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   if (first_field_value == error_mark_node)
 366     return error_mark_node;
 367
 368   // Start building a constructor for the value we will return.
 369
 370   VEC(constructor_elt,gc)* init = VEC_alloc(constructor_elt, gc, 2);
 371
 372   constructor_elt* elt = VEC_quick_push(constructor_elt, init, NULL);
 373   tree field = TYPE_FIELDS(lhs_type_tree);
 374   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)),
 375                     (lhs_is_empty ? "__type_descriptor" : "__methods")) == 0);
 376   elt->index = field;
 377   elt->value = fold_convert_loc(location, TREE_TYPE(field), first_field_value);
 378
 379   elt = VEC_quick_push(constructor_elt, init, NULL);
 380   field = DECL_CHAIN(field);
 381   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__object") == 0);
 382   elt->index = field;
 383
 384   if (rhs_type->points_to() != NULL)
 385     {
 386       //  We are assigning a pointer to the interface; the interface
 387       // holds the pointer itself.
 388       elt->value = rhs_tree;
 389       return build_constructor(lhs_type_tree, init);
 390     }
 391
 392   // We are assigning a non-pointer value to the interface; the
 393   // interface gets a copy of the value in the heap.
 394
 395   tree object_size = TYPE_SIZE_UNIT(TREE_TYPE(rhs_tree));
 396
 397   tree space = gogo->allocate_memory(rhs_type, object_size, location);
 398   space = fold_convert_loc(location, build_pointer_type(TREE_TYPE(rhs_tree)),
 399                            space);
 400   space = save_expr(space);
 401
 402   tree ref = build_fold_indirect_ref_loc(location, space);
 403   TREE_THIS_NOTRAP(ref) = 1;
 404   tree set = fold_build2_loc(location, MODIFY_EXPR, void_type_node,
 405                              ref, rhs_tree);
 406
 407   elt->value = fold_convert_loc(location, TREE_TYPE(field), space);
 408
 409   return build2(COMPOUND_EXPR, lhs_type_tree, set,
 410                 build_constructor(lhs_type_tree, init));
 411 }
 412
 413 // Return a tree for the type descriptor of RHS_TREE, which has
 414 // interface type RHS_TYPE.  If RHS_TREE is nil the result will be
 415 // NULL.
 416
 417 tree
 418 Expression::get_interface_type_descriptor(Translate_context*,
 419                                           Type* rhs_type, tree rhs_tree,
 420                                           source_location location)
 421 {
 422   tree rhs_type_tree = TREE_TYPE(rhs_tree);
 423   gcc_assert(TREE_CODE(rhs_type_tree) == RECORD_TYPE);
 424   tree rhs_field = TYPE_FIELDS(rhs_type_tree);
 425   tree v = build3(COMPONENT_REF, TREE_TYPE(rhs_field), rhs_tree, rhs_field,
 426                   NULL_TREE);
 427   if (rhs_type->interface_type()->is_empty())
 428     {
 429       gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(rhs_field)),
 430                         "__type_descriptor") == 0);
 431       return v;
 432     }
 433
 434   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(rhs_field)), "__methods")
 435              == 0);
 436   gcc_assert(POINTER_TYPE_P(TREE_TYPE(v)));
 437   v = save_expr(v);
 438   tree v1 = build_fold_indirect_ref_loc(location, v);
 439   gcc_assert(TREE_CODE(TREE_TYPE(v1)) == RECORD_TYPE);
 440   tree f = TYPE_FIELDS(TREE_TYPE(v1));
 441   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(f)), "__type_descriptor")
 442              == 0);
 443   v1 = build3(COMPONENT_REF, TREE_TYPE(f), v1, f, NULL_TREE);
 444
 445   tree eq = fold_build2_loc(location, EQ_EXPR, boolean_type_node, v,
 446                             fold_convert_loc(location, TREE_TYPE(v),
 447                                              null_pointer_node));
 448   tree n = fold_convert_loc(location, TREE_TYPE(v1), null_pointer_node);
 449   return fold_build3_loc(location, COND_EXPR, TREE_TYPE(v1),
 450                          eq, n, v1);
 451 }
 452
 453 // Return a tree for the conversion of an interface type to an
 454 // interface type.
 455
 456 tree
 457 Expression::convert_interface_to_interface(Translate_context* context,
 458                                            Type *lhs_type, Type *rhs_type,
 459                                            tree rhs_tree, bool for_type_guard,
 460                                            source_location location)
 461 {
 462   Gogo* gogo = context->gogo();
 463   Interface_type* lhs_interface_type = lhs_type->interface_type();
 464   bool lhs_is_empty = lhs_interface_type->is_empty();
 465
 466   tree lhs_type_tree = lhs_type->get_tree(gogo);
 467   if (lhs_type_tree == error_mark_node)
 468     return error_mark_node;
 469
 470   // In the general case this requires runtime examination of the type
 471   // method table to match it up with the interface methods.
 472
 473   // FIXME: If all of the methods in the right hand side interface
 474   // also appear in the left hand side interface, then we don't need
 475   // to do a runtime check, although we still need to build a new
 476   // method table.
 477
 478   // Get the type descriptor for the right hand side.  This will be
 479   // NULL for a nil interface.
 480
 481   if (!DECL_P(rhs_tree))
 482     rhs_tree = save_expr(rhs_tree);
 483
 484   tree rhs_type_descriptor =
 485     Expression::get_interface_type_descriptor(context, rhs_type, rhs_tree,
 486                                               location);
 487
 488   // The result is going to be a two element constructor.
 489
 490   VEC(constructor_elt,gc)* init = VEC_alloc(constructor_elt, gc, 2);
 491
 492   constructor_elt* elt = VEC_quick_push(constructor_elt, init, NULL);
 493   tree field = TYPE_FIELDS(lhs_type_tree);
 494   elt->index = field;
 495
 496   if (for_type_guard)
 497     {
 498       // A type assertion fails when converting a nil interface.
 499       tree lhs_type_descriptor = lhs_type->type_descriptor_pointer(gogo);
 500       static tree assert_interface_decl;
 501       tree call = Gogo::call_builtin(&assert_interface_decl,
 502                                      location,
 503                                      "__go_assert_interface",
 504                                      2,
 505                                      ptr_type_node,
 506                                      TREE_TYPE(lhs_type_descriptor),
 507                                      lhs_type_descriptor,
 508                                      TREE_TYPE(rhs_type_descriptor),
 509                                      rhs_type_descriptor);
 510       if (call == error_mark_node)
 511         return error_mark_node;
 512       // This will panic if the interface conversion fails.
 513       TREE_NOTHROW(assert_interface_decl) = 0;
 514       elt->value = fold_convert_loc(location, TREE_TYPE(field), call);
 515     }
 516   else if (lhs_is_empty)
 517     {
 518       // A convertion to an empty interface always succeeds, and the
 519       // first field is just the type descriptor of the object.
 520       gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)),
 521                         "__type_descriptor") == 0);
 522       gcc_assert(TREE_TYPE(field) == TREE_TYPE(rhs_type_descriptor));
 523       elt->value = rhs_type_descriptor;
 524     }
 525   else
 526     {
 527       // A conversion to a non-empty interface may fail, but unlike a
 528       // type assertion converting nil will always succeed.
 529       gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__methods")
 530                  == 0);
 531       tree lhs_type_descriptor = lhs_type->type_descriptor_pointer(gogo);
 532       static tree convert_interface_decl;
 533       tree call = Gogo::call_builtin(&convert_interface_decl,
 534                                      location,
 535                                      "__go_convert_interface",
 536                                      2,
 537                                      ptr_type_node,
 538                                      TREE_TYPE(lhs_type_descriptor),
 539                                      lhs_type_descriptor,
 540                                      TREE_TYPE(rhs_type_descriptor),
 541                                      rhs_type_descriptor);
 542       if (call == error_mark_node)
 543         return error_mark_node;
 544       // This will panic if the interface conversion fails.
 545       TREE_NOTHROW(convert_interface_decl) = 0;
 546       elt->value = fold_convert_loc(location, TREE_TYPE(field), call);
 547     }
 548
 549   // The second field is simply the object pointer.
 550
 551   elt = VEC_quick_push(constructor_elt, init, NULL);
 552   field = DECL_CHAIN(field);
 553   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__object") == 0);
 554   elt->index = field;
 555
 556   tree rhs_type_tree = TREE_TYPE(rhs_tree);
 557   gcc_assert(TREE_CODE(rhs_type_tree) == RECORD_TYPE);
 558   tree rhs_field = DECL_CHAIN(TYPE_FIELDS(rhs_type_tree));
 559   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(rhs_field)), "__object") == 0);
 560   elt->value = build3(COMPONENT_REF, TREE_TYPE(rhs_field), rhs_tree, rhs_field,
 561                       NULL_TREE);
 562
 563   return build_constructor(lhs_type_tree, init);
 564 }
 565
 566 // Return a tree for the conversion of an interface type to a
 567 // non-interface type.
 568
 569 tree
 570 Expression::convert_interface_to_type(Translate_context* context,
 571                                       Type *lhs_type, Type* rhs_type,
 572                                       tree rhs_tree, source_location location)
 573 {
 574   Gogo* gogo = context->gogo();
 575   tree rhs_type_tree = TREE_TYPE(rhs_tree);
 576
 577   tree lhs_type_tree = lhs_type->get_tree(gogo);
 578   if (lhs_type_tree == error_mark_node)
 579     return error_mark_node;
 580
 581   // Call a function to check that the type is valid.  The function
 582   // will panic with an appropriate runtime type error if the type is
 583   // not valid.
 584
 585   tree lhs_type_descriptor = lhs_type->type_descriptor_pointer(gogo);
 586
 587   if (!DECL_P(rhs_tree))
 588     rhs_tree = save_expr(rhs_tree);
 589
 590   tree rhs_type_descriptor =
 591     Expression::get_interface_type_descriptor(context, rhs_type, rhs_tree,
 592                                               location);
 593
 594   tree rhs_inter_descriptor = rhs_type->type_descriptor_pointer(gogo);
 595
 596   static tree check_interface_type_decl;
 597   tree call = Gogo::call_builtin(&check_interface_type_decl,
 598                                  location,
 599                                  "__go_check_interface_type",
 600                                  3,
 601                                  void_type_node,
 602                                  TREE_TYPE(lhs_type_descriptor),
 603                                  lhs_type_descriptor,
 604                                  TREE_TYPE(rhs_type_descriptor),
 605                                  rhs_type_descriptor,
 606                                  TREE_TYPE(rhs_inter_descriptor),
 607                                  rhs_inter_descriptor);
 608   if (call == error_mark_node)
 609     return error_mark_node;
 610   // This call will panic if the conversion is invalid.
 611   TREE_NOTHROW(check_interface_type_decl) = 0;
 612
 613   // If the call succeeds, pull out the value.
 614   gcc_assert(TREE_CODE(rhs_type_tree) == RECORD_TYPE);
 615   tree rhs_field = DECL_CHAIN(TYPE_FIELDS(rhs_type_tree));
 616   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(rhs_field)), "__object") == 0);
 617   tree val = build3(COMPONENT_REF, TREE_TYPE(rhs_field), rhs_tree, rhs_field,
 618                     NULL_TREE);
 619
 620   // If the value is a pointer, then it is the value we want.
 621   // Otherwise it points to the value.
 622   if (lhs_type->points_to() == NULL)
 623     {
 624       val = fold_convert_loc(location, build_pointer_type(lhs_type_tree), val);
 625       val = build_fold_indirect_ref_loc(location, val);
 626     }
 627
 628   return build2(COMPOUND_EXPR, lhs_type_tree, call,
 629                 fold_convert_loc(location, lhs_type_tree, val));
 630 }
 631
 632 // Convert an expression to a tree.  This is implemented by the child
 633 // class.  Not that it is not in general safe to call this multiple
 634 // times for a single expression, but that we don't catch such errors.
 635
 636 tree
 637 Expression::get_tree(Translate_context* context)
 638 {
 639   // The child may have marked this expression as having an error.
 640   if (this->classification_ == EXPRESSION_ERROR)
 641     return error_mark_node;
 642
 643   return this->do_get_tree(context);
 644 }
 645
 646 // Return a tree for VAL in TYPE.
 647
 648 tree
 649 Expression::integer_constant_tree(mpz_t val, tree type)
 650 {
 651   if (type == error_mark_node)
 652     return error_mark_node;
 653   else if (TREE_CODE(type) == INTEGER_TYPE)
 654     return double_int_to_tree(type,
 655                               mpz_get_double_int(type, val, true));
 656   else if (TREE_CODE(type) == REAL_TYPE)
 657     {
 658       mpfr_t fval;
 659       mpfr_init_set_z(fval, val, GMP_RNDN);
 660       tree ret = Expression::float_constant_tree(fval, type);
 661       mpfr_clear(fval);
 662       return ret;
 663     }
 664   else if (TREE_CODE(type) == COMPLEX_TYPE)
 665     {
 666       mpfr_t fval;
 667       mpfr_init_set_z(fval, val, GMP_RNDN);
 668       tree real = Expression::float_constant_tree(fval, TREE_TYPE(type));
 669       mpfr_clear(fval);
 670       tree imag = build_real_from_int_cst(TREE_TYPE(type),
 671                                           integer_zero_node);
 672       return build_complex(type, real, imag);
 673     }
 674   else
 675     gcc_unreachable();
 676 }
 677
 678 // Return a tree for VAL in TYPE.
 679
 680 tree
 681 Expression::float_constant_tree(mpfr_t val, tree type)
 682 {
 683   if (type == error_mark_node)
 684     return error_mark_node;
 685   else if (TREE_CODE(type) == INTEGER_TYPE)
 686     {
 687       mpz_t ival;
 688       mpz_init(ival);
 689       mpfr_get_z(ival, val, GMP_RNDN);
 690       tree ret = Expression::integer_constant_tree(ival, type);
 691       mpz_clear(ival);
 692       return ret;
 693     }
 694   else if (TREE_CODE(type) == REAL_TYPE)
 695     {
 696       REAL_VALUE_TYPE r1;
 697       real_from_mpfr(&r1, val, type, GMP_RNDN);
 698       REAL_VALUE_TYPE r2;
 699       real_convert(&r2, TYPE_MODE(type), &r1);
 700       return build_real(type, r2);
 701     }
 702   else if (TREE_CODE(type) == COMPLEX_TYPE)
 703     {
 704       REAL_VALUE_TYPE r1;
 705       real_from_mpfr(&r1, val, TREE_TYPE(type), GMP_RNDN);
 706       REAL_VALUE_TYPE r2;
 707       real_convert(&r2, TYPE_MODE(TREE_TYPE(type)), &r1);
 708       tree imag = build_real_from_int_cst(TREE_TYPE(type),
 709                                           integer_zero_node);
 710       return build_complex(type, build_real(TREE_TYPE(type), r2), imag);
 711     }
 712   else
 713     gcc_unreachable();
 714 }
 715
 716 // Return a tree for REAL/IMAG in TYPE.
 717
 718 tree
 719 Expression::complex_constant_tree(mpfr_t real, mpfr_t imag, tree type)
 720 {
 721   if (type == error_mark_node)
 722     return error_mark_node;
 723   else if (TREE_CODE(type) == INTEGER_TYPE || TREE_CODE(type) == REAL_TYPE)
 724     return Expression::float_constant_tree(real, type);
 725   else if (TREE_CODE(type) == COMPLEX_TYPE)
 726     {
 727       REAL_VALUE_TYPE r1;
 728       real_from_mpfr(&r1, real, TREE_TYPE(type), GMP_RNDN);
 729       REAL_VALUE_TYPE r2;
 730       real_convert(&r2, TYPE_MODE(TREE_TYPE(type)), &r1);
 731
 732       REAL_VALUE_TYPE r3;
 733       real_from_mpfr(&r3, imag, TREE_TYPE(type), GMP_RNDN);
 734       REAL_VALUE_TYPE r4;
 735       real_convert(&r4, TYPE_MODE(TREE_TYPE(type)), &r3);
 736
 737       return build_complex(type, build_real(TREE_TYPE(type), r2),
 738                            build_real(TREE_TYPE(type), r4));
 739     }
 740   else
 741     gcc_unreachable();
 742 }
 743
 744 // Return a tree which evaluates to true if VAL, of arbitrary integer
 745 // type, is negative or is more than the maximum value of BOUND_TYPE.
 746 // If SOFAR is not NULL, it is or'red into the result.  The return
 747 // value may be NULL if SOFAR is NULL.
 748
 749 tree
 750 Expression::check_bounds(tree val, tree bound_type, tree sofar,
 751                          source_location loc)
 752 {
 753   tree val_type = TREE_TYPE(val);
 754   tree ret = NULL_TREE;
 755
 756   if (!TYPE_UNSIGNED(val_type))
 757     {
 758       ret = fold_build2_loc(loc, LT_EXPR, boolean_type_node, val,
 759                             build_int_cst(val_type, 0));
 760       if (ret == boolean_false_node)
 761         ret = NULL_TREE;
 762     }
 763
 764   if ((TYPE_UNSIGNED(val_type) && !TYPE_UNSIGNED(bound_type))
 765       || TYPE_SIZE(val_type) > TYPE_SIZE(bound_type))
 766     {
 767       tree max = TYPE_MAX_VALUE(bound_type);
 768       tree big = fold_build2_loc(loc, GT_EXPR, boolean_type_node, val,
 769                                  fold_convert_loc(loc, val_type, max));
 770       if (big == boolean_false_node)
 771         ;
 772       else if (ret == NULL_TREE)
 773         ret = big;
 774       else
 775         ret = fold_build2_loc(loc, TRUTH_OR_EXPR, boolean_type_node,
 776                               ret, big);
 777     }
 778
 779   if (ret == NULL_TREE)
 780     return sofar;
 781   else if (sofar == NULL_TREE)
 782     return ret;
 783   else
 784     return fold_build2_loc(loc, TRUTH_OR_EXPR, boolean_type_node,
 785                            sofar, ret);
 786 }
 787
 788 // Error expressions.  This are used to avoid cascading errors.
 789
 790 class Error_expression : public Expression
 791 {
 792  public:
 793   Error_expression(source_location location)
 794     : Expression(EXPRESSION_ERROR, location)
 795   { }
 796
 797  protected:
 798   bool
 799   do_is_constant() const
 800   { return true; }
 801
 802   bool
 803   do_integer_constant_value(bool, mpz_t val, Type**) const
 804   {
 805     mpz_set_ui(val, 0);
 806     return true;
 807   }
 808
 809   bool
 810   do_float_constant_value(mpfr_t val, Type**) const
 811   {
 812     mpfr_set_ui(val, 0, GMP_RNDN);
 813     return true;
 814   }
 815
 816   bool
 817   do_complex_constant_value(mpfr_t real, mpfr_t imag, Type**) const
 818   {
 819     mpfr_set_ui(real, 0, GMP_RNDN);
 820     mpfr_set_ui(imag, 0, GMP_RNDN);
 821     return true;
 822   }
 823
 824   void
 825   do_discarding_value()
 826   { }
 827
 828   Type*
 829   do_type()
 830   { return Type::make_error_type(); }
 831
 832   void
 833   do_determine_type(const Type_context*)
 834   { }
 835
 836   Expression*
 837   do_copy()
 838   { return this; }
 839
 840   bool
 841   do_is_addressable() const
 842   { return true; }
 843
 844   tree
 845   do_get_tree(Translate_context*)
 846   { return error_mark_node; }
 847 };
 848
 849 Expression*
 850 Expression::make_error(source_location location)
 851 {
 852   return new Error_expression(location);
 853 }
 854
 855 // An expression which is really a type.  This is used during parsing.
 856 // It is an error if these survive after lowering.
 857
 858 class
 859 Type_expression : public Expression
 860 {
 861  public:
 862   Type_expression(Type* type, source_location location)
 863     : Expression(EXPRESSION_TYPE, location),
 864       type_(type)
 865   { }
 866
 867  protected:
 868   int
 869   do_traverse(Traverse* traverse)
 870   { return Type::traverse(this->type_, traverse); }
 871
 872   Type*
 873   do_type()
 874   { return this->type_; }
 875
 876   void
 877   do_determine_type(const Type_context*)
 878   { }
 879
 880   void
 881   do_check_types(Gogo*)
 882   { this->report_error(_("invalid use of type")); }
 883
 884   Expression*
 885   do_copy()
 886   { return this; }
 887
 888   tree
 889   do_get_tree(Translate_context*)
 890   { gcc_unreachable(); }
 891
 892  private:
 893   // The type which we are representing as an expression.
 894   Type* type_;
 895 };
 896
 897 Expression*
 898 Expression::make_type(Type* type, source_location location)
 899 {
 900   return new Type_expression(type, location);
 901 }
 902
 903 // Class Parser_expression.
 904
 905 Type*
 906 Parser_expression::do_type()
 907 {
 908   // We should never really ask for the type of a Parser_expression.
 909   // However, it can happen, at least when we have an invalid const
 910   // whose initializer refers to the const itself.  In that case we
 911   // may ask for the type when lowering the const itself.
 912   gcc_assert(saw_errors());
 913   return Type::make_error_type();
 914 }
 915
 916 // Class Var_expression.
 917
 918 // Lower a variable expression.  Here we just make sure that the
 919 // initialization expression of the variable has been lowered.  This
 920 // ensures that we will be able to determine the type of the variable
 921 // if necessary.
 922
 923 Expression*
 924 Var_expression::do_lower(Gogo* gogo, Named_object* function, int)
 925 {
 926   if (this->variable_->is_variable())
 927     {
 928       Variable* var = this->variable_->var_value();
 929       // This is either a local variable or a global variable.  A
 930       // reference to a variable which is local to an enclosing
 931       // function will be a reference to a field in a closure.
 932       if (var->is_global())
 933         function = NULL;
 934       var->lower_init_expression(gogo, function);
 935     }
 936   return this;
 937 }
 938
 939 // Return the type of a reference to a variable.
 940
 941 Type*
 942 Var_expression::do_type()
 943 {
 944   if (this->variable_->is_variable())
 945     return this->variable_->var_value()->type();
 946   else if (this->variable_->is_result_variable())
 947     return this->variable_->result_var_value()->type();
 948   else
 949     gcc_unreachable();
 950 }
 951
 952 // Determine the type of a reference to a variable.
 953
 954 void
 955 Var_expression::do_determine_type(const Type_context*)
 956 {
 957   if (this->variable_->is_variable())
 958     this->variable_->var_value()->determine_type();
 959 }
 960
 961 // Something takes the address of this variable.  This means that we
 962 // may want to move the variable onto the heap.
 963
 964 void
 965 Var_expression::do_address_taken(bool escapes)
 966 {
 967   if (!escapes)
 968     ;
 969   else if (this->variable_->is_variable())
 970     this->variable_->var_value()->set_address_taken();
 971   else if (this->variable_->is_result_variable())
 972     this->variable_->result_var_value()->set_address_taken();
 973   else
 974     gcc_unreachable();
 975 }
 976
 977 // Get the tree for a reference to a variable.
 978
 979 tree
 980 Var_expression::do_get_tree(Translate_context* context)
 981 {
 982   return this->variable_->get_tree(context->gogo(), context->function());
 983 }
 984
 985 // Make a reference to a variable in an expression.
 986
 987 Expression*
 988 Expression::make_var_reference(Named_object* var, source_location location)
 989 {
 990   if (var->is_sink())
 991     return Expression::make_sink(location);
 992
 993   // FIXME: Creating a new object for each reference to a variable is
 994   // wasteful.
 995   return new Var_expression(var, location);
 996 }
 997
 998 // Class Temporary_reference_expression.
 999
1000 // The type.
1001
1002 Type*
1003 Temporary_reference_expression::do_type()
1004 {
1005   return this->statement_->type();
1006 }
1007
1008 // Called if something takes the address of this temporary variable.
1009 // We never have to move temporary variables to the heap, but we do
1010 // need to know that they must live in the stack rather than in a
1011 // register.
1012
1013 void
1014 Temporary_reference_expression::do_address_taken(bool)
1015 {
1016   this->statement_->set_is_address_taken();
1017 }
1018
1019 // Get a tree referring to the variable.
1020
1021 tree
1022 Temporary_reference_expression::do_get_tree(Translate_context*)
1023 {
1024   return this->statement_->get_decl();
1025 }
1026
1027 // Make a reference to a temporary variable.
1028
1029 Expression*
1030 Expression::make_temporary_reference(Temporary_statement* statement,
1031                                      source_location location)
1032 {
1033   return new Temporary_reference_expression(statement, location);
1034 }
1035
1036 // A sink expression--a use of the blank identifier _.
1037
1038 class Sink_expression : public Expression
1039 {
1040  public:
1041   Sink_expression(source_location location)
1042     : Expression(EXPRESSION_SINK, location),
1043       type_(NULL), var_(NULL_TREE)
1044   { }
1045
1046  protected:
1047   void
1048   do_discarding_value()
1049   { }
1050
1051   Type*
1052   do_type();
1053
1054   void
1055   do_determine_type(const Type_context*);
1056
1057   Expression*
1058   do_copy()
1059   { return new Sink_expression(this->location()); }
1060
1061   tree
1062   do_get_tree(Translate_context*);
1063
1064  private:
1065   // The type of this sink variable.
1066   Type* type_;
1067   // The temporary variable we generate.
1068   tree var_;
1069 };
1070
1071 // Return the type of a sink expression.
1072
1073 Type*
1074 Sink_expression::do_type()
1075 {
1076   if (this->type_ == NULL)
1077     return Type::make_sink_type();
1078   return this->type_;
1079 }
1080
1081 // Determine the type of a sink expression.
1082
1083 void
1084 Sink_expression::do_determine_type(const Type_context* context)
1085 {
1086   if (context->type != NULL)
1087     this->type_ = context->type;
1088 }
1089
1090 // Return a temporary variable for a sink expression.  This will
1091 // presumably be a write-only variable which the middle-end will drop.
1092
1093 tree
1094 Sink_expression::do_get_tree(Translate_context* context)
1095 {
1096   if (this->var_ == NULL_TREE)
1097     {
1098       gcc_assert(this->type_ != NULL && !this->type_->is_sink_type());
1099       this->var_ = create_tmp_var(this->type_->get_tree(context->gogo()),
1100                                   "blank");
1101     }
1102   return this->var_;
1103 }
1104
1105 // Make a sink expression.
1106
1107 Expression*
1108 Expression::make_sink(source_location location)
1109 {
1110   return new Sink_expression(location);
1111 }
1112
1113 // Class Func_expression.
1114
1115 // FIXME: Can a function expression appear in a constant expression?
1116 // The value is unchanging.  Initializing a constant to the address of
1117 // a function seems like it could work, though there might be little
1118 // point to it.
1119
1120 // Traversal.
1121
1122 int
1123 Func_expression::do_traverse(Traverse* traverse)
1124 {
1125   return (this->closure_ == NULL
1126           ? TRAVERSE_CONTINUE
1127           : Expression::traverse(&this->closure_, traverse));
1128 }
1129
1130 // Return the type of a function expression.
1131
1132 Type*
1133 Func_expression::do_type()
1134 {
1135   if (this->function_->is_function())
1136     return this->function_->func_value()->type();
1137   else if (this->function_->is_function_declaration())
1138     return this->function_->func_declaration_value()->type();
1139   else
1140     gcc_unreachable();
1141 }
1142
1143 // Get the tree for a function expression without evaluating the
1144 // closure.
1145
1146 tree
1147 Func_expression::get_tree_without_closure(Gogo* gogo)
1148 {
1149   Function_type* fntype;
1150   if (this->function_->is_function())
1151     fntype = this->function_->func_value()->type();
1152   else if (this->function_->is_function_declaration())
1153     fntype = this->function_->func_declaration_value()->type();
1154   else
1155     gcc_unreachable();
1156
1157   // Builtin functions are handled specially by Call_expression.  We
1158   // can't take their address.
1159   if (fntype->is_builtin())
1160     {
1161       error_at(this->location(), "invalid use of special builtin function %qs",
1162                this->function_->name().c_str());
1163       return error_mark_node;
1164     }
1165
1166   Named_object* no = this->function_;
1167
1168   tree id = no->get_id(gogo);
1169   if (id == error_mark_node)
1170     return error_mark_node;
1171
1172   tree fndecl;
1173   if (no->is_function())
1174     fndecl = no->func_value()->get_or_make_decl(gogo, no, id);
1175   else if (no->is_function_declaration())
1176     fndecl = no->func_declaration_value()->get_or_make_decl(gogo, no, id);
1177   else
1178     gcc_unreachable();
1179
1180   if (fndecl == error_mark_node)
1181     return error_mark_node;
1182
1183   return build_fold_addr_expr_loc(this->location(), fndecl);
1184 }
1185
1186 // Get the tree for a function expression.  This is used when we take
1187 // the address of a function rather than simply calling it.  If the
1188 // function has a closure, we must use a trampoline.
1189
1190 tree
1191 Func_expression::do_get_tree(Translate_context* context)
1192 {
1193   Gogo* gogo = context->gogo();
1194
1195   tree fnaddr = this->get_tree_without_closure(gogo);
1196   if (fnaddr == error_mark_node)
1197     return error_mark_node;
1198
1199   gcc_assert(TREE_CODE(fnaddr) == ADDR_EXPR
1200              && TREE_CODE(TREE_OPERAND(fnaddr, 0)) == FUNCTION_DECL);
1201   TREE_ADDRESSABLE(TREE_OPERAND(fnaddr, 0)) = 1;
1202
1203   // For a normal non-nested function call, that is all we have to do.
1204   if (!this->function_->is_function()
1205       || this->function_->func_value()->enclosing() == NULL)
1206     {
1207       gcc_assert(this->closure_ == NULL);
1208       return fnaddr;
1209     }
1210
1211   // For a nested function call, we have to always allocate a
1212   // trampoline.  If we don't always allocate, then closures will not
1213   // be reliably distinct.
1214   Expression* closure = this->closure_;
1215   tree closure_tree;
1216   if (closure == NULL)
1217     closure_tree = null_pointer_node;
1218   else
1219     {
1220       // Get the value of the closure.  This will be a pointer to
1221       // space allocated on the heap.
1222       closure_tree = closure->get_tree(context);
1223       if (closure_tree == error_mark_node)
1224         return error_mark_node;
1225       gcc_assert(POINTER_TYPE_P(TREE_TYPE(closure_tree)));
1226     }
1227
1228   // Now we need to build some code on the heap.  This code will load
1229   // the static chain pointer with the closure and then jump to the
1230   // body of the function.  The normal gcc approach is to build the
1231   // code on the stack.  Unfortunately we can not do that, as Go
1232   // permits us to return the function pointer.
1233
1234   return gogo->make_trampoline(fnaddr, closure_tree, this->location());
1235 }
1236
1237 // Make a reference to a function in an expression.
1238
1239 Expression*
1240 Expression::make_func_reference(Named_object* function, Expression* closure,
1241                                 source_location location)
1242 {
1243   return new Func_expression(function, closure, location);
1244 }
1245
1246 // Class Unknown_expression.
1247
1248 // Return the name of an unknown expression.
1249
1250 const std::string&
1251 Unknown_expression::name() const
1252 {
1253   return this->named_object_->name();
1254 }
1255
1256 // Lower a reference to an unknown name.
1257
1258 Expression*
1259 Unknown_expression::do_lower(Gogo*, Named_object*, int)
1260 {
1261   source_location location = this->location();
1262   Named_object* no = this->named_object_;
1263   Named_object* real;
1264   if (!no->is_unknown())
1265     real = no;
1266   else
1267     {
1268       real = no->unknown_value()->real_named_object();
1269       if (real == NULL)
1270         {
1271           if (this->is_composite_literal_key_)
1272             return this;
1273           error_at(location, "reference to undefined name %qs",
1274                    this->named_object_->message_name().c_str());
1275           return Expression::make_error(location);
1276         }
1277     }
1278   switch (real->classification())
1279     {
1280     case Named_object::NAMED_OBJECT_CONST:
1281       return Expression::make_const_reference(real, location);
1282     case Named_object::NAMED_OBJECT_TYPE:
1283       return Expression::make_type(real->type_value(), location);
1284     case Named_object::NAMED_OBJECT_TYPE_DECLARATION:
1285       if (this->is_composite_literal_key_)
1286         return this;
1287       error_at(location, "reference to undefined type %qs",
1288                real->message_name().c_str());
1289       return Expression::make_error(location);
1290     case Named_object::NAMED_OBJECT_VAR:
1291       return Expression::make_var_reference(real, location);
1292     case Named_object::NAMED_OBJECT_FUNC:
1293     case Named_object::NAMED_OBJECT_FUNC_DECLARATION:
1294       return Expression::make_func_reference(real, NULL, location);
1295     case Named_object::NAMED_OBJECT_PACKAGE:
1296       if (this->is_composite_literal_key_)
1297         return this;
1298       error_at(location, "unexpected reference to package");
1299       return Expression::make_error(location);
1300     default:
1301       gcc_unreachable();
1302     }
1303 }
1304
1305 // Make a reference to an unknown name.
1306
1307 Expression*
1308 Expression::make_unknown_reference(Named_object* no, source_location location)
1309 {
1310   gcc_assert(no->resolve()->is_unknown());
1311   return new Unknown_expression(no, location);
1312 }
1313
1314 // A boolean expression.
1315
1316 class Boolean_expression : public Expression
1317 {
1318  public:
1319   Boolean_expression(bool val, source_location location)
1320     : Expression(EXPRESSION_BOOLEAN, location),
1321       val_(val), type_(NULL)
1322   { }
1323
1324   static Expression*
1325   do_import(Import*);
1326
1327  protected:
1328   bool
1329   do_is_constant() const
1330   { return true; }
1331
1332   Type*
1333   do_type();
1334
1335   void
1336   do_determine_type(const Type_context*);
1337
1338   Expression*
1339   do_copy()
1340   { return this; }
1341
1342   tree
1343   do_get_tree(Translate_context*)
1344   { return this->val_ ? boolean_true_node : boolean_false_node; }
1345
1346   void
1347   do_export(Export* exp) const
1348   { exp->write_c_string(this->val_ ? "true" : "false"); }
1349
1350  private:
1351   // The constant.
1352   bool val_;
1353   // The type as determined by context.
1354   Type* type_;
1355 };
1356
1357 // Get the type.
1358
1359 Type*
1360 Boolean_expression::do_type()
1361 {
1362   if (this->type_ == NULL)
1363     this->type_ = Type::make_boolean_type();
1364   return this->type_;
1365 }
1366
1367 // Set the type from the context.
1368
1369 void
1370 Boolean_expression::do_determine_type(const Type_context* context)
1371 {
1372   if (this->type_ != NULL && !this->type_->is_abstract())
1373     ;
1374   else if (context->type != NULL && context->type->is_boolean_type())
1375     this->type_ = context->type;
1376   else if (!context->may_be_abstract)
1377     this->type_ = Type::lookup_bool_type();
1378 }
1379
1380 // Import a boolean constant.
1381
1382 Expression*
1383 Boolean_expression::do_import(Import* imp)
1384 {
1385   if (imp->peek_char() == 't')
1386     {
1387       imp->require_c_string("true");
1388       return Expression::make_boolean(true, imp->location());
1389     }
1390   else
1391     {
1392       imp->require_c_string("false");
1393       return Expression::make_boolean(false, imp->location());
1394     }
1395 }
1396
1397 // Make a boolean expression.
1398
1399 Expression*
1400 Expression::make_boolean(bool val, source_location location)
1401 {
1402   return new Boolean_expression(val, location);
1403 }
1404
1405 // Class String_expression.
1406
1407 // Get the type.
1408
1409 Type*
1410 String_expression::do_type()
1411 {
1412   if (this->type_ == NULL)
1413     this->type_ = Type::make_string_type();
1414   return this->type_;
1415 }
1416
1417 // Set the type from the context.
1418
1419 void
1420 String_expression::do_determine_type(const Type_context* context)
1421 {
1422   if (this->type_ != NULL && !this->type_->is_abstract())
1423     ;
1424   else if (context->type != NULL && context->type->is_string_type())
1425     this->type_ = context->type;
1426   else if (!context->may_be_abstract)
1427     this->type_ = Type::lookup_string_type();
1428 }
1429
1430 // Build a string constant.
1431
1432 tree
1433 String_expression::do_get_tree(Translate_context* context)
1434 {
1435   return context->gogo()->go_string_constant_tree(this->val_);
1436 }
1437
1438 // Export a string expression.
1439
1440 void
1441 String_expression::do_export(Export* exp) const
1442 {
1443   std::string s;
1444   s.reserve(this->val_.length() * 4 + 2);
1445   s += '"';
1446   for (std::string::const_iterator p = this->val_.begin();
1447        p != this->val_.end();
1448        ++p)
1449     {
1450       if (*p == '\\' || *p == '"')
1451         {
1452           s += '\\';
1453           s += *p;
1454         }
1455       else if (*p >= 0x20 && *p < 0x7f)
1456         s += *p;
1457       else if (*p == '\n')
1458         s += "\\n";
1459       else if (*p == '\t')
1460         s += "\\t";
1461       else
1462         {
1463           s += "\\x";
1464           unsigned char c = *p;
1465           unsigned int dig = c >> 4;
1466           s += dig < 10 ? '0' + dig : 'A' + dig - 10;
1467           dig = c & 0xf;
1468           s += dig < 10 ? '0' + dig : 'A' + dig - 10;
1469         }
1470     }
1471   s += '"';
1472   exp->write_string(s);
1473 }
1474
1475 // Import a string expression.
1476
1477 Expression*
1478 String_expression::do_import(Import* imp)
1479 {
1480   imp->require_c_string("\"");
1481   std::string val;
1482   while (true)
1483     {
1484       int c = imp->get_char();
1485       if (c == '"' || c == -1)
1486         break;
1487       if (c != '\\')
1488         val += static_cast<char>(c);
1489       else
1490         {
1491           c = imp->get_char();
1492           if (c == '\\' || c == '"')
1493             val += static_cast<char>(c);
1494           else if (c == 'n')
1495             val += '\n';
1496           else if (c == 't')
1497             val += '\t';
1498           else if (c == 'x')
1499             {
1500               c = imp->get_char();
1501               unsigned int vh = c >= '0' && c <= '9' ? c - '0' : c - 'A' + 10;
1502               c = imp->get_char();
1503               unsigned int vl = c >= '0' && c <= '9' ? c - '0' : c - 'A' + 10;
1504               char v = (vh << 4) | vl;
1505               val += v;
1506             }
1507           else
1508             {
1509               error_at(imp->location(), "bad string constant");
1510               return Expression::make_error(imp->location());
1511             }
1512         }
1513     }
1514   return Expression::make_string(val, imp->location());
1515 }
1516
1517 // Make a string expression.
1518
1519 Expression*
1520 Expression::make_string(const std::string& val, source_location location)
1521 {
1522   return new String_expression(val, location);
1523 }
1524
1525 // Make an integer expression.
1526
1527 class Integer_expression : public Expression
1528 {
1529  public:
1530   Integer_expression(const mpz_t* val, Type* type, source_location location)
1531     : Expression(EXPRESSION_INTEGER, location),
1532       type_(type)
1533   { mpz_init_set(this->val_, *val); }
1534
1535   static Expression*
1536   do_import(Import*);
1537
1538   // Return whether VAL fits in the type.
1539   static bool
1540   check_constant(mpz_t val, Type*, source_location);
1541
1542   // Write VAL to export data.
1543   static void
1544   export_integer(Export* exp, const mpz_t val);
1545
1546  protected:
1547   bool
1548   do_is_constant() const
1549   { return true; }
1550
1551   bool
1552   do_integer_constant_value(bool, mpz_t val, Type** ptype) const;
1553
1554   Type*
1555   do_type();
1556
1557   void
1558   do_determine_type(const Type_context* context);
1559
1560   void
1561   do_check_types(Gogo*);
1562
1563   tree
1564   do_get_tree(Translate_context*);
1565
1566   Expression*
1567   do_copy()
1568   { return Expression::make_integer(&this->val_, this->type_,
1569                                     this->location()); }
1570
1571   void
1572   do_export(Export*) const;
1573
1574  private:
1575   // The integer value.
1576   mpz_t val_;
1577   // The type so far.
1578   Type* type_;
1579 };
1580
1581 // Return an integer constant value.
1582
1583 bool
1584 Integer_expression::do_integer_constant_value(bool, mpz_t val,
1585                                               Type** ptype) const
1586 {
1587   if (this->type_ != NULL)
1588     *ptype = this->type_;
1589   mpz_set(val, this->val_);
1590   return true;
1591 }
1592
1593 // Return the current type.  If we haven't set the type yet, we return
1594 // an abstract integer type.
1595
1596 Type*
1597 Integer_expression::do_type()
1598 {
1599   if (this->type_ == NULL)
1600     this->type_ = Type::make_abstract_integer_type();
1601   return this->type_;
1602 }
1603
1604 // Set the type of the integer value.  Here we may switch from an
1605 // abstract type to a real type.
1606
1607 void
1608 Integer_expression::do_determine_type(const Type_context* context)
1609 {
1610   if (this->type_ != NULL && !this->type_->is_abstract())
1611     ;
1612   else if (context->type != NULL
1613            && (context->type->integer_type() != NULL
1614                || context->type->float_type() != NULL
1615                || context->type->complex_type() != NULL))
1616     this->type_ = context->type;
1617   else if (!context->may_be_abstract)
1618     this->type_ = Type::lookup_integer_type("int");
1619 }
1620
1621 // Return true if the integer VAL fits in the range of the type TYPE.
1622 // Otherwise give an error and return false.  TYPE may be NULL.
1623
1624 bool
1625 Integer_expression::check_constant(mpz_t val, Type* type,
1626                                    source_location location)
1627 {
1628   if (type == NULL)
1629     return true;
1630   Integer_type* itype = type->integer_type();
1631   if (itype == NULL || itype->is_abstract())
1632     return true;
1633
1634   int bits = mpz_sizeinbase(val, 2);
1635
1636   if (itype->is_unsigned())
1637     {
1638       // For an unsigned type we can only accept a nonnegative number,
1639       // and we must be able to represent at least BITS.
1640       if (mpz_sgn(val) >= 0
1641           && bits <= itype->bits())
1642         return true;
1643     }
1644   else
1645     {
1646       // For a signed type we need an extra bit to indicate the sign.
1647       // We have to handle the most negative integer specially.
1648       if (bits + 1 <= itype->bits()
1649           || (bits <= itype->bits()
1650               && mpz_sgn(val) < 0
1651               && (mpz_scan1(val, 0)
1652                   == static_cast<unsigned long>(itype->bits() - 1))
1653               && mpz_scan0(val, itype->bits()) == ULONG_MAX))
1654         return true;
1655     }
1656
1657   error_at(location, "integer constant overflow");
1658   return false;
1659 }
1660
1661 // Check the type of an integer constant.
1662
1663 void
1664 Integer_expression::do_check_types(Gogo*)
1665 {
1666   if (this->type_ == NULL)
1667     return;
1668   if (!Integer_expression::check_constant(this->val_, this->type_,
1669                                           this->location()))
1670     this->set_is_error();
1671 }
1672
1673 // Get a tree for an integer constant.
1674
1675 tree
1676 Integer_expression::do_get_tree(Translate_context* context)
1677 {
1678   Gogo* gogo = context->gogo();
1679   tree type;
1680   if (this->type_ != NULL && !this->type_->is_abstract())
1681     type = this->type_->get_tree(gogo);
1682   else if (this->type_ != NULL && this->type_->float_type() != NULL)
1683     {
1684       // We are converting to an abstract floating point type.
1685       type = Type::lookup_float_type("float64")->get_tree(gogo);
1686     }
1687   else if (this->type_ != NULL && this->type_->complex_type() != NULL)
1688     {
1689       // We are converting to an abstract complex type.
1690       type = Type::lookup_complex_type("complex128")->get_tree(gogo);
1691     }
1692   else
1693     {
1694       // If we still have an abstract type here, then this is being
1695       // used in a constant expression which didn't get reduced for
1696       // some reason.  Use a type which will fit the value.  We use <,
1697       // not <=, because we need an extra bit for the sign bit.
1698       int bits = mpz_sizeinbase(this->val_, 2);
1699       if (bits < INT_TYPE_SIZE)
1700         type = Type::lookup_integer_type("int")->get_tree(gogo);
1701       else if (bits < 64)
1702         type = Type::lookup_integer_type("int64")->get_tree(gogo);
1703       else
1704         type = long_long_integer_type_node;
1705     }
1706   return Expression::integer_constant_tree(this->val_, type);
1707 }
1708
1709 // Write VAL to export data.
1710
1711 void
1712 Integer_expression::export_integer(Export* exp, const mpz_t val)
1713 {
1714   char* s = mpz_get_str(NULL, 10, val);
1715   exp->write_c_string(s);
1716   free(s);
1717 }
1718
1719 // Export an integer in a constant expression.
1720
1721 void
1722 Integer_expression::do_export(Export* exp) const
1723 {
1724   Integer_expression::export_integer(exp, this->val_);
1725   // A trailing space lets us reliably identify the end of the number.
1726   exp->write_c_string(" ");
1727 }
1728
1729 // Import an integer, floating point, or complex value.  This handles
1730 // all these types because they all start with digits.
1731
1732 Expression*
1733 Integer_expression::do_import(Import* imp)
1734 {
1735   std::string num = imp->read_identifier();
1736   imp->require_c_string(" ");
1737   if (!num.empty() && num[num.length() - 1] == 'i')
1738     {
1739       mpfr_t real;
1740       size_t plus_pos = num.find('+', 1);
1741       size_t minus_pos = num.find('-', 1);
1742       size_t pos;
1743       if (plus_pos == std::string::npos)
1744         pos = minus_pos;
1745       else if (minus_pos == std::string::npos)
1746         pos = plus_pos;
1747       else
1748         {
1749           error_at(imp->location(), "bad number in import data: %qs",
1750                    num.c_str());
1751           return Expression::make_error(imp->location());
1752         }
1753       if (pos == std::string::npos)
1754         mpfr_set_ui(real, 0, GMP_RNDN);
1755       else
1756         {
1757           std::string real_str = num.substr(0, pos);
1758           if (mpfr_init_set_str(real, real_str.c_str(), 10, GMP_RNDN) != 0)
1759             {
1760               error_at(imp->location(), "bad number in import data: %qs",
1761                        real_str.c_str());
1762               return Expression::make_error(imp->location());
1763             }
1764         }
1765
1766       std::string imag_str;
1767       if (pos == std::string::npos)
1768         imag_str = num;
1769       else
1770         imag_str = num.substr(pos);
1771       imag_str = imag_str.substr(0, imag_str.size() - 1);
1772       mpfr_t imag;
1773       if (mpfr_init_set_str(imag, imag_str.c_str(), 10, GMP_RNDN) != 0)
1774         {
1775           error_at(imp->location(), "bad number in import data: %qs",
1776                    imag_str.c_str());
1777           return Expression::make_error(imp->location());
1778         }
1779       Expression* ret = Expression::make_complex(&real, &imag, NULL,
1780                                                  imp->location());
1781       mpfr_clear(real);
1782       mpfr_clear(imag);
1783       return ret;
1784     }
1785   else if (num.find('.') == std::string::npos
1786            && num.find('E') == std::string::npos)
1787     {
1788       mpz_t val;
1789       if (mpz_init_set_str(val, num.c_str(), 10) != 0)
1790         {
1791           error_at(imp->location(), "bad number in import data: %qs",
1792                    num.c_str());
1793           return Expression::make_error(imp->location());
1794         }
1795       Expression* ret = Expression::make_integer(&val, NULL, imp->location());
1796       mpz_clear(val);
1797       return ret;
1798     }
1799   else
1800     {
1801       mpfr_t val;
1802       if (mpfr_init_set_str(val, num.c_str(), 10, GMP_RNDN) != 0)
1803         {
1804           error_at(imp->location(), "bad number in import data: %qs",
1805                    num.c_str());
1806           return Expression::make_error(imp->location());
1807         }
1808       Expression* ret = Expression::make_float(&val, NULL, imp->location());
1809       mpfr_clear(val);
1810       return ret;
1811     }
1812 }
1813
1814 // Build a new integer value.
1815
1816 Expression*
1817 Expression::make_integer(const mpz_t* val, Type* type,
1818                          source_location location)
1819 {
1820   return new Integer_expression(val, type, location);
1821 }
1822
1823 // Floats.
1824
1825 class Float_expression : public Expression
1826 {
1827  public:
1828   Float_expression(const mpfr_t* val, Type* type, source_location location)
1829     : Expression(EXPRESSION_FLOAT, location),
1830       type_(type)
1831   {
1832     mpfr_init_set(this->val_, *val, GMP_RNDN);
1833   }
1834
1835   // Constrain VAL to fit into TYPE.
1836   static void
1837   constrain_float(mpfr_t val, Type* type);
1838
1839   // Return whether VAL fits in the type.
1840   static bool
1841   check_constant(mpfr_t val, Type*, source_location);
1842
1843   // Write VAL to export data.
1844   static void
1845   export_float(Export* exp, const mpfr_t val);
1846
1847  protected:
1848   bool
1849   do_is_constant() const
1850   { return true; }
1851
1852   bool
1853   do_float_constant_value(mpfr_t val, Type**) const;
1854
1855   Type*
1856   do_type();
1857
1858   void
1859   do_determine_type(const Type_context*);
1860
1861   void
1862   do_check_types(Gogo*);
1863
1864   Expression*
1865   do_copy()
1866   { return Expression::make_float(&this->val_, this->type_,
1867                                   this->location()); }
1868
1869   tree
1870   do_get_tree(Translate_context*);
1871
1872   void
1873   do_export(Export*) const;
1874
1875  private:
1876   // The floating point value.
1877   mpfr_t val_;
1878   // The type so far.
1879   Type* type_;
1880 };
1881
1882 // Constrain VAL to fit into TYPE.
1883
1884 void
1885 Float_expression::constrain_float(mpfr_t val, Type* type)
1886 {
1887   Float_type* ftype = type->float_type();
1888   if (ftype != NULL && !ftype->is_abstract())
1889     {
1890       tree type_tree = ftype->type_tree();
1891       REAL_VALUE_TYPE rvt;
1892       real_from_mpfr(&rvt, val, type_tree, GMP_RNDN);
1893       real_convert(&rvt, TYPE_MODE(type_tree), &rvt);
1894       mpfr_from_real(val, &rvt, GMP_RNDN);
1895     }
1896 }
1897
1898 // Return a floating point constant value.
1899
1900 bool
1901 Float_expression::do_float_constant_value(mpfr_t val, Type** ptype) const
1902 {
1903   if (this->type_ != NULL)
1904     *ptype = this->type_;
1905   mpfr_set(val, this->val_, GMP_RNDN);
1906   return true;
1907 }
1908
1909 // Return the current type.  If we haven't set the type yet, we return
1910 // an abstract float type.
1911
1912 Type*
1913 Float_expression::do_type()
1914 {
1915   if (this->type_ == NULL)
1916     this->type_ = Type::make_abstract_float_type();
1917   return this->type_;
1918 }
1919
1920 // Set the type of the float value.  Here we may switch from an
1921 // abstract type to a real type.
1922
1923 void
1924 Float_expression::do_determine_type(const Type_context* context)
1925 {
1926   if (this->type_ != NULL && !this->type_->is_abstract())
1927     ;
1928   else if (context->type != NULL
1929            && (context->type->integer_type() != NULL
1930                || context->type->float_type() != NULL
1931                || context->type->complex_type() != NULL))
1932     this->type_ = context->type;
1933   else if (!context->may_be_abstract)
1934     this->type_ = Type::lookup_float_type("float64");
1935 }
1936
1937 // Return true if the floating point value VAL fits in the range of
1938 // the type TYPE.  Otherwise give an error and return false.  TYPE may
1939 // be NULL.
1940
1941 bool
1942 Float_expression::check_constant(mpfr_t val, Type* type,
1943                                  source_location location)
1944 {
1945   if (type == NULL)
1946     return true;
1947   Float_type* ftype = type->float_type();
1948   if (ftype == NULL || ftype->is_abstract())
1949     return true;
1950
1951   // A NaN or Infinity always fits in the range of the type.
1952   if (mpfr_nan_p(val) || mpfr_inf_p(val) || mpfr_zero_p(val))
1953     return true;
1954
1955   mp_exp_t exp = mpfr_get_exp(val);
1956   mp_exp_t max_exp;
1957   switch (ftype->bits())
1958     {
1959     case 32:
1960       max_exp = 128;
1961       break;
1962     case 64:
1963       max_exp = 1024;
1964       break;
1965     default:
1966       gcc_unreachable();
1967     }
1968   if (exp > max_exp)
1969     {
1970       error_at(location, "floating point constant overflow");
1971       return false;
1972     }
1973   return true;
1974 }
1975
1976 // Check the type of a float value.
1977
1978 void
1979 Float_expression::do_check_types(Gogo*)
1980 {
1981   if (this->type_ == NULL)
1982     return;
1983
1984   if (!Float_expression::check_constant(this->val_, this->type_,
1985                                         this->location()))
1986     this->set_is_error();
1987
1988   Integer_type* integer_type = this->type_->integer_type();
1989   if (integer_type != NULL)
1990     {
1991       if (!mpfr_integer_p(this->val_))
1992         this->report_error(_("floating point constant truncated to integer"));
1993       else
1994         {
1995           gcc_assert(!integer_type->is_abstract());
1996           mpz_t ival;
1997           mpz_init(ival);
1998           mpfr_get_z(ival, this->val_, GMP_RNDN);
1999           Integer_expression::check_constant(ival, integer_type,
2000                                              this->location());
2001           mpz_clear(ival);
2002         }
2003     }
2004 }
2005
2006 // Get a tree for a float constant.
2007
2008 tree
2009 Float_expression::do_get_tree(Translate_context* context)
2010 {
2011   Gogo* gogo = context->gogo();
2012   tree type;
2013   if (this->type_ != NULL && !this->type_->is_abstract())
2014     type = this->type_->get_tree(gogo);
2015   else if (this->type_ != NULL && this->type_->integer_type() != NULL)
2016     {
2017       // We have an abstract integer type.  We just hope for the best.
2018       type = Type::lookup_integer_type("int")->get_tree(gogo);
2019     }
2020   else
2021     {
2022       // If we still have an abstract type here, then this is being
2023       // used in a constant expression which didn't get reduced.  We
2024       // just use float64 and hope for the best.
2025       type = Type::lookup_float_type("float64")->get_tree(gogo);
2026     }
2027   return Expression::float_constant_tree(this->val_, type);
2028 }
2029
2030 // Write a floating point number to export data.
2031
2032 void
2033 Float_expression::export_float(Export *exp, const mpfr_t val)
2034 {
2035   mp_exp_t exponent;
2036   char* s = mpfr_get_str(NULL, &exponent, 10, 0, val, GMP_RNDN);
2037   if (*s == '-')
2038     exp->write_c_string("-");
2039   exp->write_c_string("0.");
2040   exp->write_c_string(*s == '-' ? s + 1 : s);
2041   mpfr_free_str(s);
2042   char buf[30];
2043   snprintf(buf, sizeof buf, "E%ld", exponent);
2044   exp->write_c_string(buf);
2045 }
2046
2047 // Export a floating point number in a constant expression.
2048
2049 void
2050 Float_expression::do_export(Export* exp) const
2051 {
2052   Float_expression::export_float(exp, this->val_);
2053   // A trailing space lets us reliably identify the end of the number.
2054   exp->write_c_string(" ");
2055 }
2056
2057 // Make a float expression.
2058
2059 Expression*
2060 Expression::make_float(const mpfr_t* val, Type* type, source_location location)
2061 {
2062   return new Float_expression(val, type, location);
2063 }
2064
2065 // Complex numbers.
2066
2067 class Complex_expression : public Expression
2068 {
2069  public:
2070   Complex_expression(const mpfr_t* real, const mpfr_t* imag, Type* type,
2071                      source_location location)
2072     : Expression(EXPRESSION_COMPLEX, location),
2073       type_(type)
2074   {
2075     mpfr_init_set(this->real_, *real, GMP_RNDN);
2076     mpfr_init_set(this->imag_, *imag, GMP_RNDN);
2077   }
2078
2079   // Constrain REAL/IMAG to fit into TYPE.
2080   static void
2081   constrain_complex(mpfr_t real, mpfr_t imag, Type* type);
2082
2083   // Return whether REAL/IMAG fits in the type.
2084   static bool
2085   check_constant(mpfr_t real, mpfr_t imag, Type*, source_location);
2086
2087   // Write REAL/IMAG to export data.
2088   static void
2089   export_complex(Export* exp, const mpfr_t real, const mpfr_t val);
2090
2091  protected:
2092   bool
2093   do_is_constant() const
2094   { return true; }
2095
2096   bool
2097   do_complex_constant_value(mpfr_t real, mpfr_t imag, Type**) const;
2098
2099   Type*
2100   do_type();
2101
2102   void
2103   do_determine_type(const Type_context*);
2104
2105   void
2106   do_check_types(Gogo*);
2107
2108   Expression*
2109   do_copy()
2110   {
2111     return Expression::make_complex(&this->real_, &this->imag_, this->type_,
2112                                     this->location());
2113   }
2114
2115   tree
2116   do_get_tree(Translate_context*);
2117
2118   void
2119   do_export(Export*) const;
2120
2121  private:
2122   // The real part.
2123   mpfr_t real_;
2124   // The imaginary part;
2125   mpfr_t imag_;
2126   // The type if known.
2127   Type* type_;
2128 };
2129
2130 // Constrain REAL/IMAG to fit into TYPE.
2131
2132 void
2133 Complex_expression::constrain_complex(mpfr_t real, mpfr_t imag, Type* type)
2134 {
2135   Complex_type* ctype = type->complex_type();
2136   if (ctype != NULL && !ctype->is_abstract())
2137     {
2138       tree type_tree = ctype->type_tree();
2139
2140       REAL_VALUE_TYPE rvt;
2141       real_from_mpfr(&rvt, real, TREE_TYPE(type_tree), GMP_RNDN);
2142       real_convert(&rvt, TYPE_MODE(TREE_TYPE(type_tree)), &rvt);
2143       mpfr_from_real(real, &rvt, GMP_RNDN);
2144
2145       real_from_mpfr(&rvt, imag, TREE_TYPE(type_tree), GMP_RNDN);
2146       real_convert(&rvt, TYPE_MODE(TREE_TYPE(type_tree)), &rvt);
2147       mpfr_from_real(imag, &rvt, GMP_RNDN);
2148     }
2149 }
2150
2151 // Return a complex constant value.
2152
2153 bool
2154 Complex_expression::do_complex_constant_value(mpfr_t real, mpfr_t imag,
2155                                               Type** ptype) const
2156 {
2157   if (this->type_ != NULL)
2158     *ptype = this->type_;
2159   mpfr_set(real, this->real_, GMP_RNDN);
2160   mpfr_set(imag, this->imag_, GMP_RNDN);
2161   return true;
2162 }
2163
2164 // Return the current type.  If we haven't set the type yet, we return
2165 // an abstract complex type.
2166
2167 Type*
2168 Complex_expression::do_type()
2169 {
2170   if (this->type_ == NULL)
2171     this->type_ = Type::make_abstract_complex_type();
2172   return this->type_;
2173 }
2174
2175 // Set the type of the complex value.  Here we may switch from an
2176 // abstract type to a real type.
2177
2178 void
2179 Complex_expression::do_determine_type(const Type_context* context)
2180 {
2181   if (this->type_ != NULL && !this->type_->is_abstract())
2182     ;
2183   else if (context->type != NULL
2184            && context->type->complex_type() != NULL)
2185     this->type_ = context->type;
2186   else if (!context->may_be_abstract)
2187     this->type_ = Type::lookup_complex_type("complex128");
2188 }
2189
2190 // Return true if the complex value REAL/IMAG fits in the range of the
2191 // type TYPE.  Otherwise give an error and return false.  TYPE may be
2192 // NULL.
2193
2194 bool
2195 Complex_expression::check_constant(mpfr_t real, mpfr_t imag, Type* type,
2196                                    source_location location)
2197 {
2198   if (type == NULL)
2199     return true;
2200   Complex_type* ctype = type->complex_type();
2201   if (ctype == NULL || ctype->is_abstract())
2202     return true;
2203
2204   mp_exp_t max_exp;
2205   switch (ctype->bits())
2206     {
2207     case 64:
2208       max_exp = 128;
2209       break;
2210     case 128:
2211       max_exp = 1024;
2212       break;
2213     default:
2214       gcc_unreachable();
2215     }
2216
2217   // A NaN or Infinity always fits in the range of the type.
2218   if (!mpfr_nan_p(real) && !mpfr_inf_p(real) && !mpfr_zero_p(real))
2219     {
2220       if (mpfr_get_exp(real) > max_exp)
2221         {
2222           error_at(location, "complex real part constant overflow");
2223           return false;
2224         }
2225     }
2226
2227   if (!mpfr_nan_p(imag) && !mpfr_inf_p(imag) && !mpfr_zero_p(imag))
2228     {
2229       if (mpfr_get_exp(imag) > max_exp)
2230         {
2231           error_at(location, "complex imaginary part constant overflow");
2232           return false;
2233         }
2234     }
2235
2236   return true;
2237 }
2238
2239 // Check the type of a complex value.
2240
2241 void
2242 Complex_expression::do_check_types(Gogo*)
2243 {
2244   if (this->type_ == NULL)
2245     return;
2246
2247   if (!Complex_expression::check_constant(this->real_, this->imag_,
2248                                           this->type_, this->location()))
2249     this->set_is_error();
2250 }
2251
2252 // Get a tree for a complex constant.
2253
2254 tree
2255 Complex_expression::do_get_tree(Translate_context* context)
2256 {
2257   Gogo* gogo = context->gogo();
2258   tree type;
2259   if (this->type_ != NULL && !this->type_->is_abstract())
2260     type = this->type_->get_tree(gogo);
2261   else
2262     {
2263       // If we still have an abstract type here, this this is being
2264       // used in a constant expression which didn't get reduced.  We
2265       // just use complex128 and hope for the best.
2266       type = Type::lookup_complex_type("complex128")->get_tree(gogo);
2267     }
2268   return Expression::complex_constant_tree(this->real_, this->imag_, type);
2269 }
2270
2271 // Write REAL/IMAG to export data.
2272
2273 void
2274 Complex_expression::export_complex(Export* exp, const mpfr_t real,
2275                                    const mpfr_t imag)
2276 {
2277   if (!mpfr_zero_p(real))
2278     {
2279       Float_expression::export_float(exp, real);
2280       if (mpfr_sgn(imag) > 0)
2281         exp->write_c_string("+");
2282     }
2283   Float_expression::export_float(exp, imag);
2284   exp->write_c_string("i");
2285 }
2286
2287 // Export a complex number in a constant expression.
2288
2289 void
2290 Complex_expression::do_export(Export* exp) const
2291 {
2292   Complex_expression::export_complex(exp, this->real_, this->imag_);
2293   // A trailing space lets us reliably identify the end of the number.
2294   exp->write_c_string(" ");
2295 }
2296
2297 // Make a complex expression.
2298
2299 Expression*
2300 Expression::make_complex(const mpfr_t* real, const mpfr_t* imag, Type* type,
2301                          source_location location)
2302 {
2303   return new Complex_expression(real, imag, type, location);
2304 }
2305
2306 // Find a named object in an expression.
2307
2308 class Find_named_object : public Traverse
2309 {
2310  public:
2311   Find_named_object(Named_object* no)
2312     : Traverse(traverse_expressions),
2313       no_(no), found_(false)
2314   { }
2315
2316   // Whether we found the object.
2317   bool
2318   found() const
2319   { return this->found_; }
2320
2321  protected:
2322   int
2323   expression(Expression**);
2324
2325  private:
2326   // The object we are looking for.
2327   Named_object* no_;
2328   // Whether we found it.
2329   bool found_;
2330 };
2331
2332 // A reference to a const in an expression.
2333
2334 class Const_expression : public Expression
2335 {
2336  public:
2337   Const_expression(Named_object* constant, source_location location)
2338     : Expression(EXPRESSION_CONST_REFERENCE, location),
2339       constant_(constant), type_(NULL), seen_(false)
2340   { }
2341
2342   Named_object*
2343   named_object()
2344   { return this->constant_; }
2345
2346   // Check that the initializer does not refer to the constant itself.
2347   void
2348   check_for_init_loop();
2349
2350  protected:
2351   int
2352   do_traverse(Traverse*);
2353
2354   Expression*
2355   do_lower(Gogo*, Named_object*, int);
2356
2357   bool
2358   do_is_constant() const
2359   { return true; }
2360
2361   bool
2362   do_integer_constant_value(bool, mpz_t val, Type**) const;
2363
2364   bool
2365   do_float_constant_value(mpfr_t val, Type**) const;
2366
2367   bool
2368   do_complex_constant_value(mpfr_t real, mpfr_t imag, Type**) const;
2369
2370   bool
2371   do_string_constant_value(std::string* val) const
2372   { return this->constant_->const_value()->expr()->string_constant_value(val); }
2373
2374   Type*
2375   do_type();
2376
2377   // The type of a const is set by the declaration, not the use.
2378   void
2379   do_determine_type(const Type_context*);
2380
2381   void
2382   do_check_types(Gogo*);
2383
2384   Expression*
2385   do_copy()
2386   { return this; }
2387
2388   tree
2389   do_get_tree(Translate_context* context);
2390
2391   // When exporting a reference to a const as part of a const
2392   // expression, we export the value.  We ignore the fact that it has
2393   // a name.
2394   void
2395   do_export(Export* exp) const
2396   { this->constant_->const_value()->expr()->export_expression(exp); }
2397
2398  private:
2399   // The constant.
2400   Named_object* constant_;
2401   // The type of this reference.  This is used if the constant has an
2402   // abstract type.
2403   Type* type_;
2404   // Used to prevent infinite recursion when a constant incorrectly
2405   // refers to itself.
2406   mutable bool seen_;
2407 };
2408
2409 // Traversal.
2410
2411 int
2412 Const_expression::do_traverse(Traverse* traverse)
2413 {
2414   if (this->type_ != NULL)
2415     return Type::traverse(this->type_, traverse);
2416   return TRAVERSE_CONTINUE;
2417 }
2418
2419 // Lower a constant expression.  This is where we convert the
2420 // predeclared constant iota into an integer value.
2421
2422 Expression*
2423 Const_expression::do_lower(Gogo* gogo, Named_object*, int iota_value)
2424 {
2425   if (this->constant_->const_value()->expr()->classification()
2426       == EXPRESSION_IOTA)
2427     {
2428       if (iota_value == -1)
2429         {
2430           error_at(this->location(),
2431                    "iota is only defined in const declarations");
2432           iota_value = 0;
2433         }
2434       mpz_t val;
2435       mpz_init_set_ui(val, static_cast<unsigned long>(iota_value));
2436       Expression* ret = Expression::make_integer(&val, NULL,
2437                                                  this->location());
2438       mpz_clear(val);
2439       return ret;
2440     }
2441
2442   // Make sure that the constant itself has been lowered.
2443   gogo->lower_constant(this->constant_);
2444
2445   return this;
2446 }
2447
2448 // Return an integer constant value.
2449
2450 bool
2451 Const_expression::do_integer_constant_value(bool iota_is_constant, mpz_t val,
2452                                             Type** ptype) const
2453 {
2454   if (this->seen_)
2455     return false;
2456
2457   Type* ctype;
2458   if (this->type_ != NULL)
2459     ctype = this->type_;
2460   else
2461     ctype = this->constant_->const_value()->type();
2462   if (ctype != NULL && ctype->integer_type() == NULL)
2463     return false;
2464
2465   Expression* e = this->constant_->const_value()->expr();
2466
2467   this->seen_ = true;
2468
2469   Type* t;
2470   bool r = e->integer_constant_value(iota_is_constant, val, &t);
2471
2472   this->seen_ = false;
2473
2474   if (r
2475       && ctype != NULL
2476       && !Integer_expression::check_constant(val, ctype, this->location()))
2477     return false;
2478
2479   *ptype = ctype != NULL ? ctype : t;
2480   return r;
2481 }
2482
2483 // Return a floating point constant value.
2484
2485 bool
2486 Const_expression::do_float_constant_value(mpfr_t val, Type** ptype) const
2487 {
2488   if (this->seen_)
2489     return false;
2490
2491   Type* ctype;
2492   if (this->type_ != NULL)
2493     ctype = this->type_;
2494   else
2495     ctype = this->constant_->const_value()->type();
2496   if (ctype != NULL && ctype->float_type() == NULL)
2497     return false;
2498
2499   this->seen_ = true;
2500
2501   Type* t;
2502   bool r = this->constant_->const_value()->expr()->float_constant_value(val,
2503                                                                         &t);
2504
2505   this->seen_ = false;
2506
2507   if (r && ctype != NULL)
2508     {
2509       if (!Float_expression::check_constant(val, ctype, this->location()))
2510         return false;
2511       Float_expression::constrain_float(val, ctype);
2512     }
2513   *ptype = ctype != NULL ? ctype : t;
2514   return r;
2515 }
2516
2517 // Return a complex constant value.
2518
2519 bool
2520 Const_expression::do_complex_constant_value(mpfr_t real, mpfr_t imag,
2521                                             Type **ptype) const
2522 {
2523   if (this->seen_)
2524     return false;
2525
2526   Type* ctype;
2527   if (this->type_ != NULL)
2528     ctype = this->type_;
2529   else
2530     ctype = this->constant_->const_value()->type();
2531   if (ctype != NULL && ctype->complex_type() == NULL)
2532     return false;
2533
2534   this->seen_ = true;
2535
2536   Type *t;
2537   bool r = this->constant_->const_value()->expr()->complex_constant_value(real,
2538                                                                           imag,
2539                                                                           &t);
2540
2541   this->seen_ = false;
2542
2543   if (r && ctype != NULL)
2544     {
2545       if (!Complex_expression::check_constant(real, imag, ctype,
2546                                               this->location()))
2547         return false;
2548       Complex_expression::constrain_complex(real, imag, ctype);
2549     }
2550   *ptype = ctype != NULL ? ctype : t;
2551   return r;
2552 }
2553
2554 // Return the type of the const reference.
2555
2556 Type*
2557 Const_expression::do_type()
2558 {
2559   if (this->type_ != NULL)
2560     return this->type_;
2561
2562   Named_constant* nc = this->constant_->const_value();
2563
2564   if (this->seen_ || nc->lowering())
2565     {
2566       this->report_error(_("constant refers to itself"));
2567       this->type_ = Type::make_error_type();
2568       return this->type_;
2569     }
2570
2571   this->seen_ = true;
2572
2573   Type* ret = nc->type();
2574
2575   if (ret != NULL)
2576     {
2577       this->seen_ = false;
2578       return ret;
2579     }
2580
2581   // During parsing, a named constant may have a NULL type, but we
2582   // must not return a NULL type here.
2583   ret = nc->expr()->type();
2584
2585   this->seen_ = false;
2586
2587   return ret;
2588 }
2589
2590 // Set the type of the const reference.
2591
2592 void
2593 Const_expression::do_determine_type(const Type_context* context)
2594 {
2595   Type* ctype = this->constant_->const_value()->type();
2596   Type* cetype = (ctype != NULL
2597                   ? ctype
2598                   : this->constant_->const_value()->expr()->type());
2599   if (ctype != NULL && !ctype->is_abstract())
2600     ;
2601   else if (context->type != NULL
2602            && (context->type->integer_type() != NULL
2603                || context->type->float_type() != NULL
2604                || context->type->complex_type() != NULL)
2605            && (cetype->integer_type() != NULL
2606                || cetype->float_type() != NULL
2607                || cetype->complex_type() != NULL))
2608     this->type_ = context->type;
2609   else if (context->type != NULL
2610            && context->type->is_string_type()
2611            && cetype->is_string_type())
2612     this->type_ = context->type;
2613   else if (context->type != NULL
2614            && context->type->is_boolean_type()
2615            && cetype->is_boolean_type())
2616     this->type_ = context->type;
2617   else if (!context->may_be_abstract)
2618     {
2619       if (cetype->is_abstract())
2620         cetype = cetype->make_non_abstract_type();
2621       this->type_ = cetype;
2622     }
2623 }
2624
2625 // Check for a loop in which the initializer of a constant refers to
2626 // the constant itself.
2627
2628 void
2629 Const_expression::check_for_init_loop()
2630 {
2631   if (this->type_ != NULL && this->type_->is_error_type())
2632     return;
2633
2634   if (this->seen_)
2635     {
2636       this->report_error(_("constant refers to itself"));
2637       this->type_ = Type::make_error_type();
2638       return;
2639     }
2640
2641   Expression* init = this->constant_->const_value()->expr();
2642   Find_named_object find_named_object(this->constant_);
2643
2644   this->seen_ = true;
2645   Expression::traverse(&init, &find_named_object);
2646   this->seen_ = false;
2647
2648   if (find_named_object.found())
2649     {
2650       if (this->type_ == NULL || !this->type_->is_error_type())
2651         {
2652           this->report_error(_("constant refers to itself"));
2653           this->type_ = Type::make_error_type();
2654         }
2655       return;
2656     }
2657 }
2658
2659 // Check types of a const reference.
2660
2661 void
2662 Const_expression::do_check_types(Gogo*)
2663 {
2664   if (this->type_ != NULL && this->type_->is_error_type())
2665     return;
2666
2667   this->check_for_init_loop();
2668
2669   if (this->type_ == NULL || this->type_->is_abstract())
2670     return;
2671
2672   // Check for integer overflow.
2673   if (this->type_->integer_type() != NULL)
2674     {
2675       mpz_t ival;
2676       mpz_init(ival);
2677       Type* dummy;
2678       if (!this->integer_constant_value(true, ival, &dummy))
2679         {
2680           mpfr_t fval;
2681           mpfr_init(fval);
2682           Expression* cexpr = this->constant_->const_value()->expr();
2683           if (cexpr->float_constant_value(fval, &dummy))
2684             {
2685               if (!mpfr_integer_p(fval))
2686                 this->report_error(_("floating point constant "
2687                                      "truncated to integer"));
2688               else
2689                 {
2690                   mpfr_get_z(ival, fval, GMP_RNDN);
2691                   Integer_expression::check_constant(ival, this->type_,
2692                                                      this->location());
2693                 }
2694             }
2695           mpfr_clear(fval);
2696         }
2697       mpz_clear(ival);
2698     }
2699 }
2700
2701 // Return a tree for the const reference.
2702
2703 tree
2704 Const_expression::do_get_tree(Translate_context* context)
2705 {
2706   Gogo* gogo = context->gogo();
2707   tree type_tree;
2708   if (this->type_ == NULL)
2709     type_tree = NULL_TREE;
2710   else
2711     {
2712       type_tree = this->type_->get_tree(gogo);
2713       if (type_tree == error_mark_node)
2714         return error_mark_node;
2715     }
2716
2717   // If the type has been set for this expression, but the underlying
2718   // object is an abstract int or float, we try to get the abstract
2719   // value.  Otherwise we may lose something in the conversion.
2720   if (this->type_ != NULL
2721       && (this->constant_->const_value()->type() == NULL
2722           || this->constant_->const_value()->type()->is_abstract()))
2723     {
2724       Expression* expr = this->constant_->const_value()->expr();
2725       mpz_t ival;
2726       mpz_init(ival);
2727       Type* t;
2728       if (expr->integer_constant_value(true, ival, &t))
2729         {
2730           tree ret = Expression::integer_constant_tree(ival, type_tree);
2731           mpz_clear(ival);
2732           return ret;
2733         }
2734       mpz_clear(ival);
2735
2736       mpfr_t fval;
2737       mpfr_init(fval);
2738       if (expr->float_constant_value(fval, &t))
2739         {
2740           tree ret = Expression::float_constant_tree(fval, type_tree);
2741           mpfr_clear(fval);
2742           return ret;
2743         }
2744
2745       mpfr_t imag;
2746       mpfr_init(imag);
2747       if (expr->complex_constant_value(fval, imag, &t))
2748         {
2749           tree ret = Expression::complex_constant_tree(fval, imag, type_tree);
2750           mpfr_clear(fval);
2751           mpfr_clear(imag);
2752           return ret;
2753         }
2754       mpfr_clear(imag);
2755       mpfr_clear(fval);
2756     }
2757
2758   tree const_tree = this->constant_->get_tree(gogo, context->function());
2759   if (this->type_ == NULL
2760       || const_tree == error_mark_node
2761       || TREE_TYPE(const_tree) == error_mark_node)
2762     return const_tree;
2763
2764   tree ret;
2765   if (TYPE_MAIN_VARIANT(type_tree) == TYPE_MAIN_VARIANT(TREE_TYPE(const_tree)))
2766     ret = fold_convert(type_tree, const_tree);
2767   else if (TREE_CODE(type_tree) == INTEGER_TYPE)
2768     ret = fold(convert_to_integer(type_tree, const_tree));
2769   else if (TREE_CODE(type_tree) == REAL_TYPE)
2770     ret = fold(convert_to_real(type_tree, const_tree));
2771   else if (TREE_CODE(type_tree) == COMPLEX_TYPE)
2772     ret = fold(convert_to_complex(type_tree, const_tree));
2773   else
2774     gcc_unreachable();
2775   return ret;
2776 }
2777
2778 // Make a reference to a constant in an expression.
2779
2780 Expression*
2781 Expression::make_const_reference(Named_object* constant,
2782                                  source_location location)
2783 {
2784   return new Const_expression(constant, location);
2785 }
2786
2787 // Find a named object in an expression.
2788
2789 int
2790 Find_named_object::expression(Expression** pexpr)
2791 {
2792   switch ((*pexpr)->classification())
2793     {
2794     case Expression::EXPRESSION_CONST_REFERENCE:
2795       {
2796         Const_expression* ce = static_cast<Const_expression*>(*pexpr);
2797         if (ce->named_object() == this->no_)
2798           break;
2799
2800         // We need to check a constant initializer explicitly, as
2801         // loops here will not be caught by the loop checking for
2802         // variable initializers.
2803         ce->check_for_init_loop();
2804
2805         return TRAVERSE_CONTINUE;
2806       }
2807
2808     case Expression::EXPRESSION_VAR_REFERENCE:
2809       if ((*pexpr)->var_expression()->named_object() == this->no_)
2810         break;
2811       return TRAVERSE_CONTINUE;
2812     case Expression::EXPRESSION_FUNC_REFERENCE:
2813       if ((*pexpr)->func_expression()->named_object() == this->no_)
2814         break;
2815       return TRAVERSE_CONTINUE;
2816     default:
2817       return TRAVERSE_CONTINUE;
2818     }
2819   this->found_ = true;
2820   return TRAVERSE_EXIT;
2821 }
2822
2823 // The nil value.
2824
2825 class Nil_expression : public Expression
2826 {
2827  public:
2828   Nil_expression(source_location location)
2829     : Expression(EXPRESSION_NIL, location)
2830   { }
2831
2832   static Expression*
2833   do_import(Import*);
2834
2835  protected:
2836   bool
2837   do_is_constant() const
2838   { return true; }
2839
2840   Type*
2841   do_type()
2842   { return Type::make_nil_type(); }
2843
2844   void
2845   do_determine_type(const Type_context*)
2846   { }
2847
2848   Expression*
2849   do_copy()
2850   { return this; }
2851
2852   tree
2853   do_get_tree(Translate_context*)
2854   { return null_pointer_node; }
2855
2856   void
2857   do_export(Export* exp) const
2858   { exp->write_c_string("nil"); }
2859 };
2860
2861 // Import a nil expression.
2862
2863 Expression*
2864 Nil_expression::do_import(Import* imp)
2865 {
2866   imp->require_c_string("nil");
2867   return Expression::make_nil(imp->location());
2868 }
2869
2870 // Make a nil expression.
2871
2872 Expression*
2873 Expression::make_nil(source_location location)
2874 {
2875   return new Nil_expression(location);
2876 }
2877
2878 // The value of the predeclared constant iota.  This is little more
2879 // than a marker.  This will be lowered to an integer in
2880 // Const_expression::do_lower, which is where we know the value that
2881 // it should have.
2882
2883 class Iota_expression : public Parser_expression
2884 {
2885  public:
2886   Iota_expression(source_location location)
2887     : Parser_expression(EXPRESSION_IOTA, location)
2888   { }
2889
2890  protected:
2891   Expression*
2892   do_lower(Gogo*, Named_object*, int)
2893   { gcc_unreachable(); }
2894
2895   // There should only ever be one of these.
2896   Expression*
2897   do_copy()
2898   { gcc_unreachable(); }
2899 };
2900
2901 // Make an iota expression.  This is only called for one case: the
2902 // value of the predeclared constant iota.
2903
2904 Expression*
2905 Expression::make_iota()
2906 {
2907   static Iota_expression iota_expression(UNKNOWN_LOCATION);
2908   return &iota_expression;
2909 }
2910
2911 // A type conversion expression.
2912
2913 class Type_conversion_expression : public Expression
2914 {
2915  public:
2916   Type_conversion_expression(Type* type, Expression* expr,
2917                              source_location location)
2918     : Expression(EXPRESSION_CONVERSION, location),
2919       type_(type), expr_(expr), may_convert_function_types_(false)
2920   { }
2921
2922   // Return the type to which we are converting.
2923   Type*
2924   type() const
2925   { return this->type_; }
2926
2927   // Return the expression which we are converting.
2928   Expression*
2929   expr() const
2930   { return this->expr_; }
2931
2932   // Permit converting from one function type to another.  This is
2933   // used internally for method expressions.
2934   void
2935   set_may_convert_function_types()
2936   {
2937     this->may_convert_function_types_ = true;
2938   }
2939
2940   // Import a type conversion expression.
2941   static Expression*
2942   do_import(Import*);
2943
2944  protected:
2945   int
2946   do_traverse(Traverse* traverse);
2947
2948   Expression*
2949   do_lower(Gogo*, Named_object*, int);
2950
2951   bool
2952   do_is_constant() const
2953   { return this->expr_->is_constant(); }
2954
2955   bool
2956   do_integer_constant_value(bool, mpz_t, Type**) const;
2957
2958   bool
2959   do_float_constant_value(mpfr_t, Type**) const;
2960
2961   bool
2962   do_complex_constant_value(mpfr_t, mpfr_t, Type**) const;
2963
2964   bool
2965   do_string_constant_value(std::string*) const;
2966
2967   Type*
2968   do_type()
2969   { return this->type_; }
2970
2971   void
2972   do_determine_type(const Type_context*)
2973   {
2974     Type_context subcontext(this->type_, false);
2975     this->expr_->determine_type(&subcontext);
2976   }
2977
2978   void
2979   do_check_types(Gogo*);
2980
2981   Expression*
2982   do_copy()
2983   {
2984     return new Type_conversion_expression(this->type_, this->expr_->copy(),
2985                                           this->location());
2986   }
2987
2988   tree
2989   do_get_tree(Translate_context* context);
2990
2991   void
2992   do_export(Export*) const;
2993
2994  private:
2995   // The type to convert to.
2996   Type* type_;
2997   // The expression to convert.
2998   Expression* expr_;
2999   // True if this is permitted to convert function types.  This is
3000   // used internally for method expressions.
3001   bool may_convert_function_types_;
3002 };
3003
3004 // Traversal.
3005
3006 int
3007 Type_conversion_expression::do_traverse(Traverse* traverse)
3008 {
3009   if (Expression::traverse(&this->expr_, traverse) == TRAVERSE_EXIT
3010       || Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
3011     return TRAVERSE_EXIT;
3012   return TRAVERSE_CONTINUE;
3013 }
3014
3015 // Convert to a constant at lowering time.
3016
3017 Expression*
3018 Type_conversion_expression::do_lower(Gogo*, Named_object*, int)
3019 {
3020   Type* type = this->type_;
3021   Expression* val = this->expr_;
3022   source_location location = this->location();
3023
3024   if (type->integer_type() != NULL)
3025     {
3026       mpz_t ival;
3027       mpz_init(ival);
3028       Type* dummy;
3029       if (val->integer_constant_value(false, ival, &dummy))
3030         {
3031           if (!Integer_expression::check_constant(ival, type, location))
3032             mpz_set_ui(ival, 0);
3033           Expression* ret = Expression::make_integer(&ival, type, location);
3034           mpz_clear(ival);
3035           return ret;
3036         }
3037
3038       mpfr_t fval;
3039       mpfr_init(fval);
3040       if (val->float_constant_value(fval, &dummy))
3041         {
3042           if (!mpfr_integer_p(fval))
3043             {
3044               error_at(location,
3045                        "floating point constant truncated to integer");
3046               return Expression::make_error(location);
3047             }
3048           mpfr_get_z(ival, fval, GMP_RNDN);
3049           if (!Integer_expression::check_constant(ival, type, location))
3050             mpz_set_ui(ival, 0);
3051           Expression* ret = Expression::make_integer(&ival, type, location);
3052           mpfr_clear(fval);
3053           mpz_clear(ival);
3054           return ret;
3055         }
3056       mpfr_clear(fval);
3057       mpz_clear(ival);
3058     }
3059
3060   if (type->float_type() != NULL)
3061     {
3062       mpfr_t fval;
3063       mpfr_init(fval);
3064       Type* dummy;
3065       if (val->float_constant_value(fval, &dummy))
3066         {
3067           if (!Float_expression::check_constant(fval, type, location))
3068             mpfr_set_ui(fval, 0, GMP_RNDN);
3069           Float_expression::constrain_float(fval, type);
3070           Expression *ret = Expression::make_float(&fval, type, location);
3071           mpfr_clear(fval);
3072           return ret;
3073         }
3074       mpfr_clear(fval);
3075     }
3076
3077   if (type->complex_type() != NULL)
3078     {
3079       mpfr_t real;
3080       mpfr_t imag;
3081       mpfr_init(real);
3082       mpfr_init(imag);
3083       Type* dummy;
3084       if (val->complex_constant_value(real, imag, &dummy))
3085         {
3086           if (!Complex_expression::check_constant(real, imag, type, location))
3087             {
3088               mpfr_set_ui(real, 0, GMP_RNDN);
3089               mpfr_set_ui(imag, 0, GMP_RNDN);
3090             }
3091           Complex_expression::constrain_complex(real, imag, type);
3092           Expression* ret = Expression::make_complex(&real, &imag, type,
3093                                                      location);
3094           mpfr_clear(real);
3095           mpfr_clear(imag);
3096           return ret;
3097         }
3098       mpfr_clear(real);
3099       mpfr_clear(imag);
3100     }
3101
3102   if (type->is_open_array_type() && type->named_type() == NULL)
3103     {
3104       Type* element_type = type->array_type()->element_type()->forwarded();
3105       bool is_byte = element_type == Type::lookup_integer_type("uint8");
3106       bool is_int = element_type == Type::lookup_integer_type("int");
3107       if (is_byte || is_int)
3108         {
3109           std::string s;
3110           if (val->string_constant_value(&s))
3111             {
3112               Expression_list* vals = new Expression_list();
3113               if (is_byte)
3114                 {
3115                   for (std::string::const_iterator p = s.begin();
3116                        p != s.end();
3117                        p++)
3118                     {
3119                       mpz_t val;
3120                       mpz_init_set_ui(val, static_cast<unsigned char>(*p));
3121                       Expression* v = Expression::make_integer(&val,
3122                                                                element_type,
3123                                                                location);
3124                       vals->push_back(v);
3125                       mpz_clear(val);
3126                     }
3127                 }
3128               else
3129                 {
3130                   const char *p = s.data();
3131                   const char *pend = s.data() + s.length();
3132                   while (p < pend)
3133                     {
3134                       unsigned int c;
3135                       int adv = Lex::fetch_char(p, &c);
3136                       if (adv == 0)
3137                         {
3138                           warning_at(this->location(), 0,
3139                                      "invalid UTF-8 encoding");
3140                           adv = 1;
3141                         }
3142                       p += adv;
3143                       mpz_t val;
3144                       mpz_init_set_ui(val, c);
3145                       Expression* v = Expression::make_integer(&val,
3146                                                                element_type,
3147                                                                location);
3148                       vals->push_back(v);
3149                       mpz_clear(val);
3150                     }
3151                 }
3152
3153               return Expression::make_slice_composite_literal(type, vals,
3154                                                               location);
3155             }
3156         }
3157     }
3158
3159   return this;
3160 }
3161
3162 // Return the constant integer value if there is one.
3163
3164 bool
3165 Type_conversion_expression::do_integer_constant_value(bool iota_is_constant,
3166                                                       mpz_t val,
3167                                                       Type** ptype) const
3168 {
3169   if (this->type_->integer_type() == NULL)
3170     return false;
3171
3172   mpz_t ival;
3173   mpz_init(ival);
3174   Type* dummy;
3175   if (this->expr_->integer_constant_value(iota_is_constant, ival, &dummy))
3176     {
3177       if (!Integer_expression::check_constant(ival, this->type_,
3178                                               this->location()))
3179         {
3180           mpz_clear(ival);
3181           return false;
3182         }
3183       mpz_set(val, ival);
3184       mpz_clear(ival);
3185       *ptype = this->type_;
3186       return true;
3187     }
3188   mpz_clear(ival);
3189
3190   mpfr_t fval;
3191   mpfr_init(fval);
3192   if (this->expr_->float_constant_value(fval, &dummy))
3193     {
3194       mpfr_get_z(val, fval, GMP_RNDN);
3195       mpfr_clear(fval);
3196       if (!Integer_expression::check_constant(val, this->type_,
3197                                               this->location()))
3198         return false;
3199       *ptype = this->type_;
3200       return true;
3201     }
3202   mpfr_clear(fval);
3203
3204   return false;
3205 }
3206
3207 // Return the constant floating point value if there is one.
3208
3209 bool
3210 Type_conversion_expression::do_float_constant_value(mpfr_t val,
3211                                                     Type** ptype) const
3212 {
3213   if (this->type_->float_type() == NULL)
3214     return false;
3215
3216   mpfr_t fval;
3217   mpfr_init(fval);
3218   Type* dummy;
3219   if (this->expr_->float_constant_value(fval, &dummy))
3220     {
3221       if (!Float_expression::check_constant(fval, this->type_,
3222                                             this->location()))
3223         {
3224           mpfr_clear(fval);
3225           return false;
3226         }
3227       mpfr_set(val, fval, GMP_RNDN);
3228       mpfr_clear(fval);
3229       Float_expression::constrain_float(val, this->type_);
3230       *ptype = this->type_;
3231       return true;
3232     }
3233   mpfr_clear(fval);
3234
3235   return false;
3236 }
3237
3238 // Return the constant complex value if there is one.
3239
3240 bool
3241 Type_conversion_expression::do_complex_constant_value(mpfr_t real,
3242                                                       mpfr_t imag,
3243                                                       Type **ptype) const
3244 {
3245   if (this->type_->complex_type() == NULL)
3246     return false;
3247
3248   mpfr_t rval;
3249   mpfr_t ival;
3250   mpfr_init(rval);
3251   mpfr_init(ival);
3252   Type* dummy;
3253   if (this->expr_->complex_constant_value(rval, ival, &dummy))
3254     {
3255       if (!Complex_expression::check_constant(rval, ival, this->type_,
3256                                               this->location()))
3257         {
3258           mpfr_clear(rval);
3259           mpfr_clear(ival);
3260           return false;
3261         }
3262       mpfr_set(real, rval, GMP_RNDN);
3263       mpfr_set(imag, ival, GMP_RNDN);
3264       mpfr_clear(rval);
3265       mpfr_clear(ival);
3266       Complex_expression::constrain_complex(real, imag, this->type_);
3267       *ptype = this->type_;
3268       return true;
3269     }
3270   mpfr_clear(rval);
3271   mpfr_clear(ival);
3272
3273   return false;
3274 }
3275
3276 // Return the constant string value if there is one.
3277
3278 bool
3279 Type_conversion_expression::do_string_constant_value(std::string* val) const
3280 {
3281   if (this->type_->is_string_type()
3282       && this->expr_->type()->integer_type() != NULL)
3283     {
3284       mpz_t ival;
3285       mpz_init(ival);
3286       Type* dummy;
3287       if (this->expr_->integer_constant_value(false, ival, &dummy))
3288         {
3289           unsigned long ulval = mpz_get_ui(ival);
3290           if (mpz_cmp_ui(ival, ulval) == 0)
3291             {
3292               Lex::append_char(ulval, true, val, this->location());
3293               mpz_clear(ival);
3294               return true;
3295             }
3296         }
3297       mpz_clear(ival);
3298     }
3299
3300   // FIXME: Could handle conversion from const []int here.
3301
3302   return false;
3303 }
3304
3305 // Check that types are convertible.
3306
3307 void
3308 Type_conversion_expression::do_check_types(Gogo*)
3309 {
3310   Type* type = this->type_;
3311   Type* expr_type = this->expr_->type();
3312   std::string reason;
3313
3314   if (type->is_error_type()
3315       || type->is_undefined()
3316       || expr_type->is_error_type()
3317       || expr_type->is_undefined())
3318     {
3319       // Make sure we emit an error for an undefined type.
3320       type->base();
3321       expr_type->base();
3322       this->set_is_error();
3323       return;
3324     }
3325
3326   if (this->may_convert_function_types_
3327       && type->function_type() != NULL
3328       && expr_type->function_type() != NULL)
3329     return;
3330
3331   if (Type::are_convertible(type, expr_type, &reason))
3332     return;
3333
3334   error_at(this->location(), "%s", reason.c_str());
3335   this->set_is_error();
3336 }
3337
3338 // Get a tree for a type conversion.
3339
3340 tree
3341 Type_conversion_expression::do_get_tree(Translate_context* context)
3342 {
3343   Gogo* gogo = context->gogo();
3344   tree type_tree = this->type_->get_tree(gogo);
3345   tree expr_tree = this->expr_->get_tree(context);
3346
3347   if (type_tree == error_mark_node
3348       || expr_tree == error_mark_node
3349       || TREE_TYPE(expr_tree) == error_mark_node)
3350     return error_mark_node;
3351
3352   if (TYPE_MAIN_VARIANT(type_tree) == TYPE_MAIN_VARIANT(TREE_TYPE(expr_tree)))
3353     return fold_convert(type_tree, expr_tree);
3354
3355   Type* type = this->type_;
3356   Type* expr_type = this->expr_->type();
3357   tree ret;
3358   if (type->interface_type() != NULL || expr_type->interface_type() != NULL)
3359     ret = Expression::convert_for_assignment(context, type, expr_type,
3360                                              expr_tree, this->location());
3361   else if (type->integer_type() != NULL)
3362     {
3363       if (expr_type->integer_type() != NULL
3364           || expr_type->float_type() != NULL
3365           || expr_type->is_unsafe_pointer_type())
3366         ret = fold(convert_to_integer(type_tree, expr_tree));
3367       else
3368         gcc_unreachable();
3369     }
3370   else if (type->float_type() != NULL)
3371     {
3372       if (expr_type->integer_type() != NULL
3373           || expr_type->float_type() != NULL)
3374         ret = fold(convert_to_real(type_tree, expr_tree));
3375       else
3376         gcc_unreachable();
3377     }
3378   else if (type->complex_type() != NULL)
3379     {
3380       if (expr_type->complex_type() != NULL)
3381         ret = fold(convert_to_complex(type_tree, expr_tree));
3382       else
3383         gcc_unreachable();
3384     }
3385   else if (type->is_string_type()
3386            && expr_type->integer_type() != NULL)
3387     {
3388       expr_tree = fold_convert(integer_type_node, expr_tree);
3389       if (host_integerp(expr_tree, 0))
3390         {
3391           HOST_WIDE_INT intval = tree_low_cst(expr_tree, 0);
3392           std::string s;
3393           Lex::append_char(intval, true, &s, this->location());
3394           Expression* se = Expression::make_string(s, this->location());
3395           return se->get_tree(context);
3396         }
3397
3398       static tree int_to_string_fndecl;
3399       ret = Gogo::call_builtin(&int_to_string_fndecl,
3400                                this->location(),
3401                                "__go_int_to_string",
3402                                1,
3403                                type_tree,
3404                                integer_type_node,
3405                                fold_convert(integer_type_node, expr_tree));
3406     }
3407   else if (type->is_string_type()
3408            && (expr_type->array_type() != NULL
3409                || (expr_type->points_to() != NULL
3410                    && expr_type->points_to()->array_type() != NULL)))
3411     {
3412       Type* t = expr_type;
3413       if (t->points_to() != NULL)
3414         {
3415           t = t->points_to();
3416           expr_tree = build_fold_indirect_ref(expr_tree);
3417         }
3418       if (!DECL_P(expr_tree))
3419         expr_tree = save_expr(expr_tree);
3420       Array_type* a = t->array_type();
3421       Type* e = a->element_type()->forwarded();
3422       gcc_assert(e->integer_type() != NULL);
3423       tree valptr = fold_convert(const_ptr_type_node,
3424                                  a->value_pointer_tree(gogo, expr_tree));
3425       tree len = a->length_tree(gogo, expr_tree);
3426       len = fold_convert_loc(this->location(), size_type_node, len);
3427       if (e->integer_type()->is_unsigned()
3428           && e->integer_type()->bits() == 8)
3429         {
3430           static tree byte_array_to_string_fndecl;
3431           ret = Gogo::call_builtin(&byte_array_to_string_fndecl,
3432                                    this->location(),
3433                                    "__go_byte_array_to_string",
3434                                    2,
3435                                    type_tree,
3436                                    const_ptr_type_node,
3437                                    valptr,
3438                                    size_type_node,
3439                                    len);
3440         }
3441       else
3442         {
3443           gcc_assert(e == Type::lookup_integer_type("int"));
3444           static tree int_array_to_string_fndecl;
3445           ret = Gogo::call_builtin(&int_array_to_string_fndecl,
3446                                    this->location(),
3447                                    "__go_int_array_to_string",
3448                                    2,
3449                                    type_tree,
3450                                    const_ptr_type_node,
3451                                    valptr,
3452                                    size_type_node,
3453                                    len);
3454         }
3455     }
3456   else if (type->is_open_array_type() && expr_type->is_string_type())
3457     {
3458       Type* e = type->array_type()->element_type()->forwarded();
3459       gcc_assert(e->integer_type() != NULL);
3460       if (e->integer_type()->is_unsigned()
3461           && e->integer_type()->bits() == 8)
3462         {
3463           static tree string_to_byte_array_fndecl;
3464           ret = Gogo::call_builtin(&string_to_byte_array_fndecl,
3465                                    this->location(),
3466                                    "__go_string_to_byte_array",
3467                                    1,
3468                                    type_tree,
3469                                    TREE_TYPE(expr_tree),
3470                                    expr_tree);
3471         }
3472       else
3473         {
3474           gcc_assert(e == Type::lookup_integer_type("int"));
3475           static tree string_to_int_array_fndecl;
3476           ret = Gogo::call_builtin(&string_to_int_array_fndecl,
3477                                    this->location(),
3478                                    "__go_string_to_int_array",
3479                                    1,
3480                                    type_tree,
3481                                    TREE_TYPE(expr_tree),
3482                                    expr_tree);
3483         }
3484     }
3485   else if ((type->is_unsafe_pointer_type()
3486             && expr_type->points_to() != NULL)
3487            || (expr_type->is_unsafe_pointer_type()
3488                && type->points_to() != NULL))
3489     ret = fold_convert(type_tree, expr_tree);
3490   else if (type->is_unsafe_pointer_type()
3491            && expr_type->integer_type() != NULL)
3492     ret = convert_to_pointer(type_tree, expr_tree);
3493   else if (this->may_convert_function_types_
3494            && type->function_type() != NULL
3495            && expr_type->function_type() != NULL)
3496     ret = fold_convert_loc(this->location(), type_tree, expr_tree);
3497   else
3498     ret = Expression::convert_for_assignment(context, type, expr_type,
3499                                              expr_tree, this->location());
3500
3501   return ret;
3502 }
3503
3504 // Output a type conversion in a constant expression.
3505
3506 void
3507 Type_conversion_expression::do_export(Export* exp) const
3508 {
3509   exp->write_c_string("convert(");
3510   exp->write_type(this->type_);
3511   exp->write_c_string(", ");
3512   this->expr_->export_expression(exp);
3513   exp->write_c_string(")");
3514 }
3515
3516 // Import a type conversion or a struct construction.
3517
3518 Expression*
3519 Type_conversion_expression::do_import(Import* imp)
3520 {
3521   imp->require_c_string("convert(");
3522   Type* type = imp->read_type();
3523   imp->require_c_string(", ");
3524   Expression* val = Expression::import_expression(imp);
3525   imp->require_c_string(")");
3526   return Expression::make_cast(type, val, imp->location());
3527 }
3528
3529 // Make a type cast expression.
3530
3531 Expression*
3532 Expression::make_cast(Type* type, Expression* val, source_location location)
3533 {
3534   if (type->is_error_type() || val->is_error_expression())
3535     return Expression::make_error(location);
3536   return new Type_conversion_expression(type, val, location);
3537 }
3538
3539 // Unary expressions.
3540
3541 class Unary_expression : public Expression
3542 {
3543  public:
3544   Unary_expression(Operator op, Expression* expr, source_location location)
3545     : Expression(EXPRESSION_UNARY, location),
3546       op_(op), escapes_(true), expr_(expr)
3547   { }
3548
3549   // Return the operator.
3550   Operator
3551   op() const
3552   { return this->op_; }
3553
3554   // Return the operand.
3555   Expression*
3556   operand() const
3557   { return this->expr_; }
3558
3559   // Record that an address expression does not escape.
3560   void
3561   set_does_not_escape()
3562   {
3563     gcc_assert(this->op_ == OPERATOR_AND);
3564     this->escapes_ = false;
3565   }
3566
3567   // Apply unary opcode OP to UVAL, setting VAL.  Return true if this
3568   // could be done, false if not.
3569   static bool
3570   eval_integer(Operator op, Type* utype, mpz_t uval, mpz_t val,
3571                source_location);
3572
3573   // Apply unary opcode OP to UVAL, setting VAL.  Return true if this
3574   // could be done, false if not.
3575   static bool
3576   eval_float(Operator op, mpfr_t uval, mpfr_t val);
3577
3578   // Apply unary opcode OP to UREAL/UIMAG, setting REAL/IMAG.  Return
3579   // true if this could be done, false if not.
3580   static bool
3581   eval_complex(Operator op, mpfr_t ureal, mpfr_t uimag, mpfr_t real,
3582                mpfr_t imag);
3583
3584   static Expression*
3585   do_import(Import*);
3586
3587  protected:
3588   int
3589   do_traverse(Traverse* traverse)
3590   { return Expression::traverse(&this->expr_, traverse); }
3591
3592   Expression*
3593   do_lower(Gogo*, Named_object*, int);
3594
3595   bool
3596   do_is_constant() const;
3597
3598   bool
3599   do_integer_constant_value(bool, mpz_t, Type**) const;
3600
3601   bool
3602   do_float_constant_value(mpfr_t, Type**) const;
3603
3604   bool
3605   do_complex_constant_value(mpfr_t, mpfr_t, Type**) const;
3606
3607   Type*
3608   do_type();
3609
3610   void
3611   do_determine_type(const Type_context*);
3612
3613   void
3614   do_check_types(Gogo*);
3615
3616   Expression*
3617   do_copy()
3618   {
3619     return Expression::make_unary(this->op_, this->expr_->copy(),
3620                                   this->location());
3621   }
3622
3623   bool
3624   do_is_addressable() const
3625   { return this->op_ == OPERATOR_MULT; }
3626
3627   tree
3628   do_get_tree(Translate_context*);
3629
3630   void
3631   do_export(Export*) const;
3632
3633  private:
3634   // The unary operator to apply.
3635   Operator op_;
3636   // Normally true.  False if this is an address expression which does
3637   // not escape the current function.
3638   bool escapes_;
3639   // The operand.
3640   Expression* expr_;
3641 };
3642
3643 // If we are taking the address of a composite literal, and the
3644 // contents are not constant, then we want to make a heap composite
3645 // instead.
3646
3647 Expression*
3648 Unary_expression::do_lower(Gogo*, Named_object*, int)
3649 {
3650   source_location loc = this->location();
3651   Operator op = this->op_;
3652   Expression* expr = this->expr_;
3653
3654   if (op == OPERATOR_MULT && expr->is_type_expression())
3655     return Expression::make_type(Type::make_pointer_type(expr->type()), loc);
3656
3657   // *&x simplifies to x.  *(*T)(unsafe.Pointer)(&x) does not require
3658   // moving x to the heap.  FIXME: Is it worth doing a real escape
3659   // analysis here?  This case is found in math/unsafe.go and is
3660   // therefore worth special casing.
3661   if (op == OPERATOR_MULT)
3662     {
3663       Expression* e = expr;
3664       while (e->classification() == EXPRESSION_CONVERSION)
3665         {
3666           Type_conversion_expression* te
3667             = static_cast<Type_conversion_expression*>(e);
3668           e = te->expr();
3669         }
3670
3671       if (e->classification() == EXPRESSION_UNARY)
3672         {
3673           Unary_expression* ue = static_cast<Unary_expression*>(e);
3674           if (ue->op_ == OPERATOR_AND)
3675             {
3676               if (e == expr)
3677                 {
3678                   // *&x == x.
3679                   return ue->expr_;
3680                 }
3681               ue->set_does_not_escape();
3682             }
3683         }
3684     }
3685
3686   if (op == OPERATOR_PLUS || op == OPERATOR_MINUS
3687       || op == OPERATOR_NOT || op == OPERATOR_XOR)
3688     {
3689       Expression* ret = NULL;
3690
3691       mpz_t eval;
3692       mpz_init(eval);
3693       Type* etype;
3694       if (expr->integer_constant_value(false, eval, &etype))
3695         {
3696           mpz_t val;
3697           mpz_init(val);
3698           if (Unary_expression::eval_integer(op, etype, eval, val, loc))
3699             ret = Expression::make_integer(&val, etype, loc);
3700           mpz_clear(val);
3701         }
3702       mpz_clear(eval);
3703       if (ret != NULL)
3704         return ret;
3705
3706       if (op == OPERATOR_PLUS || op == OPERATOR_MINUS)
3707         {
3708           mpfr_t fval;
3709           mpfr_init(fval);
3710           Type* ftype;
3711           if (expr->float_constant_value(fval, &ftype))
3712             {
3713               mpfr_t val;
3714               mpfr_init(val);
3715               if (Unary_expression::eval_float(op, fval, val))
3716                 ret = Expression::make_float(&val, ftype, loc);
3717               mpfr_clear(val);
3718             }
3719           if (ret != NULL)
3720             {
3721               mpfr_clear(fval);
3722               return ret;
3723             }
3724
3725           mpfr_t ival;
3726           mpfr_init(ival);
3727           if (expr->complex_constant_value(fval, ival, &ftype))
3728             {
3729               mpfr_t real;
3730               mpfr_t imag;
3731               mpfr_init(real);
3732               mpfr_init(imag);
3733               if (Unary_expression::eval_complex(op, fval, ival, real, imag))
3734                 ret = Expression::make_complex(&real, &imag, ftype, loc);
3735               mpfr_clear(real);
3736               mpfr_clear(imag);
3737             }
3738           mpfr_clear(ival);
3739           mpfr_clear(fval);
3740           if (ret != NULL)
3741             return ret;
3742         }
3743     }
3744
3745   return this;
3746 }
3747
3748 // Return whether a unary expression is a constant.
3749
3750 bool
3751 Unary_expression::do_is_constant() const
3752 {
3753   if (this->op_ == OPERATOR_MULT)
3754     {
3755       // Indirecting through a pointer is only constant if the object
3756       // to which the expression points is constant, but we currently
3757       // have no way to determine that.
3758       return false;
3759     }
3760   else if (this->op_ == OPERATOR_AND)
3761     {
3762       // Taking the address of a variable is constant if it is a
3763       // global variable, not constant otherwise.  In other cases
3764       // taking the address is probably not a constant.
3765       Var_expression* ve = this->expr_->var_expression();
3766       if (ve != NULL)
3767         {
3768           Named_object* no = ve->named_object();
3769           return no->is_variable() && no->var_value()->is_global();
3770         }
3771       return false;
3772     }
3773   else
3774     return this->expr_->is_constant();
3775 }
3776
3777 // Apply unary opcode OP to UVAL, setting VAL.  UTYPE is the type of
3778 // UVAL, if known; it may be NULL.  Return true if this could be done,
3779 // false if not.
3780
3781 bool
3782 Unary_expression::eval_integer(Operator op, Type* utype, mpz_t uval, mpz_t val,
3783                                source_location location)
3784 {
3785   switch (op)
3786     {
3787     case OPERATOR_PLUS:
3788       mpz_set(val, uval);
3789       return true;
3790     case OPERATOR_MINUS:
3791       mpz_neg(val, uval);
3792       return Integer_expression::check_constant(val, utype, location);
3793     case OPERATOR_NOT:
3794       mpz_set_ui(val, mpz_cmp_si(uval, 0) == 0 ? 1 : 0);
3795       return true;
3796     case OPERATOR_XOR:
3797       if (utype == NULL
3798           || utype->integer_type() == NULL
3799           || utype->integer_type()->is_abstract())
3800         mpz_com(val, uval);
3801       else
3802         {
3803           // The number of HOST_WIDE_INTs that it takes to represent
3804           // UVAL.
3805           size_t count = ((mpz_sizeinbase(uval, 2)
3806                            + HOST_BITS_PER_WIDE_INT
3807                            - 1)
3808                           / HOST_BITS_PER_WIDE_INT);
3809
3810           unsigned HOST_WIDE_INT* phwi = new unsigned HOST_WIDE_INT[count];
3811           memset(phwi, 0, count * sizeof(HOST_WIDE_INT));
3812
3813           size_t ecount;
3814           mpz_export(phwi, &ecount, -1, sizeof(HOST_WIDE_INT), 0, 0, uval);
3815           gcc_assert(ecount <= count);
3816
3817           // Trim down to the number of words required by the type.
3818           size_t obits = utype->integer_type()->bits();
3819           if (!utype->integer_type()->is_unsigned())
3820             ++obits;
3821           size_t ocount = ((obits + HOST_BITS_PER_WIDE_INT - 1)
3822                            / HOST_BITS_PER_WIDE_INT);
3823           gcc_assert(ocount <= ocount);
3824
3825           for (size_t i = 0; i < ocount; ++i)
3826             phwi[i] = ~phwi[i];
3827
3828           size_t clearbits = ocount * HOST_BITS_PER_WIDE_INT - obits;
3829           if (clearbits != 0)
3830             phwi[ocount - 1] &= (((unsigned HOST_WIDE_INT) (HOST_WIDE_INT) -1)
3831                                  >> clearbits);
3832
3833           mpz_import(val, ocount, -1, sizeof(HOST_WIDE_INT), 0, 0, phwi);
3834
3835           delete[] phwi;
3836         }
3837       return Integer_expression::check_constant(val, utype, location);
3838     case OPERATOR_AND:
3839     case OPERATOR_MULT:
3840       return false;
3841     default:
3842       gcc_unreachable();
3843     }
3844 }
3845
3846 // Apply unary opcode OP to UVAL, setting VAL.  Return true if this
3847 // could be done, false if not.
3848
3849 bool
3850 Unary_expression::eval_float(Operator op, mpfr_t uval, mpfr_t val)
3851 {
3852   switch (op)
3853     {
3854     case OPERATOR_PLUS:
3855       mpfr_set(val, uval, GMP_RNDN);
3856       return true;
3857     case OPERATOR_MINUS:
3858       mpfr_neg(val, uval, GMP_RNDN);
3859       return true;
3860     case OPERATOR_NOT:
3861     case OPERATOR_XOR:
3862     case OPERATOR_AND:
3863     case OPERATOR_MULT:
3864       return false;
3865     default:
3866       gcc_unreachable();
3867     }
3868 }
3869
3870 // Apply unary opcode OP to RVAL/IVAL, setting REAL/IMAG.  Return true
3871 // if this could be done, false if not.
3872
3873 bool
3874 Unary_expression::eval_complex(Operator op, mpfr_t rval, mpfr_t ival,
3875                                mpfr_t real, mpfr_t imag)
3876 {
3877   switch (op)
3878     {
3879     case OPERATOR_PLUS:
3880       mpfr_set(real, rval, GMP_RNDN);
3881       mpfr_set(imag, ival, GMP_RNDN);
3882       return true;
3883     case OPERATOR_MINUS:
3884       mpfr_neg(real, rval, GMP_RNDN);
3885       mpfr_neg(imag, ival, GMP_RNDN);
3886       return true;
3887     case OPERATOR_NOT:
3888     case OPERATOR_XOR:
3889     case OPERATOR_AND:
3890     case OPERATOR_MULT:
3891       return false;
3892     default:
3893       gcc_unreachable();
3894     }
3895 }
3896
3897 // Return the integral constant value of a unary expression, if it has one.
3898
3899 bool
3900 Unary_expression::do_integer_constant_value(bool iota_is_constant, mpz_t val,
3901                                             Type** ptype) const
3902 {
3903   mpz_t uval;
3904   mpz_init(uval);
3905   bool ret;
3906   if (!this->expr_->integer_constant_value(iota_is_constant, uval, ptype))
3907     ret = false;
3908   else
3909     ret = Unary_expression::eval_integer(this->op_, *ptype, uval, val,
3910                                          this->location());
3911   mpz_clear(uval);
3912   return ret;
3913 }
3914
3915 // Return the floating point constant value of a unary expression, if
3916 // it has one.
3917
3918 bool
3919 Unary_expression::do_float_constant_value(mpfr_t val, Type** ptype) const
3920 {
3921   mpfr_t uval;
3922   mpfr_init(uval);
3923   bool ret;
3924   if (!this->expr_->float_constant_value(uval, ptype))
3925     ret = false;
3926   else
3927     ret = Unary_expression::eval_float(this->op_, uval, val);
3928   mpfr_clear(uval);
3929   return ret;
3930 }
3931
3932 // Return the complex constant value of a unary expression, if it has
3933 // one.
3934
3935 bool
3936 Unary_expression::do_complex_constant_value(mpfr_t real, mpfr_t imag,
3937                                             Type** ptype) const
3938 {
3939   mpfr_t rval;
3940   mpfr_t ival;
3941   mpfr_init(rval);
3942   mpfr_init(ival);
3943   bool ret;
3944   if (!this->expr_->complex_constant_value(rval, ival, ptype))
3945     ret = false;
3946   else
3947     ret = Unary_expression::eval_complex(this->op_, rval, ival, real, imag);
3948   mpfr_clear(rval);
3949   mpfr_clear(ival);
3950   return ret;
3951 }
3952
3953 // Return the type of a unary expression.
3954
3955 Type*
3956 Unary_expression::do_type()
3957 {
3958   switch (this->op_)
3959     {
3960     case OPERATOR_PLUS:
3961     case OPERATOR_MINUS:
3962     case OPERATOR_NOT:
3963     case OPERATOR_XOR:
3964       return this->expr_->type();
3965
3966     case OPERATOR_AND:
3967       return Type::make_pointer_type(this->expr_->type());
3968
3969     case OPERATOR_MULT:
3970       {
3971         Type* subtype = this->expr_->type();
3972         Type* points_to = subtype->points_to();
3973         if (points_to == NULL)
3974           return Type::make_error_type();
3975         return points_to;
3976       }
3977
3978     default:
3979       gcc_unreachable();
3980     }
3981 }
3982
3983 // Determine abstract types for a unary expression.
3984
3985 void
3986 Unary_expression::do_determine_type(const Type_context* context)
3987 {
3988   switch (this->op_)
3989     {
3990     case OPERATOR_PLUS:
3991     case OPERATOR_MINUS:
3992     case OPERATOR_NOT:
3993     case OPERATOR_XOR:
3994       this->expr_->determine_type(context);
3995       break;
3996
3997     case OPERATOR_AND:
3998       // Taking the address of something.
3999       {
4000         Type* subtype = (context->type == NULL
4001                          ? NULL
4002                          : context->type->points_to());
4003         Type_context subcontext(subtype, false);
4004         this->expr_->determine_type(&subcontext);
4005       }
4006       break;
4007
4008     case OPERATOR_MULT:
4009       // Indirecting through a pointer.
4010       {
4011         Type* subtype = (context->type == NULL
4012                          ? NULL
4013                          : Type::make_pointer_type(context->type));
4014         Type_context subcontext(subtype, false);
4015         this->expr_->determine_type(&subcontext);
4016       }
4017       break;
4018
4019     default:
4020       gcc_unreachable();
4021     }
4022 }
4023
4024 // Check types for a unary expression.
4025
4026 void
4027 Unary_expression::do_check_types(Gogo*)
4028 {
4029   Type* type = this->expr_->type();
4030   if (type->is_error_type())
4031     {
4032       this->set_is_error();
4033       return;
4034     }
4035
4036   switch (this->op_)
4037     {
4038     case OPERATOR_PLUS:
4039     case OPERATOR_MINUS:
4040       if (type->integer_type() == NULL
4041           && type->float_type() == NULL
4042           && type->complex_type() == NULL)
4043         this->report_error(_("expected numeric type"));
4044       break;
4045
4046     case OPERATOR_NOT:
4047     case OPERATOR_XOR:
4048       if (type->integer_type() == NULL
4049           && !type->is_boolean_type())
4050         this->report_error(_("expected integer or boolean type"));
4051       break;
4052
4053     case OPERATOR_AND:
4054       if (!this->expr_->is_addressable())
4055         this->report_error(_("invalid operand for unary %<&%>"));
4056       else
4057         this->expr_->address_taken(this->escapes_);
4058       break;
4059
4060     case OPERATOR_MULT:
4061       // Indirecting through a pointer.
4062       if (type->points_to() == NULL)
4063         this->report_error(_("expected pointer"));
4064       break;
4065
4066     default:
4067       gcc_unreachable();
4068     }
4069 }
4070
4071 // Get a tree for a unary expression.
4072
4073 tree
4074 Unary_expression::do_get_tree(Translate_context* context)
4075 {
4076   tree expr = this->expr_->get_tree(context);
4077   if (expr == error_mark_node)
4078     return error_mark_node;
4079
4080   source_location loc = this->location();
4081   switch (this->op_)
4082     {
4083     case OPERATOR_PLUS:
4084       return expr;
4085
4086     case OPERATOR_MINUS:
4087       {
4088         tree type = TREE_TYPE(expr);
4089         tree compute_type = excess_precision_type(type);
4090         if (compute_type != NULL_TREE)
4091           expr = ::convert(compute_type, expr);
4092         tree ret = fold_build1_loc(loc, NEGATE_EXPR,
4093                                    (compute_type != NULL_TREE
4094                                     ? compute_type
4095                                     : type),
4096                                    expr);
4097         if (compute_type != NULL_TREE)
4098           ret = ::convert(type, ret);
4099         return ret;
4100       }
4101
4102     case OPERATOR_NOT:
4103       if (TREE_CODE(TREE_TYPE(expr)) == BOOLEAN_TYPE)
4104         return fold_build1_loc(loc, TRUTH_NOT_EXPR, TREE_TYPE(expr), expr);
4105       else
4106         return fold_build2_loc(loc, NE_EXPR, boolean_type_node, expr,
4107                                build_int_cst(TREE_TYPE(expr), 0));
4108
4109     case OPERATOR_XOR:
4110       return fold_build1_loc(loc, BIT_NOT_EXPR, TREE_TYPE(expr), expr);
4111
4112     case OPERATOR_AND:
4113       // We should not see a non-constant constructor here; cases
4114       // where we would see one should have been moved onto the heap
4115       // at parse time.  Taking the address of a nonconstant
4116       // constructor will not do what the programmer expects.
4117       gcc_assert(TREE_CODE(expr) != CONSTRUCTOR || TREE_CONSTANT(expr));
4118       gcc_assert(TREE_CODE(expr) != ADDR_EXPR);
4119
4120       // Build a decl for a constant constructor.
4121       if (TREE_CODE(expr) == CONSTRUCTOR && TREE_CONSTANT(expr))
4122         {
4123           tree decl = build_decl(this->location(), VAR_DECL,
4124                                  create_tmp_var_name("C"), TREE_TYPE(expr));
4125           DECL_EXTERNAL(decl) = 0;
4126           TREE_PUBLIC(decl) = 0;
4127           TREE_READONLY(decl) = 1;
4128           TREE_CONSTANT(decl) = 1;
4129           TREE_STATIC(decl) = 1;
4130           TREE_ADDRESSABLE(decl) = 1;
4131           DECL_ARTIFICIAL(decl) = 1;
4132           DECL_INITIAL(decl) = expr;
4133           rest_of_decl_compilation(decl, 1, 0);
4134           expr = decl;
4135         }
4136
4137       return build_fold_addr_expr_loc(loc, expr);
4138
4139     case OPERATOR_MULT:
4140       {
4141         gcc_assert(POINTER_TYPE_P(TREE_TYPE(expr)));
4142
4143         // If we are dereferencing the pointer to a large struct, we
4144         // need to check for nil.  We don't bother to check for small
4145         // structs because we expect the system to crash on a nil
4146         // pointer dereference.
4147         HOST_WIDE_INT s = int_size_in_bytes(TREE_TYPE(TREE_TYPE(expr)));
4148         if (s == -1 || s >= 4096)
4149           {
4150             if (!DECL_P(expr))
4151               expr = save_expr(expr);
4152             tree compare = fold_build2_loc(loc, EQ_EXPR, boolean_type_node,
4153                                            expr,
4154                                            fold_convert(TREE_TYPE(expr),
4155                                                         null_pointer_node));
4156             tree crash = Gogo::runtime_error(RUNTIME_ERROR_NIL_DEREFERENCE,
4157                                              loc);
4158             expr = fold_build2_loc(loc, COMPOUND_EXPR, TREE_TYPE(expr),
4159                                    build3(COND_EXPR, void_type_node,
4160                                           compare, crash, NULL_TREE),
4161                                    expr);
4162           }
4163
4164         // If the type of EXPR is a recursive pointer type, then we
4165         // need to insert a cast before indirecting.
4166         if (TREE_TYPE(TREE_TYPE(expr)) == ptr_type_node)
4167           {
4168             Type* pt = this->expr_->type()->points_to();
4169             tree ind = pt->get_tree(context->gogo());
4170             expr = fold_convert_loc(loc, build_pointer_type(ind), expr);
4171           }
4172
4173         return build_fold_indirect_ref_loc(loc, expr);
4174       }
4175
4176     default:
4177       gcc_unreachable();
4178     }
4179 }
4180
4181 // Export a unary expression.
4182
4183 void
4184 Unary_expression::do_export(Export* exp) const
4185 {
4186   switch (this->op_)
4187     {
4188     case OPERATOR_PLUS:
4189       exp->write_c_string("+ ");
4190       break;
4191     case OPERATOR_MINUS:
4192       exp->write_c_string("- ");
4193       break;
4194     case OPERATOR_NOT:
4195       exp->write_c_string("! ");
4196       break;
4197     case OPERATOR_XOR:
4198       exp->write_c_string("^ ");
4199       break;
4200     case OPERATOR_AND:
4201     case OPERATOR_MULT:
4202     default:
4203       gcc_unreachable();
4204     }
4205   this->expr_->export_expression(exp);
4206 }
4207
4208 // Import a unary expression.
4209
4210 Expression*
4211 Unary_expression::do_import(Import* imp)
4212 {
4213   Operator op;
4214   switch (imp->get_char())
4215     {
4216     case '+':
4217       op = OPERATOR_PLUS;
4218       break;
4219     case '-':
4220       op = OPERATOR_MINUS;
4221       break;
4222     case '!':
4223       op = OPERATOR_NOT;
4224       break;
4225     case '^':
4226       op = OPERATOR_XOR;
4227       break;
4228     default:
4229       gcc_unreachable();
4230     }
4231   imp->require_c_string(" ");
4232   Expression* expr = Expression::import_expression(imp);
4233   return Expression::make_unary(op, expr, imp->location());
4234 }
4235
4236 // Make a unary expression.
4237
4238 Expression*
4239 Expression::make_unary(Operator op, Expression* expr, source_location location)
4240 {
4241   return new Unary_expression(op, expr, location);
4242 }
4243
4244 // If this is an indirection through a pointer, return the expression
4245 // being pointed through.  Otherwise return this.
4246
4247 Expression*
4248 Expression::deref()
4249 {
4250   if (this->classification_ == EXPRESSION_UNARY)
4251     {
4252       Unary_expression* ue = static_cast<Unary_expression*>(this);
4253       if (ue->op() == OPERATOR_MULT)
4254         return ue->operand();
4255     }
4256   return this;
4257 }
4258
4259 // Class Binary_expression.
4260
4261 // Traversal.
4262
4263 int
4264 Binary_expression::do_traverse(Traverse* traverse)
4265 {
4266   int t = Expression::traverse(&this->left_, traverse);
4267   if (t == TRAVERSE_EXIT)
4268     return TRAVERSE_EXIT;
4269   return Expression::traverse(&this->right_, traverse);
4270 }
4271
4272 // Compare integer constants according to OP.
4273
4274 bool
4275 Binary_expression::compare_integer(Operator op, mpz_t left_val,
4276                                    mpz_t right_val)
4277 {
4278   int i = mpz_cmp(left_val, right_val);
4279   switch (op)
4280     {
4281     case OPERATOR_EQEQ:
4282       return i == 0;
4283     case OPERATOR_NOTEQ:
4284       return i != 0;
4285     case OPERATOR_LT:
4286       return i < 0;
4287     case OPERATOR_LE:
4288       return i <= 0;
4289     case OPERATOR_GT:
4290       return i > 0;
4291     case OPERATOR_GE:
4292       return i >= 0;
4293     default:
4294       gcc_unreachable();
4295     }
4296 }
4297
4298 // Compare floating point constants according to OP.
4299
4300 bool
4301 Binary_expression::compare_float(Operator op, Type* type, mpfr_t left_val,
4302                                  mpfr_t right_val)
4303 {
4304   int i;
4305   if (type == NULL)
4306     i = mpfr_cmp(left_val, right_val);
4307   else
4308     {
4309       mpfr_t lv;
4310       mpfr_init_set(lv, left_val, GMP_RNDN);
4311       mpfr_t rv;
4312       mpfr_init_set(rv, right_val, GMP_RNDN);
4313       Float_expression::constrain_float(lv, type);
4314       Float_expression::constrain_float(rv, type);
4315       i = mpfr_cmp(lv, rv);
4316       mpfr_clear(lv);
4317       mpfr_clear(rv);
4318     }
4319   switch (op)
4320     {
4321     case OPERATOR_EQEQ:
4322       return i == 0;
4323     case OPERATOR_NOTEQ:
4324       return i != 0;
4325     case OPERATOR_LT:
4326       return i < 0;
4327     case OPERATOR_LE:
4328       return i <= 0;
4329     case OPERATOR_GT:
4330       return i > 0;
4331     case OPERATOR_GE:
4332       return i >= 0;
4333     default:
4334       gcc_unreachable();
4335     }
4336 }
4337
4338 // Compare complex constants according to OP.  Complex numbers may
4339 // only be compared for equality.
4340
4341 bool
4342 Binary_expression::compare_complex(Operator op, Type* type,
4343                                    mpfr_t left_real, mpfr_t left_imag,
4344                                    mpfr_t right_real, mpfr_t right_imag)
4345 {
4346   bool is_equal;
4347   if (type == NULL)
4348     is_equal = (mpfr_cmp(left_real, right_real) == 0
4349                 && mpfr_cmp(left_imag, right_imag) == 0);
4350   else
4351     {
4352       mpfr_t lr;
4353       mpfr_t li;
4354       mpfr_init_set(lr, left_real, GMP_RNDN);
4355       mpfr_init_set(li, left_imag, GMP_RNDN);
4356       mpfr_t rr;
4357       mpfr_t ri;
4358       mpfr_init_set(rr, right_real, GMP_RNDN);
4359       mpfr_init_set(ri, right_imag, GMP_RNDN);
4360       Complex_expression::constrain_complex(lr, li, type);
4361       Complex_expression::constrain_complex(rr, ri, type);
4362       is_equal = mpfr_cmp(lr, rr) == 0 && mpfr_cmp(li, ri) == 0;
4363       mpfr_clear(lr);
4364       mpfr_clear(li);
4365       mpfr_clear(rr);
4366       mpfr_clear(ri);
4367     }
4368   switch (op)
4369     {
4370     case OPERATOR_EQEQ:
4371       return is_equal;
4372     case OPERATOR_NOTEQ:
4373       return !is_equal;
4374     default:
4375       gcc_unreachable();
4376     }
4377 }
4378
4379 // Apply binary opcode OP to LEFT_VAL and RIGHT_VAL, setting VAL.
4380 // LEFT_TYPE is the type of LEFT_VAL, RIGHT_TYPE is the type of
4381 // RIGHT_VAL; LEFT_TYPE and/or RIGHT_TYPE may be NULL.  Return true if
4382 // this could be done, false if not.
4383
4384 bool
4385 Binary_expression::eval_integer(Operator op, Type* left_type, mpz_t left_val,
4386                                 Type* right_type, mpz_t right_val,
4387                                 source_location location, mpz_t val)
4388 {
4389   bool is_shift_op = false;
4390   switch (op)
4391     {
4392     case OPERATOR_OROR:
4393     case OPERATOR_ANDAND:
4394     case OPERATOR_EQEQ:
4395     case OPERATOR_NOTEQ:
4396     case OPERATOR_LT:
4397     case OPERATOR_LE:
4398     case OPERATOR_GT:
4399     case OPERATOR_GE:
4400       // These return boolean values.  We should probably handle them
4401       // anyhow in case a type conversion is used on the result.
4402       return false;
4403     case OPERATOR_PLUS:
4404       mpz_add(val, left_val, right_val);
4405       break;
4406     case OPERATOR_MINUS:
4407       mpz_sub(val, left_val, right_val);
4408       break;
4409     case OPERATOR_OR:
4410       mpz_ior(val, left_val, right_val);
4411       break;
4412     case OPERATOR_XOR:
4413       mpz_xor(val, left_val, right_val);
4414       break;
4415     case OPERATOR_MULT:
4416       mpz_mul(val, left_val, right_val);
4417       break;
4418     case OPERATOR_DIV:
4419       if (mpz_sgn(right_val) != 0)
4420         mpz_tdiv_q(val, left_val, right_val);
4421       else
4422         {
4423           error_at(location, "division by zero");
4424           mpz_set_ui(val, 0);
4425           return true;
4426         }
4427       break;
4428     case OPERATOR_MOD:
4429       if (mpz_sgn(right_val) != 0)
4430         mpz_tdiv_r(val, left_val, right_val);
4431       else
4432         {
4433           error_at(location, "division by zero");
4434           mpz_set_ui(val, 0);
4435           return true;
4436         }
4437       break;
4438     case OPERATOR_LSHIFT:
4439       {
4440         unsigned long shift = mpz_get_ui(right_val);
4441         if (mpz_cmp_ui(right_val, shift) != 0 || shift > 0x100000)
4442           {
4443             error_at(location, "shift count overflow");
4444             mpz_set_ui(val, 0);
4445             return true;
4446           }
4447         mpz_mul_2exp(val, left_val, shift);
4448         is_shift_op = true;
4449         break;
4450       }
4451       break;
4452     case OPERATOR_RSHIFT:
4453       {
4454         unsigned long shift = mpz_get_ui(right_val);
4455         if (mpz_cmp_ui(right_val, shift) != 0)
4456           {
4457             error_at(location, "shift count overflow");
4458             mpz_set_ui(val, 0);
4459             return true;
4460           }
4461         if (mpz_cmp_ui(left_val, 0) >= 0)
4462           mpz_tdiv_q_2exp(val, left_val, shift);
4463         else
4464           mpz_fdiv_q_2exp(val, left_val, shift);
4465         is_shift_op = true;
4466         break;
4467       }
4468       break;
4469     case OPERATOR_AND:
4470       mpz_and(val, left_val, right_val);
4471       break;
4472     case OPERATOR_BITCLEAR:
4473       {
4474         mpz_t tval;
4475         mpz_init(tval);
4476         mpz_com(tval, right_val);
4477         mpz_and(val, left_val, tval);
4478         mpz_clear(tval);
4479       }
4480       break;
4481     default:
4482       gcc_unreachable();
4483     }
4484
4485   Type* type = left_type;
4486   if (!is_shift_op)
4487     {
4488       if (type == NULL)
4489         type = right_type;
4490       else if (type != right_type && right_type != NULL)
4491         {
4492           if (type->is_abstract())
4493             type = right_type;
4494           else if (!right_type->is_abstract())
4495             {
4496               // This look like a type error which should be diagnosed
4497               // elsewhere.  Don't do anything here, to avoid an
4498               // unhelpful chain of error messages.
4499               return true;
4500             }
4501         }
4502     }
4503
4504   if (type != NULL && !type->is_abstract())
4505     {
4506       // We have to check the operands too, as we have implicitly
4507       // coerced them to TYPE.
4508       if ((type != left_type
4509            && !Integer_expression::check_constant(left_val, type, location))
4510           || (!is_shift_op
4511               && type != right_type
4512               && !Integer_expression::check_constant(right_val, type,
4513                                                      location))
4514           || !Integer_expression::check_constant(val, type, location))
4515         mpz_set_ui(val, 0);
4516     }
4517
4518   return true;
4519 }
4520
4521 // Apply binary opcode OP to LEFT_VAL and RIGHT_VAL, setting VAL.
4522 // Return true if this could be done, false if not.
4523
4524 bool
4525 Binary_expression::eval_float(Operator op, Type* left_type, mpfr_t left_val,
4526                               Type* right_type, mpfr_t right_val,
4527                               mpfr_t val, source_location location)
4528 {
4529   switch (op)
4530     {
4531     case OPERATOR_OROR:
4532     case OPERATOR_ANDAND:
4533     case OPERATOR_EQEQ:
4534     case OPERATOR_NOTEQ:
4535     case OPERATOR_LT:
4536     case OPERATOR_LE:
4537     case OPERATOR_GT:
4538     case OPERATOR_GE:
4539       // These return boolean values.  We should probably handle them
4540       // anyhow in case a type conversion is used on the result.
4541       return false;
4542     case OPERATOR_PLUS:
4543       mpfr_add(val, left_val, right_val, GMP_RNDN);
4544       break;
4545     case OPERATOR_MINUS:
4546       mpfr_sub(val, left_val, right_val, GMP_RNDN);
4547       break;
4548     case OPERATOR_OR:
4549     case OPERATOR_XOR:
4550     case OPERATOR_AND:
4551     case OPERATOR_BITCLEAR:
4552       return false;
4553     case OPERATOR_MULT:
4554       mpfr_mul(val, left_val, right_val, GMP_RNDN);
4555       break;
4556     case OPERATOR_DIV:
4557       if (mpfr_zero_p(right_val))
4558         error_at(location, "division by zero");
4559       mpfr_div(val, left_val, right_val, GMP_RNDN);
4560       break;
4561     case OPERATOR_MOD:
4562       return false;
4563     case OPERATOR_LSHIFT:
4564     case OPERATOR_RSHIFT:
4565       return false;
4566     default:
4567       gcc_unreachable();
4568     }
4569
4570   Type* type = left_type;
4571   if (type == NULL)
4572     type = right_type;
4573   else if (type != right_type && right_type != NULL)
4574     {
4575       if (type->is_abstract())
4576         type = right_type;
4577       else if (!right_type->is_abstract())
4578         {
4579           // This looks like a type error which should be diagnosed
4580           // elsewhere.  Don't do anything here, to avoid an unhelpful
4581           // chain of error messages.
4582           return true;
4583         }
4584     }
4585
4586   if (type != NULL && !type->is_abstract())
4587     {
4588       if ((type != left_type
4589            && !Float_expression::check_constant(left_val, type, location))
4590           || (type != right_type
4591               && !Float_expression::check_constant(right_val, type,
4592                                                    location))
4593           || !Float_expression::check_constant(val, type, location))
4594         mpfr_set_ui(val, 0, GMP_RNDN);
4595     }
4596
4597   return true;
4598 }
4599
4600 // Apply binary opcode OP to LEFT_REAL/LEFT_IMAG and
4601 // RIGHT_REAL/RIGHT_IMAG, setting REAL/IMAG.  Return true if this
4602 // could be done, false if not.
4603
4604 bool
4605 Binary_expression::eval_complex(Operator op, Type* left_type,
4606                                 mpfr_t left_real, mpfr_t left_imag,
4607                                 Type *right_type,
4608                                 mpfr_t right_real, mpfr_t right_imag,
4609                                 mpfr_t real, mpfr_t imag,
4610                                 source_location location)
4611 {
4612   switch (op)
4613     {
4614     case OPERATOR_OROR:
4615     case OPERATOR_ANDAND:
4616     case OPERATOR_EQEQ:
4617     case OPERATOR_NOTEQ:
4618     case OPERATOR_LT:
4619     case OPERATOR_LE:
4620     case OPERATOR_GT:
4621     case OPERATOR_GE:
4622       // These return boolean values and must be handled differently.
4623       return false;
4624     case OPERATOR_PLUS:
4625       mpfr_add(real, left_real, right_real, GMP_RNDN);
4626       mpfr_add(imag, left_imag, right_imag, GMP_RNDN);
4627       break;
4628     case OPERATOR_MINUS:
4629       mpfr_sub(real, left_real, right_real, GMP_RNDN);
4630       mpfr_sub(imag, left_imag, right_imag, GMP_RNDN);
4631       break;
4632     case OPERATOR_OR:
4633     case OPERATOR_XOR:
4634     case OPERATOR_AND:
4635     case OPERATOR_BITCLEAR:
4636       return false;
4637     case OPERATOR_MULT:
4638       {
4639         // You might think that multiplying two complex numbers would
4640         // be simple, and you would be right, until you start to think
4641         // about getting the right answer for infinity.  If one
4642         // operand here is infinity and the other is anything other
4643         // than zero or NaN, then we are going to wind up subtracting
4644         // two infinity values.  That will give us a NaN, but the
4645         // correct answer is infinity.
4646
4647         mpfr_t lrrr;
4648         mpfr_init(lrrr);
4649         mpfr_mul(lrrr, left_real, right_real, GMP_RNDN);
4650
4651         mpfr_t lrri;
4652         mpfr_init(lrri);
4653         mpfr_mul(lrri, left_real, right_imag, GMP_RNDN);
4654
4655         mpfr_t lirr;
4656         mpfr_init(lirr);
4657         mpfr_mul(lirr, left_imag, right_real, GMP_RNDN);
4658
4659         mpfr_t liri;
4660         mpfr_init(liri);
4661         mpfr_mul(liri, left_imag, right_imag, GMP_RNDN);
4662
4663         mpfr_sub(real, lrrr, liri, GMP_RNDN);
4664         mpfr_add(imag, lrri, lirr, GMP_RNDN);
4665
4666         // If we get NaN on both sides, check whether it should really
4667         // be infinity.  The rule is that if either side of the
4668         // complex number is infinity, then the whole value is
4669         // infinity, even if the other side is NaN.  So the only case
4670         // we have to fix is the one in which both sides are NaN.
4671         if (mpfr_nan_p(real) && mpfr_nan_p(imag)
4672             && (!mpfr_nan_p(left_real) || !mpfr_nan_p(left_imag))
4673             && (!mpfr_nan_p(right_real) || !mpfr_nan_p(right_imag)))
4674           {
4675             bool is_infinity = false;
4676
4677             mpfr_t lr;
4678             mpfr_t li;
4679             mpfr_init_set(lr, left_real, GMP_RNDN);
4680             mpfr_init_set(li, left_imag, GMP_RNDN);
4681
4682             mpfr_t rr;
4683             mpfr_t ri;
4684             mpfr_init_set(rr, right_real, GMP_RNDN);
4685             mpfr_init_set(ri, right_imag, GMP_RNDN);
4686
4687             // If the left side is infinity, then the result is
4688             // infinity.
4689             if (mpfr_inf_p(lr) || mpfr_inf_p(li))
4690               {
4691                 mpfr_set_ui(lr, mpfr_inf_p(lr) ? 1 : 0, GMP_RNDN);
4692                 mpfr_copysign(lr, lr, left_real, GMP_RNDN);
4693                 mpfr_set_ui(li, mpfr_inf_p(li) ? 1 : 0, GMP_RNDN);
4694                 mpfr_copysign(li, li, left_imag, GMP_RNDN);
4695                 if (mpfr_nan_p(rr))
4696                   {
4697                     mpfr_set_ui(rr, 0, GMP_RNDN);
4698                     mpfr_copysign(rr, rr, right_real, GMP_RNDN);
4699                   }
4700                 if (mpfr_nan_p(ri))
4701                   {
4702                     mpfr_set_ui(ri, 0, GMP_RNDN);
4703                     mpfr_copysign(ri, ri, right_imag, GMP_RNDN);
4704                   }
4705                 is_infinity = true;
4706               }
4707
4708             // If the right side is infinity, then the result is
4709             // infinity.
4710             if (mpfr_inf_p(rr) || mpfr_inf_p(ri))
4711               {
4712                 mpfr_set_ui(rr, mpfr_inf_p(rr) ? 1 : 0, GMP_RNDN);
4713                 mpfr_copysign(rr, rr, right_real, GMP_RNDN);
4714                 mpfr_set_ui(ri, mpfr_inf_p(ri) ? 1 : 0, GMP_RNDN);
4715                 mpfr_copysign(ri, ri, right_imag, GMP_RNDN);
4716                 if (mpfr_nan_p(lr))
4717                   {
4718                     mpfr_set_ui(lr, 0, GMP_RNDN);
4719                     mpfr_copysign(lr, lr, left_real, GMP_RNDN);
4720                   }
4721                 if (mpfr_nan_p(li))
4722                   {
4723                     mpfr_set_ui(li, 0, GMP_RNDN);
4724                     mpfr_copysign(li, li, left_imag, GMP_RNDN);
4725                   }
4726                 is_infinity = true;
4727               }
4728
4729             // If we got an overflow in the intermediate computations,
4730             // then the result is infinity.
4731             if (!is_infinity
4732                 && (mpfr_inf_p(lrrr) || mpfr_inf_p(lrri)
4733                     || mpfr_inf_p(lirr) || mpfr_inf_p(liri)))
4734               {
4735                 if (mpfr_nan_p(lr))
4736                   {
4737                     mpfr_set_ui(lr, 0, GMP_RNDN);
4738                     mpfr_copysign(lr, lr, left_real, GMP_RNDN);
4739                   }
4740                 if (mpfr_nan_p(li))
4741                   {
4742                     mpfr_set_ui(li, 0, GMP_RNDN);
4743                     mpfr_copysign(li, li, left_imag, GMP_RNDN);
4744                   }
4745                 if (mpfr_nan_p(rr))
4746                   {
4747                     mpfr_set_ui(rr, 0, GMP_RNDN);
4748                     mpfr_copysign(rr, rr, right_real, GMP_RNDN);
4749                   }
4750                 if (mpfr_nan_p(ri))
4751                   {
4752                     mpfr_set_ui(ri, 0, GMP_RNDN);
4753                     mpfr_copysign(ri, ri, right_imag, GMP_RNDN);
4754                   }
4755                 is_infinity = true;
4756               }
4757
4758             if (is_infinity)
4759               {
4760                 mpfr_mul(lrrr, lr, rr, GMP_RNDN);
4761                 mpfr_mul(lrri, lr, ri, GMP_RNDN);
4762                 mpfr_mul(lirr, li, rr, GMP_RNDN);
4763                 mpfr_mul(liri, li, ri, GMP_RNDN);
4764                 mpfr_sub(real, lrrr, liri, GMP_RNDN);
4765                 mpfr_add(imag, lrri, lirr, GMP_RNDN);
4766                 mpfr_set_inf(real, mpfr_sgn(real));
4767                 mpfr_set_inf(imag, mpfr_sgn(imag));
4768               }
4769
4770             mpfr_clear(lr);
4771             mpfr_clear(li);
4772             mpfr_clear(rr);
4773             mpfr_clear(ri);
4774           }
4775
4776         mpfr_clear(lrrr);
4777         mpfr_clear(lrri);
4778         mpfr_clear(lirr);
4779         mpfr_clear(liri);
4780       }
4781       break;
4782     case OPERATOR_DIV:
4783       {
4784         // For complex division we want to avoid having an
4785         // intermediate overflow turn the whole result in a NaN.  We
4786         // scale the values to try to avoid this.
4787
4788         if (mpfr_zero_p(right_real) && mpfr_zero_p(right_imag))
4789           error_at(location, "division by zero");
4790
4791         mpfr_t rra;
4792         mpfr_t ria;
4793         mpfr_init(rra);
4794         mpfr_init(ria);
4795         mpfr_abs(rra, right_real, GMP_RNDN);
4796         mpfr_abs(ria, right_imag, GMP_RNDN);
4797         mpfr_t t;
4798         mpfr_init(t);
4799         mpfr_max(t, rra, ria, GMP_RNDN);
4800
4801         mpfr_t rr;
4802         mpfr_t ri;
4803         mpfr_init_set(rr, right_real, GMP_RNDN);
4804         mpfr_init_set(ri, right_imag, GMP_RNDN);
4805         long ilogbw = 0;
4806         if (!mpfr_inf_p(t) && !mpfr_nan_p(t) && !mpfr_zero_p(t))
4807           {
4808             ilogbw = mpfr_get_exp(t);
4809             mpfr_mul_2si(rr, rr, - ilogbw, GMP_RNDN);
4810             mpfr_mul_2si(ri, ri, - ilogbw, GMP_RNDN);
4811           }
4812
4813         mpfr_t denom;
4814         mpfr_init(denom);
4815         mpfr_mul(denom, rr, rr, GMP_RNDN);
4816         mpfr_mul(t, ri, ri, GMP_RNDN);
4817         mpfr_add(denom, denom, t, GMP_RNDN);
4818
4819         mpfr_mul(real, left_real, rr, GMP_RNDN);
4820         mpfr_mul(t, left_imag, ri, GMP_RNDN);
4821         mpfr_add(real, real, t, GMP_RNDN);
4822         mpfr_div(real, real, denom, GMP_RNDN);
4823         mpfr_mul_2si(real, real, - ilogbw, GMP_RNDN);
4824
4825         mpfr_mul(imag, left_imag, rr, GMP_RNDN);
4826         mpfr_mul(t, left_real, ri, GMP_RNDN);
4827         mpfr_sub(imag, imag, t, GMP_RNDN);
4828         mpfr_div(imag, imag, denom, GMP_RNDN);
4829         mpfr_mul_2si(imag, imag, - ilogbw, GMP_RNDN);
4830
4831         // If we wind up with NaN on both sides, check whether we
4832         // should really have infinity.  The rule is that if either
4833         // side of the complex number is infinity, then the whole
4834         // value is infinity, even if the other side is NaN.  So the
4835         // only case we have to fix is the one in which both sides are
4836         // NaN.
4837         if (mpfr_nan_p(real) && mpfr_nan_p(imag)
4838             && (!mpfr_nan_p(left_real) || !mpfr_nan_p(left_imag))
4839             && (!mpfr_nan_p(right_real) || !mpfr_nan_p(right_imag)))
4840           {
4841             if (mpfr_zero_p(denom))
4842               {
4843                 mpfr_set_inf(real, mpfr_sgn(rr));
4844                 mpfr_mul(real, real, left_real, GMP_RNDN);
4845                 mpfr_set_inf(imag, mpfr_sgn(rr));
4846                 mpfr_mul(imag, imag, left_imag, GMP_RNDN);
4847               }
4848             else if ((mpfr_inf_p(left_real) || mpfr_inf_p(left_imag))
4849                      && mpfr_number_p(rr) && mpfr_number_p(ri))
4850               {
4851                 mpfr_set_ui(t, mpfr_inf_p(left_real) ? 1 : 0, GMP_RNDN);
4852                 mpfr_copysign(t, t, left_real, GMP_RNDN);
4853
4854                 mpfr_t t2;
4855                 mpfr_init_set_ui(t2, mpfr_inf_p(left_imag) ? 1 : 0, GMP_RNDN);
4856                 mpfr_copysign(t2, t2, left_imag, GMP_RNDN);
4857
4858                 mpfr_t t3;
4859                 mpfr_init(t3);
4860                 mpfr_mul(t3, t, rr, GMP_RNDN);
4861
4862                 mpfr_t t4;
4863                 mpfr_init(t4);
4864                 mpfr_mul(t4, t2, ri, GMP_RNDN);
4865
4866                 mpfr_add(t3, t3, t4, GMP_RNDN);
4867                 mpfr_set_inf(real, mpfr_sgn(t3));
4868
4869                 mpfr_mul(t3, t2, rr, GMP_RNDN);
4870                 mpfr_mul(t4, t, ri, GMP_RNDN);
4871                 mpfr_sub(t3, t3, t4, GMP_RNDN);
4872                 mpfr_set_inf(imag, mpfr_sgn(t3));
4873
4874                 mpfr_clear(t2);
4875                 mpfr_clear(t3);
4876                 mpfr_clear(t4);
4877               }
4878             else if ((mpfr_inf_p(right_real) || mpfr_inf_p(right_imag))
4879                      && mpfr_number_p(left_real) && mpfr_number_p(left_imag))
4880               {
4881                 mpfr_set_ui(t, mpfr_inf_p(rr) ? 1 : 0, GMP_RNDN);
4882                 mpfr_copysign(t, t, rr, GMP_RNDN);
4883
4884                 mpfr_t t2;
4885                 mpfr_init_set_ui(t2, mpfr_inf_p(ri) ? 1 : 0, GMP_RNDN);
4886                 mpfr_copysign(t2, t2, ri, GMP_RNDN);
4887
4888                 mpfr_t t3;
4889                 mpfr_init(t3);
4890                 mpfr_mul(t3, left_real, t, GMP_RNDN);
4891
4892                 mpfr_t t4;
4893                 mpfr_init(t4);
4894                 mpfr_mul(t4, left_imag, t2, GMP_RNDN);
4895
4896                 mpfr_add(t3, t3, t4, GMP_RNDN);
4897                 mpfr_set_ui(real, 0, GMP_RNDN);
4898                 mpfr_mul(real, real, t3, GMP_RNDN);
4899
4900                 mpfr_mul(t3, left_imag, t, GMP_RNDN);
4901                 mpfr_mul(t4, left_real, t2, GMP_RNDN);
4902                 mpfr_sub(t3, t3, t4, GMP_RNDN);
4903                 mpfr_set_ui(imag, 0, GMP_RNDN);
4904                 mpfr_mul(imag, imag, t3, GMP_RNDN);
4905
4906                 mpfr_clear(t2);
4907                 mpfr_clear(t3);
4908                 mpfr_clear(t4);
4909               }
4910           }
4911
4912         mpfr_clear(denom);
4913         mpfr_clear(rr);
4914         mpfr_clear(ri);
4915         mpfr_clear(t);
4916         mpfr_clear(rra);
4917         mpfr_clear(ria);
4918       }
4919       break;
4920     case OPERATOR_MOD:
4921       return false;
4922     case OPERATOR_LSHIFT:
4923     case OPERATOR_RSHIFT:
4924       return false;
4925     default:
4926       gcc_unreachable();
4927     }
4928
4929   Type* type = left_type;
4930   if (type == NULL)
4931     type = right_type;
4932   else if (type != right_type && right_type != NULL)
4933     {
4934       if (type->is_abstract())
4935         type = right_type;
4936       else if (!right_type->is_abstract())
4937         {
4938           // This looks like a type error which should be diagnosed
4939           // elsewhere.  Don't do anything here, to avoid an unhelpful
4940           // chain of error messages.
4941           return true;
4942         }
4943     }
4944
4945   if (type != NULL && !type->is_abstract())
4946     {
4947       if ((type != left_type
4948            && !Complex_expression::check_constant(left_real, left_imag,
4949                                                   type, location))
4950           || (type != right_type
4951               && !Complex_expression::check_constant(right_real, right_imag,
4952                                                      type, location))
4953           || !Complex_expression::check_constant(real, imag, type,
4954                                                  location))
4955         {
4956           mpfr_set_ui(real, 0, GMP_RNDN);
4957           mpfr_set_ui(imag, 0, GMP_RNDN);
4958         }
4959     }
4960
4961   return true;
4962 }
4963
4964 // Lower a binary expression.  We have to evaluate constant
4965 // expressions now, in order to implement Go's unlimited precision
4966 // constants.
4967
4968 Expression*
4969 Binary_expression::do_lower(Gogo*, Named_object*, int)
4970 {
4971   source_location location = this->location();
4972   Operator op = this->op_;
4973   Expression* left = this->left_;
4974   Expression* right = this->right_;
4975
4976   const bool is_comparison = (op == OPERATOR_EQEQ
4977                               || op == OPERATOR_NOTEQ
4978                               || op == OPERATOR_LT
4979                               || op == OPERATOR_LE
4980                               || op == OPERATOR_GT
4981                               || op == OPERATOR_GE);
4982
4983   // Integer constant expressions.
4984   {
4985     mpz_t left_val;
4986     mpz_init(left_val);
4987     Type* left_type;
4988     mpz_t right_val;
4989     mpz_init(right_val);
4990     Type* right_type;
4991     if (left->integer_constant_value(false, left_val, &left_type)
4992         && right->integer_constant_value(false, right_val, &right_type))
4993       {
4994         Expression* ret = NULL;
4995         if (left_type != right_type
4996             && left_type != NULL
4997             && right_type != NULL
4998             && left_type->base() != right_type->base()
4999             && op != OPERATOR_LSHIFT
5000             && op != OPERATOR_RSHIFT)
5001           {
5002             // May be a type error--let it be diagnosed later.
5003           }
5004         else if (is_comparison)
5005           {
5006             bool b = Binary_expression::compare_integer(op, left_val,
5007                                                         right_val);
5008             ret = Expression::make_cast(Type::lookup_bool_type(),
5009                                         Expression::make_boolean(b, location),
5010                                         location);
5011           }
5012         else
5013           {
5014             mpz_t val;
5015             mpz_init(val);
5016
5017             if (Binary_expression::eval_integer(op, left_type, left_val,
5018                                                 right_type, right_val,
5019                                                 location, val))
5020               {
5021                 gcc_assert(op != OPERATOR_OROR && op != OPERATOR_ANDAND);
5022                 Type* type;
5023                 if (op == OPERATOR_LSHIFT || op == OPERATOR_RSHIFT)
5024                   type = left_type;
5025                 else if (left_type == NULL)
5026                   type = right_type;
5027                 else if (right_type == NULL)
5028                   type = left_type;
5029                 else if (!left_type->is_abstract()
5030                          && left_type->named_type() != NULL)
5031                   type = left_type;
5032                 else if (!right_type->is_abstract()
5033                          && right_type->named_type() != NULL)
5034                   type = right_type;
5035                 else if (!left_type->is_abstract())
5036                   type = left_type;
5037                 else if (!right_type->is_abstract())
5038                   type = right_type;
5039                 else if (left_type->float_type() != NULL)
5040                   type = left_type;
5041                 else if (right_type->float_type() != NULL)
5042                   type = right_type;
5043                 else if (left_type->complex_type() != NULL)
5044                   type = left_type;
5045                 else if (right_type->complex_type() != NULL)
5046                   type = right_type;
5047                 else
5048                   type = left_type;
5049                 ret = Expression::make_integer(&val, type, location);
5050               }
5051
5052             mpz_clear(val);
5053           }
5054
5055         if (ret != NULL)
5056           {
5057             mpz_clear(right_val);
5058             mpz_clear(left_val);
5059             return ret;
5060           }
5061       }
5062     mpz_clear(right_val);
5063     mpz_clear(left_val);
5064   }
5065
5066   // Floating point constant expressions.
5067   {
5068     mpfr_t left_val;
5069     mpfr_init(left_val);
5070     Type* left_type;
5071     mpfr_t right_val;
5072     mpfr_init(right_val);
5073     Type* right_type;
5074     if (left->float_constant_value(left_val, &left_type)
5075         && right->float_constant_value(right_val, &right_type))
5076       {
5077         Expression* ret = NULL;
5078         if (left_type != right_type
5079             && left_type != NULL
5080             && right_type != NULL
5081             && left_type->base() != right_type->base()
5082             && op != OPERATOR_LSHIFT
5083             && op != OPERATOR_RSHIFT)
5084           {
5085             // May be a type error--let it be diagnosed later.
5086           }
5087         else if (is_comparison)
5088           {
5089             bool b = Binary_expression::compare_float(op,
5090                                                       (left_type != NULL
5091                                                        ? left_type
5092                                                        : right_type),
5093                                                       left_val, right_val);
5094             ret = Expression::make_boolean(b, location);
5095           }
5096         else
5097           {
5098             mpfr_t val;
5099             mpfr_init(val);
5100
5101             if (Binary_expression::eval_float(op, left_type, left_val,
5102                                               right_type, right_val, val,
5103                                               location))
5104               {
5105                 gcc_assert(op != OPERATOR_OROR && op != OPERATOR_ANDAND
5106                            && op != OPERATOR_LSHIFT && op != OPERATOR_RSHIFT);
5107                 Type* type;
5108                 if (left_type == NULL)
5109                   type = right_type;
5110                 else if (right_type == NULL)
5111                   type = left_type;
5112                 else if (!left_type->is_abstract()
5113                          && left_type->named_type() != NULL)
5114                   type = left_type;
5115                 else if (!right_type->is_abstract()
5116                          && right_type->named_type() != NULL)
5117                   type = right_type;
5118                 else if (!left_type->is_abstract())
5119                   type = left_type;
5120                 else if (!right_type->is_abstract())
5121                   type = right_type;
5122                 else if (left_type->float_type() != NULL)
5123                   type = left_type;
5124                 else if (right_type->float_type() != NULL)
5125                   type = right_type;
5126                 else
5127                   type = left_type;
5128                 ret = Expression::make_float(&val, type, location);
5129               }
5130
5131             mpfr_clear(val);
5132           }
5133
5134         if (ret != NULL)
5135           {
5136             mpfr_clear(right_val);
5137             mpfr_clear(left_val);
5138             return ret;
5139           }
5140       }
5141     mpfr_clear(right_val);
5142     mpfr_clear(left_val);
5143   }
5144
5145   // Complex constant expressions.
5146   {
5147     mpfr_t left_real;
5148     mpfr_t left_imag;
5149     mpfr_init(left_real);
5150     mpfr_init(left_imag);
5151     Type* left_type;
5152
5153     mpfr_t right_real;
5154     mpfr_t right_imag;
5155     mpfr_init(right_real);
5156     mpfr_init(right_imag);
5157     Type* right_type;
5158
5159     if (left->complex_constant_value(left_real, left_imag, &left_type)
5160         && right->complex_constant_value(right_real, right_imag, &right_type))
5161       {
5162         Expression* ret = NULL;
5163         if (left_type != right_type
5164             && left_type != NULL
5165             && right_type != NULL
5166             && left_type->base() != right_type->base())
5167           {
5168             // May be a type error--let it be diagnosed later.
5169           }
5170         else if (op == OPERATOR_EQEQ || op == OPERATOR_NOTEQ)
5171           {
5172             bool b = Binary_expression::compare_complex(op,
5173                                                         (left_type != NULL
5174                                                          ? left_type
5175                                                          : right_type),
5176                                                         left_real,
5177                                                         left_imag,
5178                                                         right_real,
5179                                                         right_imag);
5180             ret = Expression::make_boolean(b, location);
5181           }
5182         else
5183           {
5184             mpfr_t real;
5185             mpfr_t imag;
5186             mpfr_init(real);
5187             mpfr_init(imag);
5188
5189             if (Binary_expression::eval_complex(op, left_type,
5190                                                 left_real, left_imag,
5191                                                 right_type,
5192                                                 right_real, right_imag,
5193                                                 real, imag,
5194                                                 location))
5195               {
5196                 gcc_assert(op != OPERATOR_OROR && op != OPERATOR_ANDAND
5197                            && op != OPERATOR_LSHIFT && op != OPERATOR_RSHIFT);
5198                 Type* type;
5199                 if (left_type == NULL)
5200                   type = right_type;
5201                 else if (right_type == NULL)
5202                   type = left_type;
5203                 else if (!left_type->is_abstract()
5204                          && left_type->named_type() != NULL)
5205                   type = left_type;
5206                 else if (!right_type->is_abstract()
5207                          && right_type->named_type() != NULL)
5208                   type = right_type;
5209                 else if (!left_type->is_abstract())
5210                   type = left_type;
5211                 else if (!right_type->is_abstract())
5212                   type = right_type;
5213                 else if (left_type->complex_type() != NULL)
5214                   type = left_type;
5215                 else if (right_type->complex_type() != NULL)
5216                   type = right_type;
5217                 else
5218                   type = left_type;
5219                 ret = Expression::make_complex(&real, &imag, type,
5220                                                location);
5221               }
5222             mpfr_clear(real);
5223             mpfr_clear(imag);
5224           }
5225
5226         if (ret != NULL)
5227           {
5228             mpfr_clear(left_real);
5229             mpfr_clear(left_imag);
5230             mpfr_clear(right_real);
5231             mpfr_clear(right_imag);
5232             return ret;
5233           }
5234       }
5235
5236     mpfr_clear(left_real);
5237     mpfr_clear(left_imag);
5238     mpfr_clear(right_real);
5239     mpfr_clear(right_imag);
5240   }
5241
5242   // String constant expressions.
5243   if (op == OPERATOR_PLUS
5244       && left->type()->is_string_type()
5245       && right->type()->is_string_type())
5246     {
5247       std::string left_string;
5248       std::string right_string;
5249       if (left->string_constant_value(&left_string)
5250           && right->string_constant_value(&right_string))
5251         return Expression::make_string(left_string + right_string, location);
5252     }
5253
5254   return this;
5255 }
5256
5257 // Return the integer constant value, if it has one.
5258
5259 bool
5260 Binary_expression::do_integer_constant_value(bool iota_is_constant, mpz_t val,
5261                                              Type** ptype) const
5262 {
5263   mpz_t left_val;
5264   mpz_init(left_val);
5265   Type* left_type;
5266   if (!this->left_->integer_constant_value(iota_is_constant, left_val,
5267                                            &left_type))
5268     {
5269       mpz_clear(left_val);
5270       return false;
5271     }
5272
5273   mpz_t right_val;
5274   mpz_init(right_val);
5275   Type* right_type;
5276   if (!this->right_->integer_constant_value(iota_is_constant, right_val,
5277                                             &right_type))
5278     {
5279       mpz_clear(right_val);
5280       mpz_clear(left_val);
5281       return false;
5282     }
5283
5284   bool ret;
5285   if (left_type != right_type
5286       && left_type != NULL
5287       && right_type != NULL
5288       && left_type->base() != right_type->base()
5289       && this->op_ != OPERATOR_RSHIFT
5290       && this->op_ != OPERATOR_LSHIFT)
5291     ret = false;
5292   else
5293     ret = Binary_expression::eval_integer(this->op_, left_type, left_val,
5294                                           right_type, right_val,
5295                                           this->location(), val);
5296
5297   mpz_clear(right_val);
5298   mpz_clear(left_val);
5299
5300   if (ret)
5301     *ptype = left_type;
5302
5303   return ret;
5304 }
5305
5306 // Return the floating point constant value, if it has one.
5307
5308 bool
5309 Binary_expression::do_float_constant_value(mpfr_t val, Type** ptype) const
5310 {
5311   mpfr_t left_val;
5312   mpfr_init(left_val);
5313   Type* left_type;
5314   if (!this->left_->float_constant_value(left_val, &left_type))
5315     {
5316       mpfr_clear(left_val);
5317       return false;
5318     }
5319
5320   mpfr_t right_val;
5321   mpfr_init(right_val);
5322   Type* right_type;
5323   if (!this->right_->float_constant_value(right_val, &right_type))
5324     {
5325       mpfr_clear(right_val);
5326       mpfr_clear(left_val);
5327       return false;
5328     }
5329
5330   bool ret;
5331   if (left_type != right_type
5332       && left_type != NULL
5333       && right_type != NULL
5334       && left_type->base() != right_type->base())
5335     ret = false;
5336   else
5337     ret = Binary_expression::eval_float(this->op_, left_type, left_val,
5338                                         right_type, right_val,
5339                                         val, this->location());
5340
5341   mpfr_clear(left_val);
5342   mpfr_clear(right_val);
5343
5344   if (ret)
5345     *ptype = left_type;
5346
5347   return ret;
5348 }
5349
5350 // Return the complex constant value, if it has one.
5351
5352 bool
5353 Binary_expression::do_complex_constant_value(mpfr_t real, mpfr_t imag,
5354                                              Type** ptype) const
5355 {
5356   mpfr_t left_real;
5357   mpfr_t left_imag;
5358   mpfr_init(left_real);
5359   mpfr_init(left_imag);
5360   Type* left_type;
5361   if (!this->left_->complex_constant_value(left_real, left_imag, &left_type))
5362     {
5363       mpfr_clear(left_real);
5364       mpfr_clear(left_imag);
5365       return false;
5366     }
5367
5368   mpfr_t right_real;
5369   mpfr_t right_imag;
5370   mpfr_init(right_real);
5371   mpfr_init(right_imag);
5372   Type* right_type;
5373   if (!this->right_->complex_constant_value(right_real, right_imag,
5374                                             &right_type))
5375     {
5376       mpfr_clear(left_real);
5377       mpfr_clear(left_imag);
5378       mpfr_clear(right_real);
5379       mpfr_clear(right_imag);
5380       return false;
5381     }
5382
5383   bool ret;
5384   if (left_type != right_type
5385       && left_type != NULL
5386       && right_type != NULL
5387       && left_type->base() != right_type->base())
5388     ret = false;
5389   else
5390     ret = Binary_expression::eval_complex(this->op_, left_type,
5391                                           left_real, left_imag,
5392                                           right_type,
5393                                           right_real, right_imag,
5394                                           real, imag,
5395                                           this->location());
5396   mpfr_clear(left_real);
5397   mpfr_clear(left_imag);
5398   mpfr_clear(right_real);
5399   mpfr_clear(right_imag);
5400
5401   if (ret)
5402     *ptype = left_type;
5403
5404   return ret;
5405 }
5406
5407 // Note that the value is being discarded.
5408
5409 void
5410 Binary_expression::do_discarding_value()
5411 {
5412   if (this->op_ == OPERATOR_OROR || this->op_ == OPERATOR_ANDAND)
5413     this->right_->discarding_value();
5414   else
5415     this->warn_about_unused_value();
5416 }
5417
5418 // Get type.
5419
5420 Type*
5421 Binary_expression::do_type()
5422 {
5423   if (this->classification() == EXPRESSION_ERROR)
5424     return Type::make_error_type();
5425
5426   switch (this->op_)
5427     {
5428     case OPERATOR_OROR:
5429     case OPERATOR_ANDAND:
5430     case OPERATOR_EQEQ:
5431     case OPERATOR_NOTEQ:
5432     case OPERATOR_LT:
5433     case OPERATOR_LE:
5434     case OPERATOR_GT:
5435     case OPERATOR_GE:
5436       return Type::lookup_bool_type();
5437
5438     case OPERATOR_PLUS:
5439     case OPERATOR_MINUS:
5440     case OPERATOR_OR:
5441     case OPERATOR_XOR:
5442     case OPERATOR_MULT:
5443     case OPERATOR_DIV:
5444     case OPERATOR_MOD:
5445     case OPERATOR_AND:
5446     case OPERATOR_BITCLEAR:
5447       {
5448         Type* left_type = this->left_->type();
5449         Type* right_type = this->right_->type();
5450         if (left_type->is_error_type())
5451           return left_type;
5452         else if (right_type->is_error_type())
5453           return right_type;
5454         else if (!Type::are_compatible_for_binop(left_type, right_type))
5455           {
5456             this->report_error(_("incompatible types in binary expression"));
5457             return Type::make_error_type();
5458           }
5459         else if (!left_type->is_abstract() && left_type->named_type() != NULL)
5460           return left_type;
5461         else if (!right_type->is_abstract() && right_type->named_type() != NULL)
5462           return right_type;
5463         else if (!left_type->is_abstract())
5464           return left_type;
5465         else if (!right_type->is_abstract())
5466           return right_type;
5467         else if (left_type->complex_type() != NULL)
5468           return left_type;
5469         else if (right_type->complex_type() != NULL)
5470           return right_type;
5471         else if (left_type->float_type() != NULL)
5472           return left_type;
5473         else if (right_type->float_type() != NULL)
5474           return right_type;
5475         else
5476           return left_type;
5477       }
5478
5479     case OPERATOR_LSHIFT:
5480     case OPERATOR_RSHIFT:
5481       return this->left_->type();
5482
5483     default:
5484       gcc_unreachable();
5485     }
5486 }
5487
5488 // Set type for a binary expression.
5489
5490 void
5491 Binary_expression::do_determine_type(const Type_context* context)
5492 {
5493   Type* tleft = this->left_->type();
5494   Type* tright = this->right_->type();
5495
5496   // Both sides should have the same type, except for the shift
5497   // operations.  For a comparison, we should ignore the incoming
5498   // type.
5499
5500   bool is_shift_op = (this->op_ == OPERATOR_LSHIFT
5501                       || this->op_ == OPERATOR_RSHIFT);
5502
5503   bool is_comparison = (this->op_ == OPERATOR_EQEQ
5504                         || this->op_ == OPERATOR_NOTEQ
5505                         || this->op_ == OPERATOR_LT
5506                         || this->op_ == OPERATOR_LE
5507                         || this->op_ == OPERATOR_GT
5508                         || this->op_ == OPERATOR_GE);
5509
5510   Type_context subcontext(*context);
5511
5512   if (is_comparison)
5513     {
5514       // In a comparison, the context does not determine the types of
5515       // the operands.
5516       subcontext.type = NULL;
5517     }
5518
5519   // Set the context for the left hand operand.
5520   if (is_shift_op)
5521     {
5522       // The right hand operand plays no role in determining the type
5523       // of the left hand operand.  A shift of an abstract integer in
5524       // a string context gets special treatment, which may be a
5525       // language bug.
5526       if (subcontext.type != NULL
5527           && subcontext.type->is_string_type()
5528           && tleft->is_abstract())
5529         error_at(this->location(), "shift of non-integer operand");
5530     }
5531   else if (!tleft->is_abstract())
5532     subcontext.type = tleft;
5533   else if (!tright->is_abstract())
5534     subcontext.type = tright;
5535   else if (subcontext.type == NULL)
5536     {
5537       if ((tleft->integer_type() != NULL && tright->integer_type() != NULL)
5538           || (tleft->float_type() != NULL && tright->float_type() != NULL)
5539           || (tleft->complex_type() != NULL && tright->complex_type() != NULL))
5540         {
5541           // Both sides have an abstract integer, abstract float, or
5542           // abstract complex type.  Just let CONTEXT determine
5543           // whether they may remain abstract or not.
5544         }
5545       else if (tleft->complex_type() != NULL)
5546         subcontext.type = tleft;
5547       else if (tright->complex_type() != NULL)
5548         subcontext.type = tright;
5549       else if (tleft->float_type() != NULL)
5550         subcontext.type = tleft;
5551       else if (tright->float_type() != NULL)
5552         subcontext.type = tright;
5553       else
5554         subcontext.type = tleft;
5555
5556       if (subcontext.type != NULL && !context->may_be_abstract)
5557         subcontext.type = subcontext.type->make_non_abstract_type();
5558     }
5559
5560   this->left_->determine_type(&subcontext);
5561
5562   // The context for the right hand operand is the same as for the
5563   // left hand operand, except for a shift operator.
5564   if (is_shift_op)
5565     {
5566       subcontext.type = Type::lookup_integer_type("uint");
5567       subcontext.may_be_abstract = false;
5568     }
5569
5570   this->right_->determine_type(&subcontext);
5571 }
5572
5573 // Report an error if the binary operator OP does not support TYPE.
5574 // Return whether the operation is OK.  This should not be used for
5575 // shift.
5576
5577 bool
5578 Binary_expression::check_operator_type(Operator op, Type* type,
5579                                        source_location location)
5580 {
5581   switch (op)
5582     {
5583     case OPERATOR_OROR:
5584     case OPERATOR_ANDAND:
5585       if (!type->is_boolean_type())
5586         {
5587           error_at(location, "expected boolean type");
5588           return false;
5589         }
5590       break;
5591
5592     case OPERATOR_EQEQ:
5593     case OPERATOR_NOTEQ:
5594       if (type->integer_type() == NULL
5595           && type->float_type() == NULL
5596           && type->complex_type() == NULL
5597           && !type->is_string_type()
5598           && type->points_to() == NULL
5599           && !type->is_nil_type()
5600           && !type->is_boolean_type()
5601           && type->interface_type() == NULL
5602           && (type->array_type() == NULL
5603               || type->array_type()->length() != NULL)
5604           && type->map_type() == NULL
5605           && type->channel_type() == NULL
5606           && type->function_type() == NULL)
5607         {
5608           error_at(location,
5609                    ("expected integer, floating, complex, string, pointer, "
5610                     "boolean, interface, slice, map, channel, "
5611                     "or function type"));
5612           return false;
5613         }
5614       break;
5615
5616     case OPERATOR_LT:
5617     case OPERATOR_LE:
5618     case OPERATOR_GT:
5619     case OPERATOR_GE:
5620       if (type->integer_type() == NULL
5621           && type->float_type() == NULL
5622           && !type->is_string_type())
5623         {
5624           error_at(location, "expected integer, floating, or string type");
5625           return false;
5626         }
5627       break;
5628
5629     case OPERATOR_PLUS:
5630     case OPERATOR_PLUSEQ:
5631       if (type->integer_type() == NULL
5632           && type->float_type() == NULL
5633           && type->complex_type() == NULL
5634           && !type->is_string_type())
5635         {
5636           error_at(location,
5637                    "expected integer, floating, complex, or string type");
5638           return false;
5639         }
5640       break;
5641
5642     case OPERATOR_MINUS:
5643     case OPERATOR_MINUSEQ:
5644     case OPERATOR_MULT:
5645     case OPERATOR_MULTEQ:
5646     case OPERATOR_DIV:
5647     case OPERATOR_DIVEQ:
5648       if (type->integer_type() == NULL
5649           && type->float_type() == NULL
5650           && type->complex_type() == NULL)
5651         {
5652           error_at(location, "expected integer, floating, or complex type");
5653           return false;
5654         }
5655       break;
5656
5657     case OPERATOR_MOD:
5658     case OPERATOR_MODEQ:
5659     case OPERATOR_OR:
5660     case OPERATOR_OREQ:
5661     case OPERATOR_AND:
5662     case OPERATOR_ANDEQ:
5663     case OPERATOR_XOR:
5664     case OPERATOR_XOREQ:
5665     case OPERATOR_BITCLEAR:
5666     case OPERATOR_BITCLEAREQ:
5667       if (type->integer_type() == NULL)
5668         {
5669           error_at(location, "expected integer type");
5670           return false;
5671         }
5672       break;
5673
5674     default:
5675       gcc_unreachable();
5676     }
5677
5678   return true;
5679 }
5680
5681 // Check types.
5682
5683 void
5684 Binary_expression::do_check_types(Gogo*)
5685 {
5686   if (this->classification() == EXPRESSION_ERROR)
5687     return;
5688
5689   Type* left_type = this->left_->type();
5690   Type* right_type = this->right_->type();
5691   if (left_type->is_error_type() || right_type->is_error_type())
5692     {
5693       this->set_is_error();
5694       return;
5695     }
5696
5697   if (this->op_ == OPERATOR_EQEQ
5698       || this->op_ == OPERATOR_NOTEQ
5699       || this->op_ == OPERATOR_LT
5700       || this->op_ == OPERATOR_LE
5701       || this->op_ == OPERATOR_GT
5702       || this->op_ == OPERATOR_GE)
5703     {
5704       if (!Type::are_assignable(left_type, right_type, NULL)
5705           && !Type::are_assignable(right_type, left_type, NULL))
5706         {
5707           this->report_error(_("incompatible types in binary expression"));
5708           return;
5709         }
5710       if (!Binary_expression::check_operator_type(this->op_, left_type,
5711                                                   this->location())
5712           || !Binary_expression::check_operator_type(this->op_, right_type,
5713                                                      this->location()))
5714         {
5715           this->set_is_error();
5716           return;
5717         }
5718     }
5719   else if (this->op_ != OPERATOR_LSHIFT && this->op_ != OPERATOR_RSHIFT)
5720     {
5721       if (!Type::are_compatible_for_binop(left_type, right_type))
5722         {
5723           this->report_error(_("incompatible types in binary expression"));
5724           return;
5725         }
5726       if (!Binary_expression::check_operator_type(this->op_, left_type,
5727                                                   this->location()))
5728         {
5729           this->set_is_error();
5730           return;
5731         }
5732     }
5733   else
5734     {
5735       if (left_type->integer_type() == NULL)
5736         this->report_error(_("shift of non-integer operand"));
5737
5738       if (!right_type->is_abstract()
5739           && (right_type->integer_type() == NULL
5740               || !right_type->integer_type()->is_unsigned()))
5741         this->report_error(_("shift count not unsigned integer"));
5742       else
5743         {
5744           mpz_t val;
5745           mpz_init(val);
5746           Type* type;
5747           if (this->right_->integer_constant_value(true, val, &type))
5748             {
5749               if (mpz_sgn(val) < 0)
5750                 {
5751                   this->report_error(_("negative shift count"));
5752                   mpz_set_ui(val, 0);
5753                   source_location rloc = this->right_->location();
5754                   this->right_ = Expression::make_integer(&val, right_type,
5755                                                           rloc);
5756                 }
5757             }
5758           mpz_clear(val);
5759         }
5760     }
5761 }
5762
5763 // Get a tree for a binary expression.
5764
5765 tree
5766 Binary_expression::do_get_tree(Translate_context* context)
5767 {
5768   tree left = this->left_->get_tree(context);
5769   tree right = this->right_->get_tree(context);
5770
5771   if (left == error_mark_node || right == error_mark_node)
5772     return error_mark_node;
5773
5774   enum tree_code code;
5775   bool use_left_type = true;
5776   bool is_shift_op = false;
5777   switch (this->op_)
5778     {
5779     case OPERATOR_EQEQ:
5780     case OPERATOR_NOTEQ:
5781     case OPERATOR_LT:
5782     case OPERATOR_LE:
5783     case OPERATOR_GT:
5784     case OPERATOR_GE:
5785       return Expression::comparison_tree(context, this->op_,
5786                                          this->left_->type(), left,
5787                                          this->right_->type(), right,
5788                                          this->location());
5789
5790     case OPERATOR_OROR:
5791       code = TRUTH_ORIF_EXPR;
5792       use_left_type = false;
5793       break;
5794     case OPERATOR_ANDAND:
5795       code = TRUTH_ANDIF_EXPR;
5796       use_left_type = false;
5797       break;
5798     case OPERATOR_PLUS:
5799       code = PLUS_EXPR;
5800       break;
5801     case OPERATOR_MINUS:
5802       code = MINUS_EXPR;
5803       break;
5804     case OPERATOR_OR:
5805       code = BIT_IOR_EXPR;
5806       break;
5807     case OPERATOR_XOR:
5808       code = BIT_XOR_EXPR;
5809       break;
5810     case OPERATOR_MULT:
5811       code = MULT_EXPR;
5812       break;
5813     case OPERATOR_DIV:
5814       {
5815         Type *t = this->left_->type();
5816         if (t->float_type() != NULL || t->complex_type() != NULL)
5817           code = RDIV_EXPR;
5818         else
5819           code = TRUNC_DIV_EXPR;
5820       }
5821       break;
5822     case OPERATOR_MOD:
5823       code = TRUNC_MOD_EXPR;
5824       break;
5825     case OPERATOR_LSHIFT:
5826       code = LSHIFT_EXPR;
5827       is_shift_op = true;
5828       break;
5829     case OPERATOR_RSHIFT:
5830       code = RSHIFT_EXPR;
5831       is_shift_op = true;
5832       break;
5833     case OPERATOR_AND:
5834       code = BIT_AND_EXPR;
5835       break;
5836     case OPERATOR_BITCLEAR:
5837       right = fold_build1(BIT_NOT_EXPR, TREE_TYPE(right), right);
5838       code = BIT_AND_EXPR;
5839       break;
5840     default:
5841       gcc_unreachable();
5842     }
5843
5844   tree type = use_left_type ? TREE_TYPE(left) : TREE_TYPE(right);
5845
5846   if (this->left_->type()->is_string_type())
5847     {
5848       gcc_assert(this->op_ == OPERATOR_PLUS);
5849       tree string_type = Type::make_string_type()->get_tree(context->gogo());
5850       static tree string_plus_decl;
5851       return Gogo::call_builtin(&string_plus_decl,
5852                                 this->location(),
5853                                 "__go_string_plus",
5854                                 2,
5855                                 string_type,
5856                                 string_type,
5857                                 left,
5858                                 string_type,
5859                                 right);
5860     }
5861
5862   tree compute_type = excess_precision_type(type);
5863   if (compute_type != NULL_TREE)
5864     {
5865       left = ::convert(compute_type, left);
5866       right = ::convert(compute_type, right);
5867     }
5868
5869   tree eval_saved = NULL_TREE;
5870   if (is_shift_op)
5871     {
5872       // Make sure the values are evaluated.
5873       if (!DECL_P(left) && TREE_SIDE_EFFECTS(left))
5874         {
5875           left = save_expr(left);
5876           eval_saved = left;
5877         }
5878       if (!DECL_P(right) && TREE_SIDE_EFFECTS(right))
5879         {
5880           right = save_expr(right);
5881           if (eval_saved == NULL_TREE)
5882             eval_saved = right;
5883           else
5884             eval_saved = fold_build2_loc(this->location(), COMPOUND_EXPR,
5885                                          void_type_node, eval_saved, right);
5886         }
5887     }
5888
5889   tree ret = fold_build2_loc(this->location(),
5890                              code,
5891                              compute_type != NULL_TREE ? compute_type : type,
5892                              left, right);
5893
5894   if (compute_type != NULL_TREE)
5895     ret = ::convert(type, ret);
5896
5897   // In Go, a shift larger than the size of the type is well-defined.
5898   // This is not true in GENERIC, so we need to insert a conditional.
5899   if (is_shift_op)
5900     {
5901       gcc_assert(INTEGRAL_TYPE_P(TREE_TYPE(left)));
5902       gcc_assert(this->left_->type()->integer_type() != NULL);
5903       int bits = TYPE_PRECISION(TREE_TYPE(left));
5904
5905       tree compare = fold_build2(LT_EXPR, boolean_type_node, right,
5906                                  build_int_cst_type(TREE_TYPE(right), bits));
5907
5908       tree overflow_result = fold_convert_loc(this->location(),
5909                                               TREE_TYPE(left),
5910                                               integer_zero_node);
5911       if (this->op_ == OPERATOR_RSHIFT
5912           && !this->left_->type()->integer_type()->is_unsigned())
5913         {
5914           tree neg = fold_build2_loc(this->location(), LT_EXPR,
5915                                      boolean_type_node, left,
5916                                      fold_convert_loc(this->location(),
5917                                                       TREE_TYPE(left),
5918                                                       integer_zero_node));
5919           tree neg_one = fold_build2_loc(this->location(),
5920                                          MINUS_EXPR, TREE_TYPE(left),
5921                                          fold_convert_loc(this->location(),
5922                                                           TREE_TYPE(left),
5923                                                           integer_zero_node),
5924                                          fold_convert_loc(this->location(),
5925                                                           TREE_TYPE(left),
5926                                                           integer_one_node));
5927           overflow_result = fold_build3_loc(this->location(), COND_EXPR,
5928                                             TREE_TYPE(left), neg, neg_one,
5929                                             overflow_result);
5930         }
5931
5932       ret = fold_build3_loc(this->location(), COND_EXPR, TREE_TYPE(left),
5933                             compare, ret, overflow_result);
5934
5935       if (eval_saved != NULL_TREE)
5936         ret = fold_build2_loc(this->location(), COMPOUND_EXPR,
5937                               TREE_TYPE(ret), eval_saved, ret);
5938     }
5939
5940   return ret;
5941 }
5942
5943 // Export a binary expression.
5944
5945 void
5946 Binary_expression::do_export(Export* exp) const
5947 {
5948   exp->write_c_string("(");
5949   this->left_->export_expression(exp);
5950   switch (this->op_)
5951     {
5952     case OPERATOR_OROR:
5953       exp->write_c_string(" || ");
5954       break;
5955     case OPERATOR_ANDAND:
5956       exp->write_c_string(" && ");
5957       break;
5958     case OPERATOR_EQEQ:
5959       exp->write_c_string(" == ");
5960       break;
5961     case OPERATOR_NOTEQ:
5962       exp->write_c_string(" != ");
5963       break;
5964     case OPERATOR_LT:
5965       exp->write_c_string(" < ");
5966       break;
5967     case OPERATOR_LE:
5968       exp->write_c_string(" <= ");
5969       break;
5970     case OPERATOR_GT:
5971       exp->write_c_string(" > ");
5972       break;
5973     case OPERATOR_GE:
5974       exp->write_c_string(" >= ");
5975       break;
5976     case OPERATOR_PLUS:
5977       exp->write_c_string(" + ");
5978       break;
5979     case OPERATOR_MINUS:
5980       exp->write_c_string(" - ");
5981       break;
5982     case OPERATOR_OR:
5983       exp->write_c_string(" | ");
5984       break;
5985     case OPERATOR_XOR:
5986       exp->write_c_string(" ^ ");
5987       break;
5988     case OPERATOR_MULT:
5989       exp->write_c_string(" * ");
5990       break;
5991     case OPERATOR_DIV:
5992       exp->write_c_string(" / ");
5993       break;
5994     case OPERATOR_MOD:
5995       exp->write_c_string(" % ");
5996       break;
5997     case OPERATOR_LSHIFT:
5998       exp->write_c_string(" << ");
5999       break;
6000     case OPERATOR_RSHIFT:
6001       exp->write_c_string(" >> ");
6002       break;
6003     case OPERATOR_AND:
6004       exp->write_c_string(" & ");
6005       break;
6006     case OPERATOR_BITCLEAR:
6007       exp->write_c_string(" &^ ");
6008       break;
6009     default:
6010       gcc_unreachable();
6011     }
6012   this->right_->export_expression(exp);
6013   exp->write_c_string(")");
6014 }
6015
6016 // Import a binary expression.
6017
6018 Expression*
6019 Binary_expression::do_import(Import* imp)
6020 {
6021   imp->require_c_string("(");
6022
6023   Expression* left = Expression::import_expression(imp);
6024
6025   Operator op;
6026   if (imp->match_c_string(" || "))
6027     {
6028       op = OPERATOR_OROR;
6029       imp->advance(4);
6030     }
6031   else if (imp->match_c_string(" && "))
6032     {
6033       op = OPERATOR_ANDAND;
6034       imp->advance(4);
6035     }
6036   else if (imp->match_c_string(" == "))
6037     {
6038       op = OPERATOR_EQEQ;
6039       imp->advance(4);
6040     }
6041   else if (imp->match_c_string(" != "))
6042     {
6043       op = OPERATOR_NOTEQ;
6044       imp->advance(4);
6045     }
6046   else if (imp->match_c_string(" < "))
6047     {
6048       op = OPERATOR_LT;
6049       imp->advance(3);
6050     }
6051   else if (imp->match_c_string(" <= "))
6052     {
6053       op = OPERATOR_LE;
6054       imp->advance(4);
6055     }
6056   else if (imp->match_c_string(" > "))
6057     {
6058       op = OPERATOR_GT;
6059       imp->advance(3);
6060     }
6061   else if (imp->match_c_string(" >= "))
6062     {
6063       op = OPERATOR_GE;
6064       imp->advance(4);
6065     }
6066   else if (imp->match_c_string(" + "))
6067     {
6068       op = OPERATOR_PLUS;
6069       imp->advance(3);
6070     }
6071   else if (imp->match_c_string(" - "))
6072     {
6073       op = OPERATOR_MINUS;
6074       imp->advance(3);
6075     }
6076   else if (imp->match_c_string(" | "))
6077     {
6078       op = OPERATOR_OR;
6079       imp->advance(3);
6080     }
6081   else if (imp->match_c_string(" ^ "))
6082     {
6083       op = OPERATOR_XOR;
6084       imp->advance(3);
6085     }
6086   else if (imp->match_c_string(" * "))
6087     {
6088       op = OPERATOR_MULT;
6089       imp->advance(3);
6090     }
6091   else if (imp->match_c_string(" / "))
6092     {
6093       op = OPERATOR_DIV;
6094       imp->advance(3);
6095     }
6096   else if (imp->match_c_string(" % "))
6097     {
6098       op = OPERATOR_MOD;
6099       imp->advance(3);
6100     }
6101   else if (imp->match_c_string(" << "))
6102     {
6103       op = OPERATOR_LSHIFT;
6104       imp->advance(4);
6105     }
6106   else if (imp->match_c_string(" >> "))
6107     {
6108       op = OPERATOR_RSHIFT;
6109       imp->advance(4);
6110     }
6111   else if (imp->match_c_string(" & "))
6112     {
6113       op = OPERATOR_AND;
6114       imp->advance(3);
6115     }
6116   else if (imp->match_c_string(" &^ "))
6117     {
6118       op = OPERATOR_BITCLEAR;
6119       imp->advance(4);
6120     }
6121   else
6122     {
6123       error_at(imp->location(), "unrecognized binary operator");
6124       return Expression::make_error(imp->location());
6125     }
6126
6127   Expression* right = Expression::import_expression(imp);
6128
6129   imp->require_c_string(")");
6130
6131   return Expression::make_binary(op, left, right, imp->location());
6132 }
6133
6134 // Make a binary expression.
6135
6136 Expression*
6137 Expression::make_binary(Operator op, Expression* left, Expression* right,
6138                         source_location location)
6139 {
6140   return new Binary_expression(op, left, right, location);
6141 }
6142
6143 // Implement a comparison.
6144
6145 tree
6146 Expression::comparison_tree(Translate_context* context, Operator op,
6147                             Type* left_type, tree left_tree,
6148                             Type* right_type, tree right_tree,
6149                             source_location location)
6150 {
6151   enum tree_code code;
6152   switch (op)
6153     {
6154     case OPERATOR_EQEQ:
6155       code = EQ_EXPR;
6156       break;
6157     case OPERATOR_NOTEQ:
6158       code = NE_EXPR;
6159       break;
6160     case OPERATOR_LT:
6161       code = LT_EXPR;
6162       break;
6163     case OPERATOR_LE:
6164       code = LE_EXPR;
6165       break;
6166     case OPERATOR_GT:
6167       code = GT_EXPR;
6168       break;
6169     case OPERATOR_GE:
6170       code = GE_EXPR;
6171       break;
6172     default:
6173       gcc_unreachable();
6174     }
6175
6176   if (left_type->is_string_type() && right_type->is_string_type())
6177     {
6178       tree string_type = Type::make_string_type()->get_tree(context->gogo());
6179       static tree string_compare_decl;
6180       left_tree = Gogo::call_builtin(&string_compare_decl,
6181                                      location,
6182                                      "__go_strcmp",
6183                                      2,
6184                                      integer_type_node,
6185                                      string_type,
6186                                      left_tree,
6187                                      string_type,
6188                                      right_tree);
6189       right_tree = build_int_cst_type(integer_type_node, 0);
6190     }
6191   else if ((left_type->interface_type() != NULL
6192             && right_type->interface_type() == NULL
6193             && !right_type->is_nil_type())
6194            || (left_type->interface_type() == NULL
6195                && !left_type->is_nil_type()
6196                && right_type->interface_type() != NULL))
6197     {
6198       // Comparing an interface value to a non-interface value.
6199       if (left_type->interface_type() == NULL)
6200         {
6201           std::swap(left_type, right_type);
6202           std::swap(left_tree, right_tree);
6203         }
6204
6205       // The right operand is not an interface.  We need to take its
6206       // address if it is not a pointer.
6207       tree make_tmp;
6208       tree arg;
6209       if (right_type->points_to() != NULL)
6210         {
6211           make_tmp = NULL_TREE;
6212           arg = right_tree;
6213         }
6214       else if (TREE_ADDRESSABLE(TREE_TYPE(right_tree)) || DECL_P(right_tree))
6215         {
6216           make_tmp = NULL_TREE;
6217           arg = build_fold_addr_expr_loc(location, right_tree);
6218           if (DECL_P(right_tree))
6219             TREE_ADDRESSABLE(right_tree) = 1;
6220         }
6221       else
6222         {
6223           tree tmp = create_tmp_var(TREE_TYPE(right_tree),
6224                                     get_name(right_tree));
6225           DECL_IGNORED_P(tmp) = 0;
6226           DECL_INITIAL(tmp) = right_tree;
6227           TREE_ADDRESSABLE(tmp) = 1;
6228           make_tmp = build1(DECL_EXPR, void_type_node, tmp);
6229           SET_EXPR_LOCATION(make_tmp, location);
6230           arg = build_fold_addr_expr_loc(location, tmp);
6231         }
6232       arg = fold_convert_loc(location, ptr_type_node, arg);
6233
6234       tree descriptor = right_type->type_descriptor_pointer(context->gogo());
6235
6236       if (left_type->interface_type()->is_empty())
6237         {
6238           static tree empty_interface_value_compare_decl;
6239           left_tree = Gogo::call_builtin(&empty_interface_value_compare_decl,
6240                                          location,
6241                                          "__go_empty_interface_value_compare",
6242                                          3,
6243                                          integer_type_node,
6244                                          TREE_TYPE(left_tree),
6245                                          left_tree,
6246                                          TREE_TYPE(descriptor),
6247                                          descriptor,
6248                                          ptr_type_node,
6249                                          arg);
6250           if (left_tree == error_mark_node)
6251             return error_mark_node;
6252           // This can panic if the type is not comparable.
6253           TREE_NOTHROW(empty_interface_value_compare_decl) = 0;
6254         }
6255       else
6256         {
6257           static tree interface_value_compare_decl;
6258           left_tree = Gogo::call_builtin(&interface_value_compare_decl,
6259                                          location,
6260                                          "__go_interface_value_compare",
6261                                          3,
6262                                          integer_type_node,
6263                                          TREE_TYPE(left_tree),
6264                                          left_tree,
6265                                          TREE_TYPE(descriptor),
6266                                          descriptor,
6267                                          ptr_type_node,
6268                                          arg);
6269           if (left_tree == error_mark_node)
6270             return error_mark_node;
6271           // This can panic if the type is not comparable.
6272           TREE_NOTHROW(interface_value_compare_decl) = 0;
6273         }
6274       right_tree = build_int_cst_type(integer_type_node, 0);
6275
6276       if (make_tmp != NULL_TREE)
6277         left_tree = build2(COMPOUND_EXPR, TREE_TYPE(left_tree), make_tmp,
6278                            left_tree);
6279     }
6280   else if (left_type->interface_type() != NULL
6281            && right_type->interface_type() != NULL)
6282     {
6283       if (left_type->interface_type()->is_empty()
6284           && right_type->interface_type()->is_empty())
6285         {
6286           static tree empty_interface_compare_decl;
6287           left_tree = Gogo::call_builtin(&empty_interface_compare_decl,
6288                                          location,
6289                                          "__go_empty_interface_compare",
6290                                          2,
6291                                          integer_type_node,
6292                                          TREE_TYPE(left_tree),
6293                                          left_tree,
6294                                          TREE_TYPE(right_tree),
6295                                          right_tree);
6296           if (left_tree == error_mark_node)
6297             return error_mark_node;
6298           // This can panic if the type is uncomparable.
6299           TREE_NOTHROW(empty_interface_compare_decl) = 0;
6300         }
6301       else if (!left_type->interface_type()->is_empty()
6302                && !right_type->interface_type()->is_empty())
6303         {
6304           static tree interface_compare_decl;
6305           left_tree = Gogo::call_builtin(&interface_compare_decl,
6306                                          location,
6307                                          "__go_interface_compare",
6308                                          2,
6309                                          integer_type_node,
6310                                          TREE_TYPE(left_tree),
6311                                          left_tree,
6312                                          TREE_TYPE(right_tree),
6313                                          right_tree);
6314           if (left_tree == error_mark_node)
6315             return error_mark_node;
6316           // This can panic if the type is uncomparable.
6317           TREE_NOTHROW(interface_compare_decl) = 0;
6318         }
6319       else
6320         {
6321           if (left_type->interface_type()->is_empty())
6322             {
6323               gcc_assert(op == OPERATOR_EQEQ || op == OPERATOR_NOTEQ);
6324               std::swap(left_type, right_type);
6325               std::swap(left_tree, right_tree);
6326             }
6327           gcc_assert(!left_type->interface_type()->is_empty());
6328           gcc_assert(right_type->interface_type()->is_empty());
6329           static tree interface_empty_compare_decl;
6330           left_tree = Gogo::call_builtin(&interface_empty_compare_decl,
6331                                          location,
6332                                          "__go_interface_empty_compare",
6333                                          2,
6334                                          integer_type_node,
6335                                          TREE_TYPE(left_tree),
6336                                          left_tree,
6337                                          TREE_TYPE(right_tree),
6338                                          right_tree);
6339           if (left_tree == error_mark_node)
6340             return error_mark_node;
6341           // This can panic if the type is uncomparable.
6342           TREE_NOTHROW(interface_empty_compare_decl) = 0;
6343         }
6344
6345       right_tree = build_int_cst_type(integer_type_node, 0);
6346     }
6347
6348   if (left_type->is_nil_type()
6349       && (op == OPERATOR_EQEQ || op == OPERATOR_NOTEQ))
6350     {
6351       std::swap(left_type, right_type);
6352       std::swap(left_tree, right_tree);
6353     }
6354
6355   if (right_type->is_nil_type())
6356     {
6357       if (left_type->array_type() != NULL
6358           && left_type->array_type()->length() == NULL)
6359         {
6360           Array_type* at = left_type->array_type();
6361           left_tree = at->value_pointer_tree(context->gogo(), left_tree);
6362           right_tree = fold_convert(TREE_TYPE(left_tree), null_pointer_node);
6363         }
6364       else if (left_type->interface_type() != NULL)
6365         {
6366           // An interface is nil if the first field is nil.
6367           tree left_type_tree = TREE_TYPE(left_tree);
6368           gcc_assert(TREE_CODE(left_type_tree) == RECORD_TYPE);
6369           tree field = TYPE_FIELDS(left_type_tree);
6370           left_tree = build3(COMPONENT_REF, TREE_TYPE(field), left_tree,
6371                              field, NULL_TREE);
6372           right_tree = fold_convert(TREE_TYPE(left_tree), null_pointer_node);
6373         }
6374       else
6375         {
6376           gcc_assert(POINTER_TYPE_P(TREE_TYPE(left_tree)));
6377           right_tree = fold_convert(TREE_TYPE(left_tree), null_pointer_node);
6378         }
6379     }
6380
6381   if (left_tree == error_mark_node || right_tree == error_mark_node)
6382     return error_mark_node;
6383
6384   tree ret = fold_build2(code, boolean_type_node, left_tree, right_tree);
6385   if (CAN_HAVE_LOCATION_P(ret))
6386     SET_EXPR_LOCATION(ret, location);
6387   return ret;
6388 }
6389
6390 // Class Bound_method_expression.
6391
6392 // Traversal.
6393
6394 int
6395 Bound_method_expression::do_traverse(Traverse* traverse)
6396 {
6397   if (Expression::traverse(&this->expr_, traverse) == TRAVERSE_EXIT)
6398     return TRAVERSE_EXIT;
6399   return Expression::traverse(&this->method_, traverse);
6400 }
6401
6402 // Return the type of a bound method expression.  The type of this
6403 // object is really the type of the method with no receiver.  We
6404 // should be able to get away with just returning the type of the
6405 // method.
6406
6407 Type*
6408 Bound_method_expression::do_type()
6409 {
6410   return this->method_->type();
6411 }
6412
6413 // Determine the types of a method expression.
6414
6415 void
6416 Bound_method_expression::do_determine_type(const Type_context*)
6417 {
6418   this->method_->determine_type_no_context();
6419   Type* mtype = this->method_->type();
6420   Function_type* fntype = mtype == NULL ? NULL : mtype->function_type();
6421   if (fntype == NULL || !fntype->is_method())
6422     this->expr_->determine_type_no_context();
6423   else
6424     {
6425       Type_context subcontext(fntype->receiver()->type(), false);
6426       this->expr_->determine_type(&subcontext);
6427     }
6428 }
6429
6430 // Check the types of a method expression.
6431
6432 void
6433 Bound_method_expression::do_check_types(Gogo*)
6434 {
6435   Type* type = this->method_->type()->deref();
6436   if (type == NULL
6437       || type->function_type() == NULL
6438       || !type->function_type()->is_method())
6439     this->report_error(_("object is not a method"));
6440   else
6441     {
6442       Type* rtype = type->function_type()->receiver()->type()->deref();
6443       Type* etype = (this->expr_type_ != NULL
6444                      ? this->expr_type_
6445                      : this->expr_->type());
6446       etype = etype->deref();
6447       if (!Type::are_identical(rtype, etype, true, NULL))
6448         this->report_error(_("method type does not match object type"));
6449     }
6450 }
6451
6452 // Get the tree for a method expression.  There is no standard tree
6453 // representation for this.  The only places it may currently be used
6454 // are in a Call_expression or a Go_statement, which will take it
6455 // apart directly.  So this has nothing to do at present.
6456
6457 tree
6458 Bound_method_expression::do_get_tree(Translate_context*)
6459 {
6460   error_at(this->location(), "reference to method other than calling it");
6461   return error_mark_node;
6462 }
6463
6464 // Make a method expression.
6465
6466 Bound_method_expression*
6467 Expression::make_bound_method(Expression* expr, Expression* method,
6468                               source_location location)
6469 {
6470   return new Bound_method_expression(expr, method, location);
6471 }
6472
6473 // Class Builtin_call_expression.  This is used for a call to a
6474 // builtin function.
6475
6476 class Builtin_call_expression : public Call_expression
6477 {
6478  public:
6479   Builtin_call_expression(Gogo* gogo, Expression* fn, Expression_list* args,
6480                           bool is_varargs, source_location location);
6481
6482  protected:
6483   // This overrides Call_expression::do_lower.
6484   Expression*
6485   do_lower(Gogo*, Named_object*, int);
6486
6487   bool
6488   do_is_constant() const;
6489
6490   bool
6491   do_integer_constant_value(bool, mpz_t, Type**) const;
6492
6493   bool
6494   do_float_constant_value(mpfr_t, Type**) const;
6495
6496   bool
6497   do_complex_constant_value(mpfr_t, mpfr_t, Type**) const;
6498
6499   Type*
6500   do_type();
6501
6502   void
6503   do_determine_type(const Type_context*);
6504
6505   void
6506   do_check_types(Gogo*);
6507
6508   Expression*
6509   do_copy()
6510   {
6511     return new Builtin_call_expression(this->gogo_, this->fn()->copy(),
6512                                        this->args()->copy(),
6513                                        this->is_varargs(),
6514                                        this->location());
6515   }
6516
6517   tree
6518   do_get_tree(Translate_context*);
6519
6520   void
6521   do_export(Export*) const;
6522
6523   virtual bool
6524   do_is_recover_call() const;
6525
6526   virtual void
6527   do_set_recover_arg(Expression*);
6528
6529  private:
6530   // The builtin functions.
6531   enum Builtin_function_code
6532     {
6533       BUILTIN_INVALID,
6534
6535       // Predeclared builtin functions.
6536       BUILTIN_APPEND,
6537       BUILTIN_CAP,
6538       BUILTIN_CLOSE,
6539       BUILTIN_COMPLEX,
6540       BUILTIN_COPY,
6541       BUILTIN_IMAG,
6542       BUILTIN_LEN,
6543       BUILTIN_MAKE,
6544       BUILTIN_NEW,
6545       BUILTIN_PANIC,
6546       BUILTIN_PRINT,
6547       BUILTIN_PRINTLN,
6548       BUILTIN_REAL,
6549       BUILTIN_RECOVER,
6550
6551       // Builtin functions from the unsafe package.
6552       BUILTIN_ALIGNOF,
6553       BUILTIN_OFFSETOF,
6554       BUILTIN_SIZEOF
6555     };
6556
6557   Expression*
6558   one_arg() const;
6559
6560   bool
6561   check_one_arg();
6562
6563   static Type*
6564   real_imag_type(Type*);
6565
6566   static Type*
6567   complex_type(Type*);
6568
6569   // A pointer back to the general IR structure.  This avoids a global
6570   // variable, or passing it around everywhere.
6571   Gogo* gogo_;
6572   // The builtin function being called.
6573   Builtin_function_code code_;
6574   // Used to stop endless loops when the length of an array uses len
6575   // or cap of the array itself.
6576   mutable bool seen_;
6577 };
6578
6579 Builtin_call_expression::Builtin_call_expression(Gogo* gogo,
6580                                                  Expression* fn,
6581                                                  Expression_list* args,
6582                                                  bool is_varargs,
6583                                                  source_location location)
6584   : Call_expression(fn, args, is_varargs, location),
6585     gogo_(gogo), code_(BUILTIN_INVALID), seen_(false)
6586 {
6587   Func_expression* fnexp = this->fn()->func_expression();
6588   gcc_assert(fnexp != NULL);
6589   const std::string& name(fnexp->named_object()->name());
6590   if (name == "append")
6591     this->code_ = BUILTIN_APPEND;
6592   else if (name == "cap")
6593     this->code_ = BUILTIN_CAP;
6594   else if (name == "close")
6595     this->code_ = BUILTIN_CLOSE;
6596   else if (name == "complex")
6597     this->code_ = BUILTIN_COMPLEX;
6598   else if (name == "copy")
6599     this->code_ = BUILTIN_COPY;
6600   else if (name == "imag")
6601     this->code_ = BUILTIN_IMAG;
6602   else if (name == "len")
6603     this->code_ = BUILTIN_LEN;
6604   else if (name == "make")
6605     this->code_ = BUILTIN_MAKE;
6606   else if (name == "new")
6607     this->code_ = BUILTIN_NEW;
6608   else if (name == "panic")
6609     this->code_ = BUILTIN_PANIC;
6610   else if (name == "print")
6611     this->code_ = BUILTIN_PRINT;
6612   else if (name == "println")
6613     this->code_ = BUILTIN_PRINTLN;
6614   else if (name == "real")
6615     this->code_ = BUILTIN_REAL;
6616   else if (name == "recover")
6617     this->code_ = BUILTIN_RECOVER;
6618   else if (name == "Alignof")
6619     this->code_ = BUILTIN_ALIGNOF;
6620   else if (name == "Offsetof")
6621     this->code_ = BUILTIN_OFFSETOF;
6622   else if (name == "Sizeof")
6623     this->code_ = BUILTIN_SIZEOF;
6624   else
6625     gcc_unreachable();
6626 }
6627
6628 // Return whether this is a call to recover.  This is a virtual
6629 // function called from the parent class.
6630
6631 bool
6632 Builtin_call_expression::do_is_recover_call() const
6633 {
6634   if (this->classification() == EXPRESSION_ERROR)
6635     return false;
6636   return this->code_ == BUILTIN_RECOVER;
6637 }
6638
6639 // Set the argument for a call to recover.
6640
6641 void
6642 Builtin_call_expression::do_set_recover_arg(Expression* arg)
6643 {
6644   const Expression_list* args = this->args();
6645   gcc_assert(args == NULL || args->empty());
6646   Expression_list* new_args = new Expression_list();
6647   new_args->push_back(arg);
6648   this->set_args(new_args);
6649 }
6650
6651 // A traversal class which looks for a call expression.
6652
6653 class Find_call_expression : public Traverse
6654 {
6655  public:
6656   Find_call_expression()
6657     : Traverse(traverse_expressions),
6658       found_(false)
6659   { }
6660
6661   int
6662   expression(Expression**);
6663
6664   bool
6665   found()
6666   { return this->found_; }
6667
6668  private:
6669   bool found_;
6670 };
6671
6672 int
6673 Find_call_expression::expression(Expression** pexpr)
6674 {
6675   if ((*pexpr)->call_expression() != NULL)
6676     {
6677       this->found_ = true;
6678       return TRAVERSE_EXIT;
6679     }
6680   return TRAVERSE_CONTINUE;
6681 }
6682
6683 // Lower a builtin call expression.  This turns new and make into
6684 // specific expressions.  We also convert to a constant if we can.
6685
6686 Expression*
6687 Builtin_call_expression::do_lower(Gogo* gogo, Named_object* function, int)
6688 {
6689   if (this->code_ == BUILTIN_NEW)
6690     {
6691       const Expression_list* args = this->args();
6692       if (args == NULL || args->size() < 1)
6693         this->report_error(_("not enough arguments"));
6694       else if (args->size() > 1)
6695         this->report_error(_("too many arguments"));
6696       else
6697         {
6698           Expression* arg = args->front();
6699           if (!arg->is_type_expression())
6700             {
6701               error_at(arg->location(), "expected type");
6702               this->set_is_error();
6703             }
6704           else
6705             return Expression::make_allocation(arg->type(), this->location());
6706         }
6707     }
6708   else if (this->code_ == BUILTIN_MAKE)
6709     {
6710       const Expression_list* args = this->args();
6711       if (args == NULL || args->size() < 1)
6712         this->report_error(_("not enough arguments"));
6713       else
6714         {
6715           Expression* arg = args->front();
6716           if (!arg->is_type_expression())
6717             {
6718               error_at(arg->location(), "expected type");
6719               this->set_is_error();
6720             }
6721           else
6722             {
6723               Expression_list* newargs;
6724               if (args->size() == 1)
6725                 newargs = NULL;
6726               else
6727                 {
6728                   newargs = new Expression_list();
6729                   Expression_list::const_iterator p = args->begin();
6730                   ++p;
6731                   for (; p != args->end(); ++p)
6732                     newargs->push_back(*p);
6733                 }
6734               return Expression::make_make(arg->type(), newargs,
6735                                            this->location());
6736             }
6737         }
6738     }
6739   else if (this->is_constant())
6740     {
6741       // We can only lower len and cap if there are no function calls
6742       // in the arguments.  Otherwise we have to make the call.
6743       if (this->code_ == BUILTIN_LEN || this->code_ == BUILTIN_CAP)
6744         {
6745           Expression* arg = this->one_arg();
6746           if (!arg->is_constant())
6747             {
6748               Find_call_expression find_call;
6749               Expression::traverse(&arg, &find_call);
6750               if (find_call.found())
6751                 return this;
6752             }
6753         }
6754
6755       mpz_t ival;
6756       mpz_init(ival);
6757       Type* type;
6758       if (this->integer_constant_value(true, ival, &type))
6759         {
6760           Expression* ret = Expression::make_integer(&ival, type,
6761                                                      this->location());
6762           mpz_clear(ival);
6763           return ret;
6764         }
6765       mpz_clear(ival);
6766
6767       mpfr_t rval;
6768       mpfr_init(rval);
6769       if (this->float_constant_value(rval, &type))
6770         {
6771           Expression* ret = Expression::make_float(&rval, type,
6772                                                    this->location());
6773           mpfr_clear(rval);
6774           return ret;
6775         }
6776
6777       mpfr_t imag;
6778       mpfr_init(imag);
6779       if (this->complex_constant_value(rval, imag, &type))
6780         {
6781           Expression* ret = Expression::make_complex(&rval, &imag, type,
6782                                                      this->location());
6783           mpfr_clear(rval);
6784           mpfr_clear(imag);
6785           return ret;
6786         }
6787       mpfr_clear(rval);
6788       mpfr_clear(imag);
6789     }
6790   else if (this->code_ == BUILTIN_RECOVER)
6791     {
6792       if (function != NULL)
6793         function->func_value()->set_calls_recover();
6794       else
6795         {
6796           // Calling recover outside of a function always returns the
6797           // nil empty interface.
6798           Type* eface = Type::make_interface_type(NULL, this->location());
6799           return Expression::make_cast(eface,
6800                                        Expression::make_nil(this->location()),
6801                                        this->location());
6802         }
6803     }
6804   else if (this->code_ == BUILTIN_APPEND)
6805     {
6806       // Lower the varargs.
6807       const Expression_list* args = this->args();
6808       if (args == NULL || args->empty())
6809         return this;
6810       Type* slice_type = args->front()->type();
6811       if (!slice_type->is_open_array_type())
6812         {
6813           error_at(args->front()->location(), "argument 1 must be a slice");
6814           this->set_is_error();
6815           return this;
6816         }
6817       return this->lower_varargs(gogo, function, slice_type, 2);
6818     }
6819
6820   return this;
6821 }
6822
6823 // Return the type of the real or imag functions, given the type of
6824 // the argument.  We need to map complex to float, complex64 to
6825 // float32, and complex128 to float64, so it has to be done by name.
6826 // This returns NULL if it can't figure out the type.
6827
6828 Type*
6829 Builtin_call_expression::real_imag_type(Type* arg_type)
6830 {
6831   if (arg_type == NULL || arg_type->is_abstract())
6832     return NULL;
6833   Named_type* nt = arg_type->named_type();
6834   if (nt == NULL)
6835     return NULL;
6836   while (nt->real_type()->named_type() != NULL)
6837     nt = nt->real_type()->named_type();
6838   if (nt->name() == "complex64")
6839     return Type::lookup_float_type("float32");
6840   else if (nt->name() == "complex128")
6841     return Type::lookup_float_type("float64");
6842   else
6843     return NULL;
6844 }
6845
6846 // Return the type of the complex function, given the type of one of the
6847 // argments.  Like real_imag_type, we have to map by name.
6848
6849 Type*
6850 Builtin_call_expression::complex_type(Type* arg_type)
6851 {
6852   if (arg_type == NULL || arg_type->is_abstract())
6853     return NULL;
6854   Named_type* nt = arg_type->named_type();
6855   if (nt == NULL)
6856     return NULL;
6857   while (nt->real_type()->named_type() != NULL)
6858     nt = nt->real_type()->named_type();
6859   if (nt->name() == "float32")
6860     return Type::lookup_complex_type("complex64");
6861   else if (nt->name() == "float64")
6862     return Type::lookup_complex_type("complex128");
6863   else
6864     return NULL;
6865 }
6866
6867 // Return a single argument, or NULL if there isn't one.
6868
6869 Expression*
6870 Builtin_call_expression::one_arg() const
6871 {
6872   const Expression_list* args = this->args();
6873   if (args->size() != 1)
6874     return NULL;
6875   return args->front();
6876 }
6877
6878 // Return whether this is constant: len of a string, or len or cap of
6879 // a fixed array, or unsafe.Sizeof, unsafe.Offsetof, unsafe.Alignof.
6880
6881 bool
6882 Builtin_call_expression::do_is_constant() const
6883 {
6884   switch (this->code_)
6885     {
6886     case BUILTIN_LEN:
6887     case BUILTIN_CAP:
6888       {
6889         if (this->seen_)
6890           return false;
6891
6892         Expression* arg = this->one_arg();
6893         if (arg == NULL)
6894           return false;
6895         Type* arg_type = arg->type();
6896
6897         if (arg_type->points_to() != NULL
6898             && arg_type->points_to()->array_type() != NULL
6899             && !arg_type->points_to()->is_open_array_type())
6900           arg_type = arg_type->points_to();
6901
6902         if (arg_type->array_type() != NULL
6903             && arg_type->array_type()->length() != NULL)
6904           return true;
6905
6906         if (this->code_ == BUILTIN_LEN && arg_type->is_string_type())
6907           {
6908             this->seen_ = true;
6909             bool ret = arg->is_constant();
6910             this->seen_ = false;
6911             return ret;
6912           }
6913       }
6914       break;
6915
6916     case BUILTIN_SIZEOF:
6917     case BUILTIN_ALIGNOF:
6918       return this->one_arg() != NULL;
6919
6920     case BUILTIN_OFFSETOF:
6921       {
6922         Expression* arg = this->one_arg();
6923         if (arg == NULL)
6924           return false;
6925         return arg->field_reference_expression() != NULL;
6926       }
6927
6928     case BUILTIN_COMPLEX:
6929       {
6930         const Expression_list* args = this->args();
6931         if (args != NULL && args->size() == 2)
6932           return args->front()->is_constant() && args->back()->is_constant();
6933       }
6934       break;
6935
6936     case BUILTIN_REAL:
6937     case BUILTIN_IMAG:
6938       {
6939         Expression* arg = this->one_arg();
6940         return arg != NULL && arg->is_constant();
6941       }
6942
6943     default:
6944       break;
6945     }
6946
6947   return false;
6948 }
6949
6950 // Return an integer constant value if possible.
6951
6952 bool
6953 Builtin_call_expression::do_integer_constant_value(bool iota_is_constant,
6954                                                    mpz_t val,
6955                                                    Type** ptype) const
6956 {
6957   if (this->code_ == BUILTIN_LEN
6958       || this->code_ == BUILTIN_CAP)
6959     {
6960       Expression* arg = this->one_arg();
6961       if (arg == NULL)
6962         return false;
6963       Type* arg_type = arg->type();
6964
6965       if (this->code_ == BUILTIN_LEN && arg_type->is_string_type())
6966         {
6967           std::string sval;
6968           if (arg->string_constant_value(&sval))
6969             {
6970               mpz_set_ui(val, sval.length());
6971               *ptype = Type::lookup_integer_type("int");
6972               return true;
6973             }
6974         }
6975
6976       if (arg_type->points_to() != NULL
6977           && arg_type->points_to()->array_type() != NULL
6978           && !arg_type->points_to()->is_open_array_type())
6979         arg_type = arg_type->points_to();
6980
6981       if (arg_type->array_type() != NULL
6982           && arg_type->array_type()->length() != NULL)
6983         {
6984           if (this->seen_)
6985             return false;
6986           Expression* e = arg_type->array_type()->length();
6987           this->seen_ = true;
6988           bool r = e->integer_constant_value(iota_is_constant, val, ptype);
6989           this->seen_ = false;
6990           if (r)
6991             {
6992               *ptype = Type::lookup_integer_type("int");
6993               return true;
6994             }
6995         }
6996     }
6997   else if (this->code_ == BUILTIN_SIZEOF
6998            || this->code_ == BUILTIN_ALIGNOF)
6999     {
7000       Expression* arg = this->one_arg();
7001       if (arg == NULL)
7002         return false;
7003       Type* arg_type = arg->type();
7004       if (arg_type->is_error_type() || arg_type->is_undefined())
7005         return false;
7006       if (arg_type->is_abstract())
7007         return false;
7008       if (arg_type->named_type() != NULL)
7009         arg_type->named_type()->convert(this->gogo_);
7010       tree arg_type_tree = arg_type->get_tree(this->gogo_);
7011       if (arg_type_tree == error_mark_node)
7012         return false;
7013       unsigned long val_long;
7014       if (this->code_ == BUILTIN_SIZEOF)
7015         {
7016           tree type_size = TYPE_SIZE_UNIT(arg_type_tree);
7017           gcc_assert(TREE_CODE(type_size) == INTEGER_CST);
7018           if (TREE_INT_CST_HIGH(type_size) != 0)
7019             return false;
7020           unsigned HOST_WIDE_INT val_wide = TREE_INT_CST_LOW(type_size);
7021           val_long = static_cast<unsigned long>(val_wide);
7022           if (val_long != val_wide)
7023             return false;
7024         }
7025       else if (this->code_ == BUILTIN_ALIGNOF)
7026         {
7027           if (arg->field_reference_expression() == NULL)
7028             val_long = go_type_alignment(arg_type_tree);
7029           else
7030             {
7031               // Calling unsafe.Alignof(s.f) returns the alignment of
7032               // the type of f when it is used as a field in a struct.
7033               val_long = go_field_alignment(arg_type_tree);
7034             }
7035         }
7036       else
7037         gcc_unreachable();
7038       mpz_set_ui(val, val_long);
7039       *ptype = NULL;
7040       return true;
7041     }
7042   else if (this->code_ == BUILTIN_OFFSETOF)
7043     {
7044       Expression* arg = this->one_arg();
7045       if (arg == NULL)
7046         return false;
7047       Field_reference_expression* farg = arg->field_reference_expression();
7048       if (farg == NULL)
7049         return false;
7050       Expression* struct_expr = farg->expr();
7051       Type* st = struct_expr->type();
7052       if (st->struct_type() == NULL)
7053         return false;
7054       if (st->named_type() != NULL)
7055         st->named_type()->convert(this->gogo_);
7056       tree struct_tree = st->get_tree(this->gogo_);
7057       gcc_assert(TREE_CODE(struct_tree) == RECORD_TYPE);
7058       tree field = TYPE_FIELDS(struct_tree);
7059       for (unsigned int index = farg->field_index(); index > 0; --index)
7060         {
7061           field = DECL_CHAIN(field);
7062           gcc_assert(field != NULL_TREE);
7063         }
7064       HOST_WIDE_INT offset_wide = int_byte_position (field);
7065       if (offset_wide < 0)
7066         return false;
7067       unsigned long offset_long = static_cast<unsigned long>(offset_wide);
7068       if (offset_long != static_cast<unsigned HOST_WIDE_INT>(offset_wide))
7069         return false;
7070       mpz_set_ui(val, offset_long);
7071       return true;
7072     }
7073   return false;
7074 }
7075
7076 // Return a floating point constant value if possible.
7077
7078 bool
7079 Builtin_call_expression::do_float_constant_value(mpfr_t val,
7080                                                  Type** ptype) const
7081 {
7082   if (this->code_ == BUILTIN_REAL || this->code_ == BUILTIN_IMAG)
7083     {
7084       Expression* arg = this->one_arg();
7085       if (arg == NULL)
7086         return false;
7087
7088       mpfr_t real;
7089       mpfr_t imag;
7090       mpfr_init(real);
7091       mpfr_init(imag);
7092
7093       bool ret = false;
7094       Type* type;
7095       if (arg->complex_constant_value(real, imag, &type))
7096         {
7097           if (this->code_ == BUILTIN_REAL)
7098             mpfr_set(val, real, GMP_RNDN);
7099           else
7100             mpfr_set(val, imag, GMP_RNDN);
7101           *ptype = Builtin_call_expression::real_imag_type(type);
7102           ret = true;
7103         }
7104
7105       mpfr_clear(real);
7106       mpfr_clear(imag);
7107       return ret;
7108     }
7109
7110   return false;
7111 }
7112
7113 // Return a complex constant value if possible.
7114
7115 bool
7116 Builtin_call_expression::do_complex_constant_value(mpfr_t real, mpfr_t imag,
7117                                                    Type** ptype) const
7118 {
7119   if (this->code_ == BUILTIN_COMPLEX)
7120     {
7121       const Expression_list* args = this->args();
7122       if (args == NULL || args->size() != 2)
7123         return false;
7124
7125       mpfr_t r;
7126       mpfr_init(r);
7127       Type* rtype;
7128       if (!args->front()->float_constant_value(r, &rtype))
7129         {
7130           mpfr_clear(r);
7131           return false;
7132         }
7133
7134       mpfr_t i;
7135       mpfr_init(i);
7136
7137       bool ret = false;
7138       Type* itype;
7139       if (args->back()->float_constant_value(i, &itype)
7140           && Type::are_identical(rtype, itype, false, NULL))
7141         {
7142           mpfr_set(real, r, GMP_RNDN);
7143           mpfr_set(imag, i, GMP_RNDN);
7144           *ptype = Builtin_call_expression::complex_type(rtype);
7145           ret = true;
7146         }
7147
7148       mpfr_clear(r);
7149       mpfr_clear(i);
7150
7151       return ret;
7152     }
7153
7154   return false;
7155 }
7156
7157 // Return the type.
7158
7159 Type*
7160 Builtin_call_expression::do_type()
7161 {
7162   switch (this->code_)
7163     {
7164     case BUILTIN_INVALID:
7165     default:
7166       gcc_unreachable();
7167
7168     case BUILTIN_NEW:
7169     case BUILTIN_MAKE:
7170       {
7171         const Expression_list* args = this->args();
7172         if (args == NULL || args->empty())
7173           return Type::make_error_type();
7174         return Type::make_pointer_type(args->front()->type());
7175       }
7176
7177     case BUILTIN_CAP:
7178     case BUILTIN_COPY:
7179     case BUILTIN_LEN:
7180     case BUILTIN_ALIGNOF:
7181     case BUILTIN_OFFSETOF:
7182     case BUILTIN_SIZEOF:
7183       return Type::lookup_integer_type("int");
7184
7185     case BUILTIN_CLOSE:
7186     case BUILTIN_PANIC:
7187     case BUILTIN_PRINT:
7188     case BUILTIN_PRINTLN:
7189       return Type::make_void_type();
7190
7191     case BUILTIN_RECOVER:
7192       return Type::make_interface_type(NULL, BUILTINS_LOCATION);
7193
7194     case BUILTIN_APPEND:
7195       {
7196         const Expression_list* args = this->args();
7197         if (args == NULL || args->empty())
7198           return Type::make_error_type();
7199         return args->front()->type();
7200       }
7201
7202     case BUILTIN_REAL:
7203     case BUILTIN_IMAG:
7204       {
7205         Expression* arg = this->one_arg();
7206         if (arg == NULL)
7207           return Type::make_error_type();
7208         Type* t = arg->type();
7209         if (t->is_abstract())
7210           t = t->make_non_abstract_type();
7211         t = Builtin_call_expression::real_imag_type(t);
7212         if (t == NULL)
7213           t = Type::make_error_type();
7214         return t;
7215       }
7216
7217     case BUILTIN_COMPLEX:
7218       {
7219         const Expression_list* args = this->args();
7220         if (args == NULL || args->size() != 2)
7221           return Type::make_error_type();
7222         Type* t = args->front()->type();
7223         if (t->is_abstract())
7224           {
7225             t = args->back()->type();
7226             if (t->is_abstract())
7227               t = t->make_non_abstract_type();
7228           }
7229         t = Builtin_call_expression::complex_type(t);
7230         if (t == NULL)
7231           t = Type::make_error_type();
7232         return t;
7233       }
7234     }
7235 }
7236
7237 // Determine the type.
7238
7239 void
7240 Builtin_call_expression::do_determine_type(const Type_context* context)
7241 {
7242   if (!this->determining_types())
7243     return;
7244
7245   this->fn()->determine_type_no_context();
7246
7247   const Expression_list* args = this->args();
7248
7249   bool is_print;
7250   Type* arg_type = NULL;
7251   switch (this->code_)
7252     {
7253     case BUILTIN_PRINT:
7254     case BUILTIN_PRINTLN:
7255       // Do not force a large integer constant to "int".
7256       is_print = true;
7257       break;
7258
7259     case BUILTIN_REAL:
7260     case BUILTIN_IMAG:
7261       arg_type = Builtin_call_expression::complex_type(context->type);
7262       is_print = false;
7263       break;
7264
7265     case BUILTIN_COMPLEX:
7266       {
7267         // For the complex function the type of one operand can
7268         // determine the type of the other, as in a binary expression.
7269         arg_type = Builtin_call_expression::real_imag_type(context->type);
7270         if (args != NULL && args->size() == 2)
7271           {
7272             Type* t1 = args->front()->type();
7273             Type* t2 = args->front()->type();
7274             if (!t1->is_abstract())
7275               arg_type = t1;
7276             else if (!t2->is_abstract())
7277               arg_type = t2;
7278           }
7279         is_print = false;
7280       }
7281       break;
7282
7283     default:
7284       is_print = false;
7285       break;
7286     }
7287
7288   if (args != NULL)
7289     {
7290       for (Expression_list::const_iterator pa = args->begin();
7291            pa != args->end();
7292            ++pa)
7293         {
7294           Type_context subcontext;
7295           subcontext.type = arg_type;
7296
7297           if (is_print)
7298             {
7299               // We want to print large constants, we so can't just
7300               // use the appropriate nonabstract type.  Use uint64 for
7301               // an integer if we know it is nonnegative, otherwise
7302               // use int64 for a integer, otherwise use float64 for a
7303               // float or complex128 for a complex.
7304               Type* want_type = NULL;
7305               Type* atype = (*pa)->type();
7306               if (atype->is_abstract())
7307                 {
7308                   if (atype->integer_type() != NULL)
7309                     {
7310                       mpz_t val;
7311                       mpz_init(val);
7312                       Type* dummy;
7313                       if (this->integer_constant_value(true, val, &dummy)
7314                           && mpz_sgn(val) >= 0)
7315                         want_type = Type::lookup_integer_type("uint64");
7316                       else
7317                         want_type = Type::lookup_integer_type("int64");
7318                       mpz_clear(val);
7319                     }
7320                   else if (atype->float_type() != NULL)
7321                     want_type = Type::lookup_float_type("float64");
7322                   else if (atype->complex_type() != NULL)
7323                     want_type = Type::lookup_complex_type("complex128");
7324                   else if (atype->is_abstract_string_type())
7325                     want_type = Type::lookup_string_type();
7326                   else if (atype->is_abstract_boolean_type())
7327                     want_type = Type::lookup_bool_type();
7328                   else
7329                     gcc_unreachable();
7330                   subcontext.type = want_type;
7331                 }
7332             }
7333
7334           (*pa)->determine_type(&subcontext);
7335         }
7336     }
7337 }
7338
7339 // If there is exactly one argument, return true.  Otherwise give an
7340 // error message and return false.
7341
7342 bool
7343 Builtin_call_expression::check_one_arg()
7344 {
7345   const Expression_list* args = this->args();
7346   if (args == NULL || args->size() < 1)
7347     {
7348       this->report_error(_("not enough arguments"));
7349       return false;
7350     }
7351   else if (args->size() > 1)
7352     {
7353       this->report_error(_("too many arguments"));
7354       return false;
7355     }
7356   if (args->front()->is_error_expression()
7357       || args->front()->type()->is_error_type()
7358       || args->front()->type()->is_undefined())
7359     {
7360       this->set_is_error();
7361       return false;
7362     }
7363   return true;
7364 }
7365
7366 // Check argument types for a builtin function.
7367
7368 void
7369 Builtin_call_expression::do_check_types(Gogo*)
7370 {
7371   switch (this->code_)
7372     {
7373     case BUILTIN_INVALID:
7374     case BUILTIN_NEW:
7375     case BUILTIN_MAKE:
7376       return;
7377
7378     case BUILTIN_LEN:
7379     case BUILTIN_CAP:
7380       {
7381         // The single argument may be either a string or an array or a
7382         // map or a channel, or a pointer to a closed array.
7383         if (this->check_one_arg())
7384           {
7385             Type* arg_type = this->one_arg()->type();
7386             if (arg_type->points_to() != NULL
7387                 && arg_type->points_to()->array_type() != NULL
7388                 && !arg_type->points_to()->is_open_array_type())
7389               arg_type = arg_type->points_to();
7390             if (this->code_ == BUILTIN_CAP)
7391               {
7392                 if (!arg_type->is_error_type()
7393                     && arg_type->array_type() == NULL
7394                     && arg_type->channel_type() == NULL)
7395                   this->report_error(_("argument must be array or slice "
7396                                        "or channel"));
7397               }
7398             else
7399               {
7400                 if (!arg_type->is_error_type()
7401                     && !arg_type->is_string_type()
7402                     && arg_type->array_type() == NULL
7403                     && arg_type->map_type() == NULL
7404                     && arg_type->channel_type() == NULL)
7405                   this->report_error(_("argument must be string or "
7406                                        "array or slice or map or channel"));
7407               }
7408           }
7409       }
7410       break;
7411
7412     case BUILTIN_PRINT:
7413     case BUILTIN_PRINTLN:
7414       {
7415         const Expression_list* args = this->args();
7416         if (args == NULL)
7417           {
7418             if (this->code_ == BUILTIN_PRINT)
7419               warning_at(this->location(), 0,
7420                          "no arguments for builtin function %<%s%>",
7421                          (this->code_ == BUILTIN_PRINT
7422                           ? "print"
7423                           : "println"));
7424           }
7425         else
7426           {
7427             for (Expression_list::const_iterator p = args->begin();
7428                  p != args->end();
7429                  ++p)
7430               {
7431                 Type* type = (*p)->type();
7432                 if (type->is_error_type()
7433                     || type->is_string_type()
7434                     || type->integer_type() != NULL
7435                     || type->float_type() != NULL
7436                     || type->complex_type() != NULL
7437                     || type->is_boolean_type()
7438                     || type->points_to() != NULL
7439                     || type->interface_type() != NULL
7440                     || type->channel_type() != NULL
7441                     || type->map_type() != NULL
7442                     || type->function_type() != NULL
7443                     || type->is_open_array_type())
7444                   ;
7445                 else
7446                   this->report_error(_("unsupported argument type to "
7447                                        "builtin function"));
7448               }
7449           }
7450       }
7451       break;
7452
7453     case BUILTIN_CLOSE:
7454       if (this->check_one_arg())
7455         {
7456           if (this->one_arg()->type()->channel_type() == NULL)
7457             this->report_error(_("argument must be channel"));
7458         }
7459       break;
7460
7461     case BUILTIN_PANIC:
7462     case BUILTIN_SIZEOF:
7463     case BUILTIN_ALIGNOF:
7464       this->check_one_arg();
7465       break;
7466
7467     case BUILTIN_RECOVER:
7468       if (this->args() != NULL && !this->args()->empty())
7469         this->report_error(_("too many arguments"));
7470       break;
7471
7472     case BUILTIN_OFFSETOF:
7473       if (this->check_one_arg())
7474         {
7475           Expression* arg = this->one_arg();
7476           if (arg->field_reference_expression() == NULL)
7477             this->report_error(_("argument must be a field reference"));
7478         }
7479       break;
7480
7481     case BUILTIN_COPY:
7482       {
7483         const Expression_list* args = this->args();
7484         if (args == NULL || args->size() < 2)
7485           {
7486             this->report_error(_("not enough arguments"));
7487             break;
7488           }
7489         else if (args->size() > 2)
7490           {
7491             this->report_error(_("too many arguments"));
7492             break;
7493           }
7494         Type* arg1_type = args->front()->type();
7495         Type* arg2_type = args->back()->type();
7496         if (arg1_type->is_error_type() || arg2_type->is_error_type())
7497           break;
7498
7499         Type* e1;
7500         if (arg1_type->is_open_array_type())
7501           e1 = arg1_type->array_type()->element_type();
7502         else
7503           {
7504             this->report_error(_("left argument must be a slice"));
7505             break;
7506           }
7507
7508         Type* e2;
7509         if (arg2_type->is_open_array_type())
7510           e2 = arg2_type->array_type()->element_type();
7511         else if (arg2_type->is_string_type())
7512           e2 = Type::lookup_integer_type("uint8");
7513         else
7514           {
7515             this->report_error(_("right argument must be a slice or a string"));
7516             break;
7517           }
7518
7519         if (!Type::are_identical(e1, e2, true, NULL))
7520           this->report_error(_("element types must be the same"));
7521       }
7522       break;
7523
7524     case BUILTIN_APPEND:
7525       {
7526         const Expression_list* args = this->args();
7527         if (args == NULL || args->size() < 2)
7528           {
7529             this->report_error(_("not enough arguments"));
7530             break;
7531           }
7532         if (args->size() > 2)
7533           {
7534             this->report_error(_("too many arguments"));
7535             break;
7536           }
7537         std::string reason;
7538         if (!Type::are_assignable(args->front()->type(), args->back()->type(),
7539                                   &reason))
7540           {
7541             if (reason.empty())
7542               this->report_error(_("arguments 1 and 2 have different types"));
7543             else
7544               {
7545                 error_at(this->location(),
7546                          "arguments 1 and 2 have different types (%s)",
7547                          reason.c_str());
7548                 this->set_is_error();
7549               }
7550           }
7551         break;
7552       }
7553
7554     case BUILTIN_REAL:
7555     case BUILTIN_IMAG:
7556       if (this->check_one_arg())
7557         {
7558           if (this->one_arg()->type()->complex_type() == NULL)
7559             this->report_error(_("argument must have complex type"));
7560         }
7561       break;
7562
7563     case BUILTIN_COMPLEX:
7564       {
7565         const Expression_list* args = this->args();
7566         if (args == NULL || args->size() < 2)
7567           this->report_error(_("not enough arguments"));
7568         else if (args->size() > 2)
7569           this->report_error(_("too many arguments"));
7570         else if (args->front()->is_error_expression()
7571                  || args->front()->type()->is_error_type()
7572                  || args->back()->is_error_expression()
7573                  || args->back()->type()->is_error_type())
7574           this->set_is_error();
7575         else if (!Type::are_identical(args->front()->type(),
7576                                       args->back()->type(), true, NULL))
7577           this->report_error(_("complex arguments must have identical types"));
7578         else if (args->front()->type()->float_type() == NULL)
7579           this->report_error(_("complex arguments must have "
7580                                "floating-point type"));
7581       }
7582       break;
7583
7584     default:
7585       gcc_unreachable();
7586     }
7587 }
7588
7589 // Return the tree for a builtin function.
7590
7591 tree
7592 Builtin_call_expression::do_get_tree(Translate_context* context)
7593 {
7594   Gogo* gogo = context->gogo();
7595   source_location location = this->location();
7596   switch (this->code_)
7597     {
7598     case BUILTIN_INVALID:
7599     case BUILTIN_NEW:
7600     case BUILTIN_MAKE:
7601       gcc_unreachable();
7602
7603     case BUILTIN_LEN:
7604     case BUILTIN_CAP:
7605       {
7606         const Expression_list* args = this->args();
7607         gcc_assert(args != NULL && args->size() == 1);
7608         Expression* arg = *args->begin();
7609         Type* arg_type = arg->type();
7610
7611         if (this->seen_)
7612           {
7613             gcc_assert(saw_errors());
7614             return error_mark_node;
7615           }
7616         this->seen_ = true;
7617
7618         tree arg_tree = arg->get_tree(context);
7619
7620         this->seen_ = false;
7621
7622         if (arg_tree == error_mark_node)
7623           return error_mark_node;
7624
7625         if (arg_type->points_to() != NULL)
7626           {
7627             arg_type = arg_type->points_to();
7628             gcc_assert(arg_type->array_type() != NULL
7629                        && !arg_type->is_open_array_type());
7630             gcc_assert(POINTER_TYPE_P(TREE_TYPE(arg_tree)));
7631             arg_tree = build_fold_indirect_ref(arg_tree);
7632           }
7633
7634         tree val_tree;
7635         if (this->code_ == BUILTIN_LEN)
7636           {
7637             if (arg_type->is_string_type())
7638               val_tree = String_type::length_tree(gogo, arg_tree);
7639             else if (arg_type->array_type() != NULL)
7640               {
7641                 if (this->seen_)
7642                   {
7643                     gcc_assert(saw_errors());
7644                     return error_mark_node;
7645                   }
7646                 this->seen_ = true;
7647                 val_tree = arg_type->array_type()->length_tree(gogo, arg_tree);
7648                 this->seen_ = false;
7649               }
7650             else if (arg_type->map_type() != NULL)
7651               {
7652                 static tree map_len_fndecl;
7653                 val_tree = Gogo::call_builtin(&map_len_fndecl,
7654                                               location,
7655                                               "__go_map_len",
7656                                               1,
7657                                               sizetype,
7658                                               arg_type->get_tree(gogo),
7659                                               arg_tree);
7660               }
7661             else if (arg_type->channel_type() != NULL)
7662               {
7663                 static tree chan_len_fndecl;
7664                 val_tree = Gogo::call_builtin(&chan_len_fndecl,
7665                                               location,
7666                                               "__go_chan_len",
7667                                               1,
7668                                               sizetype,
7669                                               arg_type->get_tree(gogo),
7670                                               arg_tree);
7671               }
7672             else
7673               gcc_unreachable();
7674           }
7675         else
7676           {
7677             if (arg_type->array_type() != NULL)
7678               {
7679                 if (this->seen_)
7680                   {
7681                     gcc_assert(saw_errors());
7682                     return error_mark_node;
7683                   }
7684                 this->seen_ = true;
7685                 val_tree = arg_type->array_type()->capacity_tree(gogo,
7686                                                                  arg_tree);
7687                 this->seen_ = false;
7688               }
7689             else if (arg_type->channel_type() != NULL)
7690               {
7691                 static tree chan_cap_fndecl;
7692                 val_tree = Gogo::call_builtin(&chan_cap_fndecl,
7693                                               location,
7694                                               "__go_chan_cap",
7695                                               1,
7696                                               sizetype,
7697                                               arg_type->get_tree(gogo),
7698                                               arg_tree);
7699               }
7700             else
7701               gcc_unreachable();
7702           }
7703
7704         if (val_tree == error_mark_node)
7705           return error_mark_node;
7706
7707         tree type_tree = Type::lookup_integer_type("int")->get_tree(gogo);
7708         if (type_tree == TREE_TYPE(val_tree))
7709           return val_tree;
7710         else
7711           return fold(convert_to_integer(type_tree, val_tree));
7712       }
7713
7714     case BUILTIN_PRINT:
7715     case BUILTIN_PRINTLN:
7716       {
7717         const bool is_ln = this->code_ == BUILTIN_PRINTLN;
7718         tree stmt_list = NULL_TREE;
7719
7720         const Expression_list* call_args = this->args();
7721         if (call_args != NULL)
7722           {
7723             for (Expression_list::const_iterator p = call_args->begin();
7724                  p != call_args->end();
7725                  ++p)
7726               {
7727                 if (is_ln && p != call_args->begin())
7728                   {
7729                     static tree print_space_fndecl;
7730                     tree call = Gogo::call_builtin(&print_space_fndecl,
7731                                                    location,
7732                                                    "__go_print_space",
7733                                                    0,
7734                                                    void_type_node);
7735                     if (call == error_mark_node)
7736                       return error_mark_node;
7737                     append_to_statement_list(call, &stmt_list);
7738                   }
7739
7740                 Type* type = (*p)->type();
7741
7742                 tree arg = (*p)->get_tree(context);
7743                 if (arg == error_mark_node)
7744                   return error_mark_node;
7745
7746                 tree* pfndecl;
7747                 const char* fnname;
7748                 if (type->is_string_type())
7749                   {
7750                     static tree print_string_fndecl;
7751                     pfndecl = &print_string_fndecl;
7752                     fnname = "__go_print_string";
7753                   }
7754                 else if (type->integer_type() != NULL
7755                          && type->integer_type()->is_unsigned())
7756                   {
7757                     static tree print_uint64_fndecl;
7758                     pfndecl = &print_uint64_fndecl;
7759                     fnname = "__go_print_uint64";
7760                     Type* itype = Type::lookup_integer_type("uint64");
7761                     arg = fold_convert_loc(location, itype->get_tree(gogo),
7762                                            arg);
7763                   }
7764                 else if (type->integer_type() != NULL)
7765                   {
7766                     static tree print_int64_fndecl;
7767                     pfndecl = &print_int64_fndecl;
7768                     fnname = "__go_print_int64";
7769                     Type* itype = Type::lookup_integer_type("int64");
7770                     arg = fold_convert_loc(location, itype->get_tree(gogo),
7771                                            arg);
7772                   }
7773                 else if (type->float_type() != NULL)
7774                   {
7775                     static tree print_double_fndecl;
7776                     pfndecl = &print_double_fndecl;
7777                     fnname = "__go_print_double";
7778                     arg = fold_convert_loc(location, double_type_node, arg);
7779                   }
7780                 else if (type->complex_type() != NULL)
7781                   {
7782                     static tree print_complex_fndecl;
7783                     pfndecl = &print_complex_fndecl;
7784                     fnname = "__go_print_complex";
7785                     arg = fold_convert_loc(location, complex_double_type_node,
7786                                            arg);
7787                   }
7788                 else if (type->is_boolean_type())
7789                   {
7790                     static tree print_bool_fndecl;
7791                     pfndecl = &print_bool_fndecl;
7792                     fnname = "__go_print_bool";
7793                   }
7794                 else if (type->points_to() != NULL
7795                          || type->channel_type() != NULL
7796                          || type->map_type() != NULL
7797                          || type->function_type() != NULL)
7798                   {
7799                     static tree print_pointer_fndecl;
7800                     pfndecl = &print_pointer_fndecl;
7801                     fnname = "__go_print_pointer";
7802                     arg = fold_convert_loc(location, ptr_type_node, arg);
7803                   }
7804                 else if (type->interface_type() != NULL)
7805                   {
7806                     if (type->interface_type()->is_empty())
7807                       {
7808                         static tree print_empty_interface_fndecl;
7809                         pfndecl = &print_empty_interface_fndecl;
7810                         fnname = "__go_print_empty_interface";
7811                       }
7812                     else
7813                       {
7814                         static tree print_interface_fndecl;
7815                         pfndecl = &print_interface_fndecl;
7816                         fnname = "__go_print_interface";
7817                       }
7818                   }
7819                 else if (type->is_open_array_type())
7820                   {
7821                     static tree print_slice_fndecl;
7822                     pfndecl = &print_slice_fndecl;
7823                     fnname = "__go_print_slice";
7824                   }
7825                 else
7826                   gcc_unreachable();
7827
7828                 tree call = Gogo::call_builtin(pfndecl,
7829                                                location,
7830                                                fnname,
7831                                                1,
7832                                                void_type_node,
7833                                                TREE_TYPE(arg),
7834                                                arg);
7835                 if (call == error_mark_node)
7836                   return error_mark_node;
7837                 append_to_statement_list(call, &stmt_list);
7838               }
7839           }
7840
7841         if (is_ln)
7842           {
7843             static tree print_nl_fndecl;
7844             tree call = Gogo::call_builtin(&print_nl_fndecl,
7845                                            location,
7846                                            "__go_print_nl",
7847                                            0,
7848                                            void_type_node);
7849             if (call == error_mark_node)
7850               return error_mark_node;
7851             append_to_statement_list(call, &stmt_list);
7852           }
7853
7854         return stmt_list;
7855       }
7856
7857     case BUILTIN_PANIC:
7858       {
7859         const Expression_list* args = this->args();
7860         gcc_assert(args != NULL && args->size() == 1);
7861         Expression* arg = args->front();
7862         tree arg_tree = arg->get_tree(context);
7863         if (arg_tree == error_mark_node)
7864           return error_mark_node;
7865         Type *empty = Type::make_interface_type(NULL, BUILTINS_LOCATION);
7866         arg_tree = Expression::convert_for_assignment(context, empty,
7867                                                       arg->type(),
7868                                                       arg_tree, location);
7869         static tree panic_fndecl;
7870         tree call = Gogo::call_builtin(&panic_fndecl,
7871                                        location,
7872                                        "__go_panic",
7873                                        1,
7874                                        void_type_node,
7875                                        TREE_TYPE(arg_tree),
7876                                        arg_tree);
7877         if (call == error_mark_node)
7878           return error_mark_node;
7879         // This function will throw an exception.
7880         TREE_NOTHROW(panic_fndecl) = 0;
7881         // This function will not return.
7882         TREE_THIS_VOLATILE(panic_fndecl) = 1;
7883         return call;
7884       }
7885
7886     case BUILTIN_RECOVER:
7887       {
7888         // The argument is set when building recover thunks.  It's a
7889         // boolean value which is true if we can recover a value now.
7890         const Expression_list* args = this->args();
7891         gcc_assert(args != NULL && args->size() == 1);
7892         Expression* arg = args->front();
7893         tree arg_tree = arg->get_tree(context);
7894         if (arg_tree == error_mark_node)
7895           return error_mark_node;
7896
7897         Type *empty = Type::make_interface_type(NULL, BUILTINS_LOCATION);
7898         tree empty_tree = empty->get_tree(context->gogo());
7899
7900         Type* nil_type = Type::make_nil_type();
7901         Expression* nil = Expression::make_nil(location);
7902         tree nil_tree = nil->get_tree(context);
7903         tree empty_nil_tree = Expression::convert_for_assignment(context,
7904                                                                  empty,
7905                                                                  nil_type,
7906                                                                  nil_tree,
7907                                                                  location);
7908
7909         // We need to handle a deferred call to recover specially,
7910         // because it changes whether it can recover a panic or not.
7911         // See test7 in test/recover1.go.
7912         tree call;
7913         if (this->is_deferred())
7914           {
7915             static tree deferred_recover_fndecl;
7916             call = Gogo::call_builtin(&deferred_recover_fndecl,
7917                                       location,
7918                                       "__go_deferred_recover",
7919                                       0,
7920                                       empty_tree);
7921           }
7922         else
7923           {
7924             static tree recover_fndecl;
7925             call = Gogo::call_builtin(&recover_fndecl,
7926                                       location,
7927                                       "__go_recover",
7928                                       0,
7929                                       empty_tree);
7930           }
7931         if (call == error_mark_node)
7932           return error_mark_node;
7933         return fold_build3_loc(location, COND_EXPR, empty_tree, arg_tree,
7934                                call, empty_nil_tree);
7935       }
7936
7937     case BUILTIN_CLOSE:
7938       {
7939         const Expression_list* args = this->args();
7940         gcc_assert(args != NULL && args->size() == 1);
7941         Expression* arg = args->front();
7942         tree arg_tree = arg->get_tree(context);
7943         if (arg_tree == error_mark_node)
7944           return error_mark_node;
7945         static tree close_fndecl;
7946         return Gogo::call_builtin(&close_fndecl,
7947                                   location,
7948                                   "__go_builtin_close",
7949                                   1,
7950                                   void_type_node,
7951                                   TREE_TYPE(arg_tree),
7952                                   arg_tree);
7953       }
7954
7955     case BUILTIN_SIZEOF:
7956     case BUILTIN_OFFSETOF:
7957     case BUILTIN_ALIGNOF:
7958       {
7959         mpz_t val;
7960         mpz_init(val);
7961         Type* dummy;
7962         bool b = this->integer_constant_value(true, val, &dummy);
7963         if (!b)
7964           {
7965             gcc_assert(saw_errors());
7966             return error_mark_node;
7967           }
7968         tree type = Type::lookup_integer_type("int")->get_tree(gogo);
7969         tree ret = Expression::integer_constant_tree(val, type);
7970         mpz_clear(val);
7971         return ret;
7972       }
7973
7974     case BUILTIN_COPY:
7975       {
7976         const Expression_list* args = this->args();
7977         gcc_assert(args != NULL && args->size() == 2);
7978         Expression* arg1 = args->front();
7979         Expression* arg2 = args->back();
7980
7981         tree arg1_tree = arg1->get_tree(context);
7982         tree arg2_tree = arg2->get_tree(context);
7983         if (arg1_tree == error_mark_node || arg2_tree == error_mark_node)
7984           return error_mark_node;
7985
7986         Type* arg1_type = arg1->type();
7987         Array_type* at = arg1_type->array_type();
7988         arg1_tree = save_expr(arg1_tree);
7989         tree arg1_val = at->value_pointer_tree(gogo, arg1_tree);
7990         tree arg1_len = at->length_tree(gogo, arg1_tree);
7991         if (arg1_val == error_mark_node || arg1_len == error_mark_node)
7992           return error_mark_node;
7993
7994         Type* arg2_type = arg2->type();
7995         tree arg2_val;
7996         tree arg2_len;
7997         if (arg2_type->is_open_array_type())
7998           {
7999             at = arg2_type->array_type();
8000             arg2_tree = save_expr(arg2_tree);
8001             arg2_val = at->value_pointer_tree(gogo, arg2_tree);
8002             arg2_len = at->length_tree(gogo, arg2_tree);
8003           }
8004         else
8005           {
8006             arg2_tree = save_expr(arg2_tree);
8007             arg2_val = String_type::bytes_tree(gogo, arg2_tree);
8008             arg2_len = String_type::length_tree(gogo, arg2_tree);
8009           }
8010         if (arg2_val == error_mark_node || arg2_len == error_mark_node)
8011           return error_mark_node;
8012
8013         arg1_len = save_expr(arg1_len);
8014         arg2_len = save_expr(arg2_len);
8015         tree len = fold_build3_loc(location, COND_EXPR, TREE_TYPE(arg1_len),
8016                                    fold_build2_loc(location, LT_EXPR,
8017                                                    boolean_type_node,
8018                                                    arg1_len, arg2_len),
8019                                    arg1_len, arg2_len);
8020         len = save_expr(len);
8021
8022         Type* element_type = at->element_type();
8023         tree element_type_tree = element_type->get_tree(gogo);
8024         if (element_type_tree == error_mark_node)
8025           return error_mark_node;
8026         tree element_size = TYPE_SIZE_UNIT(element_type_tree);
8027         tree bytecount = fold_convert_loc(location, TREE_TYPE(element_size),
8028                                           len);
8029         bytecount = fold_build2_loc(location, MULT_EXPR,
8030                                     TREE_TYPE(element_size),
8031                                     bytecount, element_size);
8032         bytecount = fold_convert_loc(location, size_type_node, bytecount);
8033
8034         arg1_val = fold_convert_loc(location, ptr_type_node, arg1_val);
8035         arg2_val = fold_convert_loc(location, ptr_type_node, arg2_val);
8036
8037         static tree copy_fndecl;
8038         tree call = Gogo::call_builtin(&copy_fndecl,
8039                                        location,
8040                                        "__go_copy",
8041                                        3,
8042                                        void_type_node,
8043                                        ptr_type_node,
8044                                        arg1_val,
8045                                        ptr_type_node,
8046                                        arg2_val,
8047                                        size_type_node,
8048                                        bytecount);
8049         if (call == error_mark_node)
8050           return error_mark_node;
8051
8052         return fold_build2_loc(location, COMPOUND_EXPR, TREE_TYPE(len),
8053                                call, len);
8054       }
8055
8056     case BUILTIN_APPEND:
8057       {
8058         const Expression_list* args = this->args();
8059         gcc_assert(args != NULL && args->size() == 2);
8060         Expression* arg1 = args->front();
8061         Expression* arg2 = args->back();
8062
8063         tree arg1_tree = arg1->get_tree(context);
8064         tree arg2_tree = arg2->get_tree(context);
8065         if (arg1_tree == error_mark_node || arg2_tree == error_mark_node)
8066           return error_mark_node;
8067
8068         Array_type* at = arg1->type()->array_type();
8069         Type* element_type = at->element_type();
8070
8071         arg2_tree = Expression::convert_for_assignment(context, at,
8072                                                        arg2->type(),
8073                                                        arg2_tree,
8074                                                        location);
8075         if (arg2_tree == error_mark_node)
8076           return error_mark_node;
8077
8078         arg2_tree = save_expr(arg2_tree);
8079         tree arg2_val = at->value_pointer_tree(gogo, arg2_tree);
8080         tree arg2_len = at->length_tree(gogo, arg2_tree);
8081         if (arg2_val == error_mark_node || arg2_len == error_mark_node)
8082           return error_mark_node;
8083         arg2_val = fold_convert_loc(location, ptr_type_node, arg2_val);
8084         arg2_len = fold_convert_loc(location, size_type_node, arg2_len);
8085
8086         tree element_type_tree = element_type->get_tree(gogo);
8087         if (element_type_tree == error_mark_node)
8088           return error_mark_node;
8089         tree element_size = TYPE_SIZE_UNIT(element_type_tree);
8090         element_size = fold_convert_loc(location, size_type_node,
8091                                         element_size);
8092
8093         // We rebuild the decl each time since the slice types may
8094         // change.
8095         tree append_fndecl = NULL_TREE;
8096         return Gogo::call_builtin(&append_fndecl,
8097                                   location,
8098                                   "__go_append",
8099                                   4,
8100                                   TREE_TYPE(arg1_tree),
8101                                   TREE_TYPE(arg1_tree),
8102                                   arg1_tree,
8103                                   ptr_type_node,
8104                                   arg2_val,
8105                                   size_type_node,
8106                                   arg2_len,
8107                                   size_type_node,
8108                                   element_size);
8109       }
8110
8111     case BUILTIN_REAL:
8112     case BUILTIN_IMAG:
8113       {
8114         const Expression_list* args = this->args();
8115         gcc_assert(args != NULL && args->size() == 1);
8116         Expression* arg = args->front();
8117         tree arg_tree = arg->get_tree(context);
8118         if (arg_tree == error_mark_node)
8119           return error_mark_node;
8120         gcc_assert(COMPLEX_FLOAT_TYPE_P(TREE_TYPE(arg_tree)));
8121         if (this->code_ == BUILTIN_REAL)
8122           return fold_build1_loc(location, REALPART_EXPR,
8123                                  TREE_TYPE(TREE_TYPE(arg_tree)),
8124                                  arg_tree);
8125         else
8126           return fold_build1_loc(location, IMAGPART_EXPR,
8127                                  TREE_TYPE(TREE_TYPE(arg_tree)),
8128                                  arg_tree);
8129       }
8130
8131     case BUILTIN_COMPLEX:
8132       {
8133         const Expression_list* args = this->args();
8134         gcc_assert(args != NULL && args->size() == 2);
8135         tree r = args->front()->get_tree(context);
8136         tree i = args->back()->get_tree(context);
8137         if (r == error_mark_node || i == error_mark_node)
8138           return error_mark_node;
8139         gcc_assert(TYPE_MAIN_VARIANT(TREE_TYPE(r))
8140                    == TYPE_MAIN_VARIANT(TREE_TYPE(i)));
8141         gcc_assert(SCALAR_FLOAT_TYPE_P(TREE_TYPE(r)));
8142         return fold_build2_loc(location, COMPLEX_EXPR,
8143                                build_complex_type(TREE_TYPE(r)),
8144                                r, i);
8145       }
8146
8147     default:
8148       gcc_unreachable();
8149     }
8150 }
8151
8152 // We have to support exporting a builtin call expression, because
8153 // code can set a constant to the result of a builtin expression.
8154
8155 void
8156 Builtin_call_expression::do_export(Export* exp) const
8157 {
8158   bool ok = false;
8159
8160   mpz_t val;
8161   mpz_init(val);
8162   Type* dummy;
8163   if (this->integer_constant_value(true, val, &dummy))
8164     {
8165       Integer_expression::export_integer(exp, val);
8166       ok = true;
8167     }
8168   mpz_clear(val);
8169
8170   if (!ok)
8171     {
8172       mpfr_t fval;
8173       mpfr_init(fval);
8174       if (this->float_constant_value(fval, &dummy))
8175         {
8176           Float_expression::export_float(exp, fval);
8177           ok = true;
8178         }
8179       mpfr_clear(fval);
8180     }
8181
8182   if (!ok)
8183     {
8184       mpfr_t real;
8185       mpfr_t imag;
8186       mpfr_init(real);
8187       mpfr_init(imag);
8188       if (this->complex_constant_value(real, imag, &dummy))
8189         {
8190           Complex_expression::export_complex(exp, real, imag);
8191           ok = true;
8192         }
8193       mpfr_clear(real);
8194       mpfr_clear(imag);
8195     }
8196
8197   if (!ok)
8198     {
8199       error_at(this->location(), "value is not constant");
8200       return;
8201     }
8202
8203   // A trailing space lets us reliably identify the end of the number.
8204   exp->write_c_string(" ");
8205 }
8206
8207 // Class Call_expression.
8208
8209 // Traversal.
8210
8211 int
8212 Call_expression::do_traverse(Traverse* traverse)
8213 {
8214   if (Expression::traverse(&this->fn_, traverse) == TRAVERSE_EXIT)
8215     return TRAVERSE_EXIT;
8216   if (this->args_ != NULL)
8217     {
8218       if (this->args_->traverse(traverse) == TRAVERSE_EXIT)
8219         return TRAVERSE_EXIT;
8220     }
8221   return TRAVERSE_CONTINUE;
8222 }
8223
8224 // Lower a call statement.
8225
8226 Expression*
8227 Call_expression::do_lower(Gogo* gogo, Named_object* function, int)
8228 {
8229   // A type case can look like a function call.
8230   if (this->fn_->is_type_expression()
8231       && this->args_ != NULL
8232       && this->args_->size() == 1)
8233     return Expression::make_cast(this->fn_->type(), this->args_->front(),
8234                                  this->location());
8235
8236   // Recognize a call to a builtin function.
8237   Func_expression* fne = this->fn_->func_expression();
8238   if (fne != NULL
8239       && fne->named_object()->is_function_declaration()
8240       && fne->named_object()->func_declaration_value()->type()->is_builtin())
8241     return new Builtin_call_expression(gogo, this->fn_, this->args_,
8242                                        this->is_varargs_, this->location());
8243
8244   // Handle an argument which is a call to a function which returns
8245   // multiple results.
8246   if (this->args_ != NULL
8247       && this->args_->size() == 1
8248       && this->args_->front()->call_expression() != NULL
8249       && this->fn_->type()->function_type() != NULL)
8250     {
8251       Function_type* fntype = this->fn_->type()->function_type();
8252       size_t rc = this->args_->front()->call_expression()->result_count();
8253       if (rc > 1
8254           && fntype->parameters() != NULL
8255           && (fntype->parameters()->size() == rc
8256               || (fntype->is_varargs()
8257                   && fntype->parameters()->size() - 1 <= rc)))
8258         {
8259           Call_expression* call = this->args_->front()->call_expression();
8260           Expression_list* args = new Expression_list;
8261           for (size_t i = 0; i < rc; ++i)
8262             args->push_back(Expression::make_call_result(call, i));
8263           // We can't return a new call expression here, because this
8264           // one may be referenced by Call_result expressions.  We
8265           // also can't delete the old arguments, because we may still
8266           // traverse them somewhere up the call stack.  FIXME.
8267           this->args_ = args;
8268         }
8269     }
8270
8271   // Handle a call to a varargs function by packaging up the extra
8272   // parameters.
8273   if (this->fn_->type()->function_type() != NULL
8274       && this->fn_->type()->function_type()->is_varargs())
8275     {
8276       Function_type* fntype = this->fn_->type()->function_type();
8277       const Typed_identifier_list* parameters = fntype->parameters();
8278       gcc_assert(parameters != NULL && !parameters->empty());
8279       Type* varargs_type = parameters->back().type();
8280       return this->lower_varargs(gogo, function, varargs_type,
8281                                  parameters->size());
8282     }
8283
8284   return this;
8285 }
8286
8287 // Lower a call to a varargs function.  FUNCTION is the function in
8288 // which the call occurs--it's not the function we are calling.
8289 // VARARGS_TYPE is the type of the varargs parameter, a slice type.
8290 // PARAM_COUNT is the number of parameters of the function we are
8291 // calling; the last of these parameters will be the varargs
8292 // parameter.
8293
8294 Expression*
8295 Call_expression::lower_varargs(Gogo* gogo, Named_object* function,
8296                                Type* varargs_type, size_t param_count)
8297 {
8298   if (this->varargs_are_lowered_)
8299     return this;
8300
8301   source_location loc = this->location();
8302
8303   gcc_assert(param_count > 0);
8304   gcc_assert(varargs_type->is_open_array_type());
8305
8306   size_t arg_count = this->args_ == NULL ? 0 : this->args_->size();
8307   if (arg_count < param_count - 1)
8308     {
8309       // Not enough arguments; will be caught in check_types.
8310       return this;
8311     }
8312
8313   Expression_list* old_args = this->args_;
8314   Expression_list* new_args = new Expression_list();
8315   bool push_empty_arg = false;
8316   if (old_args == NULL || old_args->empty())
8317     {
8318       gcc_assert(param_count == 1);
8319       push_empty_arg = true;
8320     }
8321   else
8322     {
8323       Expression_list::const_iterator pa;
8324       int i = 1;
8325       for (pa = old_args->begin(); pa != old_args->end(); ++pa, ++i)
8326         {
8327           if (static_cast<size_t>(i) == param_count)
8328             break;
8329           new_args->push_back(*pa);
8330         }
8331
8332       // We have reached the varargs parameter.
8333
8334       bool issued_error = false;
8335       if (pa == old_args->end())
8336         push_empty_arg = true;
8337       else if (pa + 1 == old_args->end() && this->is_varargs_)
8338         new_args->push_back(*pa);
8339       else if (this->is_varargs_)
8340         {
8341           this->report_error(_("too many arguments"));
8342           return this;
8343         }
8344       else
8345         {
8346           Type* element_type = varargs_type->array_type()->element_type();
8347           Expression_list* vals = new Expression_list;
8348           for (; pa != old_args->end(); ++pa, ++i)
8349             {
8350               // Check types here so that we get a better message.
8351               Type* patype = (*pa)->type();
8352               source_location paloc = (*pa)->location();
8353               if (!this->check_argument_type(i, element_type, patype,
8354                                              paloc, issued_error))
8355                 continue;
8356               vals->push_back(*pa);
8357             }
8358           Expression* val =
8359             Expression::make_slice_composite_literal(varargs_type, vals, loc);
8360           new_args->push_back(val);
8361         }
8362     }
8363
8364   if (push_empty_arg)
8365     new_args->push_back(Expression::make_nil(loc));
8366
8367   // We can't return a new call expression here, because this one may
8368   // be referenced by Call_result expressions.  FIXME.
8369   if (old_args != NULL)
8370     delete old_args;
8371   this->args_ = new_args;
8372   this->varargs_are_lowered_ = true;
8373
8374   // Lower all the new subexpressions.
8375   Expression* ret = this;
8376   gogo->lower_expression(function, &ret);
8377   gcc_assert(ret == this);
8378   return ret;
8379 }
8380
8381 // Get the function type.  Returns NULL if we don't know the type.  If
8382 // this returns NULL, and if_ERROR is true, issues an error.
8383
8384 Function_type*
8385 Call_expression::get_function_type() const
8386 {
8387   return this->fn_->type()->function_type();
8388 }
8389
8390 // Return the number of values which this call will return.
8391
8392 size_t
8393 Call_expression::result_count() const
8394 {
8395   const Function_type* fntype = this->get_function_type();
8396   if (fntype == NULL)
8397     return 0;
8398   if (fntype->results() == NULL)
8399     return 0;
8400   return fntype->results()->size();
8401 }
8402
8403 // Return whether this is a call to the predeclared function recover.
8404
8405 bool
8406 Call_expression::is_recover_call() const
8407 {
8408   return this->do_is_recover_call();
8409 }
8410
8411 // Set the argument to the recover function.
8412
8413 void
8414 Call_expression::set_recover_arg(Expression* arg)
8415 {
8416   this->do_set_recover_arg(arg);
8417 }
8418
8419 // Virtual functions also implemented by Builtin_call_expression.
8420
8421 bool
8422 Call_expression::do_is_recover_call() const
8423 {
8424   return false;
8425 }
8426
8427 void
8428 Call_expression::do_set_recover_arg(Expression*)
8429 {
8430   gcc_unreachable();
8431 }
8432
8433 // Get the type.
8434
8435 Type*
8436 Call_expression::do_type()
8437 {
8438   if (this->type_ != NULL)
8439     return this->type_;
8440
8441   Type* ret;
8442   Function_type* fntype = this->get_function_type();
8443   if (fntype == NULL)
8444     return Type::make_error_type();
8445
8446   const Typed_identifier_list* results = fntype->results();
8447   if (results == NULL)
8448     ret = Type::make_void_type();
8449   else if (results->size() == 1)
8450     ret = results->begin()->type();
8451   else
8452     ret = Type::make_call_multiple_result_type(this);
8453
8454   this->type_ = ret;
8455
8456   return this->type_;
8457 }
8458
8459 // Determine types for a call expression.  We can use the function
8460 // parameter types to set the types of the arguments.
8461
8462 void
8463 Call_expression::do_determine_type(const Type_context*)
8464 {
8465   if (!this->determining_types())
8466     return;
8467
8468   this->fn_->determine_type_no_context();
8469   Function_type* fntype = this->get_function_type();
8470   const Typed_identifier_list* parameters = NULL;
8471   if (fntype != NULL)
8472     parameters = fntype->parameters();
8473   if (this->args_ != NULL)
8474     {
8475       Typed_identifier_list::const_iterator pt;
8476       if (parameters != NULL)
8477         pt = parameters->begin();
8478       for (Expression_list::const_iterator pa = this->args_->begin();
8479            pa != this->args_->end();
8480            ++pa)
8481         {
8482           if (parameters != NULL && pt != parameters->end())
8483             {
8484               Type_context subcontext(pt->type(), false);
8485               (*pa)->determine_type(&subcontext);
8486               ++pt;
8487             }
8488           else
8489             (*pa)->determine_type_no_context();
8490         }
8491     }
8492 }
8493
8494 // Called when determining types for a Call_expression.  Return true
8495 // if we should go ahead, false if they have already been determined.
8496
8497 bool
8498 Call_expression::determining_types()
8499 {
8500   if (this->types_are_determined_)
8501     return false;
8502   else
8503     {
8504       this->types_are_determined_ = true;
8505       return true;
8506     }
8507 }
8508
8509 // Check types for parameter I.
8510
8511 bool
8512 Call_expression::check_argument_type(int i, const Type* parameter_type,
8513                                      const Type* argument_type,
8514                                      source_location argument_location,
8515                                      bool issued_error)
8516 {
8517   std::string reason;
8518   if (!Type::are_assignable(parameter_type, argument_type, &reason))
8519     {
8520       if (!issued_error)
8521         {
8522           if (reason.empty())
8523             error_at(argument_location, "argument %d has incompatible type", i);
8524           else
8525             error_at(argument_location,
8526                      "argument %d has incompatible type (%s)",
8527                      i, reason.c_str());
8528         }
8529       this->set_is_error();
8530       return false;
8531     }
8532   return true;
8533 }
8534
8535 // Check types.
8536
8537 void
8538 Call_expression::do_check_types(Gogo*)
8539 {
8540   Function_type* fntype = this->get_function_type();
8541   if (fntype == NULL)
8542     {
8543       if (!this->fn_->type()->is_error_type())
8544         this->report_error(_("expected function"));
8545       return;
8546     }
8547
8548   if (fntype->is_method())
8549     {
8550       // We don't support pointers to methods, so the function has to
8551       // be a bound method expression.
8552       Bound_method_expression* bme = this->fn_->bound_method_expression();
8553       if (bme == NULL)
8554         {
8555           this->report_error(_("method call without object"));
8556           return;
8557         }
8558       Type* first_arg_type = bme->first_argument()->type();
8559       if (first_arg_type->points_to() == NULL)
8560         {
8561           // When passing a value, we need to check that we are
8562           // permitted to copy it.
8563           std::string reason;
8564           if (!Type::are_assignable(fntype->receiver()->type(),
8565                                     first_arg_type, &reason))
8566             {
8567               if (reason.empty())
8568                 this->report_error(_("incompatible type for receiver"));
8569               else
8570                 {
8571                   error_at(this->location(),
8572                            "incompatible type for receiver (%s)",
8573                            reason.c_str());
8574                   this->set_is_error();
8575                 }
8576             }
8577         }
8578     }
8579
8580   // Note that varargs was handled by the lower_varargs() method, so
8581   // we don't have to worry about it here.
8582
8583   const Typed_identifier_list* parameters = fntype->parameters();
8584   if (this->args_ == NULL)
8585     {
8586       if (parameters != NULL && !parameters->empty())
8587         this->report_error(_("not enough arguments"));
8588     }
8589   else if (parameters == NULL)
8590     this->report_error(_("too many arguments"));
8591   else
8592     {
8593       int i = 0;
8594       Typed_identifier_list::const_iterator pt = parameters->begin();
8595       for (Expression_list::const_iterator pa = this->args_->begin();
8596            pa != this->args_->end();
8597            ++pa, ++pt, ++i)
8598         {
8599           if (pt == parameters->end())
8600             {
8601               this->report_error(_("too many arguments"));
8602               return;
8603             }
8604           this->check_argument_type(i + 1, pt->type(), (*pa)->type(),
8605                                     (*pa)->location(), false);
8606         }
8607       if (pt != parameters->end())
8608         this->report_error(_("not enough arguments"));
8609     }
8610 }
8611
8612 // Return whether we have to use a temporary variable to ensure that
8613 // we evaluate this call expression in order.  If the call returns no
8614 // results then it will inevitably be executed last.  If the call
8615 // returns more than one result then it will be used with Call_result
8616 // expressions.  So we only have to use a temporary variable if the
8617 // call returns exactly one result.
8618
8619 bool
8620 Call_expression::do_must_eval_in_order() const
8621 {
8622   return this->result_count() == 1;
8623 }
8624
8625 // Get the function and the first argument to use when calling a bound
8626 // method.
8627
8628 tree
8629 Call_expression::bound_method_function(Translate_context* context,
8630                                        Bound_method_expression* bound_method,
8631                                        tree* first_arg_ptr)
8632 {
8633   Expression* first_argument = bound_method->first_argument();
8634   tree first_arg = first_argument->get_tree(context);
8635   if (first_arg == error_mark_node)
8636     return error_mark_node;
8637
8638   // We always pass a pointer to the first argument when calling a
8639   // method.
8640   if (first_argument->type()->points_to() == NULL)
8641     {
8642       tree pointer_to_arg_type = build_pointer_type(TREE_TYPE(first_arg));
8643       if (TREE_ADDRESSABLE(TREE_TYPE(first_arg))
8644           || DECL_P(first_arg)
8645           || TREE_CODE(first_arg) == INDIRECT_REF
8646           || TREE_CODE(first_arg) == COMPONENT_REF)
8647         {
8648           first_arg = build_fold_addr_expr(first_arg);
8649           if (DECL_P(first_arg))
8650             TREE_ADDRESSABLE(first_arg) = 1;
8651         }
8652       else
8653         {
8654           tree tmp = create_tmp_var(TREE_TYPE(first_arg),
8655                                     get_name(first_arg));
8656           DECL_IGNORED_P(tmp) = 0;
8657           DECL_INITIAL(tmp) = first_arg;
8658           first_arg = build2(COMPOUND_EXPR, pointer_to_arg_type,
8659                              build1(DECL_EXPR, void_type_node, tmp),
8660                              build_fold_addr_expr(tmp));
8661           TREE_ADDRESSABLE(tmp) = 1;
8662         }
8663       if (first_arg == error_mark_node)
8664         return error_mark_node;
8665     }
8666
8667   Type* fatype = bound_method->first_argument_type();
8668   if (fatype != NULL)
8669     {
8670       if (fatype->points_to() == NULL)
8671         fatype = Type::make_pointer_type(fatype);
8672       first_arg = fold_convert(fatype->get_tree(context->gogo()), first_arg);
8673       if (first_arg == error_mark_node
8674           || TREE_TYPE(first_arg) == error_mark_node)
8675         return error_mark_node;
8676     }
8677
8678   *first_arg_ptr = first_arg;
8679
8680   return bound_method->method()->get_tree(context);
8681 }
8682
8683 // Get the function and the first argument to use when calling an
8684 // interface method.
8685
8686 tree
8687 Call_expression::interface_method_function(
8688     Translate_context* context,
8689     Interface_field_reference_expression* interface_method,
8690     tree* first_arg_ptr)
8691 {
8692   tree expr = interface_method->expr()->get_tree(context);
8693   if (expr == error_mark_node)
8694     return error_mark_node;
8695   expr = save_expr(expr);
8696   tree first_arg = interface_method->get_underlying_object_tree(context, expr);
8697   if (first_arg == error_mark_node)
8698     return error_mark_node;
8699   *first_arg_ptr = first_arg;
8700   return interface_method->get_function_tree(context, expr);
8701 }
8702
8703 // Build the call expression.
8704
8705 tree
8706 Call_expression::do_get_tree(Translate_context* context)
8707 {
8708   if (this->tree_ != NULL_TREE)
8709     return this->tree_;
8710
8711   Function_type* fntype = this->get_function_type();
8712   if (fntype == NULL)
8713     return error_mark_node;
8714
8715   if (this->fn_->is_error_expression())
8716     return error_mark_node;
8717
8718   Gogo* gogo = context->gogo();
8719   source_location location = this->location();
8720
8721   Func_expression* func = this->fn_->func_expression();
8722   Bound_method_expression* bound_method = this->fn_->bound_method_expression();
8723   Interface_field_reference_expression* interface_method =
8724     this->fn_->interface_field_reference_expression();
8725   const bool has_closure = func != NULL && func->closure() != NULL;
8726   const bool is_method = bound_method != NULL || interface_method != NULL;
8727   gcc_assert(!fntype->is_method() || is_method);
8728
8729   int nargs;
8730   tree* args;
8731   if (this->args_ == NULL || this->args_->empty())
8732     {
8733       nargs = is_method ? 1 : 0;
8734       args = nargs == 0 ? NULL : new tree[nargs];
8735     }
8736   else
8737     {
8738       const Typed_identifier_list* params = fntype->parameters();
8739       gcc_assert(params != NULL);
8740
8741       nargs = this->args_->size();
8742       int i = is_method ? 1 : 0;
8743       nargs += i;
8744       args = new tree[nargs];
8745
8746       Typed_identifier_list::const_iterator pp = params->begin();
8747       Expression_list::const_iterator pe;
8748       for (pe = this->args_->begin();
8749            pe != this->args_->end();
8750            ++pe, ++pp, ++i)
8751         {
8752           gcc_assert(pp != params->end());
8753           tree arg_val = (*pe)->get_tree(context);
8754           args[i] = Expression::convert_for_assignment(context,
8755                                                        pp->type(),
8756                                                        (*pe)->type(),
8757                                                        arg_val,
8758                                                        location);
8759           if (args[i] == error_mark_node)
8760             {
8761               delete[] args;
8762               return error_mark_node;
8763             }
8764         }
8765       gcc_assert(pp == params->end());
8766       gcc_assert(i == nargs);
8767     }
8768
8769   tree rettype = TREE_TYPE(TREE_TYPE(fntype->get_tree(gogo)));
8770   if (rettype == error_mark_node)
8771     {
8772       delete[] args;
8773       return error_mark_node;
8774     }
8775
8776   tree fn;
8777   if (has_closure)
8778     fn = func->get_tree_without_closure(gogo);
8779   else if (!is_method)
8780     fn = this->fn_->get_tree(context);
8781   else if (bound_method != NULL)
8782     fn = this->bound_method_function(context, bound_method, &args[0]);
8783   else if (interface_method != NULL)
8784     fn = this->interface_method_function(context, interface_method, &args[0]);
8785   else
8786     gcc_unreachable();
8787
8788   if (fn == error_mark_node || TREE_TYPE(fn) == error_mark_node)
8789     {
8790       delete[] args;
8791       return error_mark_node;
8792     }
8793
8794   tree fndecl = fn;
8795   if (TREE_CODE(fndecl) == ADDR_EXPR)
8796     fndecl = TREE_OPERAND(fndecl, 0);
8797
8798   // Add a type cast in case the type of the function is a recursive
8799   // type which refers to itself.
8800   if (!DECL_P(fndecl) || !DECL_IS_BUILTIN(fndecl))
8801     {
8802       tree fnt = fntype->get_tree(gogo);
8803       if (fnt == error_mark_node)
8804         return error_mark_node;
8805       fn = fold_convert_loc(location, fnt, fn);
8806     }
8807
8808   // This is to support builtin math functions when using 80387 math.
8809   tree excess_type = NULL_TREE;
8810   if (DECL_P(fndecl)
8811       && DECL_IS_BUILTIN(fndecl)
8812       && DECL_BUILT_IN_CLASS(fndecl) == BUILT_IN_NORMAL
8813       && nargs > 0
8814       && ((SCALAR_FLOAT_TYPE_P(rettype)
8815            && SCALAR_FLOAT_TYPE_P(TREE_TYPE(args[0])))
8816           || (COMPLEX_FLOAT_TYPE_P(rettype)
8817               && COMPLEX_FLOAT_TYPE_P(TREE_TYPE(args[0])))))
8818     {
8819       excess_type = excess_precision_type(TREE_TYPE(args[0]));
8820       if (excess_type != NULL_TREE)
8821         {
8822           tree excess_fndecl = mathfn_built_in(excess_type,
8823                                                DECL_FUNCTION_CODE(fndecl));
8824           if (excess_fndecl == NULL_TREE)
8825             excess_type = NULL_TREE;
8826           else
8827             {
8828               fn = build_fold_addr_expr_loc(location, excess_fndecl);
8829               for (int i = 0; i < nargs; ++i)
8830                 args[i] = ::convert(excess_type, args[i]);
8831             }
8832         }
8833     }
8834
8835   tree ret = build_call_array(excess_type != NULL_TREE ? excess_type : rettype,
8836                               fn, nargs, args);
8837   delete[] args;
8838
8839   SET_EXPR_LOCATION(ret, location);
8840
8841   if (has_closure)
8842     {
8843       tree closure_tree = func->closure()->get_tree(context);
8844       if (closure_tree != error_mark_node)
8845         CALL_EXPR_STATIC_CHAIN(ret) = closure_tree;
8846     }
8847
8848   // If this is a recursive function type which returns itself, as in
8849   //   type F func() F
8850   // we have used ptr_type_node for the return type.  Add a cast here
8851   // to the correct type.
8852   if (TREE_TYPE(ret) == ptr_type_node)
8853     {
8854       tree t = this->type()->base()->get_tree(gogo);
8855       ret = fold_convert_loc(location, t, ret);
8856     }
8857
8858   if (excess_type != NULL_TREE)
8859     {
8860       // Calling convert here can undo our excess precision change.
8861       // That may or may not be a bug in convert_to_real.
8862       ret = build1(NOP_EXPR, rettype, ret);
8863     }
8864
8865   // If there is more than one result, we will refer to the call
8866   // multiple times.
8867   if (fntype->results() != NULL && fntype->results()->size() > 1)
8868     ret = save_expr(ret);
8869
8870   this->tree_ = ret;
8871
8872   return ret;
8873 }
8874
8875 // Make a call expression.
8876
8877 Call_expression*
8878 Expression::make_call(Expression* fn, Expression_list* args, bool is_varargs,
8879                       source_location location)
8880 {
8881   return new Call_expression(fn, args, is_varargs, location);
8882 }
8883
8884 // A single result from a call which returns multiple results.
8885
8886 class Call_result_expression : public Expression
8887 {
8888  public:
8889   Call_result_expression(Call_expression* call, unsigned int index)
8890     : Expression(EXPRESSION_CALL_RESULT, call->location()),
8891       call_(call), index_(index)
8892   { }
8893
8894  protected:
8895   int
8896   do_traverse(Traverse*);
8897
8898   Type*
8899   do_type();
8900
8901   void
8902   do_determine_type(const Type_context*);
8903
8904   void
8905   do_check_types(Gogo*);
8906
8907   Expression*
8908   do_copy()
8909   {
8910     return new Call_result_expression(this->call_->call_expression(),
8911                                       this->index_);
8912   }
8913
8914   bool
8915   do_must_eval_in_order() const
8916   { return true; }
8917
8918   tree
8919   do_get_tree(Translate_context*);
8920
8921  private:
8922   // The underlying call expression.
8923   Expression* call_;
8924   // Which result we want.
8925   unsigned int index_;
8926 };
8927
8928 // Traverse a call result.
8929
8930 int
8931 Call_result_expression::do_traverse(Traverse* traverse)
8932 {
8933   if (traverse->remember_expression(this->call_))
8934     {
8935       // We have already traversed the call expression.
8936       return TRAVERSE_CONTINUE;
8937     }
8938   return Expression::traverse(&this->call_, traverse);
8939 }
8940
8941 // Get the type.
8942
8943 Type*
8944 Call_result_expression::do_type()
8945 {
8946   if (this->classification() == EXPRESSION_ERROR)
8947     return Type::make_error_type();
8948
8949   // THIS->CALL_ can be replaced with a temporary reference due to
8950   // Call_expression::do_must_eval_in_order when there is an error.
8951   Call_expression* ce = this->call_->call_expression();
8952   if (ce == NULL)
8953     {
8954       this->set_is_error();
8955       return Type::make_error_type();
8956     }
8957   Function_type* fntype = ce->get_function_type();
8958   if (fntype == NULL)
8959     {
8960       this->set_is_error();
8961       return Type::make_error_type();
8962     }
8963   const Typed_identifier_list* results = fntype->results();
8964   if (results == NULL)
8965     {
8966       this->report_error(_("number of results does not match "
8967                            "number of values"));
8968       return Type::make_error_type();
8969     }
8970   Typed_identifier_list::const_iterator pr = results->begin();
8971   for (unsigned int i = 0; i < this->index_; ++i)
8972     {
8973       if (pr == results->end())
8974         break;
8975       ++pr;
8976     }
8977   if (pr == results->end())
8978     {
8979       this->report_error(_("number of results does not match "
8980                            "number of values"));
8981       return Type::make_error_type();
8982     }
8983   return pr->type();
8984 }
8985
8986 // Check the type.  Just make sure that we trigger the warning in
8987 // do_type.
8988
8989 void
8990 Call_result_expression::do_check_types(Gogo*)
8991 {
8992   this->type();
8993 }
8994
8995 // Determine the type.  We have nothing to do here, but the 0 result
8996 // needs to pass down to the caller.
8997
8998 void
8999 Call_result_expression::do_determine_type(const Type_context*)
9000 {
9001   this->call_->determine_type_no_context();
9002 }
9003
9004 // Return the tree.
9005
9006 tree
9007 Call_result_expression::do_get_tree(Translate_context* context)
9008 {
9009   tree call_tree = this->call_->get_tree(context);
9010   if (call_tree == error_mark_node)
9011     return error_mark_node;
9012   if (TREE_CODE(TREE_TYPE(call_tree)) != RECORD_TYPE)
9013     {
9014       gcc_assert(saw_errors());
9015       return error_mark_node;
9016     }
9017   tree field = TYPE_FIELDS(TREE_TYPE(call_tree));
9018   for (unsigned int i = 0; i < this->index_; ++i)
9019     {
9020       gcc_assert(field != NULL_TREE);
9021       field = DECL_CHAIN(field);
9022     }
9023   gcc_assert(field != NULL_TREE);
9024   return build3(COMPONENT_REF, TREE_TYPE(field), call_tree, field, NULL_TREE);
9025 }
9026
9027 // Make a reference to a single result of a call which returns
9028 // multiple results.
9029
9030 Expression*
9031 Expression::make_call_result(Call_expression* call, unsigned int index)
9032 {
9033   return new Call_result_expression(call, index);
9034 }
9035
9036 // Class Index_expression.
9037
9038 // Traversal.
9039
9040 int
9041 Index_expression::do_traverse(Traverse* traverse)
9042 {
9043   if (Expression::traverse(&this->left_, traverse) == TRAVERSE_EXIT
9044       || Expression::traverse(&this->start_, traverse) == TRAVERSE_EXIT
9045       || (this->end_ != NULL
9046           && Expression::traverse(&this->end_, traverse) == TRAVERSE_EXIT))
9047     return TRAVERSE_EXIT;
9048   return TRAVERSE_CONTINUE;
9049 }
9050
9051 // Lower an index expression.  This converts the generic index
9052 // expression into an array index, a string index, or a map index.
9053
9054 Expression*
9055 Index_expression::do_lower(Gogo*, Named_object*, int)
9056 {
9057   source_location location = this->location();
9058   Expression* left = this->left_;
9059   Expression* start = this->start_;
9060   Expression* end = this->end_;
9061
9062   Type* type = left->type();
9063   if (type->is_error_type())
9064     return Expression::make_error(location);
9065   else if (left->is_type_expression())
9066     {
9067       error_at(location, "attempt to index type expression");
9068       return Expression::make_error(location);
9069     }
9070   else if (type->array_type() != NULL)
9071     return Expression::make_array_index(left, start, end, location);
9072   else if (type->points_to() != NULL
9073            && type->points_to()->array_type() != NULL
9074            && !type->points_to()->is_open_array_type())
9075     {
9076       Expression* deref = Expression::make_unary(OPERATOR_MULT, left,
9077                                                  location);
9078       return Expression::make_array_index(deref, start, end, location);
9079     }
9080   else if (type->is_string_type())
9081     return Expression::make_string_index(left, start, end, location);
9082   else if (type->map_type() != NULL)
9083     {
9084       if (end != NULL)
9085         {
9086           error_at(location, "invalid slice of map");
9087           return Expression::make_error(location);
9088         }
9089       Map_index_expression* ret= Expression::make_map_index(left, start,
9090                                                             location);
9091       if (this->is_lvalue_)
9092         ret->set_is_lvalue();
9093       return ret;
9094     }
9095   else
9096     {
9097       error_at(location,
9098                "attempt to index object which is not array, string, or map");
9099       return Expression::make_error(location);
9100     }
9101 }
9102
9103 // Make an index expression.
9104
9105 Expression*
9106 Expression::make_index(Expression* left, Expression* start, Expression* end,
9107                        source_location location)
9108 {
9109   return new Index_expression(left, start, end, location);
9110 }
9111
9112 // An array index.  This is used for both indexing and slicing.
9113
9114 class Array_index_expression : public Expression
9115 {
9116  public:
9117   Array_index_expression(Expression* array, Expression* start,
9118                          Expression* end, source_location location)
9119     : Expression(EXPRESSION_ARRAY_INDEX, location),
9120       array_(array), start_(start), end_(end), type_(NULL)
9121   { }
9122
9123  protected:
9124   int
9125   do_traverse(Traverse*);
9126
9127   Type*
9128   do_type();
9129
9130   void
9131   do_determine_type(const Type_context*);
9132
9133   void
9134   do_check_types(Gogo*);
9135
9136   Expression*
9137   do_copy()
9138   {
9139     return Expression::make_array_index(this->array_->copy(),
9140                                         this->start_->copy(),
9141                                         (this->end_ == NULL
9142                                          ? NULL
9143                                          : this->end_->copy()),
9144                                         this->location());
9145   }
9146
9147   bool
9148   do_is_addressable() const;
9149
9150   void
9151   do_address_taken(bool escapes)
9152   { this->array_->address_taken(escapes); }
9153
9154   tree
9155   do_get_tree(Translate_context*);
9156
9157  private:
9158   // The array we are getting a value from.
9159   Expression* array_;
9160   // The start or only index.
9161   Expression* start_;
9162   // The end index of a slice.  This may be NULL for a simple array
9163   // index, or it may be a nil expression for the length of the array.
9164   Expression* end_;
9165   // The type of the expression.
9166   Type* type_;
9167 };
9168
9169 // Array index traversal.
9170
9171 int
9172 Array_index_expression::do_traverse(Traverse* traverse)
9173 {
9174   if (Expression::traverse(&this->array_, traverse) == TRAVERSE_EXIT)
9175     return TRAVERSE_EXIT;
9176   if (Expression::traverse(&this->start_, traverse) == TRAVERSE_EXIT)
9177     return TRAVERSE_EXIT;
9178   if (this->end_ != NULL)
9179     {
9180       if (Expression::traverse(&this->end_, traverse) == TRAVERSE_EXIT)
9181         return TRAVERSE_EXIT;
9182     }
9183   return TRAVERSE_CONTINUE;
9184 }
9185
9186 // Return the type of an array index.
9187
9188 Type*
9189 Array_index_expression::do_type()
9190 {
9191   if (this->type_ == NULL)
9192     {
9193      Array_type* type = this->array_->type()->array_type();
9194       if (type == NULL)
9195         this->type_ = Type::make_error_type();
9196       else if (this->end_ == NULL)
9197         this->type_ = type->element_type();
9198       else if (type->is_open_array_type())
9199         {
9200           // A slice of a slice has the same type as the original
9201           // slice.
9202           this->type_ = this->array_->type()->deref();
9203         }
9204       else
9205         {
9206           // A slice of an array is a slice.
9207           this->type_ = Type::make_array_type(type->element_type(), NULL);
9208         }
9209     }
9210   return this->type_;
9211 }
9212
9213 // Set the type of an array index.
9214
9215 void
9216 Array_index_expression::do_determine_type(const Type_context*)
9217 {
9218   this->array_->determine_type_no_context();
9219   this->start_->determine_type_no_context();
9220   if (this->end_ != NULL)
9221     this->end_->determine_type_no_context();
9222 }
9223
9224 // Check types of an array index.
9225
9226 void
9227 Array_index_expression::do_check_types(Gogo*)
9228 {
9229   if (this->start_->type()->integer_type() == NULL)
9230     this->report_error(_("index must be integer"));
9231   if (this->end_ != NULL
9232       && this->end_->type()->integer_type() == NULL
9233       && !this->end_->is_nil_expression())
9234     this->report_error(_("slice end must be integer"));
9235
9236   Array_type* array_type = this->array_->type()->array_type();
9237   if (array_type == NULL)
9238     {
9239       gcc_assert(this->array_->type()->is_error_type());
9240       return;
9241     }
9242
9243   unsigned int int_bits =
9244     Type::lookup_integer_type("int")->integer_type()->bits();
9245
9246   Type* dummy;
9247   mpz_t lval;
9248   mpz_init(lval);
9249   bool lval_valid = (array_type->length() != NULL
9250                      && array_type->length()->integer_constant_value(true,
9251                                                                      lval,
9252                                                                      &dummy));
9253   mpz_t ival;
9254   mpz_init(ival);
9255   if (this->start_->integer_constant_value(true, ival, &dummy))
9256     {
9257       if (mpz_sgn(ival) < 0
9258           || mpz_sizeinbase(ival, 2) >= int_bits
9259           || (lval_valid
9260               && (this->end_ == NULL
9261                   ? mpz_cmp(ival, lval) >= 0
9262                   : mpz_cmp(ival, lval) > 0)))
9263         {
9264           error_at(this->start_->location(), "array index out of bounds");
9265           this->set_is_error();
9266         }
9267     }
9268   if (this->end_ != NULL && !this->end_->is_nil_expression())
9269     {
9270       if (this->end_->integer_constant_value(true, ival, &dummy))
9271         {
9272           if (mpz_sgn(ival) < 0
9273               || mpz_sizeinbase(ival, 2) >= int_bits
9274               || (lval_valid && mpz_cmp(ival, lval) > 0))
9275             {
9276               error_at(this->end_->location(), "array index out of bounds");
9277               this->set_is_error();
9278             }
9279         }
9280     }
9281   mpz_clear(ival);
9282   mpz_clear(lval);
9283
9284   // A slice of an array requires an addressable array.  A slice of a
9285   // slice is always possible.
9286   if (this->end_ != NULL
9287       && !array_type->is_open_array_type()
9288       && !this->array_->is_addressable())
9289     this->report_error(_("array is not addressable"));
9290 }
9291
9292 // Return whether this expression is addressable.
9293
9294 bool
9295 Array_index_expression::do_is_addressable() const
9296 {
9297   // A slice expression is not addressable.
9298   if (this->end_ != NULL)
9299     return false;
9300
9301   // An index into a slice is addressable.
9302   if (this->array_->type()->is_open_array_type())
9303     return true;
9304
9305   // An index into an array is addressable if the array is
9306   // addressable.
9307   return this->array_->is_addressable();
9308 }
9309
9310 // Get a tree for an array index.
9311
9312 tree
9313 Array_index_expression::do_get_tree(Translate_context* context)
9314 {
9315   Gogo* gogo = context->gogo();
9316   source_location loc = this->location();
9317
9318   Array_type* array_type = this->array_->type()->array_type();
9319   if (array_type == NULL)
9320     {
9321       gcc_assert(this->array_->type()->is_error_type());
9322       return error_mark_node;
9323     }
9324
9325   tree type_tree = array_type->get_tree(gogo);
9326   if (type_tree == error_mark_node)
9327     return error_mark_node;
9328
9329   tree array_tree = this->array_->get_tree(context);
9330   if (array_tree == error_mark_node)
9331     return error_mark_node;
9332
9333   if (array_type->length() == NULL && !DECL_P(array_tree))
9334     array_tree = save_expr(array_tree);
9335   tree length_tree = array_type->length_tree(gogo, array_tree);
9336   if (length_tree == error_mark_node)
9337     return error_mark_node;
9338   length_tree = save_expr(length_tree);
9339   tree length_type = TREE_TYPE(length_tree);
9340
9341   tree bad_index = boolean_false_node;
9342
9343   tree start_tree = this->start_->get_tree(context);
9344   if (start_tree == error_mark_node)
9345     return error_mark_node;
9346   if (!DECL_P(start_tree))
9347     start_tree = save_expr(start_tree);
9348   if (!INTEGRAL_TYPE_P(TREE_TYPE(start_tree)))
9349     start_tree = convert_to_integer(length_type, start_tree);
9350
9351   bad_index = Expression::check_bounds(start_tree, length_type, bad_index,
9352                                        loc);
9353
9354   start_tree = fold_convert_loc(loc, length_type, start_tree);
9355   bad_index = fold_build2_loc(loc, TRUTH_OR_EXPR, boolean_type_node, bad_index,
9356                               fold_build2_loc(loc,
9357                                               (this->end_ == NULL
9358                                                ? GE_EXPR
9359                                                : GT_EXPR),
9360                                               boolean_type_node, start_tree,
9361                                               length_tree));
9362
9363   int code = (array_type->length() != NULL
9364               ? (this->end_ == NULL
9365                  ? RUNTIME_ERROR_ARRAY_INDEX_OUT_OF_BOUNDS
9366                  : RUNTIME_ERROR_ARRAY_SLICE_OUT_OF_BOUNDS)
9367               : (this->end_ == NULL
9368                  ? RUNTIME_ERROR_SLICE_INDEX_OUT_OF_BOUNDS
9369                  : RUNTIME_ERROR_SLICE_SLICE_OUT_OF_BOUNDS));
9370   tree crash = Gogo::runtime_error(code, loc);
9371
9372   if (this->end_ == NULL)
9373     {
9374       // Simple array indexing.  This has to return an l-value, so
9375       // wrap the index check into START_TREE.
9376       start_tree = build2(COMPOUND_EXPR, TREE_TYPE(start_tree),
9377                           build3(COND_EXPR, void_type_node,
9378                                  bad_index, crash, NULL_TREE),
9379                           start_tree);
9380       start_tree = fold_convert_loc(loc, sizetype, start_tree);
9381
9382       if (array_type->length() != NULL)
9383         {
9384           // Fixed array.
9385           return build4(ARRAY_REF, TREE_TYPE(type_tree), array_tree,
9386                         start_tree, NULL_TREE, NULL_TREE);
9387         }
9388       else
9389         {
9390           // Open array.
9391           tree values = array_type->value_pointer_tree(gogo, array_tree);
9392           tree element_type_tree = array_type->element_type()->get_tree(gogo);
9393           if (element_type_tree == error_mark_node)
9394             return error_mark_node;
9395           tree element_size = TYPE_SIZE_UNIT(element_type_tree);
9396           tree offset = fold_build2_loc(loc, MULT_EXPR, sizetype,
9397                                         start_tree, element_size);
9398           tree ptr = fold_build2_loc(loc, POINTER_PLUS_EXPR,
9399                                      TREE_TYPE(values), values, offset);
9400           return build_fold_indirect_ref(ptr);
9401         }
9402     }
9403
9404   // Array slice.
9405
9406   tree capacity_tree = array_type->capacity_tree(gogo, array_tree);
9407   if (capacity_tree == error_mark_node)
9408     return error_mark_node;
9409   capacity_tree = fold_convert_loc(loc, length_type, capacity_tree);
9410
9411   tree end_tree;
9412   if (this->end_->is_nil_expression())
9413     end_tree = length_tree;
9414   else
9415     {
9416       end_tree = this->end_->get_tree(context);
9417       if (end_tree == error_mark_node)
9418         return error_mark_node;
9419       if (!DECL_P(end_tree))
9420         end_tree = save_expr(end_tree);
9421       if (!INTEGRAL_TYPE_P(TREE_TYPE(end_tree)))
9422         end_tree = convert_to_integer(length_type, end_tree);
9423
9424       bad_index = Expression::check_bounds(end_tree, length_type, bad_index,
9425                                            loc);
9426
9427       end_tree = fold_convert_loc(loc, length_type, end_tree);
9428
9429       capacity_tree = save_expr(capacity_tree);
9430       tree bad_end = fold_build2_loc(loc, TRUTH_OR_EXPR, boolean_type_node,
9431                                      fold_build2_loc(loc, LT_EXPR,
9432                                                      boolean_type_node,
9433                                                      end_tree, start_tree),
9434                                      fold_build2_loc(loc, GT_EXPR,
9435                                                      boolean_type_node,
9436                                                      end_tree, capacity_tree));
9437       bad_index = fold_build2_loc(loc, TRUTH_OR_EXPR, boolean_type_node,
9438                                   bad_index, bad_end);
9439     }
9440
9441   tree element_type_tree = array_type->element_type()->get_tree(gogo);
9442   if (element_type_tree == error_mark_node)
9443     return error_mark_node;
9444   tree element_size = TYPE_SIZE_UNIT(element_type_tree);
9445
9446   tree offset = fold_build2_loc(loc, MULT_EXPR, sizetype,
9447                                 fold_convert_loc(loc, sizetype, start_tree),
9448                                 element_size);
9449
9450   tree value_pointer = array_type->value_pointer_tree(gogo, array_tree);
9451   if (value_pointer == error_mark_node)
9452     return error_mark_node;
9453
9454   value_pointer = fold_build2_loc(loc, POINTER_PLUS_EXPR,
9455                                   TREE_TYPE(value_pointer),
9456                                   value_pointer, offset);
9457
9458   tree result_length_tree = fold_build2_loc(loc, MINUS_EXPR, length_type,
9459                                             end_tree, start_tree);
9460
9461   tree result_capacity_tree = fold_build2_loc(loc, MINUS_EXPR, length_type,
9462                                               capacity_tree, start_tree);
9463
9464   tree struct_tree = this->type()->get_tree(gogo);
9465   gcc_assert(TREE_CODE(struct_tree) == RECORD_TYPE);
9466
9467   VEC(constructor_elt,gc)* init = VEC_alloc(constructor_elt, gc, 3);
9468
9469   constructor_elt* elt = VEC_quick_push(constructor_elt, init, NULL);
9470   tree field = TYPE_FIELDS(struct_tree);
9471   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__values") == 0);
9472   elt->index = field;
9473   elt->value = value_pointer;
9474
9475   elt = VEC_quick_push(constructor_elt, init, NULL);
9476   field = DECL_CHAIN(field);
9477   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__count") == 0);
9478   elt->index = field;
9479   elt->value = fold_convert_loc(loc, TREE_TYPE(field), result_length_tree);
9480
9481   elt = VEC_quick_push(constructor_elt, init, NULL);
9482   field = DECL_CHAIN(field);
9483   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__capacity") == 0);
9484   elt->index = field;
9485   elt->value = fold_convert_loc(loc, TREE_TYPE(field), result_capacity_tree);
9486
9487   tree constructor = build_constructor(struct_tree, init);
9488
9489   if (TREE_CONSTANT(value_pointer)
9490       && TREE_CONSTANT(result_length_tree)
9491       && TREE_CONSTANT(result_capacity_tree))
9492     TREE_CONSTANT(constructor) = 1;
9493
9494   return fold_build2_loc(loc, COMPOUND_EXPR, TREE_TYPE(constructor),
9495                          build3(COND_EXPR, void_type_node,
9496                                 bad_index, crash, NULL_TREE),
9497                          constructor);
9498 }
9499
9500 // Make an array index expression.  END may be NULL.
9501
9502 Expression*
9503 Expression::make_array_index(Expression* array, Expression* start,
9504                              Expression* end, source_location location)
9505 {
9506   // Taking a slice of a composite literal requires moving the literal
9507   // onto the heap.
9508   if (end != NULL && array->is_composite_literal())
9509     {
9510       array = Expression::make_heap_composite(array, location);
9511       array = Expression::make_unary(OPERATOR_MULT, array, location);
9512     }
9513   return new Array_index_expression(array, start, end, location);
9514 }
9515
9516 // A string index.  This is used for both indexing and slicing.
9517
9518 class String_index_expression : public Expression
9519 {
9520  public:
9521   String_index_expression(Expression* string, Expression* start,
9522                           Expression* end, source_location location)
9523     : Expression(EXPRESSION_STRING_INDEX, location),
9524       string_(string), start_(start), end_(end)
9525   { }
9526
9527  protected:
9528   int
9529   do_traverse(Traverse*);
9530
9531   Type*
9532   do_type();
9533
9534   void
9535   do_determine_type(const Type_context*);
9536
9537   void
9538   do_check_types(Gogo*);
9539
9540   Expression*
9541   do_copy()
9542   {
9543     return Expression::make_string_index(this->string_->copy(),
9544                                          this->start_->copy(),
9545                                          (this->end_ == NULL
9546                                           ? NULL
9547                                           : this->end_->copy()),
9548                                          this->location());
9549   }
9550
9551   tree
9552   do_get_tree(Translate_context*);
9553
9554  private:
9555   // The string we are getting a value from.
9556   Expression* string_;
9557   // The start or only index.
9558   Expression* start_;
9559   // The end index of a slice.  This may be NULL for a single index,
9560   // or it may be a nil expression for the length of the string.
9561   Expression* end_;
9562 };
9563
9564 // String index traversal.
9565
9566 int
9567 String_index_expression::do_traverse(Traverse* traverse)
9568 {
9569   if (Expression::traverse(&this->string_, traverse) == TRAVERSE_EXIT)
9570     return TRAVERSE_EXIT;
9571   if (Expression::traverse(&this->start_, traverse) == TRAVERSE_EXIT)
9572     return TRAVERSE_EXIT;
9573   if (this->end_ != NULL)
9574     {
9575       if (Expression::traverse(&this->end_, traverse) == TRAVERSE_EXIT)
9576         return TRAVERSE_EXIT;
9577     }
9578   return TRAVERSE_CONTINUE;
9579 }
9580
9581 // Return the type of a string index.
9582
9583 Type*
9584 String_index_expression::do_type()
9585 {
9586   if (this->end_ == NULL)
9587     return Type::lookup_integer_type("uint8");
9588   else
9589     return this->string_->type();
9590 }
9591
9592 // Determine the type of a string index.
9593
9594 void
9595 String_index_expression::do_determine_type(const Type_context*)
9596 {
9597   this->string_->determine_type_no_context();
9598   this->start_->determine_type_no_context();
9599   if (this->end_ != NULL)
9600     this->end_->determine_type_no_context();
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;
9901   tree make_tmp;
9902   if (current_function_decl != NULL)
9903     {
9904       tmp = create_tmp_var(TREE_TYPE(index_tree), get_name(index_tree));
9905       DECL_IGNORED_P(tmp) = 0;
9906       DECL_INITIAL(tmp) = index_tree;
9907       make_tmp = build1(DECL_EXPR, void_type_node, tmp);
9908       TREE_ADDRESSABLE(tmp) = 1;
9909     }
9910   else
9911     {
9912       tmp = build_decl(this->location(), VAR_DECL, create_tmp_var_name("M"),
9913                        TREE_TYPE(index_tree));
9914       DECL_EXTERNAL(tmp) = 0;
9915       TREE_PUBLIC(tmp) = 0;
9916       TREE_STATIC(tmp) = 1;
9917       DECL_ARTIFICIAL(tmp) = 1;
9918       if (!TREE_CONSTANT(index_tree))
9919         make_tmp = fold_build2_loc(this->location(), INIT_EXPR, void_type_node,
9920                                    tmp, index_tree);
9921       else
9922         {
9923           TREE_READONLY(tmp) = 1;
9924           TREE_CONSTANT(tmp) = 1;
9925           DECL_INITIAL(tmp) = index_tree;
9926           make_tmp = NULL_TREE;
9927         }
9928       rest_of_decl_compilation(tmp, 1, 0);
9929     }
9930   tree tmpref = fold_convert_loc(this->location(), const_ptr_type_node,
9931                                  build_fold_addr_expr_loc(this->location(),
9932                                                           tmp));
9933
9934   static tree map_index_fndecl;
9935   tree call = Gogo::call_builtin(&map_index_fndecl,
9936                                  this->location(),
9937                                  "__go_map_index",
9938                                  3,
9939                                  const_ptr_type_node,
9940                                  TREE_TYPE(map_tree),
9941                                  map_tree,
9942                                  const_ptr_type_node,
9943                                  tmpref,
9944                                  boolean_type_node,
9945                                  (insert
9946                                   ? boolean_true_node
9947                                   : boolean_false_node));
9948   if (call == error_mark_node)
9949     return error_mark_node;
9950   // This can panic on a map of interface type if the interface holds
9951   // an uncomparable or unhashable type.
9952   TREE_NOTHROW(map_index_fndecl) = 0;
9953
9954   tree val_type_tree = type->val_type()->get_tree(context->gogo());
9955   if (val_type_tree == error_mark_node)
9956     return error_mark_node;
9957   tree ptr_val_type_tree = build_pointer_type(val_type_tree);
9958
9959   tree ret = fold_convert_loc(this->location(), ptr_val_type_tree, call);
9960   if (make_tmp != NULL_TREE)
9961     ret = build2(COMPOUND_EXPR, ptr_val_type_tree, make_tmp, ret);
9962   return ret;
9963 }
9964
9965 // Make a map index expression.
9966
9967 Map_index_expression*
9968 Expression::make_map_index(Expression* map, Expression* index,
9969                            source_location location)
9970 {
9971   return new Map_index_expression(map, index, location);
9972 }
9973
9974 // Class Field_reference_expression.
9975
9976 // Return the type of a field reference.
9977
9978 Type*
9979 Field_reference_expression::do_type()
9980 {
9981   Type* type = this->expr_->type();
9982   if (type->is_error_type())
9983     return type;
9984   Struct_type* struct_type = type->struct_type();
9985   gcc_assert(struct_type != NULL);
9986   return struct_type->field(this->field_index_)->type();
9987 }
9988
9989 // Check the types for a field reference.
9990
9991 void
9992 Field_reference_expression::do_check_types(Gogo*)
9993 {
9994   Type* type = this->expr_->type();
9995   if (type->is_error_type())
9996     return;
9997   Struct_type* struct_type = type->struct_type();
9998   gcc_assert(struct_type != NULL);
9999   gcc_assert(struct_type->field(this->field_index_) != NULL);
10000 }
10001
10002 // Get a tree for a field reference.
10003
10004 tree
10005 Field_reference_expression::do_get_tree(Translate_context* context)
10006 {
10007   tree struct_tree = this->expr_->get_tree(context);
10008   if (struct_tree == error_mark_node
10009       || TREE_TYPE(struct_tree) == error_mark_node)
10010     return error_mark_node;
10011   gcc_assert(TREE_CODE(TREE_TYPE(struct_tree)) == RECORD_TYPE);
10012   tree field = TYPE_FIELDS(TREE_TYPE(struct_tree));
10013   if (field == NULL_TREE)
10014     {
10015       // This can happen for a type which refers to itself indirectly
10016       // and then turns out to be erroneous.
10017       gcc_assert(saw_errors());
10018       return error_mark_node;
10019     }
10020   for (unsigned int i = this->field_index_; i > 0; --i)
10021     {
10022       field = DECL_CHAIN(field);
10023       gcc_assert(field != NULL_TREE);
10024     }
10025   if (TREE_TYPE(field) == error_mark_node)
10026     return error_mark_node;
10027   return build3(COMPONENT_REF, TREE_TYPE(field), struct_tree, field,
10028                 NULL_TREE);
10029 }
10030
10031 // Make a reference to a qualified identifier in an expression.
10032
10033 Field_reference_expression*
10034 Expression::make_field_reference(Expression* expr, unsigned int field_index,
10035                                  source_location location)
10036 {
10037   return new Field_reference_expression(expr, field_index, location);
10038 }
10039
10040 // Class Interface_field_reference_expression.
10041
10042 // Return a tree for the pointer to the function to call.
10043
10044 tree
10045 Interface_field_reference_expression::get_function_tree(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 = TYPE_FIELDS(expr_type);
10055   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__methods") == 0);
10056
10057   tree table = build3(COMPONENT_REF, TREE_TYPE(field), expr, field, NULL_TREE);
10058   gcc_assert(POINTER_TYPE_P(TREE_TYPE(table)));
10059
10060   table = build_fold_indirect_ref(table);
10061   gcc_assert(TREE_CODE(TREE_TYPE(table)) == RECORD_TYPE);
10062
10063   std::string name = Gogo::unpack_hidden_name(this->name_);
10064   for (field = DECL_CHAIN(TYPE_FIELDS(TREE_TYPE(table)));
10065        field != NULL_TREE;
10066        field = DECL_CHAIN(field))
10067     {
10068       if (name == IDENTIFIER_POINTER(DECL_NAME(field)))
10069         break;
10070     }
10071   gcc_assert(field != NULL_TREE);
10072
10073   return build3(COMPONENT_REF, TREE_TYPE(field), table, field, NULL_TREE);
10074 }
10075
10076 // Return a tree for the first argument to pass to the interface
10077 // function.
10078
10079 tree
10080 Interface_field_reference_expression::get_underlying_object_tree(
10081     Translate_context*,
10082     tree expr)
10083 {
10084   if (this->expr_->type()->points_to() != NULL)
10085     expr = build_fold_indirect_ref(expr);
10086
10087   tree expr_type = TREE_TYPE(expr);
10088   gcc_assert(TREE_CODE(expr_type) == RECORD_TYPE);
10089
10090   tree field = DECL_CHAIN(TYPE_FIELDS(expr_type));
10091   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__object") == 0);
10092
10093   return build3(COMPONENT_REF, TREE_TYPE(field), expr, field, NULL_TREE);
10094 }
10095
10096 // Traversal.
10097
10098 int
10099 Interface_field_reference_expression::do_traverse(Traverse* traverse)
10100 {
10101   return Expression::traverse(&this->expr_, traverse);
10102 }
10103
10104 // Return the type of an interface field reference.
10105
10106 Type*
10107 Interface_field_reference_expression::do_type()
10108 {
10109   Type* expr_type = this->expr_->type();
10110
10111   Type* points_to = expr_type->points_to();
10112   if (points_to != NULL)
10113     expr_type = points_to;
10114
10115   Interface_type* interface_type = expr_type->interface_type();
10116   if (interface_type == NULL)
10117     return Type::make_error_type();
10118
10119   const Typed_identifier* method = interface_type->find_method(this->name_);
10120   if (method == NULL)
10121     return Type::make_error_type();
10122
10123   return method->type();
10124 }
10125
10126 // Determine types.
10127
10128 void
10129 Interface_field_reference_expression::do_determine_type(const Type_context*)
10130 {
10131   this->expr_->determine_type_no_context();
10132 }
10133
10134 // Check the types for an interface field reference.
10135
10136 void
10137 Interface_field_reference_expression::do_check_types(Gogo*)
10138 {
10139   Type* type = this->expr_->type();
10140
10141   Type* points_to = type->points_to();
10142   if (points_to != NULL)
10143     type = points_to;
10144
10145   Interface_type* interface_type = type->interface_type();
10146   if (interface_type == NULL)
10147     this->report_error(_("expected interface or pointer to interface"));
10148   else
10149     {
10150       const Typed_identifier* method =
10151         interface_type->find_method(this->name_);
10152       if (method == NULL)
10153         {
10154           error_at(this->location(), "method %qs not in interface",
10155                    Gogo::message_name(this->name_).c_str());
10156           this->set_is_error();
10157         }
10158     }
10159 }
10160
10161 // Get a tree for a reference to a field in an interface.  There is no
10162 // standard tree type representation for this: it's a function
10163 // attached to its first argument, like a Bound_method_expression.
10164 // The only places it may currently be used are in a Call_expression
10165 // or a Go_statement, which will take it apart directly.  So this has
10166 // nothing to do at present.
10167
10168 tree
10169 Interface_field_reference_expression::do_get_tree(Translate_context*)
10170 {
10171   gcc_unreachable();
10172 }
10173
10174 // Make a reference to a field in an interface.
10175
10176 Expression*
10177 Expression::make_interface_field_reference(Expression* expr,
10178                                            const std::string& field,
10179                                            source_location location)
10180 {
10181   return new Interface_field_reference_expression(expr, field, location);
10182 }
10183
10184 // A general selector.  This is a Parser_expression for LEFT.NAME.  It
10185 // is lowered after we know the type of the left hand side.
10186
10187 class Selector_expression : public Parser_expression
10188 {
10189  public:
10190   Selector_expression(Expression* left, const std::string& name,
10191                       source_location location)
10192     : Parser_expression(EXPRESSION_SELECTOR, location),
10193       left_(left), name_(name)
10194   { }
10195
10196  protected:
10197   int
10198   do_traverse(Traverse* traverse)
10199   { return Expression::traverse(&this->left_, traverse); }
10200
10201   Expression*
10202   do_lower(Gogo*, Named_object*, int);
10203
10204   Expression*
10205   do_copy()
10206   {
10207     return new Selector_expression(this->left_->copy(), this->name_,
10208                                    this->location());
10209   }
10210
10211  private:
10212   Expression*
10213   lower_method_expression(Gogo*);
10214
10215   // The expression on the left hand side.
10216   Expression* left_;
10217   // The name on the right hand side.
10218   std::string name_;
10219 };
10220
10221 // Lower a selector expression once we know the real type of the left
10222 // hand side.
10223
10224 Expression*
10225 Selector_expression::do_lower(Gogo* gogo, Named_object*, int)
10226 {
10227   Expression* left = this->left_;
10228   if (left->is_type_expression())
10229     return this->lower_method_expression(gogo);
10230   return Type::bind_field_or_method(gogo, left->type(), left, this->name_,
10231                                     this->location());
10232 }
10233
10234 // Lower a method expression T.M or (*T).M.  We turn this into a
10235 // function literal.
10236
10237 Expression*
10238 Selector_expression::lower_method_expression(Gogo* gogo)
10239 {
10240   source_location location = this->location();
10241   Type* type = this->left_->type();
10242   const std::string& name(this->name_);
10243
10244   bool is_pointer;
10245   if (type->points_to() == NULL)
10246     is_pointer = false;
10247   else
10248     {
10249       is_pointer = true;
10250       type = type->points_to();
10251     }
10252   Named_type* nt = type->named_type();
10253   if (nt == NULL)
10254     {
10255       error_at(location,
10256                ("method expression requires named type or "
10257                 "pointer to named type"));
10258       return Expression::make_error(location);
10259     }
10260
10261   bool is_ambiguous;
10262   Method* method = nt->method_function(name, &is_ambiguous);
10263   if (method == NULL)
10264     {
10265       if (!is_ambiguous)
10266         error_at(location, "type %<%s%> has no method %<%s%>",
10267                  nt->message_name().c_str(),
10268                  Gogo::message_name(name).c_str());
10269       else
10270         error_at(location, "method %<%s%> is ambiguous in type %<%s%>",
10271                  Gogo::message_name(name).c_str(),
10272                  nt->message_name().c_str());
10273       return Expression::make_error(location);
10274     }
10275
10276   if (!is_pointer && !method->is_value_method())
10277     {
10278       error_at(location, "method requires pointer (use %<(*%s).%s)%>",
10279                nt->message_name().c_str(),
10280                Gogo::message_name(name).c_str());
10281       return Expression::make_error(location);
10282     }
10283
10284   // Build a new function type in which the receiver becomes the first
10285   // argument.
10286   Function_type* method_type = method->type();
10287   gcc_assert(method_type->is_method());
10288
10289   const char* const receiver_name = "$this";
10290   Typed_identifier_list* parameters = new Typed_identifier_list();
10291   parameters->push_back(Typed_identifier(receiver_name, this->left_->type(),
10292                                          location));
10293
10294   const Typed_identifier_list* method_parameters = method_type->parameters();
10295   if (method_parameters != NULL)
10296     {
10297       for (Typed_identifier_list::const_iterator p = method_parameters->begin();
10298            p != method_parameters->end();
10299            ++p)
10300         parameters->push_back(*p);
10301     }
10302
10303   const Typed_identifier_list* method_results = method_type->results();
10304   Typed_identifier_list* results;
10305   if (method_results == NULL)
10306     results = NULL;
10307   else
10308     {
10309       results = new Typed_identifier_list();
10310       for (Typed_identifier_list::const_iterator p = method_results->begin();
10311            p != method_results->end();
10312            ++p)
10313         results->push_back(*p);
10314     }
10315
10316   Function_type* fntype = Type::make_function_type(NULL, parameters, results,
10317                                                    location);
10318   if (method_type->is_varargs())
10319     fntype->set_is_varargs();
10320
10321   // We generate methods which always takes a pointer to the receiver
10322   // as their first argument.  If this is for a pointer type, we can
10323   // simply reuse the existing function.  We use an internal hack to
10324   // get the right type.
10325
10326   if (is_pointer)
10327     {
10328       Named_object* mno = (method->needs_stub_method()
10329                            ? method->stub_object()
10330                            : method->named_object());
10331       Expression* f = Expression::make_func_reference(mno, NULL, location);
10332       f = Expression::make_cast(fntype, f, location);
10333       Type_conversion_expression* tce =
10334         static_cast<Type_conversion_expression*>(f);
10335       tce->set_may_convert_function_types();
10336       return f;
10337     }
10338
10339   Named_object* no = gogo->start_function(Gogo::thunk_name(), fntype, false,
10340                                           location);
10341
10342   Named_object* vno = gogo->lookup(receiver_name, NULL);
10343   gcc_assert(vno != NULL);
10344   Expression* ve = Expression::make_var_reference(vno, location);
10345   Expression* bm = Type::bind_field_or_method(gogo, nt, ve, name, location);
10346
10347   // Even though we found the method above, if it has an error type we
10348   // may see an error here.
10349   if (bm->is_error_expression())
10350     {
10351       gogo->finish_function(location);
10352       return bm;
10353     }
10354
10355   Expression_list* args;
10356   if (method_parameters == NULL)
10357     args = NULL;
10358   else
10359     {
10360       args = new Expression_list();
10361       for (Typed_identifier_list::const_iterator p = method_parameters->begin();
10362            p != method_parameters->end();
10363            ++p)
10364         {
10365           vno = gogo->lookup(p->name(), NULL);
10366           gcc_assert(vno != NULL);
10367           args->push_back(Expression::make_var_reference(vno, location));
10368         }
10369     }
10370
10371   Call_expression* call = Expression::make_call(bm, args,
10372                                                 method_type->is_varargs(),
10373                                                 location);
10374
10375   size_t count = call->result_count();
10376   Statement* s;
10377   if (count == 0)
10378     s = Statement::make_statement(call);
10379   else
10380     {
10381       Expression_list* retvals = new Expression_list();
10382       if (count <= 1)
10383         retvals->push_back(call);
10384       else
10385         {
10386           for (size_t i = 0; i < count; ++i)
10387             retvals->push_back(Expression::make_call_result(call, i));
10388         }
10389       s = Statement::make_return_statement(no->func_value()->type()->results(),
10390                                            retvals, location);
10391     }
10392   gogo->add_statement(s);
10393
10394   gogo->finish_function(location);
10395
10396   return Expression::make_func_reference(no, NULL, location);
10397 }
10398
10399 // Make a selector expression.
10400
10401 Expression*
10402 Expression::make_selector(Expression* left, const std::string& name,
10403                           source_location location)
10404 {
10405   return new Selector_expression(left, name, location);
10406 }
10407
10408 // Implement the builtin function new.
10409
10410 class Allocation_expression : public Expression
10411 {
10412  public:
10413   Allocation_expression(Type* type, source_location location)
10414     : Expression(EXPRESSION_ALLOCATION, location),
10415       type_(type)
10416   { }
10417
10418  protected:
10419   int
10420   do_traverse(Traverse* traverse)
10421   { return Type::traverse(this->type_, traverse); }
10422
10423   Type*
10424   do_type()
10425   { return Type::make_pointer_type(this->type_); }
10426
10427   void
10428   do_determine_type(const Type_context*)
10429   { }
10430
10431   void
10432   do_check_types(Gogo*);
10433
10434   Expression*
10435   do_copy()
10436   { return new Allocation_expression(this->type_, this->location()); }
10437
10438   tree
10439   do_get_tree(Translate_context*);
10440
10441  private:
10442   // The type we are allocating.
10443   Type* type_;
10444 };
10445
10446 // Check the type of an allocation expression.
10447
10448 void
10449 Allocation_expression::do_check_types(Gogo*)
10450 {
10451   if (this->type_->function_type() != NULL)
10452     this->report_error(_("invalid new of function type"));
10453 }
10454
10455 // Return a tree for an allocation expression.
10456
10457 tree
10458 Allocation_expression::do_get_tree(Translate_context* context)
10459 {
10460   tree type_tree = this->type_->get_tree(context->gogo());
10461   if (type_tree == error_mark_node)
10462     return error_mark_node;
10463   tree size_tree = TYPE_SIZE_UNIT(type_tree);
10464   tree space = context->gogo()->allocate_memory(this->type_, size_tree,
10465                                                 this->location());
10466   if (space == error_mark_node)
10467     return error_mark_node;
10468   return fold_convert(build_pointer_type(type_tree), space);
10469 }
10470
10471 // Make an allocation expression.
10472
10473 Expression*
10474 Expression::make_allocation(Type* type, source_location location)
10475 {
10476   return new Allocation_expression(type, location);
10477 }
10478
10479 // Implement the builtin function make.
10480
10481 class Make_expression : public Expression
10482 {
10483  public:
10484   Make_expression(Type* type, Expression_list* args, source_location location)
10485     : Expression(EXPRESSION_MAKE, location),
10486       type_(type), args_(args)
10487   { }
10488
10489  protected:
10490   int
10491   do_traverse(Traverse* traverse);
10492
10493   Type*
10494   do_type()
10495   { return this->type_; }
10496
10497   void
10498   do_determine_type(const Type_context*);
10499
10500   void
10501   do_check_types(Gogo*);
10502
10503   Expression*
10504   do_copy()
10505   {
10506     return new Make_expression(this->type_, this->args_->copy(),
10507                                this->location());
10508   }
10509
10510   tree
10511   do_get_tree(Translate_context*);
10512
10513  private:
10514   // The type we are making.
10515   Type* type_;
10516   // The arguments to pass to the make routine.
10517   Expression_list* args_;
10518 };
10519
10520 // Traversal.
10521
10522 int
10523 Make_expression::do_traverse(Traverse* traverse)
10524 {
10525   if (this->args_ != NULL
10526       && this->args_->traverse(traverse) == TRAVERSE_EXIT)
10527     return TRAVERSE_EXIT;
10528   if (Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
10529     return TRAVERSE_EXIT;
10530   return TRAVERSE_CONTINUE;
10531 }
10532
10533 // Set types of arguments.
10534
10535 void
10536 Make_expression::do_determine_type(const Type_context*)
10537 {
10538   if (this->args_ != NULL)
10539     {
10540       Type_context context(Type::lookup_integer_type("int"), false);
10541       for (Expression_list::const_iterator pe = this->args_->begin();
10542            pe != this->args_->end();
10543            ++pe)
10544         (*pe)->determine_type(&context);
10545     }
10546 }
10547
10548 // Check types for a make expression.
10549
10550 void
10551 Make_expression::do_check_types(Gogo*)
10552 {
10553   if (this->type_->channel_type() == NULL
10554       && this->type_->map_type() == NULL
10555       && (this->type_->array_type() == NULL
10556           || this->type_->array_type()->length() != NULL))
10557     this->report_error(_("invalid type for make function"));
10558   else if (!this->type_->check_make_expression(this->args_, this->location()))
10559     this->set_is_error();
10560 }
10561
10562 // Return a tree for a make expression.
10563
10564 tree
10565 Make_expression::do_get_tree(Translate_context* context)
10566 {
10567   return this->type_->make_expression_tree(context, this->args_,
10568                                            this->location());
10569 }
10570
10571 // Make a make expression.
10572
10573 Expression*
10574 Expression::make_make(Type* type, Expression_list* args,
10575                       source_location location)
10576 {
10577   return new Make_expression(type, args, location);
10578 }
10579
10580 // Construct a struct.
10581
10582 class Struct_construction_expression : public Expression
10583 {
10584  public:
10585   Struct_construction_expression(Type* type, Expression_list* vals,
10586                                  source_location location)
10587     : Expression(EXPRESSION_STRUCT_CONSTRUCTION, location),
10588       type_(type), vals_(vals)
10589   { }
10590
10591   // Return whether this is a constant initializer.
10592   bool
10593   is_constant_struct() const;
10594
10595  protected:
10596   int
10597   do_traverse(Traverse* traverse);
10598
10599   Type*
10600   do_type()
10601   { return this->type_; }
10602
10603   void
10604   do_determine_type(const Type_context*);
10605
10606   void
10607   do_check_types(Gogo*);
10608
10609   Expression*
10610   do_copy()
10611   {
10612     return new Struct_construction_expression(this->type_, this->vals_->copy(),
10613                                               this->location());
10614   }
10615
10616   bool
10617   do_is_addressable() const
10618   { return true; }
10619
10620   tree
10621   do_get_tree(Translate_context*);
10622
10623   void
10624   do_export(Export*) const;
10625
10626  private:
10627   // The type of the struct to construct.
10628   Type* type_;
10629   // The list of values, in order of the fields in the struct.  A NULL
10630   // entry means that the field should be zero-initialized.
10631   Expression_list* vals_;
10632 };
10633
10634 // Traversal.
10635
10636 int
10637 Struct_construction_expression::do_traverse(Traverse* traverse)
10638 {
10639   if (this->vals_ != NULL
10640       && this->vals_->traverse(traverse) == TRAVERSE_EXIT)
10641     return TRAVERSE_EXIT;
10642   if (Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
10643     return TRAVERSE_EXIT;
10644   return TRAVERSE_CONTINUE;
10645 }
10646
10647 // Return whether this is a constant initializer.
10648
10649 bool
10650 Struct_construction_expression::is_constant_struct() const
10651 {
10652   if (this->vals_ == NULL)
10653     return true;
10654   for (Expression_list::const_iterator pv = this->vals_->begin();
10655        pv != this->vals_->end();
10656        ++pv)
10657     {
10658       if (*pv != NULL
10659           && !(*pv)->is_constant()
10660           && (!(*pv)->is_composite_literal()
10661               || (*pv)->is_nonconstant_composite_literal()))
10662         return false;
10663     }
10664
10665   const Struct_field_list* fields = this->type_->struct_type()->fields();
10666   for (Struct_field_list::const_iterator pf = fields->begin();
10667        pf != fields->end();
10668        ++pf)
10669     {
10670       // There are no constant constructors for interfaces.
10671       if (pf->type()->interface_type() != NULL)
10672         return false;
10673     }
10674
10675   return true;
10676 }
10677
10678 // Final type determination.
10679
10680 void
10681 Struct_construction_expression::do_determine_type(const Type_context*)
10682 {
10683   if (this->vals_ == NULL)
10684     return;
10685   const Struct_field_list* fields = this->type_->struct_type()->fields();
10686   Expression_list::const_iterator pv = this->vals_->begin();
10687   for (Struct_field_list::const_iterator pf = fields->begin();
10688        pf != fields->end();
10689        ++pf, ++pv)
10690     {
10691       if (pv == this->vals_->end())
10692         return;
10693       if (*pv != NULL)
10694         {
10695           Type_context subcontext(pf->type(), false);
10696           (*pv)->determine_type(&subcontext);
10697         }
10698     }
10699   // Extra values are an error we will report elsewhere; we still want
10700   // to determine the type to avoid knockon errors.
10701   for (; pv != this->vals_->end(); ++pv)
10702     (*pv)->determine_type_no_context();
10703 }
10704
10705 // Check types.
10706
10707 void
10708 Struct_construction_expression::do_check_types(Gogo*)
10709 {
10710   if (this->vals_ == NULL)
10711     return;
10712
10713   Struct_type* st = this->type_->struct_type();
10714   if (this->vals_->size() > st->field_count())
10715     {
10716       this->report_error(_("too many expressions for struct"));
10717       return;
10718     }
10719
10720   const Struct_field_list* fields = st->fields();
10721   Expression_list::const_iterator pv = this->vals_->begin();
10722   int i = 0;
10723   for (Struct_field_list::const_iterator pf = fields->begin();
10724        pf != fields->end();
10725        ++pf, ++pv, ++i)
10726     {
10727       if (pv == this->vals_->end())
10728         {
10729           this->report_error(_("too few expressions for struct"));
10730           break;
10731         }
10732
10733       if (*pv == NULL)
10734         continue;
10735
10736       std::string reason;
10737       if (!Type::are_assignable(pf->type(), (*pv)->type(), &reason))
10738         {
10739           if (reason.empty())
10740             error_at((*pv)->location(),
10741                      "incompatible type for field %d in struct construction",
10742                      i + 1);
10743           else
10744             error_at((*pv)->location(),
10745                      ("incompatible type for field %d in "
10746                       "struct construction (%s)"),
10747                      i + 1, reason.c_str());
10748           this->set_is_error();
10749         }
10750     }
10751   gcc_assert(pv == this->vals_->end());
10752 }
10753
10754 // Return a tree for constructing a struct.
10755
10756 tree
10757 Struct_construction_expression::do_get_tree(Translate_context* context)
10758 {
10759   Gogo* gogo = context->gogo();
10760
10761   if (this->vals_ == NULL)
10762     return this->type_->get_init_tree(gogo, false);
10763
10764   tree type_tree = this->type_->get_tree(gogo);
10765   if (type_tree == error_mark_node)
10766     return error_mark_node;
10767   gcc_assert(TREE_CODE(type_tree) == RECORD_TYPE);
10768
10769   bool is_constant = true;
10770   const Struct_field_list* fields = this->type_->struct_type()->fields();
10771   VEC(constructor_elt,gc)* elts = VEC_alloc(constructor_elt, gc,
10772                                             fields->size());
10773   Struct_field_list::const_iterator pf = fields->begin();
10774   Expression_list::const_iterator pv = this->vals_->begin();
10775   for (tree field = TYPE_FIELDS(type_tree);
10776        field != NULL_TREE;
10777        field = DECL_CHAIN(field), ++pf)
10778     {
10779       gcc_assert(pf != fields->end());
10780
10781       tree val;
10782       if (pv == this->vals_->end())
10783         val = pf->type()->get_init_tree(gogo, false);
10784       else if (*pv == NULL)
10785         {
10786           val = pf->type()->get_init_tree(gogo, false);
10787           ++pv;
10788         }
10789       else
10790         {
10791           val = Expression::convert_for_assignment(context, pf->type(),
10792                                                    (*pv)->type(),
10793                                                    (*pv)->get_tree(context),
10794                                                    this->location());
10795           ++pv;
10796         }
10797
10798       if (val == error_mark_node || TREE_TYPE(val) == error_mark_node)
10799         return error_mark_node;
10800
10801       constructor_elt* elt = VEC_quick_push(constructor_elt, elts, NULL);
10802       elt->index = field;
10803       elt->value = val;
10804       if (!TREE_CONSTANT(val))
10805         is_constant = false;
10806     }
10807   gcc_assert(pf == fields->end());
10808
10809   tree ret = build_constructor(type_tree, elts);
10810   if (is_constant)
10811     TREE_CONSTANT(ret) = 1;
10812   return ret;
10813 }
10814
10815 // Export a struct construction.
10816
10817 void
10818 Struct_construction_expression::do_export(Export* exp) const
10819 {
10820   exp->write_c_string("convert(");
10821   exp->write_type(this->type_);
10822   for (Expression_list::const_iterator pv = this->vals_->begin();
10823        pv != this->vals_->end();
10824        ++pv)
10825     {
10826       exp->write_c_string(", ");
10827       if (*pv != NULL)
10828         (*pv)->export_expression(exp);
10829     }
10830   exp->write_c_string(")");
10831 }
10832
10833 // Make a struct composite literal.  This used by the thunk code.
10834
10835 Expression*
10836 Expression::make_struct_composite_literal(Type* type, Expression_list* vals,
10837                                           source_location location)
10838 {
10839   gcc_assert(type->struct_type() != NULL);
10840   return new Struct_construction_expression(type, vals, location);
10841 }
10842
10843 // Construct an array.  This class is not used directly; instead we
10844 // use the child classes, Fixed_array_construction_expression and
10845 // Open_array_construction_expression.
10846
10847 class Array_construction_expression : public Expression
10848 {
10849  protected:
10850   Array_construction_expression(Expression_classification classification,
10851                                 Type* type, Expression_list* vals,
10852                                 source_location location)
10853     : Expression(classification, location),
10854       type_(type), vals_(vals)
10855   { }
10856
10857  public:
10858   // Return whether this is a constant initializer.
10859   bool
10860   is_constant_array() const;
10861
10862   // Return the number of elements.
10863   size_t
10864   element_count() const
10865   { return this->vals_ == NULL ? 0 : this->vals_->size(); }
10866
10867 protected:
10868   int
10869   do_traverse(Traverse* traverse);
10870
10871   Type*
10872   do_type()
10873   { return this->type_; }
10874
10875   void
10876   do_determine_type(const Type_context*);
10877
10878   void
10879   do_check_types(Gogo*);
10880
10881   bool
10882   do_is_addressable() const
10883   { return true; }
10884
10885   void
10886   do_export(Export*) const;
10887
10888   // The list of values.
10889   Expression_list*
10890   vals()
10891   { return this->vals_; }
10892
10893   // Get a constructor tree for the array values.
10894   tree
10895   get_constructor_tree(Translate_context* context, tree type_tree);
10896
10897  private:
10898   // The type of the array to construct.
10899   Type* type_;
10900   // The list of values.
10901   Expression_list* vals_;
10902 };
10903
10904 // Traversal.
10905
10906 int
10907 Array_construction_expression::do_traverse(Traverse* traverse)
10908 {
10909   if (this->vals_ != NULL
10910       && this->vals_->traverse(traverse) == TRAVERSE_EXIT)
10911     return TRAVERSE_EXIT;
10912   if (Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
10913     return TRAVERSE_EXIT;
10914   return TRAVERSE_CONTINUE;
10915 }
10916
10917 // Return whether this is a constant initializer.
10918
10919 bool
10920 Array_construction_expression::is_constant_array() const
10921 {
10922   if (this->vals_ == NULL)
10923     return true;
10924
10925   // There are no constant constructors for interfaces.
10926   if (this->type_->array_type()->element_type()->interface_type() != NULL)
10927     return false;
10928
10929   for (Expression_list::const_iterator pv = this->vals_->begin();
10930        pv != this->vals_->end();
10931        ++pv)
10932     {
10933       if (*pv != NULL
10934           && !(*pv)->is_constant()
10935           && (!(*pv)->is_composite_literal()
10936               || (*pv)->is_nonconstant_composite_literal()))
10937         return false;
10938     }
10939   return true;
10940 }
10941
10942 // Final type determination.
10943
10944 void
10945 Array_construction_expression::do_determine_type(const Type_context*)
10946 {
10947   if (this->vals_ == NULL)
10948     return;
10949   Type_context subcontext(this->type_->array_type()->element_type(), false);
10950   for (Expression_list::const_iterator pv = this->vals_->begin();
10951        pv != this->vals_->end();
10952        ++pv)
10953     {
10954       if (*pv != NULL)
10955         (*pv)->determine_type(&subcontext);
10956     }
10957 }
10958
10959 // Check types.
10960
10961 void
10962 Array_construction_expression::do_check_types(Gogo*)
10963 {
10964   if (this->vals_ == NULL)
10965     return;
10966
10967   Array_type* at = this->type_->array_type();
10968   int i = 0;
10969   Type* element_type = at->element_type();
10970   for (Expression_list::const_iterator pv = this->vals_->begin();
10971        pv != this->vals_->end();
10972        ++pv, ++i)
10973     {
10974       if (*pv != NULL
10975           && !Type::are_assignable(element_type, (*pv)->type(), NULL))
10976         {
10977           error_at((*pv)->location(),
10978                    "incompatible type for element %d in composite literal",
10979                    i + 1);
10980           this->set_is_error();
10981         }
10982     }
10983
10984   Expression* length = at->length();
10985   if (length != NULL)
10986     {
10987       mpz_t val;
10988       mpz_init(val);
10989       Type* type;
10990       if (at->length()->integer_constant_value(true, val, &type))
10991         {
10992           if (this->vals_->size() > mpz_get_ui(val))
10993             this->report_error(_("too many elements in composite literal"));
10994         }
10995       mpz_clear(val);
10996     }
10997 }
10998
10999 // Get a constructor tree for the array values.
11000
11001 tree
11002 Array_construction_expression::get_constructor_tree(Translate_context* context,
11003                                                     tree type_tree)
11004 {
11005   VEC(constructor_elt,gc)* values = VEC_alloc(constructor_elt, gc,
11006                                               (this->vals_ == NULL
11007                                                ? 0
11008                                                : this->vals_->size()));
11009   Type* element_type = this->type_->array_type()->element_type();
11010   bool is_constant = true;
11011   if (this->vals_ != NULL)
11012     {
11013       size_t i = 0;
11014       for (Expression_list::const_iterator pv = this->vals_->begin();
11015            pv != this->vals_->end();
11016            ++pv, ++i)
11017         {
11018           constructor_elt* elt = VEC_quick_push(constructor_elt, values, NULL);
11019           elt->index = size_int(i);
11020           if (*pv == NULL)
11021             elt->value = element_type->get_init_tree(context->gogo(), false);
11022           else
11023             {
11024               tree value_tree = (*pv)->get_tree(context);
11025               elt->value = Expression::convert_for_assignment(context,
11026                                                               element_type,
11027                                                               (*pv)->type(),
11028                                                               value_tree,
11029                                                               this->location());
11030             }
11031           if (elt->value == error_mark_node)
11032             return error_mark_node;
11033           if (!TREE_CONSTANT(elt->value))
11034             is_constant = false;
11035         }
11036     }
11037
11038   tree ret = build_constructor(type_tree, values);
11039   if (is_constant)
11040     TREE_CONSTANT(ret) = 1;
11041   return ret;
11042 }
11043
11044 // Export an array construction.
11045
11046 void
11047 Array_construction_expression::do_export(Export* exp) const
11048 {
11049   exp->write_c_string("convert(");
11050   exp->write_type(this->type_);
11051   if (this->vals_ != NULL)
11052     {
11053       for (Expression_list::const_iterator pv = this->vals_->begin();
11054            pv != this->vals_->end();
11055            ++pv)
11056         {
11057           exp->write_c_string(", ");
11058           if (*pv != NULL)
11059             (*pv)->export_expression(exp);
11060         }
11061     }
11062   exp->write_c_string(")");
11063 }
11064
11065 // Construct a fixed array.
11066
11067 class Fixed_array_construction_expression :
11068   public Array_construction_expression
11069 {
11070  public:
11071   Fixed_array_construction_expression(Type* type, Expression_list* vals,
11072                                       source_location location)
11073     : Array_construction_expression(EXPRESSION_FIXED_ARRAY_CONSTRUCTION,
11074                                     type, vals, location)
11075   {
11076     gcc_assert(type->array_type() != NULL
11077                && type->array_type()->length() != NULL);
11078   }
11079
11080  protected:
11081   Expression*
11082   do_copy()
11083   {
11084     return new Fixed_array_construction_expression(this->type(),
11085                                                    (this->vals() == NULL
11086                                                     ? NULL
11087                                                     : this->vals()->copy()),
11088                                                    this->location());
11089   }
11090
11091   tree
11092   do_get_tree(Translate_context*);
11093 };
11094
11095 // Return a tree for constructing a fixed array.
11096
11097 tree
11098 Fixed_array_construction_expression::do_get_tree(Translate_context* context)
11099 {
11100   return this->get_constructor_tree(context,
11101                                     this->type()->get_tree(context->gogo()));
11102 }
11103
11104 // Construct an open array.
11105
11106 class Open_array_construction_expression : public Array_construction_expression
11107 {
11108  public:
11109   Open_array_construction_expression(Type* type, Expression_list* vals,
11110                                      source_location location)
11111     : Array_construction_expression(EXPRESSION_OPEN_ARRAY_CONSTRUCTION,
11112                                     type, vals, location)
11113   {
11114     gcc_assert(type->array_type() != NULL
11115                && type->array_type()->length() == NULL);
11116   }
11117
11118  protected:
11119   // Note that taking the address of an open array literal is invalid.
11120
11121   Expression*
11122   do_copy()
11123   {
11124     return new Open_array_construction_expression(this->type(),
11125                                                   (this->vals() == NULL
11126                                                    ? NULL
11127                                                    : this->vals()->copy()),
11128                                                   this->location());
11129   }
11130
11131   tree
11132   do_get_tree(Translate_context*);
11133 };
11134
11135 // Return a tree for constructing an open array.
11136
11137 tree
11138 Open_array_construction_expression::do_get_tree(Translate_context* context)
11139 {
11140   Array_type* array_type = this->type()->array_type();
11141   if (array_type == NULL)
11142     {
11143       gcc_assert(this->type()->is_error_type());
11144       return error_mark_node;
11145     }
11146
11147   Type* element_type = array_type->element_type();
11148   tree element_type_tree = element_type->get_tree(context->gogo());
11149   if (element_type_tree == error_mark_node)
11150     return error_mark_node;
11151
11152   tree values;
11153   tree length_tree;
11154   if (this->vals() == NULL || this->vals()->empty())
11155     {
11156       // We need to create a unique value.
11157       tree max = size_int(0);
11158       tree constructor_type = build_array_type(element_type_tree,
11159                                                build_index_type(max));
11160       if (constructor_type == error_mark_node)
11161         return error_mark_node;
11162       VEC(constructor_elt,gc)* vec = VEC_alloc(constructor_elt, gc, 1);
11163       constructor_elt* elt = VEC_quick_push(constructor_elt, vec, NULL);
11164       elt->index = size_int(0);
11165       elt->value = element_type->get_init_tree(context->gogo(), false);
11166       values = build_constructor(constructor_type, vec);
11167       if (TREE_CONSTANT(elt->value))
11168         TREE_CONSTANT(values) = 1;
11169       length_tree = size_int(0);
11170     }
11171   else
11172     {
11173       tree max = size_int(this->vals()->size() - 1);
11174       tree constructor_type = build_array_type(element_type_tree,
11175                                                build_index_type(max));
11176       if (constructor_type == error_mark_node)
11177         return error_mark_node;
11178       values = this->get_constructor_tree(context, constructor_type);
11179       length_tree = size_int(this->vals()->size());
11180     }
11181
11182   if (values == error_mark_node)
11183     return error_mark_node;
11184
11185   bool is_constant_initializer = TREE_CONSTANT(values);
11186
11187   // We have to copy the initial values into heap memory if we are in
11188   // a function or if the values are not constants.  We also have to
11189   // copy them if they may contain pointers in a non-constant context,
11190   // as otherwise the garbage collector won't see them.
11191   bool copy_to_heap = (context->function() != NULL
11192                        || !is_constant_initializer
11193                        || (element_type->has_pointer()
11194                            && !context->is_const()));
11195
11196   if (is_constant_initializer)
11197     {
11198       tree tmp = build_decl(this->location(), VAR_DECL,
11199                             create_tmp_var_name("C"), TREE_TYPE(values));
11200       DECL_EXTERNAL(tmp) = 0;
11201       TREE_PUBLIC(tmp) = 0;
11202       TREE_STATIC(tmp) = 1;
11203       DECL_ARTIFICIAL(tmp) = 1;
11204       if (copy_to_heap)
11205         {
11206           // If we are not copying the value to the heap, we will only
11207           // initialize the value once, so we can use this directly
11208           // rather than copying it.  In that case we can't make it
11209           // read-only, because the program is permitted to change it.
11210           TREE_READONLY(tmp) = 1;
11211           TREE_CONSTANT(tmp) = 1;
11212         }
11213       DECL_INITIAL(tmp) = values;
11214       rest_of_decl_compilation(tmp, 1, 0);
11215       values = tmp;
11216     }
11217
11218   tree space;
11219   tree set;
11220   if (!copy_to_heap)
11221     {
11222       // the initializer will only run once.
11223       space = build_fold_addr_expr(values);
11224       set = NULL_TREE;
11225     }
11226   else
11227     {
11228       tree memsize = TYPE_SIZE_UNIT(TREE_TYPE(values));
11229       space = context->gogo()->allocate_memory(element_type, memsize,
11230                                                this->location());
11231       space = save_expr(space);
11232
11233       tree s = fold_convert(build_pointer_type(TREE_TYPE(values)), space);
11234       tree ref = build_fold_indirect_ref_loc(this->location(), s);
11235       TREE_THIS_NOTRAP(ref) = 1;
11236       set = build2(MODIFY_EXPR, void_type_node, ref, values);
11237     }
11238
11239   // Build a constructor for the open array.
11240
11241   tree type_tree = this->type()->get_tree(context->gogo());
11242   if (type_tree == error_mark_node)
11243     return error_mark_node;
11244   gcc_assert(TREE_CODE(type_tree) == RECORD_TYPE);
11245
11246   VEC(constructor_elt,gc)* init = VEC_alloc(constructor_elt, gc, 3);
11247
11248   constructor_elt* elt = VEC_quick_push(constructor_elt, init, NULL);
11249   tree field = TYPE_FIELDS(type_tree);
11250   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__values") == 0);
11251   elt->index = field;
11252   elt->value = fold_convert(TREE_TYPE(field), space);
11253
11254   elt = VEC_quick_push(constructor_elt, init, NULL);
11255   field = DECL_CHAIN(field);
11256   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__count") == 0);
11257   elt->index = field;
11258   elt->value = fold_convert(TREE_TYPE(field), length_tree);
11259
11260   elt = VEC_quick_push(constructor_elt, init, NULL);
11261   field = DECL_CHAIN(field);
11262   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)),"__capacity") == 0);
11263   elt->index = field;
11264   elt->value = fold_convert(TREE_TYPE(field), length_tree);
11265
11266   tree constructor = build_constructor(type_tree, init);
11267   if (constructor == error_mark_node)
11268     return error_mark_node;
11269   if (!copy_to_heap)
11270     TREE_CONSTANT(constructor) = 1;
11271
11272   if (set == NULL_TREE)
11273     return constructor;
11274   else
11275     return build2(COMPOUND_EXPR, type_tree, set, constructor);
11276 }
11277
11278 // Make a slice composite literal.  This is used by the type
11279 // descriptor code.
11280
11281 Expression*
11282 Expression::make_slice_composite_literal(Type* type, Expression_list* vals,
11283                                          source_location location)
11284 {
11285   gcc_assert(type->is_open_array_type());
11286   return new Open_array_construction_expression(type, vals, location);
11287 }
11288
11289 // Construct a map.
11290
11291 class Map_construction_expression : public Expression
11292 {
11293  public:
11294   Map_construction_expression(Type* type, Expression_list* vals,
11295                               source_location location)
11296     : Expression(EXPRESSION_MAP_CONSTRUCTION, location),
11297       type_(type), vals_(vals)
11298   { gcc_assert(vals == NULL || vals->size() % 2 == 0); }
11299
11300  protected:
11301   int
11302   do_traverse(Traverse* traverse);
11303
11304   Type*
11305   do_type()
11306   { return this->type_; }
11307
11308   void
11309   do_determine_type(const Type_context*);
11310
11311   void
11312   do_check_types(Gogo*);
11313
11314   Expression*
11315   do_copy()
11316   {
11317     return new Map_construction_expression(this->type_, this->vals_->copy(),
11318                                            this->location());
11319   }
11320
11321   tree
11322   do_get_tree(Translate_context*);
11323
11324   void
11325   do_export(Export*) const;
11326
11327  private:
11328   // The type of the map to construct.
11329   Type* type_;
11330   // The list of values.
11331   Expression_list* vals_;
11332 };
11333
11334 // Traversal.
11335
11336 int
11337 Map_construction_expression::do_traverse(Traverse* traverse)
11338 {
11339   if (this->vals_ != NULL
11340       && this->vals_->traverse(traverse) == TRAVERSE_EXIT)
11341     return TRAVERSE_EXIT;
11342   if (Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
11343     return TRAVERSE_EXIT;
11344   return TRAVERSE_CONTINUE;
11345 }
11346
11347 // Final type determination.
11348
11349 void
11350 Map_construction_expression::do_determine_type(const Type_context*)
11351 {
11352   if (this->vals_ == NULL)
11353     return;
11354
11355   Map_type* mt = this->type_->map_type();
11356   Type_context key_context(mt->key_type(), false);
11357   Type_context val_context(mt->val_type(), false);
11358   for (Expression_list::const_iterator pv = this->vals_->begin();
11359        pv != this->vals_->end();
11360        ++pv)
11361     {
11362       (*pv)->determine_type(&key_context);
11363       ++pv;
11364       (*pv)->determine_type(&val_context);
11365     }
11366 }
11367
11368 // Check types.
11369
11370 void
11371 Map_construction_expression::do_check_types(Gogo*)
11372 {
11373   if (this->vals_ == NULL)
11374     return;
11375
11376   Map_type* mt = this->type_->map_type();
11377   int i = 0;
11378   Type* key_type = mt->key_type();
11379   Type* val_type = mt->val_type();
11380   for (Expression_list::const_iterator pv = this->vals_->begin();
11381        pv != this->vals_->end();
11382        ++pv, ++i)
11383     {
11384       if (!Type::are_assignable(key_type, (*pv)->type(), NULL))
11385         {
11386           error_at((*pv)->location(),
11387                    "incompatible type for element %d key in map construction",
11388                    i + 1);
11389           this->set_is_error();
11390         }
11391       ++pv;
11392       if (!Type::are_assignable(val_type, (*pv)->type(), NULL))
11393         {
11394           error_at((*pv)->location(),
11395                    ("incompatible type for element %d value "
11396                     "in map construction"),
11397                    i + 1);
11398           this->set_is_error();
11399         }
11400     }
11401 }
11402
11403 // Return a tree for constructing a map.
11404
11405 tree
11406 Map_construction_expression::do_get_tree(Translate_context* context)
11407 {
11408   Gogo* gogo = context->gogo();
11409   source_location loc = this->location();
11410
11411   Map_type* mt = this->type_->map_type();
11412
11413   // Build a struct to hold the key and value.
11414   tree struct_type = make_node(RECORD_TYPE);
11415
11416   Type* key_type = mt->key_type();
11417   tree id = get_identifier("__key");
11418   tree key_type_tree = key_type->get_tree(gogo);
11419   if (key_type_tree == error_mark_node)
11420     return error_mark_node;
11421   tree key_field = build_decl(loc, FIELD_DECL, id, key_type_tree);
11422   DECL_CONTEXT(key_field) = struct_type;
11423   TYPE_FIELDS(struct_type) = key_field;
11424
11425   Type* val_type = mt->val_type();
11426   id = get_identifier("__val");
11427   tree val_type_tree = val_type->get_tree(gogo);
11428   if (val_type_tree == error_mark_node)
11429     return error_mark_node;
11430   tree val_field = build_decl(loc, FIELD_DECL, id, val_type_tree);
11431   DECL_CONTEXT(val_field) = struct_type;
11432   DECL_CHAIN(key_field) = val_field;
11433
11434   layout_type(struct_type);
11435
11436   bool is_constant = true;
11437   size_t i = 0;
11438   tree valaddr;
11439   tree make_tmp;
11440
11441   if (this->vals_ == NULL || this->vals_->empty())
11442     {
11443       valaddr = null_pointer_node;
11444       make_tmp = NULL_TREE;
11445     }
11446   else
11447     {
11448       VEC(constructor_elt,gc)* values = VEC_alloc(constructor_elt, gc,
11449                                                   this->vals_->size() / 2);
11450
11451       for (Expression_list::const_iterator pv = this->vals_->begin();
11452            pv != this->vals_->end();
11453            ++pv, ++i)
11454         {
11455           bool one_is_constant = true;
11456
11457           VEC(constructor_elt,gc)* one = VEC_alloc(constructor_elt, gc, 2);
11458
11459           constructor_elt* elt = VEC_quick_push(constructor_elt, one, NULL);
11460           elt->index = key_field;
11461           tree val_tree = (*pv)->get_tree(context);
11462           elt->value = Expression::convert_for_assignment(context, key_type,
11463                                                           (*pv)->type(),
11464                                                           val_tree, loc);
11465           if (elt->value == error_mark_node)
11466             return error_mark_node;
11467           if (!TREE_CONSTANT(elt->value))
11468             one_is_constant = false;
11469
11470           ++pv;
11471
11472           elt = VEC_quick_push(constructor_elt, one, NULL);
11473           elt->index = val_field;
11474           val_tree = (*pv)->get_tree(context);
11475           elt->value = Expression::convert_for_assignment(context, val_type,
11476                                                           (*pv)->type(),
11477                                                           val_tree, loc);
11478           if (elt->value == error_mark_node)
11479             return error_mark_node;
11480           if (!TREE_CONSTANT(elt->value))
11481             one_is_constant = false;
11482
11483           elt = VEC_quick_push(constructor_elt, values, NULL);
11484           elt->index = size_int(i);
11485           elt->value = build_constructor(struct_type, one);
11486           if (one_is_constant)
11487             TREE_CONSTANT(elt->value) = 1;
11488           else
11489             is_constant = false;
11490         }
11491
11492       tree index_type = build_index_type(size_int(i - 1));
11493       tree array_type = build_array_type(struct_type, index_type);
11494       tree init = build_constructor(array_type, values);
11495       if (is_constant)
11496         TREE_CONSTANT(init) = 1;
11497       tree tmp;
11498       if (current_function_decl != NULL)
11499         {
11500           tmp = create_tmp_var(array_type, get_name(array_type));
11501           DECL_INITIAL(tmp) = init;
11502           make_tmp = fold_build1_loc(loc, DECL_EXPR, void_type_node, tmp);
11503           TREE_ADDRESSABLE(tmp) = 1;
11504         }
11505       else
11506         {
11507           tmp = build_decl(loc, VAR_DECL, create_tmp_var_name("M"), array_type);
11508           DECL_EXTERNAL(tmp) = 0;
11509           TREE_PUBLIC(tmp) = 0;
11510           TREE_STATIC(tmp) = 1;
11511           DECL_ARTIFICIAL(tmp) = 1;
11512           if (!TREE_CONSTANT(init))
11513             make_tmp = fold_build2_loc(loc, INIT_EXPR, void_type_node, tmp,
11514                                        init);
11515           else
11516             {
11517               TREE_READONLY(tmp) = 1;
11518               TREE_CONSTANT(tmp) = 1;
11519               DECL_INITIAL(tmp) = init;
11520               make_tmp = NULL_TREE;
11521             }
11522           rest_of_decl_compilation(tmp, 1, 0);
11523         }
11524
11525       valaddr = build_fold_addr_expr(tmp);
11526     }
11527
11528   tree descriptor = gogo->map_descriptor(mt);
11529
11530   tree type_tree = this->type_->get_tree(gogo);
11531   if (type_tree == error_mark_node)
11532     return error_mark_node;
11533
11534   static tree construct_map_fndecl;
11535   tree call = Gogo::call_builtin(&construct_map_fndecl,
11536                                  loc,
11537                                  "__go_construct_map",
11538                                  6,
11539                                  type_tree,
11540                                  TREE_TYPE(descriptor),
11541                                  descriptor,
11542                                  sizetype,
11543                                  size_int(i),
11544                                  sizetype,
11545                                  TYPE_SIZE_UNIT(struct_type),
11546                                  sizetype,
11547                                  byte_position(val_field),
11548                                  sizetype,
11549                                  TYPE_SIZE_UNIT(TREE_TYPE(val_field)),
11550                                  const_ptr_type_node,
11551                                  fold_convert(const_ptr_type_node, valaddr));
11552   if (call == error_mark_node)
11553     return error_mark_node;
11554
11555   tree ret;
11556   if (make_tmp == NULL)
11557     ret = call;
11558   else
11559     ret = fold_build2_loc(loc, COMPOUND_EXPR, type_tree, make_tmp, call);
11560   return ret;
11561 }
11562
11563 // Export an array construction.
11564
11565 void
11566 Map_construction_expression::do_export(Export* exp) const
11567 {
11568   exp->write_c_string("convert(");
11569   exp->write_type(this->type_);
11570   for (Expression_list::const_iterator pv = this->vals_->begin();
11571        pv != this->vals_->end();
11572        ++pv)
11573     {
11574       exp->write_c_string(", ");
11575       (*pv)->export_expression(exp);
11576     }
11577   exp->write_c_string(")");
11578 }
11579
11580 // A general composite literal.  This is lowered to a type specific
11581 // version.
11582
11583 class Composite_literal_expression : public Parser_expression
11584 {
11585  public:
11586   Composite_literal_expression(Type* type, int depth, bool has_keys,
11587                                Expression_list* vals, source_location location)
11588     : Parser_expression(EXPRESSION_COMPOSITE_LITERAL, location),
11589       type_(type), depth_(depth), vals_(vals), has_keys_(has_keys)
11590   { }
11591
11592  protected:
11593   int
11594   do_traverse(Traverse* traverse);
11595
11596   Expression*
11597   do_lower(Gogo*, Named_object*, int);
11598
11599   Expression*
11600   do_copy()
11601   {
11602     return new Composite_literal_expression(this->type_, this->depth_,
11603                                             this->has_keys_,
11604                                             (this->vals_ == NULL
11605                                              ? NULL
11606                                              : this->vals_->copy()),
11607                                             this->location());
11608   }
11609
11610  private:
11611   Expression*
11612   lower_struct(Gogo*, Type*);
11613
11614   Expression*
11615   lower_array(Type*);
11616
11617   Expression*
11618   make_array(Type*, Expression_list*);
11619
11620   Expression*
11621   lower_map(Gogo*, Named_object*, Type*);
11622
11623   // The type of the composite literal.
11624   Type* type_;
11625   // The depth within a list of composite literals within a composite
11626   // literal, when the type is omitted.
11627   int depth_;
11628   // The values to put in the composite literal.
11629   Expression_list* vals_;
11630   // If this is true, then VALS_ is a list of pairs: a key and a
11631   // value.  In an array initializer, a missing key will be NULL.
11632   bool has_keys_;
11633 };
11634
11635 // Traversal.
11636
11637 int
11638 Composite_literal_expression::do_traverse(Traverse* traverse)
11639 {
11640   if (this->vals_ != NULL
11641       && this->vals_->traverse(traverse) == TRAVERSE_EXIT)
11642     return TRAVERSE_EXIT;
11643   return Type::traverse(this->type_, traverse);
11644 }
11645
11646 // Lower a generic composite literal into a specific version based on
11647 // the type.
11648
11649 Expression*
11650 Composite_literal_expression::do_lower(Gogo* gogo, Named_object* function, int)
11651 {
11652   Type* type = this->type_;
11653
11654   for (int depth = this->depth_; depth > 0; --depth)
11655     {
11656       if (type->array_type() != NULL)
11657         type = type->array_type()->element_type();
11658       else if (type->map_type() != NULL)
11659         type = type->map_type()->val_type();
11660       else
11661         {
11662           if (!type->is_error_type())
11663             error_at(this->location(),
11664                      ("may only omit types within composite literals "
11665                       "of slice, array, or map type"));
11666           return Expression::make_error(this->location());
11667         }
11668     }
11669
11670   if (type->is_error_type())
11671     return Expression::make_error(this->location());
11672   else if (type->struct_type() != NULL)
11673     return this->lower_struct(gogo, type);
11674   else if (type->array_type() != NULL)
11675     return this->lower_array(type);
11676   else if (type->map_type() != NULL)
11677     return this->lower_map(gogo, function, type);
11678   else
11679     {
11680       error_at(this->location(),
11681                ("expected struct, slice, array, or map type "
11682                 "for composite literal"));
11683       return Expression::make_error(this->location());
11684     }
11685 }
11686
11687 // Lower a struct composite literal.
11688
11689 Expression*
11690 Composite_literal_expression::lower_struct(Gogo* gogo, Type* type)
11691 {
11692   source_location location = this->location();
11693   Struct_type* st = type->struct_type();
11694   if (this->vals_ == NULL || !this->has_keys_)
11695     return new Struct_construction_expression(type, this->vals_, location);
11696
11697   size_t field_count = st->field_count();
11698   std::vector<Expression*> vals(field_count);
11699   Expression_list::const_iterator p = this->vals_->begin();
11700   while (p != this->vals_->end())
11701     {
11702       Expression* name_expr = *p;
11703
11704       ++p;
11705       gcc_assert(p != this->vals_->end());
11706       Expression* val = *p;
11707
11708       ++p;
11709
11710       if (name_expr == NULL)
11711         {
11712           error_at(val->location(), "mixture of field and value initializers");
11713           return Expression::make_error(location);
11714         }
11715
11716       bool bad_key = false;
11717       std::string name;
11718       const Named_object* no = NULL;
11719       switch (name_expr->classification())
11720         {
11721         case EXPRESSION_UNKNOWN_REFERENCE:
11722           name = name_expr->unknown_expression()->name();
11723           break;
11724
11725         case EXPRESSION_CONST_REFERENCE:
11726           no = static_cast<Const_expression*>(name_expr)->named_object();
11727           break;
11728
11729         case EXPRESSION_TYPE:
11730           {
11731             Type* t = name_expr->type();
11732             Named_type* nt = t->named_type();
11733             if (nt == NULL)
11734               bad_key = true;
11735             else
11736               no = nt->named_object();
11737           }
11738           break;
11739
11740         case EXPRESSION_VAR_REFERENCE:
11741           no = name_expr->var_expression()->named_object();
11742           break;
11743
11744         case EXPRESSION_FUNC_REFERENCE:
11745           no = name_expr->func_expression()->named_object();
11746           break;
11747
11748         case EXPRESSION_UNARY:
11749           // If there is a local variable around with the same name as
11750           // the field, and this occurs in the closure, then the
11751           // parser may turn the field reference into an indirection
11752           // through the closure.  FIXME: This is a mess.
11753           {
11754             bad_key = true;
11755             Unary_expression* ue = static_cast<Unary_expression*>(name_expr);
11756             if (ue->op() == OPERATOR_MULT)
11757               {
11758                 Field_reference_expression* fre =
11759                   ue->operand()->field_reference_expression();
11760                 if (fre != NULL)
11761                   {
11762                     Struct_type* st =
11763                       fre->expr()->type()->deref()->struct_type();
11764                     if (st != NULL)
11765                       {
11766                         const Struct_field* sf = st->field(fre->field_index());
11767                         name = sf->field_name();
11768                         char buf[20];
11769                         snprintf(buf, sizeof buf, "%u", fre->field_index());
11770                         size_t buflen = strlen(buf);
11771                         if (name.compare(name.length() - buflen, buflen, buf)
11772                             == 0)
11773                           {
11774                             name = name.substr(0, name.length() - buflen);
11775                             bad_key = false;
11776                           }
11777                       }
11778                   }
11779               }
11780           }
11781           break;
11782
11783         default:
11784           bad_key = true;
11785           break;
11786         }
11787       if (bad_key)
11788         {
11789           error_at(name_expr->location(), "expected struct field name");
11790           return Expression::make_error(location);
11791         }
11792
11793       if (no != NULL)
11794         {
11795           name = no->name();
11796
11797           // A predefined name won't be packed.  If it starts with a
11798           // lower case letter we need to check for that case, because
11799           // the field name will be packed.
11800           if (!Gogo::is_hidden_name(name)
11801               && name[0] >= 'a'
11802               && name[0] <= 'z')
11803             {
11804               Named_object* gno = gogo->lookup_global(name.c_str());
11805               if (gno == no)
11806                 name = gogo->pack_hidden_name(name, false);
11807             }
11808         }
11809
11810       unsigned int index;
11811       const Struct_field* sf = st->find_local_field(name, &index);
11812       if (sf == NULL)
11813         {
11814           error_at(name_expr->location(), "unknown field %qs in %qs",
11815                    Gogo::message_name(name).c_str(),
11816                    (type->named_type() != NULL
11817                     ? type->named_type()->message_name().c_str()
11818                     : "unnamed struct"));
11819           return Expression::make_error(location);
11820         }
11821       if (vals[index] != NULL)
11822         {
11823           error_at(name_expr->location(),
11824                    "duplicate value for field %qs in %qs",
11825                    Gogo::message_name(name).c_str(),
11826                    (type->named_type() != NULL
11827                     ? type->named_type()->message_name().c_str()
11828                     : "unnamed struct"));
11829           return Expression::make_error(location);
11830         }
11831
11832       vals[index] = val;
11833     }
11834
11835   Expression_list* list = new Expression_list;
11836   list->reserve(field_count);
11837   for (size_t i = 0; i < field_count; ++i)
11838     list->push_back(vals[i]);
11839
11840   return new Struct_construction_expression(type, list, location);
11841 }
11842
11843 // Lower an array composite literal.
11844
11845 Expression*
11846 Composite_literal_expression::lower_array(Type* type)
11847 {
11848   source_location location = this->location();
11849   if (this->vals_ == NULL || !this->has_keys_)
11850     return this->make_array(type, this->vals_);
11851
11852   std::vector<Expression*> vals;
11853   vals.reserve(this->vals_->size());
11854   unsigned long index = 0;
11855   Expression_list::const_iterator p = this->vals_->begin();
11856   while (p != this->vals_->end())
11857     {
11858       Expression* index_expr = *p;
11859
11860       ++p;
11861       gcc_assert(p != this->vals_->end());
11862       Expression* val = *p;
11863
11864       ++p;
11865
11866       if (index_expr != NULL)
11867         {
11868           mpz_t ival;
11869           mpz_init(ival);
11870
11871           Type* dummy;
11872           if (!index_expr->integer_constant_value(true, ival, &dummy))
11873             {
11874               mpz_clear(ival);
11875               error_at(index_expr->location(),
11876                        "index expression is not integer constant");
11877               return Expression::make_error(location);
11878             }
11879
11880           if (mpz_sgn(ival) < 0)
11881             {
11882               mpz_clear(ival);
11883               error_at(index_expr->location(), "index expression is negative");
11884               return Expression::make_error(location);
11885             }
11886
11887           index = mpz_get_ui(ival);
11888           if (mpz_cmp_ui(ival, index) != 0)
11889             {
11890               mpz_clear(ival);
11891               error_at(index_expr->location(), "index value overflow");
11892               return Expression::make_error(location);
11893             }
11894
11895           Named_type* ntype = Type::lookup_integer_type("int");
11896           Integer_type* inttype = ntype->integer_type();
11897           mpz_t max;
11898           mpz_init_set_ui(max, 1);
11899           mpz_mul_2exp(max, max, inttype->bits() - 1);
11900           bool ok = mpz_cmp(ival, max) < 0;
11901           mpz_clear(max);
11902           if (!ok)
11903             {
11904               mpz_clear(ival);
11905               error_at(index_expr->location(), "index value overflow");
11906               return Expression::make_error(location);
11907             }
11908
11909           mpz_clear(ival);
11910
11911           // FIXME: Our representation isn't very good; this avoids
11912           // thrashing.
11913           if (index > 0x1000000)
11914             {
11915               error_at(index_expr->location(), "index too large for compiler");
11916               return Expression::make_error(location);
11917             }
11918         }
11919
11920       if (index == vals.size())
11921         vals.push_back(val);
11922       else
11923         {
11924           if (index > vals.size())
11925             {
11926               vals.reserve(index + 32);
11927               vals.resize(index + 1, static_cast<Expression*>(NULL));
11928             }
11929           if (vals[index] != NULL)
11930             {
11931               error_at((index_expr != NULL
11932                         ? index_expr->location()
11933                         : val->location()),
11934                        "duplicate value for index %lu",
11935                        index);
11936               return Expression::make_error(location);
11937             }
11938           vals[index] = val;
11939         }
11940
11941       ++index;
11942     }
11943
11944   size_t size = vals.size();
11945   Expression_list* list = new Expression_list;
11946   list->reserve(size);
11947   for (size_t i = 0; i < size; ++i)
11948     list->push_back(vals[i]);
11949
11950   return this->make_array(type, list);
11951 }
11952
11953 // Actually build the array composite literal. This handles
11954 // [...]{...}.
11955
11956 Expression*
11957 Composite_literal_expression::make_array(Type* type, Expression_list* vals)
11958 {
11959   source_location location = this->location();
11960   Array_type* at = type->array_type();
11961   if (at->length() != NULL && at->length()->is_nil_expression())
11962     {
11963       size_t size = vals == NULL ? 0 : vals->size();
11964       mpz_t vlen;
11965       mpz_init_set_ui(vlen, size);
11966       Expression* elen = Expression::make_integer(&vlen, NULL, location);
11967       mpz_clear(vlen);
11968       at = Type::make_array_type(at->element_type(), elen);
11969       type = at;
11970     }
11971   if (at->length() != NULL)
11972     return new Fixed_array_construction_expression(type, vals, location);
11973   else
11974     return new Open_array_construction_expression(type, vals, location);
11975 }
11976
11977 // Lower a map composite literal.
11978
11979 Expression*
11980 Composite_literal_expression::lower_map(Gogo* gogo, Named_object* function,
11981                                         Type* type)
11982 {
11983   source_location location = this->location();
11984   if (this->vals_ != NULL)
11985     {
11986       if (!this->has_keys_)
11987         {
11988           error_at(location, "map composite literal must have keys");
11989           return Expression::make_error(location);
11990         }
11991
11992       for (Expression_list::iterator p = this->vals_->begin();
11993            p != this->vals_->end();
11994            p += 2)
11995         {
11996           if (*p == NULL)
11997             {
11998               ++p;
11999               error_at((*p)->location(),
12000                        "map composite literal must have keys for every value");
12001               return Expression::make_error(location);
12002             }
12003           // Make sure we have lowered the key; it may not have been
12004           // lowered in order to handle keys for struct composite
12005           // literals.  Lower it now to get the right error message.
12006           if ((*p)->unknown_expression() != NULL)
12007             {
12008               (*p)->unknown_expression()->clear_is_composite_literal_key();
12009               gogo->lower_expression(function, &*p);
12010               gcc_assert((*p)->is_error_expression());
12011               return Expression::make_error(location);
12012             }
12013         }
12014     }
12015
12016   return new Map_construction_expression(type, this->vals_, location);
12017 }
12018
12019 // Make a composite literal expression.
12020
12021 Expression*
12022 Expression::make_composite_literal(Type* type, int depth, bool has_keys,
12023                                    Expression_list* vals,
12024                                    source_location location)
12025 {
12026   return new Composite_literal_expression(type, depth, has_keys, vals,
12027                                           location);
12028 }
12029
12030 // Return whether this expression is a composite literal.
12031
12032 bool
12033 Expression::is_composite_literal() const
12034 {
12035   switch (this->classification_)
12036     {
12037     case EXPRESSION_COMPOSITE_LITERAL:
12038     case EXPRESSION_STRUCT_CONSTRUCTION:
12039     case EXPRESSION_FIXED_ARRAY_CONSTRUCTION:
12040     case EXPRESSION_OPEN_ARRAY_CONSTRUCTION:
12041     case EXPRESSION_MAP_CONSTRUCTION:
12042       return true;
12043     default:
12044       return false;
12045     }
12046 }
12047
12048 // Return whether this expression is a composite literal which is not
12049 // constant.
12050
12051 bool
12052 Expression::is_nonconstant_composite_literal() const
12053 {
12054   switch (this->classification_)
12055     {
12056     case EXPRESSION_STRUCT_CONSTRUCTION:
12057       {
12058         const Struct_construction_expression *psce =
12059           static_cast<const Struct_construction_expression*>(this);
12060         return !psce->is_constant_struct();
12061       }
12062     case EXPRESSION_FIXED_ARRAY_CONSTRUCTION:
12063       {
12064         const Fixed_array_construction_expression *pace =
12065           static_cast<const Fixed_array_construction_expression*>(this);
12066         return !pace->is_constant_array();
12067       }
12068     case EXPRESSION_OPEN_ARRAY_CONSTRUCTION:
12069       {
12070         const Open_array_construction_expression *pace =
12071           static_cast<const Open_array_construction_expression*>(this);
12072         return !pace->is_constant_array();
12073       }
12074     case EXPRESSION_MAP_CONSTRUCTION:
12075       return true;
12076     default:
12077       return false;
12078     }
12079 }
12080
12081 // Return true if this is a reference to a local variable.
12082
12083 bool
12084 Expression::is_local_variable() const
12085 {
12086   const Var_expression* ve = this->var_expression();
12087   if (ve == NULL)
12088     return false;
12089   const Named_object* no = ve->named_object();
12090   return (no->is_result_variable()
12091           || (no->is_variable() && !no->var_value()->is_global()));
12092 }
12093
12094 // Class Type_guard_expression.
12095
12096 // Traversal.
12097
12098 int
12099 Type_guard_expression::do_traverse(Traverse* traverse)
12100 {
12101   if (Expression::traverse(&this->expr_, traverse) == TRAVERSE_EXIT
12102       || Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
12103     return TRAVERSE_EXIT;
12104   return TRAVERSE_CONTINUE;
12105 }
12106
12107 // Check types of a type guard expression.  The expression must have
12108 // an interface type, but the actual type conversion is checked at run
12109 // time.
12110
12111 void
12112 Type_guard_expression::do_check_types(Gogo*)
12113 {
12114   // 6g permits using a type guard with unsafe.pointer; we are
12115   // compatible.
12116   Type* expr_type = this->expr_->type();
12117   if (expr_type->is_unsafe_pointer_type())
12118     {
12119       if (this->type_->points_to() == NULL
12120           && (this->type_->integer_type() == NULL
12121               || (this->type_->forwarded()
12122                   != Type::lookup_integer_type("uintptr"))))
12123         this->report_error(_("invalid unsafe.Pointer conversion"));
12124     }
12125   else if (this->type_->is_unsafe_pointer_type())
12126     {
12127       if (expr_type->points_to() == NULL
12128           && (expr_type->integer_type() == NULL
12129               || (expr_type->forwarded()
12130                   != Type::lookup_integer_type("uintptr"))))
12131         this->report_error(_("invalid unsafe.Pointer conversion"));
12132     }
12133   else if (expr_type->interface_type() == NULL)
12134     {
12135       if (!expr_type->is_error_type() && !this->type_->is_error_type())
12136         this->report_error(_("type assertion only valid for interface types"));
12137       this->set_is_error();
12138     }
12139   else if (this->type_->interface_type() == NULL)
12140     {
12141       std::string reason;
12142       if (!expr_type->interface_type()->implements_interface(this->type_,
12143                                                              &reason))
12144         {
12145           if (!this->type_->is_error_type())
12146             {
12147               if (reason.empty())
12148                 this->report_error(_("impossible type assertion: "
12149                                      "type does not implement interface"));
12150               else
12151                 error_at(this->location(),
12152                          ("impossible type assertion: "
12153                           "type does not implement interface (%s)"),
12154                          reason.c_str());
12155             }
12156           this->set_is_error();
12157         }
12158     }
12159 }
12160
12161 // Return a tree for a type guard expression.
12162
12163 tree
12164 Type_guard_expression::do_get_tree(Translate_context* context)
12165 {
12166   Gogo* gogo = context->gogo();
12167   tree expr_tree = this->expr_->get_tree(context);
12168   if (expr_tree == error_mark_node)
12169     return error_mark_node;
12170   Type* expr_type = this->expr_->type();
12171   if ((this->type_->is_unsafe_pointer_type()
12172        && (expr_type->points_to() != NULL
12173            || expr_type->integer_type() != NULL))
12174       || (expr_type->is_unsafe_pointer_type()
12175           && this->type_->points_to() != NULL))
12176     return convert_to_pointer(this->type_->get_tree(gogo), expr_tree);
12177   else if (expr_type->is_unsafe_pointer_type()
12178            && this->type_->integer_type() != NULL)
12179     return convert_to_integer(this->type_->get_tree(gogo), expr_tree);
12180   else if (this->type_->interface_type() != NULL)
12181     return Expression::convert_interface_to_interface(context, this->type_,
12182                                                       this->expr_->type(),
12183                                                       expr_tree, true,
12184                                                       this->location());
12185   else
12186     return Expression::convert_for_assignment(context, this->type_,
12187                                               this->expr_->type(), expr_tree,
12188                                               this->location());
12189 }
12190
12191 // Make a type guard expression.
12192
12193 Expression*
12194 Expression::make_type_guard(Expression* expr, Type* type,
12195                             source_location location)
12196 {
12197   return new Type_guard_expression(expr, type, location);
12198 }
12199
12200 // Class Heap_composite_expression.
12201
12202 // When you take the address of a composite literal, it is allocated
12203 // on the heap.  This class implements that.
12204
12205 class Heap_composite_expression : public Expression
12206 {
12207  public:
12208   Heap_composite_expression(Expression* expr, source_location location)
12209     : Expression(EXPRESSION_HEAP_COMPOSITE, location),
12210       expr_(expr)
12211   { }
12212
12213  protected:
12214   int
12215   do_traverse(Traverse* traverse)
12216   { return Expression::traverse(&this->expr_, traverse); }
12217
12218   Type*
12219   do_type()
12220   { return Type::make_pointer_type(this->expr_->type()); }
12221
12222   void
12223   do_determine_type(const Type_context*)
12224   { this->expr_->determine_type_no_context(); }
12225
12226   Expression*
12227   do_copy()
12228   {
12229     return Expression::make_heap_composite(this->expr_->copy(),
12230                                            this->location());
12231   }
12232
12233   tree
12234   do_get_tree(Translate_context*);
12235
12236   // We only export global objects, and the parser does not generate
12237   // this in global scope.
12238   void
12239   do_export(Export*) const
12240   { gcc_unreachable(); }
12241
12242  private:
12243   // The composite literal which is being put on the heap.
12244   Expression* expr_;
12245 };
12246
12247 // Return a tree which allocates a composite literal on the heap.
12248
12249 tree
12250 Heap_composite_expression::do_get_tree(Translate_context* context)
12251 {
12252   tree expr_tree = this->expr_->get_tree(context);
12253   if (expr_tree == error_mark_node)
12254     return error_mark_node;
12255   tree expr_size = TYPE_SIZE_UNIT(TREE_TYPE(expr_tree));
12256   gcc_assert(TREE_CODE(expr_size) == INTEGER_CST);
12257   tree space = context->gogo()->allocate_memory(this->expr_->type(),
12258                                                 expr_size, this->location());
12259   space = fold_convert(build_pointer_type(TREE_TYPE(expr_tree)), space);
12260   space = save_expr(space);
12261   tree ref = build_fold_indirect_ref_loc(this->location(), space);
12262   TREE_THIS_NOTRAP(ref) = 1;
12263   tree ret = build2(COMPOUND_EXPR, TREE_TYPE(space),
12264                     build2(MODIFY_EXPR, void_type_node, ref, expr_tree),
12265                     space);
12266   SET_EXPR_LOCATION(ret, this->location());
12267   return ret;
12268 }
12269
12270 // Allocate a composite literal on the heap.
12271
12272 Expression*
12273 Expression::make_heap_composite(Expression* expr, source_location location)
12274 {
12275   return new Heap_composite_expression(expr, location);
12276 }
12277
12278 // Class Receive_expression.
12279
12280 // Return the type of a receive expression.
12281
12282 Type*
12283 Receive_expression::do_type()
12284 {
12285   Channel_type* channel_type = this->channel_->type()->channel_type();
12286   if (channel_type == NULL)
12287     return Type::make_error_type();
12288   return channel_type->element_type();
12289 }
12290
12291 // Check types for a receive expression.
12292
12293 void
12294 Receive_expression::do_check_types(Gogo*)
12295 {
12296   Type* type = this->channel_->type();
12297   if (type->is_error_type())
12298     {
12299       this->set_is_error();
12300       return;
12301     }
12302   if (type->channel_type() == NULL)
12303     {
12304       this->report_error(_("expected channel"));
12305       return;
12306     }
12307   if (!type->channel_type()->may_receive())
12308     {
12309       this->report_error(_("invalid receive on send-only channel"));
12310       return;
12311     }
12312 }
12313
12314 // Get a tree for a receive expression.
12315
12316 tree
12317 Receive_expression::do_get_tree(Translate_context* context)
12318 {
12319   Channel_type* channel_type = this->channel_->type()->channel_type();
12320   if (channel_type == NULL)
12321     {
12322       gcc_assert(this->channel_->type()->is_error_type());
12323       return error_mark_node;
12324     }
12325   Type* element_type = channel_type->element_type();
12326   tree element_type_tree = element_type->get_tree(context->gogo());
12327
12328   tree channel = this->channel_->get_tree(context);
12329   if (element_type_tree == error_mark_node || channel == error_mark_node)
12330     return error_mark_node;
12331
12332   return Gogo::receive_from_channel(element_type_tree, channel,
12333                                     this->for_select_, this->location());
12334 }
12335
12336 // Make a receive expression.
12337
12338 Receive_expression*
12339 Expression::make_receive(Expression* channel, source_location location)
12340 {
12341   return new Receive_expression(channel, location);
12342 }
12343
12344 // An expression which evaluates to a pointer to the type descriptor
12345 // of a type.
12346
12347 class Type_descriptor_expression : public Expression
12348 {
12349  public:
12350   Type_descriptor_expression(Type* type, source_location location)
12351     : Expression(EXPRESSION_TYPE_DESCRIPTOR, location),
12352       type_(type)
12353   { }
12354
12355  protected:
12356   Type*
12357   do_type()
12358   { return Type::make_type_descriptor_ptr_type(); }
12359
12360   void
12361   do_determine_type(const Type_context*)
12362   { }
12363
12364   Expression*
12365   do_copy()
12366   { return this; }
12367
12368   tree
12369   do_get_tree(Translate_context* context)
12370   { return this->type_->type_descriptor_pointer(context->gogo()); }
12371
12372  private:
12373   // The type for which this is the descriptor.
12374   Type* type_;
12375 };
12376
12377 // Make a type descriptor expression.
12378
12379 Expression*
12380 Expression::make_type_descriptor(Type* type, source_location location)
12381 {
12382   return new Type_descriptor_expression(type, location);
12383 }
12384
12385 // An expression which evaluates to some characteristic of a type.
12386 // This is only used to initialize fields of a type descriptor.  Using
12387 // a new expression class is slightly inefficient but gives us a good
12388 // separation between the frontend and the middle-end with regard to
12389 // how types are laid out.
12390
12391 class Type_info_expression : public Expression
12392 {
12393  public:
12394   Type_info_expression(Type* type, Type_info type_info)
12395     : Expression(EXPRESSION_TYPE_INFO, BUILTINS_LOCATION),
12396       type_(type), type_info_(type_info)
12397   { }
12398
12399  protected:
12400   Type*
12401   do_type();
12402
12403   void
12404   do_determine_type(const Type_context*)
12405   { }
12406
12407   Expression*
12408   do_copy()
12409   { return this; }
12410
12411   tree
12412   do_get_tree(Translate_context* context);
12413
12414  private:
12415   // The type for which we are getting information.
12416   Type* type_;
12417   // What information we want.
12418   Type_info type_info_;
12419 };
12420
12421 // The type is chosen to match what the type descriptor struct
12422 // expects.
12423
12424 Type*
12425 Type_info_expression::do_type()
12426 {
12427   switch (this->type_info_)
12428     {
12429     case TYPE_INFO_SIZE:
12430       return Type::lookup_integer_type("uintptr");
12431     case TYPE_INFO_ALIGNMENT:
12432     case TYPE_INFO_FIELD_ALIGNMENT:
12433       return Type::lookup_integer_type("uint8");
12434     default:
12435       gcc_unreachable();
12436     }
12437 }
12438
12439 // Return type information in GENERIC.
12440
12441 tree
12442 Type_info_expression::do_get_tree(Translate_context* context)
12443 {
12444   tree type_tree = this->type_->get_tree(context->gogo());
12445   if (type_tree == error_mark_node)
12446     return error_mark_node;
12447
12448   tree val_type_tree = this->type()->get_tree(context->gogo());
12449   gcc_assert(val_type_tree != error_mark_node);
12450
12451   if (this->type_info_ == TYPE_INFO_SIZE)
12452     return fold_convert_loc(BUILTINS_LOCATION, val_type_tree,
12453                             TYPE_SIZE_UNIT(type_tree));
12454   else
12455     {
12456       unsigned int val;
12457       if (this->type_info_ == TYPE_INFO_ALIGNMENT)
12458         val = go_type_alignment(type_tree);
12459       else
12460         val = go_field_alignment(type_tree);
12461       return build_int_cstu(val_type_tree, val);
12462     }
12463 }
12464
12465 // Make a type info expression.
12466
12467 Expression*
12468 Expression::make_type_info(Type* type, Type_info type_info)
12469 {
12470   return new Type_info_expression(type, type_info);
12471 }
12472
12473 // An expression which evaluates to the offset of a field within a
12474 // struct.  This, like Type_info_expression, q.v., is only used to
12475 // initialize fields of a type descriptor.
12476
12477 class Struct_field_offset_expression : public Expression
12478 {
12479  public:
12480   Struct_field_offset_expression(Struct_type* type, const Struct_field* field)
12481     : Expression(EXPRESSION_STRUCT_FIELD_OFFSET, BUILTINS_LOCATION),
12482       type_(type), field_(field)
12483   { }
12484
12485  protected:
12486   Type*
12487   do_type()
12488   { return Type::lookup_integer_type("uintptr"); }
12489
12490   void
12491   do_determine_type(const Type_context*)
12492   { }
12493
12494   Expression*
12495   do_copy()
12496   { return this; }
12497
12498   tree
12499   do_get_tree(Translate_context* context);
12500
12501  private:
12502   // The type of the struct.
12503   Struct_type* type_;
12504   // The field.
12505   const Struct_field* field_;
12506 };
12507
12508 // Return a struct field offset in GENERIC.
12509
12510 tree
12511 Struct_field_offset_expression::do_get_tree(Translate_context* context)
12512 {
12513   tree type_tree = this->type_->get_tree(context->gogo());
12514   if (type_tree == error_mark_node)
12515     return error_mark_node;
12516
12517   tree val_type_tree = this->type()->get_tree(context->gogo());
12518   gcc_assert(val_type_tree != error_mark_node);
12519
12520   const Struct_field_list* fields = this->type_->fields();
12521   tree struct_field_tree = TYPE_FIELDS(type_tree);
12522   Struct_field_list::const_iterator p;
12523   for (p = fields->begin();
12524        p != fields->end();
12525        ++p, struct_field_tree = DECL_CHAIN(struct_field_tree))
12526     {
12527       gcc_assert(struct_field_tree != NULL_TREE);
12528       if (&*p == this->field_)
12529         break;
12530     }
12531   gcc_assert(&*p == this->field_);
12532
12533   return fold_convert_loc(BUILTINS_LOCATION, val_type_tree,
12534                           byte_position(struct_field_tree));
12535 }
12536
12537 // Make an expression for a struct field offset.
12538
12539 Expression*
12540 Expression::make_struct_field_offset(Struct_type* type,
12541                                      const Struct_field* field)
12542 {
12543   return new Struct_field_offset_expression(type, field);
12544 }
12545
12546 // An expression which evaluates to the address of an unnamed label.
12547
12548 class Label_addr_expression : public Expression
12549 {
12550  public:
12551   Label_addr_expression(Label* label, source_location location)
12552     : Expression(EXPRESSION_LABEL_ADDR, location),
12553       label_(label)
12554   { }
12555
12556  protected:
12557   Type*
12558   do_type()
12559   { return Type::make_pointer_type(Type::make_void_type()); }
12560
12561   void
12562   do_determine_type(const Type_context*)
12563   { }
12564
12565   Expression*
12566   do_copy()
12567   { return new Label_addr_expression(this->label_, this->location()); }
12568
12569   tree
12570   do_get_tree(Translate_context*)
12571   { return this->label_->get_addr(this->location()); }
12572
12573  private:
12574   // The label whose address we are taking.
12575   Label* label_;
12576 };
12577
12578 // Make an expression for the address of an unnamed label.
12579
12580 Expression*
12581 Expression::make_label_addr(Label* label, source_location location)
12582 {
12583   return new Label_addr_expression(label, location);
12584 }
12585
12586 // Import an expression.  This comes at the end in order to see the
12587 // various class definitions.
12588
12589 Expression*
12590 Expression::import_expression(Import* imp)
12591 {
12592   int c = imp->peek_char();
12593   if (imp->match_c_string("- ")
12594       || imp->match_c_string("! ")
12595       || imp->match_c_string("^ "))
12596     return Unary_expression::do_import(imp);
12597   else if (c == '(')
12598     return Binary_expression::do_import(imp);
12599   else if (imp->match_c_string("true")
12600            || imp->match_c_string("false"))
12601     return Boolean_expression::do_import(imp);
12602   else if (c == '"')
12603     return String_expression::do_import(imp);
12604   else if (c == '-' || (c >= '0' && c <= '9'))
12605     {
12606       // This handles integers, floats and complex constants.
12607       return Integer_expression::do_import(imp);
12608     }
12609   else if (imp->match_c_string("nil"))
12610     return Nil_expression::do_import(imp);
12611   else if (imp->match_c_string("convert"))
12612     return Type_conversion_expression::do_import(imp);
12613   else
12614     {
12615       error_at(imp->location(), "import error: expected expression");
12616       return Expression::make_error(imp->location());
12617     }
12618 }
12619
12620 // Class Expression_list.
12621
12622 // Traverse the list.
12623
12624 int
12625 Expression_list::traverse(Traverse* traverse)
12626 {
12627   for (Expression_list::iterator p = this->begin();
12628        p != this->end();
12629        ++p)
12630     {
12631       if (*p != NULL)
12632         {
12633           if (Expression::traverse(&*p, traverse) == TRAVERSE_EXIT)
12634             return TRAVERSE_EXIT;
12635         }
12636     }
12637   return TRAVERSE_CONTINUE;
12638 }
12639
12640 // Copy the list.
12641
12642 Expression_list*
12643 Expression_list::copy()
12644 {
12645   Expression_list* ret = new Expression_list();
12646   for (Expression_list::iterator p = this->begin();
12647        p != this->end();
12648        ++p)
12649     {
12650       if (*p == NULL)
12651         ret->push_back(NULL);
12652       else
12653         ret->push_back((*p)->copy());
12654     }
12655   return ret;
12656 }
12657
12658 // Return whether an expression list has an error expression.
12659
12660 bool
12661 Expression_list::contains_error() const
12662 {
12663   for (Expression_list::const_iterator p = this->begin();
12664        p != this->end();
12665        ++p)
12666     if (*p != NULL && (*p)->is_error_expression())
12667       return true;
12668   return false;
12669 }