diff options
Diffstat (limited to 'libcxx/include/numeric')
| -rw-r--r-- | libcxx/include/numeric | 19 |
1 files changed, 8 insertions, 11 deletions
diff --git a/libcxx/include/numeric b/libcxx/include/numeric index 854bbfad65ac..5ceadc17755e 100644 --- a/libcxx/include/numeric +++ b/libcxx/include/numeric @@ -532,17 +532,14 @@ midpoint(_Tp __a, _Tp __b) noexcept _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK { using _Up = std::make_unsigned_t<_Tp>; + constexpr _Up __bitshift = std::numeric_limits<_Up>::digits - 1; - int __sign = 1; - _Up __m = __a; - _Up __M = __b; - if (__a > __b) - { - __sign = -1; - __m = __b; - __M = __a; - } - return __a + __sign * _Tp(_Up(__M-__m) >> 1); + _Up __diff = _Up(__b) - _Up(__a); + _Up __sign_bit = __b < __a; + + _Up __half_diff = (__diff / 2) + (__sign_bit << __bitshift) + (__sign_bit & __diff); + + return __a + __half_diff; } @@ -576,7 +573,7 @@ midpoint(_Fp __a, _Fp __b) noexcept return __fp_abs(__a) <= __hi && __fp_abs(__b) <= __hi ? // typical case: overflow is impossible (__a + __b)/2 : // always correctly rounded __fp_abs(__a) < __lo ? __a + __b/2 : // not safe to halve a - __fp_abs(__a) < __lo ? __a/2 + __b : // not safe to halve b + __fp_abs(__b) < __lo ? __a/2 + __b : // not safe to halve b __a/2 + __b/2; // otherwise correctly rounded } |