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| 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/s_tanhl.c | |
| parent | a5cf909b8f25f8240eabc5f1ff96b4be0472d8e1 (diff) | |
| download | glibc-37d83a089ddf7649ea0a97d4121883381e23f999.tar.gz glibc-37d83a089ddf7649ea0a97d4121883381e23f999.tar.xz glibc-37d83a089ddf7649ea0a97d4121883381e23f999.zip | |
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/s_tanhl.c')
| -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 129735b1b5..8b1706fcdc 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 */ |