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 bool in_gimple_form;
  56
  57 /* The root of the compilation pass tree, once constructed.  */
  58 static struct tree_opt_pass *all_passes, *all_ipa_passes;
  59
  60 /* Gate: execute, or not, all of the non-trivial optimizations.  */
  61
  62 static bool
  63 gate_all_optimizations (void)
  64 {
  65   return (optimize >= 1
  66           /* Don't bother doing anything if the program has errors.  */
  67           && !(errorcount || sorrycount));
  68 }
  69
  70 static struct tree_opt_pass pass_all_optimizations =
  71 {
  72   NULL,                                 /* name */
  73   gate_all_optimizations,               /* gate */
  74   NULL,                                 /* execute */
  75   NULL,                                 /* sub */
  76   NULL,                                 /* next */
  77   0,                                    /* static_pass_number */
  78   0,                                    /* tv_id */
  79   0,                                    /* properties_required */
  80   0,                                    /* properties_provided */
  81   0,                                    /* properties_destroyed */
  82   0,                                    /* todo_flags_start */
  83   0,                                    /* todo_flags_finish */
  84   0                                     /* letter */
  85 };
  86
  87 /* Pass: cleanup the CFG just before expanding trees to RTL.
  88    This is just a round of label cleanups and case node grouping
  89    because after the tree optimizers have run such cleanups may
  90    be necessary.  */
  91
  92 static void
  93 execute_cleanup_cfg_post_optimizing (void)
  94 {
  95   cleanup_tree_cfg ();
  96   cleanup_dead_labels ();
  97   group_case_labels ();
  98 }
  99
 100 static struct tree_opt_pass pass_cleanup_cfg_post_optimizing =
 101 {
 102   "final_cleanup",                      /* name */
 103   NULL,                                 /* gate */
 104   execute_cleanup_cfg_post_optimizing,  /* execute */
 105   NULL,                                 /* sub */
 106   NULL,                                 /* next */
 107   0,                                    /* static_pass_number */
 108   0,                                    /* tv_id */
 109   PROP_cfg,                             /* properties_required */
 110   0,                                    /* properties_provided */
 111   0,                                    /* properties_destroyed */
 112   0,                                    /* todo_flags_start */
 113   TODO_dump_func,                                       /* todo_flags_finish */
 114   0                                     /* letter */
 115 };
 116
 117 /* Pass: do the actions required to finish with tree-ssa optimization
 118    passes.  */
 119
 120 static void
 121 execute_free_datastructures (void)
 122 {
 123   tree *chain;
 124
 125   /* ??? This isn't the right place for this.  Worse, it got computed
 126      more or less at random in various passes.  */
 127   free_dominance_info (CDI_DOMINATORS);
 128
 129   /* Emit gotos for implicit jumps.  */
 130   disband_implicit_edges ();
 131
 132   /* Remove the ssa structures.  Do it here since this includes statement
 133      annotations that need to be intact during disband_implicit_edges.  */
 134   delete_tree_ssa ();
 135
 136   /* Re-chain the statements from the blocks.  */
 137   chain = &DECL_SAVED_TREE (current_function_decl);
 138   *chain = alloc_stmt_list ();
 139
 140   /* And get rid of annotations we no longer need.  */
 141   delete_tree_cfg_annotations ();
 142 }
 143
 144 static struct tree_opt_pass pass_free_datastructures =
 145 {
 146   NULL,                                 /* name */
 147   NULL,                                 /* gate */
 148   execute_free_datastructures,                  /* execute */
 149   NULL,                                 /* sub */
 150   NULL,                                 /* next */
 151   0,                                    /* static_pass_number */
 152   0,                                    /* tv_id */
 153   PROP_cfg,                             /* properties_required */
 154   0,                                    /* properties_provided */
 155   0,                                    /* properties_destroyed */
 156   0,                                    /* todo_flags_start */
 157   0,                                    /* todo_flags_finish */
 158   0                                     /* letter */
 159 };
 160
 161
 162 /* Do the actions required to initialize internal data structures used
 163    in tree-ssa optimization passes.  */
 164
 165 static void
 166 execute_init_datastructures (void)
 167 {
 168   /* Allocate hash tables, arrays and other structures.  */
 169   init_tree_ssa ();
 170 }
 171
 172 static struct tree_opt_pass pass_init_datastructures =
 173 {
 174   NULL,                                 /* name */
 175   NULL,                                 /* gate */
 176   execute_init_datastructures,          /* execute */
 177   NULL,                                 /* sub */
 178   NULL,                                 /* next */
 179   0,                                    /* static_pass_number */
 180   0,                                    /* tv_id */
 181   PROP_cfg,                             /* properties_required */
 182   0,                                    /* properties_provided */
 183   0,                                    /* properties_destroyed */
 184   0,                                    /* todo_flags_start */
 185   0,                                    /* todo_flags_finish */
 186   0                                     /* letter */
 187 };
 188
 189 /* Iterate over the pass tree allocating dump file numbers.  We want
 190    to do this depth first, and independent of whether the pass is
 191    enabled or not.  */
 192
 193 static void
 194 register_one_dump_file (struct tree_opt_pass *pass, bool ipa, int n)
 195 {
 196   char *dot_name, *flag_name, *glob_name;
 197   char num[10];
 198
 199   /* See below in next_pass_1.  */
 200   num[0] = '\0';
 201   if (pass->static_pass_number != -1)
 202     sprintf (num, "%d", ((int) pass->static_pass_number < 0
 203                          ? 1 : pass->static_pass_number));
 204
 205   dot_name = concat (".", pass->name, num, NULL);
 206   if (ipa)
 207     {
 208       flag_name = concat ("ipa-", pass->name, num, NULL);
 209       glob_name = concat ("ipa-", pass->name, NULL);
 210       /* First IPA dump is cgraph that is dumped via separate channels.  */
 211       pass->static_pass_number = dump_register (dot_name, flag_name, glob_name,
 212                                                 TDF_IPA, n + 1, 0);
 213     }
 214   else if (pass->properties_provided & PROP_trees)
 215     {
 216       flag_name = concat ("tree-", pass->name, num, NULL);
 217       glob_name = concat ("tree-", pass->name, NULL);
 218       pass->static_pass_number = dump_register (dot_name, flag_name, glob_name,
 219                                                 TDF_TREE, n + TDI_tree_all, 0);
 220     }
 221   else
 222     {
 223       flag_name = concat ("rtl-", pass->name, num, NULL);
 224       glob_name = concat ("rtl-", pass->name, NULL);
 225       pass->static_pass_number = dump_register (dot_name, flag_name, glob_name,
 226                                                 TDF_RTL, n, pass->letter);
 227     }
 228 }
 229
 230 static int
 231 register_dump_files (struct tree_opt_pass *pass, bool ipa, int properties)
 232 {
 233   static int n = 0;
 234   do
 235     {
 236       int new_properties;
 237       int pass_number;
 238
 239       pass->properties_required = properties;
 240       new_properties =
 241         (properties | pass->properties_provided) & ~pass->properties_destroyed;
 242
 243       /* Reset the counter when we reach RTL-based passes.  */
 244       if ((pass->properties_provided ^ pass->properties_required) & PROP_rtl)
 245         n = 0;
 246
 247       pass_number = n;
 248       if (pass->name)
 249         n++;
 250
 251       if (pass->sub)
 252         new_properties = register_dump_files (pass->sub, ipa, new_properties);
 253
 254       /* If we have a gate, combine the properties that we could have with
 255          and without the pass being examined.  */
 256       if (pass->gate)
 257         properties &= new_properties;
 258       else
 259         properties = new_properties;
 260
 261       pass->properties_provided = properties;
 262       if (pass->name)
 263         register_one_dump_file (pass, ipa, pass_number);
 264
 265       pass = pass->next;
 266     }
 267   while (pass);
 268
 269   return properties;
 270 }
 271
 272 /* Add a pass to the pass list. Duplicate the pass if it's already
 273    in the list.  */
 274
 275 static struct tree_opt_pass **
 276 next_pass_1 (struct tree_opt_pass **list, struct tree_opt_pass *pass)
 277 {
 278
 279   /* A nonzero static_pass_number indicates that the
 280      pass is already in the list.  */
 281   if (pass->static_pass_number)
 282     {
 283       struct tree_opt_pass *new;
 284
 285       new = xmalloc (sizeof (*new));
 286       memcpy (new, pass, sizeof (*new));
 287
 288       /* Indicate to register_dump_files that this pass has duplicates,
 289          and so it should rename the dump file.  The first instance will
 290          be -1, and be number of duplicates = -static_pass_number - 1.
 291          Subsequent instances will be > 0 and just the duplicate number.  */
 292       if (pass->name)
 293         {
 294           pass->static_pass_number -= 1;
 295           new->static_pass_number = -pass->static_pass_number;
 296         }
 297
 298       *list = new;
 299     }
 300   else
 301     {
 302       pass->static_pass_number = -1;
 303       *list = pass;
 304     }
 305
 306   return &(*list)->next;
 307
 308 }
 309
 310 /* Construct the pass tree.  */
 311
 312 void
 313 init_tree_optimization_passes (void)
 314 {
 315   struct tree_opt_pass **p;
 316
 317 #define NEXT_PASS(PASS)  (p = next_pass_1 (p, &PASS))
 318   /* Intraprocedural optimization passes.  */
 319   p = &all_ipa_passes;
 320   NEXT_PASS (pass_ipa_inline);
 321   *p = NULL;
 322
 323   p = &all_passes;
 324   NEXT_PASS (pass_remove_useless_stmts);
 325   NEXT_PASS (pass_mudflap_1);
 326   NEXT_PASS (pass_lower_cf);
 327   NEXT_PASS (pass_lower_eh);
 328   NEXT_PASS (pass_build_cfg);
 329   NEXT_PASS (pass_pre_expand);
 330   NEXT_PASS (pass_warn_function_return);
 331   NEXT_PASS (pass_tree_profile);
 332   NEXT_PASS (pass_init_datastructures);
 333   NEXT_PASS (pass_all_optimizations);
 334   NEXT_PASS (pass_warn_function_noreturn);
 335   NEXT_PASS (pass_mudflap_2);
 336   NEXT_PASS (pass_free_datastructures);
 337   NEXT_PASS (pass_expand);
 338   NEXT_PASS (pass_rest_of_compilation);
 339   *p = NULL;
 340
 341   p = &pass_all_optimizations.sub;
 342   NEXT_PASS (pass_referenced_vars);
 343   NEXT_PASS (pass_create_structure_vars);
 344   NEXT_PASS (pass_build_ssa);
 345   NEXT_PASS (pass_may_alias);
 346   NEXT_PASS (pass_rename_ssa_copies);
 347   NEXT_PASS (pass_early_warn_uninitialized);
 348
 349   /* Initial scalar cleanups.  */
 350   NEXT_PASS (pass_ccp);
 351   NEXT_PASS (pass_fre);
 352   NEXT_PASS (pass_dce);
 353   NEXT_PASS (pass_forwprop);
 354   NEXT_PASS (pass_vrp);
 355   NEXT_PASS (pass_copy_prop);
 356   NEXT_PASS (pass_dce);
 357   NEXT_PASS (pass_merge_phi);
 358   NEXT_PASS (pass_dominator);
 359
 360   NEXT_PASS (pass_phiopt);
 361   NEXT_PASS (pass_may_alias);
 362   NEXT_PASS (pass_tail_recursion);
 363   NEXT_PASS (pass_profile);
 364   NEXT_PASS (pass_ch);
 365   NEXT_PASS (pass_stdarg);
 366   NEXT_PASS (pass_sra);
 367   /* FIXME: SRA may generate arbitrary gimple code, exposing new
 368      aliased and call-clobbered variables.  As mentioned below,
 369      pass_may_alias should be a TODO item.  */
 370   NEXT_PASS (pass_may_alias);
 371   NEXT_PASS (pass_rename_ssa_copies);
 372   NEXT_PASS (pass_dominator);
 373   NEXT_PASS (pass_copy_prop);
 374   NEXT_PASS (pass_dce);
 375   NEXT_PASS (pass_dse);
 376   NEXT_PASS (pass_may_alias);
 377   NEXT_PASS (pass_forwprop);
 378   NEXT_PASS (pass_phiopt);
 379   NEXT_PASS (pass_store_ccp);
 380   NEXT_PASS (pass_store_copy_prop);
 381   NEXT_PASS (pass_fold_builtins);
 382   /* FIXME: May alias should a TODO but for 4.0.0,
 383      we add may_alias right after fold builtins
 384      which can create arbitrary GIMPLE.  */
 385   NEXT_PASS (pass_may_alias);
 386   NEXT_PASS (pass_cse_reciprocals);
 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_copy_prop);
 393   NEXT_PASS (pass_cd_dce);
 394   /* FIXME: If DCE is not run before checking for uninitialized uses,
 395      we may get false warnings (e.g., testsuite/gcc.dg/uninit-5.c).
 396      However, this also causes us to misdiagnose cases that should be
 397      real warnings (e.g., testsuite/gcc.dg/pr18501.c).
 398
 399      To fix the false positives in uninit-5.c, we would have to
 400      account for the predicates protecting the set and the use of each
 401      variable.  Using a representation like Gated Single Assignment
 402      may help.  */
 403   NEXT_PASS (pass_late_warn_uninitialized);
 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_uncprop);
 410   NEXT_PASS (pass_del_ssa);
 411   NEXT_PASS (pass_nrv);
 412   NEXT_PASS (pass_remove_useless_vars);
 413   NEXT_PASS (pass_mark_used_blocks);
 414   NEXT_PASS (pass_cleanup_cfg_post_optimizing);
 415   *p = NULL;
 416
 417   p = &pass_loop.sub;
 418   NEXT_PASS (pass_loop_init);
 419   NEXT_PASS (pass_copy_prop);
 420   NEXT_PASS (pass_lim);
 421   NEXT_PASS (pass_unswitch);
 422   NEXT_PASS (pass_record_bounds);
 423   NEXT_PASS (pass_linear_transform);
 424   NEXT_PASS (pass_iv_canon);
 425   NEXT_PASS (pass_if_conversion);
 426   NEXT_PASS (pass_vectorize);
 427   NEXT_PASS (pass_lower_vector_ssa);
 428   NEXT_PASS (pass_complete_unroll);
 429   NEXT_PASS (pass_iv_optimize);
 430   NEXT_PASS (pass_loop_done);
 431   *p = NULL;
 432
 433 #undef NEXT_PASS
 434
 435   register_dump_files (all_passes, false, PROP_gimple_any
 436                                           | PROP_gimple_lcf
 437                                           | PROP_gimple_leh
 438                                           | PROP_cfg);
 439   register_dump_files (all_ipa_passes, true, PROP_gimple_any
 440                                              | PROP_gimple_lcf
 441                                              | PROP_gimple_leh
 442                                              | PROP_cfg);
 443 }
 444
 445 static unsigned int last_verified;
 446
 447 static void
 448 execute_todo (struct tree_opt_pass *pass, unsigned int flags, bool use_required)
 449 {
 450   int properties
 451     = use_required ? pass->properties_required : pass->properties_provided;
 452
 453 #if defined ENABLE_CHECKING
 454   if (need_ssa_update_p ())
 455     gcc_assert (flags & TODO_update_ssa_any);
 456 #endif
 457
 458   if (flags & TODO_update_ssa_any)
 459     {
 460       unsigned update_flags = flags & TODO_update_ssa_any;
 461       update_ssa (update_flags);
 462     }
 463
 464   if (flags & TODO_cleanup_cfg)
 465     {
 466       if (current_loops)
 467         cleanup_tree_cfg_loop ();
 468       else
 469         cleanup_tree_cfg ();
 470     }
 471
 472   if ((flags & TODO_dump_func)
 473       && dump_file && current_function_decl)
 474     {
 475       if (properties & PROP_trees)
 476         dump_function_to_file (current_function_decl,
 477                                dump_file, dump_flags);
 478       else if (properties & PROP_cfg)
 479         print_rtl_with_bb (dump_file, get_insns ());
 480       else
 481         print_rtl (dump_file, get_insns ());
 482
 483       /* Flush the file.  If verification fails, we won't be able to
 484          close the file before dieing.  */
 485       fflush (dump_file);
 486     }
 487   if ((flags & TODO_dump_cgraph)
 488       && dump_file && !current_function_decl)
 489     {
 490       dump_cgraph (dump_file);
 491       /* Flush the file.  If verification fails, we won't be able to
 492          close the file before aborting.  */
 493       fflush (dump_file);
 494     }
 495
 496   if (flags & TODO_ggc_collect)
 497     {
 498       ggc_collect ();
 499     }
 500
 501 #if defined ENABLE_CHECKING
 502   if ((pass->properties_required & PROP_ssa)
 503       && !(pass->properties_destroyed & PROP_ssa))
 504     verify_ssa (true);
 505   if (flags & TODO_verify_flow)
 506     verify_flow_info ();
 507   if (flags & TODO_verify_stmts)
 508     verify_stmts ();
 509   if (flags & TODO_verify_loops)
 510     verify_loop_closed_ssa ();
 511 #endif
 512 }
 513
 514 static bool
 515 execute_one_pass (struct tree_opt_pass *pass)
 516 {
 517   unsigned int todo;
 518
 519   /* See if we're supposed to run this pass.  */
 520   if (pass->gate && !pass->gate ())
 521     return false;
 522
 523   /* Note that the folders should only create gimple expressions.
 524      This is a hack until the new folder is ready.  */
 525   in_gimple_form = (pass->properties_provided & PROP_trees) != 0;
 526
 527   /* Run pre-pass verification.  */
 528   todo = pass->todo_flags_start & ~last_verified;
 529   if (todo)
 530     execute_todo (pass, todo, true);
 531
 532   /* If a dump file name is present, open it if enabled.  */
 533   if (pass->static_pass_number != -1)
 534     {
 535       bool initializing_dump = !dump_initialized_p (pass->static_pass_number);
 536       dump_file_name = get_dump_file_name (pass->static_pass_number);
 537       dump_file = dump_begin (pass->static_pass_number, &dump_flags);
 538       if (dump_file && current_function_decl)
 539         {
 540           const char *dname, *aname;
 541           dname = lang_hooks.decl_printable_name (current_function_decl, 2);
 542           aname = (IDENTIFIER_POINTER
 543                    (DECL_ASSEMBLER_NAME (current_function_decl)));
 544           fprintf (dump_file, "\n;; Function %s (%s)%s\n\n", dname, aname,
 545              cfun->function_frequency == FUNCTION_FREQUENCY_HOT
 546              ? " (hot)"
 547              : cfun->function_frequency == FUNCTION_FREQUENCY_UNLIKELY_EXECUTED
 548              ? " (unlikely executed)"
 549              : "");
 550         }
 551
 552       if (initializing_dump
 553           && graph_dump_format != no_graph
 554           && (pass->properties_provided & (PROP_cfg | PROP_rtl))
 555               == (PROP_cfg | PROP_rtl))
 556         clean_graph_dump_file (dump_file_name);
 557     }
 558
 559   /* If a timevar is present, start it.  */
 560   if (pass->tv_id)
 561     timevar_push (pass->tv_id);
 562
 563   /* Do it!  */
 564   if (pass->execute)
 565     pass->execute ();
 566
 567   /* Stop timevar.  */
 568   if (pass->tv_id)
 569     timevar_pop (pass->tv_id);
 570
 571   if (dump_file
 572       && (pass->properties_provided & (PROP_cfg | PROP_rtl))
 573           == (PROP_cfg | PROP_rtl))
 574     print_rtl_with_bb (dump_file, get_insns ());
 575
 576   /* Run post-pass cleanup and verification.  */
 577   todo = pass->todo_flags_finish;
 578   last_verified = todo & TODO_verify_all;
 579   if (todo)
 580     execute_todo (pass, todo, false);
 581
 582   /* Flush and close dump file.  */
 583   if (dump_file_name)
 584     {
 585       free ((char *) dump_file_name);
 586       dump_file_name = NULL;
 587     }
 588   if (dump_file)
 589     {
 590       dump_end (pass->static_pass_number, dump_file);
 591       dump_file = NULL;
 592     }
 593
 594   return true;
 595 }
 596
 597 static void
 598 execute_pass_list (struct tree_opt_pass *pass)
 599 {
 600   do
 601     {
 602       if (execute_one_pass (pass) && pass->sub)
 603         execute_pass_list (pass->sub);
 604       pass = pass->next;
 605     }
 606   while (pass);
 607 }
 608
 609 /* Execute all IPA passes.  */
 610 void
 611 ipa_passes (void)
 612 {
 613    execute_pass_list (all_ipa_passes);
 614 }
 615 \f
 616
 617 /* Update recursively all inlined_to pointers of functions
 618    inlined into NODE to INLINED_TO.  */
 619 static void
 620 update_inlined_to_pointers (struct cgraph_node *node,
 621                             struct cgraph_node *inlined_to)
 622 {
 623   struct cgraph_edge *e;
 624   for (e = node->callees; e; e = e->next_callee)
 625     {
 626       if (e->callee->global.inlined_to)
 627         {
 628           e->callee->global.inlined_to = inlined_to;
 629           update_inlined_to_pointers (e->callee, inlined_to);
 630         }
 631     }
 632 }
 633
 634 \f
 635 /* For functions-as-trees languages, this performs all optimization and
 636    compilation for FNDECL.  */
 637
 638 void
 639 tree_rest_of_compilation (tree fndecl)
 640 {
 641   location_t saved_loc;
 642   struct cgraph_node *saved_node = NULL, *node;
 643
 644   timevar_push (TV_EXPAND);
 645
 646   gcc_assert (!flag_unit_at_a_time || cgraph_global_info_ready);
 647
 648   /* Initialize the RTL code for the function.  */
 649   current_function_decl = fndecl;
 650   saved_loc = input_location;
 651   input_location = DECL_SOURCE_LOCATION (fndecl);
 652   init_function_start (fndecl);
 653
 654   /* Even though we're inside a function body, we still don't want to
 655      call expand_expr to calculate the size of a variable-sized array.
 656      We haven't necessarily assigned RTL to all variables yet, so it's
 657      not safe to try to expand expressions involving them.  */
 658   cfun->x_dont_save_pending_sizes_p = 1;
 659   cfun->after_inlining = true;
 660
 661   node = cgraph_node (fndecl);
 662
 663   /* We might need the body of this function so that we can expand
 664      it inline somewhere else.  This means not lowering some constructs
 665      such as exception handling.  */
 666   if (cgraph_preserve_function_body_p (fndecl))
 667     {
 668       if (!flag_unit_at_a_time)
 669         {
 670           struct cgraph_edge *e;
 671
 672           saved_node = cgraph_clone_node (node);
 673           for (e = saved_node->callees; e; e = e->next_callee)
 674             if (!e->inline_failed)
 675               cgraph_clone_inlined_nodes (e, true);
 676         }
 677       cfun->saved_static_chain_decl = cfun->static_chain_decl;
 678       cfun->saved_tree = save_body (fndecl, &cfun->saved_args,
 679                                     &cfun->saved_static_chain_decl);
 680     }
 681
 682   if (flag_inline_trees)
 683     {
 684       struct cgraph_edge *e;
 685       for (e = node->callees; e; e = e->next_callee)
 686         if (!e->inline_failed || warn_inline)
 687           break;
 688       if (e)
 689         {
 690           timevar_push (TV_INTEGRATION);
 691           optimize_inline_calls (fndecl);
 692           timevar_pop (TV_INTEGRATION);
 693         }
 694     }
 695   /* We are not going to maintain the cgraph edges up to date.
 696      Kill it so it won't confuse us.  */
 697   while (node->callees)
 698     {
 699       /* In non-unit-at-a-time we must mark all referenced functions as needed.
 700          */
 701       if (node->callees->callee->analyzed && !flag_unit_at_a_time)
 702         cgraph_mark_needed_node (node->callees->callee);
 703       cgraph_remove_edge (node->callees);
 704     }
 705
 706   /* We are not going to maintain the cgraph edges up to date.
 707      Kill it so it won't confuse us.  */
 708   cgraph_node_remove_callees (node);
 709
 710
 711   /* Initialize the default bitmap obstack.  */
 712   bitmap_obstack_initialize (NULL);
 713   bitmap_obstack_initialize (&reg_obstack); /* FIXME, only at RTL generation*/
 714
 715   /* Perform all tree transforms and optimizations.  */
 716   execute_pass_list (all_passes);
 717
 718   bitmap_obstack_release (&reg_obstack);
 719
 720   /* Release the default bitmap obstack.  */
 721   bitmap_obstack_release (NULL);
 722
 723   /* Restore original body if still needed.  */
 724   if (cfun->saved_tree)
 725     {
 726       DECL_SAVED_TREE (fndecl) = cfun->saved_tree;
 727       DECL_ARGUMENTS (fndecl) = cfun->saved_args;
 728       cfun->static_chain_decl = cfun->saved_static_chain_decl;
 729
 730       /* When not in unit-at-a-time mode, we must preserve out of line copy
 731          representing node before inlining.  Restore original outgoing edges
 732          using clone we created earlier.  */
 733       if (!flag_unit_at_a_time)
 734         {
 735           struct cgraph_edge *e;
 736
 737           cgraph_node_remove_callees (node);
 738           node->callees = saved_node->callees;
 739           saved_node->callees = NULL;
 740           update_inlined_to_pointers (node, node);
 741           for (e = node->callees; e; e = e->next_callee)
 742             e->caller = node;
 743           cgraph_remove_node (saved_node);
 744         }
 745     }
 746   else
 747     DECL_SAVED_TREE (fndecl) = NULL;
 748   cfun = 0;
 749
 750   /* If requested, warn about function definitions where the function will
 751      return a value (usually of some struct or union type) which itself will
 752      take up a lot of stack space.  */
 753   if (warn_larger_than && !DECL_EXTERNAL (fndecl) && TREE_TYPE (fndecl))
 754     {
 755       tree ret_type = TREE_TYPE (TREE_TYPE (fndecl));
 756
 757       if (ret_type && TYPE_SIZE_UNIT (ret_type)
 758           && TREE_CODE (TYPE_SIZE_UNIT (ret_type)) == INTEGER_CST
 759           && 0 < compare_tree_int (TYPE_SIZE_UNIT (ret_type),
 760                                    larger_than_size))
 761         {
 762           unsigned int size_as_int
 763             = TREE_INT_CST_LOW (TYPE_SIZE_UNIT (ret_type));
 764
 765           if (compare_tree_int (TYPE_SIZE_UNIT (ret_type), size_as_int) == 0)
 766             warning (0, "%Jsize of return value of %qD is %u bytes",
 767                      fndecl, fndecl, size_as_int);
 768           else
 769             warning (0, "%Jsize of return value of %qD is larger than %wd bytes",
 770                      fndecl, fndecl, larger_than_size);
 771         }
 772     }
 773
 774   if (!flag_inline_trees)
 775     {
 776       DECL_SAVED_TREE (fndecl) = NULL;
 777       if (DECL_STRUCT_FUNCTION (fndecl) == 0
 778           && !cgraph_node (fndecl)->origin)
 779         {
 780           /* Stop pointing to the local nodes about to be freed.
 781              But DECL_INITIAL must remain nonzero so we know this
 782              was an actual function definition.
 783              For a nested function, this is done in c_pop_function_context.
 784              If rest_of_compilation set this to 0, leave it 0.  */
 785           if (DECL_INITIAL (fndecl) != 0)
 786             DECL_INITIAL (fndecl) = error_mark_node;
 787         }
 788     }
 789
 790   input_location = saved_loc;
 791
 792   ggc_collect ();
 793   timevar_pop (TV_EXPAND);
 794 }