https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111444
--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
(In reply to Richard Biener from comment #2)
> Hmm, so we look for a *(int **) here, reach the toplevel vop, skipping *j =
> &e?
> That should have conflicted.
Seems we actually saw that.
walk_non_aliased_vuses calls walker (vn_reference_lookup_2) on .MEM_8 vuse,
that still returns NULL, then
3909 if (stmt_may_clobber_ref_p_1 (def_stmt, ref, tbaa_p))
3910 {
3911 if (!translate)
3912 break;
3913 translate_flags disambiguate_only = TR_TRANSLATE;
3914 res = (*translate) (ref, vuse, data, &disambiguate_only);
on the def_stmt:
# .MEM_8 = VDEF <.MEM_7(D)>
*j_1(D) = &e;
returns true from stmt_may_clobber_ref_p_1, correctly saying that *j_1(D) store
can clobber *i_1(D).
But then walk_non_aliased_vuses calls
3914 res = (*translate) (ref, vuse, data, &disambiguate_only);
a few lines later, translate is vn_reference_lookup_3.
And vn_reference_lookup_3 calls vn_reference_lookup_2 here in:
tree *saved_last_vuse_ptr = data->last_vuse_ptr;
/* Do not update last_vuse_ptr in vn_reference_lookup_2. */
data->last_vuse_ptr = NULL;
tree saved_vuse = vr->vuse;
hashval_t saved_hashcode = vr->hashcode;
void *res = vn_reference_lookup_2 (ref, gimple_vuse (def_stmt),
data);
/* Need to restore vr->vuse and vr->hashcode. */
vr->vuse = saved_vuse;
vr->hashcode = saved_hashcode;
data->last_vuse_ptr = saved_last_vuse_ptr;
and def_stmt here is still the *j_1(D) = &e; statement, the problem is that
gimple_vuse (def_stmt) in that case is .MEM_7(D), so it triggers the r14-3226
if (SSA_NAME_IS_DEFAULT_DEF (vuse)) stuff at that point. So, do we need to
somehow
arrange for the if (SSA_NAME_IS_DEFAULT_DEF (vuse)) code to be done solely when
vn_reference_lookup_2 is called directly from walk_non_aliased_vuses and not
when
called from vn_reference_lookup_3?
