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 3BB72385AC3B for ; Mon, 3 Oct 2022 21:56:19 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 3BB72385AC3B 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=Content-Transfer-Encoding:MIME-Version:References: In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Content-Type:From:Reply-To: Subject:Content-ID:Content-Description:X-Debbugs-Cc; bh=cgFy5U+tcTbTo+a375A09pf+1umiu4jFwqllaN4y/jM=; b=ZrTaJSUoRGQMavhScVHQk19NG/ SFFHyRAq4C0s1CYoi6/xQyClOyVhbjkVuIEuYdLyRnu1r7dEx2VuTj6A8Fjm6YcrleDL937w+8dxo L9IKmCwIvBjgY5PVi1bJOGXAtztq+8mlOUcLLTpsOv96x+LZdw6d14Twhv+6HDB93wZhFNkJWT1nZ Uy3FWX1BGdx2e9rrnpWxWkkPT82lA8YkJx9CNFfQHNPw99/WeAKzC4fUJlIzeN6BI1Wcj1stPGi3f 6lbagd922edSNqQP/ksJlQlbZsiFJlB/gwlALzIhyTI5lCbAtn8GSmXabyMtZlgzfw4xlWgUezLL6 sTb/fRjA==; 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 1ofTQ9-00GL4S-OK; Mon, 03 Oct 2022 23:56:17 +0200 Received: from aurel32 by ohm.rr44.fr with local (Exim 4.96) (envelope-from ) id 1ofTQ8-00DozE-2c; Mon, 03 Oct 2022 23:56:16 +0200 From: Aurelien Jarno To: libc-stable@sourceware.org Cc: Aurelien Jarno , Noah Goldstein Subject: [COMMITTED 2.35 3/8] x86-64: Require BMI2 for AVX2 strcmp implementation Date: Mon, 3 Oct 2022 23:56:09 +0200 Message-Id: <20221003215614.3294221-3-aurelien@aurel32.net> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20221003215614.3294221-1-aurelien@aurel32.net> References: <20221003215614.3294221-1-aurelien@aurel32.net> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=-13.2 required=5.0 tests=BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,GIT_PATCH_0,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: The AVX2 strcmp implementation 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 (cherry picked from commit 4d64c6445735e9b34e2ac8e369312cbfc2f88e17) --- sysdeps/x86_64/multiarch/ifunc-impl-list.c | 4 +++- sysdeps/x86_64/multiarch/strcmp.c | 4 ++-- 2 files changed, 5 insertions(+), 3 deletions(-) diff --git a/sysdeps/x86_64/multiarch/ifunc-impl-list.c b/sysdeps/x86_64/multiarch/ifunc-impl-list.c index 2d8c87a42e..136e3b8103 100644 --- a/sysdeps/x86_64/multiarch/ifunc-impl-list.c +++ b/sysdeps/x86_64/multiarch/ifunc-impl-list.c @@ -521,10 +521,12 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array, /* Support sysdeps/x86_64/multiarch/strcmp.c. */ IFUNC_IMPL (i, name, strcmp, IFUNC_IMPL_ADD (array, i, strcmp, - CPU_FEATURE_USABLE (AVX2), + (CPU_FEATURE_USABLE (AVX2) + && CPU_FEATURE_USABLE (BMI2)), __strcmp_avx2) IFUNC_IMPL_ADD (array, i, strcmp, (CPU_FEATURE_USABLE (AVX2) + && CPU_FEATURE_USABLE (BMI2) && CPU_FEATURE_USABLE (RTM)), __strcmp_avx2_rtm) IFUNC_IMPL_ADD (array, i, strcmp, diff --git a/sysdeps/x86_64/multiarch/strcmp.c b/sysdeps/x86_64/multiarch/strcmp.c index 08638e2632..b2bc619585 100644 --- a/sysdeps/x86_64/multiarch/strcmp.c +++ b/sysdeps/x86_64/multiarch/strcmp.c @@ -40,11 +40,11 @@ IFUNC_SELECTOR (void) const struct cpu_features* cpu_features = __get_cpu_features (); if (CPU_FEATURE_USABLE_P (cpu_features, AVX2) + && CPU_FEATURE_USABLE_P (cpu_features, BMI2) && CPU_FEATURES_ARCH_P (cpu_features, AVX_Fast_Unaligned_Load)) { if (CPU_FEATURE_USABLE_P (cpu_features, AVX512VL) - && CPU_FEATURE_USABLE_P (cpu_features, AVX512BW) - && CPU_FEATURE_USABLE_P (cpu_features, BMI2)) + && CPU_FEATURE_USABLE_P (cpu_features, AVX512BW)) return OPTIMIZE (evex); if (CPU_FEATURE_USABLE_P (cpu_features, RTM)) -- 2.35.1