From owner-freebsd-current  Thu Oct 31  1:17:27 2002
Delivered-To: freebsd-current@freebsd.org
Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125])
	by hub.freebsd.org (Postfix) with ESMTP id 1138137B401
	for <current@FreeBSD.ORG>; Thu, 31 Oct 2002 01:17:25 -0800 (PST)
Received: from mailman.zeta.org.au (mailman.zeta.org.au [203.26.10.16])
	by mx1.FreeBSD.org (Postfix) with ESMTP id 041C443E6E
	for <current@FreeBSD.ORG>; Thu, 31 Oct 2002 01:17:24 -0800 (PST)
	(envelope-from bde@zeta.org.au)
Received: from bde.zeta.org.au (bde.zeta.org.au [203.2.228.102])
	by mailman.zeta.org.au (8.9.3/8.8.7) with ESMTP id UAA21367;
	Thu, 31 Oct 2002 20:17:12 +1100
Date: Thu, 31 Oct 2002 20:28:33 +1100 (EST)
From: Bruce Evans <bde@zeta.org.au>
X-X-Sender: bde@gamplex.bde.org
To: "M. Warner Losh" <imp@bsdimp.com>
Cc: tlambert2@mindspring.com, <rittle@labs.mot.com>,
	<rittle@latour.rsch.comm.mot.com>, <current@FreeBSD.ORG>,
	<dschultz@uclink.Berkeley.EDU>
Subject: Re: Lack of real long double support
In-Reply-To: <20021030.170154.35505346.imp@bsdimp.com>
Message-ID: <20021031202343.W8632-100000@gamplex.bde.org>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII
Sender: owner-freebsd-current@FreeBSD.ORG
Precedence: bulk
List-ID: <freebsd-current.FreeBSD.ORG>
List-Archive: <http://docs.freebsd.org/mail/> (Web Archive)
List-Help: <mailto:majordomo@FreeBSD.ORG?subject=help> (List Instructions)
List-Subscribe: <mailto:majordomo@FreeBSD.ORG?subject=subscribe%20freebsd-current>
List-Unsubscribe: <mailto:majordomo@FreeBSD.ORG?subject=unsubscribe%20freebsd-current>
X-Loop: FreeBSD.ORG

On Wed, 30 Oct 2002, M. Warner Losh wrote:

> The one issue that I've seen is
>
>     long double a = 1.0L;
>     long double b = 1.0L + LDBL_EPSION
>     if (a == b) abort();
>
> which is what I'm trying to fix. (note, "1.0L" must be spelled
> "oneld()" and long double oneld() { return (1.0L);}) to avoid the
> optimizer getting it right.

Example of how fixing this breaks a similar assertion for DBL_ESPILON:

%%%
$ cat z.c
#include <float.h>
#include <floatingpoint.h>

long double oneld = 1.0L;
double oned = 1.0;

int
main()
{
	test(2);
	test(3);
}

int
test(int prec)
{
	long double la, lb;
	double a, b;

	fpsetprec(prec);
	la = oneld;
	lb = oneld + LDBL_EPSILON;
	if (la == lb)
		printf("LDBL_EPSILON failed test 1 with prec %d\n", prec);
	la = oneld;
	lb = oneld + LDBL_EPSILON / 2;
	if (la != lb)
		printf("LDBL_EPSILON failed test 2 with prec %d\n", prec);

	a = oned;
	b = oned + DBL_EPSILON;
	if (a == b)
		printf("DBL_EPSILON failed test 1 with prec %d\n", prec);
	a = oned;
	b = oned + DBL_EPSILON / 2;
	if (a != b)
		printf("DBL_EPSILON failed test 2 with prec %d\n", prec);
}
$ cc -o z z.c
$ ./z
LDBL_EPSILON failed test 1 with prec 2
$ cc -O -o z z.c.
$ ./z
LDBL_EPSILON failed test 1 with prec 2
DBL_EPSILON failed test 2 with prec 3
%%%

The full brokenness only shows up with -O.

Bruce


To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-current" in the body of the message