From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261646AbVFOXRD (ORCPT ); Wed, 15 Jun 2005 19:17:03 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261642AbVFOXRC (ORCPT ); Wed, 15 Jun 2005 19:17:02 -0400 Received: from imf25aec.mail.bellsouth.net ([205.152.59.73]:44995 "EHLO imf25aec.mail.bellsouth.net") by vger.kernel.org with ESMTP id S261654AbVFOXO6 (ORCPT ); Wed, 15 Jun 2005 19:14:58 -0400 Message-ID: <000101c57207$6b4f3de0$2800000a@pc365dualp2> From: To: "Maciej W. Rozycki" Cc: References: <000b01c57187$ade6b9b0$2800000a@pc365dualp2> Subject: Re: .../asm-i386/bitops.h performance improvements Date: Wed, 15 Jun 2005 19:48:29 -0400 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1478 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1478 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org The only thing I've seen so far that loses is a straight original 486. Its pipe is somewhat more simple minded and interlock prone than later models. PPro, K6 and 386SX are big winners. On the 386's, lacking actual pipeline, the compactness of the LEA over the SHL/ADD can be more of an overriding factor. ----- Original Message ----- From: "Maciej W. Rozycki" To: Cc: Sent: Wednesday, June 15, 2005 11:34 Subject: Re: .../asm-i386/bitops.h performance improvements > > Be careful about model-specific penalties from using certain address > modes and AGIs when using "lea" for such calculations. > > Maciej