From: Paul Zimmermann <Paul.Zimmermann@inria.fr>
To: musl@lists.openwall.com
Subject: [musl] issue with exp10l
Date: Thu, 07 Jan 2021 12:17:33 +0100 [thread overview]
Message-ID: <mwpn2hm1wy.fsf@tomate.loria.fr> (raw)
Hi,
I am extending my comparison of the accuracy of several mathematical libraries
to the "double extended precision" (long double on x86_64).
First I notice that Musl does not provide j0, j1, y0, and y1 for the long
double format. Do you confirm?
Then I got a segmentation fault using exp10l with NaN input with a non-zero
payload.
$ cat test_exp10.c
#define _GNU_SOURCE
typedef union { __uint128_t n; long double x; } union_t;
#include <stdio.h>
#include <math.h>
int main()
{
union_t u;
u.n = 16383UL;
u.n = u.n << 64;
u.n = u.n | 629329181547216221UL;
/* u.n = 302213637488765131341149 */
long double x = u.x;
printf ("x=%La\n", x);
fflush (stdout);
long double y;
y = exp10l (x);
printf ("y=%La\n", y);
fflush (stdout);
return 0;
}
With glibc this works fine:
$ gcc -fno-builtin test_exp10.c -lm
$ ./a.out
x=nan
y=-nan
With Musl 1.2.1 I get:
$ ./a.out
x=nan
Segmentation fault
According to gdb, the issue is in pow10l:
Program received signal SIGSEGV, Segmentation fault.
0x000055555555d10e in pow10l ()
(gdb) where
#0 0x000055555555d10e in pow10l ()
#1 0x0000000080000000 in ?? ()
#2 0x0000000000003fff in ?? ()
#3 0x0000000000000000 in ?? ()
Best regards,
Paul
next reply other threads:[~2021-01-07 11:20 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-07 11:17 Paul Zimmermann [this message]
2021-01-07 19:49 ` Rich Felker
2021-01-07 20:02 ` Rich Felker
2021-01-08 9:06 ` Paul Zimmermann
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