https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91756
--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
The disambiguation needs "translation" (vn_reference_lookup_3 using the
original
ref for path-based disambiguation), but we do not allow this when looking
across backedges in the maybe_skip_until walk and the loop we have to cross
in alias disambiguation looks like
do
{
if (n <= i)
break;
ptr->a[i].foo = 1; // this stmt to disambiguate against
}
while (1);
but then DOM is happy with this structure because it valueizes in the IL
itself. So the guard against backedges must be too conservative since
DOM also walks across them. I've added this as fix for PR87132.
