diff options
Diffstat (limited to 'src/math')
| -rw-r--r-- | src/math/big/float.go | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/src/math/big/float.go b/src/math/big/float.go index 7e11f1aff5..afbed306f3 100644 --- a/src/math/big/float.go +++ b/src/math/big/float.go @@ -415,8 +415,9 @@ func (z *Float) round(sbit uint) { // bits > z.prec: mantissa too large => round r := uint(bits - z.prec - 1) // rounding bit position; r >= 0 rbit := z.mant.bit(r) & 1 // rounding bit; be safe and ensure it's a single bit - if sbit == 0 { - // TODO(gri) if rbit != 0 we don't need to compute sbit for some rounding modes (optimization) + // The sticky bit is only needed for rounding ToNearestEven + // or when the rounding bit is zero. Avoid computation otherwise. + if sbit == 0 && (rbit == 0 || z.mode == ToNearestEven) { sbit = z.mant.sticky(r) } sbit &= 1 // be safe and ensure it's a single bit |