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       if (call == error_mark_node)
 509         return error_mark_node;
 510       // This will panic if the interface conversion fails.
 511       TREE_NOTHROW(assert_interface_decl) = 0;
 512       elt->value = fold_convert_loc(location, TREE_TYPE(field), call);
 513     }
 514   else if (lhs_is_empty)
 515     {
 516       // A convertion to an empty interface always succeeds, and the
 517       // first field is just the type descriptor of the object.
 518       gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)),
 519                         "__type_descriptor") == 0);
 520       gcc_assert(TREE_TYPE(field) == TREE_TYPE(rhs_type_descriptor));
 521       elt->value = rhs_type_descriptor;
 522     }
 523   else
 524     {
 525       // A conversion to a non-empty interface may fail, but unlike a
 526       // type assertion converting nil will always succeed.
 527       gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__methods")
 528                  == 0);
 529       tree lhs_type_descriptor = lhs_type->type_descriptor_pointer(gogo);
 530       static tree convert_interface_decl;
 531       tree call = Gogo::call_builtin(&convert_interface_decl,
 532                                      location,
 533                                      "__go_convert_interface",
 534                                      2,
 535                                      ptr_type_node,
 536                                      TREE_TYPE(lhs_type_descriptor),
 537                                      lhs_type_descriptor,
 538                                      TREE_TYPE(rhs_type_descriptor),
 539                                      rhs_type_descriptor);
 540       if (call == error_mark_node)
 541         return error_mark_node;
 542       // This will panic if the interface conversion fails.
 543       TREE_NOTHROW(convert_interface_decl) = 0;
 544       elt->value = fold_convert_loc(location, TREE_TYPE(field), call);
 545     }
 546
 547   // The second field is simply the object pointer.
 548
 549   elt = VEC_quick_push(constructor_elt, init, NULL);
 550   field = DECL_CHAIN(field);
 551   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__object") == 0);
 552   elt->index = field;
 553
 554   tree rhs_type_tree = TREE_TYPE(rhs_tree);
 555   gcc_assert(TREE_CODE(rhs_type_tree) == RECORD_TYPE);
 556   tree rhs_field = DECL_CHAIN(TYPE_FIELDS(rhs_type_tree));
 557   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(rhs_field)), "__object") == 0);
 558   elt->value = build3(COMPONENT_REF, TREE_TYPE(rhs_field), rhs_tree, rhs_field,
 559                       NULL_TREE);
 560
 561   return build_constructor(lhs_type_tree, init);
 562 }
 563
 564 // Return a tree for the conversion of an interface type to a
 565 // non-interface type.
 566
 567 tree
 568 Expression::convert_interface_to_type(Translate_context* context,
 569                                       Type *lhs_type, Type* rhs_type,
 570                                       tree rhs_tree, source_location location)
 571 {
 572   Gogo* gogo = context->gogo();
 573   tree rhs_type_tree = TREE_TYPE(rhs_tree);
 574
 575   tree lhs_type_tree = lhs_type->get_tree(gogo);
 576   if (lhs_type_tree == error_mark_node)
 577     return error_mark_node;
 578
 579   // Call a function to check that the type is valid.  The function
 580   // will panic with an appropriate runtime type error if the type is
 581   // not valid.
 582
 583   tree lhs_type_descriptor = lhs_type->type_descriptor_pointer(gogo);
 584
 585   if (!DECL_P(rhs_tree))
 586     rhs_tree = save_expr(rhs_tree);
 587
 588   tree rhs_type_descriptor =
 589     Expression::get_interface_type_descriptor(context, rhs_type, rhs_tree,
 590                                               location);
 591
 592   tree rhs_inter_descriptor = rhs_type->type_descriptor_pointer(gogo);
 593
 594   static tree check_interface_type_decl;
 595   tree call = Gogo::call_builtin(&check_interface_type_decl,
 596                                  location,
 597                                  "__go_check_interface_type",
 598                                  3,
 599                                  void_type_node,
 600                                  TREE_TYPE(lhs_type_descriptor),
 601                                  lhs_type_descriptor,
 602                                  TREE_TYPE(rhs_type_descriptor),
 603                                  rhs_type_descriptor,
 604                                  TREE_TYPE(rhs_inter_descriptor),
 605                                  rhs_inter_descriptor);
 606   if (call == error_mark_node)
 607     return error_mark_node;
 608   // This call will panic if the conversion is invalid.
 609   TREE_NOTHROW(check_interface_type_decl) = 0;
 610
 611   // If the call succeeds, pull out the value.
 612   gcc_assert(TREE_CODE(rhs_type_tree) == RECORD_TYPE);
 613   tree rhs_field = DECL_CHAIN(TYPE_FIELDS(rhs_type_tree));
 614   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(rhs_field)), "__object") == 0);
 615   tree val = build3(COMPONENT_REF, TREE_TYPE(rhs_field), rhs_tree, rhs_field,
 616                     NULL_TREE);
 617
 618   // If the value is a pointer, then it is the value we want.
 619   // Otherwise it points to the value.
 620   if (lhs_type->points_to() == NULL)
 621     {
 622       val = fold_convert_loc(location, build_pointer_type(lhs_type_tree), val);
 623       val = build_fold_indirect_ref_loc(location, val);
 624     }
 625
 626   return build2(COMPOUND_EXPR, lhs_type_tree, call,
 627                 fold_convert_loc(location, lhs_type_tree, val));
 628 }
 629
 630 // Convert an expression to a tree.  This is implemented by the child
 631 // class.  Not that it is not in general safe to call this multiple
 632 // times for a single expression, but that we don't catch such errors.
 633
 634 tree
 635 Expression::get_tree(Translate_context* context)
 636 {
 637   // The child may have marked this expression as having an error.
 638   if (this->classification_ == EXPRESSION_ERROR)
 639     return error_mark_node;
 640
 641   return this->do_get_tree(context);
 642 }
 643
 644 // Return a tree for VAL in TYPE.
 645
 646 tree
 647 Expression::integer_constant_tree(mpz_t val, tree type)
 648 {
 649   if (type == error_mark_node)
 650     return error_mark_node;
 651   else if (TREE_CODE(type) == INTEGER_TYPE)
 652     return double_int_to_tree(type,
 653                               mpz_get_double_int(type, val, true));
 654   else if (TREE_CODE(type) == REAL_TYPE)
 655     {
 656       mpfr_t fval;
 657       mpfr_init_set_z(fval, val, GMP_RNDN);
 658       tree ret = Expression::float_constant_tree(fval, type);
 659       mpfr_clear(fval);
 660       return ret;
 661     }
 662   else if (TREE_CODE(type) == COMPLEX_TYPE)
 663     {
 664       mpfr_t fval;
 665       mpfr_init_set_z(fval, val, GMP_RNDN);
 666       tree real = Expression::float_constant_tree(fval, TREE_TYPE(type));
 667       mpfr_clear(fval);
 668       tree imag = build_real_from_int_cst(TREE_TYPE(type),
 669                                           integer_zero_node);
 670       return build_complex(type, real, imag);
 671     }
 672   else
 673     gcc_unreachable();
 674 }
 675
 676 // Return a tree for VAL in TYPE.
 677
 678 tree
 679 Expression::float_constant_tree(mpfr_t val, tree type)
 680 {
 681   if (type == error_mark_node)
 682     return error_mark_node;
 683   else if (TREE_CODE(type) == INTEGER_TYPE)
 684     {
 685       mpz_t ival;
 686       mpz_init(ival);
 687       mpfr_get_z(ival, val, GMP_RNDN);
 688       tree ret = Expression::integer_constant_tree(ival, type);
 689       mpz_clear(ival);
 690       return ret;
 691     }
 692   else if (TREE_CODE(type) == REAL_TYPE)
 693     {
 694       REAL_VALUE_TYPE r1;
 695       real_from_mpfr(&r1, val, type, GMP_RNDN);
 696       REAL_VALUE_TYPE r2;
 697       real_convert(&r2, TYPE_MODE(type), &r1);
 698       return build_real(type, r2);
 699     }
 700   else if (TREE_CODE(type) == COMPLEX_TYPE)
 701     {
 702       REAL_VALUE_TYPE r1;
 703       real_from_mpfr(&r1, val, TREE_TYPE(type), GMP_RNDN);
 704       REAL_VALUE_TYPE r2;
 705       real_convert(&r2, TYPE_MODE(TREE_TYPE(type)), &r1);
 706       tree imag = build_real_from_int_cst(TREE_TYPE(type),
 707                                           integer_zero_node);
 708       return build_complex(type, build_real(TREE_TYPE(type), r2), imag);
 709     }
 710   else
 711     gcc_unreachable();
 712 }
 713
 714 // Return a tree for REAL/IMAG in TYPE.
 715
 716 tree
 717 Expression::complex_constant_tree(mpfr_t real, mpfr_t imag, tree type)
 718 {
 719   if (TREE_CODE(type) == COMPLEX_TYPE)
 720     {
 721       REAL_VALUE_TYPE r1;
 722       real_from_mpfr(&r1, real, TREE_TYPE(type), GMP_RNDN);
 723       REAL_VALUE_TYPE r2;
 724       real_convert(&r2, TYPE_MODE(TREE_TYPE(type)), &r1);
 725
 726       REAL_VALUE_TYPE r3;
 727       real_from_mpfr(&r3, imag, TREE_TYPE(type), GMP_RNDN);
 728       REAL_VALUE_TYPE r4;
 729       real_convert(&r4, TYPE_MODE(TREE_TYPE(type)), &r3);
 730
 731       return build_complex(type, build_real(TREE_TYPE(type), r2),
 732                            build_real(TREE_TYPE(type), r4));
 733     }
 734   else
 735     gcc_unreachable();
 736 }
 737
 738 // Return a tree which evaluates to true if VAL, of arbitrary integer
 739 // type, is negative or is more than the maximum value of BOUND_TYPE.
 740 // If SOFAR is not NULL, it is or'red into the result.  The return
 741 // value may be NULL if SOFAR is NULL.
 742
 743 tree
 744 Expression::check_bounds(tree val, tree bound_type, tree sofar,
 745                          source_location loc)
 746 {
 747   tree val_type = TREE_TYPE(val);
 748   tree ret = NULL_TREE;
 749
 750   if (!TYPE_UNSIGNED(val_type))
 751     {
 752       ret = fold_build2_loc(loc, LT_EXPR, boolean_type_node, val,
 753                             build_int_cst(val_type, 0));
 754       if (ret == boolean_false_node)
 755         ret = NULL_TREE;
 756     }
 757
 758   if ((TYPE_UNSIGNED(val_type) && !TYPE_UNSIGNED(bound_type))
 759       || TYPE_SIZE(val_type) > TYPE_SIZE(bound_type))
 760     {
 761       tree max = TYPE_MAX_VALUE(bound_type);
 762       tree big = fold_build2_loc(loc, GT_EXPR, boolean_type_node, val,
 763                                  fold_convert_loc(loc, val_type, max));
 764       if (big == boolean_false_node)
 765         ;
 766       else if (ret == NULL_TREE)
 767         ret = big;
 768       else
 769         ret = fold_build2_loc(loc, TRUTH_OR_EXPR, boolean_type_node,
 770                               ret, big);
 771     }
 772
 773   if (ret == NULL_TREE)
 774     return sofar;
 775   else if (sofar == NULL_TREE)
 776     return ret;
 777   else
 778     return fold_build2_loc(loc, TRUTH_OR_EXPR, boolean_type_node,
 779                            sofar, ret);
 780 }
 781
 782 // Error expressions.  This are used to avoid cascading errors.
 783
 784 class Error_expression : public Expression
 785 {
 786  public:
 787   Error_expression(source_location location)
 788     : Expression(EXPRESSION_ERROR, location)
 789   { }
 790
 791  protected:
 792   bool
 793   do_is_constant() const
 794   { return true; }
 795
 796   bool
 797   do_integer_constant_value(bool, mpz_t val, Type**) const
 798   {
 799     mpz_set_ui(val, 0);
 800     return true;
 801   }
 802
 803   bool
 804   do_float_constant_value(mpfr_t val, Type**) const
 805   {
 806     mpfr_set_ui(val, 0, GMP_RNDN);
 807     return true;
 808   }
 809
 810   bool
 811   do_complex_constant_value(mpfr_t real, mpfr_t imag, Type**) const
 812   {
 813     mpfr_set_ui(real, 0, GMP_RNDN);
 814     mpfr_set_ui(imag, 0, GMP_RNDN);
 815     return true;
 816   }
 817
 818   void
 819   do_discarding_value()
 820   { }
 821
 822   Type*
 823   do_type()
 824   { return Type::make_error_type(); }
 825
 826   void
 827   do_determine_type(const Type_context*)
 828   { }
 829
 830   Expression*
 831   do_copy()
 832   { return this; }
 833
 834   bool
 835   do_is_addressable() const
 836   { return true; }
 837
 838   tree
 839   do_get_tree(Translate_context*)
 840   { return error_mark_node; }
 841 };
 842
 843 Expression*
 844 Expression::make_error(source_location location)
 845 {
 846   return new Error_expression(location);
 847 }
 848
 849 // An expression which is really a type.  This is used during parsing.
 850 // It is an error if these survive after lowering.
 851
 852 class
 853 Type_expression : public Expression
 854 {
 855  public:
 856   Type_expression(Type* type, source_location location)
 857     : Expression(EXPRESSION_TYPE, location),
 858       type_(type)
 859   { }
 860
 861  protected:
 862   int
 863   do_traverse(Traverse* traverse)
 864   { return Type::traverse(this->type_, traverse); }
 865
 866   Type*
 867   do_type()
 868   { return this->type_; }
 869
 870   void
 871   do_determine_type(const Type_context*)
 872   { }
 873
 874   void
 875   do_check_types(Gogo*)
 876   { this->report_error(_("invalid use of type")); }
 877
 878   Expression*
 879   do_copy()
 880   { return this; }
 881
 882   tree
 883   do_get_tree(Translate_context*)
 884   { gcc_unreachable(); }
 885
 886  private:
 887   // The type which we are representing as an expression.
 888   Type* type_;
 889 };
 890
 891 Expression*
 892 Expression::make_type(Type* type, source_location location)
 893 {
 894   return new Type_expression(type, location);
 895 }
 896
 897 // Class Var_expression.
 898
 899 // Lower a variable expression.  Here we just make sure that the
 900 // initialization expression of the variable has been lowered.  This
 901 // ensures that we will be able to determine the type of the variable
 902 // if necessary.
 903
 904 Expression*
 905 Var_expression::do_lower(Gogo* gogo, Named_object* function, int)
 906 {
 907   if (this->variable_->is_variable())
 908     {
 909       Variable* var = this->variable_->var_value();
 910       // This is either a local variable or a global variable.  A
 911       // reference to a variable which is local to an enclosing
 912       // function will be a reference to a field in a closure.
 913       if (var->is_global())
 914         function = NULL;
 915       var->lower_init_expression(gogo, function);
 916     }
 917   return this;
 918 }
 919
 920 // Return the name of the variable.
 921
 922 const std::string&
 923 Var_expression::name() const
 924 {
 925   return this->variable_->name();
 926 }
 927
 928 // Return the type of a reference to a variable.
 929
 930 Type*
 931 Var_expression::do_type()
 932 {
 933   if (this->variable_->is_variable())
 934     return this->variable_->var_value()->type();
 935   else if (this->variable_->is_result_variable())
 936     return this->variable_->result_var_value()->type();
 937   else
 938     gcc_unreachable();
 939 }
 940
 941 // Something takes the address of this variable.  This means that we
 942 // may want to move the variable onto the heap.
 943
 944 void
 945 Var_expression::do_address_taken(bool escapes)
 946 {
 947   if (!escapes)
 948     ;
 949   else if (this->variable_->is_variable())
 950     this->variable_->var_value()->set_address_taken();
 951   else if (this->variable_->is_result_variable())
 952     this->variable_->result_var_value()->set_address_taken();
 953   else
 954     gcc_unreachable();
 955 }
 956
 957 // Get the tree for a reference to a variable.
 958
 959 tree
 960 Var_expression::do_get_tree(Translate_context* context)
 961 {
 962   return this->variable_->get_tree(context->gogo(), context->function());
 963 }
 964
 965 // Make a reference to a variable in an expression.
 966
 967 Expression*
 968 Expression::make_var_reference(Named_object* var, source_location location)
 969 {
 970   if (var->is_sink())
 971     return Expression::make_sink(location);
 972
 973   // FIXME: Creating a new object for each reference to a variable is
 974   // wasteful.
 975   return new Var_expression(var, location);
 976 }
 977
 978 // Class Temporary_reference_expression.
 979
 980 // The type.
 981
 982 Type*
 983 Temporary_reference_expression::do_type()
 984 {
 985   return this->statement_->type();
 986 }
 987
 988 // Called if something takes the address of this temporary variable.
 989 // We never have to move temporary variables to the heap, but we do
 990 // need to know that they must live in the stack rather than in a
 991 // register.
 992
 993 void
 994 Temporary_reference_expression::do_address_taken(bool)
 995 {
 996   this->statement_->set_is_address_taken();
 997 }
 998
 999 // Get a tree referring to the variable.
1000
1001 tree
1002 Temporary_reference_expression::do_get_tree(Translate_context*)
1003 {
1004   return this->statement_->get_decl();
1005 }
1006
1007 // Make a reference to a temporary variable.
1008
1009 Expression*
1010 Expression::make_temporary_reference(Temporary_statement* statement,
1011                                      source_location location)
1012 {
1013   return new Temporary_reference_expression(statement, location);
1014 }
1015
1016 // A sink expression--a use of the blank identifier _.
1017
1018 class Sink_expression : public Expression
1019 {
1020  public:
1021   Sink_expression(source_location location)
1022     : Expression(EXPRESSION_SINK, location),
1023       type_(NULL), var_(NULL_TREE)
1024   { }
1025
1026  protected:
1027   void
1028   do_discarding_value()
1029   { }
1030
1031   Type*
1032   do_type();
1033
1034   void
1035   do_determine_type(const Type_context*);
1036
1037   Expression*
1038   do_copy()
1039   { return new Sink_expression(this->location()); }
1040
1041   tree
1042   do_get_tree(Translate_context*);
1043
1044  private:
1045   // The type of this sink variable.
1046   Type* type_;
1047   // The temporary variable we generate.
1048   tree var_;
1049 };
1050
1051 // Return the type of a sink expression.
1052
1053 Type*
1054 Sink_expression::do_type()
1055 {
1056   if (this->type_ == NULL)
1057     return Type::make_sink_type();
1058   return this->type_;
1059 }
1060
1061 // Determine the type of a sink expression.
1062
1063 void
1064 Sink_expression::do_determine_type(const Type_context* context)
1065 {
1066   if (context->type != NULL)
1067     this->type_ = context->type;
1068 }
1069
1070 // Return a temporary variable for a sink expression.  This will
1071 // presumably be a write-only variable which the middle-end will drop.
1072
1073 tree
1074 Sink_expression::do_get_tree(Translate_context* context)
1075 {
1076   if (this->var_ == NULL_TREE)
1077     {
1078       gcc_assert(this->type_ != NULL && !this->type_->is_sink_type());
1079       this->var_ = create_tmp_var(this->type_->get_tree(context->gogo()),
1080                                   "blank");
1081     }
1082   return this->var_;
1083 }
1084
1085 // Make a sink expression.
1086
1087 Expression*
1088 Expression::make_sink(source_location location)
1089 {
1090   return new Sink_expression(location);
1091 }
1092
1093 // Class Func_expression.
1094
1095 // FIXME: Can a function expression appear in a constant expression?
1096 // The value is unchanging.  Initializing a constant to the address of
1097 // a function seems like it could work, though there might be little
1098 // point to it.
1099
1100 // Return the name of the function.
1101
1102 const std::string&
1103 Func_expression::name() const
1104 {
1105   return this->function_->name();
1106 }
1107
1108 // Traversal.
1109
1110 int
1111 Func_expression::do_traverse(Traverse* traverse)
1112 {
1113   return (this->closure_ == NULL
1114           ? TRAVERSE_CONTINUE
1115           : Expression::traverse(&this->closure_, traverse));
1116 }
1117
1118 // Return the type of a function expression.
1119
1120 Type*
1121 Func_expression::do_type()
1122 {
1123   if (this->function_->is_function())
1124     return this->function_->func_value()->type();
1125   else if (this->function_->is_function_declaration())
1126     return this->function_->func_declaration_value()->type();
1127   else
1128     gcc_unreachable();
1129 }
1130
1131 // Get the tree for a function expression without evaluating the
1132 // closure.
1133
1134 tree
1135 Func_expression::get_tree_without_closure(Gogo* gogo)
1136 {
1137   Function_type* fntype;
1138   if (this->function_->is_function())
1139     fntype = this->function_->func_value()->type();
1140   else if (this->function_->is_function_declaration())
1141     fntype = this->function_->func_declaration_value()->type();
1142   else
1143     gcc_unreachable();
1144
1145   // Builtin functions are handled specially by Call_expression.  We
1146   // can't take their address.
1147   if (fntype->is_builtin())
1148     {
1149       error_at(this->location(), "invalid use of special builtin function %qs",
1150                this->function_->name().c_str());
1151       return error_mark_node;
1152     }
1153
1154   Named_object* no = this->function_;
1155
1156   tree id = no->get_id(gogo);
1157   if (id == error_mark_node)
1158     return error_mark_node;
1159
1160   tree fndecl;
1161   if (no->is_function())
1162     fndecl = no->func_value()->get_or_make_decl(gogo, no, id);
1163   else if (no->is_function_declaration())
1164     fndecl = no->func_declaration_value()->get_or_make_decl(gogo, no, id);
1165   else
1166     gcc_unreachable();
1167
1168   if (fndecl == error_mark_node)
1169     return error_mark_node;
1170
1171   return build_fold_addr_expr_loc(this->location(), fndecl);
1172 }
1173
1174 // Get the tree for a function expression.  This is used when we take
1175 // the address of a function rather than simply calling it.  If the
1176 // function has a closure, we must use a trampoline.
1177
1178 tree
1179 Func_expression::do_get_tree(Translate_context* context)
1180 {
1181   Gogo* gogo = context->gogo();
1182
1183   tree fnaddr = this->get_tree_without_closure(gogo);
1184   if (fnaddr == error_mark_node)
1185     return error_mark_node;
1186
1187   gcc_assert(TREE_CODE(fnaddr) == ADDR_EXPR
1188              && TREE_CODE(TREE_OPERAND(fnaddr, 0)) == FUNCTION_DECL);
1189   TREE_ADDRESSABLE(TREE_OPERAND(fnaddr, 0)) = 1;
1190
1191   // For a normal non-nested function call, that is all we have to do.
1192   if (!this->function_->is_function()
1193       || this->function_->func_value()->enclosing() == NULL)
1194     {
1195       gcc_assert(this->closure_ == NULL);
1196       return fnaddr;
1197     }
1198
1199   // For a nested function call, we have to always allocate a
1200   // trampoline.  If we don't always allocate, then closures will not
1201   // be reliably distinct.
1202   Expression* closure = this->closure_;
1203   tree closure_tree;
1204   if (closure == NULL)
1205     closure_tree = null_pointer_node;
1206   else
1207     {
1208       // Get the value of the closure.  This will be a pointer to
1209       // space allocated on the heap.
1210       closure_tree = closure->get_tree(context);
1211       if (closure_tree == error_mark_node)
1212         return error_mark_node;
1213       gcc_assert(POINTER_TYPE_P(TREE_TYPE(closure_tree)));
1214     }
1215
1216   // Now we need to build some code on the heap.  This code will load
1217   // the static chain pointer with the closure and then jump to the
1218   // body of the function.  The normal gcc approach is to build the
1219   // code on the stack.  Unfortunately we can not do that, as Go
1220   // permits us to return the function pointer.
1221
1222   return gogo->make_trampoline(fnaddr, closure_tree, this->location());
1223 }
1224
1225 // Make a reference to a function in an expression.
1226
1227 Expression*
1228 Expression::make_func_reference(Named_object* function, Expression* closure,
1229                                 source_location location)
1230 {
1231   return new Func_expression(function, closure, location);
1232 }
1233
1234 // Class Unknown_expression.
1235
1236 // Return the name of an unknown expression.
1237
1238 const std::string&
1239 Unknown_expression::name() const
1240 {
1241   return this->named_object_->name();
1242 }
1243
1244 // Lower a reference to an unknown name.
1245
1246 Expression*
1247 Unknown_expression::do_lower(Gogo*, Named_object*, int)
1248 {
1249   source_location location = this->location();
1250   Named_object* no = this->named_object_;
1251   Named_object* real = no->unknown_value()->real_named_object();
1252   if (real == NULL)
1253     {
1254       if (this->is_composite_literal_key_)
1255         return this;
1256       error_at(location, "reference to undefined name %qs",
1257                this->named_object_->message_name().c_str());
1258       return Expression::make_error(location);
1259     }
1260   switch (real->classification())
1261     {
1262     case Named_object::NAMED_OBJECT_CONST:
1263       return Expression::make_const_reference(real, location);
1264     case Named_object::NAMED_OBJECT_TYPE:
1265       return Expression::make_type(real->type_value(), location);
1266     case Named_object::NAMED_OBJECT_TYPE_DECLARATION:
1267       if (this->is_composite_literal_key_)
1268         return this;
1269       error_at(location, "reference to undefined type %qs",
1270                real->message_name().c_str());
1271       return Expression::make_error(location);
1272     case Named_object::NAMED_OBJECT_VAR:
1273       return Expression::make_var_reference(real, location);
1274     case Named_object::NAMED_OBJECT_FUNC:
1275     case Named_object::NAMED_OBJECT_FUNC_DECLARATION:
1276       return Expression::make_func_reference(real, NULL, location);
1277     case Named_object::NAMED_OBJECT_PACKAGE:
1278       if (this->is_composite_literal_key_)
1279         return this;
1280       error_at(location, "unexpected reference to package");
1281       return Expression::make_error(location);
1282     default:
1283       gcc_unreachable();
1284     }
1285 }
1286
1287 // Make a reference to an unknown name.
1288
1289 Expression*
1290 Expression::make_unknown_reference(Named_object* no, source_location location)
1291 {
1292   gcc_assert(no->resolve()->is_unknown());
1293   return new Unknown_expression(no, location);
1294 }
1295
1296 // A boolean expression.
1297
1298 class Boolean_expression : public Expression
1299 {
1300  public:
1301   Boolean_expression(bool val, source_location location)
1302     : Expression(EXPRESSION_BOOLEAN, location),
1303       val_(val), type_(NULL)
1304   { }
1305
1306   static Expression*
1307   do_import(Import*);
1308
1309  protected:
1310   bool
1311   do_is_constant() const
1312   { return true; }
1313
1314   Type*
1315   do_type();
1316
1317   void
1318   do_determine_type(const Type_context*);
1319
1320   Expression*
1321   do_copy()
1322   { return this; }
1323
1324   tree
1325   do_get_tree(Translate_context*)
1326   { return this->val_ ? boolean_true_node : boolean_false_node; }
1327
1328   void
1329   do_export(Export* exp) const
1330   { exp->write_c_string(this->val_ ? "true" : "false"); }
1331
1332  private:
1333   // The constant.
1334   bool val_;
1335   // The type as determined by context.
1336   Type* type_;
1337 };
1338
1339 // Get the type.
1340
1341 Type*
1342 Boolean_expression::do_type()
1343 {
1344   if (this->type_ == NULL)
1345     this->type_ = Type::make_boolean_type();
1346   return this->type_;
1347 }
1348
1349 // Set the type from the context.
1350
1351 void
1352 Boolean_expression::do_determine_type(const Type_context* context)
1353 {
1354   if (this->type_ != NULL && !this->type_->is_abstract())
1355     ;
1356   else if (context->type != NULL && context->type->is_boolean_type())
1357     this->type_ = context->type;
1358   else if (!context->may_be_abstract)
1359     this->type_ = Type::lookup_bool_type();
1360 }
1361
1362 // Import a boolean constant.
1363
1364 Expression*
1365 Boolean_expression::do_import(Import* imp)
1366 {
1367   if (imp->peek_char() == 't')
1368     {
1369       imp->require_c_string("true");
1370       return Expression::make_boolean(true, imp->location());
1371     }
1372   else
1373     {
1374       imp->require_c_string("false");
1375       return Expression::make_boolean(false, imp->location());
1376     }
1377 }
1378
1379 // Make a boolean expression.
1380
1381 Expression*
1382 Expression::make_boolean(bool val, source_location location)
1383 {
1384   return new Boolean_expression(val, location);
1385 }
1386
1387 // Class String_expression.
1388
1389 // Get the type.
1390
1391 Type*
1392 String_expression::do_type()
1393 {
1394   if (this->type_ == NULL)
1395     this->type_ = Type::make_string_type();
1396   return this->type_;
1397 }
1398
1399 // Set the type from the context.
1400
1401 void
1402 String_expression::do_determine_type(const Type_context* context)
1403 {
1404   if (this->type_ != NULL && !this->type_->is_abstract())
1405     ;
1406   else if (context->type != NULL && context->type->is_string_type())
1407     this->type_ = context->type;
1408   else if (!context->may_be_abstract)
1409     this->type_ = Type::lookup_string_type();
1410 }
1411
1412 // Build a string constant.
1413
1414 tree
1415 String_expression::do_get_tree(Translate_context* context)
1416 {
1417   return context->gogo()->go_string_constant_tree(this->val_);
1418 }
1419
1420 // Export a string expression.
1421
1422 void
1423 String_expression::do_export(Export* exp) const
1424 {
1425   std::string s;
1426   s.reserve(this->val_.length() * 4 + 2);
1427   s += '"';
1428   for (std::string::const_iterator p = this->val_.begin();
1429        p != this->val_.end();
1430        ++p)
1431     {
1432       if (*p == '\\' || *p == '"')
1433         {
1434           s += '\\';
1435           s += *p;
1436         }
1437       else if (*p >= 0x20 && *p < 0x7f)
1438         s += *p;
1439       else if (*p == '\n')
1440         s += "\\n";
1441       else if (*p == '\t')
1442         s += "\\t";
1443       else
1444         {
1445           s += "\\x";
1446           unsigned char c = *p;
1447           unsigned int dig = c >> 4;
1448           s += dig < 10 ? '0' + dig : 'A' + dig - 10;
1449           dig = c & 0xf;
1450           s += dig < 10 ? '0' + dig : 'A' + dig - 10;
1451         }
1452     }
1453   s += '"';
1454   exp->write_string(s);
1455 }
1456
1457 // Import a string expression.
1458
1459 Expression*
1460 String_expression::do_import(Import* imp)
1461 {
1462   imp->require_c_string("\"");
1463   std::string val;
1464   while (true)
1465     {
1466       int c = imp->get_char();
1467       if (c == '"' || c == -1)
1468         break;
1469       if (c != '\\')
1470         val += static_cast<char>(c);
1471       else
1472         {
1473           c = imp->get_char();
1474           if (c == '\\' || c == '"')
1475             val += static_cast<char>(c);
1476           else if (c == 'n')
1477             val += '\n';
1478           else if (c == 't')
1479             val += '\t';
1480           else if (c == 'x')
1481             {
1482               c = imp->get_char();
1483               unsigned int vh = c >= '0' && c <= '9' ? c - '0' : c - 'A' + 10;
1484               c = imp->get_char();
1485               unsigned int vl = c >= '0' && c <= '9' ? c - '0' : c - 'A' + 10;
1486               char v = (vh << 4) | vl;
1487               val += v;
1488             }
1489           else
1490             {
1491               error_at(imp->location(), "bad string constant");
1492               return Expression::make_error(imp->location());
1493             }
1494         }
1495     }
1496   return Expression::make_string(val, imp->location());
1497 }
1498
1499 // Make a string expression.
1500
1501 Expression*
1502 Expression::make_string(const std::string& val, source_location location)
1503 {
1504   return new String_expression(val, location);
1505 }
1506
1507 // Make an integer expression.
1508
1509 class Integer_expression : public Expression
1510 {
1511  public:
1512   Integer_expression(const mpz_t* val, Type* type, source_location location)
1513     : Expression(EXPRESSION_INTEGER, location),
1514       type_(type)
1515   { mpz_init_set(this->val_, *val); }
1516
1517   static Expression*
1518   do_import(Import*);
1519
1520   // Return whether VAL fits in the type.
1521   static bool
1522   check_constant(mpz_t val, Type*, source_location);
1523
1524   // Write VAL to export data.
1525   static void
1526   export_integer(Export* exp, const mpz_t val);
1527
1528  protected:
1529   bool
1530   do_is_constant() const
1531   { return true; }
1532
1533   bool
1534   do_integer_constant_value(bool, mpz_t val, Type** ptype) const;
1535
1536   Type*
1537   do_type();
1538
1539   void
1540   do_determine_type(const Type_context* context);
1541
1542   void
1543   do_check_types(Gogo*);
1544
1545   tree
1546   do_get_tree(Translate_context*);
1547
1548   Expression*
1549   do_copy()
1550   { return Expression::make_integer(&this->val_, this->type_,
1551                                     this->location()); }
1552
1553   void
1554   do_export(Export*) const;
1555
1556  private:
1557   // The integer value.
1558   mpz_t val_;
1559   // The type so far.
1560   Type* type_;
1561 };
1562
1563 // Return an integer constant value.
1564
1565 bool
1566 Integer_expression::do_integer_constant_value(bool, mpz_t val,
1567                                               Type** ptype) const
1568 {
1569   if (this->type_ != NULL)
1570     *ptype = this->type_;
1571   mpz_set(val, this->val_);
1572   return true;
1573 }
1574
1575 // Return the current type.  If we haven't set the type yet, we return
1576 // an abstract integer type.
1577
1578 Type*
1579 Integer_expression::do_type()
1580 {
1581   if (this->type_ == NULL)
1582     this->type_ = Type::make_abstract_integer_type();
1583   return this->type_;
1584 }
1585
1586 // Set the type of the integer value.  Here we may switch from an
1587 // abstract type to a real type.
1588
1589 void
1590 Integer_expression::do_determine_type(const Type_context* context)
1591 {
1592   if (this->type_ != NULL && !this->type_->is_abstract())
1593     ;
1594   else if (context->type != NULL
1595            && (context->type->integer_type() != NULL
1596                || context->type->float_type() != NULL
1597                || context->type->complex_type() != NULL))
1598     this->type_ = context->type;
1599   else if (!context->may_be_abstract)
1600     this->type_ = Type::lookup_integer_type("int");
1601 }
1602
1603 // Return true if the integer VAL fits in the range of the type TYPE.
1604 // Otherwise give an error and return false.  TYPE may be NULL.
1605
1606 bool
1607 Integer_expression::check_constant(mpz_t val, Type* type,
1608                                    source_location location)
1609 {
1610   if (type == NULL)
1611     return true;
1612   Integer_type* itype = type->integer_type();
1613   if (itype == NULL || itype->is_abstract())
1614     return true;
1615
1616   int bits = mpz_sizeinbase(val, 2);
1617
1618   if (itype->is_unsigned())
1619     {
1620       // For an unsigned type we can only accept a nonnegative number,
1621       // and we must be able to represent at least BITS.
1622       if (mpz_sgn(val) >= 0
1623           && bits <= itype->bits())
1624         return true;
1625     }
1626   else
1627     {
1628       // For a signed type we need an extra bit to indicate the sign.
1629       // We have to handle the most negative integer specially.
1630       if (bits + 1 <= itype->bits()
1631           || (bits <= itype->bits()
1632               && mpz_sgn(val) < 0
1633               && (mpz_scan1(val, 0)
1634                   == static_cast<unsigned long>(itype->bits() - 1))
1635               && mpz_scan0(val, itype->bits()) == ULONG_MAX))
1636         return true;
1637     }
1638
1639   error_at(location, "integer constant overflow");
1640   return false;
1641 }
1642
1643 // Check the type of an integer constant.
1644
1645 void
1646 Integer_expression::do_check_types(Gogo*)
1647 {
1648   if (this->type_ == NULL)
1649     return;
1650   if (!Integer_expression::check_constant(this->val_, this->type_,
1651                                           this->location()))
1652     this->set_is_error();
1653 }
1654
1655 // Get a tree for an integer constant.
1656
1657 tree
1658 Integer_expression::do_get_tree(Translate_context* context)
1659 {
1660   Gogo* gogo = context->gogo();
1661   tree type;
1662   if (this->type_ != NULL && !this->type_->is_abstract())
1663     type = this->type_->get_tree(gogo);
1664   else if (this->type_ != NULL && this->type_->float_type() != NULL)
1665     {
1666       // We are converting to an abstract floating point type.
1667       type = Type::lookup_float_type("float64")->get_tree(gogo);
1668     }
1669   else if (this->type_ != NULL && this->type_->complex_type() != NULL)
1670     {
1671       // We are converting to an abstract complex type.
1672       type = Type::lookup_complex_type("complex128")->get_tree(gogo);
1673     }
1674   else
1675     {
1676       // If we still have an abstract type here, then this is being
1677       // used in a constant expression which didn't get reduced for
1678       // some reason.  Use a type which will fit the value.  We use <,
1679       // not <=, because we need an extra bit for the sign bit.
1680       int bits = mpz_sizeinbase(this->val_, 2);
1681       if (bits < INT_TYPE_SIZE)
1682         type = Type::lookup_integer_type("int")->get_tree(gogo);
1683       else if (bits < 64)
1684         type = Type::lookup_integer_type("int64")->get_tree(gogo);
1685       else
1686         type = long_long_integer_type_node;
1687     }
1688   return Expression::integer_constant_tree(this->val_, type);
1689 }
1690
1691 // Write VAL to export data.
1692
1693 void
1694 Integer_expression::export_integer(Export* exp, const mpz_t val)
1695 {
1696   char* s = mpz_get_str(NULL, 10, val);
1697   exp->write_c_string(s);
1698   free(s);
1699 }
1700
1701 // Export an integer in a constant expression.
1702
1703 void
1704 Integer_expression::do_export(Export* exp) const
1705 {
1706   Integer_expression::export_integer(exp, this->val_);
1707   // A trailing space lets us reliably identify the end of the number.
1708   exp->write_c_string(" ");
1709 }
1710
1711 // Import an integer, floating point, or complex value.  This handles
1712 // all these types because they all start with digits.
1713
1714 Expression*
1715 Integer_expression::do_import(Import* imp)
1716 {
1717   std::string num = imp->read_identifier();
1718   imp->require_c_string(" ");
1719   if (!num.empty() && num[num.length() - 1] == 'i')
1720     {
1721       mpfr_t real;
1722       size_t plus_pos = num.find('+', 1);
1723       size_t minus_pos = num.find('-', 1);
1724       size_t pos;
1725       if (plus_pos == std::string::npos)
1726         pos = minus_pos;
1727       else if (minus_pos == std::string::npos)
1728         pos = plus_pos;
1729       else
1730         {
1731           error_at(imp->location(), "bad number in import data: %qs",
1732                    num.c_str());
1733           return Expression::make_error(imp->location());
1734         }
1735       if (pos == std::string::npos)
1736         mpfr_set_ui(real, 0, GMP_RNDN);
1737       else
1738         {
1739           std::string real_str = num.substr(0, pos);
1740           if (mpfr_init_set_str(real, real_str.c_str(), 10, GMP_RNDN) != 0)
1741             {
1742               error_at(imp->location(), "bad number in import data: %qs",
1743                        real_str.c_str());
1744               return Expression::make_error(imp->location());
1745             }
1746         }
1747
1748       std::string imag_str;
1749       if (pos == std::string::npos)
1750         imag_str = num;
1751       else
1752         imag_str = num.substr(pos);
1753       imag_str = imag_str.substr(0, imag_str.size() - 1);
1754       mpfr_t imag;
1755       if (mpfr_init_set_str(imag, imag_str.c_str(), 10, GMP_RNDN) != 0)
1756         {
1757           error_at(imp->location(), "bad number in import data: %qs",
1758                    imag_str.c_str());
1759           return Expression::make_error(imp->location());
1760         }
1761       Expression* ret = Expression::make_complex(&real, &imag, NULL,
1762                                                  imp->location());
1763       mpfr_clear(real);
1764       mpfr_clear(imag);
1765       return ret;
1766     }
1767   else if (num.find('.') == std::string::npos
1768            && num.find('E') == std::string::npos)
1769     {
1770       mpz_t val;
1771       if (mpz_init_set_str(val, num.c_str(), 10) != 0)
1772         {
1773           error_at(imp->location(), "bad number in import data: %qs",
1774                    num.c_str());
1775           return Expression::make_error(imp->location());
1776         }
1777       Expression* ret = Expression::make_integer(&val, NULL, imp->location());
1778       mpz_clear(val);
1779       return ret;
1780     }
1781   else
1782     {
1783       mpfr_t val;
1784       if (mpfr_init_set_str(val, num.c_str(), 10, GMP_RNDN) != 0)
1785         {
1786           error_at(imp->location(), "bad number in import data: %qs",
1787                    num.c_str());
1788           return Expression::make_error(imp->location());
1789         }
1790       Expression* ret = Expression::make_float(&val, NULL, imp->location());
1791       mpfr_clear(val);
1792       return ret;
1793     }
1794 }
1795
1796 // Build a new integer value.
1797
1798 Expression*
1799 Expression::make_integer(const mpz_t* val, Type* type,
1800                          source_location location)
1801 {
1802   return new Integer_expression(val, type, location);
1803 }
1804
1805 // Floats.
1806
1807 class Float_expression : public Expression
1808 {
1809  public:
1810   Float_expression(const mpfr_t* val, Type* type, source_location location)
1811     : Expression(EXPRESSION_FLOAT, location),
1812       type_(type)
1813   {
1814     mpfr_init_set(this->val_, *val, GMP_RNDN);
1815   }
1816
1817   // Constrain VAL to fit into TYPE.
1818   static void
1819   constrain_float(mpfr_t val, Type* type);
1820
1821   // Return whether VAL fits in the type.
1822   static bool
1823   check_constant(mpfr_t val, Type*, source_location);
1824
1825   // Write VAL to export data.
1826   static void
1827   export_float(Export* exp, const mpfr_t val);
1828
1829  protected:
1830   bool
1831   do_is_constant() const
1832   { return true; }
1833
1834   bool
1835   do_float_constant_value(mpfr_t val, Type**) const;
1836
1837   Type*
1838   do_type();
1839
1840   void
1841   do_determine_type(const Type_context*);
1842
1843   void
1844   do_check_types(Gogo*);
1845
1846   Expression*
1847   do_copy()
1848   { return Expression::make_float(&this->val_, this->type_,
1849                                   this->location()); }
1850
1851   tree
1852   do_get_tree(Translate_context*);
1853
1854   void
1855   do_export(Export*) const;
1856
1857  private:
1858   // The floating point value.
1859   mpfr_t val_;
1860   // The type so far.
1861   Type* type_;
1862 };
1863
1864 // Constrain VAL to fit into TYPE.
1865
1866 void
1867 Float_expression::constrain_float(mpfr_t val, Type* type)
1868 {
1869   Float_type* ftype = type->float_type();
1870   if (ftype != NULL && !ftype->is_abstract())
1871     {
1872       tree type_tree = ftype->type_tree();
1873       REAL_VALUE_TYPE rvt;
1874       real_from_mpfr(&rvt, val, type_tree, GMP_RNDN);
1875       real_convert(&rvt, TYPE_MODE(type_tree), &rvt);
1876       mpfr_from_real(val, &rvt, GMP_RNDN);
1877     }
1878 }
1879
1880 // Return a floating point constant value.
1881
1882 bool
1883 Float_expression::do_float_constant_value(mpfr_t val, Type** ptype) const
1884 {
1885   if (this->type_ != NULL)
1886     *ptype = this->type_;
1887   mpfr_set(val, this->val_, GMP_RNDN);
1888   return true;
1889 }
1890
1891 // Return the current type.  If we haven't set the type yet, we return
1892 // an abstract float type.
1893
1894 Type*
1895 Float_expression::do_type()
1896 {
1897   if (this->type_ == NULL)
1898     this->type_ = Type::make_abstract_float_type();
1899   return this->type_;
1900 }
1901
1902 // Set the type of the float value.  Here we may switch from an
1903 // abstract type to a real type.
1904
1905 void
1906 Float_expression::do_determine_type(const Type_context* context)
1907 {
1908   if (this->type_ != NULL && !this->type_->is_abstract())
1909     ;
1910   else if (context->type != NULL
1911            && (context->type->integer_type() != NULL
1912                || context->type->float_type() != NULL
1913                || context->type->complex_type() != NULL))
1914     this->type_ = context->type;
1915   else if (!context->may_be_abstract)
1916     this->type_ = Type::lookup_float_type("float");
1917 }
1918
1919 // Return true if the floating point value VAL fits in the range of
1920 // the type TYPE.  Otherwise give an error and return false.  TYPE may
1921 // be NULL.
1922
1923 bool
1924 Float_expression::check_constant(mpfr_t val, Type* type,
1925                                  source_location location)
1926 {
1927   if (type == NULL)
1928     return true;
1929   Float_type* ftype = type->float_type();
1930   if (ftype == NULL || ftype->is_abstract())
1931     return true;
1932
1933   // A NaN or Infinity always fits in the range of the type.
1934   if (mpfr_nan_p(val) || mpfr_inf_p(val) || mpfr_zero_p(val))
1935     return true;
1936
1937   mp_exp_t exp = mpfr_get_exp(val);
1938   mp_exp_t max_exp;
1939   switch (ftype->bits())
1940     {
1941     case 32:
1942       max_exp = 128;
1943       break;
1944     case 64:
1945       max_exp = 1024;
1946       break;
1947     default:
1948       gcc_unreachable();
1949     }
1950   if (exp > max_exp)
1951     {
1952       error_at(location, "floating point constant overflow");
1953       return false;
1954     }
1955   return true;
1956 }
1957
1958 // Check the type of a float value.
1959
1960 void
1961 Float_expression::do_check_types(Gogo*)
1962 {
1963   if (this->type_ == NULL)
1964     return;
1965
1966   if (!Float_expression::check_constant(this->val_, this->type_,
1967                                         this->location()))
1968     this->set_is_error();
1969
1970   Integer_type* integer_type = this->type_->integer_type();
1971   if (integer_type != NULL)
1972     {
1973       if (!mpfr_integer_p(this->val_))
1974         this->report_error(_("floating point constant truncated to integer"));
1975       else
1976         {
1977           gcc_assert(!integer_type->is_abstract());
1978           mpz_t ival;
1979           mpz_init(ival);
1980           mpfr_get_z(ival, this->val_, GMP_RNDN);
1981           Integer_expression::check_constant(ival, integer_type,
1982                                              this->location());
1983           mpz_clear(ival);
1984         }
1985     }
1986 }
1987
1988 // Get a tree for a float constant.
1989
1990 tree
1991 Float_expression::do_get_tree(Translate_context* context)
1992 {
1993   Gogo* gogo = context->gogo();
1994   tree type;
1995   if (this->type_ != NULL && !this->type_->is_abstract())
1996     type = this->type_->get_tree(gogo);
1997   else if (this->type_ != NULL && this->type_->integer_type() != NULL)
1998     {
1999       // We have an abstract integer type.  We just hope for the best.
2000       type = Type::lookup_integer_type("int")->get_tree(gogo);
2001     }
2002   else
2003     {
2004       // If we still have an abstract type here, then this is being
2005       // used in a constant expression which didn't get reduced.  We
2006       // just use float64 and hope for the best.
2007       type = Type::lookup_float_type("float64")->get_tree(gogo);
2008     }
2009   return Expression::float_constant_tree(this->val_, type);
2010 }
2011
2012 // Write a floating point number to export data.
2013
2014 void
2015 Float_expression::export_float(Export *exp, const mpfr_t val)
2016 {
2017   mp_exp_t exponent;
2018   char* s = mpfr_get_str(NULL, &exponent, 10, 0, val, GMP_RNDN);
2019   if (*s == '-')
2020     exp->write_c_string("-");
2021   exp->write_c_string("0.");
2022   exp->write_c_string(*s == '-' ? s + 1 : s);
2023   mpfr_free_str(s);
2024   char buf[30];
2025   snprintf(buf, sizeof buf, "E%ld", exponent);
2026   exp->write_c_string(buf);
2027 }
2028
2029 // Export a floating point number in a constant expression.
2030
2031 void
2032 Float_expression::do_export(Export* exp) const
2033 {
2034   Float_expression::export_float(exp, this->val_);
2035   // A trailing space lets us reliably identify the end of the number.
2036   exp->write_c_string(" ");
2037 }
2038
2039 // Make a float expression.
2040
2041 Expression*
2042 Expression::make_float(const mpfr_t* val, Type* type, source_location location)
2043 {
2044   return new Float_expression(val, type, location);
2045 }
2046
2047 // Complex numbers.
2048
2049 class Complex_expression : public Expression
2050 {
2051  public:
2052   Complex_expression(const mpfr_t* real, const mpfr_t* imag, Type* type,
2053                      source_location location)
2054     : Expression(EXPRESSION_COMPLEX, location),
2055       type_(type)
2056   {
2057     mpfr_init_set(this->real_, *real, GMP_RNDN);
2058     mpfr_init_set(this->imag_, *imag, GMP_RNDN);
2059   }
2060
2061   // Constrain REAL/IMAG to fit into TYPE.
2062   static void
2063   constrain_complex(mpfr_t real, mpfr_t imag, Type* type);
2064
2065   // Return whether REAL/IMAG fits in the type.
2066   static bool
2067   check_constant(mpfr_t real, mpfr_t imag, Type*, source_location);
2068
2069   // Write REAL/IMAG to export data.
2070   static void
2071   export_complex(Export* exp, const mpfr_t real, const mpfr_t val);
2072
2073  protected:
2074   bool
2075   do_is_constant() const
2076   { return true; }
2077
2078   bool
2079   do_complex_constant_value(mpfr_t real, mpfr_t imag, Type**) const;
2080
2081   Type*
2082   do_type();
2083
2084   void
2085   do_determine_type(const Type_context*);
2086
2087   void
2088   do_check_types(Gogo*);
2089
2090   Expression*
2091   do_copy()
2092   {
2093     return Expression::make_complex(&this->real_, &this->imag_, this->type_,
2094                                     this->location());
2095   }
2096
2097   tree
2098   do_get_tree(Translate_context*);
2099
2100   void
2101   do_export(Export*) const;
2102
2103  private:
2104   // The real part.
2105   mpfr_t real_;
2106   // The imaginary part;
2107   mpfr_t imag_;
2108   // The type if known.
2109   Type* type_;
2110 };
2111
2112 // Constrain REAL/IMAG to fit into TYPE.
2113
2114 void
2115 Complex_expression::constrain_complex(mpfr_t real, mpfr_t imag, Type* type)
2116 {
2117   Complex_type* ctype = type->complex_type();
2118   if (ctype != NULL && !ctype->is_abstract())
2119     {
2120       tree type_tree = ctype->type_tree();
2121
2122       REAL_VALUE_TYPE rvt;
2123       real_from_mpfr(&rvt, real, TREE_TYPE(type_tree), GMP_RNDN);
2124       real_convert(&rvt, TYPE_MODE(TREE_TYPE(type_tree)), &rvt);
2125       mpfr_from_real(real, &rvt, GMP_RNDN);
2126
2127       real_from_mpfr(&rvt, imag, TREE_TYPE(type_tree), GMP_RNDN);
2128       real_convert(&rvt, TYPE_MODE(TREE_TYPE(type_tree)), &rvt);
2129       mpfr_from_real(imag, &rvt, GMP_RNDN);
2130     }
2131 }
2132
2133 // Return a complex constant value.
2134
2135 bool
2136 Complex_expression::do_complex_constant_value(mpfr_t real, mpfr_t imag,
2137                                               Type** ptype) const
2138 {
2139   if (this->type_ != NULL)
2140     *ptype = this->type_;
2141   mpfr_set(real, this->real_, GMP_RNDN);
2142   mpfr_set(imag, this->imag_, GMP_RNDN);
2143   return true;
2144 }
2145
2146 // Return the current type.  If we haven't set the type yet, we return
2147 // an abstract complex type.
2148
2149 Type*
2150 Complex_expression::do_type()
2151 {
2152   if (this->type_ == NULL)
2153     this->type_ = Type::make_abstract_complex_type();
2154   return this->type_;
2155 }
2156
2157 // Set the type of the complex value.  Here we may switch from an
2158 // abstract type to a real type.
2159
2160 void
2161 Complex_expression::do_determine_type(const Type_context* context)
2162 {
2163   if (this->type_ != NULL && !this->type_->is_abstract())
2164     ;
2165   else if (context->type != NULL
2166            && context->type->complex_type() != NULL)
2167     this->type_ = context->type;
2168   else if (!context->may_be_abstract)
2169     this->type_ = Type::lookup_complex_type("complex");
2170 }
2171
2172 // Return true if the complex value REAL/IMAG fits in the range of the
2173 // type TYPE.  Otherwise give an error and return false.  TYPE may be
2174 // NULL.
2175
2176 bool
2177 Complex_expression::check_constant(mpfr_t real, mpfr_t imag, Type* type,
2178                                    source_location location)
2179 {
2180   if (type == NULL)
2181     return true;
2182   Complex_type* ctype = type->complex_type();
2183   if (ctype == NULL || ctype->is_abstract())
2184     return true;
2185
2186   mp_exp_t max_exp;
2187   switch (ctype->bits())
2188     {
2189     case 64:
2190       max_exp = 128;
2191       break;
2192     case 128:
2193       max_exp = 1024;
2194       break;
2195     default:
2196       gcc_unreachable();
2197     }
2198
2199   // A NaN or Infinity always fits in the range of the type.
2200   if (!mpfr_nan_p(real) && !mpfr_inf_p(real) && !mpfr_zero_p(real))
2201     {
2202       if (mpfr_get_exp(real) > max_exp)
2203         {
2204           error_at(location, "complex real part constant overflow");
2205           return false;
2206         }
2207     }
2208
2209   if (!mpfr_nan_p(imag) && !mpfr_inf_p(imag) && !mpfr_zero_p(imag))
2210     {
2211       if (mpfr_get_exp(imag) > max_exp)
2212         {
2213           error_at(location, "complex imaginary part constant overflow");
2214           return false;
2215         }
2216     }
2217
2218   return true;
2219 }
2220
2221 // Check the type of a complex value.
2222
2223 void
2224 Complex_expression::do_check_types(Gogo*)
2225 {
2226   if (this->type_ == NULL)
2227     return;
2228
2229   if (!Complex_expression::check_constant(this->real_, this->imag_,
2230                                           this->type_, this->location()))
2231     this->set_is_error();
2232 }
2233
2234 // Get a tree for a complex constant.
2235
2236 tree
2237 Complex_expression::do_get_tree(Translate_context* context)
2238 {
2239   Gogo* gogo = context->gogo();
2240   tree type;
2241   if (this->type_ != NULL && !this->type_->is_abstract())
2242     type = this->type_->get_tree(gogo);
2243   else
2244     {
2245       // If we still have an abstract type here, this this is being
2246       // used in a constant expression which didn't get reduced.  We
2247       // just use complex128 and hope for the best.
2248       type = Type::lookup_complex_type("complex128")->get_tree(gogo);
2249     }
2250   return Expression::complex_constant_tree(this->real_, this->imag_, type);
2251 }
2252
2253 // Write REAL/IMAG to export data.
2254
2255 void
2256 Complex_expression::export_complex(Export* exp, const mpfr_t real,
2257                                    const mpfr_t imag)
2258 {
2259   if (!mpfr_zero_p(real))
2260     {
2261       Float_expression::export_float(exp, real);
2262       if (mpfr_sgn(imag) > 0)
2263         exp->write_c_string("+");
2264     }
2265   Float_expression::export_float(exp, imag);
2266   exp->write_c_string("i");
2267 }
2268
2269 // Export a complex number in a constant expression.
2270
2271 void
2272 Complex_expression::do_export(Export* exp) const
2273 {
2274   Complex_expression::export_complex(exp, this->real_, this->imag_);
2275   // A trailing space lets us reliably identify the end of the number.
2276   exp->write_c_string(" ");
2277 }
2278
2279 // Make a complex expression.
2280
2281 Expression*
2282 Expression::make_complex(const mpfr_t* real, const mpfr_t* imag, Type* type,
2283                          source_location location)
2284 {
2285   return new Complex_expression(real, imag, type, location);
2286 }
2287
2288 // A reference to a const in an expression.
2289
2290 class Const_expression : public Expression
2291 {
2292  public:
2293   Const_expression(Named_object* constant, source_location location)
2294     : Expression(EXPRESSION_CONST_REFERENCE, location),
2295       constant_(constant), type_(NULL)
2296   { }
2297
2298   const std::string&
2299   name() const
2300   { return this->constant_->name(); }
2301
2302  protected:
2303   Expression*
2304   do_lower(Gogo*, Named_object*, int);
2305
2306   bool
2307   do_is_constant() const
2308   { return true; }
2309
2310   bool
2311   do_integer_constant_value(bool, mpz_t val, Type**) const;
2312
2313   bool
2314   do_float_constant_value(mpfr_t val, Type**) const;
2315
2316   bool
2317   do_complex_constant_value(mpfr_t real, mpfr_t imag, Type**) const;
2318
2319   bool
2320   do_string_constant_value(std::string* val) const
2321   { return this->constant_->const_value()->expr()->string_constant_value(val); }
2322
2323   Type*
2324   do_type();
2325
2326   // The type of a const is set by the declaration, not the use.
2327   void
2328   do_determine_type(const Type_context*);
2329
2330   void
2331   do_check_types(Gogo*);
2332
2333   Expression*
2334   do_copy()
2335   { return this; }
2336
2337   tree
2338   do_get_tree(Translate_context* context);
2339
2340   // When exporting a reference to a const as part of a const
2341   // expression, we export the value.  We ignore the fact that it has
2342   // a name.
2343   void
2344   do_export(Export* exp) const
2345   { this->constant_->const_value()->expr()->export_expression(exp); }
2346
2347  private:
2348   // The constant.
2349   Named_object* constant_;
2350   // The type of this reference.  This is used if the constant has an
2351   // abstract type.
2352   Type* type_;
2353 };
2354
2355 // Lower a constant expression.  This is where we convert the
2356 // predeclared constant iota into an integer value.
2357
2358 Expression*
2359 Const_expression::do_lower(Gogo* gogo, Named_object*, int iota_value)
2360 {
2361   if (this->constant_->const_value()->expr()->classification()
2362       == EXPRESSION_IOTA)
2363     {
2364       if (iota_value == -1)
2365         {
2366           error_at(this->location(),
2367                    "iota is only defined in const declarations");
2368           iota_value = 0;
2369         }
2370       mpz_t val;
2371       mpz_init_set_ui(val, static_cast<unsigned long>(iota_value));
2372       Expression* ret = Expression::make_integer(&val, NULL,
2373                                                  this->location());
2374       mpz_clear(val);
2375       return ret;
2376     }
2377
2378   // Make sure that the constant itself has been lowered.
2379   gogo->lower_constant(this->constant_);
2380
2381   return this;
2382 }
2383
2384 // Return an integer constant value.
2385
2386 bool
2387 Const_expression::do_integer_constant_value(bool iota_is_constant, mpz_t val,
2388                                             Type** ptype) const
2389 {
2390   Type* ctype;
2391   if (this->type_ != NULL)
2392     ctype = this->type_;
2393   else
2394     ctype = this->constant_->const_value()->type();
2395   if (ctype != NULL && ctype->integer_type() == NULL)
2396     return false;
2397
2398   Expression* e = this->constant_->const_value()->expr();
2399   Type* t;
2400   bool r = e->integer_constant_value(iota_is_constant, val, &t);
2401
2402   if (r
2403       && ctype != NULL
2404       && !Integer_expression::check_constant(val, ctype, this->location()))
2405     return false;
2406
2407   *ptype = ctype != NULL ? ctype : t;
2408   return r;
2409 }
2410
2411 // Return a floating point constant value.
2412
2413 bool
2414 Const_expression::do_float_constant_value(mpfr_t val, Type** ptype) const
2415 {
2416   Type* ctype;
2417   if (this->type_ != NULL)
2418     ctype = this->type_;
2419   else
2420     ctype = this->constant_->const_value()->type();
2421   if (ctype != NULL && ctype->float_type() == NULL)
2422     return false;
2423
2424   Type* t;
2425   bool r = this->constant_->const_value()->expr()->float_constant_value(val,
2426                                                                         &t);
2427   if (r && ctype != NULL)
2428     {
2429       if (!Float_expression::check_constant(val, ctype, this->location()))
2430         return false;
2431       Float_expression::constrain_float(val, ctype);
2432     }
2433   *ptype = ctype != NULL ? ctype : t;
2434   return r;
2435 }
2436
2437 // Return a complex constant value.
2438
2439 bool
2440 Const_expression::do_complex_constant_value(mpfr_t real, mpfr_t imag,
2441                                             Type **ptype) const
2442 {
2443   Type* ctype;
2444   if (this->type_ != NULL)
2445     ctype = this->type_;
2446   else
2447     ctype = this->constant_->const_value()->type();
2448   if (ctype != NULL && ctype->complex_type() == NULL)
2449     return false;
2450
2451   Type *t;
2452   bool r = this->constant_->const_value()->expr()->complex_constant_value(real,
2453                                                                           imag,
2454                                                                           &t);
2455   if (r && ctype != NULL)
2456     {
2457       if (!Complex_expression::check_constant(real, imag, ctype,
2458                                               this->location()))
2459         return false;
2460       Complex_expression::constrain_complex(real, imag, ctype);
2461     }
2462   *ptype = ctype != NULL ? ctype : t;
2463   return r;
2464 }
2465
2466 // Return the type of the const reference.
2467
2468 Type*
2469 Const_expression::do_type()
2470 {
2471   if (this->type_ != NULL)
2472     return this->type_;
2473   Named_constant* nc = this->constant_->const_value();
2474   Type* ret = nc->type();
2475   if (ret != NULL)
2476     return ret;
2477   // During parsing, a named constant may have a NULL type, but we
2478   // must not return a NULL type here.
2479   return nc->expr()->type();
2480 }
2481
2482 // Set the type of the const reference.
2483
2484 void
2485 Const_expression::do_determine_type(const Type_context* context)
2486 {
2487   Type* ctype = this->constant_->const_value()->type();
2488   Type* cetype = (ctype != NULL
2489                   ? ctype
2490                   : this->constant_->const_value()->expr()->type());
2491   if (ctype != NULL && !ctype->is_abstract())
2492     ;
2493   else if (context->type != NULL
2494            && (context->type->integer_type() != NULL
2495                || context->type->float_type() != NULL
2496                || context->type->complex_type() != NULL)
2497            && (cetype->integer_type() != NULL
2498                || cetype->float_type() != NULL
2499                || cetype->complex_type() != NULL))
2500     this->type_ = context->type;
2501   else if (context->type != NULL
2502            && context->type->is_string_type()
2503            && cetype->is_string_type())
2504     this->type_ = context->type;
2505   else if (context->type != NULL
2506            && context->type->is_boolean_type()
2507            && cetype->is_boolean_type())
2508     this->type_ = context->type;
2509   else if (!context->may_be_abstract)
2510     {
2511       if (cetype->is_abstract())
2512         cetype = cetype->make_non_abstract_type();
2513       this->type_ = cetype;
2514     }
2515 }
2516
2517 // Check types of a const reference.
2518
2519 void
2520 Const_expression::do_check_types(Gogo*)
2521 {
2522   if (this->type_ == NULL || this->type_->is_abstract())
2523     return;
2524
2525   // Check for integer overflow.
2526   if (this->type_->integer_type() != NULL)
2527     {
2528       mpz_t ival;
2529       mpz_init(ival);
2530       Type* dummy;
2531       if (!this->integer_constant_value(true, ival, &dummy))
2532         {
2533           mpfr_t fval;
2534           mpfr_init(fval);
2535           Expression* cexpr = this->constant_->const_value()->expr();
2536           if (cexpr->float_constant_value(fval, &dummy))
2537             {
2538               if (!mpfr_integer_p(fval))
2539                 this->report_error(_("floating point constant "
2540                                      "truncated to integer"));
2541               else
2542                 {
2543                   mpfr_get_z(ival, fval, GMP_RNDN);
2544                   Integer_expression::check_constant(ival, this->type_,
2545                                                      this->location());
2546                 }
2547             }
2548           mpfr_clear(fval);
2549         }
2550       mpz_clear(ival);
2551     }
2552 }
2553
2554 // Return a tree for the const reference.
2555
2556 tree
2557 Const_expression::do_get_tree(Translate_context* context)
2558 {
2559   Gogo* gogo = context->gogo();
2560   tree type_tree;
2561   if (this->type_ == NULL)
2562     type_tree = NULL_TREE;
2563   else
2564     {
2565       type_tree = this->type_->get_tree(gogo);
2566       if (type_tree == error_mark_node)
2567         return error_mark_node;
2568     }
2569
2570   // If the type has been set for this expression, but the underlying
2571   // object is an abstract int or float, we try to get the abstract
2572   // value.  Otherwise we may lose something in the conversion.
2573   if (this->type_ != NULL
2574       && this->constant_->const_value()->type()->is_abstract())
2575     {
2576       Expression* expr = this->constant_->const_value()->expr();
2577       mpz_t ival;
2578       mpz_init(ival);
2579       Type* t;
2580       if (expr->integer_constant_value(true, ival, &t))
2581         {
2582           tree ret = Expression::integer_constant_tree(ival, type_tree);
2583           mpz_clear(ival);
2584           return ret;
2585         }
2586       mpz_clear(ival);
2587
2588       mpfr_t fval;
2589       mpfr_init(fval);
2590       if (expr->float_constant_value(fval, &t))
2591         {
2592           tree ret = Expression::float_constant_tree(fval, type_tree);
2593           mpfr_clear(fval);
2594           return ret;
2595         }
2596
2597       mpfr_t imag;
2598       mpfr_init(imag);
2599       if (expr->complex_constant_value(fval, imag, &t))
2600         {
2601           tree ret = Expression::complex_constant_tree(fval, imag, type_tree);
2602           mpfr_clear(fval);
2603           mpfr_clear(imag);
2604           return ret;
2605         }
2606       mpfr_clear(imag);
2607       mpfr_clear(fval);
2608     }
2609
2610   tree const_tree = this->constant_->get_tree(gogo, context->function());
2611   if (this->type_ == NULL
2612       || const_tree == error_mark_node
2613       || TREE_TYPE(const_tree) == error_mark_node)
2614     return const_tree;
2615
2616   tree ret;
2617   if (TYPE_MAIN_VARIANT(type_tree) == TYPE_MAIN_VARIANT(TREE_TYPE(const_tree)))
2618     ret = fold_convert(type_tree, const_tree);
2619   else if (TREE_CODE(type_tree) == INTEGER_TYPE)
2620     ret = fold(convert_to_integer(type_tree, const_tree));
2621   else if (TREE_CODE(type_tree) == REAL_TYPE)
2622     ret = fold(convert_to_real(type_tree, const_tree));
2623   else if (TREE_CODE(type_tree) == COMPLEX_TYPE)
2624     ret = fold(convert_to_complex(type_tree, const_tree));
2625   else
2626     gcc_unreachable();
2627   return ret;
2628 }
2629
2630 // Make a reference to a constant in an expression.
2631
2632 Expression*
2633 Expression::make_const_reference(Named_object* constant,
2634                                  source_location location)
2635 {
2636   return new Const_expression(constant, location);
2637 }
2638
2639 // The nil value.
2640
2641 class Nil_expression : public Expression
2642 {
2643  public:
2644   Nil_expression(source_location location)
2645     : Expression(EXPRESSION_NIL, location)
2646   { }
2647
2648   static Expression*
2649   do_import(Import*);
2650
2651  protected:
2652   bool
2653   do_is_constant() const
2654   { return true; }
2655
2656   Type*
2657   do_type()
2658   { return Type::make_nil_type(); }
2659
2660   void
2661   do_determine_type(const Type_context*)
2662   { }
2663
2664   Expression*
2665   do_copy()
2666   { return this; }
2667
2668   tree
2669   do_get_tree(Translate_context*)
2670   { return null_pointer_node; }
2671
2672   void
2673   do_export(Export* exp) const
2674   { exp->write_c_string("nil"); }
2675 };
2676
2677 // Import a nil expression.
2678
2679 Expression*
2680 Nil_expression::do_import(Import* imp)
2681 {
2682   imp->require_c_string("nil");
2683   return Expression::make_nil(imp->location());
2684 }
2685
2686 // Make a nil expression.
2687
2688 Expression*
2689 Expression::make_nil(source_location location)
2690 {
2691   return new Nil_expression(location);
2692 }
2693
2694 // The value of the predeclared constant iota.  This is little more
2695 // than a marker.  This will be lowered to an integer in
2696 // Const_expression::do_lower, which is where we know the value that
2697 // it should have.
2698
2699 class Iota_expression : public Parser_expression
2700 {
2701  public:
2702   Iota_expression(source_location location)
2703     : Parser_expression(EXPRESSION_IOTA, location)
2704   { }
2705
2706  protected:
2707   Expression*
2708   do_lower(Gogo*, Named_object*, int)
2709   { gcc_unreachable(); }
2710
2711   // There should only ever be one of these.
2712   Expression*
2713   do_copy()
2714   { gcc_unreachable(); }
2715 };
2716
2717 // Make an iota expression.  This is only called for one case: the
2718 // value of the predeclared constant iota.
2719
2720 Expression*
2721 Expression::make_iota()
2722 {
2723   static Iota_expression iota_expression(UNKNOWN_LOCATION);
2724   return &iota_expression;
2725 }
2726
2727 // A type conversion expression.
2728
2729 class Type_conversion_expression : public Expression
2730 {
2731  public:
2732   Type_conversion_expression(Type* type, Expression* expr,
2733                              source_location location)
2734     : Expression(EXPRESSION_CONVERSION, location),
2735       type_(type), expr_(expr), may_convert_function_types_(false)
2736   { }
2737
2738   // Return the type to which we are converting.
2739   Type*
2740   type() const
2741   { return this->type_; }
2742
2743   // Return the expression which we are converting.
2744   Expression*
2745   expr() const
2746   { return this->expr_; }
2747
2748   // Permit converting from one function type to another.  This is
2749   // used internally for method expressions.
2750   void
2751   set_may_convert_function_types()
2752   {
2753     this->may_convert_function_types_ = true;
2754   }
2755
2756   // Import a type conversion expression.
2757   static Expression*
2758   do_import(Import*);
2759
2760  protected:
2761   int
2762   do_traverse(Traverse* traverse);
2763
2764   Expression*
2765   do_lower(Gogo*, Named_object*, int);
2766
2767   bool
2768   do_is_constant() const
2769   { return this->expr_->is_constant(); }
2770
2771   bool
2772   do_integer_constant_value(bool, mpz_t, Type**) const;
2773
2774   bool
2775   do_float_constant_value(mpfr_t, Type**) const;
2776
2777   bool
2778   do_complex_constant_value(mpfr_t, mpfr_t, Type**) const;
2779
2780   bool
2781   do_string_constant_value(std::string*) const;
2782
2783   Type*
2784   do_type()
2785   { return this->type_; }
2786
2787   void
2788   do_determine_type(const Type_context*)
2789   {
2790     Type_context subcontext(this->type_, false);
2791     this->expr_->determine_type(&subcontext);
2792   }
2793
2794   void
2795   do_check_types(Gogo*);
2796
2797   Expression*
2798   do_copy()
2799   {
2800     return new Type_conversion_expression(this->type_, this->expr_->copy(),
2801                                           this->location());
2802   }
2803
2804   tree
2805   do_get_tree(Translate_context* context);
2806
2807   void
2808   do_export(Export*) const;
2809
2810  private:
2811   // The type to convert to.
2812   Type* type_;
2813   // The expression to convert.
2814   Expression* expr_;
2815   // True if this is permitted to convert function types.  This is
2816   // used internally for method expressions.
2817   bool may_convert_function_types_;
2818 };
2819
2820 // Traversal.
2821
2822 int
2823 Type_conversion_expression::do_traverse(Traverse* traverse)
2824 {
2825   if (Expression::traverse(&this->expr_, traverse) == TRAVERSE_EXIT
2826       || Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
2827     return TRAVERSE_EXIT;
2828   return TRAVERSE_CONTINUE;
2829 }
2830
2831 // Convert to a constant at lowering time.
2832
2833 Expression*
2834 Type_conversion_expression::do_lower(Gogo*, Named_object*, int)
2835 {
2836   Type* type = this->type_;
2837   Expression* val = this->expr_;
2838   source_location location = this->location();
2839
2840   if (type->integer_type() != NULL)
2841     {
2842       mpz_t ival;
2843       mpz_init(ival);
2844       Type* dummy;
2845       if (val->integer_constant_value(false, ival, &dummy))
2846         {
2847           if (!Integer_expression::check_constant(ival, type, location))
2848             mpz_set_ui(ival, 0);
2849           Expression* ret = Expression::make_integer(&ival, type, location);
2850           mpz_clear(ival);
2851           return ret;
2852         }
2853
2854       mpfr_t fval;
2855       mpfr_init(fval);
2856       if (val->float_constant_value(fval, &dummy))
2857         {
2858           if (!mpfr_integer_p(fval))
2859             {
2860               error_at(location,
2861                        "floating point constant truncated to integer");
2862               return Expression::make_error(location);
2863             }
2864           mpfr_get_z(ival, fval, GMP_RNDN);
2865           if (!Integer_expression::check_constant(ival, type, location))
2866             mpz_set_ui(ival, 0);
2867           Expression* ret = Expression::make_integer(&ival, type, location);
2868           mpfr_clear(fval);
2869           mpz_clear(ival);
2870           return ret;
2871         }
2872       mpfr_clear(fval);
2873       mpz_clear(ival);
2874     }
2875
2876   if (type->float_type() != NULL)
2877     {
2878       mpfr_t fval;
2879       mpfr_init(fval);
2880       Type* dummy;
2881       if (val->float_constant_value(fval, &dummy))
2882         {
2883           if (!Float_expression::check_constant(fval, type, location))
2884             mpfr_set_ui(fval, 0, GMP_RNDN);
2885           Float_expression::constrain_float(fval, type);
2886           Expression *ret = Expression::make_float(&fval, type, location);
2887           mpfr_clear(fval);
2888           return ret;
2889         }
2890       mpfr_clear(fval);
2891     }
2892
2893   if (type->complex_type() != NULL)
2894     {
2895       mpfr_t real;
2896       mpfr_t imag;
2897       mpfr_init(real);
2898       mpfr_init(imag);
2899       Type* dummy;
2900       if (val->complex_constant_value(real, imag, &dummy))
2901         {
2902           if (!Complex_expression::check_constant(real, imag, type, location))
2903             {
2904               mpfr_set_ui(real, 0, GMP_RNDN);
2905               mpfr_set_ui(imag, 0, GMP_RNDN);
2906             }
2907           Complex_expression::constrain_complex(real, imag, type);
2908           Expression* ret = Expression::make_complex(&real, &imag, type,
2909                                                      location);
2910           mpfr_clear(real);
2911           mpfr_clear(imag);
2912           return ret;
2913         }
2914       mpfr_clear(real);
2915       mpfr_clear(imag);
2916     }
2917
2918   if (type->is_open_array_type() && type->named_type() == NULL)
2919     {
2920       Type* element_type = type->array_type()->element_type()->forwarded();
2921       bool is_byte = element_type == Type::lookup_integer_type("uint8");
2922       bool is_int = element_type == Type::lookup_integer_type("int");
2923       if (is_byte || is_int)
2924         {
2925           std::string s;
2926           if (val->string_constant_value(&s))
2927             {
2928               Expression_list* vals = new Expression_list();
2929               if (is_byte)
2930                 {
2931                   for (std::string::const_iterator p = s.begin();
2932                        p != s.end();
2933                        p++)
2934                     {
2935                       mpz_t val;
2936                       mpz_init_set_ui(val, static_cast<unsigned char>(*p));
2937                       Expression* v = Expression::make_integer(&val,
2938                                                                element_type,
2939                                                                location);
2940                       vals->push_back(v);
2941                       mpz_clear(val);
2942                     }
2943                 }
2944               else
2945                 {
2946                   const char *p = s.data();
2947                   const char *pend = s.data() + s.length();
2948                   while (p < pend)
2949                     {
2950                       unsigned int c;
2951                       int adv = Lex::fetch_char(p, &c);
2952                       if (adv == 0)
2953                         {
2954                           warning_at(this->location(), 0,
2955                                      "invalid UTF-8 encoding");
2956                           adv = 1;
2957                         }
2958                       p += adv;
2959                       mpz_t val;
2960                       mpz_init_set_ui(val, c);
2961                       Expression* v = Expression::make_integer(&val,
2962                                                                element_type,
2963                                                                location);
2964                       vals->push_back(v);
2965                       mpz_clear(val);
2966                     }
2967                 }
2968
2969               return Expression::make_slice_composite_literal(type, vals,
2970                                                               location);
2971             }
2972         }
2973     }
2974
2975   return this;
2976 }
2977
2978 // Return the constant integer value if there is one.
2979
2980 bool
2981 Type_conversion_expression::do_integer_constant_value(bool iota_is_constant,
2982                                                       mpz_t val,
2983                                                       Type** ptype) const
2984 {
2985   if (this->type_->integer_type() == NULL)
2986     return false;
2987
2988   mpz_t ival;
2989   mpz_init(ival);
2990   Type* dummy;
2991   if (this->expr_->integer_constant_value(iota_is_constant, ival, &dummy))
2992     {
2993       if (!Integer_expression::check_constant(ival, this->type_,
2994                                               this->location()))
2995         {
2996           mpz_clear(ival);
2997           return false;
2998         }
2999       mpz_set(val, ival);
3000       mpz_clear(ival);
3001       *ptype = this->type_;
3002       return true;
3003     }
3004   mpz_clear(ival);
3005
3006   mpfr_t fval;
3007   mpfr_init(fval);
3008   if (this->expr_->float_constant_value(fval, &dummy))
3009     {
3010       mpfr_get_z(val, fval, GMP_RNDN);
3011       mpfr_clear(fval);
3012       if (!Integer_expression::check_constant(val, this->type_,
3013                                               this->location()))
3014         return false;
3015       *ptype = this->type_;
3016       return true;
3017     }
3018   mpfr_clear(fval);
3019
3020   return false;
3021 }
3022
3023 // Return the constant floating point value if there is one.
3024
3025 bool
3026 Type_conversion_expression::do_float_constant_value(mpfr_t val,
3027                                                     Type** ptype) const
3028 {
3029   if (this->type_->float_type() == NULL)
3030     return false;
3031
3032   mpfr_t fval;
3033   mpfr_init(fval);
3034   Type* dummy;
3035   if (this->expr_->float_constant_value(fval, &dummy))
3036     {
3037       if (!Float_expression::check_constant(fval, this->type_,
3038                                             this->location()))
3039         {
3040           mpfr_clear(fval);
3041           return false;
3042         }
3043       mpfr_set(val, fval, GMP_RNDN);
3044       mpfr_clear(fval);
3045       Float_expression::constrain_float(val, this->type_);
3046       *ptype = this->type_;
3047       return true;
3048     }
3049   mpfr_clear(fval);
3050
3051   return false;
3052 }
3053
3054 // Return the constant complex value if there is one.
3055
3056 bool
3057 Type_conversion_expression::do_complex_constant_value(mpfr_t real,
3058                                                       mpfr_t imag,
3059                                                       Type **ptype) const
3060 {
3061   if (this->type_->complex_type() == NULL)
3062     return false;
3063
3064   mpfr_t rval;
3065   mpfr_t ival;
3066   mpfr_init(rval);
3067   mpfr_init(ival);
3068   Type* dummy;
3069   if (this->expr_->complex_constant_value(rval, ival, &dummy))
3070     {
3071       if (!Complex_expression::check_constant(rval, ival, this->type_,
3072                                               this->location()))
3073         {
3074           mpfr_clear(rval);
3075           mpfr_clear(ival);
3076           return false;
3077         }
3078       mpfr_set(real, rval, GMP_RNDN);
3079       mpfr_set(imag, ival, GMP_RNDN);
3080       mpfr_clear(rval);
3081       mpfr_clear(ival);
3082       Complex_expression::constrain_complex(real, imag, this->type_);
3083       *ptype = this->type_;
3084       return true;
3085     }
3086   mpfr_clear(rval);
3087   mpfr_clear(ival);
3088
3089   return false;
3090 }
3091
3092 // Return the constant string value if there is one.
3093
3094 bool
3095 Type_conversion_expression::do_string_constant_value(std::string* val) const
3096 {
3097   if (this->type_->is_string_type()
3098       && this->expr_->type()->integer_type() != NULL)
3099     {
3100       mpz_t ival;
3101       mpz_init(ival);
3102       Type* dummy;
3103       if (this->expr_->integer_constant_value(false, ival, &dummy))
3104         {
3105           unsigned long ulval = mpz_get_ui(ival);
3106           if (mpz_cmp_ui(ival, ulval) == 0)
3107             {
3108               Lex::append_char(ulval, true, val, this->location());
3109               mpz_clear(ival);
3110               return true;
3111             }
3112         }
3113       mpz_clear(ival);
3114     }
3115
3116   // FIXME: Could handle conversion from const []int here.
3117
3118   return false;
3119 }
3120
3121 // Check that types are convertible.
3122
3123 void
3124 Type_conversion_expression::do_check_types(Gogo*)
3125 {
3126   Type* type = this->type_;
3127   Type* expr_type = this->expr_->type();
3128   std::string reason;
3129
3130   if (this->may_convert_function_types_
3131       && type->function_type() != NULL
3132       && expr_type->function_type() != NULL)
3133     return;
3134
3135   if (Type::are_convertible(type, expr_type, &reason))
3136     return;
3137
3138   error_at(this->location(), "%s", reason.c_str());
3139   this->set_is_error();
3140 }
3141
3142 // Get a tree for a type conversion.
3143
3144 tree
3145 Type_conversion_expression::do_get_tree(Translate_context* context)
3146 {
3147   Gogo* gogo = context->gogo();
3148   tree type_tree = this->type_->get_tree(gogo);
3149   tree expr_tree = this->expr_->get_tree(context);
3150
3151   if (type_tree == error_mark_node
3152       || expr_tree == error_mark_node
3153       || TREE_TYPE(expr_tree) == error_mark_node)
3154     return error_mark_node;
3155
3156   if (TYPE_MAIN_VARIANT(type_tree) == TYPE_MAIN_VARIANT(TREE_TYPE(expr_tree)))
3157     return fold_convert(type_tree, expr_tree);
3158
3159   Type* type = this->type_;
3160   Type* expr_type = this->expr_->type();
3161   tree ret;
3162   if (type->interface_type() != NULL || expr_type->interface_type() != NULL)
3163     ret = Expression::convert_for_assignment(context, type, expr_type,
3164                                              expr_tree, this->location());
3165   else if (type->integer_type() != NULL)
3166     {
3167       if (expr_type->integer_type() != NULL
3168           || expr_type->float_type() != NULL
3169           || expr_type->is_unsafe_pointer_type())
3170         ret = fold(convert_to_integer(type_tree, expr_tree));
3171       else
3172         gcc_unreachable();
3173     }
3174   else if (type->float_type() != NULL)
3175     {
3176       if (expr_type->integer_type() != NULL
3177           || expr_type->float_type() != NULL)
3178         ret = fold(convert_to_real(type_tree, expr_tree));
3179       else
3180         gcc_unreachable();
3181     }
3182   else if (type->complex_type() != NULL)
3183     {
3184       if (expr_type->complex_type() != NULL)
3185         ret = fold(convert_to_complex(type_tree, expr_tree));
3186       else
3187         gcc_unreachable();
3188     }
3189   else if (type->is_string_type()
3190            && expr_type->integer_type() != NULL)
3191     {
3192       expr_tree = fold_convert(integer_type_node, expr_tree);
3193       if (host_integerp(expr_tree, 0))
3194         {
3195           HOST_WIDE_INT intval = tree_low_cst(expr_tree, 0);
3196           std::string s;
3197           Lex::append_char(intval, true, &s, this->location());
3198           Expression* se = Expression::make_string(s, this->location());
3199           return se->get_tree(context);
3200         }
3201
3202       static tree int_to_string_fndecl;
3203       ret = Gogo::call_builtin(&int_to_string_fndecl,
3204                                this->location(),
3205                                "__go_int_to_string",
3206                                1,
3207                                type_tree,
3208                                integer_type_node,
3209                                fold_convert(integer_type_node, expr_tree));
3210     }
3211   else if (type->is_string_type()
3212            && (expr_type->array_type() != NULL
3213                || (expr_type->points_to() != NULL
3214                    && expr_type->points_to()->array_type() != NULL)))
3215     {
3216       Type* t = expr_type;
3217       if (t->points_to() != NULL)
3218         {
3219           t = t->points_to();
3220           expr_tree = build_fold_indirect_ref(expr_tree);
3221         }
3222       if (!DECL_P(expr_tree))
3223         expr_tree = save_expr(expr_tree);
3224       Array_type* a = t->array_type();
3225       Type* e = a->element_type()->forwarded();
3226       gcc_assert(e->integer_type() != NULL);
3227       tree valptr = fold_convert(const_ptr_type_node,
3228                                  a->value_pointer_tree(gogo, expr_tree));
3229       tree len = a->length_tree(gogo, expr_tree);
3230       len = fold_convert_loc(this->location(), size_type_node, len);
3231       if (e->integer_type()->is_unsigned()
3232           && e->integer_type()->bits() == 8)
3233         {
3234           static tree byte_array_to_string_fndecl;
3235           ret = Gogo::call_builtin(&byte_array_to_string_fndecl,
3236                                    this->location(),
3237                                    "__go_byte_array_to_string",
3238                                    2,
3239                                    type_tree,
3240                                    const_ptr_type_node,
3241                                    valptr,
3242                                    size_type_node,
3243                                    len);
3244         }
3245       else
3246         {
3247           gcc_assert(e == Type::lookup_integer_type("int"));
3248           static tree int_array_to_string_fndecl;
3249           ret = Gogo::call_builtin(&int_array_to_string_fndecl,
3250                                    this->location(),
3251                                    "__go_int_array_to_string",
3252                                    2,
3253                                    type_tree,
3254                                    const_ptr_type_node,
3255                                    valptr,
3256                                    size_type_node,
3257                                    len);
3258         }
3259     }
3260   else if (type->is_open_array_type() && expr_type->is_string_type())
3261     {
3262       Type* e = type->array_type()->element_type()->forwarded();
3263       gcc_assert(e->integer_type() != NULL);
3264       if (e->integer_type()->is_unsigned()
3265           && e->integer_type()->bits() == 8)
3266         {
3267           static tree string_to_byte_array_fndecl;
3268           ret = Gogo::call_builtin(&string_to_byte_array_fndecl,
3269                                    this->location(),
3270                                    "__go_string_to_byte_array",
3271                                    1,
3272                                    type_tree,
3273                                    TREE_TYPE(expr_tree),
3274                                    expr_tree);
3275         }
3276       else
3277         {
3278           gcc_assert(e == Type::lookup_integer_type("int"));
3279           static tree string_to_int_array_fndecl;
3280           ret = Gogo::call_builtin(&string_to_int_array_fndecl,
3281                                    this->location(),
3282                                    "__go_string_to_int_array",
3283                                    1,
3284                                    type_tree,
3285                                    TREE_TYPE(expr_tree),
3286                                    expr_tree);
3287         }
3288     }
3289   else if ((type->is_unsafe_pointer_type()
3290             && expr_type->points_to() != NULL)
3291            || (expr_type->is_unsafe_pointer_type()
3292                && type->points_to() != NULL))
3293     ret = fold_convert(type_tree, expr_tree);
3294   else if (type->is_unsafe_pointer_type()
3295            && expr_type->integer_type() != NULL)
3296     ret = convert_to_pointer(type_tree, expr_tree);
3297   else if (this->may_convert_function_types_
3298            && type->function_type() != NULL
3299            && expr_type->function_type() != NULL)
3300     ret = fold_convert_loc(this->location(), type_tree, expr_tree);
3301   else
3302     ret = Expression::convert_for_assignment(context, type, expr_type,
3303                                              expr_tree, this->location());
3304
3305   return ret;
3306 }
3307
3308 // Output a type conversion in a constant expression.
3309
3310 void
3311 Type_conversion_expression::do_export(Export* exp) const
3312 {
3313   exp->write_c_string("convert(");
3314   exp->write_type(this->type_);
3315   exp->write_c_string(", ");
3316   this->expr_->export_expression(exp);
3317   exp->write_c_string(")");
3318 }
3319
3320 // Import a type conversion or a struct construction.
3321
3322 Expression*
3323 Type_conversion_expression::do_import(Import* imp)
3324 {
3325   imp->require_c_string("convert(");
3326   Type* type = imp->read_type();
3327   imp->require_c_string(", ");
3328   Expression* val = Expression::import_expression(imp);
3329   imp->require_c_string(")");
3330   return Expression::make_cast(type, val, imp->location());
3331 }
3332
3333 // Make a type cast expression.
3334
3335 Expression*
3336 Expression::make_cast(Type* type, Expression* val, source_location location)
3337 {
3338   if (type->is_error_type() || val->is_error_expression())
3339     return Expression::make_error(location);
3340   return new Type_conversion_expression(type, val, location);
3341 }
3342
3343 // Unary expressions.
3344
3345 class Unary_expression : public Expression
3346 {
3347  public:
3348   Unary_expression(Operator op, Expression* expr, source_location location)
3349     : Expression(EXPRESSION_UNARY, location),
3350       op_(op), escapes_(true), expr_(expr)
3351   { }
3352
3353   // Return the operator.
3354   Operator
3355   op() const
3356   { return this->op_; }
3357
3358   // Return the operand.
3359   Expression*
3360   operand() const
3361   { return this->expr_; }
3362
3363   // Record that an address expression does not escape.
3364   void
3365   set_does_not_escape()
3366   {
3367     gcc_assert(this->op_ == OPERATOR_AND);
3368     this->escapes_ = false;
3369   }
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_integer(Operator op, Type* utype, mpz_t uval, mpz_t val,
3375                source_location);
3376
3377   // Apply unary opcode OP to UVAL, setting VAL.  Return true if this
3378   // could be done, false if not.
3379   static bool
3380   eval_float(Operator op, mpfr_t uval, mpfr_t val);
3381
3382   // Apply unary opcode OP to UREAL/UIMAG, setting REAL/IMAG.  Return
3383   // true if this could be done, false if not.
3384   static bool
3385   eval_complex(Operator op, mpfr_t ureal, mpfr_t uimag, mpfr_t real,
3386                mpfr_t imag);
3387
3388   static Expression*
3389   do_import(Import*);
3390
3391  protected:
3392   int
3393   do_traverse(Traverse* traverse)
3394   { return Expression::traverse(&this->expr_, traverse); }
3395
3396   Expression*
3397   do_lower(Gogo*, Named_object*, int);
3398
3399   bool
3400   do_is_constant() const;
3401
3402   bool
3403   do_integer_constant_value(bool, mpz_t, Type**) const;
3404
3405   bool
3406   do_float_constant_value(mpfr_t, Type**) const;
3407
3408   bool
3409   do_complex_constant_value(mpfr_t, mpfr_t, Type**) const;
3410
3411   Type*
3412   do_type();
3413
3414   void
3415   do_determine_type(const Type_context*);
3416
3417   void
3418   do_check_types(Gogo*);
3419
3420   Expression*
3421   do_copy()
3422   {
3423     return Expression::make_unary(this->op_, this->expr_->copy(),
3424                                   this->location());
3425   }
3426
3427   bool
3428   do_is_addressable() const
3429   { return this->op_ == OPERATOR_MULT; }
3430
3431   tree
3432   do_get_tree(Translate_context*);
3433
3434   void
3435   do_export(Export*) const;
3436
3437  private:
3438   // The unary operator to apply.
3439   Operator op_;
3440   // Normally true.  False if this is an address expression which does
3441   // not escape the current function.
3442   bool escapes_;
3443   // The operand.
3444   Expression* expr_;
3445 };
3446
3447 // If we are taking the address of a composite literal, and the
3448 // contents are not constant, then we want to make a heap composite
3449 // instead.
3450
3451 Expression*
3452 Unary_expression::do_lower(Gogo*, Named_object*, int)
3453 {
3454   source_location loc = this->location();
3455   Operator op = this->op_;
3456   Expression* expr = this->expr_;
3457
3458   if (op == OPERATOR_MULT && expr->is_type_expression())
3459     return Expression::make_type(Type::make_pointer_type(expr->type()), loc);
3460
3461   // *&x simplifies to x.  *(*T)(unsafe.Pointer)(&x) does not require
3462   // moving x to the heap.  FIXME: Is it worth doing a real escape
3463   // analysis here?  This case is found in math/unsafe.go and is
3464   // therefore worth special casing.
3465   if (op == OPERATOR_MULT)
3466     {
3467       Expression* e = expr;
3468       while (e->classification() == EXPRESSION_CONVERSION)
3469         {
3470           Type_conversion_expression* te
3471             = static_cast<Type_conversion_expression*>(e);
3472           e = te->expr();
3473         }
3474
3475       if (e->classification() == EXPRESSION_UNARY)
3476         {
3477           Unary_expression* ue = static_cast<Unary_expression*>(e);
3478           if (ue->op_ == OPERATOR_AND)
3479             {
3480               if (e == expr)
3481                 {
3482                   // *&x == x.
3483                   return ue->expr_;
3484                 }
3485               ue->set_does_not_escape();
3486             }
3487         }
3488     }
3489
3490   if (op == OPERATOR_PLUS || op == OPERATOR_MINUS
3491       || op == OPERATOR_NOT || op == OPERATOR_XOR)
3492     {
3493       Expression* ret = NULL;
3494
3495       mpz_t eval;
3496       mpz_init(eval);
3497       Type* etype;
3498       if (expr->integer_constant_value(false, eval, &etype))
3499         {
3500           mpz_t val;
3501           mpz_init(val);
3502           if (Unary_expression::eval_integer(op, etype, eval, val, loc))
3503             ret = Expression::make_integer(&val, etype, loc);
3504           mpz_clear(val);
3505         }
3506       mpz_clear(eval);
3507       if (ret != NULL)
3508         return ret;
3509
3510       if (op == OPERATOR_PLUS || op == OPERATOR_MINUS)
3511         {
3512           mpfr_t fval;
3513           mpfr_init(fval);
3514           Type* ftype;
3515           if (expr->float_constant_value(fval, &ftype))
3516             {
3517               mpfr_t val;
3518               mpfr_init(val);
3519               if (Unary_expression::eval_float(op, fval, val))
3520                 ret = Expression::make_float(&val, ftype, loc);
3521               mpfr_clear(val);
3522             }
3523           if (ret != NULL)
3524             {
3525               mpfr_clear(fval);
3526               return ret;
3527             }
3528
3529           mpfr_t ival;
3530           mpfr_init(ival);
3531           if (expr->complex_constant_value(fval, ival, &ftype))
3532             {
3533               mpfr_t real;
3534               mpfr_t imag;
3535               mpfr_init(real);
3536               mpfr_init(imag);
3537               if (Unary_expression::eval_complex(op, fval, ival, real, imag))
3538                 ret = Expression::make_complex(&real, &imag, ftype, loc);
3539               mpfr_clear(real);
3540               mpfr_clear(imag);
3541             }
3542           mpfr_clear(ival);
3543           mpfr_clear(fval);
3544           if (ret != NULL)
3545             return ret;
3546         }
3547     }
3548
3549   return this;
3550 }
3551
3552 // Return whether a unary expression is a constant.
3553
3554 bool
3555 Unary_expression::do_is_constant() const
3556 {
3557   if (this->op_ == OPERATOR_MULT)
3558     {
3559       // Indirecting through a pointer is only constant if the object
3560       // to which the expression points is constant, but we currently
3561       // have no way to determine that.
3562       return false;
3563     }
3564   else if (this->op_ == OPERATOR_AND)
3565     {
3566       // Taking the address of a variable is constant if it is a
3567       // global variable, not constant otherwise.  In other cases
3568       // taking the address is probably not a constant.
3569       Var_expression* ve = this->expr_->var_expression();
3570       if (ve != NULL)
3571         {
3572           Named_object* no = ve->named_object();
3573           return no->is_variable() && no->var_value()->is_global();
3574         }
3575       return false;
3576     }
3577   else
3578     return this->expr_->is_constant();
3579 }
3580
3581 // Apply unary opcode OP to UVAL, setting VAL.  UTYPE is the type of
3582 // UVAL, if known; it may be NULL.  Return true if this could be done,
3583 // false if not.
3584
3585 bool
3586 Unary_expression::eval_integer(Operator op, Type* utype, mpz_t uval, mpz_t val,
3587                                source_location location)
3588 {
3589   switch (op)
3590     {
3591     case OPERATOR_PLUS:
3592       mpz_set(val, uval);
3593       return true;
3594     case OPERATOR_MINUS:
3595       mpz_neg(val, uval);
3596       return Integer_expression::check_constant(val, utype, location);
3597     case OPERATOR_NOT:
3598       mpz_set_ui(val, mpz_cmp_si(uval, 0) == 0 ? 1 : 0);
3599       return true;
3600     case OPERATOR_XOR:
3601       if (utype == NULL
3602           || utype->integer_type() == NULL
3603           || utype->integer_type()->is_abstract())
3604         mpz_com(val, uval);
3605       else
3606         {
3607           // The number of HOST_WIDE_INTs that it takes to represent
3608           // UVAL.
3609           size_t count = ((mpz_sizeinbase(uval, 2)
3610                            + HOST_BITS_PER_WIDE_INT
3611                            - 1)
3612                           / HOST_BITS_PER_WIDE_INT);
3613
3614           unsigned HOST_WIDE_INT* phwi = new unsigned HOST_WIDE_INT[count];
3615           memset(phwi, 0, count * sizeof(HOST_WIDE_INT));
3616
3617           size_t ecount;
3618           mpz_export(phwi, &ecount, -1, sizeof(HOST_WIDE_INT), 0, 0, uval);
3619           gcc_assert(ecount <= count);
3620
3621           // Trim down to the number of words required by the type.
3622           size_t obits = utype->integer_type()->bits();
3623           if (!utype->integer_type()->is_unsigned())
3624             ++obits;
3625           size_t ocount = ((obits + HOST_BITS_PER_WIDE_INT - 1)
3626                            / HOST_BITS_PER_WIDE_INT);
3627           gcc_assert(ocount <= ocount);
3628
3629           for (size_t i = 0; i < ocount; ++i)
3630             phwi[i] = ~phwi[i];
3631
3632           size_t clearbits = ocount * HOST_BITS_PER_WIDE_INT - obits;
3633           if (clearbits != 0)
3634             phwi[ocount - 1] &= (((unsigned HOST_WIDE_INT) (HOST_WIDE_INT) -1)
3635                                  >> clearbits);
3636
3637           mpz_import(val, ocount, -1, sizeof(HOST_WIDE_INT), 0, 0, phwi);
3638
3639           delete[] phwi;
3640         }
3641       return Integer_expression::check_constant(val, utype, location);
3642     case OPERATOR_AND:
3643     case OPERATOR_MULT:
3644       return false;
3645     default:
3646       gcc_unreachable();
3647     }
3648 }
3649
3650 // Apply unary opcode OP to UVAL, setting VAL.  Return true if this
3651 // could be done, false if not.
3652
3653 bool
3654 Unary_expression::eval_float(Operator op, mpfr_t uval, mpfr_t val)
3655 {
3656   switch (op)
3657     {
3658     case OPERATOR_PLUS:
3659       mpfr_set(val, uval, GMP_RNDN);
3660       return true;
3661     case OPERATOR_MINUS:
3662       mpfr_neg(val, uval, GMP_RNDN);
3663       return true;
3664     case OPERATOR_NOT:
3665     case OPERATOR_XOR:
3666     case OPERATOR_AND:
3667     case OPERATOR_MULT:
3668       return false;
3669     default:
3670       gcc_unreachable();
3671     }
3672 }
3673
3674 // Apply unary opcode OP to RVAL/IVAL, setting REAL/IMAG.  Return true
3675 // if this could be done, false if not.
3676
3677 bool
3678 Unary_expression::eval_complex(Operator op, mpfr_t rval, mpfr_t ival,
3679                                mpfr_t real, mpfr_t imag)
3680 {
3681   switch (op)
3682     {
3683     case OPERATOR_PLUS:
3684       mpfr_set(real, rval, GMP_RNDN);
3685       mpfr_set(imag, ival, GMP_RNDN);
3686       return true;
3687     case OPERATOR_MINUS:
3688       mpfr_neg(real, rval, GMP_RNDN);
3689       mpfr_neg(imag, ival, GMP_RNDN);
3690       return true;
3691     case OPERATOR_NOT:
3692     case OPERATOR_XOR:
3693     case OPERATOR_AND:
3694     case OPERATOR_MULT:
3695       return false;
3696     default:
3697       gcc_unreachable();
3698     }
3699 }
3700
3701 // Return the integral constant value of a unary expression, if it has one.
3702
3703 bool
3704 Unary_expression::do_integer_constant_value(bool iota_is_constant, mpz_t val,
3705                                             Type** ptype) const
3706 {
3707   mpz_t uval;
3708   mpz_init(uval);
3709   bool ret;
3710   if (!this->expr_->integer_constant_value(iota_is_constant, uval, ptype))
3711     ret = false;
3712   else
3713     ret = Unary_expression::eval_integer(this->op_, *ptype, uval, val,
3714                                          this->location());
3715   mpz_clear(uval);
3716   return ret;
3717 }
3718
3719 // Return the floating point constant value of a unary expression, if
3720 // it has one.
3721
3722 bool
3723 Unary_expression::do_float_constant_value(mpfr_t val, Type** ptype) const
3724 {
3725   mpfr_t uval;
3726   mpfr_init(uval);
3727   bool ret;
3728   if (!this->expr_->float_constant_value(uval, ptype))
3729     ret = false;
3730   else
3731     ret = Unary_expression::eval_float(this->op_, uval, val);
3732   mpfr_clear(uval);
3733   return ret;
3734 }
3735
3736 // Return the complex constant value of a unary expression, if it has
3737 // one.
3738
3739 bool
3740 Unary_expression::do_complex_constant_value(mpfr_t real, mpfr_t imag,
3741                                             Type** ptype) const
3742 {
3743   mpfr_t rval;
3744   mpfr_t ival;
3745   mpfr_init(rval);
3746   mpfr_init(ival);
3747   bool ret;
3748   if (!this->expr_->complex_constant_value(rval, ival, ptype))
3749     ret = false;
3750   else
3751     ret = Unary_expression::eval_complex(this->op_, rval, ival, real, imag);
3752   mpfr_clear(rval);
3753   mpfr_clear(ival);
3754   return ret;
3755 }
3756
3757 // Return the type of a unary expression.
3758
3759 Type*
3760 Unary_expression::do_type()
3761 {
3762   switch (this->op_)
3763     {
3764     case OPERATOR_PLUS:
3765     case OPERATOR_MINUS:
3766     case OPERATOR_NOT:
3767     case OPERATOR_XOR:
3768       return this->expr_->type();
3769
3770     case OPERATOR_AND:
3771       return Type::make_pointer_type(this->expr_->type());
3772
3773     case OPERATOR_MULT:
3774       {
3775         Type* subtype = this->expr_->type();
3776         Type* points_to = subtype->points_to();
3777         if (points_to == NULL)
3778           return Type::make_error_type();
3779         return points_to;
3780       }
3781
3782     default:
3783       gcc_unreachable();
3784     }
3785 }
3786
3787 // Determine abstract types for a unary expression.
3788
3789 void
3790 Unary_expression::do_determine_type(const Type_context* context)
3791 {
3792   switch (this->op_)
3793     {
3794     case OPERATOR_PLUS:
3795     case OPERATOR_MINUS:
3796     case OPERATOR_NOT:
3797     case OPERATOR_XOR:
3798       this->expr_->determine_type(context);
3799       break;
3800
3801     case OPERATOR_AND:
3802       // Taking the address of something.
3803       {
3804         Type* subtype = (context->type == NULL
3805                          ? NULL
3806                          : context->type->points_to());
3807         Type_context subcontext(subtype, false);
3808         this->expr_->determine_type(&subcontext);
3809       }
3810       break;
3811
3812     case OPERATOR_MULT:
3813       // Indirecting through a pointer.
3814       {
3815         Type* subtype = (context->type == NULL
3816                          ? NULL
3817                          : Type::make_pointer_type(context->type));
3818         Type_context subcontext(subtype, false);
3819         this->expr_->determine_type(&subcontext);
3820       }
3821       break;
3822
3823     default:
3824       gcc_unreachable();
3825     }
3826 }
3827
3828 // Check types for a unary expression.
3829
3830 void
3831 Unary_expression::do_check_types(Gogo*)
3832 {
3833   Type* type = this->expr_->type();
3834   if (type->is_error_type())
3835     {
3836       this->set_is_error();
3837       return;
3838     }
3839
3840   switch (this->op_)
3841     {
3842     case OPERATOR_PLUS:
3843     case OPERATOR_MINUS:
3844       if (type->integer_type() == NULL
3845           && type->float_type() == NULL
3846           && type->complex_type() == NULL)
3847         this->report_error(_("expected numeric type"));
3848       break;
3849
3850     case OPERATOR_NOT:
3851     case OPERATOR_XOR:
3852       if (type->integer_type() == NULL
3853           && !type->is_boolean_type())
3854         this->report_error(_("expected integer or boolean type"));
3855       break;
3856
3857     case OPERATOR_AND:
3858       if (!this->expr_->is_addressable())
3859         this->report_error(_("invalid operand for unary %<&%>"));
3860       else
3861         this->expr_->address_taken(this->escapes_);
3862       break;
3863
3864     case OPERATOR_MULT:
3865       // Indirecting through a pointer.
3866       if (type->points_to() == NULL)
3867         this->report_error(_("expected pointer"));
3868       break;
3869
3870     default:
3871       gcc_unreachable();
3872     }
3873 }
3874
3875 // Get a tree for a unary expression.
3876
3877 tree
3878 Unary_expression::do_get_tree(Translate_context* context)
3879 {
3880   tree expr = this->expr_->get_tree(context);
3881   if (expr == error_mark_node)
3882     return error_mark_node;
3883
3884   source_location loc = this->location();
3885   switch (this->op_)
3886     {
3887     case OPERATOR_PLUS:
3888       return expr;
3889
3890     case OPERATOR_MINUS:
3891       {
3892         tree type = TREE_TYPE(expr);
3893         tree compute_type = excess_precision_type(type);
3894         if (compute_type != NULL_TREE)
3895           expr = ::convert(compute_type, expr);
3896         tree ret = fold_build1_loc(loc, NEGATE_EXPR,
3897                                    (compute_type != NULL_TREE
3898                                     ? compute_type
3899                                     : type),
3900                                    expr);
3901         if (compute_type != NULL_TREE)
3902           ret = ::convert(type, ret);
3903         return ret;
3904       }
3905
3906     case OPERATOR_NOT:
3907       if (TREE_CODE(TREE_TYPE(expr)) == BOOLEAN_TYPE)
3908         return fold_build1_loc(loc, TRUTH_NOT_EXPR, TREE_TYPE(expr), expr);
3909       else
3910         return fold_build2_loc(loc, NE_EXPR, boolean_type_node, expr,
3911                                build_int_cst(TREE_TYPE(expr), 0));
3912
3913     case OPERATOR_XOR:
3914       return fold_build1_loc(loc, BIT_NOT_EXPR, TREE_TYPE(expr), expr);
3915
3916     case OPERATOR_AND:
3917       // We should not see a non-constant constructor here; cases
3918       // where we would see one should have been moved onto the heap
3919       // at parse time.  Taking the address of a nonconstant
3920       // constructor will not do what the programmer expects.
3921       gcc_assert(TREE_CODE(expr) != CONSTRUCTOR || TREE_CONSTANT(expr));
3922       gcc_assert(TREE_CODE(expr) != ADDR_EXPR);
3923
3924       // Build a decl for a constant constructor.
3925       if (TREE_CODE(expr) == CONSTRUCTOR && TREE_CONSTANT(expr))
3926         {
3927           tree decl = build_decl(this->location(), VAR_DECL,
3928                                  create_tmp_var_name("C"), TREE_TYPE(expr));
3929           DECL_EXTERNAL(decl) = 0;
3930           TREE_PUBLIC(decl) = 0;
3931           TREE_READONLY(decl) = 1;
3932           TREE_CONSTANT(decl) = 1;
3933           TREE_STATIC(decl) = 1;
3934           TREE_ADDRESSABLE(decl) = 1;
3935           DECL_ARTIFICIAL(decl) = 1;
3936           DECL_INITIAL(decl) = expr;
3937           rest_of_decl_compilation(decl, 1, 0);
3938           expr = decl;
3939         }
3940
3941       return build_fold_addr_expr_loc(loc, expr);
3942
3943     case OPERATOR_MULT:
3944       {
3945         gcc_assert(POINTER_TYPE_P(TREE_TYPE(expr)));
3946
3947         // If we are dereferencing the pointer to a large struct, we
3948         // need to check for nil.  We don't bother to check for small
3949         // structs because we expect the system to crash on a nil
3950         // pointer dereference.
3951         HOST_WIDE_INT s = int_size_in_bytes(TREE_TYPE(TREE_TYPE(expr)));
3952         if (s == -1 || s >= 4096)
3953           {
3954             if (!DECL_P(expr))
3955               expr = save_expr(expr);
3956             tree compare = fold_build2_loc(loc, EQ_EXPR, boolean_type_node,
3957                                            expr,
3958                                            fold_convert(TREE_TYPE(expr),
3959                                                         null_pointer_node));
3960             tree crash = Gogo::runtime_error(RUNTIME_ERROR_NIL_DEREFERENCE,
3961                                              loc);
3962             expr = fold_build2_loc(loc, COMPOUND_EXPR, TREE_TYPE(expr),
3963                                    build3(COND_EXPR, void_type_node,
3964                                           compare, crash, NULL_TREE),
3965                                    expr);
3966           }
3967
3968         // If the type of EXPR is a recursive pointer type, then we
3969         // need to insert a cast before indirecting.
3970         if (TREE_TYPE(TREE_TYPE(expr)) == ptr_type_node)
3971           {
3972             Type* pt = this->expr_->type()->points_to();
3973             tree ind = pt->get_tree(context->gogo());
3974             expr = fold_convert_loc(loc, build_pointer_type(ind), expr);
3975           }
3976
3977         return build_fold_indirect_ref_loc(loc, expr);
3978       }
3979
3980     default:
3981       gcc_unreachable();
3982     }
3983 }
3984
3985 // Export a unary expression.
3986
3987 void
3988 Unary_expression::do_export(Export* exp) const
3989 {
3990   switch (this->op_)
3991     {
3992     case OPERATOR_PLUS:
3993       exp->write_c_string("+ ");
3994       break;
3995     case OPERATOR_MINUS:
3996       exp->write_c_string("- ");
3997       break;
3998     case OPERATOR_NOT:
3999       exp->write_c_string("! ");
4000       break;
4001     case OPERATOR_XOR:
4002       exp->write_c_string("^ ");
4003       break;
4004     case OPERATOR_AND:
4005     case OPERATOR_MULT:
4006     default:
4007       gcc_unreachable();
4008     }
4009   this->expr_->export_expression(exp);
4010 }
4011
4012 // Import a unary expression.
4013
4014 Expression*
4015 Unary_expression::do_import(Import* imp)
4016 {
4017   Operator op;
4018   switch (imp->get_char())
4019     {
4020     case '+':
4021       op = OPERATOR_PLUS;
4022       break;
4023     case '-':
4024       op = OPERATOR_MINUS;
4025       break;
4026     case '!':
4027       op = OPERATOR_NOT;
4028       break;
4029     case '^':
4030       op = OPERATOR_XOR;
4031       break;
4032     default:
4033       gcc_unreachable();
4034     }
4035   imp->require_c_string(" ");
4036   Expression* expr = Expression::import_expression(imp);
4037   return Expression::make_unary(op, expr, imp->location());
4038 }
4039
4040 // Make a unary expression.
4041
4042 Expression*
4043 Expression::make_unary(Operator op, Expression* expr, source_location location)
4044 {
4045   return new Unary_expression(op, expr, location);
4046 }
4047
4048 // If this is an indirection through a pointer, return the expression
4049 // being pointed through.  Otherwise return this.
4050
4051 Expression*
4052 Expression::deref()
4053 {
4054   if (this->classification_ == EXPRESSION_UNARY)
4055     {
4056       Unary_expression* ue = static_cast<Unary_expression*>(this);
4057       if (ue->op() == OPERATOR_MULT)
4058         return ue->operand();
4059     }
4060   return this;
4061 }
4062
4063 // Class Binary_expression.
4064
4065 // Traversal.
4066
4067 int
4068 Binary_expression::do_traverse(Traverse* traverse)
4069 {
4070   int t = Expression::traverse(&this->left_, traverse);
4071   if (t == TRAVERSE_EXIT)
4072     return TRAVERSE_EXIT;
4073   return Expression::traverse(&this->right_, traverse);
4074 }
4075
4076 // Compare integer constants according to OP.
4077
4078 bool
4079 Binary_expression::compare_integer(Operator op, mpz_t left_val,
4080                                    mpz_t right_val)
4081 {
4082   int i = mpz_cmp(left_val, right_val);
4083   switch (op)
4084     {
4085     case OPERATOR_EQEQ:
4086       return i == 0;
4087     case OPERATOR_NOTEQ:
4088       return i != 0;
4089     case OPERATOR_LT:
4090       return i < 0;
4091     case OPERATOR_LE:
4092       return i <= 0;
4093     case OPERATOR_GT:
4094       return i > 0;
4095     case OPERATOR_GE:
4096       return i >= 0;
4097     default:
4098       gcc_unreachable();
4099     }
4100 }
4101
4102 // Compare floating point constants according to OP.
4103
4104 bool
4105 Binary_expression::compare_float(Operator op, Type* type, mpfr_t left_val,
4106                                  mpfr_t right_val)
4107 {
4108   int i;
4109   if (type == NULL)
4110     i = mpfr_cmp(left_val, right_val);
4111   else
4112     {
4113       mpfr_t lv;
4114       mpfr_init_set(lv, left_val, GMP_RNDN);
4115       mpfr_t rv;
4116       mpfr_init_set(rv, right_val, GMP_RNDN);
4117       Float_expression::constrain_float(lv, type);
4118       Float_expression::constrain_float(rv, type);
4119       i = mpfr_cmp(lv, rv);
4120       mpfr_clear(lv);
4121       mpfr_clear(rv);
4122     }
4123   switch (op)
4124     {
4125     case OPERATOR_EQEQ:
4126       return i == 0;
4127     case OPERATOR_NOTEQ:
4128       return i != 0;
4129     case OPERATOR_LT:
4130       return i < 0;
4131     case OPERATOR_LE:
4132       return i <= 0;
4133     case OPERATOR_GT:
4134       return i > 0;
4135     case OPERATOR_GE:
4136       return i >= 0;
4137     default:
4138       gcc_unreachable();
4139     }
4140 }
4141
4142 // Compare complex constants according to OP.  Complex numbers may
4143 // only be compared for equality.
4144
4145 bool
4146 Binary_expression::compare_complex(Operator op, Type* type,
4147                                    mpfr_t left_real, mpfr_t left_imag,
4148                                    mpfr_t right_real, mpfr_t right_imag)
4149 {
4150   bool is_equal;
4151   if (type == NULL)
4152     is_equal = (mpfr_cmp(left_real, right_real) == 0
4153                 && mpfr_cmp(left_imag, right_imag) == 0);
4154   else
4155     {
4156       mpfr_t lr;
4157       mpfr_t li;
4158       mpfr_init_set(lr, left_real, GMP_RNDN);
4159       mpfr_init_set(li, left_imag, GMP_RNDN);
4160       mpfr_t rr;
4161       mpfr_t ri;
4162       mpfr_init_set(rr, right_real, GMP_RNDN);
4163       mpfr_init_set(ri, right_imag, GMP_RNDN);
4164       Complex_expression::constrain_complex(lr, li, type);
4165       Complex_expression::constrain_complex(rr, ri, type);
4166       is_equal = mpfr_cmp(lr, rr) == 0 && mpfr_cmp(li, ri) == 0;
4167       mpfr_clear(lr);
4168       mpfr_clear(li);
4169       mpfr_clear(rr);
4170       mpfr_clear(ri);
4171     }
4172   switch (op)
4173     {
4174     case OPERATOR_EQEQ:
4175       return is_equal;
4176     case OPERATOR_NOTEQ:
4177       return !is_equal;
4178     default:
4179       gcc_unreachable();
4180     }
4181 }
4182
4183 // Apply binary opcode OP to LEFT_VAL and RIGHT_VAL, setting VAL.
4184 // LEFT_TYPE is the type of LEFT_VAL, RIGHT_TYPE is the type of
4185 // RIGHT_VAL; LEFT_TYPE and/or RIGHT_TYPE may be NULL.  Return true if
4186 // this could be done, false if not.
4187
4188 bool
4189 Binary_expression::eval_integer(Operator op, Type* left_type, mpz_t left_val,
4190                                 Type* right_type, mpz_t right_val,
4191                                 source_location location, mpz_t val)
4192 {
4193   bool is_shift_op = false;
4194   switch (op)
4195     {
4196     case OPERATOR_OROR:
4197     case OPERATOR_ANDAND:
4198     case OPERATOR_EQEQ:
4199     case OPERATOR_NOTEQ:
4200     case OPERATOR_LT:
4201     case OPERATOR_LE:
4202     case OPERATOR_GT:
4203     case OPERATOR_GE:
4204       // These return boolean values.  We should probably handle them
4205       // anyhow in case a type conversion is used on the result.
4206       return false;
4207     case OPERATOR_PLUS:
4208       mpz_add(val, left_val, right_val);
4209       break;
4210     case OPERATOR_MINUS:
4211       mpz_sub(val, left_val, right_val);
4212       break;
4213     case OPERATOR_OR:
4214       mpz_ior(val, left_val, right_val);
4215       break;
4216     case OPERATOR_XOR:
4217       mpz_xor(val, left_val, right_val);
4218       break;
4219     case OPERATOR_MULT:
4220       mpz_mul(val, left_val, right_val);
4221       break;
4222     case OPERATOR_DIV:
4223       if (mpz_sgn(right_val) != 0)
4224         mpz_tdiv_q(val, left_val, right_val);
4225       else
4226         {
4227           error_at(location, "division by zero");
4228           mpz_set_ui(val, 0);
4229           return true;
4230         }
4231       break;
4232     case OPERATOR_MOD:
4233       if (mpz_sgn(right_val) != 0)
4234         mpz_tdiv_r(val, left_val, right_val);
4235       else
4236         {
4237           error_at(location, "division by zero");
4238           mpz_set_ui(val, 0);
4239           return true;
4240         }
4241       break;
4242     case OPERATOR_LSHIFT:
4243       {
4244         unsigned long shift = mpz_get_ui(right_val);
4245         if (mpz_cmp_ui(right_val, shift) != 0)
4246           {
4247             error_at(location, "shift count overflow");
4248             mpz_set_ui(val, 0);
4249             return true;
4250           }
4251         mpz_mul_2exp(val, left_val, shift);
4252         is_shift_op = true;
4253         break;
4254       }
4255       break;
4256     case OPERATOR_RSHIFT:
4257       {
4258         unsigned long shift = mpz_get_ui(right_val);
4259         if (mpz_cmp_ui(right_val, shift) != 0)
4260           {
4261             error_at(location, "shift count overflow");
4262             mpz_set_ui(val, 0);
4263             return true;
4264           }
4265         if (mpz_cmp_ui(left_val, 0) >= 0)
4266           mpz_tdiv_q_2exp(val, left_val, shift);
4267         else
4268           mpz_fdiv_q_2exp(val, left_val, shift);
4269         is_shift_op = true;
4270         break;
4271       }
4272       break;
4273     case OPERATOR_AND:
4274       mpz_and(val, left_val, right_val);
4275       break;
4276     case OPERATOR_BITCLEAR:
4277       {
4278         mpz_t tval;
4279         mpz_init(tval);
4280         mpz_com(tval, right_val);
4281         mpz_and(val, left_val, tval);
4282         mpz_clear(tval);
4283       }
4284       break;
4285     default:
4286       gcc_unreachable();
4287     }
4288
4289   Type* type = left_type;
4290   if (!is_shift_op)
4291     {
4292       if (type == NULL)
4293         type = right_type;
4294       else if (type != right_type && right_type != NULL)
4295         {
4296           if (type->is_abstract())
4297             type = right_type;
4298           else if (!right_type->is_abstract())
4299             {
4300               // This look like a type error which should be diagnosed
4301               // elsewhere.  Don't do anything here, to avoid an
4302               // unhelpful chain of error messages.
4303               return true;
4304             }
4305         }
4306     }
4307
4308   if (type != NULL && !type->is_abstract())
4309     {
4310       // We have to check the operands too, as we have implicitly
4311       // coerced them to TYPE.
4312       if ((type != left_type
4313            && !Integer_expression::check_constant(left_val, type, location))
4314           || (!is_shift_op
4315               && type != right_type
4316               && !Integer_expression::check_constant(right_val, type,
4317                                                      location))
4318           || !Integer_expression::check_constant(val, type, location))
4319         mpz_set_ui(val, 0);
4320     }
4321
4322   return true;
4323 }
4324
4325 // Apply binary opcode OP to LEFT_VAL and RIGHT_VAL, setting VAL.
4326 // Return true if this could be done, false if not.
4327
4328 bool
4329 Binary_expression::eval_float(Operator op, Type* left_type, mpfr_t left_val,
4330                               Type* right_type, mpfr_t right_val,
4331                               mpfr_t val, source_location location)
4332 {
4333   switch (op)
4334     {
4335     case OPERATOR_OROR:
4336     case OPERATOR_ANDAND:
4337     case OPERATOR_EQEQ:
4338     case OPERATOR_NOTEQ:
4339     case OPERATOR_LT:
4340     case OPERATOR_LE:
4341     case OPERATOR_GT:
4342     case OPERATOR_GE:
4343       // These return boolean values.  We should probably handle them
4344       // anyhow in case a type conversion is used on the result.
4345       return false;
4346     case OPERATOR_PLUS:
4347       mpfr_add(val, left_val, right_val, GMP_RNDN);
4348       break;
4349     case OPERATOR_MINUS:
4350       mpfr_sub(val, left_val, right_val, GMP_RNDN);
4351       break;
4352     case OPERATOR_OR:
4353     case OPERATOR_XOR:
4354     case OPERATOR_AND:
4355     case OPERATOR_BITCLEAR:
4356       return false;
4357     case OPERATOR_MULT:
4358       mpfr_mul(val, left_val, right_val, GMP_RNDN);
4359       break;
4360     case OPERATOR_DIV:
4361       if (mpfr_zero_p(right_val))
4362         error_at(location, "division by zero");
4363       mpfr_div(val, left_val, right_val, GMP_RNDN);
4364       break;
4365     case OPERATOR_MOD:
4366       return false;
4367     case OPERATOR_LSHIFT:
4368     case OPERATOR_RSHIFT:
4369       return false;
4370     default:
4371       gcc_unreachable();
4372     }
4373
4374   Type* type = left_type;
4375   if (type == NULL)
4376     type = right_type;
4377   else if (type != right_type && right_type != NULL)
4378     {
4379       if (type->is_abstract())
4380         type = right_type;
4381       else if (!right_type->is_abstract())
4382         {
4383           // This looks like a type error which should be diagnosed
4384           // elsewhere.  Don't do anything here, to avoid an unhelpful
4385           // chain of error messages.
4386           return true;
4387         }
4388     }
4389
4390   if (type != NULL && !type->is_abstract())
4391     {
4392       if ((type != left_type
4393            && !Float_expression::check_constant(left_val, type, location))
4394           || (type != right_type
4395               && !Float_expression::check_constant(right_val, type,
4396                                                    location))
4397           || !Float_expression::check_constant(val, type, location))
4398         mpfr_set_ui(val, 0, GMP_RNDN);
4399     }
4400
4401   return true;
4402 }
4403
4404 // Apply binary opcode OP to LEFT_REAL/LEFT_IMAG and
4405 // RIGHT_REAL/RIGHT_IMAG, setting REAL/IMAG.  Return true if this
4406 // could be done, false if not.
4407
4408 bool
4409 Binary_expression::eval_complex(Operator op, Type* left_type,
4410                                 mpfr_t left_real, mpfr_t left_imag,
4411                                 Type *right_type,
4412                                 mpfr_t right_real, mpfr_t right_imag,
4413                                 mpfr_t real, mpfr_t imag,
4414                                 source_location location)
4415 {
4416   switch (op)
4417     {
4418     case OPERATOR_OROR:
4419     case OPERATOR_ANDAND:
4420     case OPERATOR_EQEQ:
4421     case OPERATOR_NOTEQ:
4422     case OPERATOR_LT:
4423     case OPERATOR_LE:
4424     case OPERATOR_GT:
4425     case OPERATOR_GE:
4426       // These return boolean values and must be handled differently.
4427       return false;
4428     case OPERATOR_PLUS:
4429       mpfr_add(real, left_real, right_real, GMP_RNDN);
4430       mpfr_add(imag, left_imag, right_imag, GMP_RNDN);
4431       break;
4432     case OPERATOR_MINUS:
4433       mpfr_sub(real, left_real, right_real, GMP_RNDN);
4434       mpfr_sub(imag, left_imag, right_imag, GMP_RNDN);
4435       break;
4436     case OPERATOR_OR:
4437     case OPERATOR_XOR:
4438     case OPERATOR_AND:
4439     case OPERATOR_BITCLEAR:
4440       return false;
4441     case OPERATOR_MULT:
4442       {
4443         // You might think that multiplying two complex numbers would
4444         // be simple, and you would be right, until you start to think
4445         // about getting the right answer for infinity.  If one
4446         // operand here is infinity and the other is anything other
4447         // than zero or NaN, then we are going to wind up subtracting
4448         // two infinity values.  That will give us a NaN, but the
4449         // correct answer is infinity.
4450
4451         mpfr_t lrrr;
4452         mpfr_init(lrrr);
4453         mpfr_mul(lrrr, left_real, right_real, GMP_RNDN);
4454
4455         mpfr_t lrri;
4456         mpfr_init(lrri);
4457         mpfr_mul(lrri, left_real, right_imag, GMP_RNDN);
4458
4459         mpfr_t lirr;
4460         mpfr_init(lirr);
4461         mpfr_mul(lirr, left_imag, right_real, GMP_RNDN);
4462
4463         mpfr_t liri;
4464         mpfr_init(liri);
4465         mpfr_mul(liri, left_imag, right_imag, GMP_RNDN);
4466
4467         mpfr_sub(real, lrrr, liri, GMP_RNDN);
4468         mpfr_add(imag, lrri, lirr, GMP_RNDN);
4469
4470         // If we get NaN on both sides, check whether it should really
4471         // be infinity.  The rule is that if either side of the
4472         // complex number is infinity, then the whole value is
4473         // infinity, even if the other side is NaN.  So the only case
4474         // we have to fix is the one in which both sides are NaN.
4475         if (mpfr_nan_p(real) && mpfr_nan_p(imag)
4476             && (!mpfr_nan_p(left_real) || !mpfr_nan_p(left_imag))
4477             && (!mpfr_nan_p(right_real) || !mpfr_nan_p(right_imag)))
4478           {
4479             bool is_infinity = false;
4480
4481             mpfr_t lr;
4482             mpfr_t li;
4483             mpfr_init_set(lr, left_real, GMP_RNDN);
4484             mpfr_init_set(li, left_imag, GMP_RNDN);
4485
4486             mpfr_t rr;
4487             mpfr_t ri;
4488             mpfr_init_set(rr, right_real, GMP_RNDN);
4489             mpfr_init_set(ri, right_imag, GMP_RNDN);
4490
4491             // If the left side is infinity, then the result is
4492             // infinity.
4493             if (mpfr_inf_p(lr) || mpfr_inf_p(li))
4494               {
4495                 mpfr_set_ui(lr, mpfr_inf_p(lr) ? 1 : 0, GMP_RNDN);
4496                 mpfr_copysign(lr, lr, left_real, GMP_RNDN);
4497                 mpfr_set_ui(li, mpfr_inf_p(li) ? 1 : 0, GMP_RNDN);
4498                 mpfr_copysign(li, li, left_imag, GMP_RNDN);
4499                 if (mpfr_nan_p(rr))
4500                   {
4501                     mpfr_set_ui(rr, 0, GMP_RNDN);
4502                     mpfr_copysign(rr, rr, right_real, GMP_RNDN);
4503                   }
4504                 if (mpfr_nan_p(ri))
4505                   {
4506                     mpfr_set_ui(ri, 0, GMP_RNDN);
4507                     mpfr_copysign(ri, ri, right_imag, GMP_RNDN);
4508                   }
4509                 is_infinity = true;
4510               }
4511
4512             // If the right side is infinity, then the result is
4513             // infinity.
4514             if (mpfr_inf_p(rr) || mpfr_inf_p(ri))
4515               {
4516                 mpfr_set_ui(rr, mpfr_inf_p(rr) ? 1 : 0, GMP_RNDN);
4517                 mpfr_copysign(rr, rr, right_real, GMP_RNDN);
4518                 mpfr_set_ui(ri, mpfr_inf_p(ri) ? 1 : 0, GMP_RNDN);
4519                 mpfr_copysign(ri, ri, right_imag, GMP_RNDN);
4520                 if (mpfr_nan_p(lr))
4521                   {
4522                     mpfr_set_ui(lr, 0, GMP_RNDN);
4523                     mpfr_copysign(lr, lr, left_real, GMP_RNDN);
4524                   }
4525                 if (mpfr_nan_p(li))
4526                   {
4527                     mpfr_set_ui(li, 0, GMP_RNDN);
4528                     mpfr_copysign(li, li, left_imag, GMP_RNDN);
4529                   }
4530                 is_infinity = true;
4531               }
4532
4533             // If we got an overflow in the intermediate computations,
4534             // then the result is infinity.
4535             if (!is_infinity
4536                 && (mpfr_inf_p(lrrr) || mpfr_inf_p(lrri)
4537                     || mpfr_inf_p(lirr) || mpfr_inf_p(liri)))
4538               {
4539                 if (mpfr_nan_p(lr))
4540                   {
4541                     mpfr_set_ui(lr, 0, GMP_RNDN);
4542                     mpfr_copysign(lr, lr, left_real, GMP_RNDN);
4543                   }
4544                 if (mpfr_nan_p(li))
4545                   {
4546                     mpfr_set_ui(li, 0, GMP_RNDN);
4547                     mpfr_copysign(li, li, left_imag, GMP_RNDN);
4548                   }
4549                 if (mpfr_nan_p(rr))
4550                   {
4551                     mpfr_set_ui(rr, 0, GMP_RNDN);
4552                     mpfr_copysign(rr, rr, right_real, GMP_RNDN);
4553                   }
4554                 if (mpfr_nan_p(ri))
4555                   {
4556                     mpfr_set_ui(ri, 0, GMP_RNDN);
4557                     mpfr_copysign(ri, ri, right_imag, GMP_RNDN);
4558                   }
4559                 is_infinity = true;
4560               }
4561
4562             if (is_infinity)
4563               {
4564                 mpfr_mul(lrrr, lr, rr, GMP_RNDN);
4565                 mpfr_mul(lrri, lr, ri, GMP_RNDN);
4566                 mpfr_mul(lirr, li, rr, GMP_RNDN);
4567                 mpfr_mul(liri, li, ri, GMP_RNDN);
4568                 mpfr_sub(real, lrrr, liri, GMP_RNDN);
4569                 mpfr_add(imag, lrri, lirr, GMP_RNDN);
4570                 mpfr_set_inf(real, mpfr_sgn(real));
4571                 mpfr_set_inf(imag, mpfr_sgn(imag));
4572               }
4573
4574             mpfr_clear(lr);
4575             mpfr_clear(li);
4576             mpfr_clear(rr);
4577             mpfr_clear(ri);
4578           }
4579
4580         mpfr_clear(lrrr);
4581         mpfr_clear(lrri);
4582         mpfr_clear(lirr);
4583         mpfr_clear(liri);
4584       }
4585       break;
4586     case OPERATOR_DIV:
4587       {
4588         // For complex division we want to avoid having an
4589         // intermediate overflow turn the whole result in a NaN.  We
4590         // scale the values to try to avoid this.
4591
4592         if (mpfr_zero_p(right_real) && mpfr_zero_p(right_imag))
4593           error_at(location, "division by zero");
4594
4595         mpfr_t rra;
4596         mpfr_t ria;
4597         mpfr_init(rra);
4598         mpfr_init(ria);
4599         mpfr_abs(rra, right_real, GMP_RNDN);
4600         mpfr_abs(ria, right_imag, GMP_RNDN);
4601         mpfr_t t;
4602         mpfr_init(t);
4603         mpfr_max(t, rra, ria, GMP_RNDN);
4604
4605         mpfr_t rr;
4606         mpfr_t ri;
4607         mpfr_init_set(rr, right_real, GMP_RNDN);
4608         mpfr_init_set(ri, right_imag, GMP_RNDN);
4609         long ilogbw = 0;
4610         if (!mpfr_inf_p(t) && !mpfr_nan_p(t) && !mpfr_zero_p(t))
4611           {
4612             ilogbw = mpfr_get_exp(t);
4613             mpfr_mul_2si(rr, rr, - ilogbw, GMP_RNDN);
4614             mpfr_mul_2si(ri, ri, - ilogbw, GMP_RNDN);
4615           }
4616
4617         mpfr_t denom;
4618         mpfr_init(denom);
4619         mpfr_mul(denom, rr, rr, GMP_RNDN);
4620         mpfr_mul(t, ri, ri, GMP_RNDN);
4621         mpfr_add(denom, denom, t, GMP_RNDN);
4622
4623         mpfr_mul(real, left_real, rr, GMP_RNDN);
4624         mpfr_mul(t, left_imag, ri, GMP_RNDN);
4625         mpfr_add(real, real, t, GMP_RNDN);
4626         mpfr_div(real, real, denom, GMP_RNDN);
4627         mpfr_mul_2si(real, real, - ilogbw, GMP_RNDN);
4628
4629         mpfr_mul(imag, left_imag, rr, GMP_RNDN);
4630         mpfr_mul(t, left_real, ri, GMP_RNDN);
4631         mpfr_sub(imag, imag, t, GMP_RNDN);
4632         mpfr_div(imag, imag, denom, GMP_RNDN);
4633         mpfr_mul_2si(imag, imag, - ilogbw, GMP_RNDN);
4634
4635         // If we wind up with NaN on both sides, check whether we
4636         // should really have infinity.  The rule is that if either
4637         // side of the complex number is infinity, then the whole
4638         // value is infinity, even if the other side is NaN.  So the
4639         // only case we have to fix is the one in which both sides are
4640         // NaN.
4641         if (mpfr_nan_p(real) && mpfr_nan_p(imag)
4642             && (!mpfr_nan_p(left_real) || !mpfr_nan_p(left_imag))
4643             && (!mpfr_nan_p(right_real) || !mpfr_nan_p(right_imag)))
4644           {
4645             if (mpfr_zero_p(denom))
4646               {
4647                 mpfr_set_inf(real, mpfr_sgn(rr));
4648                 mpfr_mul(real, real, left_real, GMP_RNDN);
4649                 mpfr_set_inf(imag, mpfr_sgn(rr));
4650                 mpfr_mul(imag, imag, left_imag, GMP_RNDN);
4651               }
4652             else if ((mpfr_inf_p(left_real) || mpfr_inf_p(left_imag))
4653                      && mpfr_number_p(rr) && mpfr_number_p(ri))
4654               {
4655                 mpfr_set_ui(t, mpfr_inf_p(left_real) ? 1 : 0, GMP_RNDN);
4656                 mpfr_copysign(t, t, left_real, GMP_RNDN);
4657
4658                 mpfr_t t2;
4659                 mpfr_init_set_ui(t2, mpfr_inf_p(left_imag) ? 1 : 0, GMP_RNDN);
4660                 mpfr_copysign(t2, t2, left_imag, GMP_RNDN);
4661
4662                 mpfr_t t3;
4663                 mpfr_init(t3);
4664                 mpfr_mul(t3, t, rr, GMP_RNDN);
4665
4666                 mpfr_t t4;
4667                 mpfr_init(t4);
4668                 mpfr_mul(t4, t2, ri, GMP_RNDN);
4669
4670                 mpfr_add(t3, t3, t4, GMP_RNDN);
4671                 mpfr_set_inf(real, mpfr_sgn(t3));
4672
4673                 mpfr_mul(t3, t2, rr, GMP_RNDN);
4674                 mpfr_mul(t4, t, ri, GMP_RNDN);
4675                 mpfr_sub(t3, t3, t4, GMP_RNDN);
4676                 mpfr_set_inf(imag, mpfr_sgn(t3));
4677
4678                 mpfr_clear(t2);
4679                 mpfr_clear(t3);
4680                 mpfr_clear(t4);
4681               }
4682             else if ((mpfr_inf_p(right_real) || mpfr_inf_p(right_imag))
4683                      && mpfr_number_p(left_real) && mpfr_number_p(left_imag))
4684               {
4685                 mpfr_set_ui(t, mpfr_inf_p(rr) ? 1 : 0, GMP_RNDN);
4686                 mpfr_copysign(t, t, rr, GMP_RNDN);
4687
4688                 mpfr_t t2;
4689                 mpfr_init_set_ui(t2, mpfr_inf_p(ri) ? 1 : 0, GMP_RNDN);
4690                 mpfr_copysign(t2, t2, ri, GMP_RNDN);
4691
4692                 mpfr_t t3;
4693                 mpfr_init(t3);
4694                 mpfr_mul(t3, left_real, t, GMP_RNDN);
4695
4696                 mpfr_t t4;
4697                 mpfr_init(t4);
4698                 mpfr_mul(t4, left_imag, t2, GMP_RNDN);
4699
4700                 mpfr_add(t3, t3, t4, GMP_RNDN);
4701                 mpfr_set_ui(real, 0, GMP_RNDN);
4702                 mpfr_mul(real, real, t3, GMP_RNDN);
4703
4704                 mpfr_mul(t3, left_imag, t, GMP_RNDN);
4705                 mpfr_mul(t4, left_real, t2, GMP_RNDN);
4706                 mpfr_sub(t3, t3, t4, GMP_RNDN);
4707                 mpfr_set_ui(imag, 0, GMP_RNDN);
4708                 mpfr_mul(imag, imag, t3, GMP_RNDN);
4709
4710                 mpfr_clear(t2);
4711                 mpfr_clear(t3);
4712                 mpfr_clear(t4);
4713               }
4714           }
4715
4716         mpfr_clear(denom);
4717         mpfr_clear(rr);
4718         mpfr_clear(ri);
4719         mpfr_clear(t);
4720         mpfr_clear(rra);
4721         mpfr_clear(ria);
4722       }
4723       break;
4724     case OPERATOR_MOD:
4725       return false;
4726     case OPERATOR_LSHIFT:
4727     case OPERATOR_RSHIFT:
4728       return false;
4729     default:
4730       gcc_unreachable();
4731     }
4732
4733   Type* type = left_type;
4734   if (type == NULL)
4735     type = right_type;
4736   else if (type != right_type && right_type != NULL)
4737     {
4738       if (type->is_abstract())
4739         type = right_type;
4740       else if (!right_type->is_abstract())
4741         {
4742           // This looks like a type error which should be diagnosed
4743           // elsewhere.  Don't do anything here, to avoid an unhelpful
4744           // chain of error messages.
4745           return true;
4746         }
4747     }
4748
4749   if (type != NULL && !type->is_abstract())
4750     {
4751       if ((type != left_type
4752            && !Complex_expression::check_constant(left_real, left_imag,
4753                                                   type, location))
4754           || (type != right_type
4755               && !Complex_expression::check_constant(right_real, right_imag,
4756                                                      type, location))
4757           || !Complex_expression::check_constant(real, imag, type,
4758                                                  location))
4759         {
4760           mpfr_set_ui(real, 0, GMP_RNDN);
4761           mpfr_set_ui(imag, 0, GMP_RNDN);
4762         }
4763     }
4764
4765   return true;
4766 }
4767
4768 // Lower a binary expression.  We have to evaluate constant
4769 // expressions now, in order to implement Go's unlimited precision
4770 // constants.
4771
4772 Expression*
4773 Binary_expression::do_lower(Gogo*, Named_object*, int)
4774 {
4775   source_location location = this->location();
4776   Operator op = this->op_;
4777   Expression* left = this->left_;
4778   Expression* right = this->right_;
4779
4780   const bool is_comparison = (op == OPERATOR_EQEQ
4781                               || op == OPERATOR_NOTEQ
4782                               || op == OPERATOR_LT
4783                               || op == OPERATOR_LE
4784                               || op == OPERATOR_GT
4785                               || op == OPERATOR_GE);
4786
4787   // Integer constant expressions.
4788   {
4789     mpz_t left_val;
4790     mpz_init(left_val);
4791     Type* left_type;
4792     mpz_t right_val;
4793     mpz_init(right_val);
4794     Type* right_type;
4795     if (left->integer_constant_value(false, left_val, &left_type)
4796         && right->integer_constant_value(false, right_val, &right_type))
4797       {
4798         Expression* ret = NULL;
4799         if (left_type != right_type
4800             && left_type != NULL
4801             && right_type != NULL
4802             && left_type->base() != right_type->base()
4803             && op != OPERATOR_LSHIFT
4804             && op != OPERATOR_RSHIFT)
4805           {
4806             // May be a type error--let it be diagnosed later.
4807           }
4808         else if (is_comparison)
4809           {
4810             bool b = Binary_expression::compare_integer(op, left_val,
4811                                                         right_val);
4812             ret = Expression::make_cast(Type::lookup_bool_type(),
4813                                         Expression::make_boolean(b, location),
4814                                         location);
4815           }
4816         else
4817           {
4818             mpz_t val;
4819             mpz_init(val);
4820
4821             if (Binary_expression::eval_integer(op, left_type, left_val,
4822                                                 right_type, right_val,
4823                                                 location, val))
4824               {
4825                 gcc_assert(op != OPERATOR_OROR && op != OPERATOR_ANDAND);
4826                 Type* type;
4827                 if (op == OPERATOR_LSHIFT || op == OPERATOR_RSHIFT)
4828                   type = left_type;
4829                 else if (left_type == NULL)
4830                   type = right_type;
4831                 else if (right_type == NULL)
4832                   type = left_type;
4833                 else if (!left_type->is_abstract()
4834                          && left_type->named_type() != NULL)
4835                   type = left_type;
4836                 else if (!right_type->is_abstract()
4837                          && right_type->named_type() != NULL)
4838                   type = right_type;
4839                 else if (!left_type->is_abstract())
4840                   type = left_type;
4841                 else if (!right_type->is_abstract())
4842                   type = right_type;
4843                 else if (left_type->float_type() != NULL)
4844                   type = left_type;
4845                 else if (right_type->float_type() != NULL)
4846                   type = right_type;
4847                 else if (left_type->complex_type() != NULL)
4848                   type = left_type;
4849                 else if (right_type->complex_type() != NULL)
4850                   type = right_type;
4851                 else
4852                   type = left_type;
4853                 ret = Expression::make_integer(&val, type, location);
4854               }
4855
4856             mpz_clear(val);
4857           }
4858
4859         if (ret != NULL)
4860           {
4861             mpz_clear(right_val);
4862             mpz_clear(left_val);
4863             return ret;
4864           }
4865       }
4866     mpz_clear(right_val);
4867     mpz_clear(left_val);
4868   }
4869
4870   // Floating point constant expressions.
4871   {
4872     mpfr_t left_val;
4873     mpfr_init(left_val);
4874     Type* left_type;
4875     mpfr_t right_val;
4876     mpfr_init(right_val);
4877     Type* right_type;
4878     if (left->float_constant_value(left_val, &left_type)
4879         && right->float_constant_value(right_val, &right_type))
4880       {
4881         Expression* ret = NULL;
4882         if (left_type != right_type
4883             && left_type != NULL
4884             && right_type != NULL
4885             && left_type->base() != right_type->base()
4886             && op != OPERATOR_LSHIFT
4887             && op != OPERATOR_RSHIFT)
4888           {
4889             // May be a type error--let it be diagnosed later.
4890           }
4891         else if (is_comparison)
4892           {
4893             bool b = Binary_expression::compare_float(op,
4894                                                       (left_type != NULL
4895                                                        ? left_type
4896                                                        : right_type),
4897                                                       left_val, right_val);
4898             ret = Expression::make_boolean(b, location);
4899           }
4900         else
4901           {
4902             mpfr_t val;
4903             mpfr_init(val);
4904
4905             if (Binary_expression::eval_float(op, left_type, left_val,
4906                                               right_type, right_val, val,
4907                                               location))
4908               {
4909                 gcc_assert(op != OPERATOR_OROR && op != OPERATOR_ANDAND
4910                            && op != OPERATOR_LSHIFT && op != OPERATOR_RSHIFT);
4911                 Type* type;
4912                 if (left_type == NULL)
4913                   type = right_type;
4914                 else if (right_type == NULL)
4915                   type = left_type;
4916                 else if (!left_type->is_abstract()
4917                          && left_type->named_type() != NULL)
4918                   type = left_type;
4919                 else if (!right_type->is_abstract()
4920                          && right_type->named_type() != NULL)
4921                   type = right_type;
4922                 else if (!left_type->is_abstract())
4923                   type = left_type;
4924                 else if (!right_type->is_abstract())
4925                   type = right_type;
4926                 else if (left_type->float_type() != NULL)
4927                   type = left_type;
4928                 else if (right_type->float_type() != NULL)
4929                   type = right_type;
4930                 else
4931                   type = left_type;
4932                 ret = Expression::make_float(&val, type, location);
4933               }
4934
4935             mpfr_clear(val);
4936           }
4937
4938         if (ret != NULL)
4939           {
4940             mpfr_clear(right_val);
4941             mpfr_clear(left_val);
4942             return ret;
4943           }
4944       }
4945     mpfr_clear(right_val);
4946     mpfr_clear(left_val);
4947   }
4948
4949   // Complex constant expressions.
4950   {
4951     mpfr_t left_real;
4952     mpfr_t left_imag;
4953     mpfr_init(left_real);
4954     mpfr_init(left_imag);
4955     Type* left_type;
4956
4957     mpfr_t right_real;
4958     mpfr_t right_imag;
4959     mpfr_init(right_real);
4960     mpfr_init(right_imag);
4961     Type* right_type;
4962
4963     if (left->complex_constant_value(left_real, left_imag, &left_type)
4964         && right->complex_constant_value(right_real, right_imag, &right_type))
4965       {
4966         Expression* ret = NULL;
4967         if (left_type != right_type
4968             && left_type != NULL
4969             && right_type != NULL
4970             && left_type->base() != right_type->base())
4971           {
4972             // May be a type error--let it be diagnosed later.
4973           }
4974         else if (is_comparison)
4975           {
4976             bool b = Binary_expression::compare_complex(op,
4977                                                         (left_type != NULL
4978                                                          ? left_type
4979                                                          : right_type),
4980                                                         left_real,
4981                                                         left_imag,
4982                                                         right_real,
4983                                                         right_imag);
4984             ret = Expression::make_boolean(b, location);
4985           }
4986         else
4987           {
4988             mpfr_t real;
4989             mpfr_t imag;
4990             mpfr_init(real);
4991             mpfr_init(imag);
4992
4993             if (Binary_expression::eval_complex(op, left_type,
4994                                                 left_real, left_imag,
4995                                                 right_type,
4996                                                 right_real, right_imag,
4997                                                 real, imag,
4998                                                 location))
4999               {
5000                 gcc_assert(op != OPERATOR_OROR && op != OPERATOR_ANDAND
5001                            && op != OPERATOR_LSHIFT && op != OPERATOR_RSHIFT);
5002                 Type* type;
5003                 if (left_type == NULL)
5004                   type = right_type;
5005                 else if (right_type == NULL)
5006                   type = left_type;
5007                 else if (!left_type->is_abstract()
5008                          && left_type->named_type() != NULL)
5009                   type = left_type;
5010                 else if (!right_type->is_abstract()
5011                          && right_type->named_type() != NULL)
5012                   type = right_type;
5013                 else if (!left_type->is_abstract())
5014                   type = left_type;
5015                 else if (!right_type->is_abstract())
5016                   type = right_type;
5017                 else if (left_type->complex_type() != NULL)
5018                   type = left_type;
5019                 else if (right_type->complex_type() != NULL)
5020                   type = right_type;
5021                 else
5022                   type = left_type;
5023                 ret = Expression::make_complex(&real, &imag, type,
5024                                                location);
5025               }
5026             mpfr_clear(real);
5027             mpfr_clear(imag);
5028           }
5029
5030         if (ret != NULL)
5031           {
5032             mpfr_clear(left_real);
5033             mpfr_clear(left_imag);
5034             mpfr_clear(right_real);
5035             mpfr_clear(right_imag);
5036             return ret;
5037           }
5038       }
5039
5040     mpfr_clear(left_real);
5041     mpfr_clear(left_imag);
5042     mpfr_clear(right_real);
5043     mpfr_clear(right_imag);
5044   }
5045
5046   // String constant expressions.
5047   if (op == OPERATOR_PLUS
5048       && left->type()->is_string_type()
5049       && right->type()->is_string_type())
5050     {
5051       std::string left_string;
5052       std::string right_string;
5053       if (left->string_constant_value(&left_string)
5054           && right->string_constant_value(&right_string))
5055         return Expression::make_string(left_string + right_string, location);
5056     }
5057
5058   return this;
5059 }
5060
5061 // Return the integer constant value, if it has one.
5062
5063 bool
5064 Binary_expression::do_integer_constant_value(bool iota_is_constant, mpz_t val,
5065                                              Type** ptype) const
5066 {
5067   mpz_t left_val;
5068   mpz_init(left_val);
5069   Type* left_type;
5070   if (!this->left_->integer_constant_value(iota_is_constant, left_val,
5071                                            &left_type))
5072     {
5073       mpz_clear(left_val);
5074       return false;
5075     }
5076
5077   mpz_t right_val;
5078   mpz_init(right_val);
5079   Type* right_type;
5080   if (!this->right_->integer_constant_value(iota_is_constant, right_val,
5081                                             &right_type))
5082     {
5083       mpz_clear(right_val);
5084       mpz_clear(left_val);
5085       return false;
5086     }
5087
5088   bool ret;
5089   if (left_type != right_type
5090       && left_type != NULL
5091       && right_type != NULL
5092       && left_type->base() != right_type->base()
5093       && this->op_ != OPERATOR_RSHIFT
5094       && this->op_ != OPERATOR_LSHIFT)
5095     ret = false;
5096   else
5097     ret = Binary_expression::eval_integer(this->op_, left_type, left_val,
5098                                           right_type, right_val,
5099                                           this->location(), val);
5100
5101   mpz_clear(right_val);
5102   mpz_clear(left_val);
5103
5104   if (ret)
5105     *ptype = left_type;
5106
5107   return ret;
5108 }
5109
5110 // Return the floating point constant value, if it has one.
5111
5112 bool
5113 Binary_expression::do_float_constant_value(mpfr_t val, Type** ptype) const
5114 {
5115   mpfr_t left_val;
5116   mpfr_init(left_val);
5117   Type* left_type;
5118   if (!this->left_->float_constant_value(left_val, &left_type))
5119     {
5120       mpfr_clear(left_val);
5121       return false;
5122     }
5123
5124   mpfr_t right_val;
5125   mpfr_init(right_val);
5126   Type* right_type;
5127   if (!this->right_->float_constant_value(right_val, &right_type))
5128     {
5129       mpfr_clear(right_val);
5130       mpfr_clear(left_val);
5131       return false;
5132     }
5133
5134   bool ret;
5135   if (left_type != right_type
5136       && left_type != NULL
5137       && right_type != NULL
5138       && left_type->base() != right_type->base())
5139     ret = false;
5140   else
5141     ret = Binary_expression::eval_float(this->op_, left_type, left_val,
5142                                         right_type, right_val,
5143                                         val, this->location());
5144
5145   mpfr_clear(left_val);
5146   mpfr_clear(right_val);
5147
5148   if (ret)
5149     *ptype = left_type;
5150
5151   return ret;
5152 }
5153
5154 // Return the complex constant value, if it has one.
5155
5156 bool
5157 Binary_expression::do_complex_constant_value(mpfr_t real, mpfr_t imag,
5158                                              Type** ptype) const
5159 {
5160   mpfr_t left_real;
5161   mpfr_t left_imag;
5162   mpfr_init(left_real);
5163   mpfr_init(left_imag);
5164   Type* left_type;
5165   if (!this->left_->complex_constant_value(left_real, left_imag, &left_type))
5166     {
5167       mpfr_clear(left_real);
5168       mpfr_clear(left_imag);
5169       return false;
5170     }
5171
5172   mpfr_t right_real;
5173   mpfr_t right_imag;
5174   mpfr_init(right_real);
5175   mpfr_init(right_imag);
5176   Type* right_type;
5177   if (!this->right_->complex_constant_value(right_real, right_imag,
5178                                             &right_type))
5179     {
5180       mpfr_clear(left_real);
5181       mpfr_clear(left_imag);
5182       mpfr_clear(right_real);
5183       mpfr_clear(right_imag);
5184       return false;
5185     }
5186
5187   bool ret;
5188   if (left_type != right_type
5189       && left_type != NULL
5190       && right_type != NULL
5191       && left_type->base() != right_type->base())
5192     ret = false;
5193   else
5194     ret = Binary_expression::eval_complex(this->op_, left_type,
5195                                           left_real, left_imag,
5196                                           right_type,
5197                                           right_real, right_imag,
5198                                           real, imag,
5199                                           this->location());
5200   mpfr_clear(left_real);
5201   mpfr_clear(left_imag);
5202   mpfr_clear(right_real);
5203   mpfr_clear(right_imag);
5204
5205   if (ret)
5206     *ptype = left_type;
5207
5208   return ret;
5209 }
5210
5211 // Note that the value is being discarded.
5212
5213 void
5214 Binary_expression::do_discarding_value()
5215 {
5216   if (this->op_ == OPERATOR_OROR || this->op_ == OPERATOR_ANDAND)
5217     this->right_->discarding_value();
5218   else
5219     this->warn_about_unused_value();
5220 }
5221
5222 // Get type.
5223
5224 Type*
5225 Binary_expression::do_type()
5226 {
5227   switch (this->op_)
5228     {
5229     case OPERATOR_OROR:
5230     case OPERATOR_ANDAND:
5231     case OPERATOR_EQEQ:
5232     case OPERATOR_NOTEQ:
5233     case OPERATOR_LT:
5234     case OPERATOR_LE:
5235     case OPERATOR_GT:
5236     case OPERATOR_GE:
5237       return Type::lookup_bool_type();
5238
5239     case OPERATOR_PLUS:
5240     case OPERATOR_MINUS:
5241     case OPERATOR_OR:
5242     case OPERATOR_XOR:
5243     case OPERATOR_MULT:
5244     case OPERATOR_DIV:
5245     case OPERATOR_MOD:
5246     case OPERATOR_AND:
5247     case OPERATOR_BITCLEAR:
5248       {
5249         Type* left_type = this->left_->type();
5250         Type* right_type = this->right_->type();
5251         if (!left_type->is_abstract() && left_type->named_type() != NULL)
5252           return left_type;
5253         else if (!right_type->is_abstract() && right_type->named_type() != NULL)
5254           return right_type;
5255         else if (!left_type->is_abstract())
5256           return left_type;
5257         else if (!right_type->is_abstract())
5258           return right_type;
5259         else if (left_type->complex_type() != NULL)
5260           return left_type;
5261         else if (right_type->complex_type() != NULL)
5262           return right_type;
5263         else if (left_type->float_type() != NULL)
5264           return left_type;
5265         else if (right_type->float_type() != NULL)
5266           return right_type;
5267         else
5268           return left_type;
5269       }
5270
5271     case OPERATOR_LSHIFT:
5272     case OPERATOR_RSHIFT:
5273       return this->left_->type();
5274
5275     default:
5276       gcc_unreachable();
5277     }
5278 }
5279
5280 // Set type for a binary expression.
5281
5282 void
5283 Binary_expression::do_determine_type(const Type_context* context)
5284 {
5285   Type* tleft = this->left_->type();
5286   Type* tright = this->right_->type();
5287
5288   // Both sides should have the same type, except for the shift
5289   // operations.  For a comparison, we should ignore the incoming
5290   // type.
5291
5292   bool is_shift_op = (this->op_ == OPERATOR_LSHIFT
5293                       || this->op_ == OPERATOR_RSHIFT);
5294
5295   bool is_comparison = (this->op_ == OPERATOR_EQEQ
5296                         || this->op_ == OPERATOR_NOTEQ
5297                         || this->op_ == OPERATOR_LT
5298                         || this->op_ == OPERATOR_LE
5299                         || this->op_ == OPERATOR_GT
5300                         || this->op_ == OPERATOR_GE);
5301
5302   Type_context subcontext(*context);
5303
5304   if (is_comparison)
5305     {
5306       // In a comparison, the context does not determine the types of
5307       // the operands.
5308       subcontext.type = NULL;
5309     }
5310
5311   // Set the context for the left hand operand.
5312   if (is_shift_op)
5313     {
5314       // The right hand operand plays no role in determining the type
5315       // of the left hand operand.  A shift of an abstract integer in
5316       // a string context gets special treatment, which may be a
5317       // language bug.
5318       if (subcontext.type != NULL
5319           && subcontext.type->is_string_type()
5320           && tleft->is_abstract())
5321         error_at(this->location(), "shift of non-integer operand");
5322     }
5323   else if (!tleft->is_abstract())
5324     subcontext.type = tleft;
5325   else if (!tright->is_abstract())
5326     subcontext.type = tright;
5327   else if (subcontext.type == NULL)
5328     {
5329       if ((tleft->integer_type() != NULL && tright->integer_type() != NULL)
5330           || (tleft->float_type() != NULL && tright->float_type() != NULL)
5331           || (tleft->complex_type() != NULL && tright->complex_type() != NULL))
5332         {
5333           // Both sides have an abstract integer, abstract float, or
5334           // abstract complex type.  Just let CONTEXT determine
5335           // whether they may remain abstract or not.
5336         }
5337       else if (tleft->complex_type() != NULL)
5338         subcontext.type = tleft;
5339       else if (tright->complex_type() != NULL)
5340         subcontext.type = tright;
5341       else if (tleft->float_type() != NULL)
5342         subcontext.type = tleft;
5343       else if (tright->float_type() != NULL)
5344         subcontext.type = tright;
5345       else
5346         subcontext.type = tleft;
5347     }
5348
5349   this->left_->determine_type(&subcontext);
5350
5351   // The context for the right hand operand is the same as for the
5352   // left hand operand, except for a shift operator.
5353   if (is_shift_op)
5354     {
5355       subcontext.type = Type::lookup_integer_type("uint");
5356       subcontext.may_be_abstract = false;
5357     }
5358
5359   this->right_->determine_type(&subcontext);
5360 }
5361
5362 // Report an error if the binary operator OP does not support TYPE.
5363 // Return whether the operation is OK.  This should not be used for
5364 // shift.
5365
5366 bool
5367 Binary_expression::check_operator_type(Operator op, Type* type,
5368                                        source_location location)
5369 {
5370   switch (op)
5371     {
5372     case OPERATOR_OROR:
5373     case OPERATOR_ANDAND:
5374       if (!type->is_boolean_type())
5375         {
5376           error_at(location, "expected boolean type");
5377           return false;
5378         }
5379       break;
5380
5381     case OPERATOR_EQEQ:
5382     case OPERATOR_NOTEQ:
5383       if (type->integer_type() == NULL
5384           && type->float_type() == NULL
5385           && type->complex_type() == NULL
5386           && !type->is_string_type()
5387           && type->points_to() == NULL
5388           && !type->is_nil_type()
5389           && !type->is_boolean_type()
5390           && type->interface_type() == NULL
5391           && (type->array_type() == NULL
5392               || type->array_type()->length() != NULL)
5393           && type->map_type() == NULL
5394           && type->channel_type() == NULL
5395           && type->function_type() == NULL)
5396         {
5397           error_at(location,
5398                    ("expected integer, floating, complex, string, pointer, "
5399                     "boolean, interface, slice, map, channel, "
5400                     "or function type"));
5401           return false;
5402         }
5403       break;
5404
5405     case OPERATOR_LT:
5406     case OPERATOR_LE:
5407     case OPERATOR_GT:
5408     case OPERATOR_GE:
5409       if (type->integer_type() == NULL
5410           && type->float_type() == NULL
5411           && !type->is_string_type())
5412         {
5413           error_at(location, "expected integer, floating, or string type");
5414           return false;
5415         }
5416       break;
5417
5418     case OPERATOR_PLUS:
5419     case OPERATOR_PLUSEQ:
5420       if (type->integer_type() == NULL
5421           && type->float_type() == NULL
5422           && type->complex_type() == NULL
5423           && !type->is_string_type())
5424         {
5425           error_at(location,
5426                    "expected integer, floating, complex, or string type");
5427           return false;
5428         }
5429       break;
5430
5431     case OPERATOR_MINUS:
5432     case OPERATOR_MINUSEQ:
5433     case OPERATOR_MULT:
5434     case OPERATOR_MULTEQ:
5435     case OPERATOR_DIV:
5436     case OPERATOR_DIVEQ:
5437       if (type->integer_type() == NULL
5438           && type->float_type() == NULL
5439           && type->complex_type() == NULL)
5440         {
5441           error_at(location, "expected integer, floating, or complex type");
5442           return false;
5443         }
5444       break;
5445
5446     case OPERATOR_MOD:
5447     case OPERATOR_MODEQ:
5448     case OPERATOR_OR:
5449     case OPERATOR_OREQ:
5450     case OPERATOR_AND:
5451     case OPERATOR_ANDEQ:
5452     case OPERATOR_XOR:
5453     case OPERATOR_XOREQ:
5454     case OPERATOR_BITCLEAR:
5455     case OPERATOR_BITCLEAREQ:
5456       if (type->integer_type() == NULL)
5457         {
5458           error_at(location, "expected integer type");
5459           return false;
5460         }
5461       break;
5462
5463     default:
5464       gcc_unreachable();
5465     }
5466
5467   return true;
5468 }
5469
5470 // Check types.
5471
5472 void
5473 Binary_expression::do_check_types(Gogo*)
5474 {
5475   Type* left_type = this->left_->type();
5476   Type* right_type = this->right_->type();
5477   if (left_type->is_error_type() || right_type->is_error_type())
5478     {
5479       this->set_is_error();
5480       return;
5481     }
5482
5483   if (this->op_ == OPERATOR_EQEQ
5484       || this->op_ == OPERATOR_NOTEQ
5485       || this->op_ == OPERATOR_LT
5486       || this->op_ == OPERATOR_LE
5487       || this->op_ == OPERATOR_GT
5488       || this->op_ == OPERATOR_GE)
5489     {
5490       if (!Type::are_assignable(left_type, right_type, NULL)
5491           && !Type::are_assignable(right_type, left_type, NULL))
5492         {
5493           this->report_error(_("incompatible types in binary expression"));
5494           return;
5495         }
5496       if (!Binary_expression::check_operator_type(this->op_, left_type,
5497                                                   this->location())
5498           || !Binary_expression::check_operator_type(this->op_, right_type,
5499                                                      this->location()))
5500         {
5501           this->set_is_error();
5502           return;
5503         }
5504     }
5505   else if (this->op_ != OPERATOR_LSHIFT && this->op_ != OPERATOR_RSHIFT)
5506     {
5507       if (!Type::are_compatible_for_binop(left_type, right_type))
5508         {
5509           this->report_error(_("incompatible types in binary expression"));
5510           return;
5511         }
5512       if (!Binary_expression::check_operator_type(this->op_, left_type,
5513                                                   this->location()))
5514         {
5515           this->set_is_error();
5516           return;
5517         }
5518     }
5519   else
5520     {
5521       if (left_type->integer_type() == NULL)
5522         this->report_error(_("shift of non-integer operand"));
5523
5524       if (!right_type->is_abstract()
5525           && (right_type->integer_type() == NULL
5526               || !right_type->integer_type()->is_unsigned()))
5527         this->report_error(_("shift count not unsigned integer"));
5528       else
5529         {
5530           mpz_t val;
5531           mpz_init(val);
5532           Type* type;
5533           if (this->right_->integer_constant_value(true, val, &type))
5534             {
5535               if (mpz_sgn(val) < 0)
5536                 this->report_error(_("negative shift count"));
5537             }
5538           mpz_clear(val);
5539         }
5540     }
5541 }
5542
5543 // Get a tree for a binary expression.
5544
5545 tree
5546 Binary_expression::do_get_tree(Translate_context* context)
5547 {
5548   tree left = this->left_->get_tree(context);
5549   tree right = this->right_->get_tree(context);
5550
5551   if (left == error_mark_node || right == error_mark_node)
5552     return error_mark_node;
5553
5554   enum tree_code code;
5555   bool use_left_type = true;
5556   bool is_shift_op = false;
5557   switch (this->op_)
5558     {
5559     case OPERATOR_EQEQ:
5560     case OPERATOR_NOTEQ:
5561     case OPERATOR_LT:
5562     case OPERATOR_LE:
5563     case OPERATOR_GT:
5564     case OPERATOR_GE:
5565       return Expression::comparison_tree(context, this->op_,
5566                                          this->left_->type(), left,
5567                                          this->right_->type(), right,
5568                                          this->location());
5569
5570     case OPERATOR_OROR:
5571       code = TRUTH_ORIF_EXPR;
5572       use_left_type = false;
5573       break;
5574     case OPERATOR_ANDAND:
5575       code = TRUTH_ANDIF_EXPR;
5576       use_left_type = false;
5577       break;
5578     case OPERATOR_PLUS:
5579       code = PLUS_EXPR;
5580       break;
5581     case OPERATOR_MINUS:
5582       code = MINUS_EXPR;
5583       break;
5584     case OPERATOR_OR:
5585       code = BIT_IOR_EXPR;
5586       break;
5587     case OPERATOR_XOR:
5588       code = BIT_XOR_EXPR;
5589       break;
5590     case OPERATOR_MULT:
5591       code = MULT_EXPR;
5592       break;
5593     case OPERATOR_DIV:
5594       {
5595         Type *t = this->left_->type();
5596         if (t->float_type() != NULL || t->complex_type() != NULL)
5597           code = RDIV_EXPR;
5598         else
5599           code = TRUNC_DIV_EXPR;
5600       }
5601       break;
5602     case OPERATOR_MOD:
5603       code = TRUNC_MOD_EXPR;
5604       break;
5605     case OPERATOR_LSHIFT:
5606       code = LSHIFT_EXPR;
5607       is_shift_op = true;
5608       break;
5609     case OPERATOR_RSHIFT:
5610       code = RSHIFT_EXPR;
5611       is_shift_op = true;
5612       break;
5613     case OPERATOR_AND:
5614       code = BIT_AND_EXPR;
5615       break;
5616     case OPERATOR_BITCLEAR:
5617       right = fold_build1(BIT_NOT_EXPR, TREE_TYPE(right), right);
5618       code = BIT_AND_EXPR;
5619       break;
5620     default:
5621       gcc_unreachable();
5622     }
5623
5624   tree type = use_left_type ? TREE_TYPE(left) : TREE_TYPE(right);
5625
5626   if (this->left_->type()->is_string_type())
5627     {
5628       gcc_assert(this->op_ == OPERATOR_PLUS);
5629       tree string_type = Type::make_string_type()->get_tree(context->gogo());
5630       static tree string_plus_decl;
5631       return Gogo::call_builtin(&string_plus_decl,
5632                                 this->location(),
5633                                 "__go_string_plus",
5634                                 2,
5635                                 string_type,
5636                                 string_type,
5637                                 left,
5638                                 string_type,
5639                                 right);
5640     }
5641
5642   tree compute_type = excess_precision_type(type);
5643   if (compute_type != NULL_TREE)
5644     {
5645       left = ::convert(compute_type, left);
5646       right = ::convert(compute_type, right);
5647     }
5648
5649   tree eval_saved = NULL_TREE;
5650   if (is_shift_op)
5651     {
5652       if (!DECL_P(left))
5653         left = save_expr(left);
5654       if (!DECL_P(right))
5655         right = save_expr(right);
5656       // Make sure the values are evaluated.
5657       eval_saved = fold_build2_loc(this->location(), COMPOUND_EXPR,
5658                                    void_type_node, left, right);
5659     }
5660
5661   tree ret = fold_build2_loc(this->location(),
5662                              code,
5663                              compute_type != NULL_TREE ? compute_type : type,
5664                              left, right);
5665
5666   if (compute_type != NULL_TREE)
5667     ret = ::convert(type, ret);
5668
5669   // In Go, a shift larger than the size of the type is well-defined.
5670   // This is not true in GENERIC, so we need to insert a conditional.
5671   if (is_shift_op)
5672     {
5673       gcc_assert(INTEGRAL_TYPE_P(TREE_TYPE(left)));
5674       gcc_assert(this->left_->type()->integer_type() != NULL);
5675       int bits = TYPE_PRECISION(TREE_TYPE(left));
5676
5677       tree compare = fold_build2(LT_EXPR, boolean_type_node, right,
5678                                  build_int_cst_type(TREE_TYPE(right), bits));
5679
5680       tree overflow_result = fold_convert_loc(this->location(),
5681                                               TREE_TYPE(left),
5682                                               integer_zero_node);
5683       if (this->op_ == OPERATOR_RSHIFT
5684           && !this->left_->type()->integer_type()->is_unsigned())
5685         {
5686           tree neg = fold_build2_loc(this->location(), LT_EXPR,
5687                                      boolean_type_node, left,
5688                                      fold_convert_loc(this->location(),
5689                                                       TREE_TYPE(left),
5690                                                       integer_zero_node));
5691           tree neg_one = fold_build2_loc(this->location(),
5692                                          MINUS_EXPR, TREE_TYPE(left),
5693                                          fold_convert_loc(this->location(),
5694                                                           TREE_TYPE(left),
5695                                                           integer_zero_node),
5696                                          fold_convert_loc(this->location(),
5697                                                           TREE_TYPE(left),
5698                                                           integer_one_node));
5699           overflow_result = fold_build3_loc(this->location(), COND_EXPR,
5700                                             TREE_TYPE(left), neg, neg_one,
5701                                             overflow_result);
5702         }
5703
5704       ret = fold_build3_loc(this->location(), COND_EXPR, TREE_TYPE(left),
5705                             compare, ret, overflow_result);
5706
5707       ret = fold_build2_loc(this->location(), COMPOUND_EXPR,
5708                             TREE_TYPE(ret), eval_saved, ret);
5709     }
5710
5711   return ret;
5712 }
5713
5714 // Export a binary expression.
5715
5716 void
5717 Binary_expression::do_export(Export* exp) const
5718 {
5719   exp->write_c_string("(");
5720   this->left_->export_expression(exp);
5721   switch (this->op_)
5722     {
5723     case OPERATOR_OROR:
5724       exp->write_c_string(" || ");
5725       break;
5726     case OPERATOR_ANDAND:
5727       exp->write_c_string(" && ");
5728       break;
5729     case OPERATOR_EQEQ:
5730       exp->write_c_string(" == ");
5731       break;
5732     case OPERATOR_NOTEQ:
5733       exp->write_c_string(" != ");
5734       break;
5735     case OPERATOR_LT:
5736       exp->write_c_string(" < ");
5737       break;
5738     case OPERATOR_LE:
5739       exp->write_c_string(" <= ");
5740       break;
5741     case OPERATOR_GT:
5742       exp->write_c_string(" > ");
5743       break;
5744     case OPERATOR_GE:
5745       exp->write_c_string(" >= ");
5746       break;
5747     case OPERATOR_PLUS:
5748       exp->write_c_string(" + ");
5749       break;
5750     case OPERATOR_MINUS:
5751       exp->write_c_string(" - ");
5752       break;
5753     case OPERATOR_OR:
5754       exp->write_c_string(" | ");
5755       break;
5756     case OPERATOR_XOR:
5757       exp->write_c_string(" ^ ");
5758       break;
5759     case OPERATOR_MULT:
5760       exp->write_c_string(" * ");
5761       break;
5762     case OPERATOR_DIV:
5763       exp->write_c_string(" / ");
5764       break;
5765     case OPERATOR_MOD:
5766       exp->write_c_string(" % ");
5767       break;
5768     case OPERATOR_LSHIFT:
5769       exp->write_c_string(" << ");
5770       break;
5771     case OPERATOR_RSHIFT:
5772       exp->write_c_string(" >> ");
5773       break;
5774     case OPERATOR_AND:
5775       exp->write_c_string(" & ");
5776       break;
5777     case OPERATOR_BITCLEAR:
5778       exp->write_c_string(" &^ ");
5779       break;
5780     default:
5781       gcc_unreachable();
5782     }
5783   this->right_->export_expression(exp);
5784   exp->write_c_string(")");
5785 }
5786
5787 // Import a binary expression.
5788
5789 Expression*
5790 Binary_expression::do_import(Import* imp)
5791 {
5792   imp->require_c_string("(");
5793
5794   Expression* left = Expression::import_expression(imp);
5795
5796   Operator op;
5797   if (imp->match_c_string(" || "))
5798     {
5799       op = OPERATOR_OROR;
5800       imp->advance(4);
5801     }
5802   else if (imp->match_c_string(" && "))
5803     {
5804       op = OPERATOR_ANDAND;
5805       imp->advance(4);
5806     }
5807   else if (imp->match_c_string(" == "))
5808     {
5809       op = OPERATOR_EQEQ;
5810       imp->advance(4);
5811     }
5812   else if (imp->match_c_string(" != "))
5813     {
5814       op = OPERATOR_NOTEQ;
5815       imp->advance(4);
5816     }
5817   else if (imp->match_c_string(" < "))
5818     {
5819       op = OPERATOR_LT;
5820       imp->advance(3);
5821     }
5822   else if (imp->match_c_string(" <= "))
5823     {
5824       op = OPERATOR_LE;
5825       imp->advance(4);
5826     }
5827   else if (imp->match_c_string(" > "))
5828     {
5829       op = OPERATOR_GT;
5830       imp->advance(3);
5831     }
5832   else if (imp->match_c_string(" >= "))
5833     {
5834       op = OPERATOR_GE;
5835       imp->advance(4);
5836     }
5837   else if (imp->match_c_string(" + "))
5838     {
5839       op = OPERATOR_PLUS;
5840       imp->advance(3);
5841     }
5842   else if (imp->match_c_string(" - "))
5843     {
5844       op = OPERATOR_MINUS;
5845       imp->advance(3);
5846     }
5847   else if (imp->match_c_string(" | "))
5848     {
5849       op = OPERATOR_OR;
5850       imp->advance(3);
5851     }
5852   else if (imp->match_c_string(" ^ "))
5853     {
5854       op = OPERATOR_XOR;
5855       imp->advance(3);
5856     }
5857   else if (imp->match_c_string(" * "))
5858     {
5859       op = OPERATOR_MULT;
5860       imp->advance(3);
5861     }
5862   else if (imp->match_c_string(" / "))
5863     {
5864       op = OPERATOR_DIV;
5865       imp->advance(3);
5866     }
5867   else if (imp->match_c_string(" % "))
5868     {
5869       op = OPERATOR_MOD;
5870       imp->advance(3);
5871     }
5872   else if (imp->match_c_string(" << "))
5873     {
5874       op = OPERATOR_LSHIFT;
5875       imp->advance(4);
5876     }
5877   else if (imp->match_c_string(" >> "))
5878     {
5879       op = OPERATOR_RSHIFT;
5880       imp->advance(4);
5881     }
5882   else if (imp->match_c_string(" & "))
5883     {
5884       op = OPERATOR_AND;
5885       imp->advance(3);
5886     }
5887   else if (imp->match_c_string(" &^ "))
5888     {
5889       op = OPERATOR_BITCLEAR;
5890       imp->advance(4);
5891     }
5892   else
5893     {
5894       error_at(imp->location(), "unrecognized binary operator");
5895       return Expression::make_error(imp->location());
5896     }
5897
5898   Expression* right = Expression::import_expression(imp);
5899
5900   imp->require_c_string(")");
5901
5902   return Expression::make_binary(op, left, right, imp->location());
5903 }
5904
5905 // Make a binary expression.
5906
5907 Expression*
5908 Expression::make_binary(Operator op, Expression* left, Expression* right,
5909                         source_location location)
5910 {
5911   return new Binary_expression(op, left, right, location);
5912 }
5913
5914 // Implement a comparison.
5915
5916 tree
5917 Expression::comparison_tree(Translate_context* context, Operator op,
5918                             Type* left_type, tree left_tree,
5919                             Type* right_type, tree right_tree,
5920                             source_location location)
5921 {
5922   enum tree_code code;
5923   switch (op)
5924     {
5925     case OPERATOR_EQEQ:
5926       code = EQ_EXPR;
5927       break;
5928     case OPERATOR_NOTEQ:
5929       code = NE_EXPR;
5930       break;
5931     case OPERATOR_LT:
5932       code = LT_EXPR;
5933       break;
5934     case OPERATOR_LE:
5935       code = LE_EXPR;
5936       break;
5937     case OPERATOR_GT:
5938       code = GT_EXPR;
5939       break;
5940     case OPERATOR_GE:
5941       code = GE_EXPR;
5942       break;
5943     default:
5944       gcc_unreachable();
5945     }
5946
5947   if (left_type->is_string_type() && right_type->is_string_type())
5948     {
5949       tree string_type = Type::make_string_type()->get_tree(context->gogo());
5950       static tree string_compare_decl;
5951       left_tree = Gogo::call_builtin(&string_compare_decl,
5952                                      location,
5953                                      "__go_strcmp",
5954                                      2,
5955                                      integer_type_node,
5956                                      string_type,
5957                                      left_tree,
5958                                      string_type,
5959                                      right_tree);
5960       right_tree = build_int_cst_type(integer_type_node, 0);
5961     }
5962   else if ((left_type->interface_type() != NULL
5963             && right_type->interface_type() == NULL
5964             && !right_type->is_nil_type())
5965            || (left_type->interface_type() == NULL
5966                && !left_type->is_nil_type()
5967                && right_type->interface_type() != NULL))
5968     {
5969       // Comparing an interface value to a non-interface value.
5970       if (left_type->interface_type() == NULL)
5971         {
5972           std::swap(left_type, right_type);
5973           std::swap(left_tree, right_tree);
5974         }
5975
5976       // The right operand is not an interface.  We need to take its
5977       // address if it is not a pointer.
5978       tree make_tmp;
5979       tree arg;
5980       if (right_type->points_to() != NULL)
5981         {
5982           make_tmp = NULL_TREE;
5983           arg = right_tree;
5984         }
5985       else if (TREE_ADDRESSABLE(TREE_TYPE(right_tree)) || DECL_P(right_tree))
5986         {
5987           make_tmp = NULL_TREE;
5988           arg = build_fold_addr_expr_loc(location, right_tree);
5989           if (DECL_P(right_tree))
5990             TREE_ADDRESSABLE(right_tree) = 1;
5991         }
5992       else
5993         {
5994           tree tmp = create_tmp_var(TREE_TYPE(right_tree),
5995                                     get_name(right_tree));
5996           DECL_IGNORED_P(tmp) = 0;
5997           DECL_INITIAL(tmp) = right_tree;
5998           TREE_ADDRESSABLE(tmp) = 1;
5999           make_tmp = build1(DECL_EXPR, void_type_node, tmp);
6000           SET_EXPR_LOCATION(make_tmp, location);
6001           arg = build_fold_addr_expr_loc(location, tmp);
6002         }
6003       arg = fold_convert_loc(location, ptr_type_node, arg);
6004
6005       tree descriptor = right_type->type_descriptor_pointer(context->gogo());
6006
6007       if (left_type->interface_type()->is_empty())
6008         {
6009           static tree empty_interface_value_compare_decl;
6010           left_tree = Gogo::call_builtin(&empty_interface_value_compare_decl,
6011                                          location,
6012                                          "__go_empty_interface_value_compare",
6013                                          3,
6014                                          integer_type_node,
6015                                          TREE_TYPE(left_tree),
6016                                          left_tree,
6017                                          TREE_TYPE(descriptor),
6018                                          descriptor,
6019                                          ptr_type_node,
6020                                          arg);
6021           if (left_tree == error_mark_node)
6022             return error_mark_node;
6023           // This can panic if the type is not comparable.
6024           TREE_NOTHROW(empty_interface_value_compare_decl) = 0;
6025         }
6026       else
6027         {
6028           static tree interface_value_compare_decl;
6029           left_tree = Gogo::call_builtin(&interface_value_compare_decl,
6030                                          location,
6031                                          "__go_interface_value_compare",
6032                                          3,
6033                                          integer_type_node,
6034                                          TREE_TYPE(left_tree),
6035                                          left_tree,
6036                                          TREE_TYPE(descriptor),
6037                                          descriptor,
6038                                          ptr_type_node,
6039                                          arg);
6040           if (left_tree == error_mark_node)
6041             return error_mark_node;
6042           // This can panic if the type is not comparable.
6043           TREE_NOTHROW(interface_value_compare_decl) = 0;
6044         }
6045       right_tree = build_int_cst_type(integer_type_node, 0);
6046
6047       if (make_tmp != NULL_TREE)
6048         left_tree = build2(COMPOUND_EXPR, TREE_TYPE(left_tree), make_tmp,
6049                            left_tree);
6050     }
6051   else if (left_type->interface_type() != NULL
6052            && right_type->interface_type() != NULL)
6053     {
6054       if (left_type->interface_type()->is_empty())
6055         {
6056           gcc_assert(right_type->interface_type()->is_empty());
6057           static tree empty_interface_compare_decl;
6058           left_tree = Gogo::call_builtin(&empty_interface_compare_decl,
6059                                          location,
6060                                          "__go_empty_interface_compare",
6061                                          2,
6062                                          integer_type_node,
6063                                          TREE_TYPE(left_tree),
6064                                          left_tree,
6065                                          TREE_TYPE(right_tree),
6066                                          right_tree);
6067           if (left_tree == error_mark_node)
6068             return error_mark_node;
6069           // This can panic if the type is uncomparable.
6070           TREE_NOTHROW(empty_interface_compare_decl) = 0;
6071         }
6072       else
6073         {
6074           gcc_assert(!right_type->interface_type()->is_empty());
6075           static tree interface_compare_decl;
6076           left_tree = Gogo::call_builtin(&interface_compare_decl,
6077                                          location,
6078                                          "__go_interface_compare",
6079                                          2,
6080                                          integer_type_node,
6081                                          TREE_TYPE(left_tree),
6082                                          left_tree,
6083                                          TREE_TYPE(right_tree),
6084                                          right_tree);
6085           if (left_tree == error_mark_node)
6086             return error_mark_node;
6087           // This can panic if the type is uncomparable.
6088           TREE_NOTHROW(interface_compare_decl) = 0;
6089         }
6090       right_tree = build_int_cst_type(integer_type_node, 0);
6091     }
6092
6093   if (left_type->is_nil_type()
6094       && (op == OPERATOR_EQEQ || op == OPERATOR_NOTEQ))
6095     {
6096       std::swap(left_type, right_type);
6097       std::swap(left_tree, right_tree);
6098     }
6099
6100   if (right_type->is_nil_type())
6101     {
6102       if (left_type->array_type() != NULL
6103           && left_type->array_type()->length() == NULL)
6104         {
6105           Array_type* at = left_type->array_type();
6106           left_tree = at->value_pointer_tree(context->gogo(), left_tree);
6107           right_tree = fold_convert(TREE_TYPE(left_tree), null_pointer_node);
6108         }
6109       else if (left_type->interface_type() != NULL)
6110         {
6111           // An interface is nil if the first field is nil.
6112           tree left_type_tree = TREE_TYPE(left_tree);
6113           gcc_assert(TREE_CODE(left_type_tree) == RECORD_TYPE);
6114           tree field = TYPE_FIELDS(left_type_tree);
6115           left_tree = build3(COMPONENT_REF, TREE_TYPE(field), left_tree,
6116                              field, NULL_TREE);
6117           right_tree = fold_convert(TREE_TYPE(left_tree), null_pointer_node);
6118         }
6119       else
6120         {
6121           gcc_assert(POINTER_TYPE_P(TREE_TYPE(left_tree)));
6122           right_tree = fold_convert(TREE_TYPE(left_tree), null_pointer_node);
6123         }
6124     }
6125
6126   if (left_tree == error_mark_node || right_tree == error_mark_node)
6127     return error_mark_node;
6128
6129   tree ret = fold_build2(code, boolean_type_node, left_tree, right_tree);
6130   if (CAN_HAVE_LOCATION_P(ret))
6131     SET_EXPR_LOCATION(ret, location);
6132   return ret;
6133 }
6134
6135 // Class Bound_method_expression.
6136
6137 // Traversal.
6138
6139 int
6140 Bound_method_expression::do_traverse(Traverse* traverse)
6141 {
6142   if (Expression::traverse(&this->expr_, traverse) == TRAVERSE_EXIT)
6143     return TRAVERSE_EXIT;
6144   return Expression::traverse(&this->method_, traverse);
6145 }
6146
6147 // Return the type of a bound method expression.  The type of this
6148 // object is really the type of the method with no receiver.  We
6149 // should be able to get away with just returning the type of the
6150 // method.
6151
6152 Type*
6153 Bound_method_expression::do_type()
6154 {
6155   return this->method_->type();
6156 }
6157
6158 // Determine the types of a method expression.
6159
6160 void
6161 Bound_method_expression::do_determine_type(const Type_context*)
6162 {
6163   this->method_->determine_type_no_context();
6164   Type* mtype = this->method_->type();
6165   Function_type* fntype = mtype == NULL ? NULL : mtype->function_type();
6166   if (fntype == NULL || !fntype->is_method())
6167     this->expr_->determine_type_no_context();
6168   else
6169     {
6170       Type_context subcontext(fntype->receiver()->type(), false);
6171       this->expr_->determine_type(&subcontext);
6172     }
6173 }
6174
6175 // Check the types of a method expression.
6176
6177 void
6178 Bound_method_expression::do_check_types(Gogo*)
6179 {
6180   Type* type = this->method_->type()->deref();
6181   if (type == NULL
6182       || type->function_type() == NULL
6183       || !type->function_type()->is_method())
6184     this->report_error(_("object is not a method"));
6185   else
6186     {
6187       Type* rtype = type->function_type()->receiver()->type()->deref();
6188       Type* etype = (this->expr_type_ != NULL
6189                      ? this->expr_type_
6190                      : this->expr_->type());
6191       etype = etype->deref();
6192       if (!Type::are_identical(rtype, etype, true, NULL))
6193         this->report_error(_("method type does not match object type"));
6194     }
6195 }
6196
6197 // Get the tree for a method expression.  There is no standard tree
6198 // representation for this.  The only places it may currently be used
6199 // are in a Call_expression or a Go_statement, which will take it
6200 // apart directly.  So this has nothing to do at present.
6201
6202 tree
6203 Bound_method_expression::do_get_tree(Translate_context*)
6204 {
6205   gcc_unreachable();
6206 }
6207
6208 // Make a method expression.
6209
6210 Bound_method_expression*
6211 Expression::make_bound_method(Expression* expr, Expression* method,
6212                               source_location location)
6213 {
6214   return new Bound_method_expression(expr, method, location);
6215 }
6216
6217 // Class Builtin_call_expression.  This is used for a call to a
6218 // builtin function.
6219
6220 class Builtin_call_expression : public Call_expression
6221 {
6222  public:
6223   Builtin_call_expression(Gogo* gogo, Expression* fn, Expression_list* args,
6224                           bool is_varargs, source_location location);
6225
6226  protected:
6227   // This overrides Call_expression::do_lower.
6228   Expression*
6229   do_lower(Gogo*, Named_object*, int);
6230
6231   bool
6232   do_is_constant() const;
6233
6234   bool
6235   do_integer_constant_value(bool, mpz_t, Type**) const;
6236
6237   bool
6238   do_float_constant_value(mpfr_t, Type**) const;
6239
6240   bool
6241   do_complex_constant_value(mpfr_t, mpfr_t, Type**) const;
6242
6243   Type*
6244   do_type();
6245
6246   void
6247   do_determine_type(const Type_context*);
6248
6249   void
6250   do_check_types(Gogo*);
6251
6252   Expression*
6253   do_copy()
6254   {
6255     return new Builtin_call_expression(this->gogo_, this->fn()->copy(),
6256                                        this->args()->copy(),
6257                                        this->is_varargs(),
6258                                        this->location());
6259   }
6260
6261   tree
6262   do_get_tree(Translate_context*);
6263
6264   void
6265   do_export(Export*) const;
6266
6267   virtual bool
6268   do_is_recover_call() const;
6269
6270   virtual void
6271   do_set_recover_arg(Expression*);
6272
6273  private:
6274   // The builtin functions.
6275   enum Builtin_function_code
6276     {
6277       BUILTIN_INVALID,
6278
6279       // Predeclared builtin functions.
6280       BUILTIN_APPEND,
6281       BUILTIN_CAP,
6282       BUILTIN_CLOSE,
6283       BUILTIN_CLOSED,
6284       BUILTIN_CMPLX,
6285       BUILTIN_COPY,
6286       BUILTIN_IMAG,
6287       BUILTIN_LEN,
6288       BUILTIN_MAKE,
6289       BUILTIN_NEW,
6290       BUILTIN_PANIC,
6291       BUILTIN_PRINT,
6292       BUILTIN_PRINTLN,
6293       BUILTIN_REAL,
6294       BUILTIN_RECOVER,
6295
6296       // Builtin functions from the unsafe package.
6297       BUILTIN_ALIGNOF,
6298       BUILTIN_OFFSETOF,
6299       BUILTIN_SIZEOF
6300     };
6301
6302   Expression*
6303   one_arg() const;
6304
6305   bool
6306   check_one_arg();
6307
6308   static Type*
6309   real_imag_type(Type*);
6310
6311   static Type*
6312   cmplx_type(Type*);
6313
6314   // A pointer back to the general IR structure.  This avoids a global
6315   // variable, or passing it around everywhere.
6316   Gogo* gogo_;
6317   // The builtin function being called.
6318   Builtin_function_code code_;
6319 };
6320
6321 Builtin_call_expression::Builtin_call_expression(Gogo* gogo,
6322                                                  Expression* fn,
6323                                                  Expression_list* args,
6324                                                  bool is_varargs,
6325                                                  source_location location)
6326   : Call_expression(fn, args, is_varargs, location),
6327     gogo_(gogo), code_(BUILTIN_INVALID)
6328 {
6329   Func_expression* fnexp = this->fn()->func_expression();
6330   gcc_assert(fnexp != NULL);
6331   const std::string& name(fnexp->named_object()->name());
6332   if (name == "append")
6333     this->code_ = BUILTIN_APPEND;
6334   else if (name == "cap")
6335     this->code_ = BUILTIN_CAP;
6336   else if (name == "close")
6337     this->code_ = BUILTIN_CLOSE;
6338   else if (name == "closed")
6339     this->code_ = BUILTIN_CLOSED;
6340   else if (name == "cmplx")
6341     this->code_ = BUILTIN_CMPLX;
6342   else if (name == "copy")
6343     this->code_ = BUILTIN_COPY;
6344   else if (name == "imag")
6345     this->code_ = BUILTIN_IMAG;
6346   else if (name == "len")
6347     this->code_ = BUILTIN_LEN;
6348   else if (name == "make")
6349     this->code_ = BUILTIN_MAKE;
6350   else if (name == "new")
6351     this->code_ = BUILTIN_NEW;
6352   else if (name == "panic")
6353     this->code_ = BUILTIN_PANIC;
6354   else if (name == "print")
6355     this->code_ = BUILTIN_PRINT;
6356   else if (name == "println")
6357     this->code_ = BUILTIN_PRINTLN;
6358   else if (name == "real")
6359     this->code_ = BUILTIN_REAL;
6360   else if (name == "recover")
6361     this->code_ = BUILTIN_RECOVER;
6362   else if (name == "Alignof")
6363     this->code_ = BUILTIN_ALIGNOF;
6364   else if (name == "Offsetof")
6365     this->code_ = BUILTIN_OFFSETOF;
6366   else if (name == "Sizeof")
6367     this->code_ = BUILTIN_SIZEOF;
6368   else
6369     gcc_unreachable();
6370 }
6371
6372 // Return whether this is a call to recover.  This is a virtual
6373 // function called from the parent class.
6374
6375 bool
6376 Builtin_call_expression::do_is_recover_call() const
6377 {
6378   if (this->classification() == EXPRESSION_ERROR)
6379     return false;
6380   return this->code_ == BUILTIN_RECOVER;
6381 }
6382
6383 // Set the argument for a call to recover.
6384
6385 void
6386 Builtin_call_expression::do_set_recover_arg(Expression* arg)
6387 {
6388   const Expression_list* args = this->args();
6389   gcc_assert(args == NULL || args->empty());
6390   Expression_list* new_args = new Expression_list();
6391   new_args->push_back(arg);
6392   this->set_args(new_args);
6393 }
6394
6395 // A traversal class which looks for a call expression.
6396
6397 class Find_call_expression : public Traverse
6398 {
6399  public:
6400   Find_call_expression()
6401     : Traverse(traverse_expressions),
6402       found_(false)
6403   { }
6404
6405   int
6406   expression(Expression**);
6407
6408   bool
6409   found()
6410   { return this->found_; }
6411
6412  private:
6413   bool found_;
6414 };
6415
6416 int
6417 Find_call_expression::expression(Expression** pexpr)
6418 {
6419   if ((*pexpr)->call_expression() != NULL)
6420     {
6421       this->found_ = true;
6422       return TRAVERSE_EXIT;
6423     }
6424   return TRAVERSE_CONTINUE;
6425 }
6426
6427 // Lower a builtin call expression.  This turns new and make into
6428 // specific expressions.  We also convert to a constant if we can.
6429
6430 Expression*
6431 Builtin_call_expression::do_lower(Gogo* gogo, Named_object* function, int)
6432 {
6433   if (this->code_ == BUILTIN_NEW)
6434     {
6435       const Expression_list* args = this->args();
6436       if (args == NULL || args->size() < 1)
6437         this->report_error(_("not enough arguments"));
6438       else if (args->size() > 1)
6439         this->report_error(_("too many 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             return Expression::make_allocation(arg->type(), this->location());
6450         }
6451     }
6452   else if (this->code_ == BUILTIN_MAKE)
6453     {
6454       const Expression_list* args = this->args();
6455       if (args == NULL || args->size() < 1)
6456         this->report_error(_("not enough arguments"));
6457       else
6458         {
6459           Expression* arg = args->front();
6460           if (!arg->is_type_expression())
6461             {
6462               error_at(arg->location(), "expected type");
6463               this->set_is_error();
6464             }
6465           else
6466             {
6467               Expression_list* newargs;
6468               if (args->size() == 1)
6469                 newargs = NULL;
6470               else
6471                 {
6472                   newargs = new Expression_list();
6473                   Expression_list::const_iterator p = args->begin();
6474                   ++p;
6475                   for (; p != args->end(); ++p)
6476                     newargs->push_back(*p);
6477                 }
6478               return Expression::make_make(arg->type(), newargs,
6479                                            this->location());
6480             }
6481         }
6482     }
6483   else if (this->is_constant())
6484     {
6485       // We can only lower len and cap if there are no function calls
6486       // in the arguments.  Otherwise we have to make the call.
6487       if (this->code_ == BUILTIN_LEN || this->code_ == BUILTIN_CAP)
6488         {
6489           Expression* arg = this->one_arg();
6490           if (!arg->is_constant())
6491             {
6492               Find_call_expression find_call;
6493               Expression::traverse(&arg, &find_call);
6494               if (find_call.found())
6495                 return this;
6496             }
6497         }
6498
6499       mpz_t ival;
6500       mpz_init(ival);
6501       Type* type;
6502       if (this->integer_constant_value(true, ival, &type))
6503         {
6504           Expression* ret = Expression::make_integer(&ival, type,
6505                                                      this->location());
6506           mpz_clear(ival);
6507           return ret;
6508         }
6509       mpz_clear(ival);
6510
6511       mpfr_t rval;
6512       mpfr_init(rval);
6513       if (this->float_constant_value(rval, &type))
6514         {
6515           Expression* ret = Expression::make_float(&rval, type,
6516                                                    this->location());
6517           mpfr_clear(rval);
6518           return ret;
6519         }
6520
6521       mpfr_t imag;
6522       mpfr_init(imag);
6523       if (this->complex_constant_value(rval, imag, &type))
6524         {
6525           Expression* ret = Expression::make_complex(&rval, &imag, type,
6526                                                      this->location());
6527           mpfr_clear(rval);
6528           mpfr_clear(imag);
6529           return ret;
6530         }
6531       mpfr_clear(rval);
6532       mpfr_clear(imag);
6533     }
6534   else if (this->code_ == BUILTIN_RECOVER)
6535     {
6536       if (function != NULL)
6537         function->func_value()->set_calls_recover();
6538       else
6539         {
6540           // Calling recover outside of a function always returns the
6541           // nil empty interface.
6542           Type* eface = Type::make_interface_type(NULL, this->location());
6543           return Expression::make_cast(eface,
6544                                        Expression::make_nil(this->location()),
6545                                        this->location());
6546         }
6547     }
6548   else if (this->code_ == BUILTIN_APPEND)
6549     {
6550       // Lower the varargs.
6551       const Expression_list* args = this->args();
6552       if (args == NULL || args->empty())
6553         return this;
6554       Type* slice_type = args->front()->type();
6555       if (!slice_type->is_open_array_type())
6556         {
6557           error_at(args->front()->location(), "argument 1 must be a slice");
6558           this->set_is_error();
6559           return this;
6560         }
6561       return this->lower_varargs(gogo, function, slice_type, 2);
6562     }
6563
6564   return this;
6565 }
6566
6567 // Return the type of the real or imag functions, given the type of
6568 // the argument.  We need to map complex to float, complex64 to
6569 // float32, and complex128 to float64, so it has to be done by name.
6570 // This returns NULL if it can't figure out the type.
6571
6572 Type*
6573 Builtin_call_expression::real_imag_type(Type* arg_type)
6574 {
6575   if (arg_type == NULL || arg_type->is_abstract())
6576     return NULL;
6577   Named_type* nt = arg_type->named_type();
6578   if (nt == NULL)
6579     return NULL;
6580   while (nt->real_type()->named_type() != NULL)
6581     nt = nt->real_type()->named_type();
6582   if (nt->name() == "complex")
6583     return Type::lookup_float_type("float");
6584   else if (nt->name() == "complex64")
6585     return Type::lookup_float_type("float32");
6586   else if (nt->name() == "complex128")
6587     return Type::lookup_float_type("float64");
6588   else
6589     return NULL;
6590 }
6591
6592 // Return the type of the cmplx function, given the type of one of the
6593 // argments.  Like real_imag_type, we have to map by name.
6594
6595 Type*
6596 Builtin_call_expression::cmplx_type(Type* arg_type)
6597 {
6598   if (arg_type == NULL || arg_type->is_abstract())
6599     return NULL;
6600   Named_type* nt = arg_type->named_type();
6601   if (nt == NULL)
6602     return NULL;
6603   while (nt->real_type()->named_type() != NULL)
6604     nt = nt->real_type()->named_type();
6605   if (nt->name() == "float")
6606     return Type::lookup_complex_type("complex");
6607   else if (nt->name() == "float32")
6608     return Type::lookup_complex_type("complex64");
6609   else if (nt->name() == "float64")
6610     return Type::lookup_complex_type("complex128");
6611   else
6612     return NULL;
6613 }
6614
6615 // Return a single argument, or NULL if there isn't one.
6616
6617 Expression*
6618 Builtin_call_expression::one_arg() const
6619 {
6620   const Expression_list* args = this->args();
6621   if (args->size() != 1)
6622     return NULL;
6623   return args->front();
6624 }
6625
6626 // Return whether this is constant: len of a string, or len or cap of
6627 // a fixed array, or unsafe.Sizeof, unsafe.Offsetof, unsafe.Alignof.
6628
6629 bool
6630 Builtin_call_expression::do_is_constant() const
6631 {
6632   switch (this->code_)
6633     {
6634     case BUILTIN_LEN:
6635     case BUILTIN_CAP:
6636       {
6637         Expression* arg = this->one_arg();
6638         if (arg == NULL)
6639           return false;
6640         Type* arg_type = arg->type();
6641
6642         if (arg_type->points_to() != NULL
6643             && arg_type->points_to()->array_type() != NULL
6644             && !arg_type->points_to()->is_open_array_type())
6645           arg_type = arg_type->points_to();
6646
6647         if (arg_type->array_type() != NULL
6648             && arg_type->array_type()->length() != NULL)
6649           return arg_type->array_type()->length()->is_constant();
6650
6651         if (this->code_ == BUILTIN_LEN && arg_type->is_string_type())
6652           return arg->is_constant();
6653       }
6654       break;
6655
6656     case BUILTIN_SIZEOF:
6657     case BUILTIN_ALIGNOF:
6658       return this->one_arg() != NULL;
6659
6660     case BUILTIN_OFFSETOF:
6661       {
6662         Expression* arg = this->one_arg();
6663         if (arg == NULL)
6664           return false;
6665         return arg->field_reference_expression() != NULL;
6666       }
6667
6668     case BUILTIN_CMPLX:
6669       {
6670         const Expression_list* args = this->args();
6671         if (args != NULL && args->size() == 2)
6672           return args->front()->is_constant() && args->back()->is_constant();
6673       }
6674       break;
6675
6676     case BUILTIN_REAL:
6677     case BUILTIN_IMAG:
6678       {
6679         Expression* arg = this->one_arg();
6680         return arg != NULL && arg->is_constant();
6681       }
6682
6683     default:
6684       break;
6685     }
6686
6687   return false;
6688 }
6689
6690 // Return an integer constant value if possible.
6691
6692 bool
6693 Builtin_call_expression::do_integer_constant_value(bool iota_is_constant,
6694                                                    mpz_t val,
6695                                                    Type** ptype) const
6696 {
6697   if (this->code_ == BUILTIN_LEN
6698       || this->code_ == BUILTIN_CAP)
6699     {
6700       Expression* arg = this->one_arg();
6701       if (arg == NULL)
6702         return false;
6703       Type* arg_type = arg->type();
6704
6705       if (this->code_ == BUILTIN_LEN && arg_type->is_string_type())
6706         {
6707           std::string sval;
6708           if (arg->string_constant_value(&sval))
6709             {
6710               mpz_set_ui(val, sval.length());
6711               *ptype = Type::lookup_integer_type("int");
6712               return true;
6713             }
6714         }
6715
6716       if (arg_type->points_to() != NULL
6717           && arg_type->points_to()->array_type() != NULL
6718           && !arg_type->points_to()->is_open_array_type())
6719         arg_type = arg_type->points_to();
6720
6721       if (arg_type->array_type() != NULL
6722           && arg_type->array_type()->length() != NULL)
6723         {
6724           Expression* e = arg_type->array_type()->length();
6725           if (e->integer_constant_value(iota_is_constant, val, ptype))
6726             {
6727               *ptype = Type::lookup_integer_type("int");
6728               return true;
6729             }
6730         }
6731     }
6732   else if (this->code_ == BUILTIN_SIZEOF
6733            || this->code_ == BUILTIN_ALIGNOF)
6734     {
6735       Expression* arg = this->one_arg();
6736       if (arg == NULL)
6737         return false;
6738       Type* arg_type = arg->type();
6739       if (arg_type->is_error_type() || arg_type->is_undefined())
6740         return false;
6741       if (arg_type->is_abstract())
6742         return false;
6743       tree arg_type_tree = arg_type->get_tree(this->gogo_);
6744       unsigned long val_long;
6745       if (this->code_ == BUILTIN_SIZEOF)
6746         {
6747           tree type_size = TYPE_SIZE_UNIT(arg_type_tree);
6748           gcc_assert(TREE_CODE(type_size) == INTEGER_CST);
6749           if (TREE_INT_CST_HIGH(type_size) != 0)
6750             return false;
6751           unsigned HOST_WIDE_INT val_wide = TREE_INT_CST_LOW(type_size);
6752           val_long = static_cast<unsigned long>(val_wide);
6753           if (val_long != val_wide)
6754             return false;
6755         }
6756       else if (this->code_ == BUILTIN_ALIGNOF)
6757         {
6758           if (arg->field_reference_expression() == NULL)
6759             val_long = go_type_alignment(arg_type_tree);
6760           else
6761             {
6762               // Calling unsafe.Alignof(s.f) returns the alignment of
6763               // the type of f when it is used as a field in a struct.
6764               val_long = go_field_alignment(arg_type_tree);
6765             }
6766         }
6767       else
6768         gcc_unreachable();
6769       mpz_set_ui(val, val_long);
6770       *ptype = NULL;
6771       return true;
6772     }
6773   else if (this->code_ == BUILTIN_OFFSETOF)
6774     {
6775       Expression* arg = this->one_arg();
6776       if (arg == NULL)
6777         return false;
6778       Field_reference_expression* farg = arg->field_reference_expression();
6779       if (farg == NULL)
6780         return false;
6781       Expression* struct_expr = farg->expr();
6782       Type* st = struct_expr->type();
6783       if (st->struct_type() == NULL)
6784         return false;
6785       tree struct_tree = st->get_tree(this->gogo_);
6786       gcc_assert(TREE_CODE(struct_tree) == RECORD_TYPE);
6787       tree field = TYPE_FIELDS(struct_tree);
6788       for (unsigned int index = farg->field_index(); index > 0; --index)
6789         {
6790           field = DECL_CHAIN(field);
6791           gcc_assert(field != NULL_TREE);
6792         }
6793       HOST_WIDE_INT offset_wide = int_byte_position (field);
6794       if (offset_wide < 0)
6795         return false;
6796       unsigned long offset_long = static_cast<unsigned long>(offset_wide);
6797       if (offset_long != static_cast<unsigned HOST_WIDE_INT>(offset_wide))
6798         return false;
6799       mpz_set_ui(val, offset_long);
6800       return true;
6801     }
6802   return false;
6803 }
6804
6805 // Return a floating point constant value if possible.
6806
6807 bool
6808 Builtin_call_expression::do_float_constant_value(mpfr_t val,
6809                                                  Type** ptype) const
6810 {
6811   if (this->code_ == BUILTIN_REAL || this->code_ == BUILTIN_IMAG)
6812     {
6813       Expression* arg = this->one_arg();
6814       if (arg == NULL)
6815         return false;
6816
6817       mpfr_t real;
6818       mpfr_t imag;
6819       mpfr_init(real);
6820       mpfr_init(imag);
6821
6822       bool ret = false;
6823       Type* type;
6824       if (arg->complex_constant_value(real, imag, &type))
6825         {
6826           if (this->code_ == BUILTIN_REAL)
6827             mpfr_set(val, real, GMP_RNDN);
6828           else
6829             mpfr_set(val, imag, GMP_RNDN);
6830           *ptype = Builtin_call_expression::real_imag_type(type);
6831           ret = true;
6832         }
6833
6834       mpfr_clear(real);
6835       mpfr_clear(imag);
6836       return ret;
6837     }
6838
6839   return false;
6840 }
6841
6842 // Return a complex constant value if possible.
6843
6844 bool
6845 Builtin_call_expression::do_complex_constant_value(mpfr_t real, mpfr_t imag,
6846                                                    Type** ptype) const
6847 {
6848   if (this->code_ == BUILTIN_CMPLX)
6849     {
6850       const Expression_list* args = this->args();
6851       if (args == NULL || args->size() != 2)
6852         return false;
6853
6854       mpfr_t r;
6855       mpfr_init(r);
6856       Type* rtype;
6857       if (!args->front()->float_constant_value(r, &rtype))
6858         {
6859           mpfr_clear(r);
6860           return false;
6861         }
6862
6863       mpfr_t i;
6864       mpfr_init(i);
6865
6866       bool ret = false;
6867       Type* itype;
6868       if (args->back()->float_constant_value(i, &itype)
6869           && Type::are_identical(rtype, itype, false, NULL))
6870         {
6871           mpfr_set(real, r, GMP_RNDN);
6872           mpfr_set(imag, i, GMP_RNDN);
6873           *ptype = Builtin_call_expression::cmplx_type(rtype);
6874           ret = true;
6875         }
6876
6877       mpfr_clear(r);
6878       mpfr_clear(i);
6879
6880       return ret;
6881     }
6882
6883   return false;
6884 }
6885
6886 // Return the type.
6887
6888 Type*
6889 Builtin_call_expression::do_type()
6890 {
6891   switch (this->code_)
6892     {
6893     case BUILTIN_INVALID:
6894     default:
6895       gcc_unreachable();
6896
6897     case BUILTIN_NEW:
6898     case BUILTIN_MAKE:
6899       {
6900         const Expression_list* args = this->args();
6901         if (args == NULL || args->empty())
6902           return Type::make_error_type();
6903         return Type::make_pointer_type(args->front()->type());
6904       }
6905
6906     case BUILTIN_CAP:
6907     case BUILTIN_COPY:
6908     case BUILTIN_LEN:
6909     case BUILTIN_ALIGNOF:
6910     case BUILTIN_OFFSETOF:
6911     case BUILTIN_SIZEOF:
6912       return Type::lookup_integer_type("int");
6913
6914     case BUILTIN_CLOSE:
6915     case BUILTIN_PANIC:
6916     case BUILTIN_PRINT:
6917     case BUILTIN_PRINTLN:
6918       return Type::make_void_type();
6919
6920     case BUILTIN_CLOSED:
6921       return Type::lookup_bool_type();
6922
6923     case BUILTIN_RECOVER:
6924       return Type::make_interface_type(NULL, BUILTINS_LOCATION);
6925
6926     case BUILTIN_APPEND:
6927       {
6928         const Expression_list* args = this->args();
6929         if (args == NULL || args->empty())
6930           return Type::make_error_type();
6931         return args->front()->type();
6932       }
6933
6934     case BUILTIN_REAL:
6935     case BUILTIN_IMAG:
6936       {
6937         Expression* arg = this->one_arg();
6938         if (arg == NULL)
6939           return Type::make_error_type();
6940         Type* t = arg->type();
6941         if (t->is_abstract())
6942           t = t->make_non_abstract_type();
6943         t = Builtin_call_expression::real_imag_type(t);
6944         if (t == NULL)
6945           t = Type::make_error_type();
6946         return t;
6947       }
6948
6949     case BUILTIN_CMPLX:
6950       {
6951         const Expression_list* args = this->args();
6952         if (args == NULL || args->size() != 2)
6953           return Type::make_error_type();
6954         Type* t = args->front()->type();
6955         if (t->is_abstract())
6956           {
6957             t = args->back()->type();
6958             if (t->is_abstract())
6959               t = t->make_non_abstract_type();
6960           }
6961         t = Builtin_call_expression::cmplx_type(t);
6962         if (t == NULL)
6963           t = Type::make_error_type();
6964         return t;
6965       }
6966     }
6967 }
6968
6969 // Determine the type.
6970
6971 void
6972 Builtin_call_expression::do_determine_type(const Type_context* context)
6973 {
6974   this->fn()->determine_type_no_context();
6975
6976   const Expression_list* args = this->args();
6977
6978   bool is_print;
6979   Type* arg_type = NULL;
6980   switch (this->code_)
6981     {
6982     case BUILTIN_PRINT:
6983     case BUILTIN_PRINTLN:
6984       // Do not force a large integer constant to "int".
6985       is_print = true;
6986       break;
6987
6988     case BUILTIN_REAL:
6989     case BUILTIN_IMAG:
6990       arg_type = Builtin_call_expression::cmplx_type(context->type);
6991       is_print = false;
6992       break;
6993
6994     case BUILTIN_CMPLX:
6995       {
6996         // For the cmplx function the type of one operand can
6997         // determine the type of the other, as in a binary expression.
6998         arg_type = Builtin_call_expression::real_imag_type(context->type);
6999         if (args != NULL && args->size() == 2)
7000           {
7001             Type* t1 = args->front()->type();
7002             Type* t2 = args->front()->type();
7003             if (!t1->is_abstract())
7004               arg_type = t1;
7005             else if (!t2->is_abstract())
7006               arg_type = t2;
7007           }
7008         is_print = false;
7009       }
7010       break;
7011
7012     default:
7013       is_print = false;
7014       break;
7015     }
7016
7017   if (args != NULL)
7018     {
7019       for (Expression_list::const_iterator pa = args->begin();
7020            pa != args->end();
7021            ++pa)
7022         {
7023           Type_context subcontext;
7024           subcontext.type = arg_type;
7025
7026           if (is_print)
7027             {
7028               // We want to print large constants, we so can't just
7029               // use the appropriate nonabstract type.  Use uint64 for
7030               // an integer if we know it is nonnegative, otherwise
7031               // use int64 for a integer, otherwise use float64 for a
7032               // float or complex128 for a complex.
7033               Type* want_type = NULL;
7034               Type* atype = (*pa)->type();
7035               if (atype->is_abstract())
7036                 {
7037                   if (atype->integer_type() != NULL)
7038                     {
7039                       mpz_t val;
7040                       mpz_init(val);
7041                       Type* dummy;
7042                       if (this->integer_constant_value(true, val, &dummy)
7043                           && mpz_sgn(val) >= 0)
7044                         want_type = Type::lookup_integer_type("uint64");
7045                       else
7046                         want_type = Type::lookup_integer_type("int64");
7047                       mpz_clear(val);
7048                     }
7049                   else if (atype->float_type() != NULL)
7050                     want_type = Type::lookup_float_type("float64");
7051                   else if (atype->complex_type() != NULL)
7052                     want_type = Type::lookup_complex_type("complex128");
7053                   else if (atype->is_abstract_string_type())
7054                     want_type = Type::lookup_string_type();
7055                   else if (atype->is_abstract_boolean_type())
7056                     want_type = Type::lookup_bool_type();
7057                   else
7058                     gcc_unreachable();
7059                   subcontext.type = want_type;
7060                 }
7061             }
7062
7063           (*pa)->determine_type(&subcontext);
7064         }
7065     }
7066 }
7067
7068 // If there is exactly one argument, return true.  Otherwise give an
7069 // error message and return false.
7070
7071 bool
7072 Builtin_call_expression::check_one_arg()
7073 {
7074   const Expression_list* args = this->args();
7075   if (args == NULL || args->size() < 1)
7076     {
7077       this->report_error(_("not enough arguments"));
7078       return false;
7079     }
7080   else if (args->size() > 1)
7081     {
7082       this->report_error(_("too many arguments"));
7083       return false;
7084     }
7085   if (args->front()->is_error_expression()
7086       || args->front()->type()->is_error_type()
7087       || args->front()->type()->is_undefined())
7088     {
7089       this->set_is_error();
7090       return false;
7091     }
7092   return true;
7093 }
7094
7095 // Check argument types for a builtin function.
7096
7097 void
7098 Builtin_call_expression::do_check_types(Gogo*)
7099 {
7100   switch (this->code_)
7101     {
7102     case BUILTIN_INVALID:
7103     case BUILTIN_NEW:
7104     case BUILTIN_MAKE:
7105       return;
7106
7107     case BUILTIN_LEN:
7108     case BUILTIN_CAP:
7109       {
7110         // The single argument may be either a string or an array or a
7111         // map or a channel, or a pointer to a closed array.
7112         if (this->check_one_arg())
7113           {
7114             Type* arg_type = this->one_arg()->type();
7115             if (arg_type->points_to() != NULL
7116                 && arg_type->points_to()->array_type() != NULL
7117                 && !arg_type->points_to()->is_open_array_type())
7118               arg_type = arg_type->points_to();
7119             if (this->code_ == BUILTIN_CAP)
7120               {
7121                 if (!arg_type->is_error_type()
7122                     && arg_type->array_type() == NULL
7123                     && arg_type->channel_type() == NULL)
7124                   this->report_error(_("argument must be array or slice "
7125                                        "or channel"));
7126               }
7127             else
7128               {
7129                 if (!arg_type->is_error_type()
7130                     && !arg_type->is_string_type()
7131                     && arg_type->array_type() == NULL
7132                     && arg_type->map_type() == NULL
7133                     && arg_type->channel_type() == NULL)
7134                   this->report_error(_("argument must be string or "
7135                                        "array or slice or map or channel"));
7136               }
7137           }
7138       }
7139       break;
7140
7141     case BUILTIN_PRINT:
7142     case BUILTIN_PRINTLN:
7143       {
7144         const Expression_list* args = this->args();
7145         if (args == NULL)
7146           {
7147             if (this->code_ == BUILTIN_PRINT)
7148               warning_at(this->location(), 0,
7149                          "no arguments for builtin function %<%s%>",
7150                          (this->code_ == BUILTIN_PRINT
7151                           ? "print"
7152                           : "println"));
7153           }
7154         else
7155           {
7156             for (Expression_list::const_iterator p = args->begin();
7157                  p != args->end();
7158                  ++p)
7159               {
7160                 Type* type = (*p)->type();
7161                 if (type->is_error_type()
7162                     || type->is_string_type()
7163                     || type->integer_type() != NULL
7164                     || type->float_type() != NULL
7165                     || type->complex_type() != NULL
7166                     || type->is_boolean_type()
7167                     || type->points_to() != NULL
7168                     || type->interface_type() != NULL
7169                     || type->channel_type() != NULL
7170                     || type->map_type() != NULL
7171                     || type->function_type() != NULL
7172                     || type->is_open_array_type())
7173                   ;
7174                 else
7175                   this->report_error(_("unsupported argument type to "
7176                                        "builtin function"));
7177               }
7178           }
7179       }
7180       break;
7181
7182     case BUILTIN_CLOSE:
7183     case BUILTIN_CLOSED:
7184       if (this->check_one_arg())
7185         {
7186           if (this->one_arg()->type()->channel_type() == NULL)
7187             this->report_error(_("argument must be channel"));
7188         }
7189       break;
7190
7191     case BUILTIN_PANIC:
7192     case BUILTIN_SIZEOF:
7193     case BUILTIN_ALIGNOF:
7194       this->check_one_arg();
7195       break;
7196
7197     case BUILTIN_RECOVER:
7198       if (this->args() != NULL && !this->args()->empty())
7199         this->report_error(_("too many arguments"));
7200       break;
7201
7202     case BUILTIN_OFFSETOF:
7203       if (this->check_one_arg())
7204         {
7205           Expression* arg = this->one_arg();
7206           if (arg->field_reference_expression() == NULL)
7207             this->report_error(_("argument must be a field reference"));
7208         }
7209       break;
7210
7211     case BUILTIN_COPY:
7212       {
7213         const Expression_list* args = this->args();
7214         if (args == NULL || args->size() < 2)
7215           {
7216             this->report_error(_("not enough arguments"));
7217             break;
7218           }
7219         else if (args->size() > 2)
7220           {
7221             this->report_error(_("too many arguments"));
7222             break;
7223           }
7224         Type* arg1_type = args->front()->type();
7225         Type* arg2_type = args->back()->type();
7226         if (arg1_type->is_error_type() || arg2_type->is_error_type())
7227           break;
7228
7229         Type* e1;
7230         if (arg1_type->is_open_array_type())
7231           e1 = arg1_type->array_type()->element_type();
7232         else
7233           {
7234             this->report_error(_("left argument must be a slice"));
7235             break;
7236           }
7237
7238         Type* e2;
7239         if (arg2_type->is_open_array_type())
7240           e2 = arg2_type->array_type()->element_type();
7241         else if (arg2_type->is_string_type())
7242           e2 = Type::lookup_integer_type("uint8");
7243         else
7244           {
7245             this->report_error(_("right argument must be a slice or a string"));
7246             break;
7247           }
7248
7249         if (!Type::are_identical(e1, e2, true, NULL))
7250           this->report_error(_("element types must be the same"));
7251       }
7252       break;
7253
7254     case BUILTIN_APPEND:
7255       {
7256         const Expression_list* args = this->args();
7257         if (args == NULL || args->empty())
7258           {
7259             this->report_error(_("not enough arguments"));
7260             break;
7261           }
7262         /* Lowering varargs should have left us with 2 arguments.  */
7263         gcc_assert(args->size() == 2);
7264         std::string reason;
7265         if (!Type::are_assignable(args->front()->type(), args->back()->type(),
7266                                   &reason))
7267           {
7268             if (reason.empty())
7269               this->report_error(_("arguments 1 and 2 have different types"));
7270             else
7271               {
7272                 error_at(this->location(),
7273                          "arguments 1 and 2 have different types (%s)",
7274                          reason.c_str());
7275                 this->set_is_error();
7276               }
7277           }
7278         break;
7279       }
7280
7281     case BUILTIN_REAL:
7282     case BUILTIN_IMAG:
7283       if (this->check_one_arg())
7284         {
7285           if (this->one_arg()->type()->complex_type() == NULL)
7286             this->report_error(_("argument must have complex type"));
7287         }
7288       break;
7289
7290     case BUILTIN_CMPLX:
7291       {
7292         const Expression_list* args = this->args();
7293         if (args == NULL || args->size() < 2)
7294           this->report_error(_("not enough arguments"));
7295         else if (args->size() > 2)
7296           this->report_error(_("too many arguments"));
7297         else if (args->front()->is_error_expression()
7298                  || args->front()->type()->is_error_type()
7299                  || args->back()->is_error_expression()
7300                  || args->back()->type()->is_error_type())
7301           this->set_is_error();
7302         else if (!Type::are_identical(args->front()->type(),
7303                                       args->back()->type(), true, NULL))
7304           this->report_error(_("cmplx arguments must have identical types"));
7305         else if (args->front()->type()->float_type() == NULL)
7306           this->report_error(_("cmplx arguments must have "
7307                                "floating-point type"));
7308       }
7309       break;
7310
7311     default:
7312       gcc_unreachable();
7313     }
7314 }
7315
7316 // Return the tree for a builtin function.
7317
7318 tree
7319 Builtin_call_expression::do_get_tree(Translate_context* context)
7320 {
7321   Gogo* gogo = context->gogo();
7322   source_location location = this->location();
7323   switch (this->code_)
7324     {
7325     case BUILTIN_INVALID:
7326     case BUILTIN_NEW:
7327     case BUILTIN_MAKE:
7328       gcc_unreachable();
7329
7330     case BUILTIN_LEN:
7331     case BUILTIN_CAP:
7332       {
7333         const Expression_list* args = this->args();
7334         gcc_assert(args != NULL && args->size() == 1);
7335         Expression* arg = *args->begin();
7336         Type* arg_type = arg->type();
7337         tree arg_tree = arg->get_tree(context);
7338         if (arg_tree == error_mark_node)
7339           return error_mark_node;
7340
7341         if (arg_type->points_to() != NULL)
7342           {
7343             arg_type = arg_type->points_to();
7344             gcc_assert(arg_type->array_type() != NULL
7345                        && !arg_type->is_open_array_type());
7346             gcc_assert(POINTER_TYPE_P(TREE_TYPE(arg_tree)));
7347             arg_tree = build_fold_indirect_ref(arg_tree);
7348           }
7349
7350         tree val_tree;
7351         if (this->code_ == BUILTIN_LEN)
7352           {
7353             if (arg_type->is_string_type())
7354               val_tree = String_type::length_tree(gogo, arg_tree);
7355             else if (arg_type->array_type() != NULL)
7356               val_tree = arg_type->array_type()->length_tree(gogo, arg_tree);
7357             else if (arg_type->map_type() != NULL)
7358               {
7359                 static tree map_len_fndecl;
7360                 val_tree = Gogo::call_builtin(&map_len_fndecl,
7361                                               location,
7362                                               "__go_map_len",
7363                                               1,
7364                                               sizetype,
7365                                               arg_type->get_tree(gogo),
7366                                               arg_tree);
7367               }
7368             else if (arg_type->channel_type() != NULL)
7369               {
7370                 static tree chan_len_fndecl;
7371                 val_tree = Gogo::call_builtin(&chan_len_fndecl,
7372                                               location,
7373                                               "__go_chan_len",
7374                                               1,
7375                                               sizetype,
7376                                               arg_type->get_tree(gogo),
7377                                               arg_tree);
7378               }
7379             else
7380               gcc_unreachable();
7381           }
7382         else
7383           {
7384             if (arg_type->array_type() != NULL)
7385               val_tree = arg_type->array_type()->capacity_tree(gogo, arg_tree);
7386             else if (arg_type->channel_type() != NULL)
7387               {
7388                 static tree chan_cap_fndecl;
7389                 val_tree = Gogo::call_builtin(&chan_cap_fndecl,
7390                                               location,
7391                                               "__go_chan_cap",
7392                                               1,
7393                                               sizetype,
7394                                               arg_type->get_tree(gogo),
7395                                               arg_tree);
7396               }
7397             else
7398               gcc_unreachable();
7399           }
7400
7401         if (val_tree == error_mark_node)
7402           return error_mark_node;
7403
7404         tree type_tree = Type::lookup_integer_type("int")->get_tree(gogo);
7405         if (type_tree == TREE_TYPE(val_tree))
7406           return val_tree;
7407         else
7408           return fold(convert_to_integer(type_tree, val_tree));
7409       }
7410
7411     case BUILTIN_PRINT:
7412     case BUILTIN_PRINTLN:
7413       {
7414         const bool is_ln = this->code_ == BUILTIN_PRINTLN;
7415         tree stmt_list = NULL_TREE;
7416
7417         const Expression_list* call_args = this->args();
7418         if (call_args != NULL)
7419           {
7420             for (Expression_list::const_iterator p = call_args->begin();
7421                  p != call_args->end();
7422                  ++p)
7423               {
7424                 if (is_ln && p != call_args->begin())
7425                   {
7426                     static tree print_space_fndecl;
7427                     tree call = Gogo::call_builtin(&print_space_fndecl,
7428                                                    location,
7429                                                    "__go_print_space",
7430                                                    0,
7431                                                    void_type_node);
7432                     if (call == error_mark_node)
7433                       return error_mark_node;
7434                     append_to_statement_list(call, &stmt_list);
7435                   }
7436
7437                 Type* type = (*p)->type();
7438
7439                 tree arg = (*p)->get_tree(context);
7440                 if (arg == error_mark_node)
7441                   return error_mark_node;
7442
7443                 tree* pfndecl;
7444                 const char* fnname;
7445                 if (type->is_string_type())
7446                   {
7447                     static tree print_string_fndecl;
7448                     pfndecl = &print_string_fndecl;
7449                     fnname = "__go_print_string";
7450                   }
7451                 else if (type->integer_type() != NULL
7452                          && type->integer_type()->is_unsigned())
7453                   {
7454                     static tree print_uint64_fndecl;
7455                     pfndecl = &print_uint64_fndecl;
7456                     fnname = "__go_print_uint64";
7457                     Type* itype = Type::lookup_integer_type("uint64");
7458                     arg = fold_convert_loc(location, itype->get_tree(gogo),
7459                                            arg);
7460                   }
7461                 else if (type->integer_type() != NULL)
7462                   {
7463                     static tree print_int64_fndecl;
7464                     pfndecl = &print_int64_fndecl;
7465                     fnname = "__go_print_int64";
7466                     Type* itype = Type::lookup_integer_type("int64");
7467                     arg = fold_convert_loc(location, itype->get_tree(gogo),
7468                                            arg);
7469                   }
7470                 else if (type->float_type() != NULL)
7471                   {
7472                     static tree print_double_fndecl;
7473                     pfndecl = &print_double_fndecl;
7474                     fnname = "__go_print_double";
7475                     arg = fold_convert_loc(location, double_type_node, arg);
7476                   }
7477                 else if (type->complex_type() != NULL)
7478                   {
7479                     static tree print_complex_fndecl;
7480                     pfndecl = &print_complex_fndecl;
7481                     fnname = "__go_print_complex";
7482                     arg = fold_convert_loc(location, complex_double_type_node,
7483                                            arg);
7484                   }
7485                 else if (type->is_boolean_type())
7486                   {
7487                     static tree print_bool_fndecl;
7488                     pfndecl = &print_bool_fndecl;
7489                     fnname = "__go_print_bool";
7490                   }
7491                 else if (type->points_to() != NULL
7492                          || type->channel_type() != NULL
7493                          || type->map_type() != NULL
7494                          || type->function_type() != NULL)
7495                   {
7496                     static tree print_pointer_fndecl;
7497                     pfndecl = &print_pointer_fndecl;
7498                     fnname = "__go_print_pointer";
7499                     arg = fold_convert_loc(location, ptr_type_node, arg);
7500                   }
7501                 else if (type->interface_type() != NULL)
7502                   {
7503                     if (type->interface_type()->is_empty())
7504                       {
7505                         static tree print_empty_interface_fndecl;
7506                         pfndecl = &print_empty_interface_fndecl;
7507                         fnname = "__go_print_empty_interface";
7508                       }
7509                     else
7510                       {
7511                         static tree print_interface_fndecl;
7512                         pfndecl = &print_interface_fndecl;
7513                         fnname = "__go_print_interface";
7514                       }
7515                   }
7516                 else if (type->is_open_array_type())
7517                   {
7518                     static tree print_slice_fndecl;
7519                     pfndecl = &print_slice_fndecl;
7520                     fnname = "__go_print_slice";
7521                   }
7522                 else
7523                   gcc_unreachable();
7524
7525                 tree call = Gogo::call_builtin(pfndecl,
7526                                                location,
7527                                                fnname,
7528                                                1,
7529                                                void_type_node,
7530                                                TREE_TYPE(arg),
7531                                                arg);
7532                 if (call == error_mark_node)
7533                   return error_mark_node;
7534                 append_to_statement_list(call, &stmt_list);
7535               }
7536           }
7537
7538         if (is_ln)
7539           {
7540             static tree print_nl_fndecl;
7541             tree call = Gogo::call_builtin(&print_nl_fndecl,
7542                                            location,
7543                                            "__go_print_nl",
7544                                            0,
7545                                            void_type_node);
7546             if (call == error_mark_node)
7547               return error_mark_node;
7548             append_to_statement_list(call, &stmt_list);
7549           }
7550
7551         return stmt_list;
7552       }
7553
7554     case BUILTIN_PANIC:
7555       {
7556         const Expression_list* args = this->args();
7557         gcc_assert(args != NULL && args->size() == 1);
7558         Expression* arg = args->front();
7559         tree arg_tree = arg->get_tree(context);
7560         if (arg_tree == error_mark_node)
7561           return error_mark_node;
7562         Type *empty = Type::make_interface_type(NULL, BUILTINS_LOCATION);
7563         arg_tree = Expression::convert_for_assignment(context, empty,
7564                                                       arg->type(),
7565                                                       arg_tree, location);
7566         static tree panic_fndecl;
7567         tree call = Gogo::call_builtin(&panic_fndecl,
7568                                        location,
7569                                        "__go_panic",
7570                                        1,
7571                                        void_type_node,
7572                                        TREE_TYPE(arg_tree),
7573                                        arg_tree);
7574         if (call == error_mark_node)
7575           return error_mark_node;
7576         // This function will throw an exception.
7577         TREE_NOTHROW(panic_fndecl) = 0;
7578         // This function will not return.
7579         TREE_THIS_VOLATILE(panic_fndecl) = 1;
7580         return call;
7581       }
7582
7583     case BUILTIN_RECOVER:
7584       {
7585         // The argument is set when building recover thunks.  It's a
7586         // boolean value which is true if we can recover a value now.
7587         const Expression_list* args = this->args();
7588         gcc_assert(args != NULL && args->size() == 1);
7589         Expression* arg = args->front();
7590         tree arg_tree = arg->get_tree(context);
7591         if (arg_tree == error_mark_node)
7592           return error_mark_node;
7593
7594         Type *empty = Type::make_interface_type(NULL, BUILTINS_LOCATION);
7595         tree empty_tree = empty->get_tree(context->gogo());
7596
7597         Type* nil_type = Type::make_nil_type();
7598         Expression* nil = Expression::make_nil(location);
7599         tree nil_tree = nil->get_tree(context);
7600         tree empty_nil_tree = Expression::convert_for_assignment(context,
7601                                                                  empty,
7602                                                                  nil_type,
7603                                                                  nil_tree,
7604                                                                  location);
7605
7606         // We need to handle a deferred call to recover specially,
7607         // because it changes whether it can recover a panic or not.
7608         // See test7 in test/recover1.go.
7609         tree call;
7610         if (this->is_deferred())
7611           {
7612             static tree deferred_recover_fndecl;
7613             call = Gogo::call_builtin(&deferred_recover_fndecl,
7614                                       location,
7615                                       "__go_deferred_recover",
7616                                       0,
7617                                       empty_tree);
7618           }
7619         else
7620           {
7621             static tree recover_fndecl;
7622             call = Gogo::call_builtin(&recover_fndecl,
7623                                       location,
7624                                       "__go_recover",
7625                                       0,
7626                                       empty_tree);
7627           }
7628         if (call == error_mark_node)
7629           return error_mark_node;
7630         return fold_build3_loc(location, COND_EXPR, empty_tree, arg_tree,
7631                                call, empty_nil_tree);
7632       }
7633
7634     case BUILTIN_CLOSE:
7635     case BUILTIN_CLOSED:
7636       {
7637         const Expression_list* args = this->args();
7638         gcc_assert(args != NULL && args->size() == 1);
7639         Expression* arg = args->front();
7640         tree arg_tree = arg->get_tree(context);
7641         if (arg_tree == error_mark_node)
7642           return error_mark_node;
7643         if (this->code_ == BUILTIN_CLOSE)
7644           {
7645             static tree close_fndecl;
7646             return Gogo::call_builtin(&close_fndecl,
7647                                       location,
7648                                       "__go_builtin_close",
7649                                       1,
7650                                       void_type_node,
7651                                       TREE_TYPE(arg_tree),
7652                                       arg_tree);
7653           }
7654         else
7655           {
7656             static tree closed_fndecl;
7657             return Gogo::call_builtin(&closed_fndecl,
7658                                       location,
7659                                       "__go_builtin_closed",
7660                                       1,
7661                                       boolean_type_node,
7662                                       TREE_TYPE(arg_tree),
7663                                       arg_tree);
7664           }
7665       }
7666
7667     case BUILTIN_SIZEOF:
7668     case BUILTIN_OFFSETOF:
7669     case BUILTIN_ALIGNOF:
7670       {
7671         mpz_t val;
7672         mpz_init(val);
7673         Type* dummy;
7674         bool b = this->integer_constant_value(true, val, &dummy);
7675         gcc_assert(b);
7676         tree type = Type::lookup_integer_type("int")->get_tree(gogo);
7677         tree ret = Expression::integer_constant_tree(val, type);
7678         mpz_clear(val);
7679         return ret;
7680       }
7681
7682     case BUILTIN_COPY:
7683       {
7684         const Expression_list* args = this->args();
7685         gcc_assert(args != NULL && args->size() == 2);
7686         Expression* arg1 = args->front();
7687         Expression* arg2 = args->back();
7688
7689         tree arg1_tree = arg1->get_tree(context);
7690         tree arg2_tree = arg2->get_tree(context);
7691         if (arg1_tree == error_mark_node || arg2_tree == error_mark_node)
7692           return error_mark_node;
7693
7694         Type* arg1_type = arg1->type();
7695         Array_type* at = arg1_type->array_type();
7696         arg1_tree = save_expr(arg1_tree);
7697         tree arg1_val = at->value_pointer_tree(gogo, arg1_tree);
7698         tree arg1_len = at->length_tree(gogo, arg1_tree);
7699         if (arg1_val == error_mark_node || arg1_len == error_mark_node)
7700           return error_mark_node;
7701
7702         Type* arg2_type = arg2->type();
7703         tree arg2_val;
7704         tree arg2_len;
7705         if (arg2_type->is_open_array_type())
7706           {
7707             at = arg2_type->array_type();
7708             arg2_tree = save_expr(arg2_tree);
7709             arg2_val = at->value_pointer_tree(gogo, arg2_tree);
7710             arg2_len = at->length_tree(gogo, arg2_tree);
7711           }
7712         else
7713           {
7714             arg2_tree = save_expr(arg2_tree);
7715             arg2_val = String_type::bytes_tree(gogo, arg2_tree);
7716             arg2_len = String_type::length_tree(gogo, arg2_tree);
7717           }
7718         if (arg2_val == error_mark_node || arg2_len == error_mark_node)
7719           return error_mark_node;
7720
7721         arg1_len = save_expr(arg1_len);
7722         arg2_len = save_expr(arg2_len);
7723         tree len = fold_build3_loc(location, COND_EXPR, TREE_TYPE(arg1_len),
7724                                    fold_build2_loc(location, LT_EXPR,
7725                                                    boolean_type_node,
7726                                                    arg1_len, arg2_len),
7727                                    arg1_len, arg2_len);
7728         len = save_expr(len);
7729
7730         Type* element_type = at->element_type();
7731         tree element_type_tree = element_type->get_tree(gogo);
7732         if (element_type_tree == error_mark_node)
7733           return error_mark_node;
7734         tree element_size = TYPE_SIZE_UNIT(element_type_tree);
7735         tree bytecount = fold_convert_loc(location, TREE_TYPE(element_size),
7736                                           len);
7737         bytecount = fold_build2_loc(location, MULT_EXPR,
7738                                     TREE_TYPE(element_size),
7739                                     bytecount, element_size);
7740         bytecount = fold_convert_loc(location, size_type_node, bytecount);
7741
7742         tree call = build_call_expr_loc(location,
7743                                         built_in_decls[BUILT_IN_MEMMOVE],
7744                                         3, arg1_val, arg2_val, bytecount);
7745
7746         return fold_build2_loc(location, COMPOUND_EXPR, TREE_TYPE(len),
7747                                call, len);
7748       }
7749
7750     case BUILTIN_APPEND:
7751       {
7752         const Expression_list* args = this->args();
7753         gcc_assert(args != NULL && args->size() == 2);
7754         Expression* arg1 = args->front();
7755         Expression* arg2 = args->back();
7756
7757         tree arg1_tree = arg1->get_tree(context);
7758         tree arg2_tree = arg2->get_tree(context);
7759         if (arg1_tree == error_mark_node || arg2_tree == error_mark_node)
7760           return error_mark_node;
7761
7762         tree descriptor_tree = arg1->type()->type_descriptor_pointer(gogo);
7763
7764         // We rebuild the decl each time since the slice types may
7765         // change.
7766         tree append_fndecl = NULL_TREE;
7767         return Gogo::call_builtin(&append_fndecl,
7768                                   location,
7769                                   "__go_append",
7770                                   3,
7771                                   TREE_TYPE(arg1_tree),
7772                                   TREE_TYPE(descriptor_tree),
7773                                   descriptor_tree,
7774                                   TREE_TYPE(arg1_tree),
7775                                   arg1_tree,
7776                                   TREE_TYPE(arg2_tree),
7777                                   arg2_tree);
7778       }
7779
7780     case BUILTIN_REAL:
7781     case BUILTIN_IMAG:
7782       {
7783         const Expression_list* args = this->args();
7784         gcc_assert(args != NULL && args->size() == 1);
7785         Expression* arg = args->front();
7786         tree arg_tree = arg->get_tree(context);
7787         if (arg_tree == error_mark_node)
7788           return error_mark_node;
7789         gcc_assert(COMPLEX_FLOAT_TYPE_P(TREE_TYPE(arg_tree)));
7790         if (this->code_ == BUILTIN_REAL)
7791           return fold_build1_loc(location, REALPART_EXPR,
7792                                  TREE_TYPE(TREE_TYPE(arg_tree)),
7793                                  arg_tree);
7794         else
7795           return fold_build1_loc(location, IMAGPART_EXPR,
7796                                  TREE_TYPE(TREE_TYPE(arg_tree)),
7797                                  arg_tree);
7798       }
7799
7800     case BUILTIN_CMPLX:
7801       {
7802         const Expression_list* args = this->args();
7803         gcc_assert(args != NULL && args->size() == 2);
7804         tree r = args->front()->get_tree(context);
7805         tree i = args->back()->get_tree(context);
7806         if (r == error_mark_node || i == error_mark_node)
7807           return error_mark_node;
7808         gcc_assert(TYPE_MAIN_VARIANT(TREE_TYPE(r))
7809                    == TYPE_MAIN_VARIANT(TREE_TYPE(i)));
7810         gcc_assert(SCALAR_FLOAT_TYPE_P(TREE_TYPE(r)));
7811         return fold_build2_loc(location, COMPLEX_EXPR,
7812                                build_complex_type(TREE_TYPE(r)),
7813                                r, i);
7814       }
7815
7816     default:
7817       gcc_unreachable();
7818     }
7819 }
7820
7821 // We have to support exporting a builtin call expression, because
7822 // code can set a constant to the result of a builtin expression.
7823
7824 void
7825 Builtin_call_expression::do_export(Export* exp) const
7826 {
7827   bool ok = false;
7828
7829   mpz_t val;
7830   mpz_init(val);
7831   Type* dummy;
7832   if (this->integer_constant_value(true, val, &dummy))
7833     {
7834       Integer_expression::export_integer(exp, val);
7835       ok = true;
7836     }
7837   mpz_clear(val);
7838
7839   if (!ok)
7840     {
7841       mpfr_t fval;
7842       mpfr_init(fval);
7843       if (this->float_constant_value(fval, &dummy))
7844         {
7845           Float_expression::export_float(exp, fval);
7846           ok = true;
7847         }
7848       mpfr_clear(fval);
7849     }
7850
7851   if (!ok)
7852     {
7853       mpfr_t real;
7854       mpfr_t imag;
7855       mpfr_init(real);
7856       mpfr_init(imag);
7857       if (this->complex_constant_value(real, imag, &dummy))
7858         {
7859           Complex_expression::export_complex(exp, real, imag);
7860           ok = true;
7861         }
7862       mpfr_clear(real);
7863       mpfr_clear(imag);
7864     }
7865
7866   if (!ok)
7867     {
7868       error_at(this->location(), "value is not constant");
7869       return;
7870     }
7871
7872   // A trailing space lets us reliably identify the end of the number.
7873   exp->write_c_string(" ");
7874 }
7875
7876 // Class Call_expression.
7877
7878 // Traversal.
7879
7880 int
7881 Call_expression::do_traverse(Traverse* traverse)
7882 {
7883   if (Expression::traverse(&this->fn_, traverse) == TRAVERSE_EXIT)
7884     return TRAVERSE_EXIT;
7885   if (this->args_ != NULL)
7886     {
7887       if (this->args_->traverse(traverse) == TRAVERSE_EXIT)
7888         return TRAVERSE_EXIT;
7889     }
7890   return TRAVERSE_CONTINUE;
7891 }
7892
7893 // Lower a call statement.
7894
7895 Expression*
7896 Call_expression::do_lower(Gogo* gogo, Named_object* function, int)
7897 {
7898   // A type case can look like a function call.
7899   if (this->fn_->is_type_expression()
7900       && this->args_ != NULL
7901       && this->args_->size() == 1)
7902     return Expression::make_cast(this->fn_->type(), this->args_->front(),
7903                                  this->location());
7904
7905   // Recognize a call to a builtin function.
7906   Func_expression* fne = this->fn_->func_expression();
7907   if (fne != NULL
7908       && fne->named_object()->is_function_declaration()
7909       && fne->named_object()->func_declaration_value()->type()->is_builtin())
7910     return new Builtin_call_expression(gogo, this->fn_, this->args_,
7911                                        this->is_varargs_, this->location());
7912
7913   // Handle an argument which is a call to a function which returns
7914   // multiple results.
7915   if (this->args_ != NULL
7916       && this->args_->size() == 1
7917       && this->args_->front()->call_expression() != NULL
7918       && this->fn_->type()->function_type() != NULL)
7919     {
7920       Function_type* fntype = this->fn_->type()->function_type();
7921       size_t rc = this->args_->front()->call_expression()->result_count();
7922       if (rc > 1
7923           && fntype->parameters() != NULL
7924           && (fntype->parameters()->size() == rc
7925               || (fntype->is_varargs()
7926                   && fntype->parameters()->size() - 1 <= rc)))
7927         {
7928           Call_expression* call = this->args_->front()->call_expression();
7929           Expression_list* args = new Expression_list;
7930           for (size_t i = 0; i < rc; ++i)
7931             args->push_back(Expression::make_call_result(call, i));
7932           // We can't return a new call expression here, because this
7933           // one may be referenced by Call_result expressions.  FIXME.
7934           delete this->args_;
7935           this->args_ = args;
7936         }
7937     }
7938
7939   // Handle a call to a varargs function by packaging up the extra
7940   // parameters.
7941   if (this->fn_->type()->function_type() != NULL
7942       && this->fn_->type()->function_type()->is_varargs())
7943     {
7944       Function_type* fntype = this->fn_->type()->function_type();
7945       const Typed_identifier_list* parameters = fntype->parameters();
7946       gcc_assert(parameters != NULL && !parameters->empty());
7947       Type* varargs_type = parameters->back().type();
7948       return this->lower_varargs(gogo, function, varargs_type,
7949                                  parameters->size());
7950     }
7951
7952   return this;
7953 }
7954
7955 // Lower a call to a varargs function.  FUNCTION is the function in
7956 // which the call occurs--it's not the function we are calling.
7957 // VARARGS_TYPE is the type of the varargs parameter, a slice type.
7958 // PARAM_COUNT is the number of parameters of the function we are
7959 // calling; the last of these parameters will be the varargs
7960 // parameter.
7961
7962 Expression*
7963 Call_expression::lower_varargs(Gogo* gogo, Named_object* function,
7964                                Type* varargs_type, size_t param_count)
7965 {
7966   if (this->varargs_are_lowered_)
7967     return this;
7968
7969   source_location loc = this->location();
7970
7971   gcc_assert(param_count > 0);
7972   gcc_assert(varargs_type->is_open_array_type());
7973
7974   size_t arg_count = this->args_ == NULL ? 0 : this->args_->size();
7975   if (arg_count < param_count - 1)
7976     {
7977       // Not enough arguments; will be caught in check_types.
7978       return this;
7979     }
7980
7981   Expression_list* old_args = this->args_;
7982   Expression_list* new_args = new Expression_list();
7983   bool push_empty_arg = false;
7984   if (old_args == NULL || old_args->empty())
7985     {
7986       gcc_assert(param_count == 1);
7987       push_empty_arg = true;
7988     }
7989   else
7990     {
7991       Expression_list::const_iterator pa;
7992       int i = 1;
7993       for (pa = old_args->begin(); pa != old_args->end(); ++pa, ++i)
7994         {
7995           if (static_cast<size_t>(i) == param_count)
7996             break;
7997           new_args->push_back(*pa);
7998         }
7999
8000       // We have reached the varargs parameter.
8001
8002       bool issued_error = false;
8003       if (pa == old_args->end())
8004         push_empty_arg = true;
8005       else if (pa + 1 == old_args->end() && this->is_varargs_)
8006         new_args->push_back(*pa);
8007       else if (this->is_varargs_)
8008         {
8009           this->report_error(_("too many arguments"));
8010           return this;
8011         }
8012       else if (pa + 1 == old_args->end()
8013                && this->is_compatible_varargs_argument(function, *pa,
8014                                                        varargs_type,
8015                                                        &issued_error))
8016         new_args->push_back(*pa);
8017       else
8018         {
8019           Type* element_type = varargs_type->array_type()->element_type();
8020           Expression_list* vals = new Expression_list;
8021           for (; pa != old_args->end(); ++pa, ++i)
8022             {
8023               // Check types here so that we get a better message.
8024               Type* patype = (*pa)->type();
8025               source_location paloc = (*pa)->location();
8026               if (!this->check_argument_type(i, element_type, patype,
8027                                              paloc, issued_error))
8028                 continue;
8029               vals->push_back(*pa);
8030             }
8031           Expression* val =
8032             Expression::make_slice_composite_literal(varargs_type, vals, loc);
8033           new_args->push_back(val);
8034         }
8035     }
8036
8037   if (push_empty_arg)
8038     new_args->push_back(Expression::make_nil(loc));
8039
8040   // We can't return a new call expression here, because this one may
8041   // be referenced by Call_result expressions.  FIXME.
8042   if (old_args != NULL)
8043     delete old_args;
8044   this->args_ = new_args;
8045   this->varargs_are_lowered_ = true;
8046
8047   // Lower all the new subexpressions.
8048   Expression* ret = this;
8049   gogo->lower_expression(function, &ret);
8050   gcc_assert(ret == this);
8051   return ret;
8052 }
8053
8054 // Return true if ARG is a varargs argment which should be passed to
8055 // the varargs parameter of type PARAM_TYPE without wrapping.  ARG
8056 // will be the last argument passed in the call, and PARAM_TYPE will
8057 // be the type of the last parameter of the varargs function being
8058 // called.
8059
8060 bool
8061 Call_expression::is_compatible_varargs_argument(Named_object* function,
8062                                                 Expression* arg,
8063                                                 Type* param_type,
8064                                                 bool* issued_error)
8065 {
8066   *issued_error = false;
8067
8068   Type* var_type = NULL;
8069
8070   // The simple case is passing the varargs parameter of the caller.
8071   Var_expression* ve = arg->var_expression();
8072   if (ve != NULL && ve->named_object()->is_variable())
8073     {
8074       Variable* var = ve->named_object()->var_value();
8075       if (var->is_varargs_parameter())
8076         var_type = var->type();
8077     }
8078
8079   // The complex case is passing the varargs parameter of some
8080   // enclosing function.  This will look like passing down *c.f where
8081   // c is the closure variable and f is a field in the closure.
8082   if (function != NULL
8083       && function->func_value()->needs_closure()
8084       && arg->classification() == EXPRESSION_UNARY)
8085     {
8086       Unary_expression* ue = static_cast<Unary_expression*>(arg);
8087       if (ue->op() == OPERATOR_MULT)
8088         {
8089           Field_reference_expression* fre =
8090             ue->operand()->deref()->field_reference_expression();
8091           if (fre != NULL)
8092             {
8093               Var_expression* ve = fre->expr()->deref()->var_expression();
8094               if (ve != NULL)
8095                 {
8096                   Named_object* no = ve->named_object();
8097                   Function* f = function->func_value();
8098                   if (no == f->closure_var())
8099                     {
8100                       // At this point we know that this indeed a
8101                       // reference to some enclosing variable.  Now we
8102                       // need to figure out whether that variable is a
8103                       // varargs parameter.
8104                       Named_object* enclosing =
8105                         f->enclosing_var(fre->field_index());
8106                       Variable* var = enclosing->var_value();
8107                       if (var->is_varargs_parameter())
8108                         var_type = var->type();
8109                     }
8110                 }
8111             }
8112         }
8113     }
8114
8115   if (var_type == NULL)
8116     return false;
8117
8118   // We only match if the parameter is the same, with an identical
8119   // type.
8120   Array_type* var_at = var_type->array_type();
8121   gcc_assert(var_at != NULL);
8122   Array_type* param_at = param_type->array_type();
8123   if (param_at != NULL
8124       && Type::are_identical(var_at->element_type(),
8125                              param_at->element_type(), true, NULL))
8126     return true;
8127   error_at(arg->location(), "... mismatch: passing ...T as ...");
8128   *issued_error = true;
8129   return false;
8130 }
8131
8132 // Get the function type.  Returns NULL if we don't know the type.  If
8133 // this returns NULL, and if_ERROR is true, issues an error.
8134
8135 Function_type*
8136 Call_expression::get_function_type() const
8137 {
8138   return this->fn_->type()->function_type();
8139 }
8140
8141 // Return the number of values which this call will return.
8142
8143 size_t
8144 Call_expression::result_count() const
8145 {
8146   const Function_type* fntype = this->get_function_type();
8147   if (fntype == NULL)
8148     return 0;
8149   if (fntype->results() == NULL)
8150     return 0;
8151   return fntype->results()->size();
8152 }
8153
8154 // Return whether this is a call to the predeclared function recover.
8155
8156 bool
8157 Call_expression::is_recover_call() const
8158 {
8159   return this->do_is_recover_call();
8160 }
8161
8162 // Set the argument to the recover function.
8163
8164 void
8165 Call_expression::set_recover_arg(Expression* arg)
8166 {
8167   this->do_set_recover_arg(arg);
8168 }
8169
8170 // Virtual functions also implemented by Builtin_call_expression.
8171
8172 bool
8173 Call_expression::do_is_recover_call() const
8174 {
8175   return false;
8176 }
8177
8178 void
8179 Call_expression::do_set_recover_arg(Expression*)
8180 {
8181   gcc_unreachable();
8182 }
8183
8184 // Get the type.
8185
8186 Type*
8187 Call_expression::do_type()
8188 {
8189   if (this->type_ != NULL)
8190     return this->type_;
8191
8192   Type* ret;
8193   Function_type* fntype = this->get_function_type();
8194   if (fntype == NULL)
8195     return Type::make_error_type();
8196
8197   const Typed_identifier_list* results = fntype->results();
8198   if (results == NULL)
8199     ret = Type::make_void_type();
8200   else if (results->size() == 1)
8201     ret = results->begin()->type();
8202   else
8203     ret = Type::make_call_multiple_result_type(this);
8204
8205   this->type_ = ret;
8206
8207   return this->type_;
8208 }
8209
8210 // Determine types for a call expression.  We can use the function
8211 // parameter types to set the types of the arguments.
8212
8213 void
8214 Call_expression::do_determine_type(const Type_context*)
8215 {
8216   this->fn_->determine_type_no_context();
8217   Function_type* fntype = this->get_function_type();
8218   const Typed_identifier_list* parameters = NULL;
8219   if (fntype != NULL)
8220     parameters = fntype->parameters();
8221   if (this->args_ != NULL)
8222     {
8223       Typed_identifier_list::const_iterator pt;
8224       if (parameters != NULL)
8225         pt = parameters->begin();
8226       for (Expression_list::const_iterator pa = this->args_->begin();
8227            pa != this->args_->end();
8228            ++pa)
8229         {
8230           if (parameters != NULL && pt != parameters->end())
8231             {
8232               Type_context subcontext(pt->type(), false);
8233               (*pa)->determine_type(&subcontext);
8234               ++pt;
8235             }
8236           else
8237             (*pa)->determine_type_no_context();
8238         }
8239     }
8240 }
8241
8242 // Check types for parameter I.
8243
8244 bool
8245 Call_expression::check_argument_type(int i, const Type* parameter_type,
8246                                      const Type* argument_type,
8247                                      source_location argument_location,
8248                                      bool issued_error)
8249 {
8250   std::string reason;
8251   if (!Type::are_assignable(parameter_type, argument_type, &reason))
8252     {
8253       if (!issued_error)
8254         {
8255           if (reason.empty())
8256             error_at(argument_location, "argument %d has incompatible type", i);
8257           else
8258             error_at(argument_location,
8259                      "argument %d has incompatible type (%s)",
8260                      i, reason.c_str());
8261         }
8262       this->set_is_error();
8263       return false;
8264     }
8265   return true;
8266 }
8267
8268 // Check types.
8269
8270 void
8271 Call_expression::do_check_types(Gogo*)
8272 {
8273   Function_type* fntype = this->get_function_type();
8274   if (fntype == NULL)
8275     {
8276       if (!this->fn_->type()->is_error_type())
8277         this->report_error(_("expected function"));
8278       return;
8279     }
8280
8281   if (fntype->is_method())
8282     {
8283       // We don't support pointers to methods, so the function has to
8284       // be a bound method expression.
8285       Bound_method_expression* bme = this->fn_->bound_method_expression();
8286       if (bme == NULL)
8287         {
8288           this->report_error(_("method call without object"));
8289           return;
8290         }
8291       Type* first_arg_type = bme->first_argument()->type();
8292       if (first_arg_type->points_to() == NULL)
8293         {
8294           // When passing a value, we need to check that we are
8295           // permitted to copy it.
8296           std::string reason;
8297           if (!Type::are_assignable(fntype->receiver()->type(),
8298                                     first_arg_type, &reason))
8299             {
8300               if (reason.empty())
8301                 this->report_error(_("incompatible type for receiver"));
8302               else
8303                 {
8304                   error_at(this->location(),
8305                            "incompatible type for receiver (%s)",
8306                            reason.c_str());
8307                   this->set_is_error();
8308                 }
8309             }
8310         }
8311     }
8312
8313   // Note that varargs was handled by the lower_varargs() method, so
8314   // we don't have to worry about it here.
8315
8316   const Typed_identifier_list* parameters = fntype->parameters();
8317   if (this->args_ == NULL)
8318     {
8319       if (parameters != NULL && !parameters->empty())
8320         this->report_error(_("not enough arguments"));
8321     }
8322   else if (parameters == NULL)
8323     this->report_error(_("too many arguments"));
8324   else
8325     {
8326       int i = 0;
8327       Typed_identifier_list::const_iterator pt = parameters->begin();
8328       for (Expression_list::const_iterator pa = this->args_->begin();
8329            pa != this->args_->end();
8330            ++pa, ++pt, ++i)
8331         {
8332           if (pt == parameters->end())
8333             {
8334               this->report_error(_("too many arguments"));
8335               return;
8336             }
8337           this->check_argument_type(i + 1, pt->type(), (*pa)->type(),
8338                                     (*pa)->location(), false);
8339         }
8340       if (pt != parameters->end())
8341         this->report_error(_("not enough arguments"));
8342     }
8343 }
8344
8345 // Return whether we have to use a temporary variable to ensure that
8346 // we evaluate this call expression in order.  If the call returns no
8347 // results then it will inevitably be executed last.  If the call
8348 // returns more than one result then it will be used with Call_result
8349 // expressions.  So we only have to use a temporary variable if the
8350 // call returns exactly one result.
8351
8352 bool
8353 Call_expression::do_must_eval_in_order() const
8354 {
8355   return this->result_count() == 1;
8356 }
8357
8358 // Get the function and the first argument to use when calling a bound
8359 // method.
8360
8361 tree
8362 Call_expression::bound_method_function(Translate_context* context,
8363                                        Bound_method_expression* bound_method,
8364                                        tree* first_arg_ptr)
8365 {
8366   Expression* first_argument = bound_method->first_argument();
8367   tree first_arg = first_argument->get_tree(context);
8368   if (first_arg == error_mark_node)
8369     return error_mark_node;
8370
8371   // We always pass a pointer to the first argument when calling a
8372   // method.
8373   if (first_argument->type()->points_to() == NULL)
8374     {
8375       tree pointer_to_arg_type = build_pointer_type(TREE_TYPE(first_arg));
8376       if (TREE_ADDRESSABLE(TREE_TYPE(first_arg))
8377           || DECL_P(first_arg)
8378           || TREE_CODE(first_arg) == INDIRECT_REF
8379           || TREE_CODE(first_arg) == COMPONENT_REF)
8380         {
8381           first_arg = build_fold_addr_expr(first_arg);
8382           if (DECL_P(first_arg))
8383             TREE_ADDRESSABLE(first_arg) = 1;
8384         }
8385       else
8386         {
8387           tree tmp = create_tmp_var(TREE_TYPE(first_arg),
8388                                     get_name(first_arg));
8389           DECL_IGNORED_P(tmp) = 0;
8390           DECL_INITIAL(tmp) = first_arg;
8391           first_arg = build2(COMPOUND_EXPR, pointer_to_arg_type,
8392                              build1(DECL_EXPR, void_type_node, tmp),
8393                              build_fold_addr_expr(tmp));
8394           TREE_ADDRESSABLE(tmp) = 1;
8395         }
8396       if (first_arg == error_mark_node)
8397         return error_mark_node;
8398     }
8399
8400   Type* fatype = bound_method->first_argument_type();
8401   if (fatype != NULL)
8402     {
8403       if (fatype->points_to() == NULL)
8404         fatype = Type::make_pointer_type(fatype);
8405       first_arg = fold_convert(fatype->get_tree(context->gogo()), first_arg);
8406       if (first_arg == error_mark_node
8407           || TREE_TYPE(first_arg) == error_mark_node)
8408         return error_mark_node;
8409     }
8410
8411   *first_arg_ptr = first_arg;
8412
8413   return bound_method->method()->get_tree(context);
8414 }
8415
8416 // Get the function and the first argument to use when calling an
8417 // interface method.
8418
8419 tree
8420 Call_expression::interface_method_function(
8421     Translate_context* context,
8422     Interface_field_reference_expression* interface_method,
8423     tree* first_arg_ptr)
8424 {
8425   tree expr = interface_method->expr()->get_tree(context);
8426   if (expr == error_mark_node)
8427     return error_mark_node;
8428   expr = save_expr(expr);
8429   tree first_arg = interface_method->get_underlying_object_tree(context, expr);
8430   if (first_arg == error_mark_node)
8431     return error_mark_node;
8432   *first_arg_ptr = first_arg;
8433   return interface_method->get_function_tree(context, expr);
8434 }
8435
8436 // Build the call expression.
8437
8438 tree
8439 Call_expression::do_get_tree(Translate_context* context)
8440 {
8441   if (this->tree_ != NULL_TREE)
8442     return this->tree_;
8443
8444   Function_type* fntype = this->get_function_type();
8445   if (fntype == NULL)
8446     return error_mark_node;
8447
8448   if (this->fn_->is_error_expression())
8449     return error_mark_node;
8450
8451   Gogo* gogo = context->gogo();
8452   source_location location = this->location();
8453
8454   Func_expression* func = this->fn_->func_expression();
8455   Bound_method_expression* bound_method = this->fn_->bound_method_expression();
8456   Interface_field_reference_expression* interface_method =
8457     this->fn_->interface_field_reference_expression();
8458   const bool has_closure = func != NULL && func->closure() != NULL;
8459   const bool is_method = bound_method != NULL || interface_method != NULL;
8460   gcc_assert(!fntype->is_method() || is_method);
8461
8462   int nargs;
8463   tree* args;
8464   if (this->args_ == NULL || this->args_->empty())
8465     {
8466       nargs = is_method ? 1 : 0;
8467       args = nargs == 0 ? NULL : new tree[nargs];
8468     }
8469   else
8470     {
8471       const Typed_identifier_list* params = fntype->parameters();
8472       gcc_assert(params != NULL);
8473
8474       nargs = this->args_->size();
8475       int i = is_method ? 1 : 0;
8476       nargs += i;
8477       args = new tree[nargs];
8478
8479       Typed_identifier_list::const_iterator pp = params->begin();
8480       Expression_list::const_iterator pe;
8481       for (pe = this->args_->begin();
8482            pe != this->args_->end();
8483            ++pe, ++pp, ++i)
8484         {
8485           tree arg_val = (*pe)->get_tree(context);
8486           args[i] = Expression::convert_for_assignment(context,
8487                                                        pp->type(),
8488                                                        (*pe)->type(),
8489                                                        arg_val,
8490                                                        location);
8491           if (args[i] == error_mark_node)
8492             return error_mark_node;
8493         }
8494       gcc_assert(pp == params->end());
8495       gcc_assert(i == nargs);
8496     }
8497
8498   tree rettype = TREE_TYPE(TREE_TYPE(fntype->get_tree(gogo)));
8499   if (rettype == error_mark_node)
8500     return error_mark_node;
8501
8502   tree fn;
8503   if (has_closure)
8504     fn = func->get_tree_without_closure(gogo);
8505   else if (!is_method)
8506     fn = this->fn_->get_tree(context);
8507   else if (bound_method != NULL)
8508     fn = this->bound_method_function(context, bound_method, &args[0]);
8509   else if (interface_method != NULL)
8510     fn = this->interface_method_function(context, interface_method, &args[0]);
8511   else
8512     gcc_unreachable();
8513
8514   if (fn == error_mark_node || TREE_TYPE(fn) == error_mark_node)
8515     return error_mark_node;
8516
8517   // This is to support builtin math functions when using 80387 math.
8518   tree fndecl = fn;
8519   if (TREE_CODE(fndecl) == ADDR_EXPR)
8520     fndecl = TREE_OPERAND(fndecl, 0);
8521   tree excess_type = NULL_TREE;
8522   if (DECL_P(fndecl)
8523       && DECL_IS_BUILTIN(fndecl)
8524       && DECL_BUILT_IN_CLASS(fndecl) == BUILT_IN_NORMAL
8525       && nargs > 0
8526       && ((SCALAR_FLOAT_TYPE_P(rettype)
8527            && SCALAR_FLOAT_TYPE_P(TREE_TYPE(args[0])))
8528           || (COMPLEX_FLOAT_TYPE_P(rettype)
8529               && COMPLEX_FLOAT_TYPE_P(TREE_TYPE(args[0])))))
8530     {
8531       excess_type = excess_precision_type(TREE_TYPE(args[0]));
8532       if (excess_type != NULL_TREE)
8533         {
8534           tree excess_fndecl = mathfn_built_in(excess_type,
8535                                                DECL_FUNCTION_CODE(fndecl));
8536           if (excess_fndecl == NULL_TREE)
8537             excess_type = NULL_TREE;
8538           else
8539             {
8540               fn = build_fold_addr_expr_loc(location, excess_fndecl);
8541               for (int i = 0; i < nargs; ++i)
8542                 args[i] = ::convert(excess_type, args[i]);
8543             }
8544         }
8545     }
8546
8547   tree ret = build_call_array(excess_type != NULL_TREE ? excess_type : rettype,
8548                               fn, nargs, args);
8549   delete[] args;
8550
8551   SET_EXPR_LOCATION(ret, location);
8552
8553   if (has_closure)
8554     {
8555       tree closure_tree = func->closure()->get_tree(context);
8556       if (closure_tree != error_mark_node)
8557         CALL_EXPR_STATIC_CHAIN(ret) = closure_tree;
8558     }
8559
8560   // If this is a recursive function type which returns itself, as in
8561   //   type F func() F
8562   // we have used ptr_type_node for the return type.  Add a cast here
8563   // to the correct type.
8564   if (TREE_TYPE(ret) == ptr_type_node)
8565     {
8566       tree t = this->type()->get_tree(gogo);
8567       ret = fold_convert_loc(location, t, ret);
8568     }
8569
8570   if (excess_type != NULL_TREE)
8571     {
8572       // Calling convert here can undo our excess precision change.
8573       // That may or may not be a bug in convert_to_real.
8574       ret = build1(NOP_EXPR, rettype, ret);
8575     }
8576
8577   // If there is more than one result, we will refer to the call
8578   // multiple times.
8579   if (fntype->results() != NULL && fntype->results()->size() > 1)
8580     ret = save_expr(ret);
8581
8582   this->tree_ = ret;
8583
8584   return ret;
8585 }
8586
8587 // Make a call expression.
8588
8589 Call_expression*
8590 Expression::make_call(Expression* fn, Expression_list* args, bool is_varargs,
8591                       source_location location)
8592 {
8593   return new Call_expression(fn, args, is_varargs, location);
8594 }
8595
8596 // A single result from a call which returns multiple results.
8597
8598 class Call_result_expression : public Expression
8599 {
8600  public:
8601   Call_result_expression(Call_expression* call, unsigned int index)
8602     : Expression(EXPRESSION_CALL_RESULT, call->location()),
8603       call_(call), index_(index)
8604   { }
8605
8606  protected:
8607   int
8608   do_traverse(Traverse*);
8609
8610   Type*
8611   do_type();
8612
8613   void
8614   do_determine_type(const Type_context*);
8615
8616   void
8617   do_check_types(Gogo*);
8618
8619   Expression*
8620   do_copy()
8621   {
8622     return new Call_result_expression(this->call_->call_expression(),
8623                                       this->index_);
8624   }
8625
8626   bool
8627   do_must_eval_in_order() const
8628   { return true; }
8629
8630   tree
8631   do_get_tree(Translate_context*);
8632
8633  private:
8634   // The underlying call expression.
8635   Expression* call_;
8636   // Which result we want.
8637   unsigned int index_;
8638 };
8639
8640 // Traverse a call result.
8641
8642 int
8643 Call_result_expression::do_traverse(Traverse* traverse)
8644 {
8645   if (traverse->remember_expression(this->call_))
8646     {
8647       // We have already traversed the call expression.
8648       return TRAVERSE_CONTINUE;
8649     }
8650   return Expression::traverse(&this->call_, traverse);
8651 }
8652
8653 // Get the type.
8654
8655 Type*
8656 Call_result_expression::do_type()
8657 {
8658   // THIS->CALL_ can be replaced with a temporary reference due to
8659   // Call_expression::do_must_eval_in_order when there is an error.
8660   Call_expression* ce = this->call_->call_expression();
8661   if (ce == NULL)
8662     return Type::make_error_type();
8663   Function_type* fntype = ce->get_function_type();
8664   if (fntype == NULL)
8665     return Type::make_error_type();
8666   const Typed_identifier_list* results = fntype->results();
8667   Typed_identifier_list::const_iterator pr = results->begin();
8668   for (unsigned int i = 0; i < this->index_; ++i)
8669     {
8670       if (pr == results->end())
8671         return Type::make_error_type();
8672       ++pr;
8673     }
8674   if (pr == results->end())
8675     return Type::make_error_type();
8676   return pr->type();
8677 }
8678
8679 // Check the type.  This is where we give an error if we're trying to
8680 // extract too many values from a call.
8681
8682 void
8683 Call_result_expression::do_check_types(Gogo*)
8684 {
8685   bool ok = true;
8686   Call_expression* ce = this->call_->call_expression();
8687   if (ce != NULL)
8688     ok = this->index_ < ce->result_count();
8689   else
8690     {
8691       // This can happen when the call returns a single value but we
8692       // are asking for the second result.
8693       if (this->call_->is_error_expression())
8694         return;
8695       ok = false;
8696     }
8697   if (!ok)
8698     this->report_error(_("number of results does not match number of values"));
8699 }
8700
8701 // Determine the type.  We have nothing to do here, but the 0 result
8702 // needs to pass down to the caller.
8703
8704 void
8705 Call_result_expression::do_determine_type(const Type_context*)
8706 {
8707   if (this->index_ == 0)
8708     this->call_->determine_type_no_context();
8709 }
8710
8711 // Return the tree.
8712
8713 tree
8714 Call_result_expression::do_get_tree(Translate_context* context)
8715 {
8716   tree call_tree = this->call_->get_tree(context);
8717   if (call_tree == error_mark_node)
8718     return error_mark_node;
8719   gcc_assert(TREE_CODE(TREE_TYPE(call_tree)) == RECORD_TYPE);
8720   tree field = TYPE_FIELDS(TREE_TYPE(call_tree));
8721   for (unsigned int i = 0; i < this->index_; ++i)
8722     {
8723       gcc_assert(field != NULL_TREE);
8724       field = DECL_CHAIN(field);
8725     }
8726   gcc_assert(field != NULL_TREE);
8727   return build3(COMPONENT_REF, TREE_TYPE(field), call_tree, field, NULL_TREE);
8728 }
8729
8730 // Make a reference to a single result of a call which returns
8731 // multiple results.
8732
8733 Expression*
8734 Expression::make_call_result(Call_expression* call, unsigned int index)
8735 {
8736   return new Call_result_expression(call, index);
8737 }
8738
8739 // Class Index_expression.
8740
8741 // Traversal.
8742
8743 int
8744 Index_expression::do_traverse(Traverse* traverse)
8745 {
8746   if (Expression::traverse(&this->left_, traverse) == TRAVERSE_EXIT
8747       || Expression::traverse(&this->start_, traverse) == TRAVERSE_EXIT
8748       || (this->end_ != NULL
8749           && Expression::traverse(&this->end_, traverse) == TRAVERSE_EXIT))
8750     return TRAVERSE_EXIT;
8751   return TRAVERSE_CONTINUE;
8752 }
8753
8754 // Lower an index expression.  This converts the generic index
8755 // expression into an array index, a string index, or a map index.
8756
8757 Expression*
8758 Index_expression::do_lower(Gogo*, Named_object*, int)
8759 {
8760   source_location location = this->location();
8761   Expression* left = this->left_;
8762   Expression* start = this->start_;
8763   Expression* end = this->end_;
8764
8765   Type* type = left->type();
8766   if (type->is_error_type())
8767     return Expression::make_error(location);
8768   else if (type->array_type() != NULL)
8769     return Expression::make_array_index(left, start, end, location);
8770   else if (type->points_to() != NULL
8771            && type->points_to()->array_type() != NULL
8772            && !type->points_to()->is_open_array_type())
8773     {
8774       Expression* deref = Expression::make_unary(OPERATOR_MULT, left,
8775                                                  location);
8776       return Expression::make_array_index(deref, start, end, location);
8777     }
8778   else if (type->is_string_type())
8779     return Expression::make_string_index(left, start, end, location);
8780   else if (type->map_type() != NULL)
8781     {
8782       if (end != NULL)
8783         {
8784           error_at(location, "invalid slice of map");
8785           return Expression::make_error(location);
8786         }
8787       Map_index_expression* ret= Expression::make_map_index(left, start,
8788                                                             location);
8789       if (this->is_lvalue_)
8790         ret->set_is_lvalue();
8791       return ret;
8792     }
8793   else
8794     {
8795       error_at(location,
8796                "attempt to index object which is not array, string, or map");
8797       return Expression::make_error(location);
8798     }
8799 }
8800
8801 // Make an index expression.
8802
8803 Expression*
8804 Expression::make_index(Expression* left, Expression* start, Expression* end,
8805                        source_location location)
8806 {
8807   return new Index_expression(left, start, end, location);
8808 }
8809
8810 // An array index.  This is used for both indexing and slicing.
8811
8812 class Array_index_expression : public Expression
8813 {
8814  public:
8815   Array_index_expression(Expression* array, Expression* start,
8816                          Expression* end, source_location location)
8817     : Expression(EXPRESSION_ARRAY_INDEX, location),
8818       array_(array), start_(start), end_(end), type_(NULL)
8819   { }
8820
8821  protected:
8822   int
8823   do_traverse(Traverse*);
8824
8825   Type*
8826   do_type();
8827
8828   void
8829   do_determine_type(const Type_context*);
8830
8831   void
8832   do_check_types(Gogo*);
8833
8834   Expression*
8835   do_copy()
8836   {
8837     return Expression::make_array_index(this->array_->copy(),
8838                                         this->start_->copy(),
8839                                         (this->end_ == NULL
8840                                          ? NULL
8841                                          : this->end_->copy()),
8842                                         this->location());
8843   }
8844
8845   bool
8846   do_is_addressable() const;
8847
8848   void
8849   do_address_taken(bool escapes)
8850   { this->array_->address_taken(escapes); }
8851
8852   tree
8853   do_get_tree(Translate_context*);
8854
8855  private:
8856   // The array we are getting a value from.
8857   Expression* array_;
8858   // The start or only index.
8859   Expression* start_;
8860   // The end index of a slice.  This may be NULL for a simple array
8861   // index, or it may be a nil expression for the length of the array.
8862   Expression* end_;
8863   // The type of the expression.
8864   Type* type_;
8865 };
8866
8867 // Array index traversal.
8868
8869 int
8870 Array_index_expression::do_traverse(Traverse* traverse)
8871 {
8872   if (Expression::traverse(&this->array_, traverse) == TRAVERSE_EXIT)
8873     return TRAVERSE_EXIT;
8874   if (Expression::traverse(&this->start_, traverse) == TRAVERSE_EXIT)
8875     return TRAVERSE_EXIT;
8876   if (this->end_ != NULL)
8877     {
8878       if (Expression::traverse(&this->end_, traverse) == TRAVERSE_EXIT)
8879         return TRAVERSE_EXIT;
8880     }
8881   return TRAVERSE_CONTINUE;
8882 }
8883
8884 // Return the type of an array index.
8885
8886 Type*
8887 Array_index_expression::do_type()
8888 {
8889   if (this->type_ == NULL)
8890     {
8891      Array_type* type = this->array_->type()->array_type();
8892       if (type == NULL)
8893         this->type_ = Type::make_error_type();
8894       else if (this->end_ == NULL)
8895         this->type_ = type->element_type();
8896       else if (type->is_open_array_type())
8897         {
8898           // A slice of a slice has the same type as the original
8899           // slice.
8900           this->type_ = this->array_->type()->deref();
8901         }
8902       else
8903         {
8904           // A slice of an array is a slice.
8905           this->type_ = Type::make_array_type(type->element_type(), NULL);
8906         }
8907     }
8908   return this->type_;
8909 }
8910
8911 // Set the type of an array index.
8912
8913 void
8914 Array_index_expression::do_determine_type(const Type_context*)
8915 {
8916   this->array_->determine_type_no_context();
8917   Type_context subcontext(NULL, true);
8918   this->start_->determine_type(&subcontext);
8919   if (this->end_ != NULL)
8920     this->end_->determine_type(&subcontext);
8921 }
8922
8923 // Check types of an array index.
8924
8925 void
8926 Array_index_expression::do_check_types(Gogo*)
8927 {
8928   if (this->start_->type()->integer_type() == NULL)
8929     this->report_error(_("index must be integer"));
8930   if (this->end_ != NULL
8931       && this->end_->type()->integer_type() == NULL
8932       && !this->end_->is_nil_expression())
8933     this->report_error(_("slice end must be integer"));
8934
8935   Array_type* array_type = this->array_->type()->array_type();
8936   gcc_assert(array_type != NULL);
8937
8938   unsigned int int_bits =
8939     Type::lookup_integer_type("int")->integer_type()->bits();
8940
8941   Type* dummy;
8942   mpz_t lval;
8943   mpz_init(lval);
8944   bool lval_valid = (array_type->length() != NULL
8945                      && array_type->length()->integer_constant_value(true,
8946                                                                      lval,
8947                                                                      &dummy));
8948   mpz_t ival;
8949   mpz_init(ival);
8950   if (this->start_->integer_constant_value(true, ival, &dummy))
8951     {
8952       if (mpz_sgn(ival) < 0
8953           || mpz_sizeinbase(ival, 2) >= int_bits
8954           || (lval_valid
8955               && (this->end_ == NULL
8956                   ? mpz_cmp(ival, lval) >= 0
8957                   : mpz_cmp(ival, lval) > 0)))
8958         {
8959           error_at(this->start_->location(), "array index out of bounds");
8960           this->set_is_error();
8961         }
8962     }
8963   if (this->end_ != NULL && !this->end_->is_nil_expression())
8964     {
8965       if (this->end_->integer_constant_value(true, ival, &dummy))
8966         {
8967           if (mpz_sgn(ival) < 0
8968               || mpz_sizeinbase(ival, 2) >= int_bits
8969               || (lval_valid && mpz_cmp(ival, lval) > 0))
8970             {
8971               error_at(this->end_->location(), "array index out of bounds");
8972               this->set_is_error();
8973             }
8974         }
8975     }
8976   mpz_clear(ival);
8977   mpz_clear(lval);
8978
8979   // A slice of an array requires an addressable array.  A slice of a
8980   // slice is always possible.
8981   if (this->end_ != NULL
8982       && !array_type->is_open_array_type()
8983       && !this->array_->is_addressable())
8984     this->report_error(_("array is not addressable"));
8985 }
8986
8987 // Return whether this expression is addressable.
8988
8989 bool
8990 Array_index_expression::do_is_addressable() const
8991 {
8992   // A slice expression is not addressable.
8993   if (this->end_ != NULL)
8994     return false;
8995
8996   // An index into a slice is addressable.
8997   if (this->array_->type()->is_open_array_type())
8998     return true;
8999
9000   // An index into an array is addressable if the array is
9001   // addressable.
9002   return this->array_->is_addressable();
9003 }
9004
9005 // Get a tree for an array index.
9006
9007 tree
9008 Array_index_expression::do_get_tree(Translate_context* context)
9009 {
9010   Gogo* gogo = context->gogo();
9011   source_location loc = this->location();
9012
9013   Array_type* array_type = this->array_->type()->array_type();
9014   gcc_assert(array_type != NULL);
9015
9016   tree type_tree = array_type->get_tree(gogo);
9017   if (type_tree == error_mark_node)
9018     return error_mark_node;
9019
9020   tree array_tree = this->array_->get_tree(context);
9021   if (array_tree == error_mark_node)
9022     return error_mark_node;
9023
9024   if (array_type->length() == NULL && !DECL_P(array_tree))
9025     array_tree = save_expr(array_tree);
9026   tree length_tree = array_type->length_tree(gogo, array_tree);
9027   if (length_tree == error_mark_node)
9028     return error_mark_node;
9029   length_tree = save_expr(length_tree);
9030   tree length_type = TREE_TYPE(length_tree);
9031
9032   tree bad_index = boolean_false_node;
9033
9034   tree start_tree = this->start_->get_tree(context);
9035   if (start_tree == error_mark_node)
9036     return error_mark_node;
9037   if (!DECL_P(start_tree))
9038     start_tree = save_expr(start_tree);
9039   if (!INTEGRAL_TYPE_P(TREE_TYPE(start_tree)))
9040     start_tree = convert_to_integer(length_type, start_tree);
9041
9042   bad_index = Expression::check_bounds(start_tree, length_type, bad_index,
9043                                        loc);
9044
9045   start_tree = fold_convert_loc(loc, length_type, start_tree);
9046   bad_index = fold_build2_loc(loc, TRUTH_OR_EXPR, boolean_type_node, bad_index,
9047                               fold_build2_loc(loc,
9048                                               (this->end_ == NULL
9049                                                ? GE_EXPR
9050                                                : GT_EXPR),
9051                                               boolean_type_node, start_tree,
9052                                               length_tree));
9053
9054   int code = (array_type->length() != NULL
9055               ? (this->end_ == NULL
9056                  ? RUNTIME_ERROR_ARRAY_INDEX_OUT_OF_BOUNDS
9057                  : RUNTIME_ERROR_ARRAY_SLICE_OUT_OF_BOUNDS)
9058               : (this->end_ == NULL
9059                  ? RUNTIME_ERROR_SLICE_INDEX_OUT_OF_BOUNDS
9060                  : RUNTIME_ERROR_SLICE_SLICE_OUT_OF_BOUNDS));
9061   tree crash = Gogo::runtime_error(code, loc);
9062
9063   if (this->end_ == NULL)
9064     {
9065       // Simple array indexing.  This has to return an l-value, so
9066       // wrap the index check into START_TREE.
9067       start_tree = build2(COMPOUND_EXPR, TREE_TYPE(start_tree),
9068                           build3(COND_EXPR, void_type_node,
9069                                  bad_index, crash, NULL_TREE),
9070                           start_tree);
9071       start_tree = fold_convert_loc(loc, sizetype, start_tree);
9072
9073       if (array_type->length() != NULL)
9074         {
9075           // Fixed array.
9076           return build4(ARRAY_REF, TREE_TYPE(type_tree), array_tree,
9077                         start_tree, NULL_TREE, NULL_TREE);
9078         }
9079       else
9080         {
9081           // Open array.
9082           tree values = array_type->value_pointer_tree(gogo, array_tree);
9083           tree element_type_tree = array_type->element_type()->get_tree(gogo);
9084           if (element_type_tree == error_mark_node)
9085             return error_mark_node;
9086           tree element_size = TYPE_SIZE_UNIT(element_type_tree);
9087           tree offset = fold_build2_loc(loc, MULT_EXPR, sizetype,
9088                                         start_tree, element_size);
9089           tree ptr = fold_build2_loc(loc, POINTER_PLUS_EXPR,
9090                                      TREE_TYPE(values), values, offset);
9091           return build_fold_indirect_ref(ptr);
9092         }
9093     }
9094
9095   // Array slice.
9096
9097   tree capacity_tree = array_type->capacity_tree(gogo, array_tree);
9098   if (capacity_tree == error_mark_node)
9099     return error_mark_node;
9100   capacity_tree = fold_convert_loc(loc, length_type, capacity_tree);
9101
9102   tree end_tree;
9103   if (this->end_->is_nil_expression())
9104     end_tree = length_tree;
9105   else
9106     {
9107       end_tree = this->end_->get_tree(context);
9108       if (end_tree == error_mark_node)
9109         return error_mark_node;
9110       if (!DECL_P(end_tree))
9111         end_tree = save_expr(end_tree);
9112       if (!INTEGRAL_TYPE_P(TREE_TYPE(end_tree)))
9113         end_tree = convert_to_integer(length_type, end_tree);
9114
9115       bad_index = Expression::check_bounds(end_tree, length_type, bad_index,
9116                                            loc);
9117
9118       end_tree = fold_convert_loc(loc, length_type, end_tree);
9119
9120       capacity_tree = save_expr(capacity_tree);
9121       tree bad_end = fold_build2_loc(loc, TRUTH_OR_EXPR, boolean_type_node,
9122                                      fold_build2_loc(loc, LT_EXPR,
9123                                                      boolean_type_node,
9124                                                      end_tree, start_tree),
9125                                      fold_build2_loc(loc, GT_EXPR,
9126                                                      boolean_type_node,
9127                                                      end_tree, capacity_tree));
9128       bad_index = fold_build2_loc(loc, TRUTH_OR_EXPR, boolean_type_node,
9129                                   bad_index, bad_end);
9130     }
9131
9132   tree element_type_tree = array_type->element_type()->get_tree(gogo);
9133   if (element_type_tree == error_mark_node)
9134     return error_mark_node;
9135   tree element_size = TYPE_SIZE_UNIT(element_type_tree);
9136
9137   tree offset = fold_build2_loc(loc, MULT_EXPR, sizetype,
9138                                 fold_convert_loc(loc, sizetype, start_tree),
9139                                 element_size);
9140
9141   tree value_pointer = array_type->value_pointer_tree(gogo, array_tree);
9142   if (value_pointer == error_mark_node)
9143     return error_mark_node;
9144
9145   value_pointer = fold_build2_loc(loc, POINTER_PLUS_EXPR,
9146                                   TREE_TYPE(value_pointer),
9147                                   value_pointer, offset);
9148
9149   tree result_length_tree = fold_build2_loc(loc, MINUS_EXPR, length_type,
9150                                             end_tree, start_tree);
9151
9152   tree result_capacity_tree = fold_build2_loc(loc, MINUS_EXPR, length_type,
9153                                               capacity_tree, start_tree);
9154
9155   tree struct_tree = this->type()->get_tree(gogo);
9156   gcc_assert(TREE_CODE(struct_tree) == RECORD_TYPE);
9157
9158   VEC(constructor_elt,gc)* init = VEC_alloc(constructor_elt, gc, 3);
9159
9160   constructor_elt* elt = VEC_quick_push(constructor_elt, init, NULL);
9161   tree field = TYPE_FIELDS(struct_tree);
9162   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__values") == 0);
9163   elt->index = field;
9164   elt->value = value_pointer;
9165
9166   elt = VEC_quick_push(constructor_elt, init, NULL);
9167   field = DECL_CHAIN(field);
9168   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__count") == 0);
9169   elt->index = field;
9170   elt->value = fold_convert_loc(loc, TREE_TYPE(field), result_length_tree);
9171
9172   elt = VEC_quick_push(constructor_elt, init, NULL);
9173   field = DECL_CHAIN(field);
9174   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__capacity") == 0);
9175   elt->index = field;
9176   elt->value = fold_convert_loc(loc, TREE_TYPE(field), result_capacity_tree);
9177
9178   tree constructor = build_constructor(struct_tree, init);
9179
9180   if (TREE_CONSTANT(value_pointer)
9181       && TREE_CONSTANT(result_length_tree)
9182       && TREE_CONSTANT(result_capacity_tree))
9183     TREE_CONSTANT(constructor) = 1;
9184
9185   return fold_build2_loc(loc, COMPOUND_EXPR, TREE_TYPE(constructor),
9186                          build3(COND_EXPR, void_type_node,
9187                                 bad_index, crash, NULL_TREE),
9188                          constructor);
9189 }
9190
9191 // Make an array index expression.  END may be NULL.
9192
9193 Expression*
9194 Expression::make_array_index(Expression* array, Expression* start,
9195                              Expression* end, source_location location)
9196 {
9197   // Taking a slice of a composite literal requires moving the literal
9198   // onto the heap.
9199   if (end != NULL && array->is_composite_literal())
9200     {
9201       array = Expression::make_heap_composite(array, location);
9202       array = Expression::make_unary(OPERATOR_MULT, array, location);
9203     }
9204   return new Array_index_expression(array, start, end, location);
9205 }
9206
9207 // A string index.  This is used for both indexing and slicing.
9208
9209 class String_index_expression : public Expression
9210 {
9211  public:
9212   String_index_expression(Expression* string, Expression* start,
9213                           Expression* end, source_location location)
9214     : Expression(EXPRESSION_STRING_INDEX, location),
9215       string_(string), start_(start), end_(end)
9216   { }
9217
9218  protected:
9219   int
9220   do_traverse(Traverse*);
9221
9222   Type*
9223   do_type();
9224
9225   void
9226   do_determine_type(const Type_context*);
9227
9228   void
9229   do_check_types(Gogo*);
9230
9231   Expression*
9232   do_copy()
9233   {
9234     return Expression::make_string_index(this->string_->copy(),
9235                                          this->start_->copy(),
9236                                          (this->end_ == NULL
9237                                           ? NULL
9238                                           : this->end_->copy()),
9239                                          this->location());
9240   }
9241
9242   tree
9243   do_get_tree(Translate_context*);
9244
9245  private:
9246   // The string we are getting a value from.
9247   Expression* string_;
9248   // The start or only index.
9249   Expression* start_;
9250   // The end index of a slice.  This may be NULL for a single index,
9251   // or it may be a nil expression for the length of the string.
9252   Expression* end_;
9253 };
9254
9255 // String index traversal.
9256
9257 int
9258 String_index_expression::do_traverse(Traverse* traverse)
9259 {
9260   if (Expression::traverse(&this->string_, traverse) == TRAVERSE_EXIT)
9261     return TRAVERSE_EXIT;
9262   if (Expression::traverse(&this->start_, traverse) == TRAVERSE_EXIT)
9263     return TRAVERSE_EXIT;
9264   if (this->end_ != NULL)
9265     {
9266       if (Expression::traverse(&this->end_, traverse) == TRAVERSE_EXIT)
9267         return TRAVERSE_EXIT;
9268     }
9269   return TRAVERSE_CONTINUE;
9270 }
9271
9272 // Return the type of a string index.
9273
9274 Type*
9275 String_index_expression::do_type()
9276 {
9277   if (this->end_ == NULL)
9278     return Type::lookup_integer_type("uint8");
9279   else
9280     return Type::make_string_type();
9281 }
9282
9283 // Determine the type of a string index.
9284
9285 void
9286 String_index_expression::do_determine_type(const Type_context*)
9287 {
9288   this->string_->determine_type_no_context();
9289   Type_context subcontext(NULL, true);
9290   this->start_->determine_type(&subcontext);
9291   if (this->end_ != NULL)
9292     this->end_->determine_type(&subcontext);
9293 }
9294
9295 // Check types of a string index.
9296
9297 void
9298 String_index_expression::do_check_types(Gogo*)
9299 {
9300   if (this->start_->type()->integer_type() == NULL)
9301     this->report_error(_("index must be integer"));
9302   if (this->end_ != NULL
9303       && this->end_->type()->integer_type() == NULL
9304       && !this->end_->is_nil_expression())
9305     this->report_error(_("slice end must be integer"));
9306
9307   std::string sval;
9308   bool sval_valid = this->string_->string_constant_value(&sval);
9309
9310   mpz_t ival;
9311   mpz_init(ival);
9312   Type* dummy;
9313   if (this->start_->integer_constant_value(true, ival, &dummy))
9314     {
9315       if (mpz_sgn(ival) < 0
9316           || (sval_valid && mpz_cmp_ui(ival, sval.length()) >= 0))
9317         {
9318           error_at(this->start_->location(), "string index out of bounds");
9319           this->set_is_error();
9320         }
9321     }
9322   if (this->end_ != NULL && !this->end_->is_nil_expression())
9323     {
9324       if (this->end_->integer_constant_value(true, ival, &dummy))
9325         {
9326           if (mpz_sgn(ival) < 0
9327               || (sval_valid && mpz_cmp_ui(ival, sval.length()) > 0))
9328             {
9329               error_at(this->end_->location(), "string index out of bounds");
9330               this->set_is_error();
9331             }
9332         }
9333     }
9334   mpz_clear(ival);
9335 }
9336
9337 // Get a tree for a string index.
9338
9339 tree
9340 String_index_expression::do_get_tree(Translate_context* context)
9341 {
9342   source_location loc = this->location();
9343
9344   tree string_tree = this->string_->get_tree(context);
9345   if (string_tree == error_mark_node)
9346     return error_mark_node;
9347
9348   if (this->string_->type()->points_to() != NULL)
9349     string_tree = build_fold_indirect_ref(string_tree);
9350   if (!DECL_P(string_tree))
9351     string_tree = save_expr(string_tree);
9352   tree string_type = TREE_TYPE(string_tree);
9353
9354   tree length_tree = String_type::length_tree(context->gogo(), string_tree);
9355   length_tree = save_expr(length_tree);
9356   tree length_type = TREE_TYPE(length_tree);
9357
9358   tree bad_index = boolean_false_node;
9359
9360   tree start_tree = this->start_->get_tree(context);
9361   if (start_tree == error_mark_node)
9362     return error_mark_node;
9363   if (!DECL_P(start_tree))
9364     start_tree = save_expr(start_tree);
9365   if (!INTEGRAL_TYPE_P(TREE_TYPE(start_tree)))
9366     start_tree = convert_to_integer(length_type, start_tree);
9367
9368   bad_index = Expression::check_bounds(start_tree, length_type, bad_index,
9369                                        loc);
9370
9371   start_tree = fold_convert_loc(loc, length_type, start_tree);
9372
9373   int code = (this->end_ == NULL
9374               ? RUNTIME_ERROR_STRING_INDEX_OUT_OF_BOUNDS
9375               : RUNTIME_ERROR_STRING_SLICE_OUT_OF_BOUNDS);
9376   tree crash = Gogo::runtime_error(code, loc);
9377
9378   if (this->end_ == NULL)
9379     {
9380       bad_index = fold_build2_loc(loc, TRUTH_OR_EXPR, boolean_type_node,
9381                                   bad_index,
9382                                   fold_build2_loc(loc, GE_EXPR,
9383                                                   boolean_type_node,
9384                                                   start_tree, length_tree));
9385
9386       tree bytes_tree = String_type::bytes_tree(context->gogo(), string_tree);
9387       tree ptr = fold_build2_loc(loc, POINTER_PLUS_EXPR, TREE_TYPE(bytes_tree),
9388                                  bytes_tree,
9389                                  fold_convert_loc(loc, sizetype, start_tree));
9390       tree index = build_fold_indirect_ref_loc(loc, ptr);
9391
9392       return build2(COMPOUND_EXPR, TREE_TYPE(index),
9393                     build3(COND_EXPR, void_type_node,
9394                            bad_index, crash, NULL_TREE),
9395                     index);
9396     }
9397   else
9398     {
9399       tree end_tree;
9400       if (this->end_->is_nil_expression())
9401         end_tree = build_int_cst(length_type, -1);
9402       else
9403         {
9404           end_tree = this->end_->get_tree(context);
9405           if (end_tree == error_mark_node)
9406             return error_mark_node;
9407           if (!DECL_P(end_tree))
9408             end_tree = save_expr(end_tree);
9409           if (!INTEGRAL_TYPE_P(TREE_TYPE(end_tree)))
9410             end_tree = convert_to_integer(length_type, end_tree);
9411
9412           bad_index = Expression::check_bounds(end_tree, length_type,
9413                                                bad_index, loc);
9414
9415           end_tree = fold_convert_loc(loc, length_type, end_tree);
9416         }
9417
9418       static tree strslice_fndecl;
9419       tree ret = Gogo::call_builtin(&strslice_fndecl,
9420                                     loc,
9421                                     "__go_string_slice",
9422                                     3,
9423                                     string_type,
9424                                     string_type,
9425                                     string_tree,
9426                                     length_type,
9427                                     start_tree,
9428                                     length_type,
9429                                     end_tree);
9430       if (ret == error_mark_node)
9431         return error_mark_node;
9432       // This will panic if the bounds are out of range for the
9433       // string.
9434       TREE_NOTHROW(strslice_fndecl) = 0;
9435
9436       if (bad_index == boolean_false_node)
9437         return ret;
9438       else
9439         return build2(COMPOUND_EXPR, TREE_TYPE(ret),
9440                       build3(COND_EXPR, void_type_node,
9441                              bad_index, crash, NULL_TREE),
9442                       ret);
9443     }
9444 }
9445
9446 // Make a string index expression.  END may be NULL.
9447
9448 Expression*
9449 Expression::make_string_index(Expression* string, Expression* start,
9450                               Expression* end, source_location location)
9451 {
9452   return new String_index_expression(string, start, end, location);
9453 }
9454
9455 // Class Map_index.
9456
9457 // Get the type of the map.
9458
9459 Map_type*
9460 Map_index_expression::get_map_type() const
9461 {
9462   Map_type* mt = this->map_->type()->deref()->map_type();
9463   gcc_assert(mt != NULL);
9464   return mt;
9465 }
9466
9467 // Map index traversal.
9468
9469 int
9470 Map_index_expression::do_traverse(Traverse* traverse)
9471 {
9472   if (Expression::traverse(&this->map_, traverse) == TRAVERSE_EXIT)
9473     return TRAVERSE_EXIT;
9474   return Expression::traverse(&this->index_, traverse);
9475 }
9476
9477 // Return the type of a map index.
9478
9479 Type*
9480 Map_index_expression::do_type()
9481 {
9482   Type* type = this->get_map_type()->val_type();
9483   // If this map index is in a tuple assignment, we actually return a
9484   // pointer to the value type.  Tuple_map_assignment_statement is
9485   // responsible for handling this correctly.  We need to get the type
9486   // right in case this gets assigned to a temporary variable.
9487   if (this->is_in_tuple_assignment_)
9488     type = Type::make_pointer_type(type);
9489   return type;
9490 }
9491
9492 // Fix the type of a map index.
9493
9494 void
9495 Map_index_expression::do_determine_type(const Type_context*)
9496 {
9497   this->map_->determine_type_no_context();
9498   Type_context subcontext(this->get_map_type()->key_type(), false);
9499   this->index_->determine_type(&subcontext);
9500 }
9501
9502 // Check types of a map index.
9503
9504 void
9505 Map_index_expression::do_check_types(Gogo*)
9506 {
9507   std::string reason;
9508   if (!Type::are_assignable(this->get_map_type()->key_type(),
9509                             this->index_->type(), &reason))
9510     {
9511       if (reason.empty())
9512         this->report_error(_("incompatible type for map index"));
9513       else
9514         {
9515           error_at(this->location(), "incompatible type for map index (%s)",
9516                    reason.c_str());
9517           this->set_is_error();
9518         }
9519     }
9520 }
9521
9522 // Get a tree for a map index.
9523
9524 tree
9525 Map_index_expression::do_get_tree(Translate_context* context)
9526 {
9527   Map_type* type = this->get_map_type();
9528
9529   tree valptr = this->get_value_pointer(context, this->is_lvalue_);
9530   if (valptr == error_mark_node)
9531     return error_mark_node;
9532   valptr = save_expr(valptr);
9533
9534   tree val_type_tree = TREE_TYPE(TREE_TYPE(valptr));
9535
9536   if (this->is_lvalue_)
9537     return build_fold_indirect_ref(valptr);
9538   else if (this->is_in_tuple_assignment_)
9539     {
9540       // Tuple_map_assignment_statement is responsible for using this
9541       // appropriately.
9542       return valptr;
9543     }
9544   else
9545     {
9546       return fold_build3(COND_EXPR, val_type_tree,
9547                          fold_build2(EQ_EXPR, boolean_type_node, valptr,
9548                                      fold_convert(TREE_TYPE(valptr),
9549                                                   null_pointer_node)),
9550                          type->val_type()->get_init_tree(context->gogo(),
9551                                                          false),
9552                          build_fold_indirect_ref(valptr));
9553     }
9554 }
9555
9556 // Get a tree for the map index.  This returns a tree which evaluates
9557 // to a pointer to a value.  The pointer will be NULL if the key is
9558 // not in the map.
9559
9560 tree
9561 Map_index_expression::get_value_pointer(Translate_context* context,
9562                                         bool insert)
9563 {
9564   Map_type* type = this->get_map_type();
9565
9566   tree map_tree = this->map_->get_tree(context);
9567   tree index_tree = this->index_->get_tree(context);
9568   index_tree = Expression::convert_for_assignment(context, type->key_type(),
9569                                                   this->index_->type(),
9570                                                   index_tree,
9571                                                   this->location());
9572   if (map_tree == error_mark_node || index_tree == error_mark_node)
9573     return error_mark_node;
9574
9575   if (this->map_->type()->points_to() != NULL)
9576     map_tree = build_fold_indirect_ref(map_tree);
9577
9578   // We need to pass in a pointer to the key, so stuff it into a
9579   // variable.
9580   tree tmp = create_tmp_var(TREE_TYPE(index_tree), get_name(index_tree));
9581   DECL_IGNORED_P(tmp) = 0;
9582   DECL_INITIAL(tmp) = index_tree;
9583   tree make_tmp = build1(DECL_EXPR, void_type_node, tmp);
9584   tree tmpref = fold_convert(const_ptr_type_node, build_fold_addr_expr(tmp));
9585   TREE_ADDRESSABLE(tmp) = 1;
9586
9587   static tree map_index_fndecl;
9588   tree call = Gogo::call_builtin(&map_index_fndecl,
9589                                  this->location(),
9590                                  "__go_map_index",
9591                                  3,
9592                                  const_ptr_type_node,
9593                                  TREE_TYPE(map_tree),
9594                                  map_tree,
9595                                  const_ptr_type_node,
9596                                  tmpref,
9597                                  boolean_type_node,
9598                                  (insert
9599                                   ? boolean_true_node
9600                                   : boolean_false_node));
9601   if (call == error_mark_node)
9602     return error_mark_node;
9603   // This can panic on a map of interface type if the interface holds
9604   // an uncomparable or unhashable type.
9605   TREE_NOTHROW(map_index_fndecl) = 0;
9606
9607   tree val_type_tree = type->val_type()->get_tree(context->gogo());
9608   if (val_type_tree == error_mark_node)
9609     return error_mark_node;
9610   tree ptr_val_type_tree = build_pointer_type(val_type_tree);
9611
9612   return build2(COMPOUND_EXPR, ptr_val_type_tree,
9613                 make_tmp,
9614                 fold_convert(ptr_val_type_tree, call));
9615 }
9616
9617 // Make a map index expression.
9618
9619 Map_index_expression*
9620 Expression::make_map_index(Expression* map, Expression* index,
9621                            source_location location)
9622 {
9623   return new Map_index_expression(map, index, location);
9624 }
9625
9626 // Class Field_reference_expression.
9627
9628 // Return the type of a field reference.
9629
9630 Type*
9631 Field_reference_expression::do_type()
9632 {
9633   Struct_type* struct_type = this->expr_->type()->struct_type();
9634   gcc_assert(struct_type != NULL);
9635   return struct_type->field(this->field_index_)->type();
9636 }
9637
9638 // Check the types for a field reference.
9639
9640 void
9641 Field_reference_expression::do_check_types(Gogo*)
9642 {
9643   Struct_type* struct_type = this->expr_->type()->struct_type();
9644   gcc_assert(struct_type != NULL);
9645   gcc_assert(struct_type->field(this->field_index_) != NULL);
9646 }
9647
9648 // Get a tree for a field reference.
9649
9650 tree
9651 Field_reference_expression::do_get_tree(Translate_context* context)
9652 {
9653   tree struct_tree = this->expr_->get_tree(context);
9654   if (struct_tree == error_mark_node
9655       || TREE_TYPE(struct_tree) == error_mark_node)
9656     return error_mark_node;
9657   gcc_assert(TREE_CODE(TREE_TYPE(struct_tree)) == RECORD_TYPE);
9658   tree field = TYPE_FIELDS(TREE_TYPE(struct_tree));
9659   if (field == NULL_TREE)
9660     {
9661       // This can happen for a type which refers to itself indirectly
9662       // and then turns out to be erroneous.
9663       gcc_assert(saw_errors());
9664       return error_mark_node;
9665     }
9666   for (unsigned int i = this->field_index_; i > 0; --i)
9667     {
9668       field = DECL_CHAIN(field);
9669       gcc_assert(field != NULL_TREE);
9670     }
9671   return build3(COMPONENT_REF, TREE_TYPE(field), struct_tree, field,
9672                 NULL_TREE);
9673 }
9674
9675 // Make a reference to a qualified identifier in an expression.
9676
9677 Field_reference_expression*
9678 Expression::make_field_reference(Expression* expr, unsigned int field_index,
9679                                  source_location location)
9680 {
9681   return new Field_reference_expression(expr, field_index, location);
9682 }
9683
9684 // Class Interface_field_reference_expression.
9685
9686 // Return a tree for the pointer to the function to call.
9687
9688 tree
9689 Interface_field_reference_expression::get_function_tree(Translate_context*,
9690                                                         tree expr)
9691 {
9692   if (this->expr_->type()->points_to() != NULL)
9693     expr = build_fold_indirect_ref(expr);
9694
9695   tree expr_type = TREE_TYPE(expr);
9696   gcc_assert(TREE_CODE(expr_type) == RECORD_TYPE);
9697
9698   tree field = TYPE_FIELDS(expr_type);
9699   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__methods") == 0);
9700
9701   tree table = build3(COMPONENT_REF, TREE_TYPE(field), expr, field, NULL_TREE);
9702   gcc_assert(POINTER_TYPE_P(TREE_TYPE(table)));
9703
9704   table = build_fold_indirect_ref(table);
9705   gcc_assert(TREE_CODE(TREE_TYPE(table)) == RECORD_TYPE);
9706
9707   std::string name = Gogo::unpack_hidden_name(this->name_);
9708   for (field = DECL_CHAIN(TYPE_FIELDS(TREE_TYPE(table)));
9709        field != NULL_TREE;
9710        field = DECL_CHAIN(field))
9711     {
9712       if (name == IDENTIFIER_POINTER(DECL_NAME(field)))
9713         break;
9714     }
9715   gcc_assert(field != NULL_TREE);
9716
9717   return build3(COMPONENT_REF, TREE_TYPE(field), table, field, NULL_TREE);
9718 }
9719
9720 // Return a tree for the first argument to pass to the interface
9721 // function.
9722
9723 tree
9724 Interface_field_reference_expression::get_underlying_object_tree(
9725     Translate_context*,
9726     tree expr)
9727 {
9728   if (this->expr_->type()->points_to() != NULL)
9729     expr = build_fold_indirect_ref(expr);
9730
9731   tree expr_type = TREE_TYPE(expr);
9732   gcc_assert(TREE_CODE(expr_type) == RECORD_TYPE);
9733
9734   tree field = DECL_CHAIN(TYPE_FIELDS(expr_type));
9735   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__object") == 0);
9736
9737   return build3(COMPONENT_REF, TREE_TYPE(field), expr, field, NULL_TREE);
9738 }
9739
9740 // Traversal.
9741
9742 int
9743 Interface_field_reference_expression::do_traverse(Traverse* traverse)
9744 {
9745   return Expression::traverse(&this->expr_, traverse);
9746 }
9747
9748 // Return the type of an interface field reference.
9749
9750 Type*
9751 Interface_field_reference_expression::do_type()
9752 {
9753   Type* expr_type = this->expr_->type();
9754
9755   Type* points_to = expr_type->points_to();
9756   if (points_to != NULL)
9757     expr_type = points_to;
9758
9759   Interface_type* interface_type = expr_type->interface_type();
9760   if (interface_type == NULL)
9761     return Type::make_error_type();
9762
9763   const Typed_identifier* method = interface_type->find_method(this->name_);
9764   if (method == NULL)
9765     return Type::make_error_type();
9766
9767   return method->type();
9768 }
9769
9770 // Determine types.
9771
9772 void
9773 Interface_field_reference_expression::do_determine_type(const Type_context*)
9774 {
9775   this->expr_->determine_type_no_context();
9776 }
9777
9778 // Check the types for an interface field reference.
9779
9780 void
9781 Interface_field_reference_expression::do_check_types(Gogo*)
9782 {
9783   Type* type = this->expr_->type();
9784
9785   Type* points_to = type->points_to();
9786   if (points_to != NULL)
9787     type = points_to;
9788
9789   Interface_type* interface_type = type->interface_type();
9790   if (interface_type == NULL)
9791     this->report_error(_("expected interface or pointer to interface"));
9792   else
9793     {
9794       const Typed_identifier* method =
9795         interface_type->find_method(this->name_);
9796       if (method == NULL)
9797         {
9798           error_at(this->location(), "method %qs not in interface",
9799                    Gogo::message_name(this->name_).c_str());
9800           this->set_is_error();
9801         }
9802     }
9803 }
9804
9805 // Get a tree for a reference to a field in an interface.  There is no
9806 // standard tree type representation for this: it's a function
9807 // attached to its first argument, like a Bound_method_expression.
9808 // The only places it may currently be used are in a Call_expression
9809 // or a Go_statement, which will take it apart directly.  So this has
9810 // nothing to do at present.
9811
9812 tree
9813 Interface_field_reference_expression::do_get_tree(Translate_context*)
9814 {
9815   gcc_unreachable();
9816 }
9817
9818 // Make a reference to a field in an interface.
9819
9820 Expression*
9821 Expression::make_interface_field_reference(Expression* expr,
9822                                            const std::string& field,
9823                                            source_location location)
9824 {
9825   return new Interface_field_reference_expression(expr, field, location);
9826 }
9827
9828 // A general selector.  This is a Parser_expression for LEFT.NAME.  It
9829 // is lowered after we know the type of the left hand side.
9830
9831 class Selector_expression : public Parser_expression
9832 {
9833  public:
9834   Selector_expression(Expression* left, const std::string& name,
9835                       source_location location)
9836     : Parser_expression(EXPRESSION_SELECTOR, location),
9837       left_(left), name_(name)
9838   { }
9839
9840  protected:
9841   int
9842   do_traverse(Traverse* traverse)
9843   { return Expression::traverse(&this->left_, traverse); }
9844
9845   Expression*
9846   do_lower(Gogo*, Named_object*, int);
9847
9848   Expression*
9849   do_copy()
9850   {
9851     return new Selector_expression(this->left_->copy(), this->name_,
9852                                    this->location());
9853   }
9854
9855  private:
9856   Expression*
9857   lower_method_expression(Gogo*);
9858
9859   // The expression on the left hand side.
9860   Expression* left_;
9861   // The name on the right hand side.
9862   std::string name_;
9863 };
9864
9865 // Lower a selector expression once we know the real type of the left
9866 // hand side.
9867
9868 Expression*
9869 Selector_expression::do_lower(Gogo* gogo, Named_object*, int)
9870 {
9871   Expression* left = this->left_;
9872   if (left->is_type_expression())
9873     return this->lower_method_expression(gogo);
9874   return Type::bind_field_or_method(gogo, left->type(), left, this->name_,
9875                                     this->location());
9876 }
9877
9878 // Lower a method expression T.M or (*T).M.  We turn this into a
9879 // function literal.
9880
9881 Expression*
9882 Selector_expression::lower_method_expression(Gogo* gogo)
9883 {
9884   source_location location = this->location();
9885   Type* type = this->left_->type();
9886   const std::string& name(this->name_);
9887
9888   bool is_pointer;
9889   if (type->points_to() == NULL)
9890     is_pointer = false;
9891   else
9892     {
9893       is_pointer = true;
9894       type = type->points_to();
9895     }
9896   Named_type* nt = type->named_type();
9897   if (nt == NULL)
9898     {
9899       error_at(location,
9900                ("method expression requires named type or "
9901                 "pointer to named type"));
9902       return Expression::make_error(location);
9903     }
9904
9905   bool is_ambiguous;
9906   Method* method = nt->method_function(name, &is_ambiguous);
9907   if (method == NULL)
9908     {
9909       if (!is_ambiguous)
9910         error_at(location, "type %<%s%> has no method %<%s%>",
9911                  nt->message_name().c_str(),
9912                  Gogo::message_name(name).c_str());
9913       else
9914         error_at(location, "method %<%s%> is ambiguous in type %<%s%>",
9915                  Gogo::message_name(name).c_str(),
9916                  nt->message_name().c_str());
9917       return Expression::make_error(location);
9918     }
9919
9920   if (!is_pointer && !method->is_value_method())
9921     {
9922       error_at(location, "method requires pointer (use %<(*%s).%s)%>",
9923                nt->message_name().c_str(),
9924                Gogo::message_name(name).c_str());
9925       return Expression::make_error(location);
9926     }
9927
9928   // Build a new function type in which the receiver becomes the first
9929   // argument.
9930   Function_type* method_type = method->type();
9931   gcc_assert(method_type->is_method());
9932
9933   const char* const receiver_name = "$this";
9934   Typed_identifier_list* parameters = new Typed_identifier_list();
9935   parameters->push_back(Typed_identifier(receiver_name, this->left_->type(),
9936                                          location));
9937
9938   const Typed_identifier_list* method_parameters = method_type->parameters();
9939   if (method_parameters != NULL)
9940     {
9941       for (Typed_identifier_list::const_iterator p = method_parameters->begin();
9942            p != method_parameters->end();
9943            ++p)
9944         parameters->push_back(*p);
9945     }
9946
9947   const Typed_identifier_list* method_results = method_type->results();
9948   Typed_identifier_list* results;
9949   if (method_results == NULL)
9950     results = NULL;
9951   else
9952     {
9953       results = new Typed_identifier_list();
9954       for (Typed_identifier_list::const_iterator p = method_results->begin();
9955            p != method_results->end();
9956            ++p)
9957         results->push_back(*p);
9958     }
9959
9960   Function_type* fntype = Type::make_function_type(NULL, parameters, results,
9961                                                    location);
9962   if (method_type->is_varargs())
9963     fntype->set_is_varargs();
9964
9965   // We generate methods which always takes a pointer to the receiver
9966   // as their first argument.  If this is for a pointer type, we can
9967   // simply reuse the existing function.  We use an internal hack to
9968   // get the right type.
9969
9970   if (is_pointer)
9971     {
9972       Named_object* mno = (method->needs_stub_method()
9973                            ? method->stub_object()
9974                            : method->named_object());
9975       Expression* f = Expression::make_func_reference(mno, NULL, location);
9976       f = Expression::make_cast(fntype, f, location);
9977       Type_conversion_expression* tce =
9978         static_cast<Type_conversion_expression*>(f);
9979       tce->set_may_convert_function_types();
9980       return f;
9981     }
9982
9983   Named_object* no = gogo->start_function(Gogo::thunk_name(), fntype, false,
9984                                           location);
9985
9986   Named_object* vno = gogo->lookup(receiver_name, NULL);
9987   gcc_assert(vno != NULL);
9988   Expression* ve = Expression::make_var_reference(vno, location);
9989   Expression* bm = Type::bind_field_or_method(gogo, nt, ve, name, location);
9990   gcc_assert(bm != NULL && !bm->is_error_expression());
9991
9992   Expression_list* args;
9993   if (method_parameters == NULL)
9994     args = NULL;
9995   else
9996     {
9997       args = new Expression_list();
9998       for (Typed_identifier_list::const_iterator p = method_parameters->begin();
9999            p != method_parameters->end();
10000            ++p)
10001         {
10002           vno = gogo->lookup(p->name(), NULL);
10003           gcc_assert(vno != NULL);
10004           args->push_back(Expression::make_var_reference(vno, location));
10005         }
10006     }
10007
10008   Call_expression* call = Expression::make_call(bm, args,
10009                                                 method_type->is_varargs(),
10010                                                 location);
10011
10012   size_t count = call->result_count();
10013   Statement* s;
10014   if (count == 0)
10015     s = Statement::make_statement(call);
10016   else
10017     {
10018       Expression_list* retvals = new Expression_list();
10019       if (count <= 1)
10020         retvals->push_back(call);
10021       else
10022         {
10023           for (size_t i = 0; i < count; ++i)
10024             retvals->push_back(Expression::make_call_result(call, i));
10025         }
10026       s = Statement::make_return_statement(no->func_value()->type()->results(),
10027                                            retvals, location);
10028     }
10029   gogo->add_statement(s);
10030
10031   gogo->finish_function(location);
10032
10033   return Expression::make_func_reference(no, NULL, location);
10034 }
10035
10036 // Make a selector expression.
10037
10038 Expression*
10039 Expression::make_selector(Expression* left, const std::string& name,
10040                           source_location location)
10041 {
10042   return new Selector_expression(left, name, location);
10043 }
10044
10045 // Implement the builtin function new.
10046
10047 class Allocation_expression : public Expression
10048 {
10049  public:
10050   Allocation_expression(Type* type, source_location location)
10051     : Expression(EXPRESSION_ALLOCATION, location),
10052       type_(type)
10053   { }
10054
10055  protected:
10056   int
10057   do_traverse(Traverse* traverse)
10058   { return Type::traverse(this->type_, traverse); }
10059
10060   Type*
10061   do_type()
10062   { return Type::make_pointer_type(this->type_); }
10063
10064   void
10065   do_determine_type(const Type_context*)
10066   { }
10067
10068   void
10069   do_check_types(Gogo*);
10070
10071   Expression*
10072   do_copy()
10073   { return new Allocation_expression(this->type_, this->location()); }
10074
10075   tree
10076   do_get_tree(Translate_context*);
10077
10078  private:
10079   // The type we are allocating.
10080   Type* type_;
10081 };
10082
10083 // Check the type of an allocation expression.
10084
10085 void
10086 Allocation_expression::do_check_types(Gogo*)
10087 {
10088   if (this->type_->function_type() != NULL)
10089     this->report_error(_("invalid new of function type"));
10090 }
10091
10092 // Return a tree for an allocation expression.
10093
10094 tree
10095 Allocation_expression::do_get_tree(Translate_context* context)
10096 {
10097   tree type_tree = this->type_->get_tree(context->gogo());
10098   tree size_tree = TYPE_SIZE_UNIT(type_tree);
10099   tree space = context->gogo()->allocate_memory(this->type_, size_tree,
10100                                                 this->location());
10101   return fold_convert(build_pointer_type(type_tree), space);
10102 }
10103
10104 // Make an allocation expression.
10105
10106 Expression*
10107 Expression::make_allocation(Type* type, source_location location)
10108 {
10109   return new Allocation_expression(type, location);
10110 }
10111
10112 // Implement the builtin function make.
10113
10114 class Make_expression : public Expression
10115 {
10116  public:
10117   Make_expression(Type* type, Expression_list* args, source_location location)
10118     : Expression(EXPRESSION_MAKE, location),
10119       type_(type), args_(args)
10120   { }
10121
10122  protected:
10123   int
10124   do_traverse(Traverse* traverse);
10125
10126   Type*
10127   do_type()
10128   { return this->type_; }
10129
10130   void
10131   do_determine_type(const Type_context*);
10132
10133   void
10134   do_check_types(Gogo*);
10135
10136   Expression*
10137   do_copy()
10138   {
10139     return new Make_expression(this->type_, this->args_->copy(),
10140                                this->location());
10141   }
10142
10143   tree
10144   do_get_tree(Translate_context*);
10145
10146  private:
10147   // The type we are making.
10148   Type* type_;
10149   // The arguments to pass to the make routine.
10150   Expression_list* args_;
10151 };
10152
10153 // Traversal.
10154
10155 int
10156 Make_expression::do_traverse(Traverse* traverse)
10157 {
10158   if (this->args_ != NULL
10159       && this->args_->traverse(traverse) == TRAVERSE_EXIT)
10160     return TRAVERSE_EXIT;
10161   if (Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
10162     return TRAVERSE_EXIT;
10163   return TRAVERSE_CONTINUE;
10164 }
10165
10166 // Set types of arguments.
10167
10168 void
10169 Make_expression::do_determine_type(const Type_context*)
10170 {
10171   if (this->args_ != NULL)
10172     {
10173       Type_context context(Type::lookup_integer_type("int"), false);
10174       for (Expression_list::const_iterator pe = this->args_->begin();
10175            pe != this->args_->end();
10176            ++pe)
10177         (*pe)->determine_type(&context);
10178     }
10179 }
10180
10181 // Check types for a make expression.
10182
10183 void
10184 Make_expression::do_check_types(Gogo*)
10185 {
10186   if (this->type_->channel_type() == NULL
10187       && this->type_->map_type() == NULL
10188       && (this->type_->array_type() == NULL
10189           || this->type_->array_type()->length() != NULL))
10190     this->report_error(_("invalid type for make function"));
10191   else if (!this->type_->check_make_expression(this->args_, this->location()))
10192     this->set_is_error();
10193 }
10194
10195 // Return a tree for a make expression.
10196
10197 tree
10198 Make_expression::do_get_tree(Translate_context* context)
10199 {
10200   return this->type_->make_expression_tree(context, this->args_,
10201                                            this->location());
10202 }
10203
10204 // Make a make expression.
10205
10206 Expression*
10207 Expression::make_make(Type* type, Expression_list* args,
10208                       source_location location)
10209 {
10210   return new Make_expression(type, args, location);
10211 }
10212
10213 // Construct a struct.
10214
10215 class Struct_construction_expression : public Expression
10216 {
10217  public:
10218   Struct_construction_expression(Type* type, Expression_list* vals,
10219                                  source_location location)
10220     : Expression(EXPRESSION_STRUCT_CONSTRUCTION, location),
10221       type_(type), vals_(vals)
10222   { }
10223
10224   // Return whether this is a constant initializer.
10225   bool
10226   is_constant_struct() const;
10227
10228  protected:
10229   int
10230   do_traverse(Traverse* traverse);
10231
10232   Type*
10233   do_type()
10234   { return this->type_; }
10235
10236   void
10237   do_determine_type(const Type_context*);
10238
10239   void
10240   do_check_types(Gogo*);
10241
10242   Expression*
10243   do_copy()
10244   {
10245     return new Struct_construction_expression(this->type_, this->vals_->copy(),
10246                                               this->location());
10247   }
10248
10249   bool
10250   do_is_addressable() const
10251   { return true; }
10252
10253   tree
10254   do_get_tree(Translate_context*);
10255
10256   void
10257   do_export(Export*) const;
10258
10259  private:
10260   // The type of the struct to construct.
10261   Type* type_;
10262   // The list of values, in order of the fields in the struct.  A NULL
10263   // entry means that the field should be zero-initialized.
10264   Expression_list* vals_;
10265 };
10266
10267 // Traversal.
10268
10269 int
10270 Struct_construction_expression::do_traverse(Traverse* traverse)
10271 {
10272   if (this->vals_ != NULL
10273       && this->vals_->traverse(traverse) == TRAVERSE_EXIT)
10274     return TRAVERSE_EXIT;
10275   if (Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
10276     return TRAVERSE_EXIT;
10277   return TRAVERSE_CONTINUE;
10278 }
10279
10280 // Return whether this is a constant initializer.
10281
10282 bool
10283 Struct_construction_expression::is_constant_struct() const
10284 {
10285   if (this->vals_ == NULL)
10286     return true;
10287   for (Expression_list::const_iterator pv = this->vals_->begin();
10288        pv != this->vals_->end();
10289        ++pv)
10290     {
10291       if (*pv != NULL
10292           && !(*pv)->is_constant()
10293           && (!(*pv)->is_composite_literal()
10294               || (*pv)->is_nonconstant_composite_literal()))
10295         return false;
10296     }
10297
10298   const Struct_field_list* fields = this->type_->struct_type()->fields();
10299   for (Struct_field_list::const_iterator pf = fields->begin();
10300        pf != fields->end();
10301        ++pf)
10302     {
10303       // There are no constant constructors for interfaces.
10304       if (pf->type()->interface_type() != NULL)
10305         return false;
10306     }
10307
10308   return true;
10309 }
10310
10311 // Final type determination.
10312
10313 void
10314 Struct_construction_expression::do_determine_type(const Type_context*)
10315 {
10316   if (this->vals_ == NULL)
10317     return;
10318   const Struct_field_list* fields = this->type_->struct_type()->fields();
10319   Expression_list::const_iterator pv = this->vals_->begin();
10320   for (Struct_field_list::const_iterator pf = fields->begin();
10321        pf != fields->end();
10322        ++pf, ++pv)
10323     {
10324       if (pv == this->vals_->end())
10325         return;
10326       if (*pv != NULL)
10327         {
10328           Type_context subcontext(pf->type(), false);
10329           (*pv)->determine_type(&subcontext);
10330         }
10331     }
10332 }
10333
10334 // Check types.
10335
10336 void
10337 Struct_construction_expression::do_check_types(Gogo*)
10338 {
10339   if (this->vals_ == NULL)
10340     return;
10341
10342   Struct_type* st = this->type_->struct_type();
10343   if (this->vals_->size() > st->field_count())
10344     {
10345       this->report_error(_("too many expressions for struct"));
10346       return;
10347     }
10348
10349   const Struct_field_list* fields = st->fields();
10350   Expression_list::const_iterator pv = this->vals_->begin();
10351   int i = 0;
10352   for (Struct_field_list::const_iterator pf = fields->begin();
10353        pf != fields->end();
10354        ++pf, ++pv, ++i)
10355     {
10356       if (pv == this->vals_->end())
10357         {
10358           this->report_error(_("too few expressions for struct"));
10359           break;
10360         }
10361
10362       if (*pv == NULL)
10363         continue;
10364
10365       std::string reason;
10366       if (!Type::are_assignable(pf->type(), (*pv)->type(), &reason))
10367         {
10368           if (reason.empty())
10369             error_at((*pv)->location(),
10370                      "incompatible type for field %d in struct construction",
10371                      i + 1);
10372           else
10373             error_at((*pv)->location(),
10374                      ("incompatible type for field %d in "
10375                       "struct construction (%s)"),
10376                      i + 1, reason.c_str());
10377           this->set_is_error();
10378         }
10379     }
10380   gcc_assert(pv == this->vals_->end());
10381 }
10382
10383 // Return a tree for constructing a struct.
10384
10385 tree
10386 Struct_construction_expression::do_get_tree(Translate_context* context)
10387 {
10388   Gogo* gogo = context->gogo();
10389
10390   if (this->vals_ == NULL)
10391     return this->type_->get_init_tree(gogo, false);
10392
10393   tree type_tree = this->type_->get_tree(gogo);
10394   if (type_tree == error_mark_node)
10395     return error_mark_node;
10396   gcc_assert(TREE_CODE(type_tree) == RECORD_TYPE);
10397
10398   bool is_constant = true;
10399   const Struct_field_list* fields = this->type_->struct_type()->fields();
10400   VEC(constructor_elt,gc)* elts = VEC_alloc(constructor_elt, gc,
10401                                             fields->size());
10402   Struct_field_list::const_iterator pf = fields->begin();
10403   Expression_list::const_iterator pv = this->vals_->begin();
10404   for (tree field = TYPE_FIELDS(type_tree);
10405        field != NULL_TREE;
10406        field = DECL_CHAIN(field), ++pf)
10407     {
10408       gcc_assert(pf != fields->end());
10409
10410       tree val;
10411       if (pv == this->vals_->end())
10412         val = pf->type()->get_init_tree(gogo, false);
10413       else if (*pv == NULL)
10414         {
10415           val = pf->type()->get_init_tree(gogo, false);
10416           ++pv;
10417         }
10418       else
10419         {
10420           val = Expression::convert_for_assignment(context, pf->type(),
10421                                                    (*pv)->type(),
10422                                                    (*pv)->get_tree(context),
10423                                                    this->location());
10424           ++pv;
10425         }
10426
10427       if (val == error_mark_node || TREE_TYPE(val) == error_mark_node)
10428         return error_mark_node;
10429
10430       constructor_elt* elt = VEC_quick_push(constructor_elt, elts, NULL);
10431       elt->index = field;
10432       elt->value = val;
10433       if (!TREE_CONSTANT(val))
10434         is_constant = false;
10435     }
10436   gcc_assert(pf == fields->end());
10437
10438   tree ret = build_constructor(type_tree, elts);
10439   if (is_constant)
10440     TREE_CONSTANT(ret) = 1;
10441   return ret;
10442 }
10443
10444 // Export a struct construction.
10445
10446 void
10447 Struct_construction_expression::do_export(Export* exp) const
10448 {
10449   exp->write_c_string("convert(");
10450   exp->write_type(this->type_);
10451   for (Expression_list::const_iterator pv = this->vals_->begin();
10452        pv != this->vals_->end();
10453        ++pv)
10454     {
10455       exp->write_c_string(", ");
10456       if (*pv != NULL)
10457         (*pv)->export_expression(exp);
10458     }
10459   exp->write_c_string(")");
10460 }
10461
10462 // Make a struct composite literal.  This used by the thunk code.
10463
10464 Expression*
10465 Expression::make_struct_composite_literal(Type* type, Expression_list* vals,
10466                                           source_location location)
10467 {
10468   gcc_assert(type->struct_type() != NULL);
10469   return new Struct_construction_expression(type, vals, location);
10470 }
10471
10472 // Construct an array.  This class is not used directly; instead we
10473 // use the child classes, Fixed_array_construction_expression and
10474 // Open_array_construction_expression.
10475
10476 class Array_construction_expression : public Expression
10477 {
10478  protected:
10479   Array_construction_expression(Expression_classification classification,
10480                                 Type* type, Expression_list* vals,
10481                                 source_location location)
10482     : Expression(classification, location),
10483       type_(type), vals_(vals)
10484   { }
10485
10486  public:
10487   // Return whether this is a constant initializer.
10488   bool
10489   is_constant_array() const;
10490
10491   // Return the number of elements.
10492   size_t
10493   element_count() const
10494   { return this->vals_ == NULL ? 0 : this->vals_->size(); }
10495
10496 protected:
10497   int
10498   do_traverse(Traverse* traverse);
10499
10500   Type*
10501   do_type()
10502   { return this->type_; }
10503
10504   void
10505   do_determine_type(const Type_context*);
10506
10507   void
10508   do_check_types(Gogo*);
10509
10510   bool
10511   do_is_addressable() const
10512   { return true; }
10513
10514   void
10515   do_export(Export*) const;
10516
10517   // The list of values.
10518   Expression_list*
10519   vals()
10520   { return this->vals_; }
10521
10522   // Get a constructor tree for the array values.
10523   tree
10524   get_constructor_tree(Translate_context* context, tree type_tree);
10525
10526  private:
10527   // The type of the array to construct.
10528   Type* type_;
10529   // The list of values.
10530   Expression_list* vals_;
10531 };
10532
10533 // Traversal.
10534
10535 int
10536 Array_construction_expression::do_traverse(Traverse* traverse)
10537 {
10538   if (this->vals_ != NULL
10539       && this->vals_->traverse(traverse) == TRAVERSE_EXIT)
10540     return TRAVERSE_EXIT;
10541   if (Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
10542     return TRAVERSE_EXIT;
10543   return TRAVERSE_CONTINUE;
10544 }
10545
10546 // Return whether this is a constant initializer.
10547
10548 bool
10549 Array_construction_expression::is_constant_array() const
10550 {
10551   if (this->vals_ == NULL)
10552     return true;
10553
10554   // There are no constant constructors for interfaces.
10555   if (this->type_->array_type()->element_type()->interface_type() != NULL)
10556     return false;
10557
10558   for (Expression_list::const_iterator pv = this->vals_->begin();
10559        pv != this->vals_->end();
10560        ++pv)
10561     {
10562       if (*pv != NULL
10563           && !(*pv)->is_constant()
10564           && (!(*pv)->is_composite_literal()
10565               || (*pv)->is_nonconstant_composite_literal()))
10566         return false;
10567     }
10568   return true;
10569 }
10570
10571 // Final type determination.
10572
10573 void
10574 Array_construction_expression::do_determine_type(const Type_context*)
10575 {
10576   if (this->vals_ == NULL)
10577     return;
10578   Type_context subcontext(this->type_->array_type()->element_type(), false);
10579   for (Expression_list::const_iterator pv = this->vals_->begin();
10580        pv != this->vals_->end();
10581        ++pv)
10582     {
10583       if (*pv != NULL)
10584         (*pv)->determine_type(&subcontext);
10585     }
10586 }
10587
10588 // Check types.
10589
10590 void
10591 Array_construction_expression::do_check_types(Gogo*)
10592 {
10593   if (this->vals_ == NULL)
10594     return;
10595
10596   Array_type* at = this->type_->array_type();
10597   int i = 0;
10598   Type* element_type = at->element_type();
10599   for (Expression_list::const_iterator pv = this->vals_->begin();
10600        pv != this->vals_->end();
10601        ++pv, ++i)
10602     {
10603       if (*pv != NULL
10604           && !Type::are_assignable(element_type, (*pv)->type(), NULL))
10605         {
10606           error_at((*pv)->location(),
10607                    "incompatible type for element %d in composite literal",
10608                    i + 1);
10609           this->set_is_error();
10610         }
10611     }
10612
10613   Expression* length = at->length();
10614   if (length != NULL)
10615     {
10616       mpz_t val;
10617       mpz_init(val);
10618       Type* type;
10619       if (at->length()->integer_constant_value(true, val, &type))
10620         {
10621           if (this->vals_->size() > mpz_get_ui(val))
10622             this->report_error(_("too many elements in composite literal"));
10623         }
10624       mpz_clear(val);
10625     }
10626 }
10627
10628 // Get a constructor tree for the array values.
10629
10630 tree
10631 Array_construction_expression::get_constructor_tree(Translate_context* context,
10632                                                     tree type_tree)
10633 {
10634   VEC(constructor_elt,gc)* values = VEC_alloc(constructor_elt, gc,
10635                                               (this->vals_ == NULL
10636                                                ? 0
10637                                                : this->vals_->size()));
10638   Type* element_type = this->type_->array_type()->element_type();
10639   bool is_constant = true;
10640   if (this->vals_ != NULL)
10641     {
10642       size_t i = 0;
10643       for (Expression_list::const_iterator pv = this->vals_->begin();
10644            pv != this->vals_->end();
10645            ++pv, ++i)
10646         {
10647           constructor_elt* elt = VEC_quick_push(constructor_elt, values, NULL);
10648           elt->index = size_int(i);
10649           if (*pv == NULL)
10650             elt->value = element_type->get_init_tree(context->gogo(), false);
10651           else
10652             {
10653               tree value_tree = (*pv)->get_tree(context);
10654               elt->value = Expression::convert_for_assignment(context,
10655                                                               element_type,
10656                                                               (*pv)->type(),
10657                                                               value_tree,
10658                                                               this->location());
10659             }
10660           if (elt->value == error_mark_node)
10661             return error_mark_node;
10662           if (!TREE_CONSTANT(elt->value))
10663             is_constant = false;
10664         }
10665     }
10666
10667   tree ret = build_constructor(type_tree, values);
10668   if (is_constant)
10669     TREE_CONSTANT(ret) = 1;
10670   return ret;
10671 }
10672
10673 // Export an array construction.
10674
10675 void
10676 Array_construction_expression::do_export(Export* exp) const
10677 {
10678   exp->write_c_string("convert(");
10679   exp->write_type(this->type_);
10680   if (this->vals_ != NULL)
10681     {
10682       for (Expression_list::const_iterator pv = this->vals_->begin();
10683            pv != this->vals_->end();
10684            ++pv)
10685         {
10686           exp->write_c_string(", ");
10687           if (*pv != NULL)
10688             (*pv)->export_expression(exp);
10689         }
10690     }
10691   exp->write_c_string(")");
10692 }
10693
10694 // Construct a fixed array.
10695
10696 class Fixed_array_construction_expression :
10697   public Array_construction_expression
10698 {
10699  public:
10700   Fixed_array_construction_expression(Type* type, Expression_list* vals,
10701                                       source_location location)
10702     : Array_construction_expression(EXPRESSION_FIXED_ARRAY_CONSTRUCTION,
10703                                     type, vals, location)
10704   {
10705     gcc_assert(type->array_type() != NULL
10706                && type->array_type()->length() != NULL);
10707   }
10708
10709  protected:
10710   Expression*
10711   do_copy()
10712   {
10713     return new Fixed_array_construction_expression(this->type(),
10714                                                    (this->vals() == NULL
10715                                                     ? NULL
10716                                                     : this->vals()->copy()),
10717                                                    this->location());
10718   }
10719
10720   tree
10721   do_get_tree(Translate_context*);
10722 };
10723
10724 // Return a tree for constructing a fixed array.
10725
10726 tree
10727 Fixed_array_construction_expression::do_get_tree(Translate_context* context)
10728 {
10729   return this->get_constructor_tree(context,
10730                                     this->type()->get_tree(context->gogo()));
10731 }
10732
10733 // Construct an open array.
10734
10735 class Open_array_construction_expression : public Array_construction_expression
10736 {
10737  public:
10738   Open_array_construction_expression(Type* type, Expression_list* vals,
10739                                      source_location location)
10740     : Array_construction_expression(EXPRESSION_OPEN_ARRAY_CONSTRUCTION,
10741                                     type, vals, location)
10742   {
10743     gcc_assert(type->array_type() != NULL
10744                && type->array_type()->length() == NULL);
10745   }
10746
10747  protected:
10748   // Note that taking the address of an open array literal is invalid.
10749
10750   Expression*
10751   do_copy()
10752   {
10753     return new Open_array_construction_expression(this->type(),
10754                                                   (this->vals() == NULL
10755                                                    ? NULL
10756                                                    : this->vals()->copy()),
10757                                                   this->location());
10758   }
10759
10760   tree
10761   do_get_tree(Translate_context*);
10762 };
10763
10764 // Return a tree for constructing an open array.
10765
10766 tree
10767 Open_array_construction_expression::do_get_tree(Translate_context* context)
10768 {
10769   Type* element_type = this->type()->array_type()->element_type();
10770   tree element_type_tree = element_type->get_tree(context->gogo());
10771   if (element_type_tree == error_mark_node)
10772     return error_mark_node;
10773
10774   tree values;
10775   tree length_tree;
10776   if (this->vals() == NULL || this->vals()->empty())
10777     {
10778       // We need to create a unique value.
10779       tree max = size_int(0);
10780       tree constructor_type = build_array_type(element_type_tree,
10781                                                build_index_type(max));
10782       if (constructor_type == error_mark_node)
10783         return error_mark_node;
10784       VEC(constructor_elt,gc)* vec = VEC_alloc(constructor_elt, gc, 1);
10785       constructor_elt* elt = VEC_quick_push(constructor_elt, vec, NULL);
10786       elt->index = size_int(0);
10787       elt->value = element_type->get_init_tree(context->gogo(), false);
10788       values = build_constructor(constructor_type, vec);
10789       if (TREE_CONSTANT(elt->value))
10790         TREE_CONSTANT(values) = 1;
10791       length_tree = size_int(0);
10792     }
10793   else
10794     {
10795       tree max = size_int(this->vals()->size() - 1);
10796       tree constructor_type = build_array_type(element_type_tree,
10797                                                build_index_type(max));
10798       if (constructor_type == error_mark_node)
10799         return error_mark_node;
10800       values = this->get_constructor_tree(context, constructor_type);
10801       length_tree = size_int(this->vals()->size());
10802     }
10803
10804   if (values == error_mark_node)
10805     return error_mark_node;
10806
10807   bool is_constant_initializer = TREE_CONSTANT(values);
10808   bool is_in_function = context->function() != NULL;
10809
10810   if (is_constant_initializer)
10811     {
10812       tree tmp = build_decl(this->location(), VAR_DECL,
10813                             create_tmp_var_name("C"), TREE_TYPE(values));
10814       DECL_EXTERNAL(tmp) = 0;
10815       TREE_PUBLIC(tmp) = 0;
10816       TREE_STATIC(tmp) = 1;
10817       DECL_ARTIFICIAL(tmp) = 1;
10818       if (is_in_function)
10819         {
10820           // If this is not a function, we will only initialize the
10821           // value once, so we can use this directly rather than
10822           // copying it.  In that case we can't make it read-only,
10823           // because the program is permitted to change it.
10824           TREE_READONLY(tmp) = 1;
10825           TREE_CONSTANT(tmp) = 1;
10826         }
10827       DECL_INITIAL(tmp) = values;
10828       rest_of_decl_compilation(tmp, 1, 0);
10829       values = tmp;
10830     }
10831
10832   tree space;
10833   tree set;
10834   if (!is_in_function && is_constant_initializer)
10835     {
10836       // Outside of a function, we know the initializer will only run
10837       // once.
10838       space = build_fold_addr_expr(values);
10839       set = NULL_TREE;
10840     }
10841   else
10842     {
10843       tree memsize = TYPE_SIZE_UNIT(TREE_TYPE(values));
10844       space = context->gogo()->allocate_memory(element_type, memsize,
10845                                                this->location());
10846       space = save_expr(space);
10847
10848       tree s = fold_convert(build_pointer_type(TREE_TYPE(values)), space);
10849       tree ref = build_fold_indirect_ref_loc(this->location(), s);
10850       TREE_THIS_NOTRAP(ref) = 1;
10851       set = build2(MODIFY_EXPR, void_type_node, ref, values);
10852     }
10853
10854   // Build a constructor for the open array.
10855
10856   tree type_tree = this->type()->get_tree(context->gogo());
10857   if (type_tree == error_mark_node)
10858     return error_mark_node;
10859   gcc_assert(TREE_CODE(type_tree) == RECORD_TYPE);
10860
10861   VEC(constructor_elt,gc)* init = VEC_alloc(constructor_elt, gc, 3);
10862
10863   constructor_elt* elt = VEC_quick_push(constructor_elt, init, NULL);
10864   tree field = TYPE_FIELDS(type_tree);
10865   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__values") == 0);
10866   elt->index = field;
10867   elt->value = fold_convert(TREE_TYPE(field), space);
10868
10869   elt = VEC_quick_push(constructor_elt, init, NULL);
10870   field = DECL_CHAIN(field);
10871   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__count") == 0);
10872   elt->index = field;
10873   elt->value = fold_convert(TREE_TYPE(field), length_tree);
10874
10875   elt = VEC_quick_push(constructor_elt, init, NULL);
10876   field = DECL_CHAIN(field);
10877   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)),"__capacity") == 0);
10878   elt->index = field;
10879   elt->value = fold_convert(TREE_TYPE(field), length_tree);
10880
10881   tree constructor = build_constructor(type_tree, init);
10882   if (constructor == error_mark_node)
10883     return error_mark_node;
10884   if (!is_in_function && is_constant_initializer)
10885     TREE_CONSTANT(constructor) = 1;
10886
10887   if (set == NULL_TREE)
10888     return constructor;
10889   else
10890     return build2(COMPOUND_EXPR, type_tree, set, constructor);
10891 }
10892
10893 // Make a slice composite literal.  This is used by the type
10894 // descriptor code.
10895
10896 Expression*
10897 Expression::make_slice_composite_literal(Type* type, Expression_list* vals,
10898                                          source_location location)
10899 {
10900   gcc_assert(type->is_open_array_type());
10901   return new Open_array_construction_expression(type, vals, location);
10902 }
10903
10904 // Construct a map.
10905
10906 class Map_construction_expression : public Expression
10907 {
10908  public:
10909   Map_construction_expression(Type* type, Expression_list* vals,
10910                               source_location location)
10911     : Expression(EXPRESSION_MAP_CONSTRUCTION, location),
10912       type_(type), vals_(vals)
10913   { gcc_assert(vals == NULL || vals->size() % 2 == 0); }
10914
10915  protected:
10916   int
10917   do_traverse(Traverse* traverse);
10918
10919   Type*
10920   do_type()
10921   { return this->type_; }
10922
10923   void
10924   do_determine_type(const Type_context*);
10925
10926   void
10927   do_check_types(Gogo*);
10928
10929   Expression*
10930   do_copy()
10931   {
10932     return new Map_construction_expression(this->type_, this->vals_->copy(),
10933                                            this->location());
10934   }
10935
10936   tree
10937   do_get_tree(Translate_context*);
10938
10939   void
10940   do_export(Export*) const;
10941
10942  private:
10943   // The type of the map to construct.
10944   Type* type_;
10945   // The list of values.
10946   Expression_list* vals_;
10947 };
10948
10949 // Traversal.
10950
10951 int
10952 Map_construction_expression::do_traverse(Traverse* traverse)
10953 {
10954   if (this->vals_ != NULL
10955       && this->vals_->traverse(traverse) == TRAVERSE_EXIT)
10956     return TRAVERSE_EXIT;
10957   if (Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
10958     return TRAVERSE_EXIT;
10959   return TRAVERSE_CONTINUE;
10960 }
10961
10962 // Final type determination.
10963
10964 void
10965 Map_construction_expression::do_determine_type(const Type_context*)
10966 {
10967   if (this->vals_ == NULL)
10968     return;
10969
10970   Map_type* mt = this->type_->map_type();
10971   Type_context key_context(mt->key_type(), false);
10972   Type_context val_context(mt->val_type(), false);
10973   for (Expression_list::const_iterator pv = this->vals_->begin();
10974        pv != this->vals_->end();
10975        ++pv)
10976     {
10977       (*pv)->determine_type(&key_context);
10978       ++pv;
10979       (*pv)->determine_type(&val_context);
10980     }
10981 }
10982
10983 // Check types.
10984
10985 void
10986 Map_construction_expression::do_check_types(Gogo*)
10987 {
10988   if (this->vals_ == NULL)
10989     return;
10990
10991   Map_type* mt = this->type_->map_type();
10992   int i = 0;
10993   Type* key_type = mt->key_type();
10994   Type* val_type = mt->val_type();
10995   for (Expression_list::const_iterator pv = this->vals_->begin();
10996        pv != this->vals_->end();
10997        ++pv, ++i)
10998     {
10999       if (!Type::are_assignable(key_type, (*pv)->type(), NULL))
11000         {
11001           error_at((*pv)->location(),
11002                    "incompatible type for element %d key in map construction",
11003                    i + 1);
11004           this->set_is_error();
11005         }
11006       ++pv;
11007       if (!Type::are_assignable(val_type, (*pv)->type(), NULL))
11008         {
11009           error_at((*pv)->location(),
11010                    ("incompatible type for element %d value "
11011                     "in map construction"),
11012                    i + 1);
11013           this->set_is_error();
11014         }
11015     }
11016 }
11017
11018 // Return a tree for constructing a map.
11019
11020 tree
11021 Map_construction_expression::do_get_tree(Translate_context* context)
11022 {
11023   Gogo* gogo = context->gogo();
11024   source_location loc = this->location();
11025
11026   Map_type* mt = this->type_->map_type();
11027
11028   // Build a struct to hold the key and value.
11029   tree struct_type = make_node(RECORD_TYPE);
11030
11031   Type* key_type = mt->key_type();
11032   tree id = get_identifier("__key");
11033   tree key_field = build_decl(loc, FIELD_DECL, id, key_type->get_tree(gogo));
11034   DECL_CONTEXT(key_field) = struct_type;
11035   TYPE_FIELDS(struct_type) = key_field;
11036
11037   Type* val_type = mt->val_type();
11038   id = get_identifier("__val");
11039   tree val_field = build_decl(loc, FIELD_DECL, id, val_type->get_tree(gogo));
11040   DECL_CONTEXT(val_field) = struct_type;
11041   DECL_CHAIN(key_field) = val_field;
11042
11043   layout_type(struct_type);
11044
11045   bool is_constant = true;
11046   size_t i = 0;
11047   tree valaddr;
11048   tree make_tmp;
11049
11050   if (this->vals_ == NULL || this->vals_->empty())
11051     {
11052       valaddr = null_pointer_node;
11053       make_tmp = NULL_TREE;
11054     }
11055   else
11056     {
11057       VEC(constructor_elt,gc)* values = VEC_alloc(constructor_elt, gc,
11058                                                   this->vals_->size() / 2);
11059
11060       for (Expression_list::const_iterator pv = this->vals_->begin();
11061            pv != this->vals_->end();
11062            ++pv, ++i)
11063         {
11064           bool one_is_constant = true;
11065
11066           VEC(constructor_elt,gc)* one = VEC_alloc(constructor_elt, gc, 2);
11067
11068           constructor_elt* elt = VEC_quick_push(constructor_elt, one, NULL);
11069           elt->index = key_field;
11070           tree val_tree = (*pv)->get_tree(context);
11071           elt->value = Expression::convert_for_assignment(context, key_type,
11072                                                           (*pv)->type(),
11073                                                           val_tree, loc);
11074           if (elt->value == error_mark_node)
11075             return error_mark_node;
11076           if (!TREE_CONSTANT(elt->value))
11077             one_is_constant = false;
11078
11079           ++pv;
11080
11081           elt = VEC_quick_push(constructor_elt, one, NULL);
11082           elt->index = val_field;
11083           val_tree = (*pv)->get_tree(context);
11084           elt->value = Expression::convert_for_assignment(context, val_type,
11085                                                           (*pv)->type(),
11086                                                           val_tree, loc);
11087           if (elt->value == error_mark_node)
11088             return error_mark_node;
11089           if (!TREE_CONSTANT(elt->value))
11090             one_is_constant = false;
11091
11092           elt = VEC_quick_push(constructor_elt, values, NULL);
11093           elt->index = size_int(i);
11094           elt->value = build_constructor(struct_type, one);
11095           if (one_is_constant)
11096             TREE_CONSTANT(elt->value) = 1;
11097           else
11098             is_constant = false;
11099         }
11100
11101       tree index_type = build_index_type(size_int(i - 1));
11102       tree array_type = build_array_type(struct_type, index_type);
11103       tree init = build_constructor(array_type, values);
11104       if (is_constant)
11105         TREE_CONSTANT(init) = 1;
11106       tree tmp;
11107       if (current_function_decl != NULL)
11108         {
11109           tmp = create_tmp_var(array_type, get_name(array_type));
11110           DECL_INITIAL(tmp) = init;
11111           make_tmp = fold_build1_loc(loc, DECL_EXPR, void_type_node, tmp);
11112           TREE_ADDRESSABLE(tmp) = 1;
11113         }
11114       else
11115         {
11116           tmp = build_decl(loc, VAR_DECL, create_tmp_var_name("M"), array_type);
11117           DECL_EXTERNAL(tmp) = 0;
11118           TREE_PUBLIC(tmp) = 0;
11119           TREE_STATIC(tmp) = 1;
11120           DECL_ARTIFICIAL(tmp) = 1;
11121           if (!TREE_CONSTANT(init))
11122             make_tmp = fold_build2_loc(loc, INIT_EXPR, void_type_node, tmp,
11123                                        init);
11124           else
11125             {
11126               TREE_READONLY(tmp) = 1;
11127               TREE_CONSTANT(tmp) = 1;
11128               DECL_INITIAL(tmp) = init;
11129               make_tmp = NULL_TREE;
11130             }
11131           rest_of_decl_compilation(tmp, 1, 0);
11132         }
11133
11134       valaddr = build_fold_addr_expr(tmp);
11135     }
11136
11137   tree descriptor = gogo->map_descriptor(mt);
11138
11139   tree type_tree = this->type_->get_tree(gogo);
11140
11141   static tree construct_map_fndecl;
11142   tree call = Gogo::call_builtin(&construct_map_fndecl,
11143                                  loc,
11144                                  "__go_construct_map",
11145                                  6,
11146                                  type_tree,
11147                                  TREE_TYPE(descriptor),
11148                                  descriptor,
11149                                  sizetype,
11150                                  size_int(i),
11151                                  sizetype,
11152                                  TYPE_SIZE_UNIT(struct_type),
11153                                  sizetype,
11154                                  byte_position(val_field),
11155                                  sizetype,
11156                                  TYPE_SIZE_UNIT(TREE_TYPE(val_field)),
11157                                  const_ptr_type_node,
11158                                  fold_convert(const_ptr_type_node, valaddr));
11159   if (call == error_mark_node)
11160     return error_mark_node;
11161
11162   tree ret;
11163   if (make_tmp == NULL)
11164     ret = call;
11165   else
11166     ret = fold_build2_loc(loc, COMPOUND_EXPR, type_tree, make_tmp, call);
11167   return ret;
11168 }
11169
11170 // Export an array construction.
11171
11172 void
11173 Map_construction_expression::do_export(Export* exp) const
11174 {
11175   exp->write_c_string("convert(");
11176   exp->write_type(this->type_);
11177   for (Expression_list::const_iterator pv = this->vals_->begin();
11178        pv != this->vals_->end();
11179        ++pv)
11180     {
11181       exp->write_c_string(", ");
11182       (*pv)->export_expression(exp);
11183     }
11184   exp->write_c_string(")");
11185 }
11186
11187 // A general composite literal.  This is lowered to a type specific
11188 // version.
11189
11190 class Composite_literal_expression : public Parser_expression
11191 {
11192  public:
11193   Composite_literal_expression(Type* type, int depth, bool has_keys,
11194                                Expression_list* vals, source_location location)
11195     : Parser_expression(EXPRESSION_COMPOSITE_LITERAL, location),
11196       type_(type), depth_(depth), vals_(vals), has_keys_(has_keys)
11197   { }
11198
11199  protected:
11200   int
11201   do_traverse(Traverse* traverse);
11202
11203   Expression*
11204   do_lower(Gogo*, Named_object*, int);
11205
11206   Expression*
11207   do_copy()
11208   {
11209     return new Composite_literal_expression(this->type_, this->depth_,
11210                                             this->has_keys_,
11211                                             (this->vals_ == NULL
11212                                              ? NULL
11213                                              : this->vals_->copy()),
11214                                             this->location());
11215   }
11216
11217  private:
11218   Expression*
11219   lower_struct(Type*);
11220
11221   Expression*
11222   lower_array(Type*);
11223
11224   Expression*
11225   make_array(Type*, Expression_list*);
11226
11227   Expression*
11228   lower_map(Gogo*, Named_object*, Type*);
11229
11230   // The type of the composite literal.
11231   Type* type_;
11232   // The depth within a list of composite literals within a composite
11233   // literal, when the type is omitted.
11234   int depth_;
11235   // The values to put in the composite literal.
11236   Expression_list* vals_;
11237   // If this is true, then VALS_ is a list of pairs: a key and a
11238   // value.  In an array initializer, a missing key will be NULL.
11239   bool has_keys_;
11240 };
11241
11242 // Traversal.
11243
11244 int
11245 Composite_literal_expression::do_traverse(Traverse* traverse)
11246 {
11247   if (this->vals_ != NULL
11248       && this->vals_->traverse(traverse) == TRAVERSE_EXIT)
11249     return TRAVERSE_EXIT;
11250   return Type::traverse(this->type_, traverse);
11251 }
11252
11253 // Lower a generic composite literal into a specific version based on
11254 // the type.
11255
11256 Expression*
11257 Composite_literal_expression::do_lower(Gogo* gogo, Named_object* function, int)
11258 {
11259   Type* type = this->type_;
11260
11261   for (int depth = this->depth_; depth > 0; --depth)
11262     {
11263       if (type->array_type() != NULL)
11264         type = type->array_type()->element_type();
11265       else if (type->map_type() != NULL)
11266         type = type->map_type()->val_type();
11267       else
11268         {
11269           if (!type->is_error_type())
11270             error_at(this->location(),
11271                      ("may only omit types within composite literals "
11272                       "of slice, array, or map type"));
11273           return Expression::make_error(this->location());
11274         }
11275     }
11276
11277   if (type->is_error_type())
11278     return Expression::make_error(this->location());
11279   else if (type->struct_type() != NULL)
11280     return this->lower_struct(type);
11281   else if (type->array_type() != NULL)
11282     return this->lower_array(type);
11283   else if (type->map_type() != NULL)
11284     return this->lower_map(gogo, function, type);
11285   else
11286     {
11287       error_at(this->location(),
11288                ("expected struct, slice, array, or map type "
11289                 "for composite literal"));
11290       return Expression::make_error(this->location());
11291     }
11292 }
11293
11294 // Lower a struct composite literal.
11295
11296 Expression*
11297 Composite_literal_expression::lower_struct(Type* type)
11298 {
11299   source_location location = this->location();
11300   Struct_type* st = type->struct_type();
11301   if (this->vals_ == NULL || !this->has_keys_)
11302     return new Struct_construction_expression(type, this->vals_, location);
11303
11304   size_t field_count = st->field_count();
11305   std::vector<Expression*> vals(field_count);
11306   Expression_list::const_iterator p = this->vals_->begin();
11307   while (p != this->vals_->end())
11308     {
11309       Expression* name_expr = *p;
11310
11311       ++p;
11312       gcc_assert(p != this->vals_->end());
11313       Expression* val = *p;
11314
11315       ++p;
11316
11317       if (name_expr == NULL)
11318         {
11319           error_at(val->location(), "mixture of field and value initializers");
11320           return Expression::make_error(location);
11321         }
11322
11323       bool bad_key = false;
11324       std::string name;
11325       switch (name_expr->classification())
11326         {
11327         case EXPRESSION_UNKNOWN_REFERENCE:
11328           name = name_expr->unknown_expression()->name();
11329           break;
11330
11331         case EXPRESSION_CONST_REFERENCE:
11332           name = static_cast<Const_expression*>(name_expr)->name();
11333           break;
11334
11335         case EXPRESSION_TYPE:
11336           {
11337             Type* t = name_expr->type();
11338             Named_type* nt = t->named_type();
11339             if (nt == NULL)
11340               bad_key = true;
11341             else
11342               name = nt->name();
11343           }
11344           break;
11345
11346         case EXPRESSION_VAR_REFERENCE:
11347           name = name_expr->var_expression()->name();
11348           break;
11349
11350         case EXPRESSION_FUNC_REFERENCE:
11351           name = name_expr->func_expression()->name();
11352           break;
11353
11354         case EXPRESSION_UNARY:
11355           // If there is a local variable around with the same name as
11356           // the field, and this occurs in the closure, then the
11357           // parser may turn the field reference into an indirection
11358           // through the closure.  FIXME: This is a mess.
11359           {
11360             bad_key = true;
11361             Unary_expression* ue = static_cast<Unary_expression*>(name_expr);
11362             if (ue->op() == OPERATOR_MULT)
11363               {
11364                 Field_reference_expression* fre =
11365                   ue->operand()->field_reference_expression();
11366                 if (fre != NULL)
11367                   {
11368                     Struct_type* st =
11369                       fre->expr()->type()->deref()->struct_type();
11370                     if (st != NULL)
11371                       {
11372                         const Struct_field* sf = st->field(fre->field_index());
11373                         name = sf->field_name();
11374                         char buf[20];
11375                         snprintf(buf, sizeof buf, "%u", fre->field_index());
11376                         size_t buflen = strlen(buf);
11377                         if (name.compare(name.length() - buflen, buflen, buf)
11378                             == 0)
11379                           {
11380                             name = name.substr(0, name.length() - buflen);
11381                             bad_key = false;
11382                           }
11383                       }
11384                   }
11385               }
11386           }
11387           break;
11388
11389         default:
11390           bad_key = true;
11391           break;
11392         }
11393       if (bad_key)
11394         {
11395           error_at(name_expr->location(), "expected struct field name");
11396           return Expression::make_error(location);
11397         }
11398
11399       unsigned int index;
11400       const Struct_field* sf = st->find_local_field(name, &index);
11401       if (sf == NULL)
11402         {
11403           error_at(name_expr->location(), "unknown field %qs in %qs",
11404                    Gogo::message_name(name).c_str(),
11405                    (type->named_type() != NULL
11406                     ? type->named_type()->message_name().c_str()
11407                     : "unnamed struct"));
11408           return Expression::make_error(location);
11409         }
11410       if (vals[index] != NULL)
11411         {
11412           error_at(name_expr->location(),
11413                    "duplicate value for field %qs in %qs",
11414                    Gogo::message_name(name).c_str(),
11415                    (type->named_type() != NULL
11416                     ? type->named_type()->message_name().c_str()
11417                     : "unnamed struct"));
11418           return Expression::make_error(location);
11419         }
11420
11421       vals[index] = val;
11422     }
11423
11424   Expression_list* list = new Expression_list;
11425   list->reserve(field_count);
11426   for (size_t i = 0; i < field_count; ++i)
11427     list->push_back(vals[i]);
11428
11429   return new Struct_construction_expression(type, list, location);
11430 }
11431
11432 // Lower an array composite literal.
11433
11434 Expression*
11435 Composite_literal_expression::lower_array(Type* type)
11436 {
11437   source_location location = this->location();
11438   if (this->vals_ == NULL || !this->has_keys_)
11439     return this->make_array(type, this->vals_);
11440
11441   std::vector<Expression*> vals;
11442   vals.reserve(this->vals_->size());
11443   unsigned long index = 0;
11444   Expression_list::const_iterator p = this->vals_->begin();
11445   while (p != this->vals_->end())
11446     {
11447       Expression* index_expr = *p;
11448
11449       ++p;
11450       gcc_assert(p != this->vals_->end());
11451       Expression* val = *p;
11452
11453       ++p;
11454
11455       if (index_expr != NULL)
11456         {
11457           mpz_t ival;
11458           mpz_init(ival);
11459           Type* dummy;
11460           if (!index_expr->integer_constant_value(true, ival, &dummy))
11461             {
11462               mpz_clear(ival);
11463               error_at(index_expr->location(),
11464                        "index expression is not integer constant");
11465               return Expression::make_error(location);
11466             }
11467           if (mpz_sgn(ival) < 0)
11468             {
11469               mpz_clear(ival);
11470               error_at(index_expr->location(), "index expression is negative");
11471               return Expression::make_error(location);
11472             }
11473           index = mpz_get_ui(ival);
11474           if (mpz_cmp_ui(ival, index) != 0)
11475             {
11476               mpz_clear(ival);
11477               error_at(index_expr->location(), "index value overflow");
11478               return Expression::make_error(location);
11479             }
11480           mpz_clear(ival);
11481         }
11482
11483       if (index == vals.size())
11484         vals.push_back(val);
11485       else
11486         {
11487           if (index > vals.size())
11488             {
11489               vals.reserve(index + 32);
11490               vals.resize(index + 1, static_cast<Expression*>(NULL));
11491             }
11492           if (vals[index] != NULL)
11493             {
11494               error_at((index_expr != NULL
11495                         ? index_expr->location()
11496                         : val->location()),
11497                        "duplicate value for index %lu",
11498                        index);
11499               return Expression::make_error(location);
11500             }
11501           vals[index] = val;
11502         }
11503
11504       ++index;
11505     }
11506
11507   size_t size = vals.size();
11508   Expression_list* list = new Expression_list;
11509   list->reserve(size);
11510   for (size_t i = 0; i < size; ++i)
11511     list->push_back(vals[i]);
11512
11513   return this->make_array(type, list);
11514 }
11515
11516 // Actually build the array composite literal. This handles
11517 // [...]{...}.
11518
11519 Expression*
11520 Composite_literal_expression::make_array(Type* type, Expression_list* vals)
11521 {
11522   source_location location = this->location();
11523   Array_type* at = type->array_type();
11524   if (at->length() != NULL && at->length()->is_nil_expression())
11525     {
11526       size_t size = vals == NULL ? 0 : vals->size();
11527       mpz_t vlen;
11528       mpz_init_set_ui(vlen, size);
11529       Expression* elen = Expression::make_integer(&vlen, NULL, location);
11530       mpz_clear(vlen);
11531       at = Type::make_array_type(at->element_type(), elen);
11532       type = at;
11533     }
11534   if (at->length() != NULL)
11535     return new Fixed_array_construction_expression(type, vals, location);
11536   else
11537     return new Open_array_construction_expression(type, vals, location);
11538 }
11539
11540 // Lower a map composite literal.
11541
11542 Expression*
11543 Composite_literal_expression::lower_map(Gogo* gogo, Named_object* function,
11544                                         Type* type)
11545 {
11546   source_location location = this->location();
11547   if (this->vals_ != NULL)
11548     {
11549       if (!this->has_keys_)
11550         {
11551           error_at(location, "map composite literal must have keys");
11552           return Expression::make_error(location);
11553         }
11554
11555       for (Expression_list::iterator p = this->vals_->begin();
11556            p != this->vals_->end();
11557            p += 2)
11558         {
11559           if (*p == NULL)
11560             {
11561               ++p;
11562               error_at((*p)->location(),
11563                        "map composite literal must have keys for every value");
11564               return Expression::make_error(location);
11565             }
11566           // Make sure we have lowered the key; it may not have been
11567           // lowered in order to handle keys for struct composite
11568           // literals.  Lower it now to get the right error message.
11569           if ((*p)->unknown_expression() != NULL)
11570             {
11571               (*p)->unknown_expression()->clear_is_composite_literal_key();
11572               gogo->lower_expression(function, &*p);
11573               gcc_assert((*p)->is_error_expression());
11574               return Expression::make_error(location);
11575             }
11576         }
11577     }
11578
11579   return new Map_construction_expression(type, this->vals_, location);
11580 }
11581
11582 // Make a composite literal expression.
11583
11584 Expression*
11585 Expression::make_composite_literal(Type* type, int depth, bool has_keys,
11586                                    Expression_list* vals,
11587                                    source_location location)
11588 {
11589   return new Composite_literal_expression(type, depth, has_keys, vals,
11590                                           location);
11591 }
11592
11593 // Return whether this expression is a composite literal.
11594
11595 bool
11596 Expression::is_composite_literal() const
11597 {
11598   switch (this->classification_)
11599     {
11600     case EXPRESSION_COMPOSITE_LITERAL:
11601     case EXPRESSION_STRUCT_CONSTRUCTION:
11602     case EXPRESSION_FIXED_ARRAY_CONSTRUCTION:
11603     case EXPRESSION_OPEN_ARRAY_CONSTRUCTION:
11604     case EXPRESSION_MAP_CONSTRUCTION:
11605       return true;
11606     default:
11607       return false;
11608     }
11609 }
11610
11611 // Return whether this expression is a composite literal which is not
11612 // constant.
11613
11614 bool
11615 Expression::is_nonconstant_composite_literal() const
11616 {
11617   switch (this->classification_)
11618     {
11619     case EXPRESSION_STRUCT_CONSTRUCTION:
11620       {
11621         const Struct_construction_expression *psce =
11622           static_cast<const Struct_construction_expression*>(this);
11623         return !psce->is_constant_struct();
11624       }
11625     case EXPRESSION_FIXED_ARRAY_CONSTRUCTION:
11626       {
11627         const Fixed_array_construction_expression *pace =
11628           static_cast<const Fixed_array_construction_expression*>(this);
11629         return !pace->is_constant_array();
11630       }
11631     case EXPRESSION_OPEN_ARRAY_CONSTRUCTION:
11632       {
11633         const Open_array_construction_expression *pace =
11634           static_cast<const Open_array_construction_expression*>(this);
11635         return !pace->is_constant_array();
11636       }
11637     case EXPRESSION_MAP_CONSTRUCTION:
11638       return true;
11639     default:
11640       return false;
11641     }
11642 }
11643
11644 // Return true if this is a reference to a local variable.
11645
11646 bool
11647 Expression::is_local_variable() const
11648 {
11649   const Var_expression* ve = this->var_expression();
11650   if (ve == NULL)
11651     return false;
11652   const Named_object* no = ve->named_object();
11653   return (no->is_result_variable()
11654           || (no->is_variable() && !no->var_value()->is_global()));
11655 }
11656
11657 // Class Type_guard_expression.
11658
11659 // Traversal.
11660
11661 int
11662 Type_guard_expression::do_traverse(Traverse* traverse)
11663 {
11664   if (Expression::traverse(&this->expr_, traverse) == TRAVERSE_EXIT
11665       || Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
11666     return TRAVERSE_EXIT;
11667   return TRAVERSE_CONTINUE;
11668 }
11669
11670 // Check types of a type guard expression.  The expression must have
11671 // an interface type, but the actual type conversion is checked at run
11672 // time.
11673
11674 void
11675 Type_guard_expression::do_check_types(Gogo*)
11676 {
11677   // 6g permits using a type guard with unsafe.pointer; we are
11678   // compatible.
11679   Type* expr_type = this->expr_->type();
11680   if (expr_type->is_unsafe_pointer_type())
11681     {
11682       if (this->type_->points_to() == NULL
11683           && (this->type_->integer_type() == NULL
11684               || (this->type_->forwarded()
11685                   != Type::lookup_integer_type("uintptr"))))
11686         this->report_error(_("invalid unsafe.Pointer conversion"));
11687     }
11688   else if (this->type_->is_unsafe_pointer_type())
11689     {
11690       if (expr_type->points_to() == NULL
11691           && (expr_type->integer_type() == NULL
11692               || (expr_type->forwarded()
11693                   != Type::lookup_integer_type("uintptr"))))
11694         this->report_error(_("invalid unsafe.Pointer conversion"));
11695     }
11696   else if (expr_type->interface_type() == NULL)
11697     {
11698       if (!expr_type->is_error_type() && !this->type_->is_error_type())
11699         this->report_error(_("type assertion only valid for interface types"));
11700       this->set_is_error();
11701     }
11702   else if (this->type_->interface_type() == NULL)
11703     {
11704       std::string reason;
11705       if (!expr_type->interface_type()->implements_interface(this->type_,
11706                                                              &reason))
11707         {
11708           if (!this->type_->is_error_type())
11709             {
11710               if (reason.empty())
11711                 this->report_error(_("impossible type assertion: "
11712                                      "type does not implement interface"));
11713               else
11714                 error_at(this->location(),
11715                          ("impossible type assertion: "
11716                           "type does not implement interface (%s)"),
11717                          reason.c_str());
11718             }
11719           this->set_is_error();
11720         }
11721     }
11722 }
11723
11724 // Return a tree for a type guard expression.
11725
11726 tree
11727 Type_guard_expression::do_get_tree(Translate_context* context)
11728 {
11729   Gogo* gogo = context->gogo();
11730   tree expr_tree = this->expr_->get_tree(context);
11731   if (expr_tree == error_mark_node)
11732     return error_mark_node;
11733   Type* expr_type = this->expr_->type();
11734   if ((this->type_->is_unsafe_pointer_type()
11735        && (expr_type->points_to() != NULL
11736            || expr_type->integer_type() != NULL))
11737       || (expr_type->is_unsafe_pointer_type()
11738           && this->type_->points_to() != NULL))
11739     return convert_to_pointer(this->type_->get_tree(gogo), expr_tree);
11740   else if (expr_type->is_unsafe_pointer_type()
11741            && this->type_->integer_type() != NULL)
11742     return convert_to_integer(this->type_->get_tree(gogo), expr_tree);
11743   else if (this->type_->interface_type() != NULL)
11744     return Expression::convert_interface_to_interface(context, this->type_,
11745                                                       this->expr_->type(),
11746                                                       expr_tree, true,
11747                                                       this->location());
11748   else
11749     return Expression::convert_for_assignment(context, this->type_,
11750                                               this->expr_->type(), expr_tree,
11751                                               this->location());
11752 }
11753
11754 // Make a type guard expression.
11755
11756 Expression*
11757 Expression::make_type_guard(Expression* expr, Type* type,
11758                             source_location location)
11759 {
11760   return new Type_guard_expression(expr, type, location);
11761 }
11762
11763 // Class Heap_composite_expression.
11764
11765 // When you take the address of a composite literal, it is allocated
11766 // on the heap.  This class implements that.
11767
11768 class Heap_composite_expression : public Expression
11769 {
11770  public:
11771   Heap_composite_expression(Expression* expr, source_location location)
11772     : Expression(EXPRESSION_HEAP_COMPOSITE, location),
11773       expr_(expr)
11774   { }
11775
11776  protected:
11777   int
11778   do_traverse(Traverse* traverse)
11779   { return Expression::traverse(&this->expr_, traverse); }
11780
11781   Type*
11782   do_type()
11783   { return Type::make_pointer_type(this->expr_->type()); }
11784
11785   void
11786   do_determine_type(const Type_context*)
11787   { this->expr_->determine_type_no_context(); }
11788
11789   Expression*
11790   do_copy()
11791   {
11792     return Expression::make_heap_composite(this->expr_->copy(),
11793                                            this->location());
11794   }
11795
11796   tree
11797   do_get_tree(Translate_context*);
11798
11799   // We only export global objects, and the parser does not generate
11800   // this in global scope.
11801   void
11802   do_export(Export*) const
11803   { gcc_unreachable(); }
11804
11805  private:
11806   // The composite literal which is being put on the heap.
11807   Expression* expr_;
11808 };
11809
11810 // Return a tree which allocates a composite literal on the heap.
11811
11812 tree
11813 Heap_composite_expression::do_get_tree(Translate_context* context)
11814 {
11815   tree expr_tree = this->expr_->get_tree(context);
11816   if (expr_tree == error_mark_node)
11817     return error_mark_node;
11818   tree expr_size = TYPE_SIZE_UNIT(TREE_TYPE(expr_tree));
11819   gcc_assert(TREE_CODE(expr_size) == INTEGER_CST);
11820   tree space = context->gogo()->allocate_memory(this->expr_->type(),
11821                                                 expr_size, this->location());
11822   space = fold_convert(build_pointer_type(TREE_TYPE(expr_tree)), space);
11823   space = save_expr(space);
11824   tree ref = build_fold_indirect_ref_loc(this->location(), space);
11825   TREE_THIS_NOTRAP(ref) = 1;
11826   tree ret = build2(COMPOUND_EXPR, TREE_TYPE(space),
11827                     build2(MODIFY_EXPR, void_type_node, ref, expr_tree),
11828                     space);
11829   SET_EXPR_LOCATION(ret, this->location());
11830   return ret;
11831 }
11832
11833 // Allocate a composite literal on the heap.
11834
11835 Expression*
11836 Expression::make_heap_composite(Expression* expr, source_location location)
11837 {
11838   return new Heap_composite_expression(expr, location);
11839 }
11840
11841 // Class Receive_expression.
11842
11843 // Return the type of a receive expression.
11844
11845 Type*
11846 Receive_expression::do_type()
11847 {
11848   Channel_type* channel_type = this->channel_->type()->channel_type();
11849   if (channel_type == NULL)
11850     return Type::make_error_type();
11851   return channel_type->element_type();
11852 }
11853
11854 // Check types for a receive expression.
11855
11856 void
11857 Receive_expression::do_check_types(Gogo*)
11858 {
11859   Type* type = this->channel_->type();
11860   if (type->is_error_type())
11861     {
11862       this->set_is_error();
11863       return;
11864     }
11865   if (type->channel_type() == NULL)
11866     {
11867       this->report_error(_("expected channel"));
11868       return;
11869     }
11870   if (!type->channel_type()->may_receive())
11871     {
11872       this->report_error(_("invalid receive on send-only channel"));
11873       return;
11874     }
11875 }
11876
11877 // Get a tree for a receive expression.
11878
11879 tree
11880 Receive_expression::do_get_tree(Translate_context* context)
11881 {
11882   Channel_type* channel_type = this->channel_->type()->channel_type();
11883   gcc_assert(channel_type != NULL);
11884   Type* element_type = channel_type->element_type();
11885   tree element_type_tree = element_type->get_tree(context->gogo());
11886
11887   tree channel = this->channel_->get_tree(context);
11888   if (element_type_tree == error_mark_node || channel == error_mark_node)
11889     return error_mark_node;
11890
11891   return Gogo::receive_from_channel(element_type_tree, channel,
11892                                     this->for_select_, this->location());
11893 }
11894
11895 // Make a receive expression.
11896
11897 Receive_expression*
11898 Expression::make_receive(Expression* channel, source_location location)
11899 {
11900   return new Receive_expression(channel, location);
11901 }
11902
11903 // Class Send_expression.
11904
11905 // Traversal.
11906
11907 int
11908 Send_expression::do_traverse(Traverse* traverse)
11909 {
11910   if (Expression::traverse(&this->channel_, traverse) == TRAVERSE_EXIT)
11911     return TRAVERSE_EXIT;
11912   return Expression::traverse(&this->val_, traverse);
11913 }
11914
11915 // Get the type.
11916
11917 Type*
11918 Send_expression::do_type()
11919 {
11920   return Type::lookup_bool_type();
11921 }
11922
11923 // Set types.
11924
11925 void
11926 Send_expression::do_determine_type(const Type_context*)
11927 {
11928   this->channel_->determine_type_no_context();
11929
11930   Type* type = this->channel_->type();
11931   Type_context subcontext;
11932   if (type->channel_type() != NULL)
11933     subcontext.type = type->channel_type()->element_type();
11934   this->val_->determine_type(&subcontext);
11935 }
11936
11937 // Check types.
11938
11939 void
11940 Send_expression::do_check_types(Gogo*)
11941 {
11942   Type* type = this->channel_->type();
11943   if (type->is_error_type())
11944     {
11945       this->set_is_error();
11946       return;
11947     }
11948   Channel_type* channel_type = type->channel_type();
11949   if (channel_type == NULL)
11950     {
11951       error_at(this->location(), "left operand of %<<-%> must be channel");
11952       this->set_is_error();
11953       return;
11954     }
11955   Type* element_type = channel_type->element_type();
11956   if (element_type != NULL
11957       && !Type::are_assignable(element_type, this->val_->type(), NULL))
11958     {
11959       this->report_error(_("incompatible types in send"));
11960       return;
11961     }
11962   if (!channel_type->may_send())
11963     {
11964       this->report_error(_("invalid send on receive-only channel"));
11965       return;
11966     }
11967 }
11968
11969 // Get a tree for a send expression.
11970
11971 tree
11972 Send_expression::do_get_tree(Translate_context* context)
11973 {
11974   tree channel = this->channel_->get_tree(context);
11975   tree val = this->val_->get_tree(context);
11976   if (channel == error_mark_node || val == error_mark_node)
11977     return error_mark_node;
11978   Channel_type* channel_type = this->channel_->type()->channel_type();
11979   val = Expression::convert_for_assignment(context,
11980                                            channel_type->element_type(),
11981                                            this->val_->type(),
11982                                            val,
11983                                            this->location());
11984   return Gogo::send_on_channel(channel, val, this->is_value_discarded_,
11985                                this->for_select_, this->location());
11986 }
11987
11988 // Make a send expression
11989
11990 Send_expression*
11991 Expression::make_send(Expression* channel, Expression* val,
11992                       source_location location)
11993 {
11994   return new Send_expression(channel, val, location);
11995 }
11996
11997 // An expression which evaluates to a pointer to the type descriptor
11998 // of a type.
11999
12000 class Type_descriptor_expression : public Expression
12001 {
12002  public:
12003   Type_descriptor_expression(Type* type, source_location location)
12004     : Expression(EXPRESSION_TYPE_DESCRIPTOR, location),
12005       type_(type)
12006   { }
12007
12008  protected:
12009   Type*
12010   do_type()
12011   { return Type::make_type_descriptor_ptr_type(); }
12012
12013   void
12014   do_determine_type(const Type_context*)
12015   { }
12016
12017   Expression*
12018   do_copy()
12019   { return this; }
12020
12021   tree
12022   do_get_tree(Translate_context* context)
12023   { return this->type_->type_descriptor_pointer(context->gogo()); }
12024
12025  private:
12026   // The type for which this is the descriptor.
12027   Type* type_;
12028 };
12029
12030 // Make a type descriptor expression.
12031
12032 Expression*
12033 Expression::make_type_descriptor(Type* type, source_location location)
12034 {
12035   return new Type_descriptor_expression(type, location);
12036 }
12037
12038 // An expression which evaluates to some characteristic of a type.
12039 // This is only used to initialize fields of a type descriptor.  Using
12040 // a new expression class is slightly inefficient but gives us a good
12041 // separation between the frontend and the middle-end with regard to
12042 // how types are laid out.
12043
12044 class Type_info_expression : public Expression
12045 {
12046  public:
12047   Type_info_expression(Type* type, Type_info type_info)
12048     : Expression(EXPRESSION_TYPE_INFO, BUILTINS_LOCATION),
12049       type_(type), type_info_(type_info)
12050   { }
12051
12052  protected:
12053   Type*
12054   do_type();
12055
12056   void
12057   do_determine_type(const Type_context*)
12058   { }
12059
12060   Expression*
12061   do_copy()
12062   { return this; }
12063
12064   tree
12065   do_get_tree(Translate_context* context);
12066
12067  private:
12068   // The type for which we are getting information.
12069   Type* type_;
12070   // What information we want.
12071   Type_info type_info_;
12072 };
12073
12074 // The type is chosen to match what the type descriptor struct
12075 // expects.
12076
12077 Type*
12078 Type_info_expression::do_type()
12079 {
12080   switch (this->type_info_)
12081     {
12082     case TYPE_INFO_SIZE:
12083       return Type::lookup_integer_type("uintptr");
12084     case TYPE_INFO_ALIGNMENT:
12085     case TYPE_INFO_FIELD_ALIGNMENT:
12086       return Type::lookup_integer_type("uint8");
12087     default:
12088       gcc_unreachable();
12089     }
12090 }
12091
12092 // Return type information in GENERIC.
12093
12094 tree
12095 Type_info_expression::do_get_tree(Translate_context* context)
12096 {
12097   tree type_tree = this->type_->get_tree(context->gogo());
12098   if (type_tree == error_mark_node)
12099     return error_mark_node;
12100
12101   tree val_type_tree = this->type()->get_tree(context->gogo());
12102   gcc_assert(val_type_tree != error_mark_node);
12103
12104   if (this->type_info_ == TYPE_INFO_SIZE)
12105     return fold_convert_loc(BUILTINS_LOCATION, val_type_tree,
12106                             TYPE_SIZE_UNIT(type_tree));
12107   else
12108     {
12109       unsigned int val;
12110       if (this->type_info_ == TYPE_INFO_ALIGNMENT)
12111         val = go_type_alignment(type_tree);
12112       else
12113         val = go_field_alignment(type_tree);
12114       return build_int_cstu(val_type_tree, val);
12115     }
12116 }
12117
12118 // Make a type info expression.
12119
12120 Expression*
12121 Expression::make_type_info(Type* type, Type_info type_info)
12122 {
12123   return new Type_info_expression(type, type_info);
12124 }
12125
12126 // An expression which evaluates to the offset of a field within a
12127 // struct.  This, like Type_info_expression, q.v., is only used to
12128 // initialize fields of a type descriptor.
12129
12130 class Struct_field_offset_expression : public Expression
12131 {
12132  public:
12133   Struct_field_offset_expression(Struct_type* type, const Struct_field* field)
12134     : Expression(EXPRESSION_STRUCT_FIELD_OFFSET, BUILTINS_LOCATION),
12135       type_(type), field_(field)
12136   { }
12137
12138  protected:
12139   Type*
12140   do_type()
12141   { return Type::lookup_integer_type("uintptr"); }
12142
12143   void
12144   do_determine_type(const Type_context*)
12145   { }
12146
12147   Expression*
12148   do_copy()
12149   { return this; }
12150
12151   tree
12152   do_get_tree(Translate_context* context);
12153
12154  private:
12155   // The type of the struct.
12156   Struct_type* type_;
12157   // The field.
12158   const Struct_field* field_;
12159 };
12160
12161 // Return a struct field offset in GENERIC.
12162
12163 tree
12164 Struct_field_offset_expression::do_get_tree(Translate_context* context)
12165 {
12166   tree type_tree = this->type_->get_tree(context->gogo());
12167   if (type_tree == error_mark_node)
12168     return error_mark_node;
12169
12170   tree val_type_tree = this->type()->get_tree(context->gogo());
12171   gcc_assert(val_type_tree != error_mark_node);
12172
12173   const Struct_field_list* fields = this->type_->fields();
12174   tree struct_field_tree = TYPE_FIELDS(type_tree);
12175   Struct_field_list::const_iterator p;
12176   for (p = fields->begin();
12177        p != fields->end();
12178        ++p, struct_field_tree = DECL_CHAIN(struct_field_tree))
12179     {
12180       gcc_assert(struct_field_tree != NULL_TREE);
12181       if (&*p == this->field_)
12182         break;
12183     }
12184   gcc_assert(&*p == this->field_);
12185
12186   return fold_convert_loc(BUILTINS_LOCATION, val_type_tree,
12187                           byte_position(struct_field_tree));
12188 }
12189
12190 // Make an expression for a struct field offset.
12191
12192 Expression*
12193 Expression::make_struct_field_offset(Struct_type* type,
12194                                      const Struct_field* field)
12195 {
12196   return new Struct_field_offset_expression(type, field);
12197 }
12198
12199 // An expression which evaluates to the address of an unnamed label.
12200
12201 class Label_addr_expression : public Expression
12202 {
12203  public:
12204   Label_addr_expression(Label* label, source_location location)
12205     : Expression(EXPRESSION_LABEL_ADDR, location),
12206       label_(label)
12207   { }
12208
12209  protected:
12210   Type*
12211   do_type()
12212   { return Type::make_pointer_type(Type::make_void_type()); }
12213
12214   void
12215   do_determine_type(const Type_context*)
12216   { }
12217
12218   Expression*
12219   do_copy()
12220   { return new Label_addr_expression(this->label_, this->location()); }
12221
12222   tree
12223   do_get_tree(Translate_context*)
12224   { return this->label_->get_addr(this->location()); }
12225
12226  private:
12227   // The label whose address we are taking.
12228   Label* label_;
12229 };
12230
12231 // Make an expression for the address of an unnamed label.
12232
12233 Expression*
12234 Expression::make_label_addr(Label* label, source_location location)
12235 {
12236   return new Label_addr_expression(label, location);
12237 }
12238
12239 // Import an expression.  This comes at the end in order to see the
12240 // various class definitions.
12241
12242 Expression*
12243 Expression::import_expression(Import* imp)
12244 {
12245   int c = imp->peek_char();
12246   if (imp->match_c_string("- ")
12247       || imp->match_c_string("! ")
12248       || imp->match_c_string("^ "))
12249     return Unary_expression::do_import(imp);
12250   else if (c == '(')
12251     return Binary_expression::do_import(imp);
12252   else if (imp->match_c_string("true")
12253            || imp->match_c_string("false"))
12254     return Boolean_expression::do_import(imp);
12255   else if (c == '"')
12256     return String_expression::do_import(imp);
12257   else if (c == '-' || (c >= '0' && c <= '9'))
12258     {
12259       // This handles integers, floats and complex constants.
12260       return Integer_expression::do_import(imp);
12261     }
12262   else if (imp->match_c_string("nil"))
12263     return Nil_expression::do_import(imp);
12264   else if (imp->match_c_string("convert"))
12265     return Type_conversion_expression::do_import(imp);
12266   else
12267     {
12268       error_at(imp->location(), "import error: expected expression");
12269       return Expression::make_error(imp->location());
12270     }
12271 }
12272
12273 // Class Expression_list.
12274
12275 // Traverse the list.
12276
12277 int
12278 Expression_list::traverse(Traverse* traverse)
12279 {
12280   for (Expression_list::iterator p = this->begin();
12281        p != this->end();
12282        ++p)
12283     {
12284       if (*p != NULL)
12285         {
12286           if (Expression::traverse(&*p, traverse) == TRAVERSE_EXIT)
12287             return TRAVERSE_EXIT;
12288         }
12289     }
12290   return TRAVERSE_CONTINUE;
12291 }
12292
12293 // Copy the list.
12294
12295 Expression_list*
12296 Expression_list::copy()
12297 {
12298   Expression_list* ret = new Expression_list();
12299   for (Expression_list::iterator p = this->begin();
12300        p != this->end();
12301        ++p)
12302     {
12303       if (*p == NULL)
12304         ret->push_back(NULL);
12305       else
12306         ret->push_back((*p)->copy());
12307     }
12308   return ret;
12309 }
12310
12311 // Return whether an expression list has an error expression.
12312
12313 bool
12314 Expression_list::contains_error() const
12315 {
12316   for (Expression_list::const_iterator p = this->begin();
12317        p != this->end();
12318        ++p)
12319     if (*p != NULL && (*p)->is_error_expression())
12320       return true;
12321   return false;
12322 }