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   Type* type = this->expr_->type();
3828   if (type->is_error_type())
3829     {
3830       this->set_is_error();
3831       return;
3832     }
3833
3834   switch (this->op_)
3835     {
3836     case OPERATOR_PLUS:
3837     case OPERATOR_MINUS:
3838       if (type->integer_type() == NULL
3839           && type->float_type() == NULL
3840           && type->complex_type() == NULL)
3841         this->report_error(_("expected numeric type"));
3842       break;
3843
3844     case OPERATOR_NOT:
3845     case OPERATOR_XOR:
3846       if (type->integer_type() == NULL
3847           && !type->is_boolean_type())
3848         this->report_error(_("expected integer or boolean type"));
3849       break;
3850
3851     case OPERATOR_AND:
3852       if (!this->expr_->is_addressable())
3853         this->report_error(_("invalid operand for unary %<&%>"));
3854       else
3855         this->expr_->address_taken(this->escapes_);
3856       break;
3857
3858     case OPERATOR_MULT:
3859       // Indirecting through a pointer.
3860       if (type->points_to() == NULL)
3861         this->report_error(_("expected pointer"));
3862       break;
3863
3864     default:
3865       gcc_unreachable();
3866     }
3867 }
3868
3869 // Get a tree for a unary expression.
3870
3871 tree
3872 Unary_expression::do_get_tree(Translate_context* context)
3873 {
3874   tree expr = this->expr_->get_tree(context);
3875   if (expr == error_mark_node)
3876     return error_mark_node;
3877
3878   source_location loc = this->location();
3879   switch (this->op_)
3880     {
3881     case OPERATOR_PLUS:
3882       return expr;
3883
3884     case OPERATOR_MINUS:
3885       {
3886         tree type = TREE_TYPE(expr);
3887         tree compute_type = excess_precision_type(type);
3888         if (compute_type != NULL_TREE)
3889           expr = ::convert(compute_type, expr);
3890         tree ret = fold_build1_loc(loc, NEGATE_EXPR,
3891                                    (compute_type != NULL_TREE
3892                                     ? compute_type
3893                                     : type),
3894                                    expr);
3895         if (compute_type != NULL_TREE)
3896           ret = ::convert(type, ret);
3897         return ret;
3898       }
3899
3900     case OPERATOR_NOT:
3901       if (TREE_CODE(TREE_TYPE(expr)) == BOOLEAN_TYPE)
3902         return fold_build1_loc(loc, TRUTH_NOT_EXPR, TREE_TYPE(expr), expr);
3903       else
3904         return fold_build2_loc(loc, NE_EXPR, boolean_type_node, expr,
3905                                build_int_cst(TREE_TYPE(expr), 0));
3906
3907     case OPERATOR_XOR:
3908       return fold_build1_loc(loc, BIT_NOT_EXPR, TREE_TYPE(expr), expr);
3909
3910     case OPERATOR_AND:
3911       // We should not see a non-constant constructor here; cases
3912       // where we would see one should have been moved onto the heap
3913       // at parse time.  Taking the address of a nonconstant
3914       // constructor will not do what the programmer expects.
3915       gcc_assert(TREE_CODE(expr) != CONSTRUCTOR || TREE_CONSTANT(expr));
3916       gcc_assert(TREE_CODE(expr) != ADDR_EXPR);
3917
3918       // Build a decl for a constant constructor.
3919       if (TREE_CODE(expr) == CONSTRUCTOR && TREE_CONSTANT(expr))
3920         {
3921           tree decl = build_decl(this->location(), VAR_DECL,
3922                                  create_tmp_var_name("C"), TREE_TYPE(expr));
3923           DECL_EXTERNAL(decl) = 0;
3924           TREE_PUBLIC(decl) = 0;
3925           TREE_READONLY(decl) = 1;
3926           TREE_CONSTANT(decl) = 1;
3927           TREE_STATIC(decl) = 1;
3928           TREE_ADDRESSABLE(decl) = 1;
3929           DECL_ARTIFICIAL(decl) = 1;
3930           DECL_INITIAL(decl) = expr;
3931           rest_of_decl_compilation(decl, 1, 0);
3932           expr = decl;
3933         }
3934
3935       return build_fold_addr_expr_loc(loc, expr);
3936
3937     case OPERATOR_MULT:
3938       {
3939         gcc_assert(POINTER_TYPE_P(TREE_TYPE(expr)));
3940
3941         // If we are dereferencing the pointer to a large struct, we
3942         // need to check for nil.  We don't bother to check for small
3943         // structs because we expect the system to crash on a nil
3944         // pointer dereference.
3945         HOST_WIDE_INT s = int_size_in_bytes(TREE_TYPE(TREE_TYPE(expr)));
3946         if (s == -1 || s >= 4096)
3947           {
3948             if (!DECL_P(expr))
3949               expr = save_expr(expr);
3950             tree compare = fold_build2_loc(loc, EQ_EXPR, boolean_type_node,
3951                                            expr,
3952                                            fold_convert(TREE_TYPE(expr),
3953                                                         null_pointer_node));
3954             tree crash = Gogo::runtime_error(RUNTIME_ERROR_NIL_DEREFERENCE,
3955                                              loc);
3956             expr = fold_build2_loc(loc, COMPOUND_EXPR, TREE_TYPE(expr),
3957                                    build3(COND_EXPR, void_type_node,
3958                                           compare, crash, NULL_TREE),
3959                                    expr);
3960           }
3961
3962         // If the type of EXPR is a recursive pointer type, then we
3963         // need to insert a cast before indirecting.
3964         if (TREE_TYPE(TREE_TYPE(expr)) == ptr_type_node)
3965           {
3966             Type* pt = this->expr_->type()->points_to();
3967             tree ind = pt->get_tree(context->gogo());
3968             expr = fold_convert_loc(loc, build_pointer_type(ind), expr);
3969           }
3970
3971         return build_fold_indirect_ref_loc(loc, expr);
3972       }
3973
3974     default:
3975       gcc_unreachable();
3976     }
3977 }
3978
3979 // Export a unary expression.
3980
3981 void
3982 Unary_expression::do_export(Export* exp) const
3983 {
3984   switch (this->op_)
3985     {
3986     case OPERATOR_PLUS:
3987       exp->write_c_string("+ ");
3988       break;
3989     case OPERATOR_MINUS:
3990       exp->write_c_string("- ");
3991       break;
3992     case OPERATOR_NOT:
3993       exp->write_c_string("! ");
3994       break;
3995     case OPERATOR_XOR:
3996       exp->write_c_string("^ ");
3997       break;
3998     case OPERATOR_AND:
3999     case OPERATOR_MULT:
4000     default:
4001       gcc_unreachable();
4002     }
4003   this->expr_->export_expression(exp);
4004 }
4005
4006 // Import a unary expression.
4007
4008 Expression*
4009 Unary_expression::do_import(Import* imp)
4010 {
4011   Operator op;
4012   switch (imp->get_char())
4013     {
4014     case '+':
4015       op = OPERATOR_PLUS;
4016       break;
4017     case '-':
4018       op = OPERATOR_MINUS;
4019       break;
4020     case '!':
4021       op = OPERATOR_NOT;
4022       break;
4023     case '^':
4024       op = OPERATOR_XOR;
4025       break;
4026     default:
4027       gcc_unreachable();
4028     }
4029   imp->require_c_string(" ");
4030   Expression* expr = Expression::import_expression(imp);
4031   return Expression::make_unary(op, expr, imp->location());
4032 }
4033
4034 // Make a unary expression.
4035
4036 Expression*
4037 Expression::make_unary(Operator op, Expression* expr, source_location location)
4038 {
4039   return new Unary_expression(op, expr, location);
4040 }
4041
4042 // If this is an indirection through a pointer, return the expression
4043 // being pointed through.  Otherwise return this.
4044
4045 Expression*
4046 Expression::deref()
4047 {
4048   if (this->classification_ == EXPRESSION_UNARY)
4049     {
4050       Unary_expression* ue = static_cast<Unary_expression*>(this);
4051       if (ue->op() == OPERATOR_MULT)
4052         return ue->operand();
4053     }
4054   return this;
4055 }
4056
4057 // Class Binary_expression.
4058
4059 // Traversal.
4060
4061 int
4062 Binary_expression::do_traverse(Traverse* traverse)
4063 {
4064   int t = Expression::traverse(&this->left_, traverse);
4065   if (t == TRAVERSE_EXIT)
4066     return TRAVERSE_EXIT;
4067   return Expression::traverse(&this->right_, traverse);
4068 }
4069
4070 // Compare integer constants according to OP.
4071
4072 bool
4073 Binary_expression::compare_integer(Operator op, mpz_t left_val,
4074                                    mpz_t right_val)
4075 {
4076   int i = mpz_cmp(left_val, right_val);
4077   switch (op)
4078     {
4079     case OPERATOR_EQEQ:
4080       return i == 0;
4081     case OPERATOR_NOTEQ:
4082       return i != 0;
4083     case OPERATOR_LT:
4084       return i < 0;
4085     case OPERATOR_LE:
4086       return i <= 0;
4087     case OPERATOR_GT:
4088       return i > 0;
4089     case OPERATOR_GE:
4090       return i >= 0;
4091     default:
4092       gcc_unreachable();
4093     }
4094 }
4095
4096 // Compare floating point constants according to OP.
4097
4098 bool
4099 Binary_expression::compare_float(Operator op, Type* type, mpfr_t left_val,
4100                                  mpfr_t right_val)
4101 {
4102   int i;
4103   if (type == NULL)
4104     i = mpfr_cmp(left_val, right_val);
4105   else
4106     {
4107       mpfr_t lv;
4108       mpfr_init_set(lv, left_val, GMP_RNDN);
4109       mpfr_t rv;
4110       mpfr_init_set(rv, right_val, GMP_RNDN);
4111       Float_expression::constrain_float(lv, type);
4112       Float_expression::constrain_float(rv, type);
4113       i = mpfr_cmp(lv, rv);
4114       mpfr_clear(lv);
4115       mpfr_clear(rv);
4116     }
4117   switch (op)
4118     {
4119     case OPERATOR_EQEQ:
4120       return i == 0;
4121     case OPERATOR_NOTEQ:
4122       return i != 0;
4123     case OPERATOR_LT:
4124       return i < 0;
4125     case OPERATOR_LE:
4126       return i <= 0;
4127     case OPERATOR_GT:
4128       return i > 0;
4129     case OPERATOR_GE:
4130       return i >= 0;
4131     default:
4132       gcc_unreachable();
4133     }
4134 }
4135
4136 // Compare complex constants according to OP.  Complex numbers may
4137 // only be compared for equality.
4138
4139 bool
4140 Binary_expression::compare_complex(Operator op, Type* type,
4141                                    mpfr_t left_real, mpfr_t left_imag,
4142                                    mpfr_t right_real, mpfr_t right_imag)
4143 {
4144   bool is_equal;
4145   if (type == NULL)
4146     is_equal = (mpfr_cmp(left_real, right_real) == 0
4147                 && mpfr_cmp(left_imag, right_imag) == 0);
4148   else
4149     {
4150       mpfr_t lr;
4151       mpfr_t li;
4152       mpfr_init_set(lr, left_real, GMP_RNDN);
4153       mpfr_init_set(li, left_imag, GMP_RNDN);
4154       mpfr_t rr;
4155       mpfr_t ri;
4156       mpfr_init_set(rr, right_real, GMP_RNDN);
4157       mpfr_init_set(ri, right_imag, GMP_RNDN);
4158       Complex_expression::constrain_complex(lr, li, type);
4159       Complex_expression::constrain_complex(rr, ri, type);
4160       is_equal = mpfr_cmp(lr, rr) == 0 && mpfr_cmp(li, ri) == 0;
4161       mpfr_clear(lr);
4162       mpfr_clear(li);
4163       mpfr_clear(rr);
4164       mpfr_clear(ri);
4165     }
4166   switch (op)
4167     {
4168     case OPERATOR_EQEQ:
4169       return is_equal;
4170     case OPERATOR_NOTEQ:
4171       return !is_equal;
4172     default:
4173       gcc_unreachable();
4174     }
4175 }
4176
4177 // Apply binary opcode OP to LEFT_VAL and RIGHT_VAL, setting VAL.
4178 // LEFT_TYPE is the type of LEFT_VAL, RIGHT_TYPE is the type of
4179 // RIGHT_VAL; LEFT_TYPE and/or RIGHT_TYPE may be NULL.  Return true if
4180 // this could be done, false if not.
4181
4182 bool
4183 Binary_expression::eval_integer(Operator op, Type* left_type, mpz_t left_val,
4184                                 Type* right_type, mpz_t right_val,
4185                                 source_location location, mpz_t val)
4186 {
4187   bool is_shift_op = false;
4188   switch (op)
4189     {
4190     case OPERATOR_OROR:
4191     case OPERATOR_ANDAND:
4192     case OPERATOR_EQEQ:
4193     case OPERATOR_NOTEQ:
4194     case OPERATOR_LT:
4195     case OPERATOR_LE:
4196     case OPERATOR_GT:
4197     case OPERATOR_GE:
4198       // These return boolean values.  We should probably handle them
4199       // anyhow in case a type conversion is used on the result.
4200       return false;
4201     case OPERATOR_PLUS:
4202       mpz_add(val, left_val, right_val);
4203       break;
4204     case OPERATOR_MINUS:
4205       mpz_sub(val, left_val, right_val);
4206       break;
4207     case OPERATOR_OR:
4208       mpz_ior(val, left_val, right_val);
4209       break;
4210     case OPERATOR_XOR:
4211       mpz_xor(val, left_val, right_val);
4212       break;
4213     case OPERATOR_MULT:
4214       mpz_mul(val, left_val, right_val);
4215       break;
4216     case OPERATOR_DIV:
4217       if (mpz_sgn(right_val) != 0)
4218         mpz_tdiv_q(val, left_val, right_val);
4219       else
4220         {
4221           error_at(location, "division by zero");
4222           mpz_set_ui(val, 0);
4223           return true;
4224         }
4225       break;
4226     case OPERATOR_MOD:
4227       if (mpz_sgn(right_val) != 0)
4228         mpz_tdiv_r(val, left_val, right_val);
4229       else
4230         {
4231           error_at(location, "division by zero");
4232           mpz_set_ui(val, 0);
4233           return true;
4234         }
4235       break;
4236     case OPERATOR_LSHIFT:
4237       {
4238         unsigned long shift = mpz_get_ui(right_val);
4239         if (mpz_cmp_ui(right_val, shift) != 0)
4240           {
4241             error_at(location, "shift count overflow");
4242             mpz_set_ui(val, 0);
4243             return true;
4244           }
4245         mpz_mul_2exp(val, left_val, shift);
4246         is_shift_op = true;
4247         break;
4248       }
4249       break;
4250     case OPERATOR_RSHIFT:
4251       {
4252         unsigned long shift = mpz_get_ui(right_val);
4253         if (mpz_cmp_ui(right_val, shift) != 0)
4254           {
4255             error_at(location, "shift count overflow");
4256             mpz_set_ui(val, 0);
4257             return true;
4258           }
4259         if (mpz_cmp_ui(left_val, 0) >= 0)
4260           mpz_tdiv_q_2exp(val, left_val, shift);
4261         else
4262           mpz_fdiv_q_2exp(val, left_val, shift);
4263         is_shift_op = true;
4264         break;
4265       }
4266       break;
4267     case OPERATOR_AND:
4268       mpz_and(val, left_val, right_val);
4269       break;
4270     case OPERATOR_BITCLEAR:
4271       {
4272         mpz_t tval;
4273         mpz_init(tval);
4274         mpz_com(tval, right_val);
4275         mpz_and(val, left_val, tval);
4276         mpz_clear(tval);
4277       }
4278       break;
4279     default:
4280       gcc_unreachable();
4281     }
4282
4283   Type* type = left_type;
4284   if (!is_shift_op)
4285     {
4286       if (type == NULL)
4287         type = right_type;
4288       else if (type != right_type && right_type != NULL)
4289         {
4290           if (type->is_abstract())
4291             type = right_type;
4292           else if (!right_type->is_abstract())
4293             {
4294               // This look like a type error which should be diagnosed
4295               // elsewhere.  Don't do anything here, to avoid an
4296               // unhelpful chain of error messages.
4297               return true;
4298             }
4299         }
4300     }
4301
4302   if (type != NULL && !type->is_abstract())
4303     {
4304       // We have to check the operands too, as we have implicitly
4305       // coerced them to TYPE.
4306       if ((type != left_type
4307            && !Integer_expression::check_constant(left_val, type, location))
4308           || (!is_shift_op
4309               && type != right_type
4310               && !Integer_expression::check_constant(right_val, type,
4311                                                      location))
4312           || !Integer_expression::check_constant(val, type, location))
4313         mpz_set_ui(val, 0);
4314     }
4315
4316   return true;
4317 }
4318
4319 // Apply binary opcode OP to LEFT_VAL and RIGHT_VAL, setting VAL.
4320 // Return true if this could be done, false if not.
4321
4322 bool
4323 Binary_expression::eval_float(Operator op, Type* left_type, mpfr_t left_val,
4324                               Type* right_type, mpfr_t right_val,
4325                               mpfr_t val, source_location location)
4326 {
4327   switch (op)
4328     {
4329     case OPERATOR_OROR:
4330     case OPERATOR_ANDAND:
4331     case OPERATOR_EQEQ:
4332     case OPERATOR_NOTEQ:
4333     case OPERATOR_LT:
4334     case OPERATOR_LE:
4335     case OPERATOR_GT:
4336     case OPERATOR_GE:
4337       // These return boolean values.  We should probably handle them
4338       // anyhow in case a type conversion is used on the result.
4339       return false;
4340     case OPERATOR_PLUS:
4341       mpfr_add(val, left_val, right_val, GMP_RNDN);
4342       break;
4343     case OPERATOR_MINUS:
4344       mpfr_sub(val, left_val, right_val, GMP_RNDN);
4345       break;
4346     case OPERATOR_OR:
4347     case OPERATOR_XOR:
4348     case OPERATOR_AND:
4349     case OPERATOR_BITCLEAR:
4350       return false;
4351     case OPERATOR_MULT:
4352       mpfr_mul(val, left_val, right_val, GMP_RNDN);
4353       break;
4354     case OPERATOR_DIV:
4355       if (mpfr_zero_p(right_val))
4356         error_at(location, "division by zero");
4357       mpfr_div(val, left_val, right_val, GMP_RNDN);
4358       break;
4359     case OPERATOR_MOD:
4360       return false;
4361     case OPERATOR_LSHIFT:
4362     case OPERATOR_RSHIFT:
4363       return false;
4364     default:
4365       gcc_unreachable();
4366     }
4367
4368   Type* type = left_type;
4369   if (type == NULL)
4370     type = right_type;
4371   else if (type != right_type && right_type != NULL)
4372     {
4373       if (type->is_abstract())
4374         type = right_type;
4375       else if (!right_type->is_abstract())
4376         {
4377           // This looks like a type error which should be diagnosed
4378           // elsewhere.  Don't do anything here, to avoid an unhelpful
4379           // chain of error messages.
4380           return true;
4381         }
4382     }
4383
4384   if (type != NULL && !type->is_abstract())
4385     {
4386       if ((type != left_type
4387            && !Float_expression::check_constant(left_val, type, location))
4388           || (type != right_type
4389               && !Float_expression::check_constant(right_val, type,
4390                                                    location))
4391           || !Float_expression::check_constant(val, type, location))
4392         mpfr_set_ui(val, 0, GMP_RNDN);
4393     }
4394
4395   return true;
4396 }
4397
4398 // Apply binary opcode OP to LEFT_REAL/LEFT_IMAG and
4399 // RIGHT_REAL/RIGHT_IMAG, setting REAL/IMAG.  Return true if this
4400 // could be done, false if not.
4401
4402 bool
4403 Binary_expression::eval_complex(Operator op, Type* left_type,
4404                                 mpfr_t left_real, mpfr_t left_imag,
4405                                 Type *right_type,
4406                                 mpfr_t right_real, mpfr_t right_imag,
4407                                 mpfr_t real, mpfr_t imag,
4408                                 source_location location)
4409 {
4410   switch (op)
4411     {
4412     case OPERATOR_OROR:
4413     case OPERATOR_ANDAND:
4414     case OPERATOR_EQEQ:
4415     case OPERATOR_NOTEQ:
4416     case OPERATOR_LT:
4417     case OPERATOR_LE:
4418     case OPERATOR_GT:
4419     case OPERATOR_GE:
4420       // These return boolean values and must be handled differently.
4421       return false;
4422     case OPERATOR_PLUS:
4423       mpfr_add(real, left_real, right_real, GMP_RNDN);
4424       mpfr_add(imag, left_imag, right_imag, GMP_RNDN);
4425       break;
4426     case OPERATOR_MINUS:
4427       mpfr_sub(real, left_real, right_real, GMP_RNDN);
4428       mpfr_sub(imag, left_imag, right_imag, GMP_RNDN);
4429       break;
4430     case OPERATOR_OR:
4431     case OPERATOR_XOR:
4432     case OPERATOR_AND:
4433     case OPERATOR_BITCLEAR:
4434       return false;
4435     case OPERATOR_MULT:
4436       {
4437         // You might think that multiplying two complex numbers would
4438         // be simple, and you would be right, until you start to think
4439         // about getting the right answer for infinity.  If one
4440         // operand here is infinity and the other is anything other
4441         // than zero or NaN, then we are going to wind up subtracting
4442         // two infinity values.  That will give us a NaN, but the
4443         // correct answer is infinity.
4444
4445         mpfr_t lrrr;
4446         mpfr_init(lrrr);
4447         mpfr_mul(lrrr, left_real, right_real, GMP_RNDN);
4448
4449         mpfr_t lrri;
4450         mpfr_init(lrri);
4451         mpfr_mul(lrri, left_real, right_imag, GMP_RNDN);
4452
4453         mpfr_t lirr;
4454         mpfr_init(lirr);
4455         mpfr_mul(lirr, left_imag, right_real, GMP_RNDN);
4456
4457         mpfr_t liri;
4458         mpfr_init(liri);
4459         mpfr_mul(liri, left_imag, right_imag, GMP_RNDN);
4460
4461         mpfr_sub(real, lrrr, liri, GMP_RNDN);
4462         mpfr_add(imag, lrri, lirr, GMP_RNDN);
4463
4464         // If we get NaN on both sides, check whether it should really
4465         // be infinity.  The rule is that if either side of the
4466         // complex number is infinity, then the whole value is
4467         // infinity, even if the other side is NaN.  So the only case
4468         // we have to fix is the one in which both sides are NaN.
4469         if (mpfr_nan_p(real) && mpfr_nan_p(imag)
4470             && (!mpfr_nan_p(left_real) || !mpfr_nan_p(left_imag))
4471             && (!mpfr_nan_p(right_real) || !mpfr_nan_p(right_imag)))
4472           {
4473             bool is_infinity = false;
4474
4475             mpfr_t lr;
4476             mpfr_t li;
4477             mpfr_init_set(lr, left_real, GMP_RNDN);
4478             mpfr_init_set(li, left_imag, GMP_RNDN);
4479
4480             mpfr_t rr;
4481             mpfr_t ri;
4482             mpfr_init_set(rr, right_real, GMP_RNDN);
4483             mpfr_init_set(ri, right_imag, GMP_RNDN);
4484
4485             // If the left side is infinity, then the result is
4486             // infinity.
4487             if (mpfr_inf_p(lr) || mpfr_inf_p(li))
4488               {
4489                 mpfr_set_ui(lr, mpfr_inf_p(lr) ? 1 : 0, GMP_RNDN);
4490                 mpfr_copysign(lr, lr, left_real, GMP_RNDN);
4491                 mpfr_set_ui(li, mpfr_inf_p(li) ? 1 : 0, GMP_RNDN);
4492                 mpfr_copysign(li, li, left_imag, GMP_RNDN);
4493                 if (mpfr_nan_p(rr))
4494                   {
4495                     mpfr_set_ui(rr, 0, GMP_RNDN);
4496                     mpfr_copysign(rr, rr, right_real, GMP_RNDN);
4497                   }
4498                 if (mpfr_nan_p(ri))
4499                   {
4500                     mpfr_set_ui(ri, 0, GMP_RNDN);
4501                     mpfr_copysign(ri, ri, right_imag, GMP_RNDN);
4502                   }
4503                 is_infinity = true;
4504               }
4505
4506             // If the right side is infinity, then the result is
4507             // infinity.
4508             if (mpfr_inf_p(rr) || mpfr_inf_p(ri))
4509               {
4510                 mpfr_set_ui(rr, mpfr_inf_p(rr) ? 1 : 0, GMP_RNDN);
4511                 mpfr_copysign(rr, rr, right_real, GMP_RNDN);
4512                 mpfr_set_ui(ri, mpfr_inf_p(ri) ? 1 : 0, GMP_RNDN);
4513                 mpfr_copysign(ri, ri, right_imag, GMP_RNDN);
4514                 if (mpfr_nan_p(lr))
4515                   {
4516                     mpfr_set_ui(lr, 0, GMP_RNDN);
4517                     mpfr_copysign(lr, lr, left_real, GMP_RNDN);
4518                   }
4519                 if (mpfr_nan_p(li))
4520                   {
4521                     mpfr_set_ui(li, 0, GMP_RNDN);
4522                     mpfr_copysign(li, li, left_imag, GMP_RNDN);
4523                   }
4524                 is_infinity = true;
4525               }
4526
4527             // If we got an overflow in the intermediate computations,
4528             // then the result is infinity.
4529             if (!is_infinity
4530                 && (mpfr_inf_p(lrrr) || mpfr_inf_p(lrri)
4531                     || mpfr_inf_p(lirr) || mpfr_inf_p(liri)))
4532               {
4533                 if (mpfr_nan_p(lr))
4534                   {
4535                     mpfr_set_ui(lr, 0, GMP_RNDN);
4536                     mpfr_copysign(lr, lr, left_real, GMP_RNDN);
4537                   }
4538                 if (mpfr_nan_p(li))
4539                   {
4540                     mpfr_set_ui(li, 0, GMP_RNDN);
4541                     mpfr_copysign(li, li, left_imag, GMP_RNDN);
4542                   }
4543                 if (mpfr_nan_p(rr))
4544                   {
4545                     mpfr_set_ui(rr, 0, GMP_RNDN);
4546                     mpfr_copysign(rr, rr, right_real, GMP_RNDN);
4547                   }
4548                 if (mpfr_nan_p(ri))
4549                   {
4550                     mpfr_set_ui(ri, 0, GMP_RNDN);
4551                     mpfr_copysign(ri, ri, right_imag, GMP_RNDN);
4552                   }
4553                 is_infinity = true;
4554               }
4555
4556             if (is_infinity)
4557               {
4558                 mpfr_mul(lrrr, lr, rr, GMP_RNDN);
4559                 mpfr_mul(lrri, lr, ri, GMP_RNDN);
4560                 mpfr_mul(lirr, li, rr, GMP_RNDN);
4561                 mpfr_mul(liri, li, ri, GMP_RNDN);
4562                 mpfr_sub(real, lrrr, liri, GMP_RNDN);
4563                 mpfr_add(imag, lrri, lirr, GMP_RNDN);
4564                 mpfr_set_inf(real, mpfr_sgn(real));
4565                 mpfr_set_inf(imag, mpfr_sgn(imag));
4566               }
4567
4568             mpfr_clear(lr);
4569             mpfr_clear(li);
4570             mpfr_clear(rr);
4571             mpfr_clear(ri);
4572           }
4573
4574         mpfr_clear(lrrr);
4575         mpfr_clear(lrri);
4576         mpfr_clear(lirr);
4577         mpfr_clear(liri);
4578       }
4579       break;
4580     case OPERATOR_DIV:
4581       {
4582         // For complex division we want to avoid having an
4583         // intermediate overflow turn the whole result in a NaN.  We
4584         // scale the values to try to avoid this.
4585
4586         if (mpfr_zero_p(right_real) && mpfr_zero_p(right_imag))
4587           error_at(location, "division by zero");
4588
4589         mpfr_t rra;
4590         mpfr_t ria;
4591         mpfr_init(rra);
4592         mpfr_init(ria);
4593         mpfr_abs(rra, right_real, GMP_RNDN);
4594         mpfr_abs(ria, right_imag, GMP_RNDN);
4595         mpfr_t t;
4596         mpfr_init(t);
4597         mpfr_max(t, rra, ria, GMP_RNDN);
4598
4599         mpfr_t rr;
4600         mpfr_t ri;
4601         mpfr_init_set(rr, right_real, GMP_RNDN);
4602         mpfr_init_set(ri, right_imag, GMP_RNDN);
4603         long ilogbw = 0;
4604         if (!mpfr_inf_p(t) && !mpfr_nan_p(t) && !mpfr_zero_p(t))
4605           {
4606             ilogbw = mpfr_get_exp(t);
4607             mpfr_mul_2si(rr, rr, - ilogbw, GMP_RNDN);
4608             mpfr_mul_2si(ri, ri, - ilogbw, GMP_RNDN);
4609           }
4610
4611         mpfr_t denom;
4612         mpfr_init(denom);
4613         mpfr_mul(denom, rr, rr, GMP_RNDN);
4614         mpfr_mul(t, ri, ri, GMP_RNDN);
4615         mpfr_add(denom, denom, t, GMP_RNDN);
4616
4617         mpfr_mul(real, left_real, rr, GMP_RNDN);
4618         mpfr_mul(t, left_imag, ri, GMP_RNDN);
4619         mpfr_add(real, real, t, GMP_RNDN);
4620         mpfr_div(real, real, denom, GMP_RNDN);
4621         mpfr_mul_2si(real, real, - ilogbw, GMP_RNDN);
4622
4623         mpfr_mul(imag, left_imag, rr, GMP_RNDN);
4624         mpfr_mul(t, left_real, ri, GMP_RNDN);
4625         mpfr_sub(imag, imag, t, GMP_RNDN);
4626         mpfr_div(imag, imag, denom, GMP_RNDN);
4627         mpfr_mul_2si(imag, imag, - ilogbw, GMP_RNDN);
4628
4629         // If we wind up with NaN on both sides, check whether we
4630         // should really have infinity.  The rule is that if either
4631         // side of the complex number is infinity, then the whole
4632         // value is infinity, even if the other side is NaN.  So the
4633         // only case we have to fix is the one in which both sides are
4634         // NaN.
4635         if (mpfr_nan_p(real) && mpfr_nan_p(imag)
4636             && (!mpfr_nan_p(left_real) || !mpfr_nan_p(left_imag))
4637             && (!mpfr_nan_p(right_real) || !mpfr_nan_p(right_imag)))
4638           {
4639             if (mpfr_zero_p(denom))
4640               {
4641                 mpfr_set_inf(real, mpfr_sgn(rr));
4642                 mpfr_mul(real, real, left_real, GMP_RNDN);
4643                 mpfr_set_inf(imag, mpfr_sgn(rr));
4644                 mpfr_mul(imag, imag, left_imag, GMP_RNDN);
4645               }
4646             else if ((mpfr_inf_p(left_real) || mpfr_inf_p(left_imag))
4647                      && mpfr_number_p(rr) && mpfr_number_p(ri))
4648               {
4649                 mpfr_set_ui(t, mpfr_inf_p(left_real) ? 1 : 0, GMP_RNDN);
4650                 mpfr_copysign(t, t, left_real, GMP_RNDN);
4651
4652                 mpfr_t t2;
4653                 mpfr_init_set_ui(t2, mpfr_inf_p(left_imag) ? 1 : 0, GMP_RNDN);
4654                 mpfr_copysign(t2, t2, left_imag, GMP_RNDN);
4655
4656                 mpfr_t t3;
4657                 mpfr_init(t3);
4658                 mpfr_mul(t3, t, rr, GMP_RNDN);
4659
4660                 mpfr_t t4;
4661                 mpfr_init(t4);
4662                 mpfr_mul(t4, t2, ri, GMP_RNDN);
4663
4664                 mpfr_add(t3, t3, t4, GMP_RNDN);
4665                 mpfr_set_inf(real, mpfr_sgn(t3));
4666
4667                 mpfr_mul(t3, t2, rr, GMP_RNDN);
4668                 mpfr_mul(t4, t, ri, GMP_RNDN);
4669                 mpfr_sub(t3, t3, t4, GMP_RNDN);
4670                 mpfr_set_inf(imag, mpfr_sgn(t3));
4671
4672                 mpfr_clear(t2);
4673                 mpfr_clear(t3);
4674                 mpfr_clear(t4);
4675               }
4676             else if ((mpfr_inf_p(right_real) || mpfr_inf_p(right_imag))
4677                      && mpfr_number_p(left_real) && mpfr_number_p(left_imag))
4678               {
4679                 mpfr_set_ui(t, mpfr_inf_p(rr) ? 1 : 0, GMP_RNDN);
4680                 mpfr_copysign(t, t, rr, GMP_RNDN);
4681
4682                 mpfr_t t2;
4683                 mpfr_init_set_ui(t2, mpfr_inf_p(ri) ? 1 : 0, GMP_RNDN);
4684                 mpfr_copysign(t2, t2, ri, GMP_RNDN);
4685
4686                 mpfr_t t3;
4687                 mpfr_init(t3);
4688                 mpfr_mul(t3, left_real, t, GMP_RNDN);
4689
4690                 mpfr_t t4;
4691                 mpfr_init(t4);
4692                 mpfr_mul(t4, left_imag, t2, GMP_RNDN);
4693
4694                 mpfr_add(t3, t3, t4, GMP_RNDN);
4695                 mpfr_set_ui(real, 0, GMP_RNDN);
4696                 mpfr_mul(real, real, t3, GMP_RNDN);
4697
4698                 mpfr_mul(t3, left_imag, t, GMP_RNDN);
4699                 mpfr_mul(t4, left_real, t2, GMP_RNDN);
4700                 mpfr_sub(t3, t3, t4, GMP_RNDN);
4701                 mpfr_set_ui(imag, 0, GMP_RNDN);
4702                 mpfr_mul(imag, imag, t3, GMP_RNDN);
4703
4704                 mpfr_clear(t2);
4705                 mpfr_clear(t3);
4706                 mpfr_clear(t4);
4707               }
4708           }
4709
4710         mpfr_clear(denom);
4711         mpfr_clear(rr);
4712         mpfr_clear(ri);
4713         mpfr_clear(t);
4714         mpfr_clear(rra);
4715         mpfr_clear(ria);
4716       }
4717       break;
4718     case OPERATOR_MOD:
4719       return false;
4720     case OPERATOR_LSHIFT:
4721     case OPERATOR_RSHIFT:
4722       return false;
4723     default:
4724       gcc_unreachable();
4725     }
4726
4727   Type* type = left_type;
4728   if (type == NULL)
4729     type = right_type;
4730   else if (type != right_type && right_type != NULL)
4731     {
4732       if (type->is_abstract())
4733         type = right_type;
4734       else if (!right_type->is_abstract())
4735         {
4736           // This looks like a type error which should be diagnosed
4737           // elsewhere.  Don't do anything here, to avoid an unhelpful
4738           // chain of error messages.
4739           return true;
4740         }
4741     }
4742
4743   if (type != NULL && !type->is_abstract())
4744     {
4745       if ((type != left_type
4746            && !Complex_expression::check_constant(left_real, left_imag,
4747                                                   type, location))
4748           || (type != right_type
4749               && !Complex_expression::check_constant(right_real, right_imag,
4750                                                      type, location))
4751           || !Complex_expression::check_constant(real, imag, type,
4752                                                  location))
4753         {
4754           mpfr_set_ui(real, 0, GMP_RNDN);
4755           mpfr_set_ui(imag, 0, GMP_RNDN);
4756         }
4757     }
4758
4759   return true;
4760 }
4761
4762 // Lower a binary expression.  We have to evaluate constant
4763 // expressions now, in order to implement Go's unlimited precision
4764 // constants.
4765
4766 Expression*
4767 Binary_expression::do_lower(Gogo*, Named_object*, int)
4768 {
4769   source_location location = this->location();
4770   Operator op = this->op_;
4771   Expression* left = this->left_;
4772   Expression* right = this->right_;
4773
4774   const bool is_comparison = (op == OPERATOR_EQEQ
4775                               || op == OPERATOR_NOTEQ
4776                               || op == OPERATOR_LT
4777                               || op == OPERATOR_LE
4778                               || op == OPERATOR_GT
4779                               || op == OPERATOR_GE);
4780
4781   // Integer constant expressions.
4782   {
4783     mpz_t left_val;
4784     mpz_init(left_val);
4785     Type* left_type;
4786     mpz_t right_val;
4787     mpz_init(right_val);
4788     Type* right_type;
4789     if (left->integer_constant_value(false, left_val, &left_type)
4790         && right->integer_constant_value(false, right_val, &right_type))
4791       {
4792         Expression* ret = NULL;
4793         if (left_type != right_type
4794             && left_type != NULL
4795             && right_type != NULL
4796             && left_type->base() != right_type->base()
4797             && op != OPERATOR_LSHIFT
4798             && op != OPERATOR_RSHIFT)
4799           {
4800             // May be a type error--let it be diagnosed later.
4801           }
4802         else if (is_comparison)
4803           {
4804             bool b = Binary_expression::compare_integer(op, left_val,
4805                                                         right_val);
4806             ret = Expression::make_cast(Type::lookup_bool_type(),
4807                                         Expression::make_boolean(b, location),
4808                                         location);
4809           }
4810         else
4811           {
4812             mpz_t val;
4813             mpz_init(val);
4814
4815             if (Binary_expression::eval_integer(op, left_type, left_val,
4816                                                 right_type, right_val,
4817                                                 location, val))
4818               {
4819                 gcc_assert(op != OPERATOR_OROR && op != OPERATOR_ANDAND);
4820                 Type* type;
4821                 if (op == OPERATOR_LSHIFT || op == OPERATOR_RSHIFT)
4822                   type = left_type;
4823                 else if (left_type == NULL)
4824                   type = right_type;
4825                 else if (right_type == NULL)
4826                   type = left_type;
4827                 else if (!left_type->is_abstract()
4828                          && left_type->named_type() != NULL)
4829                   type = left_type;
4830                 else if (!right_type->is_abstract()
4831                          && right_type->named_type() != NULL)
4832                   type = right_type;
4833                 else if (!left_type->is_abstract())
4834                   type = left_type;
4835                 else if (!right_type->is_abstract())
4836                   type = right_type;
4837                 else if (left_type->float_type() != NULL)
4838                   type = left_type;
4839                 else if (right_type->float_type() != NULL)
4840                   type = right_type;
4841                 else if (left_type->complex_type() != NULL)
4842                   type = left_type;
4843                 else if (right_type->complex_type() != NULL)
4844                   type = right_type;
4845                 else
4846                   type = left_type;
4847                 ret = Expression::make_integer(&val, type, location);
4848               }
4849
4850             mpz_clear(val);
4851           }
4852
4853         if (ret != NULL)
4854           {
4855             mpz_clear(right_val);
4856             mpz_clear(left_val);
4857             return ret;
4858           }
4859       }
4860     mpz_clear(right_val);
4861     mpz_clear(left_val);
4862   }
4863
4864   // Floating point constant expressions.
4865   {
4866     mpfr_t left_val;
4867     mpfr_init(left_val);
4868     Type* left_type;
4869     mpfr_t right_val;
4870     mpfr_init(right_val);
4871     Type* right_type;
4872     if (left->float_constant_value(left_val, &left_type)
4873         && right->float_constant_value(right_val, &right_type))
4874       {
4875         Expression* ret = NULL;
4876         if (left_type != right_type
4877             && left_type != NULL
4878             && right_type != NULL
4879             && left_type->base() != right_type->base()
4880             && op != OPERATOR_LSHIFT
4881             && op != OPERATOR_RSHIFT)
4882           {
4883             // May be a type error--let it be diagnosed later.
4884           }
4885         else if (is_comparison)
4886           {
4887             bool b = Binary_expression::compare_float(op,
4888                                                       (left_type != NULL
4889                                                        ? left_type
4890                                                        : right_type),
4891                                                       left_val, right_val);
4892             ret = Expression::make_boolean(b, location);
4893           }
4894         else
4895           {
4896             mpfr_t val;
4897             mpfr_init(val);
4898
4899             if (Binary_expression::eval_float(op, left_type, left_val,
4900                                               right_type, right_val, val,
4901                                               location))
4902               {
4903                 gcc_assert(op != OPERATOR_OROR && op != OPERATOR_ANDAND
4904                            && op != OPERATOR_LSHIFT && op != OPERATOR_RSHIFT);
4905                 Type* type;
4906                 if (left_type == NULL)
4907                   type = right_type;
4908                 else if (right_type == NULL)
4909                   type = left_type;
4910                 else if (!left_type->is_abstract()
4911                          && left_type->named_type() != NULL)
4912                   type = left_type;
4913                 else if (!right_type->is_abstract()
4914                          && right_type->named_type() != NULL)
4915                   type = right_type;
4916                 else if (!left_type->is_abstract())
4917                   type = left_type;
4918                 else if (!right_type->is_abstract())
4919                   type = right_type;
4920                 else if (left_type->float_type() != NULL)
4921                   type = left_type;
4922                 else if (right_type->float_type() != NULL)
4923                   type = right_type;
4924                 else
4925                   type = left_type;
4926                 ret = Expression::make_float(&val, type, location);
4927               }
4928
4929             mpfr_clear(val);
4930           }
4931
4932         if (ret != NULL)
4933           {
4934             mpfr_clear(right_val);
4935             mpfr_clear(left_val);
4936             return ret;
4937           }
4938       }
4939     mpfr_clear(right_val);
4940     mpfr_clear(left_val);
4941   }
4942
4943   // Complex constant expressions.
4944   {
4945     mpfr_t left_real;
4946     mpfr_t left_imag;
4947     mpfr_init(left_real);
4948     mpfr_init(left_imag);
4949     Type* left_type;
4950
4951     mpfr_t right_real;
4952     mpfr_t right_imag;
4953     mpfr_init(right_real);
4954     mpfr_init(right_imag);
4955     Type* right_type;
4956
4957     if (left->complex_constant_value(left_real, left_imag, &left_type)
4958         && right->complex_constant_value(right_real, right_imag, &right_type))
4959       {
4960         Expression* ret = NULL;
4961         if (left_type != right_type
4962             && left_type != NULL
4963             && right_type != NULL
4964             && left_type->base() != right_type->base())
4965           {
4966             // May be a type error--let it be diagnosed later.
4967           }
4968         else if (is_comparison)
4969           {
4970             bool b = Binary_expression::compare_complex(op,
4971                                                         (left_type != NULL
4972                                                          ? left_type
4973                                                          : right_type),
4974                                                         left_real,
4975                                                         left_imag,
4976                                                         right_real,
4977                                                         right_imag);
4978             ret = Expression::make_boolean(b, location);
4979           }
4980         else
4981           {
4982             mpfr_t real;
4983             mpfr_t imag;
4984             mpfr_init(real);
4985             mpfr_init(imag);
4986
4987             if (Binary_expression::eval_complex(op, left_type,
4988                                                 left_real, left_imag,
4989                                                 right_type,
4990                                                 right_real, right_imag,
4991                                                 real, imag,
4992                                                 location))
4993               {
4994                 gcc_assert(op != OPERATOR_OROR && op != OPERATOR_ANDAND
4995                            && op != OPERATOR_LSHIFT && op != OPERATOR_RSHIFT);
4996                 Type* type;
4997                 if (left_type == NULL)
4998                   type = right_type;
4999                 else if (right_type == NULL)
5000                   type = left_type;
5001                 else if (!left_type->is_abstract()
5002                          && left_type->named_type() != NULL)
5003                   type = left_type;
5004                 else if (!right_type->is_abstract()
5005                          && right_type->named_type() != NULL)
5006                   type = right_type;
5007                 else if (!left_type->is_abstract())
5008                   type = left_type;
5009                 else if (!right_type->is_abstract())
5010                   type = right_type;
5011                 else if (left_type->complex_type() != NULL)
5012                   type = left_type;
5013                 else if (right_type->complex_type() != NULL)
5014                   type = right_type;
5015                 else
5016                   type = left_type;
5017                 ret = Expression::make_complex(&real, &imag, type,
5018                                                location);
5019               }
5020             mpfr_clear(real);
5021             mpfr_clear(imag);
5022           }
5023
5024         if (ret != NULL)
5025           {
5026             mpfr_clear(left_real);
5027             mpfr_clear(left_imag);
5028             mpfr_clear(right_real);
5029             mpfr_clear(right_imag);
5030             return ret;
5031           }
5032       }
5033
5034     mpfr_clear(left_real);
5035     mpfr_clear(left_imag);
5036     mpfr_clear(right_real);
5037     mpfr_clear(right_imag);
5038   }
5039
5040   // String constant expressions.
5041   if (op == OPERATOR_PLUS
5042       && left->type()->is_string_type()
5043       && right->type()->is_string_type())
5044     {
5045       std::string left_string;
5046       std::string right_string;
5047       if (left->string_constant_value(&left_string)
5048           && right->string_constant_value(&right_string))
5049         return Expression::make_string(left_string + right_string, location);
5050     }
5051
5052   return this;
5053 }
5054
5055 // Return the integer constant value, if it has one.
5056
5057 bool
5058 Binary_expression::do_integer_constant_value(bool iota_is_constant, mpz_t val,
5059                                              Type** ptype) const
5060 {
5061   mpz_t left_val;
5062   mpz_init(left_val);
5063   Type* left_type;
5064   if (!this->left_->integer_constant_value(iota_is_constant, left_val,
5065                                            &left_type))
5066     {
5067       mpz_clear(left_val);
5068       return false;
5069     }
5070
5071   mpz_t right_val;
5072   mpz_init(right_val);
5073   Type* right_type;
5074   if (!this->right_->integer_constant_value(iota_is_constant, right_val,
5075                                             &right_type))
5076     {
5077       mpz_clear(right_val);
5078       mpz_clear(left_val);
5079       return false;
5080     }
5081
5082   bool ret;
5083   if (left_type != right_type
5084       && left_type != NULL
5085       && right_type != NULL
5086       && left_type->base() != right_type->base()
5087       && this->op_ != OPERATOR_RSHIFT
5088       && this->op_ != OPERATOR_LSHIFT)
5089     ret = false;
5090   else
5091     ret = Binary_expression::eval_integer(this->op_, left_type, left_val,
5092                                           right_type, right_val,
5093                                           this->location(), val);
5094
5095   mpz_clear(right_val);
5096   mpz_clear(left_val);
5097
5098   if (ret)
5099     *ptype = left_type;
5100
5101   return ret;
5102 }
5103
5104 // Return the floating point constant value, if it has one.
5105
5106 bool
5107 Binary_expression::do_float_constant_value(mpfr_t val, Type** ptype) const
5108 {
5109   mpfr_t left_val;
5110   mpfr_init(left_val);
5111   Type* left_type;
5112   if (!this->left_->float_constant_value(left_val, &left_type))
5113     {
5114       mpfr_clear(left_val);
5115       return false;
5116     }
5117
5118   mpfr_t right_val;
5119   mpfr_init(right_val);
5120   Type* right_type;
5121   if (!this->right_->float_constant_value(right_val, &right_type))
5122     {
5123       mpfr_clear(right_val);
5124       mpfr_clear(left_val);
5125       return false;
5126     }
5127
5128   bool ret;
5129   if (left_type != right_type
5130       && left_type != NULL
5131       && right_type != NULL
5132       && left_type->base() != right_type->base())
5133     ret = false;
5134   else
5135     ret = Binary_expression::eval_float(this->op_, left_type, left_val,
5136                                         right_type, right_val,
5137                                         val, this->location());
5138
5139   mpfr_clear(left_val);
5140   mpfr_clear(right_val);
5141
5142   if (ret)
5143     *ptype = left_type;
5144
5145   return ret;
5146 }
5147
5148 // Return the complex constant value, if it has one.
5149
5150 bool
5151 Binary_expression::do_complex_constant_value(mpfr_t real, mpfr_t imag,
5152                                              Type** ptype) const
5153 {
5154   mpfr_t left_real;
5155   mpfr_t left_imag;
5156   mpfr_init(left_real);
5157   mpfr_init(left_imag);
5158   Type* left_type;
5159   if (!this->left_->complex_constant_value(left_real, left_imag, &left_type))
5160     {
5161       mpfr_clear(left_real);
5162       mpfr_clear(left_imag);
5163       return false;
5164     }
5165
5166   mpfr_t right_real;
5167   mpfr_t right_imag;
5168   mpfr_init(right_real);
5169   mpfr_init(right_imag);
5170   Type* right_type;
5171   if (!this->right_->complex_constant_value(right_real, right_imag,
5172                                             &right_type))
5173     {
5174       mpfr_clear(left_real);
5175       mpfr_clear(left_imag);
5176       mpfr_clear(right_real);
5177       mpfr_clear(right_imag);
5178       return false;
5179     }
5180
5181   bool ret;
5182   if (left_type != right_type
5183       && left_type != NULL
5184       && right_type != NULL
5185       && left_type->base() != right_type->base())
5186     ret = false;
5187   else
5188     ret = Binary_expression::eval_complex(this->op_, left_type,
5189                                           left_real, left_imag,
5190                                           right_type,
5191                                           right_real, right_imag,
5192                                           real, imag,
5193                                           this->location());
5194   mpfr_clear(left_real);
5195   mpfr_clear(left_imag);
5196   mpfr_clear(right_real);
5197   mpfr_clear(right_imag);
5198
5199   if (ret)
5200     *ptype = left_type;
5201
5202   return ret;
5203 }
5204
5205 // Note that the value is being discarded.
5206
5207 void
5208 Binary_expression::do_discarding_value()
5209 {
5210   if (this->op_ == OPERATOR_OROR || this->op_ == OPERATOR_ANDAND)
5211     this->right_->discarding_value();
5212   else
5213     this->warn_about_unused_value();
5214 }
5215
5216 // Get type.
5217
5218 Type*
5219 Binary_expression::do_type()
5220 {
5221   switch (this->op_)
5222     {
5223     case OPERATOR_OROR:
5224     case OPERATOR_ANDAND:
5225     case OPERATOR_EQEQ:
5226     case OPERATOR_NOTEQ:
5227     case OPERATOR_LT:
5228     case OPERATOR_LE:
5229     case OPERATOR_GT:
5230     case OPERATOR_GE:
5231       return Type::lookup_bool_type();
5232
5233     case OPERATOR_PLUS:
5234     case OPERATOR_MINUS:
5235     case OPERATOR_OR:
5236     case OPERATOR_XOR:
5237     case OPERATOR_MULT:
5238     case OPERATOR_DIV:
5239     case OPERATOR_MOD:
5240     case OPERATOR_AND:
5241     case OPERATOR_BITCLEAR:
5242       {
5243         Type* left_type = this->left_->type();
5244         Type* right_type = this->right_->type();
5245         if (!left_type->is_abstract() && left_type->named_type() != NULL)
5246           return left_type;
5247         else if (!right_type->is_abstract() && right_type->named_type() != NULL)
5248           return right_type;
5249         else if (!left_type->is_abstract())
5250           return left_type;
5251         else if (!right_type->is_abstract())
5252           return right_type;
5253         else if (left_type->complex_type() != NULL)
5254           return left_type;
5255         else if (right_type->complex_type() != NULL)
5256           return right_type;
5257         else if (left_type->float_type() != NULL)
5258           return left_type;
5259         else if (right_type->float_type() != NULL)
5260           return right_type;
5261         else
5262           return left_type;
5263       }
5264
5265     case OPERATOR_LSHIFT:
5266     case OPERATOR_RSHIFT:
5267       return this->left_->type();
5268
5269     default:
5270       gcc_unreachable();
5271     }
5272 }
5273
5274 // Set type for a binary expression.
5275
5276 void
5277 Binary_expression::do_determine_type(const Type_context* context)
5278 {
5279   Type* tleft = this->left_->type();
5280   Type* tright = this->right_->type();
5281
5282   // Both sides should have the same type, except for the shift
5283   // operations.  For a comparison, we should ignore the incoming
5284   // type.
5285
5286   bool is_shift_op = (this->op_ == OPERATOR_LSHIFT
5287                       || this->op_ == OPERATOR_RSHIFT);
5288
5289   bool is_comparison = (this->op_ == OPERATOR_EQEQ
5290                         || this->op_ == OPERATOR_NOTEQ
5291                         || this->op_ == OPERATOR_LT
5292                         || this->op_ == OPERATOR_LE
5293                         || this->op_ == OPERATOR_GT
5294                         || this->op_ == OPERATOR_GE);
5295
5296   Type_context subcontext(*context);
5297
5298   if (is_comparison)
5299     {
5300       // In a comparison, the context does not determine the types of
5301       // the operands.
5302       subcontext.type = NULL;
5303     }
5304
5305   // Set the context for the left hand operand.
5306   if (is_shift_op)
5307     {
5308       // The right hand operand plays no role in determining the type
5309       // of the left hand operand.  A shift of an abstract integer in
5310       // a string context gets special treatment, which may be a
5311       // language bug.
5312       if (subcontext.type != NULL
5313           && subcontext.type->is_string_type()
5314           && tleft->is_abstract())
5315         error_at(this->location(), "shift of non-integer operand");
5316     }
5317   else if (!tleft->is_abstract())
5318     subcontext.type = tleft;
5319   else if (!tright->is_abstract())
5320     subcontext.type = tright;
5321   else if (subcontext.type == NULL)
5322     {
5323       if ((tleft->integer_type() != NULL && tright->integer_type() != NULL)
5324           || (tleft->float_type() != NULL && tright->float_type() != NULL)
5325           || (tleft->complex_type() != NULL && tright->complex_type() != NULL))
5326         {
5327           // Both sides have an abstract integer, abstract float, or
5328           // abstract complex type.  Just let CONTEXT determine
5329           // whether they may remain abstract or not.
5330         }
5331       else if (tleft->complex_type() != NULL)
5332         subcontext.type = tleft;
5333       else if (tright->complex_type() != NULL)
5334         subcontext.type = tright;
5335       else if (tleft->float_type() != NULL)
5336         subcontext.type = tleft;
5337       else if (tright->float_type() != NULL)
5338         subcontext.type = tright;
5339       else
5340         subcontext.type = tleft;
5341     }
5342
5343   this->left_->determine_type(&subcontext);
5344
5345   // The context for the right hand operand is the same as for the
5346   // left hand operand, except for a shift operator.
5347   if (is_shift_op)
5348     {
5349       subcontext.type = Type::lookup_integer_type("uint");
5350       subcontext.may_be_abstract = false;
5351     }
5352
5353   this->right_->determine_type(&subcontext);
5354 }
5355
5356 // Report an error if the binary operator OP does not support TYPE.
5357 // Return whether the operation is OK.  This should not be used for
5358 // shift.
5359
5360 bool
5361 Binary_expression::check_operator_type(Operator op, Type* type,
5362                                        source_location location)
5363 {
5364   switch (op)
5365     {
5366     case OPERATOR_OROR:
5367     case OPERATOR_ANDAND:
5368       if (!type->is_boolean_type())
5369         {
5370           error_at(location, "expected boolean type");
5371           return false;
5372         }
5373       break;
5374
5375     case OPERATOR_EQEQ:
5376     case OPERATOR_NOTEQ:
5377       if (type->integer_type() == NULL
5378           && type->float_type() == NULL
5379           && type->complex_type() == NULL
5380           && !type->is_string_type()
5381           && type->points_to() == NULL
5382           && !type->is_nil_type()
5383           && !type->is_boolean_type()
5384           && type->interface_type() == NULL
5385           && (type->array_type() == NULL
5386               || type->array_type()->length() != NULL)
5387           && type->map_type() == NULL
5388           && type->channel_type() == NULL
5389           && type->function_type() == NULL)
5390         {
5391           error_at(location,
5392                    ("expected integer, floating, complex, string, pointer, "
5393                     "boolean, interface, slice, map, channel, "
5394                     "or function type"));
5395           return false;
5396         }
5397       break;
5398
5399     case OPERATOR_LT:
5400     case OPERATOR_LE:
5401     case OPERATOR_GT:
5402     case OPERATOR_GE:
5403       if (type->integer_type() == NULL
5404           && type->float_type() == NULL
5405           && !type->is_string_type())
5406         {
5407           error_at(location, "expected integer, floating, or string type");
5408           return false;
5409         }
5410       break;
5411
5412     case OPERATOR_PLUS:
5413     case OPERATOR_PLUSEQ:
5414       if (type->integer_type() == NULL
5415           && type->float_type() == NULL
5416           && type->complex_type() == NULL
5417           && !type->is_string_type())
5418         {
5419           error_at(location,
5420                    "expected integer, floating, complex, or string type");
5421           return false;
5422         }
5423       break;
5424
5425     case OPERATOR_MINUS:
5426     case OPERATOR_MINUSEQ:
5427     case OPERATOR_MULT:
5428     case OPERATOR_MULTEQ:
5429     case OPERATOR_DIV:
5430     case OPERATOR_DIVEQ:
5431       if (type->integer_type() == NULL
5432           && type->float_type() == NULL
5433           && type->complex_type() == NULL)
5434         {
5435           error_at(location, "expected integer, floating, or complex type");
5436           return false;
5437         }
5438       break;
5439
5440     case OPERATOR_MOD:
5441     case OPERATOR_MODEQ:
5442     case OPERATOR_OR:
5443     case OPERATOR_OREQ:
5444     case OPERATOR_AND:
5445     case OPERATOR_ANDEQ:
5446     case OPERATOR_XOR:
5447     case OPERATOR_XOREQ:
5448     case OPERATOR_BITCLEAR:
5449     case OPERATOR_BITCLEAREQ:
5450       if (type->integer_type() == NULL)
5451         {
5452           error_at(location, "expected integer type");
5453           return false;
5454         }
5455       break;
5456
5457     default:
5458       gcc_unreachable();
5459     }
5460
5461   return true;
5462 }
5463
5464 // Check types.
5465
5466 void
5467 Binary_expression::do_check_types(Gogo*)
5468 {
5469   Type* left_type = this->left_->type();
5470   Type* right_type = this->right_->type();
5471   if (left_type->is_error_type() || right_type->is_error_type())
5472     {
5473       this->set_is_error();
5474       return;
5475     }
5476
5477   if (this->op_ == OPERATOR_EQEQ
5478       || this->op_ == OPERATOR_NOTEQ
5479       || this->op_ == OPERATOR_LT
5480       || this->op_ == OPERATOR_LE
5481       || this->op_ == OPERATOR_GT
5482       || this->op_ == OPERATOR_GE)
5483     {
5484       if (!Type::are_assignable(left_type, right_type, NULL)
5485           && !Type::are_assignable(right_type, left_type, NULL))
5486         {
5487           this->report_error(_("incompatible types in binary expression"));
5488           return;
5489         }
5490       if (!Binary_expression::check_operator_type(this->op_, left_type,
5491                                                   this->location())
5492           || !Binary_expression::check_operator_type(this->op_, right_type,
5493                                                      this->location()))
5494         {
5495           this->set_is_error();
5496           return;
5497         }
5498     }
5499   else if (this->op_ != OPERATOR_LSHIFT && this->op_ != OPERATOR_RSHIFT)
5500     {
5501       if (!Type::are_compatible_for_binop(left_type, right_type))
5502         {
5503           this->report_error(_("incompatible types in binary expression"));
5504           return;
5505         }
5506       if (!Binary_expression::check_operator_type(this->op_, left_type,
5507                                                   this->location()))
5508         {
5509           this->set_is_error();
5510           return;
5511         }
5512     }
5513   else
5514     {
5515       if (left_type->integer_type() == NULL)
5516         this->report_error(_("shift of non-integer operand"));
5517
5518       if (!right_type->is_abstract()
5519           && (right_type->integer_type() == NULL
5520               || !right_type->integer_type()->is_unsigned()))
5521         this->report_error(_("shift count not unsigned integer"));
5522       else
5523         {
5524           mpz_t val;
5525           mpz_init(val);
5526           Type* type;
5527           if (this->right_->integer_constant_value(true, val, &type))
5528             {
5529               if (mpz_sgn(val) < 0)
5530                 this->report_error(_("negative shift count"));
5531             }
5532           mpz_clear(val);
5533         }
5534     }
5535 }
5536
5537 // Get a tree for a binary expression.
5538
5539 tree
5540 Binary_expression::do_get_tree(Translate_context* context)
5541 {
5542   tree left = this->left_->get_tree(context);
5543   tree right = this->right_->get_tree(context);
5544
5545   if (left == error_mark_node || right == error_mark_node)
5546     return error_mark_node;
5547
5548   enum tree_code code;
5549   bool use_left_type = true;
5550   bool is_shift_op = false;
5551   switch (this->op_)
5552     {
5553     case OPERATOR_EQEQ:
5554     case OPERATOR_NOTEQ:
5555     case OPERATOR_LT:
5556     case OPERATOR_LE:
5557     case OPERATOR_GT:
5558     case OPERATOR_GE:
5559       return Expression::comparison_tree(context, this->op_,
5560                                          this->left_->type(), left,
5561                                          this->right_->type(), right,
5562                                          this->location());
5563
5564     case OPERATOR_OROR:
5565       code = TRUTH_ORIF_EXPR;
5566       use_left_type = false;
5567       break;
5568     case OPERATOR_ANDAND:
5569       code = TRUTH_ANDIF_EXPR;
5570       use_left_type = false;
5571       break;
5572     case OPERATOR_PLUS:
5573       code = PLUS_EXPR;
5574       break;
5575     case OPERATOR_MINUS:
5576       code = MINUS_EXPR;
5577       break;
5578     case OPERATOR_OR:
5579       code = BIT_IOR_EXPR;
5580       break;
5581     case OPERATOR_XOR:
5582       code = BIT_XOR_EXPR;
5583       break;
5584     case OPERATOR_MULT:
5585       code = MULT_EXPR;
5586       break;
5587     case OPERATOR_DIV:
5588       {
5589         Type *t = this->left_->type();
5590         if (t->float_type() != NULL || t->complex_type() != NULL)
5591           code = RDIV_EXPR;
5592         else
5593           code = TRUNC_DIV_EXPR;
5594       }
5595       break;
5596     case OPERATOR_MOD:
5597       code = TRUNC_MOD_EXPR;
5598       break;
5599     case OPERATOR_LSHIFT:
5600       code = LSHIFT_EXPR;
5601       is_shift_op = true;
5602       break;
5603     case OPERATOR_RSHIFT:
5604       code = RSHIFT_EXPR;
5605       is_shift_op = true;
5606       break;
5607     case OPERATOR_AND:
5608       code = BIT_AND_EXPR;
5609       break;
5610     case OPERATOR_BITCLEAR:
5611       right = fold_build1(BIT_NOT_EXPR, TREE_TYPE(right), right);
5612       code = BIT_AND_EXPR;
5613       break;
5614     default:
5615       gcc_unreachable();
5616     }
5617
5618   tree type = use_left_type ? TREE_TYPE(left) : TREE_TYPE(right);
5619
5620   if (this->left_->type()->is_string_type())
5621     {
5622       gcc_assert(this->op_ == OPERATOR_PLUS);
5623       tree string_type = Type::make_string_type()->get_tree(context->gogo());
5624       static tree string_plus_decl;
5625       return Gogo::call_builtin(&string_plus_decl,
5626                                 this->location(),
5627                                 "__go_string_plus",
5628                                 2,
5629                                 string_type,
5630                                 string_type,
5631                                 left,
5632                                 string_type,
5633                                 right);
5634     }
5635
5636   tree compute_type = excess_precision_type(type);
5637   if (compute_type != NULL_TREE)
5638     {
5639       left = ::convert(compute_type, left);
5640       right = ::convert(compute_type, right);
5641     }
5642
5643   tree eval_saved = NULL_TREE;
5644   if (is_shift_op)
5645     {
5646       if (!DECL_P(left))
5647         left = save_expr(left);
5648       if (!DECL_P(right))
5649         right = save_expr(right);
5650       // Make sure the values are evaluated.
5651       eval_saved = fold_build2_loc(this->location(), COMPOUND_EXPR,
5652                                    void_type_node, left, right);
5653     }
5654
5655   tree ret = fold_build2_loc(this->location(),
5656                              code,
5657                              compute_type != NULL_TREE ? compute_type : type,
5658                              left, right);
5659
5660   if (compute_type != NULL_TREE)
5661     ret = ::convert(type, ret);
5662
5663   // In Go, a shift larger than the size of the type is well-defined.
5664   // This is not true in GENERIC, so we need to insert a conditional.
5665   if (is_shift_op)
5666     {
5667       gcc_assert(INTEGRAL_TYPE_P(TREE_TYPE(left)));
5668       gcc_assert(this->left_->type()->integer_type() != NULL);
5669       int bits = TYPE_PRECISION(TREE_TYPE(left));
5670
5671       tree compare = fold_build2(LT_EXPR, boolean_type_node, right,
5672                                  build_int_cst_type(TREE_TYPE(right), bits));
5673
5674       tree overflow_result = fold_convert_loc(this->location(),
5675                                               TREE_TYPE(left),
5676                                               integer_zero_node);
5677       if (this->op_ == OPERATOR_RSHIFT
5678           && !this->left_->type()->integer_type()->is_unsigned())
5679         {
5680           tree neg = fold_build2_loc(this->location(), LT_EXPR,
5681                                      boolean_type_node, left,
5682                                      fold_convert_loc(this->location(),
5683                                                       TREE_TYPE(left),
5684                                                       integer_zero_node));
5685           tree neg_one = fold_build2_loc(this->location(),
5686                                          MINUS_EXPR, TREE_TYPE(left),
5687                                          fold_convert_loc(this->location(),
5688                                                           TREE_TYPE(left),
5689                                                           integer_zero_node),
5690                                          fold_convert_loc(this->location(),
5691                                                           TREE_TYPE(left),
5692                                                           integer_one_node));
5693           overflow_result = fold_build3_loc(this->location(), COND_EXPR,
5694                                             TREE_TYPE(left), neg, neg_one,
5695                                             overflow_result);
5696         }
5697
5698       ret = fold_build3_loc(this->location(), COND_EXPR, TREE_TYPE(left),
5699                             compare, ret, overflow_result);
5700
5701       ret = fold_build2_loc(this->location(), COMPOUND_EXPR,
5702                             TREE_TYPE(ret), eval_saved, ret);
5703     }
5704
5705   return ret;
5706 }
5707
5708 // Export a binary expression.
5709
5710 void
5711 Binary_expression::do_export(Export* exp) const
5712 {
5713   exp->write_c_string("(");
5714   this->left_->export_expression(exp);
5715   switch (this->op_)
5716     {
5717     case OPERATOR_OROR:
5718       exp->write_c_string(" || ");
5719       break;
5720     case OPERATOR_ANDAND:
5721       exp->write_c_string(" && ");
5722       break;
5723     case OPERATOR_EQEQ:
5724       exp->write_c_string(" == ");
5725       break;
5726     case OPERATOR_NOTEQ:
5727       exp->write_c_string(" != ");
5728       break;
5729     case OPERATOR_LT:
5730       exp->write_c_string(" < ");
5731       break;
5732     case OPERATOR_LE:
5733       exp->write_c_string(" <= ");
5734       break;
5735     case OPERATOR_GT:
5736       exp->write_c_string(" > ");
5737       break;
5738     case OPERATOR_GE:
5739       exp->write_c_string(" >= ");
5740       break;
5741     case OPERATOR_PLUS:
5742       exp->write_c_string(" + ");
5743       break;
5744     case OPERATOR_MINUS:
5745       exp->write_c_string(" - ");
5746       break;
5747     case OPERATOR_OR:
5748       exp->write_c_string(" | ");
5749       break;
5750     case OPERATOR_XOR:
5751       exp->write_c_string(" ^ ");
5752       break;
5753     case OPERATOR_MULT:
5754       exp->write_c_string(" * ");
5755       break;
5756     case OPERATOR_DIV:
5757       exp->write_c_string(" / ");
5758       break;
5759     case OPERATOR_MOD:
5760       exp->write_c_string(" % ");
5761       break;
5762     case OPERATOR_LSHIFT:
5763       exp->write_c_string(" << ");
5764       break;
5765     case OPERATOR_RSHIFT:
5766       exp->write_c_string(" >> ");
5767       break;
5768     case OPERATOR_AND:
5769       exp->write_c_string(" & ");
5770       break;
5771     case OPERATOR_BITCLEAR:
5772       exp->write_c_string(" &^ ");
5773       break;
5774     default:
5775       gcc_unreachable();
5776     }
5777   this->right_->export_expression(exp);
5778   exp->write_c_string(")");
5779 }
5780
5781 // Import a binary expression.
5782
5783 Expression*
5784 Binary_expression::do_import(Import* imp)
5785 {
5786   imp->require_c_string("(");
5787
5788   Expression* left = Expression::import_expression(imp);
5789
5790   Operator op;
5791   if (imp->match_c_string(" || "))
5792     {
5793       op = OPERATOR_OROR;
5794       imp->advance(4);
5795     }
5796   else if (imp->match_c_string(" && "))
5797     {
5798       op = OPERATOR_ANDAND;
5799       imp->advance(4);
5800     }
5801   else if (imp->match_c_string(" == "))
5802     {
5803       op = OPERATOR_EQEQ;
5804       imp->advance(4);
5805     }
5806   else if (imp->match_c_string(" != "))
5807     {
5808       op = OPERATOR_NOTEQ;
5809       imp->advance(4);
5810     }
5811   else if (imp->match_c_string(" < "))
5812     {
5813       op = OPERATOR_LT;
5814       imp->advance(3);
5815     }
5816   else if (imp->match_c_string(" <= "))
5817     {
5818       op = OPERATOR_LE;
5819       imp->advance(4);
5820     }
5821   else if (imp->match_c_string(" > "))
5822     {
5823       op = OPERATOR_GT;
5824       imp->advance(3);
5825     }
5826   else if (imp->match_c_string(" >= "))
5827     {
5828       op = OPERATOR_GE;
5829       imp->advance(4);
5830     }
5831   else if (imp->match_c_string(" + "))
5832     {
5833       op = OPERATOR_PLUS;
5834       imp->advance(3);
5835     }
5836   else if (imp->match_c_string(" - "))
5837     {
5838       op = OPERATOR_MINUS;
5839       imp->advance(3);
5840     }
5841   else if (imp->match_c_string(" | "))
5842     {
5843       op = OPERATOR_OR;
5844       imp->advance(3);
5845     }
5846   else if (imp->match_c_string(" ^ "))
5847     {
5848       op = OPERATOR_XOR;
5849       imp->advance(3);
5850     }
5851   else if (imp->match_c_string(" * "))
5852     {
5853       op = OPERATOR_MULT;
5854       imp->advance(3);
5855     }
5856   else if (imp->match_c_string(" / "))
5857     {
5858       op = OPERATOR_DIV;
5859       imp->advance(3);
5860     }
5861   else if (imp->match_c_string(" % "))
5862     {
5863       op = OPERATOR_MOD;
5864       imp->advance(3);
5865     }
5866   else if (imp->match_c_string(" << "))
5867     {
5868       op = OPERATOR_LSHIFT;
5869       imp->advance(4);
5870     }
5871   else if (imp->match_c_string(" >> "))
5872     {
5873       op = OPERATOR_RSHIFT;
5874       imp->advance(4);
5875     }
5876   else if (imp->match_c_string(" & "))
5877     {
5878       op = OPERATOR_AND;
5879       imp->advance(3);
5880     }
5881   else if (imp->match_c_string(" &^ "))
5882     {
5883       op = OPERATOR_BITCLEAR;
5884       imp->advance(4);
5885     }
5886   else
5887     {
5888       error_at(imp->location(), "unrecognized binary operator");
5889       return Expression::make_error(imp->location());
5890     }
5891
5892   Expression* right = Expression::import_expression(imp);
5893
5894   imp->require_c_string(")");
5895
5896   return Expression::make_binary(op, left, right, imp->location());
5897 }
5898
5899 // Make a binary expression.
5900
5901 Expression*
5902 Expression::make_binary(Operator op, Expression* left, Expression* right,
5903                         source_location location)
5904 {
5905   return new Binary_expression(op, left, right, location);
5906 }
5907
5908 // Implement a comparison.
5909
5910 tree
5911 Expression::comparison_tree(Translate_context* context, Operator op,
5912                             Type* left_type, tree left_tree,
5913                             Type* right_type, tree right_tree,
5914                             source_location location)
5915 {
5916   enum tree_code code;
5917   switch (op)
5918     {
5919     case OPERATOR_EQEQ:
5920       code = EQ_EXPR;
5921       break;
5922     case OPERATOR_NOTEQ:
5923       code = NE_EXPR;
5924       break;
5925     case OPERATOR_LT:
5926       code = LT_EXPR;
5927       break;
5928     case OPERATOR_LE:
5929       code = LE_EXPR;
5930       break;
5931     case OPERATOR_GT:
5932       code = GT_EXPR;
5933       break;
5934     case OPERATOR_GE:
5935       code = GE_EXPR;
5936       break;
5937     default:
5938       gcc_unreachable();
5939     }
5940
5941   if (left_type->is_string_type() && right_type->is_string_type())
5942     {
5943       tree string_type = Type::make_string_type()->get_tree(context->gogo());
5944       static tree string_compare_decl;
5945       left_tree = Gogo::call_builtin(&string_compare_decl,
5946                                      location,
5947                                      "__go_strcmp",
5948                                      2,
5949                                      integer_type_node,
5950                                      string_type,
5951                                      left_tree,
5952                                      string_type,
5953                                      right_tree);
5954       right_tree = build_int_cst_type(integer_type_node, 0);
5955     }
5956   else if ((left_type->interface_type() != NULL
5957             && right_type->interface_type() == NULL
5958             && !right_type->is_nil_type())
5959            || (left_type->interface_type() == NULL
5960                && !left_type->is_nil_type()
5961                && right_type->interface_type() != NULL))
5962     {
5963       // Comparing an interface value to a non-interface value.
5964       if (left_type->interface_type() == NULL)
5965         {
5966           std::swap(left_type, right_type);
5967           std::swap(left_tree, right_tree);
5968         }
5969
5970       // The right operand is not an interface.  We need to take its
5971       // address if it is not a pointer.
5972       tree make_tmp;
5973       tree arg;
5974       if (right_type->points_to() != NULL)
5975         {
5976           make_tmp = NULL_TREE;
5977           arg = right_tree;
5978         }
5979       else if (TREE_ADDRESSABLE(TREE_TYPE(right_tree)) || DECL_P(right_tree))
5980         {
5981           make_tmp = NULL_TREE;
5982           arg = build_fold_addr_expr_loc(location, right_tree);
5983           if (DECL_P(right_tree))
5984             TREE_ADDRESSABLE(right_tree) = 1;
5985         }
5986       else
5987         {
5988           tree tmp = create_tmp_var(TREE_TYPE(right_tree),
5989                                     get_name(right_tree));
5990           DECL_IGNORED_P(tmp) = 0;
5991           DECL_INITIAL(tmp) = right_tree;
5992           TREE_ADDRESSABLE(tmp) = 1;
5993           make_tmp = build1(DECL_EXPR, void_type_node, tmp);
5994           SET_EXPR_LOCATION(make_tmp, location);
5995           arg = build_fold_addr_expr_loc(location, tmp);
5996         }
5997       arg = fold_convert_loc(location, ptr_type_node, arg);
5998
5999       tree descriptor = right_type->type_descriptor_pointer(context->gogo());
6000
6001       if (left_type->interface_type()->is_empty())
6002         {
6003           static tree empty_interface_value_compare_decl;
6004           left_tree = Gogo::call_builtin(&empty_interface_value_compare_decl,
6005                                          location,
6006                                          "__go_empty_interface_value_compare",
6007                                          3,
6008                                          integer_type_node,
6009                                          TREE_TYPE(left_tree),
6010                                          left_tree,
6011                                          TREE_TYPE(descriptor),
6012                                          descriptor,
6013                                          ptr_type_node,
6014                                          arg);
6015           // This can panic if the type is not comparable.
6016           TREE_NOTHROW(empty_interface_value_compare_decl) = 0;
6017         }
6018       else
6019         {
6020           static tree interface_value_compare_decl;
6021           left_tree = Gogo::call_builtin(&interface_value_compare_decl,
6022                                          location,
6023                                          "__go_interface_value_compare",
6024                                          3,
6025                                          integer_type_node,
6026                                          TREE_TYPE(left_tree),
6027                                          left_tree,
6028                                          TREE_TYPE(descriptor),
6029                                          descriptor,
6030                                          ptr_type_node,
6031                                          arg);
6032           // This can panic if the type is not comparable.
6033           TREE_NOTHROW(interface_value_compare_decl) = 0;
6034         }
6035       right_tree = build_int_cst_type(integer_type_node, 0);
6036
6037       if (make_tmp != NULL_TREE)
6038         left_tree = build2(COMPOUND_EXPR, TREE_TYPE(left_tree), make_tmp,
6039                            left_tree);
6040     }
6041   else if (left_type->interface_type() != NULL
6042            && right_type->interface_type() != NULL)
6043     {
6044       if (left_type->interface_type()->is_empty())
6045         {
6046           gcc_assert(right_type->interface_type()->is_empty());
6047           static tree empty_interface_compare_decl;
6048           left_tree = Gogo::call_builtin(&empty_interface_compare_decl,
6049                                          location,
6050                                          "__go_empty_interface_compare",
6051                                          2,
6052                                          integer_type_node,
6053                                          TREE_TYPE(left_tree),
6054                                          left_tree,
6055                                          TREE_TYPE(right_tree),
6056                                          right_tree);
6057           // This can panic if the type is uncomparable.
6058           TREE_NOTHROW(empty_interface_compare_decl) = 0;
6059         }
6060       else
6061         {
6062           gcc_assert(!right_type->interface_type()->is_empty());
6063           static tree interface_compare_decl;
6064           left_tree = Gogo::call_builtin(&interface_compare_decl,
6065                                          location,
6066                                          "__go_interface_compare",
6067                                          2,
6068                                          integer_type_node,
6069                                          TREE_TYPE(left_tree),
6070                                          left_tree,
6071                                          TREE_TYPE(right_tree),
6072                                          right_tree);
6073           // This can panic if the type is uncomparable.
6074           TREE_NOTHROW(interface_compare_decl) = 0;
6075         }
6076       right_tree = build_int_cst_type(integer_type_node, 0);
6077     }
6078
6079   if (left_type->is_nil_type()
6080       && (op == OPERATOR_EQEQ || op == OPERATOR_NOTEQ))
6081     {
6082       std::swap(left_type, right_type);
6083       std::swap(left_tree, right_tree);
6084     }
6085
6086   if (right_type->is_nil_type())
6087     {
6088       if (left_type->array_type() != NULL
6089           && left_type->array_type()->length() == NULL)
6090         {
6091           Array_type* at = left_type->array_type();
6092           left_tree = at->value_pointer_tree(context->gogo(), left_tree);
6093           right_tree = fold_convert(TREE_TYPE(left_tree), null_pointer_node);
6094         }
6095       else if (left_type->interface_type() != NULL)
6096         {
6097           // An interface is nil if the first field is nil.
6098           tree left_type_tree = TREE_TYPE(left_tree);
6099           gcc_assert(TREE_CODE(left_type_tree) == RECORD_TYPE);
6100           tree field = TYPE_FIELDS(left_type_tree);
6101           left_tree = build3(COMPONENT_REF, TREE_TYPE(field), left_tree,
6102                              field, NULL_TREE);
6103           right_tree = fold_convert(TREE_TYPE(left_tree), null_pointer_node);
6104         }
6105       else
6106         {
6107           gcc_assert(POINTER_TYPE_P(TREE_TYPE(left_tree)));
6108           right_tree = fold_convert(TREE_TYPE(left_tree), null_pointer_node);
6109         }
6110     }
6111
6112   tree ret = fold_build2(code, boolean_type_node, left_tree, right_tree);
6113   if (CAN_HAVE_LOCATION_P(ret))
6114     SET_EXPR_LOCATION(ret, location);
6115   return ret;
6116 }
6117
6118 // Class Bound_method_expression.
6119
6120 // Traversal.
6121
6122 int
6123 Bound_method_expression::do_traverse(Traverse* traverse)
6124 {
6125   if (Expression::traverse(&this->expr_, traverse) == TRAVERSE_EXIT)
6126     return TRAVERSE_EXIT;
6127   return Expression::traverse(&this->method_, traverse);
6128 }
6129
6130 // Return the type of a bound method expression.  The type of this
6131 // object is really the type of the method with no receiver.  We
6132 // should be able to get away with just returning the type of the
6133 // method.
6134
6135 Type*
6136 Bound_method_expression::do_type()
6137 {
6138   return this->method_->type();
6139 }
6140
6141 // Determine the types of a method expression.
6142
6143 void
6144 Bound_method_expression::do_determine_type(const Type_context*)
6145 {
6146   this->method_->determine_type_no_context();
6147   Type* mtype = this->method_->type();
6148   Function_type* fntype = mtype == NULL ? NULL : mtype->function_type();
6149   if (fntype == NULL || !fntype->is_method())
6150     this->expr_->determine_type_no_context();
6151   else
6152     {
6153       Type_context subcontext(fntype->receiver()->type(), false);
6154       this->expr_->determine_type(&subcontext);
6155     }
6156 }
6157
6158 // Check the types of a method expression.
6159
6160 void
6161 Bound_method_expression::do_check_types(Gogo*)
6162 {
6163   Type* type = this->method_->type()->deref();
6164   if (type == NULL
6165       || type->function_type() == NULL
6166       || !type->function_type()->is_method())
6167     this->report_error(_("object is not a method"));
6168   else
6169     {
6170       Type* rtype = type->function_type()->receiver()->type()->deref();
6171       Type* etype = (this->expr_type_ != NULL
6172                      ? this->expr_type_
6173                      : this->expr_->type());
6174       etype = etype->deref();
6175       if (!Type::are_identical(rtype, etype, NULL))
6176         this->report_error(_("method type does not match object type"));
6177     }
6178 }
6179
6180 // Get the tree for a method expression.  There is no standard tree
6181 // representation for this.  The only places it may currently be used
6182 // are in a Call_expression or a Go_statement, which will take it
6183 // apart directly.  So this has nothing to do at present.
6184
6185 tree
6186 Bound_method_expression::do_get_tree(Translate_context*)
6187 {
6188   gcc_unreachable();
6189 }
6190
6191 // Make a method expression.
6192
6193 Bound_method_expression*
6194 Expression::make_bound_method(Expression* expr, Expression* method,
6195                               source_location location)
6196 {
6197   return new Bound_method_expression(expr, method, location);
6198 }
6199
6200 // Class Builtin_call_expression.  This is used for a call to a
6201 // builtin function.
6202
6203 class Builtin_call_expression : public Call_expression
6204 {
6205  public:
6206   Builtin_call_expression(Gogo* gogo, Expression* fn, Expression_list* args,
6207                           bool is_varargs, source_location location);
6208
6209  protected:
6210   // This overrides Call_expression::do_lower.
6211   Expression*
6212   do_lower(Gogo*, Named_object*, int);
6213
6214   bool
6215   do_is_constant() const;
6216
6217   bool
6218   do_integer_constant_value(bool, mpz_t, Type**) const;
6219
6220   bool
6221   do_float_constant_value(mpfr_t, Type**) const;
6222
6223   bool
6224   do_complex_constant_value(mpfr_t, mpfr_t, Type**) const;
6225
6226   Type*
6227   do_type();
6228
6229   void
6230   do_determine_type(const Type_context*);
6231
6232   void
6233   do_check_types(Gogo*);
6234
6235   Expression*
6236   do_copy()
6237   {
6238     return new Builtin_call_expression(this->gogo_, this->fn()->copy(),
6239                                        this->args()->copy(),
6240                                        this->is_varargs(),
6241                                        this->location());
6242   }
6243
6244   tree
6245   do_get_tree(Translate_context*);
6246
6247   void
6248   do_export(Export*) const;
6249
6250   virtual bool
6251   do_is_recover_call() const;
6252
6253   virtual void
6254   do_set_recover_arg(Expression*);
6255
6256  private:
6257   // The builtin functions.
6258   enum Builtin_function_code
6259     {
6260       BUILTIN_INVALID,
6261
6262       // Predeclared builtin functions.
6263       BUILTIN_APPEND,
6264       BUILTIN_CAP,
6265       BUILTIN_CLOSE,
6266       BUILTIN_CLOSED,
6267       BUILTIN_CMPLX,
6268       BUILTIN_COPY,
6269       BUILTIN_IMAG,
6270       BUILTIN_LEN,
6271       BUILTIN_MAKE,
6272       BUILTIN_NEW,
6273       BUILTIN_PANIC,
6274       BUILTIN_PRINT,
6275       BUILTIN_PRINTLN,
6276       BUILTIN_REAL,
6277       BUILTIN_RECOVER,
6278
6279       // Builtin functions from the unsafe package.
6280       BUILTIN_ALIGNOF,
6281       BUILTIN_OFFSETOF,
6282       BUILTIN_SIZEOF
6283     };
6284
6285   Expression*
6286   one_arg() const;
6287
6288   bool
6289   check_one_arg();
6290
6291   static Type*
6292   real_imag_type(Type*);
6293
6294   static Type*
6295   cmplx_type(Type*);
6296
6297   // A pointer back to the general IR structure.  This avoids a global
6298   // variable, or passing it around everywhere.
6299   Gogo* gogo_;
6300   // The builtin function being called.
6301   Builtin_function_code code_;
6302 };
6303
6304 Builtin_call_expression::Builtin_call_expression(Gogo* gogo,
6305                                                  Expression* fn,
6306                                                  Expression_list* args,
6307                                                  bool is_varargs,
6308                                                  source_location location)
6309   : Call_expression(fn, args, is_varargs, location),
6310     gogo_(gogo), code_(BUILTIN_INVALID)
6311 {
6312   Func_expression* fnexp = this->fn()->func_expression();
6313   gcc_assert(fnexp != NULL);
6314   const std::string& name(fnexp->named_object()->name());
6315   if (name == "append")
6316     this->code_ = BUILTIN_APPEND;
6317   else if (name == "cap")
6318     this->code_ = BUILTIN_CAP;
6319   else if (name == "close")
6320     this->code_ = BUILTIN_CLOSE;
6321   else if (name == "closed")
6322     this->code_ = BUILTIN_CLOSED;
6323   else if (name == "cmplx")
6324     this->code_ = BUILTIN_CMPLX;
6325   else if (name == "copy")
6326     this->code_ = BUILTIN_COPY;
6327   else if (name == "imag")
6328     this->code_ = BUILTIN_IMAG;
6329   else if (name == "len")
6330     this->code_ = BUILTIN_LEN;
6331   else if (name == "make")
6332     this->code_ = BUILTIN_MAKE;
6333   else if (name == "new")
6334     this->code_ = BUILTIN_NEW;
6335   else if (name == "panic")
6336     this->code_ = BUILTIN_PANIC;
6337   else if (name == "print")
6338     this->code_ = BUILTIN_PRINT;
6339   else if (name == "println")
6340     this->code_ = BUILTIN_PRINTLN;
6341   else if (name == "real")
6342     this->code_ = BUILTIN_REAL;
6343   else if (name == "recover")
6344     this->code_ = BUILTIN_RECOVER;
6345   else if (name == "Alignof")
6346     this->code_ = BUILTIN_ALIGNOF;
6347   else if (name == "Offsetof")
6348     this->code_ = BUILTIN_OFFSETOF;
6349   else if (name == "Sizeof")
6350     this->code_ = BUILTIN_SIZEOF;
6351   else
6352     gcc_unreachable();
6353 }
6354
6355 // Return whether this is a call to recover.  This is a virtual
6356 // function called from the parent class.
6357
6358 bool
6359 Builtin_call_expression::do_is_recover_call() const
6360 {
6361   if (this->classification() == EXPRESSION_ERROR)
6362     return false;
6363   return this->code_ == BUILTIN_RECOVER;
6364 }
6365
6366 // Set the argument for a call to recover.
6367
6368 void
6369 Builtin_call_expression::do_set_recover_arg(Expression* arg)
6370 {
6371   const Expression_list* args = this->args();
6372   gcc_assert(args == NULL || args->empty());
6373   Expression_list* new_args = new Expression_list();
6374   new_args->push_back(arg);
6375   this->set_args(new_args);
6376 }
6377
6378 // A traversal class which looks for a call expression.
6379
6380 class Find_call_expression : public Traverse
6381 {
6382  public:
6383   Find_call_expression()
6384     : Traverse(traverse_expressions),
6385       found_(false)
6386   { }
6387
6388   int
6389   expression(Expression**);
6390
6391   bool
6392   found()
6393   { return this->found_; }
6394
6395  private:
6396   bool found_;
6397 };
6398
6399 int
6400 Find_call_expression::expression(Expression** pexpr)
6401 {
6402   if ((*pexpr)->call_expression() != NULL)
6403     {
6404       this->found_ = true;
6405       return TRAVERSE_EXIT;
6406     }
6407   return TRAVERSE_CONTINUE;
6408 }
6409
6410 // Lower a builtin call expression.  This turns new and make into
6411 // specific expressions.  We also convert to a constant if we can.
6412
6413 Expression*
6414 Builtin_call_expression::do_lower(Gogo* gogo, Named_object* function, int)
6415 {
6416   if (this->code_ == BUILTIN_NEW)
6417     {
6418       const Expression_list* args = this->args();
6419       if (args == NULL || args->size() < 1)
6420         this->report_error(_("not enough arguments"));
6421       else if (args->size() > 1)
6422         this->report_error(_("too many arguments"));
6423       else
6424         {
6425           Expression* arg = args->front();
6426           if (!arg->is_type_expression())
6427             {
6428               error_at(arg->location(), "expected type");
6429               this->set_is_error();
6430             }
6431           else
6432             return Expression::make_allocation(arg->type(), this->location());
6433         }
6434     }
6435   else if (this->code_ == BUILTIN_MAKE)
6436     {
6437       const Expression_list* args = this->args();
6438       if (args == NULL || args->size() < 1)
6439         this->report_error(_("not enough arguments"));
6440       else
6441         {
6442           Expression* arg = args->front();
6443           if (!arg->is_type_expression())
6444             {
6445               error_at(arg->location(), "expected type");
6446               this->set_is_error();
6447             }
6448           else
6449             {
6450               Expression_list* newargs;
6451               if (args->size() == 1)
6452                 newargs = NULL;
6453               else
6454                 {
6455                   newargs = new Expression_list();
6456                   Expression_list::const_iterator p = args->begin();
6457                   ++p;
6458                   for (; p != args->end(); ++p)
6459                     newargs->push_back(*p);
6460                 }
6461               return Expression::make_make(arg->type(), newargs,
6462                                            this->location());
6463             }
6464         }
6465     }
6466   else if (this->is_constant())
6467     {
6468       // We can only lower len and cap if there are no function calls
6469       // in the arguments.  Otherwise we have to make the call.
6470       if (this->code_ == BUILTIN_LEN || this->code_ == BUILTIN_CAP)
6471         {
6472           Expression* arg = this->one_arg();
6473           if (!arg->is_constant())
6474             {
6475               Find_call_expression find_call;
6476               Expression::traverse(&arg, &find_call);
6477               if (find_call.found())
6478                 return this;
6479             }
6480         }
6481
6482       mpz_t ival;
6483       mpz_init(ival);
6484       Type* type;
6485       if (this->integer_constant_value(true, ival, &type))
6486         {
6487           Expression* ret = Expression::make_integer(&ival, type,
6488                                                      this->location());
6489           mpz_clear(ival);
6490           return ret;
6491         }
6492       mpz_clear(ival);
6493
6494       mpfr_t rval;
6495       mpfr_init(rval);
6496       if (this->float_constant_value(rval, &type))
6497         {
6498           Expression* ret = Expression::make_float(&rval, type,
6499                                                    this->location());
6500           mpfr_clear(rval);
6501           return ret;
6502         }
6503
6504       mpfr_t imag;
6505       mpfr_init(imag);
6506       if (this->complex_constant_value(rval, imag, &type))
6507         {
6508           Expression* ret = Expression::make_complex(&rval, &imag, type,
6509                                                      this->location());
6510           mpfr_clear(rval);
6511           mpfr_clear(imag);
6512           return ret;
6513         }
6514       mpfr_clear(rval);
6515       mpfr_clear(imag);
6516     }
6517   else if (this->code_ == BUILTIN_RECOVER)
6518     {
6519       if (function != NULL)
6520         function->func_value()->set_calls_recover();
6521       else
6522         {
6523           // Calling recover outside of a function always returns the
6524           // nil empty interface.
6525           Type* eface = Type::make_interface_type(NULL, this->location());
6526           return Expression::make_cast(eface,
6527                                        Expression::make_nil(this->location()),
6528                                        this->location());
6529         }
6530     }
6531   else if (this->code_ == BUILTIN_APPEND)
6532     {
6533       // Lower the varargs.
6534       const Expression_list* args = this->args();
6535       if (args == NULL || args->empty())
6536         return this;
6537       Type* slice_type = args->front()->type();
6538       if (!slice_type->is_open_array_type())
6539         {
6540           error_at(args->front()->location(), "argument 1 must be a slice");
6541           this->set_is_error();
6542           return this;
6543         }
6544       return this->lower_varargs(gogo, function, slice_type, 2);
6545     }
6546
6547   return this;
6548 }
6549
6550 // Return the type of the real or imag functions, given the type of
6551 // the argument.  We need to map complex to float, complex64 to
6552 // float32, and complex128 to float64, so it has to be done by name.
6553 // This returns NULL if it can't figure out the type.
6554
6555 Type*
6556 Builtin_call_expression::real_imag_type(Type* arg_type)
6557 {
6558   if (arg_type == NULL || arg_type->is_abstract())
6559     return NULL;
6560   Named_type* nt = arg_type->named_type();
6561   if (nt == NULL)
6562     return NULL;
6563   while (nt->real_type()->named_type() != NULL)
6564     nt = nt->real_type()->named_type();
6565   if (nt->name() == "complex")
6566     return Type::lookup_float_type("float");
6567   else if (nt->name() == "complex64")
6568     return Type::lookup_float_type("float32");
6569   else if (nt->name() == "complex128")
6570     return Type::lookup_float_type("float64");
6571   else
6572     return NULL;
6573 }
6574
6575 // Return the type of the cmplx function, given the type of one of the
6576 // argments.  Like real_imag_type, we have to map by name.
6577
6578 Type*
6579 Builtin_call_expression::cmplx_type(Type* arg_type)
6580 {
6581   if (arg_type == NULL || arg_type->is_abstract())
6582     return NULL;
6583   Named_type* nt = arg_type->named_type();
6584   if (nt == NULL)
6585     return NULL;
6586   while (nt->real_type()->named_type() != NULL)
6587     nt = nt->real_type()->named_type();
6588   if (nt->name() == "float")
6589     return Type::lookup_complex_type("complex");
6590   else if (nt->name() == "float32")
6591     return Type::lookup_complex_type("complex64");
6592   else if (nt->name() == "float64")
6593     return Type::lookup_complex_type("complex128");
6594   else
6595     return NULL;
6596 }
6597
6598 // Return a single argument, or NULL if there isn't one.
6599
6600 Expression*
6601 Builtin_call_expression::one_arg() const
6602 {
6603   const Expression_list* args = this->args();
6604   if (args->size() != 1)
6605     return NULL;
6606   return args->front();
6607 }
6608
6609 // Return whether this is constant: len of a string, or len or cap of
6610 // a fixed array, or unsafe.Sizeof, unsafe.Offsetof, unsafe.Alignof.
6611
6612 bool
6613 Builtin_call_expression::do_is_constant() const
6614 {
6615   switch (this->code_)
6616     {
6617     case BUILTIN_LEN:
6618     case BUILTIN_CAP:
6619       {
6620         Expression* arg = this->one_arg();
6621         if (arg == NULL)
6622           return false;
6623         Type* arg_type = arg->type();
6624
6625         if (arg_type->points_to() != NULL
6626             && arg_type->points_to()->array_type() != NULL
6627             && !arg_type->points_to()->is_open_array_type())
6628           arg_type = arg_type->points_to();
6629
6630         if (arg_type->array_type() != NULL
6631             && arg_type->array_type()->length() != NULL)
6632           return arg_type->array_type()->length()->is_constant();
6633
6634         if (this->code_ == BUILTIN_LEN && arg_type->is_string_type())
6635           return arg->is_constant();
6636       }
6637       break;
6638
6639     case BUILTIN_SIZEOF:
6640     case BUILTIN_ALIGNOF:
6641       return this->one_arg() != NULL;
6642
6643     case BUILTIN_OFFSETOF:
6644       {
6645         Expression* arg = this->one_arg();
6646         if (arg == NULL)
6647           return false;
6648         return arg->field_reference_expression() != NULL;
6649       }
6650
6651     case BUILTIN_CMPLX:
6652       {
6653         const Expression_list* args = this->args();
6654         if (args != NULL && args->size() == 2)
6655           return args->front()->is_constant() && args->back()->is_constant();
6656       }
6657       break;
6658
6659     case BUILTIN_REAL:
6660     case BUILTIN_IMAG:
6661       {
6662         Expression* arg = this->one_arg();
6663         return arg != NULL && arg->is_constant();
6664       }
6665
6666     default:
6667       break;
6668     }
6669
6670   return false;
6671 }
6672
6673 // Return an integer constant value if possible.
6674
6675 bool
6676 Builtin_call_expression::do_integer_constant_value(bool iota_is_constant,
6677                                                    mpz_t val,
6678                                                    Type** ptype) const
6679 {
6680   if (this->code_ == BUILTIN_LEN
6681       || this->code_ == BUILTIN_CAP)
6682     {
6683       Expression* arg = this->one_arg();
6684       if (arg == NULL)
6685         return false;
6686       Type* arg_type = arg->type();
6687
6688       if (this->code_ == BUILTIN_LEN && arg_type->is_string_type())
6689         {
6690           std::string sval;
6691           if (arg->string_constant_value(&sval))
6692             {
6693               mpz_set_ui(val, sval.length());
6694               *ptype = Type::lookup_integer_type("int");
6695               return true;
6696             }
6697         }
6698
6699       if (arg_type->points_to() != NULL
6700           && arg_type->points_to()->array_type() != NULL
6701           && !arg_type->points_to()->is_open_array_type())
6702         arg_type = arg_type->points_to();
6703
6704       if (arg_type->array_type() != NULL
6705           && arg_type->array_type()->length() != NULL)
6706         {
6707           Expression* e = arg_type->array_type()->length();
6708           if (e->integer_constant_value(iota_is_constant, val, ptype))
6709             {
6710               *ptype = Type::lookup_integer_type("int");
6711               return true;
6712             }
6713         }
6714     }
6715   else if (this->code_ == BUILTIN_SIZEOF
6716            || this->code_ == BUILTIN_ALIGNOF)
6717     {
6718       Expression* arg = this->one_arg();
6719       if (arg == NULL)
6720         return false;
6721       Type* arg_type = arg->type();
6722       if (arg_type->is_error_type())
6723         return false;
6724       if (arg_type->is_abstract())
6725         return false;
6726       tree arg_type_tree = arg_type->get_tree(this->gogo_);
6727       unsigned long val_long;
6728       if (this->code_ == BUILTIN_SIZEOF)
6729         {
6730           tree type_size = TYPE_SIZE_UNIT(arg_type_tree);
6731           gcc_assert(TREE_CODE(type_size) == INTEGER_CST);
6732           if (TREE_INT_CST_HIGH(type_size) != 0)
6733             return false;
6734           unsigned HOST_WIDE_INT val_wide = TREE_INT_CST_LOW(type_size);
6735           val_long = static_cast<unsigned long>(val_wide);
6736           if (val_long != val_wide)
6737             return false;
6738         }
6739       else if (this->code_ == BUILTIN_ALIGNOF)
6740         {
6741           if (arg->field_reference_expression() == NULL)
6742             val_long = go_type_alignment(arg_type_tree);
6743           else
6744             {
6745               // Calling unsafe.Alignof(s.f) returns the alignment of
6746               // the type of f when it is used as a field in a struct.
6747               val_long = go_field_alignment(arg_type_tree);
6748             }
6749         }
6750       else
6751         gcc_unreachable();
6752       mpz_set_ui(val, val_long);
6753       *ptype = NULL;
6754       return true;
6755     }
6756   else if (this->code_ == BUILTIN_OFFSETOF)
6757     {
6758       Expression* arg = this->one_arg();
6759       if (arg == NULL)
6760         return false;
6761       Field_reference_expression* farg = arg->field_reference_expression();
6762       if (farg == NULL)
6763         return false;
6764       Expression* struct_expr = farg->expr();
6765       Type* st = struct_expr->type();
6766       if (st->struct_type() == NULL)
6767         return false;
6768       tree struct_tree = st->get_tree(this->gogo_);
6769       gcc_assert(TREE_CODE(struct_tree) == RECORD_TYPE);
6770       tree field = TYPE_FIELDS(struct_tree);
6771       for (unsigned int index = farg->field_index(); index > 0; --index)
6772         {
6773           field = DECL_CHAIN(field);
6774           gcc_assert(field != NULL_TREE);
6775         }
6776       HOST_WIDE_INT offset_wide = int_byte_position (field);
6777       if (offset_wide < 0)
6778         return false;
6779       unsigned long offset_long = static_cast<unsigned long>(offset_wide);
6780       if (offset_long != static_cast<unsigned HOST_WIDE_INT>(offset_wide))
6781         return false;
6782       mpz_set_ui(val, offset_long);
6783       return true;
6784     }
6785   return false;
6786 }
6787
6788 // Return a floating point constant value if possible.
6789
6790 bool
6791 Builtin_call_expression::do_float_constant_value(mpfr_t val,
6792                                                  Type** ptype) const
6793 {
6794   if (this->code_ == BUILTIN_REAL || this->code_ == BUILTIN_IMAG)
6795     {
6796       Expression* arg = this->one_arg();
6797       if (arg == NULL)
6798         return false;
6799
6800       mpfr_t real;
6801       mpfr_t imag;
6802       mpfr_init(real);
6803       mpfr_init(imag);
6804
6805       bool ret = false;
6806       Type* type;
6807       if (arg->complex_constant_value(real, imag, &type))
6808         {
6809           if (this->code_ == BUILTIN_REAL)
6810             mpfr_set(val, real, GMP_RNDN);
6811           else
6812             mpfr_set(val, imag, GMP_RNDN);
6813           *ptype = Builtin_call_expression::real_imag_type(type);
6814           ret = true;
6815         }
6816
6817       mpfr_clear(real);
6818       mpfr_clear(imag);
6819       return ret;
6820     }
6821
6822   return false;
6823 }
6824
6825 // Return a complex constant value if possible.
6826
6827 bool
6828 Builtin_call_expression::do_complex_constant_value(mpfr_t real, mpfr_t imag,
6829                                                    Type** ptype) const
6830 {
6831   if (this->code_ == BUILTIN_CMPLX)
6832     {
6833       const Expression_list* args = this->args();
6834       if (args == NULL || args->size() != 2)
6835         return false;
6836
6837       mpfr_t r;
6838       mpfr_init(r);
6839       Type* rtype;
6840       if (!args->front()->float_constant_value(r, &rtype))
6841         {
6842           mpfr_clear(r);
6843           return false;
6844         }
6845
6846       mpfr_t i;
6847       mpfr_init(i);
6848
6849       bool ret = false;
6850       Type* itype;
6851       if (args->back()->float_constant_value(i, &itype)
6852           && Type::are_identical(rtype, itype, NULL))
6853         {
6854           mpfr_set(real, r, GMP_RNDN);
6855           mpfr_set(imag, i, GMP_RNDN);
6856           *ptype = Builtin_call_expression::cmplx_type(rtype);
6857           ret = true;
6858         }
6859
6860       mpfr_clear(r);
6861       mpfr_clear(i);
6862
6863       return ret;
6864     }
6865
6866   return false;
6867 }
6868
6869 // Return the type.
6870
6871 Type*
6872 Builtin_call_expression::do_type()
6873 {
6874   switch (this->code_)
6875     {
6876     case BUILTIN_INVALID:
6877     default:
6878       gcc_unreachable();
6879
6880     case BUILTIN_NEW:
6881     case BUILTIN_MAKE:
6882       {
6883         const Expression_list* args = this->args();
6884         if (args == NULL || args->empty())
6885           return Type::make_error_type();
6886         return Type::make_pointer_type(args->front()->type());
6887       }
6888
6889     case BUILTIN_CAP:
6890     case BUILTIN_COPY:
6891     case BUILTIN_LEN:
6892     case BUILTIN_ALIGNOF:
6893     case BUILTIN_OFFSETOF:
6894     case BUILTIN_SIZEOF:
6895       return Type::lookup_integer_type("int");
6896
6897     case BUILTIN_CLOSE:
6898     case BUILTIN_PANIC:
6899     case BUILTIN_PRINT:
6900     case BUILTIN_PRINTLN:
6901       return Type::make_void_type();
6902
6903     case BUILTIN_CLOSED:
6904       return Type::lookup_bool_type();
6905
6906     case BUILTIN_RECOVER:
6907       return Type::make_interface_type(NULL, BUILTINS_LOCATION);
6908
6909     case BUILTIN_APPEND:
6910       {
6911         const Expression_list* args = this->args();
6912         if (args == NULL || args->empty())
6913           return Type::make_error_type();
6914         return args->front()->type();
6915       }
6916
6917     case BUILTIN_REAL:
6918     case BUILTIN_IMAG:
6919       {
6920         Expression* arg = this->one_arg();
6921         if (arg == NULL)
6922           return Type::make_error_type();
6923         Type* t = arg->type();
6924         if (t->is_abstract())
6925           t = t->make_non_abstract_type();
6926         t = Builtin_call_expression::real_imag_type(t);
6927         if (t == NULL)
6928           t = Type::make_error_type();
6929         return t;
6930       }
6931
6932     case BUILTIN_CMPLX:
6933       {
6934         const Expression_list* args = this->args();
6935         if (args == NULL || args->size() != 2)
6936           return Type::make_error_type();
6937         Type* t = args->front()->type();
6938         if (t->is_abstract())
6939           {
6940             t = args->back()->type();
6941             if (t->is_abstract())
6942               t = t->make_non_abstract_type();
6943           }
6944         t = Builtin_call_expression::cmplx_type(t);
6945         if (t == NULL)
6946           t = Type::make_error_type();
6947         return t;
6948       }
6949     }
6950 }
6951
6952 // Determine the type.
6953
6954 void
6955 Builtin_call_expression::do_determine_type(const Type_context* context)
6956 {
6957   this->fn()->determine_type_no_context();
6958
6959   const Expression_list* args = this->args();
6960
6961   bool is_print;
6962   Type* arg_type = NULL;
6963   switch (this->code_)
6964     {
6965     case BUILTIN_PRINT:
6966     case BUILTIN_PRINTLN:
6967       // Do not force a large integer constant to "int".
6968       is_print = true;
6969       break;
6970
6971     case BUILTIN_REAL:
6972     case BUILTIN_IMAG:
6973       arg_type = Builtin_call_expression::cmplx_type(context->type);
6974       is_print = false;
6975       break;
6976
6977     case BUILTIN_CMPLX:
6978       {
6979         // For the cmplx function the type of one operand can
6980         // determine the type of the other, as in a binary expression.
6981         arg_type = Builtin_call_expression::real_imag_type(context->type);
6982         if (args != NULL && args->size() == 2)
6983           {
6984             Type* t1 = args->front()->type();
6985             Type* t2 = args->front()->type();
6986             if (!t1->is_abstract())
6987               arg_type = t1;
6988             else if (!t2->is_abstract())
6989               arg_type = t2;
6990           }
6991         is_print = false;
6992       }
6993       break;
6994
6995     default:
6996       is_print = false;
6997       break;
6998     }
6999
7000   if (args != NULL)
7001     {
7002       for (Expression_list::const_iterator pa = args->begin();
7003            pa != args->end();
7004            ++pa)
7005         {
7006           Type_context subcontext;
7007           subcontext.type = arg_type;
7008
7009           if (is_print)
7010             {
7011               // We want to print large constants, we so can't just
7012               // use the appropriate nonabstract type.  Use uint64 for
7013               // an integer if we know it is nonnegative, otherwise
7014               // use int64 for a integer, otherwise use float64 for a
7015               // float or complex128 for a complex.
7016               Type* want_type = NULL;
7017               Type* atype = (*pa)->type();
7018               if (atype->is_abstract())
7019                 {
7020                   if (atype->integer_type() != NULL)
7021                     {
7022                       mpz_t val;
7023                       mpz_init(val);
7024                       Type* dummy;
7025                       if (this->integer_constant_value(true, val, &dummy)
7026                           && mpz_sgn(val) >= 0)
7027                         want_type = Type::lookup_integer_type("uint64");
7028                       else
7029                         want_type = Type::lookup_integer_type("int64");
7030                       mpz_clear(val);
7031                     }
7032                   else if (atype->float_type() != NULL)
7033                     want_type = Type::lookup_float_type("float64");
7034                   else if (atype->complex_type() != NULL)
7035                     want_type = Type::lookup_complex_type("complex128");
7036                   else if (atype->is_abstract_string_type())
7037                     want_type = Type::lookup_string_type();
7038                   else if (atype->is_abstract_boolean_type())
7039                     want_type = Type::lookup_bool_type();
7040                   else
7041                     gcc_unreachable();
7042                   subcontext.type = want_type;
7043                 }
7044             }
7045
7046           (*pa)->determine_type(&subcontext);
7047         }
7048     }
7049 }
7050
7051 // If there is exactly one argument, return true.  Otherwise give an
7052 // error message and return false.
7053
7054 bool
7055 Builtin_call_expression::check_one_arg()
7056 {
7057   const Expression_list* args = this->args();
7058   if (args == NULL || args->size() < 1)
7059     {
7060       this->report_error(_("not enough arguments"));
7061       return false;
7062     }
7063   else if (args->size() > 1)
7064     {
7065       this->report_error(_("too many arguments"));
7066       return false;
7067     }
7068   if (args->front()->is_error_expression()
7069       || args->front()->type()->is_error_type())
7070     {
7071       this->set_is_error();
7072       return false;
7073     }
7074   return true;
7075 }
7076
7077 // Check argument types for a builtin function.
7078
7079 void
7080 Builtin_call_expression::do_check_types(Gogo*)
7081 {
7082   switch (this->code_)
7083     {
7084     case BUILTIN_INVALID:
7085     case BUILTIN_NEW:
7086     case BUILTIN_MAKE:
7087       return;
7088
7089     case BUILTIN_LEN:
7090     case BUILTIN_CAP:
7091       {
7092         // The single argument may be either a string or an array or a
7093         // map or a channel, or a pointer to a closed array.
7094         if (this->check_one_arg())
7095           {
7096             Type* arg_type = this->one_arg()->type();
7097             if (arg_type->points_to() != NULL
7098                 && arg_type->points_to()->array_type() != NULL
7099                 && !arg_type->points_to()->is_open_array_type())
7100               arg_type = arg_type->points_to();
7101             if (this->code_ == BUILTIN_CAP)
7102               {
7103                 if (!arg_type->is_error_type()
7104                     && arg_type->array_type() == NULL
7105                     && arg_type->channel_type() == NULL)
7106                   this->report_error(_("argument must be array or slice "
7107                                        "or channel"));
7108               }
7109             else
7110               {
7111                 if (!arg_type->is_error_type()
7112                     && !arg_type->is_string_type()
7113                     && arg_type->array_type() == NULL
7114                     && arg_type->map_type() == NULL
7115                     && arg_type->channel_type() == NULL)
7116                   this->report_error(_("argument must be string or "
7117                                        "array or slice or map or channel"));
7118               }
7119           }
7120       }
7121       break;
7122
7123     case BUILTIN_PRINT:
7124     case BUILTIN_PRINTLN:
7125       {
7126         const Expression_list* args = this->args();
7127         if (args == NULL)
7128           {
7129             if (this->code_ == BUILTIN_PRINT)
7130               warning_at(this->location(), 0,
7131                          "no arguments for builtin function %<%s%>",
7132                          (this->code_ == BUILTIN_PRINT
7133                           ? "print"
7134                           : "println"));
7135           }
7136         else
7137           {
7138             for (Expression_list::const_iterator p = args->begin();
7139                  p != args->end();
7140                  ++p)
7141               {
7142                 Type* type = (*p)->type();
7143                 if (type->is_error_type()
7144                     || type->is_string_type()
7145                     || type->integer_type() != NULL
7146                     || type->float_type() != NULL
7147                     || type->complex_type() != NULL
7148                     || type->is_boolean_type()
7149                     || type->points_to() != NULL
7150                     || type->interface_type() != NULL
7151                     || type->channel_type() != NULL
7152                     || type->map_type() != NULL
7153                     || type->function_type() != NULL
7154                     || type->is_open_array_type())
7155                   ;
7156                 else
7157                   this->report_error(_("unsupported argument type to "
7158                                        "builtin function"));
7159               }
7160           }
7161       }
7162       break;
7163
7164     case BUILTIN_CLOSE:
7165     case BUILTIN_CLOSED:
7166       if (this->check_one_arg())
7167         {
7168           if (this->one_arg()->type()->channel_type() == NULL)
7169             this->report_error(_("argument must be channel"));
7170         }
7171       break;
7172
7173     case BUILTIN_PANIC:
7174     case BUILTIN_SIZEOF:
7175     case BUILTIN_ALIGNOF:
7176       this->check_one_arg();
7177       break;
7178
7179     case BUILTIN_RECOVER:
7180       if (this->args() != NULL && !this->args()->empty())
7181         this->report_error(_("too many arguments"));
7182       break;
7183
7184     case BUILTIN_OFFSETOF:
7185       if (this->check_one_arg())
7186         {
7187           Expression* arg = this->one_arg();
7188           if (arg->field_reference_expression() == NULL)
7189             this->report_error(_("argument must be a field reference"));
7190         }
7191       break;
7192
7193     case BUILTIN_COPY:
7194       {
7195         const Expression_list* args = this->args();
7196         if (args == NULL || args->size() < 2)
7197           {
7198             this->report_error(_("not enough arguments"));
7199             break;
7200           }
7201         else if (args->size() > 2)
7202           {
7203             this->report_error(_("too many arguments"));
7204             break;
7205           }
7206         Type* arg1_type = args->front()->type();
7207         Type* arg2_type = args->back()->type();
7208         if (arg1_type->is_error_type() || arg2_type->is_error_type())
7209           break;
7210
7211         Type* e1;
7212         if (arg1_type->is_open_array_type())
7213           e1 = arg1_type->array_type()->element_type();
7214         else
7215           {
7216             this->report_error(_("left argument must be a slice"));
7217             break;
7218           }
7219
7220         Type* e2;
7221         if (arg2_type->is_open_array_type())
7222           e2 = arg2_type->array_type()->element_type();
7223         else if (arg2_type->is_string_type())
7224           e2 = Type::lookup_integer_type("uint8");
7225         else
7226           {
7227             this->report_error(_("right argument must be a slice or a string"));
7228             break;
7229           }
7230
7231         if (!Type::are_identical(e1, e2, NULL))
7232           this->report_error(_("element types must be the same"));
7233       }
7234       break;
7235
7236     case BUILTIN_APPEND:
7237       {
7238         const Expression_list* args = this->args();
7239         if (args == NULL || args->empty())
7240           {
7241             this->report_error(_("not enough arguments"));
7242             break;
7243           }
7244         /* Lowering varargs should have left us with 2 arguments.  */
7245         gcc_assert(args->size() == 2);
7246         std::string reason;
7247         if (!Type::are_assignable(args->front()->type(), args->back()->type(),
7248                                   &reason))
7249           {
7250             if (reason.empty())
7251               this->report_error(_("arguments 1 and 2 have different types"));
7252             else
7253               {
7254                 error_at(this->location(),
7255                          "arguments 1 and 2 have different types (%s)",
7256                          reason.c_str());
7257                 this->set_is_error();
7258               }
7259           }
7260         break;
7261       }
7262
7263     case BUILTIN_REAL:
7264     case BUILTIN_IMAG:
7265       if (this->check_one_arg())
7266         {
7267           if (this->one_arg()->type()->complex_type() == NULL)
7268             this->report_error(_("argument must have complex type"));
7269         }
7270       break;
7271
7272     case BUILTIN_CMPLX:
7273       {
7274         const Expression_list* args = this->args();
7275         if (args == NULL || args->size() < 2)
7276           this->report_error(_("not enough arguments"));
7277         else if (args->size() > 2)
7278           this->report_error(_("too many arguments"));
7279         else if (args->front()->is_error_expression()
7280                  || args->front()->type()->is_error_type()
7281                  || args->back()->is_error_expression()
7282                  || args->back()->type()->is_error_type())
7283           this->set_is_error();
7284         else if (!Type::are_identical(args->front()->type(),
7285                                       args->back()->type(), NULL))
7286           this->report_error(_("cmplx arguments must have identical types"));
7287         else if (args->front()->type()->float_type() == NULL)
7288           this->report_error(_("cmplx arguments must have "
7289                                "floating-point type"));
7290       }
7291       break;
7292
7293     default:
7294       gcc_unreachable();
7295     }
7296 }
7297
7298 // Return the tree for a builtin function.
7299
7300 tree
7301 Builtin_call_expression::do_get_tree(Translate_context* context)
7302 {
7303   Gogo* gogo = context->gogo();
7304   source_location location = this->location();
7305   switch (this->code_)
7306     {
7307     case BUILTIN_INVALID:
7308     case BUILTIN_NEW:
7309     case BUILTIN_MAKE:
7310       gcc_unreachable();
7311
7312     case BUILTIN_LEN:
7313     case BUILTIN_CAP:
7314       {
7315         const Expression_list* args = this->args();
7316         gcc_assert(args != NULL && args->size() == 1);
7317         Expression* arg = *args->begin();
7318         Type* arg_type = arg->type();
7319         tree arg_tree = arg->get_tree(context);
7320         if (arg_tree == error_mark_node)
7321           return error_mark_node;
7322
7323         if (arg_type->points_to() != NULL)
7324           {
7325             arg_type = arg_type->points_to();
7326             gcc_assert(arg_type->array_type() != NULL
7327                        && !arg_type->is_open_array_type());
7328             gcc_assert(POINTER_TYPE_P(TREE_TYPE(arg_tree)));
7329             arg_tree = build_fold_indirect_ref(arg_tree);
7330           }
7331
7332         tree val_tree;
7333         if (this->code_ == BUILTIN_LEN)
7334           {
7335             if (arg_type->is_string_type())
7336               val_tree = String_type::length_tree(gogo, arg_tree);
7337             else if (arg_type->array_type() != NULL)
7338               val_tree = arg_type->array_type()->length_tree(gogo, arg_tree);
7339             else if (arg_type->map_type() != NULL)
7340               {
7341                 static tree map_len_fndecl;
7342                 val_tree = Gogo::call_builtin(&map_len_fndecl,
7343                                               location,
7344                                               "__go_map_len",
7345                                               1,
7346                                               sizetype,
7347                                               arg_type->get_tree(gogo),
7348                                               arg_tree);
7349               }
7350             else if (arg_type->channel_type() != NULL)
7351               {
7352                 static tree chan_len_fndecl;
7353                 val_tree = Gogo::call_builtin(&chan_len_fndecl,
7354                                               location,
7355                                               "__go_chan_len",
7356                                               1,
7357                                               sizetype,
7358                                               arg_type->get_tree(gogo),
7359                                               arg_tree);
7360               }
7361             else
7362               gcc_unreachable();
7363           }
7364         else
7365           {
7366             if (arg_type->array_type() != NULL)
7367               val_tree = arg_type->array_type()->capacity_tree(gogo, arg_tree);
7368             else if (arg_type->channel_type() != NULL)
7369               {
7370                 static tree chan_cap_fndecl;
7371                 val_tree = Gogo::call_builtin(&chan_cap_fndecl,
7372                                               location,
7373                                               "__go_chan_cap",
7374                                               1,
7375                                               sizetype,
7376                                               arg_type->get_tree(gogo),
7377                                               arg_tree);
7378               }
7379             else
7380               gcc_unreachable();
7381           }
7382
7383         tree type_tree = Type::lookup_integer_type("int")->get_tree(gogo);
7384         if (type_tree == TREE_TYPE(val_tree))
7385           return val_tree;
7386         else
7387           return fold(convert_to_integer(type_tree, val_tree));
7388       }
7389
7390     case BUILTIN_PRINT:
7391     case BUILTIN_PRINTLN:
7392       {
7393         const bool is_ln = this->code_ == BUILTIN_PRINTLN;
7394         tree stmt_list = NULL_TREE;
7395
7396         const Expression_list* call_args = this->args();
7397         if (call_args != NULL)
7398           {
7399             for (Expression_list::const_iterator p = call_args->begin();
7400                  p != call_args->end();
7401                  ++p)
7402               {
7403                 if (is_ln && p != call_args->begin())
7404                   {
7405                     static tree print_space_fndecl;
7406                     tree call = Gogo::call_builtin(&print_space_fndecl,
7407                                                    location,
7408                                                    "__go_print_space",
7409                                                    0,
7410                                                    void_type_node);
7411                     append_to_statement_list(call, &stmt_list);
7412                   }
7413
7414                 Type* type = (*p)->type();
7415
7416                 tree arg = (*p)->get_tree(context);
7417                 if (arg == error_mark_node)
7418                   return error_mark_node;
7419
7420                 tree* pfndecl;
7421                 const char* fnname;
7422                 if (type->is_string_type())
7423                   {
7424                     static tree print_string_fndecl;
7425                     pfndecl = &print_string_fndecl;
7426                     fnname = "__go_print_string";
7427                   }
7428                 else if (type->integer_type() != NULL
7429                          && type->integer_type()->is_unsigned())
7430                   {
7431                     static tree print_uint64_fndecl;
7432                     pfndecl = &print_uint64_fndecl;
7433                     fnname = "__go_print_uint64";
7434                     Type* itype = Type::lookup_integer_type("uint64");
7435                     arg = fold_convert_loc(location, itype->get_tree(gogo),
7436                                            arg);
7437                   }
7438                 else if (type->integer_type() != NULL)
7439                   {
7440                     static tree print_int64_fndecl;
7441                     pfndecl = &print_int64_fndecl;
7442                     fnname = "__go_print_int64";
7443                     Type* itype = Type::lookup_integer_type("int64");
7444                     arg = fold_convert_loc(location, itype->get_tree(gogo),
7445                                            arg);
7446                   }
7447                 else if (type->float_type() != NULL)
7448                   {
7449                     static tree print_double_fndecl;
7450                     pfndecl = &print_double_fndecl;
7451                     fnname = "__go_print_double";
7452                     arg = fold_convert_loc(location, double_type_node, arg);
7453                   }
7454                 else if (type->complex_type() != NULL)
7455                   {
7456                     static tree print_complex_fndecl;
7457                     pfndecl = &print_complex_fndecl;
7458                     fnname = "__go_print_complex";
7459                     arg = fold_convert_loc(location, complex_double_type_node,
7460                                            arg);
7461                   }
7462                 else if (type->is_boolean_type())
7463                   {
7464                     static tree print_bool_fndecl;
7465                     pfndecl = &print_bool_fndecl;
7466                     fnname = "__go_print_bool";
7467                   }
7468                 else if (type->points_to() != NULL
7469                          || type->channel_type() != NULL
7470                          || type->map_type() != NULL
7471                          || type->function_type() != NULL)
7472                   {
7473                     static tree print_pointer_fndecl;
7474                     pfndecl = &print_pointer_fndecl;
7475                     fnname = "__go_print_pointer";
7476                     arg = fold_convert_loc(location, ptr_type_node, arg);
7477                   }
7478                 else if (type->interface_type() != NULL)
7479                   {
7480                     if (type->interface_type()->is_empty())
7481                       {
7482                         static tree print_empty_interface_fndecl;
7483                         pfndecl = &print_empty_interface_fndecl;
7484                         fnname = "__go_print_empty_interface";
7485                       }
7486                     else
7487                       {
7488                         static tree print_interface_fndecl;
7489                         pfndecl = &print_interface_fndecl;
7490                         fnname = "__go_print_interface";
7491                       }
7492                   }
7493                 else if (type->is_open_array_type())
7494                   {
7495                     static tree print_slice_fndecl;
7496                     pfndecl = &print_slice_fndecl;
7497                     fnname = "__go_print_slice";
7498                   }
7499                 else
7500                   gcc_unreachable();
7501
7502                 tree call = Gogo::call_builtin(pfndecl,
7503                                                location,
7504                                                fnname,
7505                                                1,
7506                                                void_type_node,
7507                                                TREE_TYPE(arg),
7508                                                arg);
7509                 append_to_statement_list(call, &stmt_list);
7510               }
7511           }
7512
7513         if (is_ln)
7514           {
7515             static tree print_nl_fndecl;
7516             tree call = Gogo::call_builtin(&print_nl_fndecl,
7517                                            location,
7518                                            "__go_print_nl",
7519                                            0,
7520                                            void_type_node);
7521             append_to_statement_list(call, &stmt_list);
7522           }
7523
7524         return stmt_list;
7525       }
7526
7527     case BUILTIN_PANIC:
7528       {
7529         const Expression_list* args = this->args();
7530         gcc_assert(args != NULL && args->size() == 1);
7531         Expression* arg = args->front();
7532         tree arg_tree = arg->get_tree(context);
7533         if (arg_tree == error_mark_node)
7534           return error_mark_node;
7535         Type *empty = Type::make_interface_type(NULL, BUILTINS_LOCATION);
7536         arg_tree = Expression::convert_for_assignment(context, empty,
7537                                                       arg->type(),
7538                                                       arg_tree, location);
7539         static tree panic_fndecl;
7540         tree call = Gogo::call_builtin(&panic_fndecl,
7541                                        location,
7542                                        "__go_panic",
7543                                        1,
7544                                        void_type_node,
7545                                        TREE_TYPE(arg_tree),
7546                                        arg_tree);
7547         // This function will throw an exception.
7548         TREE_NOTHROW(panic_fndecl) = 0;
7549         // This function will not return.
7550         TREE_THIS_VOLATILE(panic_fndecl) = 1;
7551         return call;
7552       }
7553
7554     case BUILTIN_RECOVER:
7555       {
7556         // The argument is set when building recover thunks.  It's a
7557         // boolean value which is true if we can recover a value now.
7558         const Expression_list* args = this->args();
7559         gcc_assert(args != NULL && args->size() == 1);
7560         Expression* arg = args->front();
7561         tree arg_tree = arg->get_tree(context);
7562         if (arg_tree == error_mark_node)
7563           return error_mark_node;
7564
7565         Type *empty = Type::make_interface_type(NULL, BUILTINS_LOCATION);
7566         tree empty_tree = empty->get_tree(context->gogo());
7567
7568         Type* nil_type = Type::make_nil_type();
7569         Expression* nil = Expression::make_nil(location);
7570         tree nil_tree = nil->get_tree(context);
7571         tree empty_nil_tree = Expression::convert_for_assignment(context,
7572                                                                  empty,
7573                                                                  nil_type,
7574                                                                  nil_tree,
7575                                                                  location);
7576
7577         // We need to handle a deferred call to recover specially,
7578         // because it changes whether it can recover a panic or not.
7579         // See test7 in test/recover1.go.
7580         tree call;
7581         if (this->is_deferred())
7582           {
7583             static tree deferred_recover_fndecl;
7584             call = Gogo::call_builtin(&deferred_recover_fndecl,
7585                                       location,
7586                                       "__go_deferred_recover",
7587                                       0,
7588                                       empty_tree);
7589           }
7590         else
7591           {
7592             static tree recover_fndecl;
7593             call = Gogo::call_builtin(&recover_fndecl,
7594                                       location,
7595                                       "__go_recover",
7596                                       0,
7597                                       empty_tree);
7598           }
7599         return fold_build3_loc(location, COND_EXPR, empty_tree, arg_tree,
7600                                call, empty_nil_tree);
7601       }
7602
7603     case BUILTIN_CLOSE:
7604     case BUILTIN_CLOSED:
7605       {
7606         const Expression_list* args = this->args();
7607         gcc_assert(args != NULL && args->size() == 1);
7608         Expression* arg = args->front();
7609         tree arg_tree = arg->get_tree(context);
7610         if (arg_tree == error_mark_node)
7611           return error_mark_node;
7612         if (this->code_ == BUILTIN_CLOSE)
7613           {
7614             static tree close_fndecl;
7615             return Gogo::call_builtin(&close_fndecl,
7616                                       location,
7617                                       "__go_builtin_close",
7618                                       1,
7619                                       void_type_node,
7620                                       TREE_TYPE(arg_tree),
7621                                       arg_tree);
7622           }
7623         else
7624           {
7625             static tree closed_fndecl;
7626             return Gogo::call_builtin(&closed_fndecl,
7627                                       location,
7628                                       "__go_builtin_closed",
7629                                       1,
7630                                       boolean_type_node,
7631                                       TREE_TYPE(arg_tree),
7632                                       arg_tree);
7633           }
7634       }
7635
7636     case BUILTIN_SIZEOF:
7637     case BUILTIN_OFFSETOF:
7638     case BUILTIN_ALIGNOF:
7639       {
7640         mpz_t val;
7641         mpz_init(val);
7642         Type* dummy;
7643         bool b = this->integer_constant_value(true, val, &dummy);
7644         gcc_assert(b);
7645         tree type = Type::lookup_integer_type("int")->get_tree(gogo);
7646         tree ret = Expression::integer_constant_tree(val, type);
7647         mpz_clear(val);
7648         return ret;
7649       }
7650
7651     case BUILTIN_COPY:
7652       {
7653         const Expression_list* args = this->args();
7654         gcc_assert(args != NULL && args->size() == 2);
7655         Expression* arg1 = args->front();
7656         Expression* arg2 = args->back();
7657
7658         tree arg1_tree = arg1->get_tree(context);
7659         tree arg2_tree = arg2->get_tree(context);
7660         if (arg1_tree == error_mark_node || arg2_tree == error_mark_node)
7661           return error_mark_node;
7662
7663         Type* arg1_type = arg1->type();
7664         Array_type* at = arg1_type->array_type();
7665         arg1_tree = save_expr(arg1_tree);
7666         tree arg1_val = at->value_pointer_tree(gogo, arg1_tree);
7667         tree arg1_len = at->length_tree(gogo, arg1_tree);
7668
7669         Type* arg2_type = arg2->type();
7670         tree arg2_val;
7671         tree arg2_len;
7672         if (arg2_type->is_open_array_type())
7673           {
7674             at = arg2_type->array_type();
7675             arg2_tree = save_expr(arg2_tree);
7676             arg2_val = at->value_pointer_tree(gogo, arg2_tree);
7677             arg2_len = at->length_tree(gogo, arg2_tree);
7678           }
7679         else
7680           {
7681             arg2_tree = save_expr(arg2_tree);
7682             arg2_val = String_type::bytes_tree(gogo, arg2_tree);
7683             arg2_len = String_type::length_tree(gogo, arg2_tree);
7684           }
7685
7686         arg1_len = save_expr(arg1_len);
7687         arg2_len = save_expr(arg2_len);
7688         tree len = fold_build3_loc(location, COND_EXPR, TREE_TYPE(arg1_len),
7689                                    fold_build2_loc(location, LT_EXPR,
7690                                                    boolean_type_node,
7691                                                    arg1_len, arg2_len),
7692                                    arg1_len, arg2_len);
7693         len = save_expr(len);
7694
7695         Type* element_type = at->element_type();
7696         tree element_type_tree = element_type->get_tree(gogo);
7697         tree element_size = TYPE_SIZE_UNIT(element_type_tree);
7698         tree bytecount = fold_convert_loc(location, TREE_TYPE(element_size),
7699                                           len);
7700         bytecount = fold_build2_loc(location, MULT_EXPR,
7701                                     TREE_TYPE(element_size),
7702                                     bytecount, element_size);
7703         bytecount = fold_convert_loc(location, size_type_node, bytecount);
7704
7705         tree call = build_call_expr_loc(location,
7706                                         built_in_decls[BUILT_IN_MEMMOVE],
7707                                         3, arg1_val, arg2_val, bytecount);
7708
7709         return fold_build2_loc(location, COMPOUND_EXPR, TREE_TYPE(len),
7710                                call, len);
7711       }
7712
7713     case BUILTIN_APPEND:
7714       {
7715         const Expression_list* args = this->args();
7716         gcc_assert(args != NULL && args->size() == 2);
7717         Expression* arg1 = args->front();
7718         Expression* arg2 = args->back();
7719
7720         tree arg1_tree = arg1->get_tree(context);
7721         tree arg2_tree = arg2->get_tree(context);
7722         if (arg1_tree == error_mark_node || arg2_tree == error_mark_node)
7723           return error_mark_node;
7724
7725         tree descriptor_tree = arg1->type()->type_descriptor_pointer(gogo);
7726
7727         // We rebuild the decl each time since the slice types may
7728         // change.
7729         tree append_fndecl = NULL_TREE;
7730         return Gogo::call_builtin(&append_fndecl,
7731                                   location,
7732                                   "__go_append",
7733                                   3,
7734                                   TREE_TYPE(arg1_tree),
7735                                   TREE_TYPE(descriptor_tree),
7736                                   descriptor_tree,
7737                                   TREE_TYPE(arg1_tree),
7738                                   arg1_tree,
7739                                   TREE_TYPE(arg2_tree),
7740                                   arg2_tree);
7741       }
7742
7743     case BUILTIN_REAL:
7744     case BUILTIN_IMAG:
7745       {
7746         const Expression_list* args = this->args();
7747         gcc_assert(args != NULL && args->size() == 1);
7748         Expression* arg = args->front();
7749         tree arg_tree = arg->get_tree(context);
7750         if (arg_tree == error_mark_node)
7751           return error_mark_node;
7752         gcc_assert(COMPLEX_FLOAT_TYPE_P(TREE_TYPE(arg_tree)));
7753         if (this->code_ == BUILTIN_REAL)
7754           return fold_build1_loc(location, REALPART_EXPR,
7755                                  TREE_TYPE(TREE_TYPE(arg_tree)),
7756                                  arg_tree);
7757         else
7758           return fold_build1_loc(location, IMAGPART_EXPR,
7759                                  TREE_TYPE(TREE_TYPE(arg_tree)),
7760                                  arg_tree);
7761       }
7762
7763     case BUILTIN_CMPLX:
7764       {
7765         const Expression_list* args = this->args();
7766         gcc_assert(args != NULL && args->size() == 2);
7767         tree r = args->front()->get_tree(context);
7768         tree i = args->back()->get_tree(context);
7769         if (r == error_mark_node || i == error_mark_node)
7770           return error_mark_node;
7771         gcc_assert(TYPE_MAIN_VARIANT(TREE_TYPE(r))
7772                    == TYPE_MAIN_VARIANT(TREE_TYPE(i)));
7773         gcc_assert(SCALAR_FLOAT_TYPE_P(TREE_TYPE(r)));
7774         return fold_build2_loc(location, COMPLEX_EXPR,
7775                                build_complex_type(TREE_TYPE(r)),
7776                                r, i);
7777       }
7778
7779     default:
7780       gcc_unreachable();
7781     }
7782 }
7783
7784 // We have to support exporting a builtin call expression, because
7785 // code can set a constant to the result of a builtin expression.
7786
7787 void
7788 Builtin_call_expression::do_export(Export* exp) const
7789 {
7790   bool ok = false;
7791
7792   mpz_t val;
7793   mpz_init(val);
7794   Type* dummy;
7795   if (this->integer_constant_value(true, val, &dummy))
7796     {
7797       Integer_expression::export_integer(exp, val);
7798       ok = true;
7799     }
7800   mpz_clear(val);
7801
7802   if (!ok)
7803     {
7804       mpfr_t fval;
7805       mpfr_init(fval);
7806       if (this->float_constant_value(fval, &dummy))
7807         {
7808           Float_expression::export_float(exp, fval);
7809           ok = true;
7810         }
7811       mpfr_clear(fval);
7812     }
7813
7814   if (!ok)
7815     {
7816       mpfr_t real;
7817       mpfr_t imag;
7818       mpfr_init(real);
7819       mpfr_init(imag);
7820       if (this->complex_constant_value(real, imag, &dummy))
7821         {
7822           Complex_expression::export_complex(exp, real, imag);
7823           ok = true;
7824         }
7825       mpfr_clear(real);
7826       mpfr_clear(imag);
7827     }
7828
7829   if (!ok)
7830     {
7831       error_at(this->location(), "value is not constant");
7832       return;
7833     }
7834
7835   // A trailing space lets us reliably identify the end of the number.
7836   exp->write_c_string(" ");
7837 }
7838
7839 // Class Call_expression.
7840
7841 // Traversal.
7842
7843 int
7844 Call_expression::do_traverse(Traverse* traverse)
7845 {
7846   if (Expression::traverse(&this->fn_, traverse) == TRAVERSE_EXIT)
7847     return TRAVERSE_EXIT;
7848   if (this->args_ != NULL)
7849     {
7850       if (this->args_->traverse(traverse) == TRAVERSE_EXIT)
7851         return TRAVERSE_EXIT;
7852     }
7853   return TRAVERSE_CONTINUE;
7854 }
7855
7856 // Lower a call statement.
7857
7858 Expression*
7859 Call_expression::do_lower(Gogo* gogo, Named_object* function, int)
7860 {
7861   // A type case can look like a function call.
7862   if (this->fn_->is_type_expression()
7863       && this->args_ != NULL
7864       && this->args_->size() == 1)
7865     return Expression::make_cast(this->fn_->type(), this->args_->front(),
7866                                  this->location());
7867
7868   // Recognize a call to a builtin function.
7869   Func_expression* fne = this->fn_->func_expression();
7870   if (fne != NULL
7871       && fne->named_object()->is_function_declaration()
7872       && fne->named_object()->func_declaration_value()->type()->is_builtin())
7873     return new Builtin_call_expression(gogo, this->fn_, this->args_,
7874                                        this->is_varargs_, this->location());
7875
7876   // Handle an argument which is a call to a function which returns
7877   // multiple results.
7878   if (this->args_ != NULL
7879       && this->args_->size() == 1
7880       && this->args_->front()->call_expression() != NULL
7881       && this->fn_->type()->function_type() != NULL)
7882     {
7883       Function_type* fntype = this->fn_->type()->function_type();
7884       size_t rc = this->args_->front()->call_expression()->result_count();
7885       if (rc > 1
7886           && fntype->parameters() != NULL
7887           && (fntype->parameters()->size() == rc
7888               || (fntype->is_varargs()
7889                   && fntype->parameters()->size() - 1 <= rc)))
7890         {
7891           Call_expression* call = this->args_->front()->call_expression();
7892           Expression_list* args = new Expression_list;
7893           for (size_t i = 0; i < rc; ++i)
7894             args->push_back(Expression::make_call_result(call, i));
7895           // We can't return a new call expression here, because this
7896           // one may be referenced by Call_result expressions.  FIXME.
7897           delete this->args_;
7898           this->args_ = args;
7899         }
7900     }
7901
7902   // Handle a call to a varargs function by packaging up the extra
7903   // parameters.
7904   if (this->fn_->type()->function_type() != NULL
7905       && this->fn_->type()->function_type()->is_varargs())
7906     {
7907       Function_type* fntype = this->fn_->type()->function_type();
7908       const Typed_identifier_list* parameters = fntype->parameters();
7909       gcc_assert(parameters != NULL && !parameters->empty());
7910       Type* varargs_type = parameters->back().type();
7911       return this->lower_varargs(gogo, function, varargs_type,
7912                                  parameters->size());
7913     }
7914
7915   return this;
7916 }
7917
7918 // Lower a call to a varargs function.  FUNCTION is the function in
7919 // which the call occurs--it's not the function we are calling.
7920 // VARARGS_TYPE is the type of the varargs parameter, a slice type.
7921 // PARAM_COUNT is the number of parameters of the function we are
7922 // calling; the last of these parameters will be the varargs
7923 // parameter.
7924
7925 Expression*
7926 Call_expression::lower_varargs(Gogo* gogo, Named_object* function,
7927                                Type* varargs_type, size_t param_count)
7928 {
7929   if (this->varargs_are_lowered_)
7930     return this;
7931
7932   source_location loc = this->location();
7933
7934   gcc_assert(param_count > 0);
7935   gcc_assert(varargs_type->is_open_array_type());
7936
7937   size_t arg_count = this->args_ == NULL ? 0 : this->args_->size();
7938   if (arg_count < param_count - 1)
7939     {
7940       // Not enough arguments; will be caught in check_types.
7941       return this;
7942     }
7943
7944   Expression_list* old_args = this->args_;
7945   Expression_list* new_args = new Expression_list();
7946   bool push_empty_arg = false;
7947   if (old_args == NULL || old_args->empty())
7948     {
7949       gcc_assert(param_count == 1);
7950       push_empty_arg = true;
7951     }
7952   else
7953     {
7954       Expression_list::const_iterator pa;
7955       int i = 1;
7956       for (pa = old_args->begin(); pa != old_args->end(); ++pa, ++i)
7957         {
7958           if (static_cast<size_t>(i) == param_count)
7959             break;
7960           new_args->push_back(*pa);
7961         }
7962
7963       // We have reached the varargs parameter.
7964
7965       bool issued_error = false;
7966       if (pa == old_args->end())
7967         push_empty_arg = true;
7968       else if (pa + 1 == old_args->end() && this->is_varargs_)
7969         new_args->push_back(*pa);
7970       else if (this->is_varargs_)
7971         {
7972           this->report_error(_("too many arguments"));
7973           return this;
7974         }
7975       else if (pa + 1 == old_args->end()
7976                && this->is_compatible_varargs_argument(function, *pa,
7977                                                        varargs_type,
7978                                                        &issued_error))
7979         new_args->push_back(*pa);
7980       else
7981         {
7982           Type* element_type = varargs_type->array_type()->element_type();
7983           Expression_list* vals = new Expression_list;
7984           for (; pa != old_args->end(); ++pa, ++i)
7985             {
7986               // Check types here so that we get a better message.
7987               Type* patype = (*pa)->type();
7988               source_location paloc = (*pa)->location();
7989               if (!this->check_argument_type(i, element_type, patype,
7990                                              paloc, issued_error))
7991                 continue;
7992               vals->push_back(*pa);
7993             }
7994           Expression* val =
7995             Expression::make_slice_composite_literal(varargs_type, vals, loc);
7996           new_args->push_back(val);
7997         }
7998     }
7999
8000   if (push_empty_arg)
8001     new_args->push_back(Expression::make_nil(loc));
8002
8003   // We can't return a new call expression here, because this one may
8004   // be referenced by Call_result expressions.  FIXME.
8005   if (old_args != NULL)
8006     delete old_args;
8007   this->args_ = new_args;
8008   this->varargs_are_lowered_ = true;
8009
8010   // Lower all the new subexpressions.
8011   Expression* ret = this;
8012   gogo->lower_expression(function, &ret);
8013   gcc_assert(ret == this);
8014   return ret;
8015 }
8016
8017 // Return true if ARG is a varargs argment which should be passed to
8018 // the varargs parameter of type PARAM_TYPE without wrapping.  ARG
8019 // will be the last argument passed in the call, and PARAM_TYPE will
8020 // be the type of the last parameter of the varargs function being
8021 // called.
8022
8023 bool
8024 Call_expression::is_compatible_varargs_argument(Named_object* function,
8025                                                 Expression* arg,
8026                                                 Type* param_type,
8027                                                 bool* issued_error)
8028 {
8029   *issued_error = false;
8030
8031   Type* var_type = NULL;
8032
8033   // The simple case is passing the varargs parameter of the caller.
8034   Var_expression* ve = arg->var_expression();
8035   if (ve != NULL && ve->named_object()->is_variable())
8036     {
8037       Variable* var = ve->named_object()->var_value();
8038       if (var->is_varargs_parameter())
8039         var_type = var->type();
8040     }
8041
8042   // The complex case is passing the varargs parameter of some
8043   // enclosing function.  This will look like passing down *c.f where
8044   // c is the closure variable and f is a field in the closure.
8045   if (function != NULL
8046       && function->func_value()->needs_closure()
8047       && arg->classification() == EXPRESSION_UNARY)
8048     {
8049       Unary_expression* ue = static_cast<Unary_expression*>(arg);
8050       if (ue->op() == OPERATOR_MULT)
8051         {
8052           Field_reference_expression* fre =
8053             ue->operand()->deref()->field_reference_expression();
8054           if (fre != NULL)
8055             {
8056               Var_expression* ve = fre->expr()->deref()->var_expression();
8057               if (ve != NULL)
8058                 {
8059                   Named_object* no = ve->named_object();
8060                   Function* f = function->func_value();
8061                   if (no == f->closure_var())
8062                     {
8063                       // At this point we know that this indeed a
8064                       // reference to some enclosing variable.  Now we
8065                       // need to figure out whether that variable is a
8066                       // varargs parameter.
8067                       Named_object* enclosing =
8068                         f->enclosing_var(fre->field_index());
8069                       Variable* var = enclosing->var_value();
8070                       if (var->is_varargs_parameter())
8071                         var_type = var->type();
8072                     }
8073                 }
8074             }
8075         }
8076     }
8077
8078   if (var_type == NULL)
8079     return false;
8080
8081   // We only match if the parameter is the same, with an identical
8082   // type.
8083   Array_type* var_at = var_type->array_type();
8084   gcc_assert(var_at != NULL);
8085   Array_type* param_at = param_type->array_type();
8086   if (param_at != NULL
8087       && Type::are_identical(var_at->element_type(),
8088                              param_at->element_type(), NULL))
8089     return true;
8090   error_at(arg->location(), "... mismatch: passing ...T as ...");
8091   *issued_error = true;
8092   return false;
8093 }
8094
8095 // Get the function type.  Returns NULL if we don't know the type.  If
8096 // this returns NULL, and if_ERROR is true, issues an error.
8097
8098 Function_type*
8099 Call_expression::get_function_type() const
8100 {
8101   return this->fn_->type()->function_type();
8102 }
8103
8104 // Return the number of values which this call will return.
8105
8106 size_t
8107 Call_expression::result_count() const
8108 {
8109   const Function_type* fntype = this->get_function_type();
8110   if (fntype == NULL)
8111     return 0;
8112   if (fntype->results() == NULL)
8113     return 0;
8114   return fntype->results()->size();
8115 }
8116
8117 // Return whether this is a call to the predeclared function recover.
8118
8119 bool
8120 Call_expression::is_recover_call() const
8121 {
8122   return this->do_is_recover_call();
8123 }
8124
8125 // Set the argument to the recover function.
8126
8127 void
8128 Call_expression::set_recover_arg(Expression* arg)
8129 {
8130   this->do_set_recover_arg(arg);
8131 }
8132
8133 // Virtual functions also implemented by Builtin_call_expression.
8134
8135 bool
8136 Call_expression::do_is_recover_call() const
8137 {
8138   return false;
8139 }
8140
8141 void
8142 Call_expression::do_set_recover_arg(Expression*)
8143 {
8144   gcc_unreachable();
8145 }
8146
8147 // Get the type.
8148
8149 Type*
8150 Call_expression::do_type()
8151 {
8152   if (this->type_ != NULL)
8153     return this->type_;
8154
8155   Type* ret;
8156   Function_type* fntype = this->get_function_type();
8157   if (fntype == NULL)
8158     return Type::make_error_type();
8159
8160   const Typed_identifier_list* results = fntype->results();
8161   if (results == NULL)
8162     ret = Type::make_void_type();
8163   else if (results->size() == 1)
8164     ret = results->begin()->type();
8165   else
8166     ret = Type::make_call_multiple_result_type(this);
8167
8168   this->type_ = ret;
8169
8170   return this->type_;
8171 }
8172
8173 // Determine types for a call expression.  We can use the function
8174 // parameter types to set the types of the arguments.
8175
8176 void
8177 Call_expression::do_determine_type(const Type_context*)
8178 {
8179   this->fn_->determine_type_no_context();
8180   Function_type* fntype = this->get_function_type();
8181   const Typed_identifier_list* parameters = NULL;
8182   if (fntype != NULL)
8183     parameters = fntype->parameters();
8184   if (this->args_ != NULL)
8185     {
8186       Typed_identifier_list::const_iterator pt;
8187       if (parameters != NULL)
8188         pt = parameters->begin();
8189       for (Expression_list::const_iterator pa = this->args_->begin();
8190            pa != this->args_->end();
8191            ++pa)
8192         {
8193           if (parameters != NULL && pt != parameters->end())
8194             {
8195               Type_context subcontext(pt->type(), false);
8196               (*pa)->determine_type(&subcontext);
8197               ++pt;
8198             }
8199           else
8200             (*pa)->determine_type_no_context();
8201         }
8202     }
8203 }
8204
8205 // Check types for parameter I.
8206
8207 bool
8208 Call_expression::check_argument_type(int i, const Type* parameter_type,
8209                                      const Type* argument_type,
8210                                      source_location argument_location,
8211                                      bool issued_error)
8212 {
8213   std::string reason;
8214   if (!Type::are_assignable(parameter_type, argument_type, &reason))
8215     {
8216       if (!issued_error)
8217         {
8218           if (reason.empty())
8219             error_at(argument_location, "argument %d has incompatible type", i);
8220           else
8221             error_at(argument_location,
8222                      "argument %d has incompatible type (%s)",
8223                      i, reason.c_str());
8224         }
8225       this->set_is_error();
8226       return false;
8227     }
8228   return true;
8229 }
8230
8231 // Check types.
8232
8233 void
8234 Call_expression::do_check_types(Gogo*)
8235 {
8236   Function_type* fntype = this->get_function_type();
8237   if (fntype == NULL)
8238     {
8239       if (!this->fn_->type()->is_error_type())
8240         this->report_error(_("expected function"));
8241       return;
8242     }
8243
8244   if (fntype->is_method())
8245     {
8246       // We don't support pointers to methods, so the function has to
8247       // be a bound method expression.
8248       Bound_method_expression* bme = this->fn_->bound_method_expression();
8249       if (bme == NULL)
8250         {
8251           this->report_error(_("method call without object"));
8252           return;
8253         }
8254       Type* first_arg_type = bme->first_argument()->type();
8255       if (first_arg_type->points_to() == NULL)
8256         {
8257           // When passing a value, we need to check that we are
8258           // permitted to copy it.
8259           std::string reason;
8260           if (!Type::are_assignable(fntype->receiver()->type(),
8261                                     first_arg_type, &reason))
8262             {
8263               if (reason.empty())
8264                 this->report_error(_("incompatible type for receiver"));
8265               else
8266                 {
8267                   error_at(this->location(),
8268                            "incompatible type for receiver (%s)",
8269                            reason.c_str());
8270                   this->set_is_error();
8271                 }
8272             }
8273         }
8274     }
8275
8276   // Note that varargs was handled by the lower_varargs() method, so
8277   // we don't have to worry about it here.
8278
8279   const Typed_identifier_list* parameters = fntype->parameters();
8280   if (this->args_ == NULL)
8281     {
8282       if (parameters != NULL && !parameters->empty())
8283         this->report_error(_("not enough arguments"));
8284     }
8285   else if (parameters == NULL)
8286     this->report_error(_("too many arguments"));
8287   else
8288     {
8289       int i = 0;
8290       Typed_identifier_list::const_iterator pt = parameters->begin();
8291       for (Expression_list::const_iterator pa = this->args_->begin();
8292            pa != this->args_->end();
8293            ++pa, ++pt, ++i)
8294         {
8295           if (pt == parameters->end())
8296             {
8297               this->report_error(_("too many arguments"));
8298               return;
8299             }
8300           this->check_argument_type(i + 1, pt->type(), (*pa)->type(),
8301                                     (*pa)->location(), false);
8302         }
8303       if (pt != parameters->end())
8304         this->report_error(_("not enough arguments"));
8305     }
8306 }
8307
8308 // Return whether we have to use a temporary variable to ensure that
8309 // we evaluate this call expression in order.  If the call returns no
8310 // results then it will inevitably be executed last.  If the call
8311 // returns more than one result then it will be used with Call_result
8312 // expressions.  So we only have to use a temporary variable if the
8313 // call returns exactly one result.
8314
8315 bool
8316 Call_expression::do_must_eval_in_order() const
8317 {
8318   return this->result_count() == 1;
8319 }
8320
8321 // Get the function and the first argument to use when calling a bound
8322 // method.
8323
8324 tree
8325 Call_expression::bound_method_function(Translate_context* context,
8326                                        Bound_method_expression* bound_method,
8327                                        tree* first_arg_ptr)
8328 {
8329   Expression* first_argument = bound_method->first_argument();
8330   tree first_arg = first_argument->get_tree(context);
8331   if (first_arg == error_mark_node)
8332     return error_mark_node;
8333
8334   // We always pass a pointer to the first argument when calling a
8335   // method.
8336   if (first_argument->type()->points_to() == NULL)
8337     {
8338       tree pointer_to_arg_type = build_pointer_type(TREE_TYPE(first_arg));
8339       if (TREE_ADDRESSABLE(TREE_TYPE(first_arg))
8340           || DECL_P(first_arg)
8341           || TREE_CODE(first_arg) == INDIRECT_REF
8342           || TREE_CODE(first_arg) == COMPONENT_REF)
8343         {
8344           first_arg = build_fold_addr_expr(first_arg);
8345           if (DECL_P(first_arg))
8346             TREE_ADDRESSABLE(first_arg) = 1;
8347         }
8348       else
8349         {
8350           tree tmp = create_tmp_var(TREE_TYPE(first_arg),
8351                                     get_name(first_arg));
8352           DECL_IGNORED_P(tmp) = 0;
8353           DECL_INITIAL(tmp) = first_arg;
8354           first_arg = build2(COMPOUND_EXPR, pointer_to_arg_type,
8355                              build1(DECL_EXPR, void_type_node, tmp),
8356                              build_fold_addr_expr(tmp));
8357           TREE_ADDRESSABLE(tmp) = 1;
8358         }
8359       if (first_arg == error_mark_node)
8360         return error_mark_node;
8361     }
8362
8363   Type* fatype = bound_method->first_argument_type();
8364   if (fatype != NULL)
8365     {
8366       if (fatype->points_to() == NULL)
8367         fatype = Type::make_pointer_type(fatype);
8368       first_arg = fold_convert(fatype->get_tree(context->gogo()), first_arg);
8369       if (first_arg == error_mark_node
8370           || TREE_TYPE(first_arg) == error_mark_node)
8371         return error_mark_node;
8372     }
8373
8374   *first_arg_ptr = first_arg;
8375
8376   return bound_method->method()->get_tree(context);
8377 }
8378
8379 // Get the function and the first argument to use when calling an
8380 // interface method.
8381
8382 tree
8383 Call_expression::interface_method_function(
8384     Translate_context* context,
8385     Interface_field_reference_expression* interface_method,
8386     tree* first_arg_ptr)
8387 {
8388   tree expr = interface_method->expr()->get_tree(context);
8389   if (expr == error_mark_node)
8390     return error_mark_node;
8391   expr = save_expr(expr);
8392   tree first_arg = interface_method->get_underlying_object_tree(context, expr);
8393   if (first_arg == error_mark_node)
8394     return error_mark_node;
8395   *first_arg_ptr = first_arg;
8396   return interface_method->get_function_tree(context, expr);
8397 }
8398
8399 // Build the call expression.
8400
8401 tree
8402 Call_expression::do_get_tree(Translate_context* context)
8403 {
8404   if (this->tree_ != NULL_TREE)
8405     return this->tree_;
8406
8407   Function_type* fntype = this->get_function_type();
8408   if (fntype == NULL)
8409     return error_mark_node;
8410
8411   if (this->fn_->is_error_expression())
8412     return error_mark_node;
8413
8414   Gogo* gogo = context->gogo();
8415   source_location location = this->location();
8416
8417   Func_expression* func = this->fn_->func_expression();
8418   Bound_method_expression* bound_method = this->fn_->bound_method_expression();
8419   Interface_field_reference_expression* interface_method =
8420     this->fn_->interface_field_reference_expression();
8421   const bool has_closure = func != NULL && func->closure() != NULL;
8422   const bool is_method = bound_method != NULL || interface_method != NULL;
8423   gcc_assert(!fntype->is_method() || is_method);
8424
8425   int nargs;
8426   tree* args;
8427   if (this->args_ == NULL || this->args_->empty())
8428     {
8429       nargs = is_method ? 1 : 0;
8430       args = nargs == 0 ? NULL : new tree[nargs];
8431     }
8432   else
8433     {
8434       const Typed_identifier_list* params = fntype->parameters();
8435       gcc_assert(params != NULL);
8436
8437       nargs = this->args_->size();
8438       int i = is_method ? 1 : 0;
8439       nargs += i;
8440       args = new tree[nargs];
8441
8442       Typed_identifier_list::const_iterator pp = params->begin();
8443       Expression_list::const_iterator pe;
8444       for (pe = this->args_->begin();
8445            pe != this->args_->end();
8446            ++pe, ++pp, ++i)
8447         {
8448           tree arg_val = (*pe)->get_tree(context);
8449           args[i] = Expression::convert_for_assignment(context,
8450                                                        pp->type(),
8451                                                        (*pe)->type(),
8452                                                        arg_val,
8453                                                        location);
8454           if (args[i] == error_mark_node)
8455             return error_mark_node;
8456         }
8457       gcc_assert(pp == params->end());
8458       gcc_assert(i == nargs);
8459     }
8460
8461   tree rettype = TREE_TYPE(TREE_TYPE(fntype->get_tree(gogo)));
8462   if (rettype == error_mark_node)
8463     return error_mark_node;
8464
8465   tree fn;
8466   if (has_closure)
8467     fn = func->get_tree_without_closure(gogo);
8468   else if (!is_method)
8469     fn = this->fn_->get_tree(context);
8470   else if (bound_method != NULL)
8471     fn = this->bound_method_function(context, bound_method, &args[0]);
8472   else if (interface_method != NULL)
8473     fn = this->interface_method_function(context, interface_method, &args[0]);
8474   else
8475     gcc_unreachable();
8476
8477   if (fn == error_mark_node || TREE_TYPE(fn) == error_mark_node)
8478     return error_mark_node;
8479
8480   // This is to support builtin math functions when using 80387 math.
8481   tree fndecl = fn;
8482   if (TREE_CODE(fndecl) == ADDR_EXPR)
8483     fndecl = TREE_OPERAND(fndecl, 0);
8484   tree excess_type = NULL_TREE;
8485   if (DECL_P(fndecl)
8486       && DECL_IS_BUILTIN(fndecl)
8487       && DECL_BUILT_IN_CLASS(fndecl) == BUILT_IN_NORMAL
8488       && nargs > 0
8489       && ((SCALAR_FLOAT_TYPE_P(rettype)
8490            && SCALAR_FLOAT_TYPE_P(TREE_TYPE(args[0])))
8491           || (COMPLEX_FLOAT_TYPE_P(rettype)
8492               && COMPLEX_FLOAT_TYPE_P(TREE_TYPE(args[0])))))
8493     {
8494       excess_type = excess_precision_type(TREE_TYPE(args[0]));
8495       if (excess_type != NULL_TREE)
8496         {
8497           tree excess_fndecl = mathfn_built_in(excess_type,
8498                                                DECL_FUNCTION_CODE(fndecl));
8499           if (excess_fndecl == NULL_TREE)
8500             excess_type = NULL_TREE;
8501           else
8502             {
8503               fn = build_fold_addr_expr_loc(location, excess_fndecl);
8504               for (int i = 0; i < nargs; ++i)
8505                 args[i] = ::convert(excess_type, args[i]);
8506             }
8507         }
8508     }
8509
8510   tree ret = build_call_array(excess_type != NULL_TREE ? excess_type : rettype,
8511                               fn, nargs, args);
8512   delete[] args;
8513
8514   SET_EXPR_LOCATION(ret, location);
8515
8516   if (has_closure)
8517     {
8518       tree closure_tree = func->closure()->get_tree(context);
8519       if (closure_tree != error_mark_node)
8520         CALL_EXPR_STATIC_CHAIN(ret) = closure_tree;
8521     }
8522
8523   // If this is a recursive function type which returns itself, as in
8524   //   type F func() F
8525   // we have used ptr_type_node for the return type.  Add a cast here
8526   // to the correct type.
8527   if (TREE_TYPE(ret) == ptr_type_node)
8528     {
8529       tree t = this->type()->get_tree(gogo);
8530       ret = fold_convert_loc(location, t, ret);
8531     }
8532
8533   if (excess_type != NULL_TREE)
8534     {
8535       // Calling convert here can undo our excess precision change.
8536       // That may or may not be a bug in convert_to_real.
8537       ret = build1(NOP_EXPR, rettype, ret);
8538     }
8539
8540   // If there is more than one result, we will refer to the call
8541   // multiple times.
8542   if (fntype->results() != NULL && fntype->results()->size() > 1)
8543     ret = save_expr(ret);
8544
8545   this->tree_ = ret;
8546
8547   return ret;
8548 }
8549
8550 // Make a call expression.
8551
8552 Call_expression*
8553 Expression::make_call(Expression* fn, Expression_list* args, bool is_varargs,
8554                       source_location location)
8555 {
8556   return new Call_expression(fn, args, is_varargs, location);
8557 }
8558
8559 // A single result from a call which returns multiple results.
8560
8561 class Call_result_expression : public Expression
8562 {
8563  public:
8564   Call_result_expression(Call_expression* call, unsigned int index)
8565     : Expression(EXPRESSION_CALL_RESULT, call->location()),
8566       call_(call), index_(index)
8567   { }
8568
8569  protected:
8570   int
8571   do_traverse(Traverse*);
8572
8573   Type*
8574   do_type();
8575
8576   void
8577   do_determine_type(const Type_context*);
8578
8579   void
8580   do_check_types(Gogo*);
8581
8582   Expression*
8583   do_copy()
8584   {
8585     return new Call_result_expression(this->call_->call_expression(),
8586                                       this->index_);
8587   }
8588
8589   bool
8590   do_must_eval_in_order() const
8591   { return true; }
8592
8593   tree
8594   do_get_tree(Translate_context*);
8595
8596  private:
8597   // The underlying call expression.
8598   Expression* call_;
8599   // Which result we want.
8600   unsigned int index_;
8601 };
8602
8603 // Traverse a call result.
8604
8605 int
8606 Call_result_expression::do_traverse(Traverse* traverse)
8607 {
8608   if (traverse->remember_expression(this->call_))
8609     {
8610       // We have already traversed the call expression.
8611       return TRAVERSE_CONTINUE;
8612     }
8613   return Expression::traverse(&this->call_, traverse);
8614 }
8615
8616 // Get the type.
8617
8618 Type*
8619 Call_result_expression::do_type()
8620 {
8621   // THIS->CALL_ can be replaced with a temporary reference due to
8622   // Call_expression::do_must_eval_in_order when there is an error.
8623   Call_expression* ce = this->call_->call_expression();
8624   if (ce == NULL)
8625     return Type::make_error_type();
8626   Function_type* fntype = ce->get_function_type();
8627   if (fntype == NULL)
8628     return Type::make_error_type();
8629   const Typed_identifier_list* results = fntype->results();
8630   Typed_identifier_list::const_iterator pr = results->begin();
8631   for (unsigned int i = 0; i < this->index_; ++i)
8632     {
8633       if (pr == results->end())
8634         return Type::make_error_type();
8635       ++pr;
8636     }
8637   if (pr == results->end())
8638     return Type::make_error_type();
8639   return pr->type();
8640 }
8641
8642 // Check the type.  This is where we give an error if we're trying to
8643 // extract too many values from a call.
8644
8645 void
8646 Call_result_expression::do_check_types(Gogo*)
8647 {
8648   bool ok = true;
8649   Call_expression* ce = this->call_->call_expression();
8650   if (ce != NULL)
8651     ok = this->index_ < ce->result_count();
8652   else
8653     {
8654       // This can happen when the call returns a single value but we
8655       // are asking for the second result.
8656       if (this->call_->is_error_expression())
8657         return;
8658       ok = false;
8659     }
8660   if (!ok)
8661     this->report_error(_("number of results does not match number of values"));
8662 }
8663
8664 // Determine the type.  We have nothing to do here, but the 0 result
8665 // needs to pass down to the caller.
8666
8667 void
8668 Call_result_expression::do_determine_type(const Type_context*)
8669 {
8670   if (this->index_ == 0)
8671     this->call_->determine_type_no_context();
8672 }
8673
8674 // Return the tree.
8675
8676 tree
8677 Call_result_expression::do_get_tree(Translate_context* context)
8678 {
8679   tree call_tree = this->call_->get_tree(context);
8680   if (call_tree == error_mark_node)
8681     return error_mark_node;
8682   gcc_assert(TREE_CODE(TREE_TYPE(call_tree)) == RECORD_TYPE);
8683   tree field = TYPE_FIELDS(TREE_TYPE(call_tree));
8684   for (unsigned int i = 0; i < this->index_; ++i)
8685     {
8686       gcc_assert(field != NULL_TREE);
8687       field = DECL_CHAIN(field);
8688     }
8689   gcc_assert(field != NULL_TREE);
8690   return build3(COMPONENT_REF, TREE_TYPE(field), call_tree, field, NULL_TREE);
8691 }
8692
8693 // Make a reference to a single result of a call which returns
8694 // multiple results.
8695
8696 Expression*
8697 Expression::make_call_result(Call_expression* call, unsigned int index)
8698 {
8699   return new Call_result_expression(call, index);
8700 }
8701
8702 // Class Index_expression.
8703
8704 // Traversal.
8705
8706 int
8707 Index_expression::do_traverse(Traverse* traverse)
8708 {
8709   if (Expression::traverse(&this->left_, traverse) == TRAVERSE_EXIT
8710       || Expression::traverse(&this->start_, traverse) == TRAVERSE_EXIT
8711       || (this->end_ != NULL
8712           && Expression::traverse(&this->end_, traverse) == TRAVERSE_EXIT))
8713     return TRAVERSE_EXIT;
8714   return TRAVERSE_CONTINUE;
8715 }
8716
8717 // Lower an index expression.  This converts the generic index
8718 // expression into an array index, a string index, or a map index.
8719
8720 Expression*
8721 Index_expression::do_lower(Gogo*, Named_object*, int)
8722 {
8723   source_location location = this->location();
8724   Expression* left = this->left_;
8725   Expression* start = this->start_;
8726   Expression* end = this->end_;
8727
8728   Type* type = left->type();
8729   if (type->is_error_type())
8730     return Expression::make_error(location);
8731   else if (type->array_type() != NULL)
8732     return Expression::make_array_index(left, start, end, location);
8733   else if (type->points_to() != NULL
8734            && type->points_to()->array_type() != NULL
8735            && !type->points_to()->is_open_array_type())
8736     {
8737       Expression* deref = Expression::make_unary(OPERATOR_MULT, left,
8738                                                  location);
8739       return Expression::make_array_index(deref, start, end, location);
8740     }
8741   else if (type->is_string_type())
8742     return Expression::make_string_index(left, start, end, location);
8743   else if (type->map_type() != NULL)
8744     {
8745       if (end != NULL)
8746         {
8747           error_at(location, "invalid slice of map");
8748           return Expression::make_error(location);
8749         }
8750       Map_index_expression* ret= Expression::make_map_index(left, start,
8751                                                             location);
8752       if (this->is_lvalue_)
8753         ret->set_is_lvalue();
8754       return ret;
8755     }
8756   else
8757     {
8758       error_at(location,
8759                "attempt to index object which is not array, string, or map");
8760       return Expression::make_error(location);
8761     }
8762 }
8763
8764 // Make an index expression.
8765
8766 Expression*
8767 Expression::make_index(Expression* left, Expression* start, Expression* end,
8768                        source_location location)
8769 {
8770   return new Index_expression(left, start, end, location);
8771 }
8772
8773 // An array index.  This is used for both indexing and slicing.
8774
8775 class Array_index_expression : public Expression
8776 {
8777  public:
8778   Array_index_expression(Expression* array, Expression* start,
8779                          Expression* end, source_location location)
8780     : Expression(EXPRESSION_ARRAY_INDEX, location),
8781       array_(array), start_(start), end_(end), type_(NULL)
8782   { }
8783
8784  protected:
8785   int
8786   do_traverse(Traverse*);
8787
8788   Type*
8789   do_type();
8790
8791   void
8792   do_determine_type(const Type_context*);
8793
8794   void
8795   do_check_types(Gogo*);
8796
8797   Expression*
8798   do_copy()
8799   {
8800     return Expression::make_array_index(this->array_->copy(),
8801                                         this->start_->copy(),
8802                                         (this->end_ == NULL
8803                                          ? NULL
8804                                          : this->end_->copy()),
8805                                         this->location());
8806   }
8807
8808   bool
8809   do_is_addressable() const;
8810
8811   void
8812   do_address_taken(bool escapes)
8813   { this->array_->address_taken(escapes); }
8814
8815   tree
8816   do_get_tree(Translate_context*);
8817
8818  private:
8819   // The array we are getting a value from.
8820   Expression* array_;
8821   // The start or only index.
8822   Expression* start_;
8823   // The end index of a slice.  This may be NULL for a simple array
8824   // index, or it may be a nil expression for the length of the array.
8825   Expression* end_;
8826   // The type of the expression.
8827   Type* type_;
8828 };
8829
8830 // Array index traversal.
8831
8832 int
8833 Array_index_expression::do_traverse(Traverse* traverse)
8834 {
8835   if (Expression::traverse(&this->array_, traverse) == TRAVERSE_EXIT)
8836     return TRAVERSE_EXIT;
8837   if (Expression::traverse(&this->start_, traverse) == TRAVERSE_EXIT)
8838     return TRAVERSE_EXIT;
8839   if (this->end_ != NULL)
8840     {
8841       if (Expression::traverse(&this->end_, traverse) == TRAVERSE_EXIT)
8842         return TRAVERSE_EXIT;
8843     }
8844   return TRAVERSE_CONTINUE;
8845 }
8846
8847 // Return the type of an array index.
8848
8849 Type*
8850 Array_index_expression::do_type()
8851 {
8852   if (this->type_ == NULL)
8853     {
8854      Array_type* type = this->array_->type()->array_type();
8855       if (type == NULL)
8856         this->type_ = Type::make_error_type();
8857       else if (this->end_ == NULL)
8858         this->type_ = type->element_type();
8859       else if (type->is_open_array_type())
8860         {
8861           // A slice of a slice has the same type as the original
8862           // slice.
8863           this->type_ = this->array_->type()->deref();
8864         }
8865       else
8866         {
8867           // A slice of an array is a slice.
8868           this->type_ = Type::make_array_type(type->element_type(), NULL);
8869         }
8870     }
8871   return this->type_;
8872 }
8873
8874 // Set the type of an array index.
8875
8876 void
8877 Array_index_expression::do_determine_type(const Type_context*)
8878 {
8879   this->array_->determine_type_no_context();
8880   Type_context subcontext(NULL, true);
8881   this->start_->determine_type(&subcontext);
8882   if (this->end_ != NULL)
8883     this->end_->determine_type(&subcontext);
8884 }
8885
8886 // Check types of an array index.
8887
8888 void
8889 Array_index_expression::do_check_types(Gogo*)
8890 {
8891   if (this->start_->type()->integer_type() == NULL)
8892     this->report_error(_("index must be integer"));
8893   if (this->end_ != NULL
8894       && this->end_->type()->integer_type() == NULL
8895       && !this->end_->is_nil_expression())
8896     this->report_error(_("slice end must be integer"));
8897
8898   Array_type* array_type = this->array_->type()->array_type();
8899   gcc_assert(array_type != NULL);
8900
8901   unsigned int int_bits =
8902     Type::lookup_integer_type("int")->integer_type()->bits();
8903
8904   Type* dummy;
8905   mpz_t lval;
8906   mpz_init(lval);
8907   bool lval_valid = (array_type->length() != NULL
8908                      && array_type->length()->integer_constant_value(true,
8909                                                                      lval,
8910                                                                      &dummy));
8911   mpz_t ival;
8912   mpz_init(ival);
8913   if (this->start_->integer_constant_value(true, ival, &dummy))
8914     {
8915       if (mpz_sgn(ival) < 0
8916           || mpz_sizeinbase(ival, 2) >= int_bits
8917           || (lval_valid
8918               && (this->end_ == NULL
8919                   ? mpz_cmp(ival, lval) >= 0
8920                   : mpz_cmp(ival, lval) > 0)))
8921         {
8922           error_at(this->start_->location(), "array index out of bounds");
8923           this->set_is_error();
8924         }
8925     }
8926   if (this->end_ != NULL && !this->end_->is_nil_expression())
8927     {
8928       if (this->end_->integer_constant_value(true, ival, &dummy))
8929         {
8930           if (mpz_sgn(ival) < 0
8931               || mpz_sizeinbase(ival, 2) >= int_bits
8932               || (lval_valid && mpz_cmp(ival, lval) > 0))
8933             {
8934               error_at(this->end_->location(), "array index out of bounds");
8935               this->set_is_error();
8936             }
8937         }
8938     }
8939   mpz_clear(ival);
8940   mpz_clear(lval);
8941
8942   // A slice of an array requires an addressable array.  A slice of a
8943   // slice is always possible.
8944   if (this->end_ != NULL
8945       && !array_type->is_open_array_type()
8946       && !this->array_->is_addressable())
8947     this->report_error(_("array is not addressable"));
8948 }
8949
8950 // Return whether this expression is addressable.
8951
8952 bool
8953 Array_index_expression::do_is_addressable() const
8954 {
8955   // A slice expression is not addressable.
8956   if (this->end_ != NULL)
8957     return false;
8958
8959   // An index into a slice is addressable.
8960   if (this->array_->type()->is_open_array_type())
8961     return true;
8962
8963   // An index into an array is addressable if the array is
8964   // addressable.
8965   return this->array_->is_addressable();
8966 }
8967
8968 // Get a tree for an array index.
8969
8970 tree
8971 Array_index_expression::do_get_tree(Translate_context* context)
8972 {
8973   Gogo* gogo = context->gogo();
8974   source_location loc = this->location();
8975
8976   Array_type* array_type = this->array_->type()->array_type();
8977   gcc_assert(array_type != NULL);
8978
8979   tree type_tree = array_type->get_tree(gogo);
8980
8981   tree array_tree = this->array_->get_tree(context);
8982   if (array_tree == error_mark_node)
8983     return error_mark_node;
8984
8985   if (array_type->length() == NULL && !DECL_P(array_tree))
8986     array_tree = save_expr(array_tree);
8987   tree length_tree = array_type->length_tree(gogo, array_tree);
8988   length_tree = save_expr(length_tree);
8989   tree length_type = TREE_TYPE(length_tree);
8990
8991   tree bad_index = boolean_false_node;
8992
8993   tree start_tree = this->start_->get_tree(context);
8994   if (start_tree == error_mark_node)
8995     return error_mark_node;
8996   if (!DECL_P(start_tree))
8997     start_tree = save_expr(start_tree);
8998   if (!INTEGRAL_TYPE_P(TREE_TYPE(start_tree)))
8999     start_tree = convert_to_integer(length_type, start_tree);
9000
9001   bad_index = Expression::check_bounds(start_tree, length_type, bad_index,
9002                                        loc);
9003
9004   start_tree = fold_convert_loc(loc, length_type, start_tree);
9005   bad_index = fold_build2_loc(loc, TRUTH_OR_EXPR, boolean_type_node, bad_index,
9006                               fold_build2_loc(loc,
9007                                               (this->end_ == NULL
9008                                                ? GE_EXPR
9009                                                : GT_EXPR),
9010                                               boolean_type_node, start_tree,
9011                                               length_tree));
9012
9013   int code = (array_type->length() != NULL
9014               ? (this->end_ == NULL
9015                  ? RUNTIME_ERROR_ARRAY_INDEX_OUT_OF_BOUNDS
9016                  : RUNTIME_ERROR_ARRAY_SLICE_OUT_OF_BOUNDS)
9017               : (this->end_ == NULL
9018                  ? RUNTIME_ERROR_SLICE_INDEX_OUT_OF_BOUNDS
9019                  : RUNTIME_ERROR_SLICE_SLICE_OUT_OF_BOUNDS));
9020   tree crash = Gogo::runtime_error(code, loc);
9021
9022   if (this->end_ == NULL)
9023     {
9024       // Simple array indexing.  This has to return an l-value, so
9025       // wrap the index check into START_TREE.
9026       start_tree = build2(COMPOUND_EXPR, TREE_TYPE(start_tree),
9027                           build3(COND_EXPR, void_type_node,
9028                                  bad_index, crash, NULL_TREE),
9029                           start_tree);
9030       start_tree = fold_convert_loc(loc, sizetype, start_tree);
9031
9032       if (array_type->length() != NULL)
9033         {
9034           // Fixed array.
9035           return build4(ARRAY_REF, TREE_TYPE(type_tree), array_tree,
9036                         start_tree, NULL_TREE, NULL_TREE);
9037         }
9038       else
9039         {
9040           // Open array.
9041           tree values = array_type->value_pointer_tree(gogo, array_tree);
9042           tree element_type_tree = array_type->element_type()->get_tree(gogo);
9043           tree element_size = TYPE_SIZE_UNIT(element_type_tree);
9044           tree offset = fold_build2_loc(loc, MULT_EXPR, sizetype,
9045                                         start_tree, element_size);
9046           tree ptr = fold_build2_loc(loc, POINTER_PLUS_EXPR,
9047                                      TREE_TYPE(values), values, offset);
9048           return build_fold_indirect_ref(ptr);
9049         }
9050     }
9051
9052   // Array slice.
9053
9054   tree capacity_tree = array_type->capacity_tree(gogo, array_tree);
9055   capacity_tree = fold_convert_loc(loc, length_type, capacity_tree);
9056
9057   tree end_tree;
9058   if (this->end_->is_nil_expression())
9059     end_tree = length_tree;
9060   else
9061     {
9062       end_tree = this->end_->get_tree(context);
9063       if (end_tree == error_mark_node)
9064         return error_mark_node;
9065       if (!DECL_P(end_tree))
9066         end_tree = save_expr(end_tree);
9067       if (!INTEGRAL_TYPE_P(TREE_TYPE(end_tree)))
9068         end_tree = convert_to_integer(length_type, end_tree);
9069
9070       bad_index = Expression::check_bounds(end_tree, length_type, bad_index,
9071                                            loc);
9072
9073       end_tree = fold_convert_loc(loc, length_type, end_tree);
9074
9075       capacity_tree = save_expr(capacity_tree);
9076       tree bad_end = fold_build2_loc(loc, TRUTH_OR_EXPR, boolean_type_node,
9077                                      fold_build2_loc(loc, LT_EXPR,
9078                                                      boolean_type_node,
9079                                                      end_tree, start_tree),
9080                                      fold_build2_loc(loc, GT_EXPR,
9081                                                      boolean_type_node,
9082                                                      end_tree, capacity_tree));
9083       bad_index = fold_build2_loc(loc, TRUTH_OR_EXPR, boolean_type_node,
9084                                   bad_index, bad_end);
9085     }
9086
9087   tree element_type_tree = array_type->element_type()->get_tree(gogo);
9088   tree element_size = TYPE_SIZE_UNIT(element_type_tree);
9089
9090   tree offset = fold_build2_loc(loc, MULT_EXPR, sizetype,
9091                                 fold_convert_loc(loc, sizetype, start_tree),
9092                                 element_size);
9093
9094   tree value_pointer = array_type->value_pointer_tree(gogo, array_tree);
9095
9096   value_pointer = fold_build2_loc(loc, POINTER_PLUS_EXPR,
9097                                   TREE_TYPE(value_pointer),
9098                                   value_pointer, offset);
9099
9100   tree result_length_tree = fold_build2_loc(loc, MINUS_EXPR, length_type,
9101                                             end_tree, start_tree);
9102
9103   tree result_capacity_tree = fold_build2_loc(loc, MINUS_EXPR, length_type,
9104                                               capacity_tree, start_tree);
9105
9106   tree struct_tree = this->type()->get_tree(gogo);
9107   gcc_assert(TREE_CODE(struct_tree) == RECORD_TYPE);
9108
9109   VEC(constructor_elt,gc)* init = VEC_alloc(constructor_elt, gc, 3);
9110
9111   constructor_elt* elt = VEC_quick_push(constructor_elt, init, NULL);
9112   tree field = TYPE_FIELDS(struct_tree);
9113   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__values") == 0);
9114   elt->index = field;
9115   elt->value = value_pointer;
9116
9117   elt = VEC_quick_push(constructor_elt, init, NULL);
9118   field = DECL_CHAIN(field);
9119   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__count") == 0);
9120   elt->index = field;
9121   elt->value = fold_convert_loc(loc, TREE_TYPE(field), result_length_tree);
9122
9123   elt = VEC_quick_push(constructor_elt, init, NULL);
9124   field = DECL_CHAIN(field);
9125   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__capacity") == 0);
9126   elt->index = field;
9127   elt->value = fold_convert_loc(loc, TREE_TYPE(field), result_capacity_tree);
9128
9129   tree constructor = build_constructor(struct_tree, init);
9130
9131   if (TREE_CONSTANT(value_pointer)
9132       && TREE_CONSTANT(result_length_tree)
9133       && TREE_CONSTANT(result_capacity_tree))
9134     TREE_CONSTANT(constructor) = 1;
9135
9136   return fold_build2_loc(loc, COMPOUND_EXPR, TREE_TYPE(constructor),
9137                          build3(COND_EXPR, void_type_node,
9138                                 bad_index, crash, NULL_TREE),
9139                          constructor);
9140 }
9141
9142 // Make an array index expression.  END may be NULL.
9143
9144 Expression*
9145 Expression::make_array_index(Expression* array, Expression* start,
9146                              Expression* end, source_location location)
9147 {
9148   // Taking a slice of a composite literal requires moving the literal
9149   // onto the heap.
9150   if (end != NULL && array->is_composite_literal())
9151     {
9152       array = Expression::make_heap_composite(array, location);
9153       array = Expression::make_unary(OPERATOR_MULT, array, location);
9154     }
9155   return new Array_index_expression(array, start, end, location);
9156 }
9157
9158 // A string index.  This is used for both indexing and slicing.
9159
9160 class String_index_expression : public Expression
9161 {
9162  public:
9163   String_index_expression(Expression* string, Expression* start,
9164                           Expression* end, source_location location)
9165     : Expression(EXPRESSION_STRING_INDEX, location),
9166       string_(string), start_(start), end_(end)
9167   { }
9168
9169  protected:
9170   int
9171   do_traverse(Traverse*);
9172
9173   Type*
9174   do_type();
9175
9176   void
9177   do_determine_type(const Type_context*);
9178
9179   void
9180   do_check_types(Gogo*);
9181
9182   Expression*
9183   do_copy()
9184   {
9185     return Expression::make_string_index(this->string_->copy(),
9186                                          this->start_->copy(),
9187                                          (this->end_ == NULL
9188                                           ? NULL
9189                                           : this->end_->copy()),
9190                                          this->location());
9191   }
9192
9193   tree
9194   do_get_tree(Translate_context*);
9195
9196  private:
9197   // The string we are getting a value from.
9198   Expression* string_;
9199   // The start or only index.
9200   Expression* start_;
9201   // The end index of a slice.  This may be NULL for a single index,
9202   // or it may be a nil expression for the length of the string.
9203   Expression* end_;
9204 };
9205
9206 // String index traversal.
9207
9208 int
9209 String_index_expression::do_traverse(Traverse* traverse)
9210 {
9211   if (Expression::traverse(&this->string_, traverse) == TRAVERSE_EXIT)
9212     return TRAVERSE_EXIT;
9213   if (Expression::traverse(&this->start_, traverse) == TRAVERSE_EXIT)
9214     return TRAVERSE_EXIT;
9215   if (this->end_ != NULL)
9216     {
9217       if (Expression::traverse(&this->end_, traverse) == TRAVERSE_EXIT)
9218         return TRAVERSE_EXIT;
9219     }
9220   return TRAVERSE_CONTINUE;
9221 }
9222
9223 // Return the type of a string index.
9224
9225 Type*
9226 String_index_expression::do_type()
9227 {
9228   if (this->end_ == NULL)
9229     return Type::lookup_integer_type("uint8");
9230   else
9231     return Type::make_string_type();
9232 }
9233
9234 // Determine the type of a string index.
9235
9236 void
9237 String_index_expression::do_determine_type(const Type_context*)
9238 {
9239   this->string_->determine_type_no_context();
9240   Type_context subcontext(NULL, true);
9241   this->start_->determine_type(&subcontext);
9242   if (this->end_ != NULL)
9243     this->end_->determine_type(&subcontext);
9244 }
9245
9246 // Check types of a string index.
9247
9248 void
9249 String_index_expression::do_check_types(Gogo*)
9250 {
9251   if (this->start_->type()->integer_type() == NULL)
9252     this->report_error(_("index must be integer"));
9253   if (this->end_ != NULL
9254       && this->end_->type()->integer_type() == NULL
9255       && !this->end_->is_nil_expression())
9256     this->report_error(_("slice end must be integer"));
9257
9258   std::string sval;
9259   bool sval_valid = this->string_->string_constant_value(&sval);
9260
9261   mpz_t ival;
9262   mpz_init(ival);
9263   Type* dummy;
9264   if (this->start_->integer_constant_value(true, ival, &dummy))
9265     {
9266       if (mpz_sgn(ival) < 0
9267           || (sval_valid && mpz_cmp_ui(ival, sval.length()) >= 0))
9268         {
9269           error_at(this->start_->location(), "string index out of bounds");
9270           this->set_is_error();
9271         }
9272     }
9273   if (this->end_ != NULL && !this->end_->is_nil_expression())
9274     {
9275       if (this->end_->integer_constant_value(true, ival, &dummy))
9276         {
9277           if (mpz_sgn(ival) < 0
9278               || (sval_valid && mpz_cmp_ui(ival, sval.length()) > 0))
9279             {
9280               error_at(this->end_->location(), "string index out of bounds");
9281               this->set_is_error();
9282             }
9283         }
9284     }
9285   mpz_clear(ival);
9286 }
9287
9288 // Get a tree for a string index.
9289
9290 tree
9291 String_index_expression::do_get_tree(Translate_context* context)
9292 {
9293   source_location loc = this->location();
9294
9295   tree string_tree = this->string_->get_tree(context);
9296   if (string_tree == error_mark_node)
9297     return error_mark_node;
9298
9299   if (this->string_->type()->points_to() != NULL)
9300     string_tree = build_fold_indirect_ref(string_tree);
9301   if (!DECL_P(string_tree))
9302     string_tree = save_expr(string_tree);
9303   tree string_type = TREE_TYPE(string_tree);
9304
9305   tree length_tree = String_type::length_tree(context->gogo(), string_tree);
9306   length_tree = save_expr(length_tree);
9307   tree length_type = TREE_TYPE(length_tree);
9308
9309   tree bad_index = boolean_false_node;
9310
9311   tree start_tree = this->start_->get_tree(context);
9312   if (start_tree == error_mark_node)
9313     return error_mark_node;
9314   if (!DECL_P(start_tree))
9315     start_tree = save_expr(start_tree);
9316   if (!INTEGRAL_TYPE_P(TREE_TYPE(start_tree)))
9317     start_tree = convert_to_integer(length_type, start_tree);
9318
9319   bad_index = Expression::check_bounds(start_tree, length_type, bad_index,
9320                                        loc);
9321
9322   start_tree = fold_convert_loc(loc, length_type, start_tree);
9323
9324   int code = (this->end_ == NULL
9325               ? RUNTIME_ERROR_STRING_INDEX_OUT_OF_BOUNDS
9326               : RUNTIME_ERROR_STRING_SLICE_OUT_OF_BOUNDS);
9327   tree crash = Gogo::runtime_error(code, loc);
9328
9329   if (this->end_ == NULL)
9330     {
9331       bad_index = fold_build2_loc(loc, TRUTH_OR_EXPR, boolean_type_node,
9332                                   bad_index,
9333                                   fold_build2_loc(loc, GE_EXPR,
9334                                                   boolean_type_node,
9335                                                   start_tree, length_tree));
9336
9337       tree bytes_tree = String_type::bytes_tree(context->gogo(), string_tree);
9338       tree ptr = fold_build2_loc(loc, POINTER_PLUS_EXPR, TREE_TYPE(bytes_tree),
9339                                  bytes_tree,
9340                                  fold_convert_loc(loc, sizetype, start_tree));
9341       tree index = build_fold_indirect_ref_loc(loc, ptr);
9342
9343       return build2(COMPOUND_EXPR, TREE_TYPE(index),
9344                     build3(COND_EXPR, void_type_node,
9345                            bad_index, crash, NULL_TREE),
9346                     index);
9347     }
9348   else
9349     {
9350       tree end_tree;
9351       if (this->end_->is_nil_expression())
9352         end_tree = build_int_cst(length_type, -1);
9353       else
9354         {
9355           end_tree = this->end_->get_tree(context);
9356           if (end_tree == error_mark_node)
9357             return error_mark_node;
9358           if (!DECL_P(end_tree))
9359             end_tree = save_expr(end_tree);
9360           if (!INTEGRAL_TYPE_P(TREE_TYPE(end_tree)))
9361             end_tree = convert_to_integer(length_type, end_tree);
9362
9363           bad_index = Expression::check_bounds(end_tree, length_type,
9364                                                bad_index, loc);
9365
9366           end_tree = fold_convert_loc(loc, length_type, end_tree);
9367         }
9368
9369       static tree strslice_fndecl;
9370       tree ret = Gogo::call_builtin(&strslice_fndecl,
9371                                     loc,
9372                                     "__go_string_slice",
9373                                     3,
9374                                     string_type,
9375                                     string_type,
9376                                     string_tree,
9377                                     length_type,
9378                                     start_tree,
9379                                     length_type,
9380                                     end_tree);
9381       // This will panic if the bounds are out of range for the
9382       // string.
9383       TREE_NOTHROW(strslice_fndecl) = 0;
9384
9385       if (bad_index == boolean_false_node)
9386         return ret;
9387       else
9388         return build2(COMPOUND_EXPR, TREE_TYPE(ret),
9389                       build3(COND_EXPR, void_type_node,
9390                              bad_index, crash, NULL_TREE),
9391                       ret);
9392     }
9393 }
9394
9395 // Make a string index expression.  END may be NULL.
9396
9397 Expression*
9398 Expression::make_string_index(Expression* string, Expression* start,
9399                               Expression* end, source_location location)
9400 {
9401   return new String_index_expression(string, start, end, location);
9402 }
9403
9404 // Class Map_index.
9405
9406 // Get the type of the map.
9407
9408 Map_type*
9409 Map_index_expression::get_map_type() const
9410 {
9411   Map_type* mt = this->map_->type()->deref()->map_type();
9412   gcc_assert(mt != NULL);
9413   return mt;
9414 }
9415
9416 // Map index traversal.
9417
9418 int
9419 Map_index_expression::do_traverse(Traverse* traverse)
9420 {
9421   if (Expression::traverse(&this->map_, traverse) == TRAVERSE_EXIT)
9422     return TRAVERSE_EXIT;
9423   return Expression::traverse(&this->index_, traverse);
9424 }
9425
9426 // Return the type of a map index.
9427
9428 Type*
9429 Map_index_expression::do_type()
9430 {
9431   Type* type = this->get_map_type()->val_type();
9432   // If this map index is in a tuple assignment, we actually return a
9433   // pointer to the value type.  Tuple_map_assignment_statement is
9434   // responsible for handling this correctly.  We need to get the type
9435   // right in case this gets assigned to a temporary variable.
9436   if (this->is_in_tuple_assignment_)
9437     type = Type::make_pointer_type(type);
9438   return type;
9439 }
9440
9441 // Fix the type of a map index.
9442
9443 void
9444 Map_index_expression::do_determine_type(const Type_context*)
9445 {
9446   this->map_->determine_type_no_context();
9447   Type_context subcontext(this->get_map_type()->key_type(), false);
9448   this->index_->determine_type(&subcontext);
9449 }
9450
9451 // Check types of a map index.
9452
9453 void
9454 Map_index_expression::do_check_types(Gogo*)
9455 {
9456   std::string reason;
9457   if (!Type::are_assignable(this->get_map_type()->key_type(),
9458                             this->index_->type(), &reason))
9459     {
9460       if (reason.empty())
9461         this->report_error(_("incompatible type for map index"));
9462       else
9463         {
9464           error_at(this->location(), "incompatible type for map index (%s)",
9465                    reason.c_str());
9466           this->set_is_error();
9467         }
9468     }
9469 }
9470
9471 // Get a tree for a map index.
9472
9473 tree
9474 Map_index_expression::do_get_tree(Translate_context* context)
9475 {
9476   Map_type* type = this->get_map_type();
9477
9478   tree valptr = this->get_value_pointer(context, this->is_lvalue_);
9479   if (valptr == error_mark_node)
9480     return error_mark_node;
9481   valptr = save_expr(valptr);
9482
9483   tree val_type_tree = TREE_TYPE(TREE_TYPE(valptr));
9484
9485   if (this->is_lvalue_)
9486     return build_fold_indirect_ref(valptr);
9487   else if (this->is_in_tuple_assignment_)
9488     {
9489       // Tuple_map_assignment_statement is responsible for using this
9490       // appropriately.
9491       return valptr;
9492     }
9493   else
9494     {
9495       return fold_build3(COND_EXPR, val_type_tree,
9496                          fold_build2(EQ_EXPR, boolean_type_node, valptr,
9497                                      fold_convert(TREE_TYPE(valptr),
9498                                                   null_pointer_node)),
9499                          type->val_type()->get_init_tree(context->gogo(),
9500                                                          false),
9501                          build_fold_indirect_ref(valptr));
9502     }
9503 }
9504
9505 // Get a tree for the map index.  This returns a tree which evaluates
9506 // to a pointer to a value.  The pointer will be NULL if the key is
9507 // not in the map.
9508
9509 tree
9510 Map_index_expression::get_value_pointer(Translate_context* context,
9511                                         bool insert)
9512 {
9513   Map_type* type = this->get_map_type();
9514
9515   tree map_tree = this->map_->get_tree(context);
9516   tree index_tree = this->index_->get_tree(context);
9517   index_tree = Expression::convert_for_assignment(context, type->key_type(),
9518                                                   this->index_->type(),
9519                                                   index_tree,
9520                                                   this->location());
9521   if (map_tree == error_mark_node || index_tree == error_mark_node)
9522     return error_mark_node;
9523
9524   if (this->map_->type()->points_to() != NULL)
9525     map_tree = build_fold_indirect_ref(map_tree);
9526
9527   // We need to pass in a pointer to the key, so stuff it into a
9528   // variable.
9529   tree tmp = create_tmp_var(TREE_TYPE(index_tree), get_name(index_tree));
9530   DECL_IGNORED_P(tmp) = 0;
9531   DECL_INITIAL(tmp) = index_tree;
9532   tree make_tmp = build1(DECL_EXPR, void_type_node, tmp);
9533   tree tmpref = fold_convert(const_ptr_type_node, build_fold_addr_expr(tmp));
9534   TREE_ADDRESSABLE(tmp) = 1;
9535
9536   static tree map_index_fndecl;
9537   tree call = Gogo::call_builtin(&map_index_fndecl,
9538                                  this->location(),
9539                                  "__go_map_index",
9540                                  3,
9541                                  const_ptr_type_node,
9542                                  TREE_TYPE(map_tree),
9543                                  map_tree,
9544                                  const_ptr_type_node,
9545                                  tmpref,
9546                                  boolean_type_node,
9547                                  (insert
9548                                   ? boolean_true_node
9549                                   : boolean_false_node));
9550   // This can panic on a map of interface type if the interface holds
9551   // an uncomparable or unhashable type.
9552   TREE_NOTHROW(map_index_fndecl) = 0;
9553
9554   tree val_type_tree = type->val_type()->get_tree(context->gogo());
9555   if (val_type_tree == error_mark_node)
9556     return error_mark_node;
9557   tree ptr_val_type_tree = build_pointer_type(val_type_tree);
9558
9559   return build2(COMPOUND_EXPR, ptr_val_type_tree,
9560                 make_tmp,
9561                 fold_convert(ptr_val_type_tree, call));
9562 }
9563
9564 // Make a map index expression.
9565
9566 Map_index_expression*
9567 Expression::make_map_index(Expression* map, Expression* index,
9568                            source_location location)
9569 {
9570   return new Map_index_expression(map, index, location);
9571 }
9572
9573 // Class Field_reference_expression.
9574
9575 // Return the type of a field reference.
9576
9577 Type*
9578 Field_reference_expression::do_type()
9579 {
9580   Struct_type* struct_type = this->expr_->type()->struct_type();
9581   gcc_assert(struct_type != NULL);
9582   return struct_type->field(this->field_index_)->type();
9583 }
9584
9585 // Check the types for a field reference.
9586
9587 void
9588 Field_reference_expression::do_check_types(Gogo*)
9589 {
9590   Struct_type* struct_type = this->expr_->type()->struct_type();
9591   gcc_assert(struct_type != NULL);
9592   gcc_assert(struct_type->field(this->field_index_) != NULL);
9593 }
9594
9595 // Get a tree for a field reference.
9596
9597 tree
9598 Field_reference_expression::do_get_tree(Translate_context* context)
9599 {
9600   tree struct_tree = this->expr_->get_tree(context);
9601   if (struct_tree == error_mark_node
9602       || TREE_TYPE(struct_tree) == error_mark_node)
9603     return error_mark_node;
9604   gcc_assert(TREE_CODE(TREE_TYPE(struct_tree)) == RECORD_TYPE);
9605   tree field = TYPE_FIELDS(TREE_TYPE(struct_tree));
9606   gcc_assert(field != NULL_TREE);
9607   for (unsigned int i = this->field_index_; i > 0; --i)
9608     {
9609       field = DECL_CHAIN(field);
9610       gcc_assert(field != NULL_TREE);
9611     }
9612   return build3(COMPONENT_REF, TREE_TYPE(field), struct_tree, field,
9613                 NULL_TREE);
9614 }
9615
9616 // Make a reference to a qualified identifier in an expression.
9617
9618 Field_reference_expression*
9619 Expression::make_field_reference(Expression* expr, unsigned int field_index,
9620                                  source_location location)
9621 {
9622   return new Field_reference_expression(expr, field_index, location);
9623 }
9624
9625 // Class Interface_field_reference_expression.
9626
9627 // Return a tree for the pointer to the function to call.
9628
9629 tree
9630 Interface_field_reference_expression::get_function_tree(Translate_context*,
9631                                                         tree expr)
9632 {
9633   if (this->expr_->type()->points_to() != NULL)
9634     expr = build_fold_indirect_ref(expr);
9635
9636   tree expr_type = TREE_TYPE(expr);
9637   gcc_assert(TREE_CODE(expr_type) == RECORD_TYPE);
9638
9639   tree field = TYPE_FIELDS(expr_type);
9640   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__methods") == 0);
9641
9642   tree table = build3(COMPONENT_REF, TREE_TYPE(field), expr, field, NULL_TREE);
9643   gcc_assert(POINTER_TYPE_P(TREE_TYPE(table)));
9644
9645   table = build_fold_indirect_ref(table);
9646   gcc_assert(TREE_CODE(TREE_TYPE(table)) == RECORD_TYPE);
9647
9648   std::string name = Gogo::unpack_hidden_name(this->name_);
9649   for (field = DECL_CHAIN(TYPE_FIELDS(TREE_TYPE(table)));
9650        field != NULL_TREE;
9651        field = DECL_CHAIN(field))
9652     {
9653       if (name == IDENTIFIER_POINTER(DECL_NAME(field)))
9654         break;
9655     }
9656   gcc_assert(field != NULL_TREE);
9657
9658   return build3(COMPONENT_REF, TREE_TYPE(field), table, field, NULL_TREE);
9659 }
9660
9661 // Return a tree for the first argument to pass to the interface
9662 // function.
9663
9664 tree
9665 Interface_field_reference_expression::get_underlying_object_tree(
9666     Translate_context*,
9667     tree expr)
9668 {
9669   if (this->expr_->type()->points_to() != NULL)
9670     expr = build_fold_indirect_ref(expr);
9671
9672   tree expr_type = TREE_TYPE(expr);
9673   gcc_assert(TREE_CODE(expr_type) == RECORD_TYPE);
9674
9675   tree field = DECL_CHAIN(TYPE_FIELDS(expr_type));
9676   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__object") == 0);
9677
9678   return build3(COMPONENT_REF, TREE_TYPE(field), expr, field, NULL_TREE);
9679 }
9680
9681 // Traversal.
9682
9683 int
9684 Interface_field_reference_expression::do_traverse(Traverse* traverse)
9685 {
9686   return Expression::traverse(&this->expr_, traverse);
9687 }
9688
9689 // Return the type of an interface field reference.
9690
9691 Type*
9692 Interface_field_reference_expression::do_type()
9693 {
9694   Type* expr_type = this->expr_->type();
9695
9696   Type* points_to = expr_type->points_to();
9697   if (points_to != NULL)
9698     expr_type = points_to;
9699
9700   Interface_type* interface_type = expr_type->interface_type();
9701   if (interface_type == NULL)
9702     return Type::make_error_type();
9703
9704   const Typed_identifier* method = interface_type->find_method(this->name_);
9705   if (method == NULL)
9706     return Type::make_error_type();
9707
9708   return method->type();
9709 }
9710
9711 // Determine types.
9712
9713 void
9714 Interface_field_reference_expression::do_determine_type(const Type_context*)
9715 {
9716   this->expr_->determine_type_no_context();
9717 }
9718
9719 // Check the types for an interface field reference.
9720
9721 void
9722 Interface_field_reference_expression::do_check_types(Gogo*)
9723 {
9724   Type* type = this->expr_->type();
9725
9726   Type* points_to = type->points_to();
9727   if (points_to != NULL)
9728     type = points_to;
9729
9730   Interface_type* interface_type = type->interface_type();
9731   if (interface_type == NULL)
9732     this->report_error(_("expected interface or pointer to interface"));
9733   else
9734     {
9735       const Typed_identifier* method =
9736         interface_type->find_method(this->name_);
9737       if (method == NULL)
9738         {
9739           error_at(this->location(), "method %qs not in interface",
9740                    Gogo::message_name(this->name_).c_str());
9741           this->set_is_error();
9742         }
9743     }
9744 }
9745
9746 // Get a tree for a reference to a field in an interface.  There is no
9747 // standard tree type representation for this: it's a function
9748 // attached to its first argument, like a Bound_method_expression.
9749 // The only places it may currently be used are in a Call_expression
9750 // or a Go_statement, which will take it apart directly.  So this has
9751 // nothing to do at present.
9752
9753 tree
9754 Interface_field_reference_expression::do_get_tree(Translate_context*)
9755 {
9756   gcc_unreachable();
9757 }
9758
9759 // Make a reference to a field in an interface.
9760
9761 Expression*
9762 Expression::make_interface_field_reference(Expression* expr,
9763                                            const std::string& field,
9764                                            source_location location)
9765 {
9766   return new Interface_field_reference_expression(expr, field, location);
9767 }
9768
9769 // A general selector.  This is a Parser_expression for LEFT.NAME.  It
9770 // is lowered after we know the type of the left hand side.
9771
9772 class Selector_expression : public Parser_expression
9773 {
9774  public:
9775   Selector_expression(Expression* left, const std::string& name,
9776                       source_location location)
9777     : Parser_expression(EXPRESSION_SELECTOR, location),
9778       left_(left), name_(name)
9779   { }
9780
9781  protected:
9782   int
9783   do_traverse(Traverse* traverse)
9784   { return Expression::traverse(&this->left_, traverse); }
9785
9786   Expression*
9787   do_lower(Gogo*, Named_object*, int);
9788
9789   Expression*
9790   do_copy()
9791   {
9792     return new Selector_expression(this->left_->copy(), this->name_,
9793                                    this->location());
9794   }
9795
9796  private:
9797   Expression*
9798   lower_method_expression(Gogo*);
9799
9800   // The expression on the left hand side.
9801   Expression* left_;
9802   // The name on the right hand side.
9803   std::string name_;
9804 };
9805
9806 // Lower a selector expression once we know the real type of the left
9807 // hand side.
9808
9809 Expression*
9810 Selector_expression::do_lower(Gogo* gogo, Named_object*, int)
9811 {
9812   Expression* left = this->left_;
9813   if (left->is_type_expression())
9814     return this->lower_method_expression(gogo);
9815   return Type::bind_field_or_method(gogo, left->type(), left, this->name_,
9816                                     this->location());
9817 }
9818
9819 // Lower a method expression T.M or (*T).M.  We turn this into a
9820 // function literal.
9821
9822 Expression*
9823 Selector_expression::lower_method_expression(Gogo* gogo)
9824 {
9825   source_location location = this->location();
9826   Type* type = this->left_->type();
9827   const std::string& name(this->name_);
9828
9829   bool is_pointer;
9830   if (type->points_to() == NULL)
9831     is_pointer = false;
9832   else
9833     {
9834       is_pointer = true;
9835       type = type->points_to();
9836     }
9837   Named_type* nt = type->named_type();
9838   if (nt == NULL)
9839     {
9840       error_at(location,
9841                ("method expression requires named type or "
9842                 "pointer to named type"));
9843       return Expression::make_error(location);
9844     }
9845
9846   bool is_ambiguous;
9847   Method* method = nt->method_function(name, &is_ambiguous);
9848   if (method == NULL)
9849     {
9850       if (!is_ambiguous)
9851         error_at(location, "type %<%s%> has no method %<%s%>",
9852                  nt->message_name().c_str(),
9853                  Gogo::message_name(name).c_str());
9854       else
9855         error_at(location, "method %<%s%> is ambiguous in type %<%s%>",
9856                  Gogo::message_name(name).c_str(),
9857                  nt->message_name().c_str());
9858       return Expression::make_error(location);
9859     }
9860
9861   if (!is_pointer && !method->is_value_method())
9862     {
9863       error_at(location, "method requires pointer (use %<(*%s).%s)%>",
9864                nt->message_name().c_str(),
9865                Gogo::message_name(name).c_str());
9866       return Expression::make_error(location);
9867     }
9868
9869   // Build a new function type in which the receiver becomes the first
9870   // argument.
9871   Function_type* method_type = method->type();
9872   gcc_assert(method_type->is_method());
9873
9874   const char* const receiver_name = "$this";
9875   Typed_identifier_list* parameters = new Typed_identifier_list();
9876   parameters->push_back(Typed_identifier(receiver_name, this->left_->type(),
9877                                          location));
9878
9879   const Typed_identifier_list* method_parameters = method_type->parameters();
9880   if (method_parameters != NULL)
9881     {
9882       for (Typed_identifier_list::const_iterator p = method_parameters->begin();
9883            p != method_parameters->end();
9884            ++p)
9885         parameters->push_back(*p);
9886     }
9887
9888   const Typed_identifier_list* method_results = method_type->results();
9889   Typed_identifier_list* results;
9890   if (method_results == NULL)
9891     results = NULL;
9892   else
9893     {
9894       results = new Typed_identifier_list();
9895       for (Typed_identifier_list::const_iterator p = method_results->begin();
9896            p != method_results->end();
9897            ++p)
9898         results->push_back(*p);
9899     }
9900
9901   Function_type* fntype = Type::make_function_type(NULL, parameters, results,
9902                                                    location);
9903   if (method_type->is_varargs())
9904     fntype->set_is_varargs();
9905
9906   // We generate methods which always takes a pointer to the receiver
9907   // as their first argument.  If this is for a pointer type, we can
9908   // simply reuse the existing function.  We use an internal hack to
9909   // get the right type.
9910
9911   if (is_pointer)
9912     {
9913       Named_object* mno = (method->needs_stub_method()
9914                            ? method->stub_object()
9915                            : method->named_object());
9916       Expression* f = Expression::make_func_reference(mno, NULL, location);
9917       f = Expression::make_cast(fntype, f, location);
9918       Type_conversion_expression* tce =
9919         static_cast<Type_conversion_expression*>(f);
9920       tce->set_may_convert_function_types();
9921       return f;
9922     }
9923
9924   Named_object* no = gogo->start_function(Gogo::thunk_name(), fntype, false,
9925                                           location);
9926
9927   Named_object* vno = gogo->lookup(receiver_name, NULL);
9928   gcc_assert(vno != NULL);
9929   Expression* ve = Expression::make_var_reference(vno, location);
9930   Expression* bm = Type::bind_field_or_method(gogo, nt, ve, name, location);
9931   gcc_assert(bm != NULL && !bm->is_error_expression());
9932
9933   Expression_list* args;
9934   if (method_parameters == NULL)
9935     args = NULL;
9936   else
9937     {
9938       args = new Expression_list();
9939       for (Typed_identifier_list::const_iterator p = method_parameters->begin();
9940            p != method_parameters->end();
9941            ++p)
9942         {
9943           vno = gogo->lookup(p->name(), NULL);
9944           gcc_assert(vno != NULL);
9945           args->push_back(Expression::make_var_reference(vno, location));
9946         }
9947     }
9948
9949   Call_expression* call = Expression::make_call(bm, args,
9950                                                 method_type->is_varargs(),
9951                                                 location);
9952
9953   size_t count = call->result_count();
9954   Statement* s;
9955   if (count == 0)
9956     s = Statement::make_statement(call);
9957   else
9958     {
9959       Expression_list* retvals = new Expression_list();
9960       if (count <= 1)
9961         retvals->push_back(call);
9962       else
9963         {
9964           for (size_t i = 0; i < count; ++i)
9965             retvals->push_back(Expression::make_call_result(call, i));
9966         }
9967       s = Statement::make_return_statement(no->func_value()->type()->results(),
9968                                            retvals, location);
9969     }
9970   gogo->add_statement(s);
9971
9972   gogo->finish_function(location);
9973
9974   return Expression::make_func_reference(no, NULL, location);
9975 }
9976
9977 // Make a selector expression.
9978
9979 Expression*
9980 Expression::make_selector(Expression* left, const std::string& name,
9981                           source_location location)
9982 {
9983   return new Selector_expression(left, name, location);
9984 }
9985
9986 // Implement the builtin function new.
9987
9988 class Allocation_expression : public Expression
9989 {
9990  public:
9991   Allocation_expression(Type* type, source_location location)
9992     : Expression(EXPRESSION_ALLOCATION, location),
9993       type_(type)
9994   { }
9995
9996  protected:
9997   int
9998   do_traverse(Traverse* traverse)
9999   { return Type::traverse(this->type_, traverse); }
10000
10001   Type*
10002   do_type()
10003   { return Type::make_pointer_type(this->type_); }
10004
10005   void
10006   do_determine_type(const Type_context*)
10007   { }
10008
10009   void
10010   do_check_types(Gogo*);
10011
10012   Expression*
10013   do_copy()
10014   { return new Allocation_expression(this->type_, this->location()); }
10015
10016   tree
10017   do_get_tree(Translate_context*);
10018
10019  private:
10020   // The type we are allocating.
10021   Type* type_;
10022 };
10023
10024 // Check the type of an allocation expression.
10025
10026 void
10027 Allocation_expression::do_check_types(Gogo*)
10028 {
10029   if (this->type_->function_type() != NULL)
10030     this->report_error(_("invalid new of function type"));
10031 }
10032
10033 // Return a tree for an allocation expression.
10034
10035 tree
10036 Allocation_expression::do_get_tree(Translate_context* context)
10037 {
10038   tree type_tree = this->type_->get_tree(context->gogo());
10039   tree size_tree = TYPE_SIZE_UNIT(type_tree);
10040   tree space = context->gogo()->allocate_memory(this->type_, size_tree,
10041                                                 this->location());
10042   return fold_convert(build_pointer_type(type_tree), space);
10043 }
10044
10045 // Make an allocation expression.
10046
10047 Expression*
10048 Expression::make_allocation(Type* type, source_location location)
10049 {
10050   return new Allocation_expression(type, location);
10051 }
10052
10053 // Implement the builtin function make.
10054
10055 class Make_expression : public Expression
10056 {
10057  public:
10058   Make_expression(Type* type, Expression_list* args, source_location location)
10059     : Expression(EXPRESSION_MAKE, location),
10060       type_(type), args_(args)
10061   { }
10062
10063  protected:
10064   int
10065   do_traverse(Traverse* traverse);
10066
10067   Type*
10068   do_type()
10069   { return this->type_; }
10070
10071   void
10072   do_determine_type(const Type_context*);
10073
10074   void
10075   do_check_types(Gogo*);
10076
10077   Expression*
10078   do_copy()
10079   {
10080     return new Make_expression(this->type_, this->args_->copy(),
10081                                this->location());
10082   }
10083
10084   tree
10085   do_get_tree(Translate_context*);
10086
10087  private:
10088   // The type we are making.
10089   Type* type_;
10090   // The arguments to pass to the make routine.
10091   Expression_list* args_;
10092 };
10093
10094 // Traversal.
10095
10096 int
10097 Make_expression::do_traverse(Traverse* traverse)
10098 {
10099   if (this->args_ != NULL
10100       && this->args_->traverse(traverse) == TRAVERSE_EXIT)
10101     return TRAVERSE_EXIT;
10102   if (Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
10103     return TRAVERSE_EXIT;
10104   return TRAVERSE_CONTINUE;
10105 }
10106
10107 // Set types of arguments.
10108
10109 void
10110 Make_expression::do_determine_type(const Type_context*)
10111 {
10112   if (this->args_ != NULL)
10113     {
10114       Type_context context(Type::lookup_integer_type("int"), false);
10115       for (Expression_list::const_iterator pe = this->args_->begin();
10116            pe != this->args_->end();
10117            ++pe)
10118         (*pe)->determine_type(&context);
10119     }
10120 }
10121
10122 // Check types for a make expression.
10123
10124 void
10125 Make_expression::do_check_types(Gogo*)
10126 {
10127   if (this->type_->channel_type() == NULL
10128       && this->type_->map_type() == NULL
10129       && (this->type_->array_type() == NULL
10130           || this->type_->array_type()->length() != NULL))
10131     this->report_error(_("invalid type for make function"));
10132   else if (!this->type_->check_make_expression(this->args_, this->location()))
10133     this->set_is_error();
10134 }
10135
10136 // Return a tree for a make expression.
10137
10138 tree
10139 Make_expression::do_get_tree(Translate_context* context)
10140 {
10141   return this->type_->make_expression_tree(context, this->args_,
10142                                            this->location());
10143 }
10144
10145 // Make a make expression.
10146
10147 Expression*
10148 Expression::make_make(Type* type, Expression_list* args,
10149                       source_location location)
10150 {
10151   return new Make_expression(type, args, location);
10152 }
10153
10154 // Construct a struct.
10155
10156 class Struct_construction_expression : public Expression
10157 {
10158  public:
10159   Struct_construction_expression(Type* type, Expression_list* vals,
10160                                  source_location location)
10161     : Expression(EXPRESSION_STRUCT_CONSTRUCTION, location),
10162       type_(type), vals_(vals)
10163   { }
10164
10165   // Return whether this is a constant initializer.
10166   bool
10167   is_constant_struct() const;
10168
10169  protected:
10170   int
10171   do_traverse(Traverse* traverse);
10172
10173   Type*
10174   do_type()
10175   { return this->type_; }
10176
10177   void
10178   do_determine_type(const Type_context*);
10179
10180   void
10181   do_check_types(Gogo*);
10182
10183   Expression*
10184   do_copy()
10185   {
10186     return new Struct_construction_expression(this->type_, this->vals_->copy(),
10187                                               this->location());
10188   }
10189
10190   bool
10191   do_is_addressable() const
10192   { return true; }
10193
10194   tree
10195   do_get_tree(Translate_context*);
10196
10197   void
10198   do_export(Export*) const;
10199
10200  private:
10201   // The type of the struct to construct.
10202   Type* type_;
10203   // The list of values, in order of the fields in the struct.  A NULL
10204   // entry means that the field should be zero-initialized.
10205   Expression_list* vals_;
10206 };
10207
10208 // Traversal.
10209
10210 int
10211 Struct_construction_expression::do_traverse(Traverse* traverse)
10212 {
10213   if (this->vals_ != NULL
10214       && this->vals_->traverse(traverse) == TRAVERSE_EXIT)
10215     return TRAVERSE_EXIT;
10216   if (Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
10217     return TRAVERSE_EXIT;
10218   return TRAVERSE_CONTINUE;
10219 }
10220
10221 // Return whether this is a constant initializer.
10222
10223 bool
10224 Struct_construction_expression::is_constant_struct() const
10225 {
10226   if (this->vals_ == NULL)
10227     return true;
10228   for (Expression_list::const_iterator pv = this->vals_->begin();
10229        pv != this->vals_->end();
10230        ++pv)
10231     {
10232       if (*pv != NULL
10233           && !(*pv)->is_constant()
10234           && (!(*pv)->is_composite_literal()
10235               || (*pv)->is_nonconstant_composite_literal()))
10236         return false;
10237     }
10238
10239   const Struct_field_list* fields = this->type_->struct_type()->fields();
10240   for (Struct_field_list::const_iterator pf = fields->begin();
10241        pf != fields->end();
10242        ++pf)
10243     {
10244       // There are no constant constructors for interfaces.
10245       if (pf->type()->interface_type() != NULL)
10246         return false;
10247     }
10248
10249   return true;
10250 }
10251
10252 // Final type determination.
10253
10254 void
10255 Struct_construction_expression::do_determine_type(const Type_context*)
10256 {
10257   if (this->vals_ == NULL)
10258     return;
10259   const Struct_field_list* fields = this->type_->struct_type()->fields();
10260   Expression_list::const_iterator pv = this->vals_->begin();
10261   for (Struct_field_list::const_iterator pf = fields->begin();
10262        pf != fields->end();
10263        ++pf, ++pv)
10264     {
10265       if (pv == this->vals_->end())
10266         return;
10267       if (*pv != NULL)
10268         {
10269           Type_context subcontext(pf->type(), false);
10270           (*pv)->determine_type(&subcontext);
10271         }
10272     }
10273 }
10274
10275 // Check types.
10276
10277 void
10278 Struct_construction_expression::do_check_types(Gogo*)
10279 {
10280   if (this->vals_ == NULL)
10281     return;
10282
10283   Struct_type* st = this->type_->struct_type();
10284   if (this->vals_->size() > st->field_count())
10285     {
10286       this->report_error(_("too many expressions for struct"));
10287       return;
10288     }
10289
10290   const Struct_field_list* fields = st->fields();
10291   Expression_list::const_iterator pv = this->vals_->begin();
10292   int i = 0;
10293   for (Struct_field_list::const_iterator pf = fields->begin();
10294        pf != fields->end();
10295        ++pf, ++pv, ++i)
10296     {
10297       if (pv == this->vals_->end())
10298         {
10299           this->report_error(_("too few expressions for struct"));
10300           break;
10301         }
10302
10303       if (*pv == NULL)
10304         continue;
10305
10306       std::string reason;
10307       if (!Type::are_assignable(pf->type(), (*pv)->type(), &reason))
10308         {
10309           if (reason.empty())
10310             error_at((*pv)->location(),
10311                      "incompatible type for field %d in struct construction",
10312                      i + 1);
10313           else
10314             error_at((*pv)->location(),
10315                      ("incompatible type for field %d in "
10316                       "struct construction (%s)"),
10317                      i + 1, reason.c_str());
10318           this->set_is_error();
10319         }
10320     }
10321   gcc_assert(pv == this->vals_->end());
10322 }
10323
10324 // Return a tree for constructing a struct.
10325
10326 tree
10327 Struct_construction_expression::do_get_tree(Translate_context* context)
10328 {
10329   Gogo* gogo = context->gogo();
10330
10331   if (this->vals_ == NULL)
10332     return this->type_->get_init_tree(gogo, false);
10333
10334   tree type_tree = this->type_->get_tree(gogo);
10335   if (type_tree == error_mark_node)
10336     return error_mark_node;
10337   gcc_assert(TREE_CODE(type_tree) == RECORD_TYPE);
10338
10339   bool is_constant = true;
10340   const Struct_field_list* fields = this->type_->struct_type()->fields();
10341   VEC(constructor_elt,gc)* elts = VEC_alloc(constructor_elt, gc,
10342                                             fields->size());
10343   Struct_field_list::const_iterator pf = fields->begin();
10344   Expression_list::const_iterator pv = this->vals_->begin();
10345   for (tree field = TYPE_FIELDS(type_tree);
10346        field != NULL_TREE;
10347        field = DECL_CHAIN(field), ++pf)
10348     {
10349       gcc_assert(pf != fields->end());
10350
10351       tree val;
10352       if (pv == this->vals_->end())
10353         val = pf->type()->get_init_tree(gogo, false);
10354       else if (*pv == NULL)
10355         {
10356           val = pf->type()->get_init_tree(gogo, false);
10357           ++pv;
10358         }
10359       else
10360         {
10361           val = Expression::convert_for_assignment(context, pf->type(),
10362                                                    (*pv)->type(),
10363                                                    (*pv)->get_tree(context),
10364                                                    this->location());
10365           ++pv;
10366         }
10367
10368       if (val == error_mark_node || TREE_TYPE(val) == error_mark_node)
10369         return error_mark_node;
10370
10371       constructor_elt* elt = VEC_quick_push(constructor_elt, elts, NULL);
10372       elt->index = field;
10373       elt->value = val;
10374       if (!TREE_CONSTANT(val))
10375         is_constant = false;
10376     }
10377   gcc_assert(pf == fields->end());
10378
10379   tree ret = build_constructor(type_tree, elts);
10380   if (is_constant)
10381     TREE_CONSTANT(ret) = 1;
10382   return ret;
10383 }
10384
10385 // Export a struct construction.
10386
10387 void
10388 Struct_construction_expression::do_export(Export* exp) const
10389 {
10390   exp->write_c_string("convert(");
10391   exp->write_type(this->type_);
10392   for (Expression_list::const_iterator pv = this->vals_->begin();
10393        pv != this->vals_->end();
10394        ++pv)
10395     {
10396       exp->write_c_string(", ");
10397       if (*pv != NULL)
10398         (*pv)->export_expression(exp);
10399     }
10400   exp->write_c_string(")");
10401 }
10402
10403 // Make a struct composite literal.  This used by the thunk code.
10404
10405 Expression*
10406 Expression::make_struct_composite_literal(Type* type, Expression_list* vals,
10407                                           source_location location)
10408 {
10409   gcc_assert(type->struct_type() != NULL);
10410   return new Struct_construction_expression(type, vals, location);
10411 }
10412
10413 // Construct an array.  This class is not used directly; instead we
10414 // use the child classes, Fixed_array_construction_expression and
10415 // Open_array_construction_expression.
10416
10417 class Array_construction_expression : public Expression
10418 {
10419  protected:
10420   Array_construction_expression(Expression_classification classification,
10421                                 Type* type, Expression_list* vals,
10422                                 source_location location)
10423     : Expression(classification, location),
10424       type_(type), vals_(vals)
10425   { }
10426
10427  public:
10428   // Return whether this is a constant initializer.
10429   bool
10430   is_constant_array() const;
10431
10432   // Return the number of elements.
10433   size_t
10434   element_count() const
10435   { return this->vals_ == NULL ? 0 : this->vals_->size(); }
10436
10437 protected:
10438   int
10439   do_traverse(Traverse* traverse);
10440
10441   Type*
10442   do_type()
10443   { return this->type_; }
10444
10445   void
10446   do_determine_type(const Type_context*);
10447
10448   void
10449   do_check_types(Gogo*);
10450
10451   bool
10452   do_is_addressable() const
10453   { return true; }
10454
10455   void
10456   do_export(Export*) const;
10457
10458   // The list of values.
10459   Expression_list*
10460   vals()
10461   { return this->vals_; }
10462
10463   // Get a constructor tree for the array values.
10464   tree
10465   get_constructor_tree(Translate_context* context, tree type_tree);
10466
10467  private:
10468   // The type of the array to construct.
10469   Type* type_;
10470   // The list of values.
10471   Expression_list* vals_;
10472 };
10473
10474 // Traversal.
10475
10476 int
10477 Array_construction_expression::do_traverse(Traverse* traverse)
10478 {
10479   if (this->vals_ != NULL
10480       && this->vals_->traverse(traverse) == TRAVERSE_EXIT)
10481     return TRAVERSE_EXIT;
10482   if (Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
10483     return TRAVERSE_EXIT;
10484   return TRAVERSE_CONTINUE;
10485 }
10486
10487 // Return whether this is a constant initializer.
10488
10489 bool
10490 Array_construction_expression::is_constant_array() const
10491 {
10492   if (this->vals_ == NULL)
10493     return true;
10494
10495   // There are no constant constructors for interfaces.
10496   if (this->type_->array_type()->element_type()->interface_type() != NULL)
10497     return false;
10498
10499   for (Expression_list::const_iterator pv = this->vals_->begin();
10500        pv != this->vals_->end();
10501        ++pv)
10502     {
10503       if (*pv != NULL
10504           && !(*pv)->is_constant()
10505           && (!(*pv)->is_composite_literal()
10506               || (*pv)->is_nonconstant_composite_literal()))
10507         return false;
10508     }
10509   return true;
10510 }
10511
10512 // Final type determination.
10513
10514 void
10515 Array_construction_expression::do_determine_type(const Type_context*)
10516 {
10517   if (this->vals_ == NULL)
10518     return;
10519   Type_context subcontext(this->type_->array_type()->element_type(), false);
10520   for (Expression_list::const_iterator pv = this->vals_->begin();
10521        pv != this->vals_->end();
10522        ++pv)
10523     {
10524       if (*pv != NULL)
10525         (*pv)->determine_type(&subcontext);
10526     }
10527 }
10528
10529 // Check types.
10530
10531 void
10532 Array_construction_expression::do_check_types(Gogo*)
10533 {
10534   if (this->vals_ == NULL)
10535     return;
10536
10537   Array_type* at = this->type_->array_type();
10538   int i = 0;
10539   Type* element_type = at->element_type();
10540   for (Expression_list::const_iterator pv = this->vals_->begin();
10541        pv != this->vals_->end();
10542        ++pv, ++i)
10543     {
10544       if (*pv != NULL
10545           && !Type::are_assignable(element_type, (*pv)->type(), NULL))
10546         {
10547           error_at((*pv)->location(),
10548                    "incompatible type for element %d in composite literal",
10549                    i + 1);
10550           this->set_is_error();
10551         }
10552     }
10553
10554   Expression* length = at->length();
10555   if (length != NULL)
10556     {
10557       mpz_t val;
10558       mpz_init(val);
10559       Type* type;
10560       if (at->length()->integer_constant_value(true, val, &type))
10561         {
10562           if (this->vals_->size() > mpz_get_ui(val))
10563             this->report_error(_("too many elements in composite literal"));
10564         }
10565       mpz_clear(val);
10566     }
10567 }
10568
10569 // Get a constructor tree for the array values.
10570
10571 tree
10572 Array_construction_expression::get_constructor_tree(Translate_context* context,
10573                                                     tree type_tree)
10574 {
10575   VEC(constructor_elt,gc)* values = VEC_alloc(constructor_elt, gc,
10576                                               (this->vals_ == NULL
10577                                                ? 0
10578                                                : this->vals_->size()));
10579   Type* element_type = this->type_->array_type()->element_type();
10580   bool is_constant = true;
10581   if (this->vals_ != NULL)
10582     {
10583       size_t i = 0;
10584       for (Expression_list::const_iterator pv = this->vals_->begin();
10585            pv != this->vals_->end();
10586            ++pv, ++i)
10587         {
10588           constructor_elt* elt = VEC_quick_push(constructor_elt, values, NULL);
10589           elt->index = size_int(i);
10590           if (*pv == NULL)
10591             elt->value = element_type->get_init_tree(context->gogo(), false);
10592           else
10593             {
10594               tree value_tree = (*pv)->get_tree(context);
10595               elt->value = Expression::convert_for_assignment(context,
10596                                                               element_type,
10597                                                               (*pv)->type(),
10598                                                               value_tree,
10599                                                               this->location());
10600             }
10601           if (elt->value == error_mark_node)
10602             return error_mark_node;
10603           if (!TREE_CONSTANT(elt->value))
10604             is_constant = false;
10605         }
10606     }
10607
10608   tree ret = build_constructor(type_tree, values);
10609   if (is_constant)
10610     TREE_CONSTANT(ret) = 1;
10611   return ret;
10612 }
10613
10614 // Export an array construction.
10615
10616 void
10617 Array_construction_expression::do_export(Export* exp) const
10618 {
10619   exp->write_c_string("convert(");
10620   exp->write_type(this->type_);
10621   if (this->vals_ != NULL)
10622     {
10623       for (Expression_list::const_iterator pv = this->vals_->begin();
10624            pv != this->vals_->end();
10625            ++pv)
10626         {
10627           exp->write_c_string(", ");
10628           if (*pv != NULL)
10629             (*pv)->export_expression(exp);
10630         }
10631     }
10632   exp->write_c_string(")");
10633 }
10634
10635 // Construct a fixed array.
10636
10637 class Fixed_array_construction_expression :
10638   public Array_construction_expression
10639 {
10640  public:
10641   Fixed_array_construction_expression(Type* type, Expression_list* vals,
10642                                       source_location location)
10643     : Array_construction_expression(EXPRESSION_FIXED_ARRAY_CONSTRUCTION,
10644                                     type, vals, location)
10645   {
10646     gcc_assert(type->array_type() != NULL
10647                && type->array_type()->length() != NULL);
10648   }
10649
10650  protected:
10651   Expression*
10652   do_copy()
10653   {
10654     return new Fixed_array_construction_expression(this->type(),
10655                                                    (this->vals() == NULL
10656                                                     ? NULL
10657                                                     : this->vals()->copy()),
10658                                                    this->location());
10659   }
10660
10661   tree
10662   do_get_tree(Translate_context*);
10663 };
10664
10665 // Return a tree for constructing a fixed array.
10666
10667 tree
10668 Fixed_array_construction_expression::do_get_tree(Translate_context* context)
10669 {
10670   return this->get_constructor_tree(context,
10671                                     this->type()->get_tree(context->gogo()));
10672 }
10673
10674 // Construct an open array.
10675
10676 class Open_array_construction_expression : public Array_construction_expression
10677 {
10678  public:
10679   Open_array_construction_expression(Type* type, Expression_list* vals,
10680                                      source_location location)
10681     : Array_construction_expression(EXPRESSION_OPEN_ARRAY_CONSTRUCTION,
10682                                     type, vals, location)
10683   {
10684     gcc_assert(type->array_type() != NULL
10685                && type->array_type()->length() == NULL);
10686   }
10687
10688  protected:
10689   // Note that taking the address of an open array literal is invalid.
10690
10691   Expression*
10692   do_copy()
10693   {
10694     return new Open_array_construction_expression(this->type(),
10695                                                   (this->vals() == NULL
10696                                                    ? NULL
10697                                                    : this->vals()->copy()),
10698                                                   this->location());
10699   }
10700
10701   tree
10702   do_get_tree(Translate_context*);
10703 };
10704
10705 // Return a tree for constructing an open array.
10706
10707 tree
10708 Open_array_construction_expression::do_get_tree(Translate_context* context)
10709 {
10710   Type* element_type = this->type()->array_type()->element_type();
10711   tree element_type_tree = element_type->get_tree(context->gogo());
10712   tree values;
10713   tree length_tree;
10714   if (this->vals() == NULL || this->vals()->empty())
10715     {
10716       // We need to create a unique value.
10717       tree max = size_int(0);
10718       tree constructor_type = build_array_type(element_type_tree,
10719                                                build_index_type(max));
10720       if (constructor_type == error_mark_node)
10721         return error_mark_node;
10722       VEC(constructor_elt,gc)* vec = VEC_alloc(constructor_elt, gc, 1);
10723       constructor_elt* elt = VEC_quick_push(constructor_elt, vec, NULL);
10724       elt->index = size_int(0);
10725       elt->value = element_type->get_init_tree(context->gogo(), false);
10726       values = build_constructor(constructor_type, vec);
10727       if (TREE_CONSTANT(elt->value))
10728         TREE_CONSTANT(values) = 1;
10729       length_tree = size_int(0);
10730     }
10731   else
10732     {
10733       tree max = size_int(this->vals()->size() - 1);
10734       tree constructor_type = build_array_type(element_type_tree,
10735                                                build_index_type(max));
10736       if (constructor_type == error_mark_node)
10737         return error_mark_node;
10738       values = this->get_constructor_tree(context, constructor_type);
10739       length_tree = size_int(this->vals()->size());
10740     }
10741
10742   if (values == error_mark_node)
10743     return error_mark_node;
10744
10745   bool is_constant_initializer = TREE_CONSTANT(values);
10746   bool is_in_function = context->function() != NULL;
10747
10748   if (is_constant_initializer)
10749     {
10750       tree tmp = build_decl(this->location(), VAR_DECL,
10751                             create_tmp_var_name("C"), TREE_TYPE(values));
10752       DECL_EXTERNAL(tmp) = 0;
10753       TREE_PUBLIC(tmp) = 0;
10754       TREE_STATIC(tmp) = 1;
10755       DECL_ARTIFICIAL(tmp) = 1;
10756       if (is_in_function)
10757         {
10758           // If this is not a function, we will only initialize the
10759           // value once, so we can use this directly rather than
10760           // copying it.  In that case we can't make it read-only,
10761           // because the program is permitted to change it.
10762           TREE_READONLY(tmp) = 1;
10763           TREE_CONSTANT(tmp) = 1;
10764         }
10765       DECL_INITIAL(tmp) = values;
10766       rest_of_decl_compilation(tmp, 1, 0);
10767       values = tmp;
10768     }
10769
10770   tree space;
10771   tree set;
10772   if (!is_in_function && is_constant_initializer)
10773     {
10774       // Outside of a function, we know the initializer will only run
10775       // once.
10776       space = build_fold_addr_expr(values);
10777       set = NULL_TREE;
10778     }
10779   else
10780     {
10781       tree memsize = TYPE_SIZE_UNIT(TREE_TYPE(values));
10782       space = context->gogo()->allocate_memory(element_type, memsize,
10783                                                this->location());
10784       space = save_expr(space);
10785
10786       tree s = fold_convert(build_pointer_type(TREE_TYPE(values)), space);
10787       tree ref = build_fold_indirect_ref_loc(this->location(), s);
10788       TREE_THIS_NOTRAP(ref) = 1;
10789       set = build2(MODIFY_EXPR, void_type_node, ref, values);
10790     }
10791
10792   // Build a constructor for the open array.
10793
10794   tree type_tree = this->type()->get_tree(context->gogo());
10795   gcc_assert(TREE_CODE(type_tree) == RECORD_TYPE);
10796
10797   VEC(constructor_elt,gc)* init = VEC_alloc(constructor_elt, gc, 3);
10798
10799   constructor_elt* elt = VEC_quick_push(constructor_elt, init, NULL);
10800   tree field = TYPE_FIELDS(type_tree);
10801   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__values") == 0);
10802   elt->index = field;
10803   elt->value = fold_convert(TREE_TYPE(field), space);
10804
10805   elt = VEC_quick_push(constructor_elt, init, NULL);
10806   field = DECL_CHAIN(field);
10807   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__count") == 0);
10808   elt->index = field;
10809   elt->value = fold_convert(TREE_TYPE(field), length_tree);
10810
10811   elt = VEC_quick_push(constructor_elt, init, NULL);
10812   field = DECL_CHAIN(field);
10813   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)),"__capacity") == 0);
10814   elt->index = field;
10815   elt->value = fold_convert(TREE_TYPE(field), length_tree);
10816
10817   tree constructor = build_constructor(type_tree, init);
10818   if (!is_in_function && is_constant_initializer)
10819     TREE_CONSTANT(constructor) = 1;
10820
10821   if (set == NULL_TREE)
10822     return constructor;
10823   else
10824     return build2(COMPOUND_EXPR, type_tree, set, constructor);
10825 }
10826
10827 // Make a slice composite literal.  This is used by the type
10828 // descriptor code.
10829
10830 Expression*
10831 Expression::make_slice_composite_literal(Type* type, Expression_list* vals,
10832                                          source_location location)
10833 {
10834   gcc_assert(type->is_open_array_type());
10835   return new Open_array_construction_expression(type, vals, location);
10836 }
10837
10838 // Construct a map.
10839
10840 class Map_construction_expression : public Expression
10841 {
10842  public:
10843   Map_construction_expression(Type* type, Expression_list* vals,
10844                               source_location location)
10845     : Expression(EXPRESSION_MAP_CONSTRUCTION, location),
10846       type_(type), vals_(vals)
10847   { gcc_assert(vals == NULL || vals->size() % 2 == 0); }
10848
10849  protected:
10850   int
10851   do_traverse(Traverse* traverse);
10852
10853   Type*
10854   do_type()
10855   { return this->type_; }
10856
10857   void
10858   do_determine_type(const Type_context*);
10859
10860   void
10861   do_check_types(Gogo*);
10862
10863   Expression*
10864   do_copy()
10865   {
10866     return new Map_construction_expression(this->type_, this->vals_->copy(),
10867                                            this->location());
10868   }
10869
10870   tree
10871   do_get_tree(Translate_context*);
10872
10873   void
10874   do_export(Export*) const;
10875
10876  private:
10877   // The type of the map to construct.
10878   Type* type_;
10879   // The list of values.
10880   Expression_list* vals_;
10881 };
10882
10883 // Traversal.
10884
10885 int
10886 Map_construction_expression::do_traverse(Traverse* traverse)
10887 {
10888   if (this->vals_ != NULL
10889       && this->vals_->traverse(traverse) == TRAVERSE_EXIT)
10890     return TRAVERSE_EXIT;
10891   if (Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
10892     return TRAVERSE_EXIT;
10893   return TRAVERSE_CONTINUE;
10894 }
10895
10896 // Final type determination.
10897
10898 void
10899 Map_construction_expression::do_determine_type(const Type_context*)
10900 {
10901   if (this->vals_ == NULL)
10902     return;
10903
10904   Map_type* mt = this->type_->map_type();
10905   Type_context key_context(mt->key_type(), false);
10906   Type_context val_context(mt->val_type(), false);
10907   for (Expression_list::const_iterator pv = this->vals_->begin();
10908        pv != this->vals_->end();
10909        ++pv)
10910     {
10911       (*pv)->determine_type(&key_context);
10912       ++pv;
10913       (*pv)->determine_type(&val_context);
10914     }
10915 }
10916
10917 // Check types.
10918
10919 void
10920 Map_construction_expression::do_check_types(Gogo*)
10921 {
10922   if (this->vals_ == NULL)
10923     return;
10924
10925   Map_type* mt = this->type_->map_type();
10926   int i = 0;
10927   Type* key_type = mt->key_type();
10928   Type* val_type = mt->val_type();
10929   for (Expression_list::const_iterator pv = this->vals_->begin();
10930        pv != this->vals_->end();
10931        ++pv, ++i)
10932     {
10933       if (!Type::are_assignable(key_type, (*pv)->type(), NULL))
10934         {
10935           error_at((*pv)->location(),
10936                    "incompatible type for element %d key in map construction",
10937                    i + 1);
10938           this->set_is_error();
10939         }
10940       ++pv;
10941       if (!Type::are_assignable(val_type, (*pv)->type(), NULL))
10942         {
10943           error_at((*pv)->location(),
10944                    ("incompatible type for element %d value "
10945                     "in map construction"),
10946                    i + 1);
10947           this->set_is_error();
10948         }
10949     }
10950 }
10951
10952 // Return a tree for constructing a map.
10953
10954 tree
10955 Map_construction_expression::do_get_tree(Translate_context* context)
10956 {
10957   Gogo* gogo = context->gogo();
10958   source_location loc = this->location();
10959
10960   Map_type* mt = this->type_->map_type();
10961
10962   // Build a struct to hold the key and value.
10963   tree struct_type = make_node(RECORD_TYPE);
10964
10965   Type* key_type = mt->key_type();
10966   tree id = get_identifier("__key");
10967   tree key_field = build_decl(loc, FIELD_DECL, id, key_type->get_tree(gogo));
10968   DECL_CONTEXT(key_field) = struct_type;
10969   TYPE_FIELDS(struct_type) = key_field;
10970
10971   Type* val_type = mt->val_type();
10972   id = get_identifier("__val");
10973   tree val_field = build_decl(loc, FIELD_DECL, id, val_type->get_tree(gogo));
10974   DECL_CONTEXT(val_field) = struct_type;
10975   DECL_CHAIN(key_field) = val_field;
10976
10977   layout_type(struct_type);
10978
10979   bool is_constant = true;
10980   size_t i = 0;
10981   tree valaddr;
10982   tree make_tmp;
10983
10984   if (this->vals_ == NULL || this->vals_->empty())
10985     {
10986       valaddr = null_pointer_node;
10987       make_tmp = NULL_TREE;
10988     }
10989   else
10990     {
10991       VEC(constructor_elt,gc)* values = VEC_alloc(constructor_elt, gc,
10992                                                   this->vals_->size() / 2);
10993
10994       for (Expression_list::const_iterator pv = this->vals_->begin();
10995            pv != this->vals_->end();
10996            ++pv, ++i)
10997         {
10998           bool one_is_constant = true;
10999
11000           VEC(constructor_elt,gc)* one = VEC_alloc(constructor_elt, gc, 2);
11001
11002           constructor_elt* elt = VEC_quick_push(constructor_elt, one, NULL);
11003           elt->index = key_field;
11004           tree val_tree = (*pv)->get_tree(context);
11005           elt->value = Expression::convert_for_assignment(context, key_type,
11006                                                           (*pv)->type(),
11007                                                           val_tree, loc);
11008           if (elt->value == error_mark_node)
11009             return error_mark_node;
11010           if (!TREE_CONSTANT(elt->value))
11011             one_is_constant = false;
11012
11013           ++pv;
11014
11015           elt = VEC_quick_push(constructor_elt, one, NULL);
11016           elt->index = val_field;
11017           val_tree = (*pv)->get_tree(context);
11018           elt->value = Expression::convert_for_assignment(context, val_type,
11019                                                           (*pv)->type(),
11020                                                           val_tree, loc);
11021           if (elt->value == error_mark_node)
11022             return error_mark_node;
11023           if (!TREE_CONSTANT(elt->value))
11024             one_is_constant = false;
11025
11026           elt = VEC_quick_push(constructor_elt, values, NULL);
11027           elt->index = size_int(i);
11028           elt->value = build_constructor(struct_type, one);
11029           if (one_is_constant)
11030             TREE_CONSTANT(elt->value) = 1;
11031           else
11032             is_constant = false;
11033         }
11034
11035       tree index_type = build_index_type(size_int(i - 1));
11036       tree array_type = build_array_type(struct_type, index_type);
11037       tree init = build_constructor(array_type, values);
11038       if (is_constant)
11039         TREE_CONSTANT(init) = 1;
11040       tree tmp;
11041       if (current_function_decl != NULL)
11042         {
11043           tmp = create_tmp_var(array_type, get_name(array_type));
11044           DECL_INITIAL(tmp) = init;
11045           make_tmp = fold_build1_loc(loc, DECL_EXPR, void_type_node, tmp);
11046           TREE_ADDRESSABLE(tmp) = 1;
11047         }
11048       else
11049         {
11050           tmp = build_decl(loc, VAR_DECL, create_tmp_var_name("M"), array_type);
11051           DECL_EXTERNAL(tmp) = 0;
11052           TREE_PUBLIC(tmp) = 0;
11053           TREE_STATIC(tmp) = 1;
11054           DECL_ARTIFICIAL(tmp) = 1;
11055           if (!TREE_CONSTANT(init))
11056             make_tmp = fold_build2_loc(loc, INIT_EXPR, void_type_node, tmp,
11057                                        init);
11058           else
11059             {
11060               TREE_READONLY(tmp) = 1;
11061               TREE_CONSTANT(tmp) = 1;
11062               DECL_INITIAL(tmp) = init;
11063               make_tmp = NULL_TREE;
11064             }
11065           rest_of_decl_compilation(tmp, 1, 0);
11066         }
11067
11068       valaddr = build_fold_addr_expr(tmp);
11069     }
11070
11071   tree descriptor = gogo->map_descriptor(mt);
11072
11073   tree type_tree = this->type_->get_tree(gogo);
11074
11075   static tree construct_map_fndecl;
11076   tree call = Gogo::call_builtin(&construct_map_fndecl,
11077                                  loc,
11078                                  "__go_construct_map",
11079                                  6,
11080                                  type_tree,
11081                                  TREE_TYPE(descriptor),
11082                                  descriptor,
11083                                  sizetype,
11084                                  size_int(i),
11085                                  sizetype,
11086                                  TYPE_SIZE_UNIT(struct_type),
11087                                  sizetype,
11088                                  byte_position(val_field),
11089                                  sizetype,
11090                                  TYPE_SIZE_UNIT(TREE_TYPE(val_field)),
11091                                  const_ptr_type_node,
11092                                  fold_convert(const_ptr_type_node, valaddr));
11093
11094   tree ret;
11095   if (make_tmp == NULL)
11096     ret = call;
11097   else
11098     ret = fold_build2_loc(loc, COMPOUND_EXPR, type_tree, make_tmp, call);
11099   return ret;
11100 }
11101
11102 // Export an array construction.
11103
11104 void
11105 Map_construction_expression::do_export(Export* exp) const
11106 {
11107   exp->write_c_string("convert(");
11108   exp->write_type(this->type_);
11109   for (Expression_list::const_iterator pv = this->vals_->begin();
11110        pv != this->vals_->end();
11111        ++pv)
11112     {
11113       exp->write_c_string(", ");
11114       (*pv)->export_expression(exp);
11115     }
11116   exp->write_c_string(")");
11117 }
11118
11119 // A general composite literal.  This is lowered to a type specific
11120 // version.
11121
11122 class Composite_literal_expression : public Parser_expression
11123 {
11124  public:
11125   Composite_literal_expression(Type* type, int depth, bool has_keys,
11126                                Expression_list* vals, source_location location)
11127     : Parser_expression(EXPRESSION_COMPOSITE_LITERAL, location),
11128       type_(type), depth_(depth), vals_(vals), has_keys_(has_keys)
11129   { }
11130
11131  protected:
11132   int
11133   do_traverse(Traverse* traverse);
11134
11135   Expression*
11136   do_lower(Gogo*, Named_object*, int);
11137
11138   Expression*
11139   do_copy()
11140   {
11141     return new Composite_literal_expression(this->type_, this->depth_,
11142                                             this->has_keys_,
11143                                             (this->vals_ == NULL
11144                                              ? NULL
11145                                              : this->vals_->copy()),
11146                                             this->location());
11147   }
11148
11149  private:
11150   Expression*
11151   lower_struct(Type*);
11152
11153   Expression*
11154   lower_array(Type*);
11155
11156   Expression*
11157   make_array(Type*, Expression_list*);
11158
11159   Expression*
11160   lower_map(Gogo*, Named_object*, Type*);
11161
11162   // The type of the composite literal.
11163   Type* type_;
11164   // The depth within a list of composite literals within a composite
11165   // literal, when the type is omitted.
11166   int depth_;
11167   // The values to put in the composite literal.
11168   Expression_list* vals_;
11169   // If this is true, then VALS_ is a list of pairs: a key and a
11170   // value.  In an array initializer, a missing key will be NULL.
11171   bool has_keys_;
11172 };
11173
11174 // Traversal.
11175
11176 int
11177 Composite_literal_expression::do_traverse(Traverse* traverse)
11178 {
11179   if (this->vals_ != NULL
11180       && this->vals_->traverse(traverse) == TRAVERSE_EXIT)
11181     return TRAVERSE_EXIT;
11182   return Type::traverse(this->type_, traverse);
11183 }
11184
11185 // Lower a generic composite literal into a specific version based on
11186 // the type.
11187
11188 Expression*
11189 Composite_literal_expression::do_lower(Gogo* gogo, Named_object* function, int)
11190 {
11191   Type* type = this->type_;
11192
11193   for (int depth = this->depth_; depth > 0; --depth)
11194     {
11195       if (type->array_type() != NULL)
11196         type = type->array_type()->element_type();
11197       else if (type->map_type() != NULL)
11198         type = type->map_type()->val_type();
11199       else
11200         {
11201           if (!type->is_error_type())
11202             error_at(this->location(),
11203                      ("may only omit types within composite literals "
11204                       "of slice, array, or map type"));
11205           return Expression::make_error(this->location());
11206         }
11207     }
11208
11209   if (type->is_error_type())
11210     return Expression::make_error(this->location());
11211   else if (type->struct_type() != NULL)
11212     return this->lower_struct(type);
11213   else if (type->array_type() != NULL)
11214     return this->lower_array(type);
11215   else if (type->map_type() != NULL)
11216     return this->lower_map(gogo, function, type);
11217   else
11218     {
11219       error_at(this->location(),
11220                ("expected struct, slice, array, or map type "
11221                 "for composite literal"));
11222       return Expression::make_error(this->location());
11223     }
11224 }
11225
11226 // Lower a struct composite literal.
11227
11228 Expression*
11229 Composite_literal_expression::lower_struct(Type* type)
11230 {
11231   source_location location = this->location();
11232   Struct_type* st = type->struct_type();
11233   if (this->vals_ == NULL || !this->has_keys_)
11234     return new Struct_construction_expression(type, this->vals_, location);
11235
11236   size_t field_count = st->field_count();
11237   std::vector<Expression*> vals(field_count);
11238   Expression_list::const_iterator p = this->vals_->begin();
11239   while (p != this->vals_->end())
11240     {
11241       Expression* name_expr = *p;
11242
11243       ++p;
11244       gcc_assert(p != this->vals_->end());
11245       Expression* val = *p;
11246
11247       ++p;
11248
11249       if (name_expr == NULL)
11250         {
11251           error_at(val->location(), "mixture of field and value initializers");
11252           return Expression::make_error(location);
11253         }
11254
11255       bool bad_key = false;
11256       std::string name;
11257       switch (name_expr->classification())
11258         {
11259         case EXPRESSION_UNKNOWN_REFERENCE:
11260           name = name_expr->unknown_expression()->name();
11261           break;
11262
11263         case EXPRESSION_CONST_REFERENCE:
11264           name = static_cast<Const_expression*>(name_expr)->name();
11265           break;
11266
11267         case EXPRESSION_TYPE:
11268           {
11269             Type* t = name_expr->type();
11270             Named_type* nt = t->named_type();
11271             if (nt == NULL)
11272               bad_key = true;
11273             else
11274               name = nt->name();
11275           }
11276           break;
11277
11278         case EXPRESSION_VAR_REFERENCE:
11279           name = name_expr->var_expression()->name();
11280           break;
11281
11282         case EXPRESSION_FUNC_REFERENCE:
11283           name = name_expr->func_expression()->name();
11284           break;
11285
11286         case EXPRESSION_UNARY:
11287           // If there is a local variable around with the same name as
11288           // the field, and this occurs in the closure, then the
11289           // parser may turn the field reference into an indirection
11290           // through the closure.  FIXME: This is a mess.
11291           {
11292             bad_key = true;
11293             Unary_expression* ue = static_cast<Unary_expression*>(name_expr);
11294             if (ue->op() == OPERATOR_MULT)
11295               {
11296                 Field_reference_expression* fre =
11297                   ue->operand()->field_reference_expression();
11298                 if (fre != NULL)
11299                   {
11300                     Struct_type* st =
11301                       fre->expr()->type()->deref()->struct_type();
11302                     if (st != NULL)
11303                       {
11304                         const Struct_field* sf = st->field(fre->field_index());
11305                         name = sf->field_name();
11306                         char buf[20];
11307                         snprintf(buf, sizeof buf, "%u", fre->field_index());
11308                         size_t buflen = strlen(buf);
11309                         if (name.compare(name.length() - buflen, buflen, buf)
11310                             == 0)
11311                           {
11312                             name = name.substr(0, name.length() - buflen);
11313                             bad_key = false;
11314                           }
11315                       }
11316                   }
11317               }
11318           }
11319           break;
11320
11321         default:
11322           bad_key = true;
11323           break;
11324         }
11325       if (bad_key)
11326         {
11327           error_at(name_expr->location(), "expected struct field name");
11328           return Expression::make_error(location);
11329         }
11330
11331       unsigned int index;
11332       const Struct_field* sf = st->find_local_field(name, &index);
11333       if (sf == NULL)
11334         {
11335           error_at(name_expr->location(), "unknown field %qs in %qs",
11336                    Gogo::message_name(name).c_str(),
11337                    (type->named_type() != NULL
11338                     ? type->named_type()->message_name().c_str()
11339                     : "unnamed struct"));
11340           return Expression::make_error(location);
11341         }
11342       if (vals[index] != NULL)
11343         {
11344           error_at(name_expr->location(),
11345                    "duplicate value for field %qs in %qs",
11346                    Gogo::message_name(name).c_str(),
11347                    (type->named_type() != NULL
11348                     ? type->named_type()->message_name().c_str()
11349                     : "unnamed struct"));
11350           return Expression::make_error(location);
11351         }
11352
11353       vals[index] = val;
11354     }
11355
11356   Expression_list* list = new Expression_list;
11357   list->reserve(field_count);
11358   for (size_t i = 0; i < field_count; ++i)
11359     list->push_back(vals[i]);
11360
11361   return new Struct_construction_expression(type, list, location);
11362 }
11363
11364 // Lower an array composite literal.
11365
11366 Expression*
11367 Composite_literal_expression::lower_array(Type* type)
11368 {
11369   source_location location = this->location();
11370   if (this->vals_ == NULL || !this->has_keys_)
11371     return this->make_array(type, this->vals_);
11372
11373   std::vector<Expression*> vals;
11374   vals.reserve(this->vals_->size());
11375   unsigned long index = 0;
11376   Expression_list::const_iterator p = this->vals_->begin();
11377   while (p != this->vals_->end())
11378     {
11379       Expression* index_expr = *p;
11380
11381       ++p;
11382       gcc_assert(p != this->vals_->end());
11383       Expression* val = *p;
11384
11385       ++p;
11386
11387       if (index_expr != NULL)
11388         {
11389           mpz_t ival;
11390           mpz_init(ival);
11391           Type* dummy;
11392           if (!index_expr->integer_constant_value(true, ival, &dummy))
11393             {
11394               mpz_clear(ival);
11395               error_at(index_expr->location(),
11396                        "index expression is not integer constant");
11397               return Expression::make_error(location);
11398             }
11399           if (mpz_sgn(ival) < 0)
11400             {
11401               mpz_clear(ival);
11402               error_at(index_expr->location(), "index expression is negative");
11403               return Expression::make_error(location);
11404             }
11405           index = mpz_get_ui(ival);
11406           if (mpz_cmp_ui(ival, index) != 0)
11407             {
11408               mpz_clear(ival);
11409               error_at(index_expr->location(), "index value overflow");
11410               return Expression::make_error(location);
11411             }
11412           mpz_clear(ival);
11413         }
11414
11415       if (index == vals.size())
11416         vals.push_back(val);
11417       else
11418         {
11419           if (index > vals.size())
11420             {
11421               vals.reserve(index + 32);
11422               vals.resize(index + 1, static_cast<Expression*>(NULL));
11423             }
11424           if (vals[index] != NULL)
11425             {
11426               error_at((index_expr != NULL
11427                         ? index_expr->location()
11428                         : val->location()),
11429                        "duplicate value for index %lu",
11430                        index);
11431               return Expression::make_error(location);
11432             }
11433           vals[index] = val;
11434         }
11435
11436       ++index;
11437     }
11438
11439   size_t size = vals.size();
11440   Expression_list* list = new Expression_list;
11441   list->reserve(size);
11442   for (size_t i = 0; i < size; ++i)
11443     list->push_back(vals[i]);
11444
11445   return this->make_array(type, list);
11446 }
11447
11448 // Actually build the array composite literal. This handles
11449 // [...]{...}.
11450
11451 Expression*
11452 Composite_literal_expression::make_array(Type* type, Expression_list* vals)
11453 {
11454   source_location location = this->location();
11455   Array_type* at = type->array_type();
11456   if (at->length() != NULL && at->length()->is_nil_expression())
11457     {
11458       size_t size = vals == NULL ? 0 : vals->size();
11459       mpz_t vlen;
11460       mpz_init_set_ui(vlen, size);
11461       Expression* elen = Expression::make_integer(&vlen, NULL, location);
11462       mpz_clear(vlen);
11463       at = Type::make_array_type(at->element_type(), elen);
11464       type = at;
11465     }
11466   if (at->length() != NULL)
11467     return new Fixed_array_construction_expression(type, vals, location);
11468   else
11469     return new Open_array_construction_expression(type, vals, location);
11470 }
11471
11472 // Lower a map composite literal.
11473
11474 Expression*
11475 Composite_literal_expression::lower_map(Gogo* gogo, Named_object* function,
11476                                         Type* type)
11477 {
11478   source_location location = this->location();
11479   if (this->vals_ != NULL)
11480     {
11481       if (!this->has_keys_)
11482         {
11483           error_at(location, "map composite literal must have keys");
11484           return Expression::make_error(location);
11485         }
11486
11487       for (Expression_list::iterator p = this->vals_->begin();
11488            p != this->vals_->end();
11489            p += 2)
11490         {
11491           if (*p == NULL)
11492             {
11493               ++p;
11494               error_at((*p)->location(),
11495                        "map composite literal must have keys for every value");
11496               return Expression::make_error(location);
11497             }
11498           // Make sure we have lowered the key; it may not have been
11499           // lowered in order to handle keys for struct composite
11500           // literals.  Lower it now to get the right error message.
11501           if ((*p)->unknown_expression() != NULL)
11502             {
11503               (*p)->unknown_expression()->clear_is_composite_literal_key();
11504               gogo->lower_expression(function, &*p);
11505               gcc_assert((*p)->is_error_expression());
11506               return Expression::make_error(location);
11507             }
11508         }
11509     }
11510
11511   return new Map_construction_expression(type, this->vals_, location);
11512 }
11513
11514 // Make a composite literal expression.
11515
11516 Expression*
11517 Expression::make_composite_literal(Type* type, int depth, bool has_keys,
11518                                    Expression_list* vals,
11519                                    source_location location)
11520 {
11521   return new Composite_literal_expression(type, depth, has_keys, vals,
11522                                           location);
11523 }
11524
11525 // Return whether this expression is a composite literal.
11526
11527 bool
11528 Expression::is_composite_literal() const
11529 {
11530   switch (this->classification_)
11531     {
11532     case EXPRESSION_COMPOSITE_LITERAL:
11533     case EXPRESSION_STRUCT_CONSTRUCTION:
11534     case EXPRESSION_FIXED_ARRAY_CONSTRUCTION:
11535     case EXPRESSION_OPEN_ARRAY_CONSTRUCTION:
11536     case EXPRESSION_MAP_CONSTRUCTION:
11537       return true;
11538     default:
11539       return false;
11540     }
11541 }
11542
11543 // Return whether this expression is a composite literal which is not
11544 // constant.
11545
11546 bool
11547 Expression::is_nonconstant_composite_literal() const
11548 {
11549   switch (this->classification_)
11550     {
11551     case EXPRESSION_STRUCT_CONSTRUCTION:
11552       {
11553         const Struct_construction_expression *psce =
11554           static_cast<const Struct_construction_expression*>(this);
11555         return !psce->is_constant_struct();
11556       }
11557     case EXPRESSION_FIXED_ARRAY_CONSTRUCTION:
11558       {
11559         const Fixed_array_construction_expression *pace =
11560           static_cast<const Fixed_array_construction_expression*>(this);
11561         return !pace->is_constant_array();
11562       }
11563     case EXPRESSION_OPEN_ARRAY_CONSTRUCTION:
11564       {
11565         const Open_array_construction_expression *pace =
11566           static_cast<const Open_array_construction_expression*>(this);
11567         return !pace->is_constant_array();
11568       }
11569     case EXPRESSION_MAP_CONSTRUCTION:
11570       return true;
11571     default:
11572       return false;
11573     }
11574 }
11575
11576 // Return true if this is a reference to a local variable.
11577
11578 bool
11579 Expression::is_local_variable() const
11580 {
11581   const Var_expression* ve = this->var_expression();
11582   if (ve == NULL)
11583     return false;
11584   const Named_object* no = ve->named_object();
11585   return (no->is_result_variable()
11586           || (no->is_variable() && !no->var_value()->is_global()));
11587 }
11588
11589 // Class Type_guard_expression.
11590
11591 // Traversal.
11592
11593 int
11594 Type_guard_expression::do_traverse(Traverse* traverse)
11595 {
11596   if (Expression::traverse(&this->expr_, traverse) == TRAVERSE_EXIT
11597       || Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
11598     return TRAVERSE_EXIT;
11599   return TRAVERSE_CONTINUE;
11600 }
11601
11602 // Check types of a type guard expression.  The expression must have
11603 // an interface type, but the actual type conversion is checked at run
11604 // time.
11605
11606 void
11607 Type_guard_expression::do_check_types(Gogo*)
11608 {
11609   // 6g permits using a type guard with unsafe.pointer; we are
11610   // compatible.
11611   Type* expr_type = this->expr_->type();
11612   if (expr_type->is_unsafe_pointer_type())
11613     {
11614       if (this->type_->points_to() == NULL
11615           && (this->type_->integer_type() == NULL
11616               || (this->type_->forwarded()
11617                   != Type::lookup_integer_type("uintptr"))))
11618         this->report_error(_("invalid unsafe.Pointer conversion"));
11619     }
11620   else if (this->type_->is_unsafe_pointer_type())
11621     {
11622       if (expr_type->points_to() == NULL
11623           && (expr_type->integer_type() == NULL
11624               || (expr_type->forwarded()
11625                   != Type::lookup_integer_type("uintptr"))))
11626         this->report_error(_("invalid unsafe.Pointer conversion"));
11627     }
11628   else if (expr_type->interface_type() == NULL)
11629     {
11630       if (!expr_type->is_error_type() && !this->type_->is_error_type())
11631         this->report_error(_("type assertion only valid for interface types"));
11632       this->set_is_error();
11633     }
11634   else if (this->type_->interface_type() == NULL)
11635     {
11636       std::string reason;
11637       if (!expr_type->interface_type()->implements_interface(this->type_,
11638                                                              &reason))
11639         {
11640           if (!this->type_->is_error_type())
11641             {
11642               if (reason.empty())
11643                 this->report_error(_("impossible type assertion: "
11644                                      "type does not implement interface"));
11645               else
11646                 error_at(this->location(),
11647                          ("impossible type assertion: "
11648                           "type does not implement interface (%s)"),
11649                          reason.c_str());
11650             }
11651           this->set_is_error();
11652         }
11653     }
11654 }
11655
11656 // Return a tree for a type guard expression.
11657
11658 tree
11659 Type_guard_expression::do_get_tree(Translate_context* context)
11660 {
11661   Gogo* gogo = context->gogo();
11662   tree expr_tree = this->expr_->get_tree(context);
11663   if (expr_tree == error_mark_node)
11664     return error_mark_node;
11665   Type* expr_type = this->expr_->type();
11666   if ((this->type_->is_unsafe_pointer_type()
11667        && (expr_type->points_to() != NULL
11668            || expr_type->integer_type() != NULL))
11669       || (expr_type->is_unsafe_pointer_type()
11670           && this->type_->points_to() != NULL))
11671     return convert_to_pointer(this->type_->get_tree(gogo), expr_tree);
11672   else if (expr_type->is_unsafe_pointer_type()
11673            && this->type_->integer_type() != NULL)
11674     return convert_to_integer(this->type_->get_tree(gogo), expr_tree);
11675   else if (this->type_->interface_type() != NULL)
11676     return Expression::convert_interface_to_interface(context, this->type_,
11677                                                       this->expr_->type(),
11678                                                       expr_tree, true,
11679                                                       this->location());
11680   else
11681     return Expression::convert_for_assignment(context, this->type_,
11682                                               this->expr_->type(), expr_tree,
11683                                               this->location());
11684 }
11685
11686 // Make a type guard expression.
11687
11688 Expression*
11689 Expression::make_type_guard(Expression* expr, Type* type,
11690                             source_location location)
11691 {
11692   return new Type_guard_expression(expr, type, location);
11693 }
11694
11695 // Class Heap_composite_expression.
11696
11697 // When you take the address of a composite literal, it is allocated
11698 // on the heap.  This class implements that.
11699
11700 class Heap_composite_expression : public Expression
11701 {
11702  public:
11703   Heap_composite_expression(Expression* expr, source_location location)
11704     : Expression(EXPRESSION_HEAP_COMPOSITE, location),
11705       expr_(expr)
11706   { }
11707
11708  protected:
11709   int
11710   do_traverse(Traverse* traverse)
11711   { return Expression::traverse(&this->expr_, traverse); }
11712
11713   Type*
11714   do_type()
11715   { return Type::make_pointer_type(this->expr_->type()); }
11716
11717   void
11718   do_determine_type(const Type_context*)
11719   { this->expr_->determine_type_no_context(); }
11720
11721   Expression*
11722   do_copy()
11723   {
11724     return Expression::make_heap_composite(this->expr_->copy(),
11725                                            this->location());
11726   }
11727
11728   tree
11729   do_get_tree(Translate_context*);
11730
11731   // We only export global objects, and the parser does not generate
11732   // this in global scope.
11733   void
11734   do_export(Export*) const
11735   { gcc_unreachable(); }
11736
11737  private:
11738   // The composite literal which is being put on the heap.
11739   Expression* expr_;
11740 };
11741
11742 // Return a tree which allocates a composite literal on the heap.
11743
11744 tree
11745 Heap_composite_expression::do_get_tree(Translate_context* context)
11746 {
11747   tree expr_tree = this->expr_->get_tree(context);
11748   if (expr_tree == error_mark_node)
11749     return error_mark_node;
11750   tree expr_size = TYPE_SIZE_UNIT(TREE_TYPE(expr_tree));
11751   gcc_assert(TREE_CODE(expr_size) == INTEGER_CST);
11752   tree space = context->gogo()->allocate_memory(this->expr_->type(),
11753                                                 expr_size, this->location());
11754   space = fold_convert(build_pointer_type(TREE_TYPE(expr_tree)), space);
11755   space = save_expr(space);
11756   tree ref = build_fold_indirect_ref_loc(this->location(), space);
11757   TREE_THIS_NOTRAP(ref) = 1;
11758   tree ret = build2(COMPOUND_EXPR, TREE_TYPE(space),
11759                     build2(MODIFY_EXPR, void_type_node, ref, expr_tree),
11760                     space);
11761   SET_EXPR_LOCATION(ret, this->location());
11762   return ret;
11763 }
11764
11765 // Allocate a composite literal on the heap.
11766
11767 Expression*
11768 Expression::make_heap_composite(Expression* expr, source_location location)
11769 {
11770   return new Heap_composite_expression(expr, location);
11771 }
11772
11773 // Class Receive_expression.
11774
11775 // Return the type of a receive expression.
11776
11777 Type*
11778 Receive_expression::do_type()
11779 {
11780   Channel_type* channel_type = this->channel_->type()->channel_type();
11781   if (channel_type == NULL)
11782     return Type::make_error_type();
11783   return channel_type->element_type();
11784 }
11785
11786 // Check types for a receive expression.
11787
11788 void
11789 Receive_expression::do_check_types(Gogo*)
11790 {
11791   Type* type = this->channel_->type();
11792   if (type->is_error_type())
11793     {
11794       this->set_is_error();
11795       return;
11796     }
11797   if (type->channel_type() == NULL)
11798     {
11799       this->report_error(_("expected channel"));
11800       return;
11801     }
11802   if (!type->channel_type()->may_receive())
11803     {
11804       this->report_error(_("invalid receive on send-only channel"));
11805       return;
11806     }
11807 }
11808
11809 // Get a tree for a receive expression.
11810
11811 tree
11812 Receive_expression::do_get_tree(Translate_context* context)
11813 {
11814   Channel_type* channel_type = this->channel_->type()->channel_type();
11815   gcc_assert(channel_type != NULL);
11816   Type* element_type = channel_type->element_type();
11817   tree element_type_tree = element_type->get_tree(context->gogo());
11818
11819   tree channel = this->channel_->get_tree(context);
11820   if (element_type_tree == error_mark_node || channel == error_mark_node)
11821     return error_mark_node;
11822
11823   return Gogo::receive_from_channel(element_type_tree, channel,
11824                                     this->for_select_, this->location());
11825 }
11826
11827 // Make a receive expression.
11828
11829 Receive_expression*
11830 Expression::make_receive(Expression* channel, source_location location)
11831 {
11832   return new Receive_expression(channel, location);
11833 }
11834
11835 // Class Send_expression.
11836
11837 // Traversal.
11838
11839 int
11840 Send_expression::do_traverse(Traverse* traverse)
11841 {
11842   if (Expression::traverse(&this->channel_, traverse) == TRAVERSE_EXIT)
11843     return TRAVERSE_EXIT;
11844   return Expression::traverse(&this->val_, traverse);
11845 }
11846
11847 // Get the type.
11848
11849 Type*
11850 Send_expression::do_type()
11851 {
11852   return Type::lookup_bool_type();
11853 }
11854
11855 // Set types.
11856
11857 void
11858 Send_expression::do_determine_type(const Type_context*)
11859 {
11860   this->channel_->determine_type_no_context();
11861
11862   Type* type = this->channel_->type();
11863   Type_context subcontext;
11864   if (type->channel_type() != NULL)
11865     subcontext.type = type->channel_type()->element_type();
11866   this->val_->determine_type(&subcontext);
11867 }
11868
11869 // Check types.
11870
11871 void
11872 Send_expression::do_check_types(Gogo*)
11873 {
11874   Type* type = this->channel_->type();
11875   if (type->is_error_type())
11876     {
11877       this->set_is_error();
11878       return;
11879     }
11880   Channel_type* channel_type = type->channel_type();
11881   if (channel_type == NULL)
11882     {
11883       error_at(this->location(), "left operand of %<<-%> must be channel");
11884       this->set_is_error();
11885       return;
11886     }
11887   Type* element_type = channel_type->element_type();
11888   if (element_type != NULL
11889       && !Type::are_assignable(element_type, this->val_->type(), NULL))
11890     {
11891       this->report_error(_("incompatible types in send"));
11892       return;
11893     }
11894   if (!channel_type->may_send())
11895     {
11896       this->report_error(_("invalid send on receive-only channel"));
11897       return;
11898     }
11899 }
11900
11901 // Get a tree for a send expression.
11902
11903 tree
11904 Send_expression::do_get_tree(Translate_context* context)
11905 {
11906   tree channel = this->channel_->get_tree(context);
11907   tree val = this->val_->get_tree(context);
11908   if (channel == error_mark_node || val == error_mark_node)
11909     return error_mark_node;
11910   Channel_type* channel_type = this->channel_->type()->channel_type();
11911   val = Expression::convert_for_assignment(context,
11912                                            channel_type->element_type(),
11913                                            this->val_->type(),
11914                                            val,
11915                                            this->location());
11916   return Gogo::send_on_channel(channel, val, this->is_value_discarded_,
11917                                this->for_select_, this->location());
11918 }
11919
11920 // Make a send expression
11921
11922 Send_expression*
11923 Expression::make_send(Expression* channel, Expression* val,
11924                       source_location location)
11925 {
11926   return new Send_expression(channel, val, location);
11927 }
11928
11929 // An expression which evaluates to a pointer to the type descriptor
11930 // of a type.
11931
11932 class Type_descriptor_expression : public Expression
11933 {
11934  public:
11935   Type_descriptor_expression(Type* type, source_location location)
11936     : Expression(EXPRESSION_TYPE_DESCRIPTOR, location),
11937       type_(type)
11938   { }
11939
11940  protected:
11941   Type*
11942   do_type()
11943   { return Type::make_type_descriptor_ptr_type(); }
11944
11945   void
11946   do_determine_type(const Type_context*)
11947   { }
11948
11949   Expression*
11950   do_copy()
11951   { return this; }
11952
11953   tree
11954   do_get_tree(Translate_context* context)
11955   { return this->type_->type_descriptor_pointer(context->gogo()); }
11956
11957  private:
11958   // The type for which this is the descriptor.
11959   Type* type_;
11960 };
11961
11962 // Make a type descriptor expression.
11963
11964 Expression*
11965 Expression::make_type_descriptor(Type* type, source_location location)
11966 {
11967   return new Type_descriptor_expression(type, location);
11968 }
11969
11970 // An expression which evaluates to some characteristic of a type.
11971 // This is only used to initialize fields of a type descriptor.  Using
11972 // a new expression class is slightly inefficient but gives us a good
11973 // separation between the frontend and the middle-end with regard to
11974 // how types are laid out.
11975
11976 class Type_info_expression : public Expression
11977 {
11978  public:
11979   Type_info_expression(Type* type, Type_info type_info)
11980     : Expression(EXPRESSION_TYPE_INFO, BUILTINS_LOCATION),
11981       type_(type), type_info_(type_info)
11982   { }
11983
11984  protected:
11985   Type*
11986   do_type();
11987
11988   void
11989   do_determine_type(const Type_context*)
11990   { }
11991
11992   Expression*
11993   do_copy()
11994   { return this; }
11995
11996   tree
11997   do_get_tree(Translate_context* context);
11998
11999  private:
12000   // The type for which we are getting information.
12001   Type* type_;
12002   // What information we want.
12003   Type_info type_info_;
12004 };
12005
12006 // The type is chosen to match what the type descriptor struct
12007 // expects.
12008
12009 Type*
12010 Type_info_expression::do_type()
12011 {
12012   switch (this->type_info_)
12013     {
12014     case TYPE_INFO_SIZE:
12015       return Type::lookup_integer_type("uintptr");
12016     case TYPE_INFO_ALIGNMENT:
12017     case TYPE_INFO_FIELD_ALIGNMENT:
12018       return Type::lookup_integer_type("uint8");
12019     default:
12020       gcc_unreachable();
12021     }
12022 }
12023
12024 // Return type information in GENERIC.
12025
12026 tree
12027 Type_info_expression::do_get_tree(Translate_context* context)
12028 {
12029   tree type_tree = this->type_->get_tree(context->gogo());
12030   if (type_tree == error_mark_node)
12031     return error_mark_node;
12032
12033   tree val_type_tree = this->type()->get_tree(context->gogo());
12034   gcc_assert(val_type_tree != error_mark_node);
12035
12036   if (this->type_info_ == TYPE_INFO_SIZE)
12037     return fold_convert_loc(BUILTINS_LOCATION, val_type_tree,
12038                             TYPE_SIZE_UNIT(type_tree));
12039   else
12040     {
12041       unsigned int val;
12042       if (this->type_info_ == TYPE_INFO_ALIGNMENT)
12043         val = go_type_alignment(type_tree);
12044       else
12045         val = go_field_alignment(type_tree);
12046       return build_int_cstu(val_type_tree, val);
12047     }
12048 }
12049
12050 // Make a type info expression.
12051
12052 Expression*
12053 Expression::make_type_info(Type* type, Type_info type_info)
12054 {
12055   return new Type_info_expression(type, type_info);
12056 }
12057
12058 // An expression which evaluates to the offset of a field within a
12059 // struct.  This, like Type_info_expression, q.v., is only used to
12060 // initialize fields of a type descriptor.
12061
12062 class Struct_field_offset_expression : public Expression
12063 {
12064  public:
12065   Struct_field_offset_expression(Struct_type* type, const Struct_field* field)
12066     : Expression(EXPRESSION_STRUCT_FIELD_OFFSET, BUILTINS_LOCATION),
12067       type_(type), field_(field)
12068   { }
12069
12070  protected:
12071   Type*
12072   do_type()
12073   { return Type::lookup_integer_type("uintptr"); }
12074
12075   void
12076   do_determine_type(const Type_context*)
12077   { }
12078
12079   Expression*
12080   do_copy()
12081   { return this; }
12082
12083   tree
12084   do_get_tree(Translate_context* context);
12085
12086  private:
12087   // The type of the struct.
12088   Struct_type* type_;
12089   // The field.
12090   const Struct_field* field_;
12091 };
12092
12093 // Return a struct field offset in GENERIC.
12094
12095 tree
12096 Struct_field_offset_expression::do_get_tree(Translate_context* context)
12097 {
12098   tree type_tree = this->type_->get_tree(context->gogo());
12099   if (type_tree == error_mark_node)
12100     return error_mark_node;
12101
12102   tree val_type_tree = this->type()->get_tree(context->gogo());
12103   gcc_assert(val_type_tree != error_mark_node);
12104
12105   const Struct_field_list* fields = this->type_->fields();
12106   tree struct_field_tree = TYPE_FIELDS(type_tree);
12107   Struct_field_list::const_iterator p;
12108   for (p = fields->begin();
12109        p != fields->end();
12110        ++p, struct_field_tree = DECL_CHAIN(struct_field_tree))
12111     {
12112       gcc_assert(struct_field_tree != NULL_TREE);
12113       if (&*p == this->field_)
12114         break;
12115     }
12116   gcc_assert(&*p == this->field_);
12117
12118   return fold_convert_loc(BUILTINS_LOCATION, val_type_tree,
12119                           byte_position(struct_field_tree));
12120 }
12121
12122 // Make an expression for a struct field offset.
12123
12124 Expression*
12125 Expression::make_struct_field_offset(Struct_type* type,
12126                                      const Struct_field* field)
12127 {
12128   return new Struct_field_offset_expression(type, field);
12129 }
12130
12131 // An expression which evaluates to the address of an unnamed label.
12132
12133 class Label_addr_expression : public Expression
12134 {
12135  public:
12136   Label_addr_expression(Label* label, source_location location)
12137     : Expression(EXPRESSION_LABEL_ADDR, location),
12138       label_(label)
12139   { }
12140
12141  protected:
12142   Type*
12143   do_type()
12144   { return Type::make_pointer_type(Type::make_void_type()); }
12145
12146   void
12147   do_determine_type(const Type_context*)
12148   { }
12149
12150   Expression*
12151   do_copy()
12152   { return new Label_addr_expression(this->label_, this->location()); }
12153
12154   tree
12155   do_get_tree(Translate_context*)
12156   { return this->label_->get_addr(this->location()); }
12157
12158  private:
12159   // The label whose address we are taking.
12160   Label* label_;
12161 };
12162
12163 // Make an expression for the address of an unnamed label.
12164
12165 Expression*
12166 Expression::make_label_addr(Label* label, source_location location)
12167 {
12168   return new Label_addr_expression(label, location);
12169 }
12170
12171 // Import an expression.  This comes at the end in order to see the
12172 // various class definitions.
12173
12174 Expression*
12175 Expression::import_expression(Import* imp)
12176 {
12177   int c = imp->peek_char();
12178   if (imp->match_c_string("- ")
12179       || imp->match_c_string("! ")
12180       || imp->match_c_string("^ "))
12181     return Unary_expression::do_import(imp);
12182   else if (c == '(')
12183     return Binary_expression::do_import(imp);
12184   else if (imp->match_c_string("true")
12185            || imp->match_c_string("false"))
12186     return Boolean_expression::do_import(imp);
12187   else if (c == '"')
12188     return String_expression::do_import(imp);
12189   else if (c == '-' || (c >= '0' && c <= '9'))
12190     {
12191       // This handles integers, floats and complex constants.
12192       return Integer_expression::do_import(imp);
12193     }
12194   else if (imp->match_c_string("nil"))
12195     return Nil_expression::do_import(imp);
12196   else if (imp->match_c_string("convert"))
12197     return Type_conversion_expression::do_import(imp);
12198   else
12199     {
12200       error_at(imp->location(), "import error: expected expression");
12201       return Expression::make_error(imp->location());
12202     }
12203 }
12204
12205 // Class Expression_list.
12206
12207 // Traverse the list.
12208
12209 int
12210 Expression_list::traverse(Traverse* traverse)
12211 {
12212   for (Expression_list::iterator p = this->begin();
12213        p != this->end();
12214        ++p)
12215     {
12216       if (*p != NULL)
12217         {
12218           if (Expression::traverse(&*p, traverse) == TRAVERSE_EXIT)
12219             return TRAVERSE_EXIT;
12220         }
12221     }
12222   return TRAVERSE_CONTINUE;
12223 }
12224
12225 // Copy the list.
12226
12227 Expression_list*
12228 Expression_list::copy()
12229 {
12230   Expression_list* ret = new Expression_list();
12231   for (Expression_list::iterator p = this->begin();
12232        p != this->end();
12233        ++p)
12234     {
12235       if (*p == NULL)
12236         ret->push_back(NULL);
12237       else
12238         ret->push_back((*p)->copy());
12239     }
12240   return ret;
12241 }
12242
12243 // Return whether an expression list has an error expression.
12244
12245 bool
12246 Expression_list::contains_error() const
12247 {
12248   for (Expression_list::const_iterator p = this->begin();
12249        p != this->end();
12250        ++p)
12251     if (*p != NULL && (*p)->is_error_expression())
12252       return true;
12253   return false;
12254 }