From owner-freebsd-current@freebsd.org Mon Feb 15 20:49:15 2021 Return-Path: Delivered-To: freebsd-current@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id B2DE953956A for ; Mon, 15 Feb 2021 20:49:15 +0000 (UTC) (envelope-from sgk@troutmask.apl.washington.edu) Received: from troutmask.apl.washington.edu (troutmask.apl.washington.edu [128.95.76.21]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (2048 bits) client-digest SHA256) (Client CN "troutmask", Issuer "troutmask" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id 4Dfbn64L84z3MJR for ; Mon, 15 Feb 2021 20:49:14 +0000 (UTC) (envelope-from sgk@troutmask.apl.washington.edu) Received: from troutmask.apl.washington.edu (localhost [127.0.0.1]) by troutmask.apl.washington.edu (8.16.1/8.16.1) with ESMTPS id 11FKnD5a086379 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NO) for ; Mon, 15 Feb 2021 12:49:13 -0800 (PST) (envelope-from sgk@troutmask.apl.washington.edu) Received: (from sgk@localhost) by troutmask.apl.washington.edu (8.16.1/8.16.1/Submit) id 11FKnDI3086378 for freebsd-current@freebsd.org; Mon, 15 Feb 2021 12:49:13 -0800 (PST) (envelope-from sgk) Date: Mon, 15 Feb 2021 12:49:13 -0800 From: Steve Kargl To: freebsd-current@freebsd.org Subject: Re: HEADSUP: math is broken with clang and optimization Message-ID: <20210215204913.GA86364@troutmask.apl.washington.edu> References: <20210214215958.GA80810@troutmask.apl.washington.edu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210214215958.GA80810@troutmask.apl.washington.edu> X-Rspamd-Queue-Id: 4Dfbn64L84z3MJR X-Spamd-Bar: -- Authentication-Results: mx1.freebsd.org; dkim=none; dmarc=fail reason="No valid SPF, No valid DKIM" header.from=washington.edu (policy=none); spf=none (mx1.freebsd.org: domain of sgk@troutmask.apl.washington.edu has no SPF policy when checking 128.95.76.21) smtp.mailfrom=sgk@troutmask.apl.washington.edu X-Spamd-Result: default: False [-3.00 / 15.00]; RCVD_TLS_ALL(0.00)[]; ARC_NA(0.00)[]; MID_RHS_MATCH_FROM(0.00)[]; FROM_HAS_DN(0.00)[]; RBL_DBL_DONT_QUERY_IPS(0.00)[128.95.76.21:from]; TO_MATCH_ENVRCPT_ALL(0.00)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; MIME_GOOD(-0.10)[text/plain]; TO_DN_NONE(0.00)[]; PREVIOUSLY_DELIVERED(0.00)[freebsd-current@freebsd.org]; RCPT_COUNT_ONE(0.00)[1]; SPAMHAUS_ZRD(0.00)[128.95.76.21:from:127.0.2.255]; NEURAL_HAM_MEDIUM(-1.00)[-1.000]; NEURAL_HAM_SHORT(-1.00)[-0.997]; R_SPF_NA(0.00)[no SPF record]; FROM_EQ_ENVFROM(0.00)[]; R_DKIM_NA(0.00)[]; MIME_TRACE(0.00)[0:+]; ASN(0.00)[asn:73, ipnet:128.95.0.0/16, country:US]; RCVD_COUNT_TWO(0.00)[2]; MAILMAN_DEST(0.00)[freebsd-current]; DMARC_POLICY_SOFTFAIL(0.10)[washington.edu : No valid SPF, No valid DKIM, none] X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 15 Feb 2021 20:49:15 -0000 On Sun, Feb 14, 2021 at 01:59:58PM -0800, Steve Kargl wrote: > Just a headsup for anyone doing numerical work with > FreeBSD-current. clang with optimization of -O1 or > higher produces wrong results. Testing 1 million > complex values of ccoshf and limiting |z| < 20, > shows > This is either an in-ling bug or discarding a cast issue. With everything in the same file so clang has dp_ccosh available to it when compiling main. void dp_ccosh(double x, double y, double *re, double *im) { *re = cosh(x) * cos(y); *im = sinh(x) * sin(y); } int main(int argc, char *argv[]) { float complex f, z; double re, im, ur, ui; float x, y; float xmax; ... for (j = 0; j < NUM; j++) { x = xmax * rangef(); y = xmax * rangef(); z = CMPLXF(x,y); f = ccoshf(z); dp_ccosh((double)x, (double)y, &re, &im); gives the wrong results. Changing this to int main(int argc, char *argv[]) { float complex f, z; double re, im, ur, ui; float x, y; volatile float xv, yv; float xmax; ... for (j = 0; j < NUM; j++) { xv = x = xmax * rangef(); yv = y = xmax * rangef(); z = CMPLXF(x,y); f = ccoshf(z); dp_ccosh((double)xv, (double)yv, &re, &im); gives the expected and correct results. -- Steve