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 #include "gcov-io.h"
  31 #include "profile.h"
  32
  33 /* Initialize loop optimizer.  */
  34
  35 struct loops *
  36 loop_optimizer_init (dumpfile)
  37      FILE *dumpfile;
  38 {
  39   struct loops *loops = xcalloc (1, sizeof (struct loops));
  40   edge e;
  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       /* No loops.  */
  53       flow_loops_free (loops);
  54       free (loops);
  55       return NULL;
  56     }
  57
  58   /* Not going to update these.  */
  59   free (loops->cfg.rc_order);
  60   loops->cfg.rc_order = NULL;
  61   free (loops->cfg.dfs_order);
  62   loops->cfg.dfs_order = NULL;
  63
  64   /* Initialize structures for layout changes.  */
  65   cfg_layout_initialize (loops);
  66
  67   /* Create pre-headers.  */
  68   create_preheaders (loops, CP_SIMPLE_PREHEADERS | CP_INSIDE_CFGLAYOUT);
  69
  70   /* Force all latches to have only single successor.  */
  71   force_single_succ_latches (loops);
  72
  73   /* Mark irreducible loops.  */
  74   mark_irreducible_loops (loops);
  75
  76   /* Dump loops.  */
  77   flow_loops_dump (loops, dumpfile, NULL, 1);
  78
  79 #ifdef ENABLE_CHECKING
  80   verify_dominators (loops->cfg.dom);
  81   verify_loop_structure (loops);
  82 #endif
  83
  84   return loops;
  85 }
  86
  87 /* Finalize loop optimizer.  */
  88 void
  89 loop_optimizer_finalize (loops, dumpfile)
  90      struct loops *loops;
  91      FILE *dumpfile;
  92 {
  93   basic_block bb;
  94
  95   /* Finalize layout changes.  */
  96   /* Make chain.  */
  97   FOR_EACH_BB (bb)
  98     if (bb->next_bb != EXIT_BLOCK_PTR)
  99       RBI (bb)->next = bb->next_bb;
 100
 101   /* Another dump.  */
 102   flow_loops_dump (loops, dumpfile, NULL, 1);
 103
 104   /* Clean up.  */
 105   flow_loops_free (loops);
 106   free (loops);
 107
 108   /* Finalize changes.  */
 109   cfg_layout_finalize ();
 110
 111   /* Checking.  */
 112 #ifdef ENABLE_CHECKING
 113   verify_flow_info ();
 114 #endif
 115 }
 116