From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-yw1-x1130.google.com (mail-yw1-x1130.google.com [IPv6:2607:f8b0:4864:20::1130]) by sourceware.org (Postfix) with ESMTPS id AA70C3842AC8 for ; Wed, 29 Jun 2022 19:20:01 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org AA70C3842AC8 Received: by mail-yw1-x1130.google.com with SMTP id 00721157ae682-3177f4ce3e2so158051407b3.5 for ; Wed, 29 Jun 2022 12:20:01 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=huQUzqzmF0XJzmZVKJLjIpkaEeAz/t0J9kepHxd4/iw=; b=KgOdJ+GBWqlQvCDKyvfBEfUcFCsTfiv3KI2HIjWpGuuBCxtvzkcI5mwAMnaJjCDF2j Cj0UWU90sWfcz6YaZnGdrZ58yGaoYI/UpXiNEiOYS7bzbTvwsh3M/hgY4kEFXq7TYUbt PRWd4shO78iOA5nCtnooePjH/KVZJ8eYJe/yNzwD1+WNOY9eOb5ZygyK9i85cNQGODUX y/Fj8OLWbAL1K3xCRApIyU2N9kiHi9dIzBIsG6S8IXVnnkwpYdb0yucz5WLW2fIlLRkx JpfhJ3HiUz+hM4Egf0rqrONLfKwBMDThGHI6XbnnNaoIjSObHEvmgSEJtEPDseLtxm3h mvpw== X-Gm-Message-State: AJIora+Y5XWA/QvErMnaAUwCNZr0vdkGHtNE23eIE/vkQ3NQHzIPddXz dTEaEB5IAZZ25kACAknxbfF1xMEdo2W8O6TMrfA= X-Google-Smtp-Source: AGRyM1tzu+3AzuxODzsDz0fTkt4D3MJrh4JVl46sReB+6FydH/XA2xA4YlnzTvqZs2YWZv6W6ToQAQT8xbNcrId1UFQ= X-Received: by 2002:a0d:eb0b:0:b0:317:ab2f:a8ec with SMTP id u11-20020a0deb0b000000b00317ab2fa8ecmr5734330ywe.473.1656530400962; Wed, 29 Jun 2022 12:20:00 -0700 (PDT) MIME-Version: 1.0 References: <20220628152717.17838-1-goldstein.w.n@gmail.com> In-Reply-To: From: Noah Goldstein Date: Wed, 29 Jun 2022 12:19:50 -0700 Message-ID: Subject: Re: [PATCH v1 1/2] x86: Add comment explaining no Slow_SSE4_2 check in ifunc-sse4_2 To: "H.J. Lu" Cc: GNU C Library , "Carlos O'Donell" Content-Type: text/plain; charset="UTF-8" X-Spam-Status: No, score=-9.5 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-List-Received-Date: Wed, 29 Jun 2022 19:20:04 -0000 On Wed, Jun 29, 2022 at 11:54 AM H.J. Lu wrote: > > On Tue, Jun 28, 2022 at 8:27 AM Noah Goldstein wrote: > > > > 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 | 6 +++++- > > 1 file changed, 5 insertions(+), 1 deletion(-) > > > > diff --git a/sysdeps/x86_64/multiarch/ifunc-sse4_2.h b/sysdeps/x86_64/multiarch/ifunc-sse4_2.h > > index ee36525bcf..204c4b5406 100644 > > --- a/sysdeps/x86_64/multiarch/ifunc-sse4_2.h > > +++ b/sysdeps/x86_64/multiarch/ifunc-sse4_2.h > > @@ -27,7 +27,11 @@ IFUNC_SELECTOR (void) > > { > > const struct cpu_features* cpu_features = __get_cpu_features (); > > > > - if (CPU_FEATURE_USABLE_P (cpu_features, SSE4_2)) > > + /* This function uses slow sse4.2 instructions (pcmpstri) but since > > + there is no other optimized implementation keep using. If an > > + optimized fallback is added add a X86_ISA_CPU_FEATURE_USABLE_P > > + (cpu_features, SSE4_2) check. */ > > Did you mean Slow_SSE4_2? Yes. Will fix for V2. > > > + if (ISA_CPU_FEATURE_USABLE_P (cpu_features, SSE4_2)) > > return OPTIMIZE (sse42); > > > > return OPTIMIZE (generic); > > -- > > 2.34.1 > > > > > -- > H.J.