Martin Stjernholm | c15e7e4 | 2020-12-02 22:50:53 +0000 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2011 The Android Open Source Project |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | #ifndef ART_LIBARTBASE_BASE_MEMORY_REGION_H_ |
| 18 | #define ART_LIBARTBASE_BASE_MEMORY_REGION_H_ |
| 19 | |
| 20 | #include <stdint.h> |
| 21 | #include <type_traits> |
| 22 | |
| 23 | #include <android-base/logging.h> |
| 24 | |
| 25 | #include "bit_utils.h" |
| 26 | #include "casts.h" |
| 27 | #include "enums.h" |
| 28 | #include "globals.h" |
| 29 | #include "macros.h" |
| 30 | #include "value_object.h" |
| 31 | |
| 32 | namespace art { |
| 33 | |
| 34 | // Memory regions are useful for accessing memory with bounds check in |
| 35 | // debug mode. They can be safely passed by value and do not assume ownership |
| 36 | // of the region. |
| 37 | class MemoryRegion final : public ValueObject { |
| 38 | public: |
| 39 | struct ContentEquals { |
| 40 | constexpr bool operator()(const MemoryRegion& lhs, const MemoryRegion& rhs) const { |
| 41 | return lhs.size() == rhs.size() && memcmp(lhs.begin(), rhs.begin(), lhs.size()) == 0; |
| 42 | } |
| 43 | }; |
| 44 | |
| 45 | MemoryRegion() : pointer_(nullptr), size_(0) {} |
| 46 | MemoryRegion(void* pointer_in, uintptr_t size_in) : pointer_(pointer_in), size_(size_in) {} |
| 47 | |
| 48 | void* pointer() const { return pointer_; } |
| 49 | size_t size() const { return size_; } |
| 50 | size_t size_in_bits() const { return size_ * kBitsPerByte; } |
| 51 | |
| 52 | static size_t pointer_offset() { |
| 53 | return OFFSETOF_MEMBER(MemoryRegion, pointer_); |
| 54 | } |
| 55 | |
| 56 | uint8_t* begin() const { return reinterpret_cast<uint8_t*>(pointer_); } |
| 57 | uint8_t* end() const { return begin() + size_; } |
| 58 | |
| 59 | // Load value of type `T` at `offset`. The memory address corresponding |
| 60 | // to `offset` should be word-aligned (on ARM, this is a requirement). |
| 61 | template<typename T> |
| 62 | ALWAYS_INLINE T Load(uintptr_t offset) const { |
| 63 | T* address = ComputeInternalPointer<T>(offset); |
| 64 | DCHECK(IsWordAligned(address)); |
| 65 | return *address; |
| 66 | } |
| 67 | |
| 68 | // Store `value` (of type `T`) at `offset`. The memory address |
| 69 | // corresponding to `offset` should be word-aligned (on ARM, this is |
| 70 | // a requirement). |
| 71 | template<typename T> |
| 72 | ALWAYS_INLINE void Store(uintptr_t offset, T value) const { |
| 73 | T* address = ComputeInternalPointer<T>(offset); |
| 74 | DCHECK(IsWordAligned(address)); |
| 75 | *address = value; |
| 76 | } |
| 77 | |
| 78 | // Load value of type `T` at `offset`. The memory address corresponding |
| 79 | // to `offset` does not need to be word-aligned. |
| 80 | template<typename T> |
| 81 | ALWAYS_INLINE T LoadUnaligned(uintptr_t offset) const { |
| 82 | // Equivalent unsigned integer type corresponding to T. |
android-t1 | 3d2c5b2 | 2022-10-12 13:43:18 +0800 | [diff] [blame] | 83 | using U = std::make_unsigned_t<T>; |
Martin Stjernholm | c15e7e4 | 2020-12-02 22:50:53 +0000 | [diff] [blame] | 84 | U equivalent_unsigned_integer_value = 0; |
| 85 | // Read the value byte by byte in a little-endian fashion. |
| 86 | for (size_t i = 0; i < sizeof(U); ++i) { |
| 87 | equivalent_unsigned_integer_value += |
| 88 | *ComputeInternalPointer<uint8_t>(offset + i) << (i * kBitsPerByte); |
| 89 | } |
| 90 | return bit_cast<T, U>(equivalent_unsigned_integer_value); |
| 91 | } |
| 92 | |
| 93 | // Store `value` (of type `T`) at `offset`. The memory address |
| 94 | // corresponding to `offset` does not need to be word-aligned. |
| 95 | template<typename T> |
| 96 | ALWAYS_INLINE void StoreUnaligned(uintptr_t offset, T value) const { |
| 97 | // Equivalent unsigned integer type corresponding to T. |
android-t1 | 3d2c5b2 | 2022-10-12 13:43:18 +0800 | [diff] [blame] | 98 | using U = std::make_unsigned_t<T>; |
Martin Stjernholm | c15e7e4 | 2020-12-02 22:50:53 +0000 | [diff] [blame] | 99 | U equivalent_unsigned_integer_value = bit_cast<U, T>(value); |
| 100 | // Write the value byte by byte in a little-endian fashion. |
| 101 | for (size_t i = 0; i < sizeof(U); ++i) { |
| 102 | *ComputeInternalPointer<uint8_t>(offset + i) = |
| 103 | (equivalent_unsigned_integer_value >> (i * kBitsPerByte)) & 0xFF; |
| 104 | } |
| 105 | } |
| 106 | |
| 107 | template<typename T> |
| 108 | ALWAYS_INLINE T* PointerTo(uintptr_t offset) const { |
| 109 | return ComputeInternalPointer<T>(offset); |
| 110 | } |
| 111 | |
| 112 | void CopyFrom(size_t offset, const MemoryRegion& from) const; |
| 113 | |
| 114 | template<class Vector> |
| 115 | void CopyFromVector(size_t offset, Vector& vector) const { |
| 116 | if (!vector.empty()) { |
| 117 | CopyFrom(offset, MemoryRegion(vector.data(), vector.size())); |
| 118 | } |
| 119 | } |
| 120 | |
| 121 | // Compute a sub memory region based on an existing one. |
| 122 | ALWAYS_INLINE MemoryRegion Subregion(uintptr_t offset, uintptr_t size_in) const { |
| 123 | CHECK_GE(this->size(), size_in); |
| 124 | CHECK_LE(offset, this->size() - size_in); |
| 125 | return MemoryRegion(reinterpret_cast<void*>(begin() + offset), size_in); |
| 126 | } |
| 127 | |
| 128 | // Compute an extended memory region based on an existing one. |
| 129 | ALWAYS_INLINE void Extend(const MemoryRegion& region, uintptr_t extra) { |
| 130 | pointer_ = region.pointer(); |
| 131 | size_ = (region.size() + extra); |
| 132 | } |
| 133 | |
| 134 | private: |
| 135 | template<typename T> |
| 136 | ALWAYS_INLINE T* ComputeInternalPointer(size_t offset) const { |
| 137 | CHECK_GE(size(), sizeof(T)); |
| 138 | CHECK_LE(offset, size() - sizeof(T)); |
| 139 | return reinterpret_cast<T*>(begin() + offset); |
| 140 | } |
| 141 | |
| 142 | // Locate the bit with the given offset. Returns a pointer to the byte |
| 143 | // containing the bit, and sets bit_mask to the bit within that byte. |
| 144 | ALWAYS_INLINE uint8_t* ComputeBitPointer(uintptr_t bit_offset, uint8_t* bit_mask) const { |
| 145 | uintptr_t bit_remainder = (bit_offset & (kBitsPerByte - 1)); |
| 146 | *bit_mask = (1U << bit_remainder); |
| 147 | uintptr_t byte_offset = (bit_offset >> kBitsPerByteLog2); |
| 148 | return ComputeInternalPointer<uint8_t>(byte_offset); |
| 149 | } |
| 150 | |
| 151 | // Is `address` aligned on a machine word? |
| 152 | template<typename T> static constexpr bool IsWordAligned(const T* address) { |
| 153 | // Word alignment in bytes. Determined from pointer size. |
| 154 | return IsAligned<kRuntimePointerSize>(address); |
| 155 | } |
| 156 | |
| 157 | void* pointer_; |
| 158 | size_t size_; |
| 159 | }; |
| 160 | |
| 161 | } // namespace art |
| 162 | |
| 163 | #endif // ART_LIBARTBASE_BASE_MEMORY_REGION_H_ |