llvm/libc/src/__support/FPUtil/except_value_utils.h

//===-- Common header for helpers to set exceptional values -----*- 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_EXCEPT_VALUE_UTILS_H
#define LLVM_LIBC_SRC___SUPPORT_FPUTIL_EXCEPT_VALUE_UTILS_H

#include "FEnvImpl.h"
#include "FPBits.h"
#include "cast.h"
#include "rounding_mode.h"
#include "src/__support/CPP/optional.h"
#include "src/__support/macros/config.h"
#include "src/__support/macros/optimization.h" // LIBC_UNLIKELY
#include "src/__support/macros/properties/cpu_features.h"
#include "src/__support/macros/properties/types.h"

namespace LIBC_NAMESPACE_DECL {

namespace fputil {

// This file contains utility functions and classes to manage exceptional values
// when there are many of them.
//
// Example usage:
//
// Define list of exceptional inputs and outputs:
//   static constexpr int N = ...;  // Number of exceptional values.
//   static constexpr fputil::ExceptValues<StorageType, N> Excepts {
//     <list of input bits, output bits and offsets>
//   };
//
// Check for exceptional inputs:
//   if (auto r = Excepts.lookup(x_bits); LIBC_UNLIKELY(r.has_value()))
//     return r.value();

template <typename T, size_t N> struct ExceptValues { … };

// Helper functions to set results for exceptional cases.
template <typename T> LIBC_INLINE T round_result_slightly_down(T value_rn) { … }

template <typename T> LIBC_INLINE T round_result_slightly_up(T value_rn) { … }

#if defined(LIBC_TYPES_HAS_FLOAT16) &&                                         \
    !defined(LIBC_TARGET_CPU_HAS_FAST_FLOAT16_OPS)
template <> LIBC_INLINE float16 round_result_slightly_down(float16 value_rn) { … }

template <> LIBC_INLINE float16 round_result_slightly_up(float16 value_rn) { … }
#endif

} // namespace fputil

} // namespace LIBC_NAMESPACE_DECL

#endif // LLVM_LIBC_SRC___SUPPORT_FPUTIL_EXCEPT_VALUE_UTILS_H