https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113265
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
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CC| |rguenth at gcc dot gnu.org
--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
We have
/* X / -X is -1. */
(simplify
(div:C @0 (negate @0))
...
which doesn't use (negate_expr_p @0) but that wouldn't help because
(match negate_expr_p
(minus @0 @1)
(if ((ANY_INTEGRAL_TYPE_P (type) && TYPE_OVERFLOW_WRAPS (type))
|| (FLOAT_TYPE_P (type)
&& !HONOR_SIGN_DEPENDENT_ROUNDING (type)
&& !HONOR_SIGNED_ZEROS (type)))))
as (a - b) might be INT_MIN which we can't negate w/o invoking undefined
behavior. We also don't have (negate_expr_p @0), a way to match the
then negated form.
VN might come to the rescue to turn b - a to -(a - b) if that is available.
