585da50d7d
This PR adds the code of Boost.Math as of version 1.89 into the third-party directory, as discussed in a recent RFC [1]. The goal is for this code to be used as a back-end for the C++17 Math Special Functions. As explained in third-paty/README.md, this code is cleared for usage inside libc++ for the Math Special functions, however the LLVM Foundation should be consulted before using this code anywhere else in the LLVM project, due to the fact that it is under the Boost Software License (as opposed to the usual LLVM license). See the RFC [1] for more details. [1]: https://discourse.llvm.org/t/rfc-libc-taking-a-dependency-on-boost-math-for-the-c-17-math-special-functions
131 lines
4.2 KiB
C++
131 lines
4.2 KiB
C++
// (C) Copyright Matt Borland 2022.
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// Use, modification and distribution are subject to the
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// Boost Software License, Version 1.0. (See accompanying file
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// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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#ifndef BOOST_MATH_CCMATH_FMA_HPP
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#define BOOST_MATH_CCMATH_FMA_HPP
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#include <boost/math/ccmath/detail/config.hpp>
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#ifdef BOOST_MATH_NO_CCMATH
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#error "The header <boost/math/fma.hpp> can only be used in C++17 and later."
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#endif
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#include <boost/math/ccmath/isinf.hpp>
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#include <boost/math/ccmath/isnan.hpp>
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namespace boost::math::ccmath {
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namespace detail {
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template <typename T>
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constexpr T fma_imp(const T x, const T y, const T z) noexcept
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{
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#if defined(__GNUC__) && !defined(__clang__) && !defined(__INTEL_COMPILER) && !defined(__INTEL_LLVM_COMPILER)
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if constexpr (std::is_same_v<T, float>)
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{
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return __builtin_fmaf(x, y, z);
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}
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else if constexpr (std::is_same_v<T, double>)
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{
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return __builtin_fma(x, y, z);
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}
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else if constexpr (std::is_same_v<T, long double>)
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{
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return __builtin_fmal(x, y, z);
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}
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#endif
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// If we can't use compiler intrinsics hope that -fma flag optimizes this call to fma instruction
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return (x * y) + z;
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}
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} // Namespace detail
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template <typename Real, std::enable_if_t<!std::is_integral_v<Real>, bool> = true>
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constexpr Real fma(Real x, Real y, Real z) noexcept
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{
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if (BOOST_MATH_IS_CONSTANT_EVALUATED(x))
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{
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if (x == 0 && boost::math::ccmath::isinf(y))
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{
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return std::numeric_limits<Real>::quiet_NaN();
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}
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else if (y == 0 && boost::math::ccmath::isinf(x))
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{
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return std::numeric_limits<Real>::quiet_NaN();
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}
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else if (boost::math::ccmath::isnan(x))
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{
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return std::numeric_limits<Real>::quiet_NaN();
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}
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else if (boost::math::ccmath::isnan(y))
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{
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return std::numeric_limits<Real>::quiet_NaN();
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}
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else if (boost::math::ccmath::isnan(z))
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{
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return std::numeric_limits<Real>::quiet_NaN();
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}
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return boost::math::ccmath::detail::fma_imp(x, y, z);
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}
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else
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{
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using std::fma;
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return fma(x, y, z);
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}
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}
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template <typename T1, typename T2, typename T3>
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constexpr auto fma(T1 x, T2 y, T3 z) noexcept
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{
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if (BOOST_MATH_IS_CONSTANT_EVALUATED(x))
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{
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// If the type is an integer (e.g. epsilon == 0) then set the epsilon value to 1 so that type is at a minimum
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// cast to double
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constexpr auto T1p = std::numeric_limits<T1>::epsilon() > 0 ? std::numeric_limits<T1>::epsilon() : 1;
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constexpr auto T2p = std::numeric_limits<T2>::epsilon() > 0 ? std::numeric_limits<T2>::epsilon() : 1;
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constexpr auto T3p = std::numeric_limits<T3>::epsilon() > 0 ? std::numeric_limits<T3>::epsilon() : 1;
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using promoted_type =
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#ifndef BOOST_MATH_NO_LONG_DOUBLE_MATH_FUNCTIONS
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std::conditional_t<T1p <= LDBL_EPSILON && T1p <= T2p, T1,
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std::conditional_t<T2p <= LDBL_EPSILON && T2p <= T1p, T2,
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std::conditional_t<T3p <= LDBL_EPSILON && T3p <= T2p, T3,
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#endif
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std::conditional_t<T1p <= DBL_EPSILON && T1p <= T2p, T1,
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std::conditional_t<T2p <= DBL_EPSILON && T2p <= T1p, T2,
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std::conditional_t<T3p <= DBL_EPSILON && T3p <= T2p, T3, double
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#ifndef BOOST_MATH_NO_LONG_DOUBLE_MATH_FUNCTIONS
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>>>>>>;
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#else
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>>>;
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#endif
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return boost::math::ccmath::fma(promoted_type(x), promoted_type(y), promoted_type(z));
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}
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else
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{
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using std::fma;
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return fma(x, y, z);
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}
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}
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constexpr float fmaf(float x, float y, float z) noexcept
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{
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return boost::math::ccmath::fma(x, y, z);
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}
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#ifndef BOOST_MATH_NO_LONG_DOUBLE_MATH_FUNCTIONS
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constexpr long double fmal(long double x, long double y, long double z) noexcept
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{
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return boost::math::ccmath::fma(x, y, z);
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}
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#endif
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} // Namespace boost::math::ccmath
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#endif // BOOST_MATH_CCMATH_FMA_HPP
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