Re: [PATCH 1/2] Don't issue vzeroupper for vzeroupper call_insn.

[Uros Bizjak <ubizjak@gmail.com>]

On Tue, Jun 27, 2023 at 8:08 AM Hongtao Liu <crazylht@gmail.com> wrote:
>
> On Tue, Jun 27, 2023 at 2:05 PM Uros Bizjak <ubizjak@gmail.com> wrote:
> >
> > On Tue, Jun 27, 2023 at 7:55 AM liuhongt <hongtao.liu@intel.com> wrote:
> > >
> > > Bootstrapped and regtested on x86_64-pc-linux-gnu{-m32,}.
> > > Ok for trunk?
> > >
> > > gcc/ChangeLog:
> > >
> > >         PR target/82735
> > >         * config/i386/i386.cc (ix86_avx_u127_mode_needed): Don't emit
> > >         vzeroupper for vzeroupper call_insn.
> > >
> > > gcc/testsuite/ChangeLog:
> > >
> > >         * gcc.target/i386/avx-vzeroupper-30.c: New test.
> > > ---
> > >  gcc/config/i386/i386.cc                           |  5 +++--
> > >  gcc/testsuite/gcc.target/i386/avx-vzeroupper-30.c | 15 +++++++++++++++
> > >  2 files changed, 18 insertions(+), 2 deletions(-)
> > >  create mode 100644 gcc/testsuite/gcc.target/i386/avx-vzeroupper-30.c
> > >
> > > diff --git a/gcc/config/i386/i386.cc b/gcc/config/i386/i386.cc
> > > index 0761965344b..caca74d6dec 100644
> > > --- a/gcc/config/i386/i386.cc
> > > +++ b/gcc/config/i386/i386.cc
> > > @@ -14489,8 +14489,9 @@ ix86_avx_u128_mode_needed (rtx_insn *insn)
> > >          modes wider than 256 bits.  It's only safe to issue a
> > >          vzeroupper if all SSE registers are clobbered.  */
> > >        const function_abi &abi = insn_callee_abi (insn);
> > > -      if (!hard_reg_set_subset_p (reg_class_contents[SSE_REGS],
> > > -                                 abi.mode_clobbers (V4DImode)))
> > > +      if (vzeroupper_pattern (PATTERN (insn), VOIDmode)
> > > +         || !hard_reg_set_subset_p (reg_class_contents[SSE_REGS],
> > > +                                    abi.mode_clobbers (V4DImode)))
> > >         return AVX_U128_ANY;
> >
> > You also want to check for vzeroall_pattern here.
> This is inside
>  if (CALL_P (insn))
>
> vzeroupper is defined as special call_insn, but vzeroall is not.

Indeed. Patch is OK as it is then.

Thanks,
Uros.

> >
> > OK with the above change.
> >
> > Thanks,
> > Uros.
> >
> > >
> > >        return AVX_U128_CLEAN;
> > > diff --git a/gcc/testsuite/gcc.target/i386/avx-vzeroupper-30.c b/gcc/testsuite/gcc.target/i386/avx-vzeroupper-30.c
> > > new file mode 100644
> > > index 00000000000..c1c9baa8fc4
> > > --- /dev/null
> > > +++ b/gcc/testsuite/gcc.target/i386/avx-vzeroupper-30.c
> > > @@ -0,0 +1,15 @@
> > > +/* { dg-do compile } */
> > > +/* { dg-options "-O2 -mavx -mvzeroupper -dp" } */
> > > +
> > > +#include <immintrin.h>
> > > +
> > > +extern __m256 x, y;
> > > +
> > > +void
> > > +foo ()
> > > +{
> > > +  x = y;
> > > +  _mm256_zeroupper ();
> > > +}
> > > +
> > > +/* { dg-final { scan-assembler-times "avx_vzeroupper" 1 } } */
> > > --
> > > 2.39.1.388.g2fc9e9ca3c
> > >
>
>
>
> --
> BR,
> Hongtao