From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8EF08C73C41 for ; Tue, 9 Jul 2019 13:38:48 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id D8FFC20861 for ; Tue, 9 Jul 2019 13:38:47 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D8FFC20861 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.crashing.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 45jk1K0Hq6zDqXs for ; Tue, 9 Jul 2019 23:38:45 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=permerror (mailfrom) smtp.mailfrom=kernel.crashing.org (client-ip=63.228.1.57; helo=gate.crashing.org; envelope-from=segher@kernel.crashing.org; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=kernel.crashing.org Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 45jjy56MkwzDqVN for ; Tue, 9 Jul 2019 23:35:57 +1000 (AEST) Received: from gate.crashing.org (localhost.localdomain [127.0.0.1]) by gate.crashing.org (8.14.1/8.14.1) with ESMTP id x69DZgCw003161; Tue, 9 Jul 2019 08:35:42 -0500 Received: (from segher@localhost) by gate.crashing.org (8.14.1/8.14.1/Submit) id x69DZfPa003160; Tue, 9 Jul 2019 08:35:41 -0500 X-Authentication-Warning: gate.crashing.org: segher set sender to segher@kernel.crashing.org using -f Date: Tue, 9 Jul 2019 08:35:40 -0500 From: Segher Boessenkool To: Christophe Leroy Subject: Re: [PATCH v2] powerpc: slightly improve cache helpers Message-ID: <20190709133540.GJ30355@gate.crashing.org> References: <45hnfp6SlLz9sP0@ozlabs.org> <20190708191416.GA21442@archlinux-threadripper> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.4.2.3i X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com, Paul Mackerras , Nathan Chancellor , linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Tue, Jul 09, 2019 at 07:04:43AM +0200, Christophe Leroy wrote: > Le 08/07/2019 à 21:14, Nathan Chancellor a écrit : > >On Mon, Jul 08, 2019 at 11:19:30AM +1000, Michael Ellerman wrote: > >>On Fri, 2019-05-10 at 09:24:48 UTC, Christophe Leroy wrote: > >>>Cache instructions (dcbz, dcbi, dcbf and dcbst) take two registers > >>>that are summed to obtain the target address. Using 'Z' constraint > >>>and '%y0' argument gives GCC the opportunity to use both registers > >>>instead of only one with the second being forced to 0. > >>> > >>>Suggested-by: Segher Boessenkool > >>>Signed-off-by: Christophe Leroy > >> > >>Applied to powerpc next, thanks. > >> > >>https://git.kernel.org/powerpc/c/6c5875843b87c3adea2beade9d1b8b3d4523900a > >> > >>cheers > > > >This patch causes a regression with clang: > > Is that a Clang bug ? I would think so, but cannot tell from the given information. > Do you have a disassembly of the code both with and without this patch > in order to compare ? That's what we need to start debugging this, yup. > Segher, any idea ? There is nothing I recognise, no. Segher