From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from hall.aurel32.net (hall.aurel32.net [IPv6:2001:bc8:30d7:100::1]) by sourceware.org (Postfix) with ESMTPS id 4F9A03858D32 for ; Sun, 2 Oct 2022 18:09:06 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 4F9A03858D32 Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=aurel32.net Authentication-Results: sourceware.org; spf=none smtp.mailfrom=aurel32.net DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=aurel32.net ; s=202004.hall; h=In-Reply-To:Content-Type:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Content-Transfer-Encoding:From:Reply-To: Subject:Content-ID:Content-Description:X-Debbugs-Cc; bh=VFsJPhMikv5QBL2QvgyvmC3N1i2fRfIBzc+mXz9xFX4=; b=SBQL3LwMKlNoT6G4EaKnMyetKN avYb+Wh43ZVonTi5g1F9NW3uaKHr7fwUVGMWr4X8yV78MhL8vo7/IP8Rr/XtUDgyYblLMAHxKJWxm YPy9IAH8ZONURgRXXonB3Gb90CVTKCDFrp3Y3gwnZ3YkS8W3v79W+z+CmcRZ3Je4BGkdQmfzWbhIw ch8o4qhDi72oFQesE/MhscFKD3PRRzJ92ronGy3+pxbCFaGjnoy+qHLeFm0+mjK89nEJaEG72gffk XuFHK3ZYapbXPemSQWHu/61f+CjnO2IHusSeeEUdrrqDXYbUOGO3i7K6lvXYoULQDw0yT7V+eUKID vtJ6b+Zg==; Received: from [2a01:e34:ec5d:a741:8a4c:7c4e:dc4c:1787] (helo=ohm.rr44.fr) by hall.aurel32.net with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1of3Oi-00FVU7-90; Sun, 02 Oct 2022 20:09:04 +0200 Received: from aurel32 by ohm.rr44.fr with local (Exim 4.96) (envelope-from ) id 1of3Oh-00D1Ya-2n; Sun, 02 Oct 2022 20:09:03 +0200 Date: Sun, 2 Oct 2022 20:09:03 +0200 From: Aurelien Jarno To: Noah Goldstein Cc: libc-alpha@sourceware.org, "H . J . Lu" , Sunil K Pandey Subject: Re: [PATCH v2 0/6] x86: Fix AVX2 string functions requiring BMI1, BMI2 or LZCNT (BZ #29611) Message-ID: Mail-Followup-To: Noah Goldstein , libc-alpha@sourceware.org, "H . J . Lu" , Sunil K Pandey References: <20221002123424.3079805-1-aurelien@aurel32.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/2.2.7 (2022-08-07) X-Spam-Status: No, score=-7.1 required=5.0 tests=BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,SPF_HELO_PASS,SPF_NONE,TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: On 2022-10-02 09:21, Noah Goldstein wrote: > On Sun, Oct 2, 2022 at 5:34 AM Aurelien Jarno wrote: > > > > Some early Intel Haswell CPU have AVX2 instructions, but do not have > > BMI1 and BMI2 instructions. Some AVX2 string functions only check for > > AVX2, but use BMI1, BMI2 or LZCNT instructions. This patchset tries to > > fix that. > > > > While most fixes only change ifunc-impl-list.c, and thus only concerns > > the testsuite, the strn(case)cmp is a real issue affecting early Intel > > str(case)cmp as well, correct? Oops, yes forgot to update the cover letter on that aspect. > > Haswell CPU, reported to affect Debian Sid and Fedora Rawhide. > > > > On the other hand, the check for LZCNT in memrchr is purely for > > correctness, I am not aware of a CPU implementing AVX2 without LZCNT. > > > > This has been tested by remplacing all BMI1 and BMI2 instructions in the > > source code by the "ud2" instruction and disabling the BMI1, BMI2 > > feature detection, and running the testsuite. > > > > Resolves: BZ #29611 > > > > Change v1 -> v2: > > - Better scan for BMI2 instructions (shlx and shrx) and BMI1 > > instructions (blsmsk) instructions following the feedback from Noah > > Goldstein > > > > Aurelien Jarno (6): > > x86: include BMI1 and BMI2 in x86-64-v3 level > > x86-64: Require BMI2 for AVX2 str*cmp and wcs(n)cmp implementations > > x86-64: Require BMI2 for AVX2 (raw|w)memchr implementations > > x86-64: Require LZCNT for AVX2 memrchr implementation > > x86-64: Require BMI1/BMI2 for AVX2 strrchr and wcsrchr implementations > > x86-64: Require BMI2 for AVX2 memrchr implementation > > > > sysdeps/x86/get-isa-level.h | 2 + > > sysdeps/x86/isa-level.h | 2 + > > sysdeps/x86_64/multiarch/ifunc-avx2.h | 2 + > > sysdeps/x86_64/multiarch/ifunc-impl-list.c | 86 ++++++++++++++++----- > > sysdeps/x86_64/multiarch/ifunc-strcasecmp.h | 1 + > > sysdeps/x86_64/multiarch/strcmp.c | 4 +- > > sysdeps/x86_64/multiarch/strncmp.c | 4 +- > > 7 files changed, 76 insertions(+), 25 deletions(-) > > > > -- > > 2.35.1 > > > -- Aurelien Jarno GPG: 4096R/1DDD8C9B aurelien@aurel32.net http://www.aurel32.net