From nobody Fri Dec 19 04:02:17 2025 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 CC5EDC83F01 for ; Wed, 30 Aug 2023 18:33:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233656AbjH3Sd0 (ORCPT ); Wed, 30 Aug 2023 14:33:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44974 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244771AbjH3N5x (ORCPT ); Wed, 30 Aug 2023 09:57:53 -0400 Received: from gnuweeb.org (gnuweeb.org [51.81.211.47]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D1ED5C2 for ; Wed, 30 Aug 2023 06:57:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gnuweeb.org; s=default; t=1693403870; bh=+oMZFii0whVGbdwH8pUpekgq85QDy15fOQgKa9a73pQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=tUranpan3lHKDejmmUM6IFSKipf93sVsIUWGiRLkuDyZJI5nSJHwKhP0mnLK5fP+3 uR1snhiBNUCgPaRvnbpDB/9DkkmlGeuEjomvpkqhRII9or/GSZLDnbley7ahM9qCM5 /FcdRKKwIgp2u/hSaEGM58shCpe+dNqrcFyma7k6WHSfCxh2q1lVgcJkFOLVzyNsRv kQTXEA2BKi6xSerLZUuqf9DGJ2Z9HLgwAQjCrevgjO3uq5iRmAYlKfG6f4u1yliVBm VFfSzcArGOrKbtrLtltVr6Ik3WZxU+mdIMp/U6nZyiuG8nR/ci0ytWjJL9tIhtBFfv lk4lwD92oEadA== Received: from localhost.localdomain (unknown [182.253.126.208]) by gnuweeb.org (Postfix) with ESMTPSA id 3CE9324B32D; Wed, 30 Aug 2023 20:57:46 +0700 (WIB) From: Ammar Faizi To: Willy Tarreau , =?UTF-8?q?Thomas=20Wei=C3=9Fschuh?= Cc: Ammar Faizi , Nicholas Rosenberg , Alviro Iskandar Setiawan , Michael William Jonathan , GNU/Weeb Mailing List , Linux Kernel Mailing List Subject: [RFC PATCH v1 3/5] tools/nolibc: x86-64: Use `rep cmpsb` for `memcmp()` Date: Wed, 30 Aug 2023 20:57:24 +0700 Message-Id: <20230830135726.1939997-4-ammarfaizi2@gnuweeb.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230830135726.1939997-1-ammarfaizi2@gnuweeb.org> References: <20230830135726.1939997-1-ammarfaizi2@gnuweeb.org> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Simplify memcmp() on the x86-64 arch. The x86-64 arch has a 'rep cmpsb' instruction, which can be used to implement the memcmp() function. %rdi =3D source 1 %rsi =3D source 2 %rcx =3D length Signed-off-by: Ammar Faizi --- tools/include/nolibc/arch-x86_64.h | 19 +++++++++++++++++++ tools/include/nolibc/string.h | 2 ++ 2 files changed, 21 insertions(+) diff --git a/tools/include/nolibc/arch-x86_64.h b/tools/include/nolibc/arch= -x86_64.h index 42f2674ad1ecdd64..6c1b54ba9f774e7b 100644 --- a/tools/include/nolibc/arch-x86_64.h +++ b/tools/include/nolibc/arch-x86_64.h @@ -214,4 +214,23 @@ __asm__ ( "retq\n" ); =20 +#define NOLIBC_ARCH_HAS_MEMCMP +static int memcmp(const void *s1, const void *s2, size_t n) +{ + const unsigned char *p1 =3D s1; + const unsigned char *p2 =3D s2; + + if (!n) + return 0; + + __asm__ volatile ( + "rep cmpsb" + : "+D"(p2), "+S"(p1), "+c"(n) + : "m"(*(const unsigned char (*)[n])s1), + "m"(*(const unsigned char (*)[n])s2) + ); + + return p1[-1] - p2[-1]; +} + #endif /* _NOLIBC_ARCH_X86_64_H */ diff --git a/tools/include/nolibc/string.h b/tools/include/nolibc/string.h index 1bad6121ef8c4ab5..3c941289d5dd0985 100644 --- a/tools/include/nolibc/string.h +++ b/tools/include/nolibc/string.h @@ -15,6 +15,7 @@ static void *malloc(size_t len); * As much as possible, please keep functions alphabetically sorted. */ =20 +#ifndef NOLIBC_ARCH_HAS_MEMCMP static __attribute__((unused)) int memcmp(const void *s1, const void *s2, size_t n) { @@ -26,6 +27,7 @@ int memcmp(const void *s1, const void *s2, size_t n) } return c1; } +#endif /* #ifndef NOLIBC_ARCH_HAS_MEMCMP */ =20 static __attribute__((unused)) void *_nolibc_memcpy_up(void *dst, const void *src, size_t len) --=20 Ammar Faizi