On Sun, Nov 4, 2018 at 8:17 PM H.J. Lu <hjl.to...@gmail.com> wrote:
>
> On Sun, Nov 4, 2018 at 8:41 AM Uros Bizjak <ubiz...@gmail.com> wrote:
> >
> > On Fri, Nov 2, 2018 at 6:25 PM H.J. Lu <hongjiu...@intel.com> wrote:
> > >
> > > Remove duplicated AVX2/AVX512 vec_dup patterns and replace them with
> > > subreg. gcc.target/i386/avx2-vbroadcastss_ps256-1.c is changed by
> > >
> > > avx2_test:
> > > .cfi_startproc
> > > - vmovaps x(%rip), %xmm1
> > > - vbroadcastss %xmm1, %ymm0
> > > + vbroadcastss x(%rip), %ymm0
> > > vmovaps %ymm0, y(%rip)
> > > vzeroupper
> > > ret
> > > .cfi_endproc
> > >
> > > gcc.target/i386/avx512vl-vbroadcast-3.c is changed by
> > >
> > > @@ -113,7 +113,7 @@ f10:
> > > .cfi_startproc
> > > vmovaps %ymm0, %ymm16
> > > vpermilps $85, %ymm16, %ymm16
> > > - vbroadcastss %xmm16, %ymm16
> > > + vshuff32x4 $0x0, %ymm16, %ymm16, %ymm16
> > > vzeroupper
> > > ret
> > > .cfi_endproc
> > > @@ -153,8 +153,7 @@ f12:
> > > f13:
> > > .LFB12:
> > > .cfi_startproc
> > > - vmovaps (%rdi), %ymm16
> > > - vbroadcastss %xmm16, %ymm16
> > > + vbroadcastss (%rdi), %ymm16
> > > vzeroupper
> > > ret
> > > .cfi_endproc
> >
> > Actually, we can achieve the same with pre-reload splitters. Please
> > see the attached patch for a couple of examples and a fix for
> > vbroadcastss that accesses the memory in wrong mode.
> >
>
> My patch removes a bunch of duplicated patterns from sse.md. But
> yours adds a couple more patterns. Isn't fewer patterns preferred?
Playing SUBREG games before reload does not look safe to me. We would
like to create a simpler instruction out of the combination of vector
load and broadcast, so I think that combine+split is the right tool
for this simplification.
BTW: Half of my proposed patch is a fix to a avx2_pbroadcast<mode>{_1}
pattern, which models wrong access to memory.
Uros.
