From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751639Ab1GPAOw (ORCPT ); Fri, 15 Jul 2011 20:14:52 -0400 Received: from claw.goop.org ([74.207.240.146]:45379 "EHLO claw.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751080Ab1GPAOv (ORCPT ); Fri, 15 Jul 2011 20:14:51 -0400 Message-ID: <4E20D7E9.6070802@goop.org> Date: Fri, 15 Jul 2011 17:14:33 -0700 From: Jeremy Fitzhardinge User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.17) Gecko/20110428 Fedora/3.1.10-1.fc15 Lightning/1.0b3pre Thunderbird/3.1.10 MIME-Version: 1.0 To: "H. Peter Anvin" CC: Peter Zijlstra , Linus Torvalds , Ingo Molnar , the arch/x86 maintainers , Linux Kernel Mailing List , Nick Piggin , Jeremy Fitzhardinge , "H.J. Lu" Subject: Re: [PATCH RFC 0/7] x86: convert ticketlocks to C and remove duplicate code References: <4E0506A8.3010102@zytor.com> <4E0512BC.5010900@goop.org> <1ade2577-044b-4391-a607-91a4a989c3ff@email.android.com> <4E2077E1.4060606@goop.org> <4E20C80A.4050307@zytor.com> In-Reply-To: <4E20C80A.4050307@zytor.com> X-Enigmail-Version: 1.1.2 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 On 07/15/2011 04:06 PM, H. Peter Anvin wrote: > On 07/15/2011 10:24 AM, Jeremy Fitzhardinge wrote: >> I posted a bug about gcc not generating cmp %ah, %al in this case, but the general consensus was that >> it's not a good choice on current Intel chips, because it causes a partial word stall, and that the >> current generated code is better. (And gcc can generate "cmp %Xh, %Xl" if it wants to - see below.) >> > Which version of gcc is this, and also, do you have the gcc bug report > number? I was talking to H.J. and he said he thought it sounded strange. gcc version 4.6.0 20110530 (Red Hat 4.6.0-9) (GCC) It's bug 47556. J