/* Loop unswitching.
- Copyright (C) 2004, 2005, 2007, 2008 Free Software Foundation, Inc.
+ Copyright (C) 2004, 2005, 2007, 2008, 2010 Free Software Foundation, Inc.
This file is part of GCC.
#include "coretypes.h"
#include "tm.h"
#include "tree.h"
-#include "rtl.h"
#include "tm_p.h"
-#include "hard-reg-set.h"
#include "basic-block.h"
#include "output.h"
-#include "diagnostic.h"
#include "tree-flow.h"
#include "tree-dump.h"
#include "timevar.h"
if (!stmt || gimple_code (stmt) != GIMPLE_COND)
return NULL_TREE;
+ /* To keep the things simple, we do not directly remove the conditions,
+ but just replace tests with 0 != 0 resp. 1 != 0. Prevent the infinite
+ loop where we would unswitch again on such a condition. */
+ if (gimple_cond_true_p (stmt) || gimple_cond_false_p (stmt))
+ return NULL_TREE;
+
/* Condition must be invariant. */
FOR_EACH_SSA_TREE_OPERAND (use, stmt, iter, SSA_OP_USE)
{
cond = build2 (gimple_cond_code (stmt), boolean_type_node,
gimple_cond_lhs (stmt), gimple_cond_rhs (stmt));
- /* To keep the things simple, we do not directly remove the conditions,
- but just replace tests with 0/1. Prevent the infinite loop where we
- would unswitch again on such a condition. */
- if (integer_zerop (cond) || integer_nonzerop (cond))
- return NULL_TREE;
-
return cond;
}
{
basic_block *bbs;
struct loop *nloop;
- unsigned i;
+ unsigned i, found;
tree cond = NULL_TREE;
gimple stmt;
bool changed = false;
- /* Do not unswitch too much. */
- if (num > PARAM_VALUE (PARAM_MAX_UNSWITCH_LEVEL))
- {
- if (dump_file && (dump_flags & TDF_DETAILS))
- fprintf (dump_file, ";; Not unswitching anymore, hit max level\n");
- return false;
- }
-
i = 0;
bbs = get_loop_body (loop);
+ found = loop->num_nodes;
while (1)
{
if (i == loop->num_nodes)
{
- free (bbs);
- return changed;
+ if (dump_file
+ && num > PARAM_VALUE (PARAM_MAX_UNSWITCH_LEVEL)
+ && (dump_flags & TDF_DETAILS))
+ fprintf (dump_file, ";; Not unswitching anymore, hit max level\n");
+
+ if (found == loop->num_nodes)
+ {
+ free (bbs);
+ return changed;
+ }
+ break;
}
cond = simplify_using_entry_checks (loop, cond);
gimple_cond_set_condition_from_tree (stmt, boolean_false_node);
changed = true;
}
+ /* Do not unswitch too much. */
+ else if (num > PARAM_VALUE (PARAM_MAX_UNSWITCH_LEVEL))
+ {
+ i++;
+ continue;
+ }
+ /* In nested tree_unswitch_single_loop first optimize all conditions
+ using entry checks, then discover still reachable blocks in the
+ loop and find the condition only among those still reachable bbs. */
+ else if (num != 0)
+ {
+ if (found == loop->num_nodes)
+ found = i;
+ i++;
+ continue;
+ }
else
- break;
+ {
+ found = i;
+ break;
+ }
update_stmt (stmt);
i++;
}
+ if (num != 0)
+ {
+ basic_block *tos, *worklist;
+
+ /* When called recursively, first do a quick discovery
+ of reachable bbs after the above changes and only
+ consider conditions in still reachable bbs. */
+ tos = worklist = XNEWVEC (basic_block, loop->num_nodes);
+
+ for (i = 0; i < loop->num_nodes; i++)
+ bbs[i]->flags &= ~BB_REACHABLE;
+
+ /* Start with marking header. */
+ *tos++ = bbs[0];
+ bbs[0]->flags |= BB_REACHABLE;
+
+ /* Iterate: find everything reachable from what we've already seen
+ within the same innermost loop. Don't look through false edges
+ if condition is always true or true edges if condition is
+ always false. */
+ while (tos != worklist)
+ {
+ basic_block b = *--tos;
+ edge e;
+ edge_iterator ei;
+ int flags = 0;
+
+ if (EDGE_COUNT (b->succs) == 2)
+ {
+ gimple stmt = last_stmt (b);
+ if (stmt
+ && gimple_code (stmt) == GIMPLE_COND)
+ {
+ if (gimple_cond_true_p (stmt))
+ flags = EDGE_FALSE_VALUE;
+ else if (gimple_cond_false_p (stmt))
+ flags = EDGE_TRUE_VALUE;
+ }
+ }
+
+ FOR_EACH_EDGE (e, ei, b->succs)
+ {
+ basic_block dest = e->dest;
+
+ if (dest->loop_father == loop
+ && !(dest->flags & BB_REACHABLE)
+ && !(e->flags & flags))
+ {
+ *tos++ = dest;
+ dest->flags |= BB_REACHABLE;
+ }
+ }
+ }
+
+ free (worklist);
+
+ /* Find a bb to unswitch on. */
+ for (; found < loop->num_nodes; found++)
+ if ((bbs[found]->flags & BB_REACHABLE)
+ && (cond = tree_may_unswitch_on (bbs[found], loop)))
+ break;
+
+ if (found == loop->num_nodes)
+ {
+ free (bbs);
+ return changed;
+ }
+ }
+
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, ";; Unswitching loop\n");
initialize_original_copy_tables ();
/* Unswitch the loop on this condition. */
- nloop = tree_unswitch_loop (loop, bbs[i], cond);
+ nloop = tree_unswitch_loop (loop, bbs[found], cond);
if (!nloop)
{
free_original_copy_tables ();
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