Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758129AbZKXPhk (ORCPT ); Tue, 24 Nov 2009 10:37:40 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758097AbZKXPhk (ORCPT ); Tue, 24 Nov 2009 10:37:40 -0500 Received: from mx1.redhat.com ([209.132.183.28]:30863 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757343AbZKXPhj (ORCPT ); Tue, 24 Nov 2009 10:37:39 -0500 Date: Tue, 24 Nov 2009 10:36:34 -0500 From: Jakub Jelinek To: Andrew Haley Cc: Thomas Gleixner , "H.J. Lu" , rostedt@goodmis.org, Ingo Molnar , "H. Peter Anvin" , LKML , Andrew Morton , Heiko Carstens , feng.tang@intel.com, Peter Zijlstra , Frederic Weisbecker , David Daney , Richard Guenther , gcc , Linus Torvalds Subject: Re: [PATCH][GIT PULL][v2.6.32] tracing/x86: Add check to detect GCC messing with mcount prologue Message-ID: <20091124153634.GK22813@hs20-bc2-1.build.redhat.com> Reply-To: Jakub Jelinek References: <1258694593.22249.1012.camel@gandalf.stny.rr.com> <1258736456.22249.1032.camel@gandalf.stny.rr.com> <4B06EF6F.2050507@redhat.com> <6dc9ffc80911220138y15bfa91agccf5c29f1c30e09a@mail.gmail.com> <4B0972C9.302@redhat.com> <6dc9ffc80911221530t38d83cf6je739743c8d756667@mail.gmail.com> <4B0BF119.4070704@redhat.com> <20091124150604.GJ22813@hs20-bc2-1.build.redhat.com> <4B0BFC84.7070806@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4B0BFC84.7070806@redhat.com> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1169 Lines: 25 On Tue, Nov 24, 2009 at 03:32:20PM +0000, Andrew Haley wrote: > Jakub Jelinek wrote: > > On Tue, Nov 24, 2009 at 03:55:49PM +0100, Thomas Gleixner wrote: > >>> you should compile your code with -maccumulate-outgoing-args, and there's > >>> no need to use -mtune=generic. Is that right? > >> Seems to work. What other side effects has that ? > > > > Faster code, significant increase in code size though. > > Does it affect code size when we don't have to realign the stack pointer? Yes, a lot. The difference is that -maccumulate-outgoing-args allocates space for arguments of the callee with most arguments in the prologue, using subtraction from sp, then to pass arguments uses movl XXX, 4(%esp) etc. and the stack pointer doesn't usually change within the function (except for alloca/VLAs). With -mno-accumulate-outgoing-args args are pushed using push instructions and stack pointer is constantly changing. Jakub -- 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/