On Tue, Aug 3, 2021 at 10:15 AM Hongtao Liu <crazy...@gmail.com> wrote:
>
> On Tue, Aug 3, 2021 at 4:03 PM Uros Bizjak via Gcc-patches
> <gcc-patches@gcc.gnu.org> wrote:
> >
> > On Mon, Aug 2, 2021 at 7:47 PM H.J. Lu <hjl.to...@gmail.com> wrote:
> > >
> > > In 64-bit mode, use XMM31 for scratch SSE register to avoid vzeroupper
> > > if possible.
> > >
> > > gcc/
> > >
> > > * config/i386/i386.c (ix86_gen_scratch_sse_rtx): In 64-bit mode,
> > > try XMM31 to avoid vzeroupper.
> > >
> > > gcc/testsuite/
> > >
> > > * gcc.target/i386/avx-vzeroupper-14.c: Pass -mno-avx512f to
> > > disable XMM31.
> > > * gcc.target/i386/avx-vzeroupper-15.c: Likewise.
> > > * gcc.target/i386/pr82941-1.c: Updated. Check for vzeroupper.
> > > * gcc.target/i386/pr82942-1.c: Likewise.
> > > * gcc.target/i386/pr82990-1.c: Likewise.
> > > * gcc.target/i386/pr82990-3.c: Likewise.
> > > * gcc.target/i386/pr82990-5.c: Likewise.
> > > * gcc.target/i386/pr100865-4b.c: Likewise.
> > > * gcc.target/i386/pr100865-6b.c: Likewise.
> > > * gcc.target/i386/pr100865-7b.c: Likewise.
> > > * gcc.target/i386/pr100865-10b.c: Likewise.
> > > * gcc.target/i386/pr100865-8b.c: Updated.
> > > * gcc.target/i386/pr100865-9b.c: Likewise.
> > > * gcc.target/i386/pr100865-11b.c: Likewise.
> > > * gcc.target/i386/pr100865-12b.c: Likewise.
> > > ---
> > > gcc/config/i386/i386.c | 18 +++++++++++++++---
> > > .../gcc.target/i386/avx-vzeroupper-14.c | 2 +-
> > > .../gcc.target/i386/avx-vzeroupper-15.c | 2 +-
> > > gcc/testsuite/gcc.target/i386/pr100865-10b.c | 1 +
> > > gcc/testsuite/gcc.target/i386/pr100865-11b.c | 2 +-
> > > gcc/testsuite/gcc.target/i386/pr100865-12b.c | 2 +-
> > > gcc/testsuite/gcc.target/i386/pr100865-4b.c | 2 ++
> > > gcc/testsuite/gcc.target/i386/pr100865-6b.c | 5 ++++-
> > > gcc/testsuite/gcc.target/i386/pr100865-7b.c | 5 ++++-
> > > gcc/testsuite/gcc.target/i386/pr100865-8b.c | 2 +-
> > > gcc/testsuite/gcc.target/i386/pr100865-9b.c | 2 +-
> > > gcc/testsuite/gcc.target/i386/pr82941-1.c | 3 ++-
> > > gcc/testsuite/gcc.target/i386/pr82942-1.c | 3 ++-
> > > gcc/testsuite/gcc.target/i386/pr82990-1.c | 3 ++-
> > > gcc/testsuite/gcc.target/i386/pr82990-3.c | 3 ++-
> > > gcc/testsuite/gcc.target/i386/pr82990-5.c | 3 ++-
> > > 16 files changed, 42 insertions(+), 16 deletions(-)
> > >
> > > diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
> > > index 842eb0e6786..ec0690876b7 100644
> > > --- a/gcc/config/i386/i386.c
> > > +++ b/gcc/config/i386/i386.c
> > > @@ -23335,9 +23335,21 @@ rtx
> > > ix86_gen_scratch_sse_rtx (machine_mode mode)
> > > {
> > > if (TARGET_SSE && !lra_in_progress)
> > > - return gen_rtx_REG (mode, (TARGET_64BIT
> > > - ? LAST_REX_SSE_REG
> > > - : LAST_SSE_REG));
> > > + {
> > > + unsigned int regno;
> > > + if (TARGET_64BIT)
> > > + {
> > > + /* In 64-bit mode, use XMM31 to avoid vzeroupper and always
> > > + use XMM31 for CSE. */
> > > + if (ix86_hard_regno_mode_ok (LAST_EXT_REX_SSE_REG, mode))
> > > + regno = LAST_EXT_REX_SSE_REG;
> > > + else
> > > + regno = LAST_REX_SSE_REG;
> > > + }
> > > + else
> > > + regno = LAST_SSE_REG;
> >
> > Assuming that ix86_hard_regno_mode_ok always returns false for XMM31
> > in 64bit mode, we can do:
> >
> > /* Use XMM31 if available to avoid vzeroupper. */
> > if (ix86_hard_regno_mode_ok (LAST_EXT_REX_SSE_REG, mode))
> > regno = LAST_EXST_REX_SSE_REG;
> > else if (TARGET_64BIT)
> > regno = LAST_EXT_REX_SSE_REG;
> why? w/o avx512 xmm31 is not available.
Oh, a typo, this should read LAST_REX_SSE_REG.
Uros.
