gcc/tree-optimize.c

   1 /* Top-level control of tree optimizations.
   2    Copyright 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
   3    Contributed by Diego Novillo <dnovillo@redhat.com>
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify
   8 it under the terms of the GNU General Public License as published by
   9 the Free Software Foundation; either version 2, or (at your option)
  10 any later version.
  11
  12 GCC is distributed in the hope that it will be useful,
  13 but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 GNU General Public License for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GCC; see the file COPYING.  If not, write to
  19 the Free Software Foundation, 59 Temple Place - Suite 330,
  20 Boston, MA 02111-1307, USA.  */
  21
  22 #include "config.h"
  23 #include "system.h"
  24 #include "coretypes.h"
  25 #include "tm.h"
  26 #include "tree.h"
  27 #include "rtl.h"
  28 #include "tm_p.h"
  29 #include "hard-reg-set.h"
  30 #include "basic-block.h"
  31 #include "output.h"
  32 #include "expr.h"
  33 #include "diagnostic.h"
  34 #include "basic-block.h"
  35 #include "flags.h"
  36 #include "tree-flow.h"
  37 #include "tree-dump.h"
  38 #include "timevar.h"
  39 #include "function.h"
  40 #include "langhooks.h"
  41 #include "toplev.h"
  42 #include "flags.h"
  43 #include "cgraph.h"
  44 #include "tree-inline.h"
  45 #include "tree-mudflap.h"
  46 #include "tree-pass.h"
  47 #include "ggc.h"
  48 #include "cgraph.h"
  49 #include "graph.h"
  50
  51
  52 /* Global variables used to communicate with passes.  */
  53 int dump_flags;
  54 bitmap vars_to_rename;
  55 bool in_gimple_form;
  56
  57 /* The root of the compilation pass tree, once constructed.  */
  58 static struct tree_opt_pass *all_passes;
  59
  60 /* Pass: dump the gimplified, inlined, functions.  */
  61
  62 static struct tree_opt_pass pass_gimple =
  63 {
  64   "gimple",                             /* name */
  65   NULL,                                 /* gate */
  66   NULL,                                 /* execute */
  67   NULL,                                 /* sub */
  68   NULL,                                 /* next */
  69   0,                                    /* static_pass_number */
  70   0,                                    /* tv_id */
  71   0,                                    /* properties_required */
  72   PROP_gimple_any,                      /* properties_provided */
  73   0,                                    /* properties_destroyed */
  74   0,                                    /* todo_flags_start */
  75   TODO_dump_func,                       /* todo_flags_finish */
  76   0                                     /* letter */
  77 };
  78
  79 /* Gate: execute, or not, all of the non-trivial optimizations.  */
  80
  81 static bool
  82 gate_all_optimizations (void)
  83 {
  84   return (optimize >= 1
  85           /* Don't bother doing anything if the program has errors.  */
  86           && !(errorcount || sorrycount));
  87 }
  88
  89 static struct tree_opt_pass pass_all_optimizations =
  90 {
  91   NULL,                                 /* name */
  92   gate_all_optimizations,               /* gate */
  93   NULL,                                 /* execute */
  94   NULL,                                 /* sub */
  95   NULL,                                 /* next */
  96   0,                                    /* static_pass_number */
  97   0,                                    /* tv_id */
  98   0,                                    /* properties_required */
  99   0,                                    /* properties_provided */
 100   0,                                    /* properties_destroyed */
 101   0,                                    /* todo_flags_start */
 102   0,                                    /* todo_flags_finish */
 103   0                                     /* letter */
 104 };
 105
 106 /* Pass: cleanup the CFG just before expanding trees to RTL.
 107    This is just a round of label cleanups and case node grouping
 108    because after the tree optimizers have run such cleanups may
 109    be necessary.  */
 110
 111 static void
 112 execute_cleanup_cfg_post_optimizing (void)
 113 {
 114   cleanup_tree_cfg ();
 115   cleanup_dead_labels ();
 116   group_case_labels ();
 117 }
 118
 119 static struct tree_opt_pass pass_cleanup_cfg_post_optimizing =
 120 {
 121   "final_cleanup",                      /* name */
 122   NULL,                                 /* gate */
 123   execute_cleanup_cfg_post_optimizing,  /* execute */
 124   NULL,                                 /* sub */
 125   NULL,                                 /* next */
 126   0,                                    /* static_pass_number */
 127   0,                                    /* tv_id */
 128   PROP_cfg,                             /* properties_required */
 129   0,                                    /* properties_provided */
 130   0,                                    /* properties_destroyed */
 131   0,                                    /* todo_flags_start */
 132   TODO_dump_func,                                       /* todo_flags_finish */
 133   0                                     /* letter */
 134 };
 135
 136 /* Pass: do the actions required to finish with tree-ssa optimization
 137    passes.  */
 138
 139 static void
 140 execute_free_datastructures (void)
 141 {
 142   tree *chain;
 143
 144   /* ??? This isn't the right place for this.  Worse, it got computed
 145      more or less at random in various passes.  */
 146   free_dominance_info (CDI_DOMINATORS);
 147
 148   /* Emit gotos for implicit jumps.  */
 149   disband_implicit_edges ();
 150
 151   /* Remove the ssa structures.  Do it here since this includes statement
 152      annotations that need to be intact during disband_implicit_edges.  */
 153   delete_tree_ssa ();
 154
 155   /* Re-chain the statements from the blocks.  */
 156   chain = &DECL_SAVED_TREE (current_function_decl);
 157   *chain = alloc_stmt_list ();
 158
 159   /* And get rid of annotations we no longer need.  */
 160   delete_tree_cfg_annotations ();
 161 }
 162
 163 static struct tree_opt_pass pass_free_datastructures =
 164 {
 165   NULL,                                 /* name */
 166   NULL,                                 /* gate */
 167   execute_free_datastructures,                  /* execute */
 168   NULL,                                 /* sub */
 169   NULL,                                 /* next */
 170   0,                                    /* static_pass_number */
 171   0,                                    /* tv_id */
 172   PROP_cfg,                             /* properties_required */
 173   0,                                    /* properties_provided */
 174   0,                                    /* properties_destroyed */
 175   0,                                    /* todo_flags_start */
 176   0,                                    /* todo_flags_finish */
 177   0                                     /* letter */
 178 };
 179
 180
 181 /* Do the actions required to initialize internal data structures used
 182    in tree-ssa optimization passes.  */
 183
 184 static void
 185 execute_init_datastructures (void)
 186 {
 187   /* Allocate hash tables, arrays and other structures.  */
 188   init_tree_ssa ();
 189 }
 190
 191 static struct tree_opt_pass pass_init_datastructures =
 192 {
 193   NULL,                                 /* name */
 194   NULL,                                 /* gate */
 195   execute_init_datastructures,          /* execute */
 196   NULL,                                 /* sub */
 197   NULL,                                 /* next */
 198   0,                                    /* static_pass_number */
 199   0,                                    /* tv_id */
 200   PROP_cfg,                             /* properties_required */
 201   0,                                    /* properties_provided */
 202   0,                                    /* properties_destroyed */
 203   0,                                    /* todo_flags_start */
 204   0,                                    /* todo_flags_finish */
 205   0                                     /* letter */
 206 };
 207
 208 /* Iterate over the pass tree allocating dump file numbers.  We want
 209    to do this depth first, and independent of whether the pass is
 210    enabled or not.  */
 211
 212 static void
 213 register_one_dump_file (struct tree_opt_pass *pass, int n)
 214 {
 215   char *dot_name, *flag_name, *glob_name;
 216   char num[10];
 217
 218   /* See below in next_pass_1.  */
 219   num[0] = '\0';
 220   if (pass->static_pass_number != -1)
 221     sprintf (num, "%d", ((int) pass->static_pass_number < 0
 222                          ? 1 : pass->static_pass_number));
 223
 224   dot_name = concat (".", pass->name, num, NULL);
 225   if (pass->properties_provided & PROP_trees)
 226     {
 227       flag_name = concat ("tree-", pass->name, num, NULL);
 228       glob_name = concat ("tree-", pass->name, NULL);
 229       pass->static_pass_number = dump_register (dot_name, flag_name, glob_name,
 230                                                 TDF_TREE, n + TDI_tree_all, 0);
 231     }
 232   else
 233     {
 234       flag_name = concat ("rtl-", pass->name, num, NULL);
 235       glob_name = concat ("rtl-", pass->name, NULL);
 236       pass->static_pass_number = dump_register (dot_name, flag_name, glob_name,
 237                                                 TDF_RTL, n, pass->letter);
 238     }
 239 }
 240
 241 static int
 242 register_dump_files (struct tree_opt_pass *pass, int properties)
 243 {
 244   static int n = 0;
 245   do
 246     {
 247       int new_properties;
 248       int pass_number;
 249
 250       pass->properties_required = properties;
 251       new_properties =
 252         (properties | pass->properties_provided) & ~pass->properties_destroyed;
 253
 254       /* Reset the counter when we reach RTL-based passes.  */
 255       if ((pass->properties_provided ^ pass->properties_required) & PROP_rtl)
 256         n = 0;
 257
 258       pass_number = n;
 259       if (pass->name)
 260         n++;
 261
 262       if (pass->sub)
 263         new_properties = register_dump_files (pass->sub, new_properties);
 264
 265       /* If we have a gate, combine the properties that we could have with
 266          and without the pass being examined.  */
 267       if (pass->gate)
 268         properties &= new_properties;
 269       else
 270         properties = new_properties;
 271
 272       pass->properties_provided = properties;
 273       if (pass->name)
 274         register_one_dump_file (pass, pass_number);
 275
 276       pass = pass->next;
 277     }
 278   while (pass);
 279
 280   return properties;
 281 }
 282
 283 /* Add a pass to the pass list. Duplicate the pass if it's already
 284    in the list.  */
 285
 286 static struct tree_opt_pass **
 287 next_pass_1 (struct tree_opt_pass **list, struct tree_opt_pass *pass)
 288 {
 289
 290   /* A nonzero static_pass_number indicates that the
 291      pass is already in the list.  */
 292   if (pass->static_pass_number)
 293     {
 294       struct tree_opt_pass *new;
 295
 296       new = xmalloc (sizeof (*new));
 297       memcpy (new, pass, sizeof (*new));
 298
 299       /* Indicate to register_dump_files that this pass has duplicates,
 300          and so it should rename the dump file.  The first instance will
 301          be -1, and be number of duplicates = -static_pass_number - 1.
 302          Subsequent instances will be > 0 and just the duplicate number.  */
 303       if (pass->name)
 304         {
 305           pass->static_pass_number -= 1;
 306           new->static_pass_number = -pass->static_pass_number;
 307         }
 308
 309       *list = new;
 310     }
 311   else
 312     {
 313       pass->static_pass_number = -1;
 314       *list = pass;
 315     }
 316
 317   return &(*list)->next;
 318
 319 }
 320
 321 /* Construct the pass tree.  */
 322
 323 void
 324 init_tree_optimization_passes (void)
 325 {
 326   struct tree_opt_pass **p;
 327
 328 #define NEXT_PASS(PASS)  (p = next_pass_1 (p, &PASS))
 329
 330   p = &all_passes;
 331   NEXT_PASS (pass_gimple);
 332   NEXT_PASS (pass_remove_useless_stmts);
 333   NEXT_PASS (pass_mudflap_1);
 334   NEXT_PASS (pass_lower_cf);
 335   NEXT_PASS (pass_lower_eh);
 336   NEXT_PASS (pass_build_cfg);
 337   NEXT_PASS (pass_pre_expand);
 338   NEXT_PASS (pass_tree_profile);
 339   NEXT_PASS (pass_init_datastructures);
 340   NEXT_PASS (pass_all_optimizations);
 341   NEXT_PASS (pass_warn_function_return);
 342   NEXT_PASS (pass_mudflap_2);
 343   NEXT_PASS (pass_free_datastructures);
 344   NEXT_PASS (pass_expand);
 345   NEXT_PASS (pass_rest_of_compilation);
 346   *p = NULL;
 347
 348   p = &pass_all_optimizations.sub;
 349   NEXT_PASS (pass_referenced_vars);
 350   NEXT_PASS (pass_build_ssa);
 351   NEXT_PASS (pass_may_alias);
 352   NEXT_PASS (pass_rename_ssa_copies);
 353   NEXT_PASS (pass_early_warn_uninitialized);
 354   NEXT_PASS (pass_dce);
 355   NEXT_PASS (pass_dominator);
 356   NEXT_PASS (pass_redundant_phi);
 357   NEXT_PASS (pass_dce);
 358   NEXT_PASS (pass_merge_phi);
 359   NEXT_PASS (pass_forwprop);
 360   NEXT_PASS (pass_phiopt);
 361   NEXT_PASS (pass_may_alias);
 362   NEXT_PASS (pass_tail_recursion);
 363   NEXT_PASS (pass_ch);
 364   NEXT_PASS (pass_profile);
 365   NEXT_PASS (pass_sra);
 366   /* FIXME: SRA may generate arbitrary gimple code, exposing new
 367      aliased and call-clobbered variables.  As mentioned below,
 368      pass_may_alias should be a TODO item.  */
 369   NEXT_PASS (pass_may_alias);
 370   NEXT_PASS (pass_rename_ssa_copies);
 371   NEXT_PASS (pass_dominator);
 372   NEXT_PASS (pass_redundant_phi);
 373   NEXT_PASS (pass_dce);
 374   NEXT_PASS (pass_dse);
 375   NEXT_PASS (pass_may_alias);
 376   NEXT_PASS (pass_forwprop);
 377   NEXT_PASS (pass_phiopt);
 378   NEXT_PASS (pass_ccp);
 379   NEXT_PASS (pass_redundant_phi);
 380   NEXT_PASS (pass_fold_builtins);
 381   /* FIXME: May alias should a TODO but for 4.0.0,
 382      we add may_alias right after fold builtins
 383      which can create arbitrary GIMPLE.  */
 384   NEXT_PASS (pass_may_alias);
 385   NEXT_PASS (pass_split_crit_edges);
 386   NEXT_PASS (pass_pre);
 387   NEXT_PASS (pass_sink_code);
 388   NEXT_PASS (pass_loop);
 389   NEXT_PASS (pass_dominator);
 390   NEXT_PASS (pass_redundant_phi);
 391   /* FIXME: If DCE is not run before checking for uninitialized uses,
 392      we may get false warnings (e.g., testsuite/gcc.dg/uninit-5.c).
 393      However, this also causes us to misdiagnose cases that should be
 394      real warnings (e.g., testsuite/gcc.dg/pr18501.c).
 395
 396      To fix the false positives in uninit-5.c, we would have to
 397      account for the predicates protecting the set and the use of each
 398      variable.  Using a representation like Gated Single Assignment
 399      may help.  */
 400   NEXT_PASS (pass_late_warn_uninitialized);
 401   NEXT_PASS (pass_cd_dce);
 402   NEXT_PASS (pass_dse);
 403   NEXT_PASS (pass_forwprop);
 404   NEXT_PASS (pass_phiopt);
 405   NEXT_PASS (pass_tail_calls);
 406   NEXT_PASS (pass_rename_ssa_copies);
 407   NEXT_PASS (pass_del_ssa);
 408   NEXT_PASS (pass_nrv);
 409   NEXT_PASS (pass_remove_useless_vars);
 410   NEXT_PASS (pass_mark_used_blocks);
 411   NEXT_PASS (pass_cleanup_cfg_post_optimizing);
 412   *p = NULL;
 413
 414   p = &pass_loop.sub;
 415   NEXT_PASS (pass_loop_init);
 416   NEXT_PASS (pass_lim);
 417   NEXT_PASS (pass_unswitch);
 418   NEXT_PASS (pass_record_bounds);
 419   NEXT_PASS (pass_linear_transform);
 420   NEXT_PASS (pass_iv_canon);
 421   NEXT_PASS (pass_if_conversion);
 422   NEXT_PASS (pass_vectorize);
 423   NEXT_PASS (pass_complete_unroll);
 424   NEXT_PASS (pass_iv_optimize);
 425   NEXT_PASS (pass_loop_done);
 426   *p = NULL;
 427
 428 #undef NEXT_PASS
 429
 430   /* Register the passes with the tree dump code.  */
 431   register_dump_files (all_passes, 0);
 432 }
 433
 434 static void execute_pass_list (struct tree_opt_pass *);
 435
 436 static unsigned int last_verified;
 437
 438 static void
 439 execute_todo (int properties, unsigned int flags)
 440 {
 441   if (flags & TODO_rename_vars)
 442     {
 443       rewrite_into_ssa (false);
 444       bitmap_clear (vars_to_rename);
 445     }
 446   if (flags & TODO_fix_def_def_chains)
 447     {
 448       rewrite_def_def_chains ();
 449       bitmap_clear (vars_to_rename);
 450     }
 451
 452   if (flags & TODO_cleanup_cfg)
 453     cleanup_tree_cfg ();
 454
 455   if ((flags & TODO_dump_func) && dump_file)
 456     {
 457       if (properties & PROP_trees)
 458         dump_function_to_file (current_function_decl,
 459                                dump_file, dump_flags);
 460       else if (properties & PROP_cfg)
 461         print_rtl_with_bb (dump_file, get_insns ());
 462       else
 463         print_rtl (dump_file, get_insns ());
 464
 465       /* Flush the file.  If verification fails, we won't be able to
 466          close the file before aborting.  */
 467       fflush (dump_file);
 468     }
 469
 470   if (flags & TODO_ggc_collect)
 471     ggc_collect ();
 472
 473 #ifdef ENABLE_CHECKING
 474   if (flags & TODO_verify_ssa)
 475     verify_ssa ();
 476   if (flags & TODO_verify_flow)
 477     verify_flow_info ();
 478   if (flags & TODO_verify_stmts)
 479     verify_stmts ();
 480 #endif
 481 }
 482
 483 static bool
 484 execute_one_pass (struct tree_opt_pass *pass)
 485 {
 486   unsigned int todo;
 487
 488   /* See if we're supposed to run this pass.  */
 489   if (pass->gate && !pass->gate ())
 490     return false;
 491
 492   /* Note that the folders should only create gimple expressions.
 493      This is a hack until the new folder is ready.  */
 494   in_gimple_form = (pass->properties_provided & PROP_trees) != 0;
 495
 496   /* Run pre-pass verification.  */
 497   todo = pass->todo_flags_start & ~last_verified;
 498   if (todo)
 499     execute_todo (pass->properties_required, todo);
 500
 501   /* If a dump file name is present, open it if enabled.  */
 502   if (pass->static_pass_number != -1)
 503     {
 504       bool initializing_dump = !dump_initialized_p (pass->static_pass_number);
 505       dump_file_name = get_dump_file_name (pass->static_pass_number);
 506       dump_file = dump_begin (pass->static_pass_number, &dump_flags);
 507       if (dump_file)
 508         {
 509           const char *dname, *aname;
 510           dname = lang_hooks.decl_printable_name (current_function_decl, 2);
 511           aname = (IDENTIFIER_POINTER
 512                    (DECL_ASSEMBLER_NAME (current_function_decl)));
 513           fprintf (dump_file, "\n;; Function %s (%s)%s\n\n", dname, aname,
 514              cfun->function_frequency == FUNCTION_FREQUENCY_HOT
 515              ? " (hot)"
 516              : cfun->function_frequency == FUNCTION_FREQUENCY_UNLIKELY_EXECUTED
 517              ? " (unlikely executed)"
 518              : "");
 519         }
 520
 521       if (initializing_dump
 522           && graph_dump_format != no_graph
 523           && (pass->properties_provided & (PROP_cfg | PROP_rtl))
 524               == (PROP_cfg | PROP_rtl))
 525         clean_graph_dump_file (dump_file_name);
 526     }
 527
 528   /* If a timevar is present, start it.  */
 529   if (pass->tv_id)
 530     timevar_push (pass->tv_id);
 531
 532   /* Do it!  */
 533   if (pass->execute)
 534     pass->execute ();
 535
 536   /* Stop timevar.  */
 537   if (pass->tv_id)
 538     timevar_pop (pass->tv_id);
 539
 540   if (dump_file
 541       && (pass->properties_provided & (PROP_cfg | PROP_rtl))
 542           == (PROP_cfg | PROP_rtl))
 543     print_rtl_with_bb (dump_file, get_insns ());
 544
 545   /* Run post-pass cleanup and verification.  */
 546   todo = pass->todo_flags_finish;
 547   last_verified = todo & TODO_verify_all;
 548   if (todo)
 549     execute_todo (pass->properties_provided, todo);
 550
 551   /* Flush and close dump file.  */
 552   if (dump_file_name)
 553     {
 554       free ((char *) dump_file_name);
 555       dump_file_name = NULL;
 556     }
 557   if (dump_file)
 558     {
 559       dump_end (pass->static_pass_number, dump_file);
 560       dump_file = NULL;
 561     }
 562
 563   return true;
 564 }
 565
 566 static void
 567 execute_pass_list (struct tree_opt_pass *pass)
 568 {
 569   do
 570     {
 571       if (execute_one_pass (pass) && pass->sub)
 572         execute_pass_list (pass->sub);
 573       pass = pass->next;
 574     }
 575   while (pass);
 576 }
 577 \f
 578
 579 /* Update recursively all inlined_to pointers of functions
 580    inlined into NODE to INLINED_TO.  */
 581 static void
 582 update_inlined_to_pointers (struct cgraph_node *node,
 583                             struct cgraph_node *inlined_to)
 584 {
 585   struct cgraph_edge *e;
 586   for (e = node->callees; e; e = e->next_callee)
 587     {
 588       if (e->callee->global.inlined_to)
 589         {
 590           e->callee->global.inlined_to = inlined_to;
 591           update_inlined_to_pointers (e->callee, inlined_to);
 592         }
 593     }
 594 }
 595
 596 \f
 597 /* For functions-as-trees languages, this performs all optimization and
 598    compilation for FNDECL.  */
 599
 600 void
 601 tree_rest_of_compilation (tree fndecl)
 602 {
 603   location_t saved_loc;
 604   struct cgraph_node *saved_node = NULL, *node;
 605
 606   timevar_push (TV_EXPAND);
 607
 608   gcc_assert (!flag_unit_at_a_time || cgraph_global_info_ready);
 609
 610   /* Initialize the RTL code for the function.  */
 611   current_function_decl = fndecl;
 612   saved_loc = input_location;
 613   input_location = DECL_SOURCE_LOCATION (fndecl);
 614   init_function_start (fndecl);
 615
 616   /* Even though we're inside a function body, we still don't want to
 617      call expand_expr to calculate the size of a variable-sized array.
 618      We haven't necessarily assigned RTL to all variables yet, so it's
 619      not safe to try to expand expressions involving them.  */
 620   cfun->x_dont_save_pending_sizes_p = 1;
 621
 622   node = cgraph_node (fndecl);
 623
 624   /* We might need the body of this function so that we can expand
 625      it inline somewhere else.  This means not lowering some constructs
 626      such as exception handling.  */
 627   if (cgraph_preserve_function_body_p (fndecl))
 628     {
 629       if (!flag_unit_at_a_time)
 630         {
 631           struct cgraph_edge *e;
 632
 633           saved_node = cgraph_clone_node (node);
 634           for (e = saved_node->callees; e; e = e->next_callee)
 635             if (!e->inline_failed)
 636               cgraph_clone_inlined_nodes (e, true);
 637         }
 638       cfun->saved_static_chain_decl = cfun->static_chain_decl;
 639       cfun->saved_tree = save_body (fndecl, &cfun->saved_args,
 640                                     &cfun->saved_static_chain_decl);
 641     }
 642
 643   if (flag_inline_trees)
 644     {
 645       struct cgraph_edge *e;
 646       for (e = node->callees; e; e = e->next_callee)
 647         if (!e->inline_failed || warn_inline)
 648           break;
 649       if (e)
 650         {
 651           timevar_push (TV_INTEGRATION);
 652           optimize_inline_calls (fndecl);
 653           timevar_pop (TV_INTEGRATION);
 654         }
 655     }
 656
 657   /* We are not going to maintain the cgraph edges up to date.
 658      Kill it so it won't confuse us.  */
 659   cgraph_node_remove_callees (node);
 660
 661
 662   /* Initialize the default bitmap obstack.  */
 663   bitmap_obstack_initialize (NULL);
 664   bitmap_obstack_initialize (&reg_obstack); /* FIXME, only at RTL generation*/
 665
 666   vars_to_rename = BITMAP_ALLOC (NULL);
 667
 668   /* Perform all tree transforms and optimizations.  */
 669   execute_pass_list (all_passes);
 670
 671   bitmap_obstack_release (&reg_obstack);
 672
 673   /* Release the default bitmap obstack.  */
 674   bitmap_obstack_release (NULL);
 675
 676   /* Restore original body if still needed.  */
 677   if (cfun->saved_tree)
 678     {
 679       DECL_SAVED_TREE (fndecl) = cfun->saved_tree;
 680       DECL_ARGUMENTS (fndecl) = cfun->saved_args;
 681       cfun->static_chain_decl = cfun->saved_static_chain_decl;
 682
 683       /* When not in unit-at-a-time mode, we must preserve out of line copy
 684          representing node before inlining.  Restore original outgoing edges
 685          using clone we created earlier.  */
 686       if (!flag_unit_at_a_time)
 687         {
 688           struct cgraph_edge *e;
 689
 690           cgraph_node_remove_callees (node);
 691           node->callees = saved_node->callees;
 692           saved_node->callees = NULL;
 693           update_inlined_to_pointers (node, node);
 694           for (e = node->callees; e; e = e->next_callee)
 695             e->caller = node;
 696           cgraph_remove_node (saved_node);
 697         }
 698     }
 699   else
 700     DECL_SAVED_TREE (fndecl) = NULL;
 701   cfun = 0;
 702
 703   /* If requested, warn about function definitions where the function will
 704      return a value (usually of some struct or union type) which itself will
 705      take up a lot of stack space.  */
 706   if (warn_larger_than && !DECL_EXTERNAL (fndecl) && TREE_TYPE (fndecl))
 707     {
 708       tree ret_type = TREE_TYPE (TREE_TYPE (fndecl));
 709
 710       if (ret_type && TYPE_SIZE_UNIT (ret_type)
 711           && TREE_CODE (TYPE_SIZE_UNIT (ret_type)) == INTEGER_CST
 712           && 0 < compare_tree_int (TYPE_SIZE_UNIT (ret_type),
 713                                    larger_than_size))
 714         {
 715           unsigned int size_as_int
 716             = TREE_INT_CST_LOW (TYPE_SIZE_UNIT (ret_type));
 717
 718           if (compare_tree_int (TYPE_SIZE_UNIT (ret_type), size_as_int) == 0)
 719             warning ("%Jsize of return value of %qD is %u bytes",
 720                      fndecl, fndecl, size_as_int);
 721           else
 722             warning ("%Jsize of return value of %qD is larger than %wd bytes",
 723                      fndecl, fndecl, larger_than_size);
 724         }
 725     }
 726
 727   if (!flag_inline_trees)
 728     {
 729       DECL_SAVED_TREE (fndecl) = NULL;
 730       if (DECL_STRUCT_FUNCTION (fndecl) == 0
 731           && !cgraph_node (fndecl)->origin)
 732         {
 733           /* Stop pointing to the local nodes about to be freed.
 734              But DECL_INITIAL must remain nonzero so we know this
 735              was an actual function definition.
 736              For a nested function, this is done in c_pop_function_context.
 737              If rest_of_compilation set this to 0, leave it 0.  */
 738           if (DECL_INITIAL (fndecl) != 0)
 739             DECL_INITIAL (fndecl) = error_mark_node;
 740         }
 741     }
 742
 743   input_location = saved_loc;
 744
 745   ggc_collect ();
 746   timevar_pop (TV_EXPAND);
 747 }