From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757329Ab3HMQoY (ORCPT ); Tue, 13 Aug 2013 12:44:24 -0400 Received: from terminus.zytor.com ([198.137.202.10]:34411 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756163Ab3HMQoX (ORCPT ); Tue, 13 Aug 2013 12:44:23 -0400 Message-ID: <520A622B.7020900@zytor.com> Date: Tue, 13 Aug 2013 09:43:23 -0700 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130625 Thunderbird/17.0.7 MIME-Version: 1.0 To: Cyrill Gorcunov CC: Andy Lutomirski , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, xemul@parallels.com, mpm@selenic.com, xiaoguangrong@linux.vnet.ibm.com, mtosatti@redhat.com, kosaki.motohiro@gmail.com, sfr@canb.auug.org.au, peterz@infradead.org, aneesh.kumar@linux.vnet.ibm.com, Ingo Molnar , Thomas Gleixner Subject: Re: [patch 2/2] [PATCH] mm: Save soft-dirty bits on file pages References: <20130730204154.407090410@gmail.com> <20130730204654.966378702@gmail.com> <20130807132812.60ad4bfe85127794094d385e@linux-foundation.org> <20130808145120.GA1775@moon> <20130812145720.3b722b066fe1bd77291331e5@linux-foundation.org> <20130813050213.GA2869@moon> <520A4D5F.6020401@zytor.com> <20130813153703.GE2869@moon> In-Reply-To: <20130813153703.GE2869@moon> X-Enigmail-Version: 1.5.2 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/13/2013 08:37 AM, Cyrill Gorcunov wrote: >> >> Does it actually matter, generated-code-wise, or is the compiler smart >> enough to figure it out? The reason I'm asking is because it makes the > > gcc-4.7.2 is smart enough to suppress useless masking (ie ((1u << 31) - 1)) > completely but I don't know if this can be assumed for all gcc series. > I would be highly surprised if it wasn't the case for any gcc we care about. -hpa