From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on gnuweeb.org X-Spam-Level: X-Spam-Status: No, score=-1.2 required=5.0 tests=ALL_TRUSTED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,URIBL_BLOCKED, URIBL_DBL_BLOCKED_OPENDNS autolearn=ham autolearn_force=no version=3.4.6 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: 8bit List-Id: 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 = source 1 %rsi = source 2 %rcx = 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" ); +#define NOLIBC_ARCH_HAS_MEMCMP +static int memcmp(const void *s1, const void *s2, size_t n) +{ + const unsigned char *p1 = s1; + const unsigned char *p2 = 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. */ +#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 */ static __attribute__((unused)) void *_nolibc_memcpy_up(void *dst, const void *src, size_t len) -- Ammar Faizi