From patchwork Thu Jun 30 20:13:18 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Noah Goldstein X-Patchwork-Id: 55613 Return-Path: X-Original-To: patchwork@sourceware.org Delivered-To: patchwork@sourceware.org Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id C09AD3857C4C for ; Thu, 30 Jun 2022 20:13:49 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org C09AD3857C4C DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1656620029; bh=NQQWL46v5IMmPBFZidwNC0hTHWMxXpvLpLbAQcIcKjg=; h=To:Subject:Date:In-Reply-To:References:List-Id:List-Unsubscribe: List-Archive:List-Post:List-Help:List-Subscribe:From:Reply-To: From; b=wWyFY3is0GJFZBi1zkEL+TiCPACdEDo0oYNUeWnYi761wChOBylMUHwp9U07RiNE2 qYJu33ja8CJU+1IeDRKll0x7da6ErvQzbB4CzdN1E3f8Zu31xIO4n6rQCpBStP45JS IvEVWLKO7pgcbYYLWBRTVY3E8xb7zJhRHLh7B7Sk= X-Original-To: libc-alpha@sourceware.org Delivered-To: libc-alpha@sourceware.org Received: from mail-pf1-x42b.google.com (mail-pf1-x42b.google.com [IPv6:2607:f8b0:4864:20::42b]) by sourceware.org (Postfix) with ESMTPS id EE9603858D39 for ; Thu, 30 Jun 2022 20:13:26 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org EE9603858D39 Received: by mail-pf1-x42b.google.com with SMTP id n12so506287pfq.0 for ; Thu, 30 Jun 2022 13:13:26 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=NQQWL46v5IMmPBFZidwNC0hTHWMxXpvLpLbAQcIcKjg=; b=cJcFEcy6oTzeNUf+2IDhkPAtYQdGJ0F3jMePVmDOwlMcn2mmgFh2uDXJcWVOF6GTVm ibfExV99DoQnaG6pNl2lS0f5beCARksMfpAL2rW+ftoTbKxTLwmuT1gPVPGubQfcJ5S9 ds7gGOCx1JNbwxa2Wa32vQwzzl8R7cIT55a3QmPOd2dUKewQ3ggWvcQi+b+75Nw/VVf+ Hb5crDgDQzwV0hv7Rs8shhRow8ffYNMD3OZd2VOAdQpacJNHCQyFu5j1he6wvZB97wVa 45keZv1A5VAGVNzKnCtmGc51q4vt1cK5DWB6Kt5hAfkQRqNgNCQ7UFsnnw4M4cB7odQZ H5yg== X-Gm-Message-State: AJIora8sBYYulXWAJCEg30W6+12/je88UKGBOOLk6Wc9mrHDIUmEv5Ek +WOuGojVSoIDCG4gHGy92xNuUuXeeiI= X-Google-Smtp-Source: AGRyM1sYkZ5QK+A+ADaDci0CrvjBLN9dxci3TA3NqApsUcQERAgiwbI6siN8d3L8ghq/kNlPvmjTmg== X-Received: by 2002:a62:8641:0:b0:527:f5f7:dee0 with SMTP id x62-20020a628641000000b00527f5f7dee0mr9712795pfd.76.1656620005789; Thu, 30 Jun 2022 13:13:25 -0700 (PDT) Received: from noah-tgl.. ([192.55.60.43]) by smtp.gmail.com with ESMTPSA id i21-20020a63e455000000b0040cfb5151fcsm13706943pgk.74.2022.06.30.13.13.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 30 Jun 2022 13:13:25 -0700 (PDT) To: libc-alpha@sourceware.org Subject: [PATCH v6 1/2] x86: Add comment explaining no Slow_SSE4_2 check in ifunc-sse4_2 Date: Thu, 30 Jun 2022 13:13:18 -0700 Message-Id: <20220630201319.3777218-1-goldstein.w.n@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220628152717.17838-1-goldstein.w.n@gmail.com> References: <20220628152717.17838-1-goldstein.w.n@gmail.com> MIME-Version: 1.0 X-Spam-Status: No, score=-11.8 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, FREEMAIL_FROM, GIT_PATCH_0, KAM_NUMSUBJECT, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-Patchwork-Original-From: Noah Goldstein via Libc-alpha From: Noah Goldstein Reply-To: Noah Goldstein Errors-To: libc-alpha-bounces+patchwork=sourceware.org@sourceware.org Sender: "Libc-alpha" Just for clarities sake and so that if a future implementation is added we remember to add the check. --- sysdeps/x86_64/multiarch/ifunc-sse4_2.h | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/sysdeps/x86_64/multiarch/ifunc-sse4_2.h b/sysdeps/x86_64/multiarch/ifunc-sse4_2.h index ee36525bcf..752798278c 100644 --- a/sysdeps/x86_64/multiarch/ifunc-sse4_2.h +++ b/sysdeps/x86_64/multiarch/ifunc-sse4_2.h @@ -27,6 +27,10 @@ IFUNC_SELECTOR (void) { const struct cpu_features* cpu_features = __get_cpu_features (); + /* This function uses slow sse4.2 instructions (pcmpstri) but since + there is no other optimized implementation keep using it. If an + optimized fallback is added add a X86_ISA_CPU_FEATURE_ARCH_P + (cpu_features, Slow_SSE4_2) check. */ if (CPU_FEATURE_USABLE_P (cpu_features, SSE4_2)) return OPTIMIZE (sse42);