gcc/go/go-gcc.cc

   1 // go-gcc.cc -- Go frontend to gcc IR.
   2 // Copyright (C) 2011 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   // Expressions.
 199
 200   Bexpression*
 201   zero_expression(Btype*);
 202
 203   // Statements.
 204
 205   Bstatement*
 206   error_statement()
 207   { return this->make_statement(error_mark_node); }
 208
 209   Bstatement*
 210   expression_statement(Bexpression*);
 211
 212   Bstatement*
 213   init_statement(Bvariable* var, Bexpression* init);
 214
 215   Bstatement*
 216   assignment_statement(Bexpression* lhs, Bexpression* rhs, Location);
 217
 218   Bstatement*
 219   return_statement(Bfunction*, const std::vector<Bexpression*>&,
 220                    Location);
 221
 222   Bstatement*
 223   if_statement(Bexpression* condition, Bblock* then_block, Bblock* else_block,
 224                Location);
 225
 226   Bstatement*
 227   switch_statement(Bexpression* value,
 228                    const std::vector<std::vector<Bexpression*> >& cases,
 229                    const std::vector<Bstatement*>& statements,
 230                    Location);
 231
 232   Bstatement*
 233   compound_statement(Bstatement*, Bstatement*);
 234
 235   Bstatement*
 236   statement_list(const std::vector<Bstatement*>&);
 237
 238   // Blocks.
 239
 240   Bblock*
 241   block(Bfunction*, Bblock*, const std::vector<Bvariable*>&,
 242         Location, Location);
 243
 244   void
 245   block_add_statements(Bblock*, const std::vector<Bstatement*>&);
 246
 247   Bstatement*
 248   block_statement(Bblock*);
 249
 250   // Variables.
 251
 252   Bvariable*
 253   error_variable()
 254   { return new Bvariable(error_mark_node); }
 255
 256   Bvariable*
 257   global_variable(const std::string& package_name,
 258                   const std::string& unique_prefix,
 259                   const std::string& name,
 260                   Btype* btype,
 261                   bool is_external,
 262                   bool is_hidden,
 263                   Location location);
 264
 265   void
 266   global_variable_set_init(Bvariable*, Bexpression*);
 267
 268   Bvariable*
 269   local_variable(Bfunction*, const std::string&, Btype*, bool,
 270                  Location);
 271
 272   Bvariable*
 273   parameter_variable(Bfunction*, const std::string&, Btype*, bool,
 274                      Location);
 275
 276   Bvariable*
 277   temporary_variable(Bfunction*, Bblock*, Btype*, Bexpression*, bool,
 278                      Location, Bstatement**);
 279
 280   Bvariable*
 281   immutable_struct(const std::string&, bool, Btype*, Location);
 282
 283   void
 284   immutable_struct_set_init(Bvariable*, const std::string&, bool, Btype*,
 285                             Location, Bexpression*);
 286
 287   Bvariable*
 288   immutable_struct_reference(const std::string&, Btype*, Location);
 289
 290   // Labels.
 291
 292   Blabel*
 293   label(Bfunction*, const std::string& name, Location);
 294
 295   Bstatement*
 296   label_definition_statement(Blabel*);
 297
 298   Bstatement*
 299   goto_statement(Blabel*, Location);
 300
 301   Bexpression*
 302   label_address(Blabel*, Location);
 303
 304  private:
 305   // Make a Bexpression from a tree.
 306   Bexpression*
 307   make_expression(tree t)
 308   { return new Bexpression(t); }
 309
 310   // Make a Bstatement from a tree.
 311   Bstatement*
 312   make_statement(tree t)
 313   { return new Bstatement(t); }
 314
 315   // Make a Btype from a tree.
 316   Btype*
 317   make_type(tree t)
 318   { return new Btype(t); }
 319
 320   Btype*
 321   fill_in_struct(Btype*, const std::vector<Btyped_identifier>&);
 322
 323   Btype*
 324   fill_in_array(Btype*, Btype*, Bexpression*);
 325 };
 326
 327 // A helper function.
 328
 329 static inline tree
 330 get_identifier_from_string(const std::string& str)
 331 {
 332   return get_identifier_with_length(str.data(), str.length());
 333 }
 334
 335 // Get an unnamed integer type.
 336
 337 Btype*
 338 Gcc_backend::integer_type(bool is_unsigned, int bits)
 339 {
 340   tree type;
 341   if (is_unsigned)
 342     {
 343       if (bits == INT_TYPE_SIZE)
 344         type = unsigned_type_node;
 345       else if (bits == CHAR_TYPE_SIZE)
 346         type = unsigned_char_type_node;
 347       else if (bits == SHORT_TYPE_SIZE)
 348         type = short_unsigned_type_node;
 349       else if (bits == LONG_TYPE_SIZE)
 350         type = long_unsigned_type_node;
 351       else if (bits == LONG_LONG_TYPE_SIZE)
 352         type = long_long_unsigned_type_node;
 353       else
 354         type = make_unsigned_type(bits);
 355     }
 356   else
 357     {
 358       if (bits == INT_TYPE_SIZE)
 359         type = integer_type_node;
 360       else if (bits == CHAR_TYPE_SIZE)
 361         type = signed_char_type_node;
 362       else if (bits == SHORT_TYPE_SIZE)
 363         type = short_integer_type_node;
 364       else if (bits == LONG_TYPE_SIZE)
 365         type = long_integer_type_node;
 366       else if (bits == LONG_LONG_TYPE_SIZE)
 367         type = long_long_integer_type_node;
 368       else
 369         type = make_signed_type(bits);
 370     }
 371   return this->make_type(type);
 372 }
 373
 374 // Get an unnamed float type.
 375
 376 Btype*
 377 Gcc_backend::float_type(int bits)
 378 {
 379   tree type;
 380   if (bits == FLOAT_TYPE_SIZE)
 381     type = float_type_node;
 382   else if (bits == DOUBLE_TYPE_SIZE)
 383     type = double_type_node;
 384   else if (bits == LONG_DOUBLE_TYPE_SIZE)
 385     type = long_double_type_node;
 386   else
 387     {
 388       type = make_node(REAL_TYPE);
 389       TYPE_PRECISION(type) = bits;
 390       layout_type(type);
 391     }
 392   return this->make_type(type);
 393 }
 394
 395 // Get an unnamed complex type.
 396
 397 Btype*
 398 Gcc_backend::complex_type(int bits)
 399 {
 400   tree type;
 401   if (bits == FLOAT_TYPE_SIZE * 2)
 402     type = complex_float_type_node;
 403   else if (bits == DOUBLE_TYPE_SIZE * 2)
 404     type = complex_double_type_node;
 405   else if (bits == LONG_DOUBLE_TYPE_SIZE * 2)
 406     type = complex_long_double_type_node;
 407   else
 408     {
 409       type = make_node(REAL_TYPE);
 410       TYPE_PRECISION(type) = bits / 2;
 411       layout_type(type);
 412       type = build_complex_type(type);
 413     }
 414   return this->make_type(type);
 415 }
 416
 417 // Get a pointer type.
 418
 419 Btype*
 420 Gcc_backend::pointer_type(Btype* to_type)
 421 {
 422   tree to_type_tree = to_type->get_tree();
 423   if (to_type_tree == error_mark_node)
 424     return this->error_type();
 425   tree type = build_pointer_type(to_type_tree);
 426   return this->make_type(type);
 427 }
 428
 429 // Make a function type.
 430
 431 Btype*
 432 Gcc_backend::function_type(const Btyped_identifier& receiver,
 433                            const std::vector<Btyped_identifier>& parameters,
 434                            const std::vector<Btyped_identifier>& results,
 435                            Location location)
 436 {
 437   tree args = NULL_TREE;
 438   tree* pp = &args;
 439   if (receiver.btype != NULL)
 440     {
 441       tree t = receiver.btype->get_tree();
 442       if (t == error_mark_node)
 443         return this->error_type();
 444       *pp = tree_cons(NULL_TREE, t, NULL_TREE);
 445       pp = &TREE_CHAIN(*pp);
 446     }
 447
 448   for (std::vector<Btyped_identifier>::const_iterator p = parameters.begin();
 449        p != parameters.end();
 450        ++p)
 451     {
 452       tree t = p->btype->get_tree();
 453       if (t == error_mark_node)
 454         return this->error_type();
 455       *pp = tree_cons(NULL_TREE, t, NULL_TREE);
 456       pp = &TREE_CHAIN(*pp);
 457     }
 458
 459   // Varargs is handled entirely at the Go level.  When converted to
 460   // GENERIC functions are not varargs.
 461   *pp = void_list_node;
 462
 463   tree result;
 464   if (results.empty())
 465     result = void_type_node;
 466   else if (results.size() == 1)
 467     result = results.front().btype->get_tree();
 468   else
 469     {
 470       result = make_node(RECORD_TYPE);
 471       tree field_trees = NULL_TREE;
 472       pp = &field_trees;
 473       for (std::vector<Btyped_identifier>::const_iterator p = results.begin();
 474            p != results.end();
 475            ++p)
 476         {
 477           const std::string name = (p->name.empty()
 478                                     ? "UNNAMED"
 479                                     : p->name);
 480           tree name_tree = get_identifier_from_string(name);
 481           tree field_type_tree = p->btype->get_tree();
 482           if (field_type_tree == error_mark_node)
 483             return this->error_type();
 484           gcc_assert(TYPE_SIZE(field_type_tree) != NULL_TREE);
 485           tree field = build_decl(location.gcc_location(), FIELD_DECL,
 486                                   name_tree, field_type_tree);
 487           DECL_CONTEXT(field) = result;
 488           *pp = field;
 489           pp = &DECL_CHAIN(field);
 490         }
 491       TYPE_FIELDS(result) = field_trees;
 492       layout_type(result);
 493     }
 494   if (result == error_mark_node)
 495     return this->error_type();
 496
 497   tree fntype = build_function_type(result, args);
 498   if (fntype == error_mark_node)
 499     return this->error_type();
 500
 501   return this->make_type(build_pointer_type(fntype));
 502 }
 503
 504 // Make a struct type.
 505
 506 Btype*
 507 Gcc_backend::struct_type(const std::vector<Btyped_identifier>& fields)
 508 {
 509   return this->fill_in_struct(this->make_type(make_node(RECORD_TYPE)), fields);
 510 }
 511
 512 // Fill in the fields of a struct type.
 513
 514 Btype*
 515 Gcc_backend::fill_in_struct(Btype* fill,
 516                             const std::vector<Btyped_identifier>& fields)
 517 {
 518   tree fill_tree = fill->get_tree();
 519   tree field_trees = NULL_TREE;
 520   tree* pp = &field_trees;
 521   for (std::vector<Btyped_identifier>::const_iterator p = fields.begin();
 522        p != fields.end();
 523        ++p)
 524     {
 525       tree name_tree = get_identifier_from_string(p->name);
 526       tree type_tree = p->btype->get_tree();
 527       if (type_tree == error_mark_node)
 528         return this->error_type();
 529       tree field = build_decl(p->location.gcc_location(), FIELD_DECL, name_tree,
 530                               type_tree);
 531       DECL_CONTEXT(field) = fill_tree;
 532       *pp = field;
 533       pp = &DECL_CHAIN(field);
 534     }
 535   TYPE_FIELDS(fill_tree) = field_trees;
 536   layout_type(fill_tree);
 537   return fill;
 538 }
 539
 540 // Make an array type.
 541
 542 Btype*
 543 Gcc_backend::array_type(Btype* element_btype, Bexpression* length)
 544 {
 545   return this->fill_in_array(this->make_type(make_node(ARRAY_TYPE)),
 546                              element_btype, length);
 547 }
 548
 549 // Fill in an array type.
 550
 551 Btype*
 552 Gcc_backend::fill_in_array(Btype* fill, Btype* element_type,
 553                            Bexpression* length)
 554 {
 555   tree element_type_tree = element_type->get_tree();
 556   tree length_tree = length->get_tree();
 557   if (element_type_tree == error_mark_node || length_tree == error_mark_node)
 558     return this->error_type();
 559
 560   gcc_assert(TYPE_SIZE(element_type_tree) != NULL_TREE);
 561
 562   length_tree = fold_convert(sizetype, length_tree);
 563
 564   // build_index_type takes the maximum index, which is one less than
 565   // the length.
 566   tree index_type_tree = build_index_type(fold_build2(MINUS_EXPR, sizetype,
 567                                                       length_tree,
 568                                                       size_one_node));
 569
 570   tree fill_tree = fill->get_tree();
 571   TREE_TYPE(fill_tree) = element_type_tree;
 572   TYPE_DOMAIN(fill_tree) = index_type_tree;
 573   TYPE_ADDR_SPACE(fill_tree) = TYPE_ADDR_SPACE(element_type_tree);
 574   layout_type(fill_tree);
 575
 576   if (TYPE_STRUCTURAL_EQUALITY_P(element_type_tree))
 577     SET_TYPE_STRUCTURAL_EQUALITY(fill_tree);
 578   else if (TYPE_CANONICAL(element_type_tree) != element_type_tree
 579            || TYPE_CANONICAL(index_type_tree) != index_type_tree)
 580     TYPE_CANONICAL(fill_tree) =
 581       build_array_type(TYPE_CANONICAL(element_type_tree),
 582                        TYPE_CANONICAL(index_type_tree));
 583
 584   return fill;
 585 }
 586
 587 // Create a placeholder for a pointer type.
 588
 589 Btype*
 590 Gcc_backend::placeholder_pointer_type(const std::string& name,
 591                                       Location location, bool)
 592 {
 593   tree ret = build_variant_type_copy(ptr_type_node);
 594   if (!name.empty())
 595     {
 596       tree decl = build_decl(location.gcc_location(), TYPE_DECL,
 597                              get_identifier_from_string(name),
 598                              ret);
 599       TYPE_NAME(ret) = decl;
 600     }
 601   return this->make_type(ret);
 602 }
 603
 604 // Set the real target type for a placeholder pointer type.
 605
 606 bool
 607 Gcc_backend::set_placeholder_pointer_type(Btype* placeholder,
 608                                           Btype* to_type)
 609 {
 610   tree pt = placeholder->get_tree();
 611   if (pt == error_mark_node)
 612     return false;
 613   gcc_assert(TREE_CODE(pt) == POINTER_TYPE);
 614   tree tt = to_type->get_tree();
 615   if (tt == error_mark_node)
 616     {
 617       TREE_TYPE(pt) = tt;
 618       return false;
 619     }
 620   gcc_assert(TREE_CODE(tt) == POINTER_TYPE);
 621   TREE_TYPE(pt) = TREE_TYPE(tt);
 622   return true;
 623 }
 624
 625 // Set the real values for a placeholder function type.
 626
 627 bool
 628 Gcc_backend::set_placeholder_function_type(Btype* placeholder, Btype* ft)
 629 {
 630   return this->set_placeholder_pointer_type(placeholder, ft);
 631 }
 632
 633 // Create a placeholder for a struct type.
 634
 635 Btype*
 636 Gcc_backend::placeholder_struct_type(const std::string& name,
 637                                      Location location)
 638 {
 639   tree ret = make_node(RECORD_TYPE);
 640   tree decl = build_decl(location.gcc_location(), TYPE_DECL,
 641                          get_identifier_from_string(name),
 642                          ret);
 643   TYPE_NAME(ret) = decl;
 644   return this->make_type(ret);
 645 }
 646
 647 // Fill in the fields of a placeholder struct type.
 648
 649 bool
 650 Gcc_backend::set_placeholder_struct_type(
 651     Btype* placeholder,
 652     const std::vector<Btyped_identifier>& fields)
 653 {
 654   tree t = placeholder->get_tree();
 655   gcc_assert(TREE_CODE(t) == RECORD_TYPE && TYPE_FIELDS(t) == NULL_TREE);
 656   Btype* r = this->fill_in_struct(placeholder, fields);
 657   return r->get_tree() != error_mark_node;
 658 }
 659
 660 // Create a placeholder for an array type.
 661
 662 Btype*
 663 Gcc_backend::placeholder_array_type(const std::string& name,
 664                                     Location location)
 665 {
 666   tree ret = make_node(ARRAY_TYPE);
 667   tree decl = build_decl(location.gcc_location(), TYPE_DECL,
 668                          get_identifier_from_string(name),
 669                          ret);
 670   TYPE_NAME(ret) = decl;
 671   return this->make_type(ret);
 672 }
 673
 674 // Fill in the fields of a placeholder array type.
 675
 676 bool
 677 Gcc_backend::set_placeholder_array_type(Btype* placeholder,
 678                                         Btype* element_btype,
 679                                         Bexpression* length)
 680 {
 681   tree t = placeholder->get_tree();
 682   gcc_assert(TREE_CODE(t) == ARRAY_TYPE && TREE_TYPE(t) == NULL_TREE);
 683   Btype* r = this->fill_in_array(placeholder, element_btype, length);
 684   return r->get_tree() != error_mark_node;
 685 }
 686
 687 // Return a named version of a type.
 688
 689 Btype*
 690 Gcc_backend::named_type(const std::string& name, Btype* btype,
 691                         Location location)
 692 {
 693   tree type = btype->get_tree();
 694   if (type == error_mark_node)
 695     return this->error_type();
 696   type = build_variant_type_copy(type);
 697   tree decl = build_decl(location.gcc_location(), TYPE_DECL,
 698                          get_identifier_from_string(name),
 699                          type);
 700   TYPE_NAME(type) = decl;
 701   return this->make_type(type);
 702 }
 703
 704 // Return a pointer type used as a marker for a circular type.
 705
 706 Btype*
 707 Gcc_backend::circular_pointer_type(Btype*, bool)
 708 {
 709   return this->make_type(ptr_type_node);
 710 }
 711
 712 // Return whether we might be looking at a circular type.
 713
 714 bool
 715 Gcc_backend::is_circular_pointer_type(Btype* btype)
 716 {
 717   return btype->get_tree() == ptr_type_node;
 718 }
 719
 720 // Return the zero value for a type.
 721
 722 Bexpression*
 723 Gcc_backend::zero_expression(Btype* btype)
 724 {
 725   tree t = btype->get_tree();
 726   tree ret;
 727   if (t == error_mark_node)
 728     ret = error_mark_node;
 729   else
 730     ret = build_zero_cst(t);
 731   return tree_to_expr(ret);
 732 }
 733
 734 // An expression as a statement.
 735
 736 Bstatement*
 737 Gcc_backend::expression_statement(Bexpression* expr)
 738 {
 739   return this->make_statement(expr->get_tree());
 740 }
 741
 742 // Variable initialization.
 743
 744 Bstatement*
 745 Gcc_backend::init_statement(Bvariable* var, Bexpression* init)
 746 {
 747   tree var_tree = var->get_tree();
 748   tree init_tree = init->get_tree();
 749   if (var_tree == error_mark_node || init_tree == error_mark_node)
 750     return this->error_statement();
 751   gcc_assert(TREE_CODE(var_tree) == VAR_DECL);
 752   DECL_INITIAL(var_tree) = init_tree;
 753   return this->make_statement(build1_loc(DECL_SOURCE_LOCATION(var_tree),
 754                                          DECL_EXPR, void_type_node, var_tree));
 755 }
 756
 757 // Assignment.
 758
 759 Bstatement*
 760 Gcc_backend::assignment_statement(Bexpression* lhs, Bexpression* rhs,
 761                                   Location location)
 762 {
 763   tree lhs_tree = lhs->get_tree();
 764   tree rhs_tree = rhs->get_tree();
 765   if (lhs_tree == error_mark_node || rhs_tree == error_mark_node)
 766     return this->error_statement();
 767   return this->make_statement(fold_build2_loc(location.gcc_location(),
 768                                               MODIFY_EXPR,
 769                                               void_type_node,
 770                                               lhs_tree, rhs_tree));
 771 }
 772
 773 // Return.
 774
 775 Bstatement*
 776 Gcc_backend::return_statement(Bfunction* bfunction,
 777                               const std::vector<Bexpression*>& vals,
 778                               Location location)
 779 {
 780   tree fntree = bfunction->get_tree();
 781   if (fntree == error_mark_node)
 782     return this->error_statement();
 783   tree result = DECL_RESULT(fntree);
 784   if (result == error_mark_node)
 785     return this->error_statement();
 786   tree ret;
 787   if (vals.empty())
 788     ret = fold_build1_loc(location.gcc_location(), RETURN_EXPR, void_type_node,
 789                           NULL_TREE);
 790   else if (vals.size() == 1)
 791     {
 792       tree val = vals.front()->get_tree();
 793       if (val == error_mark_node)
 794         return this->error_statement();
 795       tree set = fold_build2_loc(location.gcc_location(), MODIFY_EXPR,
 796                                  void_type_node, result,
 797                                  vals.front()->get_tree());
 798       ret = fold_build1_loc(location.gcc_location(), RETURN_EXPR,
 799                             void_type_node, set);
 800     }
 801   else
 802     {
 803       // To return multiple values, copy the values into a temporary
 804       // variable of the right structure type, and then assign the
 805       // temporary variable to the DECL_RESULT in the return
 806       // statement.
 807       tree stmt_list = NULL_TREE;
 808       tree rettype = TREE_TYPE(result);
 809       tree rettmp = create_tmp_var(rettype, "RESULT");
 810       tree field = TYPE_FIELDS(rettype);
 811       for (std::vector<Bexpression*>::const_iterator p = vals.begin();
 812            p != vals.end();
 813            p++, field = DECL_CHAIN(field))
 814         {
 815           gcc_assert(field != NULL_TREE);
 816           tree ref = fold_build3_loc(location.gcc_location(), COMPONENT_REF,
 817                                      TREE_TYPE(field), rettmp, field,
 818                                      NULL_TREE);
 819           tree val = (*p)->get_tree();
 820           if (val == error_mark_node)
 821             return this->error_statement();
 822           tree set = fold_build2_loc(location.gcc_location(), MODIFY_EXPR,
 823                                      void_type_node,
 824                                      ref, (*p)->get_tree());
 825           append_to_statement_list(set, &stmt_list);
 826         }
 827       gcc_assert(field == NULL_TREE);
 828       tree set = fold_build2_loc(location.gcc_location(), MODIFY_EXPR,
 829                                  void_type_node,
 830                                  result, rettmp);
 831       tree ret_expr = fold_build1_loc(location.gcc_location(), RETURN_EXPR,
 832                                       void_type_node, set);
 833       append_to_statement_list(ret_expr, &stmt_list);
 834       ret = stmt_list;
 835     }
 836   return this->make_statement(ret);
 837 }
 838
 839 // If.
 840
 841 Bstatement*
 842 Gcc_backend::if_statement(Bexpression* condition, Bblock* then_block,
 843                           Bblock* else_block, Location location)
 844 {
 845   tree cond_tree = condition->get_tree();
 846   tree then_tree = then_block->get_tree();
 847   tree else_tree = else_block == NULL ? NULL_TREE : else_block->get_tree();
 848   if (cond_tree == error_mark_node
 849       || then_tree == error_mark_node
 850       || else_tree == error_mark_node)
 851     return this->error_statement();
 852   tree ret = build3_loc(location.gcc_location(), COND_EXPR, void_type_node,
 853                         cond_tree, then_tree, else_tree);
 854   return this->make_statement(ret);
 855 }
 856
 857 // Switch.
 858
 859 Bstatement*
 860 Gcc_backend::switch_statement(
 861     Bexpression* value,
 862     const std::vector<std::vector<Bexpression*> >& cases,
 863     const std::vector<Bstatement*>& statements,
 864     Location switch_location)
 865 {
 866   gcc_assert(cases.size() == statements.size());
 867
 868   tree stmt_list = NULL_TREE;
 869   std::vector<std::vector<Bexpression*> >::const_iterator pc = cases.begin();
 870   for (std::vector<Bstatement*>::const_iterator ps = statements.begin();
 871        ps != statements.end();
 872        ++ps, ++pc)
 873     {
 874       if (pc->empty())
 875         {
 876           source_location loc = (*ps != NULL
 877                                  ? EXPR_LOCATION((*ps)->get_tree())
 878                                  : UNKNOWN_LOCATION);
 879           tree label = create_artificial_label(loc);
 880           tree c = build_case_label(NULL_TREE, NULL_TREE, label);
 881           append_to_statement_list(c, &stmt_list);
 882         }
 883       else
 884         {
 885           for (std::vector<Bexpression*>::const_iterator pcv = pc->begin();
 886                pcv != pc->end();
 887                ++pcv)
 888             {
 889               tree t = (*pcv)->get_tree();
 890               if (t == error_mark_node)
 891                 return this->error_statement();
 892               source_location loc = EXPR_LOCATION(t);
 893               tree label = create_artificial_label(loc);
 894               tree c = build_case_label((*pcv)->get_tree(), NULL_TREE, label);
 895               append_to_statement_list(c, &stmt_list);
 896             }
 897         }
 898
 899       if (*ps != NULL)
 900         {
 901           tree t = (*ps)->get_tree();
 902           if (t == error_mark_node)
 903             return this->error_statement();
 904           append_to_statement_list(t, &stmt_list);
 905         }
 906     }
 907
 908   tree tv = value->get_tree();
 909   if (tv == error_mark_node)
 910     return this->error_statement();
 911   tree t = build3_loc(switch_location.gcc_location(), SWITCH_EXPR,
 912                       void_type_node, tv, stmt_list, NULL_TREE);
 913   return this->make_statement(t);
 914 }
 915
 916 // Pair of statements.
 917
 918 Bstatement*
 919 Gcc_backend::compound_statement(Bstatement* s1, Bstatement* s2)
 920 {
 921   tree stmt_list = NULL_TREE;
 922   tree t = s1->get_tree();
 923   if (t == error_mark_node)
 924     return this->error_statement();
 925   append_to_statement_list(t, &stmt_list);
 926   t = s2->get_tree();
 927   if (t == error_mark_node)
 928     return this->error_statement();
 929   append_to_statement_list(t, &stmt_list);
 930   return this->make_statement(stmt_list);
 931 }
 932
 933 // List of statements.
 934
 935 Bstatement*
 936 Gcc_backend::statement_list(const std::vector<Bstatement*>& statements)
 937 {
 938   tree stmt_list = NULL_TREE;
 939   for (std::vector<Bstatement*>::const_iterator p = statements.begin();
 940        p != statements.end();
 941        ++p)
 942     {
 943       tree t = (*p)->get_tree();
 944       if (t == error_mark_node)
 945         return this->error_statement();
 946       append_to_statement_list(t, &stmt_list);
 947     }
 948   return this->make_statement(stmt_list);
 949 }
 950
 951 // Make a block.  For some reason gcc uses a dual structure for
 952 // blocks: BLOCK tree nodes and BIND_EXPR tree nodes.  Since the
 953 // BIND_EXPR node points to the BLOCK node, we store the BIND_EXPR in
 954 // the Bblock.
 955
 956 Bblock*
 957 Gcc_backend::block(Bfunction* function, Bblock* enclosing,
 958                    const std::vector<Bvariable*>& vars,
 959                    Location start_location,
 960                    Location)
 961 {
 962   tree block_tree = make_node(BLOCK);
 963   if (enclosing == NULL)
 964     {
 965       // FIXME: Permitting FUNCTION to be NULL is a temporary measure
 966       // until we have a proper representation of the init function.
 967       tree fndecl;
 968       if (function == NULL)
 969         fndecl = current_function_decl;
 970       else
 971         fndecl = function->get_tree();
 972       gcc_assert(fndecl != NULL_TREE);
 973
 974       // We may have already created a block for local variables when
 975       // we take the address of a parameter.
 976       if (DECL_INITIAL(fndecl) == NULL_TREE)
 977         {
 978           BLOCK_SUPERCONTEXT(block_tree) = fndecl;
 979           DECL_INITIAL(fndecl) = block_tree;
 980         }
 981       else
 982         {
 983           tree superblock_tree = DECL_INITIAL(fndecl);
 984           BLOCK_SUPERCONTEXT(block_tree) = superblock_tree;
 985           tree* pp;
 986           for (pp = &BLOCK_SUBBLOCKS(superblock_tree);
 987                *pp != NULL_TREE;
 988                pp = &BLOCK_CHAIN(*pp))
 989             ;
 990           *pp = block_tree;
 991         }
 992     }
 993   else
 994     {
 995       tree superbind_tree = enclosing->get_tree();
 996       tree superblock_tree = BIND_EXPR_BLOCK(superbind_tree);
 997       gcc_assert(TREE_CODE(superblock_tree) == BLOCK);
 998
 999       BLOCK_SUPERCONTEXT(block_tree) = superblock_tree;
1000       tree* pp;
1001       for (pp = &BLOCK_SUBBLOCKS(superblock_tree);
1002            *pp != NULL_TREE;
1003            pp = &BLOCK_CHAIN(*pp))
1004         ;
1005       *pp = block_tree;
1006     }
1007
1008   tree* pp = &BLOCK_VARS(block_tree);
1009   for (std::vector<Bvariable*>::const_iterator pv = vars.begin();
1010        pv != vars.end();
1011        ++pv)
1012     {
1013       *pp = (*pv)->get_tree();
1014       if (*pp != error_mark_node)
1015         pp = &DECL_CHAIN(*pp);
1016     }
1017   *pp = NULL_TREE;
1018
1019   TREE_USED(block_tree) = 1;
1020
1021   tree bind_tree = build3_loc(start_location.gcc_location(), BIND_EXPR,
1022                               void_type_node, BLOCK_VARS(block_tree),
1023                               NULL_TREE, block_tree);
1024   TREE_SIDE_EFFECTS(bind_tree) = 1;
1025
1026   return new Bblock(bind_tree);
1027 }
1028
1029 // Add statements to a block.
1030
1031 void
1032 Gcc_backend::block_add_statements(Bblock* bblock,
1033                                   const std::vector<Bstatement*>& statements)
1034 {
1035   tree stmt_list = NULL_TREE;
1036   for (std::vector<Bstatement*>::const_iterator p = statements.begin();
1037        p != statements.end();
1038        ++p)
1039     {
1040       tree s = (*p)->get_tree();
1041       if (s != error_mark_node)
1042         append_to_statement_list(s, &stmt_list);
1043     }
1044
1045   tree bind_tree = bblock->get_tree();
1046   gcc_assert(TREE_CODE(bind_tree) == BIND_EXPR);
1047   BIND_EXPR_BODY(bind_tree) = stmt_list;
1048 }
1049
1050 // Return a block as a statement.
1051
1052 Bstatement*
1053 Gcc_backend::block_statement(Bblock* bblock)
1054 {
1055   tree bind_tree = bblock->get_tree();
1056   gcc_assert(TREE_CODE(bind_tree) == BIND_EXPR);
1057   return this->make_statement(bind_tree);
1058 }
1059
1060 // Make a global variable.
1061
1062 Bvariable*
1063 Gcc_backend::global_variable(const std::string& package_name,
1064                              const std::string& unique_prefix,
1065                              const std::string& name,
1066                              Btype* btype,
1067                              bool is_external,
1068                              bool is_hidden,
1069                              Location location)
1070 {
1071   tree type_tree = btype->get_tree();
1072   if (type_tree == error_mark_node)
1073     return this->error_variable();
1074
1075   std::string var_name(package_name);
1076   var_name.push_back('.');
1077   var_name.append(name);
1078   tree decl = build_decl(location.gcc_location(), VAR_DECL,
1079                          get_identifier_from_string(var_name),
1080                          type_tree);
1081   if (is_external)
1082     DECL_EXTERNAL(decl) = 1;
1083   else
1084     TREE_STATIC(decl) = 1;
1085   if (!is_hidden)
1086     {
1087       TREE_PUBLIC(decl) = 1;
1088
1089       std::string asm_name(unique_prefix);
1090       asm_name.push_back('.');
1091       asm_name.append(var_name);
1092       SET_DECL_ASSEMBLER_NAME(decl, get_identifier_from_string(asm_name));
1093     }
1094   TREE_USED(decl) = 1;
1095
1096   go_preserve_from_gc(decl);
1097
1098   return new Bvariable(decl);
1099 }
1100
1101 // Set the initial value of a global variable.
1102
1103 void
1104 Gcc_backend::global_variable_set_init(Bvariable* var, Bexpression* expr)
1105 {
1106   tree expr_tree = expr->get_tree();
1107   if (expr_tree == error_mark_node)
1108     return;
1109   gcc_assert(TREE_CONSTANT(expr_tree));
1110   tree var_decl = var->get_tree();
1111   if (var_decl == error_mark_node)
1112     return;
1113   DECL_INITIAL(var_decl) = expr_tree;
1114 }
1115
1116 // Make a local variable.
1117
1118 Bvariable*
1119 Gcc_backend::local_variable(Bfunction* function, const std::string& name,
1120                             Btype* btype, bool is_address_taken,
1121                             Location location)
1122 {
1123   tree type_tree = btype->get_tree();
1124   if (type_tree == error_mark_node)
1125     return this->error_variable();
1126   tree decl = build_decl(location.gcc_location(), VAR_DECL,
1127                          get_identifier_from_string(name),
1128                          type_tree);
1129   DECL_CONTEXT(decl) = function->get_tree();
1130   TREE_USED(decl) = 1;
1131   if (is_address_taken)
1132     TREE_ADDRESSABLE(decl) = 1;
1133   go_preserve_from_gc(decl);
1134   return new Bvariable(decl);
1135 }
1136
1137 // Make a function parameter variable.
1138
1139 Bvariable*
1140 Gcc_backend::parameter_variable(Bfunction* function, const std::string& name,
1141                                 Btype* btype, bool is_address_taken,
1142                                 Location location)
1143 {
1144   tree type_tree = btype->get_tree();
1145   if (type_tree == error_mark_node)
1146     return this->error_variable();
1147   tree decl = build_decl(location.gcc_location(), PARM_DECL,
1148                          get_identifier_from_string(name),
1149                          type_tree);
1150   DECL_CONTEXT(decl) = function->get_tree();
1151   DECL_ARG_TYPE(decl) = type_tree;
1152   TREE_USED(decl) = 1;
1153   if (is_address_taken)
1154     TREE_ADDRESSABLE(decl) = 1;
1155   go_preserve_from_gc(decl);
1156   return new Bvariable(decl);
1157 }
1158
1159 // Make a temporary variable.
1160
1161 Bvariable*
1162 Gcc_backend::temporary_variable(Bfunction* function, Bblock* bblock,
1163                                 Btype* btype, Bexpression* binit,
1164                                 bool is_address_taken,
1165                                 Location location,
1166                                 Bstatement** pstatement)
1167 {
1168   tree type_tree = btype->get_tree();
1169   tree init_tree = binit == NULL ? NULL_TREE : binit->get_tree();
1170   if (type_tree == error_mark_node || init_tree == error_mark_node)
1171     {
1172       *pstatement = this->error_statement();
1173       return this->error_variable();
1174     }
1175
1176   tree var;
1177   // We can only use create_tmp_var if the type is not addressable.
1178   if (!TREE_ADDRESSABLE(type_tree))
1179     var = create_tmp_var(type_tree, "GOTMP");
1180   else
1181     {
1182       gcc_assert(bblock != NULL);
1183       var = build_decl(location.gcc_location(), VAR_DECL,
1184                        create_tmp_var_name("GOTMP"),
1185                        type_tree);
1186       DECL_ARTIFICIAL(var) = 1;
1187       DECL_IGNORED_P(var) = 1;
1188       TREE_USED(var) = 1;
1189       // FIXME: Permitting function to be NULL here is a temporary
1190       // measure until we have a proper representation of the init
1191       // function.
1192       if (function != NULL)
1193         DECL_CONTEXT(var) = function->get_tree();
1194       else
1195         {
1196           gcc_assert(current_function_decl != NULL_TREE);
1197           DECL_CONTEXT(var) = current_function_decl;
1198         }
1199
1200       // We have to add this variable to the BLOCK and the BIND_EXPR.
1201       tree bind_tree = bblock->get_tree();
1202       gcc_assert(TREE_CODE(bind_tree) == BIND_EXPR);
1203       tree block_tree = BIND_EXPR_BLOCK(bind_tree);
1204       gcc_assert(TREE_CODE(block_tree) == BLOCK);
1205       DECL_CHAIN(var) = BLOCK_VARS(block_tree);
1206       BLOCK_VARS(block_tree) = var;
1207       BIND_EXPR_VARS(bind_tree) = BLOCK_VARS(block_tree);
1208     }
1209
1210   if (init_tree != NULL_TREE)
1211     DECL_INITIAL(var) = fold_convert_loc(location.gcc_location(), type_tree,
1212                                          init_tree);
1213
1214   if (is_address_taken)
1215     TREE_ADDRESSABLE(var) = 1;
1216
1217   *pstatement = this->make_statement(build1_loc(location.gcc_location(),
1218                                                 DECL_EXPR,
1219                                                 void_type_node, var));
1220   return new Bvariable(var);
1221 }
1222
1223 // Create a named immutable initialized data structure.
1224
1225 Bvariable*
1226 Gcc_backend::immutable_struct(const std::string& name, bool, Btype* btype,
1227                               Location location)
1228 {
1229   tree type_tree = btype->get_tree();
1230   if (type_tree == error_mark_node)
1231     return this->error_variable();
1232   gcc_assert(TREE_CODE(type_tree) == RECORD_TYPE);
1233   tree decl = build_decl(location.gcc_location(), VAR_DECL,
1234                          get_identifier_from_string(name),
1235                          build_qualified_type(type_tree, TYPE_QUAL_CONST));
1236   TREE_STATIC(decl) = 1;
1237   TREE_READONLY(decl) = 1;
1238   TREE_CONSTANT(decl) = 1;
1239   TREE_USED(decl) = 1;
1240   DECL_ARTIFICIAL(decl) = 1;
1241
1242   // We don't call rest_of_decl_compilation until we have the
1243   // initializer.
1244
1245   go_preserve_from_gc(decl);
1246   return new Bvariable(decl);
1247 }
1248
1249 // Set the initializer for a variable created by immutable_struct.
1250 // This is where we finish compiling the variable.
1251
1252 void
1253 Gcc_backend::immutable_struct_set_init(Bvariable* var, const std::string&,
1254                                        bool is_common, Btype*,
1255                                        Location,
1256                                        Bexpression* initializer)
1257 {
1258   tree decl = var->get_tree();
1259   tree init_tree = initializer->get_tree();
1260   if (decl == error_mark_node || init_tree == error_mark_node)
1261     return;
1262
1263   DECL_INITIAL(decl) = init_tree;
1264
1265   // We can't call make_decl_one_only until we set DECL_INITIAL.
1266   if (!is_common)
1267     TREE_PUBLIC(decl) = 1;
1268   else
1269     {
1270       make_decl_one_only(decl, DECL_ASSEMBLER_NAME(decl));
1271       resolve_unique_section(decl, 1, 0);
1272     }
1273
1274   rest_of_decl_compilation(decl, 1, 0);
1275 }
1276
1277 // Return a reference to an immutable initialized data structure
1278 // defined in another package.
1279
1280 Bvariable*
1281 Gcc_backend::immutable_struct_reference(const std::string& name, Btype* btype,
1282                                         Location location)
1283 {
1284   tree type_tree = btype->get_tree();
1285   if (type_tree == error_mark_node)
1286     return this->error_variable();
1287   gcc_assert(TREE_CODE(type_tree) == RECORD_TYPE);
1288   tree decl = build_decl(location.gcc_location(), VAR_DECL,
1289                          get_identifier_from_string(name),
1290                          build_qualified_type(type_tree, TYPE_QUAL_CONST));
1291   TREE_READONLY(decl) = 1;
1292   TREE_CONSTANT(decl) = 1;
1293   DECL_ARTIFICIAL(decl) = 1;
1294   TREE_PUBLIC(decl) = 1;
1295   DECL_EXTERNAL(decl) = 1;
1296   go_preserve_from_gc(decl);
1297   return new Bvariable(decl);
1298 }
1299
1300 // Make a label.
1301
1302 Blabel*
1303 Gcc_backend::label(Bfunction* function, const std::string& name,
1304                    Location location)
1305 {
1306   tree decl;
1307   if (name.empty())
1308     decl = create_artificial_label(location.gcc_location());
1309   else
1310     {
1311       tree id = get_identifier_from_string(name);
1312       decl = build_decl(location.gcc_location(), LABEL_DECL, id,
1313                         void_type_node);
1314       DECL_CONTEXT(decl) = function->get_tree();
1315     }
1316   return new Blabel(decl);
1317 }
1318
1319 // Make a statement which defines a label.
1320
1321 Bstatement*
1322 Gcc_backend::label_definition_statement(Blabel* label)
1323 {
1324   tree lab = label->get_tree();
1325   tree ret = fold_build1_loc(DECL_SOURCE_LOCATION(lab), LABEL_EXPR,
1326                              void_type_node, lab);
1327   return this->make_statement(ret);
1328 }
1329
1330 // Make a goto statement.
1331
1332 Bstatement*
1333 Gcc_backend::goto_statement(Blabel* label, Location location)
1334 {
1335   tree lab = label->get_tree();
1336   tree ret = fold_build1_loc(location.gcc_location(), GOTO_EXPR, void_type_node,
1337                              lab);
1338   return this->make_statement(ret);
1339 }
1340
1341 // Get the address of a label.
1342
1343 Bexpression*
1344 Gcc_backend::label_address(Blabel* label, Location location)
1345 {
1346   tree lab = label->get_tree();
1347   TREE_USED(lab) = 1;
1348   TREE_ADDRESSABLE(lab) = 1;
1349   tree ret = fold_convert_loc(location.gcc_location(), ptr_type_node,
1350                               build_fold_addr_expr_loc(location.gcc_location(),
1351                                                        lab));
1352   return this->make_expression(ret);
1353 }
1354
1355 // The single backend.
1356
1357 static Gcc_backend gcc_backend;
1358
1359 // Return the backend generator.
1360
1361 Backend*
1362 go_get_backend()
1363 {
1364   return &gcc_backend;
1365 }
1366
1367 // FIXME: Temporary functions while converting to the new backend
1368 // interface.
1369
1370 Btype*
1371 tree_to_type(tree t)
1372 {
1373   return new Btype(t);
1374 }
1375
1376 Bexpression*
1377 tree_to_expr(tree t)
1378 {
1379   return new Bexpression(t);
1380 }
1381
1382 Bstatement*
1383 tree_to_stat(tree t)
1384 {
1385   return new Bstatement(t);
1386 }
1387
1388 Bfunction*
1389 tree_to_function(tree t)
1390 {
1391   return new Bfunction(t);
1392 }
1393
1394 Bblock*
1395 tree_to_block(tree t)
1396 {
1397   gcc_assert(TREE_CODE(t) == BIND_EXPR);
1398   return new Bblock(t);
1399 }
1400
1401 tree
1402 type_to_tree(Btype* bt)
1403 {
1404   return bt->get_tree();
1405 }
1406
1407 tree
1408 expr_to_tree(Bexpression* be)
1409 {
1410   return be->get_tree();
1411 }
1412
1413 tree
1414 stat_to_tree(Bstatement* bs)
1415 {
1416   return bs->get_tree();
1417 }
1418
1419 tree
1420 block_to_tree(Bblock* bb)
1421 {
1422   return bb->get_tree();
1423 }
1424
1425 tree
1426 var_to_tree(Bvariable* bv)
1427 {
1428   return bv->get_tree();
1429 }