(context);
9520   tree index_tree = this->index_->get_tree(context);
9521   index_tree = Expression::convert_for_assignment(context, type->key_type(),
9522                                                   this->index_->type(),
9523                                                   index_tree,
9524                                                   this->location());
9525   if (map_tree == error_mark_node || index_tree == error_mark_node)
9526     return error_mark_node;
9527
9528   if (this->map_->type()->points_to() != NULL)
9529     map_tree = build_fold_indirect_ref(map_tree);
9530
9531   // We need to pass in a pointer to the key, so stuff it into a
9532   // variable.
9533   tree tmp = create_tmp_var(TREE_TYPE(index_tree), get_name(index_tree));
9534   DECL_IGNORED_P(tmp) = 0;
9535   DECL_INITIAL(tmp) = index_tree;
9536   tree make_tmp = build1(DECL_EXPR, void_type_node, tmp);
9537   tree tmpref = fold_convert(const_ptr_type_node, build_fold_addr_expr(tmp));
9538   TREE_ADDRESSABLE(tmp) = 1;
9539
9540   static tree map_index_fndecl;
9541   tree call = Gogo::call_builtin(&map_index_fndecl,
9542                                  this->location(),
9543                                  "__go_map_index",
9544                                  3,
9545                                  const_ptr_type_node,
9546                                  TREE_TYPE(map_tree),
9547                                  map_tree,
9548                                  const_ptr_type_node,
9549                                  tmpref,
9550                                  boolean_type_node,
9551                                  (insert
9552                                   ? boolean_true_node
9553                                   : boolean_false_node));
9554   // This can panic on a map of interface type if the interface holds
9555   // an uncomparable or unhashable type.
9556   TREE_NOTHROW(map_index_fndecl) = 0;
9557
9558   tree val_type_tree = type->val_type()->get_tree(context->gogo());
9559   if (val_type_tree == error_mark_node)
9560     return error_mark_node;
9561   tree ptr_val_type_tree = build_pointer_type(val_type_tree);
9562
9563   return build2(COMPOUND_EXPR, ptr_val_type_tree,
9564                 make_tmp,
9565                 fold_convert(ptr_val_type_tree, call));
9566 }
9567
9568 // Make a map index expression.
9569
9570 Map_index_expression*
9571 Expression::make_map_index(Expression* map, Expression* index,
9572                            source_location location)
9573 {
9574   return new Map_index_expression(map, index, location);
9575 }
9576
9577 // Class Field_reference_expression.
9578
9579 // Return the type of a field reference.
9580
9581 Type*
9582 Field_reference_expression::do_type()
9583 {
9584   Struct_type* struct_type = this->expr_->type()->struct_type();
9585   gcc_assert(struct_type != NULL);
9586   return struct_type->field(this->field_index_)->type();
9587 }
9588
9589 // Check the types for a field reference.
9590
9591 void
9592 Field_reference_expression::do_check_types(Gogo*)
9593 {
9594   Struct_type* struct_type = this->expr_->type()->struct_type();
9595   gcc_assert(struct_type != NULL);
9596   gcc_assert(struct_type->field(this->field_index_) != NULL);
9597 }
9598
9599 // Get a tree for a field reference.
9600
9601 tree
9602 Field_reference_expression::do_get_tree(Translate_context* context)
9603 {
9604   tree struct_tree = this->expr_->get_tree(context);
9605   if (struct_tree == error_mark_node
9606       || TREE_TYPE(struct_tree) == error_mark_node)
9607     return error_mark_node;
9608   gcc_assert(TREE_CODE(TREE_TYPE(struct_tree)) == RECORD_TYPE);
9609   tree field = TYPE_FIELDS(TREE_TYPE(struct_tree));
9610   gcc_assert(field != NULL_TREE);
9611   for (unsigned int i = this->field_index_; i > 0; --i)
9612     {
9613       field = DECL_CHAIN(field);
9614       gcc_assert(field != NULL_TREE);
9615     }
9616   return build3(COMPONENT_REF, TREE_TYPE(field), struct_tree, field,
9617                 NULL_TREE);
9618 }
9619
9620 // Make a reference to a qualified identifier in an expression.
9621
9622 Field_reference_expression*
9623 Expression::make_field_reference(Expression* expr, unsigned int field_index,
9624                                  source_location location)
9625 {
9626   return new Field_reference_expression(expr, field_index, location);
9627 }
9628
9629 // Class Interface_field_reference_expression.
9630
9631 // Return a tree for the pointer to the function to call.
9632
9633 tree
9634 Interface_field_reference_expression::get_function_tree(Translate_context*,
9635                                                         tree expr)
9636 {
9637   if (this->expr_->type()->points_to() != NULL)
9638     expr = build_fold_indirect_ref(expr);
9639
9640   tree expr_type = TREE_TYPE(expr);
9641   gcc_assert(TREE_CODE(expr_type) == RECORD_TYPE);
9642
9643   tree field = TYPE_FIELDS(expr_type);
9644   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__methods") == 0);
9645
9646   tree table = build3(COMPONENT_REF, TREE_TYPE(field), expr, field, NULL_TREE);
9647   gcc_assert(POINTER_TYPE_P(TREE_TYPE(table)));
9648
9649   table = build_fold_indirect_ref(table);
9650   gcc_assert(TREE_CODE(TREE_TYPE(table)) == RECORD_TYPE);
9651
9652   std::string name = Gogo::unpack_hidden_name(this->name_);
9653   for (field = DECL_CHAIN(TYPE_FIELDS(TREE_TYPE(table)));
9654        field != NULL_TREE;
9655        field = DECL_CHAIN(field))
9656     {
9657       if (name == IDENTIFIER_POINTER(DECL_NAME(field)))
9658         break;
9659     }
9660   gcc_assert(field != NULL_TREE);
9661
9662   return build3(COMPONENT_REF, TREE_TYPE(field), table, field, NULL_TREE);
9663 }
9664
9665 // Return a tree for the first argument to pass to the interface
9666 // function.
9667
9668 tree
9669 Interface_field_reference_expression::get_underlying_object_tree(
9670     Translate_context*,
9671     tree expr)
9672 {
9673   if (this->expr_->type()->points_to() != NULL)
9674     expr = build_fold_indirect_ref(expr);
9675
9676   tree expr_type = TREE_TYPE(expr);
9677   gcc_assert(TREE_CODE(expr_type) == RECORD_TYPE);
9678
9679   tree field = DECL_CHAIN(TYPE_FIELDS(expr_type));
9680   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__object") == 0);
9681
9682   return build3(COMPONENT_REF, TREE_TYPE(field), expr, field, NULL_TREE);
9683 }
9684
9685 // Traversal.
9686
9687 int
9688 Interface_field_reference_expression::do_traverse(Traverse* traverse)
9689 {
9690   return Expression::traverse(&this->expr_, traverse);
9691 }
9692
9693 // Return the type of an interface field reference.
9694
9695 Type*
9696 Interface_field_reference_expression::do_type()
9697 {
9698   Type* expr_type = this->expr_->type();
9699
9700   Type* points_to = expr_type->points_to();
9701   if (points_to != NULL)
9702     expr_type = points_to;
9703
9704   Interface_type* interface_type = expr_type->interface_type();
9705   if (interface_type == NULL)
9706     return Type::make_error_type();
9707
9708   const Typed_identifier* method = interface_type->find_method(this->name_);
9709   if (method == NULL)
9710     return Type::make_error_type();
9711
9712   return method->type();
9713 }
9714
9715 // Determine types.
9716
9717 void
9718 Interface_field_reference_expression::do_determine_type(const Type_context*)
9719 {
9720   this->expr_->determine_type_no_context();
9721 }
9722
9723 // Check the types for an interface field reference.
9724
9725 void
9726 Interface_field_reference_expression::do_check_types(Gogo*)
9727 {
9728   Type* type = this->expr_->type();
9729
9730   Type* points_to = type->points_to();
9731   if (points_to != NULL)
9732     type = points_to;
9733
9734   Interface_type* interface_type = type->interface_type();
9735   if (interface_type == NULL)
9736     this->report_error(_("expected interface or pointer to interface"));
9737   else
9738     {
9739       const Typed_identifier* method =
9740         interface_type->find_method(this->name_);
9741       if (method == NULL)
9742         {
9743           error_at(this->location(), "method %qs not in interface",
9744                    Gogo::message_name(this->name_).c_str());
9745           this->set_is_error();
9746         }
9747     }
9748 }
9749
9750 // Get a tree for a reference to a field in an interface.  There is no
9751 // standard tree type representation for this: it's a function
9752 // attached to its first argument, like a Bound_method_expression.
9753 // The only places it may currently be used are in a Call_expression
9754 // or a Go_statement, which will take it apart directly.  So this has
9755 // nothing to do at present.
9756
9757 tree
9758 Interface_field_reference_expression::do_get_tree(Translate_context*)
9759 {
9760   gcc_unreachable();
9761 }
9762
9763 // Make a reference to a field in an interface.
9764
9765 Expression*
9766 Expression::make_interface_field_reference(Expression* expr,
9767                                            const std::string& field,
9768                                            source_location location)
9769 {
9770   return new Interface_field_reference_expression(expr, field, location);
9771 }
9772
9773 // A general selector.  This is a Parser_expression for LEFT.NAME.  It
9774 // is lowered after we know the type of the left hand side.
9775
9776 class Selector_expression : public Parser_expression
9777 {
9778  public:
9779   Selector_expression(Expression* left, const std::string& name,
9780                       source_location location)
9781     : Parser_expression(EXPRESSION_SELECTOR, location),
9782       left_(left), name_(name)
9783   { }
9784
9785  protected:
9786   int
9787   do_traverse(Traverse* traverse)
9788   { return Expression::traverse(&this->left_, traverse); }
9789
9790   Expression*
9791   do_lower(Gogo*, Named_object*, int);
9792
9793   Expression*
9794   do_copy()
9795   {
9796     return new Selector_expression(this->left_->copy(), this->name_,
9797                                    this->location());
9798   }
9799
9800  private:
9801   Expression*
9802   lower_method_expression(Gogo*);
9803
9804   // The expression on the left hand side.
9805   Expression* left_;
9806   // The name on the right hand side.
9807   std::string name_;
9808 };
9809
9810 // Lower a selector expression once we know the real type of the left
9811 // hand side.
9812
9813 Expression*
9814 Selector_expression::do_lower(Gogo* gogo, Named_object*, int)
9815 {
9816   Expression* left = this->left_;
9817   if (left->is_type_expression())
9818     return this->lower_method_expression(gogo);
9819   return Type::bind_field_or_method(gogo, left->type(), left, this->name_,
9820                                     this->location());
9821 }
9822
9823 // Lower a method expression T.M or (*T).M.  We turn this into a
9824 // function literal.
9825
9826 Expression*
9827 Selector_expression::lower_method_expression(Gogo* gogo)
9828 {
9829   source_location location = this->location();
9830   Type* type = this->left_->type();
9831   const std::string& name(this->name_);
9832
9833   bool is_pointer;
9834   if (type->points_to() == NULL)
9835     is_pointer = false;
9836   else
9837     {
9838       is_pointer = true;
9839       type = type->points_to();
9840     }
9841   Named_type* nt = type->named_type();
9842   if (nt == NULL)
9843     {
9844       error_at(location,
9845                ("method expression requires named type or "
9846                 "pointer to named type"));
9847       return Expression::make_error(location);
9848     }
9849
9850   bool is_ambiguous;
9851   Method* method = nt->method_function(name, &is_ambiguous);
9852   if (method == NULL)
9853     {
9854       if (!is_ambiguous)
9855         error_at(location, "type %<%s%> has no method %<%s%>",
9856                  nt->message_name().c_str(),
9857                  Gogo::message_name(name).c_str());
9858       else
9859         error_at(location, "method %<%s%> is ambiguous in type %<%s%>",
9860                  Gogo::message_name(name).c_str(),
9861                  nt->message_name().c_str());
9862       return Expression::make_error(location);
9863     }
9864
9865   if (!is_pointer && !method->is_value_method())
9866     {
9867       error_at(location, "method requires pointer (use %<(*%s).%s)%>",
9868                nt->message_name().c_str(),
9869                Gogo::message_name(name).c_str());
9870       return Expression::make_error(location);
9871     }
9872
9873   // Build a new function type in which the receiver becomes the first
9874   // argument.
9875   Function_type* method_type = method->type();
9876   gcc_assert(method_type->is_method());
9877
9878   const char* const receiver_name = "$this";
9879   Typed_identifier_list* parameters = new Typed_identifier_list();
9880   parameters->push_back(Typed_identifier(receiver_name, this->left_->type(),
9881                                          location));
9882
9883   const Typed_identifier_list* method_parameters = method_type->parameters();
9884   if (method_parameters != NULL)
9885     {
9886       for (Typed_identifier_list::const_iterator p = method_parameters->begin();
9887            p != method_parameters->end();
9888            ++p)
9889         parameters->push_back(*p);
9890     }
9891
9892   const Typed_identifier_list* method_results = method_type->results();
9893   Typed_identifier_list* results;
9894   if (method_results == NULL)
9895     results = NULL;
9896   else
9897     {
9898       results = new Typed_identifier_list();
9899       for (Typed_identifier_list::const_iterator p = method_results->begin();
9900            p != method_results->end();
9901            ++p)
9902         results->push_back(*p);
9903     }
9904
9905   Function_type* fntype = Type::make_function_type(NULL, parameters, results,
9906                                                    location);
9907   if (method_type->is_varargs())
9908     fntype->set_is_varargs();
9909
9910   // We generate methods which always takes a pointer to the receiver
9911   // as their first argument.  If this is for a pointer type, we can
9912   // simply reuse the existing function.  We use an internal hack to
9913   // get the right type.
9914
9915   if (is_pointer)
9916     {
9917       Named_object* mno = (method->needs_stub_method()
9918                            ? method->stub_object()
9919                            : method->named_object());
9920       Expression* f = Expression::make_func_reference(mno, NULL, location);
9921       f = Expression::make_cast(fntype, f, location);
9922       Type_conversion_expression* tce =
9923         static_cast<Type_conversion_expression*>(f);
9924       tce->set_may_convert_function_types();
9925       return f;
9926     }
9927
9928   Named_object* no = gogo->start_function(Gogo::thunk_name(), fntype, false,
9929                                           location);
9930
9931   Named_object* vno = gogo->lookup(receiver_name, NULL);
9932   gcc_assert(vno != NULL);
9933   Expression* ve = Expression::make_var_reference(vno, location);
9934   Expression* bm = Type::bind_field_or_method(gogo, nt, ve, name, location);
9935   gcc_assert(bm != NULL && !bm->is_error_expression());
9936
9937   Expression_list* args;
9938   if (method_parameters == NULL)
9939     args = NULL;
9940   else
9941     {
9942       args = new Expression_list();
9943       for (Typed_identifier_list::const_iterator p = method_parameters->begin();
9944            p != method_parameters->end();
9945            ++p)
9946         {
9947           vno = gogo->lookup(p->name(), NULL);
9948           gcc_assert(vno != NULL);
9949           args->push_back(Expression::make_var_reference(vno, location));
9950         }
9951     }
9952
9953   Call_expression* call = Expression::make_call(bm, args,
9954                                                 method_type->is_varargs(),
9955                                                 location);
9956
9957   size_t count = call->result_count();
9958   Statement* s;
9959   if (count == 0)
9960     s = Statement::make_statement(call);
9961   else
9962     {
9963       Expression_list* retvals = new Expression_list();
9964       if (count <= 1)
9965         retvals->push_back(call);
9966       else
9967         {
9968           for (size_t i = 0; i < count; ++i)
9969             retvals->push_back(Expression::make_call_result(call, i));
9970         }
9971       s = Statement::make_return_statement(no->func_value()->type()->results(),
9972                                            retvals, location);
9973     }
9974   gogo->add_statement(s);
9975
9976   gogo->finish_function(location);
9977
9978   return Expression::make_func_reference(no, NULL, location);
9979 }
9980
9981 // Make a selector expression.
9982
9983 Expression*
9984 Expression::make_selector(Expression* left, const std::string& name,
9985                           source_location location)
9986 {
9987   return new Selector_expression(left, name, location);
9988 }
9989
9990 // Implement the builtin function new.
9991
9992 class Allocation_expression : public Expression
9993 {
9994  public:
9995   Allocation_expression(Type* type, source_location location)
9996     : Expression(EXPRESSION_ALLOCATION, location),
9997       type_(type)
9998   { }
9999
10000  protected:
10001   int
10002   do_traverse(Traverse* traverse)
10003   { return Type::traverse(this->type_, traverse); }
10004
10005   Type*
10006   do_type()
10007   { return Type::make_pointer_type(this->type_); }
10008
10009   void
10010   do_determine_type(const Type_context*)
10011   { }
10012
10013   void
10014   do_check_types(Gogo*);
10015
10016   Expression*
10017   do_copy()
10018   { return new Allocation_expression(this->type_, this->location()); }
10019
10020   tree
10021   do_get_tree(Translate_context*);
10022
10023  private:
10024   // The type we are allocating.
10025   Type* type_;
10026 };
10027
10028 // Check the type of an allocation expression.
10029
10030 void
10031 Allocation_expression::do_check_types(Gogo*)
10032 {
10033   if (this->type_->function_type() != NULL)
10034     this->report_error(_("invalid new of function type"));
10035 }
10036
10037 // Return a tree for an allocation expression.
10038
10039 tree
10040 Allocation_expression::do_get_tree(Translate_context* context)
10041 {
10042   tree type_tree = this->type_->get_tree(context->gogo());
10043   tree size_tree = TYPE_SIZE_UNIT(type_tree);
10044   tree space = context->gogo()->allocate_memory(this->type_, size_tree,
10045                                                 this->location());
10046   return fold_convert(build_pointer_type(type_tree), space);
10047 }
10048
10049 // Make an allocation expression.
10050
10051 Expression*
10052 Expression::make_allocation(Type* type, source_location location)
10053 {
10054   return new Allocation_expression(type, location);
10055 }
10056
10057 // Implement the builtin function make.
10058
10059 class Make_expression : public Expression
10060 {
10061  public:
10062   Make_expression(Type* type, Expression_list* args, source_location location)
10063     : Expression(EXPRESSION_MAKE, location),
10064       type_(type), args_(args)
10065   { }
10066
10067  protected:
10068   int
10069   do_traverse(Traverse* traverse);
10070
10071   Type*
10072   do_type()
10073   { return this->type_; }
10074
10075   void
10076   do_determine_type(const Type_context*);
10077
10078   void
10079   do_check_types(Gogo*);
10080
10081   Expression*
10082   do_copy()
10083   {
10084     return new Make_expression(this->type_, this->args_->copy(),
10085                                this->location());
10086   }
10087
10088   tree
10089   do_get_tree(Translate_context*);
10090
10091  private:
10092   // The type we are making.
10093   Type* type_;
10094   // The arguments to pass to the make routine.
10095   Expression_list* args_;
10096 };
10097
10098 // Traversal.
10099
10100 int
10101 Make_expression::do_traverse(Traverse* traverse)
10102 {
10103   if (this->args_ != NULL
10104       && this->args_->traverse(traverse) == TRAVERSE_EXIT)
10105     return TRAVERSE_EXIT;
10106   if (Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
10107     return TRAVERSE_EXIT;
10108   return TRAVERSE_CONTINUE;
10109 }
10110
10111 // Set types of arguments.
10112
10113 void
10114 Make_expression::do_determine_type(const Type_context*)
10115 {
10116   if (this->args_ != NULL)
10117     {
10118       Type_context context(Type::lookup_integer_type("int"), false);
10119       for (Expression_list::const_iterator pe = this->args_->begin();
10120            pe != this->args_->end();
10121            ++pe)
10122         (*pe)->determine_type(&context);
10123     }
10124 }
10125
10126 // Check types for a make expression.
10127
10128 void
10129 Make_expression::do_check_types(Gogo*)
10130 {
10131   if (this->type_->channel_type() == NULL
10132       && this->type_->map_type() == NULL
10133       && (this->type_->array_type() == NULL
10134           || this->type_->array_type()->length() != NULL))
10135     this->report_error(_("invalid type for make function"));
10136   else if (!this->type_->check_make_expression(this->args_, this->location()))
10137     this->set_is_error();
10138 }
10139
10140 // Return a tree for a make expression.
10141
10142 tree
10143 Make_expression::do_get_tree(Translate_context* context)
10144 {
10145   return this->type_->make_expression_tree(context, this->args_,
10146                                            this->location());
10147 }
10148
10149 // Make a make expression.
10150
10151 Expression*
10152 Expression::make_make(Type* type, Expression_list* args,
10153                       source_location location)
10154 {
10155   return new Make_expression(type, args, location);
10156 }
10157
10158 // Construct a struct.
10159
10160 class Struct_construction_expression : public Expression
10161 {
10162  public:
10163   Struct_construction_expression(Type* type, Expression_list* vals,
10164                                  source_location location)
10165     : Expression(EXPRESSION_STRUCT_CONSTRUCTION, location),
10166       type_(type), vals_(vals)
10167   { }
10168
10169   // Return whether this is a constant initializer.
10170   bool
10171   is_constant_struct() const;
10172
10173  protected:
10174   int
10175   do_traverse(Traverse* traverse);
10176
10177   Type*
10178   do_type()
10179   { return this->type_; }
10180
10181   void
10182   do_determine_type(const Type_context*);
10183
10184   void
10185   do_check_types(Gogo*);
10186
10187   Expression*
10188   do_copy()
10189   {
10190     return new Struct_construction_expression(this->type_, this->vals_->copy(),
10191                                               this->location());
10192   }
10193
10194   bool
10195   do_is_addressable() const
10196   { return true; }
10197
10198   tree
10199   do_get_tree(Translate_context*);
10200
10201   void
10202   do_export(Export*) const;
10203
10204  private:
10205   // The type of the struct to construct.
10206   Type* type_;
10207   // The list of values, in order of the fields in the struct.  A NULL
10208   // entry means that the field should be zero-initialized.
10209   Expression_list* vals_;
10210 };
10211
10212 // Traversal.
10213
10214 int
10215 Struct_construction_expression::do_traverse(Traverse* traverse)
10216 {
10217   if (this->vals_ != NULL
10218       && this->vals_->traverse(traverse) == TRAVERSE_EXIT)
10219     return TRAVERSE_EXIT;
10220   if (Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
10221     return TRAVERSE_EXIT;
10222   return TRAVERSE_CONTINUE;
10223 }
10224
10225 // Return whether this is a constant initializer.
10226
10227 bool
10228 Struct_construction_expression::is_constant_struct() const
10229 {
10230   if (this->vals_ == NULL)
10231     return true;
10232   for (Expression_list::const_iterator pv = this->vals_->begin();
10233        pv != this->vals_->end();
10234        ++pv)
10235     {
10236       if (*pv != NULL
10237           && !(*pv)->is_constant()
10238           && (!(*pv)->is_composite_literal()
10239               || (*pv)->is_nonconstant_composite_literal()))
10240         return false;
10241     }
10242
10243   const Struct_field_list* fields = this->type_->struct_type()->fields();
10244   for (Struct_field_list::const_iterator pf = fields->begin();
10245        pf != fields->end();
10246        ++pf)
10247     {
10248       // There are no constant constructors for interfaces.
10249       if (pf->type()->interface_type() != NULL)
10250         return false;
10251     }
10252
10253   return true;
10254 }
10255
10256 // Final type determination.
10257
10258 void
10259 Struct_construction_expression::do_determine_type(const Type_context*)
10260 {
10261   if (this->vals_ == NULL)
10262     return;
10263   const Struct_field_list* fields = this->type_->struct_type()->fields();
10264   Expression_list::const_iterator pv = this->vals_->begin();
10265   for (Struct_field_list::const_iterator pf = fields->begin();
10266        pf != fields->end();
10267        ++pf, ++pv)
10268     {
10269       if (pv == this->vals_->end())
10270         return;
10271       if (*pv != NULL)
10272         {
10273           Type_context subcontext(pf->type(), false);
10274           (*pv)->determine_type(&subcontext);
10275         }
10276     }
10277 }
10278
10279 // Check types.
10280
10281 void
10282 Struct_construction_expression::do_check_types(Gogo*)
10283 {
10284   if (this->vals_ == NULL)
10285     return;
10286
10287   Struct_type* st = this->type_->struct_type();
10288   if (this->vals_->size() > st->field_count())
10289     {
10290       this->report_error(_("too many expressions for struct"));
10291       return;
10292     }
10293
10294   const Struct_field_list* fields = st->fields();
10295   Expression_list::const_iterator pv = this->vals_->begin();
10296   int i = 0;
10297   for (Struct_field_list::const_iterator pf = fields->begin();
10298        pf != fields->end();
10299        ++pf, ++pv, ++i)
10300     {
10301       if (pv == this->vals_->end())
10302         {
10303           this->report_error(_("too few expressions for struct"));
10304           break;
10305         }
10306
10307       if (*pv == NULL)
10308         continue;
10309
10310       std::string reason;
10311       if (!Type::are_assignable(pf->type(), (*pv)->type(), &reason))
10312         {
10313           if (reason.empty())
10314             error_at((*pv)->location(),
10315                      "incompatible type for field %d in struct construction",
10316                      i + 1);
10317           else
10318             error_at((*pv)->location(),
10319                      ("incompatible type for field %d in "
10320                       "struct construction (%s)"),
10321                      i + 1, reason.c_str());
10322           this->set_is_error();
10323         }
10324     }
10325   gcc_assert(pv == this->vals_->end());
10326 }
10327
10328 // Return a tree for constructing a struct.
10329
10330 tree
10331 Struct_construction_expression::do_get_tree(Translate_context* context)
10332 {
10333   Gogo* gogo = context->gogo();
10334
10335   if (this->vals_ == NULL)
10336     return this->type_->get_init_tree(gogo, false);
10337
10338   tree type_tree = this->type_->get_tree(gogo);
10339   if (type_tree == error_mark_node)
10340     return error_mark_node;
10341   gcc_assert(TREE_CODE(type_tree) == RECORD_TYPE);
10342
10343   bool is_constant = true;
10344   const Struct_field_list* fields = this->type_->struct_type()->fields();
10345   VEC(constructor_elt,gc)* elts = VEC_alloc(constructor_elt, gc,
10346                                             fields->size());
10347   Struct_field_list::const_iterator pf = fields->begin();
10348   Expression_list::const_iterator pv = this->vals_->begin();
10349   for (tree field = TYPE_FIELDS(type_tree);
10350        field != NULL_TREE;
10351        field = DECL_CHAIN(field), ++pf)
10352     {
10353       gcc_assert(pf != fields->end());
10354
10355       tree val;
10356       if (pv == this->vals_->end())
10357         val = pf->type()->get_init_tree(gogo, false);
10358       else if (*pv == NULL)
10359         {
10360           val = pf->type()->get_init_tree(gogo, false);
10361           ++pv;
10362         }
10363       else
10364         {
10365           val = Expression::convert_for_assignment(context, pf->type(),
10366                                                    (*pv)->type(),
10367                                                    (*pv)->get_tree(context),
10368                                                    this->location());
10369           ++pv;
10370         }
10371
10372       if (val == error_mark_node || TREE_TYPE(val) == error_mark_node)
10373         return error_mark_node;
10374
10375       constructor_elt* elt = VEC_quick_push(constructor_elt, elts, NULL);
10376       elt->index = field;
10377       elt->value = val;
10378       if (!TREE_CONSTANT(val))
10379         is_constant = false;
10380     }
10381   gcc_assert(pf == fields->end());
10382
10383   tree ret = build_constructor(type_tree, elts);
10384   if (is_constant)
10385     TREE_CONSTANT(ret) = 1;
10386   return ret;
10387 }
10388
10389 // Export a struct construction.
10390
10391 void
10392 Struct_construction_expression::do_export(Export* exp) const
10393 {
10394   exp->write_c_string("convert(");
10395   exp->write_type(this->type_);
10396   for (Expression_list::const_iterator pv = this->vals_->begin();
10397        pv != this->vals_->end();
10398        ++pv)
10399     {
10400       exp->write_c_string(", ");
10401       if (*pv != NULL)
10402         (*pv)->export_expression(exp);
10403     }
10404   exp->write_c_string(")");
10405 }
10406
10407 // Make a struct composite literal.  This used by the thunk code.
10408
10409 Expression*
10410 Expression::make_struct_composite_literal(Type* type, Expression_list* vals,
10411                                           source_location location)
10412 {
10413   gcc_assert(type->struct_type() != NULL);
10414   return new Struct_construction_expression(type, vals, location);
10415 }
10416
10417 // Construct an array.  This class is not used directly; instead we
10418 // use the child classes, Fixed_array_construction_expression and
10419 // Open_array_construction_expression.
10420
10421 class Array_construction_expression : public Expression
10422 {
10423  protected:
10424   Array_construction_expression(Expression_classification classification,
10425                                 Type* type, Expression_list* vals,
10426                                 source_location location)
10427     : Expression(classification, location),
10428       type_(type), vals_(vals)
10429   { }
10430
10431  public:
10432   // Return whether this is a constant initializer.
10433   bool
10434   is_constant_array() const;
10435
10436   // Return the number of elements.
10437   size_t
10438   element_count() const
10439   { return this->vals_ == NULL ? 0 : this->vals_->size(); }
10440
10441 protected:
10442   int
10443   do_traverse(Traverse* traverse);
10444
10445   Type*
10446   do_type()
10447   { return this->type_; }
10448
10449   void
10450   do_determine_type(const Type_context*);
10451
10452   void
10453   do_check_types(Gogo*);
10454
10455   bool
10456   do_is_addressable() const
10457   { return true; }
10458
10459   void
10460   do_export(Export*) const;
10461
10462   // The list of values.
10463   Expression_list*
10464   vals()
10465   { return this->vals_; }
10466
10467   // Get a constructor tree for the array values.
10468   tree
10469   get_constructor_tree(Translate_context* context, tree type_tree);
10470
10471  private:
10472   // The type of the array to construct.
10473   Type* type_;
10474   // The list of values.
10475   Expression_list* vals_;
10476 };
10477
10478 // Traversal.
10479
10480 int
10481 Array_construction_expression::do_traverse(Traverse* traverse)
10482 {
10483   if (this->vals_ != NULL
10484       && this->vals_->traverse(traverse) == TRAVERSE_EXIT)
10485     return TRAVERSE_EXIT;
10486   if (Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
10487     return TRAVERSE_EXIT;
10488   return TRAVERSE_CONTINUE;
10489 }
10490
10491 // Return whether this is a constant initializer.
10492
10493 bool
10494 Array_construction_expression::is_constant_array() const
10495 {
10496   if (this->vals_ == NULL)
10497     return true;
10498
10499   // There are no constant constructors for interfaces.
10500   if (this->type_->array_type()->element_type()->interface_type() != NULL)
10501     return false;
10502
10503   for (Expression_list::const_iterator pv = this->vals_->begin();
10504        pv != this->vals_->end();
10505        ++pv)
10506     {
10507       if (*pv != NULL
10508           && !(*pv)->is_constant()
10509           && (!(*pv)->is_composite_literal()
10510               || (*pv)->is_nonconstant_composite_literal()))
10511         return false;
10512     }
10513   return true;
10514 }
10515
10516 // Final type determination.
10517
10518 void
10519 Array_construction_expression::do_determine_type(const Type_context*)
10520 {
10521   if (this->vals_ == NULL)
10522     return;
10523   Type_context subcontext(this->type_->array_type()->element_type(), false);
10524   for (Expression_list::const_iterator pv = this->vals_->begin();
10525        pv != this->vals_->end();
10526        ++pv)
10527     {
10528       if (*pv != NULL)
10529         (*pv)->determine_type(&subcontext);
10530     }
10531 }
10532
10533 // Check types.
10534
10535 void
10536 Array_construction_expression::do_check_types(Gogo*)
10537 {
10538   if (this->vals_ == NULL)
10539     return;
10540
10541   Array_type* at = this->type_->array_type();
10542   int i = 0;
10543   Type* element_type = at->element_type();
10544   for (Expression_list::const_iterator pv = this->vals_->begin();
10545        pv != this->vals_->end();
10546        ++pv, ++i)
10547     {
10548       if (*pv != NULL
10549           && !Type::are_assignable(element_type, (*pv)->type(), NULL))
10550         {
10551           error_at((*pv)->location(),
10552                    "incompatible type for element %d in composite literal",
10553                    i + 1);
10554           this->set_is_error();
10555         }
10556     }
10557
10558   Expression* length = at->length();
10559   if (length != NULL)
10560     {
10561       mpz_t val;
10562       mpz_init(val);
10563       Type* type;
10564       if (at->length()->integer_constant_value(true, val, &type))
10565         {
10566           if (this->vals_->size() > mpz_get_ui(val))
10567             this->report_error(_("too many elements in composite literal"));
10568         }
10569       mpz_clear(val);
10570     }
10571 }
10572
10573 // Get a constructor tree for the array values.
10574
10575 tree
10576 Array_construction_expression::get_constructor_tree(Translate_context* context,
10577                                                     tree type_tree)
10578 {
10579   VEC(constructor_elt,gc)* values = VEC_alloc(constructor_elt, gc,
10580                                               (this->vals_ == NULL
10581                                                ? 0
10582                                                : this->vals_->size()));
10583   Type* element_type = this->type_->array_type()->element_type();
10584   bool is_constant = true;
10585   if (this->vals_ != NULL)
10586     {
10587       size_t i = 0;
10588       for (Expression_list::const_iterator pv = this->vals_->begin();
10589            pv != this->vals_->end();
10590            ++pv, ++i)
10591         {
10592           constructor_elt* elt = VEC_quick_push(constructor_elt, values, NULL);
10593           elt->index = size_int(i);
10594           if (*pv == NULL)
10595             elt->value = element_type->get_init_tree(context->gogo(), false);
10596           else
10597             {
10598               tree value_tree = (*pv)->get_tree(context);
10599               elt->value = Expression::convert_for_assignment(context,
10600                                                               element_type,
10601                                                               (*pv)->type(),
10602                                                               value_tree,
10603                                                               this->location());
10604             }
10605           if (elt->value == error_mark_node)
10606             return error_mark_node;
10607           if (!TREE_CONSTANT(elt->value))
10608             is_constant = false;
10609         }
10610     }
10611
10612   tree ret = build_constructor(type_tree, values);
10613   if (is_constant)
10614     TREE_CONSTANT(ret) = 1;
10615   return ret;
10616 }
10617
10618 // Export an array construction.
10619
10620 void
10621 Array_construction_expression::do_export(Export* exp) const
10622 {
10623   exp->write_c_string("convert(");
10624   exp->write_type(this->type_);
10625   if (this->vals_ != NULL)
10626     {
10627       for (Expression_list::const_iterator pv = this->vals_->begin();
10628            pv != this->vals_->end();
10629            ++pv)
10630         {
10631           exp->write_c_string(", ");
10632           if (*pv != NULL)
10633             (*pv)->export_expression(exp);
10634         }
10635     }
10636   exp->write_c_string(")");
10637 }
10638
10639 // Construct a fixed array.
10640
10641 class Fixed_array_construction_expression :
10642   public Array_construction_expression
10643 {
10644  public:
10645   Fixed_array_construction_expression(Type* type, Expression_list* vals,
10646                                       source_location location)
10647     : Array_construction_expression(EXPRESSION_FIXED_ARRAY_CONSTRUCTION,
10648                                     type, vals, location)
10649   {
10650     gcc_assert(type->array_type() != NULL
10651                && type->array_type()->length() != NULL);
10652   }
10653
10654  protected:
10655   Expression*
10656   do_copy()
10657   {
10658     return new Fixed_array_construction_expression(this->type(),
10659                                                    (this->vals() == NULL
10660                                                     ? NULL
10661                                                     : this->vals()->copy()),
10662                                                    this->location());
10663   }
10664
10665   tree
10666   do_get_tree(Translate_context*);
10667 };
10668
10669 // Return a tree for constructing a fixed array.
10670
10671 tree
10672 Fixed_array_construction_expression::do_get_tree(Translate_context* context)
10673 {
10674   return this->get_constructor_tree(context,
10675                                     this->type()->get_tree(context->gogo()));
10676 }
10677
10678 // Construct an open array.
10679
10680 class Open_array_construction_expression : public Array_construction_expression
10681 {
10682  public:
10683   Open_array_construction_expression(Type* type, Expression_list* vals,
10684                                      source_location location)
10685     : Array_construction_expression(EXPRESSION_OPEN_ARRAY_CONSTRUCTION,
10686                                     type, vals, location)
10687   {
10688     gcc_assert(type->array_type() != NULL
10689                && type->array_type()->length() == NULL);
10690   }
10691
10692  protected:
10693   // Note that taking the address of an open array literal is invalid.
10694
10695   Expression*
10696   do_copy()
10697   {
10698     return new Open_array_construction_expression(this->type(),
10699                                                   (this->vals() == NULL
10700                                                    ? NULL
10701                                                    : this->vals()->copy()),
10702                                                   this->location());
10703   }
10704
10705   tree
10706   do_get_tree(Translate_context*);
10707 };
10708
10709 // Return a tree for constructing an open array.
10710
10711 tree
10712 Open_array_construction_expression::do_get_tree(Translate_context* context)
10713 {
10714   Type* element_type = this->type()->array_type()->element_type();
10715   tree element_type_tree = element_type->get_tree(context->gogo());
10716   tree values;
10717   tree length_tree;
10718   if (this->vals() == NULL || this->vals()->empty())
10719     {
10720       // We need to create a unique value.
10721       tree max = size_int(0);
10722       tree constructor_type = build_array_type(element_type_tree,
10723                                                build_index_type(max));
10724       if (constructor_type == error_mark_node)
10725         return error_mark_node;
10726       VEC(constructor_elt,gc)* vec = VEC_alloc(constructor_elt, gc, 1);
10727       constructor_elt* elt = VEC_quick_push(constructor_elt, vec, NULL);
10728       elt->index = size_int(0);
10729       elt->value = element_type->get_init_tree(context->gogo(), false);
10730       values = build_constructor(constructor_type, vec);
10731       if (TREE_CONSTANT(elt->value))
10732         TREE_CONSTANT(values) = 1;
10733       length_tree = size_int(0);
10734     }
10735   else
10736     {
10737       tree max = size_int(this->vals()->size() - 1);
10738       tree constructor_type = build_array_type(element_type_tree,
10739                                                build_index_type(max));
10740       if (constructor_type == error_mark_node)
10741         return error_mark_node;
10742       values = this->get_constructor_tree(context, constructor_type);
10743       length_tree = size_int(this->vals()->size());
10744     }
10745
10746   if (values == error_mark_node)
10747     return error_mark_node;
10748
10749   bool is_constant_initializer = TREE_CONSTANT(values);
10750   bool is_in_function = context->function() != NULL;
10751
10752   if (is_constant_initializer)
10753     {
10754       tree tmp = build_decl(this->location(), VAR_DECL,
10755                             create_tmp_var_name("C"), TREE_TYPE(values));
10756       DECL_EXTERNAL(tmp) = 0;
10757       TREE_PUBLIC(tmp) = 0;
10758       TREE_STATIC(tmp) = 1;
10759       DECL_ARTIFICIAL(tmp) = 1;
10760       if (is_in_function)
10761         {
10762           // If this is not a function, we will only initialize the
10763           // value once, so we can use this directly rather than
10764           // copying it.  In that case we can't make it read-only,
10765           // because the program is permitted to change it.
10766           TREE_READONLY(tmp) = 1;
10767           TREE_CONSTANT(tmp) = 1;
10768         }
10769       DECL_INITIAL(tmp) = values;
10770       rest_of_decl_compilation(tmp, 1, 0);
10771       values = tmp;
10772     }
10773
10774   tree space;
10775   tree set;
10776   if (!is_in_function && is_constant_initializer)
10777     {
10778       // Outside of a function, we know the initializer will only run
10779       // once.
10780       space = build_fold_addr_expr(values);
10781       set = NULL_TREE;
10782     }
10783   else
10784     {
10785       tree memsize = TYPE_SIZE_UNIT(TREE_TYPE(values));
10786       space = context->gogo()->allocate_memory(element_type, memsize,
10787                                                this->location());
10788       space = save_expr(space);
10789
10790       tree s = fold_convert(build_pointer_type(TREE_TYPE(values)), space);
10791       tree ref = build_fold_indirect_ref_loc(this->location(), s);
10792       TREE_THIS_NOTRAP(ref) = 1;
10793       set = build2(MODIFY_EXPR, void_type_node, ref, values);
10794     }
10795
10796   // Build a constructor for the open array.
10797
10798   tree type_tree = this->type()->get_tree(context->gogo());
10799   gcc_assert(TREE_CODE(type_tree) == RECORD_TYPE);
10800
10801   VEC(constructor_elt,gc)* init = VEC_alloc(constructor_elt, gc, 3);
10802
10803   constructor_elt* elt = VEC_quick_push(constructor_elt, init, NULL);
10804   tree field = TYPE_FIELDS(type_tree);
10805   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__values") == 0);
10806   elt->index = field;
10807   elt->value = fold_convert(TREE_TYPE(field), space);
10808
10809   elt = VEC_quick_push(constructor_elt, init, NULL);
10810   field = DECL_CHAIN(field);
10811   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__count") == 0);
10812   elt->index = field;
10813   elt->value = fold_convert(TREE_TYPE(field), length_tree);
10814
10815   elt = VEC_quick_push(constructor_elt, init, NULL);
10816   field = DECL_CHAIN(field);
10817   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)),"__capacity") == 0);
10818   elt->index = field;
10819   elt->value = fold_convert(TREE_TYPE(field), length_tree);
10820
10821   tree constructor = build_constructor(type_tree, init);
10822   if (!is_in_function && is_constant_initializer)
10823     TREE_CONSTANT(constructor) = 1;
10824
10825   if (set == NULL_TREE)
10826     return constructor;
10827   else
10828     return build2(COMPOUND_EXPR, type_tree, set, constructor);
10829 }
10830
10831 // Make a slice composite literal.  This is used by the type
10832 // descriptor code.
10833
10834 Expression*
10835 Expression::make_slice_composite_literal(Type* type, Expression_list* vals,
10836                                          source_location location)
10837 {
10838   gcc_assert(type->is_open_array_type());
10839   return new Open_array_construction_expression(type, vals, location);
10840 }
10841
10842 // Construct a map.
10843
10844 class Map_construction_expression : public Expression
10845 {
10846  public:
10847   Map_construction_expression(Type* type, Expression_list* vals,
10848                               source_location location)
10849     : Expression(EXPRESSION_MAP_CONSTRUCTION, location),
10850       type_(type), vals_(vals)
10851   { gcc_assert(vals == NULL || vals->size() % 2 == 0); }
10852
10853  protected:
10854   int
10855   do_traverse(Traverse* traverse);
10856
10857   Type*
10858   do_type()
10859   { return this->type_; }
10860
10861   void
10862   do_determine_type(const Type_context*);
10863
10864   void
10865   do_check_types(Gogo*);
10866
10867   Expression*
10868   do_copy()
10869   {
10870     return new Map_construction_expression(this->type_, this->vals_->copy(),
10871                                            this->location());
10872   }
10873
10874   tree
10875   do_get_tree(Translate_context*);
10876
10877   void
10878   do_export(Export*) const;
10879
10880  private:
10881   // The type of the map to construct.
10882   Type* type_;
10883   // The list of values.
10884   Expression_list* vals_;
10885 };
10886
10887 // Traversal.
10888
10889 int
10890 Map_construction_expression::do_traverse(Traverse* traverse)
10891 {
10892   if (this->vals_ != NULL
10893       && this->vals_->traverse(traverse) == TRAVERSE_EXIT)
10894     return TRAVERSE_EXIT;
10895   if (Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
10896     return TRAVERSE_EXIT;
10897   return TRAVERSE_CONTINUE;
10898 }
10899
10900 // Final type determination.
10901
10902 void
10903 Map_construction_expression::do_determine_type(const Type_context*)
10904 {
10905   if (this->vals_ == NULL)
10906     return;
10907
10908   Map_type* mt = this->type_->map_type();
10909   Type_context key_context(mt->key_type(), false);
10910   Type_context val_context(mt->val_type(), false);
10911   for (Expression_list::const_iterator pv = this->vals_->begin();
10912        pv != this->vals_->end();
10913        ++pv)
10914     {
10915       (*pv)->determine_type(&key_context);
10916       ++pv;
10917       (*pv)->determine_type(&val_context);
10918     }
10919 }
10920
10921 // Check types.
10922
10923 void
10924 Map_construction_expression::do_check_types(Gogo*)
10925 {
10926   if (this->vals_ == NULL)
10927     return;
10928
10929   Map_type* mt = this->type_->map_type();
10930   int i = 0;
10931   Type* key_type = mt->key_type();
10932   Type* val_type = mt->val_type();
10933   for (Expression_list::const_iterator pv = this->vals_->begin();
10934        pv != this->vals_->end();
10935        ++pv, ++i)
10936     {
10937       if (!Type::are_assignable(key_type, (*pv)->type(), NULL))
10938         {
10939           error_at((*pv)->location(),
10940                    "incompatible type for element %d key in map construction",
10941                    i + 1);
10942           this->set_is_error();
10943         }
10944       ++pv;
10945       if (!Type::are_assignable(val_type, (*pv)->type(), NULL))
10946         {
10947           error_at((*pv)->location(),
10948                    ("incompatible type for element %d value "
10949                     "in map construction"),
10950                    i + 1);
10951           this->set_is_error();
10952         }
10953     }
10954 }
10955
10956 // Return a tree for constructing a map.
10957
10958 tree
10959 Map_construction_expression::do_get_tree(Translate_context* context)
10960 {
10961   Gogo* gogo = context->gogo();
10962   source_location loc = this->location();
10963
10964   Map_type* mt = this->type_->map_type();
10965
10966   // Build a struct to hold the key and value.
10967   tree struct_type = make_node(RECORD_TYPE);
10968
10969   Type* key_type = mt->key_type();
10970   tree id = get_identifier("__key");
10971   tree key_field = build_decl(loc, FIELD_DECL, id, key_type->get_tree(gogo));
10972   DECL_CONTEXT(key_field) = struct_type;
10973   TYPE_FIELDS(struct_type) = key_field;
10974
10975   Type* val_type = mt->val_type();
10976   id = get_identifier("__val");
10977   tree val_field = build_decl(loc, FIELD_DECL, id, val_type->get_tree(gogo));
10978   DECL_CONTEXT(val_field) = struct_type;
10979   DECL_CHAIN(key_field) = val_field;
10980
10981   layout_type(struct_type);
10982
10983   bool is_constant = true;
10984   size_t i = 0;
10985   tree valaddr;
10986   tree make_tmp;
10987
10988   if (this->vals_ == NULL || this->vals_->empty())
10989     {
10990       valaddr = null_pointer_node;
10991       make_tmp = NULL_TREE;
10992     }
10993   else
10994     {
10995       VEC(constructor_elt,gc)* values = VEC_alloc(constructor_elt, gc,
10996                                                   this->vals_->size() / 2);
10997
10998       for (Expression_list::const_iterator pv = this->vals_->begin();
10999            pv != this->vals_->end();
11000            ++pv, ++i)
11001         {
11002           bool one_is_constant = true;
11003
11004           VEC(constructor_elt,gc)* one = VEC_alloc(constructor_elt, gc, 2);
11005
11006           constructor_elt* elt = VEC_quick_push(constructor_elt, one, NULL);
11007           elt->index = key_field;
11008           tree val_tree = (*pv)->get_tree(context);
11009           elt->value = Expression::convert_for_assignment(context, key_type,
11010                                                           (*pv)->type(),
11011                                                           val_tree, loc);
11012           if (elt->value == error_mark_node)
11013             return error_mark_node;
11014           if (!TREE_CONSTANT(elt->value))
11015             one_is_constant = false;
11016
11017           ++pv;
11018
11019           elt = VEC_quick_push(constructor_elt, one, NULL);
11020           elt->index = val_field;
11021           val_tree = (*pv)->get_tree(context);
11022           elt->value = Expression::convert_for_assignment(context, val_type,
11023                                                           (*pv)->type(),
11024                                                           val_tree, loc);
11025           if (elt->value == error_mark_node)
11026             return error_mark_node;
11027           if (!TREE_CONSTANT(elt->value))
11028             one_is_constant = false;
11029
11030           elt = VEC_quick_push(constructor_elt, values, NULL);
11031           elt->index = size_int(i);
11032           elt->value = build_constructor(struct_type, one);
11033           if (one_is_constant)
11034             TREE_CONSTANT(elt->value) = 1;
11035           else
11036             is_constant = false;
11037         }
11038
11039       tree index_type = build_index_type(size_int(i - 1));
11040       tree array_type = build_array_type(struct_type, index_type);
11041       tree init = build_constructor(array_type, values);
11042       if (is_constant)
11043         TREE_CONSTANT(init) = 1;
11044       tree tmp;
11045       if (current_function_decl != NULL)
11046         {
11047           tmp = create_tmp_var(array_type, get_name(array_type));
11048           DECL_INITIAL(tmp) = init;
11049           make_tmp = fold_build1_loc(loc, DECL_EXPR, void_type_node, tmp);
11050           TREE_ADDRESSABLE(tmp) = 1;
11051         }
11052       else
11053         {
11054           tmp = build_decl(loc, VAR_DECL, create_tmp_var_name("M"), array_type);
11055           DECL_EXTERNAL(tmp) = 0;
11056           TREE_PUBLIC(tmp) = 0;
11057           TREE_STATIC(tmp) = 1;
11058           DECL_ARTIFICIAL(tmp) = 1;
11059           if (!TREE_CONSTANT(init))
11060             make_tmp = fold_build2_loc(loc, INIT_EXPR, void_type_node, tmp,
11061                                        init);
11062           else
11063             {
11064               TREE_READONLY(tmp) = 1;
11065               TREE_CONSTANT(tmp) = 1;
11066               DECL_INITIAL(tmp) = init;
11067               make_tmp = NULL_TREE;
11068             }
11069           rest_of_decl_compilation(tmp, 1, 0);
11070         }
11071
11072       valaddr = build_fold_addr_expr(tmp);
11073     }
11074
11075   tree descriptor = gogo->map_descriptor(mt);
11076
11077   tree type_tree = this->type_->get_tree(gogo);
11078
11079   static tree construct_map_fndecl;
11080   tree call = Gogo::call_builtin(&construct_map_fndecl,
11081                                  loc,
11082                                  "__go_construct_map",
11083                                  6,
11084                                  type_tree,
11085                                  TREE_TYPE(descriptor),
11086                                  descriptor,
11087                                  sizetype,
11088                                  size_int(i),
11089                                  sizetype,
11090                                  TYPE_SIZE_UNIT(struct_type),
11091                                  sizetype,
11092                                  byte_position(val_field),
11093                                  sizetype,
11094                                  TYPE_SIZE_UNIT(TREE_TYPE(val_field)),
11095                                  const_ptr_type_node,
11096                                  fold_convert(const_ptr_type_node, valaddr));
11097
11098   tree ret;
11099   if (make_tmp == NULL)
11100     ret = call;
11101   else
11102     ret = fold_build2_loc(loc, COMPOUND_EXPR, type_tree, make_tmp, call);
11103   return ret;
11104 }
11105
11106 // Export an array construction.
11107
11108 void
11109 Map_construction_expression::do_export(Export* exp) const
11110 {
11111   exp->write_c_string("convert(");
11112   exp->write_type(this->type_);
11113   for (Expression_list::const_iterator pv = this->vals_->begin();
11114        pv != this->vals_->end();
11115        ++pv)
11116     {
11117       exp->write_c_string(", ");
11118       (*pv)->export_expression(exp);
11119     }
11120   exp->write_c_string(")");
11121 }
11122
11123 // A general composite literal.  This is lowered to a type specific
11124 // version.
11125
11126 class Composite_literal_expression : public Parser_expression
11127 {
11128  public:
11129   Composite_literal_expression(Type* type, int depth, bool has_keys,
11130                                Expression_list* vals, source_location location)
11131     : Parser_expression(EXPRESSION_COMPOSITE_LITERAL, location),
11132       type_(type), depth_(depth), vals_(vals), has_keys_(has_keys)
11133   { }
11134
11135  protected:
11136   int
11137   do_traverse(Traverse* traverse);
11138
11139   Expression*
11140   do_lower(Gogo*, Named_object*, int);
11141
11142   Expression*
11143   do_copy()
11144   {
11145     return new Composite_literal_expression(this->type_, this->depth_,
11146                                             this->has_keys_,
11147                                             (this->vals_ == NULL
11148                                              ? NULL
11149                                              : this->vals_->copy()),
11150                                             this->location());
11151   }
11152
11153  private:
11154   Expression*
11155   lower_struct(Type*);
11156
11157   Expression*
11158   lower_array(Type*);
11159
11160   Expression*
11161   make_array(Type*, Expression_list*);
11162
11163   Expression*
11164   lower_map(Gogo*, Named_object*, Type*);
11165
11166   // The type of the composite literal.
11167   Type* type_;
11168   // The depth within a list of composite literals within a composite
11169   // literal, when the type is omitted.
11170   int depth_;
11171   // The values to put in the composite literal.
11172   Expression_list* vals_;
11173   // If this is true, then VALS_ is a list of pairs: a key and a
11174   // value.  In an array initializer, a missing key will be NULL.
11175   bool has_keys_;
11176 };
11177
11178 // Traversal.
11179
11180 int
11181 Composite_literal_expression::do_traverse(Traverse* traverse)
11182 {
11183   if (this->vals_ != NULL
11184       && this->vals_->traverse(traverse) == TRAVERSE_EXIT)
11185     return TRAVERSE_EXIT;
11186   return Type::traverse(this->type_, traverse);
11187 }
11188
11189 // Lower a generic composite literal into a specific version based on
11190 // the type.
11191
11192 Expression*
11193 Composite_literal_expression::do_lower(Gogo* gogo, Named_object* function, int)
11194 {
11195   Type* type = this->type_;
11196
11197   for (int depth = this->depth_; depth > 0; --depth)
11198     {
11199       if (type->array_type() != NULL)
11200         type = type->array_type()->element_type();
11201       else if (type->map_type() != NULL)
11202         type = type->map_type()->val_type();
11203       else
11204         {
11205           if (!type->is_error_type())
11206             error_at(this->location(),
11207                      ("may only omit types within composite literals "
11208                       "of slice, array, or map type"));
11209           return Expression::make_error(this->location());
11210         }
11211     }
11212
11213   if (type->is_error_type())
11214     return Expression::make_error(this->location());
11215   else if (type->struct_type() != NULL)
11216     return this->lower_struct(type);
11217   else if (type->array_type() != NULL)
11218     return this->lower_array(type);
11219   else if (type->map_type() != NULL)
11220     return this->lower_map(gogo, function, type);
11221   else
11222     {
11223       error_at(this->location(),
11224                ("expected struct, slice, array, or map type "
11225                 "for composite literal"));
11226       return Expression::make_error(this->location());
11227     }
11228 }
11229
11230 // Lower a struct composite literal.
11231
11232 Expression*
11233 Composite_literal_expression::lower_struct(Type* type)
11234 {
11235   source_location location = this->location();
11236   Struct_type* st = type->struct_type();
11237   if (this->vals_ == NULL || !this->has_keys_)
11238     return new Struct_construction_expression(type, this->vals_, location);
11239
11240   size_t field_count = st->field_count();
11241   std::vector<Expression*> vals(field_count);
11242   Expression_list::const_iterator p = this->vals_->begin();
11243   while (p != this->vals_->end())
11244     {
11245       Expression* name_expr = *p;
11246
11247       ++p;
11248       gcc_assert(p != this->vals_->end());
11249       Expression* val = *p;
11250
11251       ++p;
11252
11253       if (name_expr == NULL)
11254         {
11255           error_at(val->location(), "mixture of field and value initializers");
11256           return Expression::make_error(location);
11257         }
11258
11259       bool bad_key = false;
11260       std::string name;
11261       switch (name_expr->classification())
11262         {
11263         case EXPRESSION_UNKNOWN_REFERENCE:
11264           name = name_expr->unknown_expression()->name();
11265           break;
11266
11267         case EXPRESSION_CONST_REFERENCE:
11268           name = static_cast<Const_expression*>(name_expr)->name();
11269           break;
11270
11271         case EXPRESSION_TYPE:
11272           {
11273             Type* t = name_expr->type();
11274             Named_type* nt = t->named_type();
11275             if (nt == NULL)
11276               bad_key = true;
11277             else
11278               name = nt->name();
11279           }
11280           break;
11281
11282         case EXPRESSION_VAR_REFERENCE:
11283           name = name_expr->var_expression()->name();
11284           break;
11285
11286         case EXPRESSION_FUNC_REFERENCE:
11287           name = name_expr->func_expression()->name();
11288           break;
11289
11290         case EXPRESSION_UNARY:
11291           // If there is a local variable around with the same name as
11292           // the field, and this occurs in the closure, then the
11293           // parser may turn the field reference into an indirection
11294           // through the closure.  FIXME: This is a mess.
11295           {
11296             bad_key = true;
11297             Unary_expression* ue = static_cast<Unary_expression*>(name_expr);
11298             if (ue->op() == OPERATOR_MULT)
11299               {
11300                 Field_reference_expression* fre =
11301                   ue->operand()->field_reference_expression();
11302                 if (fre != NULL)
11303                   {
11304                     Struct_type* st =
11305                       fre->expr()->type()->deref()->struct_type();
11306                     if (st != NULL)
11307                       {
11308                         const Struct_field* sf = st->field(fre->field_index());
11309                         name = sf->field_name();
11310                         char buf[20];
11311                         snprintf(buf, sizeof buf, "%u", fre->field_index());
11312                         size_t buflen = strlen(buf);
11313                         if (name.compare(name.length() - buflen, buflen, buf)
11314                             == 0)
11315                           {
11316                             name = name.substr(0, name.length() - buflen);
11317                             bad_key = false;
11318                           }
11319                       }
11320                   }
11321               }
11322           }
11323           break;
11324
11325         default:
11326           bad_key = true;
11327           break;
11328         }
11329       if (bad_key)
11330         {
11331           error_at(name_expr->location(), "expected struct field name");
11332           return Expression::make_error(location);
11333         }
11334
11335       unsigned int index;
11336       const Struct_field* sf = st->find_local_field(name, &index);
11337       if (sf == NULL)
11338         {
11339           error_at(name_expr->location(), "unknown field %qs in %qs",
11340                    Gogo::message_name(name).c_str(),
11341                    (type->named_type() != NULL
11342                     ? type->named_type()->message_name().c_str()
11343                     : "unnamed struct"));
11344           return Expression::make_error(location);
11345         }
11346       if (vals[index] != NULL)
11347         {
11348           error_at(name_expr->location(),
11349                    "duplicate value for field %qs in %qs",
11350                    Gogo::message_name(name).c_str(),
11351                    (type->named_type() != NULL
11352                     ? type->named_type()->message_name().c_str()
11353                     : "unnamed struct"));
11354           return Expression::make_error(location);
11355         }
11356
11357       vals[index] = val;
11358     }
11359
11360   Expression_list* list = new Expression_list;
11361   list->reserve(field_count);
11362   for (size_t i = 0; i < field_count; ++i)
11363     list->push_back(vals[i]);
11364
11365   return new Struct_construction_expression(type, list, location);
11366 }
11367
11368 // Lower an array composite literal.
11369
11370 Expression*
11371 Composite_literal_expression::lower_array(Type* type)
11372 {
11373   source_location location = this->location();
11374   if (this->vals_ == NULL || !this->has_keys_)
11375     return this->make_array(type, this->vals_);
11376
11377   std::vector<Expression*> vals;
11378   vals.reserve(this->vals_->size());
11379   unsigned long index = 0;
11380   Expression_list::const_iterator p = this->vals_->begin();
11381   while (p != this->vals_->end())
11382     {
11383       Expression* index_expr = *p;
11384
11385       ++p;
11386       gcc_assert(p != this->vals_->end());
11387       Expression* val = *p;
11388
11389       ++p;
11390
11391       if (index_expr != NULL)
11392         {
11393           mpz_t ival;
11394           mpz_init(ival);
11395           Type* dummy;
11396           if (!index_expr->integer_constant_value(true, ival, &dummy))
11397             {
11398               mpz_clear(ival);
11399               error_at(index_expr->location(),
11400                        "index expression is not integer constant");
11401               return Expression::make_error(location);
11402             }
11403           if (mpz_sgn(ival) < 0)
11404             {
11405               mpz_clear(ival);
11406               error_at(index_expr->location(), "index expression is negative");
11407               return Expression::make_error(location);
11408             }
11409           index = mpz_get_ui(ival);
11410           if (mpz_cmp_ui(ival, index) != 0)
11411             {
11412               mpz_clear(ival);
11413               error_at(index_expr->location(), "index value overflow");
11414               return Expression::make_error(location);
11415             }
11416           mpz_clear(ival);
11417         }
11418
11419       if (index == vals.size())
11420         vals.push_back(val);
11421       else
11422         {
11423           if (index > vals.size())
11424             {
11425               vals.reserve(index + 32);
11426               vals.resize(index + 1, static_cast<Expression*>(NULL));
11427             }
11428           if (vals[index] != NULL)
11429             {
11430               error_at((index_expr != NULL
11431                         ? index_expr->location()
11432                         : val->location()),
11433                        "duplicate value for index %lu",
11434                        index);
11435               return Expression::make_error(location);
11436             }
11437           vals[index] = val;
11438         }
11439
11440       ++index;
11441     }
11442
11443   size_t size = vals.size();
11444   Expression_list* list = new Expression_list;
11445   list->reserve(size);
11446   for (size_t i = 0; i < size; ++i)
11447     list->push_back(vals[i]);
11448
11449   return this->make_array(type, list);
11450 }
11451
11452 // Actually build the array composite literal. This handles
11453 // [...]{...}.
11454
11455 Expression*
11456 Composite_literal_expression::make_array(Type* type, Expression_list* vals)
11457 {
11458   source_location location = this->location();
11459   Array_type* at = type->array_type();
11460   if (at->length() != NULL && at->length()->is_nil_expression())
11461     {
11462       size_t size = vals == NULL ? 0 : vals->size();
11463       mpz_t vlen;
11464       mpz_init_set_ui(vlen, size);
11465       Expression* elen = Expression::make_integer(&vlen, NULL, location);
11466       mpz_clear(vlen);
11467       at = Type::make_array_type(at->element_type(), elen);
11468       type = at;
11469     }
11470   if (at->length() != NULL)
11471     return new Fixed_array_construction_expression(type, vals, location);
11472   else
11473     return new Open_array_construction_expression(type, vals, location);
11474 }
11475
11476 // Lower a map composite literal.
11477
11478 Expression*
11479 Composite_literal_expression::lower_map(Gogo* gogo, Named_object* function,
11480                                         Type* type)
11481 {
11482   source_location location = this->location();
11483   if (this->vals_ != NULL)
11484     {
11485       if (!this->has_keys_)
11486         {
11487           error_at(location, "map composite literal must have keys");
11488           return Expression::make_error(location);
11489         }
11490
11491       for (Expression_list::iterator p = this->vals_->begin();
11492            p != this->vals_->end();
11493            p += 2)
11494         {
11495           if (*p == NULL)
11496             {
11497               ++p;
11498               error_at((*p)->location(),
11499                        "map composite literal must have keys for every value");
11500               return Expression::make_error(location);
11501             }
11502           // Make sure we have lowered the key; it may not have been
11503           // lowered in order to handle keys for struct composite
11504           // literals.  Lower it now to get the right error message.
11505           if ((*p)->unknown_expression() != NULL)
11506             {
11507               (*p)->unknown_expression()->clear_is_composite_literal_key();
11508               gogo->lower_expression(function, &*p);
11509               gcc_assert((*p)->is_error_expression());
11510               return Expression::make_error(location);
11511             }
11512         }
11513     }
11514
11515   return new Map_construction_expression(type, this->vals_, location);
11516 }
11517
11518 // Make a composite literal expression.
11519
11520 Expression*
11521 Expression::make_composite_literal(Type* type, int depth, bool has_keys,
11522                                    Expression_list* vals,
11523                                    source_location location)
11524 {
11525   return new Composite_literal_expression(type, depth, has_keys, vals,
11526                                           location);
11527 }
11528
11529 // Return whether this expression is a composite literal.
11530
11531 bool
11532 Expression::is_composite_literal() const
11533 {
11534   switch (this->classification_)
11535     {
11536     case EXPRESSION_COMPOSITE_LITERAL:
11537     case EXPRESSION_STRUCT_CONSTRUCTION:
11538     case EXPRESSION_FIXED_ARRAY_CONSTRUCTION:
11539     case EXPRESSION_OPEN_ARRAY_CONSTRUCTION:
11540     case EXPRESSION_MAP_CONSTRUCTION:
11541       return true;
11542     default:
11543       return false;
11544     }
11545 }
11546
11547 // Return whether this expression is a composite literal which is not
11548 // constant.
11549
11550 bool
11551 Expression::is_nonconstant_composite_literal() const
11552 {
11553   switch (this->classification_)
11554     {
11555     case EXPRESSION_STRUCT_CONSTRUCTION:
11556       {
11557         const Struct_construction_expression *psce =
11558           static_cast<const Struct_construction_expression*>(this);
11559         return !psce->is_constant_struct();
11560       }
11561     case EXPRESSION_FIXED_ARRAY_CONSTRUCTION:
11562       {
11563         const Fixed_array_construction_expression *pace =
11564           static_cast<const Fixed_array_construction_expression*>(this);
11565         return !pace->is_constant_array();
11566       }
11567     case EXPRESSION_OPEN_ARRAY_CONSTRUCTION:
11568       {
11569         const Open_array_construction_expression *pace =
11570           static_cast<const Open_array_construction_expression*>(this);
11571         return !pace->is_constant_array();
11572       }
11573     case EXPRESSION_MAP_CONSTRUCTION:
11574       return true;
11575     default:
11576       return false;
11577     }
11578 }
11579
11580 // Return true if this is a reference to a local variable.
11581
11582 bool
11583 Expression::is_local_variable() const
11584 {
11585   const Var_expression* ve = this->var_expression();
11586   if (ve == NULL)
11587     return false;
11588   const Named_object* no = ve->named_object();
11589   return (no->is_result_variable()
11590           || (no->is_variable() && !no->var_value()->is_global()));
11591 }
11592
11593 // Class Type_guard_expression.
11594
11595 // Traversal.
11596
11597 int
11598 Type_guard_expression::do_traverse(Traverse* traverse)
11599 {
11600   if (Expression::traverse(&this->expr_, traverse) == TRAVERSE_EXIT
11601       || Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
11602     return TRAVERSE_EXIT;
11603   return TRAVERSE_CONTINUE;
11604 }
11605
11606 // Check types of a type guard expression.  The expression must have
11607 // an interface type, but the actual type conversion is checked at run
11608 // time.
11609
11610 void
11611 Type_guard_expression::do_check_types(Gogo*)
11612 {
11613   // 6g permits using a type guard with unsafe.pointer; we are
11614   // compatible.
11615   Type* expr_type = this->expr_->type();
11616   if (expr_type->is_unsafe_pointer_type())
11617     {
11618       if (this->type_->points_to() == NULL
11619           && (this->type_->integer_type() == NULL
11620               || (this->type_->forwarded()
11621                   != Type::lookup_integer_type("uintptr"))))
11622         this->report_error(_("invalid unsafe.Pointer conversion"));
11623     }
11624   else if (this->type_->is_unsafe_pointer_type())
11625     {
11626       if (expr_type->points_to() == NULL
11627           && (expr_type->integer_type() == NULL
11628               || (expr_type->forwarded()
11629                   != Type::lookup_integer_type("uintptr"))))
11630         this->report_error(_("invalid unsafe.Pointer conversion"));
11631     }
11632   else if (expr_type->interface_type() == NULL)
11633     {
11634       if (!expr_type->is_error_type() && !this->type_->is_error_type())
11635         this->report_error(_("type assertion only valid for interface types"));
11636       this->set_is_error();
11637     }
11638   else if (this->type_->interface_type() == NULL)
11639     {
11640       std::string reason;
11641       if (!expr_type->interface_type()->implements_interface(this->type_,
11642                                                              &reason))
11643         {
11644           if (!this->type_->is_error_type())
11645             {
11646               if (reason.empty())
11647                 this->report_error(_("impossible type assertion: "
11648                                      "type does not implement interface"));
11649               else
11650                 error_at(this->location(),
11651                          ("impossible type assertion: "
11652                           "type does not implement interface (%s)"),
11653                          reason.c_str());
11654             }
11655           this->set_is_error();
11656         }
11657     }
11658 }
11659
11660 // Return a tree for a type guard expression.
11661
11662 tree
11663 Type_guard_expression::do_get_tree(Translate_context* context)
11664 {
11665   Gogo* gogo = context->gogo();
11666   tree expr_tree = this->expr_->get_tree(context);
11667   if (expr_tree == error_mark_node)
11668     return error_mark_node;
11669   Type* expr_type = this->expr_->type();
11670   if ((this->type_->is_unsafe_pointer_type()
11671        && (expr_type->points_to() != NULL
11672            || expr_type->integer_type() != NULL))
11673       || (expr_type->is_unsafe_pointer_type()
11674           && this->type_->points_to() != NULL))
11675     return convert_to_pointer(this->type_->get_tree(gogo), expr_tree);
11676   else if (expr_type->is_unsafe_pointer_type()
11677            && this->type_->integer_type() != NULL)
11678     return convert_to_integer(this->type_->get_tree(gogo), expr_tree);
11679   else if (this->type_->interface_type() != NULL)
11680     return Expression::convert_interface_to_interface(context, this->type_,
11681                                                       this->expr_->type(),
11682                                                       expr_tree, true,
11683                                                       this->location());
11684   else
11685     return Expression::convert_for_assignment(context, this->type_,
11686                                               this->expr_->type(), expr_tree,
11687                                               this->location());
11688 }
11689
11690 // Make a type guard expression.
11691
11692 Expression*
11693 Expression::make_type_guard(Expression* expr, Type* type,
11694                             source_location location)
11695 {
11696   return new Type_guard_expression(expr, type, location);
11697 }
11698
11699 // Class Heap_composite_expression.
11700
11701 // When you take the address of a composite literal, it is allocated
11702 // on the heap.  This class implements that.
11703
11704 class Heap_composite_expression : public Expression
11705 {
11706  public:
11707   Heap_composite_expression(Expression* expr, source_location location)
11708     : Expression(EXPRESSION_HEAP_COMPOSITE, location),
11709       expr_(expr)
11710   { }
11711
11712  protected:
11713   int
11714   do_traverse(Traverse* traverse)
11715   { return Expression::traverse(&this->expr_, traverse); }
11716
11717   Type*
11718   do_type()
11719   { return Type::make_pointer_type(this->expr_->type()); }
11720
11721   void
11722   do_determine_type(const Type_context*)
11723   { this->expr_->determine_type_no_context(); }
11724
11725   Expression*
11726   do_copy()
11727   {
11728     return Expression::make_heap_composite(this->expr_->copy(),
11729                                            this->location());
11730   }
11731
11732   tree
11733   do_get_tree(Translate_context*);
11734
11735   // We only export global objects, and the parser does not generate
11736   // this in global scope.
11737   void
11738   do_export(Export*) const
11739   { gcc_unreachable(); }
11740
11741  private:
11742   // The composite literal which is being put on the heap.
11743   Expression* expr_;
11744 };
11745
11746 // Return a tree which allocates a composite literal on the heap.
11747
11748 tree
11749 Heap_composite_expression::do_get_tree(Translate_context* context)
11750 {
11751   tree expr_tree = this->expr_->get_tree(context);
11752   if (expr_tree == error_mark_node)
11753     return error_mark_node;
11754   tree expr_size = TYPE_SIZE_UNIT(TREE_TYPE(expr_tree));
11755   gcc_assert(TREE_CODE(expr_size) == INTEGER_CST);
11756   tree space = context->gogo()->allocate_memory(this->expr_->type(),
11757                                                 expr_size, this->location());
11758   space = fold_convert(build_pointer_type(TREE_TYPE(expr_tree)), space);
11759   space = save_expr(space);
11760   tree ref = build_fold_indirect_ref_loc(this->location(), space);
11761   TREE_THIS_NOTRAP(ref) = 1;
11762   tree ret = build2(COMPOUND_EXPR, TREE_TYPE(space),
11763                     build2(MODIFY_EXPR, void_type_node, ref, expr_tree),
11764                     space);
11765   SET_EXPR_LOCATION(ret, this->location());
11766   return ret;
11767 }
11768
11769 // Allocate a composite literal on the heap.
11770
11771 Expression*
11772 Expression::make_heap_composite(Expression* expr, source_location location)
11773 {
11774   return new Heap_composite_expression(expr, location);
11775 }
11776
11777 // Class Receive_expression.
11778
11779 // Return the type of a receive expression.
11780
11781 Type*
11782 Receive_expression::do_type()
11783 {
11784   Channel_type* channel_type = this->channel_->type()->channel_type();
11785   if (channel_type == NULL)
11786     return Type::make_error_type();
11787   return channel_type->element_type();
11788 }
11789
11790 // Check types for a receive expression.
11791
11792 void
11793 Receive_expression::do_check_types(Gogo*)
11794 {
11795   Type* type = this->channel_->type();
11796   if (type->is_error_type())
11797     {
11798       this->set_is_error();
11799       return;
11800     }
11801   if (type->channel_type() == NULL)
11802     {
11803       this->report_error(_("expected channel"));
11804       return;
11805     }
11806   if (!type->channel_type()->may_receive())
11807     {
11808       this->report_error(_("invalid receive on send-only channel"));
11809       return;
11810     }
11811 }
11812
11813 // Get a tree for a receive expression.
11814
11815 tree
11816 Receive_expression::do_get_tree(Translate_context* context)
11817 {
11818   Channel_type* channel_type = this->channel_->type()->channel_type();
11819   gcc_assert(channel_type != NULL);
11820   Type* element_type = channel_type->element_type();
11821   tree element_type_tree = element_type->get_tree(context->gogo());
11822
11823   tree channel = this->channel_->get_tree(context);
11824   if (element_type_tree == error_mark_node || channel == error_mark_node)
11825     return error_mark_node;
11826
11827   return Gogo::receive_from_channel(element_type_tree, channel,
11828                                     this->for_select_, this->location());
11829 }
11830
11831 // Make a receive expression.
11832
11833 Receive_expression*
11834 Expression::make_receive(Expression* channel, source_location location)
11835 {
11836   return new Receive_expression(channel, location);
11837 }
11838
11839 // Class Send_expression.
11840
11841 // Traversal.
11842
11843 int
11844 Send_expression::do_traverse(Traverse* traverse)
11845 {
11846   if (Expression::traverse(&this->channel_, traverse) == TRAVERSE_EXIT)
11847     return TRAVERSE_EXIT;
11848   return Expression::traverse(&this->val_, traverse);
11849 }
11850
11851 // Get the type.
11852
11853 Type*
11854 Send_expression::do_type()
11855 {
11856   return Type::lookup_bool_type();
11857 }
11858
11859 // Set types.
11860
11861 void
11862 Send_expression::do_determine_type(const Type_context*)
11863 {
11864   this->channel_->determine_type_no_context();
11865
11866   Type* type = this->channel_->type();
11867   Type_context subcontext;
11868   if (type->channel_type() != NULL)
11869     subcontext.type = type->channel_type()->element_type();
11870   this->val_->determine_type(&subcontext);
11871 }
11872
11873 // Check types.
11874
11875 void
11876 Send_expression::do_check_types(Gogo*)
11877 {
11878   Type* type = this->channel_->type();
11879   if (type->is_error_type())
11880     {
11881       this->set_is_error();
11882       return;
11883     }
11884   Channel_type* channel_type = type->channel_type();
11885   if (channel_type == NULL)
11886     {
11887       error_at(this->location(), "left operand of %<<-%> must be channel");
11888       this->set_is_error();
11889       return;
11890     }
11891   Type* element_type = channel_type->element_type();
11892   if (element_type != NULL
11893       && !Type::are_assignable(element_type, this->val_->type(), NULL))
11894     {
11895       this->report_error(_("incompatible types in send"));
11896       return;
11897     }
11898   if (!channel_type->may_send())
11899     {
11900       this->report_error(_("invalid send on receive-only channel"));
11901       return;
11902     }
11903 }
11904
11905 // Get a tree for a send expression.
11906
11907 tree
11908 Send_expression::do_get_tree(Translate_context* context)
11909 {
11910   tree channel = this->channel_->get_tree(context);
11911   tree val = this->val_->get_tree(context);
11912   if (channel == error_mark_node || val == error_mark_node)
11913     return error_mark_node;
11914   Channel_type* channel_type = this->channel_->type()->channel_type();
11915   val = Expression::convert_for_assignment(context,
11916                                            channel_type->element_type(),
11917                                            this->val_->type(),
11918                                            val,
11919                                            this->location());
11920   return Gogo::send_on_channel(channel, val, this->is_value_discarded_,
11921                                this->for_select_, this->location());
11922 }
11923
11924 // Make a send expression
11925
11926 Send_expression*
11927 Expression::make_send(Expression* channel, Expression* val,
11928                       source_location location)
11929 {
11930   return new Send_expression(channel, val, location);
11931 }
11932
11933 // An expression which evaluates to a pointer to the type descriptor
11934 // of a type.
11935
11936 class Type_descriptor_expression : public Expression
11937 {
11938  public:
11939   Type_descriptor_expression(Type* type, source_location location)
11940     : Expression(EXPRESSION_TYPE_DESCRIPTOR, location),
11941       type_(type)
11942   { }
11943
11944  protected:
11945   Type*
11946   do_type()
11947   { return Type::make_type_descriptor_ptr_type(); }
11948
11949   void
11950   do_determine_type(const Type_context*)
11951   { }
11952
11953   Expression*
11954   do_copy()
11955   { return this; }
11956
11957   tree
11958   do_get_tree(Translate_context* context)
11959   { return this->type_->type_descriptor_pointer(context->gogo()); }
11960
11961  private:
11962   // The type for which this is the descriptor.
11963   Type* type_;
11964 };
11965
11966 // Make a type descriptor expression.
11967
11968 Expression*
11969 Expression::make_type_descriptor(Type* type, source_location location)
11970 {
11971   return new Type_descriptor_expression(type, location);
11972 }
11973
11974 // An expression which evaluates to some characteristic of a type.
11975 // This is only used to initialize fields of a type descriptor.  Using
11976 // a new expression class is slightly inefficient but gives us a good
11977 // separation between the frontend and the middle-end with regard to
11978 // how types are laid out.
11979
11980 class Type_info_expression : public Expression
11981 {
11982  public:
11983   Type_info_expression(Type* type, Type_info type_info)
11984     : Expression(EXPRESSION_TYPE_INFO, BUILTINS_LOCATION),
11985       type_(type), type_info_(type_info)
11986   { }
11987
11988  protected:
11989   Type*
11990   do_type();
11991
11992   void
11993   do_determine_type(const Type_context*)
11994   { }
11995
11996   Expression*
11997   do_copy()
11998   { return this; }
11999
12000   tree
12001   do_get_tree(Translate_context* context);
12002
12003  private:
12004   // The type for which we are getting information.
12005   Type* type_;
12006   // What information we want.
12007   Type_info type_info_;
12008 };
12009
12010 // The type is chosen to match what the type descriptor struct
12011 // expects.
12012
12013 Type*
12014 Type_info_expression::do_type()
12015 {
12016   switch (this->type_info_)
12017     {
12018     case TYPE_INFO_SIZE:
12019       return Type::lookup_integer_type("uintptr");
12020     case TYPE_INFO_ALIGNMENT:
12021     case TYPE_INFO_FIELD_ALIGNMENT:
12022       return Type::lookup_integer_type("uint8");
12023     default:
12024       gcc_unreachable();
12025     }
12026 }
12027
12028 // Return type information in GENERIC.
12029
12030 tree
12031 Type_info_expression::do_get_tree(Translate_context* context)
12032 {
12033   tree type_tree = this->type_->get_tree(context->gogo());
12034   if (type_tree == error_mark_node)
12035     return error_mark_node;
12036
12037   tree val_type_tree = this->type()->get_tree(context->gogo());
12038   gcc_assert(val_type_tree != error_mark_node);
12039
12040   if (this->type_info_ == TYPE_INFO_SIZE)
12041     return fold_convert_loc(BUILTINS_LOCATION, val_type_tree,
12042                             TYPE_SIZE_UNIT(type_tree));
12043   else
12044     {
12045       unsigned int val;
12046       if (this->type_info_ == TYPE_INFO_ALIGNMENT)
12047         val = go_type_alignment(type_tree);
12048       else
12049         val = go_field_alignment(type_tree);
12050       return build_int_cstu(val_type_tree, val);
12051     }
12052 }
12053
12054 // Make a type info expression.
12055
12056 Expression*
12057 Expression::make_type_info(Type* type, Type_info type_info)
12058 {
12059   return new Type_info_expression(type, type_info);
12060 }
12061
12062 // An expression which evaluates to the offset of a field within a
12063 // struct.  This, like Type_info_expression, q.v., is only used to
12064 // initialize fields of a type descriptor.
12065
12066 class Struct_field_offset_expression : public Expression
12067 {
12068  public:
12069   Struct_field_offset_expression(Struct_type* type, const Struct_field* field)
12070     : Expression(EXPRESSION_STRUCT_FIELD_OFFSET, BUILTINS_LOCATION),
12071       type_(type), field_(field)
12072   { }
12073
12074  protected:
12075   Type*
12076   do_type()
12077   { return Type::lookup_integer_type("uintptr"); }
12078
12079   void
12080   do_determine_type(const Type_context*)
12081   { }
12082
12083   Expression*
12084   do_copy()
12085   { return this; }
12086
12087   tree
12088   do_get_tree(Translate_context* context);
12089
12090  private:
12091   // The type of the struct.
12092   Struct_type* type_;
12093   // The field.
12094   const Struct_field* field_;
12095 };
12096
12097 // Return a struct field offset in GENERIC.
12098
12099 tree
12100 Struct_field_offset_expression::do_get_tree(Translate_context* context)
12101 {
12102   tree type_tree = this->type_->get_tree(context->gogo());
12103   if (type_tree == error_mark_node)
12104     return error_mark_node;
12105
12106   tree val_type_tree = this->type()->get_tree(context->gogo());
12107   gcc_assert(val_type_tree != error_mark_node);
12108
12109   const Struct_field_list* fields = this->type_->fields();
12110   tree struct_field_tree = TYPE_FIELDS(type_tree);
12111   Struct_field_list::const_iterator p;
12112   for (p = fields->begin();
12113        p != fields->end();
12114        ++p, struct_field_tree = DECL_CHAIN(struct_field_tree))
12115     {
12116       gcc_assert(struct_field_tree != NULL_TREE);
12117       if (&*p == this->field_)
12118         break;
12119     }
12120   gcc_assert(&*p == this->field_);
12121
12122   return fold_convert_loc(BUILTINS_LOCATION, val_type_tree,
12123                           byte_position(struct_field_tree));
12124 }
12125
12126 // Make an expression for a struct field offset.
12127
12128 Expression*
12129 Expression::make_struct_field_offset(Struct_type* type,
12130                                      const Struct_field* field)
12131 {
12132   return new Struct_field_offset_expression(type, field);
12133 }
12134
12135 // An expression which evaluates to the address of an unnamed label.
12136
12137 class Label_addr_expression : public Expression
12138 {
12139  public:
12140   Label_addr_expression(Label* label, source_location location)
12141     : Expression(EXPRESSION_LABEL_ADDR, location),
12142       label_(label)
12143   { }
12144
12145  protected:
12146   Type*
12147   do_type()
12148   { return Type::make_pointer_type(Type::make_void_type()); }
12149
12150   void
12151   do_determine_type(const Type_context*)
12152   { }
12153
12154   Expression*
12155   do_copy()
12156   { return new Label_addr_expression(this->label_, this->location()); }
12157
12158   tree
12159   do_get_tree(Translate_context*)
12160   { return this->label_->get_addr(this->location()); }
12161
12162  private:
12163   // The label whose address we are taking.
12164   Label* label_;
12165 };
12166
12167 // Make an expression for the address of an unnamed label.
12168
12169 Expression*
12170 Expression::make_label_addr(Label* label, source_location location)
12171 {
12172   return new Label_addr_expression(label, location);
12173 }
12174
12175 // Import an expression.  This comes at the end in order to see the
12176 // various class definitions.
12177
12178 Expression*
12179 Expression::import_expression(Import* imp)
12180 {
12181   int c = imp->peek_char();
12182   if (imp->match_c_string("- ")
12183       || imp->match_c_string("! ")
12184       || imp->match_c_string("^ "))
12185     return Unary_expression::do_import(imp);
12186   else if (c == '(')
12187     return Binary_expression::do_import(imp);
12188   else if (imp->match_c_string("true")
12189            || imp->match_c_string("false"))
12190     return Boolean_expression::do_import(imp);
12191   else if (c == '"')
12192     return String_expression::do_import(imp);
12193   else if (c == '-' || (c >= '0' && c <= '9'))
12194     {
12195       // This handles integers, floats and complex constants.
12196       return Integer_expression::do_import(imp);
12197     }
12198   else if (imp->match_c_string("nil"))
12199     return Nil_expression::do_import(imp);
12200   else if (imp->match_c_string("convert"))
12201     return Type_conversion_expression::do_import(imp);
12202   else
12203     {
12204       error_at(imp->location(), "import error: expected expression");
12205       return Expression::make_error(imp->location());
12206     }
12207 }
12208
12209 // Class Expression_list.
12210
12211 // Traverse the list.
12212
12213 int
12214 Expression_list::traverse(Traverse* traverse)
12215 {
12216   for (Expression_list::iterator p = this->begin();
12217        p != this->end();
12218        ++p)
12219     {
12220       if (*p != NULL)
12221         {
12222           if (Expression::traverse(&*p, traverse) == TRAVERSE_EXIT)
12223             return TRAVERSE_EXIT;
12224         }
12225     }
12226   return TRAVERSE_CONTINUE;
12227 }
12228
12229 // Copy the list.
12230
12231 Expression_list*
12232 Expression_list::copy()
12233 {
12234   Expression_list* ret = new Expression_list();
12235   for (Expression_list::iterator p = this->begin();
12236        p != this->end();
12237        ++p)
12238     {
12239       if (*p == NULL)
12240         ret->push_back(NULL);
12241       else
12242         ret->push_back((*p)->copy());
12243     }
12244   return ret;
12245 }
12246
12247 // Return whether an expression list has an error expression.
12248
12249 bool
12250 Expression_list::contains_error() const
12251 {
12252   for (Expression_list::const_iterator p = this->begin();
12253        p != this->end();
12254        ++p)
12255     if (*p != NULL && (*p)->is_error_expression())
12256       return true;
12257   return false;
12258 }