[gcc r10-10764] tree-optimization/105368 - avoid overflow in powi_cost

[Richard Biener <rguenth@gcc.gnu.org>]

https://gcc.gnu.org/g:ebe6ffee1aa2d819e4fbdf4130e054a33c274b38

commit r10-10764-gebe6ffee1aa2d819e4fbdf4130e054a33c274b38
Author: Richard Biener <rguenther@suse.de>
Date:   Mon Apr 25 10:55:21 2022 +0200

    tree-optimization/105368 - avoid overflow in powi_cost
    
    The following avoids undefined signed overflow when computing
    the absolute of the exponent in powi_cost.
    
    2022-04-25  Richard Biener  <rguenther@suse.de>
    
            PR tree-optimization/105368
            * tree-ssa-math-opts.c (powi_cost): Use absu_hwi.
    
    (cherry picked from commit f0e170f72f8bfaa2a64e1d09ebdfd48f917420f1)

Diff:
---
 gcc/tree-ssa-math-opts.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/gcc/tree-ssa-math-opts.c b/gcc/tree-ssa-math-opts.c
index 4c89fddcfc5..fbaa3deffe3 100644
--- a/gcc/tree-ssa-math-opts.c
+++ b/gcc/tree-ssa-math-opts.c
@@ -1328,7 +1328,7 @@ powi_cost (HOST_WIDE_INT n)
     return 0;
 
   /* Ignore the reciprocal when calculating the cost.  */
-  val = (n < 0) ? -n : n;
+  val = absu_hwi (n);
 
   /* Initialize the exponent cache.  */
   memset (cache, 0, POWI_TABLE_SIZE * sizeof (bool));