[PATCH v2] x86: Remove SSSE3 instruction for broadcast in memset.S (SSE2 Only)

[H.J. Lu]

On Mon, Feb 7, 2022 at 11:39 AM Noah Goldstein <goldstein.w.n@gmail.com> wrote:
>
> commit b62ace2740a106222e124cc86956448fa07abf4d
> Author: Noah Goldstein <goldstein.w.n@gmail.com>
> Date:   Sun Feb 6 00:54:18 2022 -0600
>
>     x86: Improve vec generation in memset-vec-unaligned-erms.S
>
> Revert usage of 'pshufb' in broadcast logic as it is an SSSE3
> instruction and memset.S is restricted to only SSE2 instructions.
> ---
>  sysdeps/x86_64/memset.S | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/sysdeps/x86_64/memset.S b/sysdeps/x86_64/memset.S
> index ccf036be53..3f0517bbfc 100644
> --- a/sysdeps/x86_64/memset.S
> +++ b/sysdeps/x86_64/memset.S
> @@ -30,9 +30,10 @@
>
>  # define MEMSET_SET_VEC0_AND_SET_RETURN(d, r) \
>    movd d, %xmm0; \
> -  pxor %xmm1, %xmm1; \
> -  pshufb %xmm1, %xmm0; \
> -  movq r, %rax
> +  movq r, %rax; \
> +  punpcklbw %xmm0, %xmm0; \
> +  punpcklwd %xmm0, %xmm0; \
> +  pshufd $0, %xmm0, %xmm0
>
>  # define WMEMSET_SET_VEC0_AND_SET_RETURN(d, r) \
>    movd d, %xmm0; \
> --
> 2.25.1
>

LGTM.

Reviewed-by: H.J. Lu <hjl.tools@gmail.com>

Thanks.

-- 
H.J.