kumarashishg | 826308d | 2023-06-23 13:21:22 +0000 | [diff] [blame] | 1 | // Copyright 2017 The Chromium Authors. All rights reserved. |
| 2 | // Use of this source code is governed by a BSD-style license that can be |
| 3 | // found in the LICENSE file. |
| 4 | |
| 5 | #ifndef THIRD_PARTY_BASE_NUMERICS_SAFE_MATH_SHARED_IMPL_H_ |
| 6 | #define THIRD_PARTY_BASE_NUMERICS_SAFE_MATH_SHARED_IMPL_H_ |
| 7 | |
| 8 | #include <stddef.h> |
| 9 | #include <stdint.h> |
| 10 | |
| 11 | #include <cassert> |
| 12 | #include <climits> |
| 13 | #include <cmath> |
| 14 | #include <cstdlib> |
| 15 | #include <limits> |
| 16 | #include <type_traits> |
| 17 | |
| 18 | #include "build/build_config.h" |
| 19 | #include "third_party/base/numerics/safe_conversions.h" |
| 20 | |
| 21 | #if BUILDFLAG(IS_ASMJS) |
| 22 | // Optimized safe math instructions are incompatible with asmjs. |
| 23 | #define BASE_HAS_OPTIMIZED_SAFE_MATH (0) |
| 24 | // Where available use builtin math overflow support on Clang and GCC. |
| 25 | #elif !defined(__native_client__) && \ |
| 26 | ((defined(__clang__) && \ |
| 27 | ((__clang_major__ > 3) || \ |
| 28 | (__clang_major__ == 3 && __clang_minor__ >= 4))) || \ |
| 29 | (defined(__GNUC__) && __GNUC__ >= 5)) |
| 30 | #include "third_party/base/numerics/safe_math_clang_gcc_impl.h" |
| 31 | #define BASE_HAS_OPTIMIZED_SAFE_MATH (1) |
| 32 | #else |
| 33 | #define BASE_HAS_OPTIMIZED_SAFE_MATH (0) |
| 34 | #endif |
| 35 | |
| 36 | namespace pdfium { |
| 37 | namespace base { |
| 38 | namespace internal { |
| 39 | |
| 40 | // These are the non-functioning boilerplate implementations of the optimized |
| 41 | // safe math routines. |
| 42 | #if !BASE_HAS_OPTIMIZED_SAFE_MATH |
| 43 | template <typename T, typename U> |
| 44 | struct CheckedAddFastOp { |
| 45 | static const bool is_supported = false; |
| 46 | template <typename V> |
| 47 | static constexpr bool Do(T, U, V*) { |
| 48 | // Force a compile failure if instantiated. |
| 49 | return CheckOnFailure::template HandleFailure<bool>(); |
| 50 | } |
| 51 | }; |
| 52 | |
| 53 | template <typename T, typename U> |
| 54 | struct CheckedSubFastOp { |
| 55 | static const bool is_supported = false; |
| 56 | template <typename V> |
| 57 | static constexpr bool Do(T, U, V*) { |
| 58 | // Force a compile failure if instantiated. |
| 59 | return CheckOnFailure::template HandleFailure<bool>(); |
| 60 | } |
| 61 | }; |
| 62 | |
| 63 | template <typename T, typename U> |
| 64 | struct CheckedMulFastOp { |
| 65 | static const bool is_supported = false; |
| 66 | template <typename V> |
| 67 | static constexpr bool Do(T, U, V*) { |
| 68 | // Force a compile failure if instantiated. |
| 69 | return CheckOnFailure::template HandleFailure<bool>(); |
| 70 | } |
| 71 | }; |
| 72 | |
| 73 | template <typename T, typename U> |
| 74 | struct ClampedAddFastOp { |
| 75 | static const bool is_supported = false; |
| 76 | template <typename V> |
| 77 | static constexpr V Do(T, U) { |
| 78 | // Force a compile failure if instantiated. |
| 79 | return CheckOnFailure::template HandleFailure<V>(); |
| 80 | } |
| 81 | }; |
| 82 | |
| 83 | template <typename T, typename U> |
| 84 | struct ClampedSubFastOp { |
| 85 | static const bool is_supported = false; |
| 86 | template <typename V> |
| 87 | static constexpr V Do(T, U) { |
| 88 | // Force a compile failure if instantiated. |
| 89 | return CheckOnFailure::template HandleFailure<V>(); |
| 90 | } |
| 91 | }; |
| 92 | |
| 93 | template <typename T, typename U> |
| 94 | struct ClampedMulFastOp { |
| 95 | static const bool is_supported = false; |
| 96 | template <typename V> |
| 97 | static constexpr V Do(T, U) { |
| 98 | // Force a compile failure if instantiated. |
| 99 | return CheckOnFailure::template HandleFailure<V>(); |
| 100 | } |
| 101 | }; |
| 102 | |
| 103 | template <typename T> |
| 104 | struct ClampedNegFastOp { |
| 105 | static const bool is_supported = false; |
| 106 | static constexpr T Do(T) { |
| 107 | // Force a compile failure if instantiated. |
| 108 | return CheckOnFailure::template HandleFailure<T>(); |
| 109 | } |
| 110 | }; |
| 111 | #endif // BASE_HAS_OPTIMIZED_SAFE_MATH |
| 112 | #undef BASE_HAS_OPTIMIZED_SAFE_MATH |
| 113 | |
| 114 | // This is used for UnsignedAbs, where we need to support floating-point |
| 115 | // template instantiations even though we don't actually support the operations. |
| 116 | // However, there is no corresponding implementation of e.g. SafeUnsignedAbs, |
| 117 | // so the float versions will not compile. |
| 118 | template <typename Numeric, |
| 119 | bool IsInteger = std::is_integral<Numeric>::value, |
| 120 | bool IsFloat = std::is_floating_point<Numeric>::value> |
| 121 | struct UnsignedOrFloatForSize; |
| 122 | |
| 123 | template <typename Numeric> |
| 124 | struct UnsignedOrFloatForSize<Numeric, true, false> { |
| 125 | using type = typename std::make_unsigned<Numeric>::type; |
| 126 | }; |
| 127 | |
| 128 | template <typename Numeric> |
| 129 | struct UnsignedOrFloatForSize<Numeric, false, true> { |
| 130 | using type = Numeric; |
| 131 | }; |
| 132 | |
| 133 | // Wrap the unary operations to allow SFINAE when instantiating integrals versus |
| 134 | // floating points. These don't perform any overflow checking. Rather, they |
| 135 | // exhibit well-defined overflow semantics and rely on the caller to detect |
| 136 | // if an overflow occurred. |
| 137 | |
| 138 | template <typename T, |
| 139 | typename std::enable_if<std::is_integral<T>::value>::type* = nullptr> |
| 140 | constexpr T NegateWrapper(T value) { |
| 141 | using UnsignedT = typename std::make_unsigned<T>::type; |
| 142 | // This will compile to a NEG on Intel, and is normal negation on ARM. |
| 143 | return static_cast<T>(UnsignedT(0) - static_cast<UnsignedT>(value)); |
| 144 | } |
| 145 | |
| 146 | template < |
| 147 | typename T, |
| 148 | typename std::enable_if<std::is_floating_point<T>::value>::type* = nullptr> |
| 149 | constexpr T NegateWrapper(T value) { |
| 150 | return -value; |
| 151 | } |
| 152 | |
| 153 | template <typename T, |
| 154 | typename std::enable_if<std::is_integral<T>::value>::type* = nullptr> |
| 155 | constexpr typename std::make_unsigned<T>::type InvertWrapper(T value) { |
| 156 | return ~value; |
| 157 | } |
| 158 | |
| 159 | template <typename T, |
| 160 | typename std::enable_if<std::is_integral<T>::value>::type* = nullptr> |
| 161 | constexpr T AbsWrapper(T value) { |
| 162 | return static_cast<T>(SafeUnsignedAbs(value)); |
| 163 | } |
| 164 | |
| 165 | template < |
| 166 | typename T, |
| 167 | typename std::enable_if<std::is_floating_point<T>::value>::type* = nullptr> |
| 168 | constexpr T AbsWrapper(T value) { |
| 169 | return value < 0 ? -value : value; |
| 170 | } |
| 171 | |
| 172 | template <template <typename, typename, typename> class M, |
| 173 | typename L, |
| 174 | typename R> |
| 175 | struct MathWrapper { |
| 176 | using math = M<typename UnderlyingType<L>::type, |
| 177 | typename UnderlyingType<R>::type, |
| 178 | void>; |
| 179 | using type = typename math::result_type; |
| 180 | }; |
| 181 | |
| 182 | // The following macros are just boilerplate for the standard arithmetic |
| 183 | // operator overloads and variadic function templates. A macro isn't the nicest |
| 184 | // solution, but it beats rewriting these over and over again. |
| 185 | #define BASE_NUMERIC_ARITHMETIC_VARIADIC(CLASS, CL_ABBR, OP_NAME) \ |
| 186 | template <typename L, typename R, typename... Args> \ |
| 187 | constexpr auto CL_ABBR##OP_NAME(const L lhs, const R rhs, \ |
| 188 | const Args... args) { \ |
| 189 | return CL_ABBR##MathOp<CLASS##OP_NAME##Op, L, R, Args...>(lhs, rhs, \ |
| 190 | args...); \ |
| 191 | } |
| 192 | |
| 193 | #define BASE_NUMERIC_ARITHMETIC_OPERATORS(CLASS, CL_ABBR, OP_NAME, OP, CMP_OP) \ |
| 194 | /* Binary arithmetic operator for all CLASS##Numeric operations. */ \ |
| 195 | template <typename L, typename R, \ |
| 196 | typename std::enable_if<Is##CLASS##Op<L, R>::value>::type* = \ |
| 197 | nullptr> \ |
| 198 | constexpr CLASS##Numeric< \ |
| 199 | typename MathWrapper<CLASS##OP_NAME##Op, L, R>::type> \ |
| 200 | operator OP(const L lhs, const R rhs) { \ |
| 201 | return decltype(lhs OP rhs)::template MathOp<CLASS##OP_NAME##Op>(lhs, \ |
| 202 | rhs); \ |
| 203 | } \ |
| 204 | /* Assignment arithmetic operator implementation from CLASS##Numeric. */ \ |
| 205 | template <typename L> \ |
| 206 | template <typename R> \ |
| 207 | constexpr CLASS##Numeric<L>& CLASS##Numeric<L>::operator CMP_OP( \ |
| 208 | const R rhs) { \ |
| 209 | return MathOp<CLASS##OP_NAME##Op>(rhs); \ |
| 210 | } \ |
| 211 | /* Variadic arithmetic functions that return CLASS##Numeric. */ \ |
| 212 | BASE_NUMERIC_ARITHMETIC_VARIADIC(CLASS, CL_ABBR, OP_NAME) |
| 213 | |
| 214 | } // namespace internal |
| 215 | } // namespace base |
| 216 | } // namespace pdfium |
| 217 | |
| 218 | #endif // THIRD_PARTY_BASE_NUMERICS_SAFE_MATH_SHARED_IMPL_H_ |