On Fri, Dec 8, 2023 at 10:17 AM liuhongt <hongtao....@intel.com> wrote:
>
> If the function desn't clobber any sse registers or only clobber
> 128-bit part, then vzeroupper isn't issued before the function exit.
> the status not CLEAN but ANY after the function.
>
> Also for sibling_call, it's safe to issue an vzeroupper. Also there
> could be missing vzeroupper since there's no mode_exit for
> sibling_call_p.
>
> Compared to the patch in the PR, this patch add sibling_call part.
> Bootstrapped and regtested on x86_64-pc-linux-gnu{-m32,}.
> Ok for trunk and backport?
Part of this has been approved in the PR, and for the sibling_call
part, i think it should be reasonable.
So i'm going to commit the patch.
>
> gcc/ChangeLog:
>
> PR target/112891
> * config/i386/i386.cc (ix86_avx_u128_mode_after): Return
> AVX_U128_ANY if callee_abi doesn't clobber all_sse_regs to
> align with ix86_avx_u128_mode_needed.
> (ix86_avx_u128_mode_needed): Return AVX_U128_ClEAN for
> sibling_call.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.target/i386/pr112891.c: New test.
> * gcc.target/i386/pr112891-2.c: New test.
> ---
> gcc/config/i386/i386.cc | 22 +++++++++++++---
> gcc/testsuite/gcc.target/i386/pr112891-2.c | 30 ++++++++++++++++++++++
> gcc/testsuite/gcc.target/i386/pr112891.c | 29 +++++++++++++++++++++
> 3 files changed, 78 insertions(+), 3 deletions(-)
> create mode 100644 gcc/testsuite/gcc.target/i386/pr112891-2.c
> create mode 100644 gcc/testsuite/gcc.target/i386/pr112891.c
>
> diff --git a/gcc/config/i386/i386.cc b/gcc/config/i386/i386.cc
> index 7c5cab4e2c6..fe259cdb789 100644
> --- a/gcc/config/i386/i386.cc
> +++ b/gcc/config/i386/i386.cc
> @@ -15038,8 +15038,12 @@ ix86_avx_u128_mode_needed (rtx_insn *insn)
> vzeroupper if all SSE registers are clobbered. */
> const function_abi &abi = insn_callee_abi (insn);
> if (vzeroupper_pattern (PATTERN (insn), VOIDmode)
> - || !hard_reg_set_subset_p (reg_class_contents[SSE_REGS],
> - abi.mode_clobbers (V4DImode)))
> + /* Should be safe to issue an vzeroupper before sibling_call_p.
> + Also there not mode_exit for sibling_call, so there could be
> + missing vzeroupper for that. */
> + || !(SIBLING_CALL_P (insn)
> + || hard_reg_set_subset_p (reg_class_contents[SSE_REGS],
> + abi.mode_clobbers (V4DImode))))
> return AVX_U128_ANY;
>
> return AVX_U128_CLEAN;
> @@ -15177,7 +15181,19 @@ ix86_avx_u128_mode_after (int mode, rtx_insn *insn)
> bool avx_upper_reg_found = false;
> note_stores (insn, ix86_check_avx_upper_stores, &avx_upper_reg_found);
>
> - return avx_upper_reg_found ? AVX_U128_DIRTY : AVX_U128_CLEAN;
> + if (avx_upper_reg_found)
> + return AVX_U128_DIRTY;
> +
> + /* If the function desn't clobber any sse registers or only clobber
> + 128-bit part, Then vzeroupper isn't issued before the function exit.
> + the status not CLEAN but ANY after the function. */
> + const function_abi &abi = insn_callee_abi (insn);
> + if (!(SIBLING_CALL_P (insn)
> + || hard_reg_set_subset_p (reg_class_contents[SSE_REGS],
> + abi.mode_clobbers (V4DImode))))
> + return AVX_U128_ANY;
> +
> + return AVX_U128_CLEAN;
> }
>
> /* Otherwise, return current mode. Remember that if insn
> diff --git a/gcc/testsuite/gcc.target/i386/pr112891-2.c
> b/gcc/testsuite/gcc.target/i386/pr112891-2.c
> new file mode 100644
> index 00000000000..164c3985d50
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr112891-2.c
> @@ -0,0 +1,30 @@
> +/* { dg-do compile } */
> +/* { dg-options "-mavx2 -O3" } */
> +/* { dg-final { scan-assembler-times "vzeroupper" 1 } } */
> +
> +void
> +__attribute__((noinline))
> +bar (double* a)
> +{
> + a[0] = 1.0;
> + a[1] = 2.0;
> +}
> +
> +double
> +__attribute__((noinline))
> +foo (double* __restrict a, double* b)
> +{
> + a[0] += b[0];
> + a[1] += b[1];
> + a[2] += b[2];
> + a[3] += b[3];
> + bar (b);
> + return a[5] + b[5];
> +}
> +
> +double
> +foo1 (double* __restrict a, double* b)
> +{
> + double c = foo (a, b);
> + return __builtin_exp (c);
> +}
> diff --git a/gcc/testsuite/gcc.target/i386/pr112891.c
> b/gcc/testsuite/gcc.target/i386/pr112891.c
> new file mode 100644
> index 00000000000..dbf6c67948a
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr112891.c
> @@ -0,0 +1,29 @@
> +/* { dg-do compile } */
> +/* { dg-options "-mavx2 -O3" } */
> +/* { dg-final { scan-assembler-times "vzeroupper" 1 } } */
> +
> +void
> +__attribute__((noinline))
> +bar (double* a)
> +{
> + a[0] = 1.0;
> + a[1] = 2.0;
> +}
> +
> +void
> +__attribute__((noinline))
> +foo (double* __restrict a, double* b)
> +{
> + a[0] += b[0];
> + a[1] += b[1];
> + a[2] += b[2];
> + a[3] += b[3];
> + bar (b);
> +}
> +
> +double
> +foo1 (double* __restrict a, double* b)
> +{
> + foo (a, b);
> + return __builtin_exp (b[1]);
> +}
> --
> 2.31.1
>
--
BR,
Hongtao
