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From: Alexey Tourbin <alexey.tourbin@gmail.com>
Date: Sat, 28 Aug 2021 03:27:59 +0300
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Subject: Re: [PATCH] x86-64: Add Avoid_Short_Distance_REP_MOVSB
Cc: libc-alpha@sourceware.org
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On Mon, Jul 26, 2021 at 3:03 PM H.J. Lu via Libc-alpha
<libc-alpha@sourceware.org> wrote:
> --- a/sysdeps/x86_64/multiarch/memmove-vec-unaligned-erms.S
> +++ b/sysdeps/x86_64/multiarch/memmove-vec-unaligned-erms.S
> @@ -325,12 +325,16 @@ L(movsb):
>         /* Avoid slow backward REP MOVSB.  */
>         jb      L(more_8x_vec_backward)
>  # if AVOID_SHORT_DISTANCE_REP_MOVSB
> +       andl    $X86_STRING_CONTROL_AVOID_SHORT_DISTANCE_REP_MOVSB, __x86_string_control(%rip)
> +       jz      3f
>         movq    %rdi, %rcx
>         subq    %rsi, %rcx
>         jmp     2f
>  # endif
>  1:
>  # if AVOID_SHORT_DISTANCE_REP_MOVSB
> +       andl    $X86_STRING_CONTROL_AVOID_SHORT_DISTANCE_REP_MOVSB, __x86_string_control(%rip)
> +       jz      3f
>         movq    %rsi, %rcx
>         subq    %rdi, %rcx
>  2:

Why "andl" rather than "testl"?