From: Aurelien Jarno <aurelien@aurel32.net>
To: libc-stable@sourceware.org
Cc: Aurelien Jarno <aurelien@aurel32.net>,
Noah Goldstein <goldstein.w.n@gmail.com>
Subject: [COMMITTED 2.35 5/8] x86-64: Require BMI2 for AVX2 wcs(n)cmp implementations
Date: Mon, 3 Oct 2022 23:56:11 +0200 [thread overview]
Message-ID: <20221003215614.3294221-5-aurelien@aurel32.net> (raw)
In-Reply-To: <20221003215614.3294221-1-aurelien@aurel32.net>
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
Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com>
(cherry picked from commit f31a5a884ed84bd37032729d4d1eb9d06c9f3c29)
---
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 b27ae975e4..5824554b4e 100644
--- a/sysdeps/x86_64/multiarch/ifunc-impl-list.c
+++ b/sysdeps/x86_64/multiarch/ifunc-impl-list.c
@@ -711,10 +711,12 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
/* Support sysdeps/x86_64/multiarch/wcscmp.c. */
IFUNC_IMPL (i, name, wcscmp,
IFUNC_IMPL_ADD (array, i, wcscmp,
- CPU_FEATURE_USABLE (AVX2),
+ (CPU_FEATURE_USABLE (AVX2)
+ && CPU_FEATURE_USABLE (BMI2)),
__wcscmp_avx2)
IFUNC_IMPL_ADD (array, i, wcscmp,
(CPU_FEATURE_USABLE (AVX2)
+ && CPU_FEATURE_USABLE (BMI2)
&& CPU_FEATURE_USABLE (RTM)),
__wcscmp_avx2_rtm)
IFUNC_IMPL_ADD (array, i, wcscmp,
@@ -727,10 +729,12 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
/* Support sysdeps/x86_64/multiarch/wcsncmp.c. */
IFUNC_IMPL (i, name, wcsncmp,
IFUNC_IMPL_ADD (array, i, wcsncmp,
- CPU_FEATURE_USABLE (AVX2),
+ (CPU_FEATURE_USABLE (AVX2)
+ && CPU_FEATURE_USABLE (BMI2)),
__wcsncmp_avx2)
IFUNC_IMPL_ADD (array, i, wcsncmp,
(CPU_FEATURE_USABLE (AVX2)
+ && CPU_FEATURE_USABLE (BMI2)
&& CPU_FEATURE_USABLE (RTM)),
__wcsncmp_avx2_rtm)
IFUNC_IMPL_ADD (array, i, wcsncmp,
--
2.35.1
next prev parent reply other threads:[~2022-10-03 21:56 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-03 21:56 [COMMITTED 2.35 1/8] x86: include BMI1 and BMI2 in x86-64-v3 level Aurelien Jarno
2022-10-03 21:56 ` [COMMITTED 2.35 2/8] x86-64: Require BMI2 for AVX2 str(n)casecmp implementations Aurelien Jarno
2022-10-03 21:56 ` [COMMITTED 2.35 3/8] x86-64: Require BMI2 for AVX2 strcmp implementation Aurelien Jarno
2022-10-03 21:56 ` [COMMITTED 2.35 4/8] x86-64: Require BMI2 for AVX2 strncmp implementation Aurelien Jarno
2022-10-03 21:56 ` Aurelien Jarno [this message]
2022-10-03 21:56 ` [COMMITTED 2.35 6/8] x86-64: Require BMI2 for AVX2 (raw|w)memchr implementations Aurelien Jarno
2022-10-03 21:56 ` [COMMITTED 2.35 7/8] x86-64: Require BMI2 and LZCNT for AVX2 memrchr implementation Aurelien Jarno
2022-10-03 21:56 ` [COMMITTED 2.35 8/8] x86-64: Require BMI1/BMI2 for AVX2 strrchr and wcsrchr implementations Aurelien Jarno
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=20221003215614.3294221-5-aurelien@aurel32.net \
--to=aurelien@aurel32.net \
--cc=goldstein.w.n@gmail.com \
--cc=libc-stable@sourceware.org \
/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).