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 "obstack.h"
  28 #include "basic-block.h"
  29 #include "cfgloop.h"
  30 #include "cfglayout.h"
  31
  32 /* Initialize loop optimizer.  */
  33
  34 struct loops *
  35 loop_optimizer_init (FILE *dumpfile)
  36 {
  37   struct loops *loops = xcalloc (1, sizeof (struct loops));
  38   edge e;
  39   edge_iterator ei;
  40   static bool first_time = true;
  41
  42   if (first_time)
  43     {
  44       first_time = false;
  45       init_set_costs ();
  46     }
  47
  48   /* Avoid annoying special cases of edges going to exit
  49      block.  */
  50
  51   for (ei = ei_start (EXIT_BLOCK_PTR->preds); (e = ei_safe_edge (ei)); )
  52     if ((e->flags & EDGE_FALLTHRU) && EDGE_COUNT (e->src->succs) > 1)
  53       split_edge (e);
  54     else
  55       ei_next (&ei);
  56
  57   /* Find the loops.  */
  58
  59   if (flow_loops_find (loops, LOOP_TREE) <= 1)
  60     {
  61       /* No loops.  */
  62       flow_loops_free (loops);
  63       free (loops);
  64
  65       return NULL;
  66     }
  67
  68   /* Not going to update these.  */
  69   free (loops->cfg.rc_order);
  70   loops->cfg.rc_order = NULL;
  71   free (loops->cfg.dfs_order);
  72   loops->cfg.dfs_order = NULL;
  73
  74   /* Create pre-headers.  */
  75   create_preheaders (loops, CP_SIMPLE_PREHEADERS);
  76
  77   /* Force all latches to have only single successor.  */
  78   force_single_succ_latches (loops);
  79
  80   /* Mark irreducible loops.  */
  81   mark_irreducible_loops (loops);
  82
  83   /* Dump loops.  */
  84   flow_loops_dump (loops, dumpfile, NULL, 1);
  85
  86 #ifdef ENABLE_CHECKING
  87   verify_dominators (CDI_DOMINATORS);
  88   verify_loop_structure (loops);
  89 #endif
  90
  91   return loops;
  92 }
  93
  94 /* Finalize loop optimizer.  */
  95 void
  96 loop_optimizer_finalize (struct loops *loops, FILE *dumpfile)
  97 {
  98   unsigned i;
  99
 100   if (!loops)
 101     return;
 102
 103   for (i = 1; i < loops->num; i++)
 104     if (loops->parray[i])
 105       free_simple_loop_desc (loops->parray[i]);
 106
 107   /* Another dump.  */
 108   flow_loops_dump (loops, dumpfile, NULL, 1);
 109
 110   /* Clean up.  */
 111   flow_loops_free (loops);
 112   free (loops);
 113
 114   /* Checking.  */
 115 #ifdef ENABLE_CHECKING
 116   verify_flow_info ();
 117 #endif
 118 }