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 Parser_expression.
 898
 899 Type*
 900 Parser_expression::do_type()
 901 {
 902   // We should never really ask for the type of a Parser_expression.
 903   // However, it can happen, at least when we have an invalid const
 904   // whose initializer refers to the const itself.  In that case we
 905   // may ask for the type when lowering the const itself.
 906   gcc_assert(saw_errors());
 907   return Type::make_error_type();
 908 }
 909
 910 // Class Var_expression.
 911
 912 // Lower a variable expression.  Here we just make sure that the
 913 // initialization expression of the variable has been lowered.  This
 914 // ensures that we will be able to determine the type of the variable
 915 // if necessary.
 916
 917 Expression*
 918 Var_expression::do_lower(Gogo* gogo, Named_object* function, int)
 919 {
 920   if (this->variable_->is_variable())
 921     {
 922       Variable* var = this->variable_->var_value();
 923       // This is either a local variable or a global variable.  A
 924       // reference to a variable which is local to an enclosing
 925       // function will be a reference to a field in a closure.
 926       if (var->is_global())
 927         function = NULL;
 928       var->lower_init_expression(gogo, function);
 929     }
 930   return this;
 931 }
 932
 933 // Return the name of the variable.
 934
 935 const std::string&
 936 Var_expression::name() const
 937 {
 938   return this->variable_->name();
 939 }
 940
 941 // Return the type of a reference to a variable.
 942
 943 Type*
 944 Var_expression::do_type()
 945 {
 946   if (this->variable_->is_variable())
 947     return this->variable_->var_value()->type();
 948   else if (this->variable_->is_result_variable())
 949     return this->variable_->result_var_value()->type();
 950   else
 951     gcc_unreachable();
 952 }
 953
 954 // Something takes the address of this variable.  This means that we
 955 // may want to move the variable onto the heap.
 956
 957 void
 958 Var_expression::do_address_taken(bool escapes)
 959 {
 960   if (!escapes)
 961     ;
 962   else if (this->variable_->is_variable())
 963     this->variable_->var_value()->set_address_taken();
 964   else if (this->variable_->is_result_variable())
 965     this->variable_->result_var_value()->set_address_taken();
 966   else
 967     gcc_unreachable();
 968 }
 969
 970 // Get the tree for a reference to a variable.
 971
 972 tree
 973 Var_expression::do_get_tree(Translate_context* context)
 974 {
 975   return this->variable_->get_tree(context->gogo(), context->function());
 976 }
 977
 978 // Make a reference to a variable in an expression.
 979
 980 Expression*
 981 Expression::make_var_reference(Named_object* var, source_location location)
 982 {
 983   if (var->is_sink())
 984     return Expression::make_sink(location);
 985
 986   // FIXME: Creating a new object for each reference to a variable is
 987   // wasteful.
 988   return new Var_expression(var, location);
 989 }
 990
 991 // Class Temporary_reference_expression.
 992
 993 // The type.
 994
 995 Type*
 996 Temporary_reference_expression::do_type()
 997 {
 998   return this->statement_->type();
 999 }
1000
1001 // Called if something takes the address of this temporary variable.
1002 // We never have to move temporary variables to the heap, but we do
1003 // need to know that they must live in the stack rather than in a
1004 // register.
1005
1006 void
1007 Temporary_reference_expression::do_address_taken(bool)
1008 {
1009   this->statement_->set_is_address_taken();
1010 }
1011
1012 // Get a tree referring to the variable.
1013
1014 tree
1015 Temporary_reference_expression::do_get_tree(Translate_context*)
1016 {
1017   return this->statement_->get_decl();
1018 }
1019
1020 // Make a reference to a temporary variable.
1021
1022 Expression*
1023 Expression::make_temporary_reference(Temporary_statement* statement,
1024                                      source_location location)
1025 {
1026   return new Temporary_reference_expression(statement, location);
1027 }
1028
1029 // A sink expression--a use of the blank identifier _.
1030
1031 class Sink_expression : public Expression
1032 {
1033  public:
1034   Sink_expression(source_location location)
1035     : Expression(EXPRESSION_SINK, location),
1036       type_(NULL), var_(NULL_TREE)
1037   { }
1038
1039  protected:
1040   void
1041   do_discarding_value()
1042   { }
1043
1044   Type*
1045   do_type();
1046
1047   void
1048   do_determine_type(const Type_context*);
1049
1050   Expression*
1051   do_copy()
1052   { return new Sink_expression(this->location()); }
1053
1054   tree
1055   do_get_tree(Translate_context*);
1056
1057  private:
1058   // The type of this sink variable.
1059   Type* type_;
1060   // The temporary variable we generate.
1061   tree var_;
1062 };
1063
1064 // Return the type of a sink expression.
1065
1066 Type*
1067 Sink_expression::do_type()
1068 {
1069   if (this->type_ == NULL)
1070     return Type::make_sink_type();
1071   return this->type_;
1072 }
1073
1074 // Determine the type of a sink expression.
1075
1076 void
1077 Sink_expression::do_determine_type(const Type_context* context)
1078 {
1079   if (context->type != NULL)
1080     this->type_ = context->type;
1081 }
1082
1083 // Return a temporary variable for a sink expression.  This will
1084 // presumably be a write-only variable which the middle-end will drop.
1085
1086 tree
1087 Sink_expression::do_get_tree(Translate_context* context)
1088 {
1089   if (this->var_ == NULL_TREE)
1090     {
1091       gcc_assert(this->type_ != NULL && !this->type_->is_sink_type());
1092       this->var_ = create_tmp_var(this->type_->get_tree(context->gogo()),
1093                                   "blank");
1094     }
1095   return this->var_;
1096 }
1097
1098 // Make a sink expression.
1099
1100 Expression*
1101 Expression::make_sink(source_location location)
1102 {
1103   return new Sink_expression(location);
1104 }
1105
1106 // Class Func_expression.
1107
1108 // FIXME: Can a function expression appear in a constant expression?
1109 // The value is unchanging.  Initializing a constant to the address of
1110 // a function seems like it could work, though there might be little
1111 // point to it.
1112
1113 // Return the name of the function.
1114
1115 const std::string&
1116 Func_expression::name() const
1117 {
1118   return this->function_->name();
1119 }
1120
1121 // Traversal.
1122
1123 int
1124 Func_expression::do_traverse(Traverse* traverse)
1125 {
1126   return (this->closure_ == NULL
1127           ? TRAVERSE_CONTINUE
1128           : Expression::traverse(&this->closure_, traverse));
1129 }
1130
1131 // Return the type of a function expression.
1132
1133 Type*
1134 Func_expression::do_type()
1135 {
1136   if (this->function_->is_function())
1137     return this->function_->func_value()->type();
1138   else if (this->function_->is_function_declaration())
1139     return this->function_->func_declaration_value()->type();
1140   else
1141     gcc_unreachable();
1142 }
1143
1144 // Get the tree for a function expression without evaluating the
1145 // closure.
1146
1147 tree
1148 Func_expression::get_tree_without_closure(Gogo* gogo)
1149 {
1150   Function_type* fntype;
1151   if (this->function_->is_function())
1152     fntype = this->function_->func_value()->type();
1153   else if (this->function_->is_function_declaration())
1154     fntype = this->function_->func_declaration_value()->type();
1155   else
1156     gcc_unreachable();
1157
1158   // Builtin functions are handled specially by Call_expression.  We
1159   // can't take their address.
1160   if (fntype->is_builtin())
1161     {
1162       error_at(this->location(), "invalid use of special builtin function %qs",
1163                this->function_->name().c_str());
1164       return error_mark_node;
1165     }
1166
1167   Named_object* no = this->function_;
1168
1169   tree id = no->get_id(gogo);
1170   if (id == error_mark_node)
1171     return error_mark_node;
1172
1173   tree fndecl;
1174   if (no->is_function())
1175     fndecl = no->func_value()->get_or_make_decl(gogo, no, id);
1176   else if (no->is_function_declaration())
1177     fndecl = no->func_declaration_value()->get_or_make_decl(gogo, no, id);
1178   else
1179     gcc_unreachable();
1180
1181   if (fndecl == error_mark_node)
1182     return error_mark_node;
1183
1184   return build_fold_addr_expr_loc(this->location(), fndecl);
1185 }
1186
1187 // Get the tree for a function expression.  This is used when we take
1188 // the address of a function rather than simply calling it.  If the
1189 // function has a closure, we must use a trampoline.
1190
1191 tree
1192 Func_expression::do_get_tree(Translate_context* context)
1193 {
1194   Gogo* gogo = context->gogo();
1195
1196   tree fnaddr = this->get_tree_without_closure(gogo);
1197   if (fnaddr == error_mark_node)
1198     return error_mark_node;
1199
1200   gcc_assert(TREE_CODE(fnaddr) == ADDR_EXPR
1201              && TREE_CODE(TREE_OPERAND(fnaddr, 0)) == FUNCTION_DECL);
1202   TREE_ADDRESSABLE(TREE_OPERAND(fnaddr, 0)) = 1;
1203
1204   // For a normal non-nested function call, that is all we have to do.
1205   if (!this->function_->is_function()
1206       || this->function_->func_value()->enclosing() == NULL)
1207     {
1208       gcc_assert(this->closure_ == NULL);
1209       return fnaddr;
1210     }
1211
1212   // For a nested function call, we have to always allocate a
1213   // trampoline.  If we don't always allocate, then closures will not
1214   // be reliably distinct.
1215   Expression* closure = this->closure_;
1216   tree closure_tree;
1217   if (closure == NULL)
1218     closure_tree = null_pointer_node;
1219   else
1220     {
1221       // Get the value of the closure.  This will be a pointer to
1222       // space allocated on the heap.
1223       closure_tree = closure->get_tree(context);
1224       if (closure_tree == error_mark_node)
1225         return error_mark_node;
1226       gcc_assert(POINTER_TYPE_P(TREE_TYPE(closure_tree)));
1227     }
1228
1229   // Now we need to build some code on the heap.  This code will load
1230   // the static chain pointer with the closure and then jump to the
1231   // body of the function.  The normal gcc approach is to build the
1232   // code on the stack.  Unfortunately we can not do that, as Go
1233   // permits us to return the function pointer.
1234
1235   return gogo->make_trampoline(fnaddr, closure_tree, this->location());
1236 }
1237
1238 // Make a reference to a function in an expression.
1239
1240 Expression*
1241 Expression::make_func_reference(Named_object* function, Expression* closure,
1242                                 source_location location)
1243 {
1244   return new Func_expression(function, closure, location);
1245 }
1246
1247 // Class Unknown_expression.
1248
1249 // Return the name of an unknown expression.
1250
1251 const std::string&
1252 Unknown_expression::name() const
1253 {
1254   return this->named_object_->name();
1255 }
1256
1257 // Lower a reference to an unknown name.
1258
1259 Expression*
1260 Unknown_expression::do_lower(Gogo*, Named_object*, int)
1261 {
1262   source_location location = this->location();
1263   Named_object* no = this->named_object_;
1264   Named_object* real;
1265   if (!no->is_unknown())
1266     real = no;
1267   else
1268     {
1269       real = no->unknown_value()->real_named_object();
1270       if (real == NULL)
1271         {
1272           if (this->is_composite_literal_key_)
1273             return this;
1274           error_at(location, "reference to undefined name %qs",
1275                    this->named_object_->message_name().c_str());
1276           return Expression::make_error(location);
1277         }
1278     }
1279   switch (real->classification())
1280     {
1281     case Named_object::NAMED_OBJECT_CONST:
1282       return Expression::make_const_reference(real, location);
1283     case Named_object::NAMED_OBJECT_TYPE:
1284       return Expression::make_type(real->type_value(), location);
1285     case Named_object::NAMED_OBJECT_TYPE_DECLARATION:
1286       if (this->is_composite_literal_key_)
1287         return this;
1288       error_at(location, "reference to undefined type %qs",
1289                real->message_name().c_str());
1290       return Expression::make_error(location);
1291     case Named_object::NAMED_OBJECT_VAR:
1292       return Expression::make_var_reference(real, location);
1293     case Named_object::NAMED_OBJECT_FUNC:
1294     case Named_object::NAMED_OBJECT_FUNC_DECLARATION:
1295       return Expression::make_func_reference(real, NULL, location);
1296     case Named_object::NAMED_OBJECT_PACKAGE:
1297       if (this->is_composite_literal_key_)
1298         return this;
1299       error_at(location, "unexpected reference to package");
1300       return Expression::make_error(location);
1301     default:
1302       gcc_unreachable();
1303     }
1304 }
1305
1306 // Make a reference to an unknown name.
1307
1308 Expression*
1309 Expression::make_unknown_reference(Named_object* no, source_location location)
1310 {
1311   gcc_assert(no->resolve()->is_unknown());
1312   return new Unknown_expression(no, location);
1313 }
1314
1315 // A boolean expression.
1316
1317 class Boolean_expression : public Expression
1318 {
1319  public:
1320   Boolean_expression(bool val, source_location location)
1321     : Expression(EXPRESSION_BOOLEAN, location),
1322       val_(val), type_(NULL)
1323   { }
1324
1325   static Expression*
1326   do_import(Import*);
1327
1328  protected:
1329   bool
1330   do_is_constant() const
1331   { return true; }
1332
1333   Type*
1334   do_type();
1335
1336   void
1337   do_determine_type(const Type_context*);
1338
1339   Expression*
1340   do_copy()
1341   { return this; }
1342
1343   tree
1344   do_get_tree(Translate_context*)
1345   { return this->val_ ? boolean_true_node : boolean_false_node; }
1346
1347   void
1348   do_export(Export* exp) const
1349   { exp->write_c_string(this->val_ ? "true" : "false"); }
1350
1351  private:
1352   // The constant.
1353   bool val_;
1354   // The type as determined by context.
1355   Type* type_;
1356 };
1357
1358 // Get the type.
1359
1360 Type*
1361 Boolean_expression::do_type()
1362 {
1363   if (this->type_ == NULL)
1364     this->type_ = Type::make_boolean_type();
1365   return this->type_;
1366 }
1367
1368 // Set the type from the context.
1369
1370 void
1371 Boolean_expression::do_determine_type(const Type_context* context)
1372 {
1373   if (this->type_ != NULL && !this->type_->is_abstract())
1374     ;
1375   else if (context->type != NULL && context->type->is_boolean_type())
1376     this->type_ = context->type;
1377   else if (!context->may_be_abstract)
1378     this->type_ = Type::lookup_bool_type();
1379 }
1380
1381 // Import a boolean constant.
1382
1383 Expression*
1384 Boolean_expression::do_import(Import* imp)
1385 {
1386   if (imp->peek_char() == 't')
1387     {
1388       imp->require_c_string("true");
1389       return Expression::make_boolean(true, imp->location());
1390     }
1391   else
1392     {
1393       imp->require_c_string("false");
1394       return Expression::make_boolean(false, imp->location());
1395     }
1396 }
1397
1398 // Make a boolean expression.
1399
1400 Expression*
1401 Expression::make_boolean(bool val, source_location location)
1402 {
1403   return new Boolean_expression(val, location);
1404 }
1405
1406 // Class String_expression.
1407
1408 // Get the type.
1409
1410 Type*
1411 String_expression::do_type()
1412 {
1413   if (this->type_ == NULL)
1414     this->type_ = Type::make_string_type();
1415   return this->type_;
1416 }
1417
1418 // Set the type from the context.
1419
1420 void
1421 String_expression::do_determine_type(const Type_context* context)
1422 {
1423   if (this->type_ != NULL && !this->type_->is_abstract())
1424     ;
1425   else if (context->type != NULL && context->type->is_string_type())
1426     this->type_ = context->type;
1427   else if (!context->may_be_abstract)
1428     this->type_ = Type::lookup_string_type();
1429 }
1430
1431 // Build a string constant.
1432
1433 tree
1434 String_expression::do_get_tree(Translate_context* context)
1435 {
1436   return context->gogo()->go_string_constant_tree(this->val_);
1437 }
1438
1439 // Export a string expression.
1440
1441 void
1442 String_expression::do_export(Export* exp) const
1443 {
1444   std::string s;
1445   s.reserve(this->val_.length() * 4 + 2);
1446   s += '"';
1447   for (std::string::const_iterator p = this->val_.begin();
1448        p != this->val_.end();
1449        ++p)
1450     {
1451       if (*p == '\\' || *p == '"')
1452         {
1453           s += '\\';
1454           s += *p;
1455         }
1456       else if (*p >= 0x20 && *p < 0x7f)
1457         s += *p;
1458       else if (*p == '\n')
1459         s += "\\n";
1460       else if (*p == '\t')
1461         s += "\\t";
1462       else
1463         {
1464           s += "\\x";
1465           unsigned char c = *p;
1466           unsigned int dig = c >> 4;
1467           s += dig < 10 ? '0' + dig : 'A' + dig - 10;
1468           dig = c & 0xf;
1469           s += dig < 10 ? '0' + dig : 'A' + dig - 10;
1470         }
1471     }
1472   s += '"';
1473   exp->write_string(s);
1474 }
1475
1476 // Import a string expression.
1477
1478 Expression*
1479 String_expression::do_import(Import* imp)
1480 {
1481   imp->require_c_string("\"");
1482   std::string val;
1483   while (true)
1484     {
1485       int c = imp->get_char();
1486       if (c == '"' || c == -1)
1487         break;
1488       if (c != '\\')
1489         val += static_cast<char>(c);
1490       else
1491         {
1492           c = imp->get_char();
1493           if (c == '\\' || c == '"')
1494             val += static_cast<char>(c);
1495           else if (c == 'n')
1496             val += '\n';
1497           else if (c == 't')
1498             val += '\t';
1499           else if (c == 'x')
1500             {
1501               c = imp->get_char();
1502               unsigned int vh = c >= '0' && c <= '9' ? c - '0' : c - 'A' + 10;
1503               c = imp->get_char();
1504               unsigned int vl = c >= '0' && c <= '9' ? c - '0' : c - 'A' + 10;
1505               char v = (vh << 4) | vl;
1506               val += v;
1507             }
1508           else
1509             {
1510               error_at(imp->location(), "bad string constant");
1511               return Expression::make_error(imp->location());
1512             }
1513         }
1514     }
1515   return Expression::make_string(val, imp->location());
1516 }
1517
1518 // Make a string expression.
1519
1520 Expression*
1521 Expression::make_string(const std::string& val, source_location location)
1522 {
1523   return new String_expression(val, location);
1524 }
1525
1526 // Make an integer expression.
1527
1528 class Integer_expression : public Expression
1529 {
1530  public:
1531   Integer_expression(const mpz_t* val, Type* type, source_location location)
1532     : Expression(EXPRESSION_INTEGER, location),
1533       type_(type)
1534   { mpz_init_set(this->val_, *val); }
1535
1536   static Expression*
1537   do_import(Import*);
1538
1539   // Return whether VAL fits in the type.
1540   static bool
1541   check_constant(mpz_t val, Type*, source_location);
1542
1543   // Write VAL to export data.
1544   static void
1545   export_integer(Export* exp, const mpz_t val);
1546
1547  protected:
1548   bool
1549   do_is_constant() const
1550   { return true; }
1551
1552   bool
1553   do_integer_constant_value(bool, mpz_t val, Type** ptype) const;
1554
1555   Type*
1556   do_type();
1557
1558   void
1559   do_determine_type(const Type_context* context);
1560
1561   void
1562   do_check_types(Gogo*);
1563
1564   tree
1565   do_get_tree(Translate_context*);
1566
1567   Expression*
1568   do_copy()
1569   { return Expression::make_integer(&this->val_, this->type_,
1570                                     this->location()); }
1571
1572   void
1573   do_export(Export*) const;
1574
1575  private:
1576   // The integer value.
1577   mpz_t val_;
1578   // The type so far.
1579   Type* type_;
1580 };
1581
1582 // Return an integer constant value.
1583
1584 bool
1585 Integer_expression::do_integer_constant_value(bool, mpz_t val,
1586                                               Type** ptype) const
1587 {
1588   if (this->type_ != NULL)
1589     *ptype = this->type_;
1590   mpz_set(val, this->val_);
1591   return true;
1592 }
1593
1594 // Return the current type.  If we haven't set the type yet, we return
1595 // an abstract integer type.
1596
1597 Type*
1598 Integer_expression::do_type()
1599 {
1600   if (this->type_ == NULL)
1601     this->type_ = Type::make_abstract_integer_type();
1602   return this->type_;
1603 }
1604
1605 // Set the type of the integer value.  Here we may switch from an
1606 // abstract type to a real type.
1607
1608 void
1609 Integer_expression::do_determine_type(const Type_context* context)
1610 {
1611   if (this->type_ != NULL && !this->type_->is_abstract())
1612     ;
1613   else if (context->type != NULL
1614            && (context->type->integer_type() != NULL
1615                || context->type->float_type() != NULL
1616                || context->type->complex_type() != NULL))
1617     this->type_ = context->type;
1618   else if (!context->may_be_abstract)
1619     this->type_ = Type::lookup_integer_type("int");
1620 }
1621
1622 // Return true if the integer VAL fits in the range of the type TYPE.
1623 // Otherwise give an error and return false.  TYPE may be NULL.
1624
1625 bool
1626 Integer_expression::check_constant(mpz_t val, Type* type,
1627                                    source_location location)
1628 {
1629   if (type == NULL)
1630     return true;
1631   Integer_type* itype = type->integer_type();
1632   if (itype == NULL || itype->is_abstract())
1633     return true;
1634
1635   int bits = mpz_sizeinbase(val, 2);
1636
1637   if (itype->is_unsigned())
1638     {
1639       // For an unsigned type we can only accept a nonnegative number,
1640       // and we must be able to represent at least BITS.
1641       if (mpz_sgn(val) >= 0
1642           && bits <= itype->bits())
1643         return true;
1644     }
1645   else
1646     {
1647       // For a signed type we need an extra bit to indicate the sign.
1648       // We have to handle the most negative integer specially.
1649       if (bits + 1 <= itype->bits()
1650           || (bits <= itype->bits()
1651               && mpz_sgn(val) < 0
1652               && (mpz_scan1(val, 0)
1653                   == static_cast<unsigned long>(itype->bits() - 1))
1654               && mpz_scan0(val, itype->bits()) == ULONG_MAX))
1655         return true;
1656     }
1657
1658   error_at(location, "integer constant overflow");
1659   return false;
1660 }
1661
1662 // Check the type of an integer constant.
1663
1664 void
1665 Integer_expression::do_check_types(Gogo*)
1666 {
1667   if (this->type_ == NULL)
1668     return;
1669   if (!Integer_expression::check_constant(this->val_, this->type_,
1670                                           this->location()))
1671     this->set_is_error();
1672 }
1673
1674 // Get a tree for an integer constant.
1675
1676 tree
1677 Integer_expression::do_get_tree(Translate_context* context)
1678 {
1679   Gogo* gogo = context->gogo();
1680   tree type;
1681   if (this->type_ != NULL && !this->type_->is_abstract())
1682     type = this->type_->get_tree(gogo);
1683   else if (this->type_ != NULL && this->type_->float_type() != NULL)
1684     {
1685       // We are converting to an abstract floating point type.
1686       type = Type::lookup_float_type("float64")->get_tree(gogo);
1687     }
1688   else if (this->type_ != NULL && this->type_->complex_type() != NULL)
1689     {
1690       // We are converting to an abstract complex type.
1691       type = Type::lookup_complex_type("complex128")->get_tree(gogo);
1692     }
1693   else
1694     {
1695       // If we still have an abstract type here, then this is being
1696       // used in a constant expression which didn't get reduced for
1697       // some reason.  Use a type which will fit the value.  We use <,
1698       // not <=, because we need an extra bit for the sign bit.
1699       int bits = mpz_sizeinbase(this->val_, 2);
1700       if (bits < INT_TYPE_SIZE)
1701         type = Type::lookup_integer_type("int")->get_tree(gogo);
1702       else if (bits < 64)
1703         type = Type::lookup_integer_type("int64")->get_tree(gogo);
1704       else
1705         type = long_long_integer_type_node;
1706     }
1707   return Expression::integer_constant_tree(this->val_, type);
1708 }
1709
1710 // Write VAL to export data.
1711
1712 void
1713 Integer_expression::export_integer(Export* exp, const mpz_t val)
1714 {
1715   char* s = mpz_get_str(NULL, 10, val);
1716   exp->write_c_string(s);
1717   free(s);
1718 }
1719
1720 // Export an integer in a constant expression.
1721
1722 void
1723 Integer_expression::do_export(Export* exp) const
1724 {
1725   Integer_expression::export_integer(exp, this->val_);
1726   // A trailing space lets us reliably identify the end of the number.
1727   exp->write_c_string(" ");
1728 }
1729
1730 // Import an integer, floating point, or complex value.  This handles
1731 // all these types because they all start with digits.
1732
1733 Expression*
1734 Integer_expression::do_import(Import* imp)
1735 {
1736   std::string num = imp->read_identifier();
1737   imp->require_c_string(" ");
1738   if (!num.empty() && num[num.length() - 1] == 'i')
1739     {
1740       mpfr_t real;
1741       size_t plus_pos = num.find('+', 1);
1742       size_t minus_pos = num.find('-', 1);
1743       size_t pos;
1744       if (plus_pos == std::string::npos)
1745         pos = minus_pos;
1746       else if (minus_pos == std::string::npos)
1747         pos = plus_pos;
1748       else
1749         {
1750           error_at(imp->location(), "bad number in import data: %qs",
1751                    num.c_str());
1752           return Expression::make_error(imp->location());
1753         }
1754       if (pos == std::string::npos)
1755         mpfr_set_ui(real, 0, GMP_RNDN);
1756       else
1757         {
1758           std::string real_str = num.substr(0, pos);
1759           if (mpfr_init_set_str(real, real_str.c_str(), 10, GMP_RNDN) != 0)
1760             {
1761               error_at(imp->location(), "bad number in import data: %qs",
1762                        real_str.c_str());
1763               return Expression::make_error(imp->location());
1764             }
1765         }
1766
1767       std::string imag_str;
1768       if (pos == std::string::npos)
1769         imag_str = num;
1770       else
1771         imag_str = num.substr(pos);
1772       imag_str = imag_str.substr(0, imag_str.size() - 1);
1773       mpfr_t imag;
1774       if (mpfr_init_set_str(imag, imag_str.c_str(), 10, GMP_RNDN) != 0)
1775         {
1776           error_at(imp->location(), "bad number in import data: %qs",
1777                    imag_str.c_str());
1778           return Expression::make_error(imp->location());
1779         }
1780       Expression* ret = Expression::make_complex(&real, &imag, NULL,
1781                                                  imp->location());
1782       mpfr_clear(real);
1783       mpfr_clear(imag);
1784       return ret;
1785     }
1786   else if (num.find('.') == std::string::npos
1787            && num.find('E') == std::string::npos)
1788     {
1789       mpz_t val;
1790       if (mpz_init_set_str(val, num.c_str(), 10) != 0)
1791         {
1792           error_at(imp->location(), "bad number in import data: %qs",
1793                    num.c_str());
1794           return Expression::make_error(imp->location());
1795         }
1796       Expression* ret = Expression::make_integer(&val, NULL, imp->location());
1797       mpz_clear(val);
1798       return ret;
1799     }
1800   else
1801     {
1802       mpfr_t val;
1803       if (mpfr_init_set_str(val, num.c_str(), 10, GMP_RNDN) != 0)
1804         {
1805           error_at(imp->location(), "bad number in import data: %qs",
1806                    num.c_str());
1807           return Expression::make_error(imp->location());
1808         }
1809       Expression* ret = Expression::make_float(&val, NULL, imp->location());
1810       mpfr_clear(val);
1811       return ret;
1812     }
1813 }
1814
1815 // Build a new integer value.
1816
1817 Expression*
1818 Expression::make_integer(const mpz_t* val, Type* type,
1819                          source_location location)
1820 {
1821   return new Integer_expression(val, type, location);
1822 }
1823
1824 // Floats.
1825
1826 class Float_expression : public Expression
1827 {
1828  public:
1829   Float_expression(const mpfr_t* val, Type* type, source_location location)
1830     : Expression(EXPRESSION_FLOAT, location),
1831       type_(type)
1832   {
1833     mpfr_init_set(this->val_, *val, GMP_RNDN);
1834   }
1835
1836   // Constrain VAL to fit into TYPE.
1837   static void
1838   constrain_float(mpfr_t val, Type* type);
1839
1840   // Return whether VAL fits in the type.
1841   static bool
1842   check_constant(mpfr_t val, Type*, source_location);
1843
1844   // Write VAL to export data.
1845   static void
1846   export_float(Export* exp, const mpfr_t val);
1847
1848  protected:
1849   bool
1850   do_is_constant() const
1851   { return true; }
1852
1853   bool
1854   do_float_constant_value(mpfr_t val, Type**) const;
1855
1856   Type*
1857   do_type();
1858
1859   void
1860   do_determine_type(const Type_context*);
1861
1862   void
1863   do_check_types(Gogo*);
1864
1865   Expression*
1866   do_copy()
1867   { return Expression::make_float(&this->val_, this->type_,
1868                                   this->location()); }
1869
1870   tree
1871   do_get_tree(Translate_context*);
1872
1873   void
1874   do_export(Export*) const;
1875
1876  private:
1877   // The floating point value.
1878   mpfr_t val_;
1879   // The type so far.
1880   Type* type_;
1881 };
1882
1883 // Constrain VAL to fit into TYPE.
1884
1885 void
1886 Float_expression::constrain_float(mpfr_t val, Type* type)
1887 {
1888   Float_type* ftype = type->float_type();
1889   if (ftype != NULL && !ftype->is_abstract())
1890     {
1891       tree type_tree = ftype->type_tree();
1892       REAL_VALUE_TYPE rvt;
1893       real_from_mpfr(&rvt, val, type_tree, GMP_RNDN);
1894       real_convert(&rvt, TYPE_MODE(type_tree), &rvt);
1895       mpfr_from_real(val, &rvt, GMP_RNDN);
1896     }
1897 }
1898
1899 // Return a floating point constant value.
1900
1901 bool
1902 Float_expression::do_float_constant_value(mpfr_t val, Type** ptype) const
1903 {
1904   if (this->type_ != NULL)
1905     *ptype = this->type_;
1906   mpfr_set(val, this->val_, GMP_RNDN);
1907   return true;
1908 }
1909
1910 // Return the current type.  If we haven't set the type yet, we return
1911 // an abstract float type.
1912
1913 Type*
1914 Float_expression::do_type()
1915 {
1916   if (this->type_ == NULL)
1917     this->type_ = Type::make_abstract_float_type();
1918   return this->type_;
1919 }
1920
1921 // Set the type of the float value.  Here we may switch from an
1922 // abstract type to a real type.
1923
1924 void
1925 Float_expression::do_determine_type(const Type_context* context)
1926 {
1927   if (this->type_ != NULL && !this->type_->is_abstract())
1928     ;
1929   else if (context->type != NULL
1930            && (context->type->integer_type() != NULL
1931                || context->type->float_type() != NULL
1932                || context->type->complex_type() != NULL))
1933     this->type_ = context->type;
1934   else if (!context->may_be_abstract)
1935     this->type_ = Type::lookup_float_type("float");
1936 }
1937
1938 // Return true if the floating point value VAL fits in the range of
1939 // the type TYPE.  Otherwise give an error and return false.  TYPE may
1940 // be NULL.
1941
1942 bool
1943 Float_expression::check_constant(mpfr_t val, Type* type,
1944                                  source_location location)
1945 {
1946   if (type == NULL)
1947     return true;
1948   Float_type* ftype = type->float_type();
1949   if (ftype == NULL || ftype->is_abstract())
1950     return true;
1951
1952   // A NaN or Infinity always fits in the range of the type.
1953   if (mpfr_nan_p(val) || mpfr_inf_p(val) || mpfr_zero_p(val))
1954     return true;
1955
1956   mp_exp_t exp = mpfr_get_exp(val);
1957   mp_exp_t max_exp;
1958   switch (ftype->bits())
1959     {
1960     case 32:
1961       max_exp = 128;
1962       break;
1963     case 64:
1964       max_exp = 1024;
1965       break;
1966     default:
1967       gcc_unreachable();
1968     }
1969   if (exp > max_exp)
1970     {
1971       error_at(location, "floating point constant overflow");
1972       return false;
1973     }
1974   return true;
1975 }
1976
1977 // Check the type of a float value.
1978
1979 void
1980 Float_expression::do_check_types(Gogo*)
1981 {
1982   if (this->type_ == NULL)
1983     return;
1984
1985   if (!Float_expression::check_constant(this->val_, this->type_,
1986                                         this->location()))
1987     this->set_is_error();
1988
1989   Integer_type* integer_type = this->type_->integer_type();
1990   if (integer_type != NULL)
1991     {
1992       if (!mpfr_integer_p(this->val_))
1993         this->report_error(_("floating point constant truncated to integer"));
1994       else
1995         {
1996           gcc_assert(!integer_type->is_abstract());
1997           mpz_t ival;
1998           mpz_init(ival);
1999           mpfr_get_z(ival, this->val_, GMP_RNDN);
2000           Integer_expression::check_constant(ival, integer_type,
2001                                              this->location());
2002           mpz_clear(ival);
2003         }
2004     }
2005 }
2006
2007 // Get a tree for a float constant.
2008
2009 tree
2010 Float_expression::do_get_tree(Translate_context* context)
2011 {
2012   Gogo* gogo = context->gogo();
2013   tree type;
2014   if (this->type_ != NULL && !this->type_->is_abstract())
2015     type = this->type_->get_tree(gogo);
2016   else if (this->type_ != NULL && this->type_->integer_type() != NULL)
2017     {
2018       // We have an abstract integer type.  We just hope for the best.
2019       type = Type::lookup_integer_type("int")->get_tree(gogo);
2020     }
2021   else
2022     {
2023       // If we still have an abstract type here, then this is being
2024       // used in a constant expression which didn't get reduced.  We
2025       // just use float64 and hope for the best.
2026       type = Type::lookup_float_type("float64")->get_tree(gogo);
2027     }
2028   return Expression::float_constant_tree(this->val_, type);
2029 }
2030
2031 // Write a floating point number to export data.
2032
2033 void
2034 Float_expression::export_float(Export *exp, const mpfr_t val)
2035 {
2036   mp_exp_t exponent;
2037   char* s = mpfr_get_str(NULL, &exponent, 10, 0, val, GMP_RNDN);
2038   if (*s == '-')
2039     exp->write_c_string("-");
2040   exp->write_c_string("0.");
2041   exp->write_c_string(*s == '-' ? s + 1 : s);
2042   mpfr_free_str(s);
2043   char buf[30];
2044   snprintf(buf, sizeof buf, "E%ld", exponent);
2045   exp->write_c_string(buf);
2046 }
2047
2048 // Export a floating point number in a constant expression.
2049
2050 void
2051 Float_expression::do_export(Export* exp) const
2052 {
2053   Float_expression::export_float(exp, this->val_);
2054   // A trailing space lets us reliably identify the end of the number.
2055   exp->write_c_string(" ");
2056 }
2057
2058 // Make a float expression.
2059
2060 Expression*
2061 Expression::make_float(const mpfr_t* val, Type* type, source_location location)
2062 {
2063   return new Float_expression(val, type, location);
2064 }
2065
2066 // Complex numbers.
2067
2068 class Complex_expression : public Expression
2069 {
2070  public:
2071   Complex_expression(const mpfr_t* real, const mpfr_t* imag, Type* type,
2072                      source_location location)
2073     : Expression(EXPRESSION_COMPLEX, location),
2074       type_(type)
2075   {
2076     mpfr_init_set(this->real_, *real, GMP_RNDN);
2077     mpfr_init_set(this->imag_, *imag, GMP_RNDN);
2078   }
2079
2080   // Constrain REAL/IMAG to fit into TYPE.
2081   static void
2082   constrain_complex(mpfr_t real, mpfr_t imag, Type* type);
2083
2084   // Return whether REAL/IMAG fits in the type.
2085   static bool
2086   check_constant(mpfr_t real, mpfr_t imag, Type*, source_location);
2087
2088   // Write REAL/IMAG to export data.
2089   static void
2090   export_complex(Export* exp, const mpfr_t real, const mpfr_t val);
2091
2092  protected:
2093   bool
2094   do_is_constant() const
2095   { return true; }
2096
2097   bool
2098   do_complex_constant_value(mpfr_t real, mpfr_t imag, Type**) const;
2099
2100   Type*
2101   do_type();
2102
2103   void
2104   do_determine_type(const Type_context*);
2105
2106   void
2107   do_check_types(Gogo*);
2108
2109   Expression*
2110   do_copy()
2111   {
2112     return Expression::make_complex(&this->real_, &this->imag_, this->type_,
2113                                     this->location());
2114   }
2115
2116   tree
2117   do_get_tree(Translate_context*);
2118
2119   void
2120   do_export(Export*) const;
2121
2122  private:
2123   // The real part.
2124   mpfr_t real_;
2125   // The imaginary part;
2126   mpfr_t imag_;
2127   // The type if known.
2128   Type* type_;
2129 };
2130
2131 // Constrain REAL/IMAG to fit into TYPE.
2132
2133 void
2134 Complex_expression::constrain_complex(mpfr_t real, mpfr_t imag, Type* type)
2135 {
2136   Complex_type* ctype = type->complex_type();
2137   if (ctype != NULL && !ctype->is_abstract())
2138     {
2139       tree type_tree = ctype->type_tree();
2140
2141       REAL_VALUE_TYPE rvt;
2142       real_from_mpfr(&rvt, real, TREE_TYPE(type_tree), GMP_RNDN);
2143       real_convert(&rvt, TYPE_MODE(TREE_TYPE(type_tree)), &rvt);
2144       mpfr_from_real(real, &rvt, GMP_RNDN);
2145
2146       real_from_mpfr(&rvt, imag, TREE_TYPE(type_tree), GMP_RNDN);
2147       real_convert(&rvt, TYPE_MODE(TREE_TYPE(type_tree)), &rvt);
2148       mpfr_from_real(imag, &rvt, GMP_RNDN);
2149     }
2150 }
2151
2152 // Return a complex constant value.
2153
2154 bool
2155 Complex_expression::do_complex_constant_value(mpfr_t real, mpfr_t imag,
2156                                               Type** ptype) const
2157 {
2158   if (this->type_ != NULL)
2159     *ptype = this->type_;
2160   mpfr_set(real, this->real_, GMP_RNDN);
2161   mpfr_set(imag, this->imag_, GMP_RNDN);
2162   return true;
2163 }
2164
2165 // Return the current type.  If we haven't set the type yet, we return
2166 // an abstract complex type.
2167
2168 Type*
2169 Complex_expression::do_type()
2170 {
2171   if (this->type_ == NULL)
2172     this->type_ = Type::make_abstract_complex_type();
2173   return this->type_;
2174 }
2175
2176 // Set the type of the complex value.  Here we may switch from an
2177 // abstract type to a real type.
2178
2179 void
2180 Complex_expression::do_determine_type(const Type_context* context)
2181 {
2182   if (this->type_ != NULL && !this->type_->is_abstract())
2183     ;
2184   else if (context->type != NULL
2185            && context->type->complex_type() != NULL)
2186     this->type_ = context->type;
2187   else if (!context->may_be_abstract)
2188     this->type_ = Type::lookup_complex_type("complex");
2189 }
2190
2191 // Return true if the complex value REAL/IMAG fits in the range of the
2192 // type TYPE.  Otherwise give an error and return false.  TYPE may be
2193 // NULL.
2194
2195 bool
2196 Complex_expression::check_constant(mpfr_t real, mpfr_t imag, Type* type,
2197                                    source_location location)
2198 {
2199   if (type == NULL)
2200     return true;
2201   Complex_type* ctype = type->complex_type();
2202   if (ctype == NULL || ctype->is_abstract())
2203     return true;
2204
2205   mp_exp_t max_exp;
2206   switch (ctype->bits())
2207     {
2208     case 64:
2209       max_exp = 128;
2210       break;
2211     case 128:
2212       max_exp = 1024;
2213       break;
2214     default:
2215       gcc_unreachable();
2216     }
2217
2218   // A NaN or Infinity always fits in the range of the type.
2219   if (!mpfr_nan_p(real) && !mpfr_inf_p(real) && !mpfr_zero_p(real))
2220     {
2221       if (mpfr_get_exp(real) > max_exp)
2222         {
2223           error_at(location, "complex real part constant overflow");
2224           return false;
2225         }
2226     }
2227
2228   if (!mpfr_nan_p(imag) && !mpfr_inf_p(imag) && !mpfr_zero_p(imag))
2229     {
2230       if (mpfr_get_exp(imag) > max_exp)
2231         {
2232           error_at(location, "complex imaginary part constant overflow");
2233           return false;
2234         }
2235     }
2236
2237   return true;
2238 }
2239
2240 // Check the type of a complex value.
2241
2242 void
2243 Complex_expression::do_check_types(Gogo*)
2244 {
2245   if (this->type_ == NULL)
2246     return;
2247
2248   if (!Complex_expression::check_constant(this->real_, this->imag_,
2249                                           this->type_, this->location()))
2250     this->set_is_error();
2251 }
2252
2253 // Get a tree for a complex constant.
2254
2255 tree
2256 Complex_expression::do_get_tree(Translate_context* context)
2257 {
2258   Gogo* gogo = context->gogo();
2259   tree type;
2260   if (this->type_ != NULL && !this->type_->is_abstract())
2261     type = this->type_->get_tree(gogo);
2262   else
2263     {
2264       // If we still have an abstract type here, this this is being
2265       // used in a constant expression which didn't get reduced.  We
2266       // just use complex128 and hope for the best.
2267       type = Type::lookup_complex_type("complex128")->get_tree(gogo);
2268     }
2269   return Expression::complex_constant_tree(this->real_, this->imag_, type);
2270 }
2271
2272 // Write REAL/IMAG to export data.
2273
2274 void
2275 Complex_expression::export_complex(Export* exp, const mpfr_t real,
2276                                    const mpfr_t imag)
2277 {
2278   if (!mpfr_zero_p(real))
2279     {
2280       Float_expression::export_float(exp, real);
2281       if (mpfr_sgn(imag) > 0)
2282         exp->write_c_string("+");
2283     }
2284   Float_expression::export_float(exp, imag);
2285   exp->write_c_string("i");
2286 }
2287
2288 // Export a complex number in a constant expression.
2289
2290 void
2291 Complex_expression::do_export(Export* exp) const
2292 {
2293   Complex_expression::export_complex(exp, this->real_, this->imag_);
2294   // A trailing space lets us reliably identify the end of the number.
2295   exp->write_c_string(" ");
2296 }
2297
2298 // Make a complex expression.
2299
2300 Expression*
2301 Expression::make_complex(const mpfr_t* real, const mpfr_t* imag, Type* type,
2302                          source_location location)
2303 {
2304   return new Complex_expression(real, imag, type, location);
2305 }
2306
2307 // Find a named object in an expression.
2308
2309 class Find_named_object : public Traverse
2310 {
2311  public:
2312   Find_named_object(Named_object* no)
2313     : Traverse(traverse_expressions),
2314       no_(no), found_(false)
2315   { }
2316
2317   // Whether we found the object.
2318   bool
2319   found() const
2320   { return this->found_; }
2321
2322  protected:
2323   int
2324   expression(Expression**);
2325
2326  private:
2327   // The object we are looking for.
2328   Named_object* no_;
2329   // Whether we found it.
2330   bool found_;
2331 };
2332
2333 // A reference to a const in an expression.
2334
2335 class Const_expression : public Expression
2336 {
2337  public:
2338   Const_expression(Named_object* constant, source_location location)
2339     : Expression(EXPRESSION_CONST_REFERENCE, location),
2340       constant_(constant), type_(NULL), seen_(false)
2341   { }
2342
2343   Named_object*
2344   named_object()
2345   { return this->constant_; }
2346
2347   const std::string&
2348   name() const
2349   { return this->constant_->name(); }
2350
2351   // Check that the initializer does not refer to the constant itself.
2352   void
2353   check_for_init_loop();
2354
2355  protected:
2356   Expression*
2357   do_lower(Gogo*, Named_object*, int);
2358
2359   bool
2360   do_is_constant() const
2361   { return true; }
2362
2363   bool
2364   do_integer_constant_value(bool, mpz_t val, Type**) const;
2365
2366   bool
2367   do_float_constant_value(mpfr_t val, Type**) const;
2368
2369   bool
2370   do_complex_constant_value(mpfr_t real, mpfr_t imag, Type**) const;
2371
2372   bool
2373   do_string_constant_value(std::string* val) const
2374   { return this->constant_->const_value()->expr()->string_constant_value(val); }
2375
2376   Type*
2377   do_type();
2378
2379   // The type of a const is set by the declaration, not the use.
2380   void
2381   do_determine_type(const Type_context*);
2382
2383   void
2384   do_check_types(Gogo*);
2385
2386   Expression*
2387   do_copy()
2388   { return this; }
2389
2390   tree
2391   do_get_tree(Translate_context* context);
2392
2393   // When exporting a reference to a const as part of a const
2394   // expression, we export the value.  We ignore the fact that it has
2395   // a name.
2396   void
2397   do_export(Export* exp) const
2398   { this->constant_->const_value()->expr()->export_expression(exp); }
2399
2400  private:
2401   // The constant.
2402   Named_object* constant_;
2403   // The type of this reference.  This is used if the constant has an
2404   // abstract type.
2405   Type* type_;
2406   // Used to prevent infinite recursion when a constant incorrectly
2407   // refers to itself.
2408   mutable bool seen_;
2409 };
2410
2411 // Lower a constant expression.  This is where we convert the
2412 // predeclared constant iota into an integer value.
2413
2414 Expression*
2415 Const_expression::do_lower(Gogo* gogo, Named_object*, int iota_value)
2416 {
2417   if (this->constant_->const_value()->expr()->classification()
2418       == EXPRESSION_IOTA)
2419     {
2420       if (iota_value == -1)
2421         {
2422           error_at(this->location(),
2423                    "iota is only defined in const declarations");
2424           iota_value = 0;
2425         }
2426       mpz_t val;
2427       mpz_init_set_ui(val, static_cast<unsigned long>(iota_value));
2428       Expression* ret = Expression::make_integer(&val, NULL,
2429                                                  this->location());
2430       mpz_clear(val);
2431       return ret;
2432     }
2433
2434   // Make sure that the constant itself has been lowered.
2435   gogo->lower_constant(this->constant_);
2436
2437   return this;
2438 }
2439
2440 // Return an integer constant value.
2441
2442 bool
2443 Const_expression::do_integer_constant_value(bool iota_is_constant, mpz_t val,
2444                                             Type** ptype) const
2445 {
2446   if (this->seen_)
2447     return false;
2448
2449   Type* ctype;
2450   if (this->type_ != NULL)
2451     ctype = this->type_;
2452   else
2453     ctype = this->constant_->const_value()->type();
2454   if (ctype != NULL && ctype->integer_type() == NULL)
2455     return false;
2456
2457   Expression* e = this->constant_->const_value()->expr();
2458
2459   this->seen_ = true;
2460
2461   Type* t;
2462   bool r = e->integer_constant_value(iota_is_constant, val, &t);
2463
2464   this->seen_ = false;
2465
2466   if (r
2467       && ctype != NULL
2468       && !Integer_expression::check_constant(val, ctype, this->location()))
2469     return false;
2470
2471   *ptype = ctype != NULL ? ctype : t;
2472   return r;
2473 }
2474
2475 // Return a floating point constant value.
2476
2477 bool
2478 Const_expression::do_float_constant_value(mpfr_t val, Type** ptype) const
2479 {
2480   if (this->seen_)
2481     return false;
2482
2483   Type* ctype;
2484   if (this->type_ != NULL)
2485     ctype = this->type_;
2486   else
2487     ctype = this->constant_->const_value()->type();
2488   if (ctype != NULL && ctype->float_type() == NULL)
2489     return false;
2490
2491   this->seen_ = true;
2492
2493   Type* t;
2494   bool r = this->constant_->const_value()->expr()->float_constant_value(val,
2495                                                                         &t);
2496
2497   this->seen_ = false;
2498
2499   if (r && ctype != NULL)
2500     {
2501       if (!Float_expression::check_constant(val, ctype, this->location()))
2502         return false;
2503       Float_expression::constrain_float(val, ctype);
2504     }
2505   *ptype = ctype != NULL ? ctype : t;
2506   return r;
2507 }
2508
2509 // Return a complex constant value.
2510
2511 bool
2512 Const_expression::do_complex_constant_value(mpfr_t real, mpfr_t imag,
2513                                             Type **ptype) const
2514 {
2515   if (this->seen_)
2516     return false;
2517
2518   Type* ctype;
2519   if (this->type_ != NULL)
2520     ctype = this->type_;
2521   else
2522     ctype = this->constant_->const_value()->type();
2523   if (ctype != NULL && ctype->complex_type() == NULL)
2524     return false;
2525
2526   this->seen_ = true;
2527
2528   Type *t;
2529   bool r = this->constant_->const_value()->expr()->complex_constant_value(real,
2530                                                                           imag,
2531                                                                           &t);
2532
2533   this->seen_ = false;
2534
2535   if (r && ctype != NULL)
2536     {
2537       if (!Complex_expression::check_constant(real, imag, ctype,
2538                                               this->location()))
2539         return false;
2540       Complex_expression::constrain_complex(real, imag, ctype);
2541     }
2542   *ptype = ctype != NULL ? ctype : t;
2543   return r;
2544 }
2545
2546 // Return the type of the const reference.
2547
2548 Type*
2549 Const_expression::do_type()
2550 {
2551   if (this->type_ != NULL)
2552     return this->type_;
2553
2554   Named_constant* nc = this->constant_->const_value();
2555
2556   if (this->seen_ || nc->lowering())
2557     {
2558       this->report_error(_("constant refers to itself"));
2559       this->type_ = Type::make_error_type();
2560       return this->type_;
2561     }
2562
2563   this->seen_ = true;
2564
2565   Type* ret = nc->type();
2566
2567   if (ret != NULL)
2568     {
2569       this->seen_ = false;
2570       return ret;
2571     }
2572
2573   // During parsing, a named constant may have a NULL type, but we
2574   // must not return a NULL type here.
2575   ret = nc->expr()->type();
2576
2577   this->seen_ = false;
2578
2579   return ret;
2580 }
2581
2582 // Set the type of the const reference.
2583
2584 void
2585 Const_expression::do_determine_type(const Type_context* context)
2586 {
2587   Type* ctype = this->constant_->const_value()->type();
2588   Type* cetype = (ctype != NULL
2589                   ? ctype
2590                   : this->constant_->const_value()->expr()->type());
2591   if (ctype != NULL && !ctype->is_abstract())
2592     ;
2593   else if (context->type != NULL
2594            && (context->type->integer_type() != NULL
2595                || context->type->float_type() != NULL
2596                || context->type->complex_type() != NULL)
2597            && (cetype->integer_type() != NULL
2598                || cetype->float_type() != NULL
2599                || cetype->complex_type() != NULL))
2600     this->type_ = context->type;
2601   else if (context->type != NULL
2602            && context->type->is_string_type()
2603            && cetype->is_string_type())
2604     this->type_ = context->type;
2605   else if (context->type != NULL
2606            && context->type->is_boolean_type()
2607            && cetype->is_boolean_type())
2608     this->type_ = context->type;
2609   else if (!context->may_be_abstract)
2610     {
2611       if (cetype->is_abstract())
2612         cetype = cetype->make_non_abstract_type();
2613       this->type_ = cetype;
2614     }
2615 }
2616
2617 // Check for a loop in which the initializer of a constant refers to
2618 // the constant itself.
2619
2620 void
2621 Const_expression::check_for_init_loop()
2622 {
2623   if (this->type_ != NULL && this->type_->is_error_type())
2624     return;
2625
2626   if (this->seen_)
2627     {
2628       this->report_error(_("constant refers to itself"));
2629       this->type_ = Type::make_error_type();
2630       return;
2631     }
2632
2633   Expression* init = this->constant_->const_value()->expr();
2634   Find_named_object find_named_object(this->constant_);
2635
2636   this->seen_ = true;
2637   Expression::traverse(&init, &find_named_object);
2638   this->seen_ = false;
2639
2640   if (find_named_object.found())
2641     {
2642       if (this->type_ == NULL || !this->type_->is_error_type())
2643         {
2644           this->report_error(_("constant refers to itself"));
2645           this->type_ = Type::make_error_type();
2646         }
2647       return;
2648     }
2649 }
2650
2651 // Check types of a const reference.
2652
2653 void
2654 Const_expression::do_check_types(Gogo*)
2655 {
2656   if (this->type_ != NULL && this->type_->is_error_type())
2657     return;
2658
2659   this->check_for_init_loop();
2660
2661   if (this->type_ == NULL || this->type_->is_abstract())
2662     return;
2663
2664   // Check for integer overflow.
2665   if (this->type_->integer_type() != NULL)
2666     {
2667       mpz_t ival;
2668       mpz_init(ival);
2669       Type* dummy;
2670       if (!this->integer_constant_value(true, ival, &dummy))
2671         {
2672           mpfr_t fval;
2673           mpfr_init(fval);
2674           Expression* cexpr = this->constant_->const_value()->expr();
2675           if (cexpr->float_constant_value(fval, &dummy))
2676             {
2677               if (!mpfr_integer_p(fval))
2678                 this->report_error(_("floating point constant "
2679                                      "truncated to integer"));
2680               else
2681                 {
2682                   mpfr_get_z(ival, fval, GMP_RNDN);
2683                   Integer_expression::check_constant(ival, this->type_,
2684                                                      this->location());
2685                 }
2686             }
2687           mpfr_clear(fval);
2688         }
2689       mpz_clear(ival);
2690     }
2691 }
2692
2693 // Return a tree for the const reference.
2694
2695 tree
2696 Const_expression::do_get_tree(Translate_context* context)
2697 {
2698   Gogo* gogo = context->gogo();
2699   tree type_tree;
2700   if (this->type_ == NULL)
2701     type_tree = NULL_TREE;
2702   else
2703     {
2704       type_tree = this->type_->get_tree(gogo);
2705       if (type_tree == error_mark_node)
2706         return error_mark_node;
2707     }
2708
2709   // If the type has been set for this expression, but the underlying
2710   // object is an abstract int or float, we try to get the abstract
2711   // value.  Otherwise we may lose something in the conversion.
2712   if (this->type_ != NULL
2713       && (this->constant_->const_value()->type() == NULL
2714           || this->constant_->const_value()->type()->is_abstract()))
2715     {
2716       Expression* expr = this->constant_->const_value()->expr();
2717       mpz_t ival;
2718       mpz_init(ival);
2719       Type* t;
2720       if (expr->integer_constant_value(true, ival, &t))
2721         {
2722           tree ret = Expression::integer_constant_tree(ival, type_tree);
2723           mpz_clear(ival);
2724           return ret;
2725         }
2726       mpz_clear(ival);
2727
2728       mpfr_t fval;
2729       mpfr_init(fval);
2730       if (expr->float_constant_value(fval, &t))
2731         {
2732           tree ret = Expression::float_constant_tree(fval, type_tree);
2733           mpfr_clear(fval);
2734           return ret;
2735         }
2736
2737       mpfr_t imag;
2738       mpfr_init(imag);
2739       if (expr->complex_constant_value(fval, imag, &t))
2740         {
2741           tree ret = Expression::complex_constant_tree(fval, imag, type_tree);
2742           mpfr_clear(fval);
2743           mpfr_clear(imag);
2744           return ret;
2745         }
2746       mpfr_clear(imag);
2747       mpfr_clear(fval);
2748     }
2749
2750   tree const_tree = this->constant_->get_tree(gogo, context->function());
2751   if (this->type_ == NULL
2752       || const_tree == error_mark_node
2753       || TREE_TYPE(const_tree) == error_mark_node)
2754     return const_tree;
2755
2756   tree ret;
2757   if (TYPE_MAIN_VARIANT(type_tree) == TYPE_MAIN_VARIANT(TREE_TYPE(const_tree)))
2758     ret = fold_convert(type_tree, const_tree);
2759   else if (TREE_CODE(type_tree) == INTEGER_TYPE)
2760     ret = fold(convert_to_integer(type_tree, const_tree));
2761   else if (TREE_CODE(type_tree) == REAL_TYPE)
2762     ret = fold(convert_to_real(type_tree, const_tree));
2763   else if (TREE_CODE(type_tree) == COMPLEX_TYPE)
2764     ret = fold(convert_to_complex(type_tree, const_tree));
2765   else
2766     gcc_unreachable();
2767   return ret;
2768 }
2769
2770 // Make a reference to a constant in an expression.
2771
2772 Expression*
2773 Expression::make_const_reference(Named_object* constant,
2774                                  source_location location)
2775 {
2776   return new Const_expression(constant, location);
2777 }
2778
2779 // Find a named object in an expression.
2780
2781 int
2782 Find_named_object::expression(Expression** pexpr)
2783 {
2784   switch ((*pexpr)->classification())
2785     {
2786     case Expression::EXPRESSION_CONST_REFERENCE:
2787       {
2788         Const_expression* ce = static_cast<Const_expression*>(*pexpr);
2789         if (ce->named_object() == this->no_)
2790           break;
2791
2792         // We need to check a constant initializer explicitly, as
2793         // loops here will not be caught by the loop checking for
2794         // variable initializers.
2795         ce->check_for_init_loop();
2796
2797         return TRAVERSE_CONTINUE;
2798       }
2799
2800     case Expression::EXPRESSION_VAR_REFERENCE:
2801       if ((*pexpr)->var_expression()->named_object() == this->no_)
2802         break;
2803       return TRAVERSE_CONTINUE;
2804     case Expression::EXPRESSION_FUNC_REFERENCE:
2805       if ((*pexpr)->func_expression()->named_object() == this->no_)
2806         break;
2807       return TRAVERSE_CONTINUE;
2808     default:
2809       return TRAVERSE_CONTINUE;
2810     }
2811   this->found_ = true;
2812   return TRAVERSE_EXIT;
2813 }
2814
2815 // The nil value.
2816
2817 class Nil_expression : public Expression
2818 {
2819  public:
2820   Nil_expression(source_location location)
2821     : Expression(EXPRESSION_NIL, location)
2822   { }
2823
2824   static Expression*
2825   do_import(Import*);
2826
2827  protected:
2828   bool
2829   do_is_constant() const
2830   { return true; }
2831
2832   Type*
2833   do_type()
2834   { return Type::make_nil_type(); }
2835
2836   void
2837   do_determine_type(const Type_context*)
2838   { }
2839
2840   Expression*
2841   do_copy()
2842   { return this; }
2843
2844   tree
2845   do_get_tree(Translate_context*)
2846   { return null_pointer_node; }
2847
2848   void
2849   do_export(Export* exp) const
2850   { exp->write_c_string("nil"); }
2851 };
2852
2853 // Import a nil expression.
2854
2855 Expression*
2856 Nil_expression::do_import(Import* imp)
2857 {
2858   imp->require_c_string("nil");
2859   return Expression::make_nil(imp->location());
2860 }
2861
2862 // Make a nil expression.
2863
2864 Expression*
2865 Expression::make_nil(source_location location)
2866 {
2867   return new Nil_expression(location);
2868 }
2869
2870 // The value of the predeclared constant iota.  This is little more
2871 // than a marker.  This will be lowered to an integer in
2872 // Const_expression::do_lower, which is where we know the value that
2873 // it should have.
2874
2875 class Iota_expression : public Parser_expression
2876 {
2877  public:
2878   Iota_expression(source_location location)
2879     : Parser_expression(EXPRESSION_IOTA, location)
2880   { }
2881
2882  protected:
2883   Expression*
2884   do_lower(Gogo*, Named_object*, int)
2885   { gcc_unreachable(); }
2886
2887   // There should only ever be one of these.
2888   Expression*
2889   do_copy()
2890   { gcc_unreachable(); }
2891 };
2892
2893 // Make an iota expression.  This is only called for one case: the
2894 // value of the predeclared constant iota.
2895
2896 Expression*
2897 Expression::make_iota()
2898 {
2899   static Iota_expression iota_expression(UNKNOWN_LOCATION);
2900   return &iota_expression;
2901 }
2902
2903 // A type conversion expression.
2904
2905 class Type_conversion_expression : public Expression
2906 {
2907  public:
2908   Type_conversion_expression(Type* type, Expression* expr,
2909                              source_location location)
2910     : Expression(EXPRESSION_CONVERSION, location),
2911       type_(type), expr_(expr), may_convert_function_types_(false)
2912   { }
2913
2914   // Return the type to which we are converting.
2915   Type*
2916   type() const
2917   { return this->type_; }
2918
2919   // Return the expression which we are converting.
2920   Expression*
2921   expr() const
2922   { return this->expr_; }
2923
2924   // Permit converting from one function type to another.  This is
2925   // used internally for method expressions.
2926   void
2927   set_may_convert_function_types()
2928   {
2929     this->may_convert_function_types_ = true;
2930   }
2931
2932   // Import a type conversion expression.
2933   static Expression*
2934   do_import(Import*);
2935
2936  protected:
2937   int
2938   do_traverse(Traverse* traverse);
2939
2940   Expression*
2941   do_lower(Gogo*, Named_object*, int);
2942
2943   bool
2944   do_is_constant() const
2945   { return this->expr_->is_constant(); }
2946
2947   bool
2948   do_integer_constant_value(bool, mpz_t, Type**) const;
2949
2950   bool
2951   do_float_constant_value(mpfr_t, Type**) const;
2952
2953   bool
2954   do_complex_constant_value(mpfr_t, mpfr_t, Type**) const;
2955
2956   bool
2957   do_string_constant_value(std::string*) const;
2958
2959   Type*
2960   do_type()
2961   { return this->type_; }
2962
2963   void
2964   do_determine_type(const Type_context*)
2965   {
2966     Type_context subcontext(this->type_, false);
2967     this->expr_->determine_type(&subcontext);
2968   }
2969
2970   void
2971   do_check_types(Gogo*);
2972
2973   Expression*
2974   do_copy()
2975   {
2976     return new Type_conversion_expression(this->type_, this->expr_->copy(),
2977                                           this->location());
2978   }
2979
2980   tree
2981   do_get_tree(Translate_context* context);
2982
2983   void
2984   do_export(Export*) const;
2985
2986  private:
2987   // The type to convert to.
2988   Type* type_;
2989   // The expression to convert.
2990   Expression* expr_;
2991   // True if this is permitted to convert function types.  This is
2992   // used internally for method expressions.
2993   bool may_convert_function_types_;
2994 };
2995
2996 // Traversal.
2997
2998 int
2999 Type_conversion_expression::do_traverse(Traverse* traverse)
3000 {
3001   if (Expression::traverse(&this->expr_, traverse) == TRAVERSE_EXIT
3002       || Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
3003     return TRAVERSE_EXIT;
3004   return TRAVERSE_CONTINUE;
3005 }
3006
3007 // Convert to a constant at lowering time.
3008
3009 Expression*
3010 Type_conversion_expression::do_lower(Gogo*, Named_object*, int)
3011 {
3012   Type* type = this->type_;
3013   Expression* val = this->expr_;
3014   source_location location = this->location();
3015
3016   if (type->integer_type() != NULL)
3017     {
3018       mpz_t ival;
3019       mpz_init(ival);
3020       Type* dummy;
3021       if (val->integer_constant_value(false, ival, &dummy))
3022         {
3023           if (!Integer_expression::check_constant(ival, type, location))
3024             mpz_set_ui(ival, 0);
3025           Expression* ret = Expression::make_integer(&ival, type, location);
3026           mpz_clear(ival);
3027           return ret;
3028         }
3029
3030       mpfr_t fval;
3031       mpfr_init(fval);
3032       if (val->float_constant_value(fval, &dummy))
3033         {
3034           if (!mpfr_integer_p(fval))
3035             {
3036               error_at(location,
3037                        "floating point constant truncated to integer");
3038               return Expression::make_error(location);
3039             }
3040           mpfr_get_z(ival, fval, GMP_RNDN);
3041           if (!Integer_expression::check_constant(ival, type, location))
3042             mpz_set_ui(ival, 0);
3043           Expression* ret = Expression::make_integer(&ival, type, location);
3044           mpfr_clear(fval);
3045           mpz_clear(ival);
3046           return ret;
3047         }
3048       mpfr_clear(fval);
3049       mpz_clear(ival);
3050     }
3051
3052   if (type->float_type() != NULL)
3053     {
3054       mpfr_t fval;
3055       mpfr_init(fval);
3056       Type* dummy;
3057       if (val->float_constant_value(fval, &dummy))
3058         {
3059           if (!Float_expression::check_constant(fval, type, location))
3060             mpfr_set_ui(fval, 0, GMP_RNDN);
3061           Float_expression::constrain_float(fval, type);
3062           Expression *ret = Expression::make_float(&fval, type, location);
3063           mpfr_clear(fval);
3064           return ret;
3065         }
3066       mpfr_clear(fval);
3067     }
3068
3069   if (type->complex_type() != NULL)
3070     {
3071       mpfr_t real;
3072       mpfr_t imag;
3073       mpfr_init(real);
3074       mpfr_init(imag);
3075       Type* dummy;
3076       if (val->complex_constant_value(real, imag, &dummy))
3077         {
3078           if (!Complex_expression::check_constant(real, imag, type, location))
3079             {
3080               mpfr_set_ui(real, 0, GMP_RNDN);
3081               mpfr_set_ui(imag, 0, GMP_RNDN);
3082             }
3083           Complex_expression::constrain_complex(real, imag, type);
3084           Expression* ret = Expression::make_complex(&real, &imag, type,
3085                                                      location);
3086           mpfr_clear(real);
3087           mpfr_clear(imag);
3088           return ret;
3089         }
3090       mpfr_clear(real);
3091       mpfr_clear(imag);
3092     }
3093
3094   if (type->is_open_array_type() && type->named_type() == NULL)
3095     {
3096       Type* element_type = type->array_type()->element_type()->forwarded();
3097       bool is_byte = element_type == Type::lookup_integer_type("uint8");
3098       bool is_int = element_type == Type::lookup_integer_type("int");
3099       if (is_byte || is_int)
3100         {
3101           std::string s;
3102           if (val->string_constant_value(&s))
3103             {
3104               Expression_list* vals = new Expression_list();
3105               if (is_byte)
3106                 {
3107                   for (std::string::const_iterator p = s.begin();
3108                        p != s.end();
3109                        p++)
3110                     {
3111                       mpz_t val;
3112                       mpz_init_set_ui(val, static_cast<unsigned char>(*p));
3113                       Expression* v = Expression::make_integer(&val,
3114                                                                element_type,
3115                                                                location);
3116                       vals->push_back(v);
3117                       mpz_clear(val);
3118                     }
3119                 }
3120               else
3121                 {
3122                   const char *p = s.data();
3123                   const char *pend = s.data() + s.length();
3124                   while (p < pend)
3125                     {
3126                       unsigned int c;
3127                       int adv = Lex::fetch_char(p, &c);
3128                       if (adv == 0)
3129                         {
3130                           warning_at(this->location(), 0,
3131                                      "invalid UTF-8 encoding");
3132                           adv = 1;
3133                         }
3134                       p += adv;
3135                       mpz_t val;
3136                       mpz_init_set_ui(val, c);
3137                       Expression* v = Expression::make_integer(&val,
3138                                                                element_type,
3139                                                                location);
3140                       vals->push_back(v);
3141                       mpz_clear(val);
3142                     }
3143                 }
3144
3145               return Expression::make_slice_composite_literal(type, vals,
3146                                                               location);
3147             }
3148         }
3149     }
3150
3151   return this;
3152 }
3153
3154 // Return the constant integer value if there is one.
3155
3156 bool
3157 Type_conversion_expression::do_integer_constant_value(bool iota_is_constant,
3158                                                       mpz_t val,
3159                                                       Type** ptype) const
3160 {
3161   if (this->type_->integer_type() == NULL)
3162     return false;
3163
3164   mpz_t ival;
3165   mpz_init(ival);
3166   Type* dummy;
3167   if (this->expr_->integer_constant_value(iota_is_constant, ival, &dummy))
3168     {
3169       if (!Integer_expression::check_constant(ival, this->type_,
3170                                               this->location()))
3171         {
3172           mpz_clear(ival);
3173           return false;
3174         }
3175       mpz_set(val, ival);
3176       mpz_clear(ival);
3177       *ptype = this->type_;
3178       return true;
3179     }
3180   mpz_clear(ival);
3181
3182   mpfr_t fval;
3183   mpfr_init(fval);
3184   if (this->expr_->float_constant_value(fval, &dummy))
3185     {
3186       mpfr_get_z(val, fval, GMP_RNDN);
3187       mpfr_clear(fval);
3188       if (!Integer_expression::check_constant(val, this->type_,
3189                                               this->location()))
3190         return false;
3191       *ptype = this->type_;
3192       return true;
3193     }
3194   mpfr_clear(fval);
3195
3196   return false;
3197 }
3198
3199 // Return the constant floating point value if there is one.
3200
3201 bool
3202 Type_conversion_expression::do_float_constant_value(mpfr_t val,
3203                                                     Type** ptype) const
3204 {
3205   if (this->type_->float_type() == NULL)
3206     return false;
3207
3208   mpfr_t fval;
3209   mpfr_init(fval);
3210   Type* dummy;
3211   if (this->expr_->float_constant_value(fval, &dummy))
3212     {
3213       if (!Float_expression::check_constant(fval, this->type_,
3214                                             this->location()))
3215         {
3216           mpfr_clear(fval);
3217           return false;
3218         }
3219       mpfr_set(val, fval, GMP_RNDN);
3220       mpfr_clear(fval);
3221       Float_expression::constrain_float(val, this->type_);
3222       *ptype = this->type_;
3223       return true;
3224     }
3225   mpfr_clear(fval);
3226
3227   return false;
3228 }
3229
3230 // Return the constant complex value if there is one.
3231
3232 bool
3233 Type_conversion_expression::do_complex_constant_value(mpfr_t real,
3234                                                       mpfr_t imag,
3235                                                       Type **ptype) const
3236 {
3237   if (this->type_->complex_type() == NULL)
3238     return false;
3239
3240   mpfr_t rval;
3241   mpfr_t ival;
3242   mpfr_init(rval);
3243   mpfr_init(ival);
3244   Type* dummy;
3245   if (this->expr_->complex_constant_value(rval, ival, &dummy))
3246     {
3247       if (!Complex_expression::check_constant(rval, ival, this->type_,
3248                                               this->location()))
3249         {
3250           mpfr_clear(rval);
3251           mpfr_clear(ival);
3252           return false;
3253         }
3254       mpfr_set(real, rval, GMP_RNDN);
3255       mpfr_set(imag, ival, GMP_RNDN);
3256       mpfr_clear(rval);
3257       mpfr_clear(ival);
3258       Complex_expression::constrain_complex(real, imag, this->type_);
3259       *ptype = this->type_;
3260       return true;
3261     }
3262   mpfr_clear(rval);
3263   mpfr_clear(ival);
3264
3265   return false;
3266 }
3267
3268 // Return the constant string value if there is one.
3269
3270 bool
3271 Type_conversion_expression::do_string_constant_value(std::string* val) const
3272 {
3273   if (this->type_->is_string_type()
3274       && this->expr_->type()->integer_type() != NULL)
3275     {
3276       mpz_t ival;
3277       mpz_init(ival);
3278       Type* dummy;
3279       if (this->expr_->integer_constant_value(false, ival, &dummy))
3280         {
3281           unsigned long ulval = mpz_get_ui(ival);
3282           if (mpz_cmp_ui(ival, ulval) == 0)
3283             {
3284               Lex::append_char(ulval, true, val, this->location());
3285               mpz_clear(ival);
3286               return true;
3287             }
3288         }
3289       mpz_clear(ival);
3290     }
3291
3292   // FIXME: Could handle conversion from const []int here.
3293
3294   return false;
3295 }
3296
3297 // Check that types are convertible.
3298
3299 void
3300 Type_conversion_expression::do_check_types(Gogo*)
3301 {
3302   Type* type = this->type_;
3303   Type* expr_type = this->expr_->type();
3304   std::string reason;
3305
3306   if (type->is_error_type()
3307       || type->is_undefined()
3308       || expr_type->is_error_type()
3309       || expr_type->is_undefined())
3310     {
3311       // Make sure we emit an error for an undefined type.
3312       type->base();
3313       expr_type->base();
3314       this->set_is_error();
3315       return;
3316     }
3317
3318   if (this->may_convert_function_types_
3319       && type->function_type() != NULL
3320       && expr_type->function_type() != NULL)
3321     return;
3322
3323   if (Type::are_convertible(type, expr_type, &reason))
3324     return;
3325
3326   error_at(this->location(), "%s", reason.c_str());
3327   this->set_is_error();
3328 }
3329
3330 // Get a tree for a type conversion.
3331
3332 tree
3333 Type_conversion_expression::do_get_tree(Translate_context* context)
3334 {
3335   Gogo* gogo = context->gogo();
3336   tree type_tree = this->type_->get_tree(gogo);
3337   tree expr_tree = this->expr_->get_tree(context);
3338
3339   if (type_tree == error_mark_node
3340       || expr_tree == error_mark_node
3341       || TREE_TYPE(expr_tree) == error_mark_node)
3342     return error_mark_node;
3343
3344   if (TYPE_MAIN_VARIANT(type_tree) == TYPE_MAIN_VARIANT(TREE_TYPE(expr_tree)))
3345     return fold_convert(type_tree, expr_tree);
3346
3347   Type* type = this->type_;
3348   Type* expr_type = this->expr_->type();
3349   tree ret;
3350   if (type->interface_type() != NULL || expr_type->interface_type() != NULL)
3351     ret = Expression::convert_for_assignment(context, type, expr_type,
3352                                              expr_tree, this->location());
3353   else if (type->integer_type() != NULL)
3354     {
3355       if (expr_type->integer_type() != NULL
3356           || expr_type->float_type() != NULL
3357           || expr_type->is_unsafe_pointer_type())
3358         ret = fold(convert_to_integer(type_tree, expr_tree));
3359       else
3360         gcc_unreachable();
3361     }
3362   else if (type->float_type() != NULL)
3363     {
3364       if (expr_type->integer_type() != NULL
3365           || expr_type->float_type() != NULL)
3366         ret = fold(convert_to_real(type_tree, expr_tree));
3367       else
3368         gcc_unreachable();
3369     }
3370   else if (type->complex_type() != NULL)
3371     {
3372       if (expr_type->complex_type() != NULL)
3373         ret = fold(convert_to_complex(type_tree, expr_tree));
3374       else
3375         gcc_unreachable();
3376     }
3377   else if (type->is_string_type()
3378            && expr_type->integer_type() != NULL)
3379     {
3380       expr_tree = fold_convert(integer_type_node, expr_tree);
3381       if (host_integerp(expr_tree, 0))
3382         {
3383           HOST_WIDE_INT intval = tree_low_cst(expr_tree, 0);
3384           std::string s;
3385           Lex::append_char(intval, true, &s, this->location());
3386           Expression* se = Expression::make_string(s, this->location());
3387           return se->get_tree(context);
3388         }
3389
3390       static tree int_to_string_fndecl;
3391       ret = Gogo::call_builtin(&int_to_string_fndecl,
3392                                this->location(),
3393                                "__go_int_to_string",
3394                                1,
3395                                type_tree,
3396                                integer_type_node,
3397                                fold_convert(integer_type_node, expr_tree));
3398     }
3399   else if (type->is_string_type()
3400            && (expr_type->array_type() != NULL
3401                || (expr_type->points_to() != NULL
3402                    && expr_type->points_to()->array_type() != NULL)))
3403     {
3404       Type* t = expr_type;
3405       if (t->points_to() != NULL)
3406         {
3407           t = t->points_to();
3408           expr_tree = build_fold_indirect_ref(expr_tree);
3409         }
3410       if (!DECL_P(expr_tree))
3411         expr_tree = save_expr(expr_tree);
3412       Array_type* a = t->array_type();
3413       Type* e = a->element_type()->forwarded();
3414       gcc_assert(e->integer_type() != NULL);
3415       tree valptr = fold_convert(const_ptr_type_node,
3416                                  a->value_pointer_tree(gogo, expr_tree));
3417       tree len = a->length_tree(gogo, expr_tree);
3418       len = fold_convert_loc(this->location(), size_type_node, len);
3419       if (e->integer_type()->is_unsigned()
3420           && e->integer_type()->bits() == 8)
3421         {
3422           static tree byte_array_to_string_fndecl;
3423           ret = Gogo::call_builtin(&byte_array_to_string_fndecl,
3424                                    this->location(),
3425                                    "__go_byte_array_to_string",
3426                                    2,
3427                                    type_tree,
3428                                    const_ptr_type_node,
3429                                    valptr,
3430                                    size_type_node,
3431                                    len);
3432         }
3433       else
3434         {
3435           gcc_assert(e == Type::lookup_integer_type("int"));
3436           static tree int_array_to_string_fndecl;
3437           ret = Gogo::call_builtin(&int_array_to_string_fndecl,
3438                                    this->location(),
3439                                    "__go_int_array_to_string",
3440                                    2,
3441                                    type_tree,
3442                                    const_ptr_type_node,
3443                                    valptr,
3444                                    size_type_node,
3445                                    len);
3446         }
3447     }
3448   else if (type->is_open_array_type() && expr_type->is_string_type())
3449     {
3450       Type* e = type->array_type()->element_type()->forwarded();
3451       gcc_assert(e->integer_type() != NULL);
3452       if (e->integer_type()->is_unsigned()
3453           && e->integer_type()->bits() == 8)
3454         {
3455           static tree string_to_byte_array_fndecl;
3456           ret = Gogo::call_builtin(&string_to_byte_array_fndecl,
3457                                    this->location(),
3458                                    "__go_string_to_byte_array",
3459                                    1,
3460                                    type_tree,
3461                                    TREE_TYPE(expr_tree),
3462                                    expr_tree);
3463         }
3464       else
3465         {
3466           gcc_assert(e == Type::lookup_integer_type("int"));
3467           static tree string_to_int_array_fndecl;
3468           ret = Gogo::call_builtin(&string_to_int_array_fndecl,
3469                                    this->location(),
3470                                    "__go_string_to_int_array",
3471                                    1,
3472                                    type_tree,
3473                                    TREE_TYPE(expr_tree),
3474                                    expr_tree);
3475         }
3476     }
3477   else if ((type->is_unsafe_pointer_type()
3478             && expr_type->points_to() != NULL)
3479            || (expr_type->is_unsafe_pointer_type()
3480                && type->points_to() != NULL))
3481     ret = fold_convert(type_tree, expr_tree);
3482   else if (type->is_unsafe_pointer_type()
3483            && expr_type->integer_type() != NULL)
3484     ret = convert_to_pointer(type_tree, expr_tree);
3485   else if (this->may_convert_function_types_
3486            && type->function_type() != NULL
3487            && expr_type->function_type() != NULL)
3488     ret = fold_convert_loc(this->location(), type_tree, expr_tree);
3489   else
3490     ret = Expression::convert_for_assignment(context, type, expr_type,
3491                                              expr_tree, this->location());
3492
3493   return ret;
3494 }
3495
3496 // Output a type conversion in a constant expression.
3497
3498 void
3499 Type_conversion_expression::do_export(Export* exp) const
3500 {
3501   exp->write_c_string("convert(");
3502   exp->write_type(this->type_);
3503   exp->write_c_string(", ");
3504   this->expr_->export_expression(exp);
3505   exp->write_c_string(")");
3506 }
3507
3508 // Import a type conversion or a struct construction.
3509
3510 Expression*
3511 Type_conversion_expression::do_import(Import* imp)
3512 {
3513   imp->require_c_string("convert(");
3514   Type* type = imp->read_type();
3515   imp->require_c_string(", ");
3516   Expression* val = Expression::import_expression(imp);
3517   imp->require_c_string(")");
3518   return Expression::make_cast(type, val, imp->location());
3519 }
3520
3521 // Make a type cast expression.
3522
3523 Expression*
3524 Expression::make_cast(Type* type, Expression* val, source_location location)
3525 {
3526   if (type->is_error_type() || val->is_error_expression())
3527     return Expression::make_error(location);
3528   return new Type_conversion_expression(type, val, location);
3529 }
3530
3531 // Unary expressions.
3532
3533 class Unary_expression : public Expression
3534 {
3535  public:
3536   Unary_expression(Operator op, Expression* expr, source_location location)
3537     : Expression(EXPRESSION_UNARY, location),
3538       op_(op), escapes_(true), expr_(expr)
3539   { }
3540
3541   // Return the operator.
3542   Operator
3543   op() const
3544   { return this->op_; }
3545
3546   // Return the operand.
3547   Expression*
3548   operand() const
3549   { return this->expr_; }
3550
3551   // Record that an address expression does not escape.
3552   void
3553   set_does_not_escape()
3554   {
3555     gcc_assert(this->op_ == OPERATOR_AND);
3556     this->escapes_ = false;
3557   }
3558
3559   // Apply unary opcode OP to UVAL, setting VAL.  Return true if this
3560   // could be done, false if not.
3561   static bool
3562   eval_integer(Operator op, Type* utype, mpz_t uval, mpz_t val,
3563                source_location);
3564
3565   // Apply unary opcode OP to UVAL, setting VAL.  Return true if this
3566   // could be done, false if not.
3567   static bool
3568   eval_float(Operator op, mpfr_t uval, mpfr_t val);
3569
3570   // Apply unary opcode OP to UREAL/UIMAG, setting REAL/IMAG.  Return
3571   // true if this could be done, false if not.
3572   static bool
3573   eval_complex(Operator op, mpfr_t ureal, mpfr_t uimag, mpfr_t real,
3574                mpfr_t imag);
3575
3576   static Expression*
3577   do_import(Import*);
3578
3579  protected:
3580   int
3581   do_traverse(Traverse* traverse)
3582   { return Expression::traverse(&this->expr_, traverse); }
3583
3584   Expression*
3585   do_lower(Gogo*, Named_object*, int);
3586
3587   bool
3588   do_is_constant() const;
3589
3590   bool
3591   do_integer_constant_value(bool, mpz_t, Type**) const;
3592
3593   bool
3594   do_float_constant_value(mpfr_t, Type**) const;
3595
3596   bool
3597   do_complex_constant_value(mpfr_t, mpfr_t, Type**) const;
3598
3599   Type*
3600   do_type();
3601
3602   void
3603   do_determine_type(const Type_context*);
3604
3605   void
3606   do_check_types(Gogo*);
3607
3608   Expression*
3609   do_copy()
3610   {
3611     return Expression::make_unary(this->op_, this->expr_->copy(),
3612                                   this->location());
3613   }
3614
3615   bool
3616   do_is_addressable() const
3617   { return this->op_ == OPERATOR_MULT; }
3618
3619   tree
3620   do_get_tree(Translate_context*);
3621
3622   void
3623   do_export(Export*) const;
3624
3625  private:
3626   // The unary operator to apply.
3627   Operator op_;
3628   // Normally true.  False if this is an address expression which does
3629   // not escape the current function.
3630   bool escapes_;
3631   // The operand.
3632   Expression* expr_;
3633 };
3634
3635 // If we are taking the address of a composite literal, and the
3636 // contents are not constant, then we want to make a heap composite
3637 // instead.
3638
3639 Expression*
3640 Unary_expression::do_lower(Gogo*, Named_object*, int)
3641 {
3642   source_location loc = this->location();
3643   Operator op = this->op_;
3644   Expression* expr = this->expr_;
3645
3646   if (op == OPERATOR_MULT && expr->is_type_expression())
3647     return Expression::make_type(Type::make_pointer_type(expr->type()), loc);
3648
3649   // *&x simplifies to x.  *(*T)(unsafe.Pointer)(&x) does not require
3650   // moving x to the heap.  FIXME: Is it worth doing a real escape
3651   // analysis here?  This case is found in math/unsafe.go and is
3652   // therefore worth special casing.
3653   if (op == OPERATOR_MULT)
3654     {
3655       Expression* e = expr;
3656       while (e->classification() == EXPRESSION_CONVERSION)
3657         {
3658           Type_conversion_expression* te
3659             = static_cast<Type_conversion_expression*>(e);
3660           e = te->expr();
3661         }
3662
3663       if (e->classification() == EXPRESSION_UNARY)
3664         {
3665           Unary_expression* ue = static_cast<Unary_expression*>(e);
3666           if (ue->op_ == OPERATOR_AND)
3667             {
3668               if (e == expr)
3669                 {
3670                   // *&x == x.
3671                   return ue->expr_;
3672                 }
3673               ue->set_does_not_escape();
3674             }
3675         }
3676     }
3677
3678   if (op == OPERATOR_PLUS || op == OPERATOR_MINUS
3679       || op == OPERATOR_NOT || op == OPERATOR_XOR)
3680     {
3681       Expression* ret = NULL;
3682
3683       mpz_t eval;
3684       mpz_init(eval);
3685       Type* etype;
3686       if (expr->integer_constant_value(false, eval, &etype))
3687         {
3688           mpz_t val;
3689           mpz_init(val);
3690           if (Unary_expression::eval_integer(op, etype, eval, val, loc))
3691             ret = Expression::make_integer(&val, etype, loc);
3692           mpz_clear(val);
3693         }
3694       mpz_clear(eval);
3695       if (ret != NULL)
3696         return ret;
3697
3698       if (op == OPERATOR_PLUS || op == OPERATOR_MINUS)
3699         {
3700           mpfr_t fval;
3701           mpfr_init(fval);
3702           Type* ftype;
3703           if (expr->float_constant_value(fval, &ftype))
3704             {
3705               mpfr_t val;
3706               mpfr_init(val);
3707               if (Unary_expression::eval_float(op, fval, val))
3708                 ret = Expression::make_float(&val, ftype, loc);
3709               mpfr_clear(val);
3710             }
3711           if (ret != NULL)
3712             {
3713               mpfr_clear(fval);
3714               return ret;
3715             }
3716
3717           mpfr_t ival;
3718           mpfr_init(ival);
3719           if (expr->complex_constant_value(fval, ival, &ftype))
3720             {
3721               mpfr_t real;
3722               mpfr_t imag;
3723               mpfr_init(real);
3724               mpfr_init(imag);
3725               if (Unary_expression::eval_complex(op, fval, ival, real, imag))
3726                 ret = Expression::make_complex(&real, &imag, ftype, loc);
3727               mpfr_clear(real);
3728               mpfr_clear(imag);
3729             }
3730           mpfr_clear(ival);
3731           mpfr_clear(fval);
3732           if (ret != NULL)
3733             return ret;
3734         }
3735     }
3736
3737   return this;
3738 }
3739
3740 // Return whether a unary expression is a constant.
3741
3742 bool
3743 Unary_expression::do_is_constant() const
3744 {
3745   if (this->op_ == OPERATOR_MULT)
3746     {
3747       // Indirecting through a pointer is only constant if the object
3748       // to which the expression points is constant, but we currently
3749       // have no way to determine that.
3750       return false;
3751     }
3752   else if (this->op_ == OPERATOR_AND)
3753     {
3754       // Taking the address of a variable is constant if it is a
3755       // global variable, not constant otherwise.  In other cases
3756       // taking the address is probably not a constant.
3757       Var_expression* ve = this->expr_->var_expression();
3758       if (ve != NULL)
3759         {
3760           Named_object* no = ve->named_object();
3761           return no->is_variable() && no->var_value()->is_global();
3762         }
3763       return false;
3764     }
3765   else
3766     return this->expr_->is_constant();
3767 }
3768
3769 // Apply unary opcode OP to UVAL, setting VAL.  UTYPE is the type of
3770 // UVAL, if known; it may be NULL.  Return true if this could be done,
3771 // false if not.
3772
3773 bool
3774 Unary_expression::eval_integer(Operator op, Type* utype, mpz_t uval, mpz_t val,
3775                                source_location location)
3776 {
3777   switch (op)
3778     {
3779     case OPERATOR_PLUS:
3780       mpz_set(val, uval);
3781       return true;
3782     case OPERATOR_MINUS:
3783       mpz_neg(val, uval);
3784       return Integer_expression::check_constant(val, utype, location);
3785     case OPERATOR_NOT:
3786       mpz_set_ui(val, mpz_cmp_si(uval, 0) == 0 ? 1 : 0);
3787       return true;
3788     case OPERATOR_XOR:
3789       if (utype == NULL
3790           || utype->integer_type() == NULL
3791           || utype->integer_type()->is_abstract())
3792         mpz_com(val, uval);
3793       else
3794         {
3795           // The number of HOST_WIDE_INTs that it takes to represent
3796           // UVAL.
3797           size_t count = ((mpz_sizeinbase(uval, 2)
3798                            + HOST_BITS_PER_WIDE_INT
3799                            - 1)
3800                           / HOST_BITS_PER_WIDE_INT);
3801
3802           unsigned HOST_WIDE_INT* phwi = new unsigned HOST_WIDE_INT[count];
3803           memset(phwi, 0, count * sizeof(HOST_WIDE_INT));
3804
3805           size_t ecount;
3806           mpz_export(phwi, &ecount, -1, sizeof(HOST_WIDE_INT), 0, 0, uval);
3807           gcc_assert(ecount <= count);
3808
3809           // Trim down to the number of words required by the type.
3810           size_t obits = utype->integer_type()->bits();
3811           if (!utype->integer_type()->is_unsigned())
3812             ++obits;
3813           size_t ocount = ((obits + HOST_BITS_PER_WIDE_INT - 1)
3814                            / HOST_BITS_PER_WIDE_INT);
3815           gcc_assert(ocount <= ocount);
3816
3817           for (size_t i = 0; i < ocount; ++i)
3818             phwi[i] = ~phwi[i];
3819
3820           size_t clearbits = ocount * HOST_BITS_PER_WIDE_INT - obits;
3821           if (clearbits != 0)
3822             phwi[ocount - 1] &= (((unsigned HOST_WIDE_INT) (HOST_WIDE_INT) -1)
3823                                  >> clearbits);
3824
3825           mpz_import(val, ocount, -1, sizeof(HOST_WIDE_INT), 0, 0, phwi);
3826
3827           delete[] phwi;
3828         }
3829       return Integer_expression::check_constant(val, utype, location);
3830     case OPERATOR_AND:
3831     case OPERATOR_MULT:
3832       return false;
3833     default:
3834       gcc_unreachable();
3835     }
3836 }
3837
3838 // Apply unary opcode OP to UVAL, setting VAL.  Return true if this
3839 // could be done, false if not.
3840
3841 bool
3842 Unary_expression::eval_float(Operator op, mpfr_t uval, mpfr_t val)
3843 {
3844   switch (op)
3845     {
3846     case OPERATOR_PLUS:
3847       mpfr_set(val, uval, GMP_RNDN);
3848       return true;
3849     case OPERATOR_MINUS:
3850       mpfr_neg(val, uval, GMP_RNDN);
3851       return true;
3852     case OPERATOR_NOT:
3853     case OPERATOR_XOR:
3854     case OPERATOR_AND:
3855     case OPERATOR_MULT:
3856       return false;
3857     default:
3858       gcc_unreachable();
3859     }
3860 }
3861
3862 // Apply unary opcode OP to RVAL/IVAL, setting REAL/IMAG.  Return true
3863 // if this could be done, false if not.
3864
3865 bool
3866 Unary_expression::eval_complex(Operator op, mpfr_t rval, mpfr_t ival,
3867                                mpfr_t real, mpfr_t imag)
3868 {
3869   switch (op)
3870     {
3871     case OPERATOR_PLUS:
3872       mpfr_set(real, rval, GMP_RNDN);
3873       mpfr_set(imag, ival, GMP_RNDN);
3874       return true;
3875     case OPERATOR_MINUS:
3876       mpfr_neg(real, rval, GMP_RNDN);
3877       mpfr_neg(imag, ival, GMP_RNDN);
3878       return true;
3879     case OPERATOR_NOT:
3880     case OPERATOR_XOR:
3881     case OPERATOR_AND:
3882     case OPERATOR_MULT:
3883       return false;
3884     default:
3885       gcc_unreachable();
3886     }
3887 }
3888
3889 // Return the integral constant value of a unary expression, if it has one.
3890
3891 bool
3892 Unary_expression::do_integer_constant_value(bool iota_is_constant, mpz_t val,
3893                                             Type** ptype) const
3894 {
3895   mpz_t uval;
3896   mpz_init(uval);
3897   bool ret;
3898   if (!this->expr_->integer_constant_value(iota_is_constant, uval, ptype))
3899     ret = false;
3900   else
3901     ret = Unary_expression::eval_integer(this->op_, *ptype, uval, val,
3902                                          this->location());
3903   mpz_clear(uval);
3904   return ret;
3905 }
3906
3907 // Return the floating point constant value of a unary expression, if
3908 // it has one.
3909
3910 bool
3911 Unary_expression::do_float_constant_value(mpfr_t val, Type** ptype) const
3912 {
3913   mpfr_t uval;
3914   mpfr_init(uval);
3915   bool ret;
3916   if (!this->expr_->float_constant_value(uval, ptype))
3917     ret = false;
3918   else
3919     ret = Unary_expression::eval_float(this->op_, uval, val);
3920   mpfr_clear(uval);
3921   return ret;
3922 }
3923
3924 // Return the complex constant value of a unary expression, if it has
3925 // one.
3926
3927 bool
3928 Unary_expression::do_complex_constant_value(mpfr_t real, mpfr_t imag,
3929                                             Type** ptype) const
3930 {
3931   mpfr_t rval;
3932   mpfr_t ival;
3933   mpfr_init(rval);
3934   mpfr_init(ival);
3935   bool ret;
3936   if (!this->expr_->complex_constant_value(rval, ival, ptype))
3937     ret = false;
3938   else
3939     ret = Unary_expression::eval_complex(this->op_, rval, ival, real, imag);
3940   mpfr_clear(rval);
3941   mpfr_clear(ival);
3942   return ret;
3943 }
3944
3945 // Return the type of a unary expression.
3946
3947 Type*
3948 Unary_expression::do_type()
3949 {
3950   switch (this->op_)
3951     {
3952     case OPERATOR_PLUS:
3953     case OPERATOR_MINUS:
3954     case OPERATOR_NOT:
3955     case OPERATOR_XOR:
3956       return this->expr_->type();
3957
3958     case OPERATOR_AND:
3959       return Type::make_pointer_type(this->expr_->type());
3960
3961     case OPERATOR_MULT:
3962       {
3963         Type* subtype = this->expr_->type();
3964         Type* points_to = subtype->points_to();
3965         if (points_to == NULL)
3966           return Type::make_error_type();
3967         return points_to;
3968       }
3969
3970     default:
3971       gcc_unreachable();
3972     }
3973 }
3974
3975 // Determine abstract types for a unary expression.
3976
3977 void
3978 Unary_expression::do_determine_type(const Type_context* context)
3979 {
3980   switch (this->op_)
3981     {
3982     case OPERATOR_PLUS:
3983     case OPERATOR_MINUS:
3984     case OPERATOR_NOT:
3985     case OPERATOR_XOR:
3986       this->expr_->determine_type(context);
3987       break;
3988
3989     case OPERATOR_AND:
3990       // Taking the address of something.
3991       {
3992         Type* subtype = (context->type == NULL
3993                          ? NULL
3994                          : context->type->points_to());
3995         Type_context subcontext(subtype, false);
3996         this->expr_->determine_type(&subcontext);
3997       }
3998       break;
3999
4000     case OPERATOR_MULT:
4001       // Indirecting through a pointer.
4002       {
4003         Type* subtype = (context->type == NULL
4004                          ? NULL
4005                          : Type::make_pointer_type(context->type));
4006         Type_context subcontext(subtype, false);
4007         this->expr_->determine_type(&subcontext);
4008       }
4009       break;
4010
4011     default:
4012       gcc_unreachable();
4013     }
4014 }
4015
4016 // Check types for a unary expression.
4017
4018 void
4019 Unary_expression::do_check_types(Gogo*)
4020 {
4021   Type* type = this->expr_->type();
4022   if (type->is_error_type())
4023     {
4024       this->set_is_error();
4025       return;
4026     }
4027
4028   switch (this->op_)
4029     {
4030     case OPERATOR_PLUS:
4031     case OPERATOR_MINUS:
4032       if (type->integer_type() == NULL
4033           && type->float_type() == NULL
4034           && type->complex_type() == NULL)
4035         this->report_error(_("expected numeric type"));
4036       break;
4037
4038     case OPERATOR_NOT:
4039     case OPERATOR_XOR:
4040       if (type->integer_type() == NULL
4041           && !type->is_boolean_type())
4042         this->report_error(_("expected integer or boolean type"));
4043       break;
4044
4045     case OPERATOR_AND:
4046       if (!this->expr_->is_addressable())
4047         this->report_error(_("invalid operand for unary %<&%>"));
4048       else
4049         this->expr_->address_taken(this->escapes_);
4050       break;
4051
4052     case OPERATOR_MULT:
4053       // Indirecting through a pointer.
4054       if (type->points_to() == NULL)
4055         this->report_error(_("expected pointer"));
4056       break;
4057
4058     default:
4059       gcc_unreachable();
4060     }
4061 }
4062
4063 // Get a tree for a unary expression.
4064
4065 tree
4066 Unary_expression::do_get_tree(Translate_context* context)
4067 {
4068   tree expr = this->expr_->get_tree(context);
4069   if (expr == error_mark_node)
4070     return error_mark_node;
4071
4072   source_location loc = this->location();
4073   switch (this->op_)
4074     {
4075     case OPERATOR_PLUS:
4076       return expr;
4077
4078     case OPERATOR_MINUS:
4079       {
4080         tree type = TREE_TYPE(expr);
4081         tree compute_type = excess_precision_type(type);
4082         if (compute_type != NULL_TREE)
4083           expr = ::convert(compute_type, expr);
4084         tree ret = fold_build1_loc(loc, NEGATE_EXPR,
4085                                    (compute_type != NULL_TREE
4086                                     ? compute_type
4087                                     : type),
4088                                    expr);
4089         if (compute_type != NULL_TREE)
4090           ret = ::convert(type, ret);
4091         return ret;
4092       }
4093
4094     case OPERATOR_NOT:
4095       if (TREE_CODE(TREE_TYPE(expr)) == BOOLEAN_TYPE)
4096         return fold_build1_loc(loc, TRUTH_NOT_EXPR, TREE_TYPE(expr), expr);
4097       else
4098         return fold_build2_loc(loc, NE_EXPR, boolean_type_node, expr,
4099                                build_int_cst(TREE_TYPE(expr), 0));
4100
4101     case OPERATOR_XOR:
4102       return fold_build1_loc(loc, BIT_NOT_EXPR, TREE_TYPE(expr), expr);
4103
4104     case OPERATOR_AND:
4105       // We should not see a non-constant constructor here; cases
4106       // where we would see one should have been moved onto the heap
4107       // at parse time.  Taking the address of a nonconstant
4108       // constructor will not do what the programmer expects.
4109       gcc_assert(TREE_CODE(expr) != CONSTRUCTOR || TREE_CONSTANT(expr));
4110       gcc_assert(TREE_CODE(expr) != ADDR_EXPR);
4111
4112       // Build a decl for a constant constructor.
4113       if (TREE_CODE(expr) == CONSTRUCTOR && TREE_CONSTANT(expr))
4114         {
4115           tree decl = build_decl(this->location(), VAR_DECL,
4116                                  create_tmp_var_name("C"), TREE_TYPE(expr));
4117           DECL_EXTERNAL(decl) = 0;
4118           TREE_PUBLIC(decl) = 0;
4119           TREE_READONLY(decl) = 1;
4120           TREE_CONSTANT(decl) = 1;
4121           TREE_STATIC(decl) = 1;
4122           TREE_ADDRESSABLE(decl) = 1;
4123           DECL_ARTIFICIAL(decl) = 1;
4124           DECL_INITIAL(decl) = expr;
4125           rest_of_decl_compilation(decl, 1, 0);
4126           expr = decl;
4127         }
4128
4129       return build_fold_addr_expr_loc(loc, expr);
4130
4131     case OPERATOR_MULT:
4132       {
4133         gcc_assert(POINTER_TYPE_P(TREE_TYPE(expr)));
4134
4135         // If we are dereferencing the pointer to a large struct, we
4136         // need to check for nil.  We don't bother to check for small
4137         // structs because we expect the system to crash on a nil
4138         // pointer dereference.
4139         HOST_WIDE_INT s = int_size_in_bytes(TREE_TYPE(TREE_TYPE(expr)));
4140         if (s == -1 || s >= 4096)
4141           {
4142             if (!DECL_P(expr))
4143               expr = save_expr(expr);
4144             tree compare = fold_build2_loc(loc, EQ_EXPR, boolean_type_node,
4145                                            expr,
4146                                            fold_convert(TREE_TYPE(expr),
4147                                                         null_pointer_node));
4148             tree crash = Gogo::runtime_error(RUNTIME_ERROR_NIL_DEREFERENCE,
4149                                              loc);
4150             expr = fold_build2_loc(loc, COMPOUND_EXPR, TREE_TYPE(expr),
4151                                    build3(COND_EXPR, void_type_node,
4152                                           compare, crash, NULL_TREE),
4153                                    expr);
4154           }
4155
4156         // If the type of EXPR is a recursive pointer type, then we
4157         // need to insert a cast before indirecting.
4158         if (TREE_TYPE(TREE_TYPE(expr)) == ptr_type_node)
4159           {
4160             Type* pt = this->expr_->type()->points_to();
4161             tree ind = pt->get_tree(context->gogo());
4162             expr = fold_convert_loc(loc, build_pointer_type(ind), expr);
4163           }
4164
4165         return build_fold_indirect_ref_loc(loc, expr);
4166       }
4167
4168     default:
4169       gcc_unreachable();
4170     }
4171 }
4172
4173 // Export a unary expression.
4174
4175 void
4176 Unary_expression::do_export(Export* exp) const
4177 {
4178   switch (this->op_)
4179     {
4180     case OPERATOR_PLUS:
4181       exp->write_c_string("+ ");
4182       break;
4183     case OPERATOR_MINUS:
4184       exp->write_c_string("- ");
4185       break;
4186     case OPERATOR_NOT:
4187       exp->write_c_string("! ");
4188       break;
4189     case OPERATOR_XOR:
4190       exp->write_c_string("^ ");
4191       break;
4192     case OPERATOR_AND:
4193     case OPERATOR_MULT:
4194     default:
4195       gcc_unreachable();
4196     }
4197   this->expr_->export_expression(exp);
4198 }
4199
4200 // Import a unary expression.
4201
4202 Expression*
4203 Unary_expression::do_import(Import* imp)
4204 {
4205   Operator op;
4206   switch (imp->get_char())
4207     {
4208     case '+':
4209       op = OPERATOR_PLUS;
4210       break;
4211     case '-':
4212       op = OPERATOR_MINUS;
4213       break;
4214     case '!':
4215       op = OPERATOR_NOT;
4216       break;
4217     case '^':
4218       op = OPERATOR_XOR;
4219       break;
4220     default:
4221       gcc_unreachable();
4222     }
4223   imp->require_c_string(" ");
4224   Expression* expr = Expression::import_expression(imp);
4225   return Expression::make_unary(op, expr, imp->location());
4226 }
4227
4228 // Make a unary expression.
4229
4230 Expression*
4231 Expression::make_unary(Operator op, Expression* expr, source_location location)
4232 {
4233   return new Unary_expression(op, expr, location);
4234 }
4235
4236 // If this is an indirection through a pointer, return the expression
4237 // being pointed through.  Otherwise return this.
4238
4239 Expression*
4240 Expression::deref()
4241 {
4242   if (this->classification_ == EXPRESSION_UNARY)
4243     {
4244       Unary_expression* ue = static_cast<Unary_expression*>(this);
4245       if (ue->op() == OPERATOR_MULT)
4246         return ue->operand();
4247     }
4248   return this;
4249 }
4250
4251 // Class Binary_expression.
4252
4253 // Traversal.
4254
4255 int
4256 Binary_expression::do_traverse(Traverse* traverse)
4257 {
4258   int t = Expression::traverse(&this->left_, traverse);
4259   if (t == TRAVERSE_EXIT)
4260     return TRAVERSE_EXIT;
4261   return Expression::traverse(&this->right_, traverse);
4262 }
4263
4264 // Compare integer constants according to OP.
4265
4266 bool
4267 Binary_expression::compare_integer(Operator op, mpz_t left_val,
4268                                    mpz_t right_val)
4269 {
4270   int i = mpz_cmp(left_val, right_val);
4271   switch (op)
4272     {
4273     case OPERATOR_EQEQ:
4274       return i == 0;
4275     case OPERATOR_NOTEQ:
4276       return i != 0;
4277     case OPERATOR_LT:
4278       return i < 0;
4279     case OPERATOR_LE:
4280       return i <= 0;
4281     case OPERATOR_GT:
4282       return i > 0;
4283     case OPERATOR_GE:
4284       return i >= 0;
4285     default:
4286       gcc_unreachable();
4287     }
4288 }
4289
4290 // Compare floating point constants according to OP.
4291
4292 bool
4293 Binary_expression::compare_float(Operator op, Type* type, mpfr_t left_val,
4294                                  mpfr_t right_val)
4295 {
4296   int i;
4297   if (type == NULL)
4298     i = mpfr_cmp(left_val, right_val);
4299   else
4300     {
4301       mpfr_t lv;
4302       mpfr_init_set(lv, left_val, GMP_RNDN);
4303       mpfr_t rv;
4304       mpfr_init_set(rv, right_val, GMP_RNDN);
4305       Float_expression::constrain_float(lv, type);
4306       Float_expression::constrain_float(rv, type);
4307       i = mpfr_cmp(lv, rv);
4308       mpfr_clear(lv);
4309       mpfr_clear(rv);
4310     }
4311   switch (op)
4312     {
4313     case OPERATOR_EQEQ:
4314       return i == 0;
4315     case OPERATOR_NOTEQ:
4316       return i != 0;
4317     case OPERATOR_LT:
4318       return i < 0;
4319     case OPERATOR_LE:
4320       return i <= 0;
4321     case OPERATOR_GT:
4322       return i > 0;
4323     case OPERATOR_GE:
4324       return i >= 0;
4325     default:
4326       gcc_unreachable();
4327     }
4328 }
4329
4330 // Compare complex constants according to OP.  Complex numbers may
4331 // only be compared for equality.
4332
4333 bool
4334 Binary_expression::compare_complex(Operator op, Type* type,
4335                                    mpfr_t left_real, mpfr_t left_imag,
4336                                    mpfr_t right_real, mpfr_t right_imag)
4337 {
4338   bool is_equal;
4339   if (type == NULL)
4340     is_equal = (mpfr_cmp(left_real, right_real) == 0
4341                 && mpfr_cmp(left_imag, right_imag) == 0);
4342   else
4343     {
4344       mpfr_t lr;
4345       mpfr_t li;
4346       mpfr_init_set(lr, left_real, GMP_RNDN);
4347       mpfr_init_set(li, left_imag, GMP_RNDN);
4348       mpfr_t rr;
4349       mpfr_t ri;
4350       mpfr_init_set(rr, right_real, GMP_RNDN);
4351       mpfr_init_set(ri, right_imag, GMP_RNDN);
4352       Complex_expression::constrain_complex(lr, li, type);
4353       Complex_expression::constrain_complex(rr, ri, type);
4354       is_equal = mpfr_cmp(lr, rr) == 0 && mpfr_cmp(li, ri) == 0;
4355       mpfr_clear(lr);
4356       mpfr_clear(li);
4357       mpfr_clear(rr);
4358       mpfr_clear(ri);
4359     }
4360   switch (op)
4361     {
4362     case OPERATOR_EQEQ:
4363       return is_equal;
4364     case OPERATOR_NOTEQ:
4365       return !is_equal;
4366     default:
4367       gcc_unreachable();
4368     }
4369 }
4370
4371 // Apply binary opcode OP to LEFT_VAL and RIGHT_VAL, setting VAL.
4372 // LEFT_TYPE is the type of LEFT_VAL, RIGHT_TYPE is the type of
4373 // RIGHT_VAL; LEFT_TYPE and/or RIGHT_TYPE may be NULL.  Return true if
4374 // this could be done, false if not.
4375
4376 bool
4377 Binary_expression::eval_integer(Operator op, Type* left_type, mpz_t left_val,
4378                                 Type* right_type, mpz_t right_val,
4379                                 source_location location, mpz_t val)
4380 {
4381   bool is_shift_op = false;
4382   switch (op)
4383     {
4384     case OPERATOR_OROR:
4385     case OPERATOR_ANDAND:
4386     case OPERATOR_EQEQ:
4387     case OPERATOR_NOTEQ:
4388     case OPERATOR_LT:
4389     case OPERATOR_LE:
4390     case OPERATOR_GT:
4391     case OPERATOR_GE:
4392       // These return boolean values.  We should probably handle them
4393       // anyhow in case a type conversion is used on the result.
4394       return false;
4395     case OPERATOR_PLUS:
4396       mpz_add(val, left_val, right_val);
4397       break;
4398     case OPERATOR_MINUS:
4399       mpz_sub(val, left_val, right_val);
4400       break;
4401     case OPERATOR_OR:
4402       mpz_ior(val, left_val, right_val);
4403       break;
4404     case OPERATOR_XOR:
4405       mpz_xor(val, left_val, right_val);
4406       break;
4407     case OPERATOR_MULT:
4408       mpz_mul(val, left_val, right_val);
4409       break;
4410     case OPERATOR_DIV:
4411       if (mpz_sgn(right_val) != 0)
4412         mpz_tdiv_q(val, left_val, right_val);
4413       else
4414         {
4415           error_at(location, "division by zero");
4416           mpz_set_ui(val, 0);
4417           return true;
4418         }
4419       break;
4420     case OPERATOR_MOD:
4421       if (mpz_sgn(right_val) != 0)
4422         mpz_tdiv_r(val, left_val, right_val);
4423       else
4424         {
4425           error_at(location, "division by zero");
4426           mpz_set_ui(val, 0);
4427           return true;
4428         }
4429       break;
4430     case OPERATOR_LSHIFT:
4431       {
4432         unsigned long shift = mpz_get_ui(right_val);
4433         if (mpz_cmp_ui(right_val, shift) != 0)
4434           {
4435             error_at(location, "shift count overflow");
4436             mpz_set_ui(val, 0);
4437             return true;
4438           }
4439         mpz_mul_2exp(val, left_val, shift);
4440         is_shift_op = true;
4441         break;
4442       }
4443       break;
4444     case OPERATOR_RSHIFT:
4445       {
4446         unsigned long shift = mpz_get_ui(right_val);
4447         if (mpz_cmp_ui(right_val, shift) != 0)
4448           {
4449             error_at(location, "shift count overflow");
4450             mpz_set_ui(val, 0);
4451             return true;
4452           }
4453         if (mpz_cmp_ui(left_val, 0) >= 0)
4454           mpz_tdiv_q_2exp(val, left_val, shift);
4455         else
4456           mpz_fdiv_q_2exp(val, left_val, shift);
4457         is_shift_op = true;
4458         break;
4459       }
4460       break;
4461     case OPERATOR_AND:
4462       mpz_and(val, left_val, right_val);
4463       break;
4464     case OPERATOR_BITCLEAR:
4465       {
4466         mpz_t tval;
4467         mpz_init(tval);
4468         mpz_com(tval, right_val);
4469         mpz_and(val, left_val, tval);
4470         mpz_clear(tval);
4471       }
4472       break;
4473     default:
4474       gcc_unreachable();
4475     }
4476
4477   Type* type = left_type;
4478   if (!is_shift_op)
4479     {
4480       if (type == NULL)
4481         type = right_type;
4482       else if (type != right_type && right_type != NULL)
4483         {
4484           if (type->is_abstract())
4485             type = right_type;
4486           else if (!right_type->is_abstract())
4487             {
4488               // This look like a type error which should be diagnosed
4489               // elsewhere.  Don't do anything here, to avoid an
4490               // unhelpful chain of error messages.
4491               return true;
4492             }
4493         }
4494     }
4495
4496   if (type != NULL && !type->is_abstract())
4497     {
4498       // We have to check the operands too, as we have implicitly
4499       // coerced them to TYPE.
4500       if ((type != left_type
4501            && !Integer_expression::check_constant(left_val, type, location))
4502           || (!is_shift_op
4503               && type != right_type
4504               && !Integer_expression::check_constant(right_val, type,
4505                                                      location))
4506           || !Integer_expression::check_constant(val, type, location))
4507         mpz_set_ui(val, 0);
4508     }
4509
4510   return true;
4511 }
4512
4513 // Apply binary opcode OP to LEFT_VAL and RIGHT_VAL, setting VAL.
4514 // Return true if this could be done, false if not.
4515
4516 bool
4517 Binary_expression::eval_float(Operator op, Type* left_type, mpfr_t left_val,
4518                               Type* right_type, mpfr_t right_val,
4519                               mpfr_t val, source_location location)
4520 {
4521   switch (op)
4522     {
4523     case OPERATOR_OROR:
4524     case OPERATOR_ANDAND:
4525     case OPERATOR_EQEQ:
4526     case OPERATOR_NOTEQ:
4527     case OPERATOR_LT:
4528     case OPERATOR_LE:
4529     case OPERATOR_GT:
4530     case OPERATOR_GE:
4531       // These return boolean values.  We should probably handle them
4532       // anyhow in case a type conversion is used on the result.
4533       return false;
4534     case OPERATOR_PLUS:
4535       mpfr_add(val, left_val, right_val, GMP_RNDN);
4536       break;
4537     case OPERATOR_MINUS:
4538       mpfr_sub(val, left_val, right_val, GMP_RNDN);
4539       break;
4540     case OPERATOR_OR:
4541     case OPERATOR_XOR:
4542     case OPERATOR_AND:
4543     case OPERATOR_BITCLEAR:
4544       return false;
4545     case OPERATOR_MULT:
4546       mpfr_mul(val, left_val, right_val, GMP_RNDN);
4547       break;
4548     case OPERATOR_DIV:
4549       if (mpfr_zero_p(right_val))
4550         error_at(location, "division by zero");
4551       mpfr_div(val, left_val, right_val, GMP_RNDN);
4552       break;
4553     case OPERATOR_MOD:
4554       return false;
4555     case OPERATOR_LSHIFT:
4556     case OPERATOR_RSHIFT:
4557       return false;
4558     default:
4559       gcc_unreachable();
4560     }
4561
4562   Type* type = left_type;
4563   if (type == NULL)
4564     type = right_type;
4565   else if (type != right_type && right_type != NULL)
4566     {
4567       if (type->is_abstract())
4568         type = right_type;
4569       else if (!right_type->is_abstract())
4570         {
4571           // This looks like a type error which should be diagnosed
4572           // elsewhere.  Don't do anything here, to avoid an unhelpful
4573           // chain of error messages.
4574           return true;
4575         }
4576     }
4577
4578   if (type != NULL && !type->is_abstract())
4579     {
4580       if ((type != left_type
4581            && !Float_expression::check_constant(left_val, type, location))
4582           || (type != right_type
4583               && !Float_expression::check_constant(right_val, type,
4584                                                    location))
4585           || !Float_expression::check_constant(val, type, location))
4586         mpfr_set_ui(val, 0, GMP_RNDN);
4587     }
4588
4589   return true;
4590 }
4591
4592 // Apply binary opcode OP to LEFT_REAL/LEFT_IMAG and
4593 // RIGHT_REAL/RIGHT_IMAG, setting REAL/IMAG.  Return true if this
4594 // could be done, false if not.
4595
4596 bool
4597 Binary_expression::eval_complex(Operator op, Type* left_type,
4598                                 mpfr_t left_real, mpfr_t left_imag,
4599                                 Type *right_type,
4600                                 mpfr_t right_real, mpfr_t right_imag,
4601                                 mpfr_t real, mpfr_t imag,
4602                                 source_location location)
4603 {
4604   switch (op)
4605     {
4606     case OPERATOR_OROR:
4607     case OPERATOR_ANDAND:
4608     case OPERATOR_EQEQ:
4609     case OPERATOR_NOTEQ:
4610     case OPERATOR_LT:
4611     case OPERATOR_LE:
4612     case OPERATOR_GT:
4613     case OPERATOR_GE:
4614       // These return boolean values and must be handled differently.
4615       return false;
4616     case OPERATOR_PLUS:
4617       mpfr_add(real, left_real, right_real, GMP_RNDN);
4618       mpfr_add(imag, left_imag, right_imag, GMP_RNDN);
4619       break;
4620     case OPERATOR_MINUS:
4621       mpfr_sub(real, left_real, right_real, GMP_RNDN);
4622       mpfr_sub(imag, left_imag, right_imag, GMP_RNDN);
4623       break;
4624     case OPERATOR_OR:
4625     case OPERATOR_XOR:
4626     case OPERATOR_AND:
4627     case OPERATOR_BITCLEAR:
4628       return false;
4629     case OPERATOR_MULT:
4630       {
4631         // You might think that multiplying two complex numbers would
4632         // be simple, and you would be right, until you start to think
4633         // about getting the right answer for infinity.  If one
4634         // operand here is infinity and the other is anything other
4635         // than zero or NaN, then we are going to wind up subtracting
4636         // two infinity values.  That will give us a NaN, but the
4637         // correct answer is infinity.
4638
4639         mpfr_t lrrr;
4640         mpfr_init(lrrr);
4641         mpfr_mul(lrrr, left_real, right_real, GMP_RNDN);
4642
4643         mpfr_t lrri;
4644         mpfr_init(lrri);
4645         mpfr_mul(lrri, left_real, right_imag, GMP_RNDN);
4646
4647         mpfr_t lirr;
4648         mpfr_init(lirr);
4649         mpfr_mul(lirr, left_imag, right_real, GMP_RNDN);
4650
4651         mpfr_t liri;
4652         mpfr_init(liri);
4653         mpfr_mul(liri, left_imag, right_imag, GMP_RNDN);
4654
4655         mpfr_sub(real, lrrr, liri, GMP_RNDN);
4656         mpfr_add(imag, lrri, lirr, GMP_RNDN);
4657
4658         // If we get NaN on both sides, check whether it should really
4659         // be infinity.  The rule is that if either side of the
4660         // complex number is infinity, then the whole value is
4661         // infinity, even if the other side is NaN.  So the only case
4662         // we have to fix is the one in which both sides are NaN.
4663         if (mpfr_nan_p(real) && mpfr_nan_p(imag)
4664             && (!mpfr_nan_p(left_real) || !mpfr_nan_p(left_imag))
4665             && (!mpfr_nan_p(right_real) || !mpfr_nan_p(right_imag)))
4666           {
4667             bool is_infinity = false;
4668
4669             mpfr_t lr;
4670             mpfr_t li;
4671             mpfr_init_set(lr, left_real, GMP_RNDN);
4672             mpfr_init_set(li, left_imag, GMP_RNDN);
4673
4674             mpfr_t rr;
4675             mpfr_t ri;
4676             mpfr_init_set(rr, right_real, GMP_RNDN);
4677             mpfr_init_set(ri, right_imag, GMP_RNDN);
4678
4679             // If the left side is infinity, then the result is
4680             // infinity.
4681             if (mpfr_inf_p(lr) || mpfr_inf_p(li))
4682               {
4683                 mpfr_set_ui(lr, mpfr_inf_p(lr) ? 1 : 0, GMP_RNDN);
4684                 mpfr_copysign(lr, lr, left_real, GMP_RNDN);
4685                 mpfr_set_ui(li, mpfr_inf_p(li) ? 1 : 0, GMP_RNDN);
4686                 mpfr_copysign(li, li, left_imag, GMP_RNDN);
4687                 if (mpfr_nan_p(rr))
4688                   {
4689                     mpfr_set_ui(rr, 0, GMP_RNDN);
4690                     mpfr_copysign(rr, rr, right_real, GMP_RNDN);
4691                   }
4692                 if (mpfr_nan_p(ri))
4693                   {
4694                     mpfr_set_ui(ri, 0, GMP_RNDN);
4695                     mpfr_copysign(ri, ri, right_imag, GMP_RNDN);
4696                   }
4697                 is_infinity = true;
4698               }
4699
4700             // If the right side is infinity, then the result is
4701             // infinity.
4702             if (mpfr_inf_p(rr) || mpfr_inf_p(ri))
4703               {
4704                 mpfr_set_ui(rr, mpfr_inf_p(rr) ? 1 : 0, GMP_RNDN);
4705                 mpfr_copysign(rr, rr, right_real, GMP_RNDN);
4706                 mpfr_set_ui(ri, mpfr_inf_p(ri) ? 1 : 0, GMP_RNDN);
4707                 mpfr_copysign(ri, ri, right_imag, GMP_RNDN);
4708                 if (mpfr_nan_p(lr))
4709                   {
4710                     mpfr_set_ui(lr, 0, GMP_RNDN);
4711                     mpfr_copysign(lr, lr, left_real, GMP_RNDN);
4712                   }
4713                 if (mpfr_nan_p(li))
4714                   {
4715                     mpfr_set_ui(li, 0, GMP_RNDN);
4716                     mpfr_copysign(li, li, left_imag, GMP_RNDN);
4717                   }
4718                 is_infinity = true;
4719               }
4720
4721             // If we got an overflow in the intermediate computations,
4722             // then the result is infinity.
4723             if (!is_infinity
4724                 && (mpfr_inf_p(lrrr) || mpfr_inf_p(lrri)
4725                     || mpfr_inf_p(lirr) || mpfr_inf_p(liri)))
4726               {
4727                 if (mpfr_nan_p(lr))
4728                   {
4729                     mpfr_set_ui(lr, 0, GMP_RNDN);
4730                     mpfr_copysign(lr, lr, left_real, GMP_RNDN);
4731                   }
4732                 if (mpfr_nan_p(li))
4733                   {
4734                     mpfr_set_ui(li, 0, GMP_RNDN);
4735                     mpfr_copysign(li, li, left_imag, GMP_RNDN);
4736                   }
4737                 if (mpfr_nan_p(rr))
4738                   {
4739                     mpfr_set_ui(rr, 0, GMP_RNDN);
4740                     mpfr_copysign(rr, rr, right_real, GMP_RNDN);
4741                   }
4742                 if (mpfr_nan_p(ri))
4743                   {
4744                     mpfr_set_ui(ri, 0, GMP_RNDN);
4745                     mpfr_copysign(ri, ri, right_imag, GMP_RNDN);
4746                   }
4747                 is_infinity = true;
4748               }
4749
4750             if (is_infinity)
4751               {
4752                 mpfr_mul(lrrr, lr, rr, GMP_RNDN);
4753                 mpfr_mul(lrri, lr, ri, GMP_RNDN);
4754                 mpfr_mul(lirr, li, rr, GMP_RNDN);
4755                 mpfr_mul(liri, li, ri, GMP_RNDN);
4756                 mpfr_sub(real, lrrr, liri, GMP_RNDN);
4757                 mpfr_add(imag, lrri, lirr, GMP_RNDN);
4758                 mpfr_set_inf(real, mpfr_sgn(real));
4759                 mpfr_set_inf(imag, mpfr_sgn(imag));
4760               }
4761
4762             mpfr_clear(lr);
4763             mpfr_clear(li);
4764             mpfr_clear(rr);
4765             mpfr_clear(ri);
4766           }
4767
4768         mpfr_clear(lrrr);
4769         mpfr_clear(lrri);
4770         mpfr_clear(lirr);
4771         mpfr_clear(liri);
4772       }
4773       break;
4774     case OPERATOR_DIV:
4775       {
4776         // For complex division we want to avoid having an
4777         // intermediate overflow turn the whole result in a NaN.  We
4778         // scale the values to try to avoid this.
4779
4780         if (mpfr_zero_p(right_real) && mpfr_zero_p(right_imag))
4781           error_at(location, "division by zero");
4782
4783         mpfr_t rra;
4784         mpfr_t ria;
4785         mpfr_init(rra);
4786         mpfr_init(ria);
4787         mpfr_abs(rra, right_real, GMP_RNDN);
4788         mpfr_abs(ria, right_imag, GMP_RNDN);
4789         mpfr_t t;
4790         mpfr_init(t);
4791         mpfr_max(t, rra, ria, GMP_RNDN);
4792
4793         mpfr_t rr;
4794         mpfr_t ri;
4795         mpfr_init_set(rr, right_real, GMP_RNDN);
4796         mpfr_init_set(ri, right_imag, GMP_RNDN);
4797         long ilogbw = 0;
4798         if (!mpfr_inf_p(t) && !mpfr_nan_p(t) && !mpfr_zero_p(t))
4799           {
4800             ilogbw = mpfr_get_exp(t);
4801             mpfr_mul_2si(rr, rr, - ilogbw, GMP_RNDN);
4802             mpfr_mul_2si(ri, ri, - ilogbw, GMP_RNDN);
4803           }
4804
4805         mpfr_t denom;
4806         mpfr_init(denom);
4807         mpfr_mul(denom, rr, rr, GMP_RNDN);
4808         mpfr_mul(t, ri, ri, GMP_RNDN);
4809         mpfr_add(denom, denom, t, GMP_RNDN);
4810
4811         mpfr_mul(real, left_real, rr, GMP_RNDN);
4812         mpfr_mul(t, left_imag, ri, GMP_RNDN);
4813         mpfr_add(real, real, t, GMP_RNDN);
4814         mpfr_div(real, real, denom, GMP_RNDN);
4815         mpfr_mul_2si(real, real, - ilogbw, GMP_RNDN);
4816
4817         mpfr_mul(imag, left_imag, rr, GMP_RNDN);
4818         mpfr_mul(t, left_real, ri, GMP_RNDN);
4819         mpfr_sub(imag, imag, t, GMP_RNDN);
4820         mpfr_div(imag, imag, denom, GMP_RNDN);
4821         mpfr_mul_2si(imag, imag, - ilogbw, GMP_RNDN);
4822
4823         // If we wind up with NaN on both sides, check whether we
4824         // should really have infinity.  The rule is that if either
4825         // side of the complex number is infinity, then the whole
4826         // value is infinity, even if the other side is NaN.  So the
4827         // only case we have to fix is the one in which both sides are
4828         // NaN.
4829         if (mpfr_nan_p(real) && mpfr_nan_p(imag)
4830             && (!mpfr_nan_p(left_real) || !mpfr_nan_p(left_imag))
4831             && (!mpfr_nan_p(right_real) || !mpfr_nan_p(right_imag)))
4832           {
4833             if (mpfr_zero_p(denom))
4834               {
4835                 mpfr_set_inf(real, mpfr_sgn(rr));
4836                 mpfr_mul(real, real, left_real, GMP_RNDN);
4837                 mpfr_set_inf(imag, mpfr_sgn(rr));
4838                 mpfr_mul(imag, imag, left_imag, GMP_RNDN);
4839               }
4840             else if ((mpfr_inf_p(left_real) || mpfr_inf_p(left_imag))
4841                      && mpfr_number_p(rr) && mpfr_number_p(ri))
4842               {
4843                 mpfr_set_ui(t, mpfr_inf_p(left_real) ? 1 : 0, GMP_RNDN);
4844                 mpfr_copysign(t, t, left_real, GMP_RNDN);
4845
4846                 mpfr_t t2;
4847                 mpfr_init_set_ui(t2, mpfr_inf_p(left_imag) ? 1 : 0, GMP_RNDN);
4848                 mpfr_copysign(t2, t2, left_imag, GMP_RNDN);
4849
4850                 mpfr_t t3;
4851                 mpfr_init(t3);
4852                 mpfr_mul(t3, t, rr, GMP_RNDN);
4853
4854                 mpfr_t t4;
4855                 mpfr_init(t4);
4856                 mpfr_mul(t4, t2, ri, GMP_RNDN);
4857
4858                 mpfr_add(t3, t3, t4, GMP_RNDN);
4859                 mpfr_set_inf(real, mpfr_sgn(t3));
4860
4861                 mpfr_mul(t3, t2, rr, GMP_RNDN);
4862                 mpfr_mul(t4, t, ri, GMP_RNDN);
4863                 mpfr_sub(t3, t3, t4, GMP_RNDN);
4864                 mpfr_set_inf(imag, mpfr_sgn(t3));
4865
4866                 mpfr_clear(t2);
4867                 mpfr_clear(t3);
4868                 mpfr_clear(t4);
4869               }
4870             else if ((mpfr_inf_p(right_real) || mpfr_inf_p(right_imag))
4871                      && mpfr_number_p(left_real) && mpfr_number_p(left_imag))
4872               {
4873                 mpfr_set_ui(t, mpfr_inf_p(rr) ? 1 : 0, GMP_RNDN);
4874                 mpfr_copysign(t, t, rr, GMP_RNDN);
4875
4876                 mpfr_t t2;
4877                 mpfr_init_set_ui(t2, mpfr_inf_p(ri) ? 1 : 0, GMP_RNDN);
4878                 mpfr_copysign(t2, t2, ri, GMP_RNDN);
4879
4880                 mpfr_t t3;
4881                 mpfr_init(t3);
4882                 mpfr_mul(t3, left_real, t, GMP_RNDN);
4883
4884                 mpfr_t t4;
4885                 mpfr_init(t4);
4886                 mpfr_mul(t4, left_imag, t2, GMP_RNDN);
4887
4888                 mpfr_add(t3, t3, t4, GMP_RNDN);
4889                 mpfr_set_ui(real, 0, GMP_RNDN);
4890                 mpfr_mul(real, real, t3, GMP_RNDN);
4891
4892                 mpfr_mul(t3, left_imag, t, GMP_RNDN);
4893                 mpfr_mul(t4, left_real, t2, GMP_RNDN);
4894                 mpfr_sub(t3, t3, t4, GMP_RNDN);
4895                 mpfr_set_ui(imag, 0, GMP_RNDN);
4896                 mpfr_mul(imag, imag, t3, GMP_RNDN);
4897
4898                 mpfr_clear(t2);
4899                 mpfr_clear(t3);
4900                 mpfr_clear(t4);
4901               }
4902           }
4903
4904         mpfr_clear(denom);
4905         mpfr_clear(rr);
4906         mpfr_clear(ri);
4907         mpfr_clear(t);
4908         mpfr_clear(rra);
4909         mpfr_clear(ria);
4910       }
4911       break;
4912     case OPERATOR_MOD:
4913       return false;
4914     case OPERATOR_LSHIFT:
4915     case OPERATOR_RSHIFT:
4916       return false;
4917     default:
4918       gcc_unreachable();
4919     }
4920
4921   Type* type = left_type;
4922   if (type == NULL)
4923     type = right_type;
4924   else if (type != right_type && right_type != NULL)
4925     {
4926       if (type->is_abstract())
4927         type = right_type;
4928       else if (!right_type->is_abstract())
4929         {
4930           // This looks like a type error which should be diagnosed
4931           // elsewhere.  Don't do anything here, to avoid an unhelpful
4932           // chain of error messages.
4933           return true;
4934         }
4935     }
4936
4937   if (type != NULL && !type->is_abstract())
4938     {
4939       if ((type != left_type
4940            && !Complex_expression::check_constant(left_real, left_imag,
4941                                                   type, location))
4942           || (type != right_type
4943               && !Complex_expression::check_constant(right_real, right_imag,
4944                                                      type, location))
4945           || !Complex_expression::check_constant(real, imag, type,
4946                                                  location))
4947         {
4948           mpfr_set_ui(real, 0, GMP_RNDN);
4949           mpfr_set_ui(imag, 0, GMP_RNDN);
4950         }
4951     }
4952
4953   return true;
4954 }
4955
4956 // Lower a binary expression.  We have to evaluate constant
4957 // expressions now, in order to implement Go's unlimited precision
4958 // constants.
4959
4960 Expression*
4961 Binary_expression::do_lower(Gogo*, Named_object*, int)
4962 {
4963   source_location location = this->location();
4964   Operator op = this->op_;
4965   Expression* left = this->left_;
4966   Expression* right = this->right_;
4967
4968   const bool is_comparison = (op == OPERATOR_EQEQ
4969                               || op == OPERATOR_NOTEQ
4970                               || op == OPERATOR_LT
4971                               || op == OPERATOR_LE
4972                               || op == OPERATOR_GT
4973                               || op == OPERATOR_GE);
4974
4975   // Integer constant expressions.
4976   {
4977     mpz_t left_val;
4978     mpz_init(left_val);
4979     Type* left_type;
4980     mpz_t right_val;
4981     mpz_init(right_val);
4982     Type* right_type;
4983     if (left->integer_constant_value(false, left_val, &left_type)
4984         && right->integer_constant_value(false, right_val, &right_type))
4985       {
4986         Expression* ret = NULL;
4987         if (left_type != right_type
4988             && left_type != NULL
4989             && right_type != NULL
4990             && left_type->base() != right_type->base()
4991             && op != OPERATOR_LSHIFT
4992             && op != OPERATOR_RSHIFT)
4993           {
4994             // May be a type error--let it be diagnosed later.
4995           }
4996         else if (is_comparison)
4997           {
4998             bool b = Binary_expression::compare_integer(op, left_val,
4999                                                         right_val);
5000             ret = Expression::make_cast(Type::lookup_bool_type(),
5001                                         Expression::make_boolean(b, location),
5002                                         location);
5003           }
5004         else
5005           {
5006             mpz_t val;
5007             mpz_init(val);
5008
5009             if (Binary_expression::eval_integer(op, left_type, left_val,
5010                                                 right_type, right_val,
5011                                                 location, val))
5012               {
5013                 gcc_assert(op != OPERATOR_OROR && op != OPERATOR_ANDAND);
5014                 Type* type;
5015                 if (op == OPERATOR_LSHIFT || op == OPERATOR_RSHIFT)
5016                   type = left_type;
5017                 else if (left_type == NULL)
5018                   type = right_type;
5019                 else if (right_type == NULL)
5020                   type = left_type;
5021                 else if (!left_type->is_abstract()
5022                          && left_type->named_type() != NULL)
5023                   type = left_type;
5024                 else if (!right_type->is_abstract()
5025                          && right_type->named_type() != NULL)
5026                   type = right_type;
5027                 else if (!left_type->is_abstract())
5028                   type = left_type;
5029                 else if (!right_type->is_abstract())
5030                   type = right_type;
5031                 else if (left_type->float_type() != NULL)
5032                   type = left_type;
5033                 else if (right_type->float_type() != NULL)
5034                   type = right_type;
5035                 else if (left_type->complex_type() != NULL)
5036                   type = left_type;
5037                 else if (right_type->complex_type() != NULL)
5038                   type = right_type;
5039                 else
5040                   type = left_type;
5041                 ret = Expression::make_integer(&val, type, location);
5042               }
5043
5044             mpz_clear(val);
5045           }
5046
5047         if (ret != NULL)
5048           {
5049             mpz_clear(right_val);
5050             mpz_clear(left_val);
5051             return ret;
5052           }
5053       }
5054     mpz_clear(right_val);
5055     mpz_clear(left_val);
5056   }
5057
5058   // Floating point constant expressions.
5059   {
5060     mpfr_t left_val;
5061     mpfr_init(left_val);
5062     Type* left_type;
5063     mpfr_t right_val;
5064     mpfr_init(right_val);
5065     Type* right_type;
5066     if (left->float_constant_value(left_val, &left_type)
5067         && right->float_constant_value(right_val, &right_type))
5068       {
5069         Expression* ret = NULL;
5070         if (left_type != right_type
5071             && left_type != NULL
5072             && right_type != NULL
5073             && left_type->base() != right_type->base()
5074             && op != OPERATOR_LSHIFT
5075             && op != OPERATOR_RSHIFT)
5076           {
5077             // May be a type error--let it be diagnosed later.
5078           }
5079         else if (is_comparison)
5080           {
5081             bool b = Binary_expression::compare_float(op,
5082                                                       (left_type != NULL
5083                                                        ? left_type
5084                                                        : right_type),
5085                                                       left_val, right_val);
5086             ret = Expression::make_boolean(b, location);
5087           }
5088         else
5089           {
5090             mpfr_t val;
5091             mpfr_init(val);
5092
5093             if (Binary_expression::eval_float(op, left_type, left_val,
5094                                               right_type, right_val, val,
5095                                               location))
5096               {
5097                 gcc_assert(op != OPERATOR_OROR && op != OPERATOR_ANDAND
5098                            && op != OPERATOR_LSHIFT && op != OPERATOR_RSHIFT);
5099                 Type* type;
5100                 if (left_type == NULL)
5101                   type = right_type;
5102                 else if (right_type == NULL)
5103                   type = left_type;
5104                 else if (!left_type->is_abstract()
5105                          && left_type->named_type() != NULL)
5106                   type = left_type;
5107                 else if (!right_type->is_abstract()
5108                          && right_type->named_type() != NULL)
5109                   type = right_type;
5110                 else if (!left_type->is_abstract())
5111                   type = left_type;
5112                 else if (!right_type->is_abstract())
5113                   type = right_type;
5114                 else if (left_type->float_type() != NULL)
5115                   type = left_type;
5116                 else if (right_type->float_type() != NULL)
5117                   type = right_type;
5118                 else
5119                   type = left_type;
5120                 ret = Expression::make_float(&val, type, location);
5121               }
5122
5123             mpfr_clear(val);
5124           }
5125
5126         if (ret != NULL)
5127           {
5128             mpfr_clear(right_val);
5129             mpfr_clear(left_val);
5130             return ret;
5131           }
5132       }
5133     mpfr_clear(right_val);
5134     mpfr_clear(left_val);
5135   }
5136
5137   // Complex constant expressions.
5138   {
5139     mpfr_t left_real;
5140     mpfr_t left_imag;
5141     mpfr_init(left_real);
5142     mpfr_init(left_imag);
5143     Type* left_type;
5144
5145     mpfr_t right_real;
5146     mpfr_t right_imag;
5147     mpfr_init(right_real);
5148     mpfr_init(right_imag);
5149     Type* right_type;
5150
5151     if (left->complex_constant_value(left_real, left_imag, &left_type)
5152         && right->complex_constant_value(right_real, right_imag, &right_type))
5153       {
5154         Expression* ret = NULL;
5155         if (left_type != right_type
5156             && left_type != NULL
5157             && right_type != NULL
5158             && left_type->base() != right_type->base())
5159           {
5160             // May be a type error--let it be diagnosed later.
5161           }
5162         else if (is_comparison)
5163           {
5164             bool b = Binary_expression::compare_complex(op,
5165                                                         (left_type != NULL
5166                                                          ? left_type
5167                                                          : right_type),
5168                                                         left_real,
5169                                                         left_imag,
5170                                                         right_real,
5171                                                         right_imag);
5172             ret = Expression::make_boolean(b, location);
5173           }
5174         else
5175           {
5176             mpfr_t real;
5177             mpfr_t imag;
5178             mpfr_init(real);
5179             mpfr_init(imag);
5180
5181             if (Binary_expression::eval_complex(op, left_type,
5182                                                 left_real, left_imag,
5183                                                 right_type,
5184                                                 right_real, right_imag,
5185                                                 real, imag,
5186                                                 location))
5187               {
5188                 gcc_assert(op != OPERATOR_OROR && op != OPERATOR_ANDAND
5189                            && op != OPERATOR_LSHIFT && op != OPERATOR_RSHIFT);
5190                 Type* type;
5191                 if (left_type == NULL)
5192                   type = right_type;
5193                 else if (right_type == NULL)
5194                   type = left_type;
5195                 else if (!left_type->is_abstract()
5196                          && left_type->named_type() != NULL)
5197                   type = left_type;
5198                 else if (!right_type->is_abstract()
5199                          && right_type->named_type() != NULL)
5200                   type = right_type;
5201                 else if (!left_type->is_abstract())
5202                   type = left_type;
5203                 else if (!right_type->is_abstract())
5204                   type = right_type;
5205                 else if (left_type->complex_type() != NULL)
5206                   type = left_type;
5207                 else if (right_type->complex_type() != NULL)
5208                   type = right_type;
5209                 else
5210                   type = left_type;
5211                 ret = Expression::make_complex(&real, &imag, type,
5212                                                location);
5213               }
5214             mpfr_clear(real);
5215             mpfr_clear(imag);
5216           }
5217
5218         if (ret != NULL)
5219           {
5220             mpfr_clear(left_real);
5221             mpfr_clear(left_imag);
5222             mpfr_clear(right_real);
5223             mpfr_clear(right_imag);
5224             return ret;
5225           }
5226       }
5227
5228     mpfr_clear(left_real);
5229     mpfr_clear(left_imag);
5230     mpfr_clear(right_real);
5231     mpfr_clear(right_imag);
5232   }
5233
5234   // String constant expressions.
5235   if (op == OPERATOR_PLUS
5236       && left->type()->is_string_type()
5237       && right->type()->is_string_type())
5238     {
5239       std::string left_string;
5240       std::string right_string;
5241       if (left->string_constant_value(&left_string)
5242           && right->string_constant_value(&right_string))
5243         return Expression::make_string(left_string + right_string, location);
5244     }
5245
5246   return this;
5247 }
5248
5249 // Return the integer constant value, if it has one.
5250
5251 bool
5252 Binary_expression::do_integer_constant_value(bool iota_is_constant, mpz_t val,
5253                                              Type** ptype) const
5254 {
5255   mpz_t left_val;
5256   mpz_init(left_val);
5257   Type* left_type;
5258   if (!this->left_->integer_constant_value(iota_is_constant, left_val,
5259                                            &left_type))
5260     {
5261       mpz_clear(left_val);
5262       return false;
5263     }
5264
5265   mpz_t right_val;
5266   mpz_init(right_val);
5267   Type* right_type;
5268   if (!this->right_->integer_constant_value(iota_is_constant, right_val,
5269                                             &right_type))
5270     {
5271       mpz_clear(right_val);
5272       mpz_clear(left_val);
5273       return false;
5274     }
5275
5276   bool ret;
5277   if (left_type != right_type
5278       && left_type != NULL
5279       && right_type != NULL
5280       && left_type->base() != right_type->base()
5281       && this->op_ != OPERATOR_RSHIFT
5282       && this->op_ != OPERATOR_LSHIFT)
5283     ret = false;
5284   else
5285     ret = Binary_expression::eval_integer(this->op_, left_type, left_val,
5286                                           right_type, right_val,
5287                                           this->location(), val);
5288
5289   mpz_clear(right_val);
5290   mpz_clear(left_val);
5291
5292   if (ret)
5293     *ptype = left_type;
5294
5295   return ret;
5296 }
5297
5298 // Return the floating point constant value, if it has one.
5299
5300 bool
5301 Binary_expression::do_float_constant_value(mpfr_t val, Type** ptype) const
5302 {
5303   mpfr_t left_val;
5304   mpfr_init(left_val);
5305   Type* left_type;
5306   if (!this->left_->float_constant_value(left_val, &left_type))
5307     {
5308       mpfr_clear(left_val);
5309       return false;
5310     }
5311
5312   mpfr_t right_val;
5313   mpfr_init(right_val);
5314   Type* right_type;
5315   if (!this->right_->float_constant_value(right_val, &right_type))
5316     {
5317       mpfr_clear(right_val);
5318       mpfr_clear(left_val);
5319       return false;
5320     }
5321
5322   bool ret;
5323   if (left_type != right_type
5324       && left_type != NULL
5325       && right_type != NULL
5326       && left_type->base() != right_type->base())
5327     ret = false;
5328   else
5329     ret = Binary_expression::eval_float(this->op_, left_type, left_val,
5330                                         right_type, right_val,
5331                                         val, this->location());
5332
5333   mpfr_clear(left_val);
5334   mpfr_clear(right_val);
5335
5336   if (ret)
5337     *ptype = left_type;
5338
5339   return ret;
5340 }
5341
5342 // Return the complex constant value, if it has one.
5343
5344 bool
5345 Binary_expression::do_complex_constant_value(mpfr_t real, mpfr_t imag,
5346                                              Type** ptype) const
5347 {
5348   mpfr_t left_real;
5349   mpfr_t left_imag;
5350   mpfr_init(left_real);
5351   mpfr_init(left_imag);
5352   Type* left_type;
5353   if (!this->left_->complex_constant_value(left_real, left_imag, &left_type))
5354     {
5355       mpfr_clear(left_real);
5356       mpfr_clear(left_imag);
5357       return false;
5358     }
5359
5360   mpfr_t right_real;
5361   mpfr_t right_imag;
5362   mpfr_init(right_real);
5363   mpfr_init(right_imag);
5364   Type* right_type;
5365   if (!this->right_->complex_constant_value(right_real, right_imag,
5366                                             &right_type))
5367     {
5368       mpfr_clear(left_real);
5369       mpfr_clear(left_imag);
5370       mpfr_clear(right_real);
5371       mpfr_clear(right_imag);
5372       return false;
5373     }
5374
5375   bool ret;
5376   if (left_type != right_type
5377       && left_type != NULL
5378       && right_type != NULL
5379       && left_type->base() != right_type->base())
5380     ret = false;
5381   else
5382     ret = Binary_expression::eval_complex(this->op_, left_type,
5383                                           left_real, left_imag,
5384                                           right_type,
5385                                           right_real, right_imag,
5386                                           real, imag,
5387                                           this->location());
5388   mpfr_clear(left_real);
5389   mpfr_clear(left_imag);
5390   mpfr_clear(right_real);
5391   mpfr_clear(right_imag);
5392
5393   if (ret)
5394     *ptype = left_type;
5395
5396   return ret;
5397 }
5398
5399 // Note that the value is being discarded.
5400
5401 void
5402 Binary_expression::do_discarding_value()
5403 {
5404   if (this->op_ == OPERATOR_OROR || this->op_ == OPERATOR_ANDAND)
5405     this->right_->discarding_value();
5406   else
5407     this->warn_about_unused_value();
5408 }
5409
5410 // Get type.
5411
5412 Type*
5413 Binary_expression::do_type()
5414 {
5415   switch (this->op_)
5416     {
5417     case OPERATOR_OROR:
5418     case OPERATOR_ANDAND:
5419     case OPERATOR_EQEQ:
5420     case OPERATOR_NOTEQ:
5421     case OPERATOR_LT:
5422     case OPERATOR_LE:
5423     case OPERATOR_GT:
5424     case OPERATOR_GE:
5425       return Type::lookup_bool_type();
5426
5427     case OPERATOR_PLUS:
5428     case OPERATOR_MINUS:
5429     case OPERATOR_OR:
5430     case OPERATOR_XOR:
5431     case OPERATOR_MULT:
5432     case OPERATOR_DIV:
5433     case OPERATOR_MOD:
5434     case OPERATOR_AND:
5435     case OPERATOR_BITCLEAR:
5436       {
5437         Type* left_type = this->left_->type();
5438         Type* right_type = this->right_->type();
5439         if (left_type->is_error_type())
5440           return left_type;
5441         else if (right_type->is_error_type())
5442           return right_type;
5443         else if (!left_type->is_abstract() && left_type->named_type() != NULL)
5444           return left_type;
5445         else if (!right_type->is_abstract() && right_type->named_type() != NULL)
5446           return right_type;
5447         else if (!left_type->is_abstract())
5448           return left_type;
5449         else if (!right_type->is_abstract())
5450           return right_type;
5451         else if (left_type->complex_type() != NULL)
5452           return left_type;
5453         else if (right_type->complex_type() != NULL)
5454           return right_type;
5455         else if (left_type->float_type() != NULL)
5456           return left_type;
5457         else if (right_type->float_type() != NULL)
5458           return right_type;
5459         else
5460           return left_type;
5461       }
5462
5463     case OPERATOR_LSHIFT:
5464     case OPERATOR_RSHIFT:
5465       return this->left_->type();
5466
5467     default:
5468       gcc_unreachable();
5469     }
5470 }
5471
5472 // Set type for a binary expression.
5473
5474 void
5475 Binary_expression::do_determine_type(const Type_context* context)
5476 {
5477   Type* tleft = this->left_->type();
5478   Type* tright = this->right_->type();
5479
5480   // Both sides should have the same type, except for the shift
5481   // operations.  For a comparison, we should ignore the incoming
5482   // type.
5483
5484   bool is_shift_op = (this->op_ == OPERATOR_LSHIFT
5485                       || this->op_ == OPERATOR_RSHIFT);
5486
5487   bool is_comparison = (this->op_ == OPERATOR_EQEQ
5488                         || this->op_ == OPERATOR_NOTEQ
5489                         || this->op_ == OPERATOR_LT
5490                         || this->op_ == OPERATOR_LE
5491                         || this->op_ == OPERATOR_GT
5492                         || this->op_ == OPERATOR_GE);
5493
5494   Type_context subcontext(*context);
5495
5496   if (is_comparison)
5497     {
5498       // In a comparison, the context does not determine the types of
5499       // the operands.
5500       subcontext.type = NULL;
5501     }
5502
5503   // Set the context for the left hand operand.
5504   if (is_shift_op)
5505     {
5506       // The right hand operand plays no role in determining the type
5507       // of the left hand operand.  A shift of an abstract integer in
5508       // a string context gets special treatment, which may be a
5509       // language bug.
5510       if (subcontext.type != NULL
5511           && subcontext.type->is_string_type()
5512           && tleft->is_abstract())
5513         error_at(this->location(), "shift of non-integer operand");
5514     }
5515   else if (!tleft->is_abstract())
5516     subcontext.type = tleft;
5517   else if (!tright->is_abstract())
5518     subcontext.type = tright;
5519   else if (subcontext.type == NULL)
5520     {
5521       if ((tleft->integer_type() != NULL && tright->integer_type() != NULL)
5522           || (tleft->float_type() != NULL && tright->float_type() != NULL)
5523           || (tleft->complex_type() != NULL && tright->complex_type() != NULL))
5524         {
5525           // Both sides have an abstract integer, abstract float, or
5526           // abstract complex type.  Just let CONTEXT determine
5527           // whether they may remain abstract or not.
5528         }
5529       else if (tleft->complex_type() != NULL)
5530         subcontext.type = tleft;
5531       else if (tright->complex_type() != NULL)
5532         subcontext.type = tright;
5533       else if (tleft->float_type() != NULL)
5534         subcontext.type = tleft;
5535       else if (tright->float_type() != NULL)
5536         subcontext.type = tright;
5537       else
5538         subcontext.type = tleft;
5539     }
5540
5541   this->left_->determine_type(&subcontext);
5542
5543   // The context for the right hand operand is the same as for the
5544   // left hand operand, except for a shift operator.
5545   if (is_shift_op)
5546     {
5547       subcontext.type = Type::lookup_integer_type("uint");
5548       subcontext.may_be_abstract = false;
5549     }
5550
5551   this->right_->determine_type(&subcontext);
5552 }
5553
5554 // Report an error if the binary operator OP does not support TYPE.
5555 // Return whether the operation is OK.  This should not be used for
5556 // shift.
5557
5558 bool
5559 Binary_expression::check_operator_type(Operator op, Type* type,
5560                                        source_location location)
5561 {
5562   switch (op)
5563     {
5564     case OPERATOR_OROR:
5565     case OPERATOR_ANDAND:
5566       if (!type->is_boolean_type())
5567         {
5568           error_at(location, "expected boolean type");
5569           return false;
5570         }
5571       break;
5572
5573     case OPERATOR_EQEQ:
5574     case OPERATOR_NOTEQ:
5575       if (type->integer_type() == NULL
5576           && type->float_type() == NULL
5577           && type->complex_type() == NULL
5578           && !type->is_string_type()
5579           && type->points_to() == NULL
5580           && !type->is_nil_type()
5581           && !type->is_boolean_type()
5582           && type->interface_type() == NULL
5583           && (type->array_type() == NULL
5584               || type->array_type()->length() != NULL)
5585           && type->map_type() == NULL
5586           && type->channel_type() == NULL
5587           && type->function_type() == NULL)
5588         {
5589           error_at(location,
5590                    ("expected integer, floating, complex, string, pointer, "
5591                     "boolean, interface, slice, map, channel, "
5592                     "or function type"));
5593           return false;
5594         }
5595       break;
5596
5597     case OPERATOR_LT:
5598     case OPERATOR_LE:
5599     case OPERATOR_GT:
5600     case OPERATOR_GE:
5601       if (type->integer_type() == NULL
5602           && type->float_type() == NULL
5603           && !type->is_string_type())
5604         {
5605           error_at(location, "expected integer, floating, or string type");
5606           return false;
5607         }
5608       break;
5609
5610     case OPERATOR_PLUS:
5611     case OPERATOR_PLUSEQ:
5612       if (type->integer_type() == NULL
5613           && type->float_type() == NULL
5614           && type->complex_type() == NULL
5615           && !type->is_string_type())
5616         {
5617           error_at(location,
5618                    "expected integer, floating, complex, or string type");
5619           return false;
5620         }
5621       break;
5622
5623     case OPERATOR_MINUS:
5624     case OPERATOR_MINUSEQ:
5625     case OPERATOR_MULT:
5626     case OPERATOR_MULTEQ:
5627     case OPERATOR_DIV:
5628     case OPERATOR_DIVEQ:
5629       if (type->integer_type() == NULL
5630           && type->float_type() == NULL
5631           && type->complex_type() == NULL)
5632         {
5633           error_at(location, "expected integer, floating, or complex type");
5634           return false;
5635         }
5636       break;
5637
5638     case OPERATOR_MOD:
5639     case OPERATOR_MODEQ:
5640     case OPERATOR_OR:
5641     case OPERATOR_OREQ:
5642     case OPERATOR_AND:
5643     case OPERATOR_ANDEQ:
5644     case OPERATOR_XOR:
5645     case OPERATOR_XOREQ:
5646     case OPERATOR_BITCLEAR:
5647     case OPERATOR_BITCLEAREQ:
5648       if (type->integer_type() == NULL)
5649         {
5650           error_at(location, "expected integer type");
5651           return false;
5652         }
5653       break;
5654
5655     default:
5656       gcc_unreachable();
5657     }
5658
5659   return true;
5660 }
5661
5662 // Check types.
5663
5664 void
5665 Binary_expression::do_check_types(Gogo*)
5666 {
5667   Type* left_type = this->left_->type();
5668   Type* right_type = this->right_->type();
5669   if (left_type->is_error_type() || right_type->is_error_type())
5670     {
5671       this->set_is_error();
5672       return;
5673     }
5674
5675   if (this->op_ == OPERATOR_EQEQ
5676       || this->op_ == OPERATOR_NOTEQ
5677       || this->op_ == OPERATOR_LT
5678       || this->op_ == OPERATOR_LE
5679       || this->op_ == OPERATOR_GT
5680       || this->op_ == OPERATOR_GE)
5681     {
5682       if (!Type::are_assignable(left_type, right_type, NULL)
5683           && !Type::are_assignable(right_type, left_type, NULL))
5684         {
5685           this->report_error(_("incompatible types in binary expression"));
5686           return;
5687         }
5688       if (!Binary_expression::check_operator_type(this->op_, left_type,
5689                                                   this->location())
5690           || !Binary_expression::check_operator_type(this->op_, right_type,
5691                                                      this->location()))
5692         {
5693           this->set_is_error();
5694           return;
5695         }
5696     }
5697   else if (this->op_ != OPERATOR_LSHIFT && this->op_ != OPERATOR_RSHIFT)
5698     {
5699       if (!Type::are_compatible_for_binop(left_type, right_type))
5700         {
5701           this->report_error(_("incompatible types in binary expression"));
5702           return;
5703         }
5704       if (!Binary_expression::check_operator_type(this->op_, left_type,
5705                                                   this->location()))
5706         {
5707           this->set_is_error();
5708           return;
5709         }
5710     }
5711   else
5712     {
5713       if (left_type->integer_type() == NULL)
5714         this->report_error(_("shift of non-integer operand"));
5715
5716       if (!right_type->is_abstract()
5717           && (right_type->integer_type() == NULL
5718               || !right_type->integer_type()->is_unsigned()))
5719         this->report_error(_("shift count not unsigned integer"));
5720       else
5721         {
5722           mpz_t val;
5723           mpz_init(val);
5724           Type* type;
5725           if (this->right_->integer_constant_value(true, val, &type))
5726             {
5727               if (mpz_sgn(val) < 0)
5728                 this->report_error(_("negative shift count"));
5729             }
5730           mpz_clear(val);
5731         }
5732     }
5733 }
5734
5735 // Get a tree for a binary expression.
5736
5737 tree
5738 Binary_expression::do_get_tree(Translate_context* context)
5739 {
5740   tree left = this->left_->get_tree(context);
5741   tree right = this->right_->get_tree(context);
5742
5743   if (left == error_mark_node || right == error_mark_node)
5744     return error_mark_node;
5745
5746   enum tree_code code;
5747   bool use_left_type = true;
5748   bool is_shift_op = false;
5749   switch (this->op_)
5750     {
5751     case OPERATOR_EQEQ:
5752     case OPERATOR_NOTEQ:
5753     case OPERATOR_LT:
5754     case OPERATOR_LE:
5755     case OPERATOR_GT:
5756     case OPERATOR_GE:
5757       return Expression::comparison_tree(context, this->op_,
5758                                          this->left_->type(), left,
5759                                          this->right_->type(), right,
5760                                          this->location());
5761
5762     case OPERATOR_OROR:
5763       code = TRUTH_ORIF_EXPR;
5764       use_left_type = false;
5765       break;
5766     case OPERATOR_ANDAND:
5767       code = TRUTH_ANDIF_EXPR;
5768       use_left_type = false;
5769       break;
5770     case OPERATOR_PLUS:
5771       code = PLUS_EXPR;
5772       break;
5773     case OPERATOR_MINUS:
5774       code = MINUS_EXPR;
5775       break;
5776     case OPERATOR_OR:
5777       code = BIT_IOR_EXPR;
5778       break;
5779     case OPERATOR_XOR:
5780       code = BIT_XOR_EXPR;
5781       break;
5782     case OPERATOR_MULT:
5783       code = MULT_EXPR;
5784       break;
5785     case OPERATOR_DIV:
5786       {
5787         Type *t = this->left_->type();
5788         if (t->float_type() != NULL || t->complex_type() != NULL)
5789           code = RDIV_EXPR;
5790         else
5791           code = TRUNC_DIV_EXPR;
5792       }
5793       break;
5794     case OPERATOR_MOD:
5795       code = TRUNC_MOD_EXPR;
5796       break;
5797     case OPERATOR_LSHIFT:
5798       code = LSHIFT_EXPR;
5799       is_shift_op = true;
5800       break;
5801     case OPERATOR_RSHIFT:
5802       code = RSHIFT_EXPR;
5803       is_shift_op = true;
5804       break;
5805     case OPERATOR_AND:
5806       code = BIT_AND_EXPR;
5807       break;
5808     case OPERATOR_BITCLEAR:
5809       right = fold_build1(BIT_NOT_EXPR, TREE_TYPE(right), right);
5810       code = BIT_AND_EXPR;
5811       break;
5812     default:
5813       gcc_unreachable();
5814     }
5815
5816   tree type = use_left_type ? TREE_TYPE(left) : TREE_TYPE(right);
5817
5818   if (this->left_->type()->is_string_type())
5819     {
5820       gcc_assert(this->op_ == OPERATOR_PLUS);
5821       tree string_type = Type::make_string_type()->get_tree(context->gogo());
5822       static tree string_plus_decl;
5823       return Gogo::call_builtin(&string_plus_decl,
5824                                 this->location(),
5825                                 "__go_string_plus",
5826                                 2,
5827                                 string_type,
5828                                 string_type,
5829                                 left,
5830                                 string_type,
5831                                 right);
5832     }
5833
5834   tree compute_type = excess_precision_type(type);
5835   if (compute_type != NULL_TREE)
5836     {
5837       left = ::convert(compute_type, left);
5838       right = ::convert(compute_type, right);
5839     }
5840
5841   tree eval_saved = NULL_TREE;
5842   if (is_shift_op)
5843     {
5844       if (!DECL_P(left))
5845         left = save_expr(left);
5846       if (!DECL_P(right))
5847         right = save_expr(right);
5848       // Make sure the values are evaluated.
5849       eval_saved = fold_build2_loc(this->location(), COMPOUND_EXPR,
5850                                    void_type_node, left, right);
5851     }
5852
5853   tree ret = fold_build2_loc(this->location(),
5854                              code,
5855                              compute_type != NULL_TREE ? compute_type : type,
5856                              left, right);
5857
5858   if (compute_type != NULL_TREE)
5859     ret = ::convert(type, ret);
5860
5861   // In Go, a shift larger than the size of the type is well-defined.
5862   // This is not true in GENERIC, so we need to insert a conditional.
5863   if (is_shift_op)
5864     {
5865       gcc_assert(INTEGRAL_TYPE_P(TREE_TYPE(left)));
5866       gcc_assert(this->left_->type()->integer_type() != NULL);
5867       int bits = TYPE_PRECISION(TREE_TYPE(left));
5868
5869       tree compare = fold_build2(LT_EXPR, boolean_type_node, right,
5870                                  build_int_cst_type(TREE_TYPE(right), bits));
5871
5872       tree overflow_result = fold_convert_loc(this->location(),
5873                                               TREE_TYPE(left),
5874                                               integer_zero_node);
5875       if (this->op_ == OPERATOR_RSHIFT
5876           && !this->left_->type()->integer_type()->is_unsigned())
5877         {
5878           tree neg = fold_build2_loc(this->location(), LT_EXPR,
5879                                      boolean_type_node, left,
5880                                      fold_convert_loc(this->location(),
5881                                                       TREE_TYPE(left),
5882                                                       integer_zero_node));
5883           tree neg_one = fold_build2_loc(this->location(),
5884                                          MINUS_EXPR, TREE_TYPE(left),
5885                                          fold_convert_loc(this->location(),
5886                                                           TREE_TYPE(left),
5887                                                           integer_zero_node),
5888                                          fold_convert_loc(this->location(),
5889                                                           TREE_TYPE(left),
5890                                                           integer_one_node));
5891           overflow_result = fold_build3_loc(this->location(), COND_EXPR,
5892                                             TREE_TYPE(left), neg, neg_one,
5893                                             overflow_result);
5894         }
5895
5896       ret = fold_build3_loc(this->location(), COND_EXPR, TREE_TYPE(left),
5897                             compare, ret, overflow_result);
5898
5899       ret = fold_build2_loc(this->location(), COMPOUND_EXPR,
5900                             TREE_TYPE(ret), eval_saved, ret);
5901     }
5902
5903   return ret;
5904 }
5905
5906 // Export a binary expression.
5907
5908 void
5909 Binary_expression::do_export(Export* exp) const
5910 {
5911   exp->write_c_string("(");
5912   this->left_->export_expression(exp);
5913   switch (this->op_)
5914     {
5915     case OPERATOR_OROR:
5916       exp->write_c_string(" || ");
5917       break;
5918     case OPERATOR_ANDAND:
5919       exp->write_c_string(" && ");
5920       break;
5921     case OPERATOR_EQEQ:
5922       exp->write_c_string(" == ");
5923       break;
5924     case OPERATOR_NOTEQ:
5925       exp->write_c_string(" != ");
5926       break;
5927     case OPERATOR_LT:
5928       exp->write_c_string(" < ");
5929       break;
5930     case OPERATOR_LE:
5931       exp->write_c_string(" <= ");
5932       break;
5933     case OPERATOR_GT:
5934       exp->write_c_string(" > ");
5935       break;
5936     case OPERATOR_GE:
5937       exp->write_c_string(" >= ");
5938       break;
5939     case OPERATOR_PLUS:
5940       exp->write_c_string(" + ");
5941       break;
5942     case OPERATOR_MINUS:
5943       exp->write_c_string(" - ");
5944       break;
5945     case OPERATOR_OR:
5946       exp->write_c_string(" | ");
5947       break;
5948     case OPERATOR_XOR:
5949       exp->write_c_string(" ^ ");
5950       break;
5951     case OPERATOR_MULT:
5952       exp->write_c_string(" * ");
5953       break;
5954     case OPERATOR_DIV:
5955       exp->write_c_string(" / ");
5956       break;
5957     case OPERATOR_MOD:
5958       exp->write_c_string(" % ");
5959       break;
5960     case OPERATOR_LSHIFT:
5961       exp->write_c_string(" << ");
5962       break;
5963     case OPERATOR_RSHIFT:
5964       exp->write_c_string(" >> ");
5965       break;
5966     case OPERATOR_AND:
5967       exp->write_c_string(" & ");
5968       break;
5969     case OPERATOR_BITCLEAR:
5970       exp->write_c_string(" &^ ");
5971       break;
5972     default:
5973       gcc_unreachable();
5974     }
5975   this->right_->export_expression(exp);
5976   exp->write_c_string(")");
5977 }
5978
5979 // Import a binary expression.
5980
5981 Expression*
5982 Binary_expression::do_import(Import* imp)
5983 {
5984   imp->require_c_string("(");
5985
5986   Expression* left = Expression::import_expression(imp);
5987
5988   Operator op;
5989   if (imp->match_c_string(" || "))
5990     {
5991       op = OPERATOR_OROR;
5992       imp->advance(4);
5993     }
5994   else if (imp->match_c_string(" && "))
5995     {
5996       op = OPERATOR_ANDAND;
5997       imp->advance(4);
5998     }
5999   else if (imp->match_c_string(" == "))
6000     {
6001       op = OPERATOR_EQEQ;
6002       imp->advance(4);
6003     }
6004   else if (imp->match_c_string(" != "))
6005     {
6006       op = OPERATOR_NOTEQ;
6007       imp->advance(4);
6008     }
6009   else if (imp->match_c_string(" < "))
6010     {
6011       op = OPERATOR_LT;
6012       imp->advance(3);
6013     }
6014   else if (imp->match_c_string(" <= "))
6015     {
6016       op = OPERATOR_LE;
6017       imp->advance(4);
6018     }
6019   else if (imp->match_c_string(" > "))
6020     {
6021       op = OPERATOR_GT;
6022       imp->advance(3);
6023     }
6024   else if (imp->match_c_string(" >= "))
6025     {
6026       op = OPERATOR_GE;
6027       imp->advance(4);
6028     }
6029   else if (imp->match_c_string(" + "))
6030     {
6031       op = OPERATOR_PLUS;
6032       imp->advance(3);
6033     }
6034   else if (imp->match_c_string(" - "))
6035     {
6036       op = OPERATOR_MINUS;
6037       imp->advance(3);
6038     }
6039   else if (imp->match_c_string(" | "))
6040     {
6041       op = OPERATOR_OR;
6042       imp->advance(3);
6043     }
6044   else if (imp->match_c_string(" ^ "))
6045     {
6046       op = OPERATOR_XOR;
6047       imp->advance(3);
6048     }
6049   else if (imp->match_c_string(" * "))
6050     {
6051       op = OPERATOR_MULT;
6052       imp->advance(3);
6053     }
6054   else if (imp->match_c_string(" / "))
6055     {
6056       op = OPERATOR_DIV;
6057       imp->advance(3);
6058     }
6059   else if (imp->match_c_string(" % "))
6060     {
6061       op = OPERATOR_MOD;
6062       imp->advance(3);
6063     }
6064   else if (imp->match_c_string(" << "))
6065     {
6066       op = OPERATOR_LSHIFT;
6067       imp->advance(4);
6068     }
6069   else if (imp->match_c_string(" >> "))
6070     {
6071       op = OPERATOR_RSHIFT;
6072       imp->advance(4);
6073     }
6074   else if (imp->match_c_string(" & "))
6075     {
6076       op = OPERATOR_AND;
6077       imp->advance(3);
6078     }
6079   else if (imp->match_c_string(" &^ "))
6080     {
6081       op = OPERATOR_BITCLEAR;
6082       imp->advance(4);
6083     }
6084   else
6085     {
6086       error_at(imp->location(), "unrecognized binary operator");
6087       return Expression::make_error(imp->location());
6088     }
6089
6090   Expression* right = Expression::import_expression(imp);
6091
6092   imp->require_c_string(")");
6093
6094   return Expression::make_binary(op, left, right, imp->location());
6095 }
6096
6097 // Make a binary expression.
6098
6099 Expression*
6100 Expression::make_binary(Operator op, Expression* left, Expression* right,
6101                         source_location location)
6102 {
6103   return new Binary_expression(op, left, right, location);
6104 }
6105
6106 // Implement a comparison.
6107
6108 tree
6109 Expression::comparison_tree(Translate_context* context, Operator op,
6110                             Type* left_type, tree left_tree,
6111                             Type* right_type, tree right_tree,
6112                             source_location location)
6113 {
6114   enum tree_code code;
6115   switch (op)
6116     {
6117     case OPERATOR_EQEQ:
6118       code = EQ_EXPR;
6119       break;
6120     case OPERATOR_NOTEQ:
6121       code = NE_EXPR;
6122       break;
6123     case OPERATOR_LT:
6124       code = LT_EXPR;
6125       break;
6126     case OPERATOR_LE:
6127       code = LE_EXPR;
6128       break;
6129     case OPERATOR_GT:
6130       code = GT_EXPR;
6131       break;
6132     case OPERATOR_GE:
6133       code = GE_EXPR;
6134       break;
6135     default:
6136       gcc_unreachable();
6137     }
6138
6139   if (left_type->is_string_type() && right_type->is_string_type())
6140     {
6141       tree string_type = Type::make_string_type()->get_tree(context->gogo());
6142       static tree string_compare_decl;
6143       left_tree = Gogo::call_builtin(&string_compare_decl,
6144                                      location,
6145                                      "__go_strcmp",
6146                                      2,
6147                                      integer_type_node,
6148                                      string_type,
6149                                      left_tree,
6150                                      string_type,
6151                                      right_tree);
6152       right_tree = build_int_cst_type(integer_type_node, 0);
6153     }
6154   else if ((left_type->interface_type() != NULL
6155             && right_type->interface_type() == NULL
6156             && !right_type->is_nil_type())
6157            || (left_type->interface_type() == NULL
6158                && !left_type->is_nil_type()
6159                && right_type->interface_type() != NULL))
6160     {
6161       // Comparing an interface value to a non-interface value.
6162       if (left_type->interface_type() == NULL)
6163         {
6164           std::swap(left_type, right_type);
6165           std::swap(left_tree, right_tree);
6166         }
6167
6168       // The right operand is not an interface.  We need to take its
6169       // address if it is not a pointer.
6170       tree make_tmp;
6171       tree arg;
6172       if (right_type->points_to() != NULL)
6173         {
6174           make_tmp = NULL_TREE;
6175           arg = right_tree;
6176         }
6177       else if (TREE_ADDRESSABLE(TREE_TYPE(right_tree)) || DECL_P(right_tree))
6178         {
6179           make_tmp = NULL_TREE;
6180           arg = build_fold_addr_expr_loc(location, right_tree);
6181           if (DECL_P(right_tree))
6182             TREE_ADDRESSABLE(right_tree) = 1;
6183         }
6184       else
6185         {
6186           tree tmp = create_tmp_var(TREE_TYPE(right_tree),
6187                                     get_name(right_tree));
6188           DECL_IGNORED_P(tmp) = 0;
6189           DECL_INITIAL(tmp) = right_tree;
6190           TREE_ADDRESSABLE(tmp) = 1;
6191           make_tmp = build1(DECL_EXPR, void_type_node, tmp);
6192           SET_EXPR_LOCATION(make_tmp, location);
6193           arg = build_fold_addr_expr_loc(location, tmp);
6194         }
6195       arg = fold_convert_loc(location, ptr_type_node, arg);
6196
6197       tree descriptor = right_type->type_descriptor_pointer(context->gogo());
6198
6199       if (left_type->interface_type()->is_empty())
6200         {
6201           static tree empty_interface_value_compare_decl;
6202           left_tree = Gogo::call_builtin(&empty_interface_value_compare_decl,
6203                                          location,
6204                                          "__go_empty_interface_value_compare",
6205                                          3,
6206                                          integer_type_node,
6207                                          TREE_TYPE(left_tree),
6208                                          left_tree,
6209                                          TREE_TYPE(descriptor),
6210                                          descriptor,
6211                                          ptr_type_node,
6212                                          arg);
6213           if (left_tree == error_mark_node)
6214             return error_mark_node;
6215           // This can panic if the type is not comparable.
6216           TREE_NOTHROW(empty_interface_value_compare_decl) = 0;
6217         }
6218       else
6219         {
6220           static tree interface_value_compare_decl;
6221           left_tree = Gogo::call_builtin(&interface_value_compare_decl,
6222                                          location,
6223                                          "__go_interface_value_compare",
6224                                          3,
6225                                          integer_type_node,
6226                                          TREE_TYPE(left_tree),
6227                                          left_tree,
6228                                          TREE_TYPE(descriptor),
6229                                          descriptor,
6230                                          ptr_type_node,
6231                                          arg);
6232           if (left_tree == error_mark_node)
6233             return error_mark_node;
6234           // This can panic if the type is not comparable.
6235           TREE_NOTHROW(interface_value_compare_decl) = 0;
6236         }
6237       right_tree = build_int_cst_type(integer_type_node, 0);
6238
6239       if (make_tmp != NULL_TREE)
6240         left_tree = build2(COMPOUND_EXPR, TREE_TYPE(left_tree), make_tmp,
6241                            left_tree);
6242     }
6243   else if (left_type->interface_type() != NULL
6244            && right_type->interface_type() != NULL)
6245     {
6246       if (left_type->interface_type()->is_empty())
6247         {
6248           gcc_assert(right_type->interface_type()->is_empty());
6249           static tree empty_interface_compare_decl;
6250           left_tree = Gogo::call_builtin(&empty_interface_compare_decl,
6251                                          location,
6252                                          "__go_empty_interface_compare",
6253                                          2,
6254                                          integer_type_node,
6255                                          TREE_TYPE(left_tree),
6256                                          left_tree,
6257                                          TREE_TYPE(right_tree),
6258                                          right_tree);
6259           if (left_tree == error_mark_node)
6260             return error_mark_node;
6261           // This can panic if the type is uncomparable.
6262           TREE_NOTHROW(empty_interface_compare_decl) = 0;
6263         }
6264       else
6265         {
6266           gcc_assert(!right_type->interface_type()->is_empty());
6267           static tree interface_compare_decl;
6268           left_tree = Gogo::call_builtin(&interface_compare_decl,
6269                                          location,
6270                                          "__go_interface_compare",
6271                                          2,
6272                                          integer_type_node,
6273                                          TREE_TYPE(left_tree),
6274                                          left_tree,
6275                                          TREE_TYPE(right_tree),
6276                                          right_tree);
6277           if (left_tree == error_mark_node)
6278             return error_mark_node;
6279           // This can panic if the type is uncomparable.
6280           TREE_NOTHROW(interface_compare_decl) = 0;
6281         }
6282       right_tree = build_int_cst_type(integer_type_node, 0);
6283     }
6284
6285   if (left_type->is_nil_type()
6286       && (op == OPERATOR_EQEQ || op == OPERATOR_NOTEQ))
6287     {
6288       std::swap(left_type, right_type);
6289       std::swap(left_tree, right_tree);
6290     }
6291
6292   if (right_type->is_nil_type())
6293     {
6294       if (left_type->array_type() != NULL
6295           && left_type->array_type()->length() == NULL)
6296         {
6297           Array_type* at = left_type->array_type();
6298           left_tree = at->value_pointer_tree(context->gogo(), left_tree);
6299           right_tree = fold_convert(TREE_TYPE(left_tree), null_pointer_node);
6300         }
6301       else if (left_type->interface_type() != NULL)
6302         {
6303           // An interface is nil if the first field is nil.
6304           tree left_type_tree = TREE_TYPE(left_tree);
6305           gcc_assert(TREE_CODE(left_type_tree) == RECORD_TYPE);
6306           tree field = TYPE_FIELDS(left_type_tree);
6307           left_tree = build3(COMPONENT_REF, TREE_TYPE(field), left_tree,
6308                              field, NULL_TREE);
6309           right_tree = fold_convert(TREE_TYPE(left_tree), null_pointer_node);
6310         }
6311       else
6312         {
6313           gcc_assert(POINTER_TYPE_P(TREE_TYPE(left_tree)));
6314           right_tree = fold_convert(TREE_TYPE(left_tree), null_pointer_node);
6315         }
6316     }
6317
6318   if (left_tree == error_mark_node || right_tree == error_mark_node)
6319     return error_mark_node;
6320
6321   tree ret = fold_build2(code, boolean_type_node, left_tree, right_tree);
6322   if (CAN_HAVE_LOCATION_P(ret))
6323     SET_EXPR_LOCATION(ret, location);
6324   return ret;
6325 }
6326
6327 // Class Bound_method_expression.
6328
6329 // Traversal.
6330
6331 int
6332 Bound_method_expression::do_traverse(Traverse* traverse)
6333 {
6334   if (Expression::traverse(&this->expr_, traverse) == TRAVERSE_EXIT)
6335     return TRAVERSE_EXIT;
6336   return Expression::traverse(&this->method_, traverse);
6337 }
6338
6339 // Return the type of a bound method expression.  The type of this
6340 // object is really the type of the method with no receiver.  We
6341 // should be able to get away with just returning the type of the
6342 // method.
6343
6344 Type*
6345 Bound_method_expression::do_type()
6346 {
6347   return this->method_->type();
6348 }
6349
6350 // Determine the types of a method expression.
6351
6352 void
6353 Bound_method_expression::do_determine_type(const Type_context*)
6354 {
6355   this->method_->determine_type_no_context();
6356   Type* mtype = this->method_->type();
6357   Function_type* fntype = mtype == NULL ? NULL : mtype->function_type();
6358   if (fntype == NULL || !fntype->is_method())
6359     this->expr_->determine_type_no_context();
6360   else
6361     {
6362       Type_context subcontext(fntype->receiver()->type(), false);
6363       this->expr_->determine_type(&subcontext);
6364     }
6365 }
6366
6367 // Check the types of a method expression.
6368
6369 void
6370 Bound_method_expression::do_check_types(Gogo*)
6371 {
6372   Type* type = this->method_->type()->deref();
6373   if (type == NULL
6374       || type->function_type() == NULL
6375       || !type->function_type()->is_method())
6376     this->report_error(_("object is not a method"));
6377   else
6378     {
6379       Type* rtype = type->function_type()->receiver()->type()->deref();
6380       Type* etype = (this->expr_type_ != NULL
6381                      ? this->expr_type_
6382                      : this->expr_->type());
6383       etype = etype->deref();
6384       if (!Type::are_identical(rtype, etype, true, NULL))
6385         this->report_error(_("method type does not match object type"));
6386     }
6387 }
6388
6389 // Get the tree for a method expression.  There is no standard tree
6390 // representation for this.  The only places it may currently be used
6391 // are in a Call_expression or a Go_statement, which will take it
6392 // apart directly.  So this has nothing to do at present.
6393
6394 tree
6395 Bound_method_expression::do_get_tree(Translate_context*)
6396 {
6397   gcc_unreachable();
6398 }
6399
6400 // Make a method expression.
6401
6402 Bound_method_expression*
6403 Expression::make_bound_method(Expression* expr, Expression* method,
6404                               source_location location)
6405 {
6406   return new Bound_method_expression(expr, method, location);
6407 }
6408
6409 // Class Builtin_call_expression.  This is used for a call to a
6410 // builtin function.
6411
6412 class Builtin_call_expression : public Call_expression
6413 {
6414  public:
6415   Builtin_call_expression(Gogo* gogo, Expression* fn, Expression_list* args,
6416                           bool is_varargs, source_location location);
6417
6418  protected:
6419   // This overrides Call_expression::do_lower.
6420   Expression*
6421   do_lower(Gogo*, Named_object*, int);
6422
6423   bool
6424   do_is_constant() const;
6425
6426   bool
6427   do_integer_constant_value(bool, mpz_t, Type**) const;
6428
6429   bool
6430   do_float_constant_value(mpfr_t, Type**) const;
6431
6432   bool
6433   do_complex_constant_value(mpfr_t, mpfr_t, Type**) const;
6434
6435   Type*
6436   do_type();
6437
6438   void
6439   do_determine_type(const Type_context*);
6440
6441   void
6442   do_check_types(Gogo*);
6443
6444   Expression*
6445   do_copy()
6446   {
6447     return new Builtin_call_expression(this->gogo_, this->fn()->copy(),
6448                                        this->args()->copy(),
6449                                        this->is_varargs(),
6450                                        this->location());
6451   }
6452
6453   tree
6454   do_get_tree(Translate_context*);
6455
6456   void
6457   do_export(Export*) const;
6458
6459   virtual bool
6460   do_is_recover_call() const;
6461
6462   virtual void
6463   do_set_recover_arg(Expression*);
6464
6465  private:
6466   // The builtin functions.
6467   enum Builtin_function_code
6468     {
6469       BUILTIN_INVALID,
6470
6471       // Predeclared builtin functions.
6472       BUILTIN_APPEND,
6473       BUILTIN_CAP,
6474       BUILTIN_CLOSE,
6475       BUILTIN_CLOSED,
6476       BUILTIN_CMPLX,
6477       BUILTIN_COPY,
6478       BUILTIN_IMAG,
6479       BUILTIN_LEN,
6480       BUILTIN_MAKE,
6481       BUILTIN_NEW,
6482       BUILTIN_PANIC,
6483       BUILTIN_PRINT,
6484       BUILTIN_PRINTLN,
6485       BUILTIN_REAL,
6486       BUILTIN_RECOVER,
6487
6488       // Builtin functions from the unsafe package.
6489       BUILTIN_ALIGNOF,
6490       BUILTIN_OFFSETOF,
6491       BUILTIN_SIZEOF
6492     };
6493
6494   Expression*
6495   one_arg() const;
6496
6497   bool
6498   check_one_arg();
6499
6500   static Type*
6501   real_imag_type(Type*);
6502
6503   static Type*
6504   cmplx_type(Type*);
6505
6506   // A pointer back to the general IR structure.  This avoids a global
6507   // variable, or passing it around everywhere.
6508   Gogo* gogo_;
6509   // The builtin function being called.
6510   Builtin_function_code code_;
6511   // Used to stop endless loops when the length of an array uses len
6512   // or cap of the array itself.
6513   mutable bool seen_;
6514 };
6515
6516 Builtin_call_expression::Builtin_call_expression(Gogo* gogo,
6517                                                  Expression* fn,
6518                                                  Expression_list* args,
6519                                                  bool is_varargs,
6520                                                  source_location location)
6521   : Call_expression(fn, args, is_varargs, location),
6522     gogo_(gogo), code_(BUILTIN_INVALID), seen_(false)
6523 {
6524   Func_expression* fnexp = this->fn()->func_expression();
6525   gcc_assert(fnexp != NULL);
6526   const std::string& name(fnexp->named_object()->name());
6527   if (name == "append")
6528     this->code_ = BUILTIN_APPEND;
6529   else if (name == "cap")
6530     this->code_ = BUILTIN_CAP;
6531   else if (name == "close")
6532     this->code_ = BUILTIN_CLOSE;
6533   else if (name == "closed")
6534     this->code_ = BUILTIN_CLOSED;
6535   else if (name == "cmplx")
6536     this->code_ = BUILTIN_CMPLX;
6537   else if (name == "copy")
6538     this->code_ = BUILTIN_COPY;
6539   else if (name == "imag")
6540     this->code_ = BUILTIN_IMAG;
6541   else if (name == "len")
6542     this->code_ = BUILTIN_LEN;
6543   else if (name == "make")
6544     this->code_ = BUILTIN_MAKE;
6545   else if (name == "new")
6546     this->code_ = BUILTIN_NEW;
6547   else if (name == "panic")
6548     this->code_ = BUILTIN_PANIC;
6549   else if (name == "print")
6550     this->code_ = BUILTIN_PRINT;
6551   else if (name == "println")
6552     this->code_ = BUILTIN_PRINTLN;
6553   else if (name == "real")
6554     this->code_ = BUILTIN_REAL;
6555   else if (name == "recover")
6556     this->code_ = BUILTIN_RECOVER;
6557   else if (name == "Alignof")
6558     this->code_ = BUILTIN_ALIGNOF;
6559   else if (name == "Offsetof")
6560     this->code_ = BUILTIN_OFFSETOF;
6561   else if (name == "Sizeof")
6562     this->code_ = BUILTIN_SIZEOF;
6563   else
6564     gcc_unreachable();
6565 }
6566
6567 // Return whether this is a call to recover.  This is a virtual
6568 // function called from the parent class.
6569
6570 bool
6571 Builtin_call_expression::do_is_recover_call() const
6572 {
6573   if (this->classification() == EXPRESSION_ERROR)
6574     return false;
6575   return this->code_ == BUILTIN_RECOVER;
6576 }
6577
6578 // Set the argument for a call to recover.
6579
6580 void
6581 Builtin_call_expression::do_set_recover_arg(Expression* arg)
6582 {
6583   const Expression_list* args = this->args();
6584   gcc_assert(args == NULL || args->empty());
6585   Expression_list* new_args = new Expression_list();
6586   new_args->push_back(arg);
6587   this->set_args(new_args);
6588 }
6589
6590 // A traversal class which looks for a call expression.
6591
6592 class Find_call_expression : public Traverse
6593 {
6594  public:
6595   Find_call_expression()
6596     : Traverse(traverse_expressions),
6597       found_(false)
6598   { }
6599
6600   int
6601   expression(Expression**);
6602
6603   bool
6604   found()
6605   { return this->found_; }
6606
6607  private:
6608   bool found_;
6609 };
6610
6611 int
6612 Find_call_expression::expression(Expression** pexpr)
6613 {
6614   if ((*pexpr)->call_expression() != NULL)
6615     {
6616       this->found_ = true;
6617       return TRAVERSE_EXIT;
6618     }
6619   return TRAVERSE_CONTINUE;
6620 }
6621
6622 // Lower a builtin call expression.  This turns new and make into
6623 // specific expressions.  We also convert to a constant if we can.
6624
6625 Expression*
6626 Builtin_call_expression::do_lower(Gogo* gogo, Named_object* function, int)
6627 {
6628   if (this->code_ == BUILTIN_NEW)
6629     {
6630       const Expression_list* args = this->args();
6631       if (args == NULL || args->size() < 1)
6632         this->report_error(_("not enough arguments"));
6633       else if (args->size() > 1)
6634         this->report_error(_("too many arguments"));
6635       else
6636         {
6637           Expression* arg = args->front();
6638           if (!arg->is_type_expression())
6639             {
6640               error_at(arg->location(), "expected type");
6641               this->set_is_error();
6642             }
6643           else
6644             return Expression::make_allocation(arg->type(), this->location());
6645         }
6646     }
6647   else if (this->code_ == BUILTIN_MAKE)
6648     {
6649       const Expression_list* args = this->args();
6650       if (args == NULL || args->size() < 1)
6651         this->report_error(_("not enough arguments"));
6652       else
6653         {
6654           Expression* arg = args->front();
6655           if (!arg->is_type_expression())
6656             {
6657               error_at(arg->location(), "expected type");
6658               this->set_is_error();
6659             }
6660           else
6661             {
6662               Expression_list* newargs;
6663               if (args->size() == 1)
6664                 newargs = NULL;
6665               else
6666                 {
6667                   newargs = new Expression_list();
6668                   Expression_list::const_iterator p = args->begin();
6669                   ++p;
6670                   for (; p != args->end(); ++p)
6671                     newargs->push_back(*p);
6672                 }
6673               return Expression::make_make(arg->type(), newargs,
6674                                            this->location());
6675             }
6676         }
6677     }
6678   else if (this->is_constant())
6679     {
6680       // We can only lower len and cap if there are no function calls
6681       // in the arguments.  Otherwise we have to make the call.
6682       if (this->code_ == BUILTIN_LEN || this->code_ == BUILTIN_CAP)
6683         {
6684           Expression* arg = this->one_arg();
6685           if (!arg->is_constant())
6686             {
6687               Find_call_expression find_call;
6688               Expression::traverse(&arg, &find_call);
6689               if (find_call.found())
6690                 return this;
6691             }
6692         }
6693
6694       mpz_t ival;
6695       mpz_init(ival);
6696       Type* type;
6697       if (this->integer_constant_value(true, ival, &type))
6698         {
6699           Expression* ret = Expression::make_integer(&ival, type,
6700                                                      this->location());
6701           mpz_clear(ival);
6702           return ret;
6703         }
6704       mpz_clear(ival);
6705
6706       mpfr_t rval;
6707       mpfr_init(rval);
6708       if (this->float_constant_value(rval, &type))
6709         {
6710           Expression* ret = Expression::make_float(&rval, type,
6711                                                    this->location());
6712           mpfr_clear(rval);
6713           return ret;
6714         }
6715
6716       mpfr_t imag;
6717       mpfr_init(imag);
6718       if (this->complex_constant_value(rval, imag, &type))
6719         {
6720           Expression* ret = Expression::make_complex(&rval, &imag, type,
6721                                                      this->location());
6722           mpfr_clear(rval);
6723           mpfr_clear(imag);
6724           return ret;
6725         }
6726       mpfr_clear(rval);
6727       mpfr_clear(imag);
6728     }
6729   else if (this->code_ == BUILTIN_RECOVER)
6730     {
6731       if (function != NULL)
6732         function->func_value()->set_calls_recover();
6733       else
6734         {
6735           // Calling recover outside of a function always returns the
6736           // nil empty interface.
6737           Type* eface = Type::make_interface_type(NULL, this->location());
6738           return Expression::make_cast(eface,
6739                                        Expression::make_nil(this->location()),
6740                                        this->location());
6741         }
6742     }
6743   else if (this->code_ == BUILTIN_APPEND)
6744     {
6745       // Lower the varargs.
6746       const Expression_list* args = this->args();
6747       if (args == NULL || args->empty())
6748         return this;
6749       Type* slice_type = args->front()->type();
6750       if (!slice_type->is_open_array_type())
6751         {
6752           error_at(args->front()->location(), "argument 1 must be a slice");
6753           this->set_is_error();
6754           return this;
6755         }
6756       return this->lower_varargs(gogo, function, slice_type, 2);
6757     }
6758
6759   return this;
6760 }
6761
6762 // Return the type of the real or imag functions, given the type of
6763 // the argument.  We need to map complex to float, complex64 to
6764 // float32, and complex128 to float64, so it has to be done by name.
6765 // This returns NULL if it can't figure out the type.
6766
6767 Type*
6768 Builtin_call_expression::real_imag_type(Type* arg_type)
6769 {
6770   if (arg_type == NULL || arg_type->is_abstract())
6771     return NULL;
6772   Named_type* nt = arg_type->named_type();
6773   if (nt == NULL)
6774     return NULL;
6775   while (nt->real_type()->named_type() != NULL)
6776     nt = nt->real_type()->named_type();
6777   if (nt->name() == "complex")
6778     return Type::lookup_float_type("float");
6779   else if (nt->name() == "complex64")
6780     return Type::lookup_float_type("float32");
6781   else if (nt->name() == "complex128")
6782     return Type::lookup_float_type("float64");
6783   else
6784     return NULL;
6785 }
6786
6787 // Return the type of the cmplx function, given the type of one of the
6788 // argments.  Like real_imag_type, we have to map by name.
6789
6790 Type*
6791 Builtin_call_expression::cmplx_type(Type* arg_type)
6792 {
6793   if (arg_type == NULL || arg_type->is_abstract())
6794     return NULL;
6795   Named_type* nt = arg_type->named_type();
6796   if (nt == NULL)
6797     return NULL;
6798   while (nt->real_type()->named_type() != NULL)
6799     nt = nt->real_type()->named_type();
6800   if (nt->name() == "float")
6801     return Type::lookup_complex_type("complex");
6802   else if (nt->name() == "float32")
6803     return Type::lookup_complex_type("complex64");
6804   else if (nt->name() == "float64")
6805     return Type::lookup_complex_type("complex128");
6806   else
6807     return NULL;
6808 }
6809
6810 // Return a single argument, or NULL if there isn't one.
6811
6812 Expression*
6813 Builtin_call_expression::one_arg() const
6814 {
6815   const Expression_list* args = this->args();
6816   if (args->size() != 1)
6817     return NULL;
6818   return args->front();
6819 }
6820
6821 // Return whether this is constant: len of a string, or len or cap of
6822 // a fixed array, or unsafe.Sizeof, unsafe.Offsetof, unsafe.Alignof.
6823
6824 bool
6825 Builtin_call_expression::do_is_constant() const
6826 {
6827   switch (this->code_)
6828     {
6829     case BUILTIN_LEN:
6830     case BUILTIN_CAP:
6831       {
6832         if (this->seen_)
6833           return false;
6834
6835         Expression* arg = this->one_arg();
6836         if (arg == NULL)
6837           return false;
6838         Type* arg_type = arg->type();
6839
6840         if (arg_type->points_to() != NULL
6841             && arg_type->points_to()->array_type() != NULL
6842             && !arg_type->points_to()->is_open_array_type())
6843           arg_type = arg_type->points_to();
6844
6845         if (arg_type->array_type() != NULL
6846             && arg_type->array_type()->length() != NULL)
6847           return true;
6848
6849         if (this->code_ == BUILTIN_LEN && arg_type->is_string_type())
6850           {
6851             this->seen_ = true;
6852             bool ret = arg->is_constant();
6853             this->seen_ = false;
6854             return ret;
6855           }
6856       }
6857       break;
6858
6859     case BUILTIN_SIZEOF:
6860     case BUILTIN_ALIGNOF:
6861       return this->one_arg() != NULL;
6862
6863     case BUILTIN_OFFSETOF:
6864       {
6865         Expression* arg = this->one_arg();
6866         if (arg == NULL)
6867           return false;
6868         return arg->field_reference_expression() != NULL;
6869       }
6870
6871     case BUILTIN_CMPLX:
6872       {
6873         const Expression_list* args = this->args();
6874         if (args != NULL && args->size() == 2)
6875           return args->front()->is_constant() && args->back()->is_constant();
6876       }
6877       break;
6878
6879     case BUILTIN_REAL:
6880     case BUILTIN_IMAG:
6881       {
6882         Expression* arg = this->one_arg();
6883         return arg != NULL && arg->is_constant();
6884       }
6885
6886     default:
6887       break;
6888     }
6889
6890   return false;
6891 }
6892
6893 // Return an integer constant value if possible.
6894
6895 bool
6896 Builtin_call_expression::do_integer_constant_value(bool iota_is_constant,
6897                                                    mpz_t val,
6898                                                    Type** ptype) const
6899 {
6900   if (this->code_ == BUILTIN_LEN
6901       || this->code_ == BUILTIN_CAP)
6902     {
6903       Expression* arg = this->one_arg();
6904       if (arg == NULL)
6905         return false;
6906       Type* arg_type = arg->type();
6907
6908       if (this->code_ == BUILTIN_LEN && arg_type->is_string_type())
6909         {
6910           std::string sval;
6911           if (arg->string_constant_value(&sval))
6912             {
6913               mpz_set_ui(val, sval.length());
6914               *ptype = Type::lookup_integer_type("int");
6915               return true;
6916             }
6917         }
6918
6919       if (arg_type->points_to() != NULL
6920           && arg_type->points_to()->array_type() != NULL
6921           && !arg_type->points_to()->is_open_array_type())
6922         arg_type = arg_type->points_to();
6923
6924       if (arg_type->array_type() != NULL
6925           && arg_type->array_type()->length() != NULL)
6926         {
6927           if (this->seen_)
6928             return false;
6929           Expression* e = arg_type->array_type()->length();
6930           this->seen_ = true;
6931           bool r = e->integer_constant_value(iota_is_constant, val, ptype);
6932           this->seen_ = false;
6933           if (r)
6934             {
6935               *ptype = Type::lookup_integer_type("int");
6936               return true;
6937             }
6938         }
6939     }
6940   else if (this->code_ == BUILTIN_SIZEOF
6941            || this->code_ == BUILTIN_ALIGNOF)
6942     {
6943       Expression* arg = this->one_arg();
6944       if (arg == NULL)
6945         return false;
6946       Type* arg_type = arg->type();
6947       if (arg_type->is_error_type() || arg_type->is_undefined())
6948         return false;
6949       if (arg_type->is_abstract())
6950         return false;
6951       tree arg_type_tree = arg_type->get_tree(this->gogo_);
6952       unsigned long val_long;
6953       if (this->code_ == BUILTIN_SIZEOF)
6954         {
6955           tree type_size = TYPE_SIZE_UNIT(arg_type_tree);
6956           gcc_assert(TREE_CODE(type_size) == INTEGER_CST);
6957           if (TREE_INT_CST_HIGH(type_size) != 0)
6958             return false;
6959           unsigned HOST_WIDE_INT val_wide = TREE_INT_CST_LOW(type_size);
6960           val_long = static_cast<unsigned long>(val_wide);
6961           if (val_long != val_wide)
6962             return false;
6963         }
6964       else if (this->code_ == BUILTIN_ALIGNOF)
6965         {
6966           if (arg->field_reference_expression() == NULL)
6967             val_long = go_type_alignment(arg_type_tree);
6968           else
6969             {
6970               // Calling unsafe.Alignof(s.f) returns the alignment of
6971               // the type of f when it is used as a field in a struct.
6972               val_long = go_field_alignment(arg_type_tree);
6973             }
6974         }
6975       else
6976         gcc_unreachable();
6977       mpz_set_ui(val, val_long);
6978       *ptype = NULL;
6979       return true;
6980     }
6981   else if (this->code_ == BUILTIN_OFFSETOF)
6982     {
6983       Expression* arg = this->one_arg();
6984       if (arg == NULL)
6985         return false;
6986       Field_reference_expression* farg = arg->field_reference_expression();
6987       if (farg == NULL)
6988         return false;
6989       Expression* struct_expr = farg->expr();
6990       Type* st = struct_expr->type();
6991       if (st->struct_type() == NULL)
6992         return false;
6993       tree struct_tree = st->get_tree(this->gogo_);
6994       gcc_assert(TREE_CODE(struct_tree) == RECORD_TYPE);
6995       tree field = TYPE_FIELDS(struct_tree);
6996       for (unsigned int index = farg->field_index(); index > 0; --index)
6997         {
6998           field = DECL_CHAIN(field);
6999           gcc_assert(field != NULL_TREE);
7000         }
7001       HOST_WIDE_INT offset_wide = int_byte_position (field);
7002       if (offset_wide < 0)
7003         return false;
7004       unsigned long offset_long = static_cast<unsigned long>(offset_wide);
7005       if (offset_long != static_cast<unsigned HOST_WIDE_INT>(offset_wide))
7006         return false;
7007       mpz_set_ui(val, offset_long);
7008       return true;
7009     }
7010   return false;
7011 }
7012
7013 // Return a floating point constant value if possible.
7014
7015 bool
7016 Builtin_call_expression::do_float_constant_value(mpfr_t val,
7017                                                  Type** ptype) const
7018 {
7019   if (this->code_ == BUILTIN_REAL || this->code_ == BUILTIN_IMAG)
7020     {
7021       Expression* arg = this->one_arg();
7022       if (arg == NULL)
7023         return false;
7024
7025       mpfr_t real;
7026       mpfr_t imag;
7027       mpfr_init(real);
7028       mpfr_init(imag);
7029
7030       bool ret = false;
7031       Type* type;
7032       if (arg->complex_constant_value(real, imag, &type))
7033         {
7034           if (this->code_ == BUILTIN_REAL)
7035             mpfr_set(val, real, GMP_RNDN);
7036           else
7037             mpfr_set(val, imag, GMP_RNDN);
7038           *ptype = Builtin_call_expression::real_imag_type(type);
7039           ret = true;
7040         }
7041
7042       mpfr_clear(real);
7043       mpfr_clear(imag);
7044       return ret;
7045     }
7046
7047   return false;
7048 }
7049
7050 // Return a complex constant value if possible.
7051
7052 bool
7053 Builtin_call_expression::do_complex_constant_value(mpfr_t real, mpfr_t imag,
7054                                                    Type** ptype) const
7055 {
7056   if (this->code_ == BUILTIN_CMPLX)
7057     {
7058       const Expression_list* args = this->args();
7059       if (args == NULL || args->size() != 2)
7060         return false;
7061
7062       mpfr_t r;
7063       mpfr_init(r);
7064       Type* rtype;
7065       if (!args->front()->float_constant_value(r, &rtype))
7066         {
7067           mpfr_clear(r);
7068           return false;
7069         }
7070
7071       mpfr_t i;
7072       mpfr_init(i);
7073
7074       bool ret = false;
7075       Type* itype;
7076       if (args->back()->float_constant_value(i, &itype)
7077           && Type::are_identical(rtype, itype, false, NULL))
7078         {
7079           mpfr_set(real, r, GMP_RNDN);
7080           mpfr_set(imag, i, GMP_RNDN);
7081           *ptype = Builtin_call_expression::cmplx_type(rtype);
7082           ret = true;
7083         }
7084
7085       mpfr_clear(r);
7086       mpfr_clear(i);
7087
7088       return ret;
7089     }
7090
7091   return false;
7092 }
7093
7094 // Return the type.
7095
7096 Type*
7097 Builtin_call_expression::do_type()
7098 {
7099   switch (this->code_)
7100     {
7101     case BUILTIN_INVALID:
7102     default:
7103       gcc_unreachable();
7104
7105     case BUILTIN_NEW:
7106     case BUILTIN_MAKE:
7107       {
7108         const Expression_list* args = this->args();
7109         if (args == NULL || args->empty())
7110           return Type::make_error_type();
7111         return Type::make_pointer_type(args->front()->type());
7112       }
7113
7114     case BUILTIN_CAP:
7115     case BUILTIN_COPY:
7116     case BUILTIN_LEN:
7117     case BUILTIN_ALIGNOF:
7118     case BUILTIN_OFFSETOF:
7119     case BUILTIN_SIZEOF:
7120       return Type::lookup_integer_type("int");
7121
7122     case BUILTIN_CLOSE:
7123     case BUILTIN_PANIC:
7124     case BUILTIN_PRINT:
7125     case BUILTIN_PRINTLN:
7126       return Type::make_void_type();
7127
7128     case BUILTIN_CLOSED:
7129       return Type::lookup_bool_type();
7130
7131     case BUILTIN_RECOVER:
7132       return Type::make_interface_type(NULL, BUILTINS_LOCATION);
7133
7134     case BUILTIN_APPEND:
7135       {
7136         const Expression_list* args = this->args();
7137         if (args == NULL || args->empty())
7138           return Type::make_error_type();
7139         return args->front()->type();
7140       }
7141
7142     case BUILTIN_REAL:
7143     case BUILTIN_IMAG:
7144       {
7145         Expression* arg = this->one_arg();
7146         if (arg == NULL)
7147           return Type::make_error_type();
7148         Type* t = arg->type();
7149         if (t->is_abstract())
7150           t = t->make_non_abstract_type();
7151         t = Builtin_call_expression::real_imag_type(t);
7152         if (t == NULL)
7153           t = Type::make_error_type();
7154         return t;
7155       }
7156
7157     case BUILTIN_CMPLX:
7158       {
7159         const Expression_list* args = this->args();
7160         if (args == NULL || args->size() != 2)
7161           return Type::make_error_type();
7162         Type* t = args->front()->type();
7163         if (t->is_abstract())
7164           {
7165             t = args->back()->type();
7166             if (t->is_abstract())
7167               t = t->make_non_abstract_type();
7168           }
7169         t = Builtin_call_expression::cmplx_type(t);
7170         if (t == NULL)
7171           t = Type::make_error_type();
7172         return t;
7173       }
7174     }
7175 }
7176
7177 // Determine the type.
7178
7179 void
7180 Builtin_call_expression::do_determine_type(const Type_context* context)
7181 {
7182   this->fn()->determine_type_no_context();
7183
7184   const Expression_list* args = this->args();
7185
7186   bool is_print;
7187   Type* arg_type = NULL;
7188   switch (this->code_)
7189     {
7190     case BUILTIN_PRINT:
7191     case BUILTIN_PRINTLN:
7192       // Do not force a large integer constant to "int".
7193       is_print = true;
7194       break;
7195
7196     case BUILTIN_REAL:
7197     case BUILTIN_IMAG:
7198       arg_type = Builtin_call_expression::cmplx_type(context->type);
7199       is_print = false;
7200       break;
7201
7202     case BUILTIN_CMPLX:
7203       {
7204         // For the cmplx function the type of one operand can
7205         // determine the type of the other, as in a binary expression.
7206         arg_type = Builtin_call_expression::real_imag_type(context->type);
7207         if (args != NULL && args->size() == 2)
7208           {
7209             Type* t1 = args->front()->type();
7210             Type* t2 = args->front()->type();
7211             if (!t1->is_abstract())
7212               arg_type = t1;
7213             else if (!t2->is_abstract())
7214               arg_type = t2;
7215           }
7216         is_print = false;
7217       }
7218       break;
7219
7220     default:
7221       is_print = false;
7222       break;
7223     }
7224
7225   if (args != NULL)
7226     {
7227       for (Expression_list::const_iterator pa = args->begin();
7228            pa != args->end();
7229            ++pa)
7230         {
7231           Type_context subcontext;
7232           subcontext.type = arg_type;
7233
7234           if (is_print)
7235             {
7236               // We want to print large constants, we so can't just
7237               // use the appropriate nonabstract type.  Use uint64 for
7238               // an integer if we know it is nonnegative, otherwise
7239               // use int64 for a integer, otherwise use float64 for a
7240               // float or complex128 for a complex.
7241               Type* want_type = NULL;
7242               Type* atype = (*pa)->type();
7243               if (atype->is_abstract())
7244                 {
7245                   if (atype->integer_type() != NULL)
7246                     {
7247                       mpz_t val;
7248                       mpz_init(val);
7249                       Type* dummy;
7250                       if (this->integer_constant_value(true, val, &dummy)
7251                           && mpz_sgn(val) >= 0)
7252                         want_type = Type::lookup_integer_type("uint64");
7253                       else
7254                         want_type = Type::lookup_integer_type("int64");
7255                       mpz_clear(val);
7256                     }
7257                   else if (atype->float_type() != NULL)
7258                     want_type = Type::lookup_float_type("float64");
7259                   else if (atype->complex_type() != NULL)
7260                     want_type = Type::lookup_complex_type("complex128");
7261                   else if (atype->is_abstract_string_type())
7262                     want_type = Type::lookup_string_type();
7263                   else if (atype->is_abstract_boolean_type())
7264                     want_type = Type::lookup_bool_type();
7265                   else
7266                     gcc_unreachable();
7267                   subcontext.type = want_type;
7268                 }
7269             }
7270
7271           (*pa)->determine_type(&subcontext);
7272         }
7273     }
7274 }
7275
7276 // If there is exactly one argument, return true.  Otherwise give an
7277 // error message and return false.
7278
7279 bool
7280 Builtin_call_expression::check_one_arg()
7281 {
7282   const Expression_list* args = this->args();
7283   if (args == NULL || args->size() < 1)
7284     {
7285       this->report_error(_("not enough arguments"));
7286       return false;
7287     }
7288   else if (args->size() > 1)
7289     {
7290       this->report_error(_("too many arguments"));
7291       return false;
7292     }
7293   if (args->front()->is_error_expression()
7294       || args->front()->type()->is_error_type()
7295       || args->front()->type()->is_undefined())
7296     {
7297       this->set_is_error();
7298       return false;
7299     }
7300   return true;
7301 }
7302
7303 // Check argument types for a builtin function.
7304
7305 void
7306 Builtin_call_expression::do_check_types(Gogo*)
7307 {
7308   switch (this->code_)
7309     {
7310     case BUILTIN_INVALID:
7311     case BUILTIN_NEW:
7312     case BUILTIN_MAKE:
7313       return;
7314
7315     case BUILTIN_LEN:
7316     case BUILTIN_CAP:
7317       {
7318         // The single argument may be either a string or an array or a
7319         // map or a channel, or a pointer to a closed array.
7320         if (this->check_one_arg())
7321           {
7322             Type* arg_type = this->one_arg()->type();
7323             if (arg_type->points_to() != NULL
7324                 && arg_type->points_to()->array_type() != NULL
7325                 && !arg_type->points_to()->is_open_array_type())
7326               arg_type = arg_type->points_to();
7327             if (this->code_ == BUILTIN_CAP)
7328               {
7329                 if (!arg_type->is_error_type()
7330                     && arg_type->array_type() == NULL
7331                     && arg_type->channel_type() == NULL)
7332                   this->report_error(_("argument must be array or slice "
7333                                        "or channel"));
7334               }
7335             else
7336               {
7337                 if (!arg_type->is_error_type()
7338                     && !arg_type->is_string_type()
7339                     && arg_type->array_type() == NULL
7340                     && arg_type->map_type() == NULL
7341                     && arg_type->channel_type() == NULL)
7342                   this->report_error(_("argument must be string or "
7343                                        "array or slice or map or channel"));
7344               }
7345           }
7346       }
7347       break;
7348
7349     case BUILTIN_PRINT:
7350     case BUILTIN_PRINTLN:
7351       {
7352         const Expression_list* args = this->args();
7353         if (args == NULL)
7354           {
7355             if (this->code_ == BUILTIN_PRINT)
7356               warning_at(this->location(), 0,
7357                          "no arguments for builtin function %<%s%>",
7358                          (this->code_ == BUILTIN_PRINT
7359                           ? "print"
7360                           : "println"));
7361           }
7362         else
7363           {
7364             for (Expression_list::const_iterator p = args->begin();
7365                  p != args->end();
7366                  ++p)
7367               {
7368                 Type* type = (*p)->type();
7369                 if (type->is_error_type()
7370                     || type->is_string_type()
7371                     || type->integer_type() != NULL
7372                     || type->float_type() != NULL
7373                     || type->complex_type() != NULL
7374                     || type->is_boolean_type()
7375                     || type->points_to() != NULL
7376                     || type->interface_type() != NULL
7377                     || type->channel_type() != NULL
7378                     || type->map_type() != NULL
7379                     || type->function_type() != NULL
7380                     || type->is_open_array_type())
7381                   ;
7382                 else
7383                   this->report_error(_("unsupported argument type to "
7384                                        "builtin function"));
7385               }
7386           }
7387       }
7388       break;
7389
7390     case BUILTIN_CLOSE:
7391     case BUILTIN_CLOSED:
7392       if (this->check_one_arg())
7393         {
7394           if (this->one_arg()->type()->channel_type() == NULL)
7395             this->report_error(_("argument must be channel"));
7396         }
7397       break;
7398
7399     case BUILTIN_PANIC:
7400     case BUILTIN_SIZEOF:
7401     case BUILTIN_ALIGNOF:
7402       this->check_one_arg();
7403       break;
7404
7405     case BUILTIN_RECOVER:
7406       if (this->args() != NULL && !this->args()->empty())
7407         this->report_error(_("too many arguments"));
7408       break;
7409
7410     case BUILTIN_OFFSETOF:
7411       if (this->check_one_arg())
7412         {
7413           Expression* arg = this->one_arg();
7414           if (arg->field_reference_expression() == NULL)
7415             this->report_error(_("argument must be a field reference"));
7416         }
7417       break;
7418
7419     case BUILTIN_COPY:
7420       {
7421         const Expression_list* args = this->args();
7422         if (args == NULL || args->size() < 2)
7423           {
7424             this->report_error(_("not enough arguments"));
7425             break;
7426           }
7427         else if (args->size() > 2)
7428           {
7429             this->report_error(_("too many arguments"));
7430             break;
7431           }
7432         Type* arg1_type = args->front()->type();
7433         Type* arg2_type = args->back()->type();
7434         if (arg1_type->is_error_type() || arg2_type->is_error_type())
7435           break;
7436
7437         Type* e1;
7438         if (arg1_type->is_open_array_type())
7439           e1 = arg1_type->array_type()->element_type();
7440         else
7441           {
7442             this->report_error(_("left argument must be a slice"));
7443             break;
7444           }
7445
7446         Type* e2;
7447         if (arg2_type->is_open_array_type())
7448           e2 = arg2_type->array_type()->element_type();
7449         else if (arg2_type->is_string_type())
7450           e2 = Type::lookup_integer_type("uint8");
7451         else
7452           {
7453             this->report_error(_("right argument must be a slice or a string"));
7454             break;
7455           }
7456
7457         if (!Type::are_identical(e1, e2, true, NULL))
7458           this->report_error(_("element types must be the same"));
7459       }
7460       break;
7461
7462     case BUILTIN_APPEND:
7463       {
7464         const Expression_list* args = this->args();
7465         if (args == NULL || args->size() < 2)
7466           {
7467             this->report_error(_("not enough arguments"));
7468             break;
7469           }
7470         if (args->size() > 2)
7471           {
7472             this->report_error(_("too many arguments"));
7473             break;
7474           }
7475         std::string reason;
7476         if (!Type::are_assignable(args->front()->type(), args->back()->type(),
7477                                   &reason))
7478           {
7479             if (reason.empty())
7480               this->report_error(_("arguments 1 and 2 have different types"));
7481             else
7482               {
7483                 error_at(this->location(),
7484                          "arguments 1 and 2 have different types (%s)",
7485                          reason.c_str());
7486                 this->set_is_error();
7487               }
7488           }
7489         break;
7490       }
7491
7492     case BUILTIN_REAL:
7493     case BUILTIN_IMAG:
7494       if (this->check_one_arg())
7495         {
7496           if (this->one_arg()->type()->complex_type() == NULL)
7497             this->report_error(_("argument must have complex type"));
7498         }
7499       break;
7500
7501     case BUILTIN_CMPLX:
7502       {
7503         const Expression_list* args = this->args();
7504         if (args == NULL || args->size() < 2)
7505           this->report_error(_("not enough arguments"));
7506         else if (args->size() > 2)
7507           this->report_error(_("too many arguments"));
7508         else if (args->front()->is_error_expression()
7509                  || args->front()->type()->is_error_type()
7510                  || args->back()->is_error_expression()
7511                  || args->back()->type()->is_error_type())
7512           this->set_is_error();
7513         else if (!Type::are_identical(args->front()->type(),
7514                                       args->back()->type(), true, NULL))
7515           this->report_error(_("cmplx arguments must have identical types"));
7516         else if (args->front()->type()->float_type() == NULL)
7517           this->report_error(_("cmplx arguments must have "
7518                                "floating-point type"));
7519       }
7520       break;
7521
7522     default:
7523       gcc_unreachable();
7524     }
7525 }
7526
7527 // Return the tree for a builtin function.
7528
7529 tree
7530 Builtin_call_expression::do_get_tree(Translate_context* context)
7531 {
7532   Gogo* gogo = context->gogo();
7533   source_location location = this->location();
7534   switch (this->code_)
7535     {
7536     case BUILTIN_INVALID:
7537     case BUILTIN_NEW:
7538     case BUILTIN_MAKE:
7539       gcc_unreachable();
7540
7541     case BUILTIN_LEN:
7542     case BUILTIN_CAP:
7543       {
7544         const Expression_list* args = this->args();
7545         gcc_assert(args != NULL && args->size() == 1);
7546         Expression* arg = *args->begin();
7547         Type* arg_type = arg->type();
7548
7549         if (this->seen_)
7550           {
7551             gcc_assert(saw_errors());
7552             return error_mark_node;
7553           }
7554         this->seen_ = true;
7555
7556         tree arg_tree = arg->get_tree(context);
7557
7558         this->seen_ = false;
7559
7560         if (arg_tree == error_mark_node)
7561           return error_mark_node;
7562
7563         if (arg_type->points_to() != NULL)
7564           {
7565             arg_type = arg_type->points_to();
7566             gcc_assert(arg_type->array_type() != NULL
7567                        && !arg_type->is_open_array_type());
7568             gcc_assert(POINTER_TYPE_P(TREE_TYPE(arg_tree)));
7569             arg_tree = build_fold_indirect_ref(arg_tree);
7570           }
7571
7572         tree val_tree;
7573         if (this->code_ == BUILTIN_LEN)
7574           {
7575             if (arg_type->is_string_type())
7576               val_tree = String_type::length_tree(gogo, arg_tree);
7577             else if (arg_type->array_type() != NULL)
7578               {
7579                 if (this->seen_)
7580                   {
7581                     gcc_assert(saw_errors());
7582                     return error_mark_node;
7583                   }
7584                 this->seen_ = true;
7585                 val_tree = arg_type->array_type()->length_tree(gogo, arg_tree);
7586                 this->seen_ = false;
7587               }
7588             else if (arg_type->map_type() != NULL)
7589               {
7590                 static tree map_len_fndecl;
7591                 val_tree = Gogo::call_builtin(&map_len_fndecl,
7592                                               location,
7593                                               "__go_map_len",
7594                                               1,
7595                                               sizetype,
7596                                               arg_type->get_tree(gogo),
7597                                               arg_tree);
7598               }
7599             else if (arg_type->channel_type() != NULL)
7600               {
7601                 static tree chan_len_fndecl;
7602                 val_tree = Gogo::call_builtin(&chan_len_fndecl,
7603                                               location,
7604                                               "__go_chan_len",
7605                                               1,
7606                                               sizetype,
7607                                               arg_type->get_tree(gogo),
7608                                               arg_tree);
7609               }
7610             else
7611               gcc_unreachable();
7612           }
7613         else
7614           {
7615             if (arg_type->array_type() != NULL)
7616               {
7617                 if (this->seen_)
7618                   {
7619                     gcc_assert(saw_errors());
7620                     return error_mark_node;
7621                   }
7622                 this->seen_ = true;
7623                 val_tree = arg_type->array_type()->capacity_tree(gogo,
7624                                                                  arg_tree);
7625                 this->seen_ = false;
7626               }
7627             else if (arg_type->channel_type() != NULL)
7628               {
7629                 static tree chan_cap_fndecl;
7630                 val_tree = Gogo::call_builtin(&chan_cap_fndecl,
7631                                               location,
7632                                               "__go_chan_cap",
7633                                               1,
7634                                               sizetype,
7635                                               arg_type->get_tree(gogo),
7636                                               arg_tree);
7637               }
7638             else
7639               gcc_unreachable();
7640           }
7641
7642         if (val_tree == error_mark_node)
7643           return error_mark_node;
7644
7645         tree type_tree = Type::lookup_integer_type("int")->get_tree(gogo);
7646         if (type_tree == TREE_TYPE(val_tree))
7647           return val_tree;
7648         else
7649           return fold(convert_to_integer(type_tree, val_tree));
7650       }
7651
7652     case BUILTIN_PRINT:
7653     case BUILTIN_PRINTLN:
7654       {
7655         const bool is_ln = this->code_ == BUILTIN_PRINTLN;
7656         tree stmt_list = NULL_TREE;
7657
7658         const Expression_list* call_args = this->args();
7659         if (call_args != NULL)
7660           {
7661             for (Expression_list::const_iterator p = call_args->begin();
7662                  p != call_args->end();
7663                  ++p)
7664               {
7665                 if (is_ln && p != call_args->begin())
7666                   {
7667                     static tree print_space_fndecl;
7668                     tree call = Gogo::call_builtin(&print_space_fndecl,
7669                                                    location,
7670                                                    "__go_print_space",
7671                                                    0,
7672                                                    void_type_node);
7673                     if (call == error_mark_node)
7674                       return error_mark_node;
7675                     append_to_statement_list(call, &stmt_list);
7676                   }
7677
7678                 Type* type = (*p)->type();
7679
7680                 tree arg = (*p)->get_tree(context);
7681                 if (arg == error_mark_node)
7682                   return error_mark_node;
7683
7684                 tree* pfndecl;
7685                 const char* fnname;
7686                 if (type->is_string_type())
7687                   {
7688                     static tree print_string_fndecl;
7689                     pfndecl = &print_string_fndecl;
7690                     fnname = "__go_print_string";
7691                   }
7692                 else if (type->integer_type() != NULL
7693                          && type->integer_type()->is_unsigned())
7694                   {
7695                     static tree print_uint64_fndecl;
7696                     pfndecl = &print_uint64_fndecl;
7697                     fnname = "__go_print_uint64";
7698                     Type* itype = Type::lookup_integer_type("uint64");
7699                     arg = fold_convert_loc(location, itype->get_tree(gogo),
7700                                            arg);
7701                   }
7702                 else if (type->integer_type() != NULL)
7703                   {
7704                     static tree print_int64_fndecl;
7705                     pfndecl = &print_int64_fndecl;
7706                     fnname = "__go_print_int64";
7707                     Type* itype = Type::lookup_integer_type("int64");
7708                     arg = fold_convert_loc(location, itype->get_tree(gogo),
7709                                            arg);
7710                   }
7711                 else if (type->float_type() != NULL)
7712                   {
7713                     static tree print_double_fndecl;
7714                     pfndecl = &print_double_fndecl;
7715                     fnname = "__go_print_double";
7716                     arg = fold_convert_loc(location, double_type_node, arg);
7717                   }
7718                 else if (type->complex_type() != NULL)
7719                   {
7720                     static tree print_complex_fndecl;
7721                     pfndecl = &print_complex_fndecl;
7722                     fnname = "__go_print_complex";
7723                     arg = fold_convert_loc(location, complex_double_type_node,
7724                                            arg);
7725                   }
7726                 else if (type->is_boolean_type())
7727                   {
7728                     static tree print_bool_fndecl;
7729                     pfndecl = &print_bool_fndecl;
7730                     fnname = "__go_print_bool";
7731                   }
7732                 else if (type->points_to() != NULL
7733                          || type->channel_type() != NULL
7734                          || type->map_type() != NULL
7735                          || type->function_type() != NULL)
7736                   {
7737                     static tree print_pointer_fndecl;
7738                     pfndecl = &print_pointer_fndecl;
7739                     fnname = "__go_print_pointer";
7740                     arg = fold_convert_loc(location, ptr_type_node, arg);
7741                   }
7742                 else if (type->interface_type() != NULL)
7743                   {
7744                     if (type->interface_type()->is_empty())
7745                       {
7746                         static tree print_empty_interface_fndecl;
7747                         pfndecl = &print_empty_interface_fndecl;
7748                         fnname = "__go_print_empty_interface";
7749                       }
7750                     else
7751                       {
7752                         static tree print_interface_fndecl;
7753                         pfndecl = &print_interface_fndecl;
7754                         fnname = "__go_print_interface";
7755                       }
7756                   }
7757                 else if (type->is_open_array_type())
7758                   {
7759                     static tree print_slice_fndecl;
7760                     pfndecl = &print_slice_fndecl;
7761                     fnname = "__go_print_slice";
7762                   }
7763                 else
7764                   gcc_unreachable();
7765
7766                 tree call = Gogo::call_builtin(pfndecl,
7767                                                location,
7768                                                fnname,
7769                                                1,
7770                                                void_type_node,
7771                                                TREE_TYPE(arg),
7772                                                arg);
7773                 if (call == error_mark_node)
7774                   return error_mark_node;
7775                 append_to_statement_list(call, &stmt_list);
7776               }
7777           }
7778
7779         if (is_ln)
7780           {
7781             static tree print_nl_fndecl;
7782             tree call = Gogo::call_builtin(&print_nl_fndecl,
7783                                            location,
7784                                            "__go_print_nl",
7785                                            0,
7786                                            void_type_node);
7787             if (call == error_mark_node)
7788               return error_mark_node;
7789             append_to_statement_list(call, &stmt_list);
7790           }
7791
7792         return stmt_list;
7793       }
7794
7795     case BUILTIN_PANIC:
7796       {
7797         const Expression_list* args = this->args();
7798         gcc_assert(args != NULL && args->size() == 1);
7799         Expression* arg = args->front();
7800         tree arg_tree = arg->get_tree(context);
7801         if (arg_tree == error_mark_node)
7802           return error_mark_node;
7803         Type *empty = Type::make_interface_type(NULL, BUILTINS_LOCATION);
7804         arg_tree = Expression::convert_for_assignment(context, empty,
7805                                                       arg->type(),
7806                                                       arg_tree, location);
7807         static tree panic_fndecl;
7808         tree call = Gogo::call_builtin(&panic_fndecl,
7809                                        location,
7810                                        "__go_panic",
7811                                        1,
7812                                        void_type_node,
7813                                        TREE_TYPE(arg_tree),
7814                                        arg_tree);
7815         if (call == error_mark_node)
7816           return error_mark_node;
7817         // This function will throw an exception.
7818         TREE_NOTHROW(panic_fndecl) = 0;
7819         // This function will not return.
7820         TREE_THIS_VOLATILE(panic_fndecl) = 1;
7821         return call;
7822       }
7823
7824     case BUILTIN_RECOVER:
7825       {
7826         // The argument is set when building recover thunks.  It's a
7827         // boolean value which is true if we can recover a value now.
7828         const Expression_list* args = this->args();
7829         gcc_assert(args != NULL && args->size() == 1);
7830         Expression* arg = args->front();
7831         tree arg_tree = arg->get_tree(context);
7832         if (arg_tree == error_mark_node)
7833           return error_mark_node;
7834
7835         Type *empty = Type::make_interface_type(NULL, BUILTINS_LOCATION);
7836         tree empty_tree = empty->get_tree(context->gogo());
7837
7838         Type* nil_type = Type::make_nil_type();
7839         Expression* nil = Expression::make_nil(location);
7840         tree nil_tree = nil->get_tree(context);
7841         tree empty_nil_tree = Expression::convert_for_assignment(context,
7842                                                                  empty,
7843                                                                  nil_type,
7844                                                                  nil_tree,
7845                                                                  location);
7846
7847         // We need to handle a deferred call to recover specially,
7848         // because it changes whether it can recover a panic or not.
7849         // See test7 in test/recover1.go.
7850         tree call;
7851         if (this->is_deferred())
7852           {
7853             static tree deferred_recover_fndecl;
7854             call = Gogo::call_builtin(&deferred_recover_fndecl,
7855                                       location,
7856                                       "__go_deferred_recover",
7857                                       0,
7858                                       empty_tree);
7859           }
7860         else
7861           {
7862             static tree recover_fndecl;
7863             call = Gogo::call_builtin(&recover_fndecl,
7864                                       location,
7865                                       "__go_recover",
7866                                       0,
7867                                       empty_tree);
7868           }
7869         if (call == error_mark_node)
7870           return error_mark_node;
7871         return fold_build3_loc(location, COND_EXPR, empty_tree, arg_tree,
7872                                call, empty_nil_tree);
7873       }
7874
7875     case BUILTIN_CLOSE:
7876     case BUILTIN_CLOSED:
7877       {
7878         const Expression_list* args = this->args();
7879         gcc_assert(args != NULL && args->size() == 1);
7880         Expression* arg = args->front();
7881         tree arg_tree = arg->get_tree(context);
7882         if (arg_tree == error_mark_node)
7883           return error_mark_node;
7884         if (this->code_ == BUILTIN_CLOSE)
7885           {
7886             static tree close_fndecl;
7887             return Gogo::call_builtin(&close_fndecl,
7888                                       location,
7889                                       "__go_builtin_close",
7890                                       1,
7891                                       void_type_node,
7892                                       TREE_TYPE(arg_tree),
7893                                       arg_tree);
7894           }
7895         else
7896           {
7897             static tree closed_fndecl;
7898             return Gogo::call_builtin(&closed_fndecl,
7899                                       location,
7900                                       "__go_builtin_closed",
7901                                       1,
7902                                       boolean_type_node,
7903                                       TREE_TYPE(arg_tree),
7904                                       arg_tree);
7905           }
7906       }
7907
7908     case BUILTIN_SIZEOF:
7909     case BUILTIN_OFFSETOF:
7910     case BUILTIN_ALIGNOF:
7911       {
7912         mpz_t val;
7913         mpz_init(val);
7914         Type* dummy;
7915         bool b = this->integer_constant_value(true, val, &dummy);
7916         gcc_assert(b);
7917         tree type = Type::lookup_integer_type("int")->get_tree(gogo);
7918         tree ret = Expression::integer_constant_tree(val, type);
7919         mpz_clear(val);
7920         return ret;
7921       }
7922
7923     case BUILTIN_COPY:
7924       {
7925         const Expression_list* args = this->args();
7926         gcc_assert(args != NULL && args->size() == 2);
7927         Expression* arg1 = args->front();
7928         Expression* arg2 = args->back();
7929
7930         tree arg1_tree = arg1->get_tree(context);
7931         tree arg2_tree = arg2->get_tree(context);
7932         if (arg1_tree == error_mark_node || arg2_tree == error_mark_node)
7933           return error_mark_node;
7934
7935         Type* arg1_type = arg1->type();
7936         Array_type* at = arg1_type->array_type();
7937         arg1_tree = save_expr(arg1_tree);
7938         tree arg1_val = at->value_pointer_tree(gogo, arg1_tree);
7939         tree arg1_len = at->length_tree(gogo, arg1_tree);
7940         if (arg1_val == error_mark_node || arg1_len == error_mark_node)
7941           return error_mark_node;
7942
7943         Type* arg2_type = arg2->type();
7944         tree arg2_val;
7945         tree arg2_len;
7946         if (arg2_type->is_open_array_type())
7947           {
7948             at = arg2_type->array_type();
7949             arg2_tree = save_expr(arg2_tree);
7950             arg2_val = at->value_pointer_tree(gogo, arg2_tree);
7951             arg2_len = at->length_tree(gogo, arg2_tree);
7952           }
7953         else
7954           {
7955             arg2_tree = save_expr(arg2_tree);
7956             arg2_val = String_type::bytes_tree(gogo, arg2_tree);
7957             arg2_len = String_type::length_tree(gogo, arg2_tree);
7958           }
7959         if (arg2_val == error_mark_node || arg2_len == error_mark_node)
7960           return error_mark_node;
7961
7962         arg1_len = save_expr(arg1_len);
7963         arg2_len = save_expr(arg2_len);
7964         tree len = fold_build3_loc(location, COND_EXPR, TREE_TYPE(arg1_len),
7965                                    fold_build2_loc(location, LT_EXPR,
7966                                                    boolean_type_node,
7967                                                    arg1_len, arg2_len),
7968                                    arg1_len, arg2_len);
7969         len = save_expr(len);
7970
7971         Type* element_type = at->element_type();
7972         tree element_type_tree = element_type->get_tree(gogo);
7973         if (element_type_tree == error_mark_node)
7974           return error_mark_node;
7975         tree element_size = TYPE_SIZE_UNIT(element_type_tree);
7976         tree bytecount = fold_convert_loc(location, TREE_TYPE(element_size),
7977                                           len);
7978         bytecount = fold_build2_loc(location, MULT_EXPR,
7979                                     TREE_TYPE(element_size),
7980                                     bytecount, element_size);
7981         bytecount = fold_convert_loc(location, size_type_node, bytecount);
7982
7983         arg1_val = fold_convert_loc(location, ptr_type_node, arg1_val);
7984         arg2_val = fold_convert_loc(location, ptr_type_node, arg2_val);
7985
7986         static tree copy_fndecl;
7987         tree call = Gogo::call_builtin(&copy_fndecl,
7988                                        location,
7989                                        "__go_copy",
7990                                        3,
7991                                        void_type_node,
7992                                        ptr_type_node,
7993                                        arg1_val,
7994                                        ptr_type_node,
7995                                        arg2_val,
7996                                        size_type_node,
7997                                        bytecount);
7998         if (call == error_mark_node)
7999           return error_mark_node;
8000
8001         return fold_build2_loc(location, COMPOUND_EXPR, TREE_TYPE(len),
8002                                call, len);
8003       }
8004
8005     case BUILTIN_APPEND:
8006       {
8007         const Expression_list* args = this->args();
8008         gcc_assert(args != NULL && args->size() == 2);
8009         Expression* arg1 = args->front();
8010         Expression* arg2 = args->back();
8011
8012         tree arg1_tree = arg1->get_tree(context);
8013         tree arg2_tree = arg2->get_tree(context);
8014         if (arg1_tree == error_mark_node || arg2_tree == error_mark_node)
8015           return error_mark_node;
8016
8017         Array_type* at = arg1->type()->array_type();
8018         Type* element_type = at->element_type();
8019
8020         arg2_tree = Expression::convert_for_assignment(context, at,
8021                                                        arg2->type(),
8022                                                        arg2_tree,
8023                                                        location);
8024         if (arg2_tree == error_mark_node)
8025           return error_mark_node;
8026
8027         arg2_tree = save_expr(arg2_tree);
8028         tree arg2_val = at->value_pointer_tree(gogo, arg2_tree);
8029         tree arg2_len = at->length_tree(gogo, arg2_tree);
8030         if (arg2_val == error_mark_node || arg2_len == error_mark_node)
8031           return error_mark_node;
8032         arg2_val = fold_convert_loc(location, ptr_type_node, arg2_val);
8033         arg2_len = fold_convert_loc(location, size_type_node, arg2_len);
8034
8035         tree element_type_tree = element_type->get_tree(gogo);
8036         if (element_type_tree == error_mark_node)
8037           return error_mark_node;
8038         tree element_size = TYPE_SIZE_UNIT(element_type_tree);
8039         element_size = fold_convert_loc(location, size_type_node,
8040                                         element_size);
8041
8042         // We rebuild the decl each time since the slice types may
8043         // change.
8044         tree append_fndecl = NULL_TREE;
8045         return Gogo::call_builtin(&append_fndecl,
8046                                   location,
8047                                   "__go_append",
8048                                   4,
8049                                   TREE_TYPE(arg1_tree),
8050                                   TREE_TYPE(arg1_tree),
8051                                   arg1_tree,
8052                                   ptr_type_node,
8053                                   arg2_val,
8054                                   size_type_node,
8055                                   arg2_len,
8056                                   size_type_node,
8057                                   element_size);
8058       }
8059
8060     case BUILTIN_REAL:
8061     case BUILTIN_IMAG:
8062       {
8063         const Expression_list* args = this->args();
8064         gcc_assert(args != NULL && args->size() == 1);
8065         Expression* arg = args->front();
8066         tree arg_tree = arg->get_tree(context);
8067         if (arg_tree == error_mark_node)
8068           return error_mark_node;
8069         gcc_assert(COMPLEX_FLOAT_TYPE_P(TREE_TYPE(arg_tree)));
8070         if (this->code_ == BUILTIN_REAL)
8071           return fold_build1_loc(location, REALPART_EXPR,
8072                                  TREE_TYPE(TREE_TYPE(arg_tree)),
8073                                  arg_tree);
8074         else
8075           return fold_build1_loc(location, IMAGPART_EXPR,
8076                                  TREE_TYPE(TREE_TYPE(arg_tree)),
8077                                  arg_tree);
8078       }
8079
8080     case BUILTIN_CMPLX:
8081       {
8082         const Expression_list* args = this->args();
8083         gcc_assert(args != NULL && args->size() == 2);
8084         tree r = args->front()->get_tree(context);
8085         tree i = args->back()->get_tree(context);
8086         if (r == error_mark_node || i == error_mark_node)
8087           return error_mark_node;
8088         gcc_assert(TYPE_MAIN_VARIANT(TREE_TYPE(r))
8089                    == TYPE_MAIN_VARIANT(TREE_TYPE(i)));
8090         gcc_assert(SCALAR_FLOAT_TYPE_P(TREE_TYPE(r)));
8091         return fold_build2_loc(location, COMPLEX_EXPR,
8092                                build_complex_type(TREE_TYPE(r)),
8093                                r, i);
8094       }
8095
8096     default:
8097       gcc_unreachable();
8098     }
8099 }
8100
8101 // We have to support exporting a builtin call expression, because
8102 // code can set a constant to the result of a builtin expression.
8103
8104 void
8105 Builtin_call_expression::do_export(Export* exp) const
8106 {
8107   bool ok = false;
8108
8109   mpz_t val;
8110   mpz_init(val);
8111   Type* dummy;
8112   if (this->integer_constant_value(true, val, &dummy))
8113     {
8114       Integer_expression::export_integer(exp, val);
8115       ok = true;
8116     }
8117   mpz_clear(val);
8118
8119   if (!ok)
8120     {
8121       mpfr_t fval;
8122       mpfr_init(fval);
8123       if (this->float_constant_value(fval, &dummy))
8124         {
8125           Float_expression::export_float(exp, fval);
8126           ok = true;
8127         }
8128       mpfr_clear(fval);
8129     }
8130
8131   if (!ok)
8132     {
8133       mpfr_t real;
8134       mpfr_t imag;
8135       mpfr_init(real);
8136       mpfr_init(imag);
8137       if (this->complex_constant_value(real, imag, &dummy))
8138         {
8139           Complex_expression::export_complex(exp, real, imag);
8140           ok = true;
8141         }
8142       mpfr_clear(real);
8143       mpfr_clear(imag);
8144     }
8145
8146   if (!ok)
8147     {
8148       error_at(this->location(), "value is not constant");
8149       return;
8150     }
8151
8152   // A trailing space lets us reliably identify the end of the number.
8153   exp->write_c_string(" ");
8154 }
8155
8156 // Class Call_expression.
8157
8158 // Traversal.
8159
8160 int
8161 Call_expression::do_traverse(Traverse* traverse)
8162 {
8163   if (Expression::traverse(&this->fn_, traverse) == TRAVERSE_EXIT)
8164     return TRAVERSE_EXIT;
8165   if (this->args_ != NULL)
8166     {
8167       if (this->args_->traverse(traverse) == TRAVERSE_EXIT)
8168         return TRAVERSE_EXIT;
8169     }
8170   return TRAVERSE_CONTINUE;
8171 }
8172
8173 // Lower a call statement.
8174
8175 Expression*
8176 Call_expression::do_lower(Gogo* gogo, Named_object* function, int)
8177 {
8178   // A type case can look like a function call.
8179   if (this->fn_->is_type_expression()
8180       && this->args_ != NULL
8181       && this->args_->size() == 1)
8182     return Expression::make_cast(this->fn_->type(), this->args_->front(),
8183                                  this->location());
8184
8185   // Recognize a call to a builtin function.
8186   Func_expression* fne = this->fn_->func_expression();
8187   if (fne != NULL
8188       && fne->named_object()->is_function_declaration()
8189       && fne->named_object()->func_declaration_value()->type()->is_builtin())
8190     return new Builtin_call_expression(gogo, this->fn_, this->args_,
8191                                        this->is_varargs_, this->location());
8192
8193   // Handle an argument which is a call to a function which returns
8194   // multiple results.
8195   if (this->args_ != NULL
8196       && this->args_->size() == 1
8197       && this->args_->front()->call_expression() != NULL
8198       && this->fn_->type()->function_type() != NULL)
8199     {
8200       Function_type* fntype = this->fn_->type()->function_type();
8201       size_t rc = this->args_->front()->call_expression()->result_count();
8202       if (rc > 1
8203           && fntype->parameters() != NULL
8204           && (fntype->parameters()->size() == rc
8205               || (fntype->is_varargs()
8206                   && fntype->parameters()->size() - 1 <= rc)))
8207         {
8208           Call_expression* call = this->args_->front()->call_expression();
8209           Expression_list* args = new Expression_list;
8210           for (size_t i = 0; i < rc; ++i)
8211             args->push_back(Expression::make_call_result(call, i));
8212           // We can't return a new call expression here, because this
8213           // one may be referenced by Call_result expressions.  FIXME.
8214           delete this->args_;
8215           this->args_ = args;
8216         }
8217     }
8218
8219   // Handle a call to a varargs function by packaging up the extra
8220   // parameters.
8221   if (this->fn_->type()->function_type() != NULL
8222       && this->fn_->type()->function_type()->is_varargs())
8223     {
8224       Function_type* fntype = this->fn_->type()->function_type();
8225       const Typed_identifier_list* parameters = fntype->parameters();
8226       gcc_assert(parameters != NULL && !parameters->empty());
8227       Type* varargs_type = parameters->back().type();
8228       return this->lower_varargs(gogo, function, varargs_type,
8229                                  parameters->size());
8230     }
8231
8232   return this;
8233 }
8234
8235 // Lower a call to a varargs function.  FUNCTION is the function in
8236 // which the call occurs--it's not the function we are calling.
8237 // VARARGS_TYPE is the type of the varargs parameter, a slice type.
8238 // PARAM_COUNT is the number of parameters of the function we are
8239 // calling; the last of these parameters will be the varargs
8240 // parameter.
8241
8242 Expression*
8243 Call_expression::lower_varargs(Gogo* gogo, Named_object* function,
8244                                Type* varargs_type, size_t param_count)
8245 {
8246   if (this->varargs_are_lowered_)
8247     return this;
8248
8249   source_location loc = this->location();
8250
8251   gcc_assert(param_count > 0);
8252   gcc_assert(varargs_type->is_open_array_type());
8253
8254   size_t arg_count = this->args_ == NULL ? 0 : this->args_->size();
8255   if (arg_count < param_count - 1)
8256     {
8257       // Not enough arguments; will be caught in check_types.
8258       return this;
8259     }
8260
8261   Expression_list* old_args = this->args_;
8262   Expression_list* new_args = new Expression_list();
8263   bool push_empty_arg = false;
8264   if (old_args == NULL || old_args->empty())
8265     {
8266       gcc_assert(param_count == 1);
8267       push_empty_arg = true;
8268     }
8269   else
8270     {
8271       Expression_list::const_iterator pa;
8272       int i = 1;
8273       for (pa = old_args->begin(); pa != old_args->end(); ++pa, ++i)
8274         {
8275           if (static_cast<size_t>(i) == param_count)
8276             break;
8277           new_args->push_back(*pa);
8278         }
8279
8280       // We have reached the varargs parameter.
8281
8282       bool issued_error = false;
8283       if (pa == old_args->end())
8284         push_empty_arg = true;
8285       else if (pa + 1 == old_args->end() && this->is_varargs_)
8286         new_args->push_back(*pa);
8287       else if (this->is_varargs_)
8288         {
8289           this->report_error(_("too many arguments"));
8290           return this;
8291         }
8292       else if (pa + 1 == old_args->end()
8293                && this->is_compatible_varargs_argument(function, *pa,
8294                                                        varargs_type,
8295                                                        &issued_error))
8296         new_args->push_back(*pa);
8297       else
8298         {
8299           Type* element_type = varargs_type->array_type()->element_type();
8300           Expression_list* vals = new Expression_list;
8301           for (; pa != old_args->end(); ++pa, ++i)
8302             {
8303               // Check types here so that we get a better message.
8304               Type* patype = (*pa)->type();
8305               source_location paloc = (*pa)->location();
8306               if (!this->check_argument_type(i, element_type, patype,
8307                                              paloc, issued_error))
8308                 continue;
8309               vals->push_back(*pa);
8310             }
8311           Expression* val =
8312             Expression::make_slice_composite_literal(varargs_type, vals, loc);
8313           new_args->push_back(val);
8314         }
8315     }
8316
8317   if (push_empty_arg)
8318     new_args->push_back(Expression::make_nil(loc));
8319
8320   // We can't return a new call expression here, because this one may
8321   // be referenced by Call_result expressions.  FIXME.
8322   if (old_args != NULL)
8323     delete old_args;
8324   this->args_ = new_args;
8325   this->varargs_are_lowered_ = true;
8326
8327   // Lower all the new subexpressions.
8328   Expression* ret = this;
8329   gogo->lower_expression(function, &ret);
8330   gcc_assert(ret == this);
8331   return ret;
8332 }
8333
8334 // Return true if ARG is a varargs argment which should be passed to
8335 // the varargs parameter of type PARAM_TYPE without wrapping.  ARG
8336 // will be the last argument passed in the call, and PARAM_TYPE will
8337 // be the type of the last parameter of the varargs function being
8338 // called.
8339
8340 bool
8341 Call_expression::is_compatible_varargs_argument(Named_object* function,
8342                                                 Expression* arg,
8343                                                 Type* param_type,
8344                                                 bool* issued_error)
8345 {
8346   *issued_error = false;
8347
8348   Type* var_type = NULL;
8349
8350   // The simple case is passing the varargs parameter of the caller.
8351   Var_expression* ve = arg->var_expression();
8352   if (ve != NULL && ve->named_object()->is_variable())
8353     {
8354       Variable* var = ve->named_object()->var_value();
8355       if (var->is_varargs_parameter())
8356         var_type = var->type();
8357     }
8358
8359   // The complex case is passing the varargs parameter of some
8360   // enclosing function.  This will look like passing down *c.f where
8361   // c is the closure variable and f is a field in the closure.
8362   if (function != NULL
8363       && function->func_value()->needs_closure()
8364       && arg->classification() == EXPRESSION_UNARY)
8365     {
8366       Unary_expression* ue = static_cast<Unary_expression*>(arg);
8367       if (ue->op() == OPERATOR_MULT)
8368         {
8369           Field_reference_expression* fre =
8370             ue->operand()->deref()->field_reference_expression();
8371           if (fre != NULL)
8372             {
8373               Var_expression* ve = fre->expr()->deref()->var_expression();
8374               if (ve != NULL)
8375                 {
8376                   Named_object* no = ve->named_object();
8377                   Function* f = function->func_value();
8378                   if (no == f->closure_var())
8379                     {
8380                       // At this point we know that this indeed a
8381                       // reference to some enclosing variable.  Now we
8382                       // need to figure out whether that variable is a
8383                       // varargs parameter.
8384                       Named_object* enclosing =
8385                         f->enclosing_var(fre->field_index());
8386                       Variable* var = enclosing->var_value();
8387                       if (var->is_varargs_parameter())
8388                         var_type = var->type();
8389                     }
8390                 }
8391             }
8392         }
8393     }
8394
8395   if (var_type == NULL)
8396     return false;
8397
8398   // We only match if the parameter is the same, with an identical
8399   // type.
8400   Array_type* var_at = var_type->array_type();
8401   gcc_assert(var_at != NULL);
8402   Array_type* param_at = param_type->array_type();
8403   if (param_at != NULL
8404       && Type::are_identical(var_at->element_type(),
8405                              param_at->element_type(), true, NULL))
8406     return true;
8407   error_at(arg->location(), "... mismatch: passing ...T as ...");
8408   *issued_error = true;
8409   return false;
8410 }
8411
8412 // Get the function type.  Returns NULL if we don't know the type.  If
8413 // this returns NULL, and if_ERROR is true, issues an error.
8414
8415 Function_type*
8416 Call_expression::get_function_type() const
8417 {
8418   return this->fn_->type()->function_type();
8419 }
8420
8421 // Return the number of values which this call will return.
8422
8423 size_t
8424 Call_expression::result_count() const
8425 {
8426   const Function_type* fntype = this->get_function_type();
8427   if (fntype == NULL)
8428     return 0;
8429   if (fntype->results() == NULL)
8430     return 0;
8431   return fntype->results()->size();
8432 }
8433
8434 // Return whether this is a call to the predeclared function recover.
8435
8436 bool
8437 Call_expression::is_recover_call() const
8438 {
8439   return this->do_is_recover_call();
8440 }
8441
8442 // Set the argument to the recover function.
8443
8444 void
8445 Call_expression::set_recover_arg(Expression* arg)
8446 {
8447   this->do_set_recover_arg(arg);
8448 }
8449
8450 // Virtual functions also implemented by Builtin_call_expression.
8451
8452 bool
8453 Call_expression::do_is_recover_call() const
8454 {
8455   return false;
8456 }
8457
8458 void
8459 Call_expression::do_set_recover_arg(Expression*)
8460 {
8461   gcc_unreachable();
8462 }
8463
8464 // Get the type.
8465
8466 Type*
8467 Call_expression::do_type()
8468 {
8469   if (this->type_ != NULL)
8470     return this->type_;
8471
8472   Type* ret;
8473   Function_type* fntype = this->get_function_type();
8474   if (fntype == NULL)
8475     return Type::make_error_type();
8476
8477   const Typed_identifier_list* results = fntype->results();
8478   if (results == NULL)
8479     ret = Type::make_void_type();
8480   else if (results->size() == 1)
8481     ret = results->begin()->type();
8482   else
8483     ret = Type::make_call_multiple_result_type(this);
8484
8485   this->type_ = ret;
8486
8487   return this->type_;
8488 }
8489
8490 // Determine types for a call expression.  We can use the function
8491 // parameter types to set the types of the arguments.
8492
8493 void
8494 Call_expression::do_determine_type(const Type_context*)
8495 {
8496   this->fn_->determine_type_no_context();
8497   Function_type* fntype = this->get_function_type();
8498   const Typed_identifier_list* parameters = NULL;
8499   if (fntype != NULL)
8500     parameters = fntype->parameters();
8501   if (this->args_ != NULL)
8502     {
8503       Typed_identifier_list::const_iterator pt;
8504       if (parameters != NULL)
8505         pt = parameters->begin();
8506       for (Expression_list::const_iterator pa = this->args_->begin();
8507            pa != this->args_->end();
8508            ++pa)
8509         {
8510           if (parameters != NULL && pt != parameters->end())
8511             {
8512               Type_context subcontext(pt->type(), false);
8513               (*pa)->determine_type(&subcontext);
8514               ++pt;
8515             }
8516           else
8517             (*pa)->determine_type_no_context();
8518         }
8519     }
8520 }
8521
8522 // Check types for parameter I.
8523
8524 bool
8525 Call_expression::check_argument_type(int i, const Type* parameter_type,
8526                                      const Type* argument_type,
8527                                      source_location argument_location,
8528                                      bool issued_error)
8529 {
8530   std::string reason;
8531   if (!Type::are_assignable(parameter_type, argument_type, &reason))
8532     {
8533       if (!issued_error)
8534         {
8535           if (reason.empty())
8536             error_at(argument_location, "argument %d has incompatible type", i);
8537           else
8538             error_at(argument_location,
8539                      "argument %d has incompatible type (%s)",
8540                      i, reason.c_str());
8541         }
8542       this->set_is_error();
8543       return false;
8544     }
8545   return true;
8546 }
8547
8548 // Check types.
8549
8550 void
8551 Call_expression::do_check_types(Gogo*)
8552 {
8553   Function_type* fntype = this->get_function_type();
8554   if (fntype == NULL)
8555     {
8556       if (!this->fn_->type()->is_error_type())
8557         this->report_error(_("expected function"));
8558       return;
8559     }
8560
8561   if (fntype->is_method())
8562     {
8563       // We don't support pointers to methods, so the function has to
8564       // be a bound method expression.
8565       Bound_method_expression* bme = this->fn_->bound_method_expression();
8566       if (bme == NULL)
8567         {
8568           this->report_error(_("method call without object"));
8569           return;
8570         }
8571       Type* first_arg_type = bme->first_argument()->type();
8572       if (first_arg_type->points_to() == NULL)
8573         {
8574           // When passing a value, we need to check that we are
8575           // permitted to copy it.
8576           std::string reason;
8577           if (!Type::are_assignable(fntype->receiver()->type(),
8578                                     first_arg_type, &reason))
8579             {
8580               if (reason.empty())
8581                 this->report_error(_("incompatible type for receiver"));
8582               else
8583                 {
8584                   error_at(this->location(),
8585                            "incompatible type for receiver (%s)",
8586                            reason.c_str());
8587                   this->set_is_error();
8588                 }
8589             }
8590         }
8591     }
8592
8593   // Note that varargs was handled by the lower_varargs() method, so
8594   // we don't have to worry about it here.
8595
8596   const Typed_identifier_list* parameters = fntype->parameters();
8597   if (this->args_ == NULL)
8598     {
8599       if (parameters != NULL && !parameters->empty())
8600         this->report_error(_("not enough arguments"));
8601     }
8602   else if (parameters == NULL)
8603     this->report_error(_("too many arguments"));
8604   else
8605     {
8606       int i = 0;
8607       Typed_identifier_list::const_iterator pt = parameters->begin();
8608       for (Expression_list::const_iterator pa = this->args_->begin();
8609            pa != this->args_->end();
8610            ++pa, ++pt, ++i)
8611         {
8612           if (pt == parameters->end())
8613             {
8614               this->report_error(_("too many arguments"));
8615               return;
8616             }
8617           this->check_argument_type(i + 1, pt->type(), (*pa)->type(),
8618                                     (*pa)->location(), false);
8619         }
8620       if (pt != parameters->end())
8621         this->report_error(_("not enough arguments"));
8622     }
8623 }
8624
8625 // Return whether we have to use a temporary variable to ensure that
8626 // we evaluate this call expression in order.  If the call returns no
8627 // results then it will inevitably be executed last.  If the call
8628 // returns more than one result then it will be used with Call_result
8629 // expressions.  So we only have to use a temporary variable if the
8630 // call returns exactly one result.
8631
8632 bool
8633 Call_expression::do_must_eval_in_order() const
8634 {
8635   return this->result_count() == 1;
8636 }
8637
8638 // Get the function and the first argument to use when calling a bound
8639 // method.
8640
8641 tree
8642 Call_expression::bound_method_function(Translate_context* context,
8643                                        Bound_method_expression* bound_method,
8644                                        tree* first_arg_ptr)
8645 {
8646   Expression* first_argument = bound_method->first_argument();
8647   tree first_arg = first_argument->get_tree(context);
8648   if (first_arg == error_mark_node)
8649     return error_mark_node;
8650
8651   // We always pass a pointer to the first argument when calling a
8652   // method.
8653   if (first_argument->type()->points_to() == NULL)
8654     {
8655       tree pointer_to_arg_type = build_pointer_type(TREE_TYPE(first_arg));
8656       if (TREE_ADDRESSABLE(TREE_TYPE(first_arg))
8657           || DECL_P(first_arg)
8658           || TREE_CODE(first_arg) == INDIRECT_REF
8659           || TREE_CODE(first_arg) == COMPONENT_REF)
8660         {
8661           first_arg = build_fold_addr_expr(first_arg);
8662           if (DECL_P(first_arg))
8663             TREE_ADDRESSABLE(first_arg) = 1;
8664         }
8665       else
8666         {
8667           tree tmp = create_tmp_var(TREE_TYPE(first_arg),
8668                                     get_name(first_arg));
8669           DECL_IGNORED_P(tmp) = 0;
8670           DECL_INITIAL(tmp) = first_arg;
8671           first_arg = build2(COMPOUND_EXPR, pointer_to_arg_type,
8672                              build1(DECL_EXPR, void_type_node, tmp),
8673                              build_fold_addr_expr(tmp));
8674           TREE_ADDRESSABLE(tmp) = 1;
8675         }
8676       if (first_arg == error_mark_node)
8677         return error_mark_node;
8678     }
8679
8680   Type* fatype = bound_method->first_argument_type();
8681   if (fatype != NULL)
8682     {
8683       if (fatype->points_to() == NULL)
8684         fatype = Type::make_pointer_type(fatype);
8685       first_arg = fold_convert(fatype->get_tree(context->gogo()), first_arg);
8686       if (first_arg == error_mark_node
8687           || TREE_TYPE(first_arg) == error_mark_node)
8688         return error_mark_node;
8689     }
8690
8691   *first_arg_ptr = first_arg;
8692
8693   return bound_method->method()->get_tree(context);
8694 }
8695
8696 // Get the function and the first argument to use when calling an
8697 // interface method.
8698
8699 tree
8700 Call_expression::interface_method_function(
8701     Translate_context* context,
8702     Interface_field_reference_expression* interface_method,
8703     tree* first_arg_ptr)
8704 {
8705   tree expr = interface_method->expr()->get_tree(context);
8706   if (expr == error_mark_node)
8707     return error_mark_node;
8708   expr = save_expr(expr);
8709   tree first_arg = interface_method->get_underlying_object_tree(context, expr);
8710   if (first_arg == error_mark_node)
8711     return error_mark_node;
8712   *first_arg_ptr = first_arg;
8713   return interface_method->get_function_tree(context, expr);
8714 }
8715
8716 // Build the call expression.
8717
8718 tree
8719 Call_expression::do_get_tree(Translate_context* context)
8720 {
8721   if (this->tree_ != NULL_TREE)
8722     return this->tree_;
8723
8724   Function_type* fntype = this->get_function_type();
8725   if (fntype == NULL)
8726     return error_mark_node;
8727
8728   if (this->fn_->is_error_expression())
8729     return error_mark_node;
8730
8731   Gogo* gogo = context->gogo();
8732   source_location location = this->location();
8733
8734   Func_expression* func = this->fn_->func_expression();
8735   Bound_method_expression* bound_method = this->fn_->bound_method_expression();
8736   Interface_field_reference_expression* interface_method =
8737     this->fn_->interface_field_reference_expression();
8738   const bool has_closure = func != NULL && func->closure() != NULL;
8739   const bool is_method = bound_method != NULL || interface_method != NULL;
8740   gcc_assert(!fntype->is_method() || is_method);
8741
8742   int nargs;
8743   tree* args;
8744   if (this->args_ == NULL || this->args_->empty())
8745     {
8746       nargs = is_method ? 1 : 0;
8747       args = nargs == 0 ? NULL : new tree[nargs];
8748     }
8749   else
8750     {
8751       const Typed_identifier_list* params = fntype->parameters();
8752       gcc_assert(params != NULL);
8753
8754       nargs = this->args_->size();
8755       int i = is_method ? 1 : 0;
8756       nargs += i;
8757       args = new tree[nargs];
8758
8759       Typed_identifier_list::const_iterator pp = params->begin();
8760       Expression_list::const_iterator pe;
8761       for (pe = this->args_->begin();
8762            pe != this->args_->end();
8763            ++pe, ++pp, ++i)
8764         {
8765           gcc_assert(pp != params->end());
8766           tree arg_val = (*pe)->get_tree(context);
8767           args[i] = Expression::convert_for_assignment(context,
8768                                                        pp->type(),
8769                                                        (*pe)->type(),
8770                                                        arg_val,
8771                                                        location);
8772           if (args[i] == error_mark_node)
8773             {
8774               delete[] args;
8775               return error_mark_node;
8776             }
8777         }
8778       gcc_assert(pp == params->end());
8779       gcc_assert(i == nargs);
8780     }
8781
8782   tree rettype = TREE_TYPE(TREE_TYPE(fntype->get_tree(gogo)));
8783   if (rettype == error_mark_node)
8784     {
8785       delete[] args;
8786       return error_mark_node;
8787     }
8788
8789   tree fn;
8790   if (has_closure)
8791     fn = func->get_tree_without_closure(gogo);
8792   else if (!is_method)
8793     fn = this->fn_->get_tree(context);
8794   else if (bound_method != NULL)
8795     fn = this->bound_method_function(context, bound_method, &args[0]);
8796   else if (interface_method != NULL)
8797     fn = this->interface_method_function(context, interface_method, &args[0]);
8798   else
8799     gcc_unreachable();
8800
8801   if (fn == error_mark_node || TREE_TYPE(fn) == error_mark_node)
8802     {
8803       delete[] args;
8804       return error_mark_node;
8805     }
8806
8807   // This is to support builtin math functions when using 80387 math.
8808   tree fndecl = fn;
8809   if (TREE_CODE(fndecl) == ADDR_EXPR)
8810     fndecl = TREE_OPERAND(fndecl, 0);
8811   tree excess_type = NULL_TREE;
8812   if (DECL_P(fndecl)
8813       && DECL_IS_BUILTIN(fndecl)
8814       && DECL_BUILT_IN_CLASS(fndecl) == BUILT_IN_NORMAL
8815       && nargs > 0
8816       && ((SCALAR_FLOAT_TYPE_P(rettype)
8817            && SCALAR_FLOAT_TYPE_P(TREE_TYPE(args[0])))
8818           || (COMPLEX_FLOAT_TYPE_P(rettype)
8819               && COMPLEX_FLOAT_TYPE_P(TREE_TYPE(args[0])))))
8820     {
8821       excess_type = excess_precision_type(TREE_TYPE(args[0]));
8822       if (excess_type != NULL_TREE)
8823         {
8824           tree excess_fndecl = mathfn_built_in(excess_type,
8825                                                DECL_FUNCTION_CODE(fndecl));
8826           if (excess_fndecl == NULL_TREE)
8827             excess_type = NULL_TREE;
8828           else
8829             {
8830               fn = build_fold_addr_expr_loc(location, excess_fndecl);
8831               for (int i = 0; i < nargs; ++i)
8832                 args[i] = ::convert(excess_type, args[i]);
8833             }
8834         }
8835     }
8836
8837   tree ret = build_call_array(excess_type != NULL_TREE ? excess_type : rettype,
8838                               fn, nargs, args);
8839   delete[] args;
8840
8841   SET_EXPR_LOCATION(ret, location);
8842
8843   if (has_closure)
8844     {
8845       tree closure_tree = func->closure()->get_tree(context);
8846       if (closure_tree != error_mark_node)
8847         CALL_EXPR_STATIC_CHAIN(ret) = closure_tree;
8848     }
8849
8850   // If this is a recursive function type which returns itself, as in
8851   //   type F func() F
8852   // we have used ptr_type_node for the return type.  Add a cast here
8853   // to the correct type.
8854   if (TREE_TYPE(ret) == ptr_type_node)
8855     {
8856       tree t = this->type()->get_tree(gogo);
8857       ret = fold_convert_loc(location, t, ret);
8858     }
8859
8860   if (excess_type != NULL_TREE)
8861     {
8862       // Calling convert here can undo our excess precision change.
8863       // That may or may not be a bug in convert_to_real.
8864       ret = build1(NOP_EXPR, rettype, ret);
8865     }
8866
8867   // If there is more than one result, we will refer to the call
8868   // multiple times.
8869   if (fntype->results() != NULL && fntype->results()->size() > 1)
8870     ret = save_expr(ret);
8871
8872   this->tree_ = ret;
8873
8874   return ret;
8875 }
8876
8877 // Make a call expression.
8878
8879 Call_expression*
8880 Expression::make_call(Expression* fn, Expression_list* args, bool is_varargs,
8881                       source_location location)
8882 {
8883   return new Call_expression(fn, args, is_varargs, location);
8884 }
8885
8886 // A single result from a call which returns multiple results.
8887
8888 class Call_result_expression : public Expression
8889 {
8890  public:
8891   Call_result_expression(Call_expression* call, unsigned int index)
8892     : Expression(EXPRESSION_CALL_RESULT, call->location()),
8893       call_(call), index_(index)
8894   { }
8895
8896  protected:
8897   int
8898   do_traverse(Traverse*);
8899
8900   Type*
8901   do_type();
8902
8903   void
8904   do_determine_type(const Type_context*);
8905
8906   void
8907   do_check_types(Gogo*);
8908
8909   Expression*
8910   do_copy()
8911   {
8912     return new Call_result_expression(this->call_->call_expression(),
8913                                       this->index_);
8914   }
8915
8916   bool
8917   do_must_eval_in_order() const
8918   { return true; }
8919
8920   tree
8921   do_get_tree(Translate_context*);
8922
8923  private:
8924   // The underlying call expression.
8925   Expression* call_;
8926   // Which result we want.
8927   unsigned int index_;
8928 };
8929
8930 // Traverse a call result.
8931
8932 int
8933 Call_result_expression::do_traverse(Traverse* traverse)
8934 {
8935   if (traverse->remember_expression(this->call_))
8936     {
8937       // We have already traversed the call expression.
8938       return TRAVERSE_CONTINUE;
8939     }
8940   return Expression::traverse(&this->call_, traverse);
8941 }
8942
8943 // Get the type.
8944
8945 Type*
8946 Call_result_expression::do_type()
8947 {
8948   if (this->classification() == EXPRESSION_ERROR)
8949     return Type::make_error_type();
8950
8951   // THIS->CALL_ can be replaced with a temporary reference due to
8952   // Call_expression::do_must_eval_in_order when there is an error.
8953   Call_expression* ce = this->call_->call_expression();
8954   if (ce == NULL)
8955     {
8956       this->set_is_error();
8957       return Type::make_error_type();
8958     }
8959   Function_type* fntype = ce->get_function_type();
8960   if (fntype == NULL)
8961     {
8962       this->set_is_error();
8963       return Type::make_error_type();
8964     }
8965   const Typed_identifier_list* results = fntype->results();
8966   if (results == NULL)
8967     {
8968       this->report_error(_("number of results does not match "
8969                            "number of values"));
8970       return Type::make_error_type();
8971     }
8972   Typed_identifier_list::const_iterator pr = results->begin();
8973   for (unsigned int i = 0; i < this->index_; ++i)
8974     {
8975       if (pr == results->end())
8976         break;
8977       ++pr;
8978     }
8979   if (pr == results->end())
8980     {
8981       this->report_error(_("number of results does not match "
8982                            "number of values"));
8983       return Type::make_error_type();
8984     }
8985   return pr->type();
8986 }
8987
8988 // Check the type.  Just make sure that we trigger the warning in
8989 // do_type.
8990
8991 void
8992 Call_result_expression::do_check_types(Gogo*)
8993 {
8994   this->type();
8995 }
8996
8997 // Determine the type.  We have nothing to do here, but the 0 result
8998 // needs to pass down to the caller.
8999
9000 void
9001 Call_result_expression::do_determine_type(const Type_context*)
9002 {
9003   if (this->index_ == 0)
9004     this->call_->determine_type_no_context();
9005 }
9006
9007 // Return the tree.
9008
9009 tree
9010 Call_result_expression::do_get_tree(Translate_context* context)
9011 {
9012   tree call_tree = this->call_->get_tree(context);
9013   if (call_tree == error_mark_node)
9014     return error_mark_node;
9015   if (TREE_CODE(TREE_TYPE(call_tree)) != RECORD_TYPE)
9016     {
9017       gcc_assert(saw_errors());
9018       return error_mark_node;
9019     }
9020   tree field = TYPE_FIELDS(TREE_TYPE(call_tree));
9021   for (unsigned int i = 0; i < this->index_; ++i)
9022     {
9023       gcc_assert(field != NULL_TREE);
9024       field = DECL_CHAIN(field);
9025     }
9026   gcc_assert(field != NULL_TREE);
9027   return build3(COMPONENT_REF, TREE_TYPE(field), call_tree, field, NULL_TREE);
9028 }
9029
9030 // Make a reference to a single result of a call which returns
9031 // multiple results.
9032
9033 Expression*
9034 Expression::make_call_result(Call_expression* call, unsigned int index)
9035 {
9036   return new Call_result_expression(call, index);
9037 }
9038
9039 // Class Index_expression.
9040
9041 // Traversal.
9042
9043 int
9044 Index_expression::do_traverse(Traverse* traverse)
9045 {
9046   if (Expression::traverse(&this->left_, traverse) == TRAVERSE_EXIT
9047       || Expression::traverse(&this->start_, traverse) == TRAVERSE_EXIT
9048       || (this->end_ != NULL
9049           && Expression::traverse(&this->end_, traverse) == TRAVERSE_EXIT))
9050     return TRAVERSE_EXIT;
9051   return TRAVERSE_CONTINUE;
9052 }
9053
9054 // Lower an index expression.  This converts the generic index
9055 // expression into an array index, a string index, or a map index.
9056
9057 Expression*
9058 Index_expression::do_lower(Gogo*, Named_object*, int)
9059 {
9060   source_location location = this->location();
9061   Expression* left = this->left_;
9062   Expression* start = this->start_;
9063   Expression* end = this->end_;
9064
9065   Type* type = left->type();
9066   if (type->is_error_type())
9067     return Expression::make_error(location);
9068   else if (type->array_type() != NULL)
9069     return Expression::make_array_index(left, start, end, location);
9070   else if (type->points_to() != NULL
9071            && type->points_to()->array_type() != NULL
9072            && !type->points_to()->is_open_array_type())
9073     {
9074       Expression* deref = Expression::make_unary(OPERATOR_MULT, left,
9075                                                  location);
9076       return Expression::make_array_index(deref, start, end, location);
9077     }
9078   else if (type->is_string_type())
9079     return Expression::make_string_index(left, start, end, location);
9080   else if (type->map_type() != NULL)
9081     {
9082       if (end != NULL)
9083         {
9084           error_at(location, "invalid slice of map");
9085           return Expression::make_error(location);
9086         }
9087       Map_index_expression* ret= Expression::make_map_index(left, start,
9088                                                             location);
9089       if (this->is_lvalue_)
9090         ret->set_is_lvalue();
9091       return ret;
9092     }
9093   else
9094     {
9095       error_at(location,
9096                "attempt to index object which is not array, string, or map");
9097       return Expression::make_error(location);
9098     }
9099 }
9100
9101 // Make an index expression.
9102
9103 Expression*
9104 Expression::make_index(Expression* left, Expression* start, Expression* end,
9105                        source_location location)
9106 {
9107   return new Index_expression(left, start, end, location);
9108 }
9109
9110 // An array index.  This is used for both indexing and slicing.
9111
9112 class Array_index_expression : public Expression
9113 {
9114  public:
9115   Array_index_expression(Expression* array, Expression* start,
9116                          Expression* end, source_location location)
9117     : Expression(EXPRESSION_ARRAY_INDEX, location),
9118       array_(array), start_(start), end_(end), type_(NULL)
9119   { }
9120
9121  protected:
9122   int
9123   do_traverse(Traverse*);
9124
9125   Type*
9126   do_type();
9127
9128   void
9129   do_determine_type(const Type_context*);
9130
9131   void
9132   do_check_types(Gogo*);
9133
9134   Expression*
9135   do_copy()
9136   {
9137     return Expression::make_array_index(this->array_->copy(),
9138                                         this->start_->copy(),
9139                                         (this->end_ == NULL
9140                                          ? NULL
9141                                          : this->end_->copy()),
9142                                         this->location());
9143   }
9144
9145   bool
9146   do_is_addressable() const;
9147
9148   void
9149   do_address_taken(bool escapes)
9150   { this->array_->address_taken(escapes); }
9151
9152   tree
9153   do_get_tree(Translate_context*);
9154
9155  private:
9156   // The array we are getting a value from.
9157   Expression* array_;
9158   // The start or only index.
9159   Expression* start_;
9160   // The end index of a slice.  This may be NULL for a simple array
9161   // index, or it may be a nil expression for the length of the array.
9162   Expression* end_;
9163   // The type of the expression.
9164   Type* type_;
9165 };
9166
9167 // Array index traversal.
9168
9169 int
9170 Array_index_expression::do_traverse(Traverse* traverse)
9171 {
9172   if (Expression::traverse(&this->array_, traverse) == TRAVERSE_EXIT)
9173     return TRAVERSE_EXIT;
9174   if (Expression::traverse(&this->start_, traverse) == TRAVERSE_EXIT)
9175     return TRAVERSE_EXIT;
9176   if (this->end_ != NULL)
9177     {
9178       if (Expression::traverse(&this->end_, traverse) == TRAVERSE_EXIT)
9179         return TRAVERSE_EXIT;
9180     }
9181   return TRAVERSE_CONTINUE;
9182 }
9183
9184 // Return the type of an array index.
9185
9186 Type*
9187 Array_index_expression::do_type()
9188 {
9189   if (this->type_ == NULL)
9190     {
9191      Array_type* type = this->array_->type()->array_type();
9192       if (type == NULL)
9193         this->type_ = Type::make_error_type();
9194       else if (this->end_ == NULL)
9195         this->type_ = type->element_type();
9196       else if (type->is_open_array_type())
9197         {
9198           // A slice of a slice has the same type as the original
9199           // slice.
9200           this->type_ = this->array_->type()->deref();
9201         }
9202       else
9203         {
9204           // A slice of an array is a slice.
9205           this->type_ = Type::make_array_type(type->element_type(), NULL);
9206         }
9207     }
9208   return this->type_;
9209 }
9210
9211 // Set the type of an array index.
9212
9213 void
9214 Array_index_expression::do_determine_type(const Type_context*)
9215 {
9216   this->array_->determine_type_no_context();
9217   Type_context subcontext(NULL, true);
9218   this->start_->determine_type(&subcontext);
9219   if (this->end_ != NULL)
9220     this->end_->determine_type(&subcontext);
9221 }
9222
9223 // Check types of an array index.
9224
9225 void
9226 Array_index_expression::do_check_types(Gogo*)
9227 {
9228   if (this->start_->type()->integer_type() == NULL)
9229     this->report_error(_("index must be integer"));
9230   if (this->end_ != NULL
9231       && this->end_->type()->integer_type() == NULL
9232       && !this->end_->is_nil_expression())
9233     this->report_error(_("slice end must be integer"));
9234
9235   Array_type* array_type = this->array_->type()->array_type();
9236   if (array_type == NULL)
9237     {
9238       gcc_assert(this->array_->type()->is_error_type());
9239       return;
9240     }
9241
9242   unsigned int int_bits =
9243     Type::lookup_integer_type("int")->integer_type()->bits();
9244
9245   Type* dummy;
9246   mpz_t lval;
9247   mpz_init(lval);
9248   bool lval_valid = (array_type->length() != NULL
9249                      && array_type->length()->integer_constant_value(true,
9250                                                                      lval,
9251                                                                      &dummy));
9252   mpz_t ival;
9253   mpz_init(ival);
9254   if (this->start_->integer_constant_value(true, ival, &dummy))
9255     {
9256       if (mpz_sgn(ival) < 0
9257           || mpz_sizeinbase(ival, 2) >= int_bits
9258           || (lval_valid
9259               && (this->end_ == NULL
9260                   ? mpz_cmp(ival, lval) >= 0
9261                   : mpz_cmp(ival, lval) > 0)))
9262         {
9263           error_at(this->start_->location(), "array index out of bounds");
9264           this->set_is_error();
9265         }
9266     }
9267   if (this->end_ != NULL && !this->end_->is_nil_expression())
9268     {
9269       if (this->end_->integer_constant_value(true, ival, &dummy))
9270         {
9271           if (mpz_sgn(ival) < 0
9272               || mpz_sizeinbase(ival, 2) >= int_bits
9273               || (lval_valid && mpz_cmp(ival, lval) > 0))
9274             {
9275               error_at(this->end_->location(), "array index out of bounds");
9276               this->set_is_error();
9277             }
9278         }
9279     }
9280   mpz_clear(ival);
9281   mpz_clear(lval);
9282
9283   // A slice of an array requires an addressable array.  A slice of a
9284   // slice is always possible.
9285   if (this->end_ != NULL
9286       && !array_type->is_open_array_type()
9287       && !this->array_->is_addressable())
9288     this->report_error(_("array is not addressable"));
9289 }
9290
9291 // Return whether this expression is addressable.
9292
9293 bool
9294 Array_index_expression::do_is_addressable() const
9295 {
9296   // A slice expression is not addressable.
9297   if (this->end_ != NULL)
9298     return false;
9299
9300   // An index into a slice is addressable.
9301   if (this->array_->type()->is_open_array_type())
9302     return true;
9303
9304   // An index into an array is addressable if the array is
9305   // addressable.
9306   return this->array_->is_addressable();
9307 }
9308
9309 // Get a tree for an array index.
9310
9311 tree
9312 Array_index_expression::do_get_tree(Translate_context* context)
9313 {
9314   Gogo* gogo = context->gogo();
9315   source_location loc = this->location();
9316
9317   Array_type* array_type = this->array_->type()->array_type();
9318   if (array_type == NULL)
9319     {
9320       gcc_assert(this->array_->type()->is_error_type());
9321       return error_mark_node;
9322     }
9323
9324   tree type_tree = array_type->get_tree(gogo);
9325   if (type_tree == error_mark_node)
9326     return error_mark_node;
9327
9328   tree array_tree = this->array_->get_tree(context);
9329   if (array_tree == error_mark_node)
9330     return error_mark_node;
9331
9332   if (array_type->length() == NULL && !DECL_P(array_tree))
9333     array_tree = save_expr(array_tree);
9334   tree length_tree = array_type->length_tree(gogo, array_tree);
9335   if (length_tree == error_mark_node)
9336     return error_mark_node;
9337   length_tree = save_expr(length_tree);
9338   tree length_type = TREE_TYPE(length_tree);
9339
9340   tree bad_index = boolean_false_node;
9341
9342   tree start_tree = this->start_->get_tree(context);
9343   if (start_tree == error_mark_node)
9344     return error_mark_node;
9345   if (!DECL_P(start_tree))
9346     start_tree = save_expr(start_tree);
9347   if (!INTEGRAL_TYPE_P(TREE_TYPE(start_tree)))
9348     start_tree = convert_to_integer(length_type, start_tree);
9349
9350   bad_index = Expression::check_bounds(start_tree, length_type, bad_index,
9351                                        loc);
9352
9353   start_tree = fold_convert_loc(loc, length_type, start_tree);
9354   bad_index = fold_build2_loc(loc, TRUTH_OR_EXPR, boolean_type_node, bad_index,
9355                               fold_build2_loc(loc,
9356                                               (this->end_ == NULL
9357                                                ? GE_EXPR
9358                                                : GT_EXPR),
9359                                               boolean_type_node, start_tree,
9360                                               length_tree));
9361
9362   int code = (array_type->length() != NULL
9363               ? (this->end_ == NULL
9364                  ? RUNTIME_ERROR_ARRAY_INDEX_OUT_OF_BOUNDS
9365                  : RUNTIME_ERROR_ARRAY_SLICE_OUT_OF_BOUNDS)
9366               : (this->end_ == NULL
9367                  ? RUNTIME_ERROR_SLICE_INDEX_OUT_OF_BOUNDS
9368                  : RUNTIME_ERROR_SLICE_SLICE_OUT_OF_BOUNDS));
9369   tree crash = Gogo::runtime_error(code, loc);
9370
9371   if (this->end_ == NULL)
9372     {
9373       // Simple array indexing.  This has to return an l-value, so
9374       // wrap the index check into START_TREE.
9375       start_tree = build2(COMPOUND_EXPR, TREE_TYPE(start_tree),
9376                           build3(COND_EXPR, void_type_node,
9377                                  bad_index, crash, NULL_TREE),
9378                           start_tree);
9379       start_tree = fold_convert_loc(loc, sizetype, start_tree);
9380
9381       if (array_type->length() != NULL)
9382         {
9383           // Fixed array.
9384           return build4(ARRAY_REF, TREE_TYPE(type_tree), array_tree,
9385                         start_tree, NULL_TREE, NULL_TREE);
9386         }
9387       else
9388         {
9389           // Open array.
9390           tree values = array_type->value_pointer_tree(gogo, array_tree);
9391           tree element_type_tree = array_type->element_type()->get_tree(gogo);
9392           if (element_type_tree == error_mark_node)
9393             return error_mark_node;
9394           tree element_size = TYPE_SIZE_UNIT(element_type_tree);
9395           tree offset = fold_build2_loc(loc, MULT_EXPR, sizetype,
9396                                         start_tree, element_size);
9397           tree ptr = fold_build2_loc(loc, POINTER_PLUS_EXPR,
9398                                      TREE_TYPE(values), values, offset);
9399           return build_fold_indirect_ref(ptr);
9400         }
9401     }
9402
9403   // Array slice.
9404
9405   tree capacity_tree = array_type->capacity_tree(gogo, array_tree);
9406   if (capacity_tree == error_mark_node)
9407     return error_mark_node;
9408   capacity_tree = fold_convert_loc(loc, length_type, capacity_tree);
9409
9410   tree end_tree;
9411   if (this->end_->is_nil_expression())
9412     end_tree = length_tree;
9413   else
9414     {
9415       end_tree = this->end_->get_tree(context);
9416       if (end_tree == error_mark_node)
9417         return error_mark_node;
9418       if (!DECL_P(end_tree))
9419         end_tree = save_expr(end_tree);
9420       if (!INTEGRAL_TYPE_P(TREE_TYPE(end_tree)))
9421         end_tree = convert_to_integer(length_type, end_tree);
9422
9423       bad_index = Expression::check_bounds(end_tree, length_type, bad_index,
9424                                            loc);
9425
9426       end_tree = fold_convert_loc(loc, length_type, end_tree);
9427
9428       capacity_tree = save_expr(capacity_tree);
9429       tree bad_end = fold_build2_loc(loc, TRUTH_OR_EXPR, boolean_type_node,
9430                                      fold_build2_loc(loc, LT_EXPR,
9431                                                      boolean_type_node,
9432                                                      end_tree, start_tree),
9433                                      fold_build2_loc(loc, GT_EXPR,
9434                                                      boolean_type_node,
9435                                                      end_tree, capacity_tree));
9436       bad_index = fold_build2_loc(loc, TRUTH_OR_EXPR, boolean_type_node,
9437                                   bad_index, bad_end);
9438     }
9439
9440   tree element_type_tree = array_type->element_type()->get_tree(gogo);
9441   if (element_type_tree == error_mark_node)
9442     return error_mark_node;
9443   tree element_size = TYPE_SIZE_UNIT(element_type_tree);
9444
9445   tree offset = fold_build2_loc(loc, MULT_EXPR, sizetype,
9446                                 fold_convert_loc(loc, sizetype, start_tree),
9447                                 element_size);
9448
9449   tree value_pointer = array_type->value_pointer_tree(gogo, array_tree);
9450   if (value_pointer == error_mark_node)
9451     return error_mark_node;
9452
9453   value_pointer = fold_build2_loc(loc, POINTER_PLUS_EXPR,
9454                                   TREE_TYPE(value_pointer),
9455                                   value_pointer, offset);
9456
9457   tree result_length_tree = fold_build2_loc(loc, MINUS_EXPR, length_type,
9458                                             end_tree, start_tree);
9459
9460   tree result_capacity_tree = fold_build2_loc(loc, MINUS_EXPR, length_type,
9461                                               capacity_tree, start_tree);
9462
9463   tree struct_tree = this->type()->get_tree(gogo);
9464   gcc_assert(TREE_CODE(struct_tree) == RECORD_TYPE);
9465
9466   VEC(constructor_elt,gc)* init = VEC_alloc(constructor_elt, gc, 3);
9467
9468   constructor_elt* elt = VEC_quick_push(constructor_elt, init, NULL);
9469   tree field = TYPE_FIELDS(struct_tree);
9470   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__values") == 0);
9471   elt->index = field;
9472   elt->value = value_pointer;
9473
9474   elt = VEC_quick_push(constructor_elt, init, NULL);
9475   field = DECL_CHAIN(field);
9476   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__count") == 0);
9477   elt->index = field;
9478   elt->value = fold_convert_loc(loc, TREE_TYPE(field), result_length_tree);
9479
9480   elt = VEC_quick_push(constructor_elt, init, NULL);
9481   field = DECL_CHAIN(field);
9482   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__capacity") == 0);
9483   elt->index = field;
9484   elt->value = fold_convert_loc(loc, TREE_TYPE(field), result_capacity_tree);
9485
9486   tree constructor = build_constructor(struct_tree, init);
9487
9488   if (TREE_CONSTANT(value_pointer)
9489       && TREE_CONSTANT(result_length_tree)
9490       && TREE_CONSTANT(result_capacity_tree))
9491     TREE_CONSTANT(constructor) = 1;
9492
9493   return fold_build2_loc(loc, COMPOUND_EXPR, TREE_TYPE(constructor),
9494                          build3(COND_EXPR, void_type_node,
9495                                 bad_index, crash, NULL_TREE),
9496                          constructor);
9497 }
9498
9499 // Make an array index expression.  END may be NULL.
9500
9501 Expression*
9502 Expression::make_array_index(Expression* array, Expression* start,
9503                              Expression* end, source_location location)
9504 {
9505   // Taking a slice of a composite literal requires moving the literal
9506   // onto the heap.
9507   if (end != NULL && array->is_composite_literal())
9508     {
9509       array = Expression::make_heap_composite(array, location);
9510       array = Expression::make_unary(OPERATOR_MULT, array, location);
9511     }
9512   return new Array_index_expression(array, start, end, location);
9513 }
9514
9515 // A string index.  This is used for both indexing and slicing.
9516
9517 class String_index_expression : public Expression
9518 {
9519  public:
9520   String_index_expression(Expression* string, Expression* start,
9521                           Expression* end, source_location location)
9522     : Expression(EXPRESSION_STRING_INDEX, location),
9523       string_(string), start_(start), end_(end)
9524   { }
9525
9526  protected:
9527   int
9528   do_traverse(Traverse*);
9529
9530   Type*
9531   do_type();
9532
9533   void
9534   do_determine_type(const Type_context*);
9535
9536   void
9537   do_check_types(Gogo*);
9538
9539   Expression*
9540   do_copy()
9541   {
9542     return Expression::make_string_index(this->string_->copy(),
9543                                          this->start_->copy(),
9544                                          (this->end_ == NULL
9545                                           ? NULL
9546                                           : this->end_->copy()),
9547                                          this->location());
9548   }
9549
9550   tree
9551   do_get_tree(Translate_context*);
9552
9553  private:
9554   // The string we are getting a value from.
9555   Expression* string_;
9556   // The start or only index.
9557   Expression* start_;
9558   // The end index of a slice.  This may be NULL for a single index,
9559   // or it may be a nil expression for the length of the string.
9560   Expression* end_;
9561 };
9562
9563 // String index traversal.
9564
9565 int
9566 String_index_expression::do_traverse(Traverse* traverse)
9567 {
9568   if (Expression::traverse(&this->string_, traverse) == TRAVERSE_EXIT)
9569     return TRAVERSE_EXIT;
9570   if (Expression::traverse(&this->start_, traverse) == TRAVERSE_EXIT)
9571     return TRAVERSE_EXIT;
9572   if (this->end_ != NULL)
9573     {
9574       if (Expression::traverse(&this->end_, traverse) == TRAVERSE_EXIT)
9575         return TRAVERSE_EXIT;
9576     }
9577   return TRAVERSE_CONTINUE;
9578 }
9579
9580 // Return the type of a string index.
9581
9582 Type*
9583 String_index_expression::do_type()
9584 {
9585   if (this->end_ == NULL)
9586     return Type::lookup_integer_type("uint8");
9587   else
9588     return this->string_->type();
9589 }
9590
9591 // Determine the type of a string index.
9592
9593 void
9594 String_index_expression::do_determine_type(const Type_context*)
9595 {
9596   this->string_->determine_type_no_context();
9597   Type_context subcontext(NULL, true);
9598   this->start_->determine_type(&subcontext);
9599   if (this->end_ != NULL)
9600     this->end_->determine_type(&subcontext);
9601 }
9602
9603 // Check types of a string index.
9604
9605 void
9606 String_index_expression::do_check_types(Gogo*)
9607 {
9608   if (this->start_->type()->integer_type() == NULL)
9609     this->report_error(_("index must be integer"));
9610   if (this->end_ != NULL
9611       && this->end_->type()->integer_type() == NULL
9612       && !this->end_->is_nil_expression())
9613     this->report_error(_("slice end must be integer"));
9614
9615   std::string sval;
9616   bool sval_valid = this->string_->string_constant_value(&sval);
9617
9618   mpz_t ival;
9619   mpz_init(ival);
9620   Type* dummy;
9621   if (this->start_->integer_constant_value(true, ival, &dummy))
9622     {
9623       if (mpz_sgn(ival) < 0
9624           || (sval_valid && mpz_cmp_ui(ival, sval.length()) >= 0))
9625         {
9626           error_at(this->start_->location(), "string index out of bounds");
9627           this->set_is_error();
9628         }
9629     }
9630   if (this->end_ != NULL && !this->end_->is_nil_expression())
9631     {
9632       if (this->end_->integer_constant_value(true, ival, &dummy))
9633         {
9634           if (mpz_sgn(ival) < 0
9635               || (sval_valid && mpz_cmp_ui(ival, sval.length()) > 0))
9636             {
9637               error_at(this->end_->location(), "string index out of bounds");
9638               this->set_is_error();
9639             }
9640         }
9641     }
9642   mpz_clear(ival);
9643 }
9644
9645 // Get a tree for a string index.
9646
9647 tree
9648 String_index_expression::do_get_tree(Translate_context* context)
9649 {
9650   source_location loc = this->location();
9651
9652   tree string_tree = this->string_->get_tree(context);
9653   if (string_tree == error_mark_node)
9654     return error_mark_node;
9655
9656   if (this->string_->type()->points_to() != NULL)
9657     string_tree = build_fold_indirect_ref(string_tree);
9658   if (!DECL_P(string_tree))
9659     string_tree = save_expr(string_tree);
9660   tree string_type = TREE_TYPE(string_tree);
9661
9662   tree length_tree = String_type::length_tree(context->gogo(), string_tree);
9663   length_tree = save_expr(length_tree);
9664   tree length_type = TREE_TYPE(length_tree);
9665
9666   tree bad_index = boolean_false_node;
9667
9668   tree start_tree = this->start_->get_tree(context);
9669   if (start_tree == error_mark_node)
9670     return error_mark_node;
9671   if (!DECL_P(start_tree))
9672     start_tree = save_expr(start_tree);
9673   if (!INTEGRAL_TYPE_P(TREE_TYPE(start_tree)))
9674     start_tree = convert_to_integer(length_type, start_tree);
9675
9676   bad_index = Expression::check_bounds(start_tree, length_type, bad_index,
9677                                        loc);
9678
9679   start_tree = fold_convert_loc(loc, length_type, start_tree);
9680
9681   int code = (this->end_ == NULL
9682               ? RUNTIME_ERROR_STRING_INDEX_OUT_OF_BOUNDS
9683               : RUNTIME_ERROR_STRING_SLICE_OUT_OF_BOUNDS);
9684   tree crash = Gogo::runtime_error(code, loc);
9685
9686   if (this->end_ == NULL)
9687     {
9688       bad_index = fold_build2_loc(loc, TRUTH_OR_EXPR, boolean_type_node,
9689                                   bad_index,
9690                                   fold_build2_loc(loc, GE_EXPR,
9691                                                   boolean_type_node,
9692                                                   start_tree, length_tree));
9693
9694       tree bytes_tree = String_type::bytes_tree(context->gogo(), string_tree);
9695       tree ptr = fold_build2_loc(loc, POINTER_PLUS_EXPR, TREE_TYPE(bytes_tree),
9696                                  bytes_tree,
9697                                  fold_convert_loc(loc, sizetype, start_tree));
9698       tree index = build_fold_indirect_ref_loc(loc, ptr);
9699
9700       return build2(COMPOUND_EXPR, TREE_TYPE(index),
9701                     build3(COND_EXPR, void_type_node,
9702                            bad_index, crash, NULL_TREE),
9703                     index);
9704     }
9705   else
9706     {
9707       tree end_tree;
9708       if (this->end_->is_nil_expression())
9709         end_tree = build_int_cst(length_type, -1);
9710       else
9711         {
9712           end_tree = this->end_->get_tree(context);
9713           if (end_tree == error_mark_node)
9714             return error_mark_node;
9715           if (!DECL_P(end_tree))
9716             end_tree = save_expr(end_tree);
9717           if (!INTEGRAL_TYPE_P(TREE_TYPE(end_tree)))
9718             end_tree = convert_to_integer(length_type, end_tree);
9719
9720           bad_index = Expression::check_bounds(end_tree, length_type,
9721                                                bad_index, loc);
9722
9723           end_tree = fold_convert_loc(loc, length_type, end_tree);
9724         }
9725
9726       static tree strslice_fndecl;
9727       tree ret = Gogo::call_builtin(&strslice_fndecl,
9728                                     loc,
9729                                     "__go_string_slice",
9730                                     3,
9731                                     string_type,
9732                                     string_type,
9733                                     string_tree,
9734                                     length_type,
9735                                     start_tree,
9736                                     length_type,
9737                                     end_tree);
9738       if (ret == error_mark_node)
9739         return error_mark_node;
9740       // This will panic if the bounds are out of range for the
9741       // string.
9742       TREE_NOTHROW(strslice_fndecl) = 0;
9743
9744       if (bad_index == boolean_false_node)
9745         return ret;
9746       else
9747         return build2(COMPOUND_EXPR, TREE_TYPE(ret),
9748                       build3(COND_EXPR, void_type_node,
9749                              bad_index, crash, NULL_TREE),
9750                       ret);
9751     }
9752 }
9753
9754 // Make a string index expression.  END may be NULL.
9755
9756 Expression*
9757 Expression::make_string_index(Expression* string, Expression* start,
9758                               Expression* end, source_location location)
9759 {
9760   return new String_index_expression(string, start, end, location);
9761 }
9762
9763 // Class Map_index.
9764
9765 // Get the type of the map.
9766
9767 Map_type*
9768 Map_index_expression::get_map_type() const
9769 {
9770   Map_type* mt = this->map_->type()->deref()->map_type();
9771   if (mt == NULL)
9772     gcc_assert(saw_errors());
9773   return mt;
9774 }
9775
9776 // Map index traversal.
9777
9778 int
9779 Map_index_expression::do_traverse(Traverse* traverse)
9780 {
9781   if (Expression::traverse(&this->map_, traverse) == TRAVERSE_EXIT)
9782     return TRAVERSE_EXIT;
9783   return Expression::traverse(&this->index_, traverse);
9784 }
9785
9786 // Return the type of a map index.
9787
9788 Type*
9789 Map_index_expression::do_type()
9790 {
9791   Map_type* mt = this->get_map_type();
9792   if (mt == NULL)
9793     return Type::make_error_type();
9794   Type* type = mt->val_type();
9795   // If this map index is in a tuple assignment, we actually return a
9796   // pointer to the value type.  Tuple_map_assignment_statement is
9797   // responsible for handling this correctly.  We need to get the type
9798   // right in case this gets assigned to a temporary variable.
9799   if (this->is_in_tuple_assignment_)
9800     type = Type::make_pointer_type(type);
9801   return type;
9802 }
9803
9804 // Fix the type of a map index.
9805
9806 void
9807 Map_index_expression::do_determine_type(const Type_context*)
9808 {
9809   this->map_->determine_type_no_context();
9810   Map_type* mt = this->get_map_type();
9811   Type* key_type = mt == NULL ? NULL : mt->key_type();
9812   Type_context subcontext(key_type, false);
9813   this->index_->determine_type(&subcontext);
9814 }
9815
9816 // Check types of a map index.
9817
9818 void
9819 Map_index_expression::do_check_types(Gogo*)
9820 {
9821   std::string reason;
9822   Map_type* mt = this->get_map_type();
9823   if (mt == NULL)
9824     return;
9825   if (!Type::are_assignable(mt->key_type(), this->index_->type(), &reason))
9826     {
9827       if (reason.empty())
9828         this->report_error(_("incompatible type for map index"));
9829       else
9830         {
9831           error_at(this->location(), "incompatible type for map index (%s)",
9832                    reason.c_str());
9833           this->set_is_error();
9834         }
9835     }
9836 }
9837
9838 // Get a tree for a map index.
9839
9840 tree
9841 Map_index_expression::do_get_tree(Translate_context* context)
9842 {
9843   Map_type* type = this->get_map_type();
9844   if (type == NULL)
9845     return error_mark_node;
9846
9847   tree valptr = this->get_value_pointer(context, this->is_lvalue_);
9848   if (valptr == error_mark_node)
9849     return error_mark_node;
9850   valptr = save_expr(valptr);
9851
9852   tree val_type_tree = TREE_TYPE(TREE_TYPE(valptr));
9853
9854   if (this->is_lvalue_)
9855     return build_fold_indirect_ref(valptr);
9856   else if (this->is_in_tuple_assignment_)
9857     {
9858       // Tuple_map_assignment_statement is responsible for using this
9859       // appropriately.
9860       return valptr;
9861     }
9862   else
9863     {
9864       return fold_build3(COND_EXPR, val_type_tree,
9865                          fold_build2(EQ_EXPR, boolean_type_node, valptr,
9866                                      fold_convert(TREE_TYPE(valptr),
9867                                                   null_pointer_node)),
9868                          type->val_type()->get_init_tree(context->gogo(),
9869                                                          false),
9870                          build_fold_indirect_ref(valptr));
9871     }
9872 }
9873
9874 // Get a tree for the map index.  This returns a tree which evaluates
9875 // to a pointer to a value.  The pointer will be NULL if the key is
9876 // not in the map.
9877
9878 tree
9879 Map_index_expression::get_value_pointer(Translate_context* context,
9880                                         bool insert)
9881 {
9882   Map_type* type = this->get_map_type();
9883   if (type == NULL)
9884     return error_mark_node;
9885
9886   tree map_tree = this->map_->get_tree(context);
9887   tree index_tree = this->index_->get_tree(context);
9888   index_tree = Expression::convert_for_assignment(context, type->key_type(),
9889                                                   this->index_->type(),
9890                                                   index_tree,
9891                                                   this->location());
9892   if (map_tree == error_mark_node || index_tree == error_mark_node)
9893     return error_mark_node;
9894
9895   if (this->map_->type()->points_to() != NULL)
9896     map_tree = build_fold_indirect_ref(map_tree);
9897
9898   // We need to pass in a pointer to the key, so stuff it into a
9899   // variable.
9900   tree tmp = create_tmp_var(TREE_TYPE(index_tree), get_name(index_tree));
9901   DECL_IGNORED_P(tmp) = 0;
9902   DECL_INITIAL(tmp) = index_tree;
9903   tree make_tmp = build1(DECL_EXPR, void_type_node, tmp);
9904   tree tmpref = fold_convert(const_ptr_type_node, build_fold_addr_expr(tmp));
9905   TREE_ADDRESSABLE(tmp) = 1;
9906
9907   static tree map_index_fndecl;
9908   tree call = Gogo::call_builtin(&map_index_fndecl,
9909                                  this->location(),
9910                                  "__go_map_index",
9911                                  3,
9912                                  const_ptr_type_node,
9913                                  TREE_TYPE(map_tree),
9914                                  map_tree,
9915                                  const_ptr_type_node,
9916                                  tmpref,
9917                                  boolean_type_node,
9918                                  (insert
9919                                   ? boolean_true_node
9920                                   : boolean_false_node));
9921   if (call == error_mark_node)
9922     return error_mark_node;
9923   // This can panic on a map of interface type if the interface holds
9924   // an uncomparable or unhashable type.
9925   TREE_NOTHROW(map_index_fndecl) = 0;
9926
9927   tree val_type_tree = type->val_type()->get_tree(context->gogo());
9928   if (val_type_tree == error_mark_node)
9929     return error_mark_node;
9930   tree ptr_val_type_tree = build_pointer_type(val_type_tree);
9931
9932   return build2(COMPOUND_EXPR, ptr_val_type_tree,
9933                 make_tmp,
9934                 fold_convert(ptr_val_type_tree, call));
9935 }
9936
9937 // Make a map index expression.
9938
9939 Map_index_expression*
9940 Expression::make_map_index(Expression* map, Expression* index,
9941                            source_location location)
9942 {
9943   return new Map_index_expression(map, index, location);
9944 }
9945
9946 // Class Field_reference_expression.
9947
9948 // Return the type of a field reference.
9949
9950 Type*
9951 Field_reference_expression::do_type()
9952 {
9953   Struct_type* struct_type = this->expr_->type()->struct_type();
9954   gcc_assert(struct_type != NULL);
9955   return struct_type->field(this->field_index_)->type();
9956 }
9957
9958 // Check the types for a field reference.
9959
9960 void
9961 Field_reference_expression::do_check_types(Gogo*)
9962 {
9963   Struct_type* struct_type = this->expr_->type()->struct_type();
9964   gcc_assert(struct_type != NULL);
9965   gcc_assert(struct_type->field(this->field_index_) != NULL);
9966 }
9967
9968 // Get a tree for a field reference.
9969
9970 tree
9971 Field_reference_expression::do_get_tree(Translate_context* context)
9972 {
9973   tree struct_tree = this->expr_->get_tree(context);
9974   if (struct_tree == error_mark_node
9975       || TREE_TYPE(struct_tree) == error_mark_node)
9976     return error_mark_node;
9977   gcc_assert(TREE_CODE(TREE_TYPE(struct_tree)) == RECORD_TYPE);
9978   tree field = TYPE_FIELDS(TREE_TYPE(struct_tree));
9979   if (field == NULL_TREE)
9980     {
9981       // This can happen for a type which refers to itself indirectly
9982       // and then turns out to be erroneous.
9983       gcc_assert(saw_errors());
9984       return error_mark_node;
9985     }
9986   for (unsigned int i = this->field_index_; i > 0; --i)
9987     {
9988       field = DECL_CHAIN(field);
9989       gcc_assert(field != NULL_TREE);
9990     }
9991   return build3(COMPONENT_REF, TREE_TYPE(field), struct_tree, field,
9992                 NULL_TREE);
9993 }
9994
9995 // Make a reference to a qualified identifier in an expression.
9996
9997 Field_reference_expression*
9998 Expression::make_field_reference(Expression* expr, unsigned int field_index,
9999                                  source_location location)
10000 {
10001   return new Field_reference_expression(expr, field_index, location);
10002 }
10003
10004 // Class Interface_field_reference_expression.
10005
10006 // Return a tree for the pointer to the function to call.
10007
10008 tree
10009 Interface_field_reference_expression::get_function_tree(Translate_context*,
10010                                                         tree expr)
10011 {
10012   if (this->expr_->type()->points_to() != NULL)
10013     expr = build_fold_indirect_ref(expr);
10014
10015   tree expr_type = TREE_TYPE(expr);
10016   gcc_assert(TREE_CODE(expr_type) == RECORD_TYPE);
10017
10018   tree field = TYPE_FIELDS(expr_type);
10019   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__methods") == 0);
10020
10021   tree table = build3(COMPONENT_REF, TREE_TYPE(field), expr, field, NULL_TREE);
10022   gcc_assert(POINTER_TYPE_P(TREE_TYPE(table)));
10023
10024   table = build_fold_indirect_ref(table);
10025   gcc_assert(TREE_CODE(TREE_TYPE(table)) == RECORD_TYPE);
10026
10027   std::string name = Gogo::unpack_hidden_name(this->name_);
10028   for (field = DECL_CHAIN(TYPE_FIELDS(TREE_TYPE(table)));
10029        field != NULL_TREE;
10030        field = DECL_CHAIN(field))
10031     {
10032       if (name == IDENTIFIER_POINTER(DECL_NAME(field)))
10033         break;
10034     }
10035   gcc_assert(field != NULL_TREE);
10036
10037   return build3(COMPONENT_REF, TREE_TYPE(field), table, field, NULL_TREE);
10038 }
10039
10040 // Return a tree for the first argument to pass to the interface
10041 // function.
10042
10043 tree
10044 Interface_field_reference_expression::get_underlying_object_tree(
10045     Translate_context*,
10046     tree expr)
10047 {
10048   if (this->expr_->type()->points_to() != NULL)
10049     expr = build_fold_indirect_ref(expr);
10050
10051   tree expr_type = TREE_TYPE(expr);
10052   gcc_assert(TREE_CODE(expr_type) == RECORD_TYPE);
10053
10054   tree field = DECL_CHAIN(TYPE_FIELDS(expr_type));
10055   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__object") == 0);
10056
10057   return build3(COMPONENT_REF, TREE_TYPE(field), expr, field, NULL_TREE);
10058 }
10059
10060 // Traversal.
10061
10062 int
10063 Interface_field_reference_expression::do_traverse(Traverse* traverse)
10064 {
10065   return Expression::traverse(&this->expr_, traverse);
10066 }
10067
10068 // Return the type of an interface field reference.
10069
10070 Type*
10071 Interface_field_reference_expression::do_type()
10072 {
10073   Type* expr_type = this->expr_->type();
10074
10075   Type* points_to = expr_type->points_to();
10076   if (points_to != NULL)
10077     expr_type = points_to;
10078
10079   Interface_type* interface_type = expr_type->interface_type();
10080   if (interface_type == NULL)
10081     return Type::make_error_type();
10082
10083   const Typed_identifier* method = interface_type->find_method(this->name_);
10084   if (method == NULL)
10085     return Type::make_error_type();
10086
10087   return method->type();
10088 }
10089
10090 // Determine types.
10091
10092 void
10093 Interface_field_reference_expression::do_determine_type(const Type_context*)
10094 {
10095   this->expr_->determine_type_no_context();
10096 }
10097
10098 // Check the types for an interface field reference.
10099
10100 void
10101 Interface_field_reference_expression::do_check_types(Gogo*)
10102 {
10103   Type* type = this->expr_->type();
10104
10105   Type* points_to = type->points_to();
10106   if (points_to != NULL)
10107     type = points_to;
10108
10109   Interface_type* interface_type = type->interface_type();
10110   if (interface_type == NULL)
10111     this->report_error(_("expected interface or pointer to interface"));
10112   else
10113     {
10114       const Typed_identifier* method =
10115         interface_type->find_method(this->name_);
10116       if (method == NULL)
10117         {
10118           error_at(this->location(), "method %qs not in interface",
10119                    Gogo::message_name(this->name_).c_str());
10120           this->set_is_error();
10121         }
10122     }
10123 }
10124
10125 // Get a tree for a reference to a field in an interface.  There is no
10126 // standard tree type representation for this: it's a function
10127 // attached to its first argument, like a Bound_method_expression.
10128 // The only places it may currently be used are in a Call_expression
10129 // or a Go_statement, which will take it apart directly.  So this has
10130 // nothing to do at present.
10131
10132 tree
10133 Interface_field_reference_expression::do_get_tree(Translate_context*)
10134 {
10135   gcc_unreachable();
10136 }
10137
10138 // Make a reference to a field in an interface.
10139
10140 Expression*
10141 Expression::make_interface_field_reference(Expression* expr,
10142                                            const std::string& field,
10143                                            source_location location)
10144 {
10145   return new Interface_field_reference_expression(expr, field, location);
10146 }
10147
10148 // A general selector.  This is a Parser_expression for LEFT.NAME.  It
10149 // is lowered after we know the type of the left hand side.
10150
10151 class Selector_expression : public Parser_expression
10152 {
10153  public:
10154   Selector_expression(Expression* left, const std::string& name,
10155                       source_location location)
10156     : Parser_expression(EXPRESSION_SELECTOR, location),
10157       left_(left), name_(name)
10158   { }
10159
10160  protected:
10161   int
10162   do_traverse(Traverse* traverse)
10163   { return Expression::traverse(&this->left_, traverse); }
10164
10165   Expression*
10166   do_lower(Gogo*, Named_object*, int);
10167
10168   Expression*
10169   do_copy()
10170   {
10171     return new Selector_expression(this->left_->copy(), this->name_,
10172                                    this->location());
10173   }
10174
10175  private:
10176   Expression*
10177   lower_method_expression(Gogo*);
10178
10179   // The expression on the left hand side.
10180   Expression* left_;
10181   // The name on the right hand side.
10182   std::string name_;
10183 };
10184
10185 // Lower a selector expression once we know the real type of the left
10186 // hand side.
10187
10188 Expression*
10189 Selector_expression::do_lower(Gogo* gogo, Named_object*, int)
10190 {
10191   Expression* left = this->left_;
10192   if (left->is_type_expression())
10193     return this->lower_method_expression(gogo);
10194   return Type::bind_field_or_method(gogo, left->type(), left, this->name_,
10195                                     this->location());
10196 }
10197
10198 // Lower a method expression T.M or (*T).M.  We turn this into a
10199 // function literal.
10200
10201 Expression*
10202 Selector_expression::lower_method_expression(Gogo* gogo)
10203 {
10204   source_location location = this->location();
10205   Type* type = this->left_->type();
10206   const std::string& name(this->name_);
10207
10208   bool is_pointer;
10209   if (type->points_to() == NULL)
10210     is_pointer = false;
10211   else
10212     {
10213       is_pointer = true;
10214       type = type->points_to();
10215     }
10216   Named_type* nt = type->named_type();
10217   if (nt == NULL)
10218     {
10219       error_at(location,
10220                ("method expression requires named type or "
10221                 "pointer to named type"));
10222       return Expression::make_error(location);
10223     }
10224
10225   bool is_ambiguous;
10226   Method* method = nt->method_function(name, &is_ambiguous);
10227   if (method == NULL)
10228     {
10229       if (!is_ambiguous)
10230         error_at(location, "type %<%s%> has no method %<%s%>",
10231                  nt->message_name().c_str(),
10232                  Gogo::message_name(name).c_str());
10233       else
10234         error_at(location, "method %<%s%> is ambiguous in type %<%s%>",
10235                  Gogo::message_name(name).c_str(),
10236                  nt->message_name().c_str());
10237       return Expression::make_error(location);
10238     }
10239
10240   if (!is_pointer && !method->is_value_method())
10241     {
10242       error_at(location, "method requires pointer (use %<(*%s).%s)%>",
10243                nt->message_name().c_str(),
10244                Gogo::message_name(name).c_str());
10245       return Expression::make_error(location);
10246     }
10247
10248   // Build a new function type in which the receiver becomes the first
10249   // argument.
10250   Function_type* method_type = method->type();
10251   gcc_assert(method_type->is_method());
10252
10253   const char* const receiver_name = "$this";
10254   Typed_identifier_list* parameters = new Typed_identifier_list();
10255   parameters->push_back(Typed_identifier(receiver_name, this->left_->type(),
10256                                          location));
10257
10258   const Typed_identifier_list* method_parameters = method_type->parameters();
10259   if (method_parameters != NULL)
10260     {
10261       for (Typed_identifier_list::const_iterator p = method_parameters->begin();
10262            p != method_parameters->end();
10263            ++p)
10264         parameters->push_back(*p);
10265     }
10266
10267   const Typed_identifier_list* method_results = method_type->results();
10268   Typed_identifier_list* results;
10269   if (method_results == NULL)
10270     results = NULL;
10271   else
10272     {
10273       results = new Typed_identifier_list();
10274       for (Typed_identifier_list::const_iterator p = method_results->begin();
10275            p != method_results->end();
10276            ++p)
10277         results->push_back(*p);
10278     }
10279
10280   Function_type* fntype = Type::make_function_type(NULL, parameters, results,
10281                                                    location);
10282   if (method_type->is_varargs())
10283     fntype->set_is_varargs();
10284
10285   // We generate methods which always takes a pointer to the receiver
10286   // as their first argument.  If this is for a pointer type, we can
10287   // simply reuse the existing function.  We use an internal hack to
10288   // get the right type.
10289
10290   if (is_pointer)
10291     {
10292       Named_object* mno = (method->needs_stub_method()
10293                            ? method->stub_object()
10294                            : method->named_object());
10295       Expression* f = Expression::make_func_reference(mno, NULL, location);
10296       f = Expression::make_cast(fntype, f, location);
10297       Type_conversion_expression* tce =
10298         static_cast<Type_conversion_expression*>(f);
10299       tce->set_may_convert_function_types();
10300       return f;
10301     }
10302
10303   Named_object* no = gogo->start_function(Gogo::thunk_name(), fntype, false,
10304                                           location);
10305
10306   Named_object* vno = gogo->lookup(receiver_name, NULL);
10307   gcc_assert(vno != NULL);
10308   Expression* ve = Expression::make_var_reference(vno, location);
10309   Expression* bm = Type::bind_field_or_method(gogo, nt, ve, name, location);
10310   gcc_assert(bm != NULL && !bm->is_error_expression());
10311
10312   Expression_list* args;
10313   if (method_parameters == NULL)
10314     args = NULL;
10315   else
10316     {
10317       args = new Expression_list();
10318       for (Typed_identifier_list::const_iterator p = method_parameters->begin();
10319            p != method_parameters->end();
10320            ++p)
10321         {
10322           vno = gogo->lookup(p->name(), NULL);
10323           gcc_assert(vno != NULL);
10324           args->push_back(Expression::make_var_reference(vno, location));
10325         }
10326     }
10327
10328   Call_expression* call = Expression::make_call(bm, args,
10329                                                 method_type->is_varargs(),
10330                                                 location);
10331
10332   size_t count = call->result_count();
10333   Statement* s;
10334   if (count == 0)
10335     s = Statement::make_statement(call);
10336   else
10337     {
10338       Expression_list* retvals = new Expression_list();
10339       if (count <= 1)
10340         retvals->push_back(call);
10341       else
10342         {
10343           for (size_t i = 0; i < count; ++i)
10344             retvals->push_back(Expression::make_call_result(call, i));
10345         }
10346       s = Statement::make_return_statement(no->func_value()->type()->results(),
10347                                            retvals, location);
10348     }
10349   gogo->add_statement(s);
10350
10351   gogo->finish_function(location);
10352
10353   return Expression::make_func_reference(no, NULL, location);
10354 }
10355
10356 // Make a selector expression.
10357
10358 Expression*
10359 Expression::make_selector(Expression* left, const std::string& name,
10360                           source_location location)
10361 {
10362   return new Selector_expression(left, name, location);
10363 }
10364
10365 // Implement the builtin function new.
10366
10367 class Allocation_expression : public Expression
10368 {
10369  public:
10370   Allocation_expression(Type* type, source_location location)
10371     : Expression(EXPRESSION_ALLOCATION, location),
10372       type_(type)
10373   { }
10374
10375  protected:
10376   int
10377   do_traverse(Traverse* traverse)
10378   { return Type::traverse(this->type_, traverse); }
10379
10380   Type*
10381   do_type()
10382   { return Type::make_pointer_type(this->type_); }
10383
10384   void
10385   do_determine_type(const Type_context*)
10386   { }
10387
10388   void
10389   do_check_types(Gogo*);
10390
10391   Expression*
10392   do_copy()
10393   { return new Allocation_expression(this->type_, this->location()); }
10394
10395   tree
10396   do_get_tree(Translate_context*);
10397
10398  private:
10399   // The type we are allocating.
10400   Type* type_;
10401 };
10402
10403 // Check the type of an allocation expression.
10404
10405 void
10406 Allocation_expression::do_check_types(Gogo*)
10407 {
10408   if (this->type_->function_type() != NULL)
10409     this->report_error(_("invalid new of function type"));
10410 }
10411
10412 // Return a tree for an allocation expression.
10413
10414 tree
10415 Allocation_expression::do_get_tree(Translate_context* context)
10416 {
10417   tree type_tree = this->type_->get_tree(context->gogo());
10418   if (type_tree == error_mark_node)
10419     return error_mark_node;
10420   tree size_tree = TYPE_SIZE_UNIT(type_tree);
10421   tree space = context->gogo()->allocate_memory(this->type_, size_tree,
10422                                                 this->location());
10423   if (space == error_mark_node)
10424     return error_mark_node;
10425   return fold_convert(build_pointer_type(type_tree), space);
10426 }
10427
10428 // Make an allocation expression.
10429
10430 Expression*
10431 Expression::make_allocation(Type* type, source_location location)
10432 {
10433   return new Allocation_expression(type, location);
10434 }
10435
10436 // Implement the builtin function make.
10437
10438 class Make_expression : public Expression
10439 {
10440  public:
10441   Make_expression(Type* type, Expression_list* args, source_location location)
10442     : Expression(EXPRESSION_MAKE, location),
10443       type_(type), args_(args)
10444   { }
10445
10446  protected:
10447   int
10448   do_traverse(Traverse* traverse);
10449
10450   Type*
10451   do_type()
10452   { return this->type_; }
10453
10454   void
10455   do_determine_type(const Type_context*);
10456
10457   void
10458   do_check_types(Gogo*);
10459
10460   Expression*
10461   do_copy()
10462   {
10463     return new Make_expression(this->type_, this->args_->copy(),
10464                                this->location());
10465   }
10466
10467   tree
10468   do_get_tree(Translate_context*);
10469
10470  private:
10471   // The type we are making.
10472   Type* type_;
10473   // The arguments to pass to the make routine.
10474   Expression_list* args_;
10475 };
10476
10477 // Traversal.
10478
10479 int
10480 Make_expression::do_traverse(Traverse* traverse)
10481 {
10482   if (this->args_ != NULL
10483       && this->args_->traverse(traverse) == TRAVERSE_EXIT)
10484     return TRAVERSE_EXIT;
10485   if (Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
10486     return TRAVERSE_EXIT;
10487   return TRAVERSE_CONTINUE;
10488 }
10489
10490 // Set types of arguments.
10491
10492 void
10493 Make_expression::do_determine_type(const Type_context*)
10494 {
10495   if (this->args_ != NULL)
10496     {
10497       Type_context context(Type::lookup_integer_type("int"), false);
10498       for (Expression_list::const_iterator pe = this->args_->begin();
10499            pe != this->args_->end();
10500            ++pe)
10501         (*pe)->determine_type(&context);
10502     }
10503 }
10504
10505 // Check types for a make expression.
10506
10507 void
10508 Make_expression::do_check_types(Gogo*)
10509 {
10510   if (this->type_->channel_type() == NULL
10511       && this->type_->map_type() == NULL
10512       && (this->type_->array_type() == NULL
10513           || this->type_->array_type()->length() != NULL))
10514     this->report_error(_("invalid type for make function"));
10515   else if (!this->type_->check_make_expression(this->args_, this->location()))
10516     this->set_is_error();
10517 }
10518
10519 // Return a tree for a make expression.
10520
10521 tree
10522 Make_expression::do_get_tree(Translate_context* context)
10523 {
10524   return this->type_->make_expression_tree(context, this->args_,
10525                                            this->location());
10526 }
10527
10528 // Make a make expression.
10529
10530 Expression*
10531 Expression::make_make(Type* type, Expression_list* args,
10532                       source_location location)
10533 {
10534   return new Make_expression(type, args, location);
10535 }
10536
10537 // Construct a struct.
10538
10539 class Struct_construction_expression : public Expression
10540 {
10541  public:
10542   Struct_construction_expression(Type* type, Expression_list* vals,
10543                                  source_location location)
10544     : Expression(EXPRESSION_STRUCT_CONSTRUCTION, location),
10545       type_(type), vals_(vals)
10546   { }
10547
10548   // Return whether this is a constant initializer.
10549   bool
10550   is_constant_struct() const;
10551
10552  protected:
10553   int
10554   do_traverse(Traverse* traverse);
10555
10556   Type*
10557   do_type()
10558   { return this->type_; }
10559
10560   void
10561   do_determine_type(const Type_context*);
10562
10563   void
10564   do_check_types(Gogo*);
10565
10566   Expression*
10567   do_copy()
10568   {
10569     return new Struct_construction_expression(this->type_, this->vals_->copy(),
10570                                               this->location());
10571   }
10572
10573   bool
10574   do_is_addressable() const
10575   { return true; }
10576
10577   tree
10578   do_get_tree(Translate_context*);
10579
10580   void
10581   do_export(Export*) const;
10582
10583  private:
10584   // The type of the struct to construct.
10585   Type* type_;
10586   // The list of values, in order of the fields in the struct.  A NULL
10587   // entry means that the field should be zero-initialized.
10588   Expression_list* vals_;
10589 };
10590
10591 // Traversal.
10592
10593 int
10594 Struct_construction_expression::do_traverse(Traverse* traverse)
10595 {
10596   if (this->vals_ != NULL
10597       && this->vals_->traverse(traverse) == TRAVERSE_EXIT)
10598     return TRAVERSE_EXIT;
10599   if (Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
10600     return TRAVERSE_EXIT;
10601   return TRAVERSE_CONTINUE;
10602 }
10603
10604 // Return whether this is a constant initializer.
10605
10606 bool
10607 Struct_construction_expression::is_constant_struct() const
10608 {
10609   if (this->vals_ == NULL)
10610     return true;
10611   for (Expression_list::const_iterator pv = this->vals_->begin();
10612        pv != this->vals_->end();
10613        ++pv)
10614     {
10615       if (*pv != NULL
10616           && !(*pv)->is_constant()
10617           && (!(*pv)->is_composite_literal()
10618               || (*pv)->is_nonconstant_composite_literal()))
10619         return false;
10620     }
10621
10622   const Struct_field_list* fields = this->type_->struct_type()->fields();
10623   for (Struct_field_list::const_iterator pf = fields->begin();
10624        pf != fields->end();
10625        ++pf)
10626     {
10627       // There are no constant constructors for interfaces.
10628       if (pf->type()->interface_type() != NULL)
10629         return false;
10630     }
10631
10632   return true;
10633 }
10634
10635 // Final type determination.
10636
10637 void
10638 Struct_construction_expression::do_determine_type(const Type_context*)
10639 {
10640   if (this->vals_ == NULL)
10641     return;
10642   const Struct_field_list* fields = this->type_->struct_type()->fields();
10643   Expression_list::const_iterator pv = this->vals_->begin();
10644   for (Struct_field_list::const_iterator pf = fields->begin();
10645        pf != fields->end();
10646        ++pf, ++pv)
10647     {
10648       if (pv == this->vals_->end())
10649         return;
10650       if (*pv != NULL)
10651         {
10652           Type_context subcontext(pf->type(), false);
10653           (*pv)->determine_type(&subcontext);
10654         }
10655     }
10656   // Extra values are an error we will report elsewhere; we still want
10657   // to determine the type to avoid knockon errors.
10658   for (; pv != this->vals_->end(); ++pv)
10659     (*pv)->determine_type_no_context();
10660 }
10661
10662 // Check types.
10663
10664 void
10665 Struct_construction_expression::do_check_types(Gogo*)
10666 {
10667   if (this->vals_ == NULL)
10668     return;
10669
10670   Struct_type* st = this->type_->struct_type();
10671   if (this->vals_->size() > st->field_count())
10672     {
10673       this->report_error(_("too many expressions for struct"));
10674       return;
10675     }
10676
10677   const Struct_field_list* fields = st->fields();
10678   Expression_list::const_iterator pv = this->vals_->begin();
10679   int i = 0;
10680   for (Struct_field_list::const_iterator pf = fields->begin();
10681        pf != fields->end();
10682        ++pf, ++pv, ++i)
10683     {
10684       if (pv == this->vals_->end())
10685         {
10686           this->report_error(_("too few expressions for struct"));
10687           break;
10688         }
10689
10690       if (*pv == NULL)
10691         continue;
10692
10693       std::string reason;
10694       if (!Type::are_assignable(pf->type(), (*pv)->type(), &reason))
10695         {
10696           if (reason.empty())
10697             error_at((*pv)->location(),
10698                      "incompatible type for field %d in struct construction",
10699                      i + 1);
10700           else
10701             error_at((*pv)->location(),
10702                      ("incompatible type for field %d in "
10703                       "struct construction (%s)"),
10704                      i + 1, reason.c_str());
10705           this->set_is_error();
10706         }
10707     }
10708   gcc_assert(pv == this->vals_->end());
10709 }
10710
10711 // Return a tree for constructing a struct.
10712
10713 tree
10714 Struct_construction_expression::do_get_tree(Translate_context* context)
10715 {
10716   Gogo* gogo = context->gogo();
10717
10718   if (this->vals_ == NULL)
10719     return this->type_->get_init_tree(gogo, false);
10720
10721   tree type_tree = this->type_->get_tree(gogo);
10722   if (type_tree == error_mark_node)
10723     return error_mark_node;
10724   gcc_assert(TREE_CODE(type_tree) == RECORD_TYPE);
10725
10726   bool is_constant = true;
10727   const Struct_field_list* fields = this->type_->struct_type()->fields();
10728   VEC(constructor_elt,gc)* elts = VEC_alloc(constructor_elt, gc,
10729                                             fields->size());
10730   Struct_field_list::const_iterator pf = fields->begin();
10731   Expression_list::const_iterator pv = this->vals_->begin();
10732   for (tree field = TYPE_FIELDS(type_tree);
10733        field != NULL_TREE;
10734        field = DECL_CHAIN(field), ++pf)
10735     {
10736       gcc_assert(pf != fields->end());
10737
10738       tree val;
10739       if (pv == this->vals_->end())
10740         val = pf->type()->get_init_tree(gogo, false);
10741       else if (*pv == NULL)
10742         {
10743           val = pf->type()->get_init_tree(gogo, false);
10744           ++pv;
10745         }
10746       else
10747         {
10748           val = Expression::convert_for_assignment(context, pf->type(),
10749                                                    (*pv)->type(),
10750                                                    (*pv)->get_tree(context),
10751                                                    this->location());
10752           ++pv;
10753         }
10754
10755       if (val == error_mark_node || TREE_TYPE(val) == error_mark_node)
10756         return error_mark_node;
10757
10758       constructor_elt* elt = VEC_quick_push(constructor_elt, elts, NULL);
10759       elt->index = field;
10760       elt->value = val;
10761       if (!TREE_CONSTANT(val))
10762         is_constant = false;
10763     }
10764   gcc_assert(pf == fields->end());
10765
10766   tree ret = build_constructor(type_tree, elts);
10767   if (is_constant)
10768     TREE_CONSTANT(ret) = 1;
10769   return ret;
10770 }
10771
10772 // Export a struct construction.
10773
10774 void
10775 Struct_construction_expression::do_export(Export* exp) const
10776 {
10777   exp->write_c_string("convert(");
10778   exp->write_type(this->type_);
10779   for (Expression_list::const_iterator pv = this->vals_->begin();
10780        pv != this->vals_->end();
10781        ++pv)
10782     {
10783       exp->write_c_string(", ");
10784       if (*pv != NULL)
10785         (*pv)->export_expression(exp);
10786     }
10787   exp->write_c_string(")");
10788 }
10789
10790 // Make a struct composite literal.  This used by the thunk code.
10791
10792 Expression*
10793 Expression::make_struct_composite_literal(Type* type, Expression_list* vals,
10794                                           source_location location)
10795 {
10796   gcc_assert(type->struct_type() != NULL);
10797   return new Struct_construction_expression(type, vals, location);
10798 }
10799
10800 // Construct an array.  This class is not used directly; instead we
10801 // use the child classes, Fixed_array_construction_expression and
10802 // Open_array_construction_expression.
10803
10804 class Array_construction_expression : public Expression
10805 {
10806  protected:
10807   Array_construction_expression(Expression_classification classification,
10808                                 Type* type, Expression_list* vals,
10809                                 source_location location)
10810     : Expression(classification, location),
10811       type_(type), vals_(vals)
10812   { }
10813
10814  public:
10815   // Return whether this is a constant initializer.
10816   bool
10817   is_constant_array() const;
10818
10819   // Return the number of elements.
10820   size_t
10821   element_count() const
10822   { return this->vals_ == NULL ? 0 : this->vals_->size(); }
10823
10824 protected:
10825   int
10826   do_traverse(Traverse* traverse);
10827
10828   Type*
10829   do_type()
10830   { return this->type_; }
10831
10832   void
10833   do_determine_type(const Type_context*);
10834
10835   void
10836   do_check_types(Gogo*);
10837
10838   bool
10839   do_is_addressable() const
10840   { return true; }
10841
10842   void
10843   do_export(Export*) const;
10844
10845   // The list of values.
10846   Expression_list*
10847   vals()
10848   { return this->vals_; }
10849
10850   // Get a constructor tree for the array values.
10851   tree
10852   get_constructor_tree(Translate_context* context, tree type_tree);
10853
10854  private:
10855   // The type of the array to construct.
10856   Type* type_;
10857   // The list of values.
10858   Expression_list* vals_;
10859 };
10860
10861 // Traversal.
10862
10863 int
10864 Array_construction_expression::do_traverse(Traverse* traverse)
10865 {
10866   if (this->vals_ != NULL
10867       && this->vals_->traverse(traverse) == TRAVERSE_EXIT)
10868     return TRAVERSE_EXIT;
10869   if (Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
10870     return TRAVERSE_EXIT;
10871   return TRAVERSE_CONTINUE;
10872 }
10873
10874 // Return whether this is a constant initializer.
10875
10876 bool
10877 Array_construction_expression::is_constant_array() const
10878 {
10879   if (this->vals_ == NULL)
10880     return true;
10881
10882   // There are no constant constructors for interfaces.
10883   if (this->type_->array_type()->element_type()->interface_type() != NULL)
10884     return false;
10885
10886   for (Expression_list::const_iterator pv = this->vals_->begin();
10887        pv != this->vals_->end();
10888        ++pv)
10889     {
10890       if (*pv != NULL
10891           && !(*pv)->is_constant()
10892           && (!(*pv)->is_composite_literal()
10893               || (*pv)->is_nonconstant_composite_literal()))
10894         return false;
10895     }
10896   return true;
10897 }
10898
10899 // Final type determination.
10900
10901 void
10902 Array_construction_expression::do_determine_type(const Type_context*)
10903 {
10904   if (this->vals_ == NULL)
10905     return;
10906   Type_context subcontext(this->type_->array_type()->element_type(), false);
10907   for (Expression_list::const_iterator pv = this->vals_->begin();
10908        pv != this->vals_->end();
10909        ++pv)
10910     {
10911       if (*pv != NULL)
10912         (*pv)->determine_type(&subcontext);
10913     }
10914 }
10915
10916 // Check types.
10917
10918 void
10919 Array_construction_expression::do_check_types(Gogo*)
10920 {
10921   if (this->vals_ == NULL)
10922     return;
10923
10924   Array_type* at = this->type_->array_type();
10925   int i = 0;
10926   Type* element_type = at->element_type();
10927   for (Expression_list::const_iterator pv = this->vals_->begin();
10928        pv != this->vals_->end();
10929        ++pv, ++i)
10930     {
10931       if (*pv != NULL
10932           && !Type::are_assignable(element_type, (*pv)->type(), NULL))
10933         {
10934           error_at((*pv)->location(),
10935                    "incompatible type for element %d in composite literal",
10936                    i + 1);
10937           this->set_is_error();
10938         }
10939     }
10940
10941   Expression* length = at->length();
10942   if (length != NULL)
10943     {
10944       mpz_t val;
10945       mpz_init(val);
10946       Type* type;
10947       if (at->length()->integer_constant_value(true, val, &type))
10948         {
10949           if (this->vals_->size() > mpz_get_ui(val))
10950             this->report_error(_("too many elements in composite literal"));
10951         }
10952       mpz_clear(val);
10953     }
10954 }
10955
10956 // Get a constructor tree for the array values.
10957
10958 tree
10959 Array_construction_expression::get_constructor_tree(Translate_context* context,
10960                                                     tree type_tree)
10961 {
10962   VEC(constructor_elt,gc)* values = VEC_alloc(constructor_elt, gc,
10963                                               (this->vals_ == NULL
10964                                                ? 0
10965                                                : this->vals_->size()));
10966   Type* element_type = this->type_->array_type()->element_type();
10967   bool is_constant = true;
10968   if (this->vals_ != NULL)
10969     {
10970       size_t i = 0;
10971       for (Expression_list::const_iterator pv = this->vals_->begin();
10972            pv != this->vals_->end();
10973            ++pv, ++i)
10974         {
10975           constructor_elt* elt = VEC_quick_push(constructor_elt, values, NULL);
10976           elt->index = size_int(i);
10977           if (*pv == NULL)
10978             elt->value = element_type->get_init_tree(context->gogo(), false);
10979           else
10980             {
10981               tree value_tree = (*pv)->get_tree(context);
10982               elt->value = Expression::convert_for_assignment(context,
10983                                                               element_type,
10984                                                               (*pv)->type(),
10985                                                               value_tree,
10986                                                               this->location());
10987             }
10988           if (elt->value == error_mark_node)
10989             return error_mark_node;
10990           if (!TREE_CONSTANT(elt->value))
10991             is_constant = false;
10992         }
10993     }
10994
10995   tree ret = build_constructor(type_tree, values);
10996   if (is_constant)
10997     TREE_CONSTANT(ret) = 1;
10998   return ret;
10999 }
11000
11001 // Export an array construction.
11002
11003 void
11004 Array_construction_expression::do_export(Export* exp) const
11005 {
11006   exp->write_c_string("convert(");
11007   exp->write_type(this->type_);
11008   if (this->vals_ != NULL)
11009     {
11010       for (Expression_list::const_iterator pv = this->vals_->begin();
11011            pv != this->vals_->end();
11012            ++pv)
11013         {
11014           exp->write_c_string(", ");
11015           if (*pv != NULL)
11016             (*pv)->export_expression(exp);
11017         }
11018     }
11019   exp->write_c_string(")");
11020 }
11021
11022 // Construct a fixed array.
11023
11024 class Fixed_array_construction_expression :
11025   public Array_construction_expression
11026 {
11027  public:
11028   Fixed_array_construction_expression(Type* type, Expression_list* vals,
11029                                       source_location location)
11030     : Array_construction_expression(EXPRESSION_FIXED_ARRAY_CONSTRUCTION,
11031                                     type, vals, location)
11032   {
11033     gcc_assert(type->array_type() != NULL
11034                && type->array_type()->length() != NULL);
11035   }
11036
11037  protected:
11038   Expression*
11039   do_copy()
11040   {
11041     return new Fixed_array_construction_expression(this->type(),
11042                                                    (this->vals() == NULL
11043                                                     ? NULL
11044                                                     : this->vals()->copy()),
11045                                                    this->location());
11046   }
11047
11048   tree
11049   do_get_tree(Translate_context*);
11050 };
11051
11052 // Return a tree for constructing a fixed array.
11053
11054 tree
11055 Fixed_array_construction_expression::do_get_tree(Translate_context* context)
11056 {
11057   return this->get_constructor_tree(context,
11058                                     this->type()->get_tree(context->gogo()));
11059 }
11060
11061 // Construct an open array.
11062
11063 class Open_array_construction_expression : public Array_construction_expression
11064 {
11065  public:
11066   Open_array_construction_expression(Type* type, Expression_list* vals,
11067                                      source_location location)
11068     : Array_construction_expression(EXPRESSION_OPEN_ARRAY_CONSTRUCTION,
11069                                     type, vals, location)
11070   {
11071     gcc_assert(type->array_type() != NULL
11072                && type->array_type()->length() == NULL);
11073   }
11074
11075  protected:
11076   // Note that taking the address of an open array literal is invalid.
11077
11078   Expression*
11079   do_copy()
11080   {
11081     return new Open_array_construction_expression(this->type(),
11082                                                   (this->vals() == NULL
11083                                                    ? NULL
11084                                                    : this->vals()->copy()),
11085                                                   this->location());
11086   }
11087
11088   tree
11089   do_get_tree(Translate_context*);
11090 };
11091
11092 // Return a tree for constructing an open array.
11093
11094 tree
11095 Open_array_construction_expression::do_get_tree(Translate_context* context)
11096 {
11097   Array_type* array_type = this->type()->array_type();
11098   if (array_type == NULL)
11099     {
11100       gcc_assert(this->type()->is_error_type());
11101       return error_mark_node;
11102     }
11103
11104   Type* element_type = array_type->element_type();
11105   tree element_type_tree = element_type->get_tree(context->gogo());
11106   if (element_type_tree == error_mark_node)
11107     return error_mark_node;
11108
11109   tree values;
11110   tree length_tree;
11111   if (this->vals() == NULL || this->vals()->empty())
11112     {
11113       // We need to create a unique value.
11114       tree max = size_int(0);
11115       tree constructor_type = build_array_type(element_type_tree,
11116                                                build_index_type(max));
11117       if (constructor_type == error_mark_node)
11118         return error_mark_node;
11119       VEC(constructor_elt,gc)* vec = VEC_alloc(constructor_elt, gc, 1);
11120       constructor_elt* elt = VEC_quick_push(constructor_elt, vec, NULL);
11121       elt->index = size_int(0);
11122       elt->value = element_type->get_init_tree(context->gogo(), false);
11123       values = build_constructor(constructor_type, vec);
11124       if (TREE_CONSTANT(elt->value))
11125         TREE_CONSTANT(values) = 1;
11126       length_tree = size_int(0);
11127     }
11128   else
11129     {
11130       tree max = size_int(this->vals()->size() - 1);
11131       tree constructor_type = build_array_type(element_type_tree,
11132                                                build_index_type(max));
11133       if (constructor_type == error_mark_node)
11134         return error_mark_node;
11135       values = this->get_constructor_tree(context, constructor_type);
11136       length_tree = size_int(this->vals()->size());
11137     }
11138
11139   if (values == error_mark_node)
11140     return error_mark_node;
11141
11142   bool is_constant_initializer = TREE_CONSTANT(values);
11143   bool is_in_function = context->function() != NULL;
11144
11145   if (is_constant_initializer)
11146     {
11147       tree tmp = build_decl(this->location(), VAR_DECL,
11148                             create_tmp_var_name("C"), TREE_TYPE(values));
11149       DECL_EXTERNAL(tmp) = 0;
11150       TREE_PUBLIC(tmp) = 0;
11151       TREE_STATIC(tmp) = 1;
11152       DECL_ARTIFICIAL(tmp) = 1;
11153       if (is_in_function)
11154         {
11155           // If this is not a function, we will only initialize the
11156           // value once, so we can use this directly rather than
11157           // copying it.  In that case we can't make it read-only,
11158           // because the program is permitted to change it.
11159           TREE_READONLY(tmp) = 1;
11160           TREE_CONSTANT(tmp) = 1;
11161         }
11162       DECL_INITIAL(tmp) = values;
11163       rest_of_decl_compilation(tmp, 1, 0);
11164       values = tmp;
11165     }
11166
11167   tree space;
11168   tree set;
11169   if (!is_in_function && is_constant_initializer)
11170     {
11171       // Outside of a function, we know the initializer will only run
11172       // once.
11173       space = build_fold_addr_expr(values);
11174       set = NULL_TREE;
11175     }
11176   else
11177     {
11178       tree memsize = TYPE_SIZE_UNIT(TREE_TYPE(values));
11179       space = context->gogo()->allocate_memory(element_type, memsize,
11180                                                this->location());
11181       space = save_expr(space);
11182
11183       tree s = fold_convert(build_pointer_type(TREE_TYPE(values)), space);
11184       tree ref = build_fold_indirect_ref_loc(this->location(), s);
11185       TREE_THIS_NOTRAP(ref) = 1;
11186       set = build2(MODIFY_EXPR, void_type_node, ref, values);
11187     }
11188
11189   // Build a constructor for the open array.
11190
11191   tree type_tree = this->type()->get_tree(context->gogo());
11192   if (type_tree == error_mark_node)
11193     return error_mark_node;
11194   gcc_assert(TREE_CODE(type_tree) == RECORD_TYPE);
11195
11196   VEC(constructor_elt,gc)* init = VEC_alloc(constructor_elt, gc, 3);
11197
11198   constructor_elt* elt = VEC_quick_push(constructor_elt, init, NULL);
11199   tree field = TYPE_FIELDS(type_tree);
11200   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__values") == 0);
11201   elt->index = field;
11202   elt->value = fold_convert(TREE_TYPE(field), space);
11203
11204   elt = VEC_quick_push(constructor_elt, init, NULL);
11205   field = DECL_CHAIN(field);
11206   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__count") == 0);
11207   elt->index = field;
11208   elt->value = fold_convert(TREE_TYPE(field), length_tree);
11209
11210   elt = VEC_quick_push(constructor_elt, init, NULL);
11211   field = DECL_CHAIN(field);
11212   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)),"__capacity") == 0);
11213   elt->index = field;
11214   elt->value = fold_convert(TREE_TYPE(field), length_tree);
11215
11216   tree constructor = build_constructor(type_tree, init);
11217   if (constructor == error_mark_node)
11218     return error_mark_node;
11219   if (!is_in_function && is_constant_initializer)
11220     TREE_CONSTANT(constructor) = 1;
11221
11222   if (set == NULL_TREE)
11223     return constructor;
11224   else
11225     return build2(COMPOUND_EXPR, type_tree, set, constructor);
11226 }
11227
11228 // Make a slice composite literal.  This is used by the type
11229 // descriptor code.
11230
11231 Expression*
11232 Expression::make_slice_composite_literal(Type* type, Expression_list* vals,
11233                                          source_location location)
11234 {
11235   gcc_assert(type->is_open_array_type());
11236   return new Open_array_construction_expression(type, vals, location);
11237 }
11238
11239 // Construct a map.
11240
11241 class Map_construction_expression : public Expression
11242 {
11243  public:
11244   Map_construction_expression(Type* type, Expression_list* vals,
11245                               source_location location)
11246     : Expression(EXPRESSION_MAP_CONSTRUCTION, location),
11247       type_(type), vals_(vals)
11248   { gcc_assert(vals == NULL || vals->size() % 2 == 0); }
11249
11250  protected:
11251   int
11252   do_traverse(Traverse* traverse);
11253
11254   Type*
11255   do_type()
11256   { return this->type_; }
11257
11258   void
11259   do_determine_type(const Type_context*);
11260
11261   void
11262   do_check_types(Gogo*);
11263
11264   Expression*
11265   do_copy()
11266   {
11267     return new Map_construction_expression(this->type_, this->vals_->copy(),
11268                                            this->location());
11269   }
11270
11271   tree
11272   do_get_tree(Translate_context*);
11273
11274   void
11275   do_export(Export*) const;
11276
11277  private:
11278   // The type of the map to construct.
11279   Type* type_;
11280   // The list of values.
11281   Expression_list* vals_;
11282 };
11283
11284 // Traversal.
11285
11286 int
11287 Map_construction_expression::do_traverse(Traverse* traverse)
11288 {
11289   if (this->vals_ != NULL
11290       && this->vals_->traverse(traverse) == TRAVERSE_EXIT)
11291     return TRAVERSE_EXIT;
11292   if (Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
11293     return TRAVERSE_EXIT;
11294   return TRAVERSE_CONTINUE;
11295 }
11296
11297 // Final type determination.
11298
11299 void
11300 Map_construction_expression::do_determine_type(const Type_context*)
11301 {
11302   if (this->vals_ == NULL)
11303     return;
11304
11305   Map_type* mt = this->type_->map_type();
11306   Type_context key_context(mt->key_type(), false);
11307   Type_context val_context(mt->val_type(), false);
11308   for (Expression_list::const_iterator pv = this->vals_->begin();
11309        pv != this->vals_->end();
11310        ++pv)
11311     {
11312       (*pv)->determine_type(&key_context);
11313       ++pv;
11314       (*pv)->determine_type(&val_context);
11315     }
11316 }
11317
11318 // Check types.
11319
11320 void
11321 Map_construction_expression::do_check_types(Gogo*)
11322 {
11323   if (this->vals_ == NULL)
11324     return;
11325
11326   Map_type* mt = this->type_->map_type();
11327   int i = 0;
11328   Type* key_type = mt->key_type();
11329   Type* val_type = mt->val_type();
11330   for (Expression_list::const_iterator pv = this->vals_->begin();
11331        pv != this->vals_->end();
11332        ++pv, ++i)
11333     {
11334       if (!Type::are_assignable(key_type, (*pv)->type(), NULL))
11335         {
11336           error_at((*pv)->location(),
11337                    "incompatible type for element %d key in map construction",
11338                    i + 1);
11339           this->set_is_error();
11340         }
11341       ++pv;
11342       if (!Type::are_assignable(val_type, (*pv)->type(), NULL))
11343         {
11344           error_at((*pv)->location(),
11345                    ("incompatible type for element %d value "
11346                     "in map construction"),
11347                    i + 1);
11348           this->set_is_error();
11349         }
11350     }
11351 }
11352
11353 // Return a tree for constructing a map.
11354
11355 tree
11356 Map_construction_expression::do_get_tree(Translate_context* context)
11357 {
11358   Gogo* gogo = context->gogo();
11359   source_location loc = this->location();
11360
11361   Map_type* mt = this->type_->map_type();
11362
11363   // Build a struct to hold the key and value.
11364   tree struct_type = make_node(RECORD_TYPE);
11365
11366   Type* key_type = mt->key_type();
11367   tree id = get_identifier("__key");
11368   tree key_type_tree = key_type->get_tree(gogo);
11369   if (key_type_tree == error_mark_node)
11370     return error_mark_node;
11371   tree key_field = build_decl(loc, FIELD_DECL, id, key_type_tree);
11372   DECL_CONTEXT(key_field) = struct_type;
11373   TYPE_FIELDS(struct_type) = key_field;
11374
11375   Type* val_type = mt->val_type();
11376   id = get_identifier("__val");
11377   tree val_type_tree = val_type->get_tree(gogo);
11378   if (val_type_tree == error_mark_node)
11379     return error_mark_node;
11380   tree val_field = build_decl(loc, FIELD_DECL, id, val_type_tree);
11381   DECL_CONTEXT(val_field) = struct_type;
11382   DECL_CHAIN(key_field) = val_field;
11383
11384   layout_type(struct_type);
11385
11386   bool is_constant = true;
11387   size_t i = 0;
11388   tree valaddr;
11389   tree make_tmp;
11390
11391   if (this->vals_ == NULL || this->vals_->empty())
11392     {
11393       valaddr = null_pointer_node;
11394       make_tmp = NULL_TREE;
11395     }
11396   else
11397     {
11398       VEC(constructor_elt,gc)* values = VEC_alloc(constructor_elt, gc,
11399                                                   this->vals_->size() / 2);
11400
11401       for (Expression_list::const_iterator pv = this->vals_->begin();
11402            pv != this->vals_->end();
11403            ++pv, ++i)
11404         {
11405           bool one_is_constant = true;
11406
11407           VEC(constructor_elt,gc)* one = VEC_alloc(constructor_elt, gc, 2);
11408
11409           constructor_elt* elt = VEC_quick_push(constructor_elt, one, NULL);
11410           elt->index = key_field;
11411           tree val_tree = (*pv)->get_tree(context);
11412           elt->value = Expression::convert_for_assignment(context, key_type,
11413                                                           (*pv)->type(),
11414                                                           val_tree, loc);
11415           if (elt->value == error_mark_node)
11416             return error_mark_node;
11417           if (!TREE_CONSTANT(elt->value))
11418             one_is_constant = false;
11419
11420           ++pv;
11421
11422           elt = VEC_quick_push(constructor_elt, one, NULL);
11423           elt->index = val_field;
11424           val_tree = (*pv)->get_tree(context);
11425           elt->value = Expression::convert_for_assignment(context, val_type,
11426                                                           (*pv)->type(),
11427                                                           val_tree, loc);
11428           if (elt->value == error_mark_node)
11429             return error_mark_node;
11430           if (!TREE_CONSTANT(elt->value))
11431             one_is_constant = false;
11432
11433           elt = VEC_quick_push(constructor_elt, values, NULL);
11434           elt->index = size_int(i);
11435           elt->value = build_constructor(struct_type, one);
11436           if (one_is_constant)
11437             TREE_CONSTANT(elt->value) = 1;
11438           else
11439             is_constant = false;
11440         }
11441
11442       tree index_type = build_index_type(size_int(i - 1));
11443       tree array_type = build_array_type(struct_type, index_type);
11444       tree init = build_constructor(array_type, values);
11445       if (is_constant)
11446         TREE_CONSTANT(init) = 1;
11447       tree tmp;
11448       if (current_function_decl != NULL)
11449         {
11450           tmp = create_tmp_var(array_type, get_name(array_type));
11451           DECL_INITIAL(tmp) = init;
11452           make_tmp = fold_build1_loc(loc, DECL_EXPR, void_type_node, tmp);
11453           TREE_ADDRESSABLE(tmp) = 1;
11454         }
11455       else
11456         {
11457           tmp = build_decl(loc, VAR_DECL, create_tmp_var_name("M"), array_type);
11458           DECL_EXTERNAL(tmp) = 0;
11459           TREE_PUBLIC(tmp) = 0;
11460           TREE_STATIC(tmp) = 1;
11461           DECL_ARTIFICIAL(tmp) = 1;
11462           if (!TREE_CONSTANT(init))
11463             make_tmp = fold_build2_loc(loc, INIT_EXPR, void_type_node, tmp,
11464                                        init);
11465           else
11466             {
11467               TREE_READONLY(tmp) = 1;
11468               TREE_CONSTANT(tmp) = 1;
11469               DECL_INITIAL(tmp) = init;
11470               make_tmp = NULL_TREE;
11471             }
11472           rest_of_decl_compilation(tmp, 1, 0);
11473         }
11474
11475       valaddr = build_fold_addr_expr(tmp);
11476     }
11477
11478   tree descriptor = gogo->map_descriptor(mt);
11479
11480   tree type_tree = this->type_->get_tree(gogo);
11481   if (type_tree == error_mark_node)
11482     return error_mark_node;
11483
11484   static tree construct_map_fndecl;
11485   tree call = Gogo::call_builtin(&construct_map_fndecl,
11486                                  loc,
11487                                  "__go_construct_map",
11488                                  6,
11489                                  type_tree,
11490                                  TREE_TYPE(descriptor),
11491                                  descriptor,
11492                                  sizetype,
11493                                  size_int(i),
11494                                  sizetype,
11495                                  TYPE_SIZE_UNIT(struct_type),
11496                                  sizetype,
11497                                  byte_position(val_field),
11498                                  sizetype,
11499                                  TYPE_SIZE_UNIT(TREE_TYPE(val_field)),
11500                                  const_ptr_type_node,
11501                                  fold_convert(const_ptr_type_node, valaddr));
11502   if (call == error_mark_node)
11503     return error_mark_node;
11504
11505   tree ret;
11506   if (make_tmp == NULL)
11507     ret = call;
11508   else
11509     ret = fold_build2_loc(loc, COMPOUND_EXPR, type_tree, make_tmp, call);
11510   return ret;
11511 }
11512
11513 // Export an array construction.
11514
11515 void
11516 Map_construction_expression::do_export(Export* exp) const
11517 {
11518   exp->write_c_string("convert(");
11519   exp->write_type(this->type_);
11520   for (Expression_list::const_iterator pv = this->vals_->begin();
11521        pv != this->vals_->end();
11522        ++pv)
11523     {
11524       exp->write_c_string(", ");
11525       (*pv)->export_expression(exp);
11526     }
11527   exp->write_c_string(")");
11528 }
11529
11530 // A general composite literal.  This is lowered to a type specific
11531 // version.
11532
11533 class Composite_literal_expression : public Parser_expression
11534 {
11535  public:
11536   Composite_literal_expression(Type* type, int depth, bool has_keys,
11537                                Expression_list* vals, source_location location)
11538     : Parser_expression(EXPRESSION_COMPOSITE_LITERAL, location),
11539       type_(type), depth_(depth), vals_(vals), has_keys_(has_keys)
11540   { }
11541
11542  protected:
11543   int
11544   do_traverse(Traverse* traverse);
11545
11546   Expression*
11547   do_lower(Gogo*, Named_object*, int);
11548
11549   Expression*
11550   do_copy()
11551   {
11552     return new Composite_literal_expression(this->type_, this->depth_,
11553                                             this->has_keys_,
11554                                             (this->vals_ == NULL
11555                                              ? NULL
11556                                              : this->vals_->copy()),
11557                                             this->location());
11558   }
11559
11560  private:
11561   Expression*
11562   lower_struct(Type*);
11563
11564   Expression*
11565   lower_array(Type*);
11566
11567   Expression*
11568   make_array(Type*, Expression_list*);
11569
11570   Expression*
11571   lower_map(Gogo*, Named_object*, Type*);
11572
11573   // The type of the composite literal.
11574   Type* type_;
11575   // The depth within a list of composite literals within a composite
11576   // literal, when the type is omitted.
11577   int depth_;
11578   // The values to put in the composite literal.
11579   Expression_list* vals_;
11580   // If this is true, then VALS_ is a list of pairs: a key and a
11581   // value.  In an array initializer, a missing key will be NULL.
11582   bool has_keys_;
11583 };
11584
11585 // Traversal.
11586
11587 int
11588 Composite_literal_expression::do_traverse(Traverse* traverse)
11589 {
11590   if (this->vals_ != NULL
11591       && this->vals_->traverse(traverse) == TRAVERSE_EXIT)
11592     return TRAVERSE_EXIT;
11593   return Type::traverse(this->type_, traverse);
11594 }
11595
11596 // Lower a generic composite literal into a specific version based on
11597 // the type.
11598
11599 Expression*
11600 Composite_literal_expression::do_lower(Gogo* gogo, Named_object* function, int)
11601 {
11602   Type* type = this->type_;
11603
11604   for (int depth = this->depth_; depth > 0; --depth)
11605     {
11606       if (type->array_type() != NULL)
11607         type = type->array_type()->element_type();
11608       else if (type->map_type() != NULL)
11609         type = type->map_type()->val_type();
11610       else
11611         {
11612           if (!type->is_error_type())
11613             error_at(this->location(),
11614                      ("may only omit types within composite literals "
11615                       "of slice, array, or map type"));
11616           return Expression::make_error(this->location());
11617         }
11618     }
11619
11620   if (type->is_error_type())
11621     return Expression::make_error(this->location());
11622   else if (type->struct_type() != NULL)
11623     return this->lower_struct(type);
11624   else if (type->array_type() != NULL)
11625     return this->lower_array(type);
11626   else if (type->map_type() != NULL)
11627     return this->lower_map(gogo, function, type);
11628   else
11629     {
11630       error_at(this->location(),
11631                ("expected struct, slice, array, or map type "
11632                 "for composite literal"));
11633       return Expression::make_error(this->location());
11634     }
11635 }
11636
11637 // Lower a struct composite literal.
11638
11639 Expression*
11640 Composite_literal_expression::lower_struct(Type* type)
11641 {
11642   source_location location = this->location();
11643   Struct_type* st = type->struct_type();
11644   if (this->vals_ == NULL || !this->has_keys_)
11645     return new Struct_construction_expression(type, this->vals_, location);
11646
11647   size_t field_count = st->field_count();
11648   std::vector<Expression*> vals(field_count);
11649   Expression_list::const_iterator p = this->vals_->begin();
11650   while (p != this->vals_->end())
11651     {
11652       Expression* name_expr = *p;
11653
11654       ++p;
11655       gcc_assert(p != this->vals_->end());
11656       Expression* val = *p;
11657
11658       ++p;
11659
11660       if (name_expr == NULL)
11661         {
11662           error_at(val->location(), "mixture of field and value initializers");
11663           return Expression::make_error(location);
11664         }
11665
11666       bool bad_key = false;
11667       std::string name;
11668       switch (name_expr->classification())
11669         {
11670         case EXPRESSION_UNKNOWN_REFERENCE:
11671           name = name_expr->unknown_expression()->name();
11672           break;
11673
11674         case EXPRESSION_CONST_REFERENCE:
11675           name = static_cast<Const_expression*>(name_expr)->name();
11676           break;
11677
11678         case EXPRESSION_TYPE:
11679           {
11680             Type* t = name_expr->type();
11681             Named_type* nt = t->named_type();
11682             if (nt == NULL)
11683               bad_key = true;
11684             else
11685               name = nt->name();
11686           }
11687           break;
11688
11689         case EXPRESSION_VAR_REFERENCE:
11690           name = name_expr->var_expression()->name();
11691           break;
11692
11693         case EXPRESSION_FUNC_REFERENCE:
11694           name = name_expr->func_expression()->name();
11695           break;
11696
11697         case EXPRESSION_UNARY:
11698           // If there is a local variable around with the same name as
11699           // the field, and this occurs in the closure, then the
11700           // parser may turn the field reference into an indirection
11701           // through the closure.  FIXME: This is a mess.
11702           {
11703             bad_key = true;
11704             Unary_expression* ue = static_cast<Unary_expression*>(name_expr);
11705             if (ue->op() == OPERATOR_MULT)
11706               {
11707                 Field_reference_expression* fre =
11708                   ue->operand()->field_reference_expression();
11709                 if (fre != NULL)
11710                   {
11711                     Struct_type* st =
11712                       fre->expr()->type()->deref()->struct_type();
11713                     if (st != NULL)
11714                       {
11715                         const Struct_field* sf = st->field(fre->field_index());
11716                         name = sf->field_name();
11717                         char buf[20];
11718                         snprintf(buf, sizeof buf, "%u", fre->field_index());
11719                         size_t buflen = strlen(buf);
11720                         if (name.compare(name.length() - buflen, buflen, buf)
11721                             == 0)
11722                           {
11723                             name = name.substr(0, name.length() - buflen);
11724                             bad_key = false;
11725                           }
11726                       }
11727                   }
11728               }
11729           }
11730           break;
11731
11732         default:
11733           bad_key = true;
11734           break;
11735         }
11736       if (bad_key)
11737         {
11738           error_at(name_expr->location(), "expected struct field name");
11739           return Expression::make_error(location);
11740         }
11741
11742       unsigned int index;
11743       const Struct_field* sf = st->find_local_field(name, &index);
11744       if (sf == NULL)
11745         {
11746           error_at(name_expr->location(), "unknown field %qs in %qs",
11747                    Gogo::message_name(name).c_str(),
11748                    (type->named_type() != NULL
11749                     ? type->named_type()->message_name().c_str()
11750                     : "unnamed struct"));
11751           return Expression::make_error(location);
11752         }
11753       if (vals[index] != NULL)
11754         {
11755           error_at(name_expr->location(),
11756                    "duplicate value for field %qs in %qs",
11757                    Gogo::message_name(name).c_str(),
11758                    (type->named_type() != NULL
11759                     ? type->named_type()->message_name().c_str()
11760                     : "unnamed struct"));
11761           return Expression::make_error(location);
11762         }
11763
11764       vals[index] = val;
11765     }
11766
11767   Expression_list* list = new Expression_list;
11768   list->reserve(field_count);
11769   for (size_t i = 0; i < field_count; ++i)
11770     list->push_back(vals[i]);
11771
11772   return new Struct_construction_expression(type, list, location);
11773 }
11774
11775 // Lower an array composite literal.
11776
11777 Expression*
11778 Composite_literal_expression::lower_array(Type* type)
11779 {
11780   source_location location = this->location();
11781   if (this->vals_ == NULL || !this->has_keys_)
11782     return this->make_array(type, this->vals_);
11783
11784   std::vector<Expression*> vals;
11785   vals.reserve(this->vals_->size());
11786   unsigned long index = 0;
11787   Expression_list::const_iterator p = this->vals_->begin();
11788   while (p != this->vals_->end())
11789     {
11790       Expression* index_expr = *p;
11791
11792       ++p;
11793       gcc_assert(p != this->vals_->end());
11794       Expression* val = *p;
11795
11796       ++p;
11797
11798       if (index_expr != NULL)
11799         {
11800           mpz_t ival;
11801           mpz_init(ival);
11802           Type* dummy;
11803           if (!index_expr->integer_constant_value(true, ival, &dummy))
11804             {
11805               mpz_clear(ival);
11806               error_at(index_expr->location(),
11807                        "index expression is not integer constant");
11808               return Expression::make_error(location);
11809             }
11810           if (mpz_sgn(ival) < 0)
11811             {
11812               mpz_clear(ival);
11813               error_at(index_expr->location(), "index expression is negative");
11814               return Expression::make_error(location);
11815             }
11816           index = mpz_get_ui(ival);
11817           if (mpz_cmp_ui(ival, index) != 0)
11818             {
11819               mpz_clear(ival);
11820               error_at(index_expr->location(), "index value overflow");
11821               return Expression::make_error(location);
11822             }
11823           mpz_clear(ival);
11824         }
11825
11826       if (index == vals.size())
11827         vals.push_back(val);
11828       else
11829         {
11830           if (index > vals.size())
11831             {
11832               vals.reserve(index + 32);
11833               vals.resize(index + 1, static_cast<Expression*>(NULL));
11834             }
11835           if (vals[index] != NULL)
11836             {
11837               error_at((index_expr != NULL
11838                         ? index_expr->location()
11839                         : val->location()),
11840                        "duplicate value for index %lu",
11841                        index);
11842               return Expression::make_error(location);
11843             }
11844           vals[index] = val;
11845         }
11846
11847       ++index;
11848     }
11849
11850   size_t size = vals.size();
11851   Expression_list* list = new Expression_list;
11852   list->reserve(size);
11853   for (size_t i = 0; i < size; ++i)
11854     list->push_back(vals[i]);
11855
11856   return this->make_array(type, list);
11857 }
11858
11859 // Actually build the array composite literal. This handles
11860 // [...]{...}.
11861
11862 Expression*
11863 Composite_literal_expression::make_array(Type* type, Expression_list* vals)
11864 {
11865   source_location location = this->location();
11866   Array_type* at = type->array_type();
11867   if (at->length() != NULL && at->length()->is_nil_expression())
11868     {
11869       size_t size = vals == NULL ? 0 : vals->size();
11870       mpz_t vlen;
11871       mpz_init_set_ui(vlen, size);
11872       Expression* elen = Expression::make_integer(&vlen, NULL, location);
11873       mpz_clear(vlen);
11874       at = Type::make_array_type(at->element_type(), elen);
11875       type = at;
11876     }
11877   if (at->length() != NULL)
11878     return new Fixed_array_construction_expression(type, vals, location);
11879   else
11880     return new Open_array_construction_expression(type, vals, location);
11881 }
11882
11883 // Lower a map composite literal.
11884
11885 Expression*
11886 Composite_literal_expression::lower_map(Gogo* gogo, Named_object* function,
11887                                         Type* type)
11888 {
11889   source_location location = this->location();
11890   if (this->vals_ != NULL)
11891     {
11892       if (!this->has_keys_)
11893         {
11894           error_at(location, "map composite literal must have keys");
11895           return Expression::make_error(location);
11896         }
11897
11898       for (Expression_list::iterator p = this->vals_->begin();
11899            p != this->vals_->end();
11900            p += 2)
11901         {
11902           if (*p == NULL)
11903             {
11904               ++p;
11905               error_at((*p)->location(),
11906                        "map composite literal must have keys for every value");
11907               return Expression::make_error(location);
11908             }
11909           // Make sure we have lowered the key; it may not have been
11910           // lowered in order to handle keys for struct composite
11911           // literals.  Lower it now to get the right error message.
11912           if ((*p)->unknown_expression() != NULL)
11913             {
11914               (*p)->unknown_expression()->clear_is_composite_literal_key();
11915               gogo->lower_expression(function, &*p);
11916               gcc_assert((*p)->is_error_expression());
11917               return Expression::make_error(location);
11918             }
11919         }
11920     }
11921
11922   return new Map_construction_expression(type, this->vals_, location);
11923 }
11924
11925 // Make a composite literal expression.
11926
11927 Expression*
11928 Expression::make_composite_literal(Type* type, int depth, bool has_keys,
11929                                    Expression_list* vals,
11930                                    source_location location)
11931 {
11932   return new Composite_literal_expression(type, depth, has_keys, vals,
11933                                           location);
11934 }
11935
11936 // Return whether this expression is a composite literal.
11937
11938 bool
11939 Expression::is_composite_literal() const
11940 {
11941   switch (this->classification_)
11942     {
11943     case EXPRESSION_COMPOSITE_LITERAL:
11944     case EXPRESSION_STRUCT_CONSTRUCTION:
11945     case EXPRESSION_FIXED_ARRAY_CONSTRUCTION:
11946     case EXPRESSION_OPEN_ARRAY_CONSTRUCTION:
11947     case EXPRESSION_MAP_CONSTRUCTION:
11948       return true;
11949     default:
11950       return false;
11951     }
11952 }
11953
11954 // Return whether this expression is a composite literal which is not
11955 // constant.
11956
11957 bool
11958 Expression::is_nonconstant_composite_literal() const
11959 {
11960   switch (this->classification_)
11961     {
11962     case EXPRESSION_STRUCT_CONSTRUCTION:
11963       {
11964         const Struct_construction_expression *psce =
11965           static_cast<const Struct_construction_expression*>(this);
11966         return !psce->is_constant_struct();
11967       }
11968     case EXPRESSION_FIXED_ARRAY_CONSTRUCTION:
11969       {
11970         const Fixed_array_construction_expression *pace =
11971           static_cast<const Fixed_array_construction_expression*>(this);
11972         return !pace->is_constant_array();
11973       }
11974     case EXPRESSION_OPEN_ARRAY_CONSTRUCTION:
11975       {
11976         const Open_array_construction_expression *pace =
11977           static_cast<const Open_array_construction_expression*>(this);
11978         return !pace->is_constant_array();
11979       }
11980     case EXPRESSION_MAP_CONSTRUCTION:
11981       return true;
11982     default:
11983       return false;
11984     }
11985 }
11986
11987 // Return true if this is a reference to a local variable.
11988
11989 bool
11990 Expression::is_local_variable() const
11991 {
11992   const Var_expression* ve = this->var_expression();
11993   if (ve == NULL)
11994     return false;
11995   const Named_object* no = ve->named_object();
11996   return (no->is_result_variable()
11997           || (no->is_variable() && !no->var_value()->is_global()));
11998 }
11999
12000 // Class Type_guard_expression.
12001
12002 // Traversal.
12003
12004 int
12005 Type_guard_expression::do_traverse(Traverse* traverse)
12006 {
12007   if (Expression::traverse(&this->expr_, traverse) == TRAVERSE_EXIT
12008       || Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
12009     return TRAVERSE_EXIT;
12010   return TRAVERSE_CONTINUE;
12011 }
12012
12013 // Check types of a type guard expression.  The expression must have
12014 // an interface type, but the actual type conversion is checked at run
12015 // time.
12016
12017 void
12018 Type_guard_expression::do_check_types(Gogo*)
12019 {
12020   // 6g permits using a type guard with unsafe.pointer; we are
12021   // compatible.
12022   Type* expr_type = this->expr_->type();
12023   if (expr_type->is_unsafe_pointer_type())
12024     {
12025       if (this->type_->points_to() == NULL
12026           && (this->type_->integer_type() == NULL
12027               || (this->type_->forwarded()
12028                   != Type::lookup_integer_type("uintptr"))))
12029         this->report_error(_("invalid unsafe.Pointer conversion"));
12030     }
12031   else if (this->type_->is_unsafe_pointer_type())
12032     {
12033       if (expr_type->points_to() == NULL
12034           && (expr_type->integer_type() == NULL
12035               || (expr_type->forwarded()
12036                   != Type::lookup_integer_type("uintptr"))))
12037         this->report_error(_("invalid unsafe.Pointer conversion"));
12038     }
12039   else if (expr_type->interface_type() == NULL)
12040     {
12041       if (!expr_type->is_error_type() && !this->type_->is_error_type())
12042         this->report_error(_("type assertion only valid for interface types"));
12043       this->set_is_error();
12044     }
12045   else if (this->type_->interface_type() == NULL)
12046     {
12047       std::string reason;
12048       if (!expr_type->interface_type()->implements_interface(this->type_,
12049                                                              &reason))
12050         {
12051           if (!this->type_->is_error_type())
12052             {
12053               if (reason.empty())
12054                 this->report_error(_("impossible type assertion: "
12055                                      "type does not implement interface"));
12056               else
12057                 error_at(this->location(),
12058                          ("impossible type assertion: "
12059                           "type does not implement interface (%s)"),
12060                          reason.c_str());
12061             }
12062           this->set_is_error();
12063         }
12064     }
12065 }
12066
12067 // Return a tree for a type guard expression.
12068
12069 tree
12070 Type_guard_expression::do_get_tree(Translate_context* context)
12071 {
12072   Gogo* gogo = context->gogo();
12073   tree expr_tree = this->expr_->get_tree(context);
12074   if (expr_tree == error_mark_node)
12075     return error_mark_node;
12076   Type* expr_type = this->expr_->type();
12077   if ((this->type_->is_unsafe_pointer_type()
12078        && (expr_type->points_to() != NULL
12079            || expr_type->integer_type() != NULL))
12080       || (expr_type->is_unsafe_pointer_type()
12081           && this->type_->points_to() != NULL))
12082     return convert_to_pointer(this->type_->get_tree(gogo), expr_tree);
12083   else if (expr_type->is_unsafe_pointer_type()
12084            && this->type_->integer_type() != NULL)
12085     return convert_to_integer(this->type_->get_tree(gogo), expr_tree);
12086   else if (this->type_->interface_type() != NULL)
12087     return Expression::convert_interface_to_interface(context, this->type_,
12088                                                       this->expr_->type(),
12089                                                       expr_tree, true,
12090                                                       this->location());
12091   else
12092     return Expression::convert_for_assignment(context, this->type_,
12093                                               this->expr_->type(), expr_tree,
12094                                               this->location());
12095 }
12096
12097 // Make a type guard expression.
12098
12099 Expression*
12100 Expression::make_type_guard(Expression* expr, Type* type,
12101                             source_location location)
12102 {
12103   return new Type_guard_expression(expr, type, location);
12104 }
12105
12106 // Class Heap_composite_expression.
12107
12108 // When you take the address of a composite literal, it is allocated
12109 // on the heap.  This class implements that.
12110
12111 class Heap_composite_expression : public Expression
12112 {
12113  public:
12114   Heap_composite_expression(Expression* expr, source_location location)
12115     : Expression(EXPRESSION_HEAP_COMPOSITE, location),
12116       expr_(expr)
12117   { }
12118
12119  protected:
12120   int
12121   do_traverse(Traverse* traverse)
12122   { return Expression::traverse(&this->expr_, traverse); }
12123
12124   Type*
12125   do_type()
12126   { return Type::make_pointer_type(this->expr_->type()); }
12127
12128   void
12129   do_determine_type(const Type_context*)
12130   { this->expr_->determine_type_no_context(); }
12131
12132   Expression*
12133   do_copy()
12134   {
12135     return Expression::make_heap_composite(this->expr_->copy(),
12136                                            this->location());
12137   }
12138
12139   tree
12140   do_get_tree(Translate_context*);
12141
12142   // We only export global objects, and the parser does not generate
12143   // this in global scope.
12144   void
12145   do_export(Export*) const
12146   { gcc_unreachable(); }
12147
12148  private:
12149   // The composite literal which is being put on the heap.
12150   Expression* expr_;
12151 };
12152
12153 // Return a tree which allocates a composite literal on the heap.
12154
12155 tree
12156 Heap_composite_expression::do_get_tree(Translate_context* context)
12157 {
12158   tree expr_tree = this->expr_->get_tree(context);
12159   if (expr_tree == error_mark_node)
12160     return error_mark_node;
12161   tree expr_size = TYPE_SIZE_UNIT(TREE_TYPE(expr_tree));
12162   gcc_assert(TREE_CODE(expr_size) == INTEGER_CST);
12163   tree space = context->gogo()->allocate_memory(this->expr_->type(),
12164                                                 expr_size, this->location());
12165   space = fold_convert(build_pointer_type(TREE_TYPE(expr_tree)), space);
12166   space = save_expr(space);
12167   tree ref = build_fold_indirect_ref_loc(this->location(), space);
12168   TREE_THIS_NOTRAP(ref) = 1;
12169   tree ret = build2(COMPOUND_EXPR, TREE_TYPE(space),
12170                     build2(MODIFY_EXPR, void_type_node, ref, expr_tree),
12171                     space);
12172   SET_EXPR_LOCATION(ret, this->location());
12173   return ret;
12174 }
12175
12176 // Allocate a composite literal on the heap.
12177
12178 Expression*
12179 Expression::make_heap_composite(Expression* expr, source_location location)
12180 {
12181   return new Heap_composite_expression(expr, location);
12182 }
12183
12184 // Class Receive_expression.
12185
12186 // Return the type of a receive expression.
12187
12188 Type*
12189 Receive_expression::do_type()
12190 {
12191   Channel_type* channel_type = this->channel_->type()->channel_type();
12192   if (channel_type == NULL)
12193     return Type::make_error_type();
12194   return channel_type->element_type();
12195 }
12196
12197 // Check types for a receive expression.
12198
12199 void
12200 Receive_expression::do_check_types(Gogo*)
12201 {
12202   Type* type = this->channel_->type();
12203   if (type->is_error_type())
12204     {
12205       this->set_is_error();
12206       return;
12207     }
12208   if (type->channel_type() == NULL)
12209     {
12210       this->report_error(_("expected channel"));
12211       return;
12212     }
12213   if (!type->channel_type()->may_receive())
12214     {
12215       this->report_error(_("invalid receive on send-only channel"));
12216       return;
12217     }
12218 }
12219
12220 // Get a tree for a receive expression.
12221
12222 tree
12223 Receive_expression::do_get_tree(Translate_context* context)
12224 {
12225   Channel_type* channel_type = this->channel_->type()->channel_type();
12226   gcc_assert(channel_type != NULL);
12227   Type* element_type = channel_type->element_type();
12228   tree element_type_tree = element_type->get_tree(context->gogo());
12229
12230   tree channel = this->channel_->get_tree(context);
12231   if (element_type_tree == error_mark_node || channel == error_mark_node)
12232     return error_mark_node;
12233
12234   return Gogo::receive_from_channel(element_type_tree, channel,
12235                                     this->for_select_, this->location());
12236 }
12237
12238 // Make a receive expression.
12239
12240 Receive_expression*
12241 Expression::make_receive(Expression* channel, source_location location)
12242 {
12243   return new Receive_expression(channel, location);
12244 }
12245
12246 // Class Send_expression.
12247
12248 // Traversal.
12249
12250 int
12251 Send_expression::do_traverse(Traverse* traverse)
12252 {
12253   if (Expression::traverse(&this->channel_, traverse) == TRAVERSE_EXIT)
12254     return TRAVERSE_EXIT;
12255   return Expression::traverse(&this->val_, traverse);
12256 }
12257
12258 // Get the type.
12259
12260 Type*
12261 Send_expression::do_type()
12262 {
12263   return Type::lookup_bool_type();
12264 }
12265
12266 // Set types.
12267
12268 void
12269 Send_expression::do_determine_type(const Type_context*)
12270 {
12271   this->channel_->determine_type_no_context();
12272
12273   Type* type = this->channel_->type();
12274   Type_context subcontext;
12275   if (type->channel_type() != NULL)
12276     subcontext.type = type->channel_type()->element_type();
12277   this->val_->determine_type(&subcontext);
12278 }
12279
12280 // Check types.
12281
12282 void
12283 Send_expression::do_check_types(Gogo*)
12284 {
12285   Type* type = this->channel_->type();
12286   if (type->is_error_type())
12287     {
12288       this->set_is_error();
12289       return;
12290     }
12291   Channel_type* channel_type = type->channel_type();
12292   if (channel_type == NULL)
12293     {
12294       error_at(this->location(), "left operand of %<<-%> must be channel");
12295       this->set_is_error();
12296       return;
12297     }
12298   Type* element_type = channel_type->element_type();
12299   if (element_type != NULL
12300       && !Type::are_assignable(element_type, this->val_->type(), NULL))
12301     {
12302       this->report_error(_("incompatible types in send"));
12303       return;
12304     }
12305   if (!channel_type->may_send())
12306     {
12307       this->report_error(_("invalid send on receive-only channel"));
12308       return;
12309     }
12310 }
12311
12312 // Get a tree for a send expression.
12313
12314 tree
12315 Send_expression::do_get_tree(Translate_context* context)
12316 {
12317   tree channel = this->channel_->get_tree(context);
12318   tree val = this->val_->get_tree(context);
12319   if (channel == error_mark_node || val == error_mark_node)
12320     return error_mark_node;
12321   Channel_type* channel_type = this->channel_->type()->channel_type();
12322   val = Expression::convert_for_assignment(context,
12323                                            channel_type->element_type(),
12324                                            this->val_->type(),
12325                                            val,
12326                                            this->location());
12327   return Gogo::send_on_channel(channel, val, this->is_value_discarded_,
12328                                this->for_select_, this->location());
12329 }
12330
12331 // Make a send expression
12332
12333 Send_expression*
12334 Expression::make_send(Expression* channel, Expression* val,
12335                       source_location location)
12336 {
12337   return new Send_expression(channel, val, location);
12338 }
12339
12340 // An expression which evaluates to a pointer to the type descriptor
12341 // of a type.
12342
12343 class Type_descriptor_expression : public Expression
12344 {
12345  public:
12346   Type_descriptor_expression(Type* type, source_location location)
12347     : Expression(EXPRESSION_TYPE_DESCRIPTOR, location),
12348       type_(type)
12349   { }
12350
12351  protected:
12352   Type*
12353   do_type()
12354   { return Type::make_type_descriptor_ptr_type(); }
12355
12356   void
12357   do_determine_type(const Type_context*)
12358   { }
12359
12360   Expression*
12361   do_copy()
12362   { return this; }
12363
12364   tree
12365   do_get_tree(Translate_context* context)
12366   { return this->type_->type_descriptor_pointer(context->gogo()); }
12367
12368  private:
12369   // The type for which this is the descriptor.
12370   Type* type_;
12371 };
12372
12373 // Make a type descriptor expression.
12374
12375 Expression*
12376 Expression::make_type_descriptor(Type* type, source_location location)
12377 {
12378   return new Type_descriptor_expression(type, location);
12379 }
12380
12381 // An expression which evaluates to some characteristic of a type.
12382 // This is only used to initialize fields of a type descriptor.  Using
12383 // a new expression class is slightly inefficient but gives us a good
12384 // separation between the frontend and the middle-end with regard to
12385 // how types are laid out.
12386
12387 class Type_info_expression : public Expression
12388 {
12389  public:
12390   Type_info_expression(Type* type, Type_info type_info)
12391     : Expression(EXPRESSION_TYPE_INFO, BUILTINS_LOCATION),
12392       type_(type), type_info_(type_info)
12393   { }
12394
12395  protected:
12396   Type*
12397   do_type();
12398
12399   void
12400   do_determine_type(const Type_context*)
12401   { }
12402
12403   Expression*
12404   do_copy()
12405   { return this; }
12406
12407   tree
12408   do_get_tree(Translate_context* context);
12409
12410  private:
12411   // The type for which we are getting information.
12412   Type* type_;
12413   // What information we want.
12414   Type_info type_info_;
12415 };
12416
12417 // The type is chosen to match what the type descriptor struct
12418 // expects.
12419
12420 Type*
12421 Type_info_expression::do_type()
12422 {
12423   switch (this->type_info_)
12424     {
12425     case TYPE_INFO_SIZE:
12426       return Type::lookup_integer_type("uintptr");
12427     case TYPE_INFO_ALIGNMENT:
12428     case TYPE_INFO_FIELD_ALIGNMENT:
12429       return Type::lookup_integer_type("uint8");
12430     default:
12431       gcc_unreachable();
12432     }
12433 }
12434
12435 // Return type information in GENERIC.
12436
12437 tree
12438 Type_info_expression::do_get_tree(Translate_context* context)
12439 {
12440   tree type_tree = this->type_->get_tree(context->gogo());
12441   if (type_tree == error_mark_node)
12442     return error_mark_node;
12443
12444   tree val_type_tree = this->type()->get_tree(context->gogo());
12445   gcc_assert(val_type_tree != error_mark_node);
12446
12447   if (this->type_info_ == TYPE_INFO_SIZE)
12448     return fold_convert_loc(BUILTINS_LOCATION, val_type_tree,
12449                             TYPE_SIZE_UNIT(type_tree));
12450   else
12451     {
12452       unsigned int val;
12453       if (this->type_info_ == TYPE_INFO_ALIGNMENT)
12454         val = go_type_alignment(type_tree);
12455       else
12456         val = go_field_alignment(type_tree);
12457       return build_int_cstu(val_type_tree, val);
12458     }
12459 }
12460
12461 // Make a type info expression.
12462
12463 Expression*
12464 Expression::make_type_info(Type* type, Type_info type_info)
12465 {
12466   return new Type_info_expression(type, type_info);
12467 }
12468
12469 // An expression which evaluates to the offset of a field within a
12470 // struct.  This, like Type_info_expression, q.v., is only used to
12471 // initialize fields of a type descriptor.
12472
12473 class Struct_field_offset_expression : public Expression
12474 {
12475  public:
12476   Struct_field_offset_expression(Struct_type* type, const Struct_field* field)
12477     : Expression(EXPRESSION_STRUCT_FIELD_OFFSET, BUILTINS_LOCATION),
12478       type_(type), field_(field)
12479   { }
12480
12481  protected:
12482   Type*
12483   do_type()
12484   { return Type::lookup_integer_type("uintptr"); }
12485
12486   void
12487   do_determine_type(const Type_context*)
12488   { }
12489
12490   Expression*
12491   do_copy()
12492   { return this; }
12493
12494   tree
12495   do_get_tree(Translate_context* context);
12496
12497  private:
12498   // The type of the struct.
12499   Struct_type* type_;
12500   // The field.
12501   const Struct_field* field_;
12502 };
12503
12504 // Return a struct field offset in GENERIC.
12505
12506 tree
12507 Struct_field_offset_expression::do_get_tree(Translate_context* context)
12508 {
12509   tree type_tree = this->type_->get_tree(context->gogo());
12510   if (type_tree == error_mark_node)
12511     return error_mark_node;
12512
12513   tree val_type_tree = this->type()->get_tree(context->gogo());
12514   gcc_assert(val_type_tree != error_mark_node);
12515
12516   const Struct_field_list* fields = this->type_->fields();
12517   tree struct_field_tree = TYPE_FIELDS(type_tree);
12518   Struct_field_list::const_iterator p;
12519   for (p = fields->begin();
12520        p != fields->end();
12521        ++p, struct_field_tree = DECL_CHAIN(struct_field_tree))
12522     {
12523       gcc_assert(struct_field_tree != NULL_TREE);
12524       if (&*p == this->field_)
12525         break;
12526     }
12527   gcc_assert(&*p == this->field_);
12528
12529   return fold_convert_loc(BUILTINS_LOCATION, val_type_tree,
12530                           byte_position(struct_field_tree));
12531 }
12532
12533 // Make an expression for a struct field offset.
12534
12535 Expression*
12536 Expression::make_struct_field_offset(Struct_type* type,
12537                                      const Struct_field* field)
12538 {
12539   return new Struct_field_offset_expression(type, field);
12540 }
12541
12542 // An expression which evaluates to the address of an unnamed label.
12543
12544 class Label_addr_expression : public Expression
12545 {
12546  public:
12547   Label_addr_expression(Label* label, source_location location)
12548     : Expression(EXPRESSION_LABEL_ADDR, location),
12549       label_(label)
12550   { }
12551
12552  protected:
12553   Type*
12554   do_type()
12555   { return Type::make_pointer_type(Type::make_void_type()); }
12556
12557   void
12558   do_determine_type(const Type_context*)
12559   { }
12560
12561   Expression*
12562   do_copy()
12563   { return new Label_addr_expression(this->label_, this->location()); }
12564
12565   tree
12566   do_get_tree(Translate_context*)
12567   { return this->label_->get_addr(this->location()); }
12568
12569  private:
12570   // The label whose address we are taking.
12571   Label* label_;
12572 };
12573
12574 // Make an expression for the address of an unnamed label.
12575
12576 Expression*
12577 Expression::make_label_addr(Label* label, source_location location)
12578 {
12579   return new Label_addr_expression(label, location);
12580 }
12581
12582 // Import an expression.  This comes at the end in order to see the
12583 // various class definitions.
12584
12585 Expression*
12586 Expression::import_expression(Import* imp)
12587 {
12588   int c = imp->peek_char();
12589   if (imp->match_c_string("- ")
12590       || imp->match_c_string("! ")
12591       || imp->match_c_string("^ "))
12592     return Unary_expression::do_import(imp);
12593   else if (c == '(')
12594     return Binary_expression::do_import(imp);
12595   else if (imp->match_c_string("true")
12596            || imp->match_c_string("false"))
12597     return Boolean_expression::do_import(imp);
12598   else if (c == '"')
12599     return String_expression::do_import(imp);
12600   else if (c == '-' || (c >= '0' && c <= '9'))
12601     {
12602       // This handles integers, floats and complex constants.
12603       return Integer_expression::do_import(imp);
12604     }
12605   else if (imp->match_c_string("nil"))
12606     return Nil_expression::do_import(imp);
12607   else if (imp->match_c_string("convert"))
12608     return Type_conversion_expression::do_import(imp);
12609   else
12610     {
12611       error_at(imp->location(), "import error: expected expression");
12612       return Expression::make_error(imp->location());
12613     }
12614 }
12615
12616 // Class Expression_list.
12617
12618 // Traverse the list.
12619
12620 int
12621 Expression_list::traverse(Traverse* traverse)
12622 {
12623   for (Expression_list::iterator p = this->begin();
12624        p != this->end();
12625        ++p)
12626     {
12627       if (*p != NULL)
12628         {
12629           if (Expression::traverse(&*p, traverse) == TRAVERSE_EXIT)
12630             return TRAVERSE_EXIT;
12631         }
12632     }
12633   return TRAVERSE_CONTINUE;
12634 }
12635
12636 // Copy the list.
12637
12638 Expression_list*
12639 Expression_list::copy()
12640 {
12641   Expression_list* ret = new Expression_list();
12642   for (Expression_list::iterator p = this->begin();
12643        p != this->end();
12644        ++p)
12645     {
12646       if (*p == NULL)
12647         ret->push_back(NULL);
12648       else
12649         ret->push_back((*p)->copy());
12650     }
12651   return ret;
12652 }
12653
12654 // Return whether an expression list has an error expression.
12655
12656 bool
12657 Expression_list::contains_error() const
12658 {
12659   for (Expression_list::const_iterator p = this->begin();
12660        p != this->end();
12661        ++p)
12662     if (*p != NULL && (*p)->is_error_expression())
12663       return true;
12664   return false;
12665 }