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   /* Avoid annoying special cases of edges going to exit
  41      block.  */
  42   for (e = EXIT_BLOCK_PTR->pred; e; e = e->pred_next)
  43     if ((e->flags & EDGE_FALLTHRU) && e->src->succ->succ_next)
  44       split_edge (e);
  45
  46   /* Find the loops.  */
  47
  48   if (flow_loops_find (loops, LOOP_TREE) <= 1)
  49     {
  50       /* No loops.  */
  51       flow_loops_free (loops);
  52       free (loops);
  53       return NULL;
  54     }
  55
  56   /* Not going to update these.  */
  57   free (loops->cfg.rc_order);
  58   loops->cfg.rc_order = NULL;
  59   free (loops->cfg.dfs_order);
  60   loops->cfg.dfs_order = NULL;
  61
  62   /* Initialize structures for layout changes.  */
  63   cfg_layout_initialize (loops);
  64
  65   /* Create pre-headers.  */
  66   create_preheaders (loops, CP_SIMPLE_PREHEADERS | CP_INSIDE_CFGLAYOUT);
  67
  68   /* Force all latches to have only single successor.  */
  69   force_single_succ_latches (loops);
  70
  71   /* Mark irreducible loops.  */
  72   mark_irreducible_loops (loops);
  73
  74   /* Dump loops.  */
  75   flow_loops_dump (loops, dumpfile, NULL, 1);
  76
  77 #ifdef ENABLE_CHECKING
  78   verify_dominators (loops->cfg.dom);
  79   verify_loop_structure (loops);
  80 #endif
  81
  82   return loops;
  83 }
  84
  85 /* Finalize loop optimizer.  */
  86 void
  87 loop_optimizer_finalize (loops, dumpfile)
  88      struct loops *loops;
  89      FILE *dumpfile;
  90 {
  91   basic_block bb;
  92
  93   /* Finalize layout changes.  */
  94   /* Make chain.  */
  95   FOR_EACH_BB (bb)
  96     if (bb->next_bb != EXIT_BLOCK_PTR)
  97       RBI (bb)->next = bb->next_bb;
  98
  99   /* Another dump.  */
 100   flow_loops_dump (loops, dumpfile, NULL, 1);
 101
 102   /* Clean up.  */
 103   flow_loops_free (loops);
 104   free (loops);
 105
 106   /* Finalize changes.  */
 107   cfg_layout_finalize ();
 108
 109   /* Checking.  */
 110 #ifdef ENABLE_CHECKING
 111   verify_flow_info ();
 112 #endif
 113 }
 114