Date: Mon, 23 Sep 2002 15:17:23 -0400 (EDT) From: Mikhail Teteri <mi@aldan.algebra.com> To: FreeBSD-gnats-submit@FreeBSD.org Cc: kan@FreeBSD.org Subject: bin/43299: march=pentium4 miscompiles msun/src/e_pow.c Message-ID: <200209231917.g8NJHNMd001235@250-217.customer.cloud9.net>
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>Number: 43299
>Category: bin
>Synopsis: march=pentium4 miscompiles msun/src/e_pow.c
>Confidential: no
>Severity: serious
>Priority: medium
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Mon Sep 23 12:20:01 PDT 2002
>Closed-Date:
>Last-Modified:
>Originator: Mikhail Teterin
>Release: FreeBSD 5.0-CURRENT i386
>Organization:
Virtual Estates, Inc.
>Environment:
System: FreeBSD misha.murex.com 5.0-CURRENT FreeBSD 5.0-CURRENT #2: Tue Sep 17 11:27:30 EDT 2002 mteterin@misha.murex.com:/misha/obj/misha/src/sys/Misha-g i386
The compiler:
Using built-in specs.
Configured with: FreeBSD/i386 system compiler
Thread model: posix
gcc version 3.2.1 [FreeBSD] 20020916 (prerelease)
>Description:
If the e_pow.c is compiled with march=pentium4, the pow(3) will
be returning 0 whenever y (the second argument) is not an integer.
>How-To-Repeat:
#include <math.h>
#include <stdio.h>
double __ieee754_pow(double, double);
int main() {
printf("%g^%g is %g\n", 2.0, 2.1, __ieee754_pow(2.0, 2.1));
return 0;
}
cd /usr/src/lib/msun/src
cc -O -march=pentium4 t.c e_pow.c -lm
./a.out
2^2.1 is 0
Notice, that I use -lm I eliminate other possible
miscompilations from the equation...
>Fix:
Use -O0 or -mno-sse2:
2^2.1 is 4.28709
>Release-Note:
>Audit-Trail:
>Unformatted:
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