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

[Hongtao Liu <crazylht@gmail.com>]

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.
>
> 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