llvm/libc/src/__support/FPUtil/generic/FMA.h

//===-- Common header for FMA implementations -------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_LIBC_SRC___SUPPORT_FPUTIL_GENERIC_FMA_H
#define LLVM_LIBC_SRC___SUPPORT_FPUTIL_GENERIC_FMA_H

#include "src/__support/CPP/bit.h"
#include "src/__support/CPP/limits.h"
#include "src/__support/CPP/type_traits.h"
#include "src/__support/FPUtil/BasicOperations.h"
#include "src/__support/FPUtil/FPBits.h"
#include "src/__support/FPUtil/dyadic_float.h"
#include "src/__support/FPUtil/rounding_mode.h"
#include "src/__support/big_int.h"
#include "src/__support/macros/attributes.h"   // LIBC_INLINE
#include "src/__support/macros/config.h"
#include "src/__support/macros/optimization.h" // LIBC_UNLIKELY

#include "hdr/fenv_macros.h"

namespace LIBC_NAMESPACE_DECL {
namespace fputil {
namespace generic {

template <typename OutType, typename InType>
LIBC_INLINE cpp::enable_if_t<cpp::is_floating_point_v<OutType> &&
                                 cpp::is_floating_point_v<InType> &&
                                 sizeof(OutType) <= sizeof(InType),
                             OutType>
fma(InType x, InType y, InType z);

// TODO(lntue): Implement fmaf that is correctly rounded to all rounding modes.
// The implementation below only is only correct for the default rounding mode,
// round-to-nearest tie-to-even.
template <> LIBC_INLINE float fma<float>(float x, float y, float z) { … }

namespace internal {

// Extract the sticky bits and shift the `mantissa` to the right by
// `shift_length`.
template <typename T>
LIBC_INLINE cpp::enable_if_t<is_unsigned_integral_or_big_int_v<T>, bool>
shift_mantissa(int shift_length, T &mant) { … }

} // namespace internal

template <typename OutType, typename InType>
LIBC_INLINE cpp::enable_if_t<cpp::is_floating_point_v<OutType> &&
                                 cpp::is_floating_point_v<InType> &&
                                 sizeof(OutType) <= sizeof(InType),
                             OutType>
fma(InType x, InType y, InType z) { … }

} // namespace generic
} // namespace fputil
} // namespace LIBC_NAMESPACE_DECL

#endif // LLVM_LIBC_SRC___SUPPORT_FPUTIL_GENERIC_FMA_H