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/* Loop optimizer initialization routines.
Copyright (C) 2002, 2003, 2004 Free Software Foundation, Inc.
This file is part of GCC.
GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 2, or (at your option) any later
version.
GCC is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
for more details.
You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING. If not, write to the Free
Software Foundation, 59 Temple Place - Suite 330, Boston, MA
02111-1307, USA. */
#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"
#include "rtl.h"
#include "hard-reg-set.h"
#include "basic-block.h"
#include "cfgloop.h"
#include "cfglayout.h"
static void fixup_loop_exit_succesor (basic_block, basic_block);
/* Initialize loop optimizer. */
struct loops *
loop_optimizer_init (FILE *dumpfile)
{
struct loops *loops = xcalloc (1, sizeof (struct loops));
edge e;
/* Initialize structures for layout changes. */
cfg_layout_initialize (0);
/* Avoid annoying special cases of edges going to exit
block. */
for (e = EXIT_BLOCK_PTR->pred; e; e = e->pred_next)
if ((e->flags & EDGE_FALLTHRU) && e->src->succ->succ_next)
split_edge (e);
/* Find the loops. */
if (flow_loops_find (loops, LOOP_TREE) <= 1)
{
basic_block bb;
/* No loops. */
flow_loops_free (loops);
free_dominance_info (CDI_DOMINATORS);
free (loops);
/* Make chain. */
FOR_EACH_BB (bb)
if (bb->next_bb != EXIT_BLOCK_PTR)
bb->rbi->next = bb->next_bb;
cfg_layout_finalize ();
return NULL;
}
/* Not going to update these. */
free (loops->cfg.rc_order);
loops->cfg.rc_order = NULL;
free (loops->cfg.dfs_order);
loops->cfg.dfs_order = NULL;
/* Create pre-headers. */
create_preheaders (loops, CP_SIMPLE_PREHEADERS);
/* Force all latches to have only single successor. */
force_single_succ_latches (loops);
/* Mark irreducible loops. */
mark_irreducible_loops (loops);
/* Dump loops. */
flow_loops_dump (loops, dumpfile, NULL, 1);
#ifdef ENABLE_CHECKING
verify_dominators (CDI_DOMINATORS);
verify_loop_structure (loops);
#endif
return loops;
}
/* The first basic block is moved after the second in the reorder chain. */
static void
fixup_loop_exit_succesor (basic_block exit_succ, basic_block latch)
{
basic_block bb = exit_succ;
basic_block bb1 = latch;
if (!(bb && bb->rbi->next))
return;
if (!bb1)
return;
if (bb && bb->rbi->next)
{
basic_block c = ENTRY_BLOCK_PTR->next_bb;
while (c->rbi->next != bb)
c = c->rbi->next;
c->rbi->next = bb->rbi->next;
}
if(bb1->rbi->next == NULL)
{
bb1->rbi->next=bb;
bb->rbi->next=NULL;
}
else
{
basic_block tmp;
tmp = bb1->rbi->next;
bb1->rbi->next = bb;
bb->rbi->next = tmp;
}
}
/* Finalize loop optimizer. */
void
loop_optimizer_finalize (struct loops *loops, FILE *dumpfile)
{
basic_block bb;
unsigned int i;
/* Finalize layout changes. */
/* Make chain. */
FOR_EACH_BB (bb)
if (bb->next_bb != EXIT_BLOCK_PTR)
bb->rbi->next = bb->next_bb;
/* Another dump. */
flow_loops_dump (loops, dumpfile, NULL, 1);
/* For loops ending with a branch and count instruction, move the basic
block found before the unrolling on the fallthru path of this branch,
after the unrolled code. This will allow branch simplification. */
for (i = 1; i < loops->num; i++)
{
struct loop *loop = loops->parray[i];
struct loop_desc *desc;
basic_block loop_real_latch, bb, bb_exit;
edge e;
if (loop == NULL)
continue;
if (!loop->simple)
continue;
if (!loop->has_desc)
continue;
if (loop->lpt_decision.decision != LPT_UNROLL_RUNTIME)
continue;
desc = &loop->desc;
if (desc == NULL)
continue;
if (loop->latch->pred == NULL)
continue;
loop_real_latch = loop->latch->pred->src;
if (desc->postincr)
continue;
if (!is_bct_cond (BB_END (loop_real_latch)))
continue;
for (e = loop_real_latch->succ; e ; e = e->succ_next)
if (e->flags & EDGE_FALLTHRU)
break;
if (e == NULL)
continue;
bb_exit = e->dest;
bb = NULL;
/* Leave the case of the bb_exit falling through to exit to
fixed_fallthru_exit_predecessor */
for (e = EXIT_BLOCK_PTR->pred; e; e = e->pred_next)
if (e->flags & EDGE_FALLTHRU)
bb = e->src;
if (bb_exit == bb)
continue;
fixup_loop_exit_succesor (bb_exit, loop->latch);
}
/* Clean up. */
flow_loops_free (loops);
free_dominance_info (CDI_DOMINATORS);
free (loops);
/* Finalize changes. */
cfg_layout_finalize ();
/* Checking. */
#ifdef ENABLE_CHECKING
verify_flow_info ();
#endif
}
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