From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:55341) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TDdLr-0003wL-Cm for qemu-devel@nongnu.org; Mon, 17 Sep 2012 11:35:17 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1TDdLg-0000im-GH for qemu-devel@nongnu.org; Mon, 17 Sep 2012 11:35:11 -0400 Received: from mail-qa0-f45.google.com ([209.85.216.45]:58864) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TDdLg-0000iU-D4 for qemu-devel@nongnu.org; Mon, 17 Sep 2012 11:35:00 -0400 Received: by qadc10 with SMTP id c10so1608120qad.4 for ; Mon, 17 Sep 2012 08:35:00 -0700 (PDT) Sender: Richard Henderson Message-ID: <50574320.6030407@twiddle.net> Date: Mon, 17 Sep 2012 08:34:56 -0700 From: Richard Henderson MIME-Version: 1.0 References: <1347836915-14091-1-git-send-email-aurelien@aurel32.net> <1347836915-14091-4-git-send-email-aurelien@aurel32.net> In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 3/5] target-arm: convert shl and shr helpers to TCG List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Maydell Cc: Laurent Desnogues , qemu-devel@nongnu.org, Aurelien Jarno On 09/17/2012 02:43 AM, Peter Maydell wrote: > The TCG shift operations are undefined behaviour (not merely > undefined result) if the shift is >= 32, so we must avoid > doing that even if we're going to throw away the answer. I don't think that ought to be true. In particular, I've just posted a patch to cure the Sparc TCG backend from producing an illegal insn in the face of a shift with a count of 64. I'd much rather we simply had an undefined result. r~