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* [gcc r10-10765] tree-optimization/105431 - another overflow in powi handling
@ 2022-05-27 13:15 Richard Biener
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From: Richard Biener @ 2022-05-27 13:15 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:e41fa23451c965516a37282268231933fd948845
commit r10-10765-ge41fa23451c965516a37282268231933fd948845
Author: Richard Biener <rguenther@suse.de>
Date: Fri Apr 29 08:45:48 2022 +0200
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.c (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 44b09adb9bad99dd7e3017c5ecefed7f7c9a1590)
Diff:
---
gcc/tree-ssa-math-opts.c | 12 +++++-------
1 file changed, 5 insertions(+), 7 deletions(-)
diff --git a/gcc/tree-ssa-math-opts.c b/gcc/tree-ssa-math-opts.c
index fbaa3deffe3..dd0b8c6f057 100644
--- a/gcc/tree-ssa-math-opts.c
+++ b/gcc/tree-ssa-math-opts.c
@@ -1361,7 +1361,7 @@ 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;
@@ -1414,7 +1414,7 @@ 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;
@@ -1438,11 +1438,9 @@ 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;
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