From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932158AbWDZKIm (ORCPT ); Wed, 26 Apr 2006 06:08:42 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751420AbWDZKIm (ORCPT ); Wed, 26 Apr 2006 06:08:42 -0400 Received: from pentafluge.infradead.org ([213.146.154.40]:6035 "EHLO pentafluge.infradead.org") by vger.kernel.org with ESMTP id S1751398AbWDZKIm (ORCPT ); Wed, 26 Apr 2006 06:08:42 -0400 Subject: Re: [PATCH] likely cleanup: remove unlikely for kfree(NULL) From: Arjan van de Ven To: =?ISO-8859-1?Q?J=F6rn?= Engel Cc: Pekka J Enberg , Hua Zhong , linux-kernel@vger.kernel.org, akpm@osdl.org In-Reply-To: <20060426100559.GC29108@wohnheim.fh-wedel.de> References: <84144f020604260030v26f42b0bke639053928d5e471@mail.gmail.com> <1146038324.5956.0.camel@laptopd505.fenrus.org> <1146040038.7016.0.camel@laptopd505.fenrus.org> <20060426100559.GC29108@wohnheim.fh-wedel.de> Content-Type: text/plain; charset=UTF-8 Date: Wed, 26 Apr 2006 12:08:37 +0200 Message-Id: <1146046118.7016.5.camel@laptopd505.fenrus.org> Mime-Version: 1.0 X-Mailer: Evolution 2.2.3 (2.2.3-2.fc4) Content-Transfer-Encoding: 8bit X-SRS-Rewrite: SMTP reverse-path rewritten from by pentafluge.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2006-04-26 at 12:05 +0200, Jörn Engel wrote: > On Wed, 26 April 2006 10:27:18 +0200, Arjan van de Ven wrote: > > > > what I would like is kfree to become an inline wrapper that does the > > null check inline, that way gcc can optimize it out (and it will in 4.1 > > with the VRP pass) if gcc can prove it's not NULL. > > How well can gcc optimize this case? if you deref'd the pointer it'll optimize it away (assuming a new enough gcc, like 4.1)