Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753604AbXFYAJu (ORCPT ); Sun, 24 Jun 2007 20:09:50 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751850AbXFYAJn (ORCPT ); Sun, 24 Jun 2007 20:09:43 -0400 Received: from pentafluge.infradead.org ([213.146.154.40]:41344 "EHLO pentafluge.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751430AbXFYAJm (ORCPT ); Sun, 24 Jun 2007 20:09:42 -0400 Subject: Re: [PATCH] trivial: the memset operation on a automatic array variable should be optimized out by data initialization From: Arjan van de Ven To: Benjamin LaHaise Cc: Oleg Verych , rae l , trivial@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20070624232314.GA971@kvack.org> References: <467cac85.081b600a.5b88.457f@mx.google.com> <91b13c310706240558p70dbaed2g570b57ab480aa974@mail.gmail.com> <20070624222518.GA10398@flower.upol.cz> <1182723318.6819.5.camel@laptopd505.fenrus.org> <20070624232314.GA971@kvack.org> Content-Type: text/plain Organization: Intel International BV Date: Sun, 24 Jun 2007 17:09:16 -0700 Message-Id: <1182730156.6819.8.camel@laptopd505.fenrus.org> Mime-Version: 1.0 X-Mailer: Evolution 2.10.2 (2.10.2-2.fc7) Content-Transfer-Encoding: 7bit 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 Content-Length: 936 Lines: 20 On Sun, 2007-06-24 at 19:23 -0400, Benjamin LaHaise wrote: > On Sun, Jun 24, 2007 at 03:15:17PM -0700, Arjan van de Ven wrote: > > we should just alias our memset to the __builtin one, and then provide a > > generic one from lib/ for the cases gcc needs to do a fallback. > > The last time I checked, gcc generated horrible badly performing code for > builtin memset/memcpy() when -Os is specified. if you care about the last cycle, don't specify -Os but -O2. simple as that... you get what you tell the compiler you want. -- if you want to mail me at work (you don't), use arjan (at) linux.intel.com Test the interaction between Linux and your BIOS via http://www.linuxfirmwarekit.org - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/