From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 10657 invoked by alias); 22 Nov 2007 19:40:09 -0000 Received: (qmail 10582 invoked by uid 22791); 22 Nov 2007 19:40:08 -0000 X-Spam-Check-By: sourceware.org Received: from py-out-1112.google.com (HELO py-out-1112.google.com) (64.233.166.181) by sourceware.org (qpsmtpd/0.31) with ESMTP; Thu, 22 Nov 2007 19:40:03 +0000 Received: by py-out-1112.google.com with SMTP id a29so9658294pyi for ; Thu, 22 Nov 2007 11:40:01 -0800 (PST) Received: by 10.65.133.8 with SMTP id k8mr20259244qbn.1195760400288; Thu, 22 Nov 2007 11:40:00 -0800 (PST) Received: by 10.65.203.6 with HTTP; Thu, 22 Nov 2007 11:40:00 -0800 (PST) Message-ID: <84fc9c000711221140o3e32ec65i913ce2fd60666588@mail.gmail.com> Date: Fri, 23 Nov 2007 02:30:00 -0000 From: "Richard Guenther" To: "Frank Ch. Eigler" Subject: Re: Designs for better debug info in GCC Cc: "Mark Mitchell" , "David Edelsohn" , "Ian Lance Taylor" , "Alexandre Oliva" , gcc-patches@gcc.gnu.org, gcc@gcc.gnu.org In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <84fc9c000711050327x74845c78ya18a3329fcf9e4d2@mail.gmail.com> <4732519C.6070802@codesourcery.com> <200711080014.lA80EEiA028452@makai.watson.ibm.com> <473259AA.1070400@codesourcery.com> 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/msg00575.txt.bz2 On Nov 22, 2007 8:22 PM, Frank Ch. Eigler wrote: > > Mark Mitchell writes: > > > [...] > >> 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. > > It may be asking to belabour the obvious. GCC users do not want to > have to compile with "-O0 -g" just to debug during development (or > during crash analysis *after deployment*!). Developers would like to > be able to place breakpoints anywhere by reference to the source code, > and would like to access any variables logically present there. > Developers will accept that optimized code will by its nature make > some of these fuzzy, but incorrect data must be and incomplete data > should be minimized. > > That they put up with the status quo at all is a historical artifact > of being told so long not to expect any better. As it is (without serious overhead) impossible to do both, you either have to live with possibly incorrect but elaborate or incomplete but correct debug information for optimized code. Choose one ;) What we (Matz and myself) are trying to do is provide elaborate debug information with the chance of wrong (I'd call it superflous, or extra) debug information. Alexandre seems to aim at the world-domination solution (with the serious overhead in terms of implementation and verboseness). Richard.