https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98891
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Ever confirmed|0 |1
CC| |jakub at gcc dot gnu.org,
| |wilco at gcc dot gnu.org
Last reconfirmed| |2021-03-17
--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Reduced testcase:
extern unsigned long long a, b, c;
void
foo (void)
{
a = b | ~c;
}
Seems this is the usual dilemma between split double-word operations early vs.
split it late, each has its advantages and serious disadvantages.
By splitting early, combiner can't really do much with it, it is split into
loads, not, or and store of the halves separately and combiner doesn't see the
two halves together, one would need essentially vectorization on RTL to match
that.
