[Bug lto/83201] [7/8 Regression] SPEC CPU2017 505.mcf_r produces incorrect output when built with -flto and FDO

[rguenther at suse dot de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83201

--- Comment #12 from rguenther at suse dot de <rguenther at suse dot de> ---
On Tue, 19 Dec 2017, marxin at gcc dot gnu.org wrote:

> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83201
> 
> --- Comment #11 from Martin Liška <marxin at gcc dot gnu.org> ---
> (In reply to rguenther@suse.de from comment #10)
> > On Tue, 19 Dec 2017, marxin at gcc dot gnu.org wrote:
> > 
> > > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83201
> > > 
> > > --- Comment #9 from Martin Liška <marxin at gcc dot gnu.org> ---
> > > Using just a single ltrans, I see first divergence in mcf_r.ltrans0.088t.dom1.
> > > Richi, how possible is the revision real culprit?
> > 
> > Unlikely, it probably triggers a latent issue...
> 
> That's not much positive :/ Ideas what to do with that?

Given 505.mcf_r isn't too large figuring out the miscompiled function
shouldn't be too hard (heh, well ...).  The key is probably to somehow
reproduce without FDO ... like just do -fprofile-use?  What other flags
did you use on x86_64?