From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 7912 invoked by alias); 6 Jan 2015 08:23:23 -0000 Mailing-List: contact gcc-patches-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-patches-owner@gcc.gnu.org Received: (qmail 7896 invoked by uid 89); 6 Jan 2015 08:23:20 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.1 required=5.0 tests=AWL,BAYES_00,SPF_HELO_PASS,SPF_PASS,T_RP_MATCHES_RCVD autolearn=ham version=3.3.2 X-HELO: mx1.redhat.com Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (AES256-GCM-SHA384 encrypted) ESMTPS; Tue, 06 Jan 2015 08:23:19 +0000 Received: from int-mx09.intmail.prod.int.phx2.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id t068NIDe017053 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL) for ; Tue, 6 Jan 2015 03:23:18 -0500 Received: from tucnak.zalov.cz (ovpn-116-64.ams2.redhat.com [10.36.116.64]) by int-mx09.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id t068NGQJ028800 (version=TLSv1/SSLv3 cipher=AES128-GCM-SHA256 bits=128 verify=NO); Tue, 6 Jan 2015 03:23:17 -0500 Received: from tucnak.zalov.cz (localhost [127.0.0.1]) by tucnak.zalov.cz (8.14.9/8.14.9) with ESMTP id t068NESu005699; Tue, 6 Jan 2015 09:23:15 +0100 Received: (from jakub@localhost) by tucnak.zalov.cz (8.14.9/8.14.9/Submit) id t068NDqr005698; Tue, 6 Jan 2015 09:23:13 +0100 Date: Tue, 06 Jan 2015 08:23:00 -0000 From: Jakub Jelinek To: Jeff Law Cc: Dodji Seketeli , Jason Merrill , gcc-patches@gcc.gnu.org Subject: Re: Patch ping Message-ID: <20150106082313.GD1667@tucnak.redhat.com> Reply-To: Jakub Jelinek References: <20150105135313.GS1667@tucnak.redhat.com> <54AB01CD.8030509@redhat.com> <20150105213903.GA1667@tucnak.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150105213903.GA1667@tucnak.redhat.com> User-Agent: Mutt/1.5.23 (2014-03-12) X-IsSubscribed: yes X-SW-Source: 2015-01/txt/msg00194.txt.bz2 On Mon, Jan 05, 2015 at 10:39:03PM +0100, Jakub Jelinek wrote: > > >http://gcc.gnu.org/ml/gcc-patches/2014-12/msg00297.html > > > - -fsanitize=vptr support > > How is this different from vtable pointer verification that we already > > support? Is there some reason we can't just use that instead? > > I don't now the current vtable pointer verification too much, but my > understanding of it is that it is hardly usable, because e.g. it requires > libstdc++ to be rebuilt with the verification enabled, otherwise you can't > verify stuff, and that means a performance penalty even for code you don't > want to verify. Unlike that, -fsanitize=vptr is lightweight, and you only > rebuild with it what you want and can have other code kept as is, not > recompiled. Also, it seems to verify significantly less than -fsanitize=vptr does, only method calls, while -fsanitize=vptr also verifies member accesses and downcasts/upcasts. Jakub