From: Noah Goldstein <goldstein.w.n@gmail.com>
To: Aurelien Jarno <aurelien@aurel32.net>
Cc: libc-alpha@sourceware.org, "H . J . Lu" <hjl.tools@gmail.com>,
Sunil K Pandey <skpgkp2@gmail.com>
Subject: Re: [PATCH v3 5/8] x86-64: Require BMI2 for AVX2 wcs(n)cmp implementations
Date: Mon, 3 Oct 2022 14:11:49 -0700 [thread overview]
Message-ID: <CAFUsyfK2Wn6RjB=ix9dh7AXsmxF3B9xvQjR5UtjQ2UFWEjWyrA@mail.gmail.com> (raw)
In-Reply-To: <20221003195944.3274548-6-aurelien@aurel32.net>
On Mon, Oct 3, 2022 at 12:59 PM Aurelien Jarno <aurelien@aurel32.net> wrote:
>
> The AVX2 wcs(n)cmp implementations use the 'bzhi' instruction, which
> belongs to the BMI2 CPU feature.
>
> NB: It also uses the 'tzcnt' BMI1 instruction, but it is executed as BSF
> as BSF if the CPU doesn't support TZCNT, and produces the same result
> for non-zero input.
>
> Partially fixes: b77b06e0e296 ("x86: Optimize strcmp-avx2.S")
> Partially resolves: BZ #29611
> ---
> sysdeps/x86_64/multiarch/ifunc-impl-list.c | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/sysdeps/x86_64/multiarch/ifunc-impl-list.c b/sysdeps/x86_64/multiarch/ifunc-impl-list.c
> index aebef3daaf..fec8790c11 100644
> --- a/sysdeps/x86_64/multiarch/ifunc-impl-list.c
> +++ b/sysdeps/x86_64/multiarch/ifunc-impl-list.c
> @@ -810,10 +810,12 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
> && CPU_FEATURE_USABLE (BMI2)),
> __wcscmp_evex)
> X86_IFUNC_IMPL_ADD_V3 (array, i, wcscmp,
> - CPU_FEATURE_USABLE (AVX2),
> + (CPU_FEATURE_USABLE (AVX2)
> + && CPU_FEATURE_USABLE (BMI2)),
> __wcscmp_avx2)
> X86_IFUNC_IMPL_ADD_V3 (array, i, wcscmp,
> (CPU_FEATURE_USABLE (AVX2)
> + && CPU_FEATURE_USABLE (BMI2)
> && CPU_FEATURE_USABLE (RTM)),
> __wcscmp_avx2_rtm)
> /* ISA V2 wrapper for SSE2 implementation because the SSE2
> @@ -830,10 +832,12 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
> && CPU_FEATURE_USABLE (BMI2)),
> __wcsncmp_evex)
> X86_IFUNC_IMPL_ADD_V3 (array, i, wcsncmp,
> - CPU_FEATURE_USABLE (AVX2),
> + (CPU_FEATURE_USABLE (AVX2)
> + && CPU_FEATURE_USABLE (BMI2)),
> __wcsncmp_avx2)
> X86_IFUNC_IMPL_ADD_V3 (array, i, wcsncmp,
> (CPU_FEATURE_USABLE (AVX2)
> + && CPU_FEATURE_USABLE (BMI2)
> && CPU_FEATURE_USABLE (RTM)),
> __wcsncmp_avx2_rtm)
> /* ISA V2 wrapper for GENERIC implementation because the
> --
> 2.35.1
>
LGTM.
Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com>
next prev parent reply other threads:[~2022-10-03 21:12 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-03 19:59 [PATCH v3 0/8] x86: Fix AVX2 string functions requiring BMI1, BMI2 or LZCNT (BZ #29611) Aurelien Jarno
2022-10-03 19:59 ` [PATCH v3 1/8] x86: include BMI1 and BMI2 in x86-64-v3 level Aurelien Jarno
2022-10-03 21:11 ` Noah Goldstein
2022-10-03 19:59 ` [PATCH v3 2/8] x86-64: Require BMI2 for AVX2 str(n)casecmp implementations Aurelien Jarno
2022-10-03 21:11 ` Noah Goldstein
2022-10-03 19:59 ` [PATCH v3 3/8] x86-64: Require BMI2 for AVX2 strcmp implementation Aurelien Jarno
2022-10-03 21:12 ` Noah Goldstein
2022-10-03 19:59 ` [PATCH v3 4/8] x86-64: Require BMI2 for AVX2 strncmp implementation Aurelien Jarno
2022-10-03 21:11 ` Noah Goldstein
2022-10-03 19:59 ` [PATCH v3 5/8] x86-64: Require BMI2 for AVX2 wcs(n)cmp implementations Aurelien Jarno
2022-10-03 21:11 ` Noah Goldstein [this message]
2022-10-03 19:59 ` [PATCH v3 6/8] x86-64: Require BMI2 for AVX2 (raw|w)memchr implementations Aurelien Jarno
2022-10-03 21:12 ` Noah Goldstein
2022-10-03 19:59 ` [PATCH v3 7/8] x86-64: Require BMI2 and LZCNT for AVX2 memrchr implementation Aurelien Jarno
2022-10-03 21:12 ` Noah Goldstein
2022-10-03 19:59 ` [PATCH v3 8/8] x86-64: Require BMI1/BMI2 for AVX2 strrchr and wcsrchr implementations Aurelien Jarno
2022-10-03 21:12 ` Noah Goldstein
2022-10-03 20:47 ` [PATCH v3 0/8] x86: Fix AVX2 string functions requiring BMI1, BMI2 or LZCNT (BZ #29611) Sunil Pandey
2022-10-03 21:11 ` Noah Goldstein
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CAFUsyfK2Wn6RjB=ix9dh7AXsmxF3B9xvQjR5UtjQ2UFWEjWyrA@mail.gmail.com' \
--to=goldstein.w.n@gmail.com \
--cc=aurelien@aurel32.net \
--cc=hjl.tools@gmail.com \
--cc=libc-alpha@sourceware.org \
--cc=skpgkp2@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).