[Bug tree-optimization/125501] [14/15/16/17 Regression] wrong code at -O3 that crashes at runtime

[amacleod at redhat dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=125501

--- Comment #9 from Andrew Macleod <amacleod at redhat dot com> ---
(In reply to Richard Biener from comment #7)
> What unswitch produces still looks OK.  Instead of if (a4 == 0) return;
> we'll do if (a4 == a5) if (a4 == 0) return;  But the inner if is gone
> in .optimized, DOM3/threadfull2/VRP2 remove it.
> 
> I suspect sth is amiss with ranger/relations, we have some unreachable ()
> on some unrelated path.
> 
> Andrew, can you have a look please?

I'll look later when I get a chance, but at first glance on my build, it shows

  q.i.225t.cddce3:Deleting : if (a4_14(D) == 0B)

  its there through store-merging, and then cddce3 deleted the second if... ?