From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.33) id 1BTtjT-0005sW-D8 for qemu-devel@nongnu.org; Fri, 28 May 2004 22:37:59 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.33) id 1BTtjP-0005rD-Kq for qemu-devel@nongnu.org; Fri, 28 May 2004 22:37:57 -0400 Received: from [199.232.76.173] (helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.33) id 1BTtch-00033B-1V for qemu-devel@nongnu.org; Fri, 28 May 2004 22:30:59 -0400 Received: from mail by monty-python.gnu.org with spam-scanned (Exim 4.34) id 1BTq2N-0006zz-MQ for qemu-devel@nongnu.org; Fri, 28 May 2004 18:41:47 -0400 Received: from [62.4.22.179] (helo=mail.bbrox.com) by monty-python.gnu.org with esmtp (Exim 4.34) id 1BTpdX-0002IA-J7 for qemu-devel@nongnu.org; Fri, 28 May 2004 18:15:36 -0400 Date: Sat, 29 May 2004 00:15:25 +0200 From: Lionel Ulmer Subject: Re: [SOLVED] Re: [Qemu-devel] Overoptimization Message-ID: <20040529001525.A387@bbland> References: <40B693A7.9050006@ums.usu.ru> <20040528101351.GA18592@MAIL.13thfloor.at> <40B71B59.7080406@ums.usu.ru> <20040528110838.GA19126@MAIL.13thfloor.at> <40B743C0.8020003@ums.usu.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <40B743C0.8020003@ums.usu.ru>; from patrakov@ums.usu.ru on Fri, May 28, 2004 at 07:50:56PM +0600 Reply-To: qemu-devel@gnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org List-ID: > In fact I just had to read the gcc info page and remove optimizations > one by one. Result, with gcc 3.3.2: > > -Wall -O2 -g -fomit-frame-pointer (defaults) = unsafe, > -Wall -O2 -g -fomit-frame-pointer -fno-strict-aliasing = safe. > > So it looks like slirp code breaks strict aliasing rules assumed by -O2. > Since the problem has been identified precisely, it has to be fixed in > qemu CVS. I think this aliasing stuff will really provoke a LOT of bugs out there for years to come... For example, Wine switched to '-fno-strict-aliasing' a long time ago :-) Lionel -- Lionel Ulmer - http://www.bbrox.org/