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tree-optimization/105431 - another overflow in powi handling 

This avoids undefined signed overflow when calling powi_as_mults_1.

2022-04-29  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/105431
	* tree-ssa-math-opts.cc (powi_as_mults_1): Make n unsigned.
	(powi_as_mults): Use absu_hwi.
	(gimple_expand_builtin_powi): Remove now pointless n != -n
	check.

(cherry picked from commit 44b09adb9b)
This commit is contained in:
Richard Biener 2022-04-29 08:45:48 +02:00
parent 72c2898ccd
commit 1e43783b3f
1 changed files with 5 additions and 7 deletions
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12
gcc/tree-ssa-math-opts.cc
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@ -1495,7 +1495,7 @@ powi_cost (HOST_WIDE_INT n)
static tree
powi_as_mults_1 (gimple_stmt_iterator *gsi, location_t loc, tree type,
HOST_WIDE_INT n, tree *cache)
unsigned HOST_WIDE_INT n, tree *cache)
{
tree op0, op1, ssa_target;
unsigned HOST_WIDE_INT digit;
@ -1548,7 +1548,7 @@ powi_as_mults (gimple_stmt_iterator *gsi, location_t loc,
memset (cache, 0, sizeof (cache));
cache[1] = arg0;
result = powi_as_mults_1 (gsi, loc, type, (n < 0) ? -n : n, cache);
result = powi_as_mults_1 (gsi, loc, type, absu_hwi (n), cache);
if (n >= 0)
return result;
@ -1572,11 +1572,9 @@ static tree
gimple_expand_builtin_powi (gimple_stmt_iterator *gsi, location_t loc,
tree arg0, HOST_WIDE_INT n)
{
/* Avoid largest negative number. */
if (n != -n
&& ((n >= -1 && n <= 2)
|| (optimize_function_for_speed_p (cfun)
&& powi_cost (n) <= POWI_MAX_MULTS)))
if ((n >= -1 && n <= 2)
|| (optimize_function_for_speed_p (cfun)
&& powi_cost (n) <= POWI_MAX_MULTS))
return powi_as_mults (gsi, loc, arg0, n);
return NULL_TREE;