https://gcc.gnu.org/g:25127123100f04c2d5d70c6933a5f5aedcd69c40
commit r15-1808-g25127123100f04c2d5d70c6933a5f5aedcd69c40
Author: Tamar Christina <tamar.christ...@arm.com>
Date: Wed Jul 3 09:30:28 2024 +0100
ivopts: fix wide_int_constant_multiple_p when VAL and DIV are 0. [PR114932]
wide_int_constant_multiple_p tries to check if for two tree expressions a
and b
that there is a multiplier which makes a == b * c.
This code however seems to think that there's no c where a=0 and b=0 are
equal
which is of course wrong.
This fixes it and also fixes the comment.
gcc/ChangeLog:
PR tree-optimization/114932
* tree-affine.cc (wide_int_constant_multiple_p): Support 0 and 0
being
multiples.
Diff:
---
gcc/tree-affine.cc | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)
diff --git a/gcc/tree-affine.cc b/gcc/tree-affine.cc
index d6309c43903..76117aa4fd6 100644
--- a/gcc/tree-affine.cc
+++ b/gcc/tree-affine.cc
@@ -880,11 +880,11 @@ free_affine_expand_cache (hash_map<tree, name_expansion
*> **cache)
*cache = NULL;
}
-/* If VAL != CST * DIV for any constant CST, returns false.
- Otherwise, if *MULT_SET is true, additionally compares CST and MULT,
- and if they are different, returns false. Finally, if neither of these
- two cases occur, true is returned, and CST is stored to MULT and MULT_SET
- is set to true. */
+/* If VAL == CST * DIV for any constant CST, returns true.
+ and if *MULT_SET is true, additionally compares CST and MULT
+ and if they are different, returns false. If true is returned, CST is
+ stored to MULT and MULT_SET is set to true unless VAL and DIV are both zero
+ in which case neither MULT nor MULT_SET are updated. */
static bool
wide_int_constant_multiple_p (const poly_widest_int &val,
@@ -895,6 +895,9 @@ wide_int_constant_multiple_p (const poly_widest_int &val,
if (known_eq (val, 0))
{
+ if (known_eq (div, 0))
+ return true;
+
if (*mult_set && maybe_ne (*mult, 0))
return false;
*mult_set = true;
