https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120941
H.J. Lu <hjl.tools at gmail dot com> changed:
What |Removed |Added
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CC| |rguenth at gcc dot gnu.org
--- Comment #15 from H.J. Lu <hjl.tools at gmail dot com> ---
(In reply to H.J. Lu from comment #14)
> (In reply to Filip Kastl from comment #11)
> > (In reply to H.J. Lu from comment #9)
> > > Created attachment 61803 [details]
> > > A patch
> > >
> > > Please try this.
> >
> > Tried applying this on top of r16-1644-gaba3b9d3a48a07.
> > With r16-1644-gaba3b9d3a48a07 ... 224s
> > With r16-1644-gaba3b9d3a48a07 and the patch ... 161s
> > (this is on the machine where I originally measured 24% slowdown)
> >
> > Looks like this patch gets us the original speed and even a bit more. Nice.
> >
> > (In reply to H.J. Lu from comment #10)
> > > (In reply to Filip Kastl from comment #8)
> > > > The same commit (r16-1644-gaba3b9d3a48a07) causes ~20% slowdown of
> > > > 470lbm
> > > > from 2006 SPEC on Zen5 with -Ofast -march=native -flto -fprofile-use.
> > > >
> > > > https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=1283.240.0
> > >
> > > Can you extra a small testcase to show the issue?
> >
> > I could try. But we already have a patch. So I think we don't have to
> > search for a smaller testcase. What do you think?
>
> It isn't needed.
Richard commented my patch:
https://gcc.gnu.org/pipermail/gcc-patches/2025-July/688899.html
Please extra a small testcase so that I can find a different way to fix it.
You can do
1. Identify which file caused the regression:
2. Compile file with -da
3. Search *.311r.rrvl for
Replace:
...
with:
and
Add:
...
and extract a small testcase from debug dump.
