From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752572AbaFBHYK (ORCPT ); Mon, 2 Jun 2014 03:24:10 -0400 Received: from dehamd003.servertools24.de ([31.47.254.18]:40789 "EHLO dehamd003.servertools24.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751567AbaFBHYJ (ORCPT ); Mon, 2 Jun 2014 03:24:09 -0400 X-No-Relay: not in my network X-No-Relay: not in my network X-No-Relay: not in my network X-No-Relay: not in my network X-No-Relay: not in my network X-No-Relay: not in my network X-No-Relay: not in my network X-No-Relay: not in my network Message-ID: <538C2694.1090308@ladisch.de> Date: Mon, 02 Jun 2014 09:24:04 +0200 From: Clemens Ladisch User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:24.0) Gecko/20100101 Thunderbird/24.5.0 MIME-Version: 1.0 To: Rickard Strandqvist , Tony Luck , Fenghua Yu CC: Paul Gortmaker , "Rafael J. Wysocki" , "Srivatsa S. Bhat" , linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] arch: ia64: kernel: palinfo.c: Optimization of the Code References: <1401659019-17586-1-git-send-email-rickard_strandqvist@spectrumdigital.se> In-Reply-To: <1401659019-17586-1-git-send-email-rickard_strandqvist@spectrumdigital.se> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Rickard Strandqvist wrote: > From what I know, AND is faster then modulo. Which is why the compiler does this optimization automatically, if it can prove that it is correct. > - if (i != 0 && (i%64) == 0) > + if (i != 0 && (i&63) == 0) Did you prove that i cannot be negative? Regards, Clemens