From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED!not-for-mail From: Joseph Myers Newsgroups: gmane.comp.lib.glibc.alpha Subject: Re: [PATCH] v11 Improves __ieee754_exp() performance by greater than 5x on sparc/x86. Date: Fri, 2 Feb 2018 15:33:25 +0000 Message-ID: References: <1517262265-79445-1-git-send-email-patrick.mcgehearty@oracle.com> <361bac88-5538-227f-b6dc-76416178192c@arm.com> NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" X-Trace: blaine.gmane.org 1517585521 15793 195.159.176.226 (2 Feb 2018 15:32:01 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Fri, 2 Feb 2018 15:32:01 +0000 (UTC) User-Agent: Alpine 2.20 (DEB 67 2015-01-07) Cc: Patrick McGehearty , , To: Szabolcs Nagy Original-X-From: libc-alpha-return-89917-glibc-alpha=m.gmane.org@sourceware.org Fri Feb 02 16:31:56 2018 Return-path: Envelope-to: glibc-alpha@blaine.gmane.org DomainKey-Signature: a=rsa-sha1; c=nofws; d=sourceware.org; h=list-id :list-unsubscribe:list-subscribe:list-archive:list-post :list-help:sender:date:from:to:cc:subject:in-reply-to:message-id :references:mime-version:content-type; q=dns; s=default; b=jGmpo QeutpmJhULbnrefvqlFwrAmuXM8L3l9N5JGwRAFl8eRYglz11Ft48FQzs6/s6hcP ETECHaE7k3YfNmOfPBLVxHqZSKZUxqkTWGDGJYNmbZ4ojCoBej4Xtp3wCf98f4c+ GoihhHJLTVUuV1D/W10OvJK5nMXYeqkJQE3+bc= DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=sourceware.org; h=list-id :list-unsubscribe:list-subscribe:list-archive:list-post :list-help:sender:date:from:to:cc:subject:in-reply-to:message-id :references:mime-version:content-type; s=default; bh=iVhnebLTu5G ub9s4qJCZXxbcuaw=; b=qAW2uIlIDTpQvJKh6Oh8V+Hz7GQTpPRMSccV8jSs4B8 i1uewmvcB4vK4SjgEVS4XRCDmn8diyuFruW75BUlqojWVYstzTNuiT7MLS8oSdBE ec2JeOKfw5OXwMyiVIhDfPwg+XH5RfMRvl/nxPyGfSSagOFfvNzDbK8V9R2fv+KA = Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Original-Sender: libc-alpha-owner@sourceware.org Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.0 required=5.0 tests=AWL,BAYES_00,RCVD_IN_DNSWL_NONE,SPF_PASS,URIBL_RED autolearn=ham version=3.3.2 spammy=sk:precisi X-HELO: relay1.mentorg.com In-Reply-To: <361bac88-5538-227f-b6dc-76416178192c@arm.com> X-ClientProxiedBy: svr-ies-mbx-01.mgc.mentorg.com (139.181.222.1) To svr-ies-mbx-01.mgc.mentorg.com (139.181.222.1) Xref: news.gmane.org gmane.comp.lib.glibc.alpha:82267 Archived-At: Received: from server1.sourceware.org ([209.132.180.131] helo=sourceware.org) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1ehdJL-0002Mf-Iz for glibc-alpha@blaine.gmane.org; Fri, 02 Feb 2018 16:31:31 +0100 Received: (qmail 97797 invoked by alias); 2 Feb 2018 15:33:33 -0000 Received: (qmail 97785 invoked by uid 89); 2 Feb 2018 15:33:32 -0000 On Fri, 2 Feb 2018, Szabolcs Nagy wrote: > (i also removed the rounding mode settings in both cases > as that can be avoided at least on aarch64) There is or was certainly code in the existing exp that gives completely wrong results in non-default rounding modes (that was bug 3976) - e.g. using precision-extension techniques that require round-to-nearest - though I don't know if that applies to the fast case code or if it's only in code for slow cases (or code for slow cases but using other rounding modes results in the slow cases getting used much more). -- Joseph S. Myers joseph@codesourcery.com