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 (dumpfile)
  35      FILE *dumpfile;
  36 {
  37   struct loops *loops = xcalloc (1, sizeof (struct loops));
  38   edge e;
  39
  40   /* Initialize structures for layout changes.  */
  41   cfg_layout_initialize ();
  42
  43   /* Avoid annoying special cases of edges going to exit
  44      block.  */
  45   for (e = EXIT_BLOCK_PTR->pred; e; e = e->pred_next)
  46     if ((e->flags & EDGE_FALLTHRU) && e->src->succ->succ_next)
  47       split_edge (e);
  48
  49   /* Find the loops.  */
  50
  51   if (flow_loops_find (loops, LOOP_TREE) <= 1)
  52     {
  53       basic_block bb;
  54
  55       /* No loops.  */
  56       flow_loops_free (loops);
  57       free (loops);
  58       /* Make chain.  */
  59       FOR_EACH_BB (bb)
  60         if (bb->next_bb != EXIT_BLOCK_PTR)
  61           bb->rbi->next = bb->next_bb;
  62           cfg_layout_finalize ();
  63       return NULL;
  64     }
  65
  66   /* Not going to update these.  */
  67   free (loops->cfg.rc_order);
  68   loops->cfg.rc_order = NULL;
  69   free (loops->cfg.dfs_order);
  70   loops->cfg.dfs_order = NULL;
  71
  72   /* Create pre-headers.  */
  73   create_preheaders (loops, CP_SIMPLE_PREHEADERS);
  74
  75   /* Force all latches to have only single successor.  */
  76   force_single_succ_latches (loops);
  77
  78   /* Mark irreducible loops.  */
  79   mark_irreducible_loops (loops);
  80
  81   /* Dump loops.  */
  82   flow_loops_dump (loops, dumpfile, NULL, 1);
  83
  84 #ifdef ENABLE_CHECKING
  85   verify_dominators (loops->cfg.dom);
  86   verify_loop_structure (loops);
  87 #endif
  88
  89   return loops;
  90 }
  91
  92 /* Finalize loop optimizer.  */
  93 void
  94 loop_optimizer_finalize (loops, dumpfile)
  95      struct loops *loops;
  96      FILE *dumpfile;
  97 {
  98   basic_block bb;
  99
 100   /* Finalize layout changes.  */
 101   /* Make chain.  */
 102   FOR_EACH_BB (bb)
 103     if (bb->next_bb != EXIT_BLOCK_PTR)
 104       bb->rbi->next = bb->next_bb;
 105
 106   /* Another dump.  */
 107   flow_loops_dump (loops, dumpfile, NULL, 1);
 108
 109   /* Clean up.  */
 110   flow_loops_free (loops);
 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 }
 121