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/*
* Copyright (C) 1999-2000 Harri Porten (porten@kde.org)
* Copyright (C) 2001 Peter Kelly (pmk@post.com)
* Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
*/
#ifndef MarkedBlock_h
#define MarkedBlock_h
#include <wtf/Bitmap.h>
#include <wtf/FixedArray.h>
#include <wtf/PageAllocationAligned.h>
#define ASSERT_CLASS_FITS_IN_CELL(class) COMPILE_ASSERT(sizeof(class) <= MarkedBlock::CELL_SIZE, class_fits_in_cell)
namespace JSC {
class Heap;
class JSCell;
class JSGlobalData;
class MarkedBlock {
#if OS(WINCE) || OS(SYMBIAN) || PLATFORM(BREWMP)
static const size_t BLOCK_SIZE = 64 * 1024; // 64k
#else
static const size_t BLOCK_SIZE = 256 * 1024; // 256k
#endif
static const size_t BLOCK_OFFSET_MASK = BLOCK_SIZE - 1;
static const size_t BLOCK_MASK = ~BLOCK_OFFSET_MASK;
static const size_t MINIMUM_CELL_SIZE = 64;
static const size_t CELL_ARRAY_LENGTH = (MINIMUM_CELL_SIZE / sizeof(double)) + (MINIMUM_CELL_SIZE % sizeof(double) != 0 ? sizeof(double) : 0);
public:
// This is still public for now, for use in assertions.
static const size_t CELL_SIZE = CELL_ARRAY_LENGTH * sizeof(double);
private:
static const size_t SMALL_CELL_SIZE = CELL_SIZE / 2;
static const size_t CELL_MASK = CELL_SIZE - 1;
static const size_t CELL_ALIGN_MASK = ~CELL_MASK;
static const size_t BITS_PER_BLOCK = BLOCK_SIZE / CELL_SIZE;
static const size_t CELLS_PER_BLOCK = (BLOCK_SIZE - sizeof(Heap*) - sizeof(WTF::Bitmap<BITS_PER_BLOCK>)) / CELL_SIZE; // Division rounds down intentionally.
struct CollectorCell {
FixedArray<double, CELL_ARRAY_LENGTH> memory;
};
// Cell size needs to be a power of two for CELL_MASK to be valid.
COMPILE_ASSERT(!(sizeof(CollectorCell) % 2), Collector_cell_size_is_power_of_two);
public:
static MarkedBlock* create(JSGlobalData*);
static void destroy(MarkedBlock*);
static bool isCellAligned(const void*);
static MarkedBlock* blockFor(const void*);
Heap* heap() const;
void* allocate(size_t& nextCell);
void sweep();
bool isEmpty();
void clearMarks();
size_t markCount();
size_t size();
size_t capacity();
size_t cellNumber(const void*);
bool isMarked(const void*);
bool testAndSetMarked(const void*);
void setMarked(const void*);
template <typename Functor> void forEach(Functor&);
FixedArray<CollectorCell, CELLS_PER_BLOCK> cells;
private:
MarkedBlock(const PageAllocationAligned&, JSGlobalData*);
WTF::Bitmap<BITS_PER_BLOCK> marked;
PageAllocationAligned m_allocation;
Heap* m_heap;
};
inline bool MarkedBlock::isCellAligned(const void* p)
{
return !((intptr_t)(p) & CELL_MASK);
}
inline MarkedBlock* MarkedBlock::blockFor(const void* p)
{
return reinterpret_cast<MarkedBlock*>(reinterpret_cast<uintptr_t>(p) & BLOCK_MASK);
}
inline Heap* MarkedBlock::heap() const
{
return m_heap;
}
inline bool MarkedBlock::isEmpty()
{
marked.clear(CELLS_PER_BLOCK - 1); // Clear the always-set last bit to avoid confusing isEmpty().
bool result = marked.isEmpty();
marked.set(CELLS_PER_BLOCK - 1);
return result;
}
inline void MarkedBlock::clearMarks()
{
// allocate() assumes that the last mark bit is always set.
marked.clearAll();
marked.set(CELLS_PER_BLOCK - 1);
}
inline size_t MarkedBlock::markCount()
{
return marked.count() - 1; // The last mark bit is always set.
}
inline size_t MarkedBlock::size()
{
return markCount() * CELL_SIZE;
}
inline size_t MarkedBlock::capacity()
{
return BLOCK_SIZE;
}
inline size_t MarkedBlock::cellNumber(const void* cell)
{
return (reinterpret_cast<uintptr_t>(cell) & BLOCK_OFFSET_MASK) / CELL_SIZE;
}
inline bool MarkedBlock::isMarked(const void* cell)
{
return marked.get(cellNumber(cell));
}
inline bool MarkedBlock::testAndSetMarked(const void* cell)
{
return marked.testAndSet(cellNumber(cell));
}
inline void MarkedBlock::setMarked(const void* cell)
{
marked.set(cellNumber(cell));
}
template <typename Functor> inline void MarkedBlock::forEach(Functor& functor)
{
for (size_t i = 0; i < CELLS_PER_BLOCK - 1; ++i) { // The last cell is a dummy place-holder.
if (!marked.get(i))
continue;
functor(reinterpret_cast<JSCell*>(&cells[i]));
}
}
} // namespace JSC
#endif // MarkedSpace_h
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