From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 130381 invoked by alias); 23 Oct 2017 21:31:55 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Received: (qmail 130372 invoked by uid 89); 23 Oct 2017 21:31:54 -0000 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= X-HELO: relay1.mentorg.com Date: Mon, 23 Oct 2017 21:31:00 -0000 From: Joseph Myers To: Patrick McGehearty CC: Subject: Re: [PATCH] Improves __ieee754_exp() performance by greater than 5x on sparc/x86. In-Reply-To: <8631eace-21b0-e371-e014-295ceb511cc0@oracle.com> Message-ID: References: <1508172962-97543-1-git-send-email-patrick.mcgehearty@oracle.com> <6d6104ad-b846-68b3-8f87-3216d1e52412@oracle.com> <8631eace-21b0-e371-e014-295ceb511cc0@oracle.com> User-Agent: Alpine 2.20 (DEB 67 2015-01-07) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" X-ClientProxiedBy: svr-ies-mbx-01.mgc.mentorg.com (139.181.222.1) To SVR-IES-MBX-03.mgc.mentorg.com (139.181.222.3) X-SW-Source: 2017-10/txt/msg01101.txt.bz2 On Mon, 23 Oct 2017, Patrick McGehearty wrote: > Now I understand your point and researched the source of the comment and > reason for the use of "small". By my reading of the ieee754 definition > of "inexact", exp(x) for any x except 0.0 should set the inexact bit. However, while that would apply for TS 18661-4 crexp (corresponding directly to the IEEE 754 exp operation), glibc's accuracy goals for functions not bound to IEEE operations are as documented in math.texi, and those do not include correctness in whether "inexact" is raised. (There is some existing code in glibc to set "inexact" in cases where it's not necessary to do so. Removing such code would be reasonable cleanups, but is independent of this exp patch.) -- Joseph S. Myers joseph@codesourcery.com