| // 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 SAFEMATH_SAFE_MATH_SHARED_IMPL_H_ |
| #define SAFEMATH_SAFE_MATH_SHARED_IMPL_H_ |
| |
| #include <stddef.h> |
| #include <stdint.h> |
| |
| #include <math.h> |
| #include <cassert> |
| #include <climits> |
| #include <cstdlib> |
| #include <limits> |
| #include <type_traits> |
| |
| #include <safemath/safe_conversions.h> |
| |
| #ifdef __asmjs__ |
| // Optimized safe math instructions are incompatible with asmjs. |
| #define SAFEMATH_HAS_OPTIMIZED_SAFE_MATH (0) |
| // Where available use builtin math overflow support on Clang and GCC. |
| #elif !defined(__native_client__) && \ |
| ((defined(__clang__) && \ |
| ((__clang_major__ > 3) || \ |
| (__clang_major__ == 3 && __clang_minor__ >= 4))) || \ |
| (defined(__GNUC__) && __GNUC__ >= 5)) |
| #include <safemath/safe_math_clang_gcc_impl.h> |
| #define SAFEMATH_HAS_OPTIMIZED_SAFE_MATH (1) |
| #else |
| #define SAFEMATH_HAS_OPTIMIZED_SAFE_MATH (0) |
| #endif |
| |
| namespace safemath { |
| namespace internal { |
| |
| // These are the non-functioning boilerplate implementations of the optimized |
| // safe math routines. |
| #if !SAFEMATH_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 // SAFEMATH_HAS_OPTIMIZED_SAFE_MATH |
| #undef SAFEMATH_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 SAFEMATH_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 SAFEMATH_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. */ \ |
| SAFEMATH_NUMERIC_ARITHMETIC_VARIADIC(CLASS, CL_ABBR, OP_NAME) |
| |
| } // namespace internal |
| } // namespace safemath |
| |
| #endif // SAFEMATH_SAFE_MATH_SHARED_IMPL_H_ |