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 C7B2CCA0FE5 for ; Fri, 1 Sep 2023 14:23:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1349964AbjIAOXk convert rfc822-to-8bit (ORCPT ); Fri, 1 Sep 2023 10:23:40 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37668 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234756AbjIAOXj (ORCPT ); Fri, 1 Sep 2023 10:23:39 -0400 Received: from eu-smtp-delivery-151.mimecast.com (eu-smtp-delivery-151.mimecast.com [185.58.86.151]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3432ACC5 for ; Fri, 1 Sep 2023 07:23:36 -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-mtapsc-3-upz6m7wVOF-ZST2cWmMt8w-1; Fri, 01 Sep 2023 15:23:33 +0100 X-MC-Unique: upz6m7wVOF-ZST2cWmMt8w-1 Received: from AcuMS.Aculab.com (10.202.163.4) by AcuMS.aculab.com (10.202.163.4) with Microsoft SMTP Server (TLS) id 15.0.1497.48; Fri, 1 Sep 2023 15:23:28 +0100 Received: from AcuMS.Aculab.com ([::1]) by AcuMS.aculab.com ([::1]) with mapi id 15.00.1497.048; Fri, 1 Sep 2023 15:23:28 +0100 From: David Laight To: 'Ammar Faizi' , Willy Tarreau CC: =?iso-8859-1?Q?Thomas_Wei=DFschuh?= , "Nicholas Rosenberg" , Alviro Iskandar Setiawan , Michael William Jonathan , GNU/Weeb Mailing List , Linux Kernel Mailing List Subject: RE: [RFC PATCH v1 0/5] nolibc x86-64 string functions Thread-Topic: [RFC PATCH v1 0/5] nolibc x86-64 string functions Thread-Index: AQHZ23UUaWogkrxxpUapKlllYL+KVbAF2IcQgAAa01yAABQxQA== Date: Fri, 1 Sep 2023 14:23:28 +0000 Message-ID: References: <20230830135726.1939997-1-ammarfaizi2@gnuweeb.org> <5a821292d96a4dbc84c96ccdc6b5b666@AcuMS.aculab.com> In-Reply-To: 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: 01 September 2023 14:06 ... > > You're completely right indeed, reminds me about the copy_up/copy_down > > that were not used anymore :-) > > I'm an idiot, will fix that. Another attempt as suggested below: > > __asm__ ( > ".section .text.nolibc_memmove\n" > ".weak memmove\n" > "memmove:\n" > " movq %rdx, %rcx\n" > " movq %rdi, %rdx\n" > " movq %rdi, %rax\n" You seem to have confused yourself about whether you are using %eax or %edx. > " subq %rsi, %rdx\n" > " cmpq %rcx, %rdx\n" > " jnb .Lforward_copy\n" I think I'd fall through to the forwards copy and not worry about replicating the 'reps movsb' and 'ret'. IIRC 'cld' can be slow as well. > " leaq -1(%rdi, %rcx, 1), %rdi\n" > " leaq -1(%rsi, %rcx, 1), %rsi\n" > " std\n" > ".Lforward_copy:\n" > " rep movsb\n" > " cld\n" > " ret\n" > ); > > -- > Ammar Faizi David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)