From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 12337 invoked by alias); 28 Jun 2005 22:09:38 -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 12313 invoked by uid 22791); 28 Jun 2005 22:09:29 -0000 Received: from dumbledore.codesourcery.com (HELO mail.codesourcery.com) (65.74.133.11) by sourceware.org (qpsmtpd/0.30-dev) with ESMTP; Tue, 28 Jun 2005 22:09:29 +0000 Received: (qmail 15922 invoked from network); 28 Jun 2005 22:09:27 -0000 Received: from unknown (HELO digraph.polyomino.org.uk) (joseph@127.0.0.2) by mail.codesourcery.com with ESMTPA; 28 Jun 2005 22:09:27 -0000 Received: from jsm28 (helo=localhost) by digraph.polyomino.org.uk with local-esmtp (Exim 4.51) id 1DnOGj-00046Q-Kn; Tue, 28 Jun 2005 22:09:25 +0000 Date: Tue, 28 Jun 2005 22:09:00 -0000 From: "Joseph S. Myers" X-X-Sender: jsm28@digraph.polyomino.org.uk To: Robert Dewar cc: 'gcc mailing list' Subject: Re: signed is undefined and has been since 1992 (in GCC) In-Reply-To: <42C1A23F.6000806@adacore.com> Message-ID: References: <20050628142441.GA52889@dspnet.fr.eu.org> <20050628145148.GD52889@dspnet.fr.eu.org> <17089.26325.169281.749633@zapata.pink> <20050628171752.GE52889@dspnet.fr.eu.org> <42C19BE8.9050107@adacore.com> <42C1A23F.6000806@adacore.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-SW-Source: 2005-06/txt/msg01213.txt.bz2 On Tue, 28 Jun 2005, Robert Dewar wrote: > are preserved. For instance on the IBM mainframe one might use signed > or unsigned operations to implement int operations. On the original > MIPS one might use trapping or non-trapping arithmetic (either would > be valid). Does -ftrapv ever take advantage of trapping instructions where the hardware has them available? Does anyone make substantial use of -ftrapv in production (whether as a tool for detecting bugs, or as a security tool where the performance cost is acceptable)? Or is it still at the stage of being a tool which would be useful in principle for some purposes but still needs some work (including on optimizing checks to reduce the performance cost) to make it useful in practice? -- Joseph S. Myers http://www.srcf.ucam.org/~jsm28/gcc/ jsm@polyomino.org.uk (personal mail) joseph@codesourcery.com (CodeSourcery mail) jsm28@gcc.gnu.org (Bugzilla assignments and CCs)