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=-8.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, 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 4A50EC433E7 for ; Wed, 14 Oct 2020 15:17:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B4C3521582 for ; Wed, 14 Oct 2020 15:17:05 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=firstfloor.org header.i=@firstfloor.org header.b="qCbCansO" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731153AbgJNPRF (ORCPT ); Wed, 14 Oct 2020 11:17:05 -0400 Received: from one.firstfloor.org ([193.170.194.197]:35812 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726006AbgJNPRE (ORCPT ); Wed, 14 Oct 2020 11:17:04 -0400 Received: by one.firstfloor.org (Postfix, from userid 503) id 3DE1B86865; Wed, 14 Oct 2020 17:17:01 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=firstfloor.org; s=mail; t=1602688622; bh=lck1LuufIBM08kr6f8nMZydijZUoUFzj7ULXVQX9vZc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=qCbCansOUz92qlcokuAWL7zxb95GWk3z0DH2xYt+LXJfeTF357kz4p5UqiZdheRUE 4ZR0jtzDgObeRz7fbceJ6QtaqYMVdc0+aa8GTWH8zKpfgvBaVBhYKUeZVOQqUdjzVJ +rk/sA3Hd8Jsy7Ukxp9rKelJaCk8N7qROdNftueQ= Date: Wed, 14 Oct 2020 08:17:01 -0700 From: Andi Kleen To: Mark Wielaard Cc: linux-kernel@vger.kernel.org, Masahiro Yamada , Michal Marek , linux-kbuild@vger.kernel.org, Ian Rogers , linux-toolchains@vger.kernel.org, Andi Kleen , Nick Desaulniers , Segher Boessenkool , Florian Weimer Subject: Re: [PATCH] Only add -fno-var-tracking-assignments workaround for old GCC versions. Message-ID: <20201014151701.vl3gh5e5teb2hqj7@two.firstfloor.org> References: <20201014110132.2680-1-mark@klomp.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201014110132.2680-1-mark@klomp.org> User-Agent: NeoMutt/20170113 (1.7.2) Precedence: bulk List-ID: X-Mailing-List: linux-toolchains@vger.kernel.org On Wed, Oct 14, 2020 at 01:01:32PM +0200, 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. Add ... This allows various tools such as a perf probe or gdb debuggers or systemtap to resolve variable locations using dwarf locations in more code. > > Signed-off-by: Mark Wielaard > Acked-by: Ian Rogers > Cc: linux-toolchains@vger.kernel.org > Cc: Andi Kleen > Cc: Nick Desaulniers > Cc: Segher Boessenkool > Cc: Florian Weimer Reviewed-by: Andi Kleen -Andi