Merge WebKit at r75993: Initial merge by git.

Change-Id: I602bbdc3974787a3b0450456a30a7868286921c3

1 files changed, 367 insertions, 0 deletions

diff --git a/Source/JavaScriptCore/runtime/MarkedSpace.cpp b/Source/JavaScriptCore/runtime/MarkedSpace.cpp
new file mode 100644
index 0000000..4bc3c18
--- /dev/null
+++ b/Source/JavaScriptCore/runtime/MarkedSpace.cpp
@@ -0,0 +1,367 @@
+/*
+ *  Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
+ *  Copyright (C) 2007 Eric Seidel <eric@webkit.org>
+ *
+ *  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
+ *
+ */
+
+#include "config.h"
+#include "MarkedSpace.h"
+
+#include "CollectorHeapIterator.h"
+#include "JSCell.h"
+#include "JSGlobalData.h"
+#include "JSLock.h"
+
+using std::max;
+
+namespace JSC {
+
+class Structure;
+
+// tunable parameters
+
+const size_t GROWTH_FACTOR = 2;
+const size_t LOW_WATER_FACTOR = 4;
+const size_t ALLOCATIONS_PER_COLLECTION = 3600;
+// This value has to be a macro to be used in max() without introducing
+// a PIC branch in Mach-O binaries, see <rdar://problem/5971391>.
+#define MIN_ARRAY_SIZE (static_cast<size_t>(14))
+
+MarkedSpace::MarkedSpace(JSGlobalData* globalData)
+    : m_globalData(globalData)
+{
+    memset(&m_heap, 0, sizeof(CollectorHeap));
+    allocateBlock();
+}
+
+void MarkedSpace::destroy(ProtectCountSet& protectedValuesCopy)
+{
+    clearMarkBits();
+    ProtectCountSet::iterator protectedValuesEnd = protectedValuesCopy.end();
+    for (ProtectCountSet::iterator it = protectedValuesCopy.begin(); it != protectedValuesEnd; ++it)
+        markCell(it->first);
+
+    m_heap.nextCell = 0;
+    m_heap.nextBlock = 0;
+    DeadObjectIterator it(m_heap, m_heap.nextBlock, m_heap.nextCell);
+    DeadObjectIterator end(m_heap, m_heap.usedBlocks);
+    for ( ; it != end; ++it)
+        (*it)->~JSCell();
+
+    protectedValuesEnd = protectedValuesCopy.end();
+    for (ProtectCountSet::iterator it = protectedValuesCopy.begin(); it != protectedValuesEnd; ++it)
+        it->first->~JSCell();
+
+    for (size_t block = 0; block < m_heap.usedBlocks; ++block)
+        m_heap.blocks[block].deallocate();
+
+    fastFree(m_heap.blocks);
+
+    memset(&m_heap, 0, sizeof(CollectorHeap));
+}
+
+NEVER_INLINE CollectorBlock* MarkedSpace::allocateBlock()
+{
+    PageAllocationAligned allocation = PageAllocationAligned::allocate(BLOCK_SIZE, BLOCK_SIZE, OSAllocator::JSGCHeapPages);
+    CollectorBlock* block = static_cast<CollectorBlock*>(allocation.base());
+    if (!block)
+        CRASH();
+
+    // Initialize block.
+
+    block->heap = &globalData()->heap;
+    clearMarkBits(block);
+
+    Structure* dummyMarkableCellStructure = globalData()->dummyMarkableCellStructure.get();
+    for (size_t i = 0; i < HeapConstants::cellsPerBlock; ++i)
+        new (&block->cells[i]) JSCell(dummyMarkableCellStructure);
+    
+    // Add block to blocks vector.
+
+    size_t numBlocks = m_heap.numBlocks;
+    if (m_heap.usedBlocks == numBlocks) {
+        static const size_t maxNumBlocks = ULONG_MAX / sizeof(PageAllocationAligned) / GROWTH_FACTOR;
+        if (numBlocks > maxNumBlocks)
+            CRASH();
+        numBlocks = max(MIN_ARRAY_SIZE, numBlocks * GROWTH_FACTOR);
+        m_heap.numBlocks = numBlocks;
+        m_heap.blocks = static_cast<PageAllocationAligned*>(fastRealloc(m_heap.blocks, numBlocks * sizeof(PageAllocationAligned)));
+    }
+    m_heap.blocks[m_heap.usedBlocks++] = allocation;
+
+    return block;
+}
+
+NEVER_INLINE void MarkedSpace::freeBlock(size_t block)
+{
+    m_heap.didShrink = true;
+
+    ObjectIterator it(m_heap, block);
+    ObjectIterator end(m_heap, block + 1);
+    for ( ; it != end; ++it)
+        (*it)->~JSCell();
+    m_heap.blocks[block].deallocate();
+
+    // swap with the last block so we compact as we go
+    m_heap.blocks[block] = m_heap.blocks[m_heap.usedBlocks - 1];
+    m_heap.usedBlocks--;
+
+    if (m_heap.numBlocks > MIN_ARRAY_SIZE && m_heap.usedBlocks < m_heap.numBlocks / LOW_WATER_FACTOR) {
+        m_heap.numBlocks = m_heap.numBlocks / GROWTH_FACTOR; 
+        m_heap.blocks = static_cast<PageAllocationAligned*>(fastRealloc(m_heap.blocks, m_heap.numBlocks * sizeof(PageAllocationAligned)));
+    }
+}
+
+void* MarkedSpace::allocate(size_t s)
+{
+    ASSERT(globalData()->identifierTable == wtfThreadData().currentIdentifierTable());
+    typedef HeapConstants::Block Block;
+    typedef HeapConstants::Cell Cell;
+    
+    ASSERT(JSLock::lockCount() > 0);
+    ASSERT(JSLock::currentThreadIsHoldingLock());
+    ASSERT_UNUSED(s, s <= HeapConstants::cellSize);
+
+    // Fast case: find the next garbage cell and recycle it.
+
+    do {
+        ASSERT(m_heap.nextBlock < m_heap.usedBlocks);
+        Block* block = m_heap.collectorBlock(m_heap.nextBlock);
+        do {
+            ASSERT(m_heap.nextCell < HeapConstants::cellsPerBlock);
+            if (!block->marked.get(m_heap.nextCell)) { // Always false for the last cell in the block
+                Cell* cell = &block->cells[m_heap.nextCell];
+
+                JSCell* imp = reinterpret_cast<JSCell*>(cell);
+                imp->~JSCell();
+
+                ++m_heap.nextCell;
+                return cell;
+            }
+            block->marked.advanceToNextPossibleFreeCell(m_heap.nextCell);
+        } while (m_heap.nextCell != HeapConstants::cellsPerBlock);
+        m_heap.nextCell = 0;
+    } while (++m_heap.nextBlock != m_heap.usedBlocks);
+    
+    return 0;
+}
+
+void MarkedSpace::resizeBlocks()
+{
+    m_heap.didShrink = false;
+
+    size_t usedCellCount = markedCells();
+    size_t minCellCount = usedCellCount + max(ALLOCATIONS_PER_COLLECTION, usedCellCount);
+    size_t minBlockCount = (minCellCount + HeapConstants::cellsPerBlock - 1) / HeapConstants::cellsPerBlock;
+
+    size_t maxCellCount = 1.25f * minCellCount;
+    size_t maxBlockCount = (maxCellCount + HeapConstants::cellsPerBlock - 1) / HeapConstants::cellsPerBlock;
+
+    if (m_heap.usedBlocks < minBlockCount)
+        growBlocks(minBlockCount);
+    else if (m_heap.usedBlocks > maxBlockCount)
+        shrinkBlocks(maxBlockCount);
+}
+
+void MarkedSpace::growBlocks(size_t neededBlocks)
+{
+    ASSERT(m_heap.usedBlocks < neededBlocks);
+    while (m_heap.usedBlocks < neededBlocks)
+        allocateBlock();
+}
+
+void MarkedSpace::shrinkBlocks(size_t neededBlocks)
+{
+    ASSERT(m_heap.usedBlocks > neededBlocks);
+    
+    // Clear the always-on last bit, so isEmpty() isn't fooled by it.
+    for (size_t i = 0; i < m_heap.usedBlocks; ++i)
+        m_heap.collectorBlock(i)->marked.clear(HeapConstants::cellsPerBlock - 1);
+
+    for (size_t i = 0; i != m_heap.usedBlocks && m_heap.usedBlocks != neededBlocks; ) {
+        if (m_heap.collectorBlock(i)->marked.isEmpty()) {
+            freeBlock(i);
+        } else
+            ++i;
+    }
+
+    // Reset the always-on last bit.
+    for (size_t i = 0; i < m_heap.usedBlocks; ++i)
+        m_heap.collectorBlock(i)->marked.set(HeapConstants::cellsPerBlock - 1);
+}
+
+inline bool isPointerAligned(void* p)
+{
+    return (((intptr_t)(p) & (sizeof(char*) - 1)) == 0);
+}
+
+// Cell size needs to be a power of two for isPossibleCell to be valid.
+COMPILE_ASSERT(sizeof(CollectorCell) % 2 == 0, Collector_cell_size_is_power_of_two);
+
+static inline bool isCellAligned(void *p)
+{
+    return (((intptr_t)(p) & CELL_MASK) == 0);
+}
+
+static inline bool isPossibleCell(void* p)
+{
+    return isCellAligned(p) && p;
+}
+
+void MarkedSpace::markConservatively(MarkStack& markStack, void* start, void* end)
+{
+#if OS(WINCE)
+    if (start > end) {
+        void* tmp = start;
+        start = end;
+        end = tmp;
+    }
+#else
+    ASSERT(start <= end);
+#endif
+
+    ASSERT((static_cast<char*>(end) - static_cast<char*>(start)) < 0x1000000);
+    ASSERT(isPointerAligned(start));
+    ASSERT(isPointerAligned(end));
+
+    char** p = static_cast<char**>(start);
+    char** e = static_cast<char**>(end);
+
+    while (p != e) {
+        char* x = *p++;
+        if (isPossibleCell(x)) {
+            size_t usedBlocks;
+            uintptr_t xAsBits = reinterpret_cast<uintptr_t>(x);
+            xAsBits &= CELL_ALIGN_MASK;
+
+            uintptr_t offset = xAsBits & BLOCK_OFFSET_MASK;
+            const size_t lastCellOffset = sizeof(CollectorCell) * (CELLS_PER_BLOCK - 1);
+            if (offset > lastCellOffset)
+                continue;
+
+            CollectorBlock* blockAddr = reinterpret_cast<CollectorBlock*>(xAsBits - offset);
+            usedBlocks = m_heap.usedBlocks;
+            for (size_t block = 0; block < usedBlocks; block++) {
+                if (m_heap.collectorBlock(block) != blockAddr)
+                    continue;
+                markStack.append(reinterpret_cast<JSCell*>(xAsBits));
+            }
+        }
+    }
+}
+
+void MarkedSpace::clearMarkBits()
+{
+    for (size_t i = 0; i < m_heap.usedBlocks; ++i)
+        clearMarkBits(m_heap.collectorBlock(i));
+}
+
+void MarkedSpace::clearMarkBits(CollectorBlock* block)
+{
+    // allocate assumes that the last cell in every block is marked.
+    block->marked.clearAll();
+    block->marked.set(HeapConstants::cellsPerBlock - 1);
+}
+
+size_t MarkedSpace::markedCells(size_t startBlock, size_t startCell) const
+{
+    ASSERT(startBlock <= m_heap.usedBlocks);
+    ASSERT(startCell < HeapConstants::cellsPerBlock);
+
+    if (startBlock >= m_heap.usedBlocks)
+        return 0;
+
+    size_t result = 0;
+    result += m_heap.collectorBlock(startBlock)->marked.count(startCell);
+    for (size_t i = startBlock + 1; i < m_heap.usedBlocks; ++i)
+        result += m_heap.collectorBlock(i)->marked.count();
+
+    return result;
+}
+
+void MarkedSpace::sweep()
+{
+#if !ENABLE(JSC_ZOMBIES)
+    Structure* dummyMarkableCellStructure = globalData()->dummyMarkableCellStructure.get();
+#endif
+
+    DeadObjectIterator it(m_heap, m_heap.nextBlock, m_heap.nextCell);
+    DeadObjectIterator end(m_heap, m_heap.usedBlocks);
+    for ( ; it != end; ++it) {
+        JSCell* cell = *it;
+#if ENABLE(JSC_ZOMBIES)
+        if (!cell->isZombie()) {
+            const ClassInfo* info = cell->classInfo();
+            cell->~JSCell();
+            new (cell) JSZombie(info, JSZombie::leakedZombieStructure());
+            Heap::markCell(cell);
+        }
+#else
+        cell->~JSCell();
+        // Callers of sweep assume it's safe to mark any cell in the heap.
+        new (cell) JSCell(dummyMarkableCellStructure);
+#endif
+    }
+}
+
+size_t MarkedSpace::objectCount() const
+{
+    return m_heap.nextBlock * HeapConstants::cellsPerBlock // allocated full blocks
+           + m_heap.nextCell // allocated cells in current block
+           + markedCells(m_heap.nextBlock, m_heap.nextCell) // marked cells in remainder of m_heap
+           - m_heap.usedBlocks; // 1 cell per block is a dummy sentinel
+}
+
+void MarkedSpace::addToStatistics(Statistics& statistics) const
+{
+    statistics.size += m_heap.usedBlocks * BLOCK_SIZE;
+    statistics.free += m_heap.usedBlocks * BLOCK_SIZE - (objectCount() * HeapConstants::cellSize);
+}
+
+MarkedSpace::Statistics MarkedSpace::statistics() const
+{
+    Statistics statistics = { 0, 0 };
+    addToStatistics(statistics);
+    return statistics;
+}
+
+size_t MarkedSpace::size() const
+{
+    return m_heap.usedBlocks * BLOCK_SIZE;
+}
+
+void MarkedSpace::reset()
+{
+    m_heap.nextCell = 0;
+    m_heap.nextBlock = 0;
+#if ENABLE(JSC_ZOMBIES)
+    sweep();
+#endif
+    resizeBlocks();
+}
+
+LiveObjectIterator MarkedSpace::primaryHeapBegin()
+{
+    return LiveObjectIterator(m_heap, 0);
+}
+
+LiveObjectIterator MarkedSpace::primaryHeapEnd()
+{
+    return LiveObjectIterator(m_heap, m_heap.usedBlocks);
+}
+
+} // namespace JSC