[Bug middle-end/106534] [13 Regression][gcn] ICE 'verify_ssa failed' / 'error: definition in block 18 does not dominate use in block 19' during libgfortran bootstrap

[tnfchris at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106534

--- Comment #6 from Tamar Christina <tnfchris at gcc dot gnu.org> ---
(In reply to rguenther@suse.de from comment #5)
> On Fri, 5 Aug 2022, burnus at gcc dot gnu.org wrote:
> 
> > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106534
> > 
> > --- Comment #4 from Tobias Burnus <burnus at gcc dot gnu.org> ---
> > Seems as if the ICE is fixed for that file by reverting the following commit:
> > 
> > commit r13-1963-gc832ec4c3ec4853ad89ff3b0dbf6e9454e75e8cc
> >     middle-end: Fix phi-ssa assertion triggers.  [PR106519]
> 
> As hinted in the e-mail exchange the earlier two transforms might need
> guarding with !diamond_p since IIRC only minmax is capable of dealing
> with it?

Yes, Though I didn't find any failing cases so I didn't guard store elim.
value_replacement is a weird one as it looks like it's already looking for some
kind of diamond form.  I can guard both to be safe, but that's essentially
doing a blind change if I can't reproduce this locally.