Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753896AbZKSSmh (ORCPT ); Thu, 19 Nov 2009 13:42:37 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753212AbZKSSmg (ORCPT ); Thu, 19 Nov 2009 13:42:36 -0500 Received: from terminus.zytor.com ([198.137.202.10]:53006 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753278AbZKSSmf (ORCPT ); Thu, 19 Nov 2009 13:42:35 -0500 Message-ID: <4B05904D.8050508@zytor.com> Date: Thu, 19 Nov 2009 10:37:01 -0800 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.4pre) Gecko/20091014 Fedora/3.0-2.8.b4.fc11 Thunderbird/3.0b4 MIME-Version: 1.0 To: rostedt@goodmis.org CC: Andrew Haley , Thomas Gleixner , Ingo Molnar , LKML , Andrew Morton , Heiko Carstens , feng.tang@intel.com, Fr??d??ric Weisbecker , Peter Zijlstra , jakub@redhat.com, gcc@gcc.gnu.org Subject: Re: BUG: GCC-4.4.x changes the function frame on some functions References: <20091119072040.GA23579@elte.hu> <4B058C76.9090609@redhat.com> <1258655585.22249.751.camel@gandalf.stny.rr.com> In-Reply-To: <1258655585.22249.751.camel@gandalf.stny.rr.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 792 Lines: 23 On 11/19/2009 10:33 AM, Steven Rostedt wrote: > > It has to align the entire stack? Why not just the variable within the > stack? > Because if the stack pointer isn't aligned, it won't know where it can stuff the variable. It has to pad *somewhere*, and since you may have more than one such variable, the most efficient way -- and by far least complex -- is for the compiler to align the stack when it sets up the stack frame. -hpa -- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf. -- 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/