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| author | Joseph Myers <joseph@codesourcery.com> | 2014-06-30 17:38:16 +0000 |
|---|---|---|
| committer | Joseph Myers <joseph@codesourcery.com> | 2014-06-30 17:38:16 +0000 |
| commit | ce9c5b3e955746a9187ffde9b16feea4a357c86a (patch) | |
| tree | e60ee24b2da9fb3291a4667607040ca7d9337fa1 /sysdeps | |
| parent | 3a6e988706d1ce2c88c933619d1f312098698ecd (diff) | |
| download | glibc-ce9c5b3e955746a9187ffde9b16feea4a357c86a.tar.gz glibc-ce9c5b3e955746a9187ffde9b16feea4a357c86a.tar.xz glibc-ce9c5b3e955746a9187ffde9b16feea4a357c86a.zip | |
Fix ldbl-128 expm1l spurious underflow (bug 16539).
This patch fixes spurious underflows from ldbl-128 expm1l, as reported in <https://sourceware.org/ml/libc-alpha/2014-06/msg00835.html> and exposed by the tests added for such a bug in the x86 / x86-64 version. The bug and fix are essentially the same, so no separate bug is filed in Bugzilla. Tested for mips64. [BZ #16539] * sysdeps/ieee754/ldbl-128/s_expm1l.c: Include <float.h>. (__expm1l): Return argument unchanged when small but not subnormal.
Diffstat (limited to 'sysdeps')
| -rw-r--r-- | sysdeps/ieee754/ldbl-128/s_expm1l.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/sysdeps/ieee754/ldbl-128/s_expm1l.c b/sysdeps/ieee754/ldbl-128/s_expm1l.c index 1c12109511..f708af504c 100644 --- a/sysdeps/ieee754/ldbl-128/s_expm1l.c +++ b/sysdeps/ieee754/ldbl-128/s_expm1l.c @@ -54,6 +54,7 @@ #include <errno.h> +#include <float.h> #include <math.h> #include <math_private.h> @@ -136,6 +137,10 @@ __expm1l (long double x) if (x < minarg) return (4.0/big - 1.0L); + /* Avoid internal underflow when result does not underflow. */ + if (fabsl (x) < 0x1p-113L && fabsl (x) >= LDBL_MIN) + return x; + /* Express x = ln 2 (k + remainder), remainder not exceeding 1/2. */ xx = C1 + C2; /* ln 2. */ px = __floorl (0.5 + x / xx); |