diff options
Diffstat (limited to 'sysdeps/ieee754/ldbl-128')
| -rw-r--r-- | sysdeps/ieee754/ldbl-128/s_fma.c | 8 | ||||
| -rw-r--r-- | sysdeps/ieee754/ldbl-128/s_fmal.c | 5 |
2 files changed, 12 insertions, 1 deletions
diff --git a/sysdeps/ieee754/ldbl-128/s_fma.c b/sysdeps/ieee754/ldbl-128/s_fma.c index 355b60e..b08ff29 100644 --- a/sysdeps/ieee754/ldbl-128/s_fma.c +++ b/sysdeps/ieee754/ldbl-128/s_fma.c @@ -1,5 +1,5 @@ /* Compute x * y + z as ternary operation. - Copyright (C) 2010 Free Software Foundation, Inc. + Copyright (C) 2010-2012 Free Software Foundation, Inc. This file is part of the GNU C Library. Contributed by Jakub Jelinek <jakub@redhat.com>, 2010. @@ -33,6 +33,12 @@ __fma (double x, double y, double z) fenv_t env; /* Multiplication is always exact. */ long double temp = (long double) x * (long double) y; + + /* Ensure correct sign of an exact zero result by performing the + addition in the original rounding mode in that case. */ + if (temp == -z) + return (double) temp + z; + union ieee854_long_double u; feholdexcept (&env); fesetround (FE_TOWARDZERO); diff --git a/sysdeps/ieee754/ldbl-128/s_fmal.c b/sysdeps/ieee754/ldbl-128/s_fmal.c index 963bbd7..df68ade 100644 --- a/sysdeps/ieee754/ldbl-128/s_fmal.c +++ b/sysdeps/ieee754/ldbl-128/s_fmal.c @@ -129,6 +129,11 @@ __fmal (long double x, long double y, long double z) y = v.d; z = w.d; } + + /* Ensure correct sign of exact 0 + 0. */ + if (__builtin_expect ((x == 0 || y == 0) && z == 0, 0)) + return x * y + z; + /* Multiplication m1 + m2 = x * y using Dekker's algorithm. */ #define C ((1LL << (LDBL_MANT_DIG + 1) / 2) + 1) long double x1 = x * C; |