gcc/loop-init.c

   1 /* Loop optimizer initialization routines.
   2    Copyright (C) 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
   3
   4 This file is part of GCC.
   5
   6 GCC is free software; you can redistribute it and/or modify it under
   7 the terms of the GNU General Public License as published by the Free
   8 Software Foundation; either version 2, or (at your option) any later
   9 version.
  10
  11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14 for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GCC; see the file COPYING.  If not, write to the Free
  18 Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
  19 02110-1301, USA.  */
  20
  21 #include "config.h"
  22 #include "system.h"
  23 #include "coretypes.h"
  24 #include "tm.h"
  25 #include "rtl.h"
  26 #include "hard-reg-set.h"
  27 #include "obstack.h"
  28 #include "basic-block.h"
  29 #include "cfgloop.h"
  30 #include "cfglayout.h"
  31 #include "tree-pass.h"
  32 #include "timevar.h"
  33 #include "flags.h"
  34
  35 /* Initialize loop optimizer.  */
  36
  37 struct loops *
  38 loop_optimizer_init (FILE *dumpfile)
  39 {
  40   struct loops *loops = xcalloc (1, sizeof (struct loops));
  41   edge e;
  42   edge_iterator ei;
  43   static bool first_time = true;
  44
  45   if (first_time)
  46     {
  47       first_time = false;
  48       init_set_costs ();
  49     }
  50
  51   /* Avoid annoying special cases of edges going to exit
  52      block.  */
  53
  54   for (ei = ei_start (EXIT_BLOCK_PTR->preds); (e = ei_safe_edge (ei)); )
  55     if ((e->flags & EDGE_FALLTHRU) && !single_succ_p (e->src))
  56       split_edge (e);
  57     else
  58       ei_next (&ei);
  59
  60   /* Find the loops.  */
  61
  62   if (flow_loops_find (loops) <= 1)
  63     {
  64       /* No loops.  */
  65       flow_loops_free (loops);
  66       free (loops);
  67
  68       return NULL;
  69     }
  70
  71   /* Not going to update these.  */
  72   free (loops->cfg.rc_order);
  73   loops->cfg.rc_order = NULL;
  74   free (loops->cfg.dfs_order);
  75   loops->cfg.dfs_order = NULL;
  76
  77   /* Create pre-headers.  */
  78   create_preheaders (loops, CP_SIMPLE_PREHEADERS);
  79
  80   /* Force all latches to have only single successor.  */
  81   force_single_succ_latches (loops);
  82
  83   /* Mark irreducible loops.  */
  84   mark_irreducible_loops (loops);
  85
  86   /* Dump loops.  */
  87   flow_loops_dump (loops, dumpfile, NULL, 1);
  88
  89 #ifdef ENABLE_CHECKING
  90   verify_dominators (CDI_DOMINATORS);
  91   verify_loop_structure (loops);
  92 #endif
  93
  94   return loops;
  95 }
  96
  97 /* Finalize loop optimizer.  */
  98 void
  99 loop_optimizer_finalize (struct loops *loops, FILE *dumpfile)
 100 {
 101   unsigned i;
 102
 103   if (!loops)
 104     return;
 105
 106   for (i = 1; i < loops->num; i++)
 107     if (loops->parray[i])
 108       free_simple_loop_desc (loops->parray[i]);
 109
 110   /* Another dump.  */
 111   flow_loops_dump (loops, dumpfile, NULL, 1);
 112
 113   /* Clean up.  */
 114   flow_loops_free (loops);
 115   free (loops);
 116
 117   /* Checking.  */
 118 #ifdef ENABLE_CHECKING
 119   verify_flow_info ();
 120 #endif
 121 }
 122 \f
 123 static bool
 124 gate_handle_loop2 (void)
 125 {
 126   return (optimize > 0 && flag_loop_optimize2
 127           && (flag_move_loop_invariants
 128               || flag_unswitch_loops
 129               || flag_peel_loops
 130               || flag_unroll_loops
 131               || flag_branch_on_count_reg));
 132 }
 133
 134 /* Perform loop optimizations.  It might be better to do them a bit
 135    sooner, but we want the profile feedback to work more
 136    efficiently.  */
 137 static void
 138 rest_of_handle_loop2 (void)
 139 {
 140   struct loops *loops;
 141   basic_block bb;
 142
 143   if (dump_file)
 144     dump_flow_info (dump_file);
 145
 146   /* Initialize structures for layout changes.  */
 147   cfg_layout_initialize (0);
 148
 149   loops = loop_optimizer_init (dump_file);
 150
 151   if (loops)
 152     {
 153       /* The optimizations:  */
 154       if (flag_move_loop_invariants)
 155         move_loop_invariants (loops);
 156
 157       if (flag_unswitch_loops)
 158         unswitch_loops (loops);
 159
 160       if (flag_peel_loops || flag_unroll_loops)
 161         unroll_and_peel_loops (loops,
 162                                (flag_peel_loops ? UAP_PEEL : 0) |
 163                                (flag_unroll_loops ? UAP_UNROLL : 0) |
 164                                (flag_unroll_all_loops ? UAP_UNROLL_ALL : 0));
 165
 166 #ifdef HAVE_doloop_end
 167       if (flag_branch_on_count_reg && HAVE_doloop_end)
 168         doloop_optimize_loops (loops);
 169 #endif /* HAVE_doloop_end */
 170
 171       loop_optimizer_finalize (loops, dump_file);
 172     }
 173
 174   free_dominance_info (CDI_DOMINATORS);
 175
 176   /* Finalize layout changes.  */
 177   FOR_EACH_BB (bb)
 178     if (bb->next_bb != EXIT_BLOCK_PTR)
 179       bb->aux = bb->next_bb;
 180   cfg_layout_finalize ();
 181
 182   cleanup_cfg (CLEANUP_EXPENSIVE);
 183   delete_trivially_dead_insns (get_insns (), max_reg_num ());
 184   reg_scan (get_insns (), max_reg_num ());
 185   if (dump_file)
 186     dump_flow_info (dump_file);
 187 }
 188
 189 struct tree_opt_pass pass_loop2 =
 190 {
 191   "loop2",                              /* name */
 192   gate_handle_loop2,                    /* gate */
 193   rest_of_handle_loop2,                 /* execute */
 194   NULL,                                 /* sub */
 195   NULL,                                 /* next */
 196   0,                                    /* static_pass_number */
 197   TV_LOOP,                              /* tv_id */
 198   0,                                    /* properties_required */
 199   0,                                    /* properties_provided */
 200   0,                                    /* properties_destroyed */
 201   0,                                    /* todo_flags_start */
 202   TODO_dump_func |
 203   TODO_ggc_collect,                     /* todo_flags_finish */
 204   'L'                                   /* letter */
 205 };
 206