From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-yw1-x1129.google.com (mail-yw1-x1129.google.com [IPv6:2607:f8b0:4864:20::1129]) by sourceware.org (Postfix) with ESMTPS id A97AA38582AD for ; Thu, 30 Jun 2022 03:09:47 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org A97AA38582AD Received: by mail-yw1-x1129.google.com with SMTP id 00721157ae682-31772f8495fso166595117b3.4 for ; Wed, 29 Jun 2022 20:09:47 -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=qPbqHqVgO60v0fIcTVnSKJq2hLi/drnVbCxVfIAuk1k=; b=OBJw+M0XQklg6BDW6DOZhY07JalC70AOqtMSh/Zr3iEexz/1bJ98XQxKJDIPjzIk92 EO5Cd4NShV8mblnQTVk5QChaeuUs1irjG9Bf7Enwp1768LELuCue1HH0tvMb8Kp3kEvH F7G3lN6Zky6iQrDDhzUlPl3X/fdEcva9AE+ok791zaKUve4mmfTtWN1xb6KVsQSFlgiW K9R5x4FROEUsENDTcTci4faWZOzzHzQuKEGp8gRG0X1M7M1uo4YwsG3DK/Q5jbNgBd98 5wSl+zlDTWZI9/5v/4Wpe2su11hpBg0RNs6/6Umplvm4Arkpgzta9DzI6NAQ/K/RWazk 3Hag== X-Gm-Message-State: AJIora9EU1zIEIb/QIK1jk166vjwk7F1BCdbIIiRLE82bUTho2do80tw kdNqvj1/zuqpPRhBJX5wkak4JZQ8MGK/YiM8C/AljWE3bb0= X-Google-Smtp-Source: AGRyM1sjdLExjEFDzEtUGgmTNtnx4WYRK0nqgtO/Wkotcp5T+8WWP502amTH7Zhes/YineBio/XzRTIBgswtjqXGi1o= X-Received: by 2002:a0d:e28f:0:b0:317:89cb:b1ff with SMTP id l137-20020a0de28f000000b0031789cbb1ffmr7888760ywe.288.1656558587137; Wed, 29 Jun 2022 20:09:47 -0700 (PDT) MIME-Version: 1.0 References: <20220628152717.17838-1-goldstein.w.n@gmail.com> <20220629220552.1241553-1-goldstein.w.n@gmail.com> In-Reply-To: From: Noah Goldstein Date: Wed, 29 Jun 2022 20:09:36 -0700 Message-ID: Subject: Re: [PATCH v2 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=-8.9 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: Thu, 30 Jun 2022 03:09:49 -0000 On Wed, Jun 29, 2022 at 3:13 PM H.J. Lu wrote: > > On Wed, Jun 29, 2022 at 3:05 PM 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..973041d23b 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_ARCH_P > > + (cpu_features, Slow_SSE4_2) check. */ > > + if (ISA_CPU_FEATURE_USABLE_P (cpu_features, SSE4_2)) This was buggy as standalone patch (hidden by the next in series). Resubmitted with fix in V4. > > return OPTIMIZE (sse42); > > > > return OPTIMIZE (generic); > > -- > > 2.34.1 > > > > LGTM. > > Thanks. > > -- > H.J.