// Copyright 2017 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef BASE_NUMERICS_SAFE_MATH_SHARED_IMPL_H_
#define BASE_NUMERICS_SAFE_MATH_SHARED_IMPL_H_
#include <stddef.h>
#include <stdint.h>
#include <cassert>
#include <climits>
#include <cmath>
#include <cstdlib>
#include <limits>
#include <type_traits>
#include "base/numerics/safe_conversions.h"
// Where available use builtin math overflow support on Clang and GCC.
#if !defined(__native_client__) && \
((defined(__clang__) && \
((__clang_major__ > 3) || \
(__clang_major__ == 3 && __clang_minor__ >= 4))) || \
(defined(__GNUC__) && __GNUC__ >= 5))
#include "base/numerics/safe_math_clang_gcc_impl.h"
#define BASE_HAS_OPTIMIZED_SAFE_MATH (1)
#else
#define BASE_HAS_OPTIMIZED_SAFE_MATH (0)
#endif
namespace base {
namespace internal {
// These are the non-functioning boilerplate implementations of the optimized
// safe math routines.
#if !BASE_HAS_OPTIMIZED_SAFE_MATH
template <typename T, typename U>
struct CheckedAddFastOp {
static const bool is_supported = false;
template <typename V>
static constexpr bool Do(T, U, V*) {
// Force a compile failure if instantiated.
return CheckOnFailure::template HandleFailure<bool>();
}
};
template <typename T, typename U>
struct CheckedSubFastOp {
static const bool is_supported = false;
template <typename V>
static constexpr bool Do(T, U, V*) {
// Force a compile failure if instantiated.
return CheckOnFailure::template HandleFailure<bool>();
}
};
template <typename T, typename U>
struct CheckedMulFastOp {
static const bool is_supported = false;
template <typename V>
static constexpr bool Do(T, U, V*) {
// Force a compile failure if instantiated.
return CheckOnFailure::template HandleFailure<bool>();
}
};
template <typename T, typename U>
struct ClampedAddFastOp {
static const bool is_supported = false;
template <typename V>
static constexpr V Do(T, U) {
// Force a compile failure if instantiated.
return CheckOnFailure::template HandleFailure<V>();
}
};
template <typename T, typename U>
struct ClampedSubFastOp {
static const bool is_supported = false;
template <typename V>
static constexpr V Do(T, U) {
// Force a compile failure if instantiated.
return CheckOnFailure::template HandleFailure<V>();
}
};
template <typename T, typename U>
struct ClampedMulFastOp {
static const bool is_supported = false;
template <typename V>
static constexpr V Do(T, U) {
// Force a compile failure if instantiated.
return CheckOnFailure::template HandleFailure<V>();
}
};
template <typename T>
struct ClampedNegFastOp {
static const bool is_supported = false;
static constexpr T Do(T) {
// Force a compile failure if instantiated.
return CheckOnFailure::template HandleFailure<T>();
}
};
#endif // BASE_HAS_OPTIMIZED_SAFE_MATH
#undef BASE_HAS_OPTIMIZED_SAFE_MATH
// This is used for UnsignedAbs, where we need to support floating-point
// template instantiations even though we don't actually support the operations.
// However, there is no corresponding implementation of e.g. SafeUnsignedAbs,
// so the float versions will not compile.
template <typename Numeric,
bool IsInteger = std::is_integral<Numeric>::value,
bool IsFloat = std::is_floating_point<Numeric>::value>
struct UnsignedOrFloatForSize;
template <typename Numeric>
struct UnsignedOrFloatForSize<Numeric, true, false> {
using type = typename std::make_unsigned<Numeric>::type;
};
template <typename Numeric>
struct UnsignedOrFloatForSize<Numeric, false, true> {
using type = Numeric;
};
// Wrap the unary operations to allow SFINAE when instantiating integrals versus
// floating points. These don't perform any overflow checking. Rather, they
// exhibit well-defined overflow semantics and rely on the caller to detect
// if an overflow occured.
template <typename T,
typename std::enable_if<std::is_integral<T>::value>::type* = nullptr>
constexpr T NegateWrapper(T value) {
using UnsignedT = typename std::make_unsigned<T>::type;
// This will compile to a NEG on Intel, and is normal negation on ARM.
return static_cast<T>(UnsignedT(0) - static_cast<UnsignedT>(value));
}
template <
typename T,
typename std::enable_if<std::is_floating_point<T>::value>::type* = nullptr>
constexpr T NegateWrapper(T value) {
return -value;
}
template <typename T,
typename std::enable_if<std::is_integral<T>::value>::type* = nullptr>
constexpr typename std::make_unsigned<T>::type InvertWrapper(T value) {
return ~value;
}
template <typename T,
typename std::enable_if<std::is_integral<T>::value>::type* = nullptr>
constexpr T AbsWrapper(T value) {
return static_cast<T>(SafeUnsignedAbs(value));
}
template <
typename T,
typename std::enable_if<std::is_floating_point<T>::value>::type* = nullptr>
constexpr T AbsWrapper(T value) {
return value < 0 ? -value : value;
}
template <template <typename, typename, typename> class M,
typename L,
typename R>
struct MathWrapper {
using math = M<typename UnderlyingType<L>::type,
typename UnderlyingType<R>::type,
void>;
using type = typename math::result_type;
};
// These variadic templates work out the return types.
// TODO(jschuh): Rip all this out once we have C++14 non-trailing auto support.
template <template <typename, typename, typename> class M,
typename L,
typename R,
typename... Args>
struct ResultType;
template <template <typename, typename, typename> class M,
typename L,
typename R>
struct ResultType<M, L, R> {
using type = typename MathWrapper<M, L, R>::type;
};
template <template <typename, typename, typename> class M,
typename L,
typename R,
typename... Args>
struct ResultType {
using type =
typename ResultType<M, typename ResultType<M, L, R>::type, Args...>::type;
};
// The following macros are just boilerplate for the standard arithmetic
// operator overloads and variadic function templates. A macro isn't the nicest
// solution, but it beats rewriting these over and over again.
#define BASE_NUMERIC_ARITHMETIC_VARIADIC(CLASS, CL_ABBR, OP_NAME) \
template <typename L, typename R, typename... Args> \
constexpr CLASS##Numeric< \
typename ResultType<CLASS##OP_NAME##Op, L, R, Args...>::type> \
CL_ABBR##OP_NAME(const L lhs, const R rhs, const Args... args) { \
return CL_ABBR##MathOp<CLASS##OP_NAME##Op, L, R, Args...>(lhs, rhs, \
args...); \
}
#define BASE_NUMERIC_ARITHMETIC_OPERATORS(CLASS, CL_ABBR, OP_NAME, OP, CMP_OP) \
/* Binary arithmetic operator for all CLASS##Numeric operations. */ \
template <typename L, typename R, \
typename std::enable_if<Is##CLASS##Op<L, R>::value>::type* = \
nullptr> \
constexpr CLASS##Numeric< \
typename MathWrapper<CLASS##OP_NAME##Op, L, R>::type> \
operator OP(const L lhs, const R rhs) { \
return decltype(lhs OP rhs)::template MathOp<CLASS##OP_NAME##Op>(lhs, \
rhs); \
} \
/* Assignment arithmetic operator implementation from CLASS##Numeric. */ \
template <typename L> \
template <typename R> \
constexpr CLASS##Numeric<L>& CLASS##Numeric<L>::operator CMP_OP( \
const R rhs) { \
return MathOp<CLASS##OP_NAME##Op>(rhs); \
} \
/* Variadic arithmetic functions that return CLASS##Numeric. */ \
BASE_NUMERIC_ARITHMETIC_VARIADIC(CLASS, CL_ABBR, OP_NAME)
} // namespace internal
} // namespace base
#endif // BASE_NUMERICS_SAFE_MATH_SHARED_IMPL_H_