diff options
| author | Joseph Myers <joseph@codesourcery.com> | 2015-08-13 16:40:39 +0000 |
|---|---|---|
| committer | Joseph Myers <joseph@codesourcery.com> | 2015-08-13 16:40:39 +0000 |
| commit | 37d83a089ddf7649ea0a97d4121883381e23f999 (patch) | |
| tree | e5cbd0a6885b4c122099090852c5f5cdd72ae409 /sysdeps/ieee754/ldbl-128 | |
| parent | a5cf909b8f25f8240eabc5f1ff96b4be0472d8e1 (diff) | |
| download | glibc-37d83a089ddf7649ea0a97d4121883381e23f999.zip glibc-37d83a089ddf7649ea0a97d4121883381e23f999.tar.gz glibc-37d83a089ddf7649ea0a97d4121883381e23f999.tar.bz2 | |
Fix tanh missing underflows (bug 16520).
Similar to various other bugs in this area, some tanh implementations
do not raise the underflow exception for subnormal arguments, when the
result is tiny and inexact. This patch forces the exception in a
similar way to previous fixes.
Tested for x86_64, x86, mips64 and powerpc.
[BZ #16520]
* sysdeps/ieee754/dbl-64/s_tanh.c: Include <float.h>.
(__tanh): Force underflow exception for arguments with small
absolute value.
* sysdeps/ieee754/flt-32/s_tanhf.c: Include <float.h>.
(__tanhf): Force underflow exception for arguments with small
absolute value.
* sysdeps/ieee754/ldbl-128/s_tanhl.c: Include <float.h>.
(__tanhl): Force underflow exception for arguments with small
absolute value.
* sysdeps/ieee754/ldbl-128ibm/s_tanhl.c: Include <float.h>.
(__tanhl): Force underflow exception for arguments with small
absolute value.
* sysdeps/ieee754/ldbl-96/s_tanhl.c: Include <float.h>.
(__tanhl): Force underflow exception for arguments with small
absolute value.
* math/auto-libm-test-in: Add more tests of tanh.
* math/auto-libm-test-out: Regenerated.
* sysdeps/i386/fpu/libm-test-ulps: Update.
Diffstat (limited to 'sysdeps/ieee754/ldbl-128')
| -rw-r--r-- | sysdeps/ieee754/ldbl-128/s_tanhl.c | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/sysdeps/ieee754/ldbl-128/s_tanhl.c b/sysdeps/ieee754/ldbl-128/s_tanhl.c index 129735b..8b1706f 100644 --- a/sysdeps/ieee754/ldbl-128/s_tanhl.c +++ b/sysdeps/ieee754/ldbl-128/s_tanhl.c @@ -41,6 +41,7 @@ * only tanhl(0)=0 is exact for finite argument. */ +#include <float.h> #include <math.h> #include <math_private.h> @@ -73,7 +74,14 @@ __tanhl (long double x) if (u.value == 0) return x; /* x == +- 0 */ if (ix < 0x3fc60000) /* |x| < 2^-57 */ - return x * (one + tiny); /* tanh(small) = small */ + { + if (fabsl (x) < LDBL_MIN) + { + long double force_underflow = x * x; + math_force_eval (force_underflow); + } + return x * (one + tiny); /* tanh(small) = small */ + } u.parts32.w0 = ix; /* Absolute value of x. */ if (ix >= 0x3fff0000) { /* |x| >= 1 */ |