From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:59943) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Zydx9-0001YK-6M for qemu-devel@nongnu.org; Tue, 17 Nov 2015 05:57:35 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Zydx5-0006jt-SO for qemu-devel@nongnu.org; Tue, 17 Nov 2015 05:57:35 -0500 Received: from mx1.redhat.com ([209.132.183.28]:60359) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Zydx5-0006jc-N0 for qemu-devel@nongnu.org; Tue, 17 Nov 2015 05:57:31 -0500 References: <1447754381-29882-1-git-send-email-pbonzini@redhat.com> <564B0150.7030400@redhat.com> <564B0386.4030701@redhat.com> From: Paolo Bonzini Message-ID: <564B0817.1010704@redhat.com> Date: Tue, 17 Nov 2015 11:57:27 +0100 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH for 2.5] QEMU does not care about left shifts of signed negative values List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Maydell Cc: QEMU Developers On 17/11/2015 11:55, Peter Maydell wrote: > If you pass clang -fwrapv then this causes -fsanitize=undefined to > no longer complain about signed integer overflows from addition. > However the sanitizer will still complain about left shifts of > negative values. The conclusion I draw is that clang (as per > the documentation) applies fwrapv only to addition &c, not to > shifts. Ok, I'll open a bug for this. It's probably unintended, they've already fixed -fwrapv once for pointers. Paolo