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=ham 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 41C86C73C41 for ; Tue, 9 Jul 2019 13:36:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1978D20844 for ; Tue, 9 Jul 2019 13:36:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726792AbfGINgK (ORCPT ); Tue, 9 Jul 2019 09:36:10 -0400 Received: from gate.crashing.org ([63.228.1.57]:57459 "EHLO gate.crashing.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725947AbfGINgK (ORCPT ); Tue, 9 Jul 2019 09:36:10 -0400 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 Cc: Nathan Chancellor , Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com 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 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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