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 CA20CC35273 for ; Mon, 7 Feb 2022 16:33:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1388555AbiBGQaj (ORCPT ); Mon, 7 Feb 2022 11:30:39 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60916 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242367AbiBGQ0O (ORCPT ); Mon, 7 Feb 2022 11:26:14 -0500 Received: from 1wt.eu (wtarreau.pck.nerim.net [62.212.114.60]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id EE3E5C0401D1 for ; Mon, 7 Feb 2022 08:26:13 -0800 (PST) Received: (from willy@localhost) by pcw.home.local (8.15.2/8.15.2/Submit) id 217GOexf014412; Mon, 7 Feb 2022 17:24:40 +0100 From: Willy Tarreau To: "Paul E . McKenney" Cc: Mark Brown , linux-kernel@vger.kernel.org, Willy Tarreau Subject: [PATCH 29/42] tools/nolibc/string: slightly simplify memmove() Date: Mon, 7 Feb 2022 17:23:41 +0100 Message-Id: <20220207162354.14293-30-w@1wt.eu> X-Mailer: git-send-email 2.17.5 In-Reply-To: <20220207162354.14293-1-w@1wt.eu> References: <20220207162354.14293-1-w@1wt.eu> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The direction test inside the loop was not always completely optimized, resulting in a larger than necessary function. This change adds a direction variable that is set out of the loop. Now the function is down to 48 bytes on x86, 32 on ARM and 68 on mips. It's worth noting that other approaches were attempted (including relying on the up and down functions) but they were only slightly beneficial on x86 and cost more on others. Signed-off-by: Willy Tarreau --- tools/include/nolibc/string.h | 20 ++++++++++++++------ 1 file changed, 14 insertions(+), 6 deletions(-) diff --git a/tools/include/nolibc/string.h b/tools/include/nolibc/string.h index 6d8fad7a92e6..b831a02de83f 100644 --- a/tools/include/nolibc/string.h +++ b/tools/include/nolibc/string.h @@ -50,14 +50,22 @@ void *_nolibc_memcpy_down(void *dst, const void *src, size_t len) static __attribute__((unused)) void *memmove(void *dst, const void *src, size_t len) { - ssize_t pos = (dst <= src) ? -1 : (long)len; - void *ret = dst; + size_t dir, pos; - while (len--) { - pos += (dst <= src) ? 1 : -1; - ((char *)dst)[pos] = ((char *)src)[pos]; + pos = len; + dir = -1; + + if (dst < src) { + pos = -1; + dir = 1; + } + + while (len) { + pos += dir; + ((char *)dst)[pos] = ((const char *)src)[pos]; + len--; } - return ret; + return dst; } /* must be exported, as it's used by libgcc on ARM */ -- 2.35.1