Re: [PATCH]i386: Optimize pmovskb on zero_extend of subreg HI of the result [PR98461]

[Uros Bizjak <ubizjak@gmail.com>]

On Mon, Jan 4, 2021 at 6:54 AM Hongtao Liu <crazylht@gmail.com> wrote:
>
> Hi:
>   The following patch adds define_insn_and_split to optimize
>
>        vpmovmskb       %xmm0, %eax
> -       movzwl  %ax, %eax
>         notl    %eax
>
>   Bootstrapped/regtested on x86_64-linux-gnu {,-m32}.
>   Ok for trunk?
>
> gcc/ChangeLog
>         PR target/98461
>         * config/i386/sse.md (*sse2_pmovskb_zexthisi): New
>         define_insn_and_split for zero_extend of subreg HI of pmovskb
>         result.
>
> gcc/testsuite/ChangeLog
>         * gcc.target/i386/sse-pr98461-2.c: New test.
> ---
>  gcc/config/i386/sse.md                         | 11 +++++++++++
>  gcc/testsuite/gcc.target/i386/sse2-pr98461-2.c | 13 +++++++++++++
>  2 files changed, 24 insertions(+)
>  create mode 100644 gcc/testsuite/gcc.target/i386/sse2-pr98461-2.c
>
> diff --git a/gcc/config/i386/sse.md b/gcc/config/i386/sse.md
> index d84103807ff..4ed6b9ae476 100644
> --- a/gcc/config/i386/sse.md
> +++ b/gcc/config/i386/sse.md
> @@ -16099,6 +16099,17 @@ (define_insn "*sse2_pmovmskb_ext"
>     (set_attr "prefix" "maybe_vex")
>     (set_attr "mode" "SI")])
>
> +(define_insn_and_split "*sse2_pmovskb_zexthisi"
> +  [(set (match_operand:SI 0 "register_operand")
> +       (zero_extend:SI (subreg:HI (unspec:SI
> +         [(match_operand:V16QI 1 "register_operand")]
> +          UNSPEC_MOVMSK) 0)))]
> +  "TARGET_SSE2"

This needs ix86_pre_reload_split () in insn predicate.

Uros.

> +  "#"
> +  "&& 1"
> +  [(set (match_dup 0)
> +       (unspec:SI [(match_dup 1)] UNSPEC_MOVMSK))])
> +
>  (define_split
>    [(set (match_operand:SI 0 "register_operand")
>         (unspec:SI
> diff --git a/gcc/testsuite/gcc.target/i386/sse2-pr98461-2.c
> b/gcc/testsuite/gcc.target/i386/sse2-pr98461-2.c
> new file mode 100644
> index 00000000000..60fc1f3e9c1
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/sse2-pr98461-2.c
> @@ -0,0 +1,13 @@
> +/* PR target/98461 */
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -msse2 -mno-sse3 -masm=att" } */
> +/* { dg-final { scan-assembler-times "\tpmovmskb\t" 1 } } */
> +/* { dg-final { scan-assembler-not "\tmovzwl" } } */
> +/* { dg-final { scan-assembler-times "\tnotl" 1 } } */
> +
> +#include <immintrin.h>
> +
> +unsigned int movemask_not1(__m128i logical) {
> +  unsigned short res = (unsigned short)(_mm_movemask_epi8(logical));
> +  return ~res;
> +}
> --
> 2.18.1
>
>
> --
> BR,
> Hongtao