Re: [PATCH][i386] Split not+broadcast+pand to broadcast+pandn.

[Hongtao Liu <crazylht@gmail.com>]

On Tue, May 25, 2021 at 2:11 PM Andrew Pinski <pinskia@gmail.com> wrote:
>
> On Mon, May 24, 2021 at 11:03 PM Hongtao Liu via Gcc-patches
> <gcc-patches@gcc.gnu.org> wrote:
> >
> > Hi:
> >   This patch is about to do transformation like below.
> >   Bootstrapped and regtested on x86_64-linux-gnu{-m32,}.
> >   Ok for trunk?
> >
> > from
> >         notl    %edi
> >         vpbroadcastd    %edi, %xmm0
> >         vpand   %xmm1, %xmm0, %xmm0
> > to
> >         vpbroadcastd    %edi, %xmm0
> >         vpandn   %xmm1, %xmm0, %xmm0
> >
> > gcc/ChangeLog:
> >
> >         PR target/100711
> >         * config/i386/sse.md (*andnot<mode>3): New combine splitter
> >         after it.
> >
> > gcc/testsuite/ChangeLog:
> >
> >         PR target/100711
> >         * gcc.target/i386/avx2-pr100711.c: New test.
> >         * gcc.target/i386/avx512bw-pr100711.c: New test.
> >
>
>
> Does it make sense to make this more generic and have combine/simplify
> rtx instead try:
> (vec_dup (not)) to (not (vec_dup))

Even w/ that, a combine splitter is still needed since we don't have
any pandn patterns which contain op1 as vec_duplicate or "not" pattern
for vector mode,  generic simplification only helps combine/forprop to
match more possibilities, but not split pattern by itself.

>
> Thanks,
> Andrew Pinski



-- 
BR,
Hongtao