From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 27981 invoked by alias); 10 Sep 2004 20:43:17 -0000 Mailing-List: contact gcc-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Archive: List-Post: List-Help: Sender: gcc-owner@gcc.gnu.org Received: (qmail 27961 invoked from network); 10 Sep 2004 20:43:12 -0000 Received: from unknown (HELO bluesmobile.specifixinc.com) (64.220.152.98) by sourceware.org with SMTP; 10 Sep 2004 20:43:12 -0000 Received: from specifixinc.com (unknown [192.168.1.2]) by bluesmobile.specifixinc.com (Postfix) with ESMTP id E884016793; Fri, 10 Sep 2004 13:43:09 -0700 (PDT) Message-ID: <414211DD.5030900@specifixinc.com> Date: Fri, 10 Sep 2004 22:15:00 -0000 From: James E Wilson User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.6) Gecko/20040114 MIME-Version: 1.0 To: "H. J. Lu" Cc: gcc@gcc.gnu.org Subject: Re: Redundant instructions in loop optimization for x86-64? References: <20040910000026.GA25099@lucon.org> <20040910095023.GF378@atrey.karlin.mff.cuni.cz> <20040910165450.GA8456@lucon.org> In-Reply-To: <20040910165450.GA8456@lucon.org> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit X-SW-Source: 2004-09/txt/msg00642.txt.bz2 H. J. Lu wrote: > Is there a way to tell gcc that 32bit zero extension isn't needed for > x86-64? It isn't quite that simple. Sometimes they will be needed. Sometimes they won't. You might want to look at http://gcc.gnu.org/ml/gcc/2004-09/msg00377.html which is a proposal to add an RTL optimization pass to eliminate unnecessary sign/zero extension instructions on targets that support both 32-bit and 64-bit code. -- Jim Wilson, GNU Tools Support, http://www.SpecifixInc.com