1 // Copyright 2016, VIXL authors 2 // All rights reserved. 3 // 4 // Redistribution and use in source and binary forms, with or without 5 // modification, are permitted provided that the following conditions are met: 6 // 7 // * Redistributions of source code must retain the above copyright notice, 8 // this list of conditions and the following disclaimer. 9 // * Redistributions in binary form must reproduce the above copyright notice, 10 // this list of conditions and the following disclaimer in the documentation 11 // and/or other materials provided with the distribution. 12 // * Neither the name of ARM Limited nor the names of its contributors may be 13 // used to endorse or promote products derived from this software without 14 // specific prior written permission. 15 // 16 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS CONTRIBUTORS "AS IS" AND 17 // ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 18 // WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 19 // DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE 20 // FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21 // DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 22 // SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 23 // CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 24 // OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 25 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 27 #ifndef VIXL_CODE_BUFFER_H 28 #define VIXL_CODE_BUFFER_H 29 30 #include <cstring> 31 32 #include "globals-vixl.h" 33 #include "utils-vixl.h" 34 35 namespace vixl { 36 37 class CodeBuffer { 38 public: 39 static const size_t kDefaultCapacity = 4 * KBytes; 40 41 explicit CodeBuffer(size_t capacity = kDefaultCapacity); 42 CodeBuffer(byte* buffer, size_t capacity); 43 ~CodeBuffer(); 44 45 void Reset(); 46 47 #ifdef VIXL_CODE_BUFFER_MMAP 48 void SetExecutable(); 49 void SetWritable(); 50 #else 51 // These require page-aligned memory blocks, which we can only guarantee with 52 // mmap. 53 VIXL_NO_RETURN_IN_DEBUG_MODE void SetExecutable() { VIXL_UNIMPLEMENTED(); } 54 VIXL_NO_RETURN_IN_DEBUG_MODE void SetWritable() { VIXL_UNIMPLEMENTED(); } 55 #endif 56 57 ptrdiff_t GetOffsetFrom(ptrdiff_t offset) const { 58 ptrdiff_t cursor_offset = cursor_ - buffer_; 59 VIXL_ASSERT((offset >= 0) && (offset <= cursor_offset)); 60 return cursor_offset - offset; 61 } 62 VIXL_DEPRECATED("GetOffsetFrom", 63 ptrdiff_t OffsetFrom(ptrdiff_t offset) const) { 64 return GetOffsetFrom(offset); 65 } 66 67 ptrdiff_t GetCursorOffset() const { return GetOffsetFrom(0); } 68 VIXL_DEPRECATED("GetCursorOffset", ptrdiff_t CursorOffset() const) { 69 return GetCursorOffset(); 70 } 71 72 void Rewind(ptrdiff_t offset) { 73 byte* rewound_cursor = buffer_ + offset; 74 VIXL_ASSERT((buffer_ <= rewound_cursor) && (rewound_cursor <= cursor_)); 75 cursor_ = rewound_cursor; 76 } 77 78 template <typename T> 79 T GetOffsetAddress(ptrdiff_t offset) const { 80 VIXL_STATIC_ASSERT(sizeof(T) >= sizeof(uintptr_t)); 81 VIXL_ASSERT((offset >= 0) && (offset <= (cursor_ - buffer_))); 82 return reinterpret_cast<T>(buffer_ + offset); 83 } 84 85 // Return the address of the start or end of the buffer. 86 template <typename T> 87 T GetStartAddress() const { 88 VIXL_STATIC_ASSERT(sizeof(T) >= sizeof(uintptr_t)); 89 return GetOffsetAddress<T>(0); 90 } 91 template <typename T> 92 T GetEndAddress() const { 93 VIXL_STATIC_ASSERT(sizeof(T) >= sizeof(uintptr_t)); 94 return GetOffsetAddress<T>(GetCapacity()); 95 } 96 97 size_t GetRemainingBytes() const { 98 VIXL_ASSERT((cursor_ >= buffer_) && (cursor_ <= (buffer_ + capacity_))); 99 return (buffer_ + capacity_) - cursor_; 100 } 101 VIXL_DEPRECATED("GetRemainingBytes", size_t RemainingBytes() const) { 102 return GetRemainingBytes(); 103 } 104 105 size_t GetSizeInBytes() const { 106 VIXL_ASSERT((cursor_ >= buffer_) && (cursor_ <= (buffer_ + capacity_))); 107 return cursor_ - buffer_; 108 } 109 110 // A code buffer can emit: 111 // * 16 or 32-bit data: instruction and constant. 112 // * 64-bit data: constant. 113 // * string: debug info. 114 void Emit16(uint16_t data) { Emit(data); } 115 116 void Emit32(uint32_t data) { Emit(data); } 117 118 void Emit64(uint64_t data) { Emit(data); } 119 120 void EmitString(const char* string); 121 122 void EmitData(const void* data, size_t size); 123 124 template <typename T> 125 void Emit(T value) { 126 VIXL_ASSERT(HasSpaceFor(sizeof(value))); 127 dirty_ = true; 128 memcpy(cursor_, &value, sizeof(value)); 129 cursor_ += sizeof(value); 130 } 131 132 void UpdateData(size_t offset, const void* data, size_t size); 133 134 // Align to 32bit. 135 void Align(); 136 137 bool Is16bitAligned() const { return IsAligned<2>(cursor_); } 138 139 bool Is32bitAligned() const { return IsAligned<4>(cursor_); } 140 141 size_t GetCapacity() const { return capacity_; } 142 VIXL_DEPRECATED("GetCapacity", size_t capacity() const) { 143 return GetCapacity(); 144 } 145 146 bool IsManaged() const { return managed_; } 147 148 void Grow(size_t new_capacity); 149 150 bool IsDirty() const { return dirty_; } 151 152 void SetClean() { dirty_ = false; } 153 154 bool HasSpaceFor(size_t amount) const { 155 return GetRemainingBytes() >= amount; 156 } 157 158 void EnsureSpaceFor(size_t amount, bool* has_grown) { 159 bool is_full = !HasSpaceFor(amount); 160 if (is_full) Grow(capacity_ * 2 + amount); 161 VIXL_ASSERT(has_grown != NULL); 162 *has_grown = is_full; 163 } 164 void EnsureSpaceFor(size_t amount) { 165 bool dummy; 166 EnsureSpaceFor(amount, &dummy); 167 } 168 169 private: 170 // Backing store of the buffer. 171 byte* buffer_; 172 // If true the backing store is allocated and deallocated by the buffer. The 173 // backing store can then grow on demand. If false the backing store is 174 // provided by the user and cannot be resized internally. 175 bool managed_; 176 // Pointer to the next location to be written. 177 byte* cursor_; 178 // True if there has been any write since the buffer was created or cleaned. 179 bool dirty_; 180 // Capacity in bytes of the backing store. 181 size_t capacity_; 182 }; 183 184 } // namespace vixl 185 186 #endif // VIXL_CODE_BUFFER_H 187
