From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760379AbXGCXKn (ORCPT ); Tue, 3 Jul 2007 19:10:43 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755276AbXGCXKf (ORCPT ); Tue, 3 Jul 2007 19:10:35 -0400 Received: from gw.goop.org ([64.81.55.164]:42489 "EHLO mail.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755133AbXGCXKe (ORCPT ); Tue, 3 Jul 2007 19:10:34 -0400 Message-ID: <468AD767.10700@goop.org> Date: Tue, 03 Jul 2007 16:10:31 -0700 From: Jeremy Fitzhardinge User-Agent: Thunderbird 2.0.0.4 (X11/20070615) MIME-Version: 1.0 To: Chuck Ebbert CC: "H. Peter Anvin" , Mathieu Desnoyers , akpm@linux-foundation.org, linux-kernel@vger.kernel.org Subject: Re: [patch 06/10] Immediate Value - i386 Optimization References: <20070703164046.645090494@polymtl.ca> <20070703164515.071300768@polymtl.ca> <468A9956.9050903@zytor.com> <20070703191605.GB4047@Krystal> <468AAF1F.6010909@zytor.com> <468AB390.7000608@redhat.com> In-Reply-To: <468AB390.7000608@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Chuck Ebbert wrote: > On 07/03/2007 04:18 PM, H. Peter Anvin wrote: > >> One could, though, use an indirect jump to achieve, if not as good, at >> least most of the effect: >> >> movl $, >> jmp * >> >> > > Yeah, but there's this GCC bug: > > http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22448 > > You can't even dereference labels in an ASM statement. I was told in absolute terms that any use of &&label other than to pass it to goto was not supported, and would not be supported. http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29305 Seems that passing to an asm() falls into the same class of problem I had. I think the underlying problem is that if the code containing the label is in an inlined function or unrolled loop, the reference can't be resolved properly anyway. J