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tree-ssa-loop-niter.c (simplify_using_initial_conditions): Limit iteration over the dominators.

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2006-06-21  Richrad Guenther  <rguenther@suse.de>

	* tree-ssa-loop-niter.c (simplify_using_initial_conditions):
	Limit iteration over the dominators.

From-SVN: r114840
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Richard Guenther 2006-06-21 08:11:28 +00:00 committed by Richard Biener
parent 470145e722
commit b16fb82dac
2 changed files with 17 additions and 2 deletions
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5
gcc/ChangeLog
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@ -1,3 +1,8 @@
2006-06-21 Richrad Guenther <rguenther@suse.de>
* tree-ssa-loop-niter.c (simplify_using_initial_conditions):
Limit iteration over the dominators.
2006-06-20 Roger Sayle <roger@eyesopen.com>
* config/mips/iris6.h (LIB_SPEC): Add support for -pthread.

14
gcc/tree-ssa-loop-niter.c
View File

@ -886,7 +886,12 @@ tree_simplify_using_condition (tree cond, tree expr)
return tree_simplify_using_condition_1 (cond, expr);
}
/* The maximum number of dominator BBs we search for conditions
of loop header copies we use for simplifying a conditional
expression. */
#define MAX_DOMINATORS_TO_WALK 8
/* Tries to simplify EXPR using the conditions on entry to LOOP.
Record the conditions used for simplification to CONDS_USED.
Returns the simplified expression (or EXPR unchanged, if no
@ -899,12 +904,16 @@ simplify_using_initial_conditions (struct loop *loop, tree expr,
edge e;
basic_block bb;
tree exp, cond;
int cnt = 0;
if (TREE_CODE (expr) == INTEGER_CST)
return expr;
/* Limit walking the dominators to avoid quadraticness in
the number of BBs times the number of loops in degenerate
cases. */
for (bb = loop->header;
bb != ENTRY_BLOCK_PTR;
bb != ENTRY_BLOCK_PTR && cnt < MAX_DOMINATORS_TO_WALK;
bb = get_immediate_dominator (CDI_DOMINATORS, bb))
{
if (!single_pred_p (bb))
@ -926,6 +935,7 @@ simplify_using_initial_conditions (struct loop *loop, tree expr,
cond);
expr = exp;
++cnt;
}
return expr;