| /* |
| * Copyright (C) 2009 University of Szeged |
| * 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. |
| * |
| * THIS SOFTWARE IS PROVIDED BY UNIVERSITY OF SZEGED ``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 UNIVERSITY OF SZEGED OR |
| * 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 AssemblerBufferWithConstantPool_h |
| #define AssemblerBufferWithConstantPool_h |
| |
| #if ENABLE(ASSEMBLER) |
| |
| #include "AssemblerBuffer.h" |
| #include <wtf/SegmentedVector.h> |
| |
| #define ASSEMBLER_HAS_CONSTANT_POOL 1 |
| |
| namespace JSC { |
| |
| /* |
| On a constant pool 4 or 8 bytes data can be stored. The values can be |
| constants or addresses. The addresses should be 32 or 64 bits. The constants |
| should be double-precisions float or integer numbers which are hard to be |
| encoded as few machine instructions. |
| |
| TODO: The pool is desinged to handle both 32 and 64 bits values, but |
| currently only the 4 bytes constants are implemented and tested. |
| |
| The AssemblerBuffer can contain multiple constant pools. Each pool is inserted |
| into the instruction stream - protected by a jump instruction from the |
| execution flow. |
| |
| The flush mechanism is called when no space remain to insert the next instruction |
| into the pool. Three values are used to determine when the constant pool itself |
| have to be inserted into the instruction stream (Assembler Buffer): |
| |
| - maxPoolSize: size of the constant pool in bytes, this value cannot be |
| larger than the maximum offset of a PC relative memory load |
| |
| - barrierSize: size of jump instruction in bytes which protects the |
| constant pool from execution |
| |
| - maxInstructionSize: maximum length of a machine instruction in bytes |
| |
| There are some callbacks which solve the target architecture specific |
| address handling: |
| |
| - TYPE patchConstantPoolLoad(TYPE load, int value): |
| patch the 'load' instruction with the index of the constant in the |
| constant pool and return the patched instruction. |
| |
| - void patchConstantPoolLoad(void* loadAddr, void* constPoolAddr): |
| patch the a PC relative load instruction at 'loadAddr' address with the |
| final relative offset. The offset can be computed with help of |
| 'constPoolAddr' (the address of the constant pool) and index of the |
| constant (which is stored previously in the load instruction itself). |
| |
| - TYPE placeConstantPoolBarrier(int size): |
| return with a constant pool barrier instruction which jumps over the |
| constant pool. |
| |
| The 'put*WithConstant*' functions should be used to place a data into the |
| constant pool. |
| */ |
| |
| template <int maxPoolSize, int barrierSize, int maxInstructionSize, class AssemblerType> |
| class AssemblerBufferWithConstantPool : public AssemblerBuffer { |
| typedef SegmentedVector<uint32_t, 512> LoadOffsets; |
| using AssemblerBuffer::putIntegral; |
| using AssemblerBuffer::putIntegralUnchecked; |
| public: |
| typedef struct { |
| short high; |
| short low; |
| } TwoShorts; |
| |
| enum { |
| UniqueConst, |
| ReusableConst, |
| UnusedEntry, |
| }; |
| |
| AssemblerBufferWithConstantPool() |
| : AssemblerBuffer() |
| , m_numConsts(0) |
| , m_maxDistance(maxPoolSize) |
| , m_lastConstDelta(0) |
| { |
| m_pool = static_cast<uint32_t*>(fastMalloc(maxPoolSize)); |
| m_mask = static_cast<char*>(fastMalloc(maxPoolSize / sizeof(uint32_t))); |
| } |
| |
| ~AssemblerBufferWithConstantPool() |
| { |
| fastFree(m_mask); |
| fastFree(m_pool); |
| } |
| |
| void ensureSpace(int space) |
| { |
| flushIfNoSpaceFor(space); |
| AssemblerBuffer::ensureSpace(space); |
| } |
| |
| void ensureSpace(int insnSpace, int constSpace) |
| { |
| flushIfNoSpaceFor(insnSpace, constSpace); |
| AssemblerBuffer::ensureSpace(insnSpace); |
| } |
| |
| void ensureSpaceForAnyInstruction(int amount = 1) |
| { |
| flushIfNoSpaceFor(amount * maxInstructionSize, amount * sizeof(uint64_t)); |
| } |
| |
| bool isAligned(int alignment) |
| { |
| flushIfNoSpaceFor(alignment); |
| return AssemblerBuffer::isAligned(alignment); |
| } |
| |
| void putByteUnchecked(int value) |
| { |
| AssemblerBuffer::putByteUnchecked(value); |
| correctDeltas(1); |
| } |
| |
| void putByte(int value) |
| { |
| flushIfNoSpaceFor(1); |
| AssemblerBuffer::putByte(value); |
| correctDeltas(1); |
| } |
| |
| void putShortUnchecked(int value) |
| { |
| AssemblerBuffer::putShortUnchecked(value); |
| correctDeltas(2); |
| } |
| |
| void putShort(int value) |
| { |
| flushIfNoSpaceFor(2); |
| AssemblerBuffer::putShort(value); |
| correctDeltas(2); |
| } |
| |
| void putIntUnchecked(int value) |
| { |
| AssemblerBuffer::putIntUnchecked(value); |
| correctDeltas(4); |
| } |
| |
| void putInt(int value) |
| { |
| flushIfNoSpaceFor(4); |
| AssemblerBuffer::putInt(value); |
| correctDeltas(4); |
| } |
| |
| void putInt64Unchecked(int64_t value) |
| { |
| AssemblerBuffer::putInt64Unchecked(value); |
| correctDeltas(8); |
| } |
| |
| void putIntegral(TwoShorts value) |
| { |
| putIntegral(value.high); |
| putIntegral(value.low); |
| } |
| |
| void putIntegralUnchecked(TwoShorts value) |
| { |
| putIntegralUnchecked(value.high); |
| putIntegralUnchecked(value.low); |
| } |
| |
| PassRefPtr<ExecutableMemoryHandle> executableCopy(JSGlobalData& globalData, void* ownerUID, JITCompilationEffort effort) |
| { |
| flushConstantPool(false); |
| return AssemblerBuffer::executableCopy(globalData, ownerUID, effort); |
| } |
| |
| void putShortWithConstantInt(uint16_t insn, uint32_t constant, bool isReusable = false) |
| { |
| putIntegralWithConstantInt(insn, constant, isReusable); |
| } |
| |
| void putIntWithConstantInt(uint32_t insn, uint32_t constant, bool isReusable = false) |
| { |
| putIntegralWithConstantInt(insn, constant, isReusable); |
| } |
| |
| // This flushing mechanism can be called after any unconditional jumps. |
| void flushWithoutBarrier(bool isForced = false) |
| { |
| // Flush if constant pool is more than 60% full to avoid overuse of this function. |
| if (isForced || 5 * static_cast<uint32_t>(m_numConsts) > 3 * maxPoolSize / sizeof(uint32_t)) |
| flushConstantPool(false); |
| } |
| |
| uint32_t* poolAddress() |
| { |
| return m_pool; |
| } |
| |
| int sizeOfConstantPool() |
| { |
| return m_numConsts; |
| } |
| |
| private: |
| void correctDeltas(int insnSize) |
| { |
| m_maxDistance -= insnSize; |
| m_lastConstDelta -= insnSize; |
| if (m_lastConstDelta < 0) |
| m_lastConstDelta = 0; |
| } |
| |
| void correctDeltas(int insnSize, int constSize) |
| { |
| correctDeltas(insnSize); |
| |
| m_maxDistance -= m_lastConstDelta; |
| m_lastConstDelta = constSize; |
| } |
| |
| template<typename IntegralType> |
| void putIntegralWithConstantInt(IntegralType insn, uint32_t constant, bool isReusable) |
| { |
| if (!m_numConsts) |
| m_maxDistance = maxPoolSize; |
| flushIfNoSpaceFor(sizeof(IntegralType), 4); |
| |
| m_loadOffsets.append(codeSize()); |
| if (isReusable) { |
| for (int i = 0; i < m_numConsts; ++i) { |
| if (m_mask[i] == ReusableConst && m_pool[i] == constant) { |
| putIntegral(static_cast<IntegralType>(AssemblerType::patchConstantPoolLoad(insn, i))); |
| correctDeltas(sizeof(IntegralType)); |
| return; |
| } |
| } |
| } |
| |
| m_pool[m_numConsts] = constant; |
| m_mask[m_numConsts] = static_cast<char>(isReusable ? ReusableConst : UniqueConst); |
| |
| putIntegral(static_cast<IntegralType>(AssemblerType::patchConstantPoolLoad(insn, m_numConsts))); |
| ++m_numConsts; |
| |
| correctDeltas(sizeof(IntegralType), 4); |
| } |
| |
| void flushConstantPool(bool useBarrier = true) |
| { |
| if (m_numConsts == 0) |
| return; |
| int alignPool = (codeSize() + (useBarrier ? barrierSize : 0)) & (sizeof(uint64_t) - 1); |
| |
| if (alignPool) |
| alignPool = sizeof(uint64_t) - alignPool; |
| |
| // Callback to protect the constant pool from execution |
| if (useBarrier) |
| putIntegral(AssemblerType::placeConstantPoolBarrier(m_numConsts * sizeof(uint32_t) + alignPool)); |
| |
| if (alignPool) { |
| if (alignPool & 1) |
| AssemblerBuffer::putByte(AssemblerType::padForAlign8); |
| if (alignPool & 2) |
| AssemblerBuffer::putShort(AssemblerType::padForAlign16); |
| if (alignPool & 4) |
| AssemblerBuffer::putInt(AssemblerType::padForAlign32); |
| } |
| |
| int constPoolOffset = codeSize(); |
| append(reinterpret_cast<char*>(m_pool), m_numConsts * sizeof(uint32_t)); |
| |
| // Patch each PC relative load |
| for (LoadOffsets::Iterator iter = m_loadOffsets.begin(); iter != m_loadOffsets.end(); ++iter) { |
| void* loadAddr = reinterpret_cast<char*>(data()) + *iter; |
| AssemblerType::patchConstantPoolLoad(loadAddr, reinterpret_cast<char*>(data()) + constPoolOffset); |
| } |
| |
| m_loadOffsets.clear(); |
| m_numConsts = 0; |
| } |
| |
| void flushIfNoSpaceFor(int nextInsnSize) |
| { |
| if (m_numConsts == 0) |
| return; |
| int lastConstDelta = m_lastConstDelta > nextInsnSize ? m_lastConstDelta - nextInsnSize : 0; |
| if ((m_maxDistance < nextInsnSize + lastConstDelta + barrierSize + (int)sizeof(uint32_t))) |
| flushConstantPool(); |
| } |
| |
| void flushIfNoSpaceFor(int nextInsnSize, int nextConstSize) |
| { |
| if (m_numConsts == 0) |
| return; |
| if ((m_maxDistance < nextInsnSize + m_lastConstDelta + nextConstSize + barrierSize + (int)sizeof(uint32_t)) || |
| (m_numConsts * sizeof(uint32_t) + nextConstSize >= maxPoolSize)) |
| flushConstantPool(); |
| } |
| |
| uint32_t* m_pool; |
| char* m_mask; |
| LoadOffsets m_loadOffsets; |
| |
| int m_numConsts; |
| int m_maxDistance; |
| int m_lastConstDelta; |
| }; |
| |
| } // namespace JSC |
| |
| #endif // ENABLE(ASSEMBLER) |
| |
| #endif // AssemblerBufferWithConstantPool_h |