diff options
Diffstat (limited to 'sysdeps/ieee754/dbl-64/e_exp2.c')
| -rw-r--r-- | sysdeps/ieee754/dbl-64/e_exp2.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/sysdeps/ieee754/dbl-64/e_exp2.c b/sysdeps/ieee754/dbl-64/e_exp2.c index 948a756df7..30f0a8f529 100644 --- a/sysdeps/ieee754/dbl-64/e_exp2.c +++ b/sysdeps/ieee754/dbl-64/e_exp2.c @@ -96,7 +96,9 @@ __ieee754_exp2 (double x) /* 3. Compute ex2 = 2^(t/512+e+ex). */ ex2_u.d = exp2_accuratetable[tval & 511]; tval >>= 9; - unsafe = abs (tval) >= -DBL_MIN_EXP - 1; + /* x2 is an integer multiple of 2^-54; avoid intermediate + underflow from the calculation of x22 * x. */ + unsafe = abs (tval) >= -DBL_MIN_EXP - 56; ex2_u.ieee.exponent += tval >> unsafe; scale_u.d = 1.0; scale_u.ieee.exponent += tval - (tval >> unsafe); |