gcc/tree-optimize.c

   1 /* Top-level control of tree optimizations.
   2    Copyright 2001, 2002, 2003, 2004, 2005, 2007, 2008, 2009, 2010
   3    Free Software Foundation, Inc.
   4    Contributed by Diego Novillo <dnovillo@redhat.com>
   5
   6 This file is part of GCC.
   7
   8 GCC is free software; you can redistribute it and/or modify
   9 it under the terms of the GNU General Public License as published by
  10 the Free Software Foundation; either version 3, or (at your option)
  11 any later version.
  12
  13 GCC is distributed in the hope that it will be useful,
  14 but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 GNU General Public License for more details.
  17
  18 You should have received a copy of the GNU General Public License
  19 along with GCC; see the file COPYING3.  If not see
  20 <http://www.gnu.org/licenses/>.  */
  21
  22 #include "config.h"
  23 #include "system.h"
  24 #include "coretypes.h"
  25 #include "tm.h"
  26 #include "tree.h"
  27 #include "tm_p.h"
  28 #include "basic-block.h"
  29 #include "flags.h"
  30 #include "tree-flow.h"
  31 #include "function.h"
  32 #include "langhooks.h"
  33 #include "diagnostic-core.h"
  34 #include "toplev.h"
  35 #include "flags.h"
  36 #include "cgraph.h"
  37 #include "tree-inline.h"
  38 #include "tree-pass.h"
  39 #include "ggc.h"
  40 #include "cgraph.h"
  41 #include "graph.h"
  42 #include "cfgloop.h"
  43 #include "except.h"
  44 #include "plugin.h"
  45
  46
  47 /* Pass: cleanup the CFG just before expanding trees to RTL.
  48    This is just a round of label cleanups and case node grouping
  49    because after the tree optimizers have run such cleanups may
  50    be necessary.  */
  51
  52 static unsigned int
  53 execute_cleanup_cfg_post_optimizing (void)
  54 {
  55   unsigned int todo = 0;
  56   if (cleanup_tree_cfg ())
  57     todo |= TODO_update_ssa;
  58   maybe_remove_unreachable_handlers ();
  59   cleanup_dead_labels ();
  60   group_case_labels ();
  61   if ((flag_compare_debug_opt || flag_compare_debug)
  62       && flag_dump_final_insns)
  63     {
  64       FILE *final_output = fopen (flag_dump_final_insns, "a");
  65
  66       if (!final_output)
  67         {
  68           error ("could not open final insn dump file %qs: %m",
  69                  flag_dump_final_insns);
  70           flag_dump_final_insns = NULL;
  71         }
  72       else
  73         {
  74           int save_unnumbered = flag_dump_unnumbered;
  75           int save_noaddr = flag_dump_noaddr;
  76
  77           flag_dump_noaddr = flag_dump_unnumbered = 1;
  78           fprintf (final_output, "\n");
  79           dump_enumerated_decls (final_output, dump_flags | TDF_NOUID);
  80           flag_dump_noaddr = save_noaddr;
  81           flag_dump_unnumbered = save_unnumbered;
  82           if (fclose (final_output))
  83             {
  84               error ("could not close final insn dump file %qs: %m",
  85                      flag_dump_final_insns);
  86               flag_dump_final_insns = NULL;
  87             }
  88         }
  89     }
  90   return todo;
  91 }
  92
  93 struct gimple_opt_pass pass_cleanup_cfg_post_optimizing =
  94 {
  95  {
  96   GIMPLE_PASS,
  97   "optimized",                          /* name */
  98   OPTGROUP_NONE,                        /* optinfo_flags */
  99   NULL,                                 /* gate */
 100   execute_cleanup_cfg_post_optimizing,  /* execute */
 101   NULL,                                 /* sub */
 102   NULL,                                 /* next */
 103   0,                                    /* static_pass_number */
 104   TV_TREE_CLEANUP_CFG,                  /* tv_id */
 105   PROP_cfg,                             /* properties_required */
 106   0,                                    /* properties_provided */
 107   0,                                    /* properties_destroyed */
 108   0,                                    /* todo_flags_start */
 109   TODO_remove_unused_locals             /* todo_flags_finish */
 110  }
 111 };
 112
 113 /* IPA passes, compilation of earlier functions or inlining
 114    might have changed some properties, such as marked functions nothrow,
 115    pure, const or noreturn.
 116    Remove redundant edges and basic blocks, and create new ones if necessary.
 117
 118    This pass can't be executed as stand alone pass from pass manager, because
 119    in between inlining and this fixup the verify_flow_info would fail.  */
 120
 121 unsigned int
 122 execute_fixup_cfg (void)
 123 {
 124   basic_block bb;
 125   gimple_stmt_iterator gsi;
 126   int todo = gimple_in_ssa_p (cfun) ? TODO_verify_ssa : 0;
 127   gcov_type count_scale;
 128   edge e;
 129   edge_iterator ei;
 130
 131   if (ENTRY_BLOCK_PTR->count)
 132     count_scale = ((cgraph_get_node (current_function_decl)->count
 133                     * REG_BR_PROB_BASE + ENTRY_BLOCK_PTR->count / 2)
 134                    / ENTRY_BLOCK_PTR->count);
 135   else
 136     count_scale = REG_BR_PROB_BASE;
 137
 138   ENTRY_BLOCK_PTR->count = cgraph_get_node (current_function_decl)->count;
 139   EXIT_BLOCK_PTR->count = (EXIT_BLOCK_PTR->count * count_scale
 140                            + REG_BR_PROB_BASE / 2) / REG_BR_PROB_BASE;
 141
 142   FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
 143     e->count = (e->count * count_scale
 144        + REG_BR_PROB_BASE / 2) / REG_BR_PROB_BASE;
 145
 146   FOR_EACH_BB (bb)
 147     {
 148       bb->count = (bb->count * count_scale
 149                    + REG_BR_PROB_BASE / 2) / REG_BR_PROB_BASE;
 150       for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
 151         {
 152           gimple stmt = gsi_stmt (gsi);
 153           tree decl = is_gimple_call (stmt)
 154                       ? gimple_call_fndecl (stmt)
 155                       : NULL;
 156           if (decl)
 157             {
 158               int flags = gimple_call_flags (stmt);
 159               if (flags & (ECF_CONST | ECF_PURE | ECF_LOOPING_CONST_OR_PURE))
 160                 {
 161                   if (gimple_purge_dead_abnormal_call_edges (bb))
 162                     todo |= TODO_cleanup_cfg;
 163
 164                   if (gimple_in_ssa_p (cfun))
 165                     {
 166                       todo |= TODO_update_ssa | TODO_cleanup_cfg;
 167                       update_stmt (stmt);
 168                     }
 169                 }
 170
 171               if (flags & ECF_NORETURN
 172                   && fixup_noreturn_call (stmt))
 173                 todo |= TODO_cleanup_cfg;
 174              }
 175
 176           if (maybe_clean_eh_stmt (stmt)
 177               && gimple_purge_dead_eh_edges (bb))
 178             todo |= TODO_cleanup_cfg;
 179         }
 180
 181       FOR_EACH_EDGE (e, ei, bb->succs)
 182         e->count = (e->count * count_scale
 183                     + REG_BR_PROB_BASE / 2) / REG_BR_PROB_BASE;
 184
 185       /* If we have a basic block with no successors that does not
 186          end with a control statement or a noreturn call end it with
 187          a call to __builtin_unreachable.  This situation can occur
 188          when inlining a noreturn call that does in fact return.  */
 189       if (EDGE_COUNT (bb->succs) == 0)
 190         {
 191           gimple stmt = last_stmt (bb);
 192           if (!stmt
 193               || (!is_ctrl_stmt (stmt)
 194                   && (!is_gimple_call (stmt)
 195                       || (gimple_call_flags (stmt) & ECF_NORETURN) == 0)))
 196             {
 197               stmt = gimple_build_call
 198                   (builtin_decl_implicit (BUILT_IN_UNREACHABLE), 0);
 199               gimple_stmt_iterator gsi = gsi_last_bb (bb);
 200               gsi_insert_after (&gsi, stmt, GSI_NEW_STMT);
 201             }
 202         }
 203     }
 204   if (count_scale != REG_BR_PROB_BASE)
 205     compute_function_frequency ();
 206
 207   /* We just processed all calls.  */
 208   if (cfun->gimple_df)
 209     vec_free (MODIFIED_NORETURN_CALLS (cfun));
 210
 211   /* Dump a textual representation of the flowgraph.  */
 212   if (dump_file)
 213     gimple_dump_cfg (dump_file, dump_flags);
 214
 215   return todo;
 216 }
 217
 218 struct gimple_opt_pass pass_fixup_cfg =
 219 {
 220  {
 221   GIMPLE_PASS,
 222   "*free_cfg_annotations",              /* name */
 223   OPTGROUP_NONE,                        /* optinfo_flags */
 224   NULL,                                 /* gate */
 225   execute_fixup_cfg,                    /* execute */
 226   NULL,                                 /* sub */
 227   NULL,                                 /* next */
 228   0,                                    /* static_pass_number */
 229   TV_NONE,                              /* tv_id */
 230   PROP_cfg,                             /* properties_required */
 231   0,                                    /* properties_provided */
 232   0,                                    /* properties_destroyed */
 233   0,                                    /* todo_flags_start */
 234   0                                     /* todo_flags_finish */
 235  }
 236 };