From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 8766 invoked by alias); 9 Jul 2010 10:24:49 -0000 Received: (qmail 8754 invoked by uid 22791); 9 Jul 2010 10:24:47 -0000 X-SWARE-Spam-Status: No, hits=-2.1 required=5.0 tests=AWL,BAYES_00,T_RP_MATCHES_RCVD X-Spam-Check-By: sourceware.org Received: from cam-admin0.cambridge.arm.com (HELO cam-admin0.cambridge.arm.com) (217.140.96.50) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Fri, 09 Jul 2010 10:24:41 +0000 Received: from cam-owa1.Emea.Arm.com (cam-owa1.emea.arm.com [10.1.255.62]) by cam-admin0.cambridge.arm.com (8.12.6/8.12.6) with ESMTP id o69AOZeI003075; Fri, 9 Jul 2010 11:24:35 +0100 (BST) Received: from [10.1.67.34] ([10.1.255.212]) by cam-owa1.Emea.Arm.com with Microsoft SMTPSVC(6.0.3790.0); Fri, 9 Jul 2010 11:24:34 +0100 Subject: Re: ARM patch: Add a Thumb-1 ldrsb peephole From: Richard Earnshaw To: Bernd Schmidt Cc: GCC Patches In-Reply-To: <4C36F592.6040901@codesourcery.com> References: <4C36F592.6040901@codesourcery.com> Content-Type: text/plain Date: Fri, 09 Jul 2010 10:24:00 -0000 Message-Id: <1278671074.19473.6.camel@e102346-lin.cambridge.arm.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit X-IsSubscribed: yes Mailing-List: contact gcc-patches-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-patches-owner@gcc.gnu.org X-SW-Source: 2010-07/txt/msg00759.txt.bz2 On Fri, 2010-07-09 at 12:10 +0200, Bernd Schmidt wrote: > Here's a small by-product of my attempts to tune Thumb-1 code. > > - add r3, r3, #124 > - mov r7, #0 > + mov r7, #124 > ldrsb r7, [r3, r7] > > Tested in the same run as mentioned in > http://gcc.gnu.org/ml/gcc-patches/2010-07/msg00756.html > > Ok? > This is OK. Hmm, makes me think. Could we also have a peephole to optimize the thumb-2 case? add r3, r3, r4 ldrsb r7, [r3, #124] // 32-bit, r3 dead into add r3, r3, #124 ldrsb r7, [r3, r4] // 16-bit