From 44b09adb9bad99dd7e3017c5ecefed7f7c9a1590 Mon Sep 17 00:00:00 2001
From: Richard Biener <rguenther@suse.de>
Date: Fri, 29 Apr 2022 08:45:48 +0200
Subject: [PATCH] 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.
---
gcc/tree-ssa-math-opts.cc | 12 +++++-------
1 file changed, 5 insertions(+), 7 deletions(-)
diff --git a/gcc/tree-ssa-math-opts.cc b/gcc/tree-ssa-math-opts.cc
index b528b0523ff1..2085597447ef 100644
--- a/gcc/tree-ssa-math-opts.cc
+++ b/gcc/tree-ssa-math-opts.cc
@@ -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;
--
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