gcc/go/go-gcc.cc

   1 // go-gcc.cc -- Go frontend to gcc IR.
   2 // Copyright (C) 2011, 2012 Free Software Foundation, Inc.
   3 // Contributed by Ian Lance Taylor, Google.
   4
   5 // This file is part of GCC.
   6
   7 // GCC is free software; you can redistribute it and/or modify it under
   8 // the terms of the GNU General Public License as published by the Free
   9 // Software Foundation; either version 3, or (at your option) any later
  10 // version.
  11
  12 // GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  13 // WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14 // FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15 // for more details.
  16
  17 // You should have received a copy of the GNU General Public License
  18 // along with GCC; see the file COPYING3.  If not see
  19 // <http://www.gnu.org/licenses/>.
  20
  21 #include "go-system.h"
  22
  23 // This has to be included outside of extern "C", so we have to
  24 // include it here before tree.h includes it later.
  25 #include <gmp.h>
  26
  27 #ifndef ENABLE_BUILD_WITH_CXX
  28 extern "C"
  29 {
  30 #endif
  31
  32 #include "tree.h"
  33 #include "tree-iterator.h"
  34 #include "gimple.h"
  35 #include "toplev.h"
  36
  37 #ifndef ENABLE_BUILD_WITH_CXX
  38 }
  39 #endif
  40
  41 #include "go-c.h"
  42
  43 #include "gogo.h"
  44 #include "backend.h"
  45
  46 // A class wrapping a tree.
  47
  48 class Gcc_tree
  49 {
  50  public:
  51   Gcc_tree(tree t)
  52     : t_(t)
  53   { }
  54
  55   tree
  56   get_tree() const
  57   { return this->t_; }
  58
  59  private:
  60   tree t_;
  61 };
  62
  63 // In gcc, types, expressions, and statements are all trees.
  64 class Btype : public Gcc_tree
  65 {
  66  public:
  67   Btype(tree t)
  68     : Gcc_tree(t)
  69   { }
  70 };
  71
  72 class Bexpression : public Gcc_tree
  73 {
  74  public:
  75   Bexpression(tree t)
  76     : Gcc_tree(t)
  77   { }
  78 };
  79
  80 class Bstatement : public Gcc_tree
  81 {
  82  public:
  83   Bstatement(tree t)
  84     : Gcc_tree(t)
  85   { }
  86 };
  87
  88 class Bfunction : public Gcc_tree
  89 {
  90  public:
  91   Bfunction(tree t)
  92     : Gcc_tree(t)
  93   { }
  94 };
  95
  96 class Bblock : public Gcc_tree
  97 {
  98  public:
  99   Bblock(tree t)
 100     : Gcc_tree(t)
 101   { }
 102 };
 103
 104 class Bvariable : public Gcc_tree
 105 {
 106  public:
 107   Bvariable(tree t)
 108     : Gcc_tree(t)
 109   { }
 110 };
 111
 112 class Blabel : public Gcc_tree
 113 {
 114  public:
 115   Blabel(tree t)
 116     : Gcc_tree(t)
 117   { }
 118 };
 119
 120 // This file implements the interface between the Go frontend proper
 121 // and the gcc IR.  This implements specific instantiations of
 122 // abstract classes defined by the Go frontend proper.  The Go
 123 // frontend proper class methods of these classes to generate the
 124 // backend representation.
 125
 126 class Gcc_backend : public Backend
 127 {
 128  public:
 129   // Types.
 130
 131   Btype*
 132   error_type()
 133   { return this->make_type(error_mark_node); }
 134
 135   Btype*
 136   void_type()
 137   { return this->make_type(void_type_node); }
 138
 139   Btype*
 140   bool_type()
 141   { return this->make_type(boolean_type_node); }
 142
 143   Btype*
 144   integer_type(bool, int);
 145
 146   Btype*
 147   float_type(int);
 148
 149   Btype*
 150   complex_type(int);
 151
 152   Btype*
 153   pointer_type(Btype*);
 154
 155   Btype*
 156   function_type(const Btyped_identifier&,
 157                 const std::vector<Btyped_identifier>&,
 158                 const std::vector<Btyped_identifier>&,
 159                 const Location);
 160
 161   Btype*
 162   struct_type(const std::vector<Btyped_identifier>&);
 163
 164   Btype*
 165   array_type(Btype*, Bexpression*);
 166
 167   Btype*
 168   placeholder_pointer_type(const std::string&, Location, bool);
 169
 170   bool
 171   set_placeholder_pointer_type(Btype*, Btype*);
 172
 173   bool
 174   set_placeholder_function_type(Btype*, Btype*);
 175
 176   Btype*
 177   placeholder_struct_type(const std::string&, Location);
 178
 179   bool
 180   set_placeholder_struct_type(Btype* placeholder,
 181                               const std::vector<Btyped_identifier>&);
 182
 183   Btype*
 184   placeholder_array_type(const std::string&, Location);
 185
 186   bool
 187   set_placeholder_array_type(Btype*, Btype*, Bexpression*);
 188
 189   Btype*
 190   named_type(const std::string&, Btype*, Location);
 191
 192   Btype*
 193   circular_pointer_type(Btype*, bool);
 194
 195   bool
 196   is_circular_pointer_type(Btype*);
 197
 198   size_t
 199   type_size(Btype*);
 200
 201   size_t
 202   type_alignment(Btype*);
 203
 204   size_t
 205   type_field_alignment(Btype*);
 206
 207   size_t
 208   type_field_offset(Btype*, size_t index);
 209
 210   // Expressions.
 211
 212   Bexpression*
 213   zero_expression(Btype*);
 214
 215   // Statements.
 216
 217   Bstatement*
 218   error_statement()
 219   { return this->make_statement(error_mark_node); }
 220
 221   Bstatement*
 222   expression_statement(Bexpression*);
 223
 224   Bstatement*
 225   init_statement(Bvariable* var, Bexpression* init);
 226
 227   Bstatement*
 228   assignment_statement(Bexpression* lhs, Bexpression* rhs, Location);
 229
 230   Bstatement*
 231   return_statement(Bfunction*, const std::vector<Bexpression*>&,
 232                    Location);
 233
 234   Bstatement*
 235   if_statement(Bexpression* condition, Bblock* then_block, Bblock* else_block,
 236                Location);
 237
 238   Bstatement*
 239   switch_statement(Bexpression* value,
 240                    const std::vector<std::vector<Bexpression*> >& cases,
 241                    const std::vector<Bstatement*>& statements,
 242                    Location);
 243
 244   Bstatement*
 245   compound_statement(Bstatement*, Bstatement*);
 246
 247   Bstatement*
 248   statement_list(const std::vector<Bstatement*>&);
 249
 250   // Blocks.
 251
 252   Bblock*
 253   block(Bfunction*, Bblock*, const std::vector<Bvariable*>&,
 254         Location, Location);
 255
 256   void
 257   block_add_statements(Bblock*, const std::vector<Bstatement*>&);
 258
 259   Bstatement*
 260   block_statement(Bblock*);
 261
 262   // Variables.
 263
 264   Bvariable*
 265   error_variable()
 266   { return new Bvariable(error_mark_node); }
 267
 268   Bvariable*
 269   global_variable(const std::string& package_name,
 270                   const std::string& unique_prefix,
 271                   const std::string& name,
 272                   Btype* btype,
 273                   bool is_external,
 274                   bool is_hidden,
 275                   Location location);
 276
 277   void
 278   global_variable_set_init(Bvariable*, Bexpression*);
 279
 280   Bvariable*
 281   local_variable(Bfunction*, const std::string&, Btype*, bool,
 282                  Location);
 283
 284   Bvariable*
 285   parameter_variable(Bfunction*, const std::string&, Btype*, bool,
 286                      Location);
 287
 288   Bvariable*
 289   temporary_variable(Bfunction*, Bblock*, Btype*, Bexpression*, bool,
 290                      Location, Bstatement**);
 291
 292   Bvariable*
 293   immutable_struct(const std::string&, bool, Btype*, Location);
 294
 295   void
 296   immutable_struct_set_init(Bvariable*, const std::string&, bool, Btype*,
 297                             Location, Bexpression*);
 298
 299   Bvariable*
 300   immutable_struct_reference(const std::string&, Btype*, Location);
 301
 302   // Labels.
 303
 304   Blabel*
 305   label(Bfunction*, const std::string& name, Location);
 306
 307   Bstatement*
 308   label_definition_statement(Blabel*);
 309
 310   Bstatement*
 311   goto_statement(Blabel*, Location);
 312
 313   Bexpression*
 314   label_address(Blabel*, Location);
 315
 316  private:
 317   // Make a Bexpression from a tree.
 318   Bexpression*
 319   make_expression(tree t)
 320   { return new Bexpression(t); }
 321
 322   // Make a Bstatement from a tree.
 323   Bstatement*
 324   make_statement(tree t)
 325   { return new Bstatement(t); }
 326
 327   // Make a Btype from a tree.
 328   Btype*
 329   make_type(tree t)
 330   { return new Btype(t); }
 331
 332   Btype*
 333   fill_in_struct(Btype*, const std::vector<Btyped_identifier>&);
 334
 335   Btype*
 336   fill_in_array(Btype*, Btype*, Bexpression*);
 337 };
 338
 339 // A helper function.
 340
 341 static inline tree
 342 get_identifier_from_string(const std::string& str)
 343 {
 344   return get_identifier_with_length(str.data(), str.length());
 345 }
 346
 347 // Get an unnamed integer type.
 348
 349 Btype*
 350 Gcc_backend::integer_type(bool is_unsigned, int bits)
 351 {
 352   tree type;
 353   if (is_unsigned)
 354     {
 355       if (bits == INT_TYPE_SIZE)
 356         type = unsigned_type_node;
 357       else if (bits == CHAR_TYPE_SIZE)
 358         type = unsigned_char_type_node;
 359       else if (bits == SHORT_TYPE_SIZE)
 360         type = short_unsigned_type_node;
 361       else if (bits == LONG_TYPE_SIZE)
 362         type = long_unsigned_type_node;
 363       else if (bits == LONG_LONG_TYPE_SIZE)
 364         type = long_long_unsigned_type_node;
 365       else
 366         type = make_unsigned_type(bits);
 367     }
 368   else
 369     {
 370       if (bits == INT_TYPE_SIZE)
 371         type = integer_type_node;
 372       else if (bits == CHAR_TYPE_SIZE)
 373         type = signed_char_type_node;
 374       else if (bits == SHORT_TYPE_SIZE)
 375         type = short_integer_type_node;
 376       else if (bits == LONG_TYPE_SIZE)
 377         type = long_integer_type_node;
 378       else if (bits == LONG_LONG_TYPE_SIZE)
 379         type = long_long_integer_type_node;
 380       else
 381         type = make_signed_type(bits);
 382     }
 383   return this->make_type(type);
 384 }
 385
 386 // Get an unnamed float type.
 387
 388 Btype*
 389 Gcc_backend::float_type(int bits)
 390 {
 391   tree type;
 392   if (bits == FLOAT_TYPE_SIZE)
 393     type = float_type_node;
 394   else if (bits == DOUBLE_TYPE_SIZE)
 395     type = double_type_node;
 396   else if (bits == LONG_DOUBLE_TYPE_SIZE)
 397     type = long_double_type_node;
 398   else
 399     {
 400       type = make_node(REAL_TYPE);
 401       TYPE_PRECISION(type) = bits;
 402       layout_type(type);
 403     }
 404   return this->make_type(type);
 405 }
 406
 407 // Get an unnamed complex type.
 408
 409 Btype*
 410 Gcc_backend::complex_type(int bits)
 411 {
 412   tree type;
 413   if (bits == FLOAT_TYPE_SIZE * 2)
 414     type = complex_float_type_node;
 415   else if (bits == DOUBLE_TYPE_SIZE * 2)
 416     type = complex_double_type_node;
 417   else if (bits == LONG_DOUBLE_TYPE_SIZE * 2)
 418     type = complex_long_double_type_node;
 419   else
 420     {
 421       type = make_node(REAL_TYPE);
 422       TYPE_PRECISION(type) = bits / 2;
 423       layout_type(type);
 424       type = build_complex_type(type);
 425     }
 426   return this->make_type(type);
 427 }
 428
 429 // Get a pointer type.
 430
 431 Btype*
 432 Gcc_backend::pointer_type(Btype* to_type)
 433 {
 434   tree to_type_tree = to_type->get_tree();
 435   if (to_type_tree == error_mark_node)
 436     return this->error_type();
 437   tree type = build_pointer_type(to_type_tree);
 438   return this->make_type(type);
 439 }
 440
 441 // Make a function type.
 442
 443 Btype*
 444 Gcc_backend::function_type(const Btyped_identifier& receiver,
 445                            const std::vector<Btyped_identifier>& parameters,
 446                            const std::vector<Btyped_identifier>& results,
 447                            Location location)
 448 {
 449   tree args = NULL_TREE;
 450   tree* pp = &args;
 451   if (receiver.btype != NULL)
 452     {
 453       tree t = receiver.btype->get_tree();
 454       if (t == error_mark_node)
 455         return this->error_type();
 456       *pp = tree_cons(NULL_TREE, t, NULL_TREE);
 457       pp = &TREE_CHAIN(*pp);
 458     }
 459
 460   for (std::vector<Btyped_identifier>::const_iterator p = parameters.begin();
 461        p != parameters.end();
 462        ++p)
 463     {
 464       tree t = p->btype->get_tree();
 465       if (t == error_mark_node)
 466         return this->error_type();
 467       *pp = tree_cons(NULL_TREE, t, NULL_TREE);
 468       pp = &TREE_CHAIN(*pp);
 469     }
 470
 471   // Varargs is handled entirely at the Go level.  When converted to
 472   // GENERIC functions are not varargs.
 473   *pp = void_list_node;
 474
 475   tree result;
 476   if (results.empty())
 477     result = void_type_node;
 478   else if (results.size() == 1)
 479     result = results.front().btype->get_tree();
 480   else
 481     {
 482       result = make_node(RECORD_TYPE);
 483       tree field_trees = NULL_TREE;
 484       pp = &field_trees;
 485       for (std::vector<Btyped_identifier>::const_iterator p = results.begin();
 486            p != results.end();
 487            ++p)
 488         {
 489           const std::string name = (p->name.empty()
 490                                     ? "UNNAMED"
 491                                     : p->name);
 492           tree name_tree = get_identifier_from_string(name);
 493           tree field_type_tree = p->btype->get_tree();
 494           if (field_type_tree == error_mark_node)
 495             return this->error_type();
 496           gcc_assert(TYPE_SIZE(field_type_tree) != NULL_TREE);
 497           tree field = build_decl(location.gcc_location(), FIELD_DECL,
 498                                   name_tree, field_type_tree);
 499           DECL_CONTEXT(field) = result;
 500           *pp = field;
 501           pp = &DECL_CHAIN(field);
 502         }
 503       TYPE_FIELDS(result) = field_trees;
 504       layout_type(result);
 505     }
 506   if (result == error_mark_node)
 507     return this->error_type();
 508
 509   tree fntype = build_function_type(result, args);
 510   if (fntype == error_mark_node)
 511     return this->error_type();
 512
 513   return this->make_type(build_pointer_type(fntype));
 514 }
 515
 516 // Make a struct type.
 517
 518 Btype*
 519 Gcc_backend::struct_type(const std::vector<Btyped_identifier>& fields)
 520 {
 521   return this->fill_in_struct(this->make_type(make_node(RECORD_TYPE)), fields);
 522 }
 523
 524 // Fill in the fields of a struct type.
 525
 526 Btype*
 527 Gcc_backend::fill_in_struct(Btype* fill,
 528                             const std::vector<Btyped_identifier>& fields)
 529 {
 530   tree fill_tree = fill->get_tree();
 531   tree field_trees = NULL_TREE;
 532   tree* pp = &field_trees;
 533   for (std::vector<Btyped_identifier>::const_iterator p = fields.begin();
 534        p != fields.end();
 535        ++p)
 536     {
 537       tree name_tree = get_identifier_from_string(p->name);
 538       tree type_tree = p->btype->get_tree();
 539       if (type_tree == error_mark_node)
 540         return this->error_type();
 541       tree field = build_decl(p->location.gcc_location(), FIELD_DECL, name_tree,
 542                               type_tree);
 543       DECL_CONTEXT(field) = fill_tree;
 544       *pp = field;
 545       pp = &DECL_CHAIN(field);
 546     }
 547   TYPE_FIELDS(fill_tree) = field_trees;
 548   layout_type(fill_tree);
 549   return fill;
 550 }
 551
 552 // Make an array type.
 553
 554 Btype*
 555 Gcc_backend::array_type(Btype* element_btype, Bexpression* length)
 556 {
 557   return this->fill_in_array(this->make_type(make_node(ARRAY_TYPE)),
 558                              element_btype, length);
 559 }
 560
 561 // Fill in an array type.
 562
 563 Btype*
 564 Gcc_backend::fill_in_array(Btype* fill, Btype* element_type,
 565                            Bexpression* length)
 566 {
 567   tree element_type_tree = element_type->get_tree();
 568   tree length_tree = length->get_tree();
 569   if (element_type_tree == error_mark_node || length_tree == error_mark_node)
 570     return this->error_type();
 571
 572   gcc_assert(TYPE_SIZE(element_type_tree) != NULL_TREE);
 573
 574   length_tree = fold_convert(sizetype, length_tree);
 575
 576   // build_index_type takes the maximum index, which is one less than
 577   // the length.
 578   tree index_type_tree = build_index_type(fold_build2(MINUS_EXPR, sizetype,
 579                                                       length_tree,
 580                                                       size_one_node));
 581
 582   tree fill_tree = fill->get_tree();
 583   TREE_TYPE(fill_tree) = element_type_tree;
 584   TYPE_DOMAIN(fill_tree) = index_type_tree;
 585   TYPE_ADDR_SPACE(fill_tree) = TYPE_ADDR_SPACE(element_type_tree);
 586   layout_type(fill_tree);
 587
 588   if (TYPE_STRUCTURAL_EQUALITY_P(element_type_tree))
 589     SET_TYPE_STRUCTURAL_EQUALITY(fill_tree);
 590   else if (TYPE_CANONICAL(element_type_tree) != element_type_tree
 591            || TYPE_CANONICAL(index_type_tree) != index_type_tree)
 592     TYPE_CANONICAL(fill_tree) =
 593       build_array_type(TYPE_CANONICAL(element_type_tree),
 594                        TYPE_CANONICAL(index_type_tree));
 595
 596   return fill;
 597 }
 598
 599 // Create a placeholder for a pointer type.
 600
 601 Btype*
 602 Gcc_backend::placeholder_pointer_type(const std::string& name,
 603                                       Location location, bool)
 604 {
 605   tree ret = build_variant_type_copy(ptr_type_node);
 606   if (!name.empty())
 607     {
 608       tree decl = build_decl(location.gcc_location(), TYPE_DECL,
 609                              get_identifier_from_string(name),
 610                              ret);
 611       TYPE_NAME(ret) = decl;
 612     }
 613   return this->make_type(ret);
 614 }
 615
 616 // Set the real target type for a placeholder pointer type.
 617
 618 bool
 619 Gcc_backend::set_placeholder_pointer_type(Btype* placeholder,
 620                                           Btype* to_type)
 621 {
 622   tree pt = placeholder->get_tree();
 623   if (pt == error_mark_node)
 624     return false;
 625   gcc_assert(TREE_CODE(pt) == POINTER_TYPE);
 626   tree tt = to_type->get_tree();
 627   if (tt == error_mark_node)
 628     {
 629       TREE_TYPE(pt) = tt;
 630       return false;
 631     }
 632   gcc_assert(TREE_CODE(tt) == POINTER_TYPE);
 633   TREE_TYPE(pt) = TREE_TYPE(tt);
 634   if (TYPE_NAME(pt) != NULL_TREE)
 635     {
 636       // Build the data structure gcc wants to see for a typedef.
 637       tree copy = build_variant_type_copy(pt);
 638       TYPE_NAME(copy) = NULL_TREE;
 639       DECL_ORIGINAL_TYPE(TYPE_NAME(pt)) = copy;
 640     }
 641   return true;
 642 }
 643
 644 // Set the real values for a placeholder function type.
 645
 646 bool
 647 Gcc_backend::set_placeholder_function_type(Btype* placeholder, Btype* ft)
 648 {
 649   return this->set_placeholder_pointer_type(placeholder, ft);
 650 }
 651
 652 // Create a placeholder for a struct type.
 653
 654 Btype*
 655 Gcc_backend::placeholder_struct_type(const std::string& name,
 656                                      Location location)
 657 {
 658   tree ret = make_node(RECORD_TYPE);
 659   tree decl = build_decl(location.gcc_location(), TYPE_DECL,
 660                          get_identifier_from_string(name),
 661                          ret);
 662   TYPE_NAME(ret) = decl;
 663   return this->make_type(ret);
 664 }
 665
 666 // Fill in the fields of a placeholder struct type.
 667
 668 bool
 669 Gcc_backend::set_placeholder_struct_type(
 670     Btype* placeholder,
 671     const std::vector<Btyped_identifier>& fields)
 672 {
 673   tree t = placeholder->get_tree();
 674   gcc_assert(TREE_CODE(t) == RECORD_TYPE && TYPE_FIELDS(t) == NULL_TREE);
 675   Btype* r = this->fill_in_struct(placeholder, fields);
 676
 677   // Build the data structure gcc wants to see for a typedef.
 678   tree copy = build_distinct_type_copy(t);
 679   TYPE_NAME(copy) = NULL_TREE;
 680   DECL_ORIGINAL_TYPE(TYPE_NAME(t)) = copy;
 681
 682   return r->get_tree() != error_mark_node;
 683 }
 684
 685 // Create a placeholder for an array type.
 686
 687 Btype*
 688 Gcc_backend::placeholder_array_type(const std::string& name,
 689                                     Location location)
 690 {
 691   tree ret = make_node(ARRAY_TYPE);
 692   tree decl = build_decl(location.gcc_location(), TYPE_DECL,
 693                          get_identifier_from_string(name),
 694                          ret);
 695   TYPE_NAME(ret) = decl;
 696   return this->make_type(ret);
 697 }
 698
 699 // Fill in the fields of a placeholder array type.
 700
 701 bool
 702 Gcc_backend::set_placeholder_array_type(Btype* placeholder,
 703                                         Btype* element_btype,
 704                                         Bexpression* length)
 705 {
 706   tree t = placeholder->get_tree();
 707   gcc_assert(TREE_CODE(t) == ARRAY_TYPE && TREE_TYPE(t) == NULL_TREE);
 708   Btype* r = this->fill_in_array(placeholder, element_btype, length);
 709
 710   // Build the data structure gcc wants to see for a typedef.
 711   tree copy = build_distinct_type_copy(t);
 712   TYPE_NAME(copy) = NULL_TREE;
 713   DECL_ORIGINAL_TYPE(TYPE_NAME(t)) = copy;
 714
 715   return r->get_tree() != error_mark_node;
 716 }
 717
 718 // Return a named version of a type.
 719
 720 Btype*
 721 Gcc_backend::named_type(const std::string& name, Btype* btype,
 722                         Location location)
 723 {
 724   tree type = btype->get_tree();
 725   if (type == error_mark_node)
 726     return this->error_type();
 727
 728   // The middle-end expects a basic type to have a name.  In Go every
 729   // basic type will have a name.  The first time we see a basic type,
 730   // give it whatever Go name we have at this point.
 731   if (TYPE_NAME(type) == NULL_TREE
 732       && location.gcc_location() == BUILTINS_LOCATION
 733       && (TREE_CODE(type) == INTEGER_TYPE
 734           || TREE_CODE(type) == REAL_TYPE
 735           || TREE_CODE(type) == COMPLEX_TYPE
 736           || TREE_CODE(type) == BOOLEAN_TYPE))
 737     {
 738       tree decl = build_decl(BUILTINS_LOCATION, TYPE_DECL,
 739                              get_identifier_from_string(name),
 740                              type);
 741       TYPE_NAME(type) = decl;
 742       return this->make_type(type);
 743     }
 744
 745   tree copy = build_variant_type_copy(type);
 746   tree decl = build_decl(location.gcc_location(), TYPE_DECL,
 747                          get_identifier_from_string(name),
 748                          copy);
 749   DECL_ORIGINAL_TYPE(decl) = type;
 750   TYPE_NAME(copy) = decl;
 751   return this->make_type(copy);
 752 }
 753
 754 // Return a pointer type used as a marker for a circular type.
 755
 756 Btype*
 757 Gcc_backend::circular_pointer_type(Btype*, bool)
 758 {
 759   return this->make_type(ptr_type_node);
 760 }
 761
 762 // Return whether we might be looking at a circular type.
 763
 764 bool
 765 Gcc_backend::is_circular_pointer_type(Btype* btype)
 766 {
 767   return btype->get_tree() == ptr_type_node;
 768 }
 769
 770 // Return the size of a type.
 771
 772 size_t
 773 Gcc_backend::type_size(Btype* btype)
 774 {
 775   tree t = TYPE_SIZE_UNIT(btype->get_tree());
 776   gcc_assert(TREE_CODE(t) == INTEGER_CST);
 777   gcc_assert(TREE_INT_CST_HIGH(t) == 0);
 778   unsigned HOST_WIDE_INT val_wide = TREE_INT_CST_LOW(t);
 779   size_t ret = static_cast<size_t>(val_wide);
 780   gcc_assert(ret == val_wide);
 781   return ret;
 782 }
 783
 784 // Return the alignment of a type.
 785
 786 size_t
 787 Gcc_backend::type_alignment(Btype* btype)
 788 {
 789   return TYPE_ALIGN_UNIT(btype->get_tree());
 790 }
 791
 792 // Return the alignment of a struct field of type BTYPE.
 793
 794 size_t
 795 Gcc_backend::type_field_alignment(Btype* btype)
 796 {
 797   return go_field_alignment(btype->get_tree());
 798 }
 799
 800 // Return the offset of a field in a struct.
 801
 802 size_t
 803 Gcc_backend::type_field_offset(Btype* btype, size_t index)
 804 {
 805   tree struct_tree = btype->get_tree();
 806   gcc_assert(TREE_CODE(struct_tree) == RECORD_TYPE);
 807   tree field = TYPE_FIELDS(struct_tree);
 808   for (; index > 0; --index)
 809     {
 810       field = DECL_CHAIN(field);
 811       gcc_assert(field != NULL_TREE);
 812     }
 813   HOST_WIDE_INT offset_wide = int_byte_position(field);
 814   gcc_assert(offset_wide >= 0);
 815   size_t ret = static_cast<size_t>(offset_wide);
 816   gcc_assert(ret == static_cast<unsigned HOST_WIDE_INT>(offset_wide));
 817   return ret;
 818 }
 819
 820 // Return the zero value for a type.
 821
 822 Bexpression*
 823 Gcc_backend::zero_expression(Btype* btype)
 824 {
 825   tree t = btype->get_tree();
 826   tree ret;
 827   if (t == error_mark_node)
 828     ret = error_mark_node;
 829   else
 830     ret = build_zero_cst(t);
 831   return tree_to_expr(ret);
 832 }
 833
 834 // An expression as a statement.
 835
 836 Bstatement*
 837 Gcc_backend::expression_statement(Bexpression* expr)
 838 {
 839   return this->make_statement(expr->get_tree());
 840 }
 841
 842 // Variable initialization.
 843
 844 Bstatement*
 845 Gcc_backend::init_statement(Bvariable* var, Bexpression* init)
 846 {
 847   tree var_tree = var->get_tree();
 848   tree init_tree = init->get_tree();
 849   if (var_tree == error_mark_node || init_tree == error_mark_node)
 850     return this->error_statement();
 851   gcc_assert(TREE_CODE(var_tree) == VAR_DECL);
 852   DECL_INITIAL(var_tree) = init_tree;
 853   return this->make_statement(build1_loc(DECL_SOURCE_LOCATION(var_tree),
 854                                          DECL_EXPR, void_type_node, var_tree));
 855 }
 856
 857 // Assignment.
 858
 859 Bstatement*
 860 Gcc_backend::assignment_statement(Bexpression* lhs, Bexpression* rhs,
 861                                   Location location)
 862 {
 863   tree lhs_tree = lhs->get_tree();
 864   tree rhs_tree = rhs->get_tree();
 865   if (lhs_tree == error_mark_node || rhs_tree == error_mark_node)
 866     return this->error_statement();
 867   return this->make_statement(fold_build2_loc(location.gcc_location(),
 868                                               MODIFY_EXPR,
 869                                               void_type_node,
 870                                               lhs_tree, rhs_tree));
 871 }
 872
 873 // Return.
 874
 875 Bstatement*
 876 Gcc_backend::return_statement(Bfunction* bfunction,
 877                               const std::vector<Bexpression*>& vals,
 878                               Location location)
 879 {
 880   tree fntree = bfunction->get_tree();
 881   if (fntree == error_mark_node)
 882     return this->error_statement();
 883   tree result = DECL_RESULT(fntree);
 884   if (result == error_mark_node)
 885     return this->error_statement();
 886   tree ret;
 887   if (vals.empty())
 888     ret = fold_build1_loc(location.gcc_location(), RETURN_EXPR, void_type_node,
 889                           NULL_TREE);
 890   else if (vals.size() == 1)
 891     {
 892       tree val = vals.front()->get_tree();
 893       if (val == error_mark_node)
 894         return this->error_statement();
 895       tree set = fold_build2_loc(location.gcc_location(), MODIFY_EXPR,
 896                                  void_type_node, result,
 897                                  vals.front()->get_tree());
 898       ret = fold_build1_loc(location.gcc_location(), RETURN_EXPR,
 899                             void_type_node, set);
 900     }
 901   else
 902     {
 903       // To return multiple values, copy the values into a temporary
 904       // variable of the right structure type, and then assign the
 905       // temporary variable to the DECL_RESULT in the return
 906       // statement.
 907       tree stmt_list = NULL_TREE;
 908       tree rettype = TREE_TYPE(result);
 909       tree rettmp = create_tmp_var(rettype, "RESULT");
 910       tree field = TYPE_FIELDS(rettype);
 911       for (std::vector<Bexpression*>::const_iterator p = vals.begin();
 912            p != vals.end();
 913            p++, field = DECL_CHAIN(field))
 914         {
 915           gcc_assert(field != NULL_TREE);
 916           tree ref = fold_build3_loc(location.gcc_location(), COMPONENT_REF,
 917                                      TREE_TYPE(field), rettmp, field,
 918                                      NULL_TREE);
 919           tree val = (*p)->get_tree();
 920           if (val == error_mark_node)
 921             return this->error_statement();
 922           tree set = fold_build2_loc(location.gcc_location(), MODIFY_EXPR,
 923                                      void_type_node,
 924                                      ref, (*p)->get_tree());
 925           append_to_statement_list(set, &stmt_list);
 926         }
 927       gcc_assert(field == NULL_TREE);
 928       tree set = fold_build2_loc(location.gcc_location(), MODIFY_EXPR,
 929                                  void_type_node,
 930                                  result, rettmp);
 931       tree ret_expr = fold_build1_loc(location.gcc_location(), RETURN_EXPR,
 932                                       void_type_node, set);
 933       append_to_statement_list(ret_expr, &stmt_list);
 934       ret = stmt_list;
 935     }
 936   return this->make_statement(ret);
 937 }
 938
 939 // If.
 940
 941 Bstatement*
 942 Gcc_backend::if_statement(Bexpression* condition, Bblock* then_block,
 943                           Bblock* else_block, Location location)
 944 {
 945   tree cond_tree = condition->get_tree();
 946   tree then_tree = then_block->get_tree();
 947   tree else_tree = else_block == NULL ? NULL_TREE : else_block->get_tree();
 948   if (cond_tree == error_mark_node
 949       || then_tree == error_mark_node
 950       || else_tree == error_mark_node)
 951     return this->error_statement();
 952   tree ret = build3_loc(location.gcc_location(), COND_EXPR, void_type_node,
 953                         cond_tree, then_tree, else_tree);
 954   return this->make_statement(ret);
 955 }
 956
 957 // Switch.
 958
 959 Bstatement*
 960 Gcc_backend::switch_statement(
 961     Bexpression* value,
 962     const std::vector<std::vector<Bexpression*> >& cases,
 963     const std::vector<Bstatement*>& statements,
 964     Location switch_location)
 965 {
 966   gcc_assert(cases.size() == statements.size());
 967
 968   tree stmt_list = NULL_TREE;
 969   std::vector<std::vector<Bexpression*> >::const_iterator pc = cases.begin();
 970   for (std::vector<Bstatement*>::const_iterator ps = statements.begin();
 971        ps != statements.end();
 972        ++ps, ++pc)
 973     {
 974       if (pc->empty())
 975         {
 976           source_location loc = (*ps != NULL
 977                                  ? EXPR_LOCATION((*ps)->get_tree())
 978                                  : UNKNOWN_LOCATION);
 979           tree label = create_artificial_label(loc);
 980           tree c = build_case_label(NULL_TREE, NULL_TREE, label);
 981           append_to_statement_list(c, &stmt_list);
 982         }
 983       else
 984         {
 985           for (std::vector<Bexpression*>::const_iterator pcv = pc->begin();
 986                pcv != pc->end();
 987                ++pcv)
 988             {
 989               tree t = (*pcv)->get_tree();
 990               if (t == error_mark_node)
 991                 return this->error_statement();
 992               source_location loc = EXPR_LOCATION(t);
 993               tree label = create_artificial_label(loc);
 994               tree c = build_case_label((*pcv)->get_tree(), NULL_TREE, label);
 995               append_to_statement_list(c, &stmt_list);
 996             }
 997         }
 998
 999       if (*ps != NULL)
1000         {
1001           tree t = (*ps)->get_tree();
1002           if (t == error_mark_node)
1003             return this->error_statement();
1004           append_to_statement_list(t, &stmt_list);
1005         }
1006     }
1007
1008   tree tv = value->get_tree();
1009   if (tv == error_mark_node)
1010     return this->error_statement();
1011   tree t = build3_loc(switch_location.gcc_location(), SWITCH_EXPR,
1012                       void_type_node, tv, stmt_list, NULL_TREE);
1013   return this->make_statement(t);
1014 }
1015
1016 // Pair of statements.
1017
1018 Bstatement*
1019 Gcc_backend::compound_statement(Bstatement* s1, Bstatement* s2)
1020 {
1021   tree stmt_list = NULL_TREE;
1022   tree t = s1->get_tree();
1023   if (t == error_mark_node)
1024     return this->error_statement();
1025   append_to_statement_list(t, &stmt_list);
1026   t = s2->get_tree();
1027   if (t == error_mark_node)
1028     return this->error_statement();
1029   append_to_statement_list(t, &stmt_list);
1030   return this->make_statement(stmt_list);
1031 }
1032
1033 // List of statements.
1034
1035 Bstatement*
1036 Gcc_backend::statement_list(const std::vector<Bstatement*>& statements)
1037 {
1038   tree stmt_list = NULL_TREE;
1039   for (std::vector<Bstatement*>::const_iterator p = statements.begin();
1040        p != statements.end();
1041        ++p)
1042     {
1043       tree t = (*p)->get_tree();
1044       if (t == error_mark_node)
1045         return this->error_statement();
1046       append_to_statement_list(t, &stmt_list);
1047     }
1048   return this->make_statement(stmt_list);
1049 }
1050
1051 // Make a block.  For some reason gcc uses a dual structure for
1052 // blocks: BLOCK tree nodes and BIND_EXPR tree nodes.  Since the
1053 // BIND_EXPR node points to the BLOCK node, we store the BIND_EXPR in
1054 // the Bblock.
1055
1056 Bblock*
1057 Gcc_backend::block(Bfunction* function, Bblock* enclosing,
1058                    const std::vector<Bvariable*>& vars,
1059                    Location start_location,
1060                    Location)
1061 {
1062   tree block_tree = make_node(BLOCK);
1063   if (enclosing == NULL)
1064     {
1065       // FIXME: Permitting FUNCTION to be NULL is a temporary measure
1066       // until we have a proper representation of the init function.
1067       tree fndecl;
1068       if (function == NULL)
1069         fndecl = current_function_decl;
1070       else
1071         fndecl = function->get_tree();
1072       gcc_assert(fndecl != NULL_TREE);
1073
1074       // We may have already created a block for local variables when
1075       // we take the address of a parameter.
1076       if (DECL_INITIAL(fndecl) == NULL_TREE)
1077         {
1078           BLOCK_SUPERCONTEXT(block_tree) = fndecl;
1079           DECL_INITIAL(fndecl) = block_tree;
1080         }
1081       else
1082         {
1083           tree superblock_tree = DECL_INITIAL(fndecl);
1084           BLOCK_SUPERCONTEXT(block_tree) = superblock_tree;
1085           tree* pp;
1086           for (pp = &BLOCK_SUBBLOCKS(superblock_tree);
1087                *pp != NULL_TREE;
1088                pp = &BLOCK_CHAIN(*pp))
1089             ;
1090           *pp = block_tree;
1091         }
1092     }
1093   else
1094     {
1095       tree superbind_tree = enclosing->get_tree();
1096       tree superblock_tree = BIND_EXPR_BLOCK(superbind_tree);
1097       gcc_assert(TREE_CODE(superblock_tree) == BLOCK);
1098
1099       BLOCK_SUPERCONTEXT(block_tree) = superblock_tree;
1100       tree* pp;
1101       for (pp = &BLOCK_SUBBLOCKS(superblock_tree);
1102            *pp != NULL_TREE;
1103            pp = &BLOCK_CHAIN(*pp))
1104         ;
1105       *pp = block_tree;
1106     }
1107
1108   tree* pp = &BLOCK_VARS(block_tree);
1109   for (std::vector<Bvariable*>::const_iterator pv = vars.begin();
1110        pv != vars.end();
1111        ++pv)
1112     {
1113       *pp = (*pv)->get_tree();
1114       if (*pp != error_mark_node)
1115         pp = &DECL_CHAIN(*pp);
1116     }
1117   *pp = NULL_TREE;
1118
1119   TREE_USED(block_tree) = 1;
1120
1121   tree bind_tree = build3_loc(start_location.gcc_location(), BIND_EXPR,
1122                               void_type_node, BLOCK_VARS(block_tree),
1123                               NULL_TREE, block_tree);
1124   TREE_SIDE_EFFECTS(bind_tree) = 1;
1125
1126   return new Bblock(bind_tree);
1127 }
1128
1129 // Add statements to a block.
1130
1131 void
1132 Gcc_backend::block_add_statements(Bblock* bblock,
1133                                   const std::vector<Bstatement*>& statements)
1134 {
1135   tree stmt_list = NULL_TREE;
1136   for (std::vector<Bstatement*>::const_iterator p = statements.begin();
1137        p != statements.end();
1138        ++p)
1139     {
1140       tree s = (*p)->get_tree();
1141       if (s != error_mark_node)
1142         append_to_statement_list(s, &stmt_list);
1143     }
1144
1145   tree bind_tree = bblock->get_tree();
1146   gcc_assert(TREE_CODE(bind_tree) == BIND_EXPR);
1147   BIND_EXPR_BODY(bind_tree) = stmt_list;
1148 }
1149
1150 // Return a block as a statement.
1151
1152 Bstatement*
1153 Gcc_backend::block_statement(Bblock* bblock)
1154 {
1155   tree bind_tree = bblock->get_tree();
1156   gcc_assert(TREE_CODE(bind_tree) == BIND_EXPR);
1157   return this->make_statement(bind_tree);
1158 }
1159
1160 // Make a global variable.
1161
1162 Bvariable*
1163 Gcc_backend::global_variable(const std::string& package_name,
1164                              const std::string& unique_prefix,
1165                              const std::string& name,
1166                              Btype* btype,
1167                              bool is_external,
1168                              bool is_hidden,
1169                              Location location)
1170 {
1171   tree type_tree = btype->get_tree();
1172   if (type_tree == error_mark_node)
1173     return this->error_variable();
1174
1175   std::string var_name(package_name);
1176   var_name.push_back('.');
1177   var_name.append(name);
1178   tree decl = build_decl(location.gcc_location(), VAR_DECL,
1179                          get_identifier_from_string(var_name),
1180                          type_tree);
1181   if (is_external)
1182     DECL_EXTERNAL(decl) = 1;
1183   else
1184     TREE_STATIC(decl) = 1;
1185   if (!is_hidden)
1186     {
1187       TREE_PUBLIC(decl) = 1;
1188
1189       std::string asm_name(unique_prefix);
1190       asm_name.push_back('.');
1191       asm_name.append(var_name);
1192       SET_DECL_ASSEMBLER_NAME(decl, get_identifier_from_string(asm_name));
1193     }
1194   TREE_USED(decl) = 1;
1195
1196   go_preserve_from_gc(decl);
1197
1198   return new Bvariable(decl);
1199 }
1200
1201 // Set the initial value of a global variable.
1202
1203 void
1204 Gcc_backend::global_variable_set_init(Bvariable* var, Bexpression* expr)
1205 {
1206   tree expr_tree = expr->get_tree();
1207   if (expr_tree == error_mark_node)
1208     return;
1209   gcc_assert(TREE_CONSTANT(expr_tree));
1210   tree var_decl = var->get_tree();
1211   if (var_decl == error_mark_node)
1212     return;
1213   DECL_INITIAL(var_decl) = expr_tree;
1214 }
1215
1216 // Make a local variable.
1217
1218 Bvariable*
1219 Gcc_backend::local_variable(Bfunction* function, const std::string& name,
1220                             Btype* btype, bool is_address_taken,
1221                             Location location)
1222 {
1223   tree type_tree = btype->get_tree();
1224   if (type_tree == error_mark_node)
1225     return this->error_variable();
1226   tree decl = build_decl(location.gcc_location(), VAR_DECL,
1227                          get_identifier_from_string(name),
1228                          type_tree);
1229   DECL_CONTEXT(decl) = function->get_tree();
1230   TREE_USED(decl) = 1;
1231   if (is_address_taken)
1232     TREE_ADDRESSABLE(decl) = 1;
1233   go_preserve_from_gc(decl);
1234   return new Bvariable(decl);
1235 }
1236
1237 // Make a function parameter variable.
1238
1239 Bvariable*
1240 Gcc_backend::parameter_variable(Bfunction* function, const std::string& name,
1241                                 Btype* btype, bool is_address_taken,
1242                                 Location location)
1243 {
1244   tree type_tree = btype->get_tree();
1245   if (type_tree == error_mark_node)
1246     return this->error_variable();
1247   tree decl = build_decl(location.gcc_location(), PARM_DECL,
1248                          get_identifier_from_string(name),
1249                          type_tree);
1250   DECL_CONTEXT(decl) = function->get_tree();
1251   DECL_ARG_TYPE(decl) = type_tree;
1252   TREE_USED(decl) = 1;
1253   if (is_address_taken)
1254     TREE_ADDRESSABLE(decl) = 1;
1255   go_preserve_from_gc(decl);
1256   return new Bvariable(decl);
1257 }
1258
1259 // Make a temporary variable.
1260
1261 Bvariable*
1262 Gcc_backend::temporary_variable(Bfunction* function, Bblock* bblock,
1263                                 Btype* btype, Bexpression* binit,
1264                                 bool is_address_taken,
1265                                 Location location,
1266                                 Bstatement** pstatement)
1267 {
1268   tree type_tree = btype->get_tree();
1269   tree init_tree = binit == NULL ? NULL_TREE : binit->get_tree();
1270   if (type_tree == error_mark_node || init_tree == error_mark_node)
1271     {
1272       *pstatement = this->error_statement();
1273       return this->error_variable();
1274     }
1275
1276   tree var;
1277   // We can only use create_tmp_var if the type is not addressable.
1278   if (!TREE_ADDRESSABLE(type_tree))
1279     var = create_tmp_var(type_tree, "GOTMP");
1280   else
1281     {
1282       gcc_assert(bblock != NULL);
1283       var = build_decl(location.gcc_location(), VAR_DECL,
1284                        create_tmp_var_name("GOTMP"),
1285                        type_tree);
1286       DECL_ARTIFICIAL(var) = 1;
1287       DECL_IGNORED_P(var) = 1;
1288       TREE_USED(var) = 1;
1289       // FIXME: Permitting function to be NULL here is a temporary
1290       // measure until we have a proper representation of the init
1291       // function.
1292       if (function != NULL)
1293         DECL_CONTEXT(var) = function->get_tree();
1294       else
1295         {
1296           gcc_assert(current_function_decl != NULL_TREE);
1297           DECL_CONTEXT(var) = current_function_decl;
1298         }
1299
1300       // We have to add this variable to the BLOCK and the BIND_EXPR.
1301       tree bind_tree = bblock->get_tree();
1302       gcc_assert(TREE_CODE(bind_tree) == BIND_EXPR);
1303       tree block_tree = BIND_EXPR_BLOCK(bind_tree);
1304       gcc_assert(TREE_CODE(block_tree) == BLOCK);
1305       DECL_CHAIN(var) = BLOCK_VARS(block_tree);
1306       BLOCK_VARS(block_tree) = var;
1307       BIND_EXPR_VARS(bind_tree) = BLOCK_VARS(block_tree);
1308     }
1309
1310   if (init_tree != NULL_TREE)
1311     DECL_INITIAL(var) = fold_convert_loc(location.gcc_location(), type_tree,
1312                                          init_tree);
1313
1314   if (is_address_taken)
1315     TREE_ADDRESSABLE(var) = 1;
1316
1317   *pstatement = this->make_statement(build1_loc(location.gcc_location(),
1318                                                 DECL_EXPR,
1319                                                 void_type_node, var));
1320   return new Bvariable(var);
1321 }
1322
1323 // Create a named immutable initialized data structure.
1324
1325 Bvariable*
1326 Gcc_backend::immutable_struct(const std::string& name, bool, Btype* btype,
1327                               Location location)
1328 {
1329   tree type_tree = btype->get_tree();
1330   if (type_tree == error_mark_node)
1331     return this->error_variable();
1332   gcc_assert(TREE_CODE(type_tree) == RECORD_TYPE);
1333   tree decl = build_decl(location.gcc_location(), VAR_DECL,
1334                          get_identifier_from_string(name),
1335                          build_qualified_type(type_tree, TYPE_QUAL_CONST));
1336   TREE_STATIC(decl) = 1;
1337   TREE_READONLY(decl) = 1;
1338   TREE_CONSTANT(decl) = 1;
1339   TREE_USED(decl) = 1;
1340   DECL_ARTIFICIAL(decl) = 1;
1341
1342   // We don't call rest_of_decl_compilation until we have the
1343   // initializer.
1344
1345   go_preserve_from_gc(decl);
1346   return new Bvariable(decl);
1347 }
1348
1349 // Set the initializer for a variable created by immutable_struct.
1350 // This is where we finish compiling the variable.
1351
1352 void
1353 Gcc_backend::immutable_struct_set_init(Bvariable* var, const std::string&,
1354                                        bool is_common, Btype*,
1355                                        Location,
1356                                        Bexpression* initializer)
1357 {
1358   tree decl = var->get_tree();
1359   tree init_tree = initializer->get_tree();
1360   if (decl == error_mark_node || init_tree == error_mark_node)
1361     return;
1362
1363   DECL_INITIAL(decl) = init_tree;
1364
1365   // We can't call make_decl_one_only until we set DECL_INITIAL.
1366   if (!is_common)
1367     TREE_PUBLIC(decl) = 1;
1368   else
1369     {
1370       make_decl_one_only(decl, DECL_ASSEMBLER_NAME(decl));
1371       resolve_unique_section(decl, 1, 0);
1372     }
1373
1374   rest_of_decl_compilation(decl, 1, 0);
1375 }
1376
1377 // Return a reference to an immutable initialized data structure
1378 // defined in another package.
1379
1380 Bvariable*
1381 Gcc_backend::immutable_struct_reference(const std::string& name, Btype* btype,
1382                                         Location location)
1383 {
1384   tree type_tree = btype->get_tree();
1385   if (type_tree == error_mark_node)
1386     return this->error_variable();
1387   gcc_assert(TREE_CODE(type_tree) == RECORD_TYPE);
1388   tree decl = build_decl(location.gcc_location(), VAR_DECL,
1389                          get_identifier_from_string(name),
1390                          build_qualified_type(type_tree, TYPE_QUAL_CONST));
1391   TREE_READONLY(decl) = 1;
1392   TREE_CONSTANT(decl) = 1;
1393   DECL_ARTIFICIAL(decl) = 1;
1394   TREE_PUBLIC(decl) = 1;
1395   DECL_EXTERNAL(decl) = 1;
1396   go_preserve_from_gc(decl);
1397   return new Bvariable(decl);
1398 }
1399
1400 // Make a label.
1401
1402 Blabel*
1403 Gcc_backend::label(Bfunction* function, const std::string& name,
1404                    Location location)
1405 {
1406   tree decl;
1407   if (name.empty())
1408     decl = create_artificial_label(location.gcc_location());
1409   else
1410     {
1411       tree id = get_identifier_from_string(name);
1412       decl = build_decl(location.gcc_location(), LABEL_DECL, id,
1413                         void_type_node);
1414       DECL_CONTEXT(decl) = function->get_tree();
1415     }
1416   return new Blabel(decl);
1417 }
1418
1419 // Make a statement which defines a label.
1420
1421 Bstatement*
1422 Gcc_backend::label_definition_statement(Blabel* label)
1423 {
1424   tree lab = label->get_tree();
1425   tree ret = fold_build1_loc(DECL_SOURCE_LOCATION(lab), LABEL_EXPR,
1426                              void_type_node, lab);
1427   return this->make_statement(ret);
1428 }
1429
1430 // Make a goto statement.
1431
1432 Bstatement*
1433 Gcc_backend::goto_statement(Blabel* label, Location location)
1434 {
1435   tree lab = label->get_tree();
1436   tree ret = fold_build1_loc(location.gcc_location(), GOTO_EXPR, void_type_node,
1437                              lab);
1438   return this->make_statement(ret);
1439 }
1440
1441 // Get the address of a label.
1442
1443 Bexpression*
1444 Gcc_backend::label_address(Blabel* label, Location location)
1445 {
1446   tree lab = label->get_tree();
1447   TREE_USED(lab) = 1;
1448   TREE_ADDRESSABLE(lab) = 1;
1449   tree ret = fold_convert_loc(location.gcc_location(), ptr_type_node,
1450                               build_fold_addr_expr_loc(location.gcc_location(),
1451                                                        lab));
1452   return this->make_expression(ret);
1453 }
1454
1455 // The single backend.
1456
1457 static Gcc_backend gcc_backend;
1458
1459 // Return the backend generator.
1460
1461 Backend*
1462 go_get_backend()
1463 {
1464   return &gcc_backend;
1465 }
1466
1467 // FIXME: Temporary functions while converting to the new backend
1468 // interface.
1469
1470 Btype*
1471 tree_to_type(tree t)
1472 {
1473   return new Btype(t);
1474 }
1475
1476 Bexpression*
1477 tree_to_expr(tree t)
1478 {
1479   return new Bexpression(t);
1480 }
1481
1482 Bstatement*
1483 tree_to_stat(tree t)
1484 {
1485   return new Bstatement(t);
1486 }
1487
1488 Bfunction*
1489 tree_to_function(tree t)
1490 {
1491   return new Bfunction(t);
1492 }
1493
1494 Bblock*
1495 tree_to_block(tree t)
1496 {
1497   gcc_assert(TREE_CODE(t) == BIND_EXPR);
1498   return new Bblock(t);
1499 }
1500
1501 tree
1502 type_to_tree(Btype* bt)
1503 {
1504   return bt->get_tree();
1505 }
1506
1507 tree
1508 expr_to_tree(Bexpression* be)
1509 {
1510   return be->get_tree();
1511 }
1512
1513 tree
1514 stat_to_tree(Bstatement* bs)
1515 {
1516   return bs->get_tree();
1517 }
1518
1519 tree
1520 block_to_tree(Bblock* bb)
1521 {
1522   return bb->get_tree();
1523 }
1524
1525 tree
1526 var_to_tree(Bvariable* bv)
1527 {
1528   return bv->get_tree();
1529 }