gcc/go/gofrontend/expressions.cc

   1 // expressions.cc -- Go frontend expression handling.
   2
   3 // Copyright 2009 The Go Authors. All rights reserved.
   4 // Use of this source code is governed by a BSD-style
   5 // license that can be found in the LICENSE file.
   6
   7 #include "go-system.h"
   8
   9 #include <gmp.h>
  10
  11 #ifndef ENABLE_BUILD_WITH_CXX
  12 extern "C"
  13 {
  14 #endif
  15
  16 #include "toplev.h"
  17 #include "intl.h"
  18 #include "tree.h"
  19 #include "gimple.h"
  20 #include "tree-iterator.h"
  21 #include "convert.h"
  22 #include "real.h"
  23 #include "realmpfr.h"
  24
  25 #ifndef ENABLE_BUILD_WITH_CXX
  26 }
  27 #endif
  28
  29 #include "go-c.h"
  30 #include "gogo.h"
  31 #include "types.h"
  32 #include "export.h"
  33 #include "import.h"
  34 #include "statements.h"
  35 #include "lex.h"
  36 #include "expressions.h"
  37
  38 // Class Expression.
  39
  40 Expression::Expression(Expression_classification classification,
  41                        source_location location)
  42   : classification_(classification), location_(location)
  43 {
  44 }
  45
  46 Expression::~Expression()
  47 {
  48 }
  49
  50 // If this expression has a constant integer value, return it.
  51
  52 bool
  53 Expression::integer_constant_value(bool iota_is_constant, mpz_t val,
  54                                    Type** ptype) const
  55 {
  56   *ptype = NULL;
  57   return this->do_integer_constant_value(iota_is_constant, val, ptype);
  58 }
  59
  60 // If this expression has a constant floating point value, return it.
  61
  62 bool
  63 Expression::float_constant_value(mpfr_t val, Type** ptype) const
  64 {
  65   *ptype = NULL;
  66   if (this->do_float_constant_value(val, ptype))
  67     return true;
  68   mpz_t ival;
  69   mpz_init(ival);
  70   Type* t;
  71   bool ret;
  72   if (!this->do_integer_constant_value(false, ival, &t))
  73     ret = false;
  74   else
  75     {
  76       mpfr_set_z(val, ival, GMP_RNDN);
  77       ret = true;
  78     }
  79   mpz_clear(ival);
  80   return ret;
  81 }
  82
  83 // If this expression has a constant complex value, return it.
  84
  85 bool
  86 Expression::complex_constant_value(mpfr_t real, mpfr_t imag,
  87                                    Type** ptype) const
  88 {
  89   *ptype = NULL;
  90   if (this->do_complex_constant_value(real, imag, ptype))
  91     return true;
  92   Type *t;
  93   if (this->float_constant_value(real, &t))
  94     {
  95       mpfr_set_ui(imag, 0, GMP_RNDN);
  96       return true;
  97     }
  98   return false;
  99 }
 100
 101 // Traverse the expressions.
 102
 103 int
 104 Expression::traverse(Expression** pexpr, Traverse* traverse)
 105 {
 106   Expression* expr = *pexpr;
 107   if ((traverse->traverse_mask() & Traverse::traverse_expressions) != 0)
 108     {
 109       int t = traverse->expression(pexpr);
 110       if (t == TRAVERSE_EXIT)
 111         return TRAVERSE_EXIT;
 112       else if (t == TRAVERSE_SKIP_COMPONENTS)
 113         return TRAVERSE_CONTINUE;
 114     }
 115   return expr->do_traverse(traverse);
 116 }
 117
 118 // Traverse subexpressions of this expression.
 119
 120 int
 121 Expression::traverse_subexpressions(Traverse* traverse)
 122 {
 123   return this->do_traverse(traverse);
 124 }
 125
 126 // Default implementation for do_traverse for child classes.
 127
 128 int
 129 Expression::do_traverse(Traverse*)
 130 {
 131   return TRAVERSE_CONTINUE;
 132 }
 133
 134 // This virtual function is called by the parser if the value of this
 135 // expression is being discarded.  By default, we warn.  Expressions
 136 // with side effects override.
 137
 138 void
 139 Expression::do_discarding_value()
 140 {
 141   this->warn_about_unused_value();
 142 }
 143
 144 // This virtual function is called to export expressions.  This will
 145 // only be used by expressions which may be constant.
 146
 147 void
 148 Expression::do_export(Export*) const
 149 {
 150   gcc_unreachable();
 151 }
 152
 153 // Warn that the value of the expression is not used.
 154
 155 void
 156 Expression::warn_about_unused_value()
 157 {
 158   warning_at(this->location(), OPT_Wunused_value, "value computed is not used");
 159 }
 160
 161 // Note that this expression is an error.  This is called by children
 162 // when they discover an error.
 163
 164 void
 165 Expression::set_is_error()
 166 {
 167   this->classification_ = EXPRESSION_ERROR;
 168 }
 169
 170 // For children to call to report an error conveniently.
 171
 172 void
 173 Expression::report_error(const char* msg)
 174 {
 175   error_at(this->location_, "%s", msg);
 176   this->set_is_error();
 177 }
 178
 179 // Set types of variables and constants.  This is implemented by the
 180 // child class.
 181
 182 void
 183 Expression::determine_type(const Type_context* context)
 184 {
 185   this->do_determine_type(context);
 186 }
 187
 188 // Set types when there is no context.
 189
 190 void
 191 Expression::determine_type_no_context()
 192 {
 193   Type_context context;
 194   this->do_determine_type(&context);
 195 }
 196
 197 // Return a tree handling any conversions which must be done during
 198 // assignment.
 199
 200 tree
 201 Expression::convert_for_assignment(Translate_context* context, Type* lhs_type,
 202                                    Type* rhs_type, tree rhs_tree,
 203                                    source_location location)
 204 {
 205   if (lhs_type == rhs_type)
 206     return rhs_tree;
 207
 208   if (lhs_type->is_error_type() || rhs_type->is_error_type())
 209     return error_mark_node;
 210
 211   if (lhs_type->is_undefined() || rhs_type->is_undefined())
 212     {
 213       // Make sure we report the error.
 214       lhs_type->base();
 215       rhs_type->base();
 216       return error_mark_node;
 217     }
 218
 219   if (rhs_tree == error_mark_node || TREE_TYPE(rhs_tree) == error_mark_node)
 220     return error_mark_node;
 221
 222   Gogo* gogo = context->gogo();
 223
 224   tree lhs_type_tree = lhs_type->get_tree(gogo);
 225   if (lhs_type_tree == error_mark_node)
 226     return error_mark_node;
 227
 228   if (lhs_type->interface_type() != NULL)
 229     {
 230       if (rhs_type->interface_type() == NULL)
 231         return Expression::convert_type_to_interface(context, lhs_type,
 232                                                      rhs_type, rhs_tree,
 233                                                      location);
 234       else
 235         return Expression::convert_interface_to_interface(context, lhs_type,
 236                                                           rhs_type, rhs_tree,
 237                                                           false, location);
 238     }
 239   else if (rhs_type->interface_type() != NULL)
 240     return Expression::convert_interface_to_type(context, lhs_type, rhs_type,
 241                                                  rhs_tree, location);
 242   else if (lhs_type->is_open_array_type()
 243            && rhs_type->is_nil_type())
 244     {
 245       // Assigning nil to an open array.
 246       gcc_assert(TREE_CODE(lhs_type_tree) == RECORD_TYPE);
 247
 248       VEC(constructor_elt,gc)* init = VEC_alloc(constructor_elt, gc, 3);
 249
 250       constructor_elt* elt = VEC_quick_push(constructor_elt, init, NULL);
 251       tree field = TYPE_FIELDS(lhs_type_tree);
 252       gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)),
 253                         "__values") == 0);
 254       elt->index = field;
 255       elt->value = fold_convert(TREE_TYPE(field), null_pointer_node);
 256
 257       elt = VEC_quick_push(constructor_elt, init, NULL);
 258       field = DECL_CHAIN(field);
 259       gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)),
 260                         "__count") == 0);
 261       elt->index = field;
 262       elt->value = fold_convert(TREE_TYPE(field), integer_zero_node);
 263
 264       elt = VEC_quick_push(constructor_elt, init, NULL);
 265       field = DECL_CHAIN(field);
 266       gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)),
 267                         "__capacity") == 0);
 268       elt->index = field;
 269       elt->value = fold_convert(TREE_TYPE(field), integer_zero_node);
 270
 271       tree val = build_constructor(lhs_type_tree, init);
 272       TREE_CONSTANT(val) = 1;
 273
 274       return val;
 275     }
 276   else if (rhs_type->is_nil_type())
 277     {
 278       // The left hand side should be a pointer type at the tree
 279       // level.
 280       gcc_assert(POINTER_TYPE_P(lhs_type_tree));
 281       return fold_convert(lhs_type_tree, null_pointer_node);
 282     }
 283   else if (lhs_type_tree == TREE_TYPE(rhs_tree))
 284     {
 285       // No conversion is needed.
 286       return rhs_tree;
 287     }
 288   else if (POINTER_TYPE_P(lhs_type_tree)
 289            || INTEGRAL_TYPE_P(lhs_type_tree)
 290            || SCALAR_FLOAT_TYPE_P(lhs_type_tree)
 291            || COMPLEX_FLOAT_TYPE_P(lhs_type_tree))
 292     return fold_convert_loc(location, lhs_type_tree, rhs_tree);
 293   else if (TREE_CODE(lhs_type_tree) == RECORD_TYPE
 294            && TREE_CODE(TREE_TYPE(rhs_tree)) == RECORD_TYPE)
 295     {
 296       // This conversion must be permitted by Go, or we wouldn't have
 297       // gotten here.
 298       gcc_assert(int_size_in_bytes(lhs_type_tree)
 299                  == int_size_in_bytes(TREE_TYPE(rhs_tree)));
 300       return fold_build1_loc(location, VIEW_CONVERT_EXPR, lhs_type_tree,
 301                              rhs_tree);
 302     }
 303   else
 304     {
 305       gcc_assert(useless_type_conversion_p(lhs_type_tree, TREE_TYPE(rhs_tree)));
 306       return rhs_tree;
 307     }
 308 }
 309
 310 // Return a tree for a conversion from a non-interface type to an
 311 // interface type.
 312
 313 tree
 314 Expression::convert_type_to_interface(Translate_context* context,
 315                                       Type* lhs_type, Type* rhs_type,
 316                                       tree rhs_tree, source_location location)
 317 {
 318   Gogo* gogo = context->gogo();
 319   Interface_type* lhs_interface_type = lhs_type->interface_type();
 320   bool lhs_is_empty = lhs_interface_type->is_empty();
 321
 322   // Since RHS_TYPE is a static type, we can create the interface
 323   // method table at compile time.
 324
 325   // When setting an interface to nil, we just set both fields to
 326   // NULL.
 327   if (rhs_type->is_nil_type())
 328     return lhs_type->get_init_tree(gogo, false);
 329
 330   // This should have been checked already.
 331   gcc_assert(lhs_interface_type->implements_interface(rhs_type, NULL));
 332
 333   tree lhs_type_tree = lhs_type->get_tree(gogo);
 334   if (lhs_type_tree == error_mark_node)
 335     return error_mark_node;
 336
 337   // An interface is a tuple.  If LHS_TYPE is an empty interface type,
 338   // then the first field is the type descriptor for RHS_TYPE.
 339   // Otherwise it is the interface method table for RHS_TYPE.
 340   tree first_field_value;
 341   if (lhs_is_empty)
 342     first_field_value = rhs_type->type_descriptor_pointer(gogo);
 343   else
 344     {
 345       // Build the interface method table for this interface and this
 346       // object type: a list of function pointers for each interface
 347       // method.
 348       Named_type* rhs_named_type = rhs_type->named_type();
 349       bool is_pointer = false;
 350       if (rhs_named_type == NULL)
 351         {
 352           rhs_named_type = rhs_type->deref()->named_type();
 353           is_pointer = true;
 354         }
 355       tree method_table;
 356       if (rhs_named_type == NULL)
 357         method_table = null_pointer_node;
 358       else
 359         method_table =
 360           rhs_named_type->interface_method_table(gogo, lhs_interface_type,
 361                                                  is_pointer);
 362       first_field_value = fold_convert_loc(location, const_ptr_type_node,
 363                                            method_table);
 364     }
 365
 366   // Start building a constructor for the value we will return.
 367
 368   VEC(constructor_elt,gc)* init = VEC_alloc(constructor_elt, gc, 2);
 369
 370   constructor_elt* elt = VEC_quick_push(constructor_elt, init, NULL);
 371   tree field = TYPE_FIELDS(lhs_type_tree);
 372   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)),
 373                     (lhs_is_empty ? "__type_descriptor" : "__methods")) == 0);
 374   elt->index = field;
 375   elt->value = fold_convert_loc(location, TREE_TYPE(field), first_field_value);
 376
 377   elt = VEC_quick_push(constructor_elt, init, NULL);
 378   field = DECL_CHAIN(field);
 379   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__object") == 0);
 380   elt->index = field;
 381
 382   if (rhs_type->points_to() != NULL)
 383     {
 384       //  We are assigning a pointer to the interface; the interface
 385       // holds the pointer itself.
 386       elt->value = rhs_tree;
 387       return build_constructor(lhs_type_tree, init);
 388     }
 389
 390   // We are assigning a non-pointer value to the interface; the
 391   // interface gets a copy of the value in the heap.
 392
 393   tree object_size = TYPE_SIZE_UNIT(TREE_TYPE(rhs_tree));
 394
 395   tree space = gogo->allocate_memory(rhs_type, object_size, location);
 396   space = fold_convert_loc(location, build_pointer_type(TREE_TYPE(rhs_tree)),
 397                            space);
 398   space = save_expr(space);
 399
 400   tree ref = build_fold_indirect_ref_loc(location, space);
 401   TREE_THIS_NOTRAP(ref) = 1;
 402   tree set = fold_build2_loc(location, MODIFY_EXPR, void_type_node,
 403                              ref, rhs_tree);
 404
 405   elt->value = fold_convert_loc(location, TREE_TYPE(field), space);
 406
 407   return build2(COMPOUND_EXPR, lhs_type_tree, set,
 408                 build_constructor(lhs_type_tree, init));
 409 }
 410
 411 // Return a tree for the type descriptor of RHS_TREE, which has
 412 // interface type RHS_TYPE.  If RHS_TREE is nil the result will be
 413 // NULL.
 414
 415 tree
 416 Expression::get_interface_type_descriptor(Translate_context*,
 417                                           Type* rhs_type, tree rhs_tree,
 418                                           source_location location)
 419 {
 420   tree rhs_type_tree = TREE_TYPE(rhs_tree);
 421   gcc_assert(TREE_CODE(rhs_type_tree) == RECORD_TYPE);
 422   tree rhs_field = TYPE_FIELDS(rhs_type_tree);
 423   tree v = build3(COMPONENT_REF, TREE_TYPE(rhs_field), rhs_tree, rhs_field,
 424                   NULL_TREE);
 425   if (rhs_type->interface_type()->is_empty())
 426     {
 427       gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(rhs_field)),
 428                         "__type_descriptor") == 0);
 429       return v;
 430     }
 431
 432   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(rhs_field)), "__methods")
 433              == 0);
 434   gcc_assert(POINTER_TYPE_P(TREE_TYPE(v)));
 435   v = save_expr(v);
 436   tree v1 = build_fold_indirect_ref_loc(location, v);
 437   gcc_assert(TREE_CODE(TREE_TYPE(v1)) == RECORD_TYPE);
 438   tree f = TYPE_FIELDS(TREE_TYPE(v1));
 439   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(f)), "__type_descriptor")
 440              == 0);
 441   v1 = build3(COMPONENT_REF, TREE_TYPE(f), v1, f, NULL_TREE);
 442
 443   tree eq = fold_build2_loc(location, EQ_EXPR, boolean_type_node, v,
 444                             fold_convert_loc(location, TREE_TYPE(v),
 445                                              null_pointer_node));
 446   tree n = fold_convert_loc(location, TREE_TYPE(v1), null_pointer_node);
 447   return fold_build3_loc(location, COND_EXPR, TREE_TYPE(v1),
 448                          eq, n, v1);
 449 }
 450
 451 // Return a tree for the conversion of an interface type to an
 452 // interface type.
 453
 454 tree
 455 Expression::convert_interface_to_interface(Translate_context* context,
 456                                            Type *lhs_type, Type *rhs_type,
 457                                            tree rhs_tree, bool for_type_guard,
 458                                            source_location location)
 459 {
 460   Gogo* gogo = context->gogo();
 461   Interface_type* lhs_interface_type = lhs_type->interface_type();
 462   bool lhs_is_empty = lhs_interface_type->is_empty();
 463
 464   tree lhs_type_tree = lhs_type->get_tree(gogo);
 465   if (lhs_type_tree == error_mark_node)
 466     return error_mark_node;
 467
 468   // In the general case this requires runtime examination of the type
 469   // method table to match it up with the interface methods.
 470
 471   // FIXME: If all of the methods in the right hand side interface
 472   // also appear in the left hand side interface, then we don't need
 473   // to do a runtime check, although we still need to build a new
 474   // method table.
 475
 476   // Get the type descriptor for the right hand side.  This will be
 477   // NULL for a nil interface.
 478
 479   if (!DECL_P(rhs_tree))
 480     rhs_tree = save_expr(rhs_tree);
 481
 482   tree rhs_type_descriptor =
 483     Expression::get_interface_type_descriptor(context, rhs_type, rhs_tree,
 484                                               location);
 485
 486   // The result is going to be a two element constructor.
 487
 488   VEC(constructor_elt,gc)* init = VEC_alloc(constructor_elt, gc, 2);
 489
 490   constructor_elt* elt = VEC_quick_push(constructor_elt, init, NULL);
 491   tree field = TYPE_FIELDS(lhs_type_tree);
 492   elt->index = field;
 493
 494   if (for_type_guard)
 495     {
 496       // A type assertion fails when converting a nil interface.
 497       tree lhs_type_descriptor = lhs_type->type_descriptor_pointer(gogo);
 498       static tree assert_interface_decl;
 499       tree call = Gogo::call_builtin(&assert_interface_decl,
 500                                      location,
 501                                      "__go_assert_interface",
 502                                      2,
 503                                      ptr_type_node,
 504                                      TREE_TYPE(lhs_type_descriptor),
 505                                      lhs_type_descriptor,
 506                                      TREE_TYPE(rhs_type_descriptor),
 507                                      rhs_type_descriptor);
 508       if (call == error_mark_node)
 509         return error_mark_node;
 510       // This will panic if the interface conversion fails.
 511       TREE_NOTHROW(assert_interface_decl) = 0;
 512       elt->value = fold_convert_loc(location, TREE_TYPE(field), call);
 513     }
 514   else if (lhs_is_empty)
 515     {
 516       // A convertion to an empty interface always succeeds, and the
 517       // first field is just the type descriptor of the object.
 518       gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)),
 519                         "__type_descriptor") == 0);
 520       gcc_assert(TREE_TYPE(field) == TREE_TYPE(rhs_type_descriptor));
 521       elt->value = rhs_type_descriptor;
 522     }
 523   else
 524     {
 525       // A conversion to a non-empty interface may fail, but unlike a
 526       // type assertion converting nil will always succeed.
 527       gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__methods")
 528                  == 0);
 529       tree lhs_type_descriptor = lhs_type->type_descriptor_pointer(gogo);
 530       static tree convert_interface_decl;
 531       tree call = Gogo::call_builtin(&convert_interface_decl,
 532                                      location,
 533                                      "__go_convert_interface",
 534                                      2,
 535                                      ptr_type_node,
 536                                      TREE_TYPE(lhs_type_descriptor),
 537                                      lhs_type_descriptor,
 538                                      TREE_TYPE(rhs_type_descriptor),
 539                                      rhs_type_descriptor);
 540       if (call == error_mark_node)
 541         return error_mark_node;
 542       // This will panic if the interface conversion fails.
 543       TREE_NOTHROW(convert_interface_decl) = 0;
 544       elt->value = fold_convert_loc(location, TREE_TYPE(field), call);
 545     }
 546
 547   // The second field is simply the object pointer.
 548
 549   elt = VEC_quick_push(constructor_elt, init, NULL);
 550   field = DECL_CHAIN(field);
 551   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__object") == 0);
 552   elt->index = field;
 553
 554   tree rhs_type_tree = TREE_TYPE(rhs_tree);
 555   gcc_assert(TREE_CODE(rhs_type_tree) == RECORD_TYPE);
 556   tree rhs_field = DECL_CHAIN(TYPE_FIELDS(rhs_type_tree));
 557   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(rhs_field)), "__object") == 0);
 558   elt->value = build3(COMPONENT_REF, TREE_TYPE(rhs_field), rhs_tree, rhs_field,
 559                       NULL_TREE);
 560
 561   return build_constructor(lhs_type_tree, init);
 562 }
 563
 564 // Return a tree for the conversion of an interface type to a
 565 // non-interface type.
 566
 567 tree
 568 Expression::convert_interface_to_type(Translate_context* context,
 569                                       Type *lhs_type, Type* rhs_type,
 570                                       tree rhs_tree, source_location location)
 571 {
 572   Gogo* gogo = context->gogo();
 573   tree rhs_type_tree = TREE_TYPE(rhs_tree);
 574
 575   tree lhs_type_tree = lhs_type->get_tree(gogo);
 576   if (lhs_type_tree == error_mark_node)
 577     return error_mark_node;
 578
 579   // Call a function to check that the type is valid.  The function
 580   // will panic with an appropriate runtime type error if the type is
 581   // not valid.
 582
 583   tree lhs_type_descriptor = lhs_type->type_descriptor_pointer(gogo);
 584
 585   if (!DECL_P(rhs_tree))
 586     rhs_tree = save_expr(rhs_tree);
 587
 588   tree rhs_type_descriptor =
 589     Expression::get_interface_type_descriptor(context, rhs_type, rhs_tree,
 590                                               location);
 591
 592   tree rhs_inter_descriptor = rhs_type->type_descriptor_pointer(gogo);
 593
 594   static tree check_interface_type_decl;
 595   tree call = Gogo::call_builtin(&check_interface_type_decl,
 596                                  location,
 597                                  "__go_check_interface_type",
 598                                  3,
 599                                  void_type_node,
 600                                  TREE_TYPE(lhs_type_descriptor),
 601                                  lhs_type_descriptor,
 602                                  TREE_TYPE(rhs_type_descriptor),
 603                                  rhs_type_descriptor,
 604                                  TREE_TYPE(rhs_inter_descriptor),
 605                                  rhs_inter_descriptor);
 606   if (call == error_mark_node)
 607     return error_mark_node;
 608   // This call will panic if the conversion is invalid.
 609   TREE_NOTHROW(check_interface_type_decl) = 0;
 610
 611   // If the call succeeds, pull out the value.
 612   gcc_assert(TREE_CODE(rhs_type_tree) == RECORD_TYPE);
 613   tree rhs_field = DECL_CHAIN(TYPE_FIELDS(rhs_type_tree));
 614   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(rhs_field)), "__object") == 0);
 615   tree val = build3(COMPONENT_REF, TREE_TYPE(rhs_field), rhs_tree, rhs_field,
 616                     NULL_TREE);
 617
 618   // If the value is a pointer, then it is the value we want.
 619   // Otherwise it points to the value.
 620   if (lhs_type->points_to() == NULL)
 621     {
 622       val = fold_convert_loc(location, build_pointer_type(lhs_type_tree), val);
 623       val = build_fold_indirect_ref_loc(location, val);
 624     }
 625
 626   return build2(COMPOUND_EXPR, lhs_type_tree, call,
 627                 fold_convert_loc(location, lhs_type_tree, val));
 628 }
 629
 630 // Convert an expression to a tree.  This is implemented by the child
 631 // class.  Not that it is not in general safe to call this multiple
 632 // times for a single expression, but that we don't catch such errors.
 633
 634 tree
 635 Expression::get_tree(Translate_context* context)
 636 {
 637   // The child may have marked this expression as having an error.
 638   if (this->classification_ == EXPRESSION_ERROR)
 639     return error_mark_node;
 640
 641   return this->do_get_tree(context);
 642 }
 643
 644 // Return a tree for VAL in TYPE.
 645
 646 tree
 647 Expression::integer_constant_tree(mpz_t val, tree type)
 648 {
 649   if (type == error_mark_node)
 650     return error_mark_node;
 651   else if (TREE_CODE(type) == INTEGER_TYPE)
 652     return double_int_to_tree(type,
 653                               mpz_get_double_int(type, val, true));
 654   else if (TREE_CODE(type) == REAL_TYPE)
 655     {
 656       mpfr_t fval;
 657       mpfr_init_set_z(fval, val, GMP_RNDN);
 658       tree ret = Expression::float_constant_tree(fval, type);
 659       mpfr_clear(fval);
 660       return ret;
 661     }
 662   else if (TREE_CODE(type) == COMPLEX_TYPE)
 663     {
 664       mpfr_t fval;
 665       mpfr_init_set_z(fval, val, GMP_RNDN);
 666       tree real = Expression::float_constant_tree(fval, TREE_TYPE(type));
 667       mpfr_clear(fval);
 668       tree imag = build_real_from_int_cst(TREE_TYPE(type),
 669                                           integer_zero_node);
 670       return build_complex(type, real, imag);
 671     }
 672   else
 673     gcc_unreachable();
 674 }
 675
 676 // Return a tree for VAL in TYPE.
 677
 678 tree
 679 Expression::float_constant_tree(mpfr_t val, tree type)
 680 {
 681   if (type == error_mark_node)
 682     return error_mark_node;
 683   else if (TREE_CODE(type) == INTEGER_TYPE)
 684     {
 685       mpz_t ival;
 686       mpz_init(ival);
 687       mpfr_get_z(ival, val, GMP_RNDN);
 688       tree ret = Expression::integer_constant_tree(ival, type);
 689       mpz_clear(ival);
 690       return ret;
 691     }
 692   else if (TREE_CODE(type) == REAL_TYPE)
 693     {
 694       REAL_VALUE_TYPE r1;
 695       real_from_mpfr(&r1, val, type, GMP_RNDN);
 696       REAL_VALUE_TYPE r2;
 697       real_convert(&r2, TYPE_MODE(type), &r1);
 698       return build_real(type, r2);
 699     }
 700   else if (TREE_CODE(type) == COMPLEX_TYPE)
 701     {
 702       REAL_VALUE_TYPE r1;
 703       real_from_mpfr(&r1, val, TREE_TYPE(type), GMP_RNDN);
 704       REAL_VALUE_TYPE r2;
 705       real_convert(&r2, TYPE_MODE(TREE_TYPE(type)), &r1);
 706       tree imag = build_real_from_int_cst(TREE_TYPE(type),
 707                                           integer_zero_node);
 708       return build_complex(type, build_real(TREE_TYPE(type), r2), imag);
 709     }
 710   else
 711     gcc_unreachable();
 712 }
 713
 714 // Return a tree for REAL/IMAG in TYPE.
 715
 716 tree
 717 Expression::complex_constant_tree(mpfr_t real, mpfr_t imag, tree type)
 718 {
 719   if (TREE_CODE(type) == COMPLEX_TYPE)
 720     {
 721       REAL_VALUE_TYPE r1;
 722       real_from_mpfr(&r1, real, TREE_TYPE(type), GMP_RNDN);
 723       REAL_VALUE_TYPE r2;
 724       real_convert(&r2, TYPE_MODE(TREE_TYPE(type)), &r1);
 725
 726       REAL_VALUE_TYPE r3;
 727       real_from_mpfr(&r3, imag, TREE_TYPE(type), GMP_RNDN);
 728       REAL_VALUE_TYPE r4;
 729       real_convert(&r4, TYPE_MODE(TREE_TYPE(type)), &r3);
 730
 731       return build_complex(type, build_real(TREE_TYPE(type), r2),
 732                            build_real(TREE_TYPE(type), r4));
 733     }
 734   else
 735     gcc_unreachable();
 736 }
 737
 738 // Return a tree which evaluates to true if VAL, of arbitrary integer
 739 // type, is negative or is more than the maximum value of BOUND_TYPE.
 740 // If SOFAR is not NULL, it is or'red into the result.  The return
 741 // value may be NULL if SOFAR is NULL.
 742
 743 tree
 744 Expression::check_bounds(tree val, tree bound_type, tree sofar,
 745                          source_location loc)
 746 {
 747   tree val_type = TREE_TYPE(val);
 748   tree ret = NULL_TREE;
 749
 750   if (!TYPE_UNSIGNED(val_type))
 751     {
 752       ret = fold_build2_loc(loc, LT_EXPR, boolean_type_node, val,
 753                             build_int_cst(val_type, 0));
 754       if (ret == boolean_false_node)
 755         ret = NULL_TREE;
 756     }
 757
 758   if ((TYPE_UNSIGNED(val_type) && !TYPE_UNSIGNED(bound_type))
 759       || TYPE_SIZE(val_type) > TYPE_SIZE(bound_type))
 760     {
 761       tree max = TYPE_MAX_VALUE(bound_type);
 762       tree big = fold_build2_loc(loc, GT_EXPR, boolean_type_node, val,
 763                                  fold_convert_loc(loc, val_type, max));
 764       if (big == boolean_false_node)
 765         ;
 766       else if (ret == NULL_TREE)
 767         ret = big;
 768       else
 769         ret = fold_build2_loc(loc, TRUTH_OR_EXPR, boolean_type_node,
 770                               ret, big);
 771     }
 772
 773   if (ret == NULL_TREE)
 774     return sofar;
 775   else if (sofar == NULL_TREE)
 776     return ret;
 777   else
 778     return fold_build2_loc(loc, TRUTH_OR_EXPR, boolean_type_node,
 779                            sofar, ret);
 780 }
 781
 782 // Error expressions.  This are used to avoid cascading errors.
 783
 784 class Error_expression : public Expression
 785 {
 786  public:
 787   Error_expression(source_location location)
 788     : Expression(EXPRESSION_ERROR, location)
 789   { }
 790
 791  protected:
 792   bool
 793   do_is_constant() const
 794   { return true; }
 795
 796   bool
 797   do_integer_constant_value(bool, mpz_t val, Type**) const
 798   {
 799     mpz_set_ui(val, 0);
 800     return true;
 801   }
 802
 803   bool
 804   do_float_constant_value(mpfr_t val, Type**) const
 805   {
 806     mpfr_set_ui(val, 0, GMP_RNDN);
 807     return true;
 808   }
 809
 810   bool
 811   do_complex_constant_value(mpfr_t real, mpfr_t imag, Type**) const
 812   {
 813     mpfr_set_ui(real, 0, GMP_RNDN);
 814     mpfr_set_ui(imag, 0, GMP_RNDN);
 815     return true;
 816   }
 817
 818   void
 819   do_discarding_value()
 820   { }
 821
 822   Type*
 823   do_type()
 824   { return Type::make_error_type(); }
 825
 826   void
 827   do_determine_type(const Type_context*)
 828   { }
 829
 830   Expression*
 831   do_copy()
 832   { return this; }
 833
 834   bool
 835   do_is_addressable() const
 836   { return true; }
 837
 838   tree
 839   do_get_tree(Translate_context*)
 840   { return error_mark_node; }
 841 };
 842
 843 Expression*
 844 Expression::make_error(source_location location)
 845 {
 846   return new Error_expression(location);
 847 }
 848
 849 // An expression which is really a type.  This is used during parsing.
 850 // It is an error if these survive after lowering.
 851
 852 class
 853 Type_expression : public Expression
 854 {
 855  public:
 856   Type_expression(Type* type, source_location location)
 857     : Expression(EXPRESSION_TYPE, location),
 858       type_(type)
 859   { }
 860
 861  protected:
 862   int
 863   do_traverse(Traverse* traverse)
 864   { return Type::traverse(this->type_, traverse); }
 865
 866   Type*
 867   do_type()
 868   { return this->type_; }
 869
 870   void
 871   do_determine_type(const Type_context*)
 872   { }
 873
 874   void
 875   do_check_types(Gogo*)
 876   { this->report_error(_("invalid use of type")); }
 877
 878   Expression*
 879   do_copy()
 880   { return this; }
 881
 882   tree
 883   do_get_tree(Translate_context*)
 884   { gcc_unreachable(); }
 885
 886  private:
 887   // The type which we are representing as an expression.
 888   Type* type_;
 889 };
 890
 891 Expression*
 892 Expression::make_type(Type* type, source_location location)
 893 {
 894   return new Type_expression(type, location);
 895 }
 896
 897 // Class Parser_expression.
 898
 899 Type*
 900 Parser_expression::do_type()
 901 {
 902   // We should never really ask for the type of a Parser_expression.
 903   // However, it can happen, at least when we have an invalid const
 904   // whose initializer refers to the const itself.  In that case we
 905   // may ask for the type when lowering the const itself.
 906   gcc_assert(saw_errors());
 907   return Type::make_error_type();
 908 }
 909
 910 // Class Var_expression.
 911
 912 // Lower a variable expression.  Here we just make sure that the
 913 // initialization expression of the variable has been lowered.  This
 914 // ensures that we will be able to determine the type of the variable
 915 // if necessary.
 916
 917 Expression*
 918 Var_expression::do_lower(Gogo* gogo, Named_object* function, int)
 919 {
 920   if (this->variable_->is_variable())
 921     {
 922       Variable* var = this->variable_->var_value();
 923       // This is either a local variable or a global variable.  A
 924       // reference to a variable which is local to an enclosing
 925       // function will be a reference to a field in a closure.
 926       if (var->is_global())
 927         function = NULL;
 928       var->lower_init_expression(gogo, function);
 929     }
 930   return this;
 931 }
 932
 933 // Return the name of the variable.
 934
 935 const std::string&
 936 Var_expression::name() const
 937 {
 938   return this->variable_->name();
 939 }
 940
 941 // Return the type of a reference to a variable.
 942
 943 Type*
 944 Var_expression::do_type()
 945 {
 946   if (this->variable_->is_variable())
 947     return this->variable_->var_value()->type();
 948   else if (this->variable_->is_result_variable())
 949     return this->variable_->result_var_value()->type();
 950   else
 951     gcc_unreachable();
 952 }
 953
 954 // Something takes the address of this variable.  This means that we
 955 // may want to move the variable onto the heap.
 956
 957 void
 958 Var_expression::do_address_taken(bool escapes)
 959 {
 960   if (!escapes)
 961     ;
 962   else if (this->variable_->is_variable())
 963     this->variable_->var_value()->set_address_taken();
 964   else if (this->variable_->is_result_variable())
 965     this->variable_->result_var_value()->set_address_taken();
 966   else
 967     gcc_unreachable();
 968 }
 969
 970 // Get the tree for a reference to a variable.
 971
 972 tree
 973 Var_expression::do_get_tree(Translate_context* context)
 974 {
 975   return this->variable_->get_tree(context->gogo(), context->function());
 976 }
 977
 978 // Make a reference to a variable in an expression.
 979
 980 Expression*
 981 Expression::make_var_reference(Named_object* var, source_location location)
 982 {
 983   if (var->is_sink())
 984     return Expression::make_sink(location);
 985
 986   // FIXME: Creating a new object for each reference to a variable is
 987   // wasteful.
 988   return new Var_expression(var, location);
 989 }
 990
 991 // Class Temporary_reference_expression.
 992
 993 // The type.
 994
 995 Type*
 996 Temporary_reference_expression::do_type()
 997 {
 998   return this->statement_->type();
 999 }
1000
1001 // Called if something takes the address of this temporary variable.
1002 // We never have to move temporary variables to the heap, but we do
1003 // need to know that they must live in the stack rather than in a
1004 // register.
1005
1006 void
1007 Temporary_reference_expression::do_address_taken(bool)
1008 {
1009   this->statement_->set_is_address_taken();
1010 }
1011
1012 // Get a tree referring to the variable.
1013
1014 tree
1015 Temporary_reference_expression::do_get_tree(Translate_context*)
1016 {
1017   return this->statement_->get_decl();
1018 }
1019
1020 // Make a reference to a temporary variable.
1021
1022 Expression*
1023 Expression::make_temporary_reference(Temporary_statement* statement,
1024                                      source_location location)
1025 {
1026   return new Temporary_reference_expression(statement, location);
1027 }
1028
1029 // A sink expression--a use of the blank identifier _.
1030
1031 class Sink_expression : public Expression
1032 {
1033  public:
1034   Sink_expression(source_location location)
1035     : Expression(EXPRESSION_SINK, location),
1036       type_(NULL), var_(NULL_TREE)
1037   { }
1038
1039  protected:
1040   void
1041   do_discarding_value()
1042   { }
1043
1044   Type*
1045   do_type();
1046
1047   void
1048   do_determine_type(const Type_context*);
1049
1050   Expression*
1051   do_copy()
1052   { return new Sink_expression(this->location()); }
1053
1054   tree
1055   do_get_tree(Translate_context*);
1056
1057  private:
1058   // The type of this sink variable.
1059   Type* type_;
1060   // The temporary variable we generate.
1061   tree var_;
1062 };
1063
1064 // Return the type of a sink expression.
1065
1066 Type*
1067 Sink_expression::do_type()
1068 {
1069   if (this->type_ == NULL)
1070     return Type::make_sink_type();
1071   return this->type_;
1072 }
1073
1074 // Determine the type of a sink expression.
1075
1076 void
1077 Sink_expression::do_determine_type(const Type_context* context)
1078 {
1079   if (context->type != NULL)
1080     this->type_ = context->type;
1081 }
1082
1083 // Return a temporary variable for a sink expression.  This will
1084 // presumably be a write-only variable which the middle-end will drop.
1085
1086 tree
1087 Sink_expression::do_get_tree(Translate_context* context)
1088 {
1089   if (this->var_ == NULL_TREE)
1090     {
1091       gcc_assert(this->type_ != NULL && !this->type_->is_sink_type());
1092       this->var_ = create_tmp_var(this->type_->get_tree(context->gogo()),
1093                                   "blank");
1094     }
1095   return this->var_;
1096 }
1097
1098 // Make a sink expression.
1099
1100 Expression*
1101 Expression::make_sink(source_location location)
1102 {
1103   return new Sink_expression(location);
1104 }
1105
1106 // Class Func_expression.
1107
1108 // FIXME: Can a function expression appear in a constant expression?
1109 // The value is unchanging.  Initializing a constant to the address of
1110 // a function seems like it could work, though there might be little
1111 // point to it.
1112
1113 // Return the name of the function.
1114
1115 const std::string&
1116 Func_expression::name() const
1117 {
1118   return this->function_->name();
1119 }
1120
1121 // Traversal.
1122
1123 int
1124 Func_expression::do_traverse(Traverse* traverse)
1125 {
1126   return (this->closure_ == NULL
1127           ? TRAVERSE_CONTINUE
1128           : Expression::traverse(&this->closure_, traverse));
1129 }
1130
1131 // Return the type of a function expression.
1132
1133 Type*
1134 Func_expression::do_type()
1135 {
1136   if (this->function_->is_function())
1137     return this->function_->func_value()->type();
1138   else if (this->function_->is_function_declaration())
1139     return this->function_->func_declaration_value()->type();
1140   else
1141     gcc_unreachable();
1142 }
1143
1144 // Get the tree for a function expression without evaluating the
1145 // closure.
1146
1147 tree
1148 Func_expression::get_tree_without_closure(Gogo* gogo)
1149 {
1150   Function_type* fntype;
1151   if (this->function_->is_function())
1152     fntype = this->function_->func_value()->type();
1153   else if (this->function_->is_function_declaration())
1154     fntype = this->function_->func_declaration_value()->type();
1155   else
1156     gcc_unreachable();
1157
1158   // Builtin functions are handled specially by Call_expression.  We
1159   // can't take their address.
1160   if (fntype->is_builtin())
1161     {
1162       error_at(this->location(), "invalid use of special builtin function %qs",
1163                this->function_->name().c_str());
1164       return error_mark_node;
1165     }
1166
1167   Named_object* no = this->function_;
1168
1169   tree id = no->get_id(gogo);
1170   if (id == error_mark_node)
1171     return error_mark_node;
1172
1173   tree fndecl;
1174   if (no->is_function())
1175     fndecl = no->func_value()->get_or_make_decl(gogo, no, id);
1176   else if (no->is_function_declaration())
1177     fndecl = no->func_declaration_value()->get_or_make_decl(gogo, no, id);
1178   else
1179     gcc_unreachable();
1180
1181   if (fndecl == error_mark_node)
1182     return error_mark_node;
1183
1184   return build_fold_addr_expr_loc(this->location(), fndecl);
1185 }
1186
1187 // Get the tree for a function expression.  This is used when we take
1188 // the address of a function rather than simply calling it.  If the
1189 // function has a closure, we must use a trampoline.
1190
1191 tree
1192 Func_expression::do_get_tree(Translate_context* context)
1193 {
1194   Gogo* gogo = context->gogo();
1195
1196   tree fnaddr = this->get_tree_without_closure(gogo);
1197   if (fnaddr == error_mark_node)
1198     return error_mark_node;
1199
1200   gcc_assert(TREE_CODE(fnaddr) == ADDR_EXPR
1201              && TREE_CODE(TREE_OPERAND(fnaddr, 0)) == FUNCTION_DECL);
1202   TREE_ADDRESSABLE(TREE_OPERAND(fnaddr, 0)) = 1;
1203
1204   // For a normal non-nested function call, that is all we have to do.
1205   if (!this->function_->is_function()
1206       || this->function_->func_value()->enclosing() == NULL)
1207     {
1208       gcc_assert(this->closure_ == NULL);
1209       return fnaddr;
1210     }
1211
1212   // For a nested function call, we have to always allocate a
1213   // trampoline.  If we don't always allocate, then closures will not
1214   // be reliably distinct.
1215   Expression* closure = this->closure_;
1216   tree closure_tree;
1217   if (closure == NULL)
1218     closure_tree = null_pointer_node;
1219   else
1220     {
1221       // Get the value of the closure.  This will be a pointer to
1222       // space allocated on the heap.
1223       closure_tree = closure->get_tree(context);
1224       if (closure_tree == error_mark_node)
1225         return error_mark_node;
1226       gcc_assert(POINTER_TYPE_P(TREE_TYPE(closure_tree)));
1227     }
1228
1229   // Now we need to build some code on the heap.  This code will load
1230   // the static chain pointer with the closure and then jump to the
1231   // body of the function.  The normal gcc approach is to build the
1232   // code on the stack.  Unfortunately we can not do that, as Go
1233   // permits us to return the function pointer.
1234
1235   return gogo->make_trampoline(fnaddr, closure_tree, this->location());
1236 }
1237
1238 // Make a reference to a function in an expression.
1239
1240 Expression*
1241 Expression::make_func_reference(Named_object* function, Expression* closure,
1242                                 source_location location)
1243 {
1244   return new Func_expression(function, closure, location);
1245 }
1246
1247 // Class Unknown_expression.
1248
1249 // Return the name of an unknown expression.
1250
1251 const std::string&
1252 Unknown_expression::name() const
1253 {
1254   return this->named_object_->name();
1255 }
1256
1257 // Lower a reference to an unknown name.
1258
1259 Expression*
1260 Unknown_expression::do_lower(Gogo*, Named_object*, int)
1261 {
1262   source_location location = this->location();
1263   Named_object* no = this->named_object_;
1264   Named_object* real;
1265   if (!no->is_unknown())
1266     real = no;
1267   else
1268     {
1269       real = no->unknown_value()->real_named_object();
1270       if (real == NULL)
1271         {
1272           if (this->is_composite_literal_key_)
1273             return this;
1274           error_at(location, "reference to undefined name %qs",
1275                    this->named_object_->message_name().c_str());
1276           return Expression::make_error(location);
1277         }
1278     }
1279   switch (real->classification())
1280     {
1281     case Named_object::NAMED_OBJECT_CONST:
1282       return Expression::make_const_reference(real, location);
1283     case Named_object::NAMED_OBJECT_TYPE:
1284       return Expression::make_type(real->type_value(), location);
1285     case Named_object::NAMED_OBJECT_TYPE_DECLARATION:
1286       if (this->is_composite_literal_key_)
1287         return this;
1288       error_at(location, "reference to undefined type %qs",
1289                real->message_name().c_str());
1290       return Expression::make_error(location);
1291     case Named_object::NAMED_OBJECT_VAR:
1292       return Expression::make_var_reference(real, location);
1293     case Named_object::NAMED_OBJECT_FUNC:
1294     case Named_object::NAMED_OBJECT_FUNC_DECLARATION:
1295       return Expression::make_func_reference(real, NULL, location);
1296     case Named_object::NAMED_OBJECT_PACKAGE:
1297       if (this->is_composite_literal_key_)
1298         return this;
1299       error_at(location, "unexpected reference to package");
1300       return Expression::make_error(location);
1301     default:
1302       gcc_unreachable();
1303     }
1304 }
1305
1306 // Make a reference to an unknown name.
1307
1308 Expression*
1309 Expression::make_unknown_reference(Named_object* no, source_location location)
1310 {
1311   gcc_assert(no->resolve()->is_unknown());
1312   return new Unknown_expression(no, location);
1313 }
1314
1315 // A boolean expression.
1316
1317 class Boolean_expression : public Expression
1318 {
1319  public:
1320   Boolean_expression(bool val, source_location location)
1321     : Expression(EXPRESSION_BOOLEAN, location),
1322       val_(val), type_(NULL)
1323   { }
1324
1325   static Expression*
1326   do_import(Import*);
1327
1328  protected:
1329   bool
1330   do_is_constant() const
1331   { return true; }
1332
1333   Type*
1334   do_type();
1335
1336   void
1337   do_determine_type(const Type_context*);
1338
1339   Expression*
1340   do_copy()
1341   { return this; }
1342
1343   tree
1344   do_get_tree(Translate_context*)
1345   { return this->val_ ? boolean_true_node : boolean_false_node; }
1346
1347   void
1348   do_export(Export* exp) const
1349   { exp->write_c_string(this->val_ ? "true" : "false"); }
1350
1351  private:
1352   // The constant.
1353   bool val_;
1354   // The type as determined by context.
1355   Type* type_;
1356 };
1357
1358 // Get the type.
1359
1360 Type*
1361 Boolean_expression::do_type()
1362 {
1363   if (this->type_ == NULL)
1364     this->type_ = Type::make_boolean_type();
1365   return this->type_;
1366 }
1367
1368 // Set the type from the context.
1369
1370 void
1371 Boolean_expression::do_determine_type(const Type_context* context)
1372 {
1373   if (this->type_ != NULL && !this->type_->is_abstract())
1374     ;
1375   else if (context->type != NULL && context->type->is_boolean_type())
1376     this->type_ = context->type;
1377   else if (!context->may_be_abstract)
1378     this->type_ = Type::lookup_bool_type();
1379 }
1380
1381 // Import a boolean constant.
1382
1383 Expression*
1384 Boolean_expression::do_import(Import* imp)
1385 {
1386   if (imp->peek_char() == 't')
1387     {
1388       imp->require_c_string("true");
1389       return Expression::make_boolean(true, imp->location());
1390     }
1391   else
1392     {
1393       imp->require_c_string("false");
1394       return Expression::make_boolean(false, imp->location());
1395     }
1396 }
1397
1398 // Make a boolean expression.
1399
1400 Expression*
1401 Expression::make_boolean(bool val, source_location location)
1402 {
1403   return new Boolean_expression(val, location);
1404 }
1405
1406 // Class String_expression.
1407
1408 // Get the type.
1409
1410 Type*
1411 String_expression::do_type()
1412 {
1413   if (this->type_ == NULL)
1414     this->type_ = Type::make_string_type();
1415   return this->type_;
1416 }
1417
1418 // Set the type from the context.
1419
1420 void
1421 String_expression::do_determine_type(const Type_context* context)
1422 {
1423   if (this->type_ != NULL && !this->type_->is_abstract())
1424     ;
1425   else if (context->type != NULL && context->type->is_string_type())
1426     this->type_ = context->type;
1427   else if (!context->may_be_abstract)
1428     this->type_ = Type::lookup_string_type();
1429 }
1430
1431 // Build a string constant.
1432
1433 tree
1434 String_expression::do_get_tree(Translate_context* context)
1435 {
1436   return context->gogo()->go_string_constant_tree(this->val_);
1437 }
1438
1439 // Export a string expression.
1440
1441 void
1442 String_expression::do_export(Export* exp) const
1443 {
1444   std::string s;
1445   s.reserve(this->val_.length() * 4 + 2);
1446   s += '"';
1447   for (std::string::const_iterator p = this->val_.begin();
1448        p != this->val_.end();
1449        ++p)
1450     {
1451       if (*p == '\\' || *p == '"')
1452         {
1453           s += '\\';
1454           s += *p;
1455         }
1456       else if (*p >= 0x20 && *p < 0x7f)
1457         s += *p;
1458       else if (*p == '\n')
1459         s += "\\n";
1460       else if (*p == '\t')
1461         s += "\\t";
1462       else
1463         {
1464           s += "\\x";
1465           unsigned char c = *p;
1466           unsigned int dig = c >> 4;
1467           s += dig < 10 ? '0' + dig : 'A' + dig - 10;
1468           dig = c & 0xf;
1469           s += dig < 10 ? '0' + dig : 'A' + dig - 10;
1470         }
1471     }
1472   s += '"';
1473   exp->write_string(s);
1474 }
1475
1476 // Import a string expression.
1477
1478 Expression*
1479 String_expression::do_import(Import* imp)
1480 {
1481   imp->require_c_string("\"");
1482   std::string val;
1483   while (true)
1484     {
1485       int c = imp->get_char();
1486       if (c == '"' || c == -1)
1487         break;
1488       if (c != '\\')
1489         val += static_cast<char>(c);
1490       else
1491         {
1492           c = imp->get_char();
1493           if (c == '\\' || c == '"')
1494             val += static_cast<char>(c);
1495           else if (c == 'n')
1496             val += '\n';
1497           else if (c == 't')
1498             val += '\t';
1499           else if (c == 'x')
1500             {
1501               c = imp->get_char();
1502               unsigned int vh = c >= '0' && c <= '9' ? c - '0' : c - 'A' + 10;
1503               c = imp->get_char();
1504               unsigned int vl = c >= '0' && c <= '9' ? c - '0' : c - 'A' + 10;
1505               char v = (vh << 4) | vl;
1506               val += v;
1507             }
1508           else
1509             {
1510               error_at(imp->location(), "bad string constant");
1511               return Expression::make_error(imp->location());
1512             }
1513         }
1514     }
1515   return Expression::make_string(val, imp->location());
1516 }
1517
1518 // Make a string expression.
1519
1520 Expression*
1521 Expression::make_string(const std::string& val, source_location location)
1522 {
1523   return new String_expression(val, location);
1524 }
1525
1526 // Make an integer expression.
1527
1528 class Integer_expression : public Expression
1529 {
1530  public:
1531   Integer_expression(const mpz_t* val, Type* type, source_location location)
1532     : Expression(EXPRESSION_INTEGER, location),
1533       type_(type)
1534   { mpz_init_set(this->val_, *val); }
1535
1536   static Expression*
1537   do_import(Import*);
1538
1539   // Return whether VAL fits in the type.
1540   static bool
1541   check_constant(mpz_t val, Type*, source_location);
1542
1543   // Write VAL to export data.
1544   static void
1545   export_integer(Export* exp, const mpz_t val);
1546
1547  protected:
1548   bool
1549   do_is_constant() const
1550   { return true; }
1551
1552   bool
1553   do_integer_constant_value(bool, mpz_t val, Type** ptype) const;
1554
1555   Type*
1556   do_type();
1557
1558   void
1559   do_determine_type(const Type_context* context);
1560
1561   void
1562   do_check_types(Gogo*);
1563
1564   tree
1565   do_get_tree(Translate_context*);
1566
1567   Expression*
1568   do_copy()
1569   { return Expression::make_integer(&this->val_, this->type_,
1570                                     this->location()); }
1571
1572   void
1573   do_export(Export*) const;
1574
1575  private:
1576   // The integer value.
1577   mpz_t val_;
1578   // The type so far.
1579   Type* type_;
1580 };
1581
1582 // Return an integer constant value.
1583
1584 bool
1585 Integer_expression::do_integer_constant_value(bool, mpz_t val,
1586                                               Type** ptype) const
1587 {
1588   if (this->type_ != NULL)
1589     *ptype = this->type_;
1590   mpz_set(val, this->val_);
1591   return true;
1592 }
1593
1594 // Return the current type.  If we haven't set the type yet, we return
1595 // an abstract integer type.
1596
1597 Type*
1598 Integer_expression::do_type()
1599 {
1600   if (this->type_ == NULL)
1601     this->type_ = Type::make_abstract_integer_type();
1602   return this->type_;
1603 }
1604
1605 // Set the type of the integer value.  Here we may switch from an
1606 // abstract type to a real type.
1607
1608 void
1609 Integer_expression::do_determine_type(const Type_context* context)
1610 {
1611   if (this->type_ != NULL && !this->type_->is_abstract())
1612     ;
1613   else if (context->type != NULL
1614            && (context->type->integer_type() != NULL
1615                || context->type->float_type() != NULL
1616                || context->type->complex_type() != NULL))
1617     this->type_ = context->type;
1618   else if (!context->may_be_abstract)
1619     this->type_ = Type::lookup_integer_type("int");
1620 }
1621
1622 // Return true if the integer VAL fits in the range of the type TYPE.
1623 // Otherwise give an error and return false.  TYPE may be NULL.
1624
1625 bool
1626 Integer_expression::check_constant(mpz_t val, Type* type,
1627                                    source_location location)
1628 {
1629   if (type == NULL)
1630     return true;
1631   Integer_type* itype = type->integer_type();
1632   if (itype == NULL || itype->is_abstract())
1633     return true;
1634
1635   int bits = mpz_sizeinbase(val, 2);
1636
1637   if (itype->is_unsigned())
1638     {
1639       // For an unsigned type we can only accept a nonnegative number,
1640       // and we must be able to represent at least BITS.
1641       if (mpz_sgn(val) >= 0
1642           && bits <= itype->bits())
1643         return true;
1644     }
1645   else
1646     {
1647       // For a signed type we need an extra bit to indicate the sign.
1648       // We have to handle the most negative integer specially.
1649       if (bits + 1 <= itype->bits()
1650           || (bits <= itype->bits()
1651               && mpz_sgn(val) < 0
1652               && (mpz_scan1(val, 0)
1653                   == static_cast<unsigned long>(itype->bits() - 1))
1654               && mpz_scan0(val, itype->bits()) == ULONG_MAX))
1655         return true;
1656     }
1657
1658   error_at(location, "integer constant overflow");
1659   return false;
1660 }
1661
1662 // Check the type of an integer constant.
1663
1664 void
1665 Integer_expression::do_check_types(Gogo*)
1666 {
1667   if (this->type_ == NULL)
1668     return;
1669   if (!Integer_expression::check_constant(this->val_, this->type_,
1670                                           this->location()))
1671     this->set_is_error();
1672 }
1673
1674 // Get a tree for an integer constant.
1675
1676 tree
1677 Integer_expression::do_get_tree(Translate_context* context)
1678 {
1679   Gogo* gogo = context->gogo();
1680   tree type;
1681   if (this->type_ != NULL && !this->type_->is_abstract())
1682     type = this->type_->get_tree(gogo);
1683   else if (this->type_ != NULL && this->type_->float_type() != NULL)
1684     {
1685       // We are converting to an abstract floating point type.
1686       type = Type::lookup_float_type("float64")->get_tree(gogo);
1687     }
1688   else if (this->type_ != NULL && this->type_->complex_type() != NULL)
1689     {
1690       // We are converting to an abstract complex type.
1691       type = Type::lookup_complex_type("complex128")->get_tree(gogo);
1692     }
1693   else
1694     {
1695       // If we still have an abstract type here, then this is being
1696       // used in a constant expression which didn't get reduced for
1697       // some reason.  Use a type which will fit the value.  We use <,
1698       // not <=, because we need an extra bit for the sign bit.
1699       int bits = mpz_sizeinbase(this->val_, 2);
1700       if (bits < INT_TYPE_SIZE)
1701         type = Type::lookup_integer_type("int")->get_tree(gogo);
1702       else if (bits < 64)
1703         type = Type::lookup_integer_type("int64")->get_tree(gogo);
1704       else
1705         type = long_long_integer_type_node;
1706     }
1707   return Expression::integer_constant_tree(this->val_, type);
1708 }
1709
1710 // Write VAL to export data.
1711
1712 void
1713 Integer_expression::export_integer(Export* exp, const mpz_t val)
1714 {
1715   char* s = mpz_get_str(NULL, 10, val);
1716   exp->write_c_string(s);
1717   free(s);
1718 }
1719
1720 // Export an integer in a constant expression.
1721
1722 void
1723 Integer_expression::do_export(Export* exp) const
1724 {
1725   Integer_expression::export_integer(exp, this->val_);
1726   // A trailing space lets us reliably identify the end of the number.
1727   exp->write_c_string(" ");
1728 }
1729
1730 // Import an integer, floating point, or complex value.  This handles
1731 // all these types because they all start with digits.
1732
1733 Expression*
1734 Integer_expression::do_import(Import* imp)
1735 {
1736   std::string num = imp->read_identifier();
1737   imp->require_c_string(" ");
1738   if (!num.empty() && num[num.length() - 1] == 'i')
1739     {
1740       mpfr_t real;
1741       size_t plus_pos = num.find('+', 1);
1742       size_t minus_pos = num.find('-', 1);
1743       size_t pos;
1744       if (plus_pos == std::string::npos)
1745         pos = minus_pos;
1746       else if (minus_pos == std::string::npos)
1747         pos = plus_pos;
1748       else
1749         {
1750           error_at(imp->location(), "bad number in import data: %qs",
1751                    num.c_str());
1752           return Expression::make_error(imp->location());
1753         }
1754       if (pos == std::string::npos)
1755         mpfr_set_ui(real, 0, GMP_RNDN);
1756       else
1757         {
1758           std::string real_str = num.substr(0, pos);
1759           if (mpfr_init_set_str(real, real_str.c_str(), 10, GMP_RNDN) != 0)
1760             {
1761               error_at(imp->location(), "bad number in import data: %qs",
1762                        real_str.c_str());
1763               return Expression::make_error(imp->location());
1764             }
1765         }
1766
1767       std::string imag_str;
1768       if (pos == std::string::npos)
1769         imag_str = num;
1770       else
1771         imag_str = num.substr(pos);
1772       imag_str = imag_str.substr(0, imag_str.size() - 1);
1773       mpfr_t imag;
1774       if (mpfr_init_set_str(imag, imag_str.c_str(), 10, GMP_RNDN) != 0)
1775         {
1776           error_at(imp->location(), "bad number in import data: %qs",
1777                    imag_str.c_str());
1778           return Expression::make_error(imp->location());
1779         }
1780       Expression* ret = Expression::make_complex(&real, &imag, NULL,
1781                                                  imp->location());
1782       mpfr_clear(real);
1783       mpfr_clear(imag);
1784       return ret;
1785     }
1786   else if (num.find('.') == std::string::npos
1787            && num.find('E') == std::string::npos)
1788     {
1789       mpz_t val;
1790       if (mpz_init_set_str(val, num.c_str(), 10) != 0)
1791         {
1792           error_at(imp->location(), "bad number in import data: %qs",
1793                    num.c_str());
1794           return Expression::make_error(imp->location());
1795         }
1796       Expression* ret = Expression::make_integer(&val, NULL, imp->location());
1797       mpz_clear(val);
1798       return ret;
1799     }
1800   else
1801     {
1802       mpfr_t val;
1803       if (mpfr_init_set_str(val, num.c_str(), 10, GMP_RNDN) != 0)
1804         {
1805           error_at(imp->location(), "bad number in import data: %qs",
1806                    num.c_str());
1807           return Expression::make_error(imp->location());
1808         }
1809       Expression* ret = Expression::make_float(&val, NULL, imp->location());
1810       mpfr_clear(val);
1811       return ret;
1812     }
1813 }
1814
1815 // Build a new integer value.
1816
1817 Expression*
1818 Expression::make_integer(const mpz_t* val, Type* type,
1819                          source_location location)
1820 {
1821   return new Integer_expression(val, type, location);
1822 }
1823
1824 // Floats.
1825
1826 class Float_expression : public Expression
1827 {
1828  public:
1829   Float_expression(const mpfr_t* val, Type* type, source_location location)
1830     : Expression(EXPRESSION_FLOAT, location),
1831       type_(type)
1832   {
1833     mpfr_init_set(this->val_, *val, GMP_RNDN);
1834   }
1835
1836   // Constrain VAL to fit into TYPE.
1837   static void
1838   constrain_float(mpfr_t val, Type* type);
1839
1840   // Return whether VAL fits in the type.
1841   static bool
1842   check_constant(mpfr_t val, Type*, source_location);
1843
1844   // Write VAL to export data.
1845   static void
1846   export_float(Export* exp, const mpfr_t val);
1847
1848  protected:
1849   bool
1850   do_is_constant() const
1851   { return true; }
1852
1853   bool
1854   do_float_constant_value(mpfr_t val, Type**) const;
1855
1856   Type*
1857   do_type();
1858
1859   void
1860   do_determine_type(const Type_context*);
1861
1862   void
1863   do_check_types(Gogo*);
1864
1865   Expression*
1866   do_copy()
1867   { return Expression::make_float(&this->val_, this->type_,
1868                                   this->location()); }
1869
1870   tree
1871   do_get_tree(Translate_context*);
1872
1873   void
1874   do_export(Export*) const;
1875
1876  private:
1877   // The floating point value.
1878   mpfr_t val_;
1879   // The type so far.
1880   Type* type_;
1881 };
1882
1883 // Constrain VAL to fit into TYPE.
1884
1885 void
1886 Float_expression::constrain_float(mpfr_t val, Type* type)
1887 {
1888   Float_type* ftype = type->float_type();
1889   if (ftype != NULL && !ftype->is_abstract())
1890     {
1891       tree type_tree = ftype->type_tree();
1892       REAL_VALUE_TYPE rvt;
1893       real_from_mpfr(&rvt, val, type_tree, GMP_RNDN);
1894       real_convert(&rvt, TYPE_MODE(type_tree), &rvt);
1895       mpfr_from_real(val, &rvt, GMP_RNDN);
1896     }
1897 }
1898
1899 // Return a floating point constant value.
1900
1901 bool
1902 Float_expression::do_float_constant_value(mpfr_t val, Type** ptype) const
1903 {
1904   if (this->type_ != NULL)
1905     *ptype = this->type_;
1906   mpfr_set(val, this->val_, GMP_RNDN);
1907   return true;
1908 }
1909
1910 // Return the current type.  If we haven't set the type yet, we return
1911 // an abstract float type.
1912
1913 Type*
1914 Float_expression::do_type()
1915 {
1916   if (this->type_ == NULL)
1917     this->type_ = Type::make_abstract_float_type();
1918   return this->type_;
1919 }
1920
1921 // Set the type of the float value.  Here we may switch from an
1922 // abstract type to a real type.
1923
1924 void
1925 Float_expression::do_determine_type(const Type_context* context)
1926 {
1927   if (this->type_ != NULL && !this->type_->is_abstract())
1928     ;
1929   else if (context->type != NULL
1930            && (context->type->integer_type() != NULL
1931                || context->type->float_type() != NULL
1932                || context->type->complex_type() != NULL))
1933     this->type_ = context->type;
1934   else if (!context->may_be_abstract)
1935     this->type_ = Type::lookup_float_type("float");
1936 }
1937
1938 // Return true if the floating point value VAL fits in the range of
1939 // the type TYPE.  Otherwise give an error and return false.  TYPE may
1940 // be NULL.
1941
1942 bool
1943 Float_expression::check_constant(mpfr_t val, Type* type,
1944                                  source_location location)
1945 {
1946   if (type == NULL)
1947     return true;
1948   Float_type* ftype = type->float_type();
1949   if (ftype == NULL || ftype->is_abstract())
1950     return true;
1951
1952   // A NaN or Infinity always fits in the range of the type.
1953   if (mpfr_nan_p(val) || mpfr_inf_p(val) || mpfr_zero_p(val))
1954     return true;
1955
1956   mp_exp_t exp = mpfr_get_exp(val);
1957   mp_exp_t max_exp;
1958   switch (ftype->bits())
1959     {
1960     case 32:
1961       max_exp = 128;
1962       break;
1963     case 64:
1964       max_exp = 1024;
1965       break;
1966     default:
1967       gcc_unreachable();
1968     }
1969   if (exp > max_exp)
1970     {
1971       error_at(location, "floating point constant overflow");
1972       return false;
1973     }
1974   return true;
1975 }
1976
1977 // Check the type of a float value.
1978
1979 void
1980 Float_expression::do_check_types(Gogo*)
1981 {
1982   if (this->type_ == NULL)
1983     return;
1984
1985   if (!Float_expression::check_constant(this->val_, this->type_,
1986                                         this->location()))
1987     this->set_is_error();
1988
1989   Integer_type* integer_type = this->type_->integer_type();
1990   if (integer_type != NULL)
1991     {
1992       if (!mpfr_integer_p(this->val_))
1993         this->report_error(_("floating point constant truncated to integer"));
1994       else
1995         {
1996           gcc_assert(!integer_type->is_abstract());
1997           mpz_t ival;
1998           mpz_init(ival);
1999           mpfr_get_z(ival, this->val_, GMP_RNDN);
2000           Integer_expression::check_constant(ival, integer_type,
2001                                              this->location());
2002           mpz_clear(ival);
2003         }
2004     }
2005 }
2006
2007 // Get a tree for a float constant.
2008
2009 tree
2010 Float_expression::do_get_tree(Translate_context* context)
2011 {
2012   Gogo* gogo = context->gogo();
2013   tree type;
2014   if (this->type_ != NULL && !this->type_->is_abstract())
2015     type = this->type_->get_tree(gogo);
2016   else if (this->type_ != NULL && this->type_->integer_type() != NULL)
2017     {
2018       // We have an abstract integer type.  We just hope for the best.
2019       type = Type::lookup_integer_type("int")->get_tree(gogo);
2020     }
2021   else
2022     {
2023       // If we still have an abstract type here, then this is being
2024       // used in a constant expression which didn't get reduced.  We
2025       // just use float64 and hope for the best.
2026       type = Type::lookup_float_type("float64")->get_tree(gogo);
2027     }
2028   return Expression::float_constant_tree(this->val_, type);
2029 }
2030
2031 // Write a floating point number to export data.
2032
2033 void
2034 Float_expression::export_float(Export *exp, const mpfr_t val)
2035 {
2036   mp_exp_t exponent;
2037   char* s = mpfr_get_str(NULL, &exponent, 10, 0, val, GMP_RNDN);
2038   if (*s == '-')
2039     exp->write_c_string("-");
2040   exp->write_c_string("0.");
2041   exp->write_c_string(*s == '-' ? s + 1 : s);
2042   mpfr_free_str(s);
2043   char buf[30];
2044   snprintf(buf, sizeof buf, "E%ld", exponent);
2045   exp->write_c_string(buf);
2046 }
2047
2048 // Export a floating point number in a constant expression.
2049
2050 void
2051 Float_expression::do_export(Export* exp) const
2052 {
2053   Float_expression::export_float(exp, this->val_);
2054   // A trailing space lets us reliably identify the end of the number.
2055   exp->write_c_string(" ");
2056 }
2057
2058 // Make a float expression.
2059
2060 Expression*
2061 Expression::make_float(const mpfr_t* val, Type* type, source_location location)
2062 {
2063   return new Float_expression(val, type, location);
2064 }
2065
2066 // Complex numbers.
2067
2068 class Complex_expression : public Expression
2069 {
2070  public:
2071   Complex_expression(const mpfr_t* real, const mpfr_t* imag, Type* type,
2072                      source_location location)
2073     : Expression(EXPRESSION_COMPLEX, location),
2074       type_(type)
2075   {
2076     mpfr_init_set(this->real_, *real, GMP_RNDN);
2077     mpfr_init_set(this->imag_, *imag, GMP_RNDN);
2078   }
2079
2080   // Constrain REAL/IMAG to fit into TYPE.
2081   static void
2082   constrain_complex(mpfr_t real, mpfr_t imag, Type* type);
2083
2084   // Return whether REAL/IMAG fits in the type.
2085   static bool
2086   check_constant(mpfr_t real, mpfr_t imag, Type*, source_location);
2087
2088   // Write REAL/IMAG to export data.
2089   static void
2090   export_complex(Export* exp, const mpfr_t real, const mpfr_t val);
2091
2092  protected:
2093   bool
2094   do_is_constant() const
2095   { return true; }
2096
2097   bool
2098   do_complex_constant_value(mpfr_t real, mpfr_t imag, Type**) const;
2099
2100   Type*
2101   do_type();
2102
2103   void
2104   do_determine_type(const Type_context*);
2105
2106   void
2107   do_check_types(Gogo*);
2108
2109   Expression*
2110   do_copy()
2111   {
2112     return Expression::make_complex(&this->real_, &this->imag_, this->type_,
2113                                     this->location());
2114   }
2115
2116   tree
2117   do_get_tree(Translate_context*);
2118
2119   void
2120   do_export(Export*) const;
2121
2122  private:
2123   // The real part.
2124   mpfr_t real_;
2125   // The imaginary part;
2126   mpfr_t imag_;
2127   // The type if known.
2128   Type* type_;
2129 };
2130
2131 // Constrain REAL/IMAG to fit into TYPE.
2132
2133 void
2134 Complex_expression::constrain_complex(mpfr_t real, mpfr_t imag, Type* type)
2135 {
2136   Complex_type* ctype = type->complex_type();
2137   if (ctype != NULL && !ctype->is_abstract())
2138     {
2139       tree type_tree = ctype->type_tree();
2140
2141       REAL_VALUE_TYPE rvt;
2142       real_from_mpfr(&rvt, real, TREE_TYPE(type_tree), GMP_RNDN);
2143       real_convert(&rvt, TYPE_MODE(TREE_TYPE(type_tree)), &rvt);
2144       mpfr_from_real(real, &rvt, GMP_RNDN);
2145
2146       real_from_mpfr(&rvt, imag, TREE_TYPE(type_tree), GMP_RNDN);
2147       real_convert(&rvt, TYPE_MODE(TREE_TYPE(type_tree)), &rvt);
2148       mpfr_from_real(imag, &rvt, GMP_RNDN);
2149     }
2150 }
2151
2152 // Return a complex constant value.
2153
2154 bool
2155 Complex_expression::do_complex_constant_value(mpfr_t real, mpfr_t imag,
2156                                               Type** ptype) const
2157 {
2158   if (this->type_ != NULL)
2159     *ptype = this->type_;
2160   mpfr_set(real, this->real_, GMP_RNDN);
2161   mpfr_set(imag, this->imag_, GMP_RNDN);
2162   return true;
2163 }
2164
2165 // Return the current type.  If we haven't set the type yet, we return
2166 // an abstract complex type.
2167
2168 Type*
2169 Complex_expression::do_type()
2170 {
2171   if (this->type_ == NULL)
2172     this->type_ = Type::make_abstract_complex_type();
2173   return this->type_;
2174 }
2175
2176 // Set the type of the complex value.  Here we may switch from an
2177 // abstract type to a real type.
2178
2179 void
2180 Complex_expression::do_determine_type(const Type_context* context)
2181 {
2182   if (this->type_ != NULL && !this->type_->is_abstract())
2183     ;
2184   else if (context->type != NULL
2185            && context->type->complex_type() != NULL)
2186     this->type_ = context->type;
2187   else if (!context->may_be_abstract)
2188     this->type_ = Type::lookup_complex_type("complex");
2189 }
2190
2191 // Return true if the complex value REAL/IMAG fits in the range of the
2192 // type TYPE.  Otherwise give an error and return false.  TYPE may be
2193 // NULL.
2194
2195 bool
2196 Complex_expression::check_constant(mpfr_t real, mpfr_t imag, Type* type,
2197                                    source_location location)
2198 {
2199   if (type == NULL)
2200     return true;
2201   Complex_type* ctype = type->complex_type();
2202   if (ctype == NULL || ctype->is_abstract())
2203     return true;
2204
2205   mp_exp_t max_exp;
2206   switch (ctype->bits())
2207     {
2208     case 64:
2209       max_exp = 128;
2210       break;
2211     case 128:
2212       max_exp = 1024;
2213       break;
2214     default:
2215       gcc_unreachable();
2216     }
2217
2218   // A NaN or Infinity always fits in the range of the type.
2219   if (!mpfr_nan_p(real) && !mpfr_inf_p(real) && !mpfr_zero_p(real))
2220     {
2221       if (mpfr_get_exp(real) > max_exp)
2222         {
2223           error_at(location, "complex real part constant overflow");
2224           return false;
2225         }
2226     }
2227
2228   if (!mpfr_nan_p(imag) && !mpfr_inf_p(imag) && !mpfr_zero_p(imag))
2229     {
2230       if (mpfr_get_exp(imag) > max_exp)
2231         {
2232           error_at(location, "complex imaginary part constant overflow");
2233           return false;
2234         }
2235     }
2236
2237   return true;
2238 }
2239
2240 // Check the type of a complex value.
2241
2242 void
2243 Complex_expression::do_check_types(Gogo*)
2244 {
2245   if (this->type_ == NULL)
2246     return;
2247
2248   if (!Complex_expression::check_constant(this->real_, this->imag_,
2249                                           this->type_, this->location()))
2250     this->set_is_error();
2251 }
2252
2253 // Get a tree for a complex constant.
2254
2255 tree
2256 Complex_expression::do_get_tree(Translate_context* context)
2257 {
2258   Gogo* gogo = context->gogo();
2259   tree type;
2260   if (this->type_ != NULL && !this->type_->is_abstract())
2261     type = this->type_->get_tree(gogo);
2262   else
2263     {
2264       // If we still have an abstract type here, this this is being
2265       // used in a constant expression which didn't get reduced.  We
2266       // just use complex128 and hope for the best.
2267       type = Type::lookup_complex_type("complex128")->get_tree(gogo);
2268     }
2269   return Expression::complex_constant_tree(this->real_, this->imag_, type);
2270 }
2271
2272 // Write REAL/IMAG to export data.
2273
2274 void
2275 Complex_expression::export_complex(Export* exp, const mpfr_t real,
2276                                    const mpfr_t imag)
2277 {
2278   if (!mpfr_zero_p(real))
2279     {
2280       Float_expression::export_float(exp, real);
2281       if (mpfr_sgn(imag) > 0)
2282         exp->write_c_string("+");
2283     }
2284   Float_expression::export_float(exp, imag);
2285   exp->write_c_string("i");
2286 }
2287
2288 // Export a complex number in a constant expression.
2289
2290 void
2291 Complex_expression::do_export(Export* exp) const
2292 {
2293   Complex_expression::export_complex(exp, this->real_, this->imag_);
2294   // A trailing space lets us reliably identify the end of the number.
2295   exp->write_c_string(" ");
2296 }
2297
2298 // Make a complex expression.
2299
2300 Expression*
2301 Expression::make_complex(const mpfr_t* real, const mpfr_t* imag, Type* type,
2302                          source_location location)
2303 {
2304   return new Complex_expression(real, imag, type, location);
2305 }
2306
2307 // Find a named object in an expression.
2308
2309 class Find_named_object : public Traverse
2310 {
2311  public:
2312   Find_named_object(Named_object* no)
2313     : Traverse(traverse_expressions),
2314       no_(no), found_(false)
2315   { }
2316
2317   // Whether we found the object.
2318   bool
2319   found() const
2320   { return this->found_; }
2321
2322  protected:
2323   int
2324   expression(Expression**);
2325
2326  private:
2327   // The object we are looking for.
2328   Named_object* no_;
2329   // Whether we found it.
2330   bool found_;
2331 };
2332
2333 // A reference to a const in an expression.
2334
2335 class Const_expression : public Expression
2336 {
2337  public:
2338   Const_expression(Named_object* constant, source_location location)
2339     : Expression(EXPRESSION_CONST_REFERENCE, location),
2340       constant_(constant), type_(NULL), seen_(false)
2341   { }
2342
2343   Named_object*
2344   named_object()
2345   { return this->constant_; }
2346
2347   const std::string&
2348   name() const
2349   { return this->constant_->name(); }
2350
2351  protected:
2352   Expression*
2353   do_lower(Gogo*, Named_object*, int);
2354
2355   bool
2356   do_is_constant() const
2357   { return true; }
2358
2359   bool
2360   do_integer_constant_value(bool, mpz_t val, Type**) const;
2361
2362   bool
2363   do_float_constant_value(mpfr_t val, Type**) const;
2364
2365   bool
2366   do_complex_constant_value(mpfr_t real, mpfr_t imag, Type**) const;
2367
2368   bool
2369   do_string_constant_value(std::string* val) const
2370   { return this->constant_->const_value()->expr()->string_constant_value(val); }
2371
2372   Type*
2373   do_type();
2374
2375   // The type of a const is set by the declaration, not the use.
2376   void
2377   do_determine_type(const Type_context*);
2378
2379   void
2380   do_check_types(Gogo*);
2381
2382   Expression*
2383   do_copy()
2384   { return this; }
2385
2386   tree
2387   do_get_tree(Translate_context* context);
2388
2389   // When exporting a reference to a const as part of a const
2390   // expression, we export the value.  We ignore the fact that it has
2391   // a name.
2392   void
2393   do_export(Export* exp) const
2394   { this->constant_->const_value()->expr()->export_expression(exp); }
2395
2396  private:
2397   // The constant.
2398   Named_object* constant_;
2399   // The type of this reference.  This is used if the constant has an
2400   // abstract type.
2401   Type* type_;
2402   // Used to prevent infinite recursion when a constant incorrectly
2403   // refers to itself.
2404   mutable bool seen_;
2405 };
2406
2407 // Lower a constant expression.  This is where we convert the
2408 // predeclared constant iota into an integer value.
2409
2410 Expression*
2411 Const_expression::do_lower(Gogo* gogo, Named_object*, int iota_value)
2412 {
2413   if (this->constant_->const_value()->expr()->classification()
2414       == EXPRESSION_IOTA)
2415     {
2416       if (iota_value == -1)
2417         {
2418           error_at(this->location(),
2419                    "iota is only defined in const declarations");
2420           iota_value = 0;
2421         }
2422       mpz_t val;
2423       mpz_init_set_ui(val, static_cast<unsigned long>(iota_value));
2424       Expression* ret = Expression::make_integer(&val, NULL,
2425                                                  this->location());
2426       mpz_clear(val);
2427       return ret;
2428     }
2429
2430   // Make sure that the constant itself has been lowered.
2431   gogo->lower_constant(this->constant_);
2432
2433   return this;
2434 }
2435
2436 // Return an integer constant value.
2437
2438 bool
2439 Const_expression::do_integer_constant_value(bool iota_is_constant, mpz_t val,
2440                                             Type** ptype) const
2441 {
2442   if (this->seen_)
2443     return false;
2444
2445   Type* ctype;
2446   if (this->type_ != NULL)
2447     ctype = this->type_;
2448   else
2449     ctype = this->constant_->const_value()->type();
2450   if (ctype != NULL && ctype->integer_type() == NULL)
2451     return false;
2452
2453   Expression* e = this->constant_->const_value()->expr();
2454
2455   this->seen_ = true;
2456
2457   Type* t;
2458   bool r = e->integer_constant_value(iota_is_constant, val, &t);
2459
2460   this->seen_ = false;
2461
2462   if (r
2463       && ctype != NULL
2464       && !Integer_expression::check_constant(val, ctype, this->location()))
2465     return false;
2466
2467   *ptype = ctype != NULL ? ctype : t;
2468   return r;
2469 }
2470
2471 // Return a floating point constant value.
2472
2473 bool
2474 Const_expression::do_float_constant_value(mpfr_t val, Type** ptype) const
2475 {
2476   if (this->seen_)
2477     return false;
2478
2479   Type* ctype;
2480   if (this->type_ != NULL)
2481     ctype = this->type_;
2482   else
2483     ctype = this->constant_->const_value()->type();
2484   if (ctype != NULL && ctype->float_type() == NULL)
2485     return false;
2486
2487   this->seen_ = true;
2488
2489   Type* t;
2490   bool r = this->constant_->const_value()->expr()->float_constant_value(val,
2491                                                                         &t);
2492
2493   this->seen_ = false;
2494
2495   if (r && ctype != NULL)
2496     {
2497       if (!Float_expression::check_constant(val, ctype, this->location()))
2498         return false;
2499       Float_expression::constrain_float(val, ctype);
2500     }
2501   *ptype = ctype != NULL ? ctype : t;
2502   return r;
2503 }
2504
2505 // Return a complex constant value.
2506
2507 bool
2508 Const_expression::do_complex_constant_value(mpfr_t real, mpfr_t imag,
2509                                             Type **ptype) const
2510 {
2511   if (this->seen_)
2512     return false;
2513
2514   Type* ctype;
2515   if (this->type_ != NULL)
2516     ctype = this->type_;
2517   else
2518     ctype = this->constant_->const_value()->type();
2519   if (ctype != NULL && ctype->complex_type() == NULL)
2520     return false;
2521
2522   this->seen_ = true;
2523
2524   Type *t;
2525   bool r = this->constant_->const_value()->expr()->complex_constant_value(real,
2526                                                                           imag,
2527                                                                           &t);
2528
2529   this->seen_ = false;
2530
2531   if (r && ctype != NULL)
2532     {
2533       if (!Complex_expression::check_constant(real, imag, ctype,
2534                                               this->location()))
2535         return false;
2536       Complex_expression::constrain_complex(real, imag, ctype);
2537     }
2538   *ptype = ctype != NULL ? ctype : t;
2539   return r;
2540 }
2541
2542 // Return the type of the const reference.
2543
2544 Type*
2545 Const_expression::do_type()
2546 {
2547   if (this->type_ != NULL)
2548     return this->type_;
2549
2550   Named_constant* nc = this->constant_->const_value();
2551
2552   if (this->seen_ || nc->lowering())
2553     {
2554       this->report_error(_("constant refers to itself"));
2555       this->type_ = Type::make_error_type();
2556       return this->type_;
2557     }
2558
2559   this->seen_ = true;
2560
2561   Type* ret = nc->type();
2562
2563   if (ret != NULL)
2564     {
2565       this->seen_ = false;
2566       return ret;
2567     }
2568
2569   // During parsing, a named constant may have a NULL type, but we
2570   // must not return a NULL type here.
2571   ret = nc->expr()->type();
2572
2573   this->seen_ = false;
2574
2575   return ret;
2576 }
2577
2578 // Set the type of the const reference.
2579
2580 void
2581 Const_expression::do_determine_type(const Type_context* context)
2582 {
2583   Type* ctype = this->constant_->const_value()->type();
2584   Type* cetype = (ctype != NULL
2585                   ? ctype
2586                   : this->constant_->const_value()->expr()->type());
2587   if (ctype != NULL && !ctype->is_abstract())
2588     ;
2589   else if (context->type != NULL
2590            && (context->type->integer_type() != NULL
2591                || context->type->float_type() != NULL
2592                || context->type->complex_type() != NULL)
2593            && (cetype->integer_type() != NULL
2594                || cetype->float_type() != NULL
2595                || cetype->complex_type() != NULL))
2596     this->type_ = context->type;
2597   else if (context->type != NULL
2598            && context->type->is_string_type()
2599            && cetype->is_string_type())
2600     this->type_ = context->type;
2601   else if (context->type != NULL
2602            && context->type->is_boolean_type()
2603            && cetype->is_boolean_type())
2604     this->type_ = context->type;
2605   else if (!context->may_be_abstract)
2606     {
2607       if (cetype->is_abstract())
2608         cetype = cetype->make_non_abstract_type();
2609       this->type_ = cetype;
2610     }
2611 }
2612
2613 // Check types of a const reference.
2614
2615 void
2616 Const_expression::do_check_types(Gogo*)
2617 {
2618   if (this->type_ != NULL && this->type_->is_error_type())
2619     return;
2620
2621   Expression* init = this->constant_->const_value()->expr();
2622   Find_named_object find_named_object(this->constant_);
2623   Expression::traverse(&init, &find_named_object);
2624   if (find_named_object.found())
2625     {
2626       this->report_error(_("constant refers to itself"));
2627       this->type_ = Type::make_error_type();
2628       return;
2629     }
2630
2631   if (this->type_ == NULL || this->type_->is_abstract())
2632     return;
2633
2634   // Check for integer overflow.
2635   if (this->type_->integer_type() != NULL)
2636     {
2637       mpz_t ival;
2638       mpz_init(ival);
2639       Type* dummy;
2640       if (!this->integer_constant_value(true, ival, &dummy))
2641         {
2642           mpfr_t fval;
2643           mpfr_init(fval);
2644           Expression* cexpr = this->constant_->const_value()->expr();
2645           if (cexpr->float_constant_value(fval, &dummy))
2646             {
2647               if (!mpfr_integer_p(fval))
2648                 this->report_error(_("floating point constant "
2649                                      "truncated to integer"));
2650               else
2651                 {
2652                   mpfr_get_z(ival, fval, GMP_RNDN);
2653                   Integer_expression::check_constant(ival, this->type_,
2654                                                      this->location());
2655                 }
2656             }
2657           mpfr_clear(fval);
2658         }
2659       mpz_clear(ival);
2660     }
2661 }
2662
2663 // Return a tree for the const reference.
2664
2665 tree
2666 Const_expression::do_get_tree(Translate_context* context)
2667 {
2668   Gogo* gogo = context->gogo();
2669   tree type_tree;
2670   if (this->type_ == NULL)
2671     type_tree = NULL_TREE;
2672   else
2673     {
2674       type_tree = this->type_->get_tree(gogo);
2675       if (type_tree == error_mark_node)
2676         return error_mark_node;
2677     }
2678
2679   // If the type has been set for this expression, but the underlying
2680   // object is an abstract int or float, we try to get the abstract
2681   // value.  Otherwise we may lose something in the conversion.
2682   if (this->type_ != NULL
2683       && (this->constant_->const_value()->type() == NULL
2684           || this->constant_->const_value()->type()->is_abstract()))
2685     {
2686       Expression* expr = this->constant_->const_value()->expr();
2687       mpz_t ival;
2688       mpz_init(ival);
2689       Type* t;
2690       if (expr->integer_constant_value(true, ival, &t))
2691         {
2692           tree ret = Expression::integer_constant_tree(ival, type_tree);
2693           mpz_clear(ival);
2694           return ret;
2695         }
2696       mpz_clear(ival);
2697
2698       mpfr_t fval;
2699       mpfr_init(fval);
2700       if (expr->float_constant_value(fval, &t))
2701         {
2702           tree ret = Expression::float_constant_tree(fval, type_tree);
2703           mpfr_clear(fval);
2704           return ret;
2705         }
2706
2707       mpfr_t imag;
2708       mpfr_init(imag);
2709       if (expr->complex_constant_value(fval, imag, &t))
2710         {
2711           tree ret = Expression::complex_constant_tree(fval, imag, type_tree);
2712           mpfr_clear(fval);
2713           mpfr_clear(imag);
2714           return ret;
2715         }
2716       mpfr_clear(imag);
2717       mpfr_clear(fval);
2718     }
2719
2720   tree const_tree = this->constant_->get_tree(gogo, context->function());
2721   if (this->type_ == NULL
2722       || const_tree == error_mark_node
2723       || TREE_TYPE(const_tree) == error_mark_node)
2724     return const_tree;
2725
2726   tree ret;
2727   if (TYPE_MAIN_VARIANT(type_tree) == TYPE_MAIN_VARIANT(TREE_TYPE(const_tree)))
2728     ret = fold_convert(type_tree, const_tree);
2729   else if (TREE_CODE(type_tree) == INTEGER_TYPE)
2730     ret = fold(convert_to_integer(type_tree, const_tree));
2731   else if (TREE_CODE(type_tree) == REAL_TYPE)
2732     ret = fold(convert_to_real(type_tree, const_tree));
2733   else if (TREE_CODE(type_tree) == COMPLEX_TYPE)
2734     ret = fold(convert_to_complex(type_tree, const_tree));
2735   else
2736     gcc_unreachable();
2737   return ret;
2738 }
2739
2740 // Make a reference to a constant in an expression.
2741
2742 Expression*
2743 Expression::make_const_reference(Named_object* constant,
2744                                  source_location location)
2745 {
2746   return new Const_expression(constant, location);
2747 }
2748
2749 // Find a named object in an expression.
2750
2751 int
2752 Find_named_object::expression(Expression** pexpr)
2753 {
2754   switch ((*pexpr)->classification())
2755     {
2756     case Expression::EXPRESSION_CONST_REFERENCE:
2757       if (static_cast<Const_expression*>(*pexpr)->named_object() == this->no_)
2758         break;
2759       return TRAVERSE_CONTINUE;
2760     case Expression::EXPRESSION_VAR_REFERENCE:
2761       if ((*pexpr)->var_expression()->named_object() == this->no_)
2762         break;
2763       return TRAVERSE_CONTINUE;
2764     case Expression::EXPRESSION_FUNC_REFERENCE:
2765       if ((*pexpr)->func_expression()->named_object() == this->no_)
2766         break;
2767       return TRAVERSE_CONTINUE;
2768     default:
2769       return TRAVERSE_CONTINUE;
2770     }
2771   this->found_ = true;
2772   return TRAVERSE_EXIT;
2773 }
2774
2775 // The nil value.
2776
2777 class Nil_expression : public Expression
2778 {
2779  public:
2780   Nil_expression(source_location location)
2781     : Expression(EXPRESSION_NIL, location)
2782   { }
2783
2784   static Expression*
2785   do_import(Import*);
2786
2787  protected:
2788   bool
2789   do_is_constant() const
2790   { return true; }
2791
2792   Type*
2793   do_type()
2794   { return Type::make_nil_type(); }
2795
2796   void
2797   do_determine_type(const Type_context*)
2798   { }
2799
2800   Expression*
2801   do_copy()
2802   { return this; }
2803
2804   tree
2805   do_get_tree(Translate_context*)
2806   { return null_pointer_node; }
2807
2808   void
2809   do_export(Export* exp) const
2810   { exp->write_c_string("nil"); }
2811 };
2812
2813 // Import a nil expression.
2814
2815 Expression*
2816 Nil_expression::do_import(Import* imp)
2817 {
2818   imp->require_c_string("nil");
2819   return Expression::make_nil(imp->location());
2820 }
2821
2822 // Make a nil expression.
2823
2824 Expression*
2825 Expression::make_nil(source_location location)
2826 {
2827   return new Nil_expression(location);
2828 }
2829
2830 // The value of the predeclared constant iota.  This is little more
2831 // than a marker.  This will be lowered to an integer in
2832 // Const_expression::do_lower, which is where we know the value that
2833 // it should have.
2834
2835 class Iota_expression : public Parser_expression
2836 {
2837  public:
2838   Iota_expression(source_location location)
2839     : Parser_expression(EXPRESSION_IOTA, location)
2840   { }
2841
2842  protected:
2843   Expression*
2844   do_lower(Gogo*, Named_object*, int)
2845   { gcc_unreachable(); }
2846
2847   // There should only ever be one of these.
2848   Expression*
2849   do_copy()
2850   { gcc_unreachable(); }
2851 };
2852
2853 // Make an iota expression.  This is only called for one case: the
2854 // value of the predeclared constant iota.
2855
2856 Expression*
2857 Expression::make_iota()
2858 {
2859   static Iota_expression iota_expression(UNKNOWN_LOCATION);
2860   return &iota_expression;
2861 }
2862
2863 // A type conversion expression.
2864
2865 class Type_conversion_expression : public Expression
2866 {
2867  public:
2868   Type_conversion_expression(Type* type, Expression* expr,
2869                              source_location location)
2870     : Expression(EXPRESSION_CONVERSION, location),
2871       type_(type), expr_(expr), may_convert_function_types_(false)
2872   { }
2873
2874   // Return the type to which we are converting.
2875   Type*
2876   type() const
2877   { return this->type_; }
2878
2879   // Return the expression which we are converting.
2880   Expression*
2881   expr() const
2882   { return this->expr_; }
2883
2884   // Permit converting from one function type to another.  This is
2885   // used internally for method expressions.
2886   void
2887   set_may_convert_function_types()
2888   {
2889     this->may_convert_function_types_ = true;
2890   }
2891
2892   // Import a type conversion expression.
2893   static Expression*
2894   do_import(Import*);
2895
2896  protected:
2897   int
2898   do_traverse(Traverse* traverse);
2899
2900   Expression*
2901   do_lower(Gogo*, Named_object*, int);
2902
2903   bool
2904   do_is_constant() const
2905   { return this->expr_->is_constant(); }
2906
2907   bool
2908   do_integer_constant_value(bool, mpz_t, Type**) const;
2909
2910   bool
2911   do_float_constant_value(mpfr_t, Type**) const;
2912
2913   bool
2914   do_complex_constant_value(mpfr_t, mpfr_t, Type**) const;
2915
2916   bool
2917   do_string_constant_value(std::string*) const;
2918
2919   Type*
2920   do_type()
2921   { return this->type_; }
2922
2923   void
2924   do_determine_type(const Type_context*)
2925   {
2926     Type_context subcontext(this->type_, false);
2927     this->expr_->determine_type(&subcontext);
2928   }
2929
2930   void
2931   do_check_types(Gogo*);
2932
2933   Expression*
2934   do_copy()
2935   {
2936     return new Type_conversion_expression(this->type_, this->expr_->copy(),
2937                                           this->location());
2938   }
2939
2940   tree
2941   do_get_tree(Translate_context* context);
2942
2943   void
2944   do_export(Export*) const;
2945
2946  private:
2947   // The type to convert to.
2948   Type* type_;
2949   // The expression to convert.
2950   Expression* expr_;
2951   // True if this is permitted to convert function types.  This is
2952   // used internally for method expressions.
2953   bool may_convert_function_types_;
2954 };
2955
2956 // Traversal.
2957
2958 int
2959 Type_conversion_expression::do_traverse(Traverse* traverse)
2960 {
2961   if (Expression::traverse(&this->expr_, traverse) == TRAVERSE_EXIT
2962       || Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
2963     return TRAVERSE_EXIT;
2964   return TRAVERSE_CONTINUE;
2965 }
2966
2967 // Convert to a constant at lowering time.
2968
2969 Expression*
2970 Type_conversion_expression::do_lower(Gogo*, Named_object*, int)
2971 {
2972   Type* type = this->type_;
2973   Expression* val = this->expr_;
2974   source_location location = this->location();
2975
2976   if (type->integer_type() != NULL)
2977     {
2978       mpz_t ival;
2979       mpz_init(ival);
2980       Type* dummy;
2981       if (val->integer_constant_value(false, ival, &dummy))
2982         {
2983           if (!Integer_expression::check_constant(ival, type, location))
2984             mpz_set_ui(ival, 0);
2985           Expression* ret = Expression::make_integer(&ival, type, location);
2986           mpz_clear(ival);
2987           return ret;
2988         }
2989
2990       mpfr_t fval;
2991       mpfr_init(fval);
2992       if (val->float_constant_value(fval, &dummy))
2993         {
2994           if (!mpfr_integer_p(fval))
2995             {
2996               error_at(location,
2997                        "floating point constant truncated to integer");
2998               return Expression::make_error(location);
2999             }
3000           mpfr_get_z(ival, fval, GMP_RNDN);
3001           if (!Integer_expression::check_constant(ival, type, location))
3002             mpz_set_ui(ival, 0);
3003           Expression* ret = Expression::make_integer(&ival, type, location);
3004           mpfr_clear(fval);
3005           mpz_clear(ival);
3006           return ret;
3007         }
3008       mpfr_clear(fval);
3009       mpz_clear(ival);
3010     }
3011
3012   if (type->float_type() != NULL)
3013     {
3014       mpfr_t fval;
3015       mpfr_init(fval);
3016       Type* dummy;
3017       if (val->float_constant_value(fval, &dummy))
3018         {
3019           if (!Float_expression::check_constant(fval, type, location))
3020             mpfr_set_ui(fval, 0, GMP_RNDN);
3021           Float_expression::constrain_float(fval, type);
3022           Expression *ret = Expression::make_float(&fval, type, location);
3023           mpfr_clear(fval);
3024           return ret;
3025         }
3026       mpfr_clear(fval);
3027     }
3028
3029   if (type->complex_type() != NULL)
3030     {
3031       mpfr_t real;
3032       mpfr_t imag;
3033       mpfr_init(real);
3034       mpfr_init(imag);
3035       Type* dummy;
3036       if (val->complex_constant_value(real, imag, &dummy))
3037         {
3038           if (!Complex_expression::check_constant(real, imag, type, location))
3039             {
3040               mpfr_set_ui(real, 0, GMP_RNDN);
3041               mpfr_set_ui(imag, 0, GMP_RNDN);
3042             }
3043           Complex_expression::constrain_complex(real, imag, type);
3044           Expression* ret = Expression::make_complex(&real, &imag, type,
3045                                                      location);
3046           mpfr_clear(real);
3047           mpfr_clear(imag);
3048           return ret;
3049         }
3050       mpfr_clear(real);
3051       mpfr_clear(imag);
3052     }
3053
3054   if (type->is_open_array_type() && type->named_type() == NULL)
3055     {
3056       Type* element_type = type->array_type()->element_type()->forwarded();
3057       bool is_byte = element_type == Type::lookup_integer_type("uint8");
3058       bool is_int = element_type == Type::lookup_integer_type("int");
3059       if (is_byte || is_int)
3060         {
3061           std::string s;
3062           if (val->string_constant_value(&s))
3063             {
3064               Expression_list* vals = new Expression_list();
3065               if (is_byte)
3066                 {
3067                   for (std::string::const_iterator p = s.begin();
3068                        p != s.end();
3069                        p++)
3070                     {
3071                       mpz_t val;
3072                       mpz_init_set_ui(val, static_cast<unsigned char>(*p));
3073                       Expression* v = Expression::make_integer(&val,
3074                                                                element_type,
3075                                                                location);
3076                       vals->push_back(v);
3077                       mpz_clear(val);
3078                     }
3079                 }
3080               else
3081                 {
3082                   const char *p = s.data();
3083                   const char *pend = s.data() + s.length();
3084                   while (p < pend)
3085                     {
3086                       unsigned int c;
3087                       int adv = Lex::fetch_char(p, &c);
3088                       if (adv == 0)
3089                         {
3090                           warning_at(this->location(), 0,
3091                                      "invalid UTF-8 encoding");
3092                           adv = 1;
3093                         }
3094                       p += adv;
3095                       mpz_t val;
3096                       mpz_init_set_ui(val, c);
3097                       Expression* v = Expression::make_integer(&val,
3098                                                                element_type,
3099                                                                location);
3100                       vals->push_back(v);
3101                       mpz_clear(val);
3102                     }
3103                 }
3104
3105               return Expression::make_slice_composite_literal(type, vals,
3106                                                               location);
3107             }
3108         }
3109     }
3110
3111   return this;
3112 }
3113
3114 // Return the constant integer value if there is one.
3115
3116 bool
3117 Type_conversion_expression::do_integer_constant_value(bool iota_is_constant,
3118                                                       mpz_t val,
3119                                                       Type** ptype) const
3120 {
3121   if (this->type_->integer_type() == NULL)
3122     return false;
3123
3124   mpz_t ival;
3125   mpz_init(ival);
3126   Type* dummy;
3127   if (this->expr_->integer_constant_value(iota_is_constant, ival, &dummy))
3128     {
3129       if (!Integer_expression::check_constant(ival, this->type_,
3130                                               this->location()))
3131         {
3132           mpz_clear(ival);
3133           return false;
3134         }
3135       mpz_set(val, ival);
3136       mpz_clear(ival);
3137       *ptype = this->type_;
3138       return true;
3139     }
3140   mpz_clear(ival);
3141
3142   mpfr_t fval;
3143   mpfr_init(fval);
3144   if (this->expr_->float_constant_value(fval, &dummy))
3145     {
3146       mpfr_get_z(val, fval, GMP_RNDN);
3147       mpfr_clear(fval);
3148       if (!Integer_expression::check_constant(val, this->type_,
3149                                               this->location()))
3150         return false;
3151       *ptype = this->type_;
3152       return true;
3153     }
3154   mpfr_clear(fval);
3155
3156   return false;
3157 }
3158
3159 // Return the constant floating point value if there is one.
3160
3161 bool
3162 Type_conversion_expression::do_float_constant_value(mpfr_t val,
3163                                                     Type** ptype) const
3164 {
3165   if (this->type_->float_type() == NULL)
3166     return false;
3167
3168   mpfr_t fval;
3169   mpfr_init(fval);
3170   Type* dummy;
3171   if (this->expr_->float_constant_value(fval, &dummy))
3172     {
3173       if (!Float_expression::check_constant(fval, this->type_,
3174                                             this->location()))
3175         {
3176           mpfr_clear(fval);
3177           return false;
3178         }
3179       mpfr_set(val, fval, GMP_RNDN);
3180       mpfr_clear(fval);
3181       Float_expression::constrain_float(val, this->type_);
3182       *ptype = this->type_;
3183       return true;
3184     }
3185   mpfr_clear(fval);
3186
3187   return false;
3188 }
3189
3190 // Return the constant complex value if there is one.
3191
3192 bool
3193 Type_conversion_expression::do_complex_constant_value(mpfr_t real,
3194                                                       mpfr_t imag,
3195                                                       Type **ptype) const
3196 {
3197   if (this->type_->complex_type() == NULL)
3198     return false;
3199
3200   mpfr_t rval;
3201   mpfr_t ival;
3202   mpfr_init(rval);
3203   mpfr_init(ival);
3204   Type* dummy;
3205   if (this->expr_->complex_constant_value(rval, ival, &dummy))
3206     {
3207       if (!Complex_expression::check_constant(rval, ival, this->type_,
3208                                               this->location()))
3209         {
3210           mpfr_clear(rval);
3211           mpfr_clear(ival);
3212           return false;
3213         }
3214       mpfr_set(real, rval, GMP_RNDN);
3215       mpfr_set(imag, ival, GMP_RNDN);
3216       mpfr_clear(rval);
3217       mpfr_clear(ival);
3218       Complex_expression::constrain_complex(real, imag, this->type_);
3219       *ptype = this->type_;
3220       return true;
3221     }
3222   mpfr_clear(rval);
3223   mpfr_clear(ival);
3224
3225   return false;
3226 }
3227
3228 // Return the constant string value if there is one.
3229
3230 bool
3231 Type_conversion_expression::do_string_constant_value(std::string* val) const
3232 {
3233   if (this->type_->is_string_type()
3234       && this->expr_->type()->integer_type() != NULL)
3235     {
3236       mpz_t ival;
3237       mpz_init(ival);
3238       Type* dummy;
3239       if (this->expr_->integer_constant_value(false, ival, &dummy))
3240         {
3241           unsigned long ulval = mpz_get_ui(ival);
3242           if (mpz_cmp_ui(ival, ulval) == 0)
3243             {
3244               Lex::append_char(ulval, true, val, this->location());
3245               mpz_clear(ival);
3246               return true;
3247             }
3248         }
3249       mpz_clear(ival);
3250     }
3251
3252   // FIXME: Could handle conversion from const []int here.
3253
3254   return false;
3255 }
3256
3257 // Check that types are convertible.
3258
3259 void
3260 Type_conversion_expression::do_check_types(Gogo*)
3261 {
3262   Type* type = this->type_;
3263   Type* expr_type = this->expr_->type();
3264   std::string reason;
3265
3266   if (type->is_error_type()
3267       || type->is_undefined()
3268       || expr_type->is_error_type()
3269       || expr_type->is_undefined())
3270     {
3271       // Make sure we emit an error for an undefined type.
3272       type->base();
3273       expr_type->base();
3274       this->set_is_error();
3275       return;
3276     }
3277
3278   if (this->may_convert_function_types_
3279       && type->function_type() != NULL
3280       && expr_type->function_type() != NULL)
3281     return;
3282
3283   if (Type::are_convertible(type, expr_type, &reason))
3284     return;
3285
3286   error_at(this->location(), "%s", reason.c_str());
3287   this->set_is_error();
3288 }
3289
3290 // Get a tree for a type conversion.
3291
3292 tree
3293 Type_conversion_expression::do_get_tree(Translate_context* context)
3294 {
3295   Gogo* gogo = context->gogo();
3296   tree type_tree = this->type_->get_tree(gogo);
3297   tree expr_tree = this->expr_->get_tree(context);
3298
3299   if (type_tree == error_mark_node
3300       || expr_tree == error_mark_node
3301       || TREE_TYPE(expr_tree) == error_mark_node)
3302     return error_mark_node;
3303
3304   if (TYPE_MAIN_VARIANT(type_tree) == TYPE_MAIN_VARIANT(TREE_TYPE(expr_tree)))
3305     return fold_convert(type_tree, expr_tree);
3306
3307   Type* type = this->type_;
3308   Type* expr_type = this->expr_->type();
3309   tree ret;
3310   if (type->interface_type() != NULL || expr_type->interface_type() != NULL)
3311     ret = Expression::convert_for_assignment(context, type, expr_type,
3312                                              expr_tree, this->location());
3313   else if (type->integer_type() != NULL)
3314     {
3315       if (expr_type->integer_type() != NULL
3316           || expr_type->float_type() != NULL
3317           || expr_type->is_unsafe_pointer_type())
3318         ret = fold(convert_to_integer(type_tree, expr_tree));
3319       else
3320         gcc_unreachable();
3321     }
3322   else if (type->float_type() != NULL)
3323     {
3324       if (expr_type->integer_type() != NULL
3325           || expr_type->float_type() != NULL)
3326         ret = fold(convert_to_real(type_tree, expr_tree));
3327       else
3328         gcc_unreachable();
3329     }
3330   else if (type->complex_type() != NULL)
3331     {
3332       if (expr_type->complex_type() != NULL)
3333         ret = fold(convert_to_complex(type_tree, expr_tree));
3334       else
3335         gcc_unreachable();
3336     }
3337   else if (type->is_string_type()
3338            && expr_type->integer_type() != NULL)
3339     {
3340       expr_tree = fold_convert(integer_type_node, expr_tree);
3341       if (host_integerp(expr_tree, 0))
3342         {
3343           HOST_WIDE_INT intval = tree_low_cst(expr_tree, 0);
3344           std::string s;
3345           Lex::append_char(intval, true, &s, this->location());
3346           Expression* se = Expression::make_string(s, this->location());
3347           return se->get_tree(context);
3348         }
3349
3350       static tree int_to_string_fndecl;
3351       ret = Gogo::call_builtin(&int_to_string_fndecl,
3352                                this->location(),
3353                                "__go_int_to_string",
3354                                1,
3355                                type_tree,
3356                                integer_type_node,
3357                                fold_convert(integer_type_node, expr_tree));
3358     }
3359   else if (type->is_string_type()
3360            && (expr_type->array_type() != NULL
3361                || (expr_type->points_to() != NULL
3362                    && expr_type->points_to()->array_type() != NULL)))
3363     {
3364       Type* t = expr_type;
3365       if (t->points_to() != NULL)
3366         {
3367           t = t->points_to();
3368           expr_tree = build_fold_indirect_ref(expr_tree);
3369         }
3370       if (!DECL_P(expr_tree))
3371         expr_tree = save_expr(expr_tree);
3372       Array_type* a = t->array_type();
3373       Type* e = a->element_type()->forwarded();
3374       gcc_assert(e->integer_type() != NULL);
3375       tree valptr = fold_convert(const_ptr_type_node,
3376                                  a->value_pointer_tree(gogo, expr_tree));
3377       tree len = a->length_tree(gogo, expr_tree);
3378       len = fold_convert_loc(this->location(), size_type_node, len);
3379       if (e->integer_type()->is_unsigned()
3380           && e->integer_type()->bits() == 8)
3381         {
3382           static tree byte_array_to_string_fndecl;
3383           ret = Gogo::call_builtin(&byte_array_to_string_fndecl,
3384                                    this->location(),
3385                                    "__go_byte_array_to_string",
3386                                    2,
3387                                    type_tree,
3388                                    const_ptr_type_node,
3389                                    valptr,
3390                                    size_type_node,
3391                                    len);
3392         }
3393       else
3394         {
3395           gcc_assert(e == Type::lookup_integer_type("int"));
3396           static tree int_array_to_string_fndecl;
3397           ret = Gogo::call_builtin(&int_array_to_string_fndecl,
3398                                    this->location(),
3399                                    "__go_int_array_to_string",
3400                                    2,
3401                                    type_tree,
3402                                    const_ptr_type_node,
3403                                    valptr,
3404                                    size_type_node,
3405                                    len);
3406         }
3407     }
3408   else if (type->is_open_array_type() && expr_type->is_string_type())
3409     {
3410       Type* e = type->array_type()->element_type()->forwarded();
3411       gcc_assert(e->integer_type() != NULL);
3412       if (e->integer_type()->is_unsigned()
3413           && e->integer_type()->bits() == 8)
3414         {
3415           static tree string_to_byte_array_fndecl;
3416           ret = Gogo::call_builtin(&string_to_byte_array_fndecl,
3417                                    this->location(),
3418                                    "__go_string_to_byte_array",
3419                                    1,
3420                                    type_tree,
3421                                    TREE_TYPE(expr_tree),
3422                                    expr_tree);
3423         }
3424       else
3425         {
3426           gcc_assert(e == Type::lookup_integer_type("int"));
3427           static tree string_to_int_array_fndecl;
3428           ret = Gogo::call_builtin(&string_to_int_array_fndecl,
3429                                    this->location(),
3430                                    "__go_string_to_int_array",
3431                                    1,
3432                                    type_tree,
3433                                    TREE_TYPE(expr_tree),
3434                                    expr_tree);
3435         }
3436     }
3437   else if ((type->is_unsafe_pointer_type()
3438             && expr_type->points_to() != NULL)
3439            || (expr_type->is_unsafe_pointer_type()
3440                && type->points_to() != NULL))
3441     ret = fold_convert(type_tree, expr_tree);
3442   else if (type->is_unsafe_pointer_type()
3443            && expr_type->integer_type() != NULL)
3444     ret = convert_to_pointer(type_tree, expr_tree);
3445   else if (this->may_convert_function_types_
3446            && type->function_type() != NULL
3447            && expr_type->function_type() != NULL)
3448     ret = fold_convert_loc(this->location(), type_tree, expr_tree);
3449   else
3450     ret = Expression::convert_for_assignment(context, type, expr_type,
3451                                              expr_tree, this->location());
3452
3453   return ret;
3454 }
3455
3456 // Output a type conversion in a constant expression.
3457
3458 void
3459 Type_conversion_expression::do_export(Export* exp) const
3460 {
3461   exp->write_c_string("convert(");
3462   exp->write_type(this->type_);
3463   exp->write_c_string(", ");
3464   this->expr_->export_expression(exp);
3465   exp->write_c_string(")");
3466 }
3467
3468 // Import a type conversion or a struct construction.
3469
3470 Expression*
3471 Type_conversion_expression::do_import(Import* imp)
3472 {
3473   imp->require_c_string("convert(");
3474   Type* type = imp->read_type();
3475   imp->require_c_string(", ");
3476   Expression* val = Expression::import_expression(imp);
3477   imp->require_c_string(")");
3478   return Expression::make_cast(type, val, imp->location());
3479 }
3480
3481 // Make a type cast expression.
3482
3483 Expression*
3484 Expression::make_cast(Type* type, Expression* val, source_location location)
3485 {
3486   if (type->is_error_type() || val->is_error_expression())
3487     return Expression::make_error(location);
3488   return new Type_conversion_expression(type, val, location);
3489 }
3490
3491 // Unary expressions.
3492
3493 class Unary_expression : public Expression
3494 {
3495  public:
3496   Unary_expression(Operator op, Expression* expr, source_location location)
3497     : Expression(EXPRESSION_UNARY, location),
3498       op_(op), escapes_(true), expr_(expr)
3499   { }
3500
3501   // Return the operator.
3502   Operator
3503   op() const
3504   { return this->op_; }
3505
3506   // Return the operand.
3507   Expression*
3508   operand() const
3509   { return this->expr_; }
3510
3511   // Record that an address expression does not escape.
3512   void
3513   set_does_not_escape()
3514   {
3515     gcc_assert(this->op_ == OPERATOR_AND);
3516     this->escapes_ = false;
3517   }
3518
3519   // Apply unary opcode OP to UVAL, setting VAL.  Return true if this
3520   // could be done, false if not.
3521   static bool
3522   eval_integer(Operator op, Type* utype, mpz_t uval, mpz_t val,
3523                source_location);
3524
3525   // Apply unary opcode OP to UVAL, setting VAL.  Return true if this
3526   // could be done, false if not.
3527   static bool
3528   eval_float(Operator op, mpfr_t uval, mpfr_t val);
3529
3530   // Apply unary opcode OP to UREAL/UIMAG, setting REAL/IMAG.  Return
3531   // true if this could be done, false if not.
3532   static bool
3533   eval_complex(Operator op, mpfr_t ureal, mpfr_t uimag, mpfr_t real,
3534                mpfr_t imag);
3535
3536   static Expression*
3537   do_import(Import*);
3538
3539  protected:
3540   int
3541   do_traverse(Traverse* traverse)
3542   { return Expression::traverse(&this->expr_, traverse); }
3543
3544   Expression*
3545   do_lower(Gogo*, Named_object*, int);
3546
3547   bool
3548   do_is_constant() const;
3549
3550   bool
3551   do_integer_constant_value(bool, mpz_t, Type**) const;
3552
3553   bool
3554   do_float_constant_value(mpfr_t, Type**) const;
3555
3556   bool
3557   do_complex_constant_value(mpfr_t, mpfr_t, Type**) const;
3558
3559   Type*
3560   do_type();
3561
3562   void
3563   do_determine_type(const Type_context*);
3564
3565   void
3566   do_check_types(Gogo*);
3567
3568   Expression*
3569   do_copy()
3570   {
3571     return Expression::make_unary(this->op_, this->expr_->copy(),
3572                                   this->location());
3573   }
3574
3575   bool
3576   do_is_addressable() const
3577   { return this->op_ == OPERATOR_MULT; }
3578
3579   tree
3580   do_get_tree(Translate_context*);
3581
3582   void
3583   do_export(Export*) const;
3584
3585  private:
3586   // The unary operator to apply.
3587   Operator op_;
3588   // Normally true.  False if this is an address expression which does
3589   // not escape the current function.
3590   bool escapes_;
3591   // The operand.
3592   Expression* expr_;
3593 };
3594
3595 // If we are taking the address of a composite literal, and the
3596 // contents are not constant, then we want to make a heap composite
3597 // instead.
3598
3599 Expression*
3600 Unary_expression::do_lower(Gogo*, Named_object*, int)
3601 {
3602   source_location loc = this->location();
3603   Operator op = this->op_;
3604   Expression* expr = this->expr_;
3605
3606   if (op == OPERATOR_MULT && expr->is_type_expression())
3607     return Expression::make_type(Type::make_pointer_type(expr->type()), loc);
3608
3609   // *&x simplifies to x.  *(*T)(unsafe.Pointer)(&x) does not require
3610   // moving x to the heap.  FIXME: Is it worth doing a real escape
3611   // analysis here?  This case is found in math/unsafe.go and is
3612   // therefore worth special casing.
3613   if (op == OPERATOR_MULT)
3614     {
3615       Expression* e = expr;
3616       while (e->classification() == EXPRESSION_CONVERSION)
3617         {
3618           Type_conversion_expression* te
3619             = static_cast<Type_conversion_expression*>(e);
3620           e = te->expr();
3621         }
3622
3623       if (e->classification() == EXPRESSION_UNARY)
3624         {
3625           Unary_expression* ue = static_cast<Unary_expression*>(e);
3626           if (ue->op_ == OPERATOR_AND)
3627             {
3628               if (e == expr)
3629                 {
3630                   // *&x == x.
3631                   return ue->expr_;
3632                 }
3633               ue->set_does_not_escape();
3634             }
3635         }
3636     }
3637
3638   if (op == OPERATOR_PLUS || op == OPERATOR_MINUS
3639       || op == OPERATOR_NOT || op == OPERATOR_XOR)
3640     {
3641       Expression* ret = NULL;
3642
3643       mpz_t eval;
3644       mpz_init(eval);
3645       Type* etype;
3646       if (expr->integer_constant_value(false, eval, &etype))
3647         {
3648           mpz_t val;
3649           mpz_init(val);
3650           if (Unary_expression::eval_integer(op, etype, eval, val, loc))
3651             ret = Expression::make_integer(&val, etype, loc);
3652           mpz_clear(val);
3653         }
3654       mpz_clear(eval);
3655       if (ret != NULL)
3656         return ret;
3657
3658       if (op == OPERATOR_PLUS || op == OPERATOR_MINUS)
3659         {
3660           mpfr_t fval;
3661           mpfr_init(fval);
3662           Type* ftype;
3663           if (expr->float_constant_value(fval, &ftype))
3664             {
3665               mpfr_t val;
3666               mpfr_init(val);
3667               if (Unary_expression::eval_float(op, fval, val))
3668                 ret = Expression::make_float(&val, ftype, loc);
3669               mpfr_clear(val);
3670             }
3671           if (ret != NULL)
3672             {
3673               mpfr_clear(fval);
3674               return ret;
3675             }
3676
3677           mpfr_t ival;
3678           mpfr_init(ival);
3679           if (expr->complex_constant_value(fval, ival, &ftype))
3680             {
3681               mpfr_t real;
3682               mpfr_t imag;
3683               mpfr_init(real);
3684               mpfr_init(imag);
3685               if (Unary_expression::eval_complex(op, fval, ival, real, imag))
3686                 ret = Expression::make_complex(&real, &imag, ftype, loc);
3687               mpfr_clear(real);
3688               mpfr_clear(imag);
3689             }
3690           mpfr_clear(ival);
3691           mpfr_clear(fval);
3692           if (ret != NULL)
3693             return ret;
3694         }
3695     }
3696
3697   return this;
3698 }
3699
3700 // Return whether a unary expression is a constant.
3701
3702 bool
3703 Unary_expression::do_is_constant() const
3704 {
3705   if (this->op_ == OPERATOR_MULT)
3706     {
3707       // Indirecting through a pointer is only constant if the object
3708       // to which the expression points is constant, but we currently
3709       // have no way to determine that.
3710       return false;
3711     }
3712   else if (this->op_ == OPERATOR_AND)
3713     {
3714       // Taking the address of a variable is constant if it is a
3715       // global variable, not constant otherwise.  In other cases
3716       // taking the address is probably not a constant.
3717       Var_expression* ve = this->expr_->var_expression();
3718       if (ve != NULL)
3719         {
3720           Named_object* no = ve->named_object();
3721           return no->is_variable() && no->var_value()->is_global();
3722         }
3723       return false;
3724     }
3725   else
3726     return this->expr_->is_constant();
3727 }
3728
3729 // Apply unary opcode OP to UVAL, setting VAL.  UTYPE is the type of
3730 // UVAL, if known; it may be NULL.  Return true if this could be done,
3731 // false if not.
3732
3733 bool
3734 Unary_expression::eval_integer(Operator op, Type* utype, mpz_t uval, mpz_t val,
3735                                source_location location)
3736 {
3737   switch (op)
3738     {
3739     case OPERATOR_PLUS:
3740       mpz_set(val, uval);
3741       return true;
3742     case OPERATOR_MINUS:
3743       mpz_neg(val, uval);
3744       return Integer_expression::check_constant(val, utype, location);
3745     case OPERATOR_NOT:
3746       mpz_set_ui(val, mpz_cmp_si(uval, 0) == 0 ? 1 : 0);
3747       return true;
3748     case OPERATOR_XOR:
3749       if (utype == NULL
3750           || utype->integer_type() == NULL
3751           || utype->integer_type()->is_abstract())
3752         mpz_com(val, uval);
3753       else
3754         {
3755           // The number of HOST_WIDE_INTs that it takes to represent
3756           // UVAL.
3757           size_t count = ((mpz_sizeinbase(uval, 2)
3758                            + HOST_BITS_PER_WIDE_INT
3759                            - 1)
3760                           / HOST_BITS_PER_WIDE_INT);
3761
3762           unsigned HOST_WIDE_INT* phwi = new unsigned HOST_WIDE_INT[count];
3763           memset(phwi, 0, count * sizeof(HOST_WIDE_INT));
3764
3765           size_t ecount;
3766           mpz_export(phwi, &ecount, -1, sizeof(HOST_WIDE_INT), 0, 0, uval);
3767           gcc_assert(ecount <= count);
3768
3769           // Trim down to the number of words required by the type.
3770           size_t obits = utype->integer_type()->bits();
3771           if (!utype->integer_type()->is_unsigned())
3772             ++obits;
3773           size_t ocount = ((obits + HOST_BITS_PER_WIDE_INT - 1)
3774                            / HOST_BITS_PER_WIDE_INT);
3775           gcc_assert(ocount <= ocount);
3776
3777           for (size_t i = 0; i < ocount; ++i)
3778             phwi[i] = ~phwi[i];
3779
3780           size_t clearbits = ocount * HOST_BITS_PER_WIDE_INT - obits;
3781           if (clearbits != 0)
3782             phwi[ocount - 1] &= (((unsigned HOST_WIDE_INT) (HOST_WIDE_INT) -1)
3783                                  >> clearbits);
3784
3785           mpz_import(val, ocount, -1, sizeof(HOST_WIDE_INT), 0, 0, phwi);
3786
3787           delete[] phwi;
3788         }
3789       return Integer_expression::check_constant(val, utype, location);
3790     case OPERATOR_AND:
3791     case OPERATOR_MULT:
3792       return false;
3793     default:
3794       gcc_unreachable();
3795     }
3796 }
3797
3798 // Apply unary opcode OP to UVAL, setting VAL.  Return true if this
3799 // could be done, false if not.
3800
3801 bool
3802 Unary_expression::eval_float(Operator op, mpfr_t uval, mpfr_t val)
3803 {
3804   switch (op)
3805     {
3806     case OPERATOR_PLUS:
3807       mpfr_set(val, uval, GMP_RNDN);
3808       return true;
3809     case OPERATOR_MINUS:
3810       mpfr_neg(val, uval, GMP_RNDN);
3811       return true;
3812     case OPERATOR_NOT:
3813     case OPERATOR_XOR:
3814     case OPERATOR_AND:
3815     case OPERATOR_MULT:
3816       return false;
3817     default:
3818       gcc_unreachable();
3819     }
3820 }
3821
3822 // Apply unary opcode OP to RVAL/IVAL, setting REAL/IMAG.  Return true
3823 // if this could be done, false if not.
3824
3825 bool
3826 Unary_expression::eval_complex(Operator op, mpfr_t rval, mpfr_t ival,
3827                                mpfr_t real, mpfr_t imag)
3828 {
3829   switch (op)
3830     {
3831     case OPERATOR_PLUS:
3832       mpfr_set(real, rval, GMP_RNDN);
3833       mpfr_set(imag, ival, GMP_RNDN);
3834       return true;
3835     case OPERATOR_MINUS:
3836       mpfr_neg(real, rval, GMP_RNDN);
3837       mpfr_neg(imag, ival, GMP_RNDN);
3838       return true;
3839     case OPERATOR_NOT:
3840     case OPERATOR_XOR:
3841     case OPERATOR_AND:
3842     case OPERATOR_MULT:
3843       return false;
3844     default:
3845       gcc_unreachable();
3846     }
3847 }
3848
3849 // Return the integral constant value of a unary expression, if it has one.
3850
3851 bool
3852 Unary_expression::do_integer_constant_value(bool iota_is_constant, mpz_t val,
3853                                             Type** ptype) const
3854 {
3855   mpz_t uval;
3856   mpz_init(uval);
3857   bool ret;
3858   if (!this->expr_->integer_constant_value(iota_is_constant, uval, ptype))
3859     ret = false;
3860   else
3861     ret = Unary_expression::eval_integer(this->op_, *ptype, uval, val,
3862                                          this->location());
3863   mpz_clear(uval);
3864   return ret;
3865 }
3866
3867 // Return the floating point constant value of a unary expression, if
3868 // it has one.
3869
3870 bool
3871 Unary_expression::do_float_constant_value(mpfr_t val, Type** ptype) const
3872 {
3873   mpfr_t uval;
3874   mpfr_init(uval);
3875   bool ret;
3876   if (!this->expr_->float_constant_value(uval, ptype))
3877     ret = false;
3878   else
3879     ret = Unary_expression::eval_float(this->op_, uval, val);
3880   mpfr_clear(uval);
3881   return ret;
3882 }
3883
3884 // Return the complex constant value of a unary expression, if it has
3885 // one.
3886
3887 bool
3888 Unary_expression::do_complex_constant_value(mpfr_t real, mpfr_t imag,
3889                                             Type** ptype) const
3890 {
3891   mpfr_t rval;
3892   mpfr_t ival;
3893   mpfr_init(rval);
3894   mpfr_init(ival);
3895   bool ret;
3896   if (!this->expr_->complex_constant_value(rval, ival, ptype))
3897     ret = false;
3898   else
3899     ret = Unary_expression::eval_complex(this->op_, rval, ival, real, imag);
3900   mpfr_clear(rval);
3901   mpfr_clear(ival);
3902   return ret;
3903 }
3904
3905 // Return the type of a unary expression.
3906
3907 Type*
3908 Unary_expression::do_type()
3909 {
3910   switch (this->op_)
3911     {
3912     case OPERATOR_PLUS:
3913     case OPERATOR_MINUS:
3914     case OPERATOR_NOT:
3915     case OPERATOR_XOR:
3916       return this->expr_->type();
3917
3918     case OPERATOR_AND:
3919       return Type::make_pointer_type(this->expr_->type());
3920
3921     case OPERATOR_MULT:
3922       {
3923         Type* subtype = this->expr_->type();
3924         Type* points_to = subtype->points_to();
3925         if (points_to == NULL)
3926           return Type::make_error_type();
3927         return points_to;
3928       }
3929
3930     default:
3931       gcc_unreachable();
3932     }
3933 }
3934
3935 // Determine abstract types for a unary expression.
3936
3937 void
3938 Unary_expression::do_determine_type(const Type_context* context)
3939 {
3940   switch (this->op_)
3941     {
3942     case OPERATOR_PLUS:
3943     case OPERATOR_MINUS:
3944     case OPERATOR_NOT:
3945     case OPERATOR_XOR:
3946       this->expr_->determine_type(context);
3947       break;
3948
3949     case OPERATOR_AND:
3950       // Taking the address of something.
3951       {
3952         Type* subtype = (context->type == NULL
3953                          ? NULL
3954                          : context->type->points_to());
3955         Type_context subcontext(subtype, false);
3956         this->expr_->determine_type(&subcontext);
3957       }
3958       break;
3959
3960     case OPERATOR_MULT:
3961       // Indirecting through a pointer.
3962       {
3963         Type* subtype = (context->type == NULL
3964                          ? NULL
3965                          : Type::make_pointer_type(context->type));
3966         Type_context subcontext(subtype, false);
3967         this->expr_->determine_type(&subcontext);
3968       }
3969       break;
3970
3971     default:
3972       gcc_unreachable();
3973     }
3974 }
3975
3976 // Check types for a unary expression.
3977
3978 void
3979 Unary_expression::do_check_types(Gogo*)
3980 {
3981   Type* type = this->expr_->type();
3982   if (type->is_error_type())
3983     {
3984       this->set_is_error();
3985       return;
3986     }
3987
3988   switch (this->op_)
3989     {
3990     case OPERATOR_PLUS:
3991     case OPERATOR_MINUS:
3992       if (type->integer_type() == NULL
3993           && type->float_type() == NULL
3994           && type->complex_type() == NULL)
3995         this->report_error(_("expected numeric type"));
3996       break;
3997
3998     case OPERATOR_NOT:
3999     case OPERATOR_XOR:
4000       if (type->integer_type() == NULL
4001           && !type->is_boolean_type())
4002         this->report_error(_("expected integer or boolean type"));
4003       break;
4004
4005     case OPERATOR_AND:
4006       if (!this->expr_->is_addressable())
4007         this->report_error(_("invalid operand for unary %<&%>"));
4008       else
4009         this->expr_->address_taken(this->escapes_);
4010       break;
4011
4012     case OPERATOR_MULT:
4013       // Indirecting through a pointer.
4014       if (type->points_to() == NULL)
4015         this->report_error(_("expected pointer"));
4016       break;
4017
4018     default:
4019       gcc_unreachable();
4020     }
4021 }
4022
4023 // Get a tree for a unary expression.
4024
4025 tree
4026 Unary_expression::do_get_tree(Translate_context* context)
4027 {
4028   tree expr = this->expr_->get_tree(context);
4029   if (expr == error_mark_node)
4030     return error_mark_node;
4031
4032   source_location loc = this->location();
4033   switch (this->op_)
4034     {
4035     case OPERATOR_PLUS:
4036       return expr;
4037
4038     case OPERATOR_MINUS:
4039       {
4040         tree type = TREE_TYPE(expr);
4041         tree compute_type = excess_precision_type(type);
4042         if (compute_type != NULL_TREE)
4043           expr = ::convert(compute_type, expr);
4044         tree ret = fold_build1_loc(loc, NEGATE_EXPR,
4045                                    (compute_type != NULL_TREE
4046                                     ? compute_type
4047                                     : type),
4048                                    expr);
4049         if (compute_type != NULL_TREE)
4050           ret = ::convert(type, ret);
4051         return ret;
4052       }
4053
4054     case OPERATOR_NOT:
4055       if (TREE_CODE(TREE_TYPE(expr)) == BOOLEAN_TYPE)
4056         return fold_build1_loc(loc, TRUTH_NOT_EXPR, TREE_TYPE(expr), expr);
4057       else
4058         return fold_build2_loc(loc, NE_EXPR, boolean_type_node, expr,
4059                                build_int_cst(TREE_TYPE(expr), 0));
4060
4061     case OPERATOR_XOR:
4062       return fold_build1_loc(loc, BIT_NOT_EXPR, TREE_TYPE(expr), expr);
4063
4064     case OPERATOR_AND:
4065       // We should not see a non-constant constructor here; cases
4066       // where we would see one should have been moved onto the heap
4067       // at parse time.  Taking the address of a nonconstant
4068       // constructor will not do what the programmer expects.
4069       gcc_assert(TREE_CODE(expr) != CONSTRUCTOR || TREE_CONSTANT(expr));
4070       gcc_assert(TREE_CODE(expr) != ADDR_EXPR);
4071
4072       // Build a decl for a constant constructor.
4073       if (TREE_CODE(expr) == CONSTRUCTOR && TREE_CONSTANT(expr))
4074         {
4075           tree decl = build_decl(this->location(), VAR_DECL,
4076                                  create_tmp_var_name("C"), TREE_TYPE(expr));
4077           DECL_EXTERNAL(decl) = 0;
4078           TREE_PUBLIC(decl) = 0;
4079           TREE_READONLY(decl) = 1;
4080           TREE_CONSTANT(decl) = 1;
4081           TREE_STATIC(decl) = 1;
4082           TREE_ADDRESSABLE(decl) = 1;
4083           DECL_ARTIFICIAL(decl) = 1;
4084           DECL_INITIAL(decl) = expr;
4085           rest_of_decl_compilation(decl, 1, 0);
4086           expr = decl;
4087         }
4088
4089       return build_fold_addr_expr_loc(loc, expr);
4090
4091     case OPERATOR_MULT:
4092       {
4093         gcc_assert(POINTER_TYPE_P(TREE_TYPE(expr)));
4094
4095         // If we are dereferencing the pointer to a large struct, we
4096         // need to check for nil.  We don't bother to check for small
4097         // structs because we expect the system to crash on a nil
4098         // pointer dereference.
4099         HOST_WIDE_INT s = int_size_in_bytes(TREE_TYPE(TREE_TYPE(expr)));
4100         if (s == -1 || s >= 4096)
4101           {
4102             if (!DECL_P(expr))
4103               expr = save_expr(expr);
4104             tree compare = fold_build2_loc(loc, EQ_EXPR, boolean_type_node,
4105                                            expr,
4106                                            fold_convert(TREE_TYPE(expr),
4107                                                         null_pointer_node));
4108             tree crash = Gogo::runtime_error(RUNTIME_ERROR_NIL_DEREFERENCE,
4109                                              loc);
4110             expr = fold_build2_loc(loc, COMPOUND_EXPR, TREE_TYPE(expr),
4111                                    build3(COND_EXPR, void_type_node,
4112                                           compare, crash, NULL_TREE),
4113                                    expr);
4114           }
4115
4116         // If the type of EXPR is a recursive pointer type, then we
4117         // need to insert a cast before indirecting.
4118         if (TREE_TYPE(TREE_TYPE(expr)) == ptr_type_node)
4119           {
4120             Type* pt = this->expr_->type()->points_to();
4121             tree ind = pt->get_tree(context->gogo());
4122             expr = fold_convert_loc(loc, build_pointer_type(ind), expr);
4123           }
4124
4125         return build_fold_indirect_ref_loc(loc, expr);
4126       }
4127
4128     default:
4129       gcc_unreachable();
4130     }
4131 }
4132
4133 // Export a unary expression.
4134
4135 void
4136 Unary_expression::do_export(Export* exp) const
4137 {
4138   switch (this->op_)
4139     {
4140     case OPERATOR_PLUS:
4141       exp->write_c_string("+ ");
4142       break;
4143     case OPERATOR_MINUS:
4144       exp->write_c_string("- ");
4145       break;
4146     case OPERATOR_NOT:
4147       exp->write_c_string("! ");
4148       break;
4149     case OPERATOR_XOR:
4150       exp->write_c_string("^ ");
4151       break;
4152     case OPERATOR_AND:
4153     case OPERATOR_MULT:
4154     default:
4155       gcc_unreachable();
4156     }
4157   this->expr_->export_expression(exp);
4158 }
4159
4160 // Import a unary expression.
4161
4162 Expression*
4163 Unary_expression::do_import(Import* imp)
4164 {
4165   Operator op;
4166   switch (imp->get_char())
4167     {
4168     case '+':
4169       op = OPERATOR_PLUS;
4170       break;
4171     case '-':
4172       op = OPERATOR_MINUS;
4173       break;
4174     case '!':
4175       op = OPERATOR_NOT;
4176       break;
4177     case '^':
4178       op = OPERATOR_XOR;
4179       break;
4180     default:
4181       gcc_unreachable();
4182     }
4183   imp->require_c_string(" ");
4184   Expression* expr = Expression::import_expression(imp);
4185   return Expression::make_unary(op, expr, imp->location());
4186 }
4187
4188 // Make a unary expression.
4189
4190 Expression*
4191 Expression::make_unary(Operator op, Expression* expr, source_location location)
4192 {
4193   return new Unary_expression(op, expr, location);
4194 }
4195
4196 // If this is an indirection through a pointer, return the expression
4197 // being pointed through.  Otherwise return this.
4198
4199 Expression*
4200 Expression::deref()
4201 {
4202   if (this->classification_ == EXPRESSION_UNARY)
4203     {
4204       Unary_expression* ue = static_cast<Unary_expression*>(this);
4205       if (ue->op() == OPERATOR_MULT)
4206         return ue->operand();
4207     }
4208   return this;
4209 }
4210
4211 // Class Binary_expression.
4212
4213 // Traversal.
4214
4215 int
4216 Binary_expression::do_traverse(Traverse* traverse)
4217 {
4218   int t = Expression::traverse(&this->left_, traverse);
4219   if (t == TRAVERSE_EXIT)
4220     return TRAVERSE_EXIT;
4221   return Expression::traverse(&this->right_, traverse);
4222 }
4223
4224 // Compare integer constants according to OP.
4225
4226 bool
4227 Binary_expression::compare_integer(Operator op, mpz_t left_val,
4228                                    mpz_t right_val)
4229 {
4230   int i = mpz_cmp(left_val, right_val);
4231   switch (op)
4232     {
4233     case OPERATOR_EQEQ:
4234       return i == 0;
4235     case OPERATOR_NOTEQ:
4236       return i != 0;
4237     case OPERATOR_LT:
4238       return i < 0;
4239     case OPERATOR_LE:
4240       return i <= 0;
4241     case OPERATOR_GT:
4242       return i > 0;
4243     case OPERATOR_GE:
4244       return i >= 0;
4245     default:
4246       gcc_unreachable();
4247     }
4248 }
4249
4250 // Compare floating point constants according to OP.
4251
4252 bool
4253 Binary_expression::compare_float(Operator op, Type* type, mpfr_t left_val,
4254                                  mpfr_t right_val)
4255 {
4256   int i;
4257   if (type == NULL)
4258     i = mpfr_cmp(left_val, right_val);
4259   else
4260     {
4261       mpfr_t lv;
4262       mpfr_init_set(lv, left_val, GMP_RNDN);
4263       mpfr_t rv;
4264       mpfr_init_set(rv, right_val, GMP_RNDN);
4265       Float_expression::constrain_float(lv, type);
4266       Float_expression::constrain_float(rv, type);
4267       i = mpfr_cmp(lv, rv);
4268       mpfr_clear(lv);
4269       mpfr_clear(rv);
4270     }
4271   switch (op)
4272     {
4273     case OPERATOR_EQEQ:
4274       return i == 0;
4275     case OPERATOR_NOTEQ:
4276       return i != 0;
4277     case OPERATOR_LT:
4278       return i < 0;
4279     case OPERATOR_LE:
4280       return i <= 0;
4281     case OPERATOR_GT:
4282       return i > 0;
4283     case OPERATOR_GE:
4284       return i >= 0;
4285     default:
4286       gcc_unreachable();
4287     }
4288 }
4289
4290 // Compare complex constants according to OP.  Complex numbers may
4291 // only be compared for equality.
4292
4293 bool
4294 Binary_expression::compare_complex(Operator op, Type* type,
4295                                    mpfr_t left_real, mpfr_t left_imag,
4296                                    mpfr_t right_real, mpfr_t right_imag)
4297 {
4298   bool is_equal;
4299   if (type == NULL)
4300     is_equal = (mpfr_cmp(left_real, right_real) == 0
4301                 && mpfr_cmp(left_imag, right_imag) == 0);
4302   else
4303     {
4304       mpfr_t lr;
4305       mpfr_t li;
4306       mpfr_init_set(lr, left_real, GMP_RNDN);
4307       mpfr_init_set(li, left_imag, GMP_RNDN);
4308       mpfr_t rr;
4309       mpfr_t ri;
4310       mpfr_init_set(rr, right_real, GMP_RNDN);
4311       mpfr_init_set(ri, right_imag, GMP_RNDN);
4312       Complex_expression::constrain_complex(lr, li, type);
4313       Complex_expression::constrain_complex(rr, ri, type);
4314       is_equal = mpfr_cmp(lr, rr) == 0 && mpfr_cmp(li, ri) == 0;
4315       mpfr_clear(lr);
4316       mpfr_clear(li);
4317       mpfr_clear(rr);
4318       mpfr_clear(ri);
4319     }
4320   switch (op)
4321     {
4322     case OPERATOR_EQEQ:
4323       return is_equal;
4324     case OPERATOR_NOTEQ:
4325       return !is_equal;
4326     default:
4327       gcc_unreachable();
4328     }
4329 }
4330
4331 // Apply binary opcode OP to LEFT_VAL and RIGHT_VAL, setting VAL.
4332 // LEFT_TYPE is the type of LEFT_VAL, RIGHT_TYPE is the type of
4333 // RIGHT_VAL; LEFT_TYPE and/or RIGHT_TYPE may be NULL.  Return true if
4334 // this could be done, false if not.
4335
4336 bool
4337 Binary_expression::eval_integer(Operator op, Type* left_type, mpz_t left_val,
4338                                 Type* right_type, mpz_t right_val,
4339                                 source_location location, mpz_t val)
4340 {
4341   bool is_shift_op = false;
4342   switch (op)
4343     {
4344     case OPERATOR_OROR:
4345     case OPERATOR_ANDAND:
4346     case OPERATOR_EQEQ:
4347     case OPERATOR_NOTEQ:
4348     case OPERATOR_LT:
4349     case OPERATOR_LE:
4350     case OPERATOR_GT:
4351     case OPERATOR_GE:
4352       // These return boolean values.  We should probably handle them
4353       // anyhow in case a type conversion is used on the result.
4354       return false;
4355     case OPERATOR_PLUS:
4356       mpz_add(val, left_val, right_val);
4357       break;
4358     case OPERATOR_MINUS:
4359       mpz_sub(val, left_val, right_val);
4360       break;
4361     case OPERATOR_OR:
4362       mpz_ior(val, left_val, right_val);
4363       break;
4364     case OPERATOR_XOR:
4365       mpz_xor(val, left_val, right_val);
4366       break;
4367     case OPERATOR_MULT:
4368       mpz_mul(val, left_val, right_val);
4369       break;
4370     case OPERATOR_DIV:
4371       if (mpz_sgn(right_val) != 0)
4372         mpz_tdiv_q(val, left_val, right_val);
4373       else
4374         {
4375           error_at(location, "division by zero");
4376           mpz_set_ui(val, 0);
4377           return true;
4378         }
4379       break;
4380     case OPERATOR_MOD:
4381       if (mpz_sgn(right_val) != 0)
4382         mpz_tdiv_r(val, left_val, right_val);
4383       else
4384         {
4385           error_at(location, "division by zero");
4386           mpz_set_ui(val, 0);
4387           return true;
4388         }
4389       break;
4390     case OPERATOR_LSHIFT:
4391       {
4392         unsigned long shift = mpz_get_ui(right_val);
4393         if (mpz_cmp_ui(right_val, shift) != 0)
4394           {
4395             error_at(location, "shift count overflow");
4396             mpz_set_ui(val, 0);
4397             return true;
4398           }
4399         mpz_mul_2exp(val, left_val, shift);
4400         is_shift_op = true;
4401         break;
4402       }
4403       break;
4404     case OPERATOR_RSHIFT:
4405       {
4406         unsigned long shift = mpz_get_ui(right_val);
4407         if (mpz_cmp_ui(right_val, shift) != 0)
4408           {
4409             error_at(location, "shift count overflow");
4410             mpz_set_ui(val, 0);
4411             return true;
4412           }
4413         if (mpz_cmp_ui(left_val, 0) >= 0)
4414           mpz_tdiv_q_2exp(val, left_val, shift);
4415         else
4416           mpz_fdiv_q_2exp(val, left_val, shift);
4417         is_shift_op = true;
4418         break;
4419       }
4420       break;
4421     case OPERATOR_AND:
4422       mpz_and(val, left_val, right_val);
4423       break;
4424     case OPERATOR_BITCLEAR:
4425       {
4426         mpz_t tval;
4427         mpz_init(tval);
4428         mpz_com(tval, right_val);
4429         mpz_and(val, left_val, tval);
4430         mpz_clear(tval);
4431       }
4432       break;
4433     default:
4434       gcc_unreachable();
4435     }
4436
4437   Type* type = left_type;
4438   if (!is_shift_op)
4439     {
4440       if (type == NULL)
4441         type = right_type;
4442       else if (type != right_type && right_type != NULL)
4443         {
4444           if (type->is_abstract())
4445             type = right_type;
4446           else if (!right_type->is_abstract())
4447             {
4448               // This look like a type error which should be diagnosed
4449               // elsewhere.  Don't do anything here, to avoid an
4450               // unhelpful chain of error messages.
4451               return true;
4452             }
4453         }
4454     }
4455
4456   if (type != NULL && !type->is_abstract())
4457     {
4458       // We have to check the operands too, as we have implicitly
4459       // coerced them to TYPE.
4460       if ((type != left_type
4461            && !Integer_expression::check_constant(left_val, type, location))
4462           || (!is_shift_op
4463               && type != right_type
4464               && !Integer_expression::check_constant(right_val, type,
4465                                                      location))
4466           || !Integer_expression::check_constant(val, type, location))
4467         mpz_set_ui(val, 0);
4468     }
4469
4470   return true;
4471 }
4472
4473 // Apply binary opcode OP to LEFT_VAL and RIGHT_VAL, setting VAL.
4474 // Return true if this could be done, false if not.
4475
4476 bool
4477 Binary_expression::eval_float(Operator op, Type* left_type, mpfr_t left_val,
4478                               Type* right_type, mpfr_t right_val,
4479                               mpfr_t val, source_location location)
4480 {
4481   switch (op)
4482     {
4483     case OPERATOR_OROR:
4484     case OPERATOR_ANDAND:
4485     case OPERATOR_EQEQ:
4486     case OPERATOR_NOTEQ:
4487     case OPERATOR_LT:
4488     case OPERATOR_LE:
4489     case OPERATOR_GT:
4490     case OPERATOR_GE:
4491       // These return boolean values.  We should probably handle them
4492       // anyhow in case a type conversion is used on the result.
4493       return false;
4494     case OPERATOR_PLUS:
4495       mpfr_add(val, left_val, right_val, GMP_RNDN);
4496       break;
4497     case OPERATOR_MINUS:
4498       mpfr_sub(val, left_val, right_val, GMP_RNDN);
4499       break;
4500     case OPERATOR_OR:
4501     case OPERATOR_XOR:
4502     case OPERATOR_AND:
4503     case OPERATOR_BITCLEAR:
4504       return false;
4505     case OPERATOR_MULT:
4506       mpfr_mul(val, left_val, right_val, GMP_RNDN);
4507       break;
4508     case OPERATOR_DIV:
4509       if (mpfr_zero_p(right_val))
4510         error_at(location, "division by zero");
4511       mpfr_div(val, left_val, right_val, GMP_RNDN);
4512       break;
4513     case OPERATOR_MOD:
4514       return false;
4515     case OPERATOR_LSHIFT:
4516     case OPERATOR_RSHIFT:
4517       return false;
4518     default:
4519       gcc_unreachable();
4520     }
4521
4522   Type* type = left_type;
4523   if (type == NULL)
4524     type = right_type;
4525   else if (type != right_type && right_type != NULL)
4526     {
4527       if (type->is_abstract())
4528         type = right_type;
4529       else if (!right_type->is_abstract())
4530         {
4531           // This looks like a type error which should be diagnosed
4532           // elsewhere.  Don't do anything here, to avoid an unhelpful
4533           // chain of error messages.
4534           return true;
4535         }
4536     }
4537
4538   if (type != NULL && !type->is_abstract())
4539     {
4540       if ((type != left_type
4541            && !Float_expression::check_constant(left_val, type, location))
4542           || (type != right_type
4543               && !Float_expression::check_constant(right_val, type,
4544                                                    location))
4545           || !Float_expression::check_constant(val, type, location))
4546         mpfr_set_ui(val, 0, GMP_RNDN);
4547     }
4548
4549   return true;
4550 }
4551
4552 // Apply binary opcode OP to LEFT_REAL/LEFT_IMAG and
4553 // RIGHT_REAL/RIGHT_IMAG, setting REAL/IMAG.  Return true if this
4554 // could be done, false if not.
4555
4556 bool
4557 Binary_expression::eval_complex(Operator op, Type* left_type,
4558                                 mpfr_t left_real, mpfr_t left_imag,
4559                                 Type *right_type,
4560                                 mpfr_t right_real, mpfr_t right_imag,
4561                                 mpfr_t real, mpfr_t imag,
4562                                 source_location location)
4563 {
4564   switch (op)
4565     {
4566     case OPERATOR_OROR:
4567     case OPERATOR_ANDAND:
4568     case OPERATOR_EQEQ:
4569     case OPERATOR_NOTEQ:
4570     case OPERATOR_LT:
4571     case OPERATOR_LE:
4572     case OPERATOR_GT:
4573     case OPERATOR_GE:
4574       // These return boolean values and must be handled differently.
4575       return false;
4576     case OPERATOR_PLUS:
4577       mpfr_add(real, left_real, right_real, GMP_RNDN);
4578       mpfr_add(imag, left_imag, right_imag, GMP_RNDN);
4579       break;
4580     case OPERATOR_MINUS:
4581       mpfr_sub(real, left_real, right_real, GMP_RNDN);
4582       mpfr_sub(imag, left_imag, right_imag, GMP_RNDN);
4583       break;
4584     case OPERATOR_OR:
4585     case OPERATOR_XOR:
4586     case OPERATOR_AND:
4587     case OPERATOR_BITCLEAR:
4588       return false;
4589     case OPERATOR_MULT:
4590       {
4591         // You might think that multiplying two complex numbers would
4592         // be simple, and you would be right, until you start to think
4593         // about getting the right answer for infinity.  If one
4594         // operand here is infinity and the other is anything other
4595         // than zero or NaN, then we are going to wind up subtracting
4596         // two infinity values.  That will give us a NaN, but the
4597         // correct answer is infinity.
4598
4599         mpfr_t lrrr;
4600         mpfr_init(lrrr);
4601         mpfr_mul(lrrr, left_real, right_real, GMP_RNDN);
4602
4603         mpfr_t lrri;
4604         mpfr_init(lrri);
4605         mpfr_mul(lrri, left_real, right_imag, GMP_RNDN);
4606
4607         mpfr_t lirr;
4608         mpfr_init(lirr);
4609         mpfr_mul(lirr, left_imag, right_real, GMP_RNDN);
4610
4611         mpfr_t liri;
4612         mpfr_init(liri);
4613         mpfr_mul(liri, left_imag, right_imag, GMP_RNDN);
4614
4615         mpfr_sub(real, lrrr, liri, GMP_RNDN);
4616         mpfr_add(imag, lrri, lirr, GMP_RNDN);
4617
4618         // If we get NaN on both sides, check whether it should really
4619         // be infinity.  The rule is that if either side of the
4620         // complex number is infinity, then the whole value is
4621         // infinity, even if the other side is NaN.  So the only case
4622         // we have to fix is the one in which both sides are NaN.
4623         if (mpfr_nan_p(real) && mpfr_nan_p(imag)
4624             && (!mpfr_nan_p(left_real) || !mpfr_nan_p(left_imag))
4625             && (!mpfr_nan_p(right_real) || !mpfr_nan_p(right_imag)))
4626           {
4627             bool is_infinity = false;
4628
4629             mpfr_t lr;
4630             mpfr_t li;
4631             mpfr_init_set(lr, left_real, GMP_RNDN);
4632             mpfr_init_set(li, left_imag, GMP_RNDN);
4633
4634             mpfr_t rr;
4635             mpfr_t ri;
4636             mpfr_init_set(rr, right_real, GMP_RNDN);
4637             mpfr_init_set(ri, right_imag, GMP_RNDN);
4638
4639             // If the left side is infinity, then the result is
4640             // infinity.
4641             if (mpfr_inf_p(lr) || mpfr_inf_p(li))
4642               {
4643                 mpfr_set_ui(lr, mpfr_inf_p(lr) ? 1 : 0, GMP_RNDN);
4644                 mpfr_copysign(lr, lr, left_real, GMP_RNDN);
4645                 mpfr_set_ui(li, mpfr_inf_p(li) ? 1 : 0, GMP_RNDN);
4646                 mpfr_copysign(li, li, left_imag, GMP_RNDN);
4647                 if (mpfr_nan_p(rr))
4648                   {
4649                     mpfr_set_ui(rr, 0, GMP_RNDN);
4650                     mpfr_copysign(rr, rr, right_real, GMP_RNDN);
4651                   }
4652                 if (mpfr_nan_p(ri))
4653                   {
4654                     mpfr_set_ui(ri, 0, GMP_RNDN);
4655                     mpfr_copysign(ri, ri, right_imag, GMP_RNDN);
4656                   }
4657                 is_infinity = true;
4658               }
4659
4660             // If the right side is infinity, then the result is
4661             // infinity.
4662             if (mpfr_inf_p(rr) || mpfr_inf_p(ri))
4663               {
4664                 mpfr_set_ui(rr, mpfr_inf_p(rr) ? 1 : 0, GMP_RNDN);
4665                 mpfr_copysign(rr, rr, right_real, GMP_RNDN);
4666                 mpfr_set_ui(ri, mpfr_inf_p(ri) ? 1 : 0, GMP_RNDN);
4667                 mpfr_copysign(ri, ri, right_imag, GMP_RNDN);
4668                 if (mpfr_nan_p(lr))
4669                   {
4670                     mpfr_set_ui(lr, 0, GMP_RNDN);
4671                     mpfr_copysign(lr, lr, left_real, GMP_RNDN);
4672                   }
4673                 if (mpfr_nan_p(li))
4674                   {
4675                     mpfr_set_ui(li, 0, GMP_RNDN);
4676                     mpfr_copysign(li, li, left_imag, GMP_RNDN);
4677                   }
4678                 is_infinity = true;
4679               }
4680
4681             // If we got an overflow in the intermediate computations,
4682             // then the result is infinity.
4683             if (!is_infinity
4684                 && (mpfr_inf_p(lrrr) || mpfr_inf_p(lrri)
4685                     || mpfr_inf_p(lirr) || mpfr_inf_p(liri)))
4686               {
4687                 if (mpfr_nan_p(lr))
4688                   {
4689                     mpfr_set_ui(lr, 0, GMP_RNDN);
4690                     mpfr_copysign(lr, lr, left_real, GMP_RNDN);
4691                   }
4692                 if (mpfr_nan_p(li))
4693                   {
4694                     mpfr_set_ui(li, 0, GMP_RNDN);
4695                     mpfr_copysign(li, li, left_imag, GMP_RNDN);
4696                   }
4697                 if (mpfr_nan_p(rr))
4698                   {
4699                     mpfr_set_ui(rr, 0, GMP_RNDN);
4700                     mpfr_copysign(rr, rr, right_real, GMP_RNDN);
4701                   }
4702                 if (mpfr_nan_p(ri))
4703                   {
4704                     mpfr_set_ui(ri, 0, GMP_RNDN);
4705                     mpfr_copysign(ri, ri, right_imag, GMP_RNDN);
4706                   }
4707                 is_infinity = true;
4708               }
4709
4710             if (is_infinity)
4711               {
4712                 mpfr_mul(lrrr, lr, rr, GMP_RNDN);
4713                 mpfr_mul(lrri, lr, ri, GMP_RNDN);
4714                 mpfr_mul(lirr, li, rr, GMP_RNDN);
4715                 mpfr_mul(liri, li, ri, GMP_RNDN);
4716                 mpfr_sub(real, lrrr, liri, GMP_RNDN);
4717                 mpfr_add(imag, lrri, lirr, GMP_RNDN);
4718                 mpfr_set_inf(real, mpfr_sgn(real));
4719                 mpfr_set_inf(imag, mpfr_sgn(imag));
4720               }
4721
4722             mpfr_clear(lr);
4723             mpfr_clear(li);
4724             mpfr_clear(rr);
4725             mpfr_clear(ri);
4726           }
4727
4728         mpfr_clear(lrrr);
4729         mpfr_clear(lrri);
4730         mpfr_clear(lirr);
4731         mpfr_clear(liri);
4732       }
4733       break;
4734     case OPERATOR_DIV:
4735       {
4736         // For complex division we want to avoid having an
4737         // intermediate overflow turn the whole result in a NaN.  We
4738         // scale the values to try to avoid this.
4739
4740         if (mpfr_zero_p(right_real) && mpfr_zero_p(right_imag))
4741           error_at(location, "division by zero");
4742
4743         mpfr_t rra;
4744         mpfr_t ria;
4745         mpfr_init(rra);
4746         mpfr_init(ria);
4747         mpfr_abs(rra, right_real, GMP_RNDN);
4748         mpfr_abs(ria, right_imag, GMP_RNDN);
4749         mpfr_t t;
4750         mpfr_init(t);
4751         mpfr_max(t, rra, ria, GMP_RNDN);
4752
4753         mpfr_t rr;
4754         mpfr_t ri;
4755         mpfr_init_set(rr, right_real, GMP_RNDN);
4756         mpfr_init_set(ri, right_imag, GMP_RNDN);
4757         long ilogbw = 0;
4758         if (!mpfr_inf_p(t) && !mpfr_nan_p(t) && !mpfr_zero_p(t))
4759           {
4760             ilogbw = mpfr_get_exp(t);
4761             mpfr_mul_2si(rr, rr, - ilogbw, GMP_RNDN);
4762             mpfr_mul_2si(ri, ri, - ilogbw, GMP_RNDN);
4763           }
4764
4765         mpfr_t denom;
4766         mpfr_init(denom);
4767         mpfr_mul(denom, rr, rr, GMP_RNDN);
4768         mpfr_mul(t, ri, ri, GMP_RNDN);
4769         mpfr_add(denom, denom, t, GMP_RNDN);
4770
4771         mpfr_mul(real, left_real, rr, GMP_RNDN);
4772         mpfr_mul(t, left_imag, ri, GMP_RNDN);
4773         mpfr_add(real, real, t, GMP_RNDN);
4774         mpfr_div(real, real, denom, GMP_RNDN);
4775         mpfr_mul_2si(real, real, - ilogbw, GMP_RNDN);
4776
4777         mpfr_mul(imag, left_imag, rr, GMP_RNDN);
4778         mpfr_mul(t, left_real, ri, GMP_RNDN);
4779         mpfr_sub(imag, imag, t, GMP_RNDN);
4780         mpfr_div(imag, imag, denom, GMP_RNDN);
4781         mpfr_mul_2si(imag, imag, - ilogbw, GMP_RNDN);
4782
4783         // If we wind up with NaN on both sides, check whether we
4784         // should really have infinity.  The rule is that if either
4785         // side of the complex number is infinity, then the whole
4786         // value is infinity, even if the other side is NaN.  So the
4787         // only case we have to fix is the one in which both sides are
4788         // NaN.
4789         if (mpfr_nan_p(real) && mpfr_nan_p(imag)
4790             && (!mpfr_nan_p(left_real) || !mpfr_nan_p(left_imag))
4791             && (!mpfr_nan_p(right_real) || !mpfr_nan_p(right_imag)))
4792           {
4793             if (mpfr_zero_p(denom))
4794               {
4795                 mpfr_set_inf(real, mpfr_sgn(rr));
4796                 mpfr_mul(real, real, left_real, GMP_RNDN);
4797                 mpfr_set_inf(imag, mpfr_sgn(rr));
4798                 mpfr_mul(imag, imag, left_imag, GMP_RNDN);
4799               }
4800             else if ((mpfr_inf_p(left_real) || mpfr_inf_p(left_imag))
4801                      && mpfr_number_p(rr) && mpfr_number_p(ri))
4802               {
4803                 mpfr_set_ui(t, mpfr_inf_p(left_real) ? 1 : 0, GMP_RNDN);
4804                 mpfr_copysign(t, t, left_real, GMP_RNDN);
4805
4806                 mpfr_t t2;
4807                 mpfr_init_set_ui(t2, mpfr_inf_p(left_imag) ? 1 : 0, GMP_RNDN);
4808                 mpfr_copysign(t2, t2, left_imag, GMP_RNDN);
4809
4810                 mpfr_t t3;
4811                 mpfr_init(t3);
4812                 mpfr_mul(t3, t, rr, GMP_RNDN);
4813
4814                 mpfr_t t4;
4815                 mpfr_init(t4);
4816                 mpfr_mul(t4, t2, ri, GMP_RNDN);
4817
4818                 mpfr_add(t3, t3, t4, GMP_RNDN);
4819                 mpfr_set_inf(real, mpfr_sgn(t3));
4820
4821                 mpfr_mul(t3, t2, rr, GMP_RNDN);
4822                 mpfr_mul(t4, t, ri, GMP_RNDN);
4823                 mpfr_sub(t3, t3, t4, GMP_RNDN);
4824                 mpfr_set_inf(imag, mpfr_sgn(t3));
4825
4826                 mpfr_clear(t2);
4827                 mpfr_clear(t3);
4828                 mpfr_clear(t4);
4829               }
4830             else if ((mpfr_inf_p(right_real) || mpfr_inf_p(right_imag))
4831                      && mpfr_number_p(left_real) && mpfr_number_p(left_imag))
4832               {
4833                 mpfr_set_ui(t, mpfr_inf_p(rr) ? 1 : 0, GMP_RNDN);
4834                 mpfr_copysign(t, t, rr, GMP_RNDN);
4835
4836                 mpfr_t t2;
4837                 mpfr_init_set_ui(t2, mpfr_inf_p(ri) ? 1 : 0, GMP_RNDN);
4838                 mpfr_copysign(t2, t2, ri, GMP_RNDN);
4839
4840                 mpfr_t t3;
4841                 mpfr_init(t3);
4842                 mpfr_mul(t3, left_real, t, GMP_RNDN);
4843
4844                 mpfr_t t4;
4845                 mpfr_init(t4);
4846                 mpfr_mul(t4, left_imag, t2, GMP_RNDN);
4847
4848                 mpfr_add(t3, t3, t4, GMP_RNDN);
4849                 mpfr_set_ui(real, 0, GMP_RNDN);
4850                 mpfr_mul(real, real, t3, GMP_RNDN);
4851
4852                 mpfr_mul(t3, left_imag, t, GMP_RNDN);
4853                 mpfr_mul(t4, left_real, t2, GMP_RNDN);
4854                 mpfr_sub(t3, t3, t4, GMP_RNDN);
4855                 mpfr_set_ui(imag, 0, GMP_RNDN);
4856                 mpfr_mul(imag, imag, t3, GMP_RNDN);
4857
4858                 mpfr_clear(t2);
4859                 mpfr_clear(t3);
4860                 mpfr_clear(t4);
4861               }
4862           }
4863
4864         mpfr_clear(denom);
4865         mpfr_clear(rr);
4866         mpfr_clear(ri);
4867         mpfr_clear(t);
4868         mpfr_clear(rra);
4869         mpfr_clear(ria);
4870       }
4871       break;
4872     case OPERATOR_MOD:
4873       return false;
4874     case OPERATOR_LSHIFT:
4875     case OPERATOR_RSHIFT:
4876       return false;
4877     default:
4878       gcc_unreachable();
4879     }
4880
4881   Type* type = left_type;
4882   if (type == NULL)
4883     type = right_type;
4884   else if (type != right_type && right_type != NULL)
4885     {
4886       if (type->is_abstract())
4887         type = right_type;
4888       else if (!right_type->is_abstract())
4889         {
4890           // This looks like a type error which should be diagnosed
4891           // elsewhere.  Don't do anything here, to avoid an unhelpful
4892           // chain of error messages.
4893           return true;
4894         }
4895     }
4896
4897   if (type != NULL && !type->is_abstract())
4898     {
4899       if ((type != left_type
4900            && !Complex_expression::check_constant(left_real, left_imag,
4901                                                   type, location))
4902           || (type != right_type
4903               && !Complex_expression::check_constant(right_real, right_imag,
4904                                                      type, location))
4905           || !Complex_expression::check_constant(real, imag, type,
4906                                                  location))
4907         {
4908           mpfr_set_ui(real, 0, GMP_RNDN);
4909           mpfr_set_ui(imag, 0, GMP_RNDN);
4910         }
4911     }
4912
4913   return true;
4914 }
4915
4916 // Lower a binary expression.  We have to evaluate constant
4917 // expressions now, in order to implement Go's unlimited precision
4918 // constants.
4919
4920 Expression*
4921 Binary_expression::do_lower(Gogo*, Named_object*, int)
4922 {
4923   source_location location = this->location();
4924   Operator op = this->op_;
4925   Expression* left = this->left_;
4926   Expression* right = this->right_;
4927
4928   const bool is_comparison = (op == OPERATOR_EQEQ
4929                               || op == OPERATOR_NOTEQ
4930                               || op == OPERATOR_LT
4931                               || op == OPERATOR_LE
4932                               || op == OPERATOR_GT
4933                               || op == OPERATOR_GE);
4934
4935   // Integer constant expressions.
4936   {
4937     mpz_t left_val;
4938     mpz_init(left_val);
4939     Type* left_type;
4940     mpz_t right_val;
4941     mpz_init(right_val);
4942     Type* right_type;
4943     if (left->integer_constant_value(false, left_val, &left_type)
4944         && right->integer_constant_value(false, right_val, &right_type))
4945       {
4946         Expression* ret = NULL;
4947         if (left_type != right_type
4948             && left_type != NULL
4949             && right_type != NULL
4950             && left_type->base() != right_type->base()
4951             && op != OPERATOR_LSHIFT
4952             && op != OPERATOR_RSHIFT)
4953           {
4954             // May be a type error--let it be diagnosed later.
4955           }
4956         else if (is_comparison)
4957           {
4958             bool b = Binary_expression::compare_integer(op, left_val,
4959                                                         right_val);
4960             ret = Expression::make_cast(Type::lookup_bool_type(),
4961                                         Expression::make_boolean(b, location),
4962                                         location);
4963           }
4964         else
4965           {
4966             mpz_t val;
4967             mpz_init(val);
4968
4969             if (Binary_expression::eval_integer(op, left_type, left_val,
4970                                                 right_type, right_val,
4971                                                 location, val))
4972               {
4973                 gcc_assert(op != OPERATOR_OROR && op != OPERATOR_ANDAND);
4974                 Type* type;
4975                 if (op == OPERATOR_LSHIFT || op == OPERATOR_RSHIFT)
4976                   type = left_type;
4977                 else if (left_type == NULL)
4978                   type = right_type;
4979                 else if (right_type == NULL)
4980                   type = left_type;
4981                 else if (!left_type->is_abstract()
4982                          && left_type->named_type() != NULL)
4983                   type = left_type;
4984                 else if (!right_type->is_abstract()
4985                          && right_type->named_type() != NULL)
4986                   type = right_type;
4987                 else if (!left_type->is_abstract())
4988                   type = left_type;
4989                 else if (!right_type->is_abstract())
4990                   type = right_type;
4991                 else if (left_type->float_type() != NULL)
4992                   type = left_type;
4993                 else if (right_type->float_type() != NULL)
4994                   type = right_type;
4995                 else if (left_type->complex_type() != NULL)
4996                   type = left_type;
4997                 else if (right_type->complex_type() != NULL)
4998                   type = right_type;
4999                 else
5000                   type = left_type;
5001                 ret = Expression::make_integer(&val, type, location);
5002               }
5003
5004             mpz_clear(val);
5005           }
5006
5007         if (ret != NULL)
5008           {
5009             mpz_clear(right_val);
5010             mpz_clear(left_val);
5011             return ret;
5012           }
5013       }
5014     mpz_clear(right_val);
5015     mpz_clear(left_val);
5016   }
5017
5018   // Floating point constant expressions.
5019   {
5020     mpfr_t left_val;
5021     mpfr_init(left_val);
5022     Type* left_type;
5023     mpfr_t right_val;
5024     mpfr_init(right_val);
5025     Type* right_type;
5026     if (left->float_constant_value(left_val, &left_type)
5027         && right->float_constant_value(right_val, &right_type))
5028       {
5029         Expression* ret = NULL;
5030         if (left_type != right_type
5031             && left_type != NULL
5032             && right_type != NULL
5033             && left_type->base() != right_type->base()
5034             && op != OPERATOR_LSHIFT
5035             && op != OPERATOR_RSHIFT)
5036           {
5037             // May be a type error--let it be diagnosed later.
5038           }
5039         else if (is_comparison)
5040           {
5041             bool b = Binary_expression::compare_float(op,
5042                                                       (left_type != NULL
5043                                                        ? left_type
5044                                                        : right_type),
5045                                                       left_val, right_val);
5046             ret = Expression::make_boolean(b, location);
5047           }
5048         else
5049           {
5050             mpfr_t val;
5051             mpfr_init(val);
5052
5053             if (Binary_expression::eval_float(op, left_type, left_val,
5054                                               right_type, right_val, val,
5055                                               location))
5056               {
5057                 gcc_assert(op != OPERATOR_OROR && op != OPERATOR_ANDAND
5058                            && op != OPERATOR_LSHIFT && op != OPERATOR_RSHIFT);
5059                 Type* type;
5060                 if (left_type == NULL)
5061                   type = right_type;
5062                 else if (right_type == NULL)
5063                   type = left_type;
5064                 else if (!left_type->is_abstract()
5065                          && left_type->named_type() != NULL)
5066                   type = left_type;
5067                 else if (!right_type->is_abstract()
5068                          && right_type->named_type() != NULL)
5069                   type = right_type;
5070                 else if (!left_type->is_abstract())
5071                   type = left_type;
5072                 else if (!right_type->is_abstract())
5073                   type = right_type;
5074                 else if (left_type->float_type() != NULL)
5075                   type = left_type;
5076                 else if (right_type->float_type() != NULL)
5077                   type = right_type;
5078                 else
5079                   type = left_type;
5080                 ret = Expression::make_float(&val, type, location);
5081               }
5082
5083             mpfr_clear(val);
5084           }
5085
5086         if (ret != NULL)
5087           {
5088             mpfr_clear(right_val);
5089             mpfr_clear(left_val);
5090             return ret;
5091           }
5092       }
5093     mpfr_clear(right_val);
5094     mpfr_clear(left_val);
5095   }
5096
5097   // Complex constant expressions.
5098   {
5099     mpfr_t left_real;
5100     mpfr_t left_imag;
5101     mpfr_init(left_real);
5102     mpfr_init(left_imag);
5103     Type* left_type;
5104
5105     mpfr_t right_real;
5106     mpfr_t right_imag;
5107     mpfr_init(right_real);
5108     mpfr_init(right_imag);
5109     Type* right_type;
5110
5111     if (left->complex_constant_value(left_real, left_imag, &left_type)
5112         && right->complex_constant_value(right_real, right_imag, &right_type))
5113       {
5114         Expression* ret = NULL;
5115         if (left_type != right_type
5116             && left_type != NULL
5117             && right_type != NULL
5118             && left_type->base() != right_type->base())
5119           {
5120             // May be a type error--let it be diagnosed later.
5121           }
5122         else if (is_comparison)
5123           {
5124             bool b = Binary_expression::compare_complex(op,
5125                                                         (left_type != NULL
5126                                                          ? left_type
5127                                                          : right_type),
5128                                                         left_real,
5129                                                         left_imag,
5130                                                         right_real,
5131                                                         right_imag);
5132             ret = Expression::make_boolean(b, location);
5133           }
5134         else
5135           {
5136             mpfr_t real;
5137             mpfr_t imag;
5138             mpfr_init(real);
5139             mpfr_init(imag);
5140
5141             if (Binary_expression::eval_complex(op, left_type,
5142                                                 left_real, left_imag,
5143                                                 right_type,
5144                                                 right_real, right_imag,
5145                                                 real, imag,
5146                                                 location))
5147               {
5148                 gcc_assert(op != OPERATOR_OROR && op != OPERATOR_ANDAND
5149                            && op != OPERATOR_LSHIFT && op != OPERATOR_RSHIFT);
5150                 Type* type;
5151                 if (left_type == NULL)
5152                   type = right_type;
5153                 else if (right_type == NULL)
5154                   type = left_type;
5155                 else if (!left_type->is_abstract()
5156                          && left_type->named_type() != NULL)
5157                   type = left_type;
5158                 else if (!right_type->is_abstract()
5159                          && right_type->named_type() != NULL)
5160                   type = right_type;
5161                 else if (!left_type->is_abstract())
5162                   type = left_type;
5163                 else if (!right_type->is_abstract())
5164                   type = right_type;
5165                 else if (left_type->complex_type() != NULL)
5166                   type = left_type;
5167                 else if (right_type->complex_type() != NULL)
5168                   type = right_type;
5169                 else
5170                   type = left_type;
5171                 ret = Expression::make_complex(&real, &imag, type,
5172                                                location);
5173               }
5174             mpfr_clear(real);
5175             mpfr_clear(imag);
5176           }
5177
5178         if (ret != NULL)
5179           {
5180             mpfr_clear(left_real);
5181             mpfr_clear(left_imag);
5182             mpfr_clear(right_real);
5183             mpfr_clear(right_imag);
5184             return ret;
5185           }
5186       }
5187
5188     mpfr_clear(left_real);
5189     mpfr_clear(left_imag);
5190     mpfr_clear(right_real);
5191     mpfr_clear(right_imag);
5192   }
5193
5194   // String constant expressions.
5195   if (op == OPERATOR_PLUS
5196       && left->type()->is_string_type()
5197       && right->type()->is_string_type())
5198     {
5199       std::string left_string;
5200       std::string right_string;
5201       if (left->string_constant_value(&left_string)
5202           && right->string_constant_value(&right_string))
5203         return Expression::make_string(left_string + right_string, location);
5204     }
5205
5206   return this;
5207 }
5208
5209 // Return the integer constant value, if it has one.
5210
5211 bool
5212 Binary_expression::do_integer_constant_value(bool iota_is_constant, mpz_t val,
5213                                              Type** ptype) const
5214 {
5215   mpz_t left_val;
5216   mpz_init(left_val);
5217   Type* left_type;
5218   if (!this->left_->integer_constant_value(iota_is_constant, left_val,
5219                                            &left_type))
5220     {
5221       mpz_clear(left_val);
5222       return false;
5223     }
5224
5225   mpz_t right_val;
5226   mpz_init(right_val);
5227   Type* right_type;
5228   if (!this->right_->integer_constant_value(iota_is_constant, right_val,
5229                                             &right_type))
5230     {
5231       mpz_clear(right_val);
5232       mpz_clear(left_val);
5233       return false;
5234     }
5235
5236   bool ret;
5237   if (left_type != right_type
5238       && left_type != NULL
5239       && right_type != NULL
5240       && left_type->base() != right_type->base()
5241       && this->op_ != OPERATOR_RSHIFT
5242       && this->op_ != OPERATOR_LSHIFT)
5243     ret = false;
5244   else
5245     ret = Binary_expression::eval_integer(this->op_, left_type, left_val,
5246                                           right_type, right_val,
5247                                           this->location(), val);
5248
5249   mpz_clear(right_val);
5250   mpz_clear(left_val);
5251
5252   if (ret)
5253     *ptype = left_type;
5254
5255   return ret;
5256 }
5257
5258 // Return the floating point constant value, if it has one.
5259
5260 bool
5261 Binary_expression::do_float_constant_value(mpfr_t val, Type** ptype) const
5262 {
5263   mpfr_t left_val;
5264   mpfr_init(left_val);
5265   Type* left_type;
5266   if (!this->left_->float_constant_value(left_val, &left_type))
5267     {
5268       mpfr_clear(left_val);
5269       return false;
5270     }
5271
5272   mpfr_t right_val;
5273   mpfr_init(right_val);
5274   Type* right_type;
5275   if (!this->right_->float_constant_value(right_val, &right_type))
5276     {
5277       mpfr_clear(right_val);
5278       mpfr_clear(left_val);
5279       return false;
5280     }
5281
5282   bool ret;
5283   if (left_type != right_type
5284       && left_type != NULL
5285       && right_type != NULL
5286       && left_type->base() != right_type->base())
5287     ret = false;
5288   else
5289     ret = Binary_expression::eval_float(this->op_, left_type, left_val,
5290                                         right_type, right_val,
5291                                         val, this->location());
5292
5293   mpfr_clear(left_val);
5294   mpfr_clear(right_val);
5295
5296   if (ret)
5297     *ptype = left_type;
5298
5299   return ret;
5300 }
5301
5302 // Return the complex constant value, if it has one.
5303
5304 bool
5305 Binary_expression::do_complex_constant_value(mpfr_t real, mpfr_t imag,
5306                                              Type** ptype) const
5307 {
5308   mpfr_t left_real;
5309   mpfr_t left_imag;
5310   mpfr_init(left_real);
5311   mpfr_init(left_imag);
5312   Type* left_type;
5313   if (!this->left_->complex_constant_value(left_real, left_imag, &left_type))
5314     {
5315       mpfr_clear(left_real);
5316       mpfr_clear(left_imag);
5317       return false;
5318     }
5319
5320   mpfr_t right_real;
5321   mpfr_t right_imag;
5322   mpfr_init(right_real);
5323   mpfr_init(right_imag);
5324   Type* right_type;
5325   if (!this->right_->complex_constant_value(right_real, right_imag,
5326                                             &right_type))
5327     {
5328       mpfr_clear(left_real);
5329       mpfr_clear(left_imag);
5330       mpfr_clear(right_real);
5331       mpfr_clear(right_imag);
5332       return false;
5333     }
5334
5335   bool ret;
5336   if (left_type != right_type
5337       && left_type != NULL
5338       && right_type != NULL
5339       && left_type->base() != right_type->base())
5340     ret = false;
5341   else
5342     ret = Binary_expression::eval_complex(this->op_, left_type,
5343                                           left_real, left_imag,
5344                                           right_type,
5345                                           right_real, right_imag,
5346                                           real, imag,
5347                                           this->location());
5348   mpfr_clear(left_real);
5349   mpfr_clear(left_imag);
5350   mpfr_clear(right_real);
5351   mpfr_clear(right_imag);
5352
5353   if (ret)
5354     *ptype = left_type;
5355
5356   return ret;
5357 }
5358
5359 // Note that the value is being discarded.
5360
5361 void
5362 Binary_expression::do_discarding_value()
5363 {
5364   if (this->op_ == OPERATOR_OROR || this->op_ == OPERATOR_ANDAND)
5365     this->right_->discarding_value();
5366   else
5367     this->warn_about_unused_value();
5368 }
5369
5370 // Get type.
5371
5372 Type*
5373 Binary_expression::do_type()
5374 {
5375   switch (this->op_)
5376     {
5377     case OPERATOR_OROR:
5378     case OPERATOR_ANDAND:
5379     case OPERATOR_EQEQ:
5380     case OPERATOR_NOTEQ:
5381     case OPERATOR_LT:
5382     case OPERATOR_LE:
5383     case OPERATOR_GT:
5384     case OPERATOR_GE:
5385       return Type::lookup_bool_type();
5386
5387     case OPERATOR_PLUS:
5388     case OPERATOR_MINUS:
5389     case OPERATOR_OR:
5390     case OPERATOR_XOR:
5391     case OPERATOR_MULT:
5392     case OPERATOR_DIV:
5393     case OPERATOR_MOD:
5394     case OPERATOR_AND:
5395     case OPERATOR_BITCLEAR:
5396       {
5397         Type* left_type = this->left_->type();
5398         Type* right_type = this->right_->type();
5399         if (!left_type->is_abstract() && left_type->named_type() != NULL)
5400           return left_type;
5401         else if (!right_type->is_abstract() && right_type->named_type() != NULL)
5402           return right_type;
5403         else if (!left_type->is_abstract())
5404           return left_type;
5405         else if (!right_type->is_abstract())
5406           return right_type;
5407         else if (left_type->complex_type() != NULL)
5408           return left_type;
5409         else if (right_type->complex_type() != NULL)
5410           return right_type;
5411         else if (left_type->float_type() != NULL)
5412           return left_type;
5413         else if (right_type->float_type() != NULL)
5414           return right_type;
5415         else
5416           return left_type;
5417       }
5418
5419     case OPERATOR_LSHIFT:
5420     case OPERATOR_RSHIFT:
5421       return this->left_->type();
5422
5423     default:
5424       gcc_unreachable();
5425     }
5426 }
5427
5428 // Set type for a binary expression.
5429
5430 void
5431 Binary_expression::do_determine_type(const Type_context* context)
5432 {
5433   Type* tleft = this->left_->type();
5434   Type* tright = this->right_->type();
5435
5436   // Both sides should have the same type, except for the shift
5437   // operations.  For a comparison, we should ignore the incoming
5438   // type.
5439
5440   bool is_shift_op = (this->op_ == OPERATOR_LSHIFT
5441                       || this->op_ == OPERATOR_RSHIFT);
5442
5443   bool is_comparison = (this->op_ == OPERATOR_EQEQ
5444                         || this->op_ == OPERATOR_NOTEQ
5445                         || this->op_ == OPERATOR_LT
5446                         || this->op_ == OPERATOR_LE
5447                         || this->op_ == OPERATOR_GT
5448                         || this->op_ == OPERATOR_GE);
5449
5450   Type_context subcontext(*context);
5451
5452   if (is_comparison)
5453     {
5454       // In a comparison, the context does not determine the types of
5455       // the operands.
5456       subcontext.type = NULL;
5457     }
5458
5459   // Set the context for the left hand operand.
5460   if (is_shift_op)
5461     {
5462       // The right hand operand plays no role in determining the type
5463       // of the left hand operand.  A shift of an abstract integer in
5464       // a string context gets special treatment, which may be a
5465       // language bug.
5466       if (subcontext.type != NULL
5467           && subcontext.type->is_string_type()
5468           && tleft->is_abstract())
5469         error_at(this->location(), "shift of non-integer operand");
5470     }
5471   else if (!tleft->is_abstract())
5472     subcontext.type = tleft;
5473   else if (!tright->is_abstract())
5474     subcontext.type = tright;
5475   else if (subcontext.type == NULL)
5476     {
5477       if ((tleft->integer_type() != NULL && tright->integer_type() != NULL)
5478           || (tleft->float_type() != NULL && tright->float_type() != NULL)
5479           || (tleft->complex_type() != NULL && tright->complex_type() != NULL))
5480         {
5481           // Both sides have an abstract integer, abstract float, or
5482           // abstract complex type.  Just let CONTEXT determine
5483           // whether they may remain abstract or not.
5484         }
5485       else if (tleft->complex_type() != NULL)
5486         subcontext.type = tleft;
5487       else if (tright->complex_type() != NULL)
5488         subcontext.type = tright;
5489       else if (tleft->float_type() != NULL)
5490         subcontext.type = tleft;
5491       else if (tright->float_type() != NULL)
5492         subcontext.type = tright;
5493       else
5494         subcontext.type = tleft;
5495     }
5496
5497   this->left_->determine_type(&subcontext);
5498
5499   // The context for the right hand operand is the same as for the
5500   // left hand operand, except for a shift operator.
5501   if (is_shift_op)
5502     {
5503       subcontext.type = Type::lookup_integer_type("uint");
5504       subcontext.may_be_abstract = false;
5505     }
5506
5507   this->right_->determine_type(&subcontext);
5508 }
5509
5510 // Report an error if the binary operator OP does not support TYPE.
5511 // Return whether the operation is OK.  This should not be used for
5512 // shift.
5513
5514 bool
5515 Binary_expression::check_operator_type(Operator op, Type* type,
5516                                        source_location location)
5517 {
5518   switch (op)
5519     {
5520     case OPERATOR_OROR:
5521     case OPERATOR_ANDAND:
5522       if (!type->is_boolean_type())
5523         {
5524           error_at(location, "expected boolean type");
5525           return false;
5526         }
5527       break;
5528
5529     case OPERATOR_EQEQ:
5530     case OPERATOR_NOTEQ:
5531       if (type->integer_type() == NULL
5532           && type->float_type() == NULL
5533           && type->complex_type() == NULL
5534           && !type->is_string_type()
5535           && type->points_to() == NULL
5536           && !type->is_nil_type()
5537           && !type->is_boolean_type()
5538           && type->interface_type() == NULL
5539           && (type->array_type() == NULL
5540               || type->array_type()->length() != NULL)
5541           && type->map_type() == NULL
5542           && type->channel_type() == NULL
5543           && type->function_type() == NULL)
5544         {
5545           error_at(location,
5546                    ("expected integer, floating, complex, string, pointer, "
5547                     "boolean, interface, slice, map, channel, "
5548                     "or function type"));
5549           return false;
5550         }
5551       break;
5552
5553     case OPERATOR_LT:
5554     case OPERATOR_LE:
5555     case OPERATOR_GT:
5556     case OPERATOR_GE:
5557       if (type->integer_type() == NULL
5558           && type->float_type() == NULL
5559           && !type->is_string_type())
5560         {
5561           error_at(location, "expected integer, floating, or string type");
5562           return false;
5563         }
5564       break;
5565
5566     case OPERATOR_PLUS:
5567     case OPERATOR_PLUSEQ:
5568       if (type->integer_type() == NULL
5569           && type->float_type() == NULL
5570           && type->complex_type() == NULL
5571           && !type->is_string_type())
5572         {
5573           error_at(location,
5574                    "expected integer, floating, complex, or string type");
5575           return false;
5576         }
5577       break;
5578
5579     case OPERATOR_MINUS:
5580     case OPERATOR_MINUSEQ:
5581     case OPERATOR_MULT:
5582     case OPERATOR_MULTEQ:
5583     case OPERATOR_DIV:
5584     case OPERATOR_DIVEQ:
5585       if (type->integer_type() == NULL
5586           && type->float_type() == NULL
5587           && type->complex_type() == NULL)
5588         {
5589           error_at(location, "expected integer, floating, or complex type");
5590           return false;
5591         }
5592       break;
5593
5594     case OPERATOR_MOD:
5595     case OPERATOR_MODEQ:
5596     case OPERATOR_OR:
5597     case OPERATOR_OREQ:
5598     case OPERATOR_AND:
5599     case OPERATOR_ANDEQ:
5600     case OPERATOR_XOR:
5601     case OPERATOR_XOREQ:
5602     case OPERATOR_BITCLEAR:
5603     case OPERATOR_BITCLEAREQ:
5604       if (type->integer_type() == NULL)
5605         {
5606           error_at(location, "expected integer type");
5607           return false;
5608         }
5609       break;
5610
5611     default:
5612       gcc_unreachable();
5613     }
5614
5615   return true;
5616 }
5617
5618 // Check types.
5619
5620 void
5621 Binary_expression::do_check_types(Gogo*)
5622 {
5623   Type* left_type = this->left_->type();
5624   Type* right_type = this->right_->type();
5625   if (left_type->is_error_type() || right_type->is_error_type())
5626     {
5627       this->set_is_error();
5628       return;
5629     }
5630
5631   if (this->op_ == OPERATOR_EQEQ
5632       || this->op_ == OPERATOR_NOTEQ
5633       || this->op_ == OPERATOR_LT
5634       || this->op_ == OPERATOR_LE
5635       || this->op_ == OPERATOR_GT
5636       || this->op_ == OPERATOR_GE)
5637     {
5638       if (!Type::are_assignable(left_type, right_type, NULL)
5639           && !Type::are_assignable(right_type, left_type, NULL))
5640         {
5641           this->report_error(_("incompatible types in binary expression"));
5642           return;
5643         }
5644       if (!Binary_expression::check_operator_type(this->op_, left_type,
5645                                                   this->location())
5646           || !Binary_expression::check_operator_type(this->op_, right_type,
5647                                                      this->location()))
5648         {
5649           this->set_is_error();
5650           return;
5651         }
5652     }
5653   else if (this->op_ != OPERATOR_LSHIFT && this->op_ != OPERATOR_RSHIFT)
5654     {
5655       if (!Type::are_compatible_for_binop(left_type, right_type))
5656         {
5657           this->report_error(_("incompatible types in binary expression"));
5658           return;
5659         }
5660       if (!Binary_expression::check_operator_type(this->op_, left_type,
5661                                                   this->location()))
5662         {
5663           this->set_is_error();
5664           return;
5665         }
5666     }
5667   else
5668     {
5669       if (left_type->integer_type() == NULL)
5670         this->report_error(_("shift of non-integer operand"));
5671
5672       if (!right_type->is_abstract()
5673           && (right_type->integer_type() == NULL
5674               || !right_type->integer_type()->is_unsigned()))
5675         this->report_error(_("shift count not unsigned integer"));
5676       else
5677         {
5678           mpz_t val;
5679           mpz_init(val);
5680           Type* type;
5681           if (this->right_->integer_constant_value(true, val, &type))
5682             {
5683               if (mpz_sgn(val) < 0)
5684                 this->report_error(_("negative shift count"));
5685             }
5686           mpz_clear(val);
5687         }
5688     }
5689 }
5690
5691 // Get a tree for a binary expression.
5692
5693 tree
5694 Binary_expression::do_get_tree(Translate_context* context)
5695 {
5696   tree left = this->left_->get_tree(context);
5697   tree right = this->right_->get_tree(context);
5698
5699   if (left == error_mark_node || right == error_mark_node)
5700     return error_mark_node;
5701
5702   enum tree_code code;
5703   bool use_left_type = true;
5704   bool is_shift_op = false;
5705   switch (this->op_)
5706     {
5707     case OPERATOR_EQEQ:
5708     case OPERATOR_NOTEQ:
5709     case OPERATOR_LT:
5710     case OPERATOR_LE:
5711     case OPERATOR_GT:
5712     case OPERATOR_GE:
5713       return Expression::comparison_tree(context, this->op_,
5714                                          this->left_->type(), left,
5715                                          this->right_->type(), right,
5716                                          this->location());
5717
5718     case OPERATOR_OROR:
5719       code = TRUTH_ORIF_EXPR;
5720       use_left_type = false;
5721       break;
5722     case OPERATOR_ANDAND:
5723       code = TRUTH_ANDIF_EXPR;
5724       use_left_type = false;
5725       break;
5726     case OPERATOR_PLUS:
5727       code = PLUS_EXPR;
5728       break;
5729     case OPERATOR_MINUS:
5730       code = MINUS_EXPR;
5731       break;
5732     case OPERATOR_OR:
5733       code = BIT_IOR_EXPR;
5734       break;
5735     case OPERATOR_XOR:
5736       code = BIT_XOR_EXPR;
5737       break;
5738     case OPERATOR_MULT:
5739       code = MULT_EXPR;
5740       break;
5741     case OPERATOR_DIV:
5742       {
5743         Type *t = this->left_->type();
5744         if (t->float_type() != NULL || t->complex_type() != NULL)
5745           code = RDIV_EXPR;
5746         else
5747           code = TRUNC_DIV_EXPR;
5748       }
5749       break;
5750     case OPERATOR_MOD:
5751       code = TRUNC_MOD_EXPR;
5752       break;
5753     case OPERATOR_LSHIFT:
5754       code = LSHIFT_EXPR;
5755       is_shift_op = true;
5756       break;
5757     case OPERATOR_RSHIFT:
5758       code = RSHIFT_EXPR;
5759       is_shift_op = true;
5760       break;
5761     case OPERATOR_AND:
5762       code = BIT_AND_EXPR;
5763       break;
5764     case OPERATOR_BITCLEAR:
5765       right = fold_build1(BIT_NOT_EXPR, TREE_TYPE(right), right);
5766       code = BIT_AND_EXPR;
5767       break;
5768     default:
5769       gcc_unreachable();
5770     }
5771
5772   tree type = use_left_type ? TREE_TYPE(left) : TREE_TYPE(right);
5773
5774   if (this->left_->type()->is_string_type())
5775     {
5776       gcc_assert(this->op_ == OPERATOR_PLUS);
5777       tree string_type = Type::make_string_type()->get_tree(context->gogo());
5778       static tree string_plus_decl;
5779       return Gogo::call_builtin(&string_plus_decl,
5780                                 this->location(),
5781                                 "__go_string_plus",
5782                                 2,
5783                                 string_type,
5784                                 string_type,
5785                                 left,
5786                                 string_type,
5787                                 right);
5788     }
5789
5790   tree compute_type = excess_precision_type(type);
5791   if (compute_type != NULL_TREE)
5792     {
5793       left = ::convert(compute_type, left);
5794       right = ::convert(compute_type, right);
5795     }
5796
5797   tree eval_saved = NULL_TREE;
5798   if (is_shift_op)
5799     {
5800       if (!DECL_P(left))
5801         left = save_expr(left);
5802       if (!DECL_P(right))
5803         right = save_expr(right);
5804       // Make sure the values are evaluated.
5805       eval_saved = fold_build2_loc(this->location(), COMPOUND_EXPR,
5806                                    void_type_node, left, right);
5807     }
5808
5809   tree ret = fold_build2_loc(this->location(),
5810                              code,
5811                              compute_type != NULL_TREE ? compute_type : type,
5812                              left, right);
5813
5814   if (compute_type != NULL_TREE)
5815     ret = ::convert(type, ret);
5816
5817   // In Go, a shift larger than the size of the type is well-defined.
5818   // This is not true in GENERIC, so we need to insert a conditional.
5819   if (is_shift_op)
5820     {
5821       gcc_assert(INTEGRAL_TYPE_P(TREE_TYPE(left)));
5822       gcc_assert(this->left_->type()->integer_type() != NULL);
5823       int bits = TYPE_PRECISION(TREE_TYPE(left));
5824
5825       tree compare = fold_build2(LT_EXPR, boolean_type_node, right,
5826                                  build_int_cst_type(TREE_TYPE(right), bits));
5827
5828       tree overflow_result = fold_convert_loc(this->location(),
5829                                               TREE_TYPE(left),
5830                                               integer_zero_node);
5831       if (this->op_ == OPERATOR_RSHIFT
5832           && !this->left_->type()->integer_type()->is_unsigned())
5833         {
5834           tree neg = fold_build2_loc(this->location(), LT_EXPR,
5835                                      boolean_type_node, left,
5836                                      fold_convert_loc(this->location(),
5837                                                       TREE_TYPE(left),
5838                                                       integer_zero_node));
5839           tree neg_one = fold_build2_loc(this->location(),
5840                                          MINUS_EXPR, TREE_TYPE(left),
5841                                          fold_convert_loc(this->location(),
5842                                                           TREE_TYPE(left),
5843                                                           integer_zero_node),
5844                                          fold_convert_loc(this->location(),
5845                                                           TREE_TYPE(left),
5846                                                           integer_one_node));
5847           overflow_result = fold_build3_loc(this->location(), COND_EXPR,
5848                                             TREE_TYPE(left), neg, neg_one,
5849                                             overflow_result);
5850         }
5851
5852       ret = fold_build3_loc(this->location(), COND_EXPR, TREE_TYPE(left),
5853                             compare, ret, overflow_result);
5854
5855       ret = fold_build2_loc(this->location(), COMPOUND_EXPR,
5856                             TREE_TYPE(ret), eval_saved, ret);
5857     }
5858
5859   return ret;
5860 }
5861
5862 // Export a binary expression.
5863
5864 void
5865 Binary_expression::do_export(Export* exp) const
5866 {
5867   exp->write_c_string("(");
5868   this->left_->export_expression(exp);
5869   switch (this->op_)
5870     {
5871     case OPERATOR_OROR:
5872       exp->write_c_string(" || ");
5873       break;
5874     case OPERATOR_ANDAND:
5875       exp->write_c_string(" && ");
5876       break;
5877     case OPERATOR_EQEQ:
5878       exp->write_c_string(" == ");
5879       break;
5880     case OPERATOR_NOTEQ:
5881       exp->write_c_string(" != ");
5882       break;
5883     case OPERATOR_LT:
5884       exp->write_c_string(" < ");
5885       break;
5886     case OPERATOR_LE:
5887       exp->write_c_string(" <= ");
5888       break;
5889     case OPERATOR_GT:
5890       exp->write_c_string(" > ");
5891       break;
5892     case OPERATOR_GE:
5893       exp->write_c_string(" >= ");
5894       break;
5895     case OPERATOR_PLUS:
5896       exp->write_c_string(" + ");
5897       break;
5898     case OPERATOR_MINUS:
5899       exp->write_c_string(" - ");
5900       break;
5901     case OPERATOR_OR:
5902       exp->write_c_string(" | ");
5903       break;
5904     case OPERATOR_XOR:
5905       exp->write_c_string(" ^ ");
5906       break;
5907     case OPERATOR_MULT:
5908       exp->write_c_string(" * ");
5909       break;
5910     case OPERATOR_DIV:
5911       exp->write_c_string(" / ");
5912       break;
5913     case OPERATOR_MOD:
5914       exp->write_c_string(" % ");
5915       break;
5916     case OPERATOR_LSHIFT:
5917       exp->write_c_string(" << ");
5918       break;
5919     case OPERATOR_RSHIFT:
5920       exp->write_c_string(" >> ");
5921       break;
5922     case OPERATOR_AND:
5923       exp->write_c_string(" & ");
5924       break;
5925     case OPERATOR_BITCLEAR:
5926       exp->write_c_string(" &^ ");
5927       break;
5928     default:
5929       gcc_unreachable();
5930     }
5931   this->right_->export_expression(exp);
5932   exp->write_c_string(")");
5933 }
5934
5935 // Import a binary expression.
5936
5937 Expression*
5938 Binary_expression::do_import(Import* imp)
5939 {
5940   imp->require_c_string("(");
5941
5942   Expression* left = Expression::import_expression(imp);
5943
5944   Operator op;
5945   if (imp->match_c_string(" || "))
5946     {
5947       op = OPERATOR_OROR;
5948       imp->advance(4);
5949     }
5950   else if (imp->match_c_string(" && "))
5951     {
5952       op = OPERATOR_ANDAND;
5953       imp->advance(4);
5954     }
5955   else if (imp->match_c_string(" == "))
5956     {
5957       op = OPERATOR_EQEQ;
5958       imp->advance(4);
5959     }
5960   else if (imp->match_c_string(" != "))
5961     {
5962       op = OPERATOR_NOTEQ;
5963       imp->advance(4);
5964     }
5965   else if (imp->match_c_string(" < "))
5966     {
5967       op = OPERATOR_LT;
5968       imp->advance(3);
5969     }
5970   else if (imp->match_c_string(" <= "))
5971     {
5972       op = OPERATOR_LE;
5973       imp->advance(4);
5974     }
5975   else if (imp->match_c_string(" > "))
5976     {
5977       op = OPERATOR_GT;
5978       imp->advance(3);
5979     }
5980   else if (imp->match_c_string(" >= "))
5981     {
5982       op = OPERATOR_GE;
5983       imp->advance(4);
5984     }
5985   else if (imp->match_c_string(" + "))
5986     {
5987       op = OPERATOR_PLUS;
5988       imp->advance(3);
5989     }
5990   else if (imp->match_c_string(" - "))
5991     {
5992       op = OPERATOR_MINUS;
5993       imp->advance(3);
5994     }
5995   else if (imp->match_c_string(" | "))
5996     {
5997       op = OPERATOR_OR;
5998       imp->advance(3);
5999     }
6000   else if (imp->match_c_string(" ^ "))
6001     {
6002       op = OPERATOR_XOR;
6003       imp->advance(3);
6004     }
6005   else if (imp->match_c_string(" * "))
6006     {
6007       op = OPERATOR_MULT;
6008       imp->advance(3);
6009     }
6010   else if (imp->match_c_string(" / "))
6011     {
6012       op = OPERATOR_DIV;
6013       imp->advance(3);
6014     }
6015   else if (imp->match_c_string(" % "))
6016     {
6017       op = OPERATOR_MOD;
6018       imp->advance(3);
6019     }
6020   else if (imp->match_c_string(" << "))
6021     {
6022       op = OPERATOR_LSHIFT;
6023       imp->advance(4);
6024     }
6025   else if (imp->match_c_string(" >> "))
6026     {
6027       op = OPERATOR_RSHIFT;
6028       imp->advance(4);
6029     }
6030   else if (imp->match_c_string(" & "))
6031     {
6032       op = OPERATOR_AND;
6033       imp->advance(3);
6034     }
6035   else if (imp->match_c_string(" &^ "))
6036     {
6037       op = OPERATOR_BITCLEAR;
6038       imp->advance(4);
6039     }
6040   else
6041     {
6042       error_at(imp->location(), "unrecognized binary operator");
6043       return Expression::make_error(imp->location());
6044     }
6045
6046   Expression* right = Expression::import_expression(imp);
6047
6048   imp->require_c_string(")");
6049
6050   return Expression::make_binary(op, left, right, imp->location());
6051 }
6052
6053 // Make a binary expression.
6054
6055 Expression*
6056 Expression::make_binary(Operator op, Expression* left, Expression* right,
6057                         source_location location)
6058 {
6059   return new Binary_expression(op, left, right, location);
6060 }
6061
6062 // Implement a comparison.
6063
6064 tree
6065 Expression::comparison_tree(Translate_context* context, Operator op,
6066                             Type* left_type, tree left_tree,
6067                             Type* right_type, tree right_tree,
6068                             source_location location)
6069 {
6070   enum tree_code code;
6071   switch (op)
6072     {
6073     case OPERATOR_EQEQ:
6074       code = EQ_EXPR;
6075       break;
6076     case OPERATOR_NOTEQ:
6077       code = NE_EXPR;
6078       break;
6079     case OPERATOR_LT:
6080       code = LT_EXPR;
6081       break;
6082     case OPERATOR_LE:
6083       code = LE_EXPR;
6084       break;
6085     case OPERATOR_GT:
6086       code = GT_EXPR;
6087       break;
6088     case OPERATOR_GE:
6089       code = GE_EXPR;
6090       break;
6091     default:
6092       gcc_unreachable();
6093     }
6094
6095   if (left_type->is_string_type() && right_type->is_string_type())
6096     {
6097       tree string_type = Type::make_string_type()->get_tree(context->gogo());
6098       static tree string_compare_decl;
6099       left_tree = Gogo::call_builtin(&string_compare_decl,
6100                                      location,
6101                                      "__go_strcmp",
6102                                      2,
6103                                      integer_type_node,
6104                                      string_type,
6105                                      left_tree,
6106                                      string_type,
6107                                      right_tree);
6108       right_tree = build_int_cst_type(integer_type_node, 0);
6109     }
6110   else if ((left_type->interface_type() != NULL
6111             && right_type->interface_type() == NULL
6112             && !right_type->is_nil_type())
6113            || (left_type->interface_type() == NULL
6114                && !left_type->is_nil_type()
6115                && right_type->interface_type() != NULL))
6116     {
6117       // Comparing an interface value to a non-interface value.
6118       if (left_type->interface_type() == NULL)
6119         {
6120           std::swap(left_type, right_type);
6121           std::swap(left_tree, right_tree);
6122         }
6123
6124       // The right operand is not an interface.  We need to take its
6125       // address if it is not a pointer.
6126       tree make_tmp;
6127       tree arg;
6128       if (right_type->points_to() != NULL)
6129         {
6130           make_tmp = NULL_TREE;
6131           arg = right_tree;
6132         }
6133       else if (TREE_ADDRESSABLE(TREE_TYPE(right_tree)) || DECL_P(right_tree))
6134         {
6135           make_tmp = NULL_TREE;
6136           arg = build_fold_addr_expr_loc(location, right_tree);
6137           if (DECL_P(right_tree))
6138             TREE_ADDRESSABLE(right_tree) = 1;
6139         }
6140       else
6141         {
6142           tree tmp = create_tmp_var(TREE_TYPE(right_tree),
6143                                     get_name(right_tree));
6144           DECL_IGNORED_P(tmp) = 0;
6145           DECL_INITIAL(tmp) = right_tree;
6146           TREE_ADDRESSABLE(tmp) = 1;
6147           make_tmp = build1(DECL_EXPR, void_type_node, tmp);
6148           SET_EXPR_LOCATION(make_tmp, location);
6149           arg = build_fold_addr_expr_loc(location, tmp);
6150         }
6151       arg = fold_convert_loc(location, ptr_type_node, arg);
6152
6153       tree descriptor = right_type->type_descriptor_pointer(context->gogo());
6154
6155       if (left_type->interface_type()->is_empty())
6156         {
6157           static tree empty_interface_value_compare_decl;
6158           left_tree = Gogo::call_builtin(&empty_interface_value_compare_decl,
6159                                          location,
6160                                          "__go_empty_interface_value_compare",
6161                                          3,
6162                                          integer_type_node,
6163                                          TREE_TYPE(left_tree),
6164                                          left_tree,
6165                                          TREE_TYPE(descriptor),
6166                                          descriptor,
6167                                          ptr_type_node,
6168                                          arg);
6169           if (left_tree == error_mark_node)
6170             return error_mark_node;
6171           // This can panic if the type is not comparable.
6172           TREE_NOTHROW(empty_interface_value_compare_decl) = 0;
6173         }
6174       else
6175         {
6176           static tree interface_value_compare_decl;
6177           left_tree = Gogo::call_builtin(&interface_value_compare_decl,
6178                                          location,
6179                                          "__go_interface_value_compare",
6180                                          3,
6181                                          integer_type_node,
6182                                          TREE_TYPE(left_tree),
6183                                          left_tree,
6184                                          TREE_TYPE(descriptor),
6185                                          descriptor,
6186                                          ptr_type_node,
6187                                          arg);
6188           if (left_tree == error_mark_node)
6189             return error_mark_node;
6190           // This can panic if the type is not comparable.
6191           TREE_NOTHROW(interface_value_compare_decl) = 0;
6192         }
6193       right_tree = build_int_cst_type(integer_type_node, 0);
6194
6195       if (make_tmp != NULL_TREE)
6196         left_tree = build2(COMPOUND_EXPR, TREE_TYPE(left_tree), make_tmp,
6197                            left_tree);
6198     }
6199   else if (left_type->interface_type() != NULL
6200            && right_type->interface_type() != NULL)
6201     {
6202       if (left_type->interface_type()->is_empty())
6203         {
6204           gcc_assert(right_type->interface_type()->is_empty());
6205           static tree empty_interface_compare_decl;
6206           left_tree = Gogo::call_builtin(&empty_interface_compare_decl,
6207                                          location,
6208                                          "__go_empty_interface_compare",
6209                                          2,
6210                                          integer_type_node,
6211                                          TREE_TYPE(left_tree),
6212                                          left_tree,
6213                                          TREE_TYPE(right_tree),
6214                                          right_tree);
6215           if (left_tree == error_mark_node)
6216             return error_mark_node;
6217           // This can panic if the type is uncomparable.
6218           TREE_NOTHROW(empty_interface_compare_decl) = 0;
6219         }
6220       else
6221         {
6222           gcc_assert(!right_type->interface_type()->is_empty());
6223           static tree interface_compare_decl;
6224           left_tree = Gogo::call_builtin(&interface_compare_decl,
6225                                          location,
6226                                          "__go_interface_compare",
6227                                          2,
6228                                          integer_type_node,
6229                                          TREE_TYPE(left_tree),
6230                                          left_tree,
6231                                          TREE_TYPE(right_tree),
6232                                          right_tree);
6233           if (left_tree == error_mark_node)
6234             return error_mark_node;
6235           // This can panic if the type is uncomparable.
6236           TREE_NOTHROW(interface_compare_decl) = 0;
6237         }
6238       right_tree = build_int_cst_type(integer_type_node, 0);
6239     }
6240
6241   if (left_type->is_nil_type()
6242       && (op == OPERATOR_EQEQ || op == OPERATOR_NOTEQ))
6243     {
6244       std::swap(left_type, right_type);
6245       std::swap(left_tree, right_tree);
6246     }
6247
6248   if (right_type->is_nil_type())
6249     {
6250       if (left_type->array_type() != NULL
6251           && left_type->array_type()->length() == NULL)
6252         {
6253           Array_type* at = left_type->array_type();
6254           left_tree = at->value_pointer_tree(context->gogo(), left_tree);
6255           right_tree = fold_convert(TREE_TYPE(left_tree), null_pointer_node);
6256         }
6257       else if (left_type->interface_type() != NULL)
6258         {
6259           // An interface is nil if the first field is nil.
6260           tree left_type_tree = TREE_TYPE(left_tree);
6261           gcc_assert(TREE_CODE(left_type_tree) == RECORD_TYPE);
6262           tree field = TYPE_FIELDS(left_type_tree);
6263           left_tree = build3(COMPONENT_REF, TREE_TYPE(field), left_tree,
6264                              field, NULL_TREE);
6265           right_tree = fold_convert(TREE_TYPE(left_tree), null_pointer_node);
6266         }
6267       else
6268         {
6269           gcc_assert(POINTER_TYPE_P(TREE_TYPE(left_tree)));
6270           right_tree = fold_convert(TREE_TYPE(left_tree), null_pointer_node);
6271         }
6272     }
6273
6274   if (left_tree == error_mark_node || right_tree == error_mark_node)
6275     return error_mark_node;
6276
6277   tree ret = fold_build2(code, boolean_type_node, left_tree, right_tree);
6278   if (CAN_HAVE_LOCATION_P(ret))
6279     SET_EXPR_LOCATION(ret, location);
6280   return ret;
6281 }
6282
6283 // Class Bound_method_expression.
6284
6285 // Traversal.
6286
6287 int
6288 Bound_method_expression::do_traverse(Traverse* traverse)
6289 {
6290   if (Expression::traverse(&this->expr_, traverse) == TRAVERSE_EXIT)
6291     return TRAVERSE_EXIT;
6292   return Expression::traverse(&this->method_, traverse);
6293 }
6294
6295 // Return the type of a bound method expression.  The type of this
6296 // object is really the type of the method with no receiver.  We
6297 // should be able to get away with just returning the type of the
6298 // method.
6299
6300 Type*
6301 Bound_method_expression::do_type()
6302 {
6303   return this->method_->type();
6304 }
6305
6306 // Determine the types of a method expression.
6307
6308 void
6309 Bound_method_expression::do_determine_type(const Type_context*)
6310 {
6311   this->method_->determine_type_no_context();
6312   Type* mtype = this->method_->type();
6313   Function_type* fntype = mtype == NULL ? NULL : mtype->function_type();
6314   if (fntype == NULL || !fntype->is_method())
6315     this->expr_->determine_type_no_context();
6316   else
6317     {
6318       Type_context subcontext(fntype->receiver()->type(), false);
6319       this->expr_->determine_type(&subcontext);
6320     }
6321 }
6322
6323 // Check the types of a method expression.
6324
6325 void
6326 Bound_method_expression::do_check_types(Gogo*)
6327 {
6328   Type* type = this->method_->type()->deref();
6329   if (type == NULL
6330       || type->function_type() == NULL
6331       || !type->function_type()->is_method())
6332     this->report_error(_("object is not a method"));
6333   else
6334     {
6335       Type* rtype = type->function_type()->receiver()->type()->deref();
6336       Type* etype = (this->expr_type_ != NULL
6337                      ? this->expr_type_
6338                      : this->expr_->type());
6339       etype = etype->deref();
6340       if (!Type::are_identical(rtype, etype, true, NULL))
6341         this->report_error(_("method type does not match object type"));
6342     }
6343 }
6344
6345 // Get the tree for a method expression.  There is no standard tree
6346 // representation for this.  The only places it may currently be used
6347 // are in a Call_expression or a Go_statement, which will take it
6348 // apart directly.  So this has nothing to do at present.
6349
6350 tree
6351 Bound_method_expression::do_get_tree(Translate_context*)
6352 {
6353   gcc_unreachable();
6354 }
6355
6356 // Make a method expression.
6357
6358 Bound_method_expression*
6359 Expression::make_bound_method(Expression* expr, Expression* method,
6360                               source_location location)
6361 {
6362   return new Bound_method_expression(expr, method, location);
6363 }
6364
6365 // Class Builtin_call_expression.  This is used for a call to a
6366 // builtin function.
6367
6368 class Builtin_call_expression : public Call_expression
6369 {
6370  public:
6371   Builtin_call_expression(Gogo* gogo, Expression* fn, Expression_list* args,
6372                           bool is_varargs, source_location location);
6373
6374  protected:
6375   // This overrides Call_expression::do_lower.
6376   Expression*
6377   do_lower(Gogo*, Named_object*, int);
6378
6379   bool
6380   do_is_constant() const;
6381
6382   bool
6383   do_integer_constant_value(bool, mpz_t, Type**) const;
6384
6385   bool
6386   do_float_constant_value(mpfr_t, Type**) const;
6387
6388   bool
6389   do_complex_constant_value(mpfr_t, mpfr_t, Type**) const;
6390
6391   Type*
6392   do_type();
6393
6394   void
6395   do_determine_type(const Type_context*);
6396
6397   void
6398   do_check_types(Gogo*);
6399
6400   Expression*
6401   do_copy()
6402   {
6403     return new Builtin_call_expression(this->gogo_, this->fn()->copy(),
6404                                        this->args()->copy(),
6405                                        this->is_varargs(),
6406                                        this->location());
6407   }
6408
6409   tree
6410   do_get_tree(Translate_context*);
6411
6412   void
6413   do_export(Export*) const;
6414
6415   virtual bool
6416   do_is_recover_call() const;
6417
6418   virtual void
6419   do_set_recover_arg(Expression*);
6420
6421  private:
6422   // The builtin functions.
6423   enum Builtin_function_code
6424     {
6425       BUILTIN_INVALID,
6426
6427       // Predeclared builtin functions.
6428       BUILTIN_APPEND,
6429       BUILTIN_CAP,
6430       BUILTIN_CLOSE,
6431       BUILTIN_CLOSED,
6432       BUILTIN_CMPLX,
6433       BUILTIN_COPY,
6434       BUILTIN_IMAG,
6435       BUILTIN_LEN,
6436       BUILTIN_MAKE,
6437       BUILTIN_NEW,
6438       BUILTIN_PANIC,
6439       BUILTIN_PRINT,
6440       BUILTIN_PRINTLN,
6441       BUILTIN_REAL,
6442       BUILTIN_RECOVER,
6443
6444       // Builtin functions from the unsafe package.
6445       BUILTIN_ALIGNOF,
6446       BUILTIN_OFFSETOF,
6447       BUILTIN_SIZEOF
6448     };
6449
6450   Expression*
6451   one_arg() const;
6452
6453   bool
6454   check_one_arg();
6455
6456   static Type*
6457   real_imag_type(Type*);
6458
6459   static Type*
6460   cmplx_type(Type*);
6461
6462   // A pointer back to the general IR structure.  This avoids a global
6463   // variable, or passing it around everywhere.
6464   Gogo* gogo_;
6465   // The builtin function being called.
6466   Builtin_function_code code_;
6467   // Used to stop endless loops when the length of an array uses len
6468   // or cap of the array itself.
6469   mutable bool seen_;
6470 };
6471
6472 Builtin_call_expression::Builtin_call_expression(Gogo* gogo,
6473                                                  Expression* fn,
6474                                                  Expression_list* args,
6475                                                  bool is_varargs,
6476                                                  source_location location)
6477   : Call_expression(fn, args, is_varargs, location),
6478     gogo_(gogo), code_(BUILTIN_INVALID), seen_(false)
6479 {
6480   Func_expression* fnexp = this->fn()->func_expression();
6481   gcc_assert(fnexp != NULL);
6482   const std::string& name(fnexp->named_object()->name());
6483   if (name == "append")
6484     this->code_ = BUILTIN_APPEND;
6485   else if (name == "cap")
6486     this->code_ = BUILTIN_CAP;
6487   else if (name == "close")
6488     this->code_ = BUILTIN_CLOSE;
6489   else if (name == "closed")
6490     this->code_ = BUILTIN_CLOSED;
6491   else if (name == "cmplx")
6492     this->code_ = BUILTIN_CMPLX;
6493   else if (name == "copy")
6494     this->code_ = BUILTIN_COPY;
6495   else if (name == "imag")
6496     this->code_ = BUILTIN_IMAG;
6497   else if (name == "len")
6498     this->code_ = BUILTIN_LEN;
6499   else if (name == "make")
6500     this->code_ = BUILTIN_MAKE;
6501   else if (name == "new")
6502     this->code_ = BUILTIN_NEW;
6503   else if (name == "panic")
6504     this->code_ = BUILTIN_PANIC;
6505   else if (name == "print")
6506     this->code_ = BUILTIN_PRINT;
6507   else if (name == "println")
6508     this->code_ = BUILTIN_PRINTLN;
6509   else if (name == "real")
6510     this->code_ = BUILTIN_REAL;
6511   else if (name == "recover")
6512     this->code_ = BUILTIN_RECOVER;
6513   else if (name == "Alignof")
6514     this->code_ = BUILTIN_ALIGNOF;
6515   else if (name == "Offsetof")
6516     this->code_ = BUILTIN_OFFSETOF;
6517   else if (name == "Sizeof")
6518     this->code_ = BUILTIN_SIZEOF;
6519   else
6520     gcc_unreachable();
6521 }
6522
6523 // Return whether this is a call to recover.  This is a virtual
6524 // function called from the parent class.
6525
6526 bool
6527 Builtin_call_expression::do_is_recover_call() const
6528 {
6529   if (this->classification() == EXPRESSION_ERROR)
6530     return false;
6531   return this->code_ == BUILTIN_RECOVER;
6532 }
6533
6534 // Set the argument for a call to recover.
6535
6536 void
6537 Builtin_call_expression::do_set_recover_arg(Expression* arg)
6538 {
6539   const Expression_list* args = this->args();
6540   gcc_assert(args == NULL || args->empty());
6541   Expression_list* new_args = new Expression_list();
6542   new_args->push_back(arg);
6543   this->set_args(new_args);
6544 }
6545
6546 // A traversal class which looks for a call expression.
6547
6548 class Find_call_expression : public Traverse
6549 {
6550  public:
6551   Find_call_expression()
6552     : Traverse(traverse_expressions),
6553       found_(false)
6554   { }
6555
6556   int
6557   expression(Expression**);
6558
6559   bool
6560   found()
6561   { return this->found_; }
6562
6563  private:
6564   bool found_;
6565 };
6566
6567 int
6568 Find_call_expression::expression(Expression** pexpr)
6569 {
6570   if ((*pexpr)->call_expression() != NULL)
6571     {
6572       this->found_ = true;
6573       return TRAVERSE_EXIT;
6574     }
6575   return TRAVERSE_CONTINUE;
6576 }
6577
6578 // Lower a builtin call expression.  This turns new and make into
6579 // specific expressions.  We also convert to a constant if we can.
6580
6581 Expression*
6582 Builtin_call_expression::do_lower(Gogo* gogo, Named_object* function, int)
6583 {
6584   if (this->code_ == BUILTIN_NEW)
6585     {
6586       const Expression_list* args = this->args();
6587       if (args == NULL || args->size() < 1)
6588         this->report_error(_("not enough arguments"));
6589       else if (args->size() > 1)
6590         this->report_error(_("too many arguments"));
6591       else
6592         {
6593           Expression* arg = args->front();
6594           if (!arg->is_type_expression())
6595             {
6596               error_at(arg->location(), "expected type");
6597               this->set_is_error();
6598             }
6599           else
6600             return Expression::make_allocation(arg->type(), this->location());
6601         }
6602     }
6603   else if (this->code_ == BUILTIN_MAKE)
6604     {
6605       const Expression_list* args = this->args();
6606       if (args == NULL || args->size() < 1)
6607         this->report_error(_("not enough arguments"));
6608       else
6609         {
6610           Expression* arg = args->front();
6611           if (!arg->is_type_expression())
6612             {
6613               error_at(arg->location(), "expected type");
6614               this->set_is_error();
6615             }
6616           else
6617             {
6618               Expression_list* newargs;
6619               if (args->size() == 1)
6620                 newargs = NULL;
6621               else
6622                 {
6623                   newargs = new Expression_list();
6624                   Expression_list::const_iterator p = args->begin();
6625                   ++p;
6626                   for (; p != args->end(); ++p)
6627                     newargs->push_back(*p);
6628                 }
6629               return Expression::make_make(arg->type(), newargs,
6630                                            this->location());
6631             }
6632         }
6633     }
6634   else if (this->is_constant())
6635     {
6636       // We can only lower len and cap if there are no function calls
6637       // in the arguments.  Otherwise we have to make the call.
6638       if (this->code_ == BUILTIN_LEN || this->code_ == BUILTIN_CAP)
6639         {
6640           Expression* arg = this->one_arg();
6641           if (!arg->is_constant())
6642             {
6643               Find_call_expression find_call;
6644               Expression::traverse(&arg, &find_call);
6645               if (find_call.found())
6646                 return this;
6647             }
6648         }
6649
6650       mpz_t ival;
6651       mpz_init(ival);
6652       Type* type;
6653       if (this->integer_constant_value(true, ival, &type))
6654         {
6655           Expression* ret = Expression::make_integer(&ival, type,
6656                                                      this->location());
6657           mpz_clear(ival);
6658           return ret;
6659         }
6660       mpz_clear(ival);
6661
6662       mpfr_t rval;
6663       mpfr_init(rval);
6664       if (this->float_constant_value(rval, &type))
6665         {
6666           Expression* ret = Expression::make_float(&rval, type,
6667                                                    this->location());
6668           mpfr_clear(rval);
6669           return ret;
6670         }
6671
6672       mpfr_t imag;
6673       mpfr_init(imag);
6674       if (this->complex_constant_value(rval, imag, &type))
6675         {
6676           Expression* ret = Expression::make_complex(&rval, &imag, type,
6677                                                      this->location());
6678           mpfr_clear(rval);
6679           mpfr_clear(imag);
6680           return ret;
6681         }
6682       mpfr_clear(rval);
6683       mpfr_clear(imag);
6684     }
6685   else if (this->code_ == BUILTIN_RECOVER)
6686     {
6687       if (function != NULL)
6688         function->func_value()->set_calls_recover();
6689       else
6690         {
6691           // Calling recover outside of a function always returns the
6692           // nil empty interface.
6693           Type* eface = Type::make_interface_type(NULL, this->location());
6694           return Expression::make_cast(eface,
6695                                        Expression::make_nil(this->location()),
6696                                        this->location());
6697         }
6698     }
6699   else if (this->code_ == BUILTIN_APPEND)
6700     {
6701       // Lower the varargs.
6702       const Expression_list* args = this->args();
6703       if (args == NULL || args->empty())
6704         return this;
6705       Type* slice_type = args->front()->type();
6706       if (!slice_type->is_open_array_type())
6707         {
6708           error_at(args->front()->location(), "argument 1 must be a slice");
6709           this->set_is_error();
6710           return this;
6711         }
6712       return this->lower_varargs(gogo, function, slice_type, 2);
6713     }
6714
6715   return this;
6716 }
6717
6718 // Return the type of the real or imag functions, given the type of
6719 // the argument.  We need to map complex to float, complex64 to
6720 // float32, and complex128 to float64, so it has to be done by name.
6721 // This returns NULL if it can't figure out the type.
6722
6723 Type*
6724 Builtin_call_expression::real_imag_type(Type* arg_type)
6725 {
6726   if (arg_type == NULL || arg_type->is_abstract())
6727     return NULL;
6728   Named_type* nt = arg_type->named_type();
6729   if (nt == NULL)
6730     return NULL;
6731   while (nt->real_type()->named_type() != NULL)
6732     nt = nt->real_type()->named_type();
6733   if (nt->name() == "complex")
6734     return Type::lookup_float_type("float");
6735   else if (nt->name() == "complex64")
6736     return Type::lookup_float_type("float32");
6737   else if (nt->name() == "complex128")
6738     return Type::lookup_float_type("float64");
6739   else
6740     return NULL;
6741 }
6742
6743 // Return the type of the cmplx function, given the type of one of the
6744 // argments.  Like real_imag_type, we have to map by name.
6745
6746 Type*
6747 Builtin_call_expression::cmplx_type(Type* arg_type)
6748 {
6749   if (arg_type == NULL || arg_type->is_abstract())
6750     return NULL;
6751   Named_type* nt = arg_type->named_type();
6752   if (nt == NULL)
6753     return NULL;
6754   while (nt->real_type()->named_type() != NULL)
6755     nt = nt->real_type()->named_type();
6756   if (nt->name() == "float")
6757     return Type::lookup_complex_type("complex");
6758   else if (nt->name() == "float32")
6759     return Type::lookup_complex_type("complex64");
6760   else if (nt->name() == "float64")
6761     return Type::lookup_complex_type("complex128");
6762   else
6763     return NULL;
6764 }
6765
6766 // Return a single argument, or NULL if there isn't one.
6767
6768 Expression*
6769 Builtin_call_expression::one_arg() const
6770 {
6771   const Expression_list* args = this->args();
6772   if (args->size() != 1)
6773     return NULL;
6774   return args->front();
6775 }
6776
6777 // Return whether this is constant: len of a string, or len or cap of
6778 // a fixed array, or unsafe.Sizeof, unsafe.Offsetof, unsafe.Alignof.
6779
6780 bool
6781 Builtin_call_expression::do_is_constant() const
6782 {
6783   switch (this->code_)
6784     {
6785     case BUILTIN_LEN:
6786     case BUILTIN_CAP:
6787       {
6788         if (this->seen_)
6789           return false;
6790
6791         Expression* arg = this->one_arg();
6792         if (arg == NULL)
6793           return false;
6794         Type* arg_type = arg->type();
6795
6796         if (arg_type->points_to() != NULL
6797             && arg_type->points_to()->array_type() != NULL
6798             && !arg_type->points_to()->is_open_array_type())
6799           arg_type = arg_type->points_to();
6800
6801         if (arg_type->array_type() != NULL
6802             && arg_type->array_type()->length() != NULL)
6803           return true;
6804
6805         if (this->code_ == BUILTIN_LEN && arg_type->is_string_type())
6806           {
6807             this->seen_ = true;
6808             bool ret = arg->is_constant();
6809             this->seen_ = false;
6810             return ret;
6811           }
6812       }
6813       break;
6814
6815     case BUILTIN_SIZEOF:
6816     case BUILTIN_ALIGNOF:
6817       return this->one_arg() != NULL;
6818
6819     case BUILTIN_OFFSETOF:
6820       {
6821         Expression* arg = this->one_arg();
6822         if (arg == NULL)
6823           return false;
6824         return arg->field_reference_expression() != NULL;
6825       }
6826
6827     case BUILTIN_CMPLX:
6828       {
6829         const Expression_list* args = this->args();
6830         if (args != NULL && args->size() == 2)
6831           return args->front()->is_constant() && args->back()->is_constant();
6832       }
6833       break;
6834
6835     case BUILTIN_REAL:
6836     case BUILTIN_IMAG:
6837       {
6838         Expression* arg = this->one_arg();
6839         return arg != NULL && arg->is_constant();
6840       }
6841
6842     default:
6843       break;
6844     }
6845
6846   return false;
6847 }
6848
6849 // Return an integer constant value if possible.
6850
6851 bool
6852 Builtin_call_expression::do_integer_constant_value(bool iota_is_constant,
6853                                                    mpz_t val,
6854                                                    Type** ptype) const
6855 {
6856   if (this->code_ == BUILTIN_LEN
6857       || this->code_ == BUILTIN_CAP)
6858     {
6859       Expression* arg = this->one_arg();
6860       if (arg == NULL)
6861         return false;
6862       Type* arg_type = arg->type();
6863
6864       if (this->code_ == BUILTIN_LEN && arg_type->is_string_type())
6865         {
6866           std::string sval;
6867           if (arg->string_constant_value(&sval))
6868             {
6869               mpz_set_ui(val, sval.length());
6870               *ptype = Type::lookup_integer_type("int");
6871               return true;
6872             }
6873         }
6874
6875       if (arg_type->points_to() != NULL
6876           && arg_type->points_to()->array_type() != NULL
6877           && !arg_type->points_to()->is_open_array_type())
6878         arg_type = arg_type->points_to();
6879
6880       if (arg_type->array_type() != NULL
6881           && arg_type->array_type()->length() != NULL)
6882         {
6883           if (this->seen_)
6884             return false;
6885           Expression* e = arg_type->array_type()->length();
6886           this->seen_ = true;
6887           bool r = e->integer_constant_value(iota_is_constant, val, ptype);
6888           this->seen_ = false;
6889           if (r)
6890             {
6891               *ptype = Type::lookup_integer_type("int");
6892               return true;
6893             }
6894         }
6895     }
6896   else if (this->code_ == BUILTIN_SIZEOF
6897            || this->code_ == BUILTIN_ALIGNOF)
6898     {
6899       Expression* arg = this->one_arg();
6900       if (arg == NULL)
6901         return false;
6902       Type* arg_type = arg->type();
6903       if (arg_type->is_error_type() || arg_type->is_undefined())
6904         return false;
6905       if (arg_type->is_abstract())
6906         return false;
6907       tree arg_type_tree = arg_type->get_tree(this->gogo_);
6908       unsigned long val_long;
6909       if (this->code_ == BUILTIN_SIZEOF)
6910         {
6911           tree type_size = TYPE_SIZE_UNIT(arg_type_tree);
6912           gcc_assert(TREE_CODE(type_size) == INTEGER_CST);
6913           if (TREE_INT_CST_HIGH(type_size) != 0)
6914             return false;
6915           unsigned HOST_WIDE_INT val_wide = TREE_INT_CST_LOW(type_size);
6916           val_long = static_cast<unsigned long>(val_wide);
6917           if (val_long != val_wide)
6918             return false;
6919         }
6920       else if (this->code_ == BUILTIN_ALIGNOF)
6921         {
6922           if (arg->field_reference_expression() == NULL)
6923             val_long = go_type_alignment(arg_type_tree);
6924           else
6925             {
6926               // Calling unsafe.Alignof(s.f) returns the alignment of
6927               // the type of f when it is used as a field in a struct.
6928               val_long = go_field_alignment(arg_type_tree);
6929             }
6930         }
6931       else
6932         gcc_unreachable();
6933       mpz_set_ui(val, val_long);
6934       *ptype = NULL;
6935       return true;
6936     }
6937   else if (this->code_ == BUILTIN_OFFSETOF)
6938     {
6939       Expression* arg = this->one_arg();
6940       if (arg == NULL)
6941         return false;
6942       Field_reference_expression* farg = arg->field_reference_expression();
6943       if (farg == NULL)
6944         return false;
6945       Expression* struct_expr = farg->expr();
6946       Type* st = struct_expr->type();
6947       if (st->struct_type() == NULL)
6948         return false;
6949       tree struct_tree = st->get_tree(this->gogo_);
6950       gcc_assert(TREE_CODE(struct_tree) == RECORD_TYPE);
6951       tree field = TYPE_FIELDS(struct_tree);
6952       for (unsigned int index = farg->field_index(); index > 0; --index)
6953         {
6954           field = DECL_CHAIN(field);
6955           gcc_assert(field != NULL_TREE);
6956         }
6957       HOST_WIDE_INT offset_wide = int_byte_position (field);
6958       if (offset_wide < 0)
6959         return false;
6960       unsigned long offset_long = static_cast<unsigned long>(offset_wide);
6961       if (offset_long != static_cast<unsigned HOST_WIDE_INT>(offset_wide))
6962         return false;
6963       mpz_set_ui(val, offset_long);
6964       return true;
6965     }
6966   return false;
6967 }
6968
6969 // Return a floating point constant value if possible.
6970
6971 bool
6972 Builtin_call_expression::do_float_constant_value(mpfr_t val,
6973                                                  Type** ptype) const
6974 {
6975   if (this->code_ == BUILTIN_REAL || this->code_ == BUILTIN_IMAG)
6976     {
6977       Expression* arg = this->one_arg();
6978       if (arg == NULL)
6979         return false;
6980
6981       mpfr_t real;
6982       mpfr_t imag;
6983       mpfr_init(real);
6984       mpfr_init(imag);
6985
6986       bool ret = false;
6987       Type* type;
6988       if (arg->complex_constant_value(real, imag, &type))
6989         {
6990           if (this->code_ == BUILTIN_REAL)
6991             mpfr_set(val, real, GMP_RNDN);
6992           else
6993             mpfr_set(val, imag, GMP_RNDN);
6994           *ptype = Builtin_call_expression::real_imag_type(type);
6995           ret = true;
6996         }
6997
6998       mpfr_clear(real);
6999       mpfr_clear(imag);
7000       return ret;
7001     }
7002
7003   return false;
7004 }
7005
7006 // Return a complex constant value if possible.
7007
7008 bool
7009 Builtin_call_expression::do_complex_constant_value(mpfr_t real, mpfr_t imag,
7010                                                    Type** ptype) const
7011 {
7012   if (this->code_ == BUILTIN_CMPLX)
7013     {
7014       const Expression_list* args = this->args();
7015       if (args == NULL || args->size() != 2)
7016         return false;
7017
7018       mpfr_t r;
7019       mpfr_init(r);
7020       Type* rtype;
7021       if (!args->front()->float_constant_value(r, &rtype))
7022         {
7023           mpfr_clear(r);
7024           return false;
7025         }
7026
7027       mpfr_t i;
7028       mpfr_init(i);
7029
7030       bool ret = false;
7031       Type* itype;
7032       if (args->back()->float_constant_value(i, &itype)
7033           && Type::are_identical(rtype, itype, false, NULL))
7034         {
7035           mpfr_set(real, r, GMP_RNDN);
7036           mpfr_set(imag, i, GMP_RNDN);
7037           *ptype = Builtin_call_expression::cmplx_type(rtype);
7038           ret = true;
7039         }
7040
7041       mpfr_clear(r);
7042       mpfr_clear(i);
7043
7044       return ret;
7045     }
7046
7047   return false;
7048 }
7049
7050 // Return the type.
7051
7052 Type*
7053 Builtin_call_expression::do_type()
7054 {
7055   switch (this->code_)
7056     {
7057     case BUILTIN_INVALID:
7058     default:
7059       gcc_unreachable();
7060
7061     case BUILTIN_NEW:
7062     case BUILTIN_MAKE:
7063       {
7064         const Expression_list* args = this->args();
7065         if (args == NULL || args->empty())
7066           return Type::make_error_type();
7067         return Type::make_pointer_type(args->front()->type());
7068       }
7069
7070     case BUILTIN_CAP:
7071     case BUILTIN_COPY:
7072     case BUILTIN_LEN:
7073     case BUILTIN_ALIGNOF:
7074     case BUILTIN_OFFSETOF:
7075     case BUILTIN_SIZEOF:
7076       return Type::lookup_integer_type("int");
7077
7078     case BUILTIN_CLOSE:
7079     case BUILTIN_PANIC:
7080     case BUILTIN_PRINT:
7081     case BUILTIN_PRINTLN:
7082       return Type::make_void_type();
7083
7084     case BUILTIN_CLOSED:
7085       return Type::lookup_bool_type();
7086
7087     case BUILTIN_RECOVER:
7088       return Type::make_interface_type(NULL, BUILTINS_LOCATION);
7089
7090     case BUILTIN_APPEND:
7091       {
7092         const Expression_list* args = this->args();
7093         if (args == NULL || args->empty())
7094           return Type::make_error_type();
7095         return args->front()->type();
7096       }
7097
7098     case BUILTIN_REAL:
7099     case BUILTIN_IMAG:
7100       {
7101         Expression* arg = this->one_arg();
7102         if (arg == NULL)
7103           return Type::make_error_type();
7104         Type* t = arg->type();
7105         if (t->is_abstract())
7106           t = t->make_non_abstract_type();
7107         t = Builtin_call_expression::real_imag_type(t);
7108         if (t == NULL)
7109           t = Type::make_error_type();
7110         return t;
7111       }
7112
7113     case BUILTIN_CMPLX:
7114       {
7115         const Expression_list* args = this->args();
7116         if (args == NULL || args->size() != 2)
7117           return Type::make_error_type();
7118         Type* t = args->front()->type();
7119         if (t->is_abstract())
7120           {
7121             t = args->back()->type();
7122             if (t->is_abstract())
7123               t = t->make_non_abstract_type();
7124           }
7125         t = Builtin_call_expression::cmplx_type(t);
7126         if (t == NULL)
7127           t = Type::make_error_type();
7128         return t;
7129       }
7130     }
7131 }
7132
7133 // Determine the type.
7134
7135 void
7136 Builtin_call_expression::do_determine_type(const Type_context* context)
7137 {
7138   this->fn()->determine_type_no_context();
7139
7140   const Expression_list* args = this->args();
7141
7142   bool is_print;
7143   Type* arg_type = NULL;
7144   switch (this->code_)
7145     {
7146     case BUILTIN_PRINT:
7147     case BUILTIN_PRINTLN:
7148       // Do not force a large integer constant to "int".
7149       is_print = true;
7150       break;
7151
7152     case BUILTIN_REAL:
7153     case BUILTIN_IMAG:
7154       arg_type = Builtin_call_expression::cmplx_type(context->type);
7155       is_print = false;
7156       break;
7157
7158     case BUILTIN_CMPLX:
7159       {
7160         // For the cmplx function the type of one operand can
7161         // determine the type of the other, as in a binary expression.
7162         arg_type = Builtin_call_expression::real_imag_type(context->type);
7163         if (args != NULL && args->size() == 2)
7164           {
7165             Type* t1 = args->front()->type();
7166             Type* t2 = args->front()->type();
7167             if (!t1->is_abstract())
7168               arg_type = t1;
7169             else if (!t2->is_abstract())
7170               arg_type = t2;
7171           }
7172         is_print = false;
7173       }
7174       break;
7175
7176     default:
7177       is_print = false;
7178       break;
7179     }
7180
7181   if (args != NULL)
7182     {
7183       for (Expression_list::const_iterator pa = args->begin();
7184            pa != args->end();
7185            ++pa)
7186         {
7187           Type_context subcontext;
7188           subcontext.type = arg_type;
7189
7190           if (is_print)
7191             {
7192               // We want to print large constants, we so can't just
7193               // use the appropriate nonabstract type.  Use uint64 for
7194               // an integer if we know it is nonnegative, otherwise
7195               // use int64 for a integer, otherwise use float64 for a
7196               // float or complex128 for a complex.
7197               Type* want_type = NULL;
7198               Type* atype = (*pa)->type();
7199               if (atype->is_abstract())
7200                 {
7201                   if (atype->integer_type() != NULL)
7202                     {
7203                       mpz_t val;
7204                       mpz_init(val);
7205                       Type* dummy;
7206                       if (this->integer_constant_value(true, val, &dummy)
7207                           && mpz_sgn(val) >= 0)
7208                         want_type = Type::lookup_integer_type("uint64");
7209                       else
7210                         want_type = Type::lookup_integer_type("int64");
7211                       mpz_clear(val);
7212                     }
7213                   else if (atype->float_type() != NULL)
7214                     want_type = Type::lookup_float_type("float64");
7215                   else if (atype->complex_type() != NULL)
7216                     want_type = Type::lookup_complex_type("complex128");
7217                   else if (atype->is_abstract_string_type())
7218                     want_type = Type::lookup_string_type();
7219                   else if (atype->is_abstract_boolean_type())
7220                     want_type = Type::lookup_bool_type();
7221                   else
7222                     gcc_unreachable();
7223                   subcontext.type = want_type;
7224                 }
7225             }
7226
7227           (*pa)->determine_type(&subcontext);
7228         }
7229     }
7230 }
7231
7232 // If there is exactly one argument, return true.  Otherwise give an
7233 // error message and return false.
7234
7235 bool
7236 Builtin_call_expression::check_one_arg()
7237 {
7238   const Expression_list* args = this->args();
7239   if (args == NULL || args->size() < 1)
7240     {
7241       this->report_error(_("not enough arguments"));
7242       return false;
7243     }
7244   else if (args->size() > 1)
7245     {
7246       this->report_error(_("too many arguments"));
7247       return false;
7248     }
7249   if (args->front()->is_error_expression()
7250       || args->front()->type()->is_error_type()
7251       || args->front()->type()->is_undefined())
7252     {
7253       this->set_is_error();
7254       return false;
7255     }
7256   return true;
7257 }
7258
7259 // Check argument types for a builtin function.
7260
7261 void
7262 Builtin_call_expression::do_check_types(Gogo*)
7263 {
7264   switch (this->code_)
7265     {
7266     case BUILTIN_INVALID:
7267     case BUILTIN_NEW:
7268     case BUILTIN_MAKE:
7269       return;
7270
7271     case BUILTIN_LEN:
7272     case BUILTIN_CAP:
7273       {
7274         // The single argument may be either a string or an array or a
7275         // map or a channel, or a pointer to a closed array.
7276         if (this->check_one_arg())
7277           {
7278             Type* arg_type = this->one_arg()->type();
7279             if (arg_type->points_to() != NULL
7280                 && arg_type->points_to()->array_type() != NULL
7281                 && !arg_type->points_to()->is_open_array_type())
7282               arg_type = arg_type->points_to();
7283             if (this->code_ == BUILTIN_CAP)
7284               {
7285                 if (!arg_type->is_error_type()
7286                     && arg_type->array_type() == NULL
7287                     && arg_type->channel_type() == NULL)
7288                   this->report_error(_("argument must be array or slice "
7289                                        "or channel"));
7290               }
7291             else
7292               {
7293                 if (!arg_type->is_error_type()
7294                     && !arg_type->is_string_type()
7295                     && arg_type->array_type() == NULL
7296                     && arg_type->map_type() == NULL
7297                     && arg_type->channel_type() == NULL)
7298                   this->report_error(_("argument must be string or "
7299                                        "array or slice or map or channel"));
7300               }
7301           }
7302       }
7303       break;
7304
7305     case BUILTIN_PRINT:
7306     case BUILTIN_PRINTLN:
7307       {
7308         const Expression_list* args = this->args();
7309         if (args == NULL)
7310           {
7311             if (this->code_ == BUILTIN_PRINT)
7312               warning_at(this->location(), 0,
7313                          "no arguments for builtin function %<%s%>",
7314                          (this->code_ == BUILTIN_PRINT
7315                           ? "print"
7316                           : "println"));
7317           }
7318         else
7319           {
7320             for (Expression_list::const_iterator p = args->begin();
7321                  p != args->end();
7322                  ++p)
7323               {
7324                 Type* type = (*p)->type();
7325                 if (type->is_error_type()
7326                     || type->is_string_type()
7327                     || type->integer_type() != NULL
7328                     || type->float_type() != NULL
7329                     || type->complex_type() != NULL
7330                     || type->is_boolean_type()
7331                     || type->points_to() != NULL
7332                     || type->interface_type() != NULL
7333                     || type->channel_type() != NULL
7334                     || type->map_type() != NULL
7335                     || type->function_type() != NULL
7336                     || type->is_open_array_type())
7337                   ;
7338                 else
7339                   this->report_error(_("unsupported argument type to "
7340                                        "builtin function"));
7341               }
7342           }
7343       }
7344       break;
7345
7346     case BUILTIN_CLOSE:
7347     case BUILTIN_CLOSED:
7348       if (this->check_one_arg())
7349         {
7350           if (this->one_arg()->type()->channel_type() == NULL)
7351             this->report_error(_("argument must be channel"));
7352         }
7353       break;
7354
7355     case BUILTIN_PANIC:
7356     case BUILTIN_SIZEOF:
7357     case BUILTIN_ALIGNOF:
7358       this->check_one_arg();
7359       break;
7360
7361     case BUILTIN_RECOVER:
7362       if (this->args() != NULL && !this->args()->empty())
7363         this->report_error(_("too many arguments"));
7364       break;
7365
7366     case BUILTIN_OFFSETOF:
7367       if (this->check_one_arg())
7368         {
7369           Expression* arg = this->one_arg();
7370           if (arg->field_reference_expression() == NULL)
7371             this->report_error(_("argument must be a field reference"));
7372         }
7373       break;
7374
7375     case BUILTIN_COPY:
7376       {
7377         const Expression_list* args = this->args();
7378         if (args == NULL || args->size() < 2)
7379           {
7380             this->report_error(_("not enough arguments"));
7381             break;
7382           }
7383         else if (args->size() > 2)
7384           {
7385             this->report_error(_("too many arguments"));
7386             break;
7387           }
7388         Type* arg1_type = args->front()->type();
7389         Type* arg2_type = args->back()->type();
7390         if (arg1_type->is_error_type() || arg2_type->is_error_type())
7391           break;
7392
7393         Type* e1;
7394         if (arg1_type->is_open_array_type())
7395           e1 = arg1_type->array_type()->element_type();
7396         else
7397           {
7398             this->report_error(_("left argument must be a slice"));
7399             break;
7400           }
7401
7402         Type* e2;
7403         if (arg2_type->is_open_array_type())
7404           e2 = arg2_type->array_type()->element_type();
7405         else if (arg2_type->is_string_type())
7406           e2 = Type::lookup_integer_type("uint8");
7407         else
7408           {
7409             this->report_error(_("right argument must be a slice or a string"));
7410             break;
7411           }
7412
7413         if (!Type::are_identical(e1, e2, true, NULL))
7414           this->report_error(_("element types must be the same"));
7415       }
7416       break;
7417
7418     case BUILTIN_APPEND:
7419       {
7420         const Expression_list* args = this->args();
7421         if (args == NULL || args->size() < 2)
7422           {
7423             this->report_error(_("not enough arguments"));
7424             break;
7425           }
7426         if (args->size() > 2)
7427           {
7428             this->report_error(_("too many arguments"));
7429             break;
7430           }
7431         std::string reason;
7432         if (!Type::are_assignable(args->front()->type(), args->back()->type(),
7433                                   &reason))
7434           {
7435             if (reason.empty())
7436               this->report_error(_("arguments 1 and 2 have different types"));
7437             else
7438               {
7439                 error_at(this->location(),
7440                          "arguments 1 and 2 have different types (%s)",
7441                          reason.c_str());
7442                 this->set_is_error();
7443               }
7444           }
7445         break;
7446       }
7447
7448     case BUILTIN_REAL:
7449     case BUILTIN_IMAG:
7450       if (this->check_one_arg())
7451         {
7452           if (this->one_arg()->type()->complex_type() == NULL)
7453             this->report_error(_("argument must have complex type"));
7454         }
7455       break;
7456
7457     case BUILTIN_CMPLX:
7458       {
7459         const Expression_list* args = this->args();
7460         if (args == NULL || args->size() < 2)
7461           this->report_error(_("not enough arguments"));
7462         else if (args->size() > 2)
7463           this->report_error(_("too many arguments"));
7464         else if (args->front()->is_error_expression()
7465                  || args->front()->type()->is_error_type()
7466                  || args->back()->is_error_expression()
7467                  || args->back()->type()->is_error_type())
7468           this->set_is_error();
7469         else if (!Type::are_identical(args->front()->type(),
7470                                       args->back()->type(), true, NULL))
7471           this->report_error(_("cmplx arguments must have identical types"));
7472         else if (args->front()->type()->float_type() == NULL)
7473           this->report_error(_("cmplx arguments must have "
7474                                "floating-point type"));
7475       }
7476       break;
7477
7478     default:
7479       gcc_unreachable();
7480     }
7481 }
7482
7483 // Return the tree for a builtin function.
7484
7485 tree
7486 Builtin_call_expression::do_get_tree(Translate_context* context)
7487 {
7488   Gogo* gogo = context->gogo();
7489   source_location location = this->location();
7490   switch (this->code_)
7491     {
7492     case BUILTIN_INVALID:
7493     case BUILTIN_NEW:
7494     case BUILTIN_MAKE:
7495       gcc_unreachable();
7496
7497     case BUILTIN_LEN:
7498     case BUILTIN_CAP:
7499       {
7500         const Expression_list* args = this->args();
7501         gcc_assert(args != NULL && args->size() == 1);
7502         Expression* arg = *args->begin();
7503         Type* arg_type = arg->type();
7504
7505         if (this->seen_)
7506           {
7507             gcc_assert(saw_errors());
7508             return error_mark_node;
7509           }
7510         this->seen_ = true;
7511
7512         tree arg_tree = arg->get_tree(context);
7513
7514         this->seen_ = false;
7515
7516         if (arg_tree == error_mark_node)
7517           return error_mark_node;
7518
7519         if (arg_type->points_to() != NULL)
7520           {
7521             arg_type = arg_type->points_to();
7522             gcc_assert(arg_type->array_type() != NULL
7523                        && !arg_type->is_open_array_type());
7524             gcc_assert(POINTER_TYPE_P(TREE_TYPE(arg_tree)));
7525             arg_tree = build_fold_indirect_ref(arg_tree);
7526           }
7527
7528         tree val_tree;
7529         if (this->code_ == BUILTIN_LEN)
7530           {
7531             if (arg_type->is_string_type())
7532               val_tree = String_type::length_tree(gogo, arg_tree);
7533             else if (arg_type->array_type() != NULL)
7534               {
7535                 if (this->seen_)
7536                   {
7537                     gcc_assert(saw_errors());
7538                     return error_mark_node;
7539                   }
7540                 this->seen_ = true;
7541                 val_tree = arg_type->array_type()->length_tree(gogo, arg_tree);
7542                 this->seen_ = false;
7543               }
7544             else if (arg_type->map_type() != NULL)
7545               {
7546                 static tree map_len_fndecl;
7547                 val_tree = Gogo::call_builtin(&map_len_fndecl,
7548                                               location,
7549                                               "__go_map_len",
7550                                               1,
7551                                               sizetype,
7552                                               arg_type->get_tree(gogo),
7553                                               arg_tree);
7554               }
7555             else if (arg_type->channel_type() != NULL)
7556               {
7557                 static tree chan_len_fndecl;
7558                 val_tree = Gogo::call_builtin(&chan_len_fndecl,
7559                                               location,
7560                                               "__go_chan_len",
7561                                               1,
7562                                               sizetype,
7563                                               arg_type->get_tree(gogo),
7564                                               arg_tree);
7565               }
7566             else
7567               gcc_unreachable();
7568           }
7569         else
7570           {
7571             if (arg_type->array_type() != NULL)
7572               {
7573                 if (this->seen_)
7574                   {
7575                     gcc_assert(saw_errors());
7576                     return error_mark_node;
7577                   }
7578                 this->seen_ = true;
7579                 val_tree = arg_type->array_type()->capacity_tree(gogo,
7580                                                                  arg_tree);
7581                 this->seen_ = false;
7582               }
7583             else if (arg_type->channel_type() != NULL)
7584               {
7585                 static tree chan_cap_fndecl;
7586                 val_tree = Gogo::call_builtin(&chan_cap_fndecl,
7587                                               location,
7588                                               "__go_chan_cap",
7589                                               1,
7590                                               sizetype,
7591                                               arg_type->get_tree(gogo),
7592                                               arg_tree);
7593               }
7594             else
7595               gcc_unreachable();
7596           }
7597
7598         if (val_tree == error_mark_node)
7599           return error_mark_node;
7600
7601         tree type_tree = Type::lookup_integer_type("int")->get_tree(gogo);
7602         if (type_tree == TREE_TYPE(val_tree))
7603           return val_tree;
7604         else
7605           return fold(convert_to_integer(type_tree, val_tree));
7606       }
7607
7608     case BUILTIN_PRINT:
7609     case BUILTIN_PRINTLN:
7610       {
7611         const bool is_ln = this->code_ == BUILTIN_PRINTLN;
7612         tree stmt_list = NULL_TREE;
7613
7614         const Expression_list* call_args = this->args();
7615         if (call_args != NULL)
7616           {
7617             for (Expression_list::const_iterator p = call_args->begin();
7618                  p != call_args->end();
7619                  ++p)
7620               {
7621                 if (is_ln && p != call_args->begin())
7622                   {
7623                     static tree print_space_fndecl;
7624                     tree call = Gogo::call_builtin(&print_space_fndecl,
7625                                                    location,
7626                                                    "__go_print_space",
7627                                                    0,
7628                                                    void_type_node);
7629                     if (call == error_mark_node)
7630                       return error_mark_node;
7631                     append_to_statement_list(call, &stmt_list);
7632                   }
7633
7634                 Type* type = (*p)->type();
7635
7636                 tree arg = (*p)->get_tree(context);
7637                 if (arg == error_mark_node)
7638                   return error_mark_node;
7639
7640                 tree* pfndecl;
7641                 const char* fnname;
7642                 if (type->is_string_type())
7643                   {
7644                     static tree print_string_fndecl;
7645                     pfndecl = &print_string_fndecl;
7646                     fnname = "__go_print_string";
7647                   }
7648                 else if (type->integer_type() != NULL
7649                          && type->integer_type()->is_unsigned())
7650                   {
7651                     static tree print_uint64_fndecl;
7652                     pfndecl = &print_uint64_fndecl;
7653                     fnname = "__go_print_uint64";
7654                     Type* itype = Type::lookup_integer_type("uint64");
7655                     arg = fold_convert_loc(location, itype->get_tree(gogo),
7656                                            arg);
7657                   }
7658                 else if (type->integer_type() != NULL)
7659                   {
7660                     static tree print_int64_fndecl;
7661                     pfndecl = &print_int64_fndecl;
7662                     fnname = "__go_print_int64";
7663                     Type* itype = Type::lookup_integer_type("int64");
7664                     arg = fold_convert_loc(location, itype->get_tree(gogo),
7665                                            arg);
7666                   }
7667                 else if (type->float_type() != NULL)
7668                   {
7669                     static tree print_double_fndecl;
7670                     pfndecl = &print_double_fndecl;
7671                     fnname = "__go_print_double";
7672                     arg = fold_convert_loc(location, double_type_node, arg);
7673                   }
7674                 else if (type->complex_type() != NULL)
7675                   {
7676                     static tree print_complex_fndecl;
7677                     pfndecl = &print_complex_fndecl;
7678                     fnname = "__go_print_complex";
7679                     arg = fold_convert_loc(location, complex_double_type_node,
7680                                            arg);
7681                   }
7682                 else if (type->is_boolean_type())
7683                   {
7684                     static tree print_bool_fndecl;
7685                     pfndecl = &print_bool_fndecl;
7686                     fnname = "__go_print_bool";
7687                   }
7688                 else if (type->points_to() != NULL
7689                          || type->channel_type() != NULL
7690                          || type->map_type() != NULL
7691                          || type->function_type() != NULL)
7692                   {
7693                     static tree print_pointer_fndecl;
7694                     pfndecl = &print_pointer_fndecl;
7695                     fnname = "__go_print_pointer";
7696                     arg = fold_convert_loc(location, ptr_type_node, arg);
7697                   }
7698                 else if (type->interface_type() != NULL)
7699                   {
7700                     if (type->interface_type()->is_empty())
7701                       {
7702                         static tree print_empty_interface_fndecl;
7703                         pfndecl = &print_empty_interface_fndecl;
7704                         fnname = "__go_print_empty_interface";
7705                       }
7706                     else
7707                       {
7708                         static tree print_interface_fndecl;
7709                         pfndecl = &print_interface_fndecl;
7710                         fnname = "__go_print_interface";
7711                       }
7712                   }
7713                 else if (type->is_open_array_type())
7714                   {
7715                     static tree print_slice_fndecl;
7716                     pfndecl = &print_slice_fndecl;
7717                     fnname = "__go_print_slice";
7718                   }
7719                 else
7720                   gcc_unreachable();
7721
7722                 tree call = Gogo::call_builtin(pfndecl,
7723                                                location,
7724                                                fnname,
7725                                                1,
7726                                                void_type_node,
7727                                                TREE_TYPE(arg),
7728                                                arg);
7729                 if (call == error_mark_node)
7730                   return error_mark_node;
7731                 append_to_statement_list(call, &stmt_list);
7732               }
7733           }
7734
7735         if (is_ln)
7736           {
7737             static tree print_nl_fndecl;
7738             tree call = Gogo::call_builtin(&print_nl_fndecl,
7739                                            location,
7740                                            "__go_print_nl",
7741                                            0,
7742                                            void_type_node);
7743             if (call == error_mark_node)
7744               return error_mark_node;
7745             append_to_statement_list(call, &stmt_list);
7746           }
7747
7748         return stmt_list;
7749       }
7750
7751     case BUILTIN_PANIC:
7752       {
7753         const Expression_list* args = this->args();
7754         gcc_assert(args != NULL && args->size() == 1);
7755         Expression* arg = args->front();
7756         tree arg_tree = arg->get_tree(context);
7757         if (arg_tree == error_mark_node)
7758           return error_mark_node;
7759         Type *empty = Type::make_interface_type(NULL, BUILTINS_LOCATION);
7760         arg_tree = Expression::convert_for_assignment(context, empty,
7761                                                       arg->type(),
7762                                                       arg_tree, location);
7763         static tree panic_fndecl;
7764         tree call = Gogo::call_builtin(&panic_fndecl,
7765                                        location,
7766                                        "__go_panic",
7767                                        1,
7768                                        void_type_node,
7769                                        TREE_TYPE(arg_tree),
7770                                        arg_tree);
7771         if (call == error_mark_node)
7772           return error_mark_node;
7773         // This function will throw an exception.
7774         TREE_NOTHROW(panic_fndecl) = 0;
7775         // This function will not return.
7776         TREE_THIS_VOLATILE(panic_fndecl) = 1;
7777         return call;
7778       }
7779
7780     case BUILTIN_RECOVER:
7781       {
7782         // The argument is set when building recover thunks.  It's a
7783         // boolean value which is true if we can recover a value now.
7784         const Expression_list* args = this->args();
7785         gcc_assert(args != NULL && args->size() == 1);
7786         Expression* arg = args->front();
7787         tree arg_tree = arg->get_tree(context);
7788         if (arg_tree == error_mark_node)
7789           return error_mark_node;
7790
7791         Type *empty = Type::make_interface_type(NULL, BUILTINS_LOCATION);
7792         tree empty_tree = empty->get_tree(context->gogo());
7793
7794         Type* nil_type = Type::make_nil_type();
7795         Expression* nil = Expression::make_nil(location);
7796         tree nil_tree = nil->get_tree(context);
7797         tree empty_nil_tree = Expression::convert_for_assignment(context,
7798                                                                  empty,
7799                                                                  nil_type,
7800                                                                  nil_tree,
7801                                                                  location);
7802
7803         // We need to handle a deferred call to recover specially,
7804         // because it changes whether it can recover a panic or not.
7805         // See test7 in test/recover1.go.
7806         tree call;
7807         if (this->is_deferred())
7808           {
7809             static tree deferred_recover_fndecl;
7810             call = Gogo::call_builtin(&deferred_recover_fndecl,
7811                                       location,
7812                                       "__go_deferred_recover",
7813                                       0,
7814                                       empty_tree);
7815           }
7816         else
7817           {
7818             static tree recover_fndecl;
7819             call = Gogo::call_builtin(&recover_fndecl,
7820                                       location,
7821                                       "__go_recover",
7822                                       0,
7823                                       empty_tree);
7824           }
7825         if (call == error_mark_node)
7826           return error_mark_node;
7827         return fold_build3_loc(location, COND_EXPR, empty_tree, arg_tree,
7828                                call, empty_nil_tree);
7829       }
7830
7831     case BUILTIN_CLOSE:
7832     case BUILTIN_CLOSED:
7833       {
7834         const Expression_list* args = this->args();
7835         gcc_assert(args != NULL && args->size() == 1);
7836         Expression* arg = args->front();
7837         tree arg_tree = arg->get_tree(context);
7838         if (arg_tree == error_mark_node)
7839           return error_mark_node;
7840         if (this->code_ == BUILTIN_CLOSE)
7841           {
7842             static tree close_fndecl;
7843             return Gogo::call_builtin(&close_fndecl,
7844                                       location,
7845                                       "__go_builtin_close",
7846                                       1,
7847                                       void_type_node,
7848                                       TREE_TYPE(arg_tree),
7849                                       arg_tree);
7850           }
7851         else
7852           {
7853             static tree closed_fndecl;
7854             return Gogo::call_builtin(&closed_fndecl,
7855                                       location,
7856                                       "__go_builtin_closed",
7857                                       1,
7858                                       boolean_type_node,
7859                                       TREE_TYPE(arg_tree),
7860                                       arg_tree);
7861           }
7862       }
7863
7864     case BUILTIN_SIZEOF:
7865     case BUILTIN_OFFSETOF:
7866     case BUILTIN_ALIGNOF:
7867       {
7868         mpz_t val;
7869         mpz_init(val);
7870         Type* dummy;
7871         bool b = this->integer_constant_value(true, val, &dummy);
7872         gcc_assert(b);
7873         tree type = Type::lookup_integer_type("int")->get_tree(gogo);
7874         tree ret = Expression::integer_constant_tree(val, type);
7875         mpz_clear(val);
7876         return ret;
7877       }
7878
7879     case BUILTIN_COPY:
7880       {
7881         const Expression_list* args = this->args();
7882         gcc_assert(args != NULL && args->size() == 2);
7883         Expression* arg1 = args->front();
7884         Expression* arg2 = args->back();
7885
7886         tree arg1_tree = arg1->get_tree(context);
7887         tree arg2_tree = arg2->get_tree(context);
7888         if (arg1_tree == error_mark_node || arg2_tree == error_mark_node)
7889           return error_mark_node;
7890
7891         Type* arg1_type = arg1->type();
7892         Array_type* at = arg1_type->array_type();
7893         arg1_tree = save_expr(arg1_tree);
7894         tree arg1_val = at->value_pointer_tree(gogo, arg1_tree);
7895         tree arg1_len = at->length_tree(gogo, arg1_tree);
7896         if (arg1_val == error_mark_node || arg1_len == error_mark_node)
7897           return error_mark_node;
7898
7899         Type* arg2_type = arg2->type();
7900         tree arg2_val;
7901         tree arg2_len;
7902         if (arg2_type->is_open_array_type())
7903           {
7904             at = arg2_type->array_type();
7905             arg2_tree = save_expr(arg2_tree);
7906             arg2_val = at->value_pointer_tree(gogo, arg2_tree);
7907             arg2_len = at->length_tree(gogo, arg2_tree);
7908           }
7909         else
7910           {
7911             arg2_tree = save_expr(arg2_tree);
7912             arg2_val = String_type::bytes_tree(gogo, arg2_tree);
7913             arg2_len = String_type::length_tree(gogo, arg2_tree);
7914           }
7915         if (arg2_val == error_mark_node || arg2_len == error_mark_node)
7916           return error_mark_node;
7917
7918         arg1_len = save_expr(arg1_len);
7919         arg2_len = save_expr(arg2_len);
7920         tree len = fold_build3_loc(location, COND_EXPR, TREE_TYPE(arg1_len),
7921                                    fold_build2_loc(location, LT_EXPR,
7922                                                    boolean_type_node,
7923                                                    arg1_len, arg2_len),
7924                                    arg1_len, arg2_len);
7925         len = save_expr(len);
7926
7927         Type* element_type = at->element_type();
7928         tree element_type_tree = element_type->get_tree(gogo);
7929         if (element_type_tree == error_mark_node)
7930           return error_mark_node;
7931         tree element_size = TYPE_SIZE_UNIT(element_type_tree);
7932         tree bytecount = fold_convert_loc(location, TREE_TYPE(element_size),
7933                                           len);
7934         bytecount = fold_build2_loc(location, MULT_EXPR,
7935                                     TREE_TYPE(element_size),
7936                                     bytecount, element_size);
7937         bytecount = fold_convert_loc(location, size_type_node, bytecount);
7938
7939         arg1_val = fold_convert_loc(location, ptr_type_node, arg1_val);
7940         arg2_val = fold_convert_loc(location, ptr_type_node, arg2_val);
7941
7942         static tree copy_fndecl;
7943         tree call = Gogo::call_builtin(&copy_fndecl,
7944                                        location,
7945                                        "__go_copy",
7946                                        3,
7947                                        void_type_node,
7948                                        ptr_type_node,
7949                                        arg1_val,
7950                                        ptr_type_node,
7951                                        arg2_val,
7952                                        size_type_node,
7953                                        bytecount);
7954         if (call == error_mark_node)
7955           return error_mark_node;
7956
7957         return fold_build2_loc(location, COMPOUND_EXPR, TREE_TYPE(len),
7958                                call, len);
7959       }
7960
7961     case BUILTIN_APPEND:
7962       {
7963         const Expression_list* args = this->args();
7964         gcc_assert(args != NULL && args->size() == 2);
7965         Expression* arg1 = args->front();
7966         Expression* arg2 = args->back();
7967
7968         tree arg1_tree = arg1->get_tree(context);
7969         tree arg2_tree = arg2->get_tree(context);
7970         if (arg1_tree == error_mark_node || arg2_tree == error_mark_node)
7971           return error_mark_node;
7972
7973         Array_type* at = arg1->type()->array_type();
7974         Type* element_type = at->element_type();
7975
7976         arg2_tree = Expression::convert_for_assignment(context, at,
7977                                                        arg2->type(),
7978                                                        arg2_tree,
7979                                                        location);
7980         if (arg2_tree == error_mark_node)
7981           return error_mark_node;
7982
7983         arg2_tree = save_expr(arg2_tree);
7984         tree arg2_val = at->value_pointer_tree(gogo, arg2_tree);
7985         tree arg2_len = at->length_tree(gogo, arg2_tree);
7986         if (arg2_val == error_mark_node || arg2_len == error_mark_node)
7987           return error_mark_node;
7988         arg2_val = fold_convert_loc(location, ptr_type_node, arg2_val);
7989         arg2_len = fold_convert_loc(location, size_type_node, arg2_len);
7990
7991         tree element_type_tree = element_type->get_tree(gogo);
7992         if (element_type_tree == error_mark_node)
7993           return error_mark_node;
7994         tree element_size = TYPE_SIZE_UNIT(element_type_tree);
7995         element_size = fold_convert_loc(location, size_type_node,
7996                                         element_size);
7997
7998         // We rebuild the decl each time since the slice types may
7999         // change.
8000         tree append_fndecl = NULL_TREE;
8001         return Gogo::call_builtin(&append_fndecl,
8002                                   location,
8003                                   "__go_append",
8004                                   4,
8005                                   TREE_TYPE(arg1_tree),
8006                                   TREE_TYPE(arg1_tree),
8007                                   arg1_tree,
8008                                   ptr_type_node,
8009                                   arg2_val,
8010                                   size_type_node,
8011                                   arg2_len,
8012                                   size_type_node,
8013                                   element_size);
8014       }
8015
8016     case BUILTIN_REAL:
8017     case BUILTIN_IMAG:
8018       {
8019         const Expression_list* args = this->args();
8020         gcc_assert(args != NULL && args->size() == 1);
8021         Expression* arg = args->front();
8022         tree arg_tree = arg->get_tree(context);
8023         if (arg_tree == error_mark_node)
8024           return error_mark_node;
8025         gcc_assert(COMPLEX_FLOAT_TYPE_P(TREE_TYPE(arg_tree)));
8026         if (this->code_ == BUILTIN_REAL)
8027           return fold_build1_loc(location, REALPART_EXPR,
8028                                  TREE_TYPE(TREE_TYPE(arg_tree)),
8029                                  arg_tree);
8030         else
8031           return fold_build1_loc(location, IMAGPART_EXPR,
8032                                  TREE_TYPE(TREE_TYPE(arg_tree)),
8033                                  arg_tree);
8034       }
8035
8036     case BUILTIN_CMPLX:
8037       {
8038         const Expression_list* args = this->args();
8039         gcc_assert(args != NULL && args->size() == 2);
8040         tree r = args->front()->get_tree(context);
8041         tree i = args->back()->get_tree(context);
8042         if (r == error_mark_node || i == error_mark_node)
8043           return error_mark_node;
8044         gcc_assert(TYPE_MAIN_VARIANT(TREE_TYPE(r))
8045                    == TYPE_MAIN_VARIANT(TREE_TYPE(i)));
8046         gcc_assert(SCALAR_FLOAT_TYPE_P(TREE_TYPE(r)));
8047         return fold_build2_loc(location, COMPLEX_EXPR,
8048                                build_complex_type(TREE_TYPE(r)),
8049                                r, i);
8050       }
8051
8052     default:
8053       gcc_unreachable();
8054     }
8055 }
8056
8057 // We have to support exporting a builtin call expression, because
8058 // code can set a constant to the result of a builtin expression.
8059
8060 void
8061 Builtin_call_expression::do_export(Export* exp) const
8062 {
8063   bool ok = false;
8064
8065   mpz_t val;
8066   mpz_init(val);
8067   Type* dummy;
8068   if (this->integer_constant_value(true, val, &dummy))
8069     {
8070       Integer_expression::export_integer(exp, val);
8071       ok = true;
8072     }
8073   mpz_clear(val);
8074
8075   if (!ok)
8076     {
8077       mpfr_t fval;
8078       mpfr_init(fval);
8079       if (this->float_constant_value(fval, &dummy))
8080         {
8081           Float_expression::export_float(exp, fval);
8082           ok = true;
8083         }
8084       mpfr_clear(fval);
8085     }
8086
8087   if (!ok)
8088     {
8089       mpfr_t real;
8090       mpfr_t imag;
8091       mpfr_init(real);
8092       mpfr_init(imag);
8093       if (this->complex_constant_value(real, imag, &dummy))
8094         {
8095           Complex_expression::export_complex(exp, real, imag);
8096           ok = true;
8097         }
8098       mpfr_clear(real);
8099       mpfr_clear(imag);
8100     }
8101
8102   if (!ok)
8103     {
8104       error_at(this->location(), "value is not constant");
8105       return;
8106     }
8107
8108   // A trailing space lets us reliably identify the end of the number.
8109   exp->write_c_string(" ");
8110 }
8111
8112 // Class Call_expression.
8113
8114 // Traversal.
8115
8116 int
8117 Call_expression::do_traverse(Traverse* traverse)
8118 {
8119   if (Expression::traverse(&this->fn_, traverse) == TRAVERSE_EXIT)
8120     return TRAVERSE_EXIT;
8121   if (this->args_ != NULL)
8122     {
8123       if (this->args_->traverse(traverse) == TRAVERSE_EXIT)
8124         return TRAVERSE_EXIT;
8125     }
8126   return TRAVERSE_CONTINUE;
8127 }
8128
8129 // Lower a call statement.
8130
8131 Expression*
8132 Call_expression::do_lower(Gogo* gogo, Named_object* function, int)
8133 {
8134   // A type case can look like a function call.
8135   if (this->fn_->is_type_expression()
8136       && this->args_ != NULL
8137       && this->args_->size() == 1)
8138     return Expression::make_cast(this->fn_->type(), this->args_->front(),
8139                                  this->location());
8140
8141   // Recognize a call to a builtin function.
8142   Func_expression* fne = this->fn_->func_expression();
8143   if (fne != NULL
8144       && fne->named_object()->is_function_declaration()
8145       && fne->named_object()->func_declaration_value()->type()->is_builtin())
8146     return new Builtin_call_expression(gogo, this->fn_, this->args_,
8147                                        this->is_varargs_, this->location());
8148
8149   // Handle an argument which is a call to a function which returns
8150   // multiple results.
8151   if (this->args_ != NULL
8152       && this->args_->size() == 1
8153       && this->args_->front()->call_expression() != NULL
8154       && this->fn_->type()->function_type() != NULL)
8155     {
8156       Function_type* fntype = this->fn_->type()->function_type();
8157       size_t rc = this->args_->front()->call_expression()->result_count();
8158       if (rc > 1
8159           && fntype->parameters() != NULL
8160           && (fntype->parameters()->size() == rc
8161               || (fntype->is_varargs()
8162                   && fntype->parameters()->size() - 1 <= rc)))
8163         {
8164           Call_expression* call = this->args_->front()->call_expression();
8165           Expression_list* args = new Expression_list;
8166           for (size_t i = 0; i < rc; ++i)
8167             args->push_back(Expression::make_call_result(call, i));
8168           // We can't return a new call expression here, because this
8169           // one may be referenced by Call_result expressions.  FIXME.
8170           delete this->args_;
8171           this->args_ = args;
8172         }
8173     }
8174
8175   // Handle a call to a varargs function by packaging up the extra
8176   // parameters.
8177   if (this->fn_->type()->function_type() != NULL
8178       && this->fn_->type()->function_type()->is_varargs())
8179     {
8180       Function_type* fntype = this->fn_->type()->function_type();
8181       const Typed_identifier_list* parameters = fntype->parameters();
8182       gcc_assert(parameters != NULL && !parameters->empty());
8183       Type* varargs_type = parameters->back().type();
8184       return this->lower_varargs(gogo, function, varargs_type,
8185                                  parameters->size());
8186     }
8187
8188   return this;
8189 }
8190
8191 // Lower a call to a varargs function.  FUNCTION is the function in
8192 // which the call occurs--it's not the function we are calling.
8193 // VARARGS_TYPE is the type of the varargs parameter, a slice type.
8194 // PARAM_COUNT is the number of parameters of the function we are
8195 // calling; the last of these parameters will be the varargs
8196 // parameter.
8197
8198 Expression*
8199 Call_expression::lower_varargs(Gogo* gogo, Named_object* function,
8200                                Type* varargs_type, size_t param_count)
8201 {
8202   if (this->varargs_are_lowered_)
8203     return this;
8204
8205   source_location loc = this->location();
8206
8207   gcc_assert(param_count > 0);
8208   gcc_assert(varargs_type->is_open_array_type());
8209
8210   size_t arg_count = this->args_ == NULL ? 0 : this->args_->size();
8211   if (arg_count < param_count - 1)
8212     {
8213       // Not enough arguments; will be caught in check_types.
8214       return this;
8215     }
8216
8217   Expression_list* old_args = this->args_;
8218   Expression_list* new_args = new Expression_list();
8219   bool push_empty_arg = false;
8220   if (old_args == NULL || old_args->empty())
8221     {
8222       gcc_assert(param_count == 1);
8223       push_empty_arg = true;
8224     }
8225   else
8226     {
8227       Expression_list::const_iterator pa;
8228       int i = 1;
8229       for (pa = old_args->begin(); pa != old_args->end(); ++pa, ++i)
8230         {
8231           if (static_cast<size_t>(i) == param_count)
8232             break;
8233           new_args->push_back(*pa);
8234         }
8235
8236       // We have reached the varargs parameter.
8237
8238       bool issued_error = false;
8239       if (pa == old_args->end())
8240         push_empty_arg = true;
8241       else if (pa + 1 == old_args->end() && this->is_varargs_)
8242         new_args->push_back(*pa);
8243       else if (this->is_varargs_)
8244         {
8245           this->report_error(_("too many arguments"));
8246           return this;
8247         }
8248       else if (pa + 1 == old_args->end()
8249                && this->is_compatible_varargs_argument(function, *pa,
8250                                                        varargs_type,
8251                                                        &issued_error))
8252         new_args->push_back(*pa);
8253       else
8254         {
8255           Type* element_type = varargs_type->array_type()->element_type();
8256           Expression_list* vals = new Expression_list;
8257           for (; pa != old_args->end(); ++pa, ++i)
8258             {
8259               // Check types here so that we get a better message.
8260               Type* patype = (*pa)->type();
8261               source_location paloc = (*pa)->location();
8262               if (!this->check_argument_type(i, element_type, patype,
8263                                              paloc, issued_error))
8264                 continue;
8265               vals->push_back(*pa);
8266             }
8267           Expression* val =
8268             Expression::make_slice_composite_literal(varargs_type, vals, loc);
8269           new_args->push_back(val);
8270         }
8271     }
8272
8273   if (push_empty_arg)
8274     new_args->push_back(Expression::make_nil(loc));
8275
8276   // We can't return a new call expression here, because this one may
8277   // be referenced by Call_result expressions.  FIXME.
8278   if (old_args != NULL)
8279     delete old_args;
8280   this->args_ = new_args;
8281   this->varargs_are_lowered_ = true;
8282
8283   // Lower all the new subexpressions.
8284   Expression* ret = this;
8285   gogo->lower_expression(function, &ret);
8286   gcc_assert(ret == this);
8287   return ret;
8288 }
8289
8290 // Return true if ARG is a varargs argment which should be passed to
8291 // the varargs parameter of type PARAM_TYPE without wrapping.  ARG
8292 // will be the last argument passed in the call, and PARAM_TYPE will
8293 // be the type of the last parameter of the varargs function being
8294 // called.
8295
8296 bool
8297 Call_expression::is_compatible_varargs_argument(Named_object* function,
8298                                                 Expression* arg,
8299                                                 Type* param_type,
8300                                                 bool* issued_error)
8301 {
8302   *issued_error = false;
8303
8304   Type* var_type = NULL;
8305
8306   // The simple case is passing the varargs parameter of the caller.
8307   Var_expression* ve = arg->var_expression();
8308   if (ve != NULL && ve->named_object()->is_variable())
8309     {
8310       Variable* var = ve->named_object()->var_value();
8311       if (var->is_varargs_parameter())
8312         var_type = var->type();
8313     }
8314
8315   // The complex case is passing the varargs parameter of some
8316   // enclosing function.  This will look like passing down *c.f where
8317   // c is the closure variable and f is a field in the closure.
8318   if (function != NULL
8319       && function->func_value()->needs_closure()
8320       && arg->classification() == EXPRESSION_UNARY)
8321     {
8322       Unary_expression* ue = static_cast<Unary_expression*>(arg);
8323       if (ue->op() == OPERATOR_MULT)
8324         {
8325           Field_reference_expression* fre =
8326             ue->operand()->deref()->field_reference_expression();
8327           if (fre != NULL)
8328             {
8329               Var_expression* ve = fre->expr()->deref()->var_expression();
8330               if (ve != NULL)
8331                 {
8332                   Named_object* no = ve->named_object();
8333                   Function* f = function->func_value();
8334                   if (no == f->closure_var())
8335                     {
8336                       // At this point we know that this indeed a
8337                       // reference to some enclosing variable.  Now we
8338                       // need to figure out whether that variable is a
8339                       // varargs parameter.
8340                       Named_object* enclosing =
8341                         f->enclosing_var(fre->field_index());
8342                       Variable* var = enclosing->var_value();
8343                       if (var->is_varargs_parameter())
8344                         var_type = var->type();
8345                     }
8346                 }
8347             }
8348         }
8349     }
8350
8351   if (var_type == NULL)
8352     return false;
8353
8354   // We only match if the parameter is the same, with an identical
8355   // type.
8356   Array_type* var_at = var_type->array_type();
8357   gcc_assert(var_at != NULL);
8358   Array_type* param_at = param_type->array_type();
8359   if (param_at != NULL
8360       && Type::are_identical(var_at->element_type(),
8361                              param_at->element_type(), true, NULL))
8362     return true;
8363   error_at(arg->location(), "... mismatch: passing ...T as ...");
8364   *issued_error = true;
8365   return false;
8366 }
8367
8368 // Get the function type.  Returns NULL if we don't know the type.  If
8369 // this returns NULL, and if_ERROR is true, issues an error.
8370
8371 Function_type*
8372 Call_expression::get_function_type() const
8373 {
8374   return this->fn_->type()->function_type();
8375 }
8376
8377 // Return the number of values which this call will return.
8378
8379 size_t
8380 Call_expression::result_count() const
8381 {
8382   const Function_type* fntype = this->get_function_type();
8383   if (fntype == NULL)
8384     return 0;
8385   if (fntype->results() == NULL)
8386     return 0;
8387   return fntype->results()->size();
8388 }
8389
8390 // Return whether this is a call to the predeclared function recover.
8391
8392 bool
8393 Call_expression::is_recover_call() const
8394 {
8395   return this->do_is_recover_call();
8396 }
8397
8398 // Set the argument to the recover function.
8399
8400 void
8401 Call_expression::set_recover_arg(Expression* arg)
8402 {
8403   this->do_set_recover_arg(arg);
8404 }
8405
8406 // Virtual functions also implemented by Builtin_call_expression.
8407
8408 bool
8409 Call_expression::do_is_recover_call() const
8410 {
8411   return false;
8412 }
8413
8414 void
8415 Call_expression::do_set_recover_arg(Expression*)
8416 {
8417   gcc_unreachable();
8418 }
8419
8420 // Get the type.
8421
8422 Type*
8423 Call_expression::do_type()
8424 {
8425   if (this->type_ != NULL)
8426     return this->type_;
8427
8428   Type* ret;
8429   Function_type* fntype = this->get_function_type();
8430   if (fntype == NULL)
8431     return Type::make_error_type();
8432
8433   const Typed_identifier_list* results = fntype->results();
8434   if (results == NULL)
8435     ret = Type::make_void_type();
8436   else if (results->size() == 1)
8437     ret = results->begin()->type();
8438   else
8439     ret = Type::make_call_multiple_result_type(this);
8440
8441   this->type_ = ret;
8442
8443   return this->type_;
8444 }
8445
8446 // Determine types for a call expression.  We can use the function
8447 // parameter types to set the types of the arguments.
8448
8449 void
8450 Call_expression::do_determine_type(const Type_context*)
8451 {
8452   this->fn_->determine_type_no_context();
8453   Function_type* fntype = this->get_function_type();
8454   const Typed_identifier_list* parameters = NULL;
8455   if (fntype != NULL)
8456     parameters = fntype->parameters();
8457   if (this->args_ != NULL)
8458     {
8459       Typed_identifier_list::const_iterator pt;
8460       if (parameters != NULL)
8461         pt = parameters->begin();
8462       for (Expression_list::const_iterator pa = this->args_->begin();
8463            pa != this->args_->end();
8464            ++pa)
8465         {
8466           if (parameters != NULL && pt != parameters->end())
8467             {
8468               Type_context subcontext(pt->type(), false);
8469               (*pa)->determine_type(&subcontext);
8470               ++pt;
8471             }
8472           else
8473             (*pa)->determine_type_no_context();
8474         }
8475     }
8476 }
8477
8478 // Check types for parameter I.
8479
8480 bool
8481 Call_expression::check_argument_type(int i, const Type* parameter_type,
8482                                      const Type* argument_type,
8483                                      source_location argument_location,
8484                                      bool issued_error)
8485 {
8486   std::string reason;
8487   if (!Type::are_assignable(parameter_type, argument_type, &reason))
8488     {
8489       if (!issued_error)
8490         {
8491           if (reason.empty())
8492             error_at(argument_location, "argument %d has incompatible type", i);
8493           else
8494             error_at(argument_location,
8495                      "argument %d has incompatible type (%s)",
8496                      i, reason.c_str());
8497         }
8498       this->set_is_error();
8499       return false;
8500     }
8501   return true;
8502 }
8503
8504 // Check types.
8505
8506 void
8507 Call_expression::do_check_types(Gogo*)
8508 {
8509   Function_type* fntype = this->get_function_type();
8510   if (fntype == NULL)
8511     {
8512       if (!this->fn_->type()->is_error_type())
8513         this->report_error(_("expected function"));
8514       return;
8515     }
8516
8517   if (fntype->is_method())
8518     {
8519       // We don't support pointers to methods, so the function has to
8520       // be a bound method expression.
8521       Bound_method_expression* bme = this->fn_->bound_method_expression();
8522       if (bme == NULL)
8523         {
8524           this->report_error(_("method call without object"));
8525           return;
8526         }
8527       Type* first_arg_type = bme->first_argument()->type();
8528       if (first_arg_type->points_to() == NULL)
8529         {
8530           // When passing a value, we need to check that we are
8531           // permitted to copy it.
8532           std::string reason;
8533           if (!Type::are_assignable(fntype->receiver()->type(),
8534                                     first_arg_type, &reason))
8535             {
8536               if (reason.empty())
8537                 this->report_error(_("incompatible type for receiver"));
8538               else
8539                 {
8540                   error_at(this->location(),
8541                            "incompatible type for receiver (%s)",
8542                            reason.c_str());
8543                   this->set_is_error();
8544                 }
8545             }
8546         }
8547     }
8548
8549   // Note that varargs was handled by the lower_varargs() method, so
8550   // we don't have to worry about it here.
8551
8552   const Typed_identifier_list* parameters = fntype->parameters();
8553   if (this->args_ == NULL)
8554     {
8555       if (parameters != NULL && !parameters->empty())
8556         this->report_error(_("not enough arguments"));
8557     }
8558   else if (parameters == NULL)
8559     this->report_error(_("too many arguments"));
8560   else
8561     {
8562       int i = 0;
8563       Typed_identifier_list::const_iterator pt = parameters->begin();
8564       for (Expression_list::const_iterator pa = this->args_->begin();
8565            pa != this->args_->end();
8566            ++pa, ++pt, ++i)
8567         {
8568           if (pt == parameters->end())
8569             {
8570               this->report_error(_("too many arguments"));
8571               return;
8572             }
8573           this->check_argument_type(i + 1, pt->type(), (*pa)->type(),
8574                                     (*pa)->location(), false);
8575         }
8576       if (pt != parameters->end())
8577         this->report_error(_("not enough arguments"));
8578     }
8579 }
8580
8581 // Return whether we have to use a temporary variable to ensure that
8582 // we evaluate this call expression in order.  If the call returns no
8583 // results then it will inevitably be executed last.  If the call
8584 // returns more than one result then it will be used with Call_result
8585 // expressions.  So we only have to use a temporary variable if the
8586 // call returns exactly one result.
8587
8588 bool
8589 Call_expression::do_must_eval_in_order() const
8590 {
8591   return this->result_count() == 1;
8592 }
8593
8594 // Get the function and the first argument to use when calling a bound
8595 // method.
8596
8597 tree
8598 Call_expression::bound_method_function(Translate_context* context,
8599                                        Bound_method_expression* bound_method,
8600                                        tree* first_arg_ptr)
8601 {
8602   Expression* first_argument = bound_method->first_argument();
8603   tree first_arg = first_argument->get_tree(context);
8604   if (first_arg == error_mark_node)
8605     return error_mark_node;
8606
8607   // We always pass a pointer to the first argument when calling a
8608   // method.
8609   if (first_argument->type()->points_to() == NULL)
8610     {
8611       tree pointer_to_arg_type = build_pointer_type(TREE_TYPE(first_arg));
8612       if (TREE_ADDRESSABLE(TREE_TYPE(first_arg))
8613           || DECL_P(first_arg)
8614           || TREE_CODE(first_arg) == INDIRECT_REF
8615           || TREE_CODE(first_arg) == COMPONENT_REF)
8616         {
8617           first_arg = build_fold_addr_expr(first_arg);
8618           if (DECL_P(first_arg))
8619             TREE_ADDRESSABLE(first_arg) = 1;
8620         }
8621       else
8622         {
8623           tree tmp = create_tmp_var(TREE_TYPE(first_arg),
8624                                     get_name(first_arg));
8625           DECL_IGNORED_P(tmp) = 0;
8626           DECL_INITIAL(tmp) = first_arg;
8627           first_arg = build2(COMPOUND_EXPR, pointer_to_arg_type,
8628                              build1(DECL_EXPR, void_type_node, tmp),
8629                              build_fold_addr_expr(tmp));
8630           TREE_ADDRESSABLE(tmp) = 1;
8631         }
8632       if (first_arg == error_mark_node)
8633         return error_mark_node;
8634     }
8635
8636   Type* fatype = bound_method->first_argument_type();
8637   if (fatype != NULL)
8638     {
8639       if (fatype->points_to() == NULL)
8640         fatype = Type::make_pointer_type(fatype);
8641       first_arg = fold_convert(fatype->get_tree(context->gogo()), first_arg);
8642       if (first_arg == error_mark_node
8643           || TREE_TYPE(first_arg) == error_mark_node)
8644         return error_mark_node;
8645     }
8646
8647   *first_arg_ptr = first_arg;
8648
8649   return bound_method->method()->get_tree(context);
8650 }
8651
8652 // Get the function and the first argument to use when calling an
8653 // interface method.
8654
8655 tree
8656 Call_expression::interface_method_function(
8657     Translate_context* context,
8658     Interface_field_reference_expression* interface_method,
8659     tree* first_arg_ptr)
8660 {
8661   tree expr = interface_method->expr()->get_tree(context);
8662   if (expr == error_mark_node)
8663     return error_mark_node;
8664   expr = save_expr(expr);
8665   tree first_arg = interface_method->get_underlying_object_tree(context, expr);
8666   if (first_arg == error_mark_node)
8667     return error_mark_node;
8668   *first_arg_ptr = first_arg;
8669   return interface_method->get_function_tree(context, expr);
8670 }
8671
8672 // Build the call expression.
8673
8674 tree
8675 Call_expression::do_get_tree(Translate_context* context)
8676 {
8677   if (this->tree_ != NULL_TREE)
8678     return this->tree_;
8679
8680   Function_type* fntype = this->get_function_type();
8681   if (fntype == NULL)
8682     return error_mark_node;
8683
8684   if (this->fn_->is_error_expression())
8685     return error_mark_node;
8686
8687   Gogo* gogo = context->gogo();
8688   source_location location = this->location();
8689
8690   Func_expression* func = this->fn_->func_expression();
8691   Bound_method_expression* bound_method = this->fn_->bound_method_expression();
8692   Interface_field_reference_expression* interface_method =
8693     this->fn_->interface_field_reference_expression();
8694   const bool has_closure = func != NULL && func->closure() != NULL;
8695   const bool is_method = bound_method != NULL || interface_method != NULL;
8696   gcc_assert(!fntype->is_method() || is_method);
8697
8698   int nargs;
8699   tree* args;
8700   if (this->args_ == NULL || this->args_->empty())
8701     {
8702       nargs = is_method ? 1 : 0;
8703       args = nargs == 0 ? NULL : new tree[nargs];
8704     }
8705   else
8706     {
8707       const Typed_identifier_list* params = fntype->parameters();
8708       gcc_assert(params != NULL);
8709
8710       nargs = this->args_->size();
8711       int i = is_method ? 1 : 0;
8712       nargs += i;
8713       args = new tree[nargs];
8714
8715       Typed_identifier_list::const_iterator pp = params->begin();
8716       Expression_list::const_iterator pe;
8717       for (pe = this->args_->begin();
8718            pe != this->args_->end();
8719            ++pe, ++pp, ++i)
8720         {
8721           gcc_assert(pp != params->end());
8722           tree arg_val = (*pe)->get_tree(context);
8723           args[i] = Expression::convert_for_assignment(context,
8724                                                        pp->type(),
8725                                                        (*pe)->type(),
8726                                                        arg_val,
8727                                                        location);
8728           if (args[i] == error_mark_node)
8729             {
8730               delete[] args;
8731               return error_mark_node;
8732             }
8733         }
8734       gcc_assert(pp == params->end());
8735       gcc_assert(i == nargs);
8736     }
8737
8738   tree rettype = TREE_TYPE(TREE_TYPE(fntype->get_tree(gogo)));
8739   if (rettype == error_mark_node)
8740     {
8741       delete[] args;
8742       return error_mark_node;
8743     }
8744
8745   tree fn;
8746   if (has_closure)
8747     fn = func->get_tree_without_closure(gogo);
8748   else if (!is_method)
8749     fn = this->fn_->get_tree(context);
8750   else if (bound_method != NULL)
8751     fn = this->bound_method_function(context, bound_method, &args[0]);
8752   else if (interface_method != NULL)
8753     fn = this->interface_method_function(context, interface_method, &args[0]);
8754   else
8755     gcc_unreachable();
8756
8757   if (fn == error_mark_node || TREE_TYPE(fn) == error_mark_node)
8758     {
8759       delete[] args;
8760       return error_mark_node;
8761     }
8762
8763   // This is to support builtin math functions when using 80387 math.
8764   tree fndecl = fn;
8765   if (TREE_CODE(fndecl) == ADDR_EXPR)
8766     fndecl = TREE_OPERAND(fndecl, 0);
8767   tree excess_type = NULL_TREE;
8768   if (DECL_P(fndecl)
8769       && DECL_IS_BUILTIN(fndecl)
8770       && DECL_BUILT_IN_CLASS(fndecl) == BUILT_IN_NORMAL
8771       && nargs > 0
8772       && ((SCALAR_FLOAT_TYPE_P(rettype)
8773            && SCALAR_FLOAT_TYPE_P(TREE_TYPE(args[0])))
8774           || (COMPLEX_FLOAT_TYPE_P(rettype)
8775               && COMPLEX_FLOAT_TYPE_P(TREE_TYPE(args[0])))))
8776     {
8777       excess_type = excess_precision_type(TREE_TYPE(args[0]));
8778       if (excess_type != NULL_TREE)
8779         {
8780           tree excess_fndecl = mathfn_built_in(excess_type,
8781                                                DECL_FUNCTION_CODE(fndecl));
8782           if (excess_fndecl == NULL_TREE)
8783             excess_type = NULL_TREE;
8784           else
8785             {
8786               fn = build_fold_addr_expr_loc(location, excess_fndecl);
8787               for (int i = 0; i < nargs; ++i)
8788                 args[i] = ::convert(excess_type, args[i]);
8789             }
8790         }
8791     }
8792
8793   tree ret = build_call_array(excess_type != NULL_TREE ? excess_type : rettype,
8794                               fn, nargs, args);
8795   delete[] args;
8796
8797   SET_EXPR_LOCATION(ret, location);
8798
8799   if (has_closure)
8800     {
8801       tree closure_tree = func->closure()->get_tree(context);
8802       if (closure_tree != error_mark_node)
8803         CALL_EXPR_STATIC_CHAIN(ret) = closure_tree;
8804     }
8805
8806   // If this is a recursive function type which returns itself, as in
8807   //   type F func() F
8808   // we have used ptr_type_node for the return type.  Add a cast here
8809   // to the correct type.
8810   if (TREE_TYPE(ret) == ptr_type_node)
8811     {
8812       tree t = this->type()->get_tree(gogo);
8813       ret = fold_convert_loc(location, t, ret);
8814     }
8815
8816   if (excess_type != NULL_TREE)
8817     {
8818       // Calling convert here can undo our excess precision change.
8819       // That may or may not be a bug in convert_to_real.
8820       ret = build1(NOP_EXPR, rettype, ret);
8821     }
8822
8823   // If there is more than one result, we will refer to the call
8824   // multiple times.
8825   if (fntype->results() != NULL && fntype->results()->size() > 1)
8826     ret = save_expr(ret);
8827
8828   this->tree_ = ret;
8829
8830   return ret;
8831 }
8832
8833 // Make a call expression.
8834
8835 Call_expression*
8836 Expression::make_call(Expression* fn, Expression_list* args, bool is_varargs,
8837                       source_location location)
8838 {
8839   return new Call_expression(fn, args, is_varargs, location);
8840 }
8841
8842 // A single result from a call which returns multiple results.
8843
8844 class Call_result_expression : public Expression
8845 {
8846  public:
8847   Call_result_expression(Call_expression* call, unsigned int index)
8848     : Expression(EXPRESSION_CALL_RESULT, call->location()),
8849       call_(call), index_(index)
8850   { }
8851
8852  protected:
8853   int
8854   do_traverse(Traverse*);
8855
8856   Type*
8857   do_type();
8858
8859   void
8860   do_determine_type(const Type_context*);
8861
8862   void
8863   do_check_types(Gogo*);
8864
8865   Expression*
8866   do_copy()
8867   {
8868     return new Call_result_expression(this->call_->call_expression(),
8869                                       this->index_);
8870   }
8871
8872   bool
8873   do_must_eval_in_order() const
8874   { return true; }
8875
8876   tree
8877   do_get_tree(Translate_context*);
8878
8879  private:
8880   // The underlying call expression.
8881   Expression* call_;
8882   // Which result we want.
8883   unsigned int index_;
8884 };
8885
8886 // Traverse a call result.
8887
8888 int
8889 Call_result_expression::do_traverse(Traverse* traverse)
8890 {
8891   if (traverse->remember_expression(this->call_))
8892     {
8893       // We have already traversed the call expression.
8894       return TRAVERSE_CONTINUE;
8895     }
8896   return Expression::traverse(&this->call_, traverse);
8897 }
8898
8899 // Get the type.
8900
8901 Type*
8902 Call_result_expression::do_type()
8903 {
8904   if (this->classification() == EXPRESSION_ERROR)
8905     return Type::make_error_type();
8906
8907   // THIS->CALL_ can be replaced with a temporary reference due to
8908   // Call_expression::do_must_eval_in_order when there is an error.
8909   Call_expression* ce = this->call_->call_expression();
8910   if (ce == NULL)
8911     {
8912       this->set_is_error();
8913       return Type::make_error_type();
8914     }
8915   Function_type* fntype = ce->get_function_type();
8916   if (fntype == NULL)
8917     {
8918       this->set_is_error();
8919       return Type::make_error_type();
8920     }
8921   const Typed_identifier_list* results = fntype->results();
8922   if (results == NULL)
8923     {
8924       this->report_error(_("number of results does not match "
8925                            "number of values"));
8926       return Type::make_error_type();
8927     }
8928   Typed_identifier_list::const_iterator pr = results->begin();
8929   for (unsigned int i = 0; i < this->index_; ++i)
8930     {
8931       if (pr == results->end())
8932         break;
8933       ++pr;
8934     }
8935   if (pr == results->end())
8936     {
8937       this->report_error(_("number of results does not match "
8938                            "number of values"));
8939       return Type::make_error_type();
8940     }
8941   return pr->type();
8942 }
8943
8944 // Check the type.  Just make sure that we trigger the warning in
8945 // do_type.
8946
8947 void
8948 Call_result_expression::do_check_types(Gogo*)
8949 {
8950   this->type();
8951 }
8952
8953 // Determine the type.  We have nothing to do here, but the 0 result
8954 // needs to pass down to the caller.
8955
8956 void
8957 Call_result_expression::do_determine_type(const Type_context*)
8958 {
8959   if (this->index_ == 0)
8960     this->call_->determine_type_no_context();
8961 }
8962
8963 // Return the tree.
8964
8965 tree
8966 Call_result_expression::do_get_tree(Translate_context* context)
8967 {
8968   tree call_tree = this->call_->get_tree(context);
8969   if (call_tree == error_mark_node)
8970     return error_mark_node;
8971   if (TREE_CODE(TREE_TYPE(call_tree)) != RECORD_TYPE)
8972     {
8973       gcc_assert(saw_errors());
8974       return error_mark_node;
8975     }
8976   tree field = TYPE_FIELDS(TREE_TYPE(call_tree));
8977   for (unsigned int i = 0; i < this->index_; ++i)
8978     {
8979       gcc_assert(field != NULL_TREE);
8980       field = DECL_CHAIN(field);
8981     }
8982   gcc_assert(field != NULL_TREE);
8983   return build3(COMPONENT_REF, TREE_TYPE(field), call_tree, field, NULL_TREE);
8984 }
8985
8986 // Make a reference to a single result of a call which returns
8987 // multiple results.
8988
8989 Expression*
8990 Expression::make_call_result(Call_expression* call, unsigned int index)
8991 {
8992   return new Call_result_expression(call, index);
8993 }
8994
8995 // Class Index_expression.
8996
8997 // Traversal.
8998
8999 int
9000 Index_expression::do_traverse(Traverse* traverse)
9001 {
9002   if (Expression::traverse(&this->left_, traverse) == TRAVERSE_EXIT
9003       || Expression::traverse(&this->start_, traverse) == TRAVERSE_EXIT
9004       || (this->end_ != NULL
9005           && Expression::traverse(&this->end_, traverse) == TRAVERSE_EXIT))
9006     return TRAVERSE_EXIT;
9007   return TRAVERSE_CONTINUE;
9008 }
9009
9010 // Lower an index expression.  This converts the generic index
9011 // expression into an array index, a string index, or a map index.
9012
9013 Expression*
9014 Index_expression::do_lower(Gogo*, Named_object*, int)
9015 {
9016   source_location location = this->location();
9017   Expression* left = this->left_;
9018   Expression* start = this->start_;
9019   Expression* end = this->end_;
9020
9021   Type* type = left->type();
9022   if (type->is_error_type())
9023     return Expression::make_error(location);
9024   else if (type->array_type() != NULL)
9025     return Expression::make_array_index(left, start, end, location);
9026   else if (type->points_to() != NULL
9027            && type->points_to()->array_type() != NULL
9028            && !type->points_to()->is_open_array_type())
9029     {
9030       Expression* deref = Expression::make_unary(OPERATOR_MULT, left,
9031                                                  location);
9032       return Expression::make_array_index(deref, start, end, location);
9033     }
9034   else if (type->is_string_type())
9035     return Expression::make_string_index(left, start, end, location);
9036   else if (type->map_type() != NULL)
9037     {
9038       if (end != NULL)
9039         {
9040           error_at(location, "invalid slice of map");
9041           return Expression::make_error(location);
9042         }
9043       Map_index_expression* ret= Expression::make_map_index(left, start,
9044                                                             location);
9045       if (this->is_lvalue_)
9046         ret->set_is_lvalue();
9047       return ret;
9048     }
9049   else
9050     {
9051       error_at(location,
9052                "attempt to index object which is not array, string, or map");
9053       return Expression::make_error(location);
9054     }
9055 }
9056
9057 // Make an index expression.
9058
9059 Expression*
9060 Expression::make_index(Expression* left, Expression* start, Expression* end,
9061                        source_location location)
9062 {
9063   return new Index_expression(left, start, end, location);
9064 }
9065
9066 // An array index.  This is used for both indexing and slicing.
9067
9068 class Array_index_expression : public Expression
9069 {
9070  public:
9071   Array_index_expression(Expression* array, Expression* start,
9072                          Expression* end, source_location location)
9073     : Expression(EXPRESSION_ARRAY_INDEX, location),
9074       array_(array), start_(start), end_(end), type_(NULL)
9075   { }
9076
9077  protected:
9078   int
9079   do_traverse(Traverse*);
9080
9081   Type*
9082   do_type();
9083
9084   void
9085   do_determine_type(const Type_context*);
9086
9087   void
9088   do_check_types(Gogo*);
9089
9090   Expression*
9091   do_copy()
9092   {
9093     return Expression::make_array_index(this->array_->copy(),
9094                                         this->start_->copy(),
9095                                         (this->end_ == NULL
9096                                          ? NULL
9097                                          : this->end_->copy()),
9098                                         this->location());
9099   }
9100
9101   bool
9102   do_is_addressable() const;
9103
9104   void
9105   do_address_taken(bool escapes)
9106   { this->array_->address_taken(escapes); }
9107
9108   tree
9109   do_get_tree(Translate_context*);
9110
9111  private:
9112   // The array we are getting a value from.
9113   Expression* array_;
9114   // The start or only index.
9115   Expression* start_;
9116   // The end index of a slice.  This may be NULL for a simple array
9117   // index, or it may be a nil expression for the length of the array.
9118   Expression* end_;
9119   // The type of the expression.
9120   Type* type_;
9121 };
9122
9123 // Array index traversal.
9124
9125 int
9126 Array_index_expression::do_traverse(Traverse* traverse)
9127 {
9128   if (Expression::traverse(&this->array_, traverse) == TRAVERSE_EXIT)
9129     return TRAVERSE_EXIT;
9130   if (Expression::traverse(&this->start_, traverse) == TRAVERSE_EXIT)
9131     return TRAVERSE_EXIT;
9132   if (this->end_ != NULL)
9133     {
9134       if (Expression::traverse(&this->end_, traverse) == TRAVERSE_EXIT)
9135         return TRAVERSE_EXIT;
9136     }
9137   return TRAVERSE_CONTINUE;
9138 }
9139
9140 // Return the type of an array index.
9141
9142 Type*
9143 Array_index_expression::do_type()
9144 {
9145   if (this->type_ == NULL)
9146     {
9147      Array_type* type = this->array_->type()->array_type();
9148       if (type == NULL)
9149         this->type_ = Type::make_error_type();
9150       else if (this->end_ == NULL)
9151         this->type_ = type->element_type();
9152       else if (type->is_open_array_type())
9153         {
9154           // A slice of a slice has the same type as the original
9155           // slice.
9156           this->type_ = this->array_->type()->deref();
9157         }
9158       else
9159         {
9160           // A slice of an array is a slice.
9161           this->type_ = Type::make_array_type(type->element_type(), NULL);
9162         }
9163     }
9164   return this->type_;
9165 }
9166
9167 // Set the type of an array index.
9168
9169 void
9170 Array_index_expression::do_determine_type(const Type_context*)
9171 {
9172   this->array_->determine_type_no_context();
9173   Type_context subcontext(NULL, true);
9174   this->start_->determine_type(&subcontext);
9175   if (this->end_ != NULL)
9176     this->end_->determine_type(&subcontext);
9177 }
9178
9179 // Check types of an array index.
9180
9181 void
9182 Array_index_expression::do_check_types(Gogo*)
9183 {
9184   if (this->start_->type()->integer_type() == NULL)
9185     this->report_error(_("index must be integer"));
9186   if (this->end_ != NULL
9187       && this->end_->type()->integer_type() == NULL
9188       && !this->end_->is_nil_expression())
9189     this->report_error(_("slice end must be integer"));
9190
9191   Array_type* array_type = this->array_->type()->array_type();
9192   if (array_type == NULL)
9193     {
9194       gcc_assert(this->array_->type()->is_error_type());
9195       return;
9196     }
9197
9198   unsigned int int_bits =
9199     Type::lookup_integer_type("int")->integer_type()->bits();
9200
9201   Type* dummy;
9202   mpz_t lval;
9203   mpz_init(lval);
9204   bool lval_valid = (array_type->length() != NULL
9205                      && array_type->length()->integer_constant_value(true,
9206                                                                      lval,
9207                                                                      &dummy));
9208   mpz_t ival;
9209   mpz_init(ival);
9210   if (this->start_->integer_constant_value(true, ival, &dummy))
9211     {
9212       if (mpz_sgn(ival) < 0
9213           || mpz_sizeinbase(ival, 2) >= int_bits
9214           || (lval_valid
9215               && (this->end_ == NULL
9216                   ? mpz_cmp(ival, lval) >= 0
9217                   : mpz_cmp(ival, lval) > 0)))
9218         {
9219           error_at(this->start_->location(), "array index out of bounds");
9220           this->set_is_error();
9221         }
9222     }
9223   if (this->end_ != NULL && !this->end_->is_nil_expression())
9224     {
9225       if (this->end_->integer_constant_value(true, ival, &dummy))
9226         {
9227           if (mpz_sgn(ival) < 0
9228               || mpz_sizeinbase(ival, 2) >= int_bits
9229               || (lval_valid && mpz_cmp(ival, lval) > 0))
9230             {
9231               error_at(this->end_->location(), "array index out of bounds");
9232               this->set_is_error();
9233             }
9234         }
9235     }
9236   mpz_clear(ival);
9237   mpz_clear(lval);
9238
9239   // A slice of an array requires an addressable array.  A slice of a
9240   // slice is always possible.
9241   if (this->end_ != NULL
9242       && !array_type->is_open_array_type()
9243       && !this->array_->is_addressable())
9244     this->report_error(_("array is not addressable"));
9245 }
9246
9247 // Return whether this expression is addressable.
9248
9249 bool
9250 Array_index_expression::do_is_addressable() const
9251 {
9252   // A slice expression is not addressable.
9253   if (this->end_ != NULL)
9254     return false;
9255
9256   // An index into a slice is addressable.
9257   if (this->array_->type()->is_open_array_type())
9258     return true;
9259
9260   // An index into an array is addressable if the array is
9261   // addressable.
9262   return this->array_->is_addressable();
9263 }
9264
9265 // Get a tree for an array index.
9266
9267 tree
9268 Array_index_expression::do_get_tree(Translate_context* context)
9269 {
9270   Gogo* gogo = context->gogo();
9271   source_location loc = this->location();
9272
9273   Array_type* array_type = this->array_->type()->array_type();
9274   if (array_type == NULL)
9275     {
9276       gcc_assert(this->array_->type()->is_error_type());
9277       return error_mark_node;
9278     }
9279
9280   tree type_tree = array_type->get_tree(gogo);
9281   if (type_tree == error_mark_node)
9282     return error_mark_node;
9283
9284   tree array_tree = this->array_->get_tree(context);
9285   if (array_tree == error_mark_node)
9286     return error_mark_node;
9287
9288   if (array_type->length() == NULL && !DECL_P(array_tree))
9289     array_tree = save_expr(array_tree);
9290   tree length_tree = array_type->length_tree(gogo, array_tree);
9291   if (length_tree == error_mark_node)
9292     return error_mark_node;
9293   length_tree = save_expr(length_tree);
9294   tree length_type = TREE_TYPE(length_tree);
9295
9296   tree bad_index = boolean_false_node;
9297
9298   tree start_tree = this->start_->get_tree(context);
9299   if (start_tree == error_mark_node)
9300     return error_mark_node;
9301   if (!DECL_P(start_tree))
9302     start_tree = save_expr(start_tree);
9303   if (!INTEGRAL_TYPE_P(TREE_TYPE(start_tree)))
9304     start_tree = convert_to_integer(length_type, start_tree);
9305
9306   bad_index = Expression::check_bounds(start_tree, length_type, bad_index,
9307                                        loc);
9308
9309   start_tree = fold_convert_loc(loc, length_type, start_tree);
9310   bad_index = fold_build2_loc(loc, TRUTH_OR_EXPR, boolean_type_node, bad_index,
9311                               fold_build2_loc(loc,
9312                                               (this->end_ == NULL
9313                                                ? GE_EXPR
9314                                                : GT_EXPR),
9315                                               boolean_type_node, start_tree,
9316                                               length_tree));
9317
9318   int code = (array_type->length() != NULL
9319               ? (this->end_ == NULL
9320                  ? RUNTIME_ERROR_ARRAY_INDEX_OUT_OF_BOUNDS
9321                  : RUNTIME_ERROR_ARRAY_SLICE_OUT_OF_BOUNDS)
9322               : (this->end_ == NULL
9323                  ? RUNTIME_ERROR_SLICE_INDEX_OUT_OF_BOUNDS
9324                  : RUNTIME_ERROR_SLICE_SLICE_OUT_OF_BOUNDS));
9325   tree crash = Gogo::runtime_error(code, loc);
9326
9327   if (this->end_ == NULL)
9328     {
9329       // Simple array indexing.  This has to return an l-value, so
9330       // wrap the index check into START_TREE.
9331       start_tree = build2(COMPOUND_EXPR, TREE_TYPE(start_tree),
9332                           build3(COND_EXPR, void_type_node,
9333                                  bad_index, crash, NULL_TREE),
9334                           start_tree);
9335       start_tree = fold_convert_loc(loc, sizetype, start_tree);
9336
9337       if (array_type->length() != NULL)
9338         {
9339           // Fixed array.
9340           return build4(ARRAY_REF, TREE_TYPE(type_tree), array_tree,
9341                         start_tree, NULL_TREE, NULL_TREE);
9342         }
9343       else
9344         {
9345           // Open array.
9346           tree values = array_type->value_pointer_tree(gogo, array_tree);
9347           tree element_type_tree = array_type->element_type()->get_tree(gogo);
9348           if (element_type_tree == error_mark_node)
9349             return error_mark_node;
9350           tree element_size = TYPE_SIZE_UNIT(element_type_tree);
9351           tree offset = fold_build2_loc(loc, MULT_EXPR, sizetype,
9352                                         start_tree, element_size);
9353           tree ptr = fold_build2_loc(loc, POINTER_PLUS_EXPR,
9354                                      TREE_TYPE(values), values, offset);
9355           return build_fold_indirect_ref(ptr);
9356         }
9357     }
9358
9359   // Array slice.
9360
9361   tree capacity_tree = array_type->capacity_tree(gogo, array_tree);
9362   if (capacity_tree == error_mark_node)
9363     return error_mark_node;
9364   capacity_tree = fold_convert_loc(loc, length_type, capacity_tree);
9365
9366   tree end_tree;
9367   if (this->end_->is_nil_expression())
9368     end_tree = length_tree;
9369   else
9370     {
9371       end_tree = this->end_->get_tree(context);
9372       if (end_tree == error_mark_node)
9373         return error_mark_node;
9374       if (!DECL_P(end_tree))
9375         end_tree = save_expr(end_tree);
9376       if (!INTEGRAL_TYPE_P(TREE_TYPE(end_tree)))
9377         end_tree = convert_to_integer(length_type, end_tree);
9378
9379       bad_index = Expression::check_bounds(end_tree, length_type, bad_index,
9380                                            loc);
9381
9382       end_tree = fold_convert_loc(loc, length_type, end_tree);
9383
9384       capacity_tree = save_expr(capacity_tree);
9385       tree bad_end = fold_build2_loc(loc, TRUTH_OR_EXPR, boolean_type_node,
9386                                      fold_build2_loc(loc, LT_EXPR,
9387                                                      boolean_type_node,
9388                                                      end_tree, start_tree),
9389                                      fold_build2_loc(loc, GT_EXPR,
9390                                                      boolean_type_node,
9391                                                      end_tree, capacity_tree));
9392       bad_index = fold_build2_loc(loc, TRUTH_OR_EXPR, boolean_type_node,
9393                                   bad_index, bad_end);
9394     }
9395
9396   tree element_type_tree = array_type->element_type()->get_tree(gogo);
9397   if (element_type_tree == error_mark_node)
9398     return error_mark_node;
9399   tree element_size = TYPE_SIZE_UNIT(element_type_tree);
9400
9401   tree offset = fold_build2_loc(loc, MULT_EXPR, sizetype,
9402                                 fold_convert_loc(loc, sizetype, start_tree),
9403                                 element_size);
9404
9405   tree value_pointer = array_type->value_pointer_tree(gogo, array_tree);
9406   if (value_pointer == error_mark_node)
9407     return error_mark_node;
9408
9409   value_pointer = fold_build2_loc(loc, POINTER_PLUS_EXPR,
9410                                   TREE_TYPE(value_pointer),
9411                                   value_pointer, offset);
9412
9413   tree result_length_tree = fold_build2_loc(loc, MINUS_EXPR, length_type,
9414                                             end_tree, start_tree);
9415
9416   tree result_capacity_tree = fold_build2_loc(loc, MINUS_EXPR, length_type,
9417                                               capacity_tree, start_tree);
9418
9419   tree struct_tree = this->type()->get_tree(gogo);
9420   gcc_assert(TREE_CODE(struct_tree) == RECORD_TYPE);
9421
9422   VEC(constructor_elt,gc)* init = VEC_alloc(constructor_elt, gc, 3);
9423
9424   constructor_elt* elt = VEC_quick_push(constructor_elt, init, NULL);
9425   tree field = TYPE_FIELDS(struct_tree);
9426   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__values") == 0);
9427   elt->index = field;
9428   elt->value = value_pointer;
9429
9430   elt = VEC_quick_push(constructor_elt, init, NULL);
9431   field = DECL_CHAIN(field);
9432   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__count") == 0);
9433   elt->index = field;
9434   elt->value = fold_convert_loc(loc, TREE_TYPE(field), result_length_tree);
9435
9436   elt = VEC_quick_push(constructor_elt, init, NULL);
9437   field = DECL_CHAIN(field);
9438   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__capacity") == 0);
9439   elt->index = field;
9440   elt->value = fold_convert_loc(loc, TREE_TYPE(field), result_capacity_tree);
9441
9442   tree constructor = build_constructor(struct_tree, init);
9443
9444   if (TREE_CONSTANT(value_pointer)
9445       && TREE_CONSTANT(result_length_tree)
9446       && TREE_CONSTANT(result_capacity_tree))
9447     TREE_CONSTANT(constructor) = 1;
9448
9449   return fold_build2_loc(loc, COMPOUND_EXPR, TREE_TYPE(constructor),
9450                          build3(COND_EXPR, void_type_node,
9451                                 bad_index, crash, NULL_TREE),
9452                          constructor);
9453 }
9454
9455 // Make an array index expression.  END may be NULL.
9456
9457 Expression*
9458 Expression::make_array_index(Expression* array, Expression* start,
9459                              Expression* end, source_location location)
9460 {
9461   // Taking a slice of a composite literal requires moving the literal
9462   // onto the heap.
9463   if (end != NULL && array->is_composite_literal())
9464     {
9465       array = Expression::make_heap_composite(array, location);
9466       array = Expression::make_unary(OPERATOR_MULT, array, location);
9467     }
9468   return new Array_index_expression(array, start, end, location);
9469 }
9470
9471 // A string index.  This is used for both indexing and slicing.
9472
9473 class String_index_expression : public Expression
9474 {
9475  public:
9476   String_index_expression(Expression* string, Expression* start,
9477                           Expression* end, source_location location)
9478     : Expression(EXPRESSION_STRING_INDEX, location),
9479       string_(string), start_(start), end_(end)
9480   { }
9481
9482  protected:
9483   int
9484   do_traverse(Traverse*);
9485
9486   Type*
9487   do_type();
9488
9489   void
9490   do_determine_type(const Type_context*);
9491
9492   void
9493   do_check_types(Gogo*);
9494
9495   Expression*
9496   do_copy()
9497   {
9498     return Expression::make_string_index(this->string_->copy(),
9499                                          this->start_->copy(),
9500                                          (this->end_ == NULL
9501                                           ? NULL
9502                                           : this->end_->copy()),
9503                                          this->location());
9504   }
9505
9506   tree
9507   do_get_tree(Translate_context*);
9508
9509  private:
9510   // The string we are getting a value from.
9511   Expression* string_;
9512   // The start or only index.
9513   Expression* start_;
9514   // The end index of a slice.  This may be NULL for a single index,
9515   // or it may be a nil expression for the length of the string.
9516   Expression* end_;
9517 };
9518
9519 // String index traversal.
9520
9521 int
9522 String_index_expression::do_traverse(Traverse* traverse)
9523 {
9524   if (Expression::traverse(&this->string_, traverse) == TRAVERSE_EXIT)
9525     return TRAVERSE_EXIT;
9526   if (Expression::traverse(&this->start_, traverse) == TRAVERSE_EXIT)
9527     return TRAVERSE_EXIT;
9528   if (this->end_ != NULL)
9529     {
9530       if (Expression::traverse(&this->end_, traverse) == TRAVERSE_EXIT)
9531         return TRAVERSE_EXIT;
9532     }
9533   return TRAVERSE_CONTINUE;
9534 }
9535
9536 // Return the type of a string index.
9537
9538 Type*
9539 String_index_expression::do_type()
9540 {
9541   if (this->end_ == NULL)
9542     return Type::lookup_integer_type("uint8");
9543   else
9544     return this->string_->type();
9545 }
9546
9547 // Determine the type of a string index.
9548
9549 void
9550 String_index_expression::do_determine_type(const Type_context*)
9551 {
9552   this->string_->determine_type_no_context();
9553   Type_context subcontext(NULL, true);
9554   this->start_->determine_type(&subcontext);
9555   if (this->end_ != NULL)
9556     this->end_->determine_type(&subcontext);
9557 }
9558
9559 // Check types of a string index.
9560
9561 void
9562 String_index_expression::do_check_types(Gogo*)
9563 {
9564   if (this->start_->type()->integer_type() == NULL)
9565     this->report_error(_("index must be integer"));
9566   if (this->end_ != NULL
9567       && this->end_->type()->integer_type() == NULL
9568       && !this->end_->is_nil_expression())
9569     this->report_error(_("slice end must be integer"));
9570
9571   std::string sval;
9572   bool sval_valid = this->string_->string_constant_value(&sval);
9573
9574   mpz_t ival;
9575   mpz_init(ival);
9576   Type* dummy;
9577   if (this->start_->integer_constant_value(true, ival, &dummy))
9578     {
9579       if (mpz_sgn(ival) < 0
9580           || (sval_valid && mpz_cmp_ui(ival, sval.length()) >= 0))
9581         {
9582           error_at(this->start_->location(), "string index out of bounds");
9583           this->set_is_error();
9584         }
9585     }
9586   if (this->end_ != NULL && !this->end_->is_nil_expression())
9587     {
9588       if (this->end_->integer_constant_value(true, ival, &dummy))
9589         {
9590           if (mpz_sgn(ival) < 0
9591               || (sval_valid && mpz_cmp_ui(ival, sval.length()) > 0))
9592             {
9593               error_at(this->end_->location(), "string index out of bounds");
9594               this->set_is_error();
9595             }
9596         }
9597     }
9598   mpz_clear(ival);
9599 }
9600
9601 // Get a tree for a string index.
9602
9603 tree
9604 String_index_expression::do_get_tree(Translate_context* context)
9605 {
9606   source_location loc = this->location();
9607
9608   tree string_tree = this->string_->get_tree(context);
9609   if (string_tree == error_mark_node)
9610     return error_mark_node;
9611
9612   if (this->string_->type()->points_to() != NULL)
9613     string_tree = build_fold_indirect_ref(string_tree);
9614   if (!DECL_P(string_tree))
9615     string_tree = save_expr(string_tree);
9616   tree string_type = TREE_TYPE(string_tree);
9617
9618   tree length_tree = String_type::length_tree(context->gogo(), string_tree);
9619   length_tree = save_expr(length_tree);
9620   tree length_type = TREE_TYPE(length_tree);
9621
9622   tree bad_index = boolean_false_node;
9623
9624   tree start_tree = this->start_->get_tree(context);
9625   if (start_tree == error_mark_node)
9626     return error_mark_node;
9627   if (!DECL_P(start_tree))
9628     start_tree = save_expr(start_tree);
9629   if (!INTEGRAL_TYPE_P(TREE_TYPE(start_tree)))
9630     start_tree = convert_to_integer(length_type, start_tree);
9631
9632   bad_index = Expression::check_bounds(start_tree, length_type, bad_index,
9633                                        loc);
9634
9635   start_tree = fold_convert_loc(loc, length_type, start_tree);
9636
9637   int code = (this->end_ == NULL
9638               ? RUNTIME_ERROR_STRING_INDEX_OUT_OF_BOUNDS
9639               : RUNTIME_ERROR_STRING_SLICE_OUT_OF_BOUNDS);
9640   tree crash = Gogo::runtime_error(code, loc);
9641
9642   if (this->end_ == NULL)
9643     {
9644       bad_index = fold_build2_loc(loc, TRUTH_OR_EXPR, boolean_type_node,
9645                                   bad_index,
9646                                   fold_build2_loc(loc, GE_EXPR,
9647                                                   boolean_type_node,
9648                                                   start_tree, length_tree));
9649
9650       tree bytes_tree = String_type::bytes_tree(context->gogo(), string_tree);
9651       tree ptr = fold_build2_loc(loc, POINTER_PLUS_EXPR, TREE_TYPE(bytes_tree),
9652                                  bytes_tree,
9653                                  fold_convert_loc(loc, sizetype, start_tree));
9654       tree index = build_fold_indirect_ref_loc(loc, ptr);
9655
9656       return build2(COMPOUND_EXPR, TREE_TYPE(index),
9657                     build3(COND_EXPR, void_type_node,
9658                            bad_index, crash, NULL_TREE),
9659                     index);
9660     }
9661   else
9662     {
9663       tree end_tree;
9664       if (this->end_->is_nil_expression())
9665         end_tree = build_int_cst(length_type, -1);
9666       else
9667         {
9668           end_tree = this->end_->get_tree(context);
9669           if (end_tree == error_mark_node)
9670             return error_mark_node;
9671           if (!DECL_P(end_tree))
9672             end_tree = save_expr(end_tree);
9673           if (!INTEGRAL_TYPE_P(TREE_TYPE(end_tree)))
9674             end_tree = convert_to_integer(length_type, end_tree);
9675
9676           bad_index = Expression::check_bounds(end_tree, length_type,
9677                                                bad_index, loc);
9678
9679           end_tree = fold_convert_loc(loc, length_type, end_tree);
9680         }
9681
9682       static tree strslice_fndecl;
9683       tree ret = Gogo::call_builtin(&strslice_fndecl,
9684                                     loc,
9685                                     "__go_string_slice",
9686                                     3,
9687                                     string_type,
9688                                     string_type,
9689                                     string_tree,
9690                                     length_type,
9691                                     start_tree,
9692                                     length_type,
9693                                     end_tree);
9694       if (ret == error_mark_node)
9695         return error_mark_node;
9696       // This will panic if the bounds are out of range for the
9697       // string.
9698       TREE_NOTHROW(strslice_fndecl) = 0;
9699
9700       if (bad_index == boolean_false_node)
9701         return ret;
9702       else
9703         return build2(COMPOUND_EXPR, TREE_TYPE(ret),
9704                       build3(COND_EXPR, void_type_node,
9705                              bad_index, crash, NULL_TREE),
9706                       ret);
9707     }
9708 }
9709
9710 // Make a string index expression.  END may be NULL.
9711
9712 Expression*
9713 Expression::make_string_index(Expression* string, Expression* start,
9714                               Expression* end, source_location location)
9715 {
9716   return new String_index_expression(string, start, end, location);
9717 }
9718
9719 // Class Map_index.
9720
9721 // Get the type of the map.
9722
9723 Map_type*
9724 Map_index_expression::get_map_type() const
9725 {
9726   Map_type* mt = this->map_->type()->deref()->map_type();
9727   if (mt == NULL)
9728     gcc_assert(saw_errors());
9729   return mt;
9730 }
9731
9732 // Map index traversal.
9733
9734 int
9735 Map_index_expression::do_traverse(Traverse* traverse)
9736 {
9737   if (Expression::traverse(&this->map_, traverse) == TRAVERSE_EXIT)
9738     return TRAVERSE_EXIT;
9739   return Expression::traverse(&this->index_, traverse);
9740 }
9741
9742 // Return the type of a map index.
9743
9744 Type*
9745 Map_index_expression::do_type()
9746 {
9747   Map_type* mt = this->get_map_type();
9748   if (mt == NULL)
9749     return Type::make_error_type();
9750   Type* type = mt->val_type();
9751   // If this map index is in a tuple assignment, we actually return a
9752   // pointer to the value type.  Tuple_map_assignment_statement is
9753   // responsible for handling this correctly.  We need to get the type
9754   // right in case this gets assigned to a temporary variable.
9755   if (this->is_in_tuple_assignment_)
9756     type = Type::make_pointer_type(type);
9757   return type;
9758 }
9759
9760 // Fix the type of a map index.
9761
9762 void
9763 Map_index_expression::do_determine_type(const Type_context*)
9764 {
9765   this->map_->determine_type_no_context();
9766   Map_type* mt = this->get_map_type();
9767   Type* key_type = mt == NULL ? NULL : mt->key_type();
9768   Type_context subcontext(key_type, false);
9769   this->index_->determine_type(&subcontext);
9770 }
9771
9772 // Check types of a map index.
9773
9774 void
9775 Map_index_expression::do_check_types(Gogo*)
9776 {
9777   std::string reason;
9778   Map_type* mt = this->get_map_type();
9779   if (mt == NULL)
9780     return;
9781   if (!Type::are_assignable(mt->key_type(), this->index_->type(), &reason))
9782     {
9783       if (reason.empty())
9784         this->report_error(_("incompatible type for map index"));
9785       else
9786         {
9787           error_at(this->location(), "incompatible type for map index (%s)",
9788                    reason.c_str());
9789           this->set_is_error();
9790         }
9791     }
9792 }
9793
9794 // Get a tree for a map index.
9795
9796 tree
9797 Map_index_expression::do_get_tree(Translate_context* context)
9798 {
9799   Map_type* type = this->get_map_type();
9800   if (type == NULL)
9801     return error_mark_node;
9802
9803   tree valptr = this->get_value_pointer(context, this->is_lvalue_);
9804   if (valptr == error_mark_node)
9805     return error_mark_node;
9806   valptr = save_expr(valptr);
9807
9808   tree val_type_tree = TREE_TYPE(TREE_TYPE(valptr));
9809
9810   if (this->is_lvalue_)
9811     return build_fold_indirect_ref(valptr);
9812   else if (this->is_in_tuple_assignment_)
9813     {
9814       // Tuple_map_assignment_statement is responsible for using this
9815       // appropriately.
9816       return valptr;
9817     }
9818   else
9819     {
9820       return fold_build3(COND_EXPR, val_type_tree,
9821                          fold_build2(EQ_EXPR, boolean_type_node, valptr,
9822                                      fold_convert(TREE_TYPE(valptr),
9823                                                   null_pointer_node)),
9824                          type->val_type()->get_init_tree(context->gogo(),
9825                                                          false),
9826                          build_fold_indirect_ref(valptr));
9827     }
9828 }
9829
9830 // Get a tree for the map index.  This returns a tree which evaluates
9831 // to a pointer to a value.  The pointer will be NULL if the key is
9832 // not in the map.
9833
9834 tree
9835 Map_index_expression::get_value_pointer(Translate_context* context,
9836                                         bool insert)
9837 {
9838   Map_type* type = this->get_map_type();
9839   if (type == NULL)
9840     return error_mark_node;
9841
9842   tree map_tree = this->map_->get_tree(context);
9843   tree index_tree = this->index_->get_tree(context);
9844   index_tree = Expression::convert_for_assignment(context, type->key_type(),
9845                                                   this->index_->type(),
9846                                                   index_tree,
9847                                                   this->location());
9848   if (map_tree == error_mark_node || index_tree == error_mark_node)
9849     return error_mark_node;
9850
9851   if (this->map_->type()->points_to() != NULL)
9852     map_tree = build_fold_indirect_ref(map_tree);
9853
9854   // We need to pass in a pointer to the key, so stuff it into a
9855   // variable.
9856   tree tmp = create_tmp_var(TREE_TYPE(index_tree), get_name(index_tree));
9857   DECL_IGNORED_P(tmp) = 0;
9858   DECL_INITIAL(tmp) = index_tree;
9859   tree make_tmp = build1(DECL_EXPR, void_type_node, tmp);
9860   tree tmpref = fold_convert(const_ptr_type_node, build_fold_addr_expr(tmp));
9861   TREE_ADDRESSABLE(tmp) = 1;
9862
9863   static tree map_index_fndecl;
9864   tree call = Gogo::call_builtin(&map_index_fndecl,
9865                                  this->location(),
9866                                  "__go_map_index",
9867                                  3,
9868                                  const_ptr_type_node,
9869                                  TREE_TYPE(map_tree),
9870                                  map_tree,
9871                                  const_ptr_type_node,
9872                                  tmpref,
9873                                  boolean_type_node,
9874                                  (insert
9875                                   ? boolean_true_node
9876                                   : boolean_false_node));
9877   if (call == error_mark_node)
9878     return error_mark_node;
9879   // This can panic on a map of interface type if the interface holds
9880   // an uncomparable or unhashable type.
9881   TREE_NOTHROW(map_index_fndecl) = 0;
9882
9883   tree val_type_tree = type->val_type()->get_tree(context->gogo());
9884   if (val_type_tree == error_mark_node)
9885     return error_mark_node;
9886   tree ptr_val_type_tree = build_pointer_type(val_type_tree);
9887
9888   return build2(COMPOUND_EXPR, ptr_val_type_tree,
9889                 make_tmp,
9890                 fold_convert(ptr_val_type_tree, call));
9891 }
9892
9893 // Make a map index expression.
9894
9895 Map_index_expression*
9896 Expression::make_map_index(Expression* map, Expression* index,
9897                            source_location location)
9898 {
9899   return new Map_index_expression(map, index, location);
9900 }
9901
9902 // Class Field_reference_expression.
9903
9904 // Return the type of a field reference.
9905
9906 Type*
9907 Field_reference_expression::do_type()
9908 {
9909   Struct_type* struct_type = this->expr_->type()->struct_type();
9910   gcc_assert(struct_type != NULL);
9911   return struct_type->field(this->field_index_)->type();
9912 }
9913
9914 // Check the types for a field reference.
9915
9916 void
9917 Field_reference_expression::do_check_types(Gogo*)
9918 {
9919   Struct_type* struct_type = this->expr_->type()->struct_type();
9920   gcc_assert(struct_type != NULL);
9921   gcc_assert(struct_type->field(this->field_index_) != NULL);
9922 }
9923
9924 // Get a tree for a field reference.
9925
9926 tree
9927 Field_reference_expression::do_get_tree(Translate_context* context)
9928 {
9929   tree struct_tree = this->expr_->get_tree(context);
9930   if (struct_tree == error_mark_node
9931       || TREE_TYPE(struct_tree) == error_mark_node)
9932     return error_mark_node;
9933   gcc_assert(TREE_CODE(TREE_TYPE(struct_tree)) == RECORD_TYPE);
9934   tree field = TYPE_FIELDS(TREE_TYPE(struct_tree));
9935   if (field == NULL_TREE)
9936     {
9937       // This can happen for a type which refers to itself indirectly
9938       // and then turns out to be erroneous.
9939       gcc_assert(saw_errors());
9940       return error_mark_node;
9941     }
9942   for (unsigned int i = this->field_index_; i > 0; --i)
9943     {
9944       field = DECL_CHAIN(field);
9945       gcc_assert(field != NULL_TREE);
9946     }
9947   return build3(COMPONENT_REF, TREE_TYPE(field), struct_tree, field,
9948                 NULL_TREE);
9949 }
9950
9951 // Make a reference to a qualified identifier in an expression.
9952
9953 Field_reference_expression*
9954 Expression::make_field_reference(Expression* expr, unsigned int field_index,
9955                                  source_location location)
9956 {
9957   return new Field_reference_expression(expr, field_index, location);
9958 }
9959
9960 // Class Interface_field_reference_expression.
9961
9962 // Return a tree for the pointer to the function to call.
9963
9964 tree
9965 Interface_field_reference_expression::get_function_tree(Translate_context*,
9966                                                         tree expr)
9967 {
9968   if (this->expr_->type()->points_to() != NULL)
9969     expr = build_fold_indirect_ref(expr);
9970
9971   tree expr_type = TREE_TYPE(expr);
9972   gcc_assert(TREE_CODE(expr_type) == RECORD_TYPE);
9973
9974   tree field = TYPE_FIELDS(expr_type);
9975   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__methods") == 0);
9976
9977   tree table = build3(COMPONENT_REF, TREE_TYPE(field), expr, field, NULL_TREE);
9978   gcc_assert(POINTER_TYPE_P(TREE_TYPE(table)));
9979
9980   table = build_fold_indirect_ref(table);
9981   gcc_assert(TREE_CODE(TREE_TYPE(table)) == RECORD_TYPE);
9982
9983   std::string name = Gogo::unpack_hidden_name(this->name_);
9984   for (field = DECL_CHAIN(TYPE_FIELDS(TREE_TYPE(table)));
9985        field != NULL_TREE;
9986        field = DECL_CHAIN(field))
9987     {
9988       if (name == IDENTIFIER_POINTER(DECL_NAME(field)))
9989         break;
9990     }
9991   gcc_assert(field != NULL_TREE);
9992
9993   return build3(COMPONENT_REF, TREE_TYPE(field), table, field, NULL_TREE);
9994 }
9995
9996 // Return a tree for the first argument to pass to the interface
9997 // function.
9998
9999 tree
10000 Interface_field_reference_expression::get_underlying_object_tree(
10001     Translate_context*,
10002     tree expr)
10003 {
10004   if (this->expr_->type()->points_to() != NULL)
10005     expr = build_fold_indirect_ref(expr);
10006
10007   tree expr_type = TREE_TYPE(expr);
10008   gcc_assert(TREE_CODE(expr_type) == RECORD_TYPE);
10009
10010   tree field = DECL_CHAIN(TYPE_FIELDS(expr_type));
10011   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__object") == 0);
10012
10013   return build3(COMPONENT_REF, TREE_TYPE(field), expr, field, NULL_TREE);
10014 }
10015
10016 // Traversal.
10017
10018 int
10019 Interface_field_reference_expression::do_traverse(Traverse* traverse)
10020 {
10021   return Expression::traverse(&this->expr_, traverse);
10022 }
10023
10024 // Return the type of an interface field reference.
10025
10026 Type*
10027 Interface_field_reference_expression::do_type()
10028 {
10029   Type* expr_type = this->expr_->type();
10030
10031   Type* points_to = expr_type->points_to();
10032   if (points_to != NULL)
10033     expr_type = points_to;
10034
10035   Interface_type* interface_type = expr_type->interface_type();
10036   if (interface_type == NULL)
10037     return Type::make_error_type();
10038
10039   const Typed_identifier* method = interface_type->find_method(this->name_);
10040   if (method == NULL)
10041     return Type::make_error_type();
10042
10043   return method->type();
10044 }
10045
10046 // Determine types.
10047
10048 void
10049 Interface_field_reference_expression::do_determine_type(const Type_context*)
10050 {
10051   this->expr_->determine_type_no_context();
10052 }
10053
10054 // Check the types for an interface field reference.
10055
10056 void
10057 Interface_field_reference_expression::do_check_types(Gogo*)
10058 {
10059   Type* type = this->expr_->type();
10060
10061   Type* points_to = type->points_to();
10062   if (points_to != NULL)
10063     type = points_to;
10064
10065   Interface_type* interface_type = type->interface_type();
10066   if (interface_type == NULL)
10067     this->report_error(_("expected interface or pointer to interface"));
10068   else
10069     {
10070       const Typed_identifier* method =
10071         interface_type->find_method(this->name_);
10072       if (method == NULL)
10073         {
10074           error_at(this->location(), "method %qs not in interface",
10075                    Gogo::message_name(this->name_).c_str());
10076           this->set_is_error();
10077         }
10078     }
10079 }
10080
10081 // Get a tree for a reference to a field in an interface.  There is no
10082 // standard tree type representation for this: it's a function
10083 // attached to its first argument, like a Bound_method_expression.
10084 // The only places it may currently be used are in a Call_expression
10085 // or a Go_statement, which will take it apart directly.  So this has
10086 // nothing to do at present.
10087
10088 tree
10089 Interface_field_reference_expression::do_get_tree(Translate_context*)
10090 {
10091   gcc_unreachable();
10092 }
10093
10094 // Make a reference to a field in an interface.
10095
10096 Expression*
10097 Expression::make_interface_field_reference(Expression* expr,
10098                                            const std::string& field,
10099                                            source_location location)
10100 {
10101   return new Interface_field_reference_expression(expr, field, location);
10102 }
10103
10104 // A general selector.  This is a Parser_expression for LEFT.NAME.  It
10105 // is lowered after we know the type of the left hand side.
10106
10107 class Selector_expression : public Parser_expression
10108 {
10109  public:
10110   Selector_expression(Expression* left, const std::string& name,
10111                       source_location location)
10112     : Parser_expression(EXPRESSION_SELECTOR, location),
10113       left_(left), name_(name)
10114   { }
10115
10116  protected:
10117   int
10118   do_traverse(Traverse* traverse)
10119   { return Expression::traverse(&this->left_, traverse); }
10120
10121   Expression*
10122   do_lower(Gogo*, Named_object*, int);
10123
10124   Expression*
10125   do_copy()
10126   {
10127     return new Selector_expression(this->left_->copy(), this->name_,
10128                                    this->location());
10129   }
10130
10131  private:
10132   Expression*
10133   lower_method_expression(Gogo*);
10134
10135   // The expression on the left hand side.
10136   Expression* left_;
10137   // The name on the right hand side.
10138   std::string name_;
10139 };
10140
10141 // Lower a selector expression once we know the real type of the left
10142 // hand side.
10143
10144 Expression*
10145 Selector_expression::do_lower(Gogo* gogo, Named_object*, int)
10146 {
10147   Expression* left = this->left_;
10148   if (left->is_type_expression())
10149     return this->lower_method_expression(gogo);
10150   return Type::bind_field_or_method(gogo, left->type(), left, this->name_,
10151                                     this->location());
10152 }
10153
10154 // Lower a method expression T.M or (*T).M.  We turn this into a
10155 // function literal.
10156
10157 Expression*
10158 Selector_expression::lower_method_expression(Gogo* gogo)
10159 {
10160   source_location location = this->location();
10161   Type* type = this->left_->type();
10162   const std::string& name(this->name_);
10163
10164   bool is_pointer;
10165   if (type->points_to() == NULL)
10166     is_pointer = false;
10167   else
10168     {
10169       is_pointer = true;
10170       type = type->points_to();
10171     }
10172   Named_type* nt = type->named_type();
10173   if (nt == NULL)
10174     {
10175       error_at(location,
10176                ("method expression requires named type or "
10177                 "pointer to named type"));
10178       return Expression::make_error(location);
10179     }
10180
10181   bool is_ambiguous;
10182   Method* method = nt->method_function(name, &is_ambiguous);
10183   if (method == NULL)
10184     {
10185       if (!is_ambiguous)
10186         error_at(location, "type %<%s%> has no method %<%s%>",
10187                  nt->message_name().c_str(),
10188                  Gogo::message_name(name).c_str());
10189       else
10190         error_at(location, "method %<%s%> is ambiguous in type %<%s%>",
10191                  Gogo::message_name(name).c_str(),
10192                  nt->message_name().c_str());
10193       return Expression::make_error(location);
10194     }
10195
10196   if (!is_pointer && !method->is_value_method())
10197     {
10198       error_at(location, "method requires pointer (use %<(*%s).%s)%>",
10199                nt->message_name().c_str(),
10200                Gogo::message_name(name).c_str());
10201       return Expression::make_error(location);
10202     }
10203
10204   // Build a new function type in which the receiver becomes the first
10205   // argument.
10206   Function_type* method_type = method->type();
10207   gcc_assert(method_type->is_method());
10208
10209   const char* const receiver_name = "$this";
10210   Typed_identifier_list* parameters = new Typed_identifier_list();
10211   parameters->push_back(Typed_identifier(receiver_name, this->left_->type(),
10212                                          location));
10213
10214   const Typed_identifier_list* method_parameters = method_type->parameters();
10215   if (method_parameters != NULL)
10216     {
10217       for (Typed_identifier_list::const_iterator p = method_parameters->begin();
10218            p != method_parameters->end();
10219            ++p)
10220         parameters->push_back(*p);
10221     }
10222
10223   const Typed_identifier_list* method_results = method_type->results();
10224   Typed_identifier_list* results;
10225   if (method_results == NULL)
10226     results = NULL;
10227   else
10228     {
10229       results = new Typed_identifier_list();
10230       for (Typed_identifier_list::const_iterator p = method_results->begin();
10231            p != method_results->end();
10232            ++p)
10233         results->push_back(*p);
10234     }
10235
10236   Function_type* fntype = Type::make_function_type(NULL, parameters, results,
10237                                                    location);
10238   if (method_type->is_varargs())
10239     fntype->set_is_varargs();
10240
10241   // We generate methods which always takes a pointer to the receiver
10242   // as their first argument.  If this is for a pointer type, we can
10243   // simply reuse the existing function.  We use an internal hack to
10244   // get the right type.
10245
10246   if (is_pointer)
10247     {
10248       Named_object* mno = (method->needs_stub_method()
10249                            ? method->stub_object()
10250                            : method->named_object());
10251       Expression* f = Expression::make_func_reference(mno, NULL, location);
10252       f = Expression::make_cast(fntype, f, location);
10253       Type_conversion_expression* tce =
10254         static_cast<Type_conversion_expression*>(f);
10255       tce->set_may_convert_function_types();
10256       return f;
10257     }
10258
10259   Named_object* no = gogo->start_function(Gogo::thunk_name(), fntype, false,
10260                                           location);
10261
10262   Named_object* vno = gogo->lookup(receiver_name, NULL);
10263   gcc_assert(vno != NULL);
10264   Expression* ve = Expression::make_var_reference(vno, location);
10265   Expression* bm = Type::bind_field_or_method(gogo, nt, ve, name, location);
10266   gcc_assert(bm != NULL && !bm->is_error_expression());
10267
10268   Expression_list* args;
10269   if (method_parameters == NULL)
10270     args = NULL;
10271   else
10272     {
10273       args = new Expression_list();
10274       for (Typed_identifier_list::const_iterator p = method_parameters->begin();
10275            p != method_parameters->end();
10276            ++p)
10277         {
10278           vno = gogo->lookup(p->name(), NULL);
10279           gcc_assert(vno != NULL);
10280           args->push_back(Expression::make_var_reference(vno, location));
10281         }
10282     }
10283
10284   Call_expression* call = Expression::make_call(bm, args,
10285                                                 method_type->is_varargs(),
10286                                                 location);
10287
10288   size_t count = call->result_count();
10289   Statement* s;
10290   if (count == 0)
10291     s = Statement::make_statement(call);
10292   else
10293     {
10294       Expression_list* retvals = new Expression_list();
10295       if (count <= 1)
10296         retvals->push_back(call);
10297       else
10298         {
10299           for (size_t i = 0; i < count; ++i)
10300             retvals->push_back(Expression::make_call_result(call, i));
10301         }
10302       s = Statement::make_return_statement(no->func_value()->type()->results(),
10303                                            retvals, location);
10304     }
10305   gogo->add_statement(s);
10306
10307   gogo->finish_function(location);
10308
10309   return Expression::make_func_reference(no, NULL, location);
10310 }
10311
10312 // Make a selector expression.
10313
10314 Expression*
10315 Expression::make_selector(Expression* left, const std::string& name,
10316                           source_location location)
10317 {
10318   return new Selector_expression(left, name, location);
10319 }
10320
10321 // Implement the builtin function new.
10322
10323 class Allocation_expression : public Expression
10324 {
10325  public:
10326   Allocation_expression(Type* type, source_location location)
10327     : Expression(EXPRESSION_ALLOCATION, location),
10328       type_(type)
10329   { }
10330
10331  protected:
10332   int
10333   do_traverse(Traverse* traverse)
10334   { return Type::traverse(this->type_, traverse); }
10335
10336   Type*
10337   do_type()
10338   { return Type::make_pointer_type(this->type_); }
10339
10340   void
10341   do_determine_type(const Type_context*)
10342   { }
10343
10344   void
10345   do_check_types(Gogo*);
10346
10347   Expression*
10348   do_copy()
10349   { return new Allocation_expression(this->type_, this->location()); }
10350
10351   tree
10352   do_get_tree(Translate_context*);
10353
10354  private:
10355   // The type we are allocating.
10356   Type* type_;
10357 };
10358
10359 // Check the type of an allocation expression.
10360
10361 void
10362 Allocation_expression::do_check_types(Gogo*)
10363 {
10364   if (this->type_->function_type() != NULL)
10365     this->report_error(_("invalid new of function type"));
10366 }
10367
10368 // Return a tree for an allocation expression.
10369
10370 tree
10371 Allocation_expression::do_get_tree(Translate_context* context)
10372 {
10373   tree type_tree = this->type_->get_tree(context->gogo());
10374   if (type_tree == error_mark_node)
10375     return error_mark_node;
10376   tree size_tree = TYPE_SIZE_UNIT(type_tree);
10377   tree space = context->gogo()->allocate_memory(this->type_, size_tree,
10378                                                 this->location());
10379   if (space == error_mark_node)
10380     return error_mark_node;
10381   return fold_convert(build_pointer_type(type_tree), space);
10382 }
10383
10384 // Make an allocation expression.
10385
10386 Expression*
10387 Expression::make_allocation(Type* type, source_location location)
10388 {
10389   return new Allocation_expression(type, location);
10390 }
10391
10392 // Implement the builtin function make.
10393
10394 class Make_expression : public Expression
10395 {
10396  public:
10397   Make_expression(Type* type, Expression_list* args, source_location location)
10398     : Expression(EXPRESSION_MAKE, location),
10399       type_(type), args_(args)
10400   { }
10401
10402  protected:
10403   int
10404   do_traverse(Traverse* traverse);
10405
10406   Type*
10407   do_type()
10408   { return this->type_; }
10409
10410   void
10411   do_determine_type(const Type_context*);
10412
10413   void
10414   do_check_types(Gogo*);
10415
10416   Expression*
10417   do_copy()
10418   {
10419     return new Make_expression(this->type_, this->args_->copy(),
10420                                this->location());
10421   }
10422
10423   tree
10424   do_get_tree(Translate_context*);
10425
10426  private:
10427   // The type we are making.
10428   Type* type_;
10429   // The arguments to pass to the make routine.
10430   Expression_list* args_;
10431 };
10432
10433 // Traversal.
10434
10435 int
10436 Make_expression::do_traverse(Traverse* traverse)
10437 {
10438   if (this->args_ != NULL
10439       && this->args_->traverse(traverse) == TRAVERSE_EXIT)
10440     return TRAVERSE_EXIT;
10441   if (Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
10442     return TRAVERSE_EXIT;
10443   return TRAVERSE_CONTINUE;
10444 }
10445
10446 // Set types of arguments.
10447
10448 void
10449 Make_expression::do_determine_type(const Type_context*)
10450 {
10451   if (this->args_ != NULL)
10452     {
10453       Type_context context(Type::lookup_integer_type("int"), false);
10454       for (Expression_list::const_iterator pe = this->args_->begin();
10455            pe != this->args_->end();
10456            ++pe)
10457         (*pe)->determine_type(&context);
10458     }
10459 }
10460
10461 // Check types for a make expression.
10462
10463 void
10464 Make_expression::do_check_types(Gogo*)
10465 {
10466   if (this->type_->channel_type() == NULL
10467       && this->type_->map_type() == NULL
10468       && (this->type_->array_type() == NULL
10469           || this->type_->array_type()->length() != NULL))
10470     this->report_error(_("invalid type for make function"));
10471   else if (!this->type_->check_make_expression(this->args_, this->location()))
10472     this->set_is_error();
10473 }
10474
10475 // Return a tree for a make expression.
10476
10477 tree
10478 Make_expression::do_get_tree(Translate_context* context)
10479 {
10480   return this->type_->make_expression_tree(context, this->args_,
10481                                            this->location());
10482 }
10483
10484 // Make a make expression.
10485
10486 Expression*
10487 Expression::make_make(Type* type, Expression_list* args,
10488                       source_location location)
10489 {
10490   return new Make_expression(type, args, location);
10491 }
10492
10493 // Construct a struct.
10494
10495 class Struct_construction_expression : public Expression
10496 {
10497  public:
10498   Struct_construction_expression(Type* type, Expression_list* vals,
10499                                  source_location location)
10500     : Expression(EXPRESSION_STRUCT_CONSTRUCTION, location),
10501       type_(type), vals_(vals)
10502   { }
10503
10504   // Return whether this is a constant initializer.
10505   bool
10506   is_constant_struct() const;
10507
10508  protected:
10509   int
10510   do_traverse(Traverse* traverse);
10511
10512   Type*
10513   do_type()
10514   { return this->type_; }
10515
10516   void
10517   do_determine_type(const Type_context*);
10518
10519   void
10520   do_check_types(Gogo*);
10521
10522   Expression*
10523   do_copy()
10524   {
10525     return new Struct_construction_expression(this->type_, this->vals_->copy(),
10526                                               this->location());
10527   }
10528
10529   bool
10530   do_is_addressable() const
10531   { return true; }
10532
10533   tree
10534   do_get_tree(Translate_context*);
10535
10536   void
10537   do_export(Export*) const;
10538
10539  private:
10540   // The type of the struct to construct.
10541   Type* type_;
10542   // The list of values, in order of the fields in the struct.  A NULL
10543   // entry means that the field should be zero-initialized.
10544   Expression_list* vals_;
10545 };
10546
10547 // Traversal.
10548
10549 int
10550 Struct_construction_expression::do_traverse(Traverse* traverse)
10551 {
10552   if (this->vals_ != NULL
10553       && this->vals_->traverse(traverse) == TRAVERSE_EXIT)
10554     return TRAVERSE_EXIT;
10555   if (Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
10556     return TRAVERSE_EXIT;
10557   return TRAVERSE_CONTINUE;
10558 }
10559
10560 // Return whether this is a constant initializer.
10561
10562 bool
10563 Struct_construction_expression::is_constant_struct() const
10564 {
10565   if (this->vals_ == NULL)
10566     return true;
10567   for (Expression_list::const_iterator pv = this->vals_->begin();
10568        pv != this->vals_->end();
10569        ++pv)
10570     {
10571       if (*pv != NULL
10572           && !(*pv)->is_constant()
10573           && (!(*pv)->is_composite_literal()
10574               || (*pv)->is_nonconstant_composite_literal()))
10575         return false;
10576     }
10577
10578   const Struct_field_list* fields = this->type_->struct_type()->fields();
10579   for (Struct_field_list::const_iterator pf = fields->begin();
10580        pf != fields->end();
10581        ++pf)
10582     {
10583       // There are no constant constructors for interfaces.
10584       if (pf->type()->interface_type() != NULL)
10585         return false;
10586     }
10587
10588   return true;
10589 }
10590
10591 // Final type determination.
10592
10593 void
10594 Struct_construction_expression::do_determine_type(const Type_context*)
10595 {
10596   if (this->vals_ == NULL)
10597     return;
10598   const Struct_field_list* fields = this->type_->struct_type()->fields();
10599   Expression_list::const_iterator pv = this->vals_->begin();
10600   for (Struct_field_list::const_iterator pf = fields->begin();
10601        pf != fields->end();
10602        ++pf, ++pv)
10603     {
10604       if (pv == this->vals_->end())
10605         return;
10606       if (*pv != NULL)
10607         {
10608           Type_context subcontext(pf->type(), false);
10609           (*pv)->determine_type(&subcontext);
10610         }
10611     }
10612 }
10613
10614 // Check types.
10615
10616 void
10617 Struct_construction_expression::do_check_types(Gogo*)
10618 {
10619   if (this->vals_ == NULL)
10620     return;
10621
10622   Struct_type* st = this->type_->struct_type();
10623   if (this->vals_->size() > st->field_count())
10624     {
10625       this->report_error(_("too many expressions for struct"));
10626       return;
10627     }
10628
10629   const Struct_field_list* fields = st->fields();
10630   Expression_list::const_iterator pv = this->vals_->begin();
10631   int i = 0;
10632   for (Struct_field_list::const_iterator pf = fields->begin();
10633        pf != fields->end();
10634        ++pf, ++pv, ++i)
10635     {
10636       if (pv == this->vals_->end())
10637         {
10638           this->report_error(_("too few expressions for struct"));
10639           break;
10640         }
10641
10642       if (*pv == NULL)
10643         continue;
10644
10645       std::string reason;
10646       if (!Type::are_assignable(pf->type(), (*pv)->type(), &reason))
10647         {
10648           if (reason.empty())
10649             error_at((*pv)->location(),
10650                      "incompatible type for field %d in struct construction",
10651                      i + 1);
10652           else
10653             error_at((*pv)->location(),
10654                      ("incompatible type for field %d in "
10655                       "struct construction (%s)"),
10656                      i + 1, reason.c_str());
10657           this->set_is_error();
10658         }
10659     }
10660   gcc_assert(pv == this->vals_->end());
10661 }
10662
10663 // Return a tree for constructing a struct.
10664
10665 tree
10666 Struct_construction_expression::do_get_tree(Translate_context* context)
10667 {
10668   Gogo* gogo = context->gogo();
10669
10670   if (this->vals_ == NULL)
10671     return this->type_->get_init_tree(gogo, false);
10672
10673   tree type_tree = this->type_->get_tree(gogo);
10674   if (type_tree == error_mark_node)
10675     return error_mark_node;
10676   gcc_assert(TREE_CODE(type_tree) == RECORD_TYPE);
10677
10678   bool is_constant = true;
10679   const Struct_field_list* fields = this->type_->struct_type()->fields();
10680   VEC(constructor_elt,gc)* elts = VEC_alloc(constructor_elt, gc,
10681                                             fields->size());
10682   Struct_field_list::const_iterator pf = fields->begin();
10683   Expression_list::const_iterator pv = this->vals_->begin();
10684   for (tree field = TYPE_FIELDS(type_tree);
10685        field != NULL_TREE;
10686        field = DECL_CHAIN(field), ++pf)
10687     {
10688       gcc_assert(pf != fields->end());
10689
10690       tree val;
10691       if (pv == this->vals_->end())
10692         val = pf->type()->get_init_tree(gogo, false);
10693       else if (*pv == NULL)
10694         {
10695           val = pf->type()->get_init_tree(gogo, false);
10696           ++pv;
10697         }
10698       else
10699         {
10700           val = Expression::convert_for_assignment(context, pf->type(),
10701                                                    (*pv)->type(),
10702                                                    (*pv)->get_tree(context),
10703                                                    this->location());
10704           ++pv;
10705         }
10706
10707       if (val == error_mark_node || TREE_TYPE(val) == error_mark_node)
10708         return error_mark_node;
10709
10710       constructor_elt* elt = VEC_quick_push(constructor_elt, elts, NULL);
10711       elt->index = field;
10712       elt->value = val;
10713       if (!TREE_CONSTANT(val))
10714         is_constant = false;
10715     }
10716   gcc_assert(pf == fields->end());
10717
10718   tree ret = build_constructor(type_tree, elts);
10719   if (is_constant)
10720     TREE_CONSTANT(ret) = 1;
10721   return ret;
10722 }
10723
10724 // Export a struct construction.
10725
10726 void
10727 Struct_construction_expression::do_export(Export* exp) const
10728 {
10729   exp->write_c_string("convert(");
10730   exp->write_type(this->type_);
10731   for (Expression_list::const_iterator pv = this->vals_->begin();
10732        pv != this->vals_->end();
10733        ++pv)
10734     {
10735       exp->write_c_string(", ");
10736       if (*pv != NULL)
10737         (*pv)->export_expression(exp);
10738     }
10739   exp->write_c_string(")");
10740 }
10741
10742 // Make a struct composite literal.  This used by the thunk code.
10743
10744 Expression*
10745 Expression::make_struct_composite_literal(Type* type, Expression_list* vals,
10746                                           source_location location)
10747 {
10748   gcc_assert(type->struct_type() != NULL);
10749   return new Struct_construction_expression(type, vals, location);
10750 }
10751
10752 // Construct an array.  This class is not used directly; instead we
10753 // use the child classes, Fixed_array_construction_expression and
10754 // Open_array_construction_expression.
10755
10756 class Array_construction_expression : public Expression
10757 {
10758  protected:
10759   Array_construction_expression(Expression_classification classification,
10760                                 Type* type, Expression_list* vals,
10761                                 source_location location)
10762     : Expression(classification, location),
10763       type_(type), vals_(vals)
10764   { }
10765
10766  public:
10767   // Return whether this is a constant initializer.
10768   bool
10769   is_constant_array() const;
10770
10771   // Return the number of elements.
10772   size_t
10773   element_count() const
10774   { return this->vals_ == NULL ? 0 : this->vals_->size(); }
10775
10776 protected:
10777   int
10778   do_traverse(Traverse* traverse);
10779
10780   Type*
10781   do_type()
10782   { return this->type_; }
10783
10784   void
10785   do_determine_type(const Type_context*);
10786
10787   void
10788   do_check_types(Gogo*);
10789
10790   bool
10791   do_is_addressable() const
10792   { return true; }
10793
10794   void
10795   do_export(Export*) const;
10796
10797   // The list of values.
10798   Expression_list*
10799   vals()
10800   { return this->vals_; }
10801
10802   // Get a constructor tree for the array values.
10803   tree
10804   get_constructor_tree(Translate_context* context, tree type_tree);
10805
10806  private:
10807   // The type of the array to construct.
10808   Type* type_;
10809   // The list of values.
10810   Expression_list* vals_;
10811 };
10812
10813 // Traversal.
10814
10815 int
10816 Array_construction_expression::do_traverse(Traverse* traverse)
10817 {
10818   if (this->vals_ != NULL
10819       && this->vals_->traverse(traverse) == TRAVERSE_EXIT)
10820     return TRAVERSE_EXIT;
10821   if (Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
10822     return TRAVERSE_EXIT;
10823   return TRAVERSE_CONTINUE;
10824 }
10825
10826 // Return whether this is a constant initializer.
10827
10828 bool
10829 Array_construction_expression::is_constant_array() const
10830 {
10831   if (this->vals_ == NULL)
10832     return true;
10833
10834   // There are no constant constructors for interfaces.
10835   if (this->type_->array_type()->element_type()->interface_type() != NULL)
10836     return false;
10837
10838   for (Expression_list::const_iterator pv = this->vals_->begin();
10839        pv != this->vals_->end();
10840        ++pv)
10841     {
10842       if (*pv != NULL
10843           && !(*pv)->is_constant()
10844           && (!(*pv)->is_composite_literal()
10845               || (*pv)->is_nonconstant_composite_literal()))
10846         return false;
10847     }
10848   return true;
10849 }
10850
10851 // Final type determination.
10852
10853 void
10854 Array_construction_expression::do_determine_type(const Type_context*)
10855 {
10856   if (this->vals_ == NULL)
10857     return;
10858   Type_context subcontext(this->type_->array_type()->element_type(), false);
10859   for (Expression_list::const_iterator pv = this->vals_->begin();
10860        pv != this->vals_->end();
10861        ++pv)
10862     {
10863       if (*pv != NULL)
10864         (*pv)->determine_type(&subcontext);
10865     }
10866 }
10867
10868 // Check types.
10869
10870 void
10871 Array_construction_expression::do_check_types(Gogo*)
10872 {
10873   if (this->vals_ == NULL)
10874     return;
10875
10876   Array_type* at = this->type_->array_type();
10877   int i = 0;
10878   Type* element_type = at->element_type();
10879   for (Expression_list::const_iterator pv = this->vals_->begin();
10880        pv != this->vals_->end();
10881        ++pv, ++i)
10882     {
10883       if (*pv != NULL
10884           && !Type::are_assignable(element_type, (*pv)->type(), NULL))
10885         {
10886           error_at((*pv)->location(),
10887                    "incompatible type for element %d in composite literal",
10888                    i + 1);
10889           this->set_is_error();
10890         }
10891     }
10892
10893   Expression* length = at->length();
10894   if (length != NULL)
10895     {
10896       mpz_t val;
10897       mpz_init(val);
10898       Type* type;
10899       if (at->length()->integer_constant_value(true, val, &type))
10900         {
10901           if (this->vals_->size() > mpz_get_ui(val))
10902             this->report_error(_("too many elements in composite literal"));
10903         }
10904       mpz_clear(val);
10905     }
10906 }
10907
10908 // Get a constructor tree for the array values.
10909
10910 tree
10911 Array_construction_expression::get_constructor_tree(Translate_context* context,
10912                                                     tree type_tree)
10913 {
10914   VEC(constructor_elt,gc)* values = VEC_alloc(constructor_elt, gc,
10915                                               (this->vals_ == NULL
10916                                                ? 0
10917                                                : this->vals_->size()));
10918   Type* element_type = this->type_->array_type()->element_type();
10919   bool is_constant = true;
10920   if (this->vals_ != NULL)
10921     {
10922       size_t i = 0;
10923       for (Expression_list::const_iterator pv = this->vals_->begin();
10924            pv != this->vals_->end();
10925            ++pv, ++i)
10926         {
10927           constructor_elt* elt = VEC_quick_push(constructor_elt, values, NULL);
10928           elt->index = size_int(i);
10929           if (*pv == NULL)
10930             elt->value = element_type->get_init_tree(context->gogo(), false);
10931           else
10932             {
10933               tree value_tree = (*pv)->get_tree(context);
10934               elt->value = Expression::convert_for_assignment(context,
10935                                                               element_type,
10936                                                               (*pv)->type(),
10937                                                               value_tree,
10938                                                               this->location());
10939             }
10940           if (elt->value == error_mark_node)
10941             return error_mark_node;
10942           if (!TREE_CONSTANT(elt->value))
10943             is_constant = false;
10944         }
10945     }
10946
10947   tree ret = build_constructor(type_tree, values);
10948   if (is_constant)
10949     TREE_CONSTANT(ret) = 1;
10950   return ret;
10951 }
10952
10953 // Export an array construction.
10954
10955 void
10956 Array_construction_expression::do_export(Export* exp) const
10957 {
10958   exp->write_c_string("convert(");
10959   exp->write_type(this->type_);
10960   if (this->vals_ != NULL)
10961     {
10962       for (Expression_list::const_iterator pv = this->vals_->begin();
10963            pv != this->vals_->end();
10964            ++pv)
10965         {
10966           exp->write_c_string(", ");
10967           if (*pv != NULL)
10968             (*pv)->export_expression(exp);
10969         }
10970     }
10971   exp->write_c_string(")");
10972 }
10973
10974 // Construct a fixed array.
10975
10976 class Fixed_array_construction_expression :
10977   public Array_construction_expression
10978 {
10979  public:
10980   Fixed_array_construction_expression(Type* type, Expression_list* vals,
10981                                       source_location location)
10982     : Array_construction_expression(EXPRESSION_FIXED_ARRAY_CONSTRUCTION,
10983                                     type, vals, location)
10984   {
10985     gcc_assert(type->array_type() != NULL
10986                && type->array_type()->length() != NULL);
10987   }
10988
10989  protected:
10990   Expression*
10991   do_copy()
10992   {
10993     return new Fixed_array_construction_expression(this->type(),
10994                                                    (this->vals() == NULL
10995                                                     ? NULL
10996                                                     : this->vals()->copy()),
10997                                                    this->location());
10998   }
10999
11000   tree
11001   do_get_tree(Translate_context*);
11002 };
11003
11004 // Return a tree for constructing a fixed array.
11005
11006 tree
11007 Fixed_array_construction_expression::do_get_tree(Translate_context* context)
11008 {
11009   return this->get_constructor_tree(context,
11010                                     this->type()->get_tree(context->gogo()));
11011 }
11012
11013 // Construct an open array.
11014
11015 class Open_array_construction_expression : public Array_construction_expression
11016 {
11017  public:
11018   Open_array_construction_expression(Type* type, Expression_list* vals,
11019                                      source_location location)
11020     : Array_construction_expression(EXPRESSION_OPEN_ARRAY_CONSTRUCTION,
11021                                     type, vals, location)
11022   {
11023     gcc_assert(type->array_type() != NULL
11024                && type->array_type()->length() == NULL);
11025   }
11026
11027  protected:
11028   // Note that taking the address of an open array literal is invalid.
11029
11030   Expression*
11031   do_copy()
11032   {
11033     return new Open_array_construction_expression(this->type(),
11034                                                   (this->vals() == NULL
11035                                                    ? NULL
11036                                                    : this->vals()->copy()),
11037                                                   this->location());
11038   }
11039
11040   tree
11041   do_get_tree(Translate_context*);
11042 };
11043
11044 // Return a tree for constructing an open array.
11045
11046 tree
11047 Open_array_construction_expression::do_get_tree(Translate_context* context)
11048 {
11049   Array_type* array_type = this->type()->array_type();
11050   if (array_type == NULL)
11051     {
11052       gcc_assert(this->type()->is_error_type());
11053       return error_mark_node;
11054     }
11055
11056   Type* element_type = array_type->element_type();
11057   tree element_type_tree = element_type->get_tree(context->gogo());
11058   if (element_type_tree == error_mark_node)
11059     return error_mark_node;
11060
11061   tree values;
11062   tree length_tree;
11063   if (this->vals() == NULL || this->vals()->empty())
11064     {
11065       // We need to create a unique value.
11066       tree max = size_int(0);
11067       tree constructor_type = build_array_type(element_type_tree,
11068                                                build_index_type(max));
11069       if (constructor_type == error_mark_node)
11070         return error_mark_node;
11071       VEC(constructor_elt,gc)* vec = VEC_alloc(constructor_elt, gc, 1);
11072       constructor_elt* elt = VEC_quick_push(constructor_elt, vec, NULL);
11073       elt->index = size_int(0);
11074       elt->value = element_type->get_init_tree(context->gogo(), false);
11075       values = build_constructor(constructor_type, vec);
11076       if (TREE_CONSTANT(elt->value))
11077         TREE_CONSTANT(values) = 1;
11078       length_tree = size_int(0);
11079     }
11080   else
11081     {
11082       tree max = size_int(this->vals()->size() - 1);
11083       tree constructor_type = build_array_type(element_type_tree,
11084                                                build_index_type(max));
11085       if (constructor_type == error_mark_node)
11086         return error_mark_node;
11087       values = this->get_constructor_tree(context, constructor_type);
11088       length_tree = size_int(this->vals()->size());
11089     }
11090
11091   if (values == error_mark_node)
11092     return error_mark_node;
11093
11094   bool is_constant_initializer = TREE_CONSTANT(values);
11095   bool is_in_function = context->function() != NULL;
11096
11097   if (is_constant_initializer)
11098     {
11099       tree tmp = build_decl(this->location(), VAR_DECL,
11100                             create_tmp_var_name("C"), TREE_TYPE(values));
11101       DECL_EXTERNAL(tmp) = 0;
11102       TREE_PUBLIC(tmp) = 0;
11103       TREE_STATIC(tmp) = 1;
11104       DECL_ARTIFICIAL(tmp) = 1;
11105       if (is_in_function)
11106         {
11107           // If this is not a function, we will only initialize the
11108           // value once, so we can use this directly rather than
11109           // copying it.  In that case we can't make it read-only,
11110           // because the program is permitted to change it.
11111           TREE_READONLY(tmp) = 1;
11112           TREE_CONSTANT(tmp) = 1;
11113         }
11114       DECL_INITIAL(tmp) = values;
11115       rest_of_decl_compilation(tmp, 1, 0);
11116       values = tmp;
11117     }
11118
11119   tree space;
11120   tree set;
11121   if (!is_in_function && is_constant_initializer)
11122     {
11123       // Outside of a function, we know the initializer will only run
11124       // once.
11125       space = build_fold_addr_expr(values);
11126       set = NULL_TREE;
11127     }
11128   else
11129     {
11130       tree memsize = TYPE_SIZE_UNIT(TREE_TYPE(values));
11131       space = context->gogo()->allocate_memory(element_type, memsize,
11132                                                this->location());
11133       space = save_expr(space);
11134
11135       tree s = fold_convert(build_pointer_type(TREE_TYPE(values)), space);
11136       tree ref = build_fold_indirect_ref_loc(this->location(), s);
11137       TREE_THIS_NOTRAP(ref) = 1;
11138       set = build2(MODIFY_EXPR, void_type_node, ref, values);
11139     }
11140
11141   // Build a constructor for the open array.
11142
11143   tree type_tree = this->type()->get_tree(context->gogo());
11144   if (type_tree == error_mark_node)
11145     return error_mark_node;
11146   gcc_assert(TREE_CODE(type_tree) == RECORD_TYPE);
11147
11148   VEC(constructor_elt,gc)* init = VEC_alloc(constructor_elt, gc, 3);
11149
11150   constructor_elt* elt = VEC_quick_push(constructor_elt, init, NULL);
11151   tree field = TYPE_FIELDS(type_tree);
11152   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__values") == 0);
11153   elt->index = field;
11154   elt->value = fold_convert(TREE_TYPE(field), space);
11155
11156   elt = VEC_quick_push(constructor_elt, init, NULL);
11157   field = DECL_CHAIN(field);
11158   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)), "__count") == 0);
11159   elt->index = field;
11160   elt->value = fold_convert(TREE_TYPE(field), length_tree);
11161
11162   elt = VEC_quick_push(constructor_elt, init, NULL);
11163   field = DECL_CHAIN(field);
11164   gcc_assert(strcmp(IDENTIFIER_POINTER(DECL_NAME(field)),"__capacity") == 0);
11165   elt->index = field;
11166   elt->value = fold_convert(TREE_TYPE(field), length_tree);
11167
11168   tree constructor = build_constructor(type_tree, init);
11169   if (constructor == error_mark_node)
11170     return error_mark_node;
11171   if (!is_in_function && is_constant_initializer)
11172     TREE_CONSTANT(constructor) = 1;
11173
11174   if (set == NULL_TREE)
11175     return constructor;
11176   else
11177     return build2(COMPOUND_EXPR, type_tree, set, constructor);
11178 }
11179
11180 // Make a slice composite literal.  This is used by the type
11181 // descriptor code.
11182
11183 Expression*
11184 Expression::make_slice_composite_literal(Type* type, Expression_list* vals,
11185                                          source_location location)
11186 {
11187   gcc_assert(type->is_open_array_type());
11188   return new Open_array_construction_expression(type, vals, location);
11189 }
11190
11191 // Construct a map.
11192
11193 class Map_construction_expression : public Expression
11194 {
11195  public:
11196   Map_construction_expression(Type* type, Expression_list* vals,
11197                               source_location location)
11198     : Expression(EXPRESSION_MAP_CONSTRUCTION, location),
11199       type_(type), vals_(vals)
11200   { gcc_assert(vals == NULL || vals->size() % 2 == 0); }
11201
11202  protected:
11203   int
11204   do_traverse(Traverse* traverse);
11205
11206   Type*
11207   do_type()
11208   { return this->type_; }
11209
11210   void
11211   do_determine_type(const Type_context*);
11212
11213   void
11214   do_check_types(Gogo*);
11215
11216   Expression*
11217   do_copy()
11218   {
11219     return new Map_construction_expression(this->type_, this->vals_->copy(),
11220                                            this->location());
11221   }
11222
11223   tree
11224   do_get_tree(Translate_context*);
11225
11226   void
11227   do_export(Export*) const;
11228
11229  private:
11230   // The type of the map to construct.
11231   Type* type_;
11232   // The list of values.
11233   Expression_list* vals_;
11234 };
11235
11236 // Traversal.
11237
11238 int
11239 Map_construction_expression::do_traverse(Traverse* traverse)
11240 {
11241   if (this->vals_ != NULL
11242       && this->vals_->traverse(traverse) == TRAVERSE_EXIT)
11243     return TRAVERSE_EXIT;
11244   if (Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
11245     return TRAVERSE_EXIT;
11246   return TRAVERSE_CONTINUE;
11247 }
11248
11249 // Final type determination.
11250
11251 void
11252 Map_construction_expression::do_determine_type(const Type_context*)
11253 {
11254   if (this->vals_ == NULL)
11255     return;
11256
11257   Map_type* mt = this->type_->map_type();
11258   Type_context key_context(mt->key_type(), false);
11259   Type_context val_context(mt->val_type(), false);
11260   for (Expression_list::const_iterator pv = this->vals_->begin();
11261        pv != this->vals_->end();
11262        ++pv)
11263     {
11264       (*pv)->determine_type(&key_context);
11265       ++pv;
11266       (*pv)->determine_type(&val_context);
11267     }
11268 }
11269
11270 // Check types.
11271
11272 void
11273 Map_construction_expression::do_check_types(Gogo*)
11274 {
11275   if (this->vals_ == NULL)
11276     return;
11277
11278   Map_type* mt = this->type_->map_type();
11279   int i = 0;
11280   Type* key_type = mt->key_type();
11281   Type* val_type = mt->val_type();
11282   for (Expression_list::const_iterator pv = this->vals_->begin();
11283        pv != this->vals_->end();
11284        ++pv, ++i)
11285     {
11286       if (!Type::are_assignable(key_type, (*pv)->type(), NULL))
11287         {
11288           error_at((*pv)->location(),
11289                    "incompatible type for element %d key in map construction",
11290                    i + 1);
11291           this->set_is_error();
11292         }
11293       ++pv;
11294       if (!Type::are_assignable(val_type, (*pv)->type(), NULL))
11295         {
11296           error_at((*pv)->location(),
11297                    ("incompatible type for element %d value "
11298                     "in map construction"),
11299                    i + 1);
11300           this->set_is_error();
11301         }
11302     }
11303 }
11304
11305 // Return a tree for constructing a map.
11306
11307 tree
11308 Map_construction_expression::do_get_tree(Translate_context* context)
11309 {
11310   Gogo* gogo = context->gogo();
11311   source_location loc = this->location();
11312
11313   Map_type* mt = this->type_->map_type();
11314
11315   // Build a struct to hold the key and value.
11316   tree struct_type = make_node(RECORD_TYPE);
11317
11318   Type* key_type = mt->key_type();
11319   tree id = get_identifier("__key");
11320   tree key_type_tree = key_type->get_tree(gogo);
11321   if (key_type_tree == error_mark_node)
11322     return error_mark_node;
11323   tree key_field = build_decl(loc, FIELD_DECL, id, key_type_tree);
11324   DECL_CONTEXT(key_field) = struct_type;
11325   TYPE_FIELDS(struct_type) = key_field;
11326
11327   Type* val_type = mt->val_type();
11328   id = get_identifier("__val");
11329   tree val_type_tree = val_type->get_tree(gogo);
11330   if (val_type_tree == error_mark_node)
11331     return error_mark_node;
11332   tree val_field = build_decl(loc, FIELD_DECL, id, val_type_tree);
11333   DECL_CONTEXT(val_field) = struct_type;
11334   DECL_CHAIN(key_field) = val_field;
11335
11336   layout_type(struct_type);
11337
11338   bool is_constant = true;
11339   size_t i = 0;
11340   tree valaddr;
11341   tree make_tmp;
11342
11343   if (this->vals_ == NULL || this->vals_->empty())
11344     {
11345       valaddr = null_pointer_node;
11346       make_tmp = NULL_TREE;
11347     }
11348   else
11349     {
11350       VEC(constructor_elt,gc)* values = VEC_alloc(constructor_elt, gc,
11351                                                   this->vals_->size() / 2);
11352
11353       for (Expression_list::const_iterator pv = this->vals_->begin();
11354            pv != this->vals_->end();
11355            ++pv, ++i)
11356         {
11357           bool one_is_constant = true;
11358
11359           VEC(constructor_elt,gc)* one = VEC_alloc(constructor_elt, gc, 2);
11360
11361           constructor_elt* elt = VEC_quick_push(constructor_elt, one, NULL);
11362           elt->index = key_field;
11363           tree val_tree = (*pv)->get_tree(context);
11364           elt->value = Expression::convert_for_assignment(context, key_type,
11365                                                           (*pv)->type(),
11366                                                           val_tree, loc);
11367           if (elt->value == error_mark_node)
11368             return error_mark_node;
11369           if (!TREE_CONSTANT(elt->value))
11370             one_is_constant = false;
11371
11372           ++pv;
11373
11374           elt = VEC_quick_push(constructor_elt, one, NULL);
11375           elt->index = val_field;
11376           val_tree = (*pv)->get_tree(context);
11377           elt->value = Expression::convert_for_assignment(context, val_type,
11378                                                           (*pv)->type(),
11379                                                           val_tree, loc);
11380           if (elt->value == error_mark_node)
11381             return error_mark_node;
11382           if (!TREE_CONSTANT(elt->value))
11383             one_is_constant = false;
11384
11385           elt = VEC_quick_push(constructor_elt, values, NULL);
11386           elt->index = size_int(i);
11387           elt->value = build_constructor(struct_type, one);
11388           if (one_is_constant)
11389             TREE_CONSTANT(elt->value) = 1;
11390           else
11391             is_constant = false;
11392         }
11393
11394       tree index_type = build_index_type(size_int(i - 1));
11395       tree array_type = build_array_type(struct_type, index_type);
11396       tree init = build_constructor(array_type, values);
11397       if (is_constant)
11398         TREE_CONSTANT(init) = 1;
11399       tree tmp;
11400       if (current_function_decl != NULL)
11401         {
11402           tmp = create_tmp_var(array_type, get_name(array_type));
11403           DECL_INITIAL(tmp) = init;
11404           make_tmp = fold_build1_loc(loc, DECL_EXPR, void_type_node, tmp);
11405           TREE_ADDRESSABLE(tmp) = 1;
11406         }
11407       else
11408         {
11409           tmp = build_decl(loc, VAR_DECL, create_tmp_var_name("M"), array_type);
11410           DECL_EXTERNAL(tmp) = 0;
11411           TREE_PUBLIC(tmp) = 0;
11412           TREE_STATIC(tmp) = 1;
11413           DECL_ARTIFICIAL(tmp) = 1;
11414           if (!TREE_CONSTANT(init))
11415             make_tmp = fold_build2_loc(loc, INIT_EXPR, void_type_node, tmp,
11416                                        init);
11417           else
11418             {
11419               TREE_READONLY(tmp) = 1;
11420               TREE_CONSTANT(tmp) = 1;
11421               DECL_INITIAL(tmp) = init;
11422               make_tmp = NULL_TREE;
11423             }
11424           rest_of_decl_compilation(tmp, 1, 0);
11425         }
11426
11427       valaddr = build_fold_addr_expr(tmp);
11428     }
11429
11430   tree descriptor = gogo->map_descriptor(mt);
11431
11432   tree type_tree = this->type_->get_tree(gogo);
11433   if (type_tree == error_mark_node)
11434     return error_mark_node;
11435
11436   static tree construct_map_fndecl;
11437   tree call = Gogo::call_builtin(&construct_map_fndecl,
11438                                  loc,
11439                                  "__go_construct_map",
11440                                  6,
11441                                  type_tree,
11442                                  TREE_TYPE(descriptor),
11443                                  descriptor,
11444                                  sizetype,
11445                                  size_int(i),
11446                                  sizetype,
11447                                  TYPE_SIZE_UNIT(struct_type),
11448                                  sizetype,
11449                                  byte_position(val_field),
11450                                  sizetype,
11451                                  TYPE_SIZE_UNIT(TREE_TYPE(val_field)),
11452                                  const_ptr_type_node,
11453                                  fold_convert(const_ptr_type_node, valaddr));
11454   if (call == error_mark_node)
11455     return error_mark_node;
11456
11457   tree ret;
11458   if (make_tmp == NULL)
11459     ret = call;
11460   else
11461     ret = fold_build2_loc(loc, COMPOUND_EXPR, type_tree, make_tmp, call);
11462   return ret;
11463 }
11464
11465 // Export an array construction.
11466
11467 void
11468 Map_construction_expression::do_export(Export* exp) const
11469 {
11470   exp->write_c_string("convert(");
11471   exp->write_type(this->type_);
11472   for (Expression_list::const_iterator pv = this->vals_->begin();
11473        pv != this->vals_->end();
11474        ++pv)
11475     {
11476       exp->write_c_string(", ");
11477       (*pv)->export_expression(exp);
11478     }
11479   exp->write_c_string(")");
11480 }
11481
11482 // A general composite literal.  This is lowered to a type specific
11483 // version.
11484
11485 class Composite_literal_expression : public Parser_expression
11486 {
11487  public:
11488   Composite_literal_expression(Type* type, int depth, bool has_keys,
11489                                Expression_list* vals, source_location location)
11490     : Parser_expression(EXPRESSION_COMPOSITE_LITERAL, location),
11491       type_(type), depth_(depth), vals_(vals), has_keys_(has_keys)
11492   { }
11493
11494  protected:
11495   int
11496   do_traverse(Traverse* traverse);
11497
11498   Expression*
11499   do_lower(Gogo*, Named_object*, int);
11500
11501   Expression*
11502   do_copy()
11503   {
11504     return new Composite_literal_expression(this->type_, this->depth_,
11505                                             this->has_keys_,
11506                                             (this->vals_ == NULL
11507                                              ? NULL
11508                                              : this->vals_->copy()),
11509                                             this->location());
11510   }
11511
11512  private:
11513   Expression*
11514   lower_struct(Type*);
11515
11516   Expression*
11517   lower_array(Type*);
11518
11519   Expression*
11520   make_array(Type*, Expression_list*);
11521
11522   Expression*
11523   lower_map(Gogo*, Named_object*, Type*);
11524
11525   // The type of the composite literal.
11526   Type* type_;
11527   // The depth within a list of composite literals within a composite
11528   // literal, when the type is omitted.
11529   int depth_;
11530   // The values to put in the composite literal.
11531   Expression_list* vals_;
11532   // If this is true, then VALS_ is a list of pairs: a key and a
11533   // value.  In an array initializer, a missing key will be NULL.
11534   bool has_keys_;
11535 };
11536
11537 // Traversal.
11538
11539 int
11540 Composite_literal_expression::do_traverse(Traverse* traverse)
11541 {
11542   if (this->vals_ != NULL
11543       && this->vals_->traverse(traverse) == TRAVERSE_EXIT)
11544     return TRAVERSE_EXIT;
11545   return Type::traverse(this->type_, traverse);
11546 }
11547
11548 // Lower a generic composite literal into a specific version based on
11549 // the type.
11550
11551 Expression*
11552 Composite_literal_expression::do_lower(Gogo* gogo, Named_object* function, int)
11553 {
11554   Type* type = this->type_;
11555
11556   for (int depth = this->depth_; depth > 0; --depth)
11557     {
11558       if (type->array_type() != NULL)
11559         type = type->array_type()->element_type();
11560       else if (type->map_type() != NULL)
11561         type = type->map_type()->val_type();
11562       else
11563         {
11564           if (!type->is_error_type())
11565             error_at(this->location(),
11566                      ("may only omit types within composite literals "
11567                       "of slice, array, or map type"));
11568           return Expression::make_error(this->location());
11569         }
11570     }
11571
11572   if (type->is_error_type())
11573     return Expression::make_error(this->location());
11574   else if (type->struct_type() != NULL)
11575     return this->lower_struct(type);
11576   else if (type->array_type() != NULL)
11577     return this->lower_array(type);
11578   else if (type->map_type() != NULL)
11579     return this->lower_map(gogo, function, type);
11580   else
11581     {
11582       error_at(this->location(),
11583                ("expected struct, slice, array, or map type "
11584                 "for composite literal"));
11585       return Expression::make_error(this->location());
11586     }
11587 }
11588
11589 // Lower a struct composite literal.
11590
11591 Expression*
11592 Composite_literal_expression::lower_struct(Type* type)
11593 {
11594   source_location location = this->location();
11595   Struct_type* st = type->struct_type();
11596   if (this->vals_ == NULL || !this->has_keys_)
11597     return new Struct_construction_expression(type, this->vals_, location);
11598
11599   size_t field_count = st->field_count();
11600   std::vector<Expression*> vals(field_count);
11601   Expression_list::const_iterator p = this->vals_->begin();
11602   while (p != this->vals_->end())
11603     {
11604       Expression* name_expr = *p;
11605
11606       ++p;
11607       gcc_assert(p != this->vals_->end());
11608       Expression* val = *p;
11609
11610       ++p;
11611
11612       if (name_expr == NULL)
11613         {
11614           error_at(val->location(), "mixture of field and value initializers");
11615           return Expression::make_error(location);
11616         }
11617
11618       bool bad_key = false;
11619       std::string name;
11620       switch (name_expr->classification())
11621         {
11622         case EXPRESSION_UNKNOWN_REFERENCE:
11623           name = name_expr->unknown_expression()->name();
11624           break;
11625
11626         case EXPRESSION_CONST_REFERENCE:
11627           name = static_cast<Const_expression*>(name_expr)->name();
11628           break;
11629
11630         case EXPRESSION_TYPE:
11631           {
11632             Type* t = name_expr->type();
11633             Named_type* nt = t->named_type();
11634             if (nt == NULL)
11635               bad_key = true;
11636             else
11637               name = nt->name();
11638           }
11639           break;
11640
11641         case EXPRESSION_VAR_REFERENCE:
11642           name = name_expr->var_expression()->name();
11643           break;
11644
11645         case EXPRESSION_FUNC_REFERENCE:
11646           name = name_expr->func_expression()->name();
11647           break;
11648
11649         case EXPRESSION_UNARY:
11650           // If there is a local variable around with the same name as
11651           // the field, and this occurs in the closure, then the
11652           // parser may turn the field reference into an indirection
11653           // through the closure.  FIXME: This is a mess.
11654           {
11655             bad_key = true;
11656             Unary_expression* ue = static_cast<Unary_expression*>(name_expr);
11657             if (ue->op() == OPERATOR_MULT)
11658               {
11659                 Field_reference_expression* fre =
11660                   ue->operand()->field_reference_expression();
11661                 if (fre != NULL)
11662                   {
11663                     Struct_type* st =
11664                       fre->expr()->type()->deref()->struct_type();
11665                     if (st != NULL)
11666                       {
11667                         const Struct_field* sf = st->field(fre->field_index());
11668                         name = sf->field_name();
11669                         char buf[20];
11670                         snprintf(buf, sizeof buf, "%u", fre->field_index());
11671                         size_t buflen = strlen(buf);
11672                         if (name.compare(name.length() - buflen, buflen, buf)
11673                             == 0)
11674                           {
11675                             name = name.substr(0, name.length() - buflen);
11676                             bad_key = false;
11677                           }
11678                       }
11679                   }
11680               }
11681           }
11682           break;
11683
11684         default:
11685           bad_key = true;
11686           break;
11687         }
11688       if (bad_key)
11689         {
11690           error_at(name_expr->location(), "expected struct field name");
11691           return Expression::make_error(location);
11692         }
11693
11694       unsigned int index;
11695       const Struct_field* sf = st->find_local_field(name, &index);
11696       if (sf == NULL)
11697         {
11698           error_at(name_expr->location(), "unknown field %qs in %qs",
11699                    Gogo::message_name(name).c_str(),
11700                    (type->named_type() != NULL
11701                     ? type->named_type()->message_name().c_str()
11702                     : "unnamed struct"));
11703           return Expression::make_error(location);
11704         }
11705       if (vals[index] != NULL)
11706         {
11707           error_at(name_expr->location(),
11708                    "duplicate value for field %qs in %qs",
11709                    Gogo::message_name(name).c_str(),
11710                    (type->named_type() != NULL
11711                     ? type->named_type()->message_name().c_str()
11712                     : "unnamed struct"));
11713           return Expression::make_error(location);
11714         }
11715
11716       vals[index] = val;
11717     }
11718
11719   Expression_list* list = new Expression_list;
11720   list->reserve(field_count);
11721   for (size_t i = 0; i < field_count; ++i)
11722     list->push_back(vals[i]);
11723
11724   return new Struct_construction_expression(type, list, location);
11725 }
11726
11727 // Lower an array composite literal.
11728
11729 Expression*
11730 Composite_literal_expression::lower_array(Type* type)
11731 {
11732   source_location location = this->location();
11733   if (this->vals_ == NULL || !this->has_keys_)
11734     return this->make_array(type, this->vals_);
11735
11736   std::vector<Expression*> vals;
11737   vals.reserve(this->vals_->size());
11738   unsigned long index = 0;
11739   Expression_list::const_iterator p = this->vals_->begin();
11740   while (p != this->vals_->end())
11741     {
11742       Expression* index_expr = *p;
11743
11744       ++p;
11745       gcc_assert(p != this->vals_->end());
11746       Expression* val = *p;
11747
11748       ++p;
11749
11750       if (index_expr != NULL)
11751         {
11752           mpz_t ival;
11753           mpz_init(ival);
11754           Type* dummy;
11755           if (!index_expr->integer_constant_value(true, ival, &dummy))
11756             {
11757               mpz_clear(ival);
11758               error_at(index_expr->location(),
11759                        "index expression is not integer constant");
11760               return Expression::make_error(location);
11761             }
11762           if (mpz_sgn(ival) < 0)
11763             {
11764               mpz_clear(ival);
11765               error_at(index_expr->location(), "index expression is negative");
11766               return Expression::make_error(location);
11767             }
11768           index = mpz_get_ui(ival);
11769           if (mpz_cmp_ui(ival, index) != 0)
11770             {
11771               mpz_clear(ival);
11772               error_at(index_expr->location(), "index value overflow");
11773               return Expression::make_error(location);
11774             }
11775           mpz_clear(ival);
11776         }
11777
11778       if (index == vals.size())
11779         vals.push_back(val);
11780       else
11781         {
11782           if (index > vals.size())
11783             {
11784               vals.reserve(index + 32);
11785               vals.resize(index + 1, static_cast<Expression*>(NULL));
11786             }
11787           if (vals[index] != NULL)
11788             {
11789               error_at((index_expr != NULL
11790                         ? index_expr->location()
11791                         : val->location()),
11792                        "duplicate value for index %lu",
11793                        index);
11794               return Expression::make_error(location);
11795             }
11796           vals[index] = val;
11797         }
11798
11799       ++index;
11800     }
11801
11802   size_t size = vals.size();
11803   Expression_list* list = new Expression_list;
11804   list->reserve(size);
11805   for (size_t i = 0; i < size; ++i)
11806     list->push_back(vals[i]);
11807
11808   return this->make_array(type, list);
11809 }
11810
11811 // Actually build the array composite literal. This handles
11812 // [...]{...}.
11813
11814 Expression*
11815 Composite_literal_expression::make_array(Type* type, Expression_list* vals)
11816 {
11817   source_location location = this->location();
11818   Array_type* at = type->array_type();
11819   if (at->length() != NULL && at->length()->is_nil_expression())
11820     {
11821       size_t size = vals == NULL ? 0 : vals->size();
11822       mpz_t vlen;
11823       mpz_init_set_ui(vlen, size);
11824       Expression* elen = Expression::make_integer(&vlen, NULL, location);
11825       mpz_clear(vlen);
11826       at = Type::make_array_type(at->element_type(), elen);
11827       type = at;
11828     }
11829   if (at->length() != NULL)
11830     return new Fixed_array_construction_expression(type, vals, location);
11831   else
11832     return new Open_array_construction_expression(type, vals, location);
11833 }
11834
11835 // Lower a map composite literal.
11836
11837 Expression*
11838 Composite_literal_expression::lower_map(Gogo* gogo, Named_object* function,
11839                                         Type* type)
11840 {
11841   source_location location = this->location();
11842   if (this->vals_ != NULL)
11843     {
11844       if (!this->has_keys_)
11845         {
11846           error_at(location, "map composite literal must have keys");
11847           return Expression::make_error(location);
11848         }
11849
11850       for (Expression_list::iterator p = this->vals_->begin();
11851            p != this->vals_->end();
11852            p += 2)
11853         {
11854           if (*p == NULL)
11855             {
11856               ++p;
11857               error_at((*p)->location(),
11858                        "map composite literal must have keys for every value");
11859               return Expression::make_error(location);
11860             }
11861           // Make sure we have lowered the key; it may not have been
11862           // lowered in order to handle keys for struct composite
11863           // literals.  Lower it now to get the right error message.
11864           if ((*p)->unknown_expression() != NULL)
11865             {
11866               (*p)->unknown_expression()->clear_is_composite_literal_key();
11867               gogo->lower_expression(function, &*p);
11868               gcc_assert((*p)->is_error_expression());
11869               return Expression::make_error(location);
11870             }
11871         }
11872     }
11873
11874   return new Map_construction_expression(type, this->vals_, location);
11875 }
11876
11877 // Make a composite literal expression.
11878
11879 Expression*
11880 Expression::make_composite_literal(Type* type, int depth, bool has_keys,
11881                                    Expression_list* vals,
11882                                    source_location location)
11883 {
11884   return new Composite_literal_expression(type, depth, has_keys, vals,
11885                                           location);
11886 }
11887
11888 // Return whether this expression is a composite literal.
11889
11890 bool
11891 Expression::is_composite_literal() const
11892 {
11893   switch (this->classification_)
11894     {
11895     case EXPRESSION_COMPOSITE_LITERAL:
11896     case EXPRESSION_STRUCT_CONSTRUCTION:
11897     case EXPRESSION_FIXED_ARRAY_CONSTRUCTION:
11898     case EXPRESSION_OPEN_ARRAY_CONSTRUCTION:
11899     case EXPRESSION_MAP_CONSTRUCTION:
11900       return true;
11901     default:
11902       return false;
11903     }
11904 }
11905
11906 // Return whether this expression is a composite literal which is not
11907 // constant.
11908
11909 bool
11910 Expression::is_nonconstant_composite_literal() const
11911 {
11912   switch (this->classification_)
11913     {
11914     case EXPRESSION_STRUCT_CONSTRUCTION:
11915       {
11916         const Struct_construction_expression *psce =
11917           static_cast<const Struct_construction_expression*>(this);
11918         return !psce->is_constant_struct();
11919       }
11920     case EXPRESSION_FIXED_ARRAY_CONSTRUCTION:
11921       {
11922         const Fixed_array_construction_expression *pace =
11923           static_cast<const Fixed_array_construction_expression*>(this);
11924         return !pace->is_constant_array();
11925       }
11926     case EXPRESSION_OPEN_ARRAY_CONSTRUCTION:
11927       {
11928         const Open_array_construction_expression *pace =
11929           static_cast<const Open_array_construction_expression*>(this);
11930         return !pace->is_constant_array();
11931       }
11932     case EXPRESSION_MAP_CONSTRUCTION:
11933       return true;
11934     default:
11935       return false;
11936     }
11937 }
11938
11939 // Return true if this is a reference to a local variable.
11940
11941 bool
11942 Expression::is_local_variable() const
11943 {
11944   const Var_expression* ve = this->var_expression();
11945   if (ve == NULL)
11946     return false;
11947   const Named_object* no = ve->named_object();
11948   return (no->is_result_variable()
11949           || (no->is_variable() && !no->var_value()->is_global()));
11950 }
11951
11952 // Class Type_guard_expression.
11953
11954 // Traversal.
11955
11956 int
11957 Type_guard_expression::do_traverse(Traverse* traverse)
11958 {
11959   if (Expression::traverse(&this->expr_, traverse) == TRAVERSE_EXIT
11960       || Type::traverse(this->type_, traverse) == TRAVERSE_EXIT)
11961     return TRAVERSE_EXIT;
11962   return TRAVERSE_CONTINUE;
11963 }
11964
11965 // Check types of a type guard expression.  The expression must have
11966 // an interface type, but the actual type conversion is checked at run
11967 // time.
11968
11969 void
11970 Type_guard_expression::do_check_types(Gogo*)
11971 {
11972   // 6g permits using a type guard with unsafe.pointer; we are
11973   // compatible.
11974   Type* expr_type = this->expr_->type();
11975   if (expr_type->is_unsafe_pointer_type())
11976     {
11977       if (this->type_->points_to() == NULL
11978           && (this->type_->integer_type() == NULL
11979               || (this->type_->forwarded()
11980                   != Type::lookup_integer_type("uintptr"))))
11981         this->report_error(_("invalid unsafe.Pointer conversion"));
11982     }
11983   else if (this->type_->is_unsafe_pointer_type())
11984     {
11985       if (expr_type->points_to() == NULL
11986           && (expr_type->integer_type() == NULL
11987               || (expr_type->forwarded()
11988                   != Type::lookup_integer_type("uintptr"))))
11989         this->report_error(_("invalid unsafe.Pointer conversion"));
11990     }
11991   else if (expr_type->interface_type() == NULL)
11992     {
11993       if (!expr_type->is_error_type() && !this->type_->is_error_type())
11994         this->report_error(_("type assertion only valid for interface types"));
11995       this->set_is_error();
11996     }
11997   else if (this->type_->interface_type() == NULL)
11998     {
11999       std::string reason;
12000       if (!expr_type->interface_type()->implements_interface(this->type_,
12001                                                              &reason))
12002         {
12003           if (!this->type_->is_error_type())
12004             {
12005               if (reason.empty())
12006                 this->report_error(_("impossible type assertion: "
12007                                      "type does not implement interface"));
12008               else
12009                 error_at(this->location(),
12010                          ("impossible type assertion: "
12011                           "type does not implement interface (%s)"),
12012                          reason.c_str());
12013             }
12014           this->set_is_error();
12015         }
12016     }
12017 }
12018
12019 // Return a tree for a type guard expression.
12020
12021 tree
12022 Type_guard_expression::do_get_tree(Translate_context* context)
12023 {
12024   Gogo* gogo = context->gogo();
12025   tree expr_tree = this->expr_->get_tree(context);
12026   if (expr_tree == error_mark_node)
12027     return error_mark_node;
12028   Type* expr_type = this->expr_->type();
12029   if ((this->type_->is_unsafe_pointer_type()
12030        && (expr_type->points_to() != NULL
12031            || expr_type->integer_type() != NULL))
12032       || (expr_type->is_unsafe_pointer_type()
12033           && this->type_->points_to() != NULL))
12034     return convert_to_pointer(this->type_->get_tree(gogo), expr_tree);
12035   else if (expr_type->is_unsafe_pointer_type()
12036            && this->type_->integer_type() != NULL)
12037     return convert_to_integer(this->type_->get_tree(gogo), expr_tree);
12038   else if (this->type_->interface_type() != NULL)
12039     return Expression::convert_interface_to_interface(context, this->type_,
12040                                                       this->expr_->type(),
12041                                                       expr_tree, true,
12042                                                       this->location());
12043   else
12044     return Expression::convert_for_assignment(context, this->type_,
12045                                               this->expr_->type(), expr_tree,
12046                                               this->location());
12047 }
12048
12049 // Make a type guard expression.
12050
12051 Expression*
12052 Expression::make_type_guard(Expression* expr, Type* type,
12053                             source_location location)
12054 {
12055   return new Type_guard_expression(expr, type, location);
12056 }
12057
12058 // Class Heap_composite_expression.
12059
12060 // When you take the address of a composite literal, it is allocated
12061 // on the heap.  This class implements that.
12062
12063 class Heap_composite_expression : public Expression
12064 {
12065  public:
12066   Heap_composite_expression(Expression* expr, source_location location)
12067     : Expression(EXPRESSION_HEAP_COMPOSITE, location),
12068       expr_(expr)
12069   { }
12070
12071  protected:
12072   int
12073   do_traverse(Traverse* traverse)
12074   { return Expression::traverse(&this->expr_, traverse); }
12075
12076   Type*
12077   do_type()
12078   { return Type::make_pointer_type(this->expr_->type()); }
12079
12080   void
12081   do_determine_type(const Type_context*)
12082   { this->expr_->determine_type_no_context(); }
12083
12084   Expression*
12085   do_copy()
12086   {
12087     return Expression::make_heap_composite(this->expr_->copy(),
12088                                            this->location());
12089   }
12090
12091   tree
12092   do_get_tree(Translate_context*);
12093
12094   // We only export global objects, and the parser does not generate
12095   // this in global scope.
12096   void
12097   do_export(Export*) const
12098   { gcc_unreachable(); }
12099
12100  private:
12101   // The composite literal which is being put on the heap.
12102   Expression* expr_;
12103 };
12104
12105 // Return a tree which allocates a composite literal on the heap.
12106
12107 tree
12108 Heap_composite_expression::do_get_tree(Translate_context* context)
12109 {
12110   tree expr_tree = this->expr_->get_tree(context);
12111   if (expr_tree == error_mark_node)
12112     return error_mark_node;
12113   tree expr_size = TYPE_SIZE_UNIT(TREE_TYPE(expr_tree));
12114   gcc_assert(TREE_CODE(expr_size) == INTEGER_CST);
12115   tree space = context->gogo()->allocate_memory(this->expr_->type(),
12116                                                 expr_size, this->location());
12117   space = fold_convert(build_pointer_type(TREE_TYPE(expr_tree)), space);
12118   space = save_expr(space);
12119   tree ref = build_fold_indirect_ref_loc(this->location(), space);
12120   TREE_THIS_NOTRAP(ref) = 1;
12121   tree ret = build2(COMPOUND_EXPR, TREE_TYPE(space),
12122                     build2(MODIFY_EXPR, void_type_node, ref, expr_tree),
12123                     space);
12124   SET_EXPR_LOCATION(ret, this->location());
12125   return ret;
12126 }
12127
12128 // Allocate a composite literal on the heap.
12129
12130 Expression*
12131 Expression::make_heap_composite(Expression* expr, source_location location)
12132 {
12133   return new Heap_composite_expression(expr, location);
12134 }
12135
12136 // Class Receive_expression.
12137
12138 // Return the type of a receive expression.
12139
12140 Type*
12141 Receive_expression::do_type()
12142 {
12143   Channel_type* channel_type = this->channel_->type()->channel_type();
12144   if (channel_type == NULL)
12145     return Type::make_error_type();
12146   return channel_type->element_type();
12147 }
12148
12149 // Check types for a receive expression.
12150
12151 void
12152 Receive_expression::do_check_types(Gogo*)
12153 {
12154   Type* type = this->channel_->type();
12155   if (type->is_error_type())
12156     {
12157       this->set_is_error();
12158       return;
12159     }
12160   if (type->channel_type() == NULL)
12161     {
12162       this->report_error(_("expected channel"));
12163       return;
12164     }
12165   if (!type->channel_type()->may_receive())
12166     {
12167       this->report_error(_("invalid receive on send-only channel"));
12168       return;
12169     }
12170 }
12171
12172 // Get a tree for a receive expression.
12173
12174 tree
12175 Receive_expression::do_get_tree(Translate_context* context)
12176 {
12177   Channel_type* channel_type = this->channel_->type()->channel_type();
12178   gcc_assert(channel_type != NULL);
12179   Type* element_type = channel_type->element_type();
12180   tree element_type_tree = element_type->get_tree(context->gogo());
12181
12182   tree channel = this->channel_->get_tree(context);
12183   if (element_type_tree == error_mark_node || channel == error_mark_node)
12184     return error_mark_node;
12185
12186   return Gogo::receive_from_channel(element_type_tree, channel,
12187                                     this->for_select_, this->location());
12188 }
12189
12190 // Make a receive expression.
12191
12192 Receive_expression*
12193 Expression::make_receive(Expression* channel, source_location location)
12194 {
12195   return new Receive_expression(channel, location);
12196 }
12197
12198 // Class Send_expression.
12199
12200 // Traversal.
12201
12202 int
12203 Send_expression::do_traverse(Traverse* traverse)
12204 {
12205   if (Expression::traverse(&this->channel_, traverse) == TRAVERSE_EXIT)
12206     return TRAVERSE_EXIT;
12207   return Expression::traverse(&this->val_, traverse);
12208 }
12209
12210 // Get the type.
12211
12212 Type*
12213 Send_expression::do_type()
12214 {
12215   return Type::lookup_bool_type();
12216 }
12217
12218 // Set types.
12219
12220 void
12221 Send_expression::do_determine_type(const Type_context*)
12222 {
12223   this->channel_->determine_type_no_context();
12224
12225   Type* type = this->channel_->type();
12226   Type_context subcontext;
12227   if (type->channel_type() != NULL)
12228     subcontext.type = type->channel_type()->element_type();
12229   this->val_->determine_type(&subcontext);
12230 }
12231
12232 // Check types.
12233
12234 void
12235 Send_expression::do_check_types(Gogo*)
12236 {
12237   Type* type = this->channel_->type();
12238   if (type->is_error_type())
12239     {
12240       this->set_is_error();
12241       return;
12242     }
12243   Channel_type* channel_type = type->channel_type();
12244   if (channel_type == NULL)
12245     {
12246       error_at(this->location(), "left operand of %<<-%> must be channel");
12247       this->set_is_error();
12248       return;
12249     }
12250   Type* element_type = channel_type->element_type();
12251   if (element_type != NULL
12252       && !Type::are_assignable(element_type, this->val_->type(), NULL))
12253     {
12254       this->report_error(_("incompatible types in send"));
12255       return;
12256     }
12257   if (!channel_type->may_send())
12258     {
12259       this->report_error(_("invalid send on receive-only channel"));
12260       return;
12261     }
12262 }
12263
12264 // Get a tree for a send expression.
12265
12266 tree
12267 Send_expression::do_get_tree(Translate_context* context)
12268 {
12269   tree channel = this->channel_->get_tree(context);
12270   tree val = this->val_->get_tree(context);
12271   if (channel == error_mark_node || val == error_mark_node)
12272     return error_mark_node;
12273   Channel_type* channel_type = this->channel_->type()->channel_type();
12274   val = Expression::convert_for_assignment(context,
12275                                            channel_type->element_type(),
12276                                            this->val_->type(),
12277                                            val,
12278                                            this->location());
12279   return Gogo::send_on_channel(channel, val, this->is_value_discarded_,
12280                                this->for_select_, this->location());
12281 }
12282
12283 // Make a send expression
12284
12285 Send_expression*
12286 Expression::make_send(Expression* channel, Expression* val,
12287                       source_location location)
12288 {
12289   return new Send_expression(channel, val, location);
12290 }
12291
12292 // An expression which evaluates to a pointer to the type descriptor
12293 // of a type.
12294
12295 class Type_descriptor_expression : public Expression
12296 {
12297  public:
12298   Type_descriptor_expression(Type* type, source_location location)
12299     : Expression(EXPRESSION_TYPE_DESCRIPTOR, location),
12300       type_(type)
12301   { }
12302
12303  protected:
12304   Type*
12305   do_type()
12306   { return Type::make_type_descriptor_ptr_type(); }
12307
12308   void
12309   do_determine_type(const Type_context*)
12310   { }
12311
12312   Expression*
12313   do_copy()
12314   { return this; }
12315
12316   tree
12317   do_get_tree(Translate_context* context)
12318   { return this->type_->type_descriptor_pointer(context->gogo()); }
12319
12320  private:
12321   // The type for which this is the descriptor.
12322   Type* type_;
12323 };
12324
12325 // Make a type descriptor expression.
12326
12327 Expression*
12328 Expression::make_type_descriptor(Type* type, source_location location)
12329 {
12330   return new Type_descriptor_expression(type, location);
12331 }
12332
12333 // An expression which evaluates to some characteristic of a type.
12334 // This is only used to initialize fields of a type descriptor.  Using
12335 // a new expression class is slightly inefficient but gives us a good
12336 // separation between the frontend and the middle-end with regard to
12337 // how types are laid out.
12338
12339 class Type_info_expression : public Expression
12340 {
12341  public:
12342   Type_info_expression(Type* type, Type_info type_info)
12343     : Expression(EXPRESSION_TYPE_INFO, BUILTINS_LOCATION),
12344       type_(type), type_info_(type_info)
12345   { }
12346
12347  protected:
12348   Type*
12349   do_type();
12350
12351   void
12352   do_determine_type(const Type_context*)
12353   { }
12354
12355   Expression*
12356   do_copy()
12357   { return this; }
12358
12359   tree
12360   do_get_tree(Translate_context* context);
12361
12362  private:
12363   // The type for which we are getting information.
12364   Type* type_;
12365   // What information we want.
12366   Type_info type_info_;
12367 };
12368
12369 // The type is chosen to match what the type descriptor struct
12370 // expects.
12371
12372 Type*
12373 Type_info_expression::do_type()
12374 {
12375   switch (this->type_info_)
12376     {
12377     case TYPE_INFO_SIZE:
12378       return Type::lookup_integer_type("uintptr");
12379     case TYPE_INFO_ALIGNMENT:
12380     case TYPE_INFO_FIELD_ALIGNMENT:
12381       return Type::lookup_integer_type("uint8");
12382     default:
12383       gcc_unreachable();
12384     }
12385 }
12386
12387 // Return type information in GENERIC.
12388
12389 tree
12390 Type_info_expression::do_get_tree(Translate_context* context)
12391 {
12392   tree type_tree = this->type_->get_tree(context->gogo());
12393   if (type_tree == error_mark_node)
12394     return error_mark_node;
12395
12396   tree val_type_tree = this->type()->get_tree(context->gogo());
12397   gcc_assert(val_type_tree != error_mark_node);
12398
12399   if (this->type_info_ == TYPE_INFO_SIZE)
12400     return fold_convert_loc(BUILTINS_LOCATION, val_type_tree,
12401                             TYPE_SIZE_UNIT(type_tree));
12402   else
12403     {
12404       unsigned int val;
12405       if (this->type_info_ == TYPE_INFO_ALIGNMENT)
12406         val = go_type_alignment(type_tree);
12407       else
12408         val = go_field_alignment(type_tree);
12409       return build_int_cstu(val_type_tree, val);
12410     }
12411 }
12412
12413 // Make a type info expression.
12414
12415 Expression*
12416 Expression::make_type_info(Type* type, Type_info type_info)
12417 {
12418   return new Type_info_expression(type, type_info);
12419 }
12420
12421 // An expression which evaluates to the offset of a field within a
12422 // struct.  This, like Type_info_expression, q.v., is only used to
12423 // initialize fields of a type descriptor.
12424
12425 class Struct_field_offset_expression : public Expression
12426 {
12427  public:
12428   Struct_field_offset_expression(Struct_type* type, const Struct_field* field)
12429     : Expression(EXPRESSION_STRUCT_FIELD_OFFSET, BUILTINS_LOCATION),
12430       type_(type), field_(field)
12431   { }
12432
12433  protected:
12434   Type*
12435   do_type()
12436   { return Type::lookup_integer_type("uintptr"); }
12437
12438   void
12439   do_determine_type(const Type_context*)
12440   { }
12441
12442   Expression*
12443   do_copy()
12444   { return this; }
12445
12446   tree
12447   do_get_tree(Translate_context* context);
12448
12449  private:
12450   // The type of the struct.
12451   Struct_type* type_;
12452   // The field.
12453   const Struct_field* field_;
12454 };
12455
12456 // Return a struct field offset in GENERIC.
12457
12458 tree
12459 Struct_field_offset_expression::do_get_tree(Translate_context* context)
12460 {
12461   tree type_tree = this->type_->get_tree(context->gogo());
12462   if (type_tree == error_mark_node)
12463     return error_mark_node;
12464
12465   tree val_type_tree = this->type()->get_tree(context->gogo());
12466   gcc_assert(val_type_tree != error_mark_node);
12467
12468   const Struct_field_list* fields = this->type_->fields();
12469   tree struct_field_tree = TYPE_FIELDS(type_tree);
12470   Struct_field_list::const_iterator p;
12471   for (p = fields->begin();
12472        p != fields->end();
12473        ++p, struct_field_tree = DECL_CHAIN(struct_field_tree))
12474     {
12475       gcc_assert(struct_field_tree != NULL_TREE);
12476       if (&*p == this->field_)
12477         break;
12478     }
12479   gcc_assert(&*p == this->field_);
12480
12481   return fold_convert_loc(BUILTINS_LOCATION, val_type_tree,
12482                           byte_position(struct_field_tree));
12483 }
12484
12485 // Make an expression for a struct field offset.
12486
12487 Expression*
12488 Expression::make_struct_field_offset(Struct_type* type,
12489                                      const Struct_field* field)
12490 {
12491   return new Struct_field_offset_expression(type, field);
12492 }
12493
12494 // An expression which evaluates to the address of an unnamed label.
12495
12496 class Label_addr_expression : public Expression
12497 {
12498  public:
12499   Label_addr_expression(Label* label, source_location location)
12500     : Expression(EXPRESSION_LABEL_ADDR, location),
12501       label_(label)
12502   { }
12503
12504  protected:
12505   Type*
12506   do_type()
12507   { return Type::make_pointer_type(Type::make_void_type()); }
12508
12509   void
12510   do_determine_type(const Type_context*)
12511   { }
12512
12513   Expression*
12514   do_copy()
12515   { return new Label_addr_expression(this->label_, this->location()); }
12516
12517   tree
12518   do_get_tree(Translate_context*)
12519   { return this->label_->get_addr(this->location()); }
12520
12521  private:
12522   // The label whose address we are taking.
12523   Label* label_;
12524 };
12525
12526 // Make an expression for the address of an unnamed label.
12527
12528 Expression*
12529 Expression::make_label_addr(Label* label, source_location location)
12530 {
12531   return new Label_addr_expression(label, location);
12532 }
12533
12534 // Import an expression.  This comes at the end in order to see the
12535 // various class definitions.
12536
12537 Expression*
12538 Expression::import_expression(Import* imp)
12539 {
12540   int c = imp->peek_char();
12541   if (imp->match_c_string("- ")
12542       || imp->match_c_string("! ")
12543       || imp->match_c_string("^ "))
12544     return Unary_expression::do_import(imp);
12545   else if (c == '(')
12546     return Binary_expression::do_import(imp);
12547   else if (imp->match_c_string("true")
12548            || imp->match_c_string("false"))
12549     return Boolean_expression::do_import(imp);
12550   else if (c == '"')
12551     return String_expression::do_import(imp);
12552   else if (c == '-' || (c >= '0' && c <= '9'))
12553     {
12554       // This handles integers, floats and complex constants.
12555       return Integer_expression::do_import(imp);
12556     }
12557   else if (imp->match_c_string("nil"))
12558     return Nil_expression::do_import(imp);
12559   else if (imp->match_c_string("convert"))
12560     return Type_conversion_expression::do_import(imp);
12561   else
12562     {
12563       error_at(imp->location(), "import error: expected expression");
12564       return Expression::make_error(imp->location());
12565     }
12566 }
12567
12568 // Class Expression_list.
12569
12570 // Traverse the list.
12571
12572 int
12573 Expression_list::traverse(Traverse* traverse)
12574 {
12575   for (Expression_list::iterator p = this->begin();
12576        p != this->end();
12577        ++p)
12578     {
12579       if (*p != NULL)
12580         {
12581           if (Expression::traverse(&*p, traverse) == TRAVERSE_EXIT)
12582             return TRAVERSE_EXIT;
12583         }
12584     }
12585   return TRAVERSE_CONTINUE;
12586 }
12587
12588 // Copy the list.
12589
12590 Expression_list*
12591 Expression_list::copy()
12592 {
12593   Expression_list* ret = new Expression_list();
12594   for (Expression_list::iterator p = this->begin();
12595        p != this->end();
12596        ++p)
12597     {
12598       if (*p == NULL)
12599         ret->push_back(NULL);
12600       else
12601         ret->push_back((*p)->copy());
12602     }
12603   return ret;
12604 }
12605
12606 // Return whether an expression list has an error expression.
12607
12608 bool
12609 Expression_list::contains_error() const
12610 {
12611   for (Expression_list::const_iterator p = this->begin();
12612        p != this->end();
12613        ++p)
12614     if (*p != NULL && (*p)->is_error_expression())
12615       return true;
12616   return false;
12617 }