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From: "cvs-commit at gcc dot gnu.org" <sourceware-bugzilla@sourceware.org>
To: glibc-bugs@sourceware.org
Subject: [Bug string/29611] Optimized AVX2 string functions unconditionally
 use BMI2 instructions
Date: Mon, 03 Oct 2022 21:55:56 +0000
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https://sourceware.org/bugzilla/show_bug.cgi?id=3D29611

--- Comment #48 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot g=
nu.org> ---
The release/2.35/master branch has been updated by Aurelien Jarno
<aurel32@sourceware.org>:

https://sourceware.org/git/gitweb.cgi?p=3Dglibc.git;h=3D7e1326c43a7ab246894=
6bd711983907d79ceca3b

commit 7e1326c43a7ab2468946bd711983907d79ceca3b
Author: Aurelien Jarno <aurelien@aurel32.net>
Date:   Mon Oct 3 23:16:46 2022 +0200

    x86-64: Require BMI2 for AVX2 strncmp implementation

    The AVX2 strncmp implementations uses 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 fc7de1d9b99ae1676bc626ddca422d7abee0eb48)

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