| /* |
| * 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. |
| * |
| * THIS SOFTWARE IS PROVIDED BY APPLE INC. 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 INC. 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 JITWriteBarrier_h |
| #define JITWriteBarrier_h |
| |
| #if ENABLE(JIT) |
| |
| #include "MacroAssembler.h" |
| #include "SlotVisitor.h" |
| #include "WriteBarrier.h" |
| |
| namespace JSC { |
| |
| class JSCell; |
| class JSGlobalData; |
| |
| // Needs to be even to appease some of the backends. |
| #define JITWriteBarrierFlag ((void*)2) |
| class JITWriteBarrierBase { |
| public: |
| typedef void* (JITWriteBarrierBase::*UnspecifiedBoolType); |
| operator UnspecifiedBoolType*() const { return get() ? reinterpret_cast<UnspecifiedBoolType*>(1) : 0; } |
| bool operator!() const { return !get(); } |
| |
| void setFlagOnBarrier() |
| { |
| ASSERT(!m_location); |
| m_location = CodeLocationDataLabelPtr(JITWriteBarrierFlag); |
| } |
| |
| bool isFlagged() const |
| { |
| return !!m_location; |
| } |
| |
| void setLocation(CodeLocationDataLabelPtr location) |
| { |
| ASSERT(!m_location); |
| m_location = location; |
| } |
| |
| CodeLocationDataLabelPtr location() const |
| { |
| ASSERT((!!m_location) && m_location.executableAddress() != JITWriteBarrierFlag); |
| return m_location; |
| } |
| |
| void clear() { clear(0); } |
| void clearToMaxUnsigned() { clear(reinterpret_cast<void*>(-1)); } |
| |
| protected: |
| JITWriteBarrierBase() |
| { |
| } |
| |
| void set(JSGlobalData&, CodeLocationDataLabelPtr location, JSCell* owner, JSCell* value) |
| { |
| Heap::writeBarrier(owner, value); |
| m_location = location; |
| ASSERT(((!!m_location) && m_location.executableAddress() != JITWriteBarrierFlag) || (location.executableAddress() == m_location.executableAddress())); |
| MacroAssembler::repatchPointer(m_location, value); |
| ASSERT(get() == value); |
| } |
| |
| JSCell* get() const |
| { |
| if (!m_location || m_location.executableAddress() == JITWriteBarrierFlag) |
| return 0; |
| void* result = static_cast<JSCell*>(MacroAssembler::readPointer(m_location)); |
| // We use -1 to indicate a "safe" empty value in the instruction stream |
| if (result == (void*)-1) |
| return 0; |
| return static_cast<JSCell*>(result); |
| } |
| |
| private: |
| void clear(void* clearedValue) |
| { |
| if (!m_location) |
| return; |
| if (m_location.executableAddress() != JITWriteBarrierFlag) |
| MacroAssembler::repatchPointer(m_location, clearedValue); |
| } |
| |
| CodeLocationDataLabelPtr m_location; |
| }; |
| |
| #undef JITWriteBarrierFlag |
| |
| template <typename T> class JITWriteBarrier : public JITWriteBarrierBase { |
| public: |
| JITWriteBarrier() |
| { |
| } |
| |
| void set(JSGlobalData& globalData, CodeLocationDataLabelPtr location, JSCell* owner, T* value) |
| { |
| validateCell(owner); |
| validateCell(value); |
| JITWriteBarrierBase::set(globalData, location, owner, value); |
| } |
| void set(JSGlobalData& globalData, JSCell* owner, T* value) |
| { |
| set(globalData, location(), owner, value); |
| } |
| T* get() const |
| { |
| T* result = static_cast<T*>(JITWriteBarrierBase::get()); |
| if (result) |
| validateCell(result); |
| return result; |
| } |
| }; |
| |
| template<typename T> inline void SlotVisitor::append(JITWriteBarrier<T>* slot) |
| { |
| internalAppend(slot->get()); |
| } |
| |
| } |
| |
| #endif // ENABLE(JIT) |
| |
| #endif |