From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 7513 invoked by alias); 19 Dec 2007 20:00:00 -0000 Received: (qmail 7497 invoked by uid 22791); 19 Dec 2007 19:59:59 -0000 X-Spam-Check-By: sourceware.org Received: from mx2.redhat.com (HELO mx2.redhat.com) (66.187.237.31) by sourceware.org (qpsmtpd/0.31) with ESMTP; Wed, 19 Dec 2007 19:59:53 +0000 Received: from int-mx1.corp.redhat.com (int-mx1.corp.redhat.com [172.16.52.254]) by mx2.redhat.com (8.13.8/8.13.8) with ESMTP id lBJJvEZA026124; Wed, 19 Dec 2007 14:57:14 -0500 Received: from pobox.corp.redhat.com (pobox.corp.redhat.com [10.11.255.20]) by int-mx1.corp.redhat.com (8.13.1/8.13.1) with ESMTP id lBJJvETt004825; Wed, 19 Dec 2007 14:57:14 -0500 Received: from livre.oliva.athome.lsd.ic.unicamp.br (vpn-14-186.rdu.redhat.com [10.11.14.186]) by pobox.corp.redhat.com (8.13.1/8.13.1) with ESMTP id lBJJvD5Z027519; Wed, 19 Dec 2007 14:57:13 -0500 Received: from livre.oliva.athome.lsd.ic.unicamp.br (localhost.localdomain [127.0.0.1]) by livre.oliva.athome.lsd.ic.unicamp.br (8.14.2/8.14.1) with ESMTP id lBJJvCU0024567; Wed, 19 Dec 2007 17:57:12 -0200 Received: (from aoliva@localhost) by livre.oliva.athome.lsd.ic.unicamp.br (8.14.2/8.14.1/Submit) id lBJJvCj9024566; Wed, 19 Dec 2007 17:57:12 -0200 To: "Daniel Berlin" Cc: "Diego Novillo" , "Mark Mitchell" , "Robert Dewar" , "Ian Lance Taylor" , "Richard Guenther" , gcc-patches@gcc.gnu.org, gcc@gcc.gnu.org Subject: Re: Designs for better debug info in GCC References: <4766DF5C.1020802@google.com> <47671BF4.5050704@google.com> <4aca3dc20712181415y3d5c3717s6d73b1335b311313@mail.gmail.com> <4aca3dc20712182207y648f7bbhab9e0af8ad2ff832@mail.gmail.com> <4aca3dc20712190759g748d6e15pa0e5146c3f5ca0ba@mail.gmail.com> From: Alexandre Oliva Errors-To: aoliva@oliva.athome.lsd.ic.unicamp.br Date: Wed, 19 Dec 2007 20:00:00 -0000 In-Reply-To: <4aca3dc20712190759g748d6e15pa0e5146c3f5ca0ba@mail.gmail.com> (Daniel Berlin's message of "Wed\, 19 Dec 2007 10\:59\:41 -0500") Message-ID: User-Agent: Gnus/5.11 (Gnus v5.11) Emacs/22.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii 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: 2007-12/txt/msg00590.txt.bz2 On Dec 19, 2007, "Daniel Berlin" wrote: > Here is the easy one: > z_5 = a_3 + b_3 > x_4 = z_5 + c_3 > DEBUG(x, x_4) > Reassoc may transform this into: > z_5 = c_3 + b_3 > x_4 = z_5 + a_3 > DEBUG(x, x_4) > Now x has the wrong value. As Andrew said, no, it doesn't. Now, if z_5 were present in a debug expression, then it would need adjusting. No different from the adjusting need for any other instruction in which z_5 was present, though. That's what I mean when I talk about letting the optimizers do their job on debug instructions too. -- Alexandre Oliva http://www.lsd.ic.unicamp.br/~oliva/ FSF Latin America Board Member http://www.fsfla.org/ Red Hat Compiler Engineer aoliva@{redhat.com, gcc.gnu.org} Free Software Evangelist oliva@{lsd.ic.unicamp.br, gnu.org}