From patchwork Wed Jul 26 16:05:24 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sunil Pandey X-Patchwork-Id: 73239 Return-Path: X-Original-To: patchwork@sourceware.org Delivered-To: patchwork@sourceware.org Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id 99CE9385AFAD for ; Wed, 26 Jul 2023 16:05:50 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 99CE9385AFAD DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1690387550; bh=QvPeV6E0fOKOUN6xD7SQ2tKi3yMBW3VPJ8rP9Vm1Woc=; h=To:Cc:Subject:Date:List-Id:List-Unsubscribe:List-Archive: List-Post:List-Help:List-Subscribe:From:Reply-To:From; b=OyAd7ExpMg404lW+pfo2/EcL3BIoI4XWAmRl0HIvamvvpyO7HdSsK5ERK8t4RYloc mcur71iyITAxTApx2u9m8QEcpxSa9Isqmtd/dMhLf/Twgi2or03eF7rDZ2kSFgp2IW aYQfNykPXm3CileL/CPszc4errYPJnkvwNBxHtpk= X-Original-To: libc-alpha@sourceware.org Delivered-To: libc-alpha@sourceware.org Received: from mga07.intel.com (mga07.intel.com [134.134.136.100]) by sourceware.org (Postfix) with ESMTPS id BF94F3854826 for ; Wed, 26 Jul 2023 16:05:26 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org BF94F3854826 X-IronPort-AV: E=McAfee;i="6600,9927,10783"; a="434325551" X-IronPort-AV: E=Sophos;i="6.01,232,1684825200"; d="scan'208";a="434325551" Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by orsmga105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 26 Jul 2023 09:05:25 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.01,202,1684825200"; d="scan'208";a="869933417" Received: from scymds03.sc.intel.com ([10.148.94.166]) by fmsmga001.fm.intel.com with ESMTP; 26 Jul 2023 09:05:26 -0700 Received: from gskx-1.sc.intel.com (gskx-1.sc.intel.com [172.25.149.211]) by scymds03.sc.intel.com (Postfix) with ESMTP id 24C625E; Wed, 26 Jul 2023 09:05:25 -0700 (PDT) To: libc-alpha@sourceware.org Cc: hjl.tools@gmail.com Subject: [PATCH] x86_64: Optimize ffsll function code size. Date: Wed, 26 Jul 2023 09:05:24 -0700 Message-ID: <20230726160524.1955013-1-skpgkp2@gmail.com> X-Mailer: git-send-email 2.41.0 MIME-Version: 1.0 X-Spam-Status: No, score=-8.8 required=5.0 tests=BAYES_00, DKIM_ADSP_CUSTOM_MED, FORGED_GMAIL_RCVD, FREEMAIL_ENVFROM_END_DIGIT, FREEMAIL_FROM, GIT_PATCH_0, HK_RANDOM_ENVFROM, HK_RANDOM_FROM, KAM_DMARC_NONE, KAM_DMARC_STATUS, NML_ADSP_CUSTOM_MED, RCVD_IN_MSPIKE_H2, SPF_HELO_NONE, SPF_SOFTFAIL, SPOOFED_FREEMAIL, SPOOF_GMAIL_MID, TXREP, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-Patchwork-Original-From: Sunil K Pandey via Libc-alpha From: Sunil Pandey Reply-To: Sunil K Pandey Errors-To: libc-alpha-bounces+patchwork=sourceware.org@sourceware.org Sender: "Libc-alpha" Ffsll function size is 17 byte, this patch optimizes size to 16 byte. Currently ffsll function randomly regress by ~20%, depending on how code get aligned. This patch fixes ffsll function random performance regression. --- sysdeps/x86_64/ffsll.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/sysdeps/x86_64/ffsll.c b/sysdeps/x86_64/ffsll.c index a1c13d4906..dbded6f0a1 100644 --- a/sysdeps/x86_64/ffsll.c +++ b/sysdeps/x86_64/ffsll.c @@ -29,7 +29,7 @@ ffsll (long long int x) long long int tmp; asm ("bsfq %2,%0\n" /* Count low bits in X and store in %1. */ - "cmoveq %1,%0\n" /* If number was zero, use -1 as result. */ + "cmove %k1,%k0\n" /* If number was zero, use -1 as result. */ : "=&r" (cnt), "=r" (tmp) : "rm" (x), "1" (-1)); return cnt + 1;