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=-17.4 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_IN_DEF_DKIM_WL 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 8C181C43457 for ; Mon, 12 Oct 2020 18:59:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4AF4720870 for ; Mon, 12 Oct 2020 18:59:46 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="qRsaQDlK" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730847AbgJLS7p (ORCPT ); Mon, 12 Oct 2020 14:59:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52376 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730787AbgJLS7p (ORCPT ); Mon, 12 Oct 2020 14:59:45 -0400 Received: from mail-pf1-x444.google.com (mail-pf1-x444.google.com [IPv6:2607:f8b0:4864:20::444]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F3431C0613D1 for ; Mon, 12 Oct 2020 11:59:44 -0700 (PDT) Received: by mail-pf1-x444.google.com with SMTP id f19so14366157pfj.11 for ; Mon, 12 Oct 2020 11:59:44 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=XdWH9D9M3/U9qxVAleAUiYrGS3wE2xPiVDjiH/su/+M=; b=qRsaQDlKwkVRsOu5VN5rMGyty+hbdZMaLwM/L1PjRUHFc52xtzXjVsz3FGbPxZQvaD F7znPPdLv9DSUL5A3cAcmm3/sC6YxvbAZysY5UV4KXSrrc5OLjpcML4I+lEgY5CLHUwf 3wYxkWDqsENblUt2EkWv5aCAYbLF9ybGtbvn9Eakx0ufjX6f0LROr+iWA+5sXemXXCrv /7Z4TBx1W7BjPHpgIjBItVc+w6dYfCxbJomNRbDB/JQGMbV/fFqx3hhdLUmht/3RKAM0 gKScA1ZdHvMa6rrt54P0PYg8nM2Vu9JjDgrAGBrBdRhZ8Y+8fWcNNicKHU069E5fKoeJ h4mw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=XdWH9D9M3/U9qxVAleAUiYrGS3wE2xPiVDjiH/su/+M=; b=dG8Q6j657+AC8xcBos19yWFIkbgOkqCDiNT5cCVJ4MbgI1kULs2xISIfqOpYYo57vg Idtkt1rx6k+hPpqE/FzvhJ5J+GK0gtsm1pNnPvG5yxSodi7SkXnf/vQe10JxryENj/lI /FTjyWlyQ6LchIjLnlxOQyvcAteYxT19xUz4E/GdIYmic204Yaa194OsPyGiis92dKAB zyZVrZ+eEhOHW210LVALfi4iTNHafLsi8LzdfHaiEpf1wPL8a7/tK9lX5uFx8enOzrTW zSL4kmSFy6XTUtlm0a7KEQQGmpRmy3Rhv/fzLOtjERsoUHkTlHXIvVhZD9eBV+o8ZlS1 X1Sg== X-Gm-Message-State: AOAM531rojJnwubZEpT3GjRnNNXbEvhYf3n5dYocG8j0Q5o2JaTPYGaM PsswVaI9NKWEFZ/fsY60COpaEB3ucl5t6qYSQs53yA== X-Google-Smtp-Source: ABdhPJz1IQDkXAJH3Ol4Ru15l2xlErlBPjjgPdwZufZsOzipmONg/Wto5Z1aTHyNCIPXWyDlVyXW5RTXdoeTeypKpyA= X-Received: by 2002:a17:90a:6b04:: with SMTP id v4mr21936098pjj.101.1602529184203; Mon, 12 Oct 2020 11:59:44 -0700 (PDT) MIME-Version: 1.0 References: <20201010215135.GB2666@wildebeest.org> <20201010220712.5352-1-mark@klomp.org> In-Reply-To: From: Nick Desaulniers Date: Mon, 12 Oct 2020 11:59:33 -0700 Message-ID: Subject: Re: [PATCH] Only add -fno-var-tracking-assignments workaround for old GCC versions. To: Ian Rogers Cc: Mark Wielaard , Andi Kleen , linux-toolchains@vger.kernel.org, LKML , Peter Zijlstra , Stephane Eranian , Arnaldo Carvalho de Melo , Ingo Molnar , Jiri Olsa , Namhyung Kim , "Phillips, Kim" , Mark Rutland , Masami Hiramatsu Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Oct 10, 2020 at 3:57 PM Ian Rogers wrote: > > On Sat, Oct 10, 2020 at 3:08 PM Mark Wielaard wrote: > > > > Some old GCC versions between 4.5.0 and 4.9.1 might miscompile code > > with -fvar-tracking-assingments (which is enabled by default with -g -O2). > > commit 2062afb4f added -fno-var-tracking-assignments unconditionally to > > work around this. But newer versions of GCC no longer have this bug, so > > only add it for versions of GCC before 5.0. > > > > Signed-off-by: Mark Wielaard > > Acked-by: Ian Rogers > > Thanks, > Ian > > > --- > > Makefile | 4 +++- > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > diff --git a/Makefile b/Makefile > > index f84d7e4ca0be..4f4a9416a87a 100644 > > --- a/Makefile > > +++ b/Makefile > > @@ -813,7 +813,9 @@ KBUILD_CFLAGS += -ftrivial-auto-var-init=zero > > KBUILD_CFLAGS += -enable-trivial-auto-var-init-zero-knowing-it-will-be-removed-from-clang > > endif > > > > -DEBUG_CFLAGS := $(call cc-option, -fno-var-tracking-assignments) > > +# Workaround https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61801 > > +# for old versions of GCC. > > +DEBUG_CFLAGS := $(call cc-ifversion, -lt, 0500, $(call cc-option, -fno-var-tracking-assignments)) Should this be wrapped in: `ifdef CONFIG_CC_IS_GCC`/`endif`? > > > > ifdef CONFIG_DEBUG_INFO > > ifdef CONFIG_DEBUG_INFO_SPLIT > > -- > > 2.18.4 > > -- Thanks, ~Nick Desaulniers