| /* |
| * Copyright (C) 2012 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 JSSegmentedVariableObject_h |
| #define JSSegmentedVariableObject_h |
| |
| #include "JSObject.h" |
| #include "JSSymbolTableObject.h" |
| #include "Register.h" |
| #include "SymbolTable.h" |
| #include <wtf/OwnArrayPtr.h> |
| #include <wtf/SegmentedVector.h> |
| #include <wtf/UnusedParam.h> |
| |
| namespace JSC { |
| |
| class LLIntOffsetsExtractor; |
| class Register; |
| |
| // This is a mostly drop-in replacement for JSVariableObject, except that it preserves |
| // the invariant that after a variable is created, its address in memory will not change |
| // so long as the JSSegmentedVariableObject is alive. This allows optimizations based |
| // on getting the address of the variable and remembering it. As well, unlike a |
| // JSVariableObject, this will manage the memory for the registers itself and neither |
| // requires nor allows for the subclasses to manage that memory. Finally, |
| // JSSegmentedVariableObject has its own GC tracing functionality, since it knows the |
| // exact dimensions of the variables array at all times. |
| |
| class JSSegmentedVariableObject : public JSSymbolTableObject { |
| friend class JIT; |
| friend class LLIntOffsetsExtractor; |
| |
| public: |
| typedef JSSymbolTableObject Base; |
| |
| WriteBarrier<Unknown>& registerAt(int index) { return m_registers[index]; } |
| |
| // This is a slow method call, which searches the register bank to find the index |
| // given a pointer. It will CRASH() if it does not find the register. Only use this |
| // in debug code (like bytecode dumping). |
| JS_EXPORT_PRIVATE int findRegisterIndex(void*); |
| |
| WriteBarrier<Unknown>* assertRegisterIsInThisObject(WriteBarrier<Unknown>* registerPointer) |
| { |
| #if !ASSERT_DISABLED |
| findRegisterIndex(registerPointer); |
| #endif |
| return registerPointer; |
| } |
| |
| // Adds numberOfRegistersToAdd registers, initializes them to Undefined, and returns |
| // the index of the first one added. |
| JS_EXPORT_PRIVATE int addRegisters(int numberOfRegistersToAdd); |
| |
| JS_EXPORT_PRIVATE static void visitChildren(JSCell*, SlotVisitor&); |
| |
| protected: |
| static const unsigned StructureFlags = OverridesVisitChildren | JSSymbolTableObject::StructureFlags; |
| |
| JSSegmentedVariableObject(JSGlobalData& globalData, Structure* structure, JSScope* scope) |
| : JSSymbolTableObject(globalData, structure, scope) |
| { |
| } |
| |
| void finishCreation(JSGlobalData& globalData) |
| { |
| Base::finishCreation(globalData); |
| } |
| |
| SegmentedVector<WriteBarrier<Unknown>, 16> m_registers; |
| }; |
| |
| } // namespace JSC |
| |
| #endif // JSSegmentedVariableObject_h |
| |