llvm/llvm/include/llvm/Support/CheckedArithmetic.h

//==-- llvm/Support/CheckedArithmetic.h - Safe arithmetical operations *- 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
//
//===----------------------------------------------------------------------===//
//
// This file contains generic functions for operating on integers which
// give the indication on whether the operation has overflown.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_SUPPORT_CHECKEDARITHMETIC_H
#define LLVM_SUPPORT_CHECKEDARITHMETIC_H

#include "llvm/ADT/APInt.h"

#include <optional>
#include <type_traits>

namespace {

/// Utility function to apply a given method of \c APInt \p F to \p LHS and
/// \p RHS.
/// \return Empty optional if the operation overflows, or result otherwise.
template <typename T, typename F>
std::enable_if_t<std::is_integral_v<T> && sizeof(T) * 8 <= 64, std::optional<T>>
checkedOp(T LHS, T RHS, F Op, bool Signed = true) { … }
}

namespace llvm {

/// Add two signed integers \p LHS and \p RHS.
/// \return Optional of sum if no signed overflow occurred,
/// \c std::nullopt otherwise.
template <typename T>
std::enable_if_t<std::is_signed_v<T>, std::optional<T>> checkedAdd(T LHS,
                                                                   T RHS) { … }

/// Subtract two signed integers \p LHS and \p RHS.
/// \return Optional of sum if no signed overflow occurred,
/// \c std::nullopt otherwise.
template <typename T>
std::enable_if_t<std::is_signed_v<T>, std::optional<T>> checkedSub(T LHS,
                                                                   T RHS) { … }

/// Multiply two signed integers \p LHS and \p RHS.
/// \return Optional of product if no signed overflow occurred,
/// \c std::nullopt otherwise.
template <typename T>
std::enable_if_t<std::is_signed_v<T>, std::optional<T>> checkedMul(T LHS,
                                                                   T RHS) { … }

/// Multiply A and B, and add C to the resulting product.
/// \return Optional of result if no signed overflow occurred,
/// \c std::nullopt otherwise.
template <typename T>
std::enable_if_t<std::is_signed_v<T>, std::optional<T>> checkedMulAdd(T A, T B,
                                                                      T C) { … }

/// Add two unsigned integers \p LHS and \p RHS.
/// \return Optional of sum if no unsigned overflow occurred,
/// \c std::nullopt otherwise.
template <typename T>
std::enable_if_t<std::is_unsigned_v<T>, std::optional<T>>
checkedAddUnsigned(T LHS, T RHS) { … }

/// Multiply two unsigned integers \p LHS and \p RHS.
/// \return Optional of product if no unsigned overflow occurred,
/// \c std::nullopt otherwise.
template <typename T>
std::enable_if_t<std::is_unsigned_v<T>, std::optional<T>>
checkedMulUnsigned(T LHS, T RHS) { … }

/// Multiply unsigned integers A and B, and add C to the resulting product.
/// \return Optional of result if no unsigned overflow occurred,
/// \c std::nullopt otherwise.
template <typename T>
std::enable_if_t<std::is_unsigned_v<T>, std::optional<T>>
checkedMulAddUnsigned(T A, T B, T C) { … }

} // End llvm namespace

#endif