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=-13.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL 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 5BFC3C433E6 for ; Fri, 29 Jan 2021 21:49:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 22B9764E10 for ; Fri, 29 Jan 2021 21:49:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233316AbhA2VtG (ORCPT ); Fri, 29 Jan 2021 16:49:06 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50472 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232401AbhA2VtC (ORCPT ); Fri, 29 Jan 2021 16:49:02 -0500 Received: from mail-pl1-x629.google.com (mail-pl1-x629.google.com [IPv6:2607:f8b0:4864:20::629]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E82F4C061574 for ; Fri, 29 Jan 2021 13:48:21 -0800 (PST) Received: by mail-pl1-x629.google.com with SMTP id u11so6034904plg.13 for ; Fri, 29 Jan 2021 13:48:21 -0800 (PST) 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=nDCl0b2Dk+cS7GVWEWeoYxC8mwKbqEi6yIqTF9Oo/qE=; b=eGTW4MG8Pl3TK+TMkm4WglBjmPDuVT8H+GAviEyFrguRE6MRa/GZZU7J398/6ZxFe0 xKPb6fAPxgSfXD/5KNroU2ifvPgvO1IC8xBnFPZzEvffhM+8Q1IErfcPS36GrEAidfn7 mZUNfyj0ahxaGDAbfudWd+sU+mGeZMHZfwwVpRbB+qDyxpH5crTLeJwY1PlaMWn6JFMS NZ0bST5Evxu51geiAxpQM2AAPsjDwei/x21em74ddRcVbmAwrCX90CFifsFs6qZ1MfxK MGUg4o5cVCabYzEtUhZy2YrZ/jRtkSNA0vITi/lAdQbWRMyGdCsUvL40t9Y8gL8BLvub ckIA== 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=nDCl0b2Dk+cS7GVWEWeoYxC8mwKbqEi6yIqTF9Oo/qE=; b=aORyM66Te1eILmYq4R1rITgLa9Iuvd1xzCVBtOSlFN3WrHB061bv017M82ClU+OkfJ SLXmCE8+HIpjc4uvnNQCS5S1U8vK5a2xadE3lSfTjr25YNOuz7yrIqPSaIXKD72MvGSy 75dBOZ9I1m5bxZyi9qOFSg0ct+5PaMzakMnznTYYBROHalmMPdrkpv9nO9zCeJM/H/sH fFcX6EBNXvsT5XmVcRf6YaqLuvTBe5a9tmQfnUHRuYQXSUL/aUAPnLU/D+sCTtdlfzYh kcaIETXluR6rUPWVcz0PGwJc7qHPAO+zVg0hq6QxMtbej8Rei//tN+MmtGCrhPylTQ/f OTzw== X-Gm-Message-State: AOAM533rHMD3e52Y3w4dmlcSFaRtpV2Ba8NDEmhDh5E/XB9CpUJsm38u oTkFXQWppJO6kJxepDlKU4c0CedkpABTN4gKtoyHeg== X-Google-Smtp-Source: ABdhPJyaUQFnwwGfCgFgWXfe9NvNBiQYNFxLJPMiY6STretlJGU4TmCaVSMStJjR790JfgkGm8fCqn5KCHfOCa2LqxE= X-Received: by 2002:a17:90a:8b82:: with SMTP id z2mr6338917pjn.25.1611956901187; Fri, 29 Jan 2021 13:48:21 -0800 (PST) MIME-Version: 1.0 References: <20210121082451.2240540-1-morbo@google.com> <20210122101156.3257143-1-morbo@google.com> In-Reply-To: From: Nick Desaulniers Date: Fri, 29 Jan 2021 13:48:10 -0800 Message-ID: Subject: Re: [PATCH v7] pgo: add clang's Profile Guided Optimization infrastructure To: Sedat Dilek Cc: Bill Wendling , Andrew Morton , Jonathan Corbet , Masahiro Yamada , Linux Doc Mailing List , LKML , Linux Kbuild mailing list , clang-built-linux , Nathan Chancellor , Sami Tolvanen Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jan 28, 2021 at 11:43 PM Sedat Dilek wrote: > > Some comments: > > [ hash mismatches ] > > Observed identical warnings when doing a rebuild with GAS or Clang-IAS. > > [ Importance of LLVM_IAS=1 working ] > > Clang-LTO and Clang-CFI depend both on LLVM_IAS=1 (see for example > "kbuild: add support for Clang LTO"). > Sooner or later we will deal with this issue (hope it is not a local problem). If you're switching back and forth between GAS and IAS, then I would expect a hash error if you're trying to reuse profiling data from one with the other. The profiling data is not portable when switching toolchains between when the profile was collected, and when it was used. -- Thanks, ~Nick Desaulniers