gcc/loop-init.c

   1 /* Loop optimizer initialization routines.
   2    Copyright (C) 2002, 2003 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, 59 Temple Place - Suite 330, Boston, MA
  19 02111-1307, 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 "basic-block.h"
  28 #include "cfgloop.h"
  29 #include "cfglayout.h"
  30
  31 /* Initialize loop optimizer.  */
  32
  33 struct loops *
  34 loop_optimizer_init (FILE *dumpfile)
  35 {
  36   struct loops *loops = xcalloc (1, sizeof (struct loops));
  37   edge e;
  38
  39   /* Initialize structures for layout changes.  */
  40   cfg_layout_initialize ();
  41
  42   /* Avoid annoying special cases of edges going to exit
  43      block.  */
  44   for (e = EXIT_BLOCK_PTR->pred; e; e = e->pred_next)
  45     if ((e->flags & EDGE_FALLTHRU) && e->src->succ->succ_next)
  46       split_edge (e);
  47
  48   /* Find the loops.  */
  49
  50   if (flow_loops_find (loops, LOOP_TREE) <= 1)
  51     {
  52       basic_block bb;
  53
  54       /* No loops.  */
  55       flow_loops_free (loops);
  56       free_dominance_info (CDI_DOMINATORS);
  57       free (loops);
  58
  59       /* Make chain.  */
  60       FOR_EACH_BB (bb)
  61         if (bb->next_bb != EXIT_BLOCK_PTR)
  62           bb->rbi->next = bb->next_bb;
  63           cfg_layout_finalize ();
  64       return NULL;
  65     }
  66
  67   /* Not going to update these.  */
  68   free (loops->cfg.rc_order);
  69   loops->cfg.rc_order = NULL;
  70   free (loops->cfg.dfs_order);
  71   loops->cfg.dfs_order = NULL;
  72
  73   /* Create pre-headers.  */
  74   create_preheaders (loops, CP_SIMPLE_PREHEADERS);
  75
  76   /* Force all latches to have only single successor.  */
  77   force_single_succ_latches (loops);
  78
  79   /* Mark irreducible loops.  */
  80   mark_irreducible_loops (loops);
  81
  82   /* Dump loops.  */
  83   flow_loops_dump (loops, dumpfile, NULL, 1);
  84
  85 #ifdef ENABLE_CHECKING
  86   verify_dominators (CDI_DOMINATORS);
  87   verify_loop_structure (loops);
  88 #endif
  89
  90   return loops;
  91 }
  92
  93 /* Finalize loop optimizer.  */
  94 void
  95 loop_optimizer_finalize (struct loops *loops, FILE *dumpfile)
  96 {
  97   basic_block bb;
  98
  99   /* Finalize layout changes.  */
 100   /* Make chain.  */
 101   FOR_EACH_BB (bb)
 102     if (bb->next_bb != EXIT_BLOCK_PTR)
 103       bb->rbi->next = bb->next_bb;
 104
 105   /* Another dump.  */
 106   flow_loops_dump (loops, dumpfile, NULL, 1);
 107
 108   /* Clean up.  */
 109   flow_loops_free (loops);
 110   free_dominance_info (CDI_DOMINATORS);
 111   free (loops);
 112
 113   /* Finalize changes.  */
 114   cfg_layout_finalize ();
 115
 116   /* Checking.  */
 117 #ifdef ENABLE_CHECKING
 118   verify_flow_info ();
 119 #endif
 120 }