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=-5.1 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no 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 6600EC2D0A3 for ; Fri, 6 Nov 2020 12:38:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D11362071A for ; Fri, 6 Nov 2020 12:38:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="WAJEZpww" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727232AbgKFMiX (ORCPT ); Fri, 6 Nov 2020 07:38:23 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54396 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726939AbgKFMiV (ORCPT ); Fri, 6 Nov 2020 07:38:21 -0500 Received: from mail-wr1-x444.google.com (mail-wr1-x444.google.com [IPv6:2a00:1450:4864:20::444]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 56DA4C0613CF; Fri, 6 Nov 2020 04:38:21 -0800 (PST) Received: by mail-wr1-x444.google.com with SMTP id p8so366664wrx.5; Fri, 06 Nov 2020 04:38:21 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:date:to:cc:subject:in-reply-to:message-id:references :user-agent:mime-version; bh=oJeBlvI7pAnkAsw70khux5ZoE/B4WwO2O42ItTpncKs=; b=WAJEZpwwyivZPgyV6gkLhK0Y/cm6bIad7kY58MOOTMAbjJoZKo0iDiFWuKcjli0joP gc+bfTLQPAg9SP87socW83t/aUHOoTR5RkwijNPW16vWWKOF6rzrZiJYpQvdwZ+wsgGu D7rOJMI/NojscP1nzw2xfqEZ81UmtOQSOGOfRKz5Y6gTgtZqESPFkj3QG5PhGjv5d6Cn uKNrf3voJrN3tlytYswcULxhhRXwFCkKmGS2/UZwTyRjZrUyzQz8RqawV8qq70IoNrqd F6bbtQl8r+roONbnTq6cfe03thF20gW839OV3v7rCEGQDuBGD8D9ci+v5VSxgZnPoSVn XUbQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:date:to:cc:subject:in-reply-to:message-id :references:user-agent:mime-version; bh=oJeBlvI7pAnkAsw70khux5ZoE/B4WwO2O42ItTpncKs=; b=GdLUE+dD9qvhoenjwCcNTz04gYLJO5RQUNyxm2u4ExHQvlUoCi437QeecI+xriSzL1 z5+2Dd1zMZmw/2WdF4FZeZlvQ8Yt5z8bGU4dcg2U7yc1EOKi188o+UnFBsi6Bec6xTSG 0L2o7DITft9n3U+Xkek0nB8BXXSWeaJT+QfOGaqtPh0XiCLCzhn+GxOK1oK5MBXD8Lf9 7eXbJYZi3NQRZuPS2LHU+ZnRdEwznE2FiDqk2lqYwCp6vrV+FoP0I5Dy5EcHox88E5L5 qWEFhX0TruvzVtH5unAJF47kpUAiRHaOevuwa8S66wprF8tVwULxv5opmWqsdWuuGHy+ Nxlw== X-Gm-Message-State: AOAM531W3BBfVl/jg2YWuTF1wKBgz3Uso2pXfM9Plr2lMG55XXZ0hTKU onOUGZD5O8XlP+vpMcZMeEI= X-Google-Smtp-Source: ABdhPJzlriX3iwt1mvdV4n7Fm1xf5GeKZnsqhivtwgEd646SLG0R7IIo49K7n1ZP2ZMZwzI9QXBiww== X-Received: by 2002:adf:dc4b:: with SMTP id m11mr2375463wrj.328.1604666300066; Fri, 06 Nov 2020 04:38:20 -0800 (PST) Received: from felia ([2001:16b8:2d20:9d00:e580:adb5:1ef:950d]) by smtp.gmail.com with ESMTPSA id j9sm1924110wrr.49.2020.11.06.04.38.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 06 Nov 2020 04:38:19 -0800 (PST) From: Lukas Bulwahn X-Google-Original-From: Lukas Bulwahn Date: Fri, 6 Nov 2020 13:38:18 +0100 (CET) X-X-Sender: lukas@felia To: Sudip Mukherjee cc: Lukas Bulwahn , Balbir Singh , Tom Rix , Nathan Chancellor , Nick Desaulniers , clang-built-linux@googlegroups.com, kernel-janitors@vger.kernel.org, linux-safety@lists.elisa.tech, linux-kernel@vger.kernel.org Subject: Re: [linux-safety] [PATCH] taskstats: remove unneeded dead assignment In-Reply-To: Message-ID: References: <20201106062210.27920-1-lukas.bulwahn@gmail.com> <6ab2415b-0642-16ee-4be0-c909e07e7565@codethink.co.uk> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 6 Nov 2020, Sudip Mukherjee wrote: > Hi Lukas, > > On 06/11/2020 10:31, Lukas Bulwahn wrote: > > > > > > On Fri, 6 Nov 2020, Sudip Mukherjee wrote: > > > >> Hi Lukas, > >> > > > > > > > I did not try but I bet (a beverage of your choice) that the object code > > remains the same also for your suggested patch. Try to disprove my claim > > and possibly earn yourself a beverage when we meet... > > Lets decide which beverage.. ;-) > > Using gcc-7.2.0 for MIPS: > > original:- ab81d3305d578c2568fbc73aad2f9e61 kernel/taskstats.o > After your change:- ab81d3305d578c2568fbc73aad2f9e61 kernel/taskstats.o > After my change:- 0acae2c8d72abd3e15bf805fccdca711 kernel/taskstats.o > > Interesting, can you share the diff of the objdump before and after? I bet it found now a different assignment from variables to registers or so; with the beverage at hand, we can then discuss if that is effectively still the same object code or not. Thanks for confirming that my patch here really remains the same compared to before, even on MIPS :) I only checked x86-64... Lukas > > -- > Regards > Sudip > > > -=-=-=-=-=-=-=-=-=-=-=- > Links: You receive all messages sent to this group. > View/Reply Online (#148): https://lists.elisa.tech/g/linux-safety/message/148 > Mute This Topic: https://lists.elisa.tech/mt/78069241/1714638 > Group Owner: linux-safety+owner@lists.elisa.tech > Unsubscribe: https://lists.elisa.tech/g/linux-safety/unsub [lukas.bulwahn@gmail.com] > -=-=-=-=-=-=-=-=-=-=-=- > > >