| /* |
| * Copyright (C) 2011 Apple Inc. All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * |
| * 1. Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * 2. Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in the |
| * documentation and/or other materials provided with the distribution. |
| * 3. Neither the name of Apple Computer, Inc. ("Apple") nor the names of |
| * its contributors may be used to endorse or promote products derived |
| * from this software without specific prior written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY |
| * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED |
| * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE |
| * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY |
| * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES |
| * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
| * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND |
| * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
| * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| #ifndef CompactJITCodeMap_h |
| #define CompactJITCodeMap_h |
| |
| #include <wtf/Assertions.h> |
| #include <wtf/FastAllocBase.h> |
| #include <wtf/FastMalloc.h> |
| #include <wtf/OwnPtr.h> |
| #include <wtf/PassOwnPtr.h> |
| #include <wtf/UnusedParam.h> |
| #include <wtf/Vector.h> |
| |
| namespace JSC { |
| |
| // Gives you a compressed map between between bytecode indices and machine code |
| // entry points. The compression simply tries to use either 1, 2, or 4 bytes for |
| // any given offset. The largest offset that can be stored is 2^30. |
| |
| // Example use: |
| // |
| // CompactJITCodeMap::Encoder encoder(map); |
| // encoder.append(a, b); |
| // encoder.append(c, d); // preconditions: c >= a, d >= b |
| // OwnPtr<CompactJITCodeMap> map = encoder.finish(); |
| // |
| // At some later time: |
| // |
| // Vector<BytecodeAndMachineOffset> decoded; |
| // map->decode(decoded); |
| |
| struct BytecodeAndMachineOffset { |
| BytecodeAndMachineOffset() { } |
| |
| BytecodeAndMachineOffset(unsigned bytecodeIndex, unsigned machineCodeOffset) |
| : m_bytecodeIndex(bytecodeIndex) |
| , m_machineCodeOffset(machineCodeOffset) |
| { |
| } |
| |
| unsigned m_bytecodeIndex; |
| unsigned m_machineCodeOffset; |
| |
| static inline unsigned getBytecodeIndex(BytecodeAndMachineOffset* mapping) |
| { |
| return mapping->m_bytecodeIndex; |
| } |
| |
| static inline unsigned getMachineCodeOffset(BytecodeAndMachineOffset* mapping) |
| { |
| return mapping->m_machineCodeOffset; |
| } |
| }; |
| |
| class CompactJITCodeMap { |
| WTF_MAKE_FAST_ALLOCATED; |
| public: |
| ~CompactJITCodeMap() |
| { |
| if (m_buffer) |
| fastFree(m_buffer); |
| } |
| |
| unsigned numberOfEntries() const |
| { |
| return m_numberOfEntries; |
| } |
| |
| void decode(Vector<BytecodeAndMachineOffset>& result) const; |
| |
| private: |
| CompactJITCodeMap(uint8_t* buffer, unsigned size, unsigned numberOfEntries) |
| : m_buffer(buffer) |
| #if !ASSERT_DISABLED |
| , m_size(size) |
| #endif |
| , m_numberOfEntries(numberOfEntries) |
| { |
| UNUSED_PARAM(size); |
| } |
| |
| uint8_t at(unsigned index) const |
| { |
| ASSERT(index < m_size); |
| return m_buffer[index]; |
| } |
| |
| unsigned decodeNumber(unsigned& index) const |
| { |
| uint8_t headValue = at(index++); |
| if (!(headValue & 128)) |
| return headValue; |
| if (!(headValue & 64)) |
| return (static_cast<unsigned>(headValue & ~128) << 8) | at(index++); |
| unsigned second = at(index++); |
| unsigned third = at(index++); |
| unsigned fourth = at(index++); |
| return (static_cast<unsigned>(headValue & ~(128 + 64)) << 24) | (second << 16) | (third << 8) | fourth; |
| } |
| |
| uint8_t* m_buffer; |
| #if !ASSERT_DISABLED |
| unsigned m_size; |
| #endif |
| unsigned m_numberOfEntries; |
| |
| public: |
| class Encoder { |
| WTF_MAKE_NONCOPYABLE(Encoder); |
| public: |
| Encoder(); |
| ~Encoder(); |
| |
| void ensureCapacityFor(unsigned numberOfEntriesToAdd); |
| void append(unsigned bytecodeIndex, unsigned machineCodeOffset); |
| PassOwnPtr<CompactJITCodeMap> finish(); |
| |
| private: |
| void appendByte(uint8_t value); |
| void encodeNumber(uint32_t value); |
| |
| uint8_t* m_buffer; |
| unsigned m_size; |
| unsigned m_capacity; |
| unsigned m_numberOfEntries; |
| |
| unsigned m_previousBytecodeIndex; |
| unsigned m_previousMachineCodeOffset; |
| }; |
| |
| class Decoder { |
| WTF_MAKE_NONCOPYABLE(Decoder); |
| public: |
| Decoder(const CompactJITCodeMap*); |
| |
| unsigned numberOfEntriesRemaining() const; |
| void read(unsigned& bytecodeIndex, unsigned& machineCodeOffset); |
| |
| private: |
| const CompactJITCodeMap* m_jitCodeMap; |
| unsigned m_previousBytecodeIndex; |
| unsigned m_previousMachineCodeOffset; |
| unsigned m_numberOfEntriesRemaining; |
| unsigned m_bufferIndex; |
| }; |
| |
| private: |
| friend class Encoder; |
| friend class Decoder; |
| }; |
| |
| inline void CompactJITCodeMap::decode(Vector<BytecodeAndMachineOffset>& result) const |
| { |
| Decoder decoder(this); |
| result.resize(decoder.numberOfEntriesRemaining()); |
| for (unsigned i = 0; i < result.size(); ++i) |
| decoder.read(result[i].m_bytecodeIndex, result[i].m_machineCodeOffset); |
| |
| ASSERT(!decoder.numberOfEntriesRemaining()); |
| } |
| |
| inline CompactJITCodeMap::Encoder::Encoder() |
| : m_buffer(0) |
| , m_size(0) |
| , m_capacity(0) |
| , m_numberOfEntries(0) |
| , m_previousBytecodeIndex(0) |
| , m_previousMachineCodeOffset(0) |
| { |
| } |
| |
| inline CompactJITCodeMap::Encoder::~Encoder() |
| { |
| if (m_buffer) |
| fastFree(m_buffer); |
| } |
| |
| inline void CompactJITCodeMap::Encoder::append(unsigned bytecodeIndex, unsigned machineCodeOffset) |
| { |
| ASSERT(bytecodeIndex >= m_previousBytecodeIndex); |
| ASSERT(machineCodeOffset >= m_previousMachineCodeOffset); |
| ensureCapacityFor(1); |
| encodeNumber(bytecodeIndex - m_previousBytecodeIndex); |
| encodeNumber(machineCodeOffset - m_previousMachineCodeOffset); |
| m_previousBytecodeIndex = bytecodeIndex; |
| m_previousMachineCodeOffset = machineCodeOffset; |
| m_numberOfEntries++; |
| } |
| |
| inline PassOwnPtr<CompactJITCodeMap> CompactJITCodeMap::Encoder::finish() |
| { |
| m_capacity = m_size; |
| m_buffer = static_cast<uint8_t*>(fastRealloc(m_buffer, m_capacity)); |
| OwnPtr<CompactJITCodeMap> result = adoptPtr(new CompactJITCodeMap(m_buffer, m_size, m_numberOfEntries)); |
| m_buffer = 0; |
| m_size = 0; |
| m_capacity = 0; |
| m_numberOfEntries = 0; |
| m_previousBytecodeIndex = 0; |
| m_previousMachineCodeOffset = 0; |
| return result.release(); |
| } |
| |
| inline void CompactJITCodeMap::Encoder::appendByte(uint8_t value) |
| { |
| ASSERT(m_size + 1 <= m_capacity); |
| m_buffer[m_size++] = value; |
| } |
| |
| inline void CompactJITCodeMap::Encoder::encodeNumber(uint32_t value) |
| { |
| ASSERT(m_size + 4 <= m_capacity); |
| ASSERT(value < (1 << 30)); |
| if (value <= 127) { |
| uint8_t headValue = static_cast<uint8_t>(value); |
| ASSERT(!(headValue & 128)); |
| appendByte(headValue); |
| } else if (value <= 16383) { |
| uint8_t headValue = static_cast<uint8_t>(value >> 8); |
| ASSERT(!(headValue & 128)); |
| ASSERT(!(headValue & 64)); |
| appendByte(headValue | 128); |
| appendByte(static_cast<uint8_t>(value)); |
| } else { |
| uint8_t headValue = static_cast<uint8_t>(value >> 24); |
| ASSERT(!(headValue & 128)); |
| ASSERT(!(headValue & 64)); |
| appendByte(headValue | 128 | 64); |
| appendByte(static_cast<uint8_t>(value >> 16)); |
| appendByte(static_cast<uint8_t>(value >> 8)); |
| appendByte(static_cast<uint8_t>(value)); |
| } |
| } |
| |
| inline void CompactJITCodeMap::Encoder::ensureCapacityFor(unsigned numberOfEntriesToAdd) |
| { |
| unsigned capacityNeeded = m_size + numberOfEntriesToAdd * 2 * 4; |
| if (capacityNeeded > m_capacity) { |
| m_capacity = capacityNeeded * 2; |
| m_buffer = static_cast<uint8_t*>(fastRealloc(m_buffer, m_capacity)); |
| } |
| } |
| |
| inline CompactJITCodeMap::Decoder::Decoder(const CompactJITCodeMap* jitCodeMap) |
| : m_jitCodeMap(jitCodeMap) |
| , m_previousBytecodeIndex(0) |
| , m_previousMachineCodeOffset(0) |
| , m_numberOfEntriesRemaining(jitCodeMap->m_numberOfEntries) |
| , m_bufferIndex(0) |
| { |
| } |
| |
| inline unsigned CompactJITCodeMap::Decoder::numberOfEntriesRemaining() const |
| { |
| ASSERT(m_numberOfEntriesRemaining || m_bufferIndex == m_jitCodeMap->m_size); |
| return m_numberOfEntriesRemaining; |
| } |
| |
| inline void CompactJITCodeMap::Decoder::read(unsigned& bytecodeIndex, unsigned& machineCodeOffset) |
| { |
| ASSERT(numberOfEntriesRemaining()); |
| |
| m_previousBytecodeIndex += m_jitCodeMap->decodeNumber(m_bufferIndex); |
| m_previousMachineCodeOffset += m_jitCodeMap->decodeNumber(m_bufferIndex); |
| bytecodeIndex = m_previousBytecodeIndex; |
| machineCodeOffset = m_previousMachineCodeOffset; |
| m_numberOfEntriesRemaining--; |
| } |
| |
| } // namespace JSC |
| |
| #endif // CompactJITCodeMap_h |