From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 9049 invoked by alias); 13 Oct 2009 14:53:53 -0000 Received: (qmail 9038 invoked by uid 22791); 13 Oct 2009 14:53:52 -0000 X-SWARE-Spam-Status: No, hits=-2.6 required=5.0 tests=AWL,BAYES_00,SPF_HELO_PASS,SPF_PASS X-Spam-Check-By: sourceware.org Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Tue, 13 Oct 2009 14:53:44 +0000 Received: from int-mx02.intmail.prod.int.phx2.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id n9DErYQA003622; Tue, 13 Oct 2009 10:53:35 -0400 Received: from omfg.slc.redhat.com (ovpn01.gateway.prod.ext.phx2.redhat.com [10.5.9.1]) by int-mx02.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id n9DErX7c028225; Tue, 13 Oct 2009 10:53:34 -0400 Message-ID: <4AD49480.7000806@redhat.com> Date: Tue, 13 Oct 2009 15:15:00 -0000 From: Jeff Law User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.1.1) Gecko/20090814 Fedora/3.0-2.6.b3.fc11 Thunderbird/3.0b3 MIME-Version: 1.0 To: Paul Brook CC: gcc@gcc.gnu.org, Michael Matz , Richard Guenther , Jan Hubicka , Toon Moene , Jan Hubicka Subject: Re: LTO and the inlining of functions only called once. References: <4AD0681E.5040200@moene.org> <4AD3D7EE.6070000@redhat.com> <200910131041.39947.paul@codesourcery.com> In-Reply-To: <200910131041.39947.paul@codesourcery.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-IsSubscribed: yes Mailing-List: contact gcc-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-owner@gcc.gnu.org X-SW-Source: 2009-10/txt/msg00282.txt.bz2 On 10/13/09 03:41, Paul Brook wrote: >> Nothing you've said changes the fact that there are a class of users >> for whom that information is vital and we ought to spend some time >> thinking about how to provide the information in a form they can >> digest. GCC dumps as they exist today are largely useless for a non-GCC >> developer to use to understand why a particular transformation did or >> did not occur in their code. This has come up time and time again and >> will continue to do so unless we find a way to provide visibility into >> the optimizer's decision making. >> > My guess is anyone inspecting the code and optimizer decisions at this level > is also going to want to strongarm the result they want when the compiler > makes the "wrong" decision. i.e. detailed unroller diagnostics are only of > limited use without (say) #pragma unroll. > Perhaps. Of course in this customer's case they're looking at 20%+ hits, so a "wrong" decision is quite costly. At least with the inliner they have a fair number of knobs they can turn once they know which heuristic is preventing inlining the key function(s) -- for other passes we don't have nearly as many knobs. jeff