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 #include "cfgloop.h"
  51
  52
  53 /* Global variables used to communicate with passes.  */
  54 int dump_flags;
  55 bitmap vars_to_rename;
  56 bool in_gimple_form;
  57
  58 /* The root of the compilation pass tree, once constructed.  */
  59 static struct tree_opt_pass *all_passes;
  60
  61 /* Pass: dump the gimplified, inlined, functions.  */
  62
  63 static struct tree_opt_pass pass_gimple =
  64 {
  65   "gimple",                             /* name */
  66   NULL,                                 /* gate */
  67   NULL,                                 /* execute */
  68   NULL,                                 /* sub */
  69   NULL,                                 /* next */
  70   0,                                    /* static_pass_number */
  71   0,                                    /* tv_id */
  72   0,                                    /* properties_required */
  73   PROP_gimple_any,                      /* properties_provided */
  74   0,                                    /* properties_destroyed */
  75   0,                                    /* todo_flags_start */
  76   TODO_dump_func,                       /* todo_flags_finish */
  77   0                                     /* letter */
  78 };
  79
  80 /* Gate: execute, or not, all of the non-trivial optimizations.  */
  81
  82 static bool
  83 gate_all_optimizations (void)
  84 {
  85   return (optimize >= 1
  86           /* Don't bother doing anything if the program has errors.  */
  87           && !(errorcount || sorrycount));
  88 }
  89
  90 static struct tree_opt_pass pass_all_optimizations =
  91 {
  92   NULL,                                 /* name */
  93   gate_all_optimizations,               /* gate */
  94   NULL,                                 /* execute */
  95   NULL,                                 /* sub */
  96   NULL,                                 /* next */
  97   0,                                    /* static_pass_number */
  98   0,                                    /* tv_id */
  99   0,                                    /* properties_required */
 100   0,                                    /* properties_provided */
 101   0,                                    /* properties_destroyed */
 102   0,                                    /* todo_flags_start */
 103   0,                                    /* todo_flags_finish */
 104   0                                     /* letter */
 105 };
 106
 107 /* Pass: cleanup the CFG just before expanding trees to RTL.
 108    This is just a round of label cleanups and case node grouping
 109    because after the tree optimizers have run such cleanups may
 110    be necessary.  */
 111
 112 static void
 113 execute_cleanup_cfg_post_optimizing (void)
 114 {
 115   cleanup_tree_cfg ();
 116   cleanup_dead_labels ();
 117   group_case_labels ();
 118 }
 119
 120 static struct tree_opt_pass pass_cleanup_cfg_post_optimizing =
 121 {
 122   "final_cleanup",                      /* name */
 123   NULL,                                 /* gate */
 124   execute_cleanup_cfg_post_optimizing,  /* execute */
 125   NULL,                                 /* sub */
 126   NULL,                                 /* next */
 127   0,                                    /* static_pass_number */
 128   0,                                    /* tv_id */
 129   PROP_cfg,                             /* properties_required */
 130   0,                                    /* properties_provided */
 131   0,                                    /* properties_destroyed */
 132   0,                                    /* todo_flags_start */
 133   TODO_dump_func,                                       /* todo_flags_finish */
 134   0                                     /* letter */
 135 };
 136
 137 /* Pass: do the actions required to finish with tree-ssa optimization
 138    passes.  */
 139
 140 static void
 141 execute_free_datastructures (void)
 142 {
 143   tree *chain;
 144
 145   /* ??? This isn't the right place for this.  Worse, it got computed
 146      more or less at random in various passes.  */
 147   free_dominance_info (CDI_DOMINATORS);
 148
 149   /* Emit gotos for implicit jumps.  */
 150   disband_implicit_edges ();
 151
 152   /* Remove the ssa structures.  Do it here since this includes statement
 153      annotations that need to be intact during disband_implicit_edges.  */
 154   delete_tree_ssa ();
 155
 156   /* Re-chain the statements from the blocks.  */
 157   chain = &DECL_SAVED_TREE (current_function_decl);
 158   *chain = alloc_stmt_list ();
 159
 160   /* And get rid of annotations we no longer need.  */
 161   delete_tree_cfg_annotations ();
 162 }
 163
 164 static struct tree_opt_pass pass_free_datastructures =
 165 {
 166   NULL,                                 /* name */
 167   NULL,                                 /* gate */
 168   execute_free_datastructures,                  /* execute */
 169   NULL,                                 /* sub */
 170   NULL,                                 /* next */
 171   0,                                    /* static_pass_number */
 172   0,                                    /* tv_id */
 173   PROP_cfg,                             /* properties_required */
 174   0,                                    /* properties_provided */
 175   0,                                    /* properties_destroyed */
 176   0,                                    /* todo_flags_start */
 177   0,                                    /* todo_flags_finish */
 178   0                                     /* letter */
 179 };
 180
 181
 182 /* Do the actions required to initialize internal data structures used
 183    in tree-ssa optimization passes.  */
 184
 185 static void
 186 execute_init_datastructures (void)
 187 {
 188   /* Allocate hash tables, arrays and other structures.  */
 189   init_tree_ssa ();
 190 }
 191
 192 static struct tree_opt_pass pass_init_datastructures =
 193 {
 194   NULL,                                 /* name */
 195   NULL,                                 /* gate */
 196   execute_init_datastructures,          /* execute */
 197   NULL,                                 /* sub */
 198   NULL,                                 /* next */
 199   0,                                    /* static_pass_number */
 200   0,                                    /* tv_id */
 201   PROP_cfg,                             /* properties_required */
 202   0,                                    /* properties_provided */
 203   0,                                    /* properties_destroyed */
 204   0,                                    /* todo_flags_start */
 205   0,                                    /* todo_flags_finish */
 206   0                                     /* letter */
 207 };
 208
 209 /* Iterate over the pass tree allocating dump file numbers.  We want
 210    to do this depth first, and independent of whether the pass is
 211    enabled or not.  */
 212
 213 static void
 214 register_one_dump_file (struct tree_opt_pass *pass, int n)
 215 {
 216   char *dot_name, *flag_name, *glob_name;
 217   char num[10];
 218
 219   /* See below in next_pass_1.  */
 220   num[0] = '\0';
 221   if (pass->static_pass_number != -1)
 222     sprintf (num, "%d", ((int) pass->static_pass_number < 0
 223                          ? 1 : pass->static_pass_number));
 224
 225   dot_name = concat (".", pass->name, num, NULL);
 226   if (pass->properties_provided & PROP_trees)
 227     {
 228       flag_name = concat ("tree-", pass->name, num, NULL);
 229       glob_name = concat ("tree-", pass->name, NULL);
 230       pass->static_pass_number = dump_register (dot_name, flag_name, glob_name,
 231                                                 TDF_TREE, n + TDI_tree_all, 0);
 232     }
 233   else
 234     {
 235       flag_name = concat ("rtl-", pass->name, num, NULL);
 236       glob_name = concat ("rtl-", pass->name, NULL);
 237       pass->static_pass_number = dump_register (dot_name, flag_name, glob_name,
 238                                                 TDF_RTL, n, pass->letter);
 239     }
 240 }
 241
 242 static int
 243 register_dump_files (struct tree_opt_pass *pass, int properties)
 244 {
 245   static int n = 0;
 246   do
 247     {
 248       int new_properties;
 249       int pass_number;
 250
 251       pass->properties_required = properties;
 252       new_properties =
 253         (properties | pass->properties_provided) & ~pass->properties_destroyed;
 254
 255       /* Reset the counter when we reach RTL-based passes.  */
 256       if ((pass->properties_provided ^ pass->properties_required) & PROP_rtl)
 257         n = 0;
 258
 259       pass_number = n;
 260       if (pass->name)
 261         n++;
 262
 263       if (pass->sub)
 264         new_properties = register_dump_files (pass->sub, new_properties);
 265
 266       /* If we have a gate, combine the properties that we could have with
 267          and without the pass being examined.  */
 268       if (pass->gate)
 269         properties &= new_properties;
 270       else
 271         properties = new_properties;
 272
 273       pass->properties_provided = properties;
 274       if (pass->name)
 275         register_one_dump_file (pass, pass_number);
 276
 277       pass = pass->next;
 278     }
 279   while (pass);
 280
 281   return properties;
 282 }
 283
 284 /* Add a pass to the pass list. Duplicate the pass if it's already
 285    in the list.  */
 286
 287 static struct tree_opt_pass **
 288 next_pass_1 (struct tree_opt_pass **list, struct tree_opt_pass *pass)
 289 {
 290
 291   /* A nonzero static_pass_number indicates that the
 292      pass is already in the list.  */
 293   if (pass->static_pass_number)
 294     {
 295       struct tree_opt_pass *new;
 296
 297       new = xmalloc (sizeof (*new));
 298       memcpy (new, pass, sizeof (*new));
 299
 300       /* Indicate to register_dump_files that this pass has duplicates,
 301          and so it should rename the dump file.  The first instance will
 302          be -1, and be number of duplicates = -static_pass_number - 1.
 303          Subsequent instances will be > 0 and just the duplicate number.  */
 304       if (pass->name)
 305         {
 306           pass->static_pass_number -= 1;
 307           new->static_pass_number = -pass->static_pass_number;
 308         }
 309
 310       *list = new;
 311     }
 312   else
 313     {
 314       pass->static_pass_number = -1;
 315       *list = pass;
 316     }
 317
 318   return &(*list)->next;
 319
 320 }
 321
 322 /* Construct the pass tree.  */
 323
 324 void
 325 init_tree_optimization_passes (void)
 326 {
 327   struct tree_opt_pass **p;
 328
 329 #define NEXT_PASS(PASS)  (p = next_pass_1 (p, &PASS))
 330
 331   p = &all_passes;
 332   NEXT_PASS (pass_gimple);
 333   NEXT_PASS (pass_remove_useless_stmts);
 334   NEXT_PASS (pass_mudflap_1);
 335   NEXT_PASS (pass_lower_cf);
 336   NEXT_PASS (pass_lower_eh);
 337   NEXT_PASS (pass_build_cfg);
 338   NEXT_PASS (pass_pre_expand);
 339   NEXT_PASS (pass_tree_profile);
 340   NEXT_PASS (pass_init_datastructures);
 341   NEXT_PASS (pass_all_optimizations);
 342   NEXT_PASS (pass_warn_function_return);
 343   NEXT_PASS (pass_mudflap_2);
 344   NEXT_PASS (pass_free_datastructures);
 345   NEXT_PASS (pass_expand);
 346   NEXT_PASS (pass_rest_of_compilation);
 347   *p = NULL;
 348
 349   p = &pass_all_optimizations.sub;
 350   NEXT_PASS (pass_referenced_vars);
 351   NEXT_PASS (pass_create_structure_vars);
 352   NEXT_PASS (pass_build_ssa);
 353   NEXT_PASS (pass_may_alias);
 354   NEXT_PASS (pass_rename_ssa_copies);
 355   NEXT_PASS (pass_early_warn_uninitialized);
 356   NEXT_PASS (pass_dce);
 357   NEXT_PASS (pass_dominator);
 358   NEXT_PASS (pass_redundant_phi);
 359   NEXT_PASS (pass_dce);
 360   NEXT_PASS (pass_merge_phi);
 361   NEXT_PASS (pass_forwprop);
 362   NEXT_PASS (pass_phiopt);
 363   NEXT_PASS (pass_may_alias);
 364   NEXT_PASS (pass_tail_recursion);
 365   NEXT_PASS (pass_ch);
 366   NEXT_PASS (pass_profile);
 367   NEXT_PASS (pass_sra);
 368   /* FIXME: SRA may generate arbitrary gimple code, exposing new
 369      aliased and call-clobbered variables.  As mentioned below,
 370      pass_may_alias should be a TODO item.  */
 371   NEXT_PASS (pass_may_alias);
 372   NEXT_PASS (pass_rename_ssa_copies);
 373   NEXT_PASS (pass_dominator);
 374   NEXT_PASS (pass_redundant_phi);
 375   NEXT_PASS (pass_dce);
 376   NEXT_PASS (pass_dse);
 377   NEXT_PASS (pass_may_alias);
 378   NEXT_PASS (pass_forwprop);
 379   NEXT_PASS (pass_phiopt);
 380   NEXT_PASS (pass_ccp);
 381   NEXT_PASS (pass_redundant_phi);
 382   NEXT_PASS (pass_fold_builtins);
 383   /* FIXME: May alias should a TODO but for 4.0.0,
 384      we add may_alias right after fold builtins
 385      which can create arbitrary GIMPLE.  */
 386   NEXT_PASS (pass_may_alias);
 387   NEXT_PASS (pass_split_crit_edges);
 388   NEXT_PASS (pass_pre);
 389   NEXT_PASS (pass_sink_code);
 390   NEXT_PASS (pass_loop);
 391   NEXT_PASS (pass_dominator);
 392   NEXT_PASS (pass_redundant_phi);
 393   /* FIXME: If DCE is not run before checking for uninitialized uses,
 394      we may get false warnings (e.g., testsuite/gcc.dg/uninit-5.c).
 395      However, this also causes us to misdiagnose cases that should be
 396      real warnings (e.g., testsuite/gcc.dg/pr18501.c).
 397
 398      To fix the false positives in uninit-5.c, we would have to
 399      account for the predicates protecting the set and the use of each
 400      variable.  Using a representation like Gated Single Assignment
 401      may help.  */
 402   NEXT_PASS (pass_late_warn_uninitialized);
 403   NEXT_PASS (pass_cd_dce);
 404   NEXT_PASS (pass_dse);
 405   NEXT_PASS (pass_forwprop);
 406   NEXT_PASS (pass_phiopt);
 407   NEXT_PASS (pass_tail_calls);
 408   NEXT_PASS (pass_rename_ssa_copies);
 409   NEXT_PASS (pass_del_ssa);
 410   NEXT_PASS (pass_nrv);
 411   NEXT_PASS (pass_remove_useless_vars);
 412   NEXT_PASS (pass_mark_used_blocks);
 413   NEXT_PASS (pass_cleanup_cfg_post_optimizing);
 414   *p = NULL;
 415
 416   p = &pass_loop.sub;
 417   NEXT_PASS (pass_loop_init);
 418   NEXT_PASS (pass_lim);
 419   NEXT_PASS (pass_unswitch);
 420   NEXT_PASS (pass_record_bounds);
 421   NEXT_PASS (pass_linear_transform);
 422   NEXT_PASS (pass_iv_canon);
 423   NEXT_PASS (pass_if_conversion);
 424   NEXT_PASS (pass_vectorize);
 425   NEXT_PASS (pass_complete_unroll);
 426   NEXT_PASS (pass_iv_optimize);
 427   NEXT_PASS (pass_loop_done);
 428   *p = NULL;
 429
 430 #undef NEXT_PASS
 431
 432   /* Register the passes with the tree dump code.  */
 433   register_dump_files (all_passes, 0);
 434 }
 435
 436 static void execute_pass_list (struct tree_opt_pass *);
 437
 438 static unsigned int last_verified;
 439
 440 static void
 441 execute_todo (int properties, unsigned int flags)
 442 {
 443   if (flags & TODO_rename_vars)
 444     {
 445       rewrite_into_ssa (false);
 446       bitmap_clear (vars_to_rename);
 447     }
 448   if (flags & TODO_fix_def_def_chains)
 449     {
 450       rewrite_def_def_chains ();
 451       bitmap_clear (vars_to_rename);
 452     }
 453
 454   if (flags & TODO_cleanup_cfg)
 455     {
 456       if (current_loops)
 457         cleanup_tree_cfg_loop ();
 458       else
 459         cleanup_tree_cfg ();
 460     }
 461
 462   if ((flags & TODO_dump_func) && dump_file)
 463     {
 464       if (properties & PROP_trees)
 465         dump_function_to_file (current_function_decl,
 466                                dump_file, dump_flags);
 467       else if (properties & PROP_cfg)
 468         print_rtl_with_bb (dump_file, get_insns ());
 469       else
 470         print_rtl (dump_file, get_insns ());
 471
 472       /* Flush the file.  If verification fails, we won't be able to
 473          close the file before aborting.  */
 474       fflush (dump_file);
 475     }
 476
 477   if (flags & TODO_ggc_collect)
 478     ggc_collect ();
 479
 480 #ifdef ENABLE_CHECKING
 481   if (flags & TODO_verify_ssa)
 482     verify_ssa ();
 483   if (flags & TODO_verify_flow)
 484     verify_flow_info ();
 485   if (flags & TODO_verify_stmts)
 486     verify_stmts ();
 487 #endif
 488 }
 489
 490 static bool
 491 execute_one_pass (struct tree_opt_pass *pass)
 492 {
 493   unsigned int todo;
 494
 495   /* See if we're supposed to run this pass.  */
 496   if (pass->gate && !pass->gate ())
 497     return false;
 498
 499   /* Note that the folders should only create gimple expressions.
 500      This is a hack until the new folder is ready.  */
 501   in_gimple_form = (pass->properties_provided & PROP_trees) != 0;
 502
 503   /* Run pre-pass verification.  */
 504   todo = pass->todo_flags_start & ~last_verified;
 505   if (todo)
 506     execute_todo (pass->properties_required, todo);
 507
 508   /* If a dump file name is present, open it if enabled.  */
 509   if (pass->static_pass_number != -1)
 510     {
 511       bool initializing_dump = !dump_initialized_p (pass->static_pass_number);
 512       dump_file_name = get_dump_file_name (pass->static_pass_number);
 513       dump_file = dump_begin (pass->static_pass_number, &dump_flags);
 514       if (dump_file)
 515         {
 516           const char *dname, *aname;
 517           dname = lang_hooks.decl_printable_name (current_function_decl, 2);
 518           aname = (IDENTIFIER_POINTER
 519                    (DECL_ASSEMBLER_NAME (current_function_decl)));
 520           fprintf (dump_file, "\n;; Function %s (%s)%s\n\n", dname, aname,
 521              cfun->function_frequency == FUNCTION_FREQUENCY_HOT
 522              ? " (hot)"
 523              : cfun->function_frequency == FUNCTION_FREQUENCY_UNLIKELY_EXECUTED
 524              ? " (unlikely executed)"
 525              : "");
 526         }
 527
 528       if (initializing_dump
 529           && graph_dump_format != no_graph
 530           && (pass->properties_provided & (PROP_cfg | PROP_rtl))
 531               == (PROP_cfg | PROP_rtl))
 532         clean_graph_dump_file (dump_file_name);
 533     }
 534
 535   /* If a timevar is present, start it.  */
 536   if (pass->tv_id)
 537     timevar_push (pass->tv_id);
 538
 539   /* Do it!  */
 540   if (pass->execute)
 541     pass->execute ();
 542
 543   /* Stop timevar.  */
 544   if (pass->tv_id)
 545     timevar_pop (pass->tv_id);
 546
 547   if (dump_file
 548       && (pass->properties_provided & (PROP_cfg | PROP_rtl))
 549           == (PROP_cfg | PROP_rtl))
 550     print_rtl_with_bb (dump_file, get_insns ());
 551
 552   /* Run post-pass cleanup and verification.  */
 553   todo = pass->todo_flags_finish;
 554   last_verified = todo & TODO_verify_all;
 555   if (todo)
 556     execute_todo (pass->properties_provided, todo);
 557
 558   /* Flush and close dump file.  */
 559   if (dump_file_name)
 560     {
 561       free ((char *) dump_file_name);
 562       dump_file_name = NULL;
 563     }
 564   if (dump_file)
 565     {
 566       dump_end (pass->static_pass_number, dump_file);
 567       dump_file = NULL;
 568     }
 569
 570   return true;
 571 }
 572
 573 static void
 574 execute_pass_list (struct tree_opt_pass *pass)
 575 {
 576   do
 577     {
 578       if (execute_one_pass (pass) && pass->sub)
 579         execute_pass_list (pass->sub);
 580       pass = pass->next;
 581     }
 582   while (pass);
 583 }
 584 \f
 585
 586 /* Update recursively all inlined_to pointers of functions
 587    inlined into NODE to INLINED_TO.  */
 588 static void
 589 update_inlined_to_pointers (struct cgraph_node *node,
 590                             struct cgraph_node *inlined_to)
 591 {
 592   struct cgraph_edge *e;
 593   for (e = node->callees; e; e = e->next_callee)
 594     {
 595       if (e->callee->global.inlined_to)
 596         {
 597           e->callee->global.inlined_to = inlined_to;
 598           update_inlined_to_pointers (e->callee, inlined_to);
 599         }
 600     }
 601 }
 602
 603 \f
 604 /* For functions-as-trees languages, this performs all optimization and
 605    compilation for FNDECL.  */
 606
 607 void
 608 tree_rest_of_compilation (tree fndecl)
 609 {
 610   location_t saved_loc;
 611   struct cgraph_node *saved_node = NULL, *node;
 612
 613   timevar_push (TV_EXPAND);
 614
 615   gcc_assert (!flag_unit_at_a_time || cgraph_global_info_ready);
 616
 617   /* Initialize the RTL code for the function.  */
 618   current_function_decl = fndecl;
 619   saved_loc = input_location;
 620   input_location = DECL_SOURCE_LOCATION (fndecl);
 621   init_function_start (fndecl);
 622
 623   /* Even though we're inside a function body, we still don't want to
 624      call expand_expr to calculate the size of a variable-sized array.
 625      We haven't necessarily assigned RTL to all variables yet, so it's
 626      not safe to try to expand expressions involving them.  */
 627   cfun->x_dont_save_pending_sizes_p = 1;
 628
 629   node = cgraph_node (fndecl);
 630
 631   /* We might need the body of this function so that we can expand
 632      it inline somewhere else.  This means not lowering some constructs
 633      such as exception handling.  */
 634   if (cgraph_preserve_function_body_p (fndecl))
 635     {
 636       if (!flag_unit_at_a_time)
 637         {
 638           struct cgraph_edge *e;
 639
 640           saved_node = cgraph_clone_node (node);
 641           for (e = saved_node->callees; e; e = e->next_callee)
 642             if (!e->inline_failed)
 643               cgraph_clone_inlined_nodes (e, true);
 644         }
 645       cfun->saved_static_chain_decl = cfun->static_chain_decl;
 646       cfun->saved_tree = save_body (fndecl, &cfun->saved_args,
 647                                     &cfun->saved_static_chain_decl);
 648     }
 649
 650   if (flag_inline_trees)
 651     {
 652       struct cgraph_edge *e;
 653       for (e = node->callees; e; e = e->next_callee)
 654         if (!e->inline_failed || warn_inline)
 655           break;
 656       if (e)
 657         {
 658           timevar_push (TV_INTEGRATION);
 659           optimize_inline_calls (fndecl);
 660           timevar_pop (TV_INTEGRATION);
 661         }
 662     }
 663
 664   /* We are not going to maintain the cgraph edges up to date.
 665      Kill it so it won't confuse us.  */
 666   cgraph_node_remove_callees (node);
 667
 668
 669   /* Initialize the default bitmap obstack.  */
 670   bitmap_obstack_initialize (NULL);
 671   bitmap_obstack_initialize (&reg_obstack); /* FIXME, only at RTL generation*/
 672
 673   vars_to_rename = BITMAP_ALLOC (NULL);
 674
 675   /* Perform all tree transforms and optimizations.  */
 676   execute_pass_list (all_passes);
 677
 678   bitmap_obstack_release (&reg_obstack);
 679
 680   /* Release the default bitmap obstack.  */
 681   bitmap_obstack_release (NULL);
 682
 683   /* Restore original body if still needed.  */
 684   if (cfun->saved_tree)
 685     {
 686       DECL_SAVED_TREE (fndecl) = cfun->saved_tree;
 687       DECL_ARGUMENTS (fndecl) = cfun->saved_args;
 688       cfun->static_chain_decl = cfun->saved_static_chain_decl;
 689
 690       /* When not in unit-at-a-time mode, we must preserve out of line copy
 691          representing node before inlining.  Restore original outgoing edges
 692          using clone we created earlier.  */
 693       if (!flag_unit_at_a_time)
 694         {
 695           struct cgraph_edge *e;
 696
 697           cgraph_node_remove_callees (node);
 698           node->callees = saved_node->callees;
 699           saved_node->callees = NULL;
 700           update_inlined_to_pointers (node, node);
 701           for (e = node->callees; e; e = e->next_callee)
 702             e->caller = node;
 703           cgraph_remove_node (saved_node);
 704         }
 705     }
 706   else
 707     DECL_SAVED_TREE (fndecl) = NULL;
 708   cfun = 0;
 709
 710   /* If requested, warn about function definitions where the function will
 711      return a value (usually of some struct or union type) which itself will
 712      take up a lot of stack space.  */
 713   if (warn_larger_than && !DECL_EXTERNAL (fndecl) && TREE_TYPE (fndecl))
 714     {
 715       tree ret_type = TREE_TYPE (TREE_TYPE (fndecl));
 716
 717       if (ret_type && TYPE_SIZE_UNIT (ret_type)
 718           && TREE_CODE (TYPE_SIZE_UNIT (ret_type)) == INTEGER_CST
 719           && 0 < compare_tree_int (TYPE_SIZE_UNIT (ret_type),
 720                                    larger_than_size))
 721         {
 722           unsigned int size_as_int
 723             = TREE_INT_CST_LOW (TYPE_SIZE_UNIT (ret_type));
 724
 725           if (compare_tree_int (TYPE_SIZE_UNIT (ret_type), size_as_int) == 0)
 726             warning ("%Jsize of return value of %qD is %u bytes",
 727                      fndecl, fndecl, size_as_int);
 728           else
 729             warning ("%Jsize of return value of %qD is larger than %wd bytes",
 730                      fndecl, fndecl, larger_than_size);
 731         }
 732     }
 733
 734   if (!flag_inline_trees)
 735     {
 736       DECL_SAVED_TREE (fndecl) = NULL;
 737       if (DECL_STRUCT_FUNCTION (fndecl) == 0
 738           && !cgraph_node (fndecl)->origin)
 739         {
 740           /* Stop pointing to the local nodes about to be freed.
 741              But DECL_INITIAL must remain nonzero so we know this
 742              was an actual function definition.
 743              For a nested function, this is done in c_pop_function_context.
 744              If rest_of_compilation set this to 0, leave it 0.  */
 745           if (DECL_INITIAL (fndecl) != 0)
 746             DECL_INITIAL (fndecl) = error_mark_node;
 747         }
 748     }
 749
 750   input_location = saved_loc;
 751
 752   ggc_collect ();
 753   timevar_pop (TV_EXPAND);
 754 }