From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761265AbXLQNg6 (ORCPT ); Mon, 17 Dec 2007 08:36:58 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753477AbXLQNgu (ORCPT ); Mon, 17 Dec 2007 08:36:50 -0500 Received: from public.id2-vpn.continvity.gns.novell.com ([195.33.99.129]:48673 "EHLO public.id2-vpn.continvity.gns.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752480AbXLQNgu convert rfc822-to-8bit (ORCPT ); Mon, 17 Dec 2007 08:36:50 -0500 Message-Id: <476689AF.76E4.0078.0@novell.com> X-Mailer: Novell GroupWise Internet Agent 7.0.2 HP Date: Mon, 17 Dec 2007 13:37:35 +0000 From: "Jan Beulich" To: "Ingo Molnar" Cc: , "Andrew Morton" , , , Subject: Re: [PATCH] x86-64: make pda's cpunumber and nodenumber unsigned References: <47610530.76E4.0078.0@novell.com> <20071217132619.GB1870@elte.hu> In-Reply-To: <20071217132619.GB1870@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8BIT Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org >>> Ingo Molnar 17.12.07 14:26 >>> > >* Jan Beulich wrote: > >> This generally allows better code to be generated, since the zero- >> extension during 32-bit operations comes for free (needed when the >> result is used as array index or similar), whereas sign extension must >> be done explicitly and frequently requires a one byte larger >> instruction due to the necessary rex64 prefix. > >good catch! Applied your patch to x86.git - queued it up for v2.6.25. I >bet there are tons of other instances where we use signed instead of >unsigned and get worse code generation. Yes, definitely. This patch was kind of a testing one whether this is a welcome change. As it appears to be, I'll probably produce more as I run into respective cases. Jan