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 E4E5D3858413 for ; Mon, 3 Oct 2022 22:04:51 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org E4E5D3858413 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=VR6kkaZauYDM6eQ+Q/39zigxYTSiu+c25QXDsW6UuU0=; b=z9qF3LCe5ASVJ7+7AMHJq6Gujo U2LLMsN4tdO/ltnsFxl7GENsMB1uUrVzPI1SmxH9pDDkaTJPXIHRWkhHfxL+1YtcEOalOpH0nJ9Zj DTLM7xx0Ev18Uo5WJ2VVGe2SS5reEOpOH832afVMrsRTF8+zYkCRzX9tjBdVRXj6lnN0LnzjX2ld+ mV72CjWgKuyvmi+su14PcjPvTWrrBKJeq4idi4i3Xlt78q758B21vZXSmfvcoajV8hpp6pXih7fQx 7fqfE+C6vDkK5X0CqHhu/5un/hQh+U2i+cyYoMFYarKRmEpNXOj3CUnA0dUMzcLZ9qJtiPieQXJRF J3b4+ASQ==; 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 1ofTYQ-00GLPf-K6; Tue, 04 Oct 2022 00:04:50 +0200 Received: from aurel32 by ohm.rr44.fr with local (Exim 4.96) (envelope-from ) id 1ofTYP-00Dq31-2S; Tue, 04 Oct 2022 00:04:49 +0200 From: Aurelien Jarno To: libc-stable@sourceware.org Cc: Aurelien Jarno , Noah Goldstein Subject: [COMMITTED 2.33 3/8] x86-64: Require BMI2 for AVX2 strcmp implementation Date: Tue, 4 Oct 2022 00:04:43 +0200 Message-Id: <20221003220448.3298308-3-aurelien@aurel32.net> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20221003220448.3298308-1-aurelien@aurel32.net> References: <20221003220448.3298308-1-aurelien@aurel32.net> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=-13.4 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 ca64b34c14..70931f1598 100644 --- a/sysdeps/x86_64/multiarch/ifunc-impl-list.c +++ b/sysdeps/x86_64/multiarch/ifunc-impl-list.c @@ -503,10 +503,12 @@ __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 b457fb4c15..0c0cd20a03 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