From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 16416 invoked by alias); 8 Nov 2007 00:35:07 -0000 Received: (qmail 16272 invoked by uid 22791); 8 Nov 2007 00:35:03 -0000 X-Spam-Check-By: sourceware.org Received: from mail.codesourcery.com (HELO mail.codesourcery.com) (65.74.133.4) by sourceware.org (qpsmtpd/0.31) with ESMTP; Thu, 08 Nov 2007 00:35:00 +0000 Received: (qmail 14358 invoked from network); 8 Nov 2007 00:34:58 -0000 Received: from unknown (HELO ?192.168.0.2?) (mitchell@127.0.0.2) by mail.codesourcery.com with ESMTPA; 8 Nov 2007 00:34:58 -0000 Message-ID: <473259AA.1070400@codesourcery.com> Date: Thu, 08 Nov 2007 05:01:00 -0000 From: Mark Mitchell User-Agent: Thunderbird 2.0.0.6 (Windows/20070728) MIME-Version: 1.0 To: David Edelsohn CC: Ian Lance Taylor , Alexandre Oliva , Richard Guenther , gcc-patches@gcc.gnu.org, gcc@gcc.gnu.org Subject: Re: Designs for better debug info in GCC References: <84fc9c000711050327x74845c78ya18a3329fcf9e4d2@mail.gmail.com> <4732519C.6070802@codesourcery.com> <200711080014.lA80EEiA028452@makai.watson.ibm.com> In-Reply-To: <200711080014.lA80EEiA028452@makai.watson.ibm.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit 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/msg00226.txt.bz2 David Edelsohn wrote: >>>>>> Mark Mitchell writes: > > Mark> I think we all agree that providing better debugging of optimized code > Mark> is a priori a good thing. So, as I see it, this thread is focused on > Mark> what internal representation we might use for that. > > Yes, it is a good thing, but not at any price. Regardless of the > representation and implementation, there is a cost. This discussion > should not start with the premise that better debugging of optimized code > is better at any cost. I agree. You're right to state this explicitly, but I'd implicitly expected that we'd do cost/benefit analysis on this feature, as we would any other. > Mark> I'd like to start by > Mark> capturing the functional changes that we want to make to GCC's debug > Mark> output -- not the changes that we want in the debug experience, or > Mark> changes that we need in GDB, but the changes in the generated DWARF. > > Who is "we"? What better debugging are GCC users demanding? What > debugging difficulties are they experiencing? Who is that set of users? > What functional changes would improve those cases? What is the cost of > those improvements in complexity, maintainability, compile time, object > file size, GDB start-up time, etc.? That's what I'm asking. First and foremost, I want to know what, concretely, Alexandre is trying to achieve, beyond "better debugging info for optimized code". Until we understand that, I don't see how we can sensibly debate any methods of implementation, possible costs, etc. -- Mark Mitchell CodeSourcery mark@codesourcery.com (650) 331-3385 x713