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References: <20221020021338.3394281-1-goldstein.w.n@gmail.com> <20221020021338.3394281-2-goldstein.w.n@gmail.com>
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From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Thu, 20 Oct 2022 10:03:03 -0700
Message-ID: <CAMe9rOpu_PgWOw4Y_WS-jA27pDdKjJBDnL2wH6GOv1JT2t+SHw@mail.gmail.com>
Subject: Re: [PATCH v1 2/4] x86: Use `testb` for case-locale check in str{n}casecmp-sse2
To: Noah Goldstein <goldstein.w.n@gmail.com>
Cc: libc-alpha@sourceware.org, carlos@systemhalted.org
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On Wed, Oct 19, 2022 at 7:14 PM Noah Goldstein <goldstein.w.n@gmail.com> wrote:
>
> `testb` saves a bit of code size is the imm-operand can be encoded
> 1-bytes.
>
> Tested on x86-64.
> ---
>  sysdeps/x86_64/multiarch/strcmp-sse2.S | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/sysdeps/x86_64/multiarch/strcmp-sse2.S b/sysdeps/x86_64/multiarch/strcmp-sse2.S
> index 3c69fc1df1..a975c924d8 100644
> --- a/sysdeps/x86_64/multiarch/strcmp-sse2.S
> +++ b/sysdeps/x86_64/multiarch/strcmp-sse2.S
> @@ -104,7 +104,7 @@ ENTRY (STRCMP)
>  #  else
>         mov     (%rdx), %RAX_LP
>  #  endif
> -       testl   $1, LOCALE_DATA_VALUES+_NL_CTYPE_NONASCII_CASE*SIZEOF_VALUES(%rax)
> +       testb   $1, LOCALE_DATA_VALUES+_NL_CTYPE_NONASCII_CASE*SIZEOF_VALUES(%rax)
>         jne     __strcasecmp_l_nonascii
>  # elif defined USE_AS_STRNCASECMP_L
>         /* We have to fall back on the C implementation for locales
> @@ -114,7 +114,7 @@ ENTRY (STRCMP)
>  #  else
>         mov     (%rcx), %RAX_LP
>  #  endif
> -       testl   $1, LOCALE_DATA_VALUES+_NL_CTYPE_NONASCII_CASE*SIZEOF_VALUES(%rax)
> +       testb   $1, LOCALE_DATA_VALUES+_NL_CTYPE_NONASCII_CASE*SIZEOF_VALUES(%rax)
>         jne     __strncasecmp_l_nonascii
>  # endif
>
> --
> 2.34.1
>

LGTM.

Thanks.

-- 
H.J.