diff --git a/libcxx/include/__math/hypot.h b/libcxx/include/__math/hypot.h index 1bf193a9ab7ee9..61fd260c594095 100644 --- a/libcxx/include/__math/hypot.h +++ b/libcxx/include/__math/hypot.h @@ -15,10 +15,21 @@ #include <__type_traits/is_same.h> #include <__type_traits/promote.h> +#if _LIBCPP_STD_VER >= 17 +# include <__algorithm/max.h> +# include <__math/abs.h> +# include <__math/roots.h> +# include <__utility/pair.h> +# include +#endif + #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) # pragma GCC system_header #endif +_LIBCPP_PUSH_MACROS +#include <__undef_macros> + _LIBCPP_BEGIN_NAMESPACE_STD namespace __math { @@ -41,8 +52,86 @@ inline _LIBCPP_HIDE_FROM_ABI typename __promote<_A1, _A2>::type hypot(_A1 __x, _ return __math::hypot((__result_type)__x, (__result_type)__y); } +#if _LIBCPP_STD_VER >= 17 +// Factors needed to determine if over-/underflow might happen for `std::hypot(x,y,z)`. +// returns [overflow_threshold, overflow_scale] +template +_LIBCPP_HIDE_FROM_ABI std::pair<_Real, _Real> __hypot_factors() { + static_assert(std::numeric_limits<_Real>::is_iec559); + + if constexpr (std::is_same_v<_Real, float>) { + static_assert(-125 == std::numeric_limits<_Real>::min_exponent); + static_assert(+128 == std::numeric_limits<_Real>::max_exponent); + return {0x1.0p+62f, 0x1.0p-70f}; + } else if constexpr (std::is_same_v<_Real, double>) { + static_assert(-1021 == std::numeric_limits<_Real>::min_exponent); + static_assert(+1024 == std::numeric_limits<_Real>::max_exponent); + return {0x1.0p+510, 0x1.0p-600}; + } else { // long double + static_assert(std::is_same_v<_Real, long double>); + + // preprocessor guard necessary, otherwise literals (e.g. `0x1.0p+8'190l`) throw warnings even when shielded by `if + // constexpr` +# if __DBL_MAX_EXP__ == __LDBL_MAX_EXP__ + static_assert(sizeof(_Real) == sizeof(double)); + return static_cast>(__math::__hypot_factors()); +# else + static_assert(sizeof(_Real) > sizeof(double)); + static_assert(-16381 == std::numeric_limits<_Real>::min_exponent); + static_assert(+16384 == std::numeric_limits<_Real>::max_exponent); + return {0x1.0p+8190l, 0x1.0p-9000l}; +# endif + } +} + +// Computes the three-dimensional hypotenuse: `std::hypot(x,y,z)`. +// The naive implementation might over-/underflow which is why this implementation is more involved: +// If the square of an argument might run into issues, we scale the arguments appropriately. +// See https://github.com/llvm/llvm-project/issues/92782 for a detailed discussion and summary. +template +_LIBCPP_HIDE_FROM_ABI _Real __hypot(_Real __x, _Real __y, _Real __z) { + const _Real __max_abs = std::max(__math::fabs(__x), std::max(__math::fabs(__y), __math::fabs(__z))); + const auto [__overflow_threshold, __overflow_scale] = __math::__hypot_factors<_Real>(); + _Real __scale; + if (__max_abs > __overflow_threshold) { // x*x + y*y + z*z might overflow + __scale = __overflow_scale; + __x *= __scale; + __y *= __scale; + __z *= __scale; + } else if (__max_abs < 1 / __overflow_threshold) { // x*x + y*y + z*z might underflow + __scale = 1 / __overflow_scale; + __x *= __scale; + __y *= __scale; + __z *= __scale; + } else + __scale = 1; + return __math::sqrt(__x * __x + __y * __y + __z * __z) / __scale; +} + +inline _LIBCPP_HIDE_FROM_ABI float hypot(float __x, float __y, float __z) { return __math::__hypot(__x, __y, __z); } + +inline _LIBCPP_HIDE_FROM_ABI double hypot(double __x, double __y, double __z) { return __math::__hypot(__x, __y, __z); } + +inline _LIBCPP_HIDE_FROM_ABI long double hypot(long double __x, long double __y, long double __z) { + return __math::__hypot(__x, __y, __z); +} + +template && is_arithmetic_v<_A2> && is_arithmetic_v<_A3>, int> = 0 > +_LIBCPP_HIDE_FROM_ABI typename __promote<_A1, _A2, _A3>::type hypot(_A1 __x, _A2 __y, _A3 __z) _NOEXCEPT { + using __result_type = typename __promote<_A1, _A2, _A3>::type; + static_assert(!( + std::is_same_v<_A1, __result_type> && std::is_same_v<_A2, __result_type> && std::is_same_v<_A3, __result_type>)); + return __math::__hypot( + static_cast<__result_type>(__x), static_cast<__result_type>(__y), static_cast<__result_type>(__z)); +} +#endif + } // namespace __math _LIBCPP_END_NAMESPACE_STD +_LIBCPP_POP_MACROS #endif // _LIBCPP___MATH_HYPOT_H diff --git a/libcxx/include/cmath b/libcxx/include/cmath index 7a87e35c846036..e74b50ac86f67d 100644 --- a/libcxx/include/cmath +++ b/libcxx/include/cmath @@ -305,6 +305,7 @@ constexpr long double lerp(long double a, long double b, long double t) noexcept */ #include <__config> +#include <__math/hypot.h> #include <__type_traits/enable_if.h> #include <__type_traits/is_arithmetic.h> #include <__type_traits/is_constant_evaluated.h> @@ -544,30 +545,6 @@ using ::scalbnl _LIBCPP_USING_IF_EXISTS; using ::tgammal _LIBCPP_USING_IF_EXISTS; using ::truncl _LIBCPP_USING_IF_EXISTS; -#if _LIBCPP_STD_VER >= 17 -inline _LIBCPP_HIDE_FROM_ABI float hypot(float __x, float __y, float __z) { - return sqrt(__x * __x + __y * __y + __z * __z); -} -inline _LIBCPP_HIDE_FROM_ABI double hypot(double __x, double __y, double __z) { - return sqrt(__x * __x + __y * __y + __z * __z); -} -inline _LIBCPP_HIDE_FROM_ABI long double hypot(long double __x, long double __y, long double __z) { - return sqrt(__x * __x + __y * __y + __z * __z); -} - -template -inline _LIBCPP_HIDE_FROM_ABI -typename enable_if_t< is_arithmetic<_A1>::value && is_arithmetic<_A2>::value && is_arithmetic<_A3>::value, - __promote<_A1, _A2, _A3> >::type -hypot(_A1 __lcpp_x, _A2 __lcpp_y, _A3 __lcpp_z) _NOEXCEPT { - typedef typename __promote<_A1, _A2, _A3>::type __result_type; - static_assert( - !(is_same<_A1, __result_type>::value && is_same<_A2, __result_type>::value && is_same<_A3, __result_type>::value), - ""); - return std::hypot((__result_type)__lcpp_x, (__result_type)__lcpp_y, (__result_type)__lcpp_z); -} -#endif - template ::value, int> = 0> _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR bool __constexpr_isnan(_A1 __lcpp_x) _NOEXCEPT { #if __has_builtin(__builtin_isnan) diff --git a/libcxx/test/libcxx/transitive_includes/cxx17.csv b/libcxx/test/libcxx/transitive_includes/cxx17.csv index e03f74f50b9144..eb2fd355ee5995 100644 --- a/libcxx/test/libcxx/transitive_includes/cxx17.csv +++ b/libcxx/test/libcxx/transitive_includes/cxx17.csv @@ -130,6 +130,9 @@ chrono type_traits chrono vector chrono version cinttypes cstdint +cmath cstddef +cmath cstdint +cmath initializer_list cmath limits cmath type_traits cmath version diff --git a/libcxx/test/libcxx/transitive_includes/cxx20.csv b/libcxx/test/libcxx/transitive_includes/cxx20.csv index 37cd4e58e7fcad..298732a234a389 100644 --- a/libcxx/test/libcxx/transitive_includes/cxx20.csv +++ b/libcxx/test/libcxx/transitive_includes/cxx20.csv @@ -135,6 +135,9 @@ chrono type_traits chrono vector chrono version cinttypes cstdint +cmath cstddef +cmath cstdint +cmath initializer_list cmath limits cmath type_traits cmath version diff --git a/libcxx/test/libcxx/transitive_includes/cxx23.csv b/libcxx/test/libcxx/transitive_includes/cxx23.csv index 098752e8699f79..027e3f757b414f 100644 --- a/libcxx/test/libcxx/transitive_includes/cxx23.csv +++ b/libcxx/test/libcxx/transitive_includes/cxx23.csv @@ -83,6 +83,9 @@ chrono string_view chrono vector chrono version cinttypes cstdint +cmath cstddef +cmath cstdint +cmath initializer_list cmath limits cmath version codecvt cctype diff --git a/libcxx/test/libcxx/transitive_includes/cxx26.csv b/libcxx/test/libcxx/transitive_includes/cxx26.csv index 098752e8699f79..027e3f757b414f 100644 --- a/libcxx/test/libcxx/transitive_includes/cxx26.csv +++ b/libcxx/test/libcxx/transitive_includes/cxx26.csv @@ -83,6 +83,9 @@ chrono string_view chrono vector chrono version cinttypes cstdint +cmath cstddef +cmath cstdint +cmath initializer_list cmath limits cmath version codecvt cctype diff --git a/libcxx/test/std/numerics/c.math/cmath.pass.cpp b/libcxx/test/std/numerics/c.math/cmath.pass.cpp index 93790844997923..19b5fd0cf89966 100644 --- a/libcxx/test/std/numerics/c.math/cmath.pass.cpp +++ b/libcxx/test/std/numerics/c.math/cmath.pass.cpp @@ -12,14 +12,17 @@ // +#include #include #include #include #include +#include "fp_compare.h" #include "test_macros.h" #include "hexfloat.h" #include "truncate_fp.h" +#include "type_algorithms.h" // convertible to int/float/double/etc template @@ -1113,6 +1116,56 @@ void test_fmin() assert(std::fmin(1,0) == 0); } +#if TEST_STD_VER >= 17 +struct TestHypot3 { + template + void operator()() const { + const auto check = [](Real elem, Real abs_tol) { + assert(std::isfinite(std::hypot(elem, Real(0), Real(0)))); + assert(fptest_close(std::hypot(elem, Real(0), Real(0)), elem, abs_tol)); + assert(std::isfinite(std::hypot(elem, elem, Real(0)))); + assert(fptest_close(std::hypot(elem, elem, Real(0)), std::sqrt(Real(2)) * elem, abs_tol)); + assert(std::isfinite(std::hypot(elem, elem, elem))); + assert(fptest_close(std::hypot(elem, elem, elem), std::sqrt(Real(3)) * elem, abs_tol)); + }; + + { // check for overflow + const auto [elem, abs_tol] = []() -> std::array { + if constexpr (std::is_same_v) + return {1e20f, 1e16f}; + else if constexpr (std::is_same_v) + return {1e300, 1e287}; + else { // long double +# if __DBL_MAX_EXP__ == __LDBL_MAX_EXP__ + return {1e300l, 1e287l}; // 64-bit +# else + return {1e4000l, 1e3985l}; // 80- or 128-bit +# endif + } + }(); + check(elem, abs_tol); + } + + { // check for underflow + const auto [elem, abs_tol] = []() -> std::array { + if constexpr (std::is_same_v) + return {1e-20f, 1e-24f}; + else if constexpr (std::is_same_v) + return {1e-287, 1e-300}; + else { // long double +# if __DBL_MAX_EXP__ == __LDBL_MAX_EXP__ + return {1e-287l, 1e-300l}; // 64-bit +# else + return {1e-3985l, 1e-4000l}; // 80- or 128-bit +# endif + } + }(); + check(elem, abs_tol); + } + } +}; +#endif + void test_hypot() { static_assert((std::is_same::value), ""); @@ -1135,25 +1188,31 @@ void test_hypot() static_assert((std::is_same::value), ""); assert(std::hypot(3,4) == 5); -#if TEST_STD_VER > 14 - static_assert((std::is_same::value), ""); - static_assert((std::is_same::value), ""); - static_assert((std::is_same::value), ""); - static_assert((std::is_same::value), ""); - static_assert((std::is_same::value), ""); - static_assert((std::is_same::value), ""); - static_assert((std::is_same::value), ""); - static_assert((std::is_same::value), ""); - static_assert((std::is_same::value), ""); - static_assert((std::is_same::value), ""); - static_assert((std::is_same::value), ""); - static_assert((std::is_same::value), ""); - static_assert((std::is_same::value), ""); - static_assert((std::is_same::value), ""); - static_assert((std::is_same::value), ""); +#if TEST_STD_VER >= 17 + // clang-format off + static_assert((std::is_same_v)); + static_assert((std::is_same_v)); + static_assert((std::is_same_v)); + static_assert((std::is_same_v)); + static_assert((std::is_same_v)); + static_assert((std::is_same_v)); + static_assert((std::is_same_v)); + static_assert((std::is_same_v)); + static_assert((std::is_same_v)); + static_assert((std::is_same_v)); + static_assert((std::is_same_v)); + static_assert((std::is_same_v)); + static_assert((std::is_same_v)); + static_assert((std::is_same_v)); + static_assert((std::is_same_v)); + // clang-format on assert(std::hypot(2,3,6) == 7); assert(std::hypot(1,4,8) == 9); + + // Check for undue over-/underflows of intermediate results. + // See discussion at https://github.com/llvm/llvm-project/issues/92782. + types::for_each(types::floating_point_types(), TestHypot3()); #endif } diff --git a/libcxx/test/support/fp_compare.h b/libcxx/test/support/fp_compare.h index 1d1933b0bcd813..3088a211dadc3b 100644 --- a/libcxx/test/support/fp_compare.h +++ b/libcxx/test/support/fp_compare.h @@ -9,39 +9,34 @@ #ifndef SUPPORT_FP_COMPARE_H #define SUPPORT_FP_COMPARE_H -#include // for std::abs -#include // for std::max +#include // for std::abs +#include // for std::max #include +#include <__config> // See https://www.boost.org/doc/libs/1_70_0/libs/test/doc/html/boost_test/testing_tools/extended_comparison/floating_point/floating_points_comparison_theory.html -template -bool fptest_close(T val, T expected, T eps) -{ - constexpr T zero = T(0); - assert(eps >= zero); +template +bool fptest_close(T val, T expected, T eps) { + _LIBCPP_CONSTEXPR T zero = T(0); + assert(eps >= zero); - // Handle the zero cases - if (eps == zero) return val == expected; - if (val == zero) return std::abs(expected) <= eps; - if (expected == zero) return std::abs(val) <= eps; + // Handle the zero cases + if (eps == zero) + return val == expected; + if (val == zero) + return std::abs(expected) <= eps; + if (expected == zero) + return std::abs(val) <= eps; - return std::abs(val - expected) < eps - && std::abs(val - expected)/std::abs(val) < eps; + return std::abs(val - expected) < eps && std::abs(val - expected) / std::abs(val) < eps; } -template -bool fptest_close_pct(T val, T expected, T percent) -{ - constexpr T zero = T(0); - assert(percent >= zero); - - // Handle the zero cases - if (percent == zero) return val == expected; - T eps = (percent / T(100)) * std::max(std::abs(val), std::abs(expected)); - - return fptest_close(val, expected, eps); +template +bool fptest_close_pct(T val, T expected, T percent) { + assert(percent >= T(0)); + T eps = (percent / T(100)) * std::max(std::abs(val), std::abs(expected)); + return fptest_close(val, expected, eps); } - #endif // SUPPORT_FP_COMPARE_H