From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 10893 invoked by alias); 9 Nov 2007 14:23:35 -0000 Received: (qmail 10834 invoked by uid 22791); 9 Nov 2007 14:23:33 -0000 X-Spam-Check-By: sourceware.org Received: from NaN.false.org (HELO nan.false.org) (208.75.86.248) by sourceware.org (qpsmtpd/0.31) with ESMTP; Fri, 09 Nov 2007 14:23:28 +0000 Received: from nan.false.org (localhost [127.0.0.1]) by nan.false.org (Postfix) with ESMTP id BDAE398354; Fri, 9 Nov 2007 14:23:26 +0000 (GMT) Received: from caradoc.them.org (22.svnf5.xdsl.nauticom.net [209.195.183.55]) by nan.false.org (Postfix) with ESMTP id 9854198100; Fri, 9 Nov 2007 14:23:26 +0000 (GMT) Received: from drow by caradoc.them.org with local (Exim 4.68) (envelope-from ) id 1IqUlZ-0000F2-No; Fri, 09 Nov 2007 09:23:25 -0500 Date: Fri, 09 Nov 2007 18:40:00 -0000 From: Daniel Jacobowitz To: gcc-patches@gcc.gnu.org, gcc@gcc.gnu.org Subject: Re: Designs for better debug info in GCC Message-ID: <20071109142325.GA911@caradoc.them.org> Mail-Followup-To: gcc-patches@gcc.gnu.org, gcc@gcc.gnu.org References: <84fc9c000711050327x74845c78ya18a3329fcf9e4d2@mail.gmail.com> <47331636.9010308@adacore.com> <20071109011124.GA32556@synopsys.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20071109011124.GA32556@synopsys.com> User-Agent: Mutt/1.5.15 (2007-04-09) 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: 2007-11/txt/msg00277.txt.bz2 [Can we pick just gcc@ or just gcc-patches@ please?] On Thu, Nov 08, 2007 at 05:11:24PM -0800, Joe Buck wrote: > Debugging would be just as easy and natural if -O0 only made sure that > values of variables are written out to memory at positions where the > user can set a breakpoint; the code doesn't need to preserve every > operation exactly as written, or read variables in from memory that > are already in registers. Kind of an -O0.5 would be more desirable > than what we have now. Careful. Eliminating reads from memory messes up debugger modification of variables, unless you can explain to the debugger that the variable is currently in both locations - this has been discussed but AFAIK there is no representation for it yet. Changing the memory location won't change the next operation that thinks it's in the register. Changing the register will be lost later. -- Daniel Jacobowitz CodeSourcery