Re: RISC-V: Folding memory for FP + constant case

[Philipp Tomsich <philipp.tomsich@vrull.eu>]

Very helpful! Looks as if regprop for stack_pointer is now either too
conservative — or one of our patches is missing in everyone's test
setup; we'll take a closer look.

On Wed, 2 Aug 2023 at 01:03, Vineet Gupta <vineetg@rivosinc.com> wrote:
>
>
>
> On 8/1/23 15:07, Philipp Tomsich wrote:
> > +Manolis Tsamis
> >
> > On Tue, 1 Aug 2023 at 23:56, Jeff Law via Gcc-patches
> > <gcc-patches@gcc.gnu.org> wrote:
> >>
> >>
> >> On 8/1/23 13:14, Vineet Gupta wrote:
> >>
> >>> I have some numbers for f-m-o v3 vs this. Attached here (vs. inline to
> >>> avoid the Thunderbird mangling the test formatting)
> >> Thanks.  Of particular importance is the leela change.  My recollection
> >> was that the f-m-o work also picked up that case.  But if my memory is
> >> faulty (always a possibility), then that shows a clear case where
> >> Jivan's work picks up a case not handled by Manolis's work.
> > f-m-o originally targeted (and benefited) the leela-case.  I wonder if
> > other optimizations/changes over the last year interfere with this and
> > what needs to be changed to accomodate this... looks like we need to
> > revisit against trunk.
> >
> > Philipp.
> >
> >> And on the other direction we can see that deepsjeng isn't helped by
> >> Jivan's work, but is helped by Manolis's new pass.
> >>
> >> I'd always hoped/expected we'd have cases where one patch clearly helped
> >> over the other.  While the .25% to .37% improvements for the three most
> >> impacted benchmarks doesn't move the needle much across the whole suite
> >> they do add up over time.
> >>
> >> Jeff
>
> I took a quick look at Leela, the significant difference is from
> additional insns with SP not getting propagated.
>
> e.g.
>
>     231b6:    mv    a4,sp
>     231b8:    sh2add    a5,a5,a4
>
> vs.
>
>     1e824:    sh2add    a5,a5,sp
>
> There are 5 such instances which more or less make up for the delta.
>
> -Vineet
>