From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 19476 invoked by alias); 5 Dec 2006 21:56:47 -0000 Received: (qmail 19455 invoked by uid 22791); 5 Dec 2006 21:56:46 -0000 X-Spam-Check-By: sourceware.org Received: from nevyn.them.org (HELO nevyn.them.org) (66.93.172.17) by sourceware.org (qpsmtpd/0.31.1) with ESMTP; Tue, 05 Dec 2006 21:56:41 +0000 Received: from drow by nevyn.them.org with local (Exim 4.63) (envelope-from ) id 1GriHH-0007ya-2O; Tue, 05 Dec 2006 16:56:39 -0500 Date: Tue, 05 Dec 2006 21:56:00 -0000 From: Daniel Jacobowitz To: Mark Kettenis Cc: gdb-patches@sourceware.org Subject: Re: PATCH: Initialize tmp_obstack Message-ID: <20061205215639.GA30371@nevyn.them.org> Mail-Followup-To: Mark Kettenis , gdb-patches@sourceware.org References: <20061202182712.GA623@lucon.org> <20061205204003.GB25572@nevyn.them.org> <12601.163.1.150.229.1165354805.squirrel@webmail.xs4all.nl> <20061205214306.GA29801@nevyn.them.org> <20637.163.1.150.229.1165355320.squirrel@webmail.xs4all.nl> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20637.163.1.150.229.1165355320.squirrel@webmail.xs4all.nl> User-Agent: Mutt/1.5.13 (2006-08-11) X-IsSubscribed: yes Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org X-SW-Source: 2006-12/txt/msg00049.txt.bz2 On Tue, Dec 05, 2006 at 10:48:40PM +0100, Mark Kettenis wrote: > Sorry, yes, this was meant to go to the list. My proposal is not to "fix" > this at all. It's a GCC bug, that's presumably fixed, and we'll ship > with -Werror turned off by default anyway. Well, there seem to be enough systems with affected GCC that HJ, Jim, and I all hit it - Ubuntu Edgy is one such. We could discuss this till we're blue in the face without getting anywhere; the uninitialized warnings are not reliable in face of this sort of pattern (isn't it a classical example of why uninitialized warnings are hard?). I think we're being overly optimistic if we expect GCC to get it right all the time. In fact, I asked a bunch of GCC developers about it on IRC and the best response I got was "then you are screwed". Or Diego's explanation: > We don't explicitly try to handle it. it's mostly side-effect of > various optimizations. some times it's jump-threading, others it's > PRE, others it's CCP, others it's VRP. > that irritates the hell out of me. we depend on optimizations for > this warning. I know that's a widely held position. -- Daniel Jacobowitz CodeSourcery