From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 4570 invoked by alias); 18 Dec 2007 16:44:28 -0000 Received: (qmail 4563 invoked by uid 22791); 18 Dec 2007 16:44:28 -0000 X-Spam-Check-By: sourceware.org Received: from mx1.redhat.com (HELO mx1.redhat.com) (66.187.233.31) by sourceware.org (qpsmtpd/0.31) with ESMTP; Tue, 18 Dec 2007 16:44:20 +0000 Received: from int-mx1.corp.redhat.com (int-mx1.corp.redhat.com [172.16.52.254]) by mx1.redhat.com (8.13.8/8.13.1) with ESMTP id lBIGiHpF015280 for ; Tue, 18 Dec 2007 11:44:18 -0500 Received: from zebedee.littlepinkcloud.COM (vpn-14-10.rdu.redhat.com [10.11.14.10]) by int-mx1.corp.redhat.com (8.13.1/8.13.1) with ESMTP id lBIGiFhs009153; Tue, 18 Dec 2007 11:44:17 -0500 Received: from littlepinkcloud.COM (localhost.localdomain [127.0.0.1]) by zebedee.littlepinkcloud.COM (8.13.8/8.13.5) with ESMTP id lBIGi8Ka030545; Tue, 18 Dec 2007 16:44:10 GMT Received: (from aph@localhost) by littlepinkcloud.COM (8.13.8/8.13.5/Submit) id lBIGi7TX030542; Tue, 18 Dec 2007 16:44:07 GMT MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <18279.63703.961312.470807@zebedee.pink> Date: Tue, 18 Dec 2007 17:04:00 -0000 From: Andrew Haley To: Robert Dewar Cc: Ian Lance Taylor , Alexandre Oliva , gcc@gcc.gnu.org Subject: Re: Designs for better debug info in GCC In-Reply-To: <4767F60A.5060505@adacore.com> References: <4737BF2C.70408@codesourcery.com> <47388599.2040701@codesourcery.com> <4749DE66.1090602@codesourcery.com> <4756B02D.9010302@google.com> <4aca3dc20712151903r46c9eceane35edb92d08240ac@mail.gmail.com> <4aca3dc20712161712w1133fb96qd66be0e9a0bb1716@mail.gmail.com> <4766B8E5.60500@google.com> <4766DF5C.1020802@google.com> <47671BF4.5050704@google.com> <4767F3B4.4020709@adacore.com> <18279.62756.166164.494778@zebedee.pink> <4767F60A.5060505@adacore.com> X-Mailer: VM 7.19 under Emacs 22.0.93.1 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: 2007-12/txt/msg00530.txt.bz2 Robert Dewar writes: > Andrew Haley wrote: > = > > > I don't think it is fine, we have constant complaints from our > > > users about this. I think we definitely need an optimization > > > level that avoids this. > > > > Short of putting a barrier at every sequence point, how would you stop > > the debugger from jumping all over the place? I'm assuming that you > > do want the debugger to show what is actually going on, not fake it. > > Note that putting a barrier at every sequence point is exactly what > Geert proposed, and I think we really need an optimization level > that does the equivalent of this. It is also needed for effective > source-object traceability for certification purposes. Yes, you > can use -O0, but the trouble is that we generate so much rubbish > at this level, much worse than commpetitive compilers with "optimization > off", and the shear amount of object code makes the traceability > analysis harder (and makes executables unnecessarily huge). I agree. It's a really interesting idea and should be fairly easy to prototype. Andrew. -- Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SL4 1TE, UK Registered in England and Wales No. 3798903