From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 14741 invoked by alias); 29 Jun 2005 06:59:18 -0000 Mailing-List: contact gcc-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Archive: List-Post: List-Help: Sender: gcc-owner@gcc.gnu.org Received: (qmail 14714 invoked by uid 22791); 29 Jun 2005 06:59:14 -0000 Received: from mx-out.tiscali.fr (HELO mail.libertysurf.net) (213.36.80.91) by sourceware.org (qpsmtpd/0.30-dev) with ESMTP; Wed, 29 Jun 2005 06:59:14 +0000 Received: from dyn-83-156-220-187.ppp.tiscali.fr (83.156.220.187) by mail.libertysurf.net (7.1.026) id 42A31B400049A1CF; Wed, 29 Jun 2005 08:59:11 +0200 From: Eric Botcazou To: Falk Hueffner Subject: Re: signed is undefined and has been since 1992 (in GCC) Date: Wed, 29 Jun 2005 06:59:00 -0000 User-Agent: KMail/1.7.1 Cc: gcc@gcc.gnu.org, "Joseph S. Myers" , Robert Dewar References: <20050628142441.GA52889@dspnet.fr.eu.org> <87zmta6scr.fsf@debian.org> In-Reply-To: <87zmta6scr.fsf@debian.org> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200506290859.31724.ebotcazou@libertysurf.fr> X-SW-Source: 2005-06/txt/msg01235.txt.bz2 > > Does -ftrapv ever take advantage of trapping instructions where the > > hardware has them available? > > Yes, for example Alpha. OK, but it's the only example. :-) > > Does anyone make substantial use of -ftrapv in production > > There are rarely bug reports about it; for example pointer difference > with odd sized objects was broken for years, and reported only twice > or so. -ftrapv is simply not usable as of today because the performance degradation is abysmal. Plus it is broken in very simple cases (PR middle-end/19020). -- Eric Botcazou