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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/flt-32 | |
| 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/flt-32')
| -rw-r--r-- | sysdeps/ieee754/flt-32/s_tanhf.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/sysdeps/ieee754/flt-32/s_tanhf.c b/sysdeps/ieee754/flt-32/s_tanhf.c index dc96da9a5b..5b48fb2e00 100644 --- a/sysdeps/ieee754/flt-32/s_tanhf.c +++ b/sysdeps/ieee754/flt-32/s_tanhf.c @@ -17,6 +17,7 @@ static char rcsid[] = "$NetBSD: s_tanhf.c,v 1.4 1995/05/10 20:48:24 jtc Exp $"; #endif +#include <float.h> #include <math.h> #include <math_private.h> @@ -41,7 +42,14 @@ float __tanhf(float x) if (ix == 0) return x; /* x == +-0 */ if (ix<0x24000000) /* |x|<2**-55 */ + { + if (fabsf (x) < FLT_MIN) + { + float force_underflow = x * x; + math_force_eval (force_underflow); + } return x*(one+x); /* tanh(small) = small */ + } if (ix>=0x3f800000) { /* |x|>=1 */ t = __expm1f(two*fabsf(x)); z = one - two/(t+two); |