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ivopts: fix wide_int_constant_multiple_p when VAL and DIV are 0. [PR114932]

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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.
This commit is contained in:
Tamar Christina 2024-07-03 09:30:28 +01:00
parent 47ea6bddd1
commit 2512712310
1 changed files with 8 additions and 5 deletions
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13
gcc/tree-affine.cc
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@ -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;