From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761996AbXGCVa4 (ORCPT ); Tue, 3 Jul 2007 17:30:56 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1761918AbXGCVam (ORCPT ); Tue, 3 Jul 2007 17:30:42 -0400 Received: from terminus.zytor.com ([192.83.249.54]:49133 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759752AbXGCVal (ORCPT ); Tue, 3 Jul 2007 17:30:41 -0400 Message-ID: <468ABFEE.3000608@zytor.com> Date: Tue, 03 Jul 2007 14:30:22 -0700 From: "H. Peter Anvin" User-Agent: Thunderbird 2.0.0.0 (X11/20070419) MIME-Version: 1.0 To: Chuck Ebbert CC: 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> X-Enigmail-Version: 0.95.0 Content-Type: text/plain; charset=ISO-8859-1 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 wouldn't to that, though, for the existing compiler. Instead, I would do: void (*func)(void); /* or what's appropriate */ asm( : "=rm" (func)); func(); -hpa