From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 43A55C83F2C for ; Sun, 3 Sep 2023 20:38:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239276AbjICUii convert rfc822-to-8bit (ORCPT ); Sun, 3 Sep 2023 16:38:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39852 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232907AbjICUig (ORCPT ); Sun, 3 Sep 2023 16:38:36 -0400 Received: from eu-smtp-delivery-151.mimecast.com (eu-smtp-delivery-151.mimecast.com [185.58.85.151]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AAFEBB7 for ; Sun, 3 Sep 2023 13:38:33 -0700 (PDT) Received: from AcuMS.aculab.com (156.67.243.121 [156.67.243.121]) by relay.mimecast.com with ESMTP with both STARTTLS and AUTH (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id uk-mta-214-vV-7UcdcOvCAXJUwEccxaw-1; Sun, 03 Sep 2023 21:38:31 +0100 X-MC-Unique: vV-7UcdcOvCAXJUwEccxaw-1 Received: from AcuMS.Aculab.com (10.202.163.6) by AcuMS.aculab.com (10.202.163.6) with Microsoft SMTP Server (TLS) id 15.0.1497.48; Sun, 3 Sep 2023 21:38:22 +0100 Received: from AcuMS.Aculab.com ([::1]) by AcuMS.aculab.com ([::1]) with mapi id 15.00.1497.048; Sun, 3 Sep 2023 21:38:22 +0100 From: David Laight To: 'Ammar Faizi' , Willy Tarreau , =?iso-8859-1?Q?Thomas_Wei=DFschuh?= CC: Nicholas Rosenberg , Alviro Iskandar Setiawan , Michael William Jonathan , GNU/Weeb Mailing List , Linux Kernel Mailing List Subject: RE: [RFC PATCH v3 0/4] nolibc x86-64 string functions Thread-Topic: [RFC PATCH v3 0/4] nolibc x86-64 string functions Thread-Index: AQHZ3aJQJGuZm6bblEePRxuhM4xRuLAJkSLg Date: Sun, 3 Sep 2023 20:38:22 +0000 Message-ID: References: <20230902133505.2176434-1-ammarfaizi2@gnuweeb.org> In-Reply-To: <20230902133505.2176434-1-ammarfaizi2@gnuweeb.org> Accept-Language: en-GB, en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: aculab.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Ammar Faizi > Sent: 02 September 2023 14:35 > > This is an RFC patchset v3 for nolibc x86-64 string functions. > > There are 4 patches in this series: > > ## Patch 1-2: Use `rep movsb`, `rep stosb` for: > - memcpy() and memmove() > - memset() > respectively. They can simplify the generated ASM code. It is worth pointing out that while the code size for 'rep xxxb' is smaller, the performance is terrible. The only time it is ever good is for the optimised forwards copies on cpu that support it. reverse, stos and scas are always horrid. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)