Re: [match.pd] [SVE] Add pattern to transform svrev(svrev(v)) --> v

[Prathamesh Kulkarni <prathamesh.kulkarni@linaro.org>]

On Tue, 11 Apr 2023 at 19:36, Prathamesh Kulkarni
<prathamesh.kulkarni@linaro.org> wrote:
>
> On Tue, 11 Apr 2023 at 14:17, Richard Biener <richard.guenther@gmail.com> wrote:
> >
> > On Wed, Apr 5, 2023 at 10:39 AM Prathamesh Kulkarni via Gcc-patches
> > <gcc-patches@gcc.gnu.org> wrote:
> > >
> > > Hi,
> > > For the following test:
> > >
> > > svint32_t f(svint32_t v)
> > > {
> > >   return svrev_s32 (svrev_s32 (v));
> > > }
> > >
> > > We generate 2 rev instructions instead of nop:
> > > f:
> > >         rev     z0.s, z0.s
> > >         rev     z0.s, z0.s
> > >         ret
> > >
> > > The attached patch tries to fix that by trying to recognize the following
> > > pattern in match.pd:
> > > v1 = VEC_PERM_EXPR (v0, v0, mask)
> > > v2 = VEC_PERM_EXPR (v1, v1, mask)
> > > -->
> > > v2 = v0
> > > if mask is { nelts - 1, nelts - 2, nelts - 3, ... }
> > >
> > > Code-gen with patch:
> > > f:
> > >         ret
> > >
> > > Bootstrap+test passes on aarch64-linux-gnu, and SVE bootstrap in progress.
> > > Does it look OK for stage-1 ?
> >
> > I didn't look at the patch but tree-ssa-forwprop.cc:simplify_permutation should
> > handle two consecutive permutes with the is_combined_permutation_identity
> > which might need tweaking for VLA vectors
> Hi Richard,
> Thanks for the suggestions. The attached patch modifies
> is_combined_permutation_identity
> to recognize the above pattern.
> Does it look OK ?
> Bootstrap+test in progress on aarch64-linux-gnu and x86_64-linux-gnu.
Hi,
ping https://gcc.gnu.org/pipermail/gcc-patches/2023-April/615502.html

Thanks,
Prathamesh
>
> Thanks,
> Prathamesh
> >
> > Richard.
> >
> > >
> > > Thanks,
> > > Prathamesh