From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 28418 invoked by alias); 19 Nov 2009 21:13:34 -0000 Received: (qmail 28410 invoked by uid 22791); 19 Nov 2009 21:13:33 -0000 X-SWARE-Spam-Status: No, hits=-2.6 required=5.0 tests=BAYES_00,SPF_HELO_PASS,SPF_PASS X-Spam-Check-By: sourceware.org Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Thu, 19 Nov 2009 21:12:30 +0000 Received: from int-mx08.intmail.prod.int.phx2.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.21]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id nAJLCNNY030764 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Thu, 19 Nov 2009 16:12:23 -0500 Received: from omfg.slc.redhat.com (ovpn01.gateway.prod.ext.phx2.redhat.com [10.5.9.1]) by int-mx08.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id nAJLCLBR020577; Thu, 19 Nov 2009 16:12:21 -0500 Message-ID: <4B05B4B5.2000102@redhat.com> Date: Thu, 19 Nov 2009 21:13:00 -0000 From: Jeff Law User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.1.4pre) Gecko/20091014 Fedora/3.0-2.8.b4.fc11 Thunderbird/3.0b4 MIME-Version: 1.0 To: Linus Torvalds CC: "H. Peter Anvin" , rostedt@goodmis.org, David Daney , Andrew Haley , Richard Guenther , 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> <1258653562.22249.682.camel@gandalf.stny.rr.com> <84fc9c000911191003t244eb864o3d5b355ab5485f@mail.gmail.com> <4B058CCD.8050605@redhat.com> <4B05982B.6060200@caviumnetworks.com> <1258658886.22249.874.camel@gandalf.stny.rr.com> <4B05A16D.1050807@zytor.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-IsSubscribed: yes Mailing-List: contact gcc-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-owner@gcc.gnu.org X-SW-Source: 2009-11/txt/msg00543.txt.bz2 On 11/19/09 13:06, Linus Torvalds wrote: > > On Thu, 19 Nov 2009, H. Peter Anvin wrote: > >> Calling the profiler immediately at the entry point is clearly the more >> sane option. It means the ABI is well-defined, stable, and independent >> of what the actual function contents are. It means that ABI isn't the >> normal C ABI (the __fentry__ function would have to preserve all >> registers), but that's fine... >> > As far as I know, that's true of _mcount already: it's not a normal ABI > and is rather a highly architecture-specific special case to begin with. > At least ARM has some (several?) special mcount calling conventions, > afaik. > Correct. _mcount's ABI typically has been defined by the implementation of the vendor's C library mcount. GCC has options to emit the profiling code prior to or after the prologue controllable through the usual variety of target macros & hooks. I can't imagine anyone would object to a clean, tested patch to change how x86-linux's profiling code was implemented. jeff