gcc/loop-init.c

   1 /* Loop optimizer initialization routines.
   2    Copyright (C) 2002, 2003, 2004 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   static bool first_time = true;
  39
  40   if (first_time)
  41     {
  42       first_time = false;
  43       init_set_costs ();
  44     }
  45
  46   /* Avoid annoying special cases of edges going to exit
  47      block.  */
  48   for (e = EXIT_BLOCK_PTR->pred; e; e = e->pred_next)
  49     if ((e->flags & EDGE_FALLTHRU) && e->src->succ->succ_next)
  50       split_edge (e);
  51
  52   /* Find the loops.  */
  53
  54   if (flow_loops_find (loops, LOOP_TREE) <= 1)
  55     {
  56       /* No loops.  */
  57       flow_loops_free (loops);
  58       free (loops);
  59
  60       return NULL;
  61     }
  62
  63   /* Not going to update these.  */
  64   free (loops->cfg.rc_order);
  65   loops->cfg.rc_order = NULL;
  66   free (loops->cfg.dfs_order);
  67   loops->cfg.dfs_order = NULL;
  68
  69   /* Create pre-headers.  */
  70   create_preheaders (loops, CP_SIMPLE_PREHEADERS);
  71
  72   /* Force all latches to have only single successor.  */
  73   force_single_succ_latches (loops);
  74
  75   /* Mark irreducible loops.  */
  76   mark_irreducible_loops (loops);
  77
  78   /* Dump loops.  */
  79   flow_loops_dump (loops, dumpfile, NULL, 1);
  80
  81 #ifdef ENABLE_CHECKING
  82   verify_dominators (CDI_DOMINATORS);
  83   verify_loop_structure (loops);
  84 #endif
  85
  86   return loops;
  87 }
  88
  89 /* Finalize loop optimizer.  */
  90 void
  91 loop_optimizer_finalize (struct loops *loops, FILE *dumpfile)
  92 {
  93   unsigned i;
  94
  95   if (!loops)
  96     return;
  97
  98   for (i = 1; i < loops->num; i++)
  99     if (loops->parray[i])
 100       free_simple_loop_desc (loops->parray[i]);
 101
 102   /* Another dump.  */
 103   flow_loops_dump (loops, dumpfile, NULL, 1);
 104
 105   /* Clean up.  */
 106   flow_loops_free (loops);
 107   free (loops);
 108
 109   /* Checking.  */
 110 #ifdef ENABLE_CHECKING
 111   verify_flow_info ();
 112 #endif
 113 }