heap/MarkedBlock.cpp

   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, JSCell::CreatingEarlyCell);
  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