From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail144.messagelabs.com (mail144.messagelabs.com [216.82.254.51]) by kanga.kvack.org (Postfix) with ESMTP id 22E455F0001 for ; Sat, 30 May 2009 19:02:48 -0400 (EDT) Date: Sat, 30 May 2009 16:00:22 -0700 From: "Larry H." Subject: Re: [PATCH] Change ZERO_SIZE_PTR to point at unmapped space Message-ID: <20090530230022.GO6535@oblivion.subreption.com> References: <20090530192829.GK6535@oblivion.subreption.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org To: Linus Torvalds Cc: linux-mm@kvack.org, Alan Cox , Rik van Riel , linux-kernel@vger.kernel.org List-ID: On 15:29 Sat 30 May , Linus Torvalds wrote: > > > On Sat, 30 May 2009, Larry H. wrote: > > > > The ZERO_OR_NULL_PTR macro is changed accordingly. This patch does > > not modify its behavior nor has any performance nor functionality > > impact. > > I'm sure it makes a code generation difference, with (a) big constants and > (b) no longer possible to merge the conditional into one single one. Like I said in the reply to Peter, this is 3 extra bytes for amd64 with gcc 4.3.3. I can't be bothered to check other architectures at the moment. Larry -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org