diff options
Diffstat (limited to 'libstdc++-v3/include/experimental/numeric')
| -rw-r--r-- | libstdc++-v3/include/experimental/numeric | 46 |
1 files changed, 26 insertions, 20 deletions
diff --git a/libstdc++-v3/include/experimental/numeric b/libstdc++-v3/include/experimental/numeric index 4c6a662fdd6..426d9430dd6 100644 --- a/libstdc++-v3/include/experimental/numeric +++ b/libstdc++-v3/include/experimental/numeric @@ -56,17 +56,15 @@ inline namespace fundamentals_v2 constexpr common_type_t<_Mn, _Nn> gcd(_Mn __m, _Nn __n) noexcept { - static_assert(is_integral_v<_Mn>, - "std::experimental::gcd arguments must be integers"); - static_assert(is_integral_v<_Nn>, - "std::experimental::gcd arguments must be integers"); - static_assert(_Mn(2) != _Mn(1), - "std::experimental::gcd arguments must not be bool"); - static_assert(_Nn(2) != _Nn(1), - "std::experimental::gcd arguments must not be bool"); - using _Up = make_unsigned_t<common_type_t<_Mn, _Nn>>; - return std::__detail::__gcd(std::__detail::__absu<_Up>(__m), - std::__detail::__absu<_Up>(__n)); + static_assert(is_integral_v<_Mn> && is_integral_v<_Nn>, + "std::experimental::gcd arguments must be integers"); + static_assert(_Mn(2) == 2 && _Nn(2) == 2, + "std::experimental::gcd arguments must not be bool"); + namespace __detail = std::__detail; + using _Ct = common_type_t<_Mn, _Nn>; + const _Ct __m2 = __detail::__abs_r<_Ct>(__m); + const _Ct __n2 = __detail::__abs_r<_Ct>(__n); + return __detail::__gcd<make_unsigned_t<_Ct>>(__m2, __n2); } /// Least common multiple @@ -74,17 +72,25 @@ inline namespace fundamentals_v2 constexpr common_type_t<_Mn, _Nn> lcm(_Mn __m, _Nn __n) { - static_assert(is_integral_v<_Mn>, + static_assert(is_integral_v<_Mn> && is_integral_v<_Nn>, "std::experimental::lcm arguments must be integers"); - static_assert(is_integral_v<_Nn>, - "std::experimental::lcm arguments must be integers"); - static_assert(_Mn(2) != _Mn(1), - "std::experimental::lcm arguments must not be bool"); - static_assert(_Nn(2) != _Nn(1), + static_assert(_Mn(2) == 2 && _Nn(2) == 2, "std::experimental::lcm arguments must not be bool"); - using _Up = make_unsigned_t<common_type_t<_Mn, _Nn>>; - return std::__detail::__lcm(std::__detail::__absu<_Up>(__m), - std::__detail::__absu<_Up>(__n)); + namespace __detail = std::__detail; + using _Ct = common_type_t<_Mn, _Nn>; + const _Ct __m2 = __detail::__abs_r<_Ct>(__m); + const _Ct __n2 = __detail::__abs_r<_Ct>(__n); + if (__m2 == 0 || __n2 == 0) + return 0; + _Ct __r = __m2 / __detail::__gcd<make_unsigned_t<_Ct>>(__m2, __n2); + + if _GLIBCXX17_CONSTEXPR (is_signed_v<_Ct>) + if (__is_constant_evaluated()) + return __r * __n2; // constant evaluation can detect overflow here. + + bool __overflow = __builtin_mul_overflow(__r, __n2, &__r); + __glibcxx_assert(!__overflow); + return __r; } } // namespace fundamentals_v2 } // namespace experimental |