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      1 /*
      2  * Copyright (C) 2011 Apple Inc. 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
      6  * are met:
      7  * 1. Redistributions of source code must retain the above copyright
      8  *    notice, this list of conditions and the following disclaimer.
      9  * 2. Redistributions in binary form must reproduce the above copyright
     10  *    notice, this list of conditions and the following disclaimer in the
     11  *    documentation and/or other materials provided with the distribution.
     12  *
     13  * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
     14  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
     15  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     16  * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
     17  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     18  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     19  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     20  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     21  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     22  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
     23  * THE POSSIBILITY OF SUCH DAMAGE.
     24  */
     25 
     26 #include "config.h"
     27 #include "MarkedBlock.h"
     28 
     29 #include "JSCell.h"
     30 #include "JSObject.h"
     31 #include "JSZombie.h"
     32 #include "ScopeChain.h"
     33 
     34 namespace JSC {
     35 
     36 MarkedBlock* MarkedBlock::create(JSGlobalData* globalData, size_t cellSize)
     37 {
     38     PageAllocationAligned allocation = PageAllocationAligned::allocate(blockSize, blockSize, OSAllocator::JSGCHeapPages);
     39     if (!static_cast<bool>(allocation))
     40         CRASH();
     41     return new (allocation.base()) MarkedBlock(allocation, globalData, cellSize);
     42 }
     43 
     44 void MarkedBlock::destroy(MarkedBlock* block)
     45 {
     46     for (size_t i = block->firstAtom(); i < block->m_endAtom; i += block->m_atomsPerCell)
     47         reinterpret_cast<JSCell*>(&block->atoms()[i])->~JSCell();
     48     block->m_allocation.deallocate();
     49 }
     50 
     51 MarkedBlock::MarkedBlock(const PageAllocationAligned& allocation, JSGlobalData* globalData, size_t cellSize)
     52     : m_nextAtom(firstAtom())
     53     , m_allocation(allocation)
     54     , m_heap(&globalData->heap)
     55     , m_prev(0)
     56     , m_next(0)
     57 {
     58     m_atomsPerCell = (cellSize + atomSize - 1) / atomSize;
     59     m_endAtom = atomsPerBlock - m_atomsPerCell + 1;
     60 
     61     Structure* dummyMarkableCellStructure = globalData->dummyMarkableCellStructure.get();
     62     for (size_t i = firstAtom(); i < m_endAtom; i += m_atomsPerCell)
     63         new (&atoms()[i]) JSCell(*globalData, dummyMarkableCellStructure);
     64 }
     65 
     66 void MarkedBlock::sweep()
     67 {
     68     Structure* dummyMarkableCellStructure = m_heap->globalData()->dummyMarkableCellStructure.get();
     69 
     70     for (size_t i = firstAtom(); i < m_endAtom; i += m_atomsPerCell) {
     71         if (m_marks.get(i))
     72             continue;
     73 
     74         JSCell* cell = reinterpret_cast<JSCell*>(&atoms()[i]);
     75 #if ENABLE(JSC_ZOMBIES)
     76         if (cell->structure() && cell->structure() != dummyMarkableCellStructure && !cell->isZombie()) {
     77             const ClassInfo* info = cell->classInfo();
     78             cell->~JSCell();
     79             new (cell) JSZombie(*m_heap->globalData(), info, m_heap->globalData()->zombieStructure.get());
     80             m_marks.set(i);
     81         }
     82 #else
     83         cell->~JSCell();
     84         new (cell) JSCell(*m_heap->globalData(), dummyMarkableCellStructure);
     85 #endif
     86     }
     87 }
     88 
     89 } // namespace JSC
     90