diff -r 000000000000 -r 4f2f89ce4247 JavaScriptCore/runtime/Collector.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/JavaScriptCore/runtime/Collector.cpp	Fri Sep 17 09:02:29 2010 +0300
@@ -0,0 +1,1275 @@
+/*
+ *  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 "Collector.h"
+
+#include "ArgList.h"
+#include "CallFrame.h"
+#include "CodeBlock.h"
+#include "CollectorHeapIterator.h"
+#include "Interpreter.h"
+#include "JSArray.h"
+#include "JSGlobalObject.h"
+#include "JSLock.h"
+#include "JSONObject.h"
+#include "JSString.h"
+#include "JSValue.h"
+#include "JSZombie.h"
+#include "MarkStack.h"
+#include "Nodes.h"
+#include "Tracing.h"
+#include <algorithm>
+#include <limits.h>
+#include <setjmp.h>
+#include <stdlib.h>
+#include <wtf/FastMalloc.h>
+#include <wtf/HashCountedSet.h>
+#include <wtf/UnusedParam.h>
+#include <wtf/VMTags.h>
+
+#if OS(DARWIN)
+
+#include <mach/mach_init.h>
+#include <mach/mach_port.h>
+#include <mach/task.h>
+#include <mach/thread_act.h>
+#include <mach/vm_map.h>
+
+#elif OS(WINDOWS)
+
+#include <windows.h>
+#include <malloc.h>
+
+#elif OS(HAIKU)
+
+#include <OS.h>
+
+#elif OS(UNIX)
+
+#include <stdlib.h>
+#if !OS(HAIKU)
+#include <sys/mman.h>
+#endif
+#include <unistd.h>
+
+#if OS(SOLARIS)
+#include <thread.h>
+#else
+#include <pthread.h>
+#endif
+
+#if HAVE(PTHREAD_NP_H)
+#include <pthread_np.h>
+#endif
+
+#if OS(QNX)
+#include <fcntl.h>
+#include <sys/procfs.h>
+#include <stdio.h>
+#include <errno.h>
+#endif
+
+#endif
+
+#define COLLECT_ON_EVERY_ALLOCATION 0
+
+using std::max;
+
+namespace JSC {
+
+// 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))
+
+#if ENABLE(JSC_MULTIPLE_THREADS)
+
+#if OS(DARWIN)
+typedef mach_port_t PlatformThread;
+#elif OS(WINDOWS)
+typedef HANDLE PlatformThread;
+#endif
+
+class Heap::Thread {
+public:
+    Thread(pthread_t pthread, const PlatformThread& platThread, void* base) 
+        : posixThread(pthread)
+        , platformThread(platThread)
+        , stackBase(base)
+    {
+    }
+
+    Thread* next;
+    pthread_t posixThread;
+    PlatformThread platformThread;
+    void* stackBase;
+};
+
+#endif
+
+Heap::Heap(JSGlobalData* globalData)
+    : m_markListSet(0)
+#if ENABLE(JSC_MULTIPLE_THREADS)
+    , m_registeredThreads(0)
+    , m_currentThreadRegistrar(0)
+#endif
+#if OS(SYMBIAN)
+    , m_blockallocator(JSCCOLLECTOR_VIRTUALMEM_RESERVATION, BLOCK_SIZE)
+#endif
+    , m_globalData(globalData)
+{
+    ASSERT(globalData);
+    memset(&m_heap, 0, sizeof(CollectorHeap));
+    allocateBlock();
+}
+
+Heap::~Heap()
+{
+    // The destroy function must already have been called, so assert this.
+    ASSERT(!m_globalData);
+}
+
+void Heap::destroy()
+{
+    JSLock lock(SilenceAssertionsOnly);
+
+    if (!m_globalData)
+        return;
+
+    ASSERT(!m_globalData->dynamicGlobalObject);
+    ASSERT(!isBusy());
+    
+    // The global object is not GC protected at this point, so sweeping may delete it
+    // (and thus the global data) before other objects that may use the global data.
+    RefPtr<JSGlobalData> protect(m_globalData);
+
+    delete m_markListSet;
+    m_markListSet = 0;
+
+    freeBlocks();
+
+#if ENABLE(JSC_MULTIPLE_THREADS)
+    if (m_currentThreadRegistrar) {
+        int error = pthread_key_delete(m_currentThreadRegistrar);
+        ASSERT_UNUSED(error, !error);
+    }
+
+    MutexLocker registeredThreadsLock(m_registeredThreadsMutex);
+    for (Heap::Thread* t = m_registeredThreads; t;) {
+        Heap::Thread* next = t->next;
+        delete t;
+        t = next;
+    }
+#endif
+#if OS(SYMBIAN)
+    m_blockallocator.destroy();
+#endif
+    m_globalData = 0;
+}
+
+NEVER_INLINE CollectorBlock* Heap::allocateBlock()
+{
+#if OS(DARWIN)
+    vm_address_t address = 0;
+    vm_map(current_task(), &address, BLOCK_SIZE, BLOCK_OFFSET_MASK, VM_FLAGS_ANYWHERE | VM_TAG_FOR_COLLECTOR_MEMORY, MEMORY_OBJECT_NULL, 0, FALSE, VM_PROT_DEFAULT, VM_PROT_DEFAULT, VM_INHERIT_DEFAULT);
+#elif OS(SYMBIAN)
+    void* address = m_blockallocator.alloc();  
+    if (!address)
+        CRASH();
+#elif OS(WINCE)
+    void* address = VirtualAlloc(NULL, BLOCK_SIZE, MEM_COMMIT | MEM_RESERVE, PAGE_READWRITE);
+#elif OS(WINDOWS)
+#if COMPILER(MINGW) && !COMPILER(MINGW64)
+    void* address = __mingw_aligned_malloc(BLOCK_SIZE, BLOCK_SIZE);
+#else
+    void* address = _aligned_malloc(BLOCK_SIZE, BLOCK_SIZE);
+#endif
+    memset(address, 0, BLOCK_SIZE);
+#elif HAVE(POSIX_MEMALIGN)
+    void* address;
+    posix_memalign(&address, BLOCK_SIZE, BLOCK_SIZE);
+#else
+
+#if ENABLE(JSC_MULTIPLE_THREADS)
+#error Need to initialize pagesize safely.
+#endif
+    static size_t pagesize = getpagesize();
+
+    size_t extra = 0;
+    if (BLOCK_SIZE > pagesize)
+        extra = BLOCK_SIZE - pagesize;
+
+    void* mmapResult = mmap(NULL, BLOCK_SIZE + extra, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON, -1, 0);
+    uintptr_t address = reinterpret_cast<uintptr_t>(mmapResult);
+
+    size_t adjust = 0;
+    if ((address & BLOCK_OFFSET_MASK) != 0)
+        adjust = BLOCK_SIZE - (address & BLOCK_OFFSET_MASK);
+
+    if (adjust > 0)
+        munmap(reinterpret_cast<char*>(address), adjust);
+
+    if (adjust < extra)
+        munmap(reinterpret_cast<char*>(address + adjust + BLOCK_SIZE), extra - adjust);
+
+    address += adjust;
+#endif
+
+    // Initialize block.
+
+    CollectorBlock* block = reinterpret_cast<CollectorBlock*>(address);
+    block->heap = this;
+    clearMarkBits(block);
+
+    Structure* dummyMarkableCellStructure = m_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(CollectorBlock*) / GROWTH_FACTOR;
+        if (numBlocks > maxNumBlocks)
+            CRASH();
+        numBlocks = max(MIN_ARRAY_SIZE, numBlocks * GROWTH_FACTOR);
+        m_heap.numBlocks = numBlocks;
+        m_heap.blocks = static_cast<CollectorBlock**>(fastRealloc(m_heap.blocks, numBlocks * sizeof(CollectorBlock*)));
+    }
+    m_heap.blocks[m_heap.usedBlocks++] = block;
+
+    return block;
+}
+
+NEVER_INLINE void Heap::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();
+    freeBlockPtr(m_heap.blocks[block]);
+
+    // 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<CollectorBlock**>(fastRealloc(m_heap.blocks, m_heap.numBlocks * sizeof(CollectorBlock*)));
+    }
+}
+
+NEVER_INLINE void Heap::freeBlockPtr(CollectorBlock* block)
+{
+#if OS(DARWIN)    
+    vm_deallocate(current_task(), reinterpret_cast<vm_address_t>(block), BLOCK_SIZE);
+#elif OS(SYMBIAN)
+    m_blockallocator.free(reinterpret_cast<void*>(block));
+#elif OS(WINCE)
+    VirtualFree(block, 0, MEM_RELEASE);
+#elif OS(WINDOWS)
+#if COMPILER(MINGW) && !COMPILER(MINGW64)
+    __mingw_aligned_free(block);
+#else
+    _aligned_free(block);
+#endif
+#elif HAVE(POSIX_MEMALIGN)
+    free(block);
+#else
+    munmap(reinterpret_cast<char*>(block), BLOCK_SIZE);
+#endif
+}
+
+void Heap::freeBlocks()
+{
+    ProtectCountSet protectedValuesCopy = m_protectedValues;
+
+    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();
+
+    ASSERT(!protectedObjectCount());
+
+    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)
+        freeBlockPtr(m_heap.blocks[block]);
+
+    fastFree(m_heap.blocks);
+
+    memset(&m_heap, 0, sizeof(CollectorHeap));
+}
+
+void Heap::recordExtraCost(size_t cost)
+{
+    // Our frequency of garbage collection tries to balance memory use against speed
+    // by collecting based on the number of newly created values. However, for values
+    // that hold on to a great deal of memory that's not in the form of other JS values,
+    // that is not good enough - in some cases a lot of those objects can pile up and
+    // use crazy amounts of memory without a GC happening. So we track these extra
+    // memory costs. Only unusually large objects are noted, and we only keep track
+    // of this extra cost until the next GC. In garbage collected languages, most values
+    // are either very short lived temporaries, or have extremely long lifetimes. So
+    // if a large value survives one garbage collection, there is not much point to
+    // collecting more frequently as long as it stays alive.
+
+    if (m_heap.extraCost > maxExtraCost && m_heap.extraCost > m_heap.usedBlocks * BLOCK_SIZE / 2) {
+        // If the last iteration through the heap deallocated blocks, we need
+        // to clean up remaining garbage before marking. Otherwise, the conservative
+        // marking mechanism might follow a pointer to unmapped memory.
+        if (m_heap.didShrink)
+            sweep();
+        reset();
+    }
+    m_heap.extraCost += cost;
+}
+
+void* Heap::allocate(size_t s)
+{
+    typedef HeapConstants::Block Block;
+    typedef HeapConstants::Cell Cell;
+    
+    ASSERT(JSLock::lockCount() > 0);
+    ASSERT(JSLock::currentThreadIsHoldingLock());
+    ASSERT_UNUSED(s, s <= HeapConstants::cellSize);
+
+    ASSERT(m_heap.operationInProgress == NoOperation);
+
+#if COLLECT_ON_EVERY_ALLOCATION
+    collectAllGarbage();
+    ASSERT(m_heap.operationInProgress == NoOperation);
+#endif
+
+allocate:
+
+    // Fast case: find the next garbage cell and recycle it.
+
+    do {
+        ASSERT(m_heap.nextBlock < m_heap.usedBlocks);
+        Block* block = reinterpret_cast<Block*>(m_heap.blocks[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];
+
+                m_heap.operationInProgress = Allocation;
+                JSCell* imp = reinterpret_cast<JSCell*>(cell);
+                imp->~JSCell();
+                m_heap.operationInProgress = NoOperation;
+
+                ++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);
+
+    // Slow case: reached the end of the heap. Mark live objects and start over.
+
+    reset();
+    goto allocate;
+}
+
+void Heap::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 Heap::growBlocks(size_t neededBlocks)
+{
+    ASSERT(m_heap.usedBlocks < neededBlocks);
+    while (m_heap.usedBlocks < neededBlocks)
+        allocateBlock();
+}
+
+void Heap::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.blocks[i]->marked.clear(HeapConstants::cellsPerBlock - 1);
+
+    for (size_t i = 0; i != m_heap.usedBlocks && m_heap.usedBlocks != neededBlocks; ) {
+        if (m_heap.blocks[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.blocks[i]->marked.set(HeapConstants::cellsPerBlock - 1);
+}
+
+#if OS(WINCE)
+JS_EXPORTDATA void* g_stackBase = 0;
+
+inline bool isPageWritable(void* page)
+{
+    MEMORY_BASIC_INFORMATION memoryInformation;
+    DWORD result = VirtualQuery(page, &memoryInformation, sizeof(memoryInformation));
+
+    // return false on error, including ptr outside memory
+    if (result != sizeof(memoryInformation))
+        return false;
+
+    DWORD protect = memoryInformation.Protect & ~(PAGE_GUARD | PAGE_NOCACHE);
+    return protect == PAGE_READWRITE
+        || protect == PAGE_WRITECOPY
+        || protect == PAGE_EXECUTE_READWRITE
+        || protect == PAGE_EXECUTE_WRITECOPY;
+}
+
+static void* getStackBase(void* previousFrame)
+{
+    // find the address of this stack frame by taking the address of a local variable
+    bool isGrowingDownward;
+    void* thisFrame = (void*)(&isGrowingDownward);
+
+    isGrowingDownward = previousFrame < &thisFrame;
+    static DWORD pageSize = 0;
+    if (!pageSize) {
+        SYSTEM_INFO systemInfo;
+        GetSystemInfo(&systemInfo);
+        pageSize = systemInfo.dwPageSize;
+    }
+
+    // scan all of memory starting from this frame, and return the last writeable page found
+    register char* currentPage = (char*)((DWORD)thisFrame & ~(pageSize - 1));
+    if (isGrowingDownward) {
+        while (currentPage > 0) {
+            // check for underflow
+            if (currentPage >= (char*)pageSize)
+                currentPage -= pageSize;
+            else
+                currentPage = 0;
+            if (!isPageWritable(currentPage))
+                return currentPage + pageSize;
+        }
+        return 0;
+    } else {
+        while (true) {
+            // guaranteed to complete because isPageWritable returns false at end of memory
+            currentPage += pageSize;
+            if (!isPageWritable(currentPage))
+                return currentPage;
+        }
+    }
+}
+#endif
+
+#if OS(QNX)
+static inline void *currentThreadStackBaseQNX()
+{
+    static void* stackBase = 0;
+    static size_t stackSize = 0;
+    static pthread_t stackThread;
+    pthread_t thread = pthread_self();
+    if (stackBase == 0 || thread != stackThread) {
+        struct _debug_thread_info threadInfo;
+        memset(&threadInfo, 0, sizeof(threadInfo));
+        threadInfo.tid = pthread_self();
+        int fd = open("/proc/self", O_RDONLY);
+        if (fd == -1) {
+            LOG_ERROR("Unable to open /proc/self (errno: %d)", errno);
+            return 0;
+        }
+        devctl(fd, DCMD_PROC_TIDSTATUS, &threadInfo, sizeof(threadInfo), 0);
+        close(fd);
+        stackBase = reinterpret_cast<void*>(threadInfo.stkbase);
+        stackSize = threadInfo.stksize;
+        ASSERT(stackBase);
+        stackThread = thread;
+    }
+    return static_cast<char*>(stackBase) + stackSize;
+}
+#endif
+
+static inline void* currentThreadStackBase()
+{
+#if OS(DARWIN)
+    pthread_t thread = pthread_self();
+    return pthread_get_stackaddr_np(thread);
+#elif OS(WINDOWS) && CPU(X86) && COMPILER(MSVC)
+    // offset 0x18 from the FS segment register gives a pointer to
+    // the thread information block for the current thread
+    NT_TIB* pTib;
+    __asm {
+        MOV EAX, FS:[18h]
+        MOV pTib, EAX
+    }
+    return static_cast<void*>(pTib->StackBase);
+#elif OS(WINDOWS) && CPU(X86) && COMPILER(GCC)
+    // offset 0x18 from the FS segment register gives a pointer to
+    // the thread information block for the current thread
+    NT_TIB* pTib;
+    asm ( "movl %%fs:0x18, %0\n"
+          : "=r" (pTib)
+        );
+    return static_cast<void*>(pTib->StackBase);
+#elif OS(WINDOWS) && CPU(X86_64)
+    PNT_TIB64 pTib = reinterpret_cast<PNT_TIB64>(NtCurrentTeb());
+    return reinterpret_cast<void*>(pTib->StackBase);
+#elif OS(QNX)
+    AtomicallyInitializedStatic(Mutex&, mutex = *new Mutex);
+    MutexLocker locker(mutex);
+    return currentThreadStackBaseQNX();
+#elif OS(SOLARIS)
+    stack_t s;
+    thr_stksegment(&s);
+    return s.ss_sp;
+#elif OS(OPENBSD)
+    pthread_t thread = pthread_self();
+    stack_t stack;
+    pthread_stackseg_np(thread, &stack);
+    return stack.ss_sp;
+#elif OS(SYMBIAN)
+    TThreadStackInfo info;
+    RThread thread;
+    thread.StackInfo(info);
+    return (void*)info.iBase;
+#elif OS(HAIKU)
+    thread_info threadInfo;
+    get_thread_info(find_thread(NULL), &threadInfo);
+    return threadInfo.stack_end;
+#elif OS(UNIX)
+    AtomicallyInitializedStatic(Mutex&, mutex = *new Mutex);
+    MutexLocker locker(mutex);
+    static void* stackBase = 0;
+    static size_t stackSize = 0;
+    static pthread_t stackThread;
+    pthread_t thread = pthread_self();
+    if (stackBase == 0 || thread != stackThread) {
+        pthread_attr_t sattr;
+        pthread_attr_init(&sattr);
+#if HAVE(PTHREAD_NP_H) || OS(NETBSD)
+        // e.g. on FreeBSD 5.4, neundorf@kde.org
+        pthread_attr_get_np(thread, &sattr);
+#else
+        // FIXME: this function is non-portable; other POSIX systems may have different np alternatives
+        pthread_getattr_np(thread, &sattr);
+#endif
+        int rc = pthread_attr_getstack(&sattr, &stackBase, &stackSize);
+        (void)rc; // FIXME: Deal with error code somehow? Seems fatal.
+        ASSERT(stackBase);
+        pthread_attr_destroy(&sattr);
+        stackThread = thread;
+    }
+    return static_cast<char*>(stackBase) + stackSize;
+#elif OS(WINCE)
+    AtomicallyInitializedStatic(Mutex&, mutex = *new Mutex);
+    MutexLocker locker(mutex);
+    if (g_stackBase)
+        return g_stackBase;
+    else {
+        int dummy;
+        return getStackBase(&dummy);
+    }
+#else
+#error Need a way to get the stack base on this platform
+#endif
+}
+
+#if ENABLE(JSC_MULTIPLE_THREADS)
+
+static inline PlatformThread getCurrentPlatformThread()
+{
+#if OS(DARWIN)
+    return pthread_mach_thread_np(pthread_self());
+#elif OS(WINDOWS)
+    return pthread_getw32threadhandle_np(pthread_self());
+#endif
+}
+
+void Heap::makeUsableFromMultipleThreads()
+{
+    if (m_currentThreadRegistrar)
+        return;
+
+    int error = pthread_key_create(&m_currentThreadRegistrar, unregisterThread);
+    if (error)
+        CRASH();
+}
+
+void Heap::registerThread()
+{
+    ASSERT(!m_globalData->exclusiveThread || m_globalData->exclusiveThread == currentThread());
+
+    if (!m_currentThreadRegistrar || pthread_getspecific(m_currentThreadRegistrar))
+        return;
+
+    pthread_setspecific(m_currentThreadRegistrar, this);
+    Heap::Thread* thread = new Heap::Thread(pthread_self(), getCurrentPlatformThread(), currentThreadStackBase());
+
+    MutexLocker lock(m_registeredThreadsMutex);
+
+    thread->next = m_registeredThreads;
+    m_registeredThreads = thread;
+}
+
+void Heap::unregisterThread(void* p)
+{
+    if (p)
+        static_cast<Heap*>(p)->unregisterThread();
+}
+
+void Heap::unregisterThread()
+{
+    pthread_t currentPosixThread = pthread_self();
+
+    MutexLocker lock(m_registeredThreadsMutex);
+
+    if (pthread_equal(currentPosixThread, m_registeredThreads->posixThread)) {
+        Thread* t = m_registeredThreads;
+        m_registeredThreads = m_registeredThreads->next;
+        delete t;
+    } else {
+        Heap::Thread* last = m_registeredThreads;
+        Heap::Thread* t;
+        for (t = m_registeredThreads->next; t; t = t->next) {
+            if (pthread_equal(t->posixThread, currentPosixThread)) {
+                last->next = t->next;
+                break;
+            }
+            last = t;
+        }
+        ASSERT(t); // If t is NULL, we never found ourselves in the list.
+        delete t;
+    }
+}
+
+#else // ENABLE(JSC_MULTIPLE_THREADS)
+
+void Heap::registerThread()
+{
+}
+
+#endif
+
+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);
+
+#if USE(JSVALUE32)
+static bool isHalfCellAligned(void *p)
+{
+    return (((intptr_t)(p) & (CELL_MASK >> 1)) == 0);
+}
+
+static inline bool isPossibleCell(void* p)
+{
+    return isHalfCellAligned(p) && p;
+}
+
+#else
+
+static inline bool isCellAligned(void *p)
+{
+    return (((intptr_t)(p) & CELL_MASK) == 0);
+}
+
+static inline bool isPossibleCell(void* p)
+{
+    return isCellAligned(p) && p;
+}
+#endif // USE(JSVALUE32)
+
+void Heap::markConservatively(MarkStack& markStack, void* start, void* end)
+{
+    if (start > end) {
+        void* tmp = start;
+        start = end;
+        end = tmp;
+    }
+
+    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);
+
+    CollectorBlock** blocks = m_heap.blocks;
+    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 (blocks[block] != blockAddr)
+                    continue;
+                markStack.append(reinterpret_cast<JSCell*>(xAsBits));
+                markStack.drain();
+            }
+        }
+    }
+}
+
+void NEVER_INLINE Heap::markCurrentThreadConservativelyInternal(MarkStack& markStack)
+{
+    void* dummy;
+    void* stackPointer = &dummy;
+    void* stackBase = currentThreadStackBase();
+    markConservatively(markStack, stackPointer, stackBase);
+}
+
+#if COMPILER(GCC)
+#define REGISTER_BUFFER_ALIGNMENT __attribute__ ((aligned (sizeof(void*))))
+#else
+#define REGISTER_BUFFER_ALIGNMENT
+#endif
+
+void Heap::markCurrentThreadConservatively(MarkStack& markStack)
+{
+    // setjmp forces volatile registers onto the stack
+    jmp_buf registers REGISTER_BUFFER_ALIGNMENT;
+#if COMPILER(MSVC)
+#pragma warning(push)
+#pragma warning(disable: 4611)
+#endif
+    setjmp(registers);
+#if COMPILER(MSVC)
+#pragma warning(pop)
+#endif
+
+    markCurrentThreadConservativelyInternal(markStack);
+}
+
+#if ENABLE(JSC_MULTIPLE_THREADS)
+
+static inline void suspendThread(const PlatformThread& platformThread)
+{
+#if OS(DARWIN)
+    thread_suspend(platformThread);
+#elif OS(WINDOWS)
+    SuspendThread(platformThread);
+#else
+#error Need a way to suspend threads on this platform
+#endif
+}
+
+static inline void resumeThread(const PlatformThread& platformThread)
+{
+#if OS(DARWIN)
+    thread_resume(platformThread);
+#elif OS(WINDOWS)
+    ResumeThread(platformThread);
+#else
+#error Need a way to resume threads on this platform
+#endif
+}
+
+typedef unsigned long usword_t; // word size, assumed to be either 32 or 64 bit
+
+#if OS(DARWIN)
+
+#if CPU(X86)
+typedef i386_thread_state_t PlatformThreadRegisters;
+#elif CPU(X86_64)
+typedef x86_thread_state64_t PlatformThreadRegisters;
+#elif CPU(PPC)
+typedef ppc_thread_state_t PlatformThreadRegisters;
+#elif CPU(PPC64)
+typedef ppc_thread_state64_t PlatformThreadRegisters;
+#elif CPU(ARM)
+typedef arm_thread_state_t PlatformThreadRegisters;
+#else
+#error Unknown Architecture
+#endif
+
+#elif OS(WINDOWS) && CPU(X86)
+typedef CONTEXT PlatformThreadRegisters;
+#else
+#error Need a thread register struct for this platform
+#endif
+
+static size_t getPlatformThreadRegisters(const PlatformThread& platformThread, PlatformThreadRegisters& regs)
+{
+#if OS(DARWIN)
+
+#if CPU(X86)
+    unsigned user_count = sizeof(regs)/sizeof(int);
+    thread_state_flavor_t flavor = i386_THREAD_STATE;
+#elif CPU(X86_64)
+    unsigned user_count = x86_THREAD_STATE64_COUNT;
+    thread_state_flavor_t flavor = x86_THREAD_STATE64;
+#elif CPU(PPC) 
+    unsigned user_count = PPC_THREAD_STATE_COUNT;
+    thread_state_flavor_t flavor = PPC_THREAD_STATE;
+#elif CPU(PPC64)
+    unsigned user_count = PPC_THREAD_STATE64_COUNT;
+    thread_state_flavor_t flavor = PPC_THREAD_STATE64;
+#elif CPU(ARM)
+    unsigned user_count = ARM_THREAD_STATE_COUNT;
+    thread_state_flavor_t flavor = ARM_THREAD_STATE;
+#else
+#error Unknown Architecture
+#endif
+
+    kern_return_t result = thread_get_state(platformThread, flavor, (thread_state_t)&regs, &user_count);
+    if (result != KERN_SUCCESS) {
+        WTFReportFatalError(__FILE__, __LINE__, WTF_PRETTY_FUNCTION, 
+                            "JavaScript garbage collection failed because thread_get_state returned an error (%d). This is probably the result of running inside Rosetta, which is not supported.", result);
+        CRASH();
+    }
+    return user_count * sizeof(usword_t);
+// end OS(DARWIN)
+
+#elif OS(WINDOWS) && CPU(X86)
+    regs.ContextFlags = CONTEXT_INTEGER | CONTEXT_CONTROL | CONTEXT_SEGMENTS;
+    GetThreadContext(platformThread, &regs);
+    return sizeof(CONTEXT);
+#else
+#error Need a way to get thread registers on this platform
+#endif
+}
+
+static inline void* otherThreadStackPointer(const PlatformThreadRegisters& regs)
+{
+#if OS(DARWIN)
+
+#if __DARWIN_UNIX03
+
+#if CPU(X86)
+    return reinterpret_cast<void*>(regs.__esp);
+#elif CPU(X86_64)
+    return reinterpret_cast<void*>(regs.__rsp);
+#elif CPU(PPC) || CPU(PPC64)
+    return reinterpret_cast<void*>(regs.__r1);
+#elif CPU(ARM)
+    return reinterpret_cast<void*>(regs.__sp);
+#else
+#error Unknown Architecture
+#endif
+
+#else // !__DARWIN_UNIX03
+
+#if CPU(X86)
+    return reinterpret_cast<void*>(regs.esp);
+#elif CPU(X86_64)
+    return reinterpret_cast<void*>(regs.rsp);
+#elif CPU(PPC) || CPU(PPC64)
+    return reinterpret_cast<void*>(regs.r1);
+#else
+#error Unknown Architecture
+#endif
+
+#endif // __DARWIN_UNIX03
+
+// end OS(DARWIN)
+#elif CPU(X86) && OS(WINDOWS)
+    return reinterpret_cast<void*>((uintptr_t) regs.Esp);
+#else
+#error Need a way to get the stack pointer for another thread on this platform
+#endif
+}
+
+void Heap::markOtherThreadConservatively(MarkStack& markStack, Thread* thread)
+{
+    suspendThread(thread->platformThread);
+
+    PlatformThreadRegisters regs;
+    size_t regSize = getPlatformThreadRegisters(thread->platformThread, regs);
+
+    // mark the thread's registers
+    markConservatively(markStack, static_cast<void*>(&regs), static_cast<void*>(reinterpret_cast<char*>(&regs) + regSize));
+
+    void* stackPointer = otherThreadStackPointer(regs);
+    markConservatively(markStack, stackPointer, thread->stackBase);
+
+    resumeThread(thread->platformThread);
+}
+
+#endif
+
+void Heap::markStackObjectsConservatively(MarkStack& markStack)
+{
+    markCurrentThreadConservatively(markStack);
+
+#if ENABLE(JSC_MULTIPLE_THREADS)
+
+    if (m_currentThreadRegistrar) {
+
+        MutexLocker lock(m_registeredThreadsMutex);
+
+#ifndef NDEBUG
+        // Forbid malloc during the mark phase. Marking a thread suspends it, so 
+        // a malloc inside markChildren() would risk a deadlock with a thread that had been 
+        // suspended while holding the malloc lock.
+        fastMallocForbid();
+#endif
+        // It is safe to access the registeredThreads list, because we earlier asserted that locks are being held,
+        // and since this is a shared heap, they are real locks.
+        for (Thread* thread = m_registeredThreads; thread; thread = thread->next) {
+            if (!pthread_equal(thread->posixThread, pthread_self()))
+                markOtherThreadConservatively(markStack, thread);
+        }
+#ifndef NDEBUG
+        fastMallocAllow();
+#endif
+    }
+#endif
+}
+
+void Heap::protect(JSValue k)
+{
+    ASSERT(k);
+    ASSERT(JSLock::currentThreadIsHoldingLock() || !m_globalData->isSharedInstance());
+
+    if (!k.isCell())
+        return;
+
+    m_protectedValues.add(k.asCell());
+}
+
+bool Heap::unprotect(JSValue k)
+{
+    ASSERT(k);
+    ASSERT(JSLock::currentThreadIsHoldingLock() || !m_globalData->isSharedInstance());
+
+    if (!k.isCell())
+        return false;
+
+    return m_protectedValues.remove(k.asCell());
+}
+
+void Heap::markProtectedObjects(MarkStack& markStack)
+{
+    ProtectCountSet::iterator end = m_protectedValues.end();
+    for (ProtectCountSet::iterator it = m_protectedValues.begin(); it != end; ++it) {
+        markStack.append(it->first);
+        markStack.drain();
+    }
+}
+
+void Heap::clearMarkBits()
+{
+    for (size_t i = 0; i < m_heap.usedBlocks; ++i)
+        clearMarkBits(m_heap.blocks[i]);
+}
+
+void Heap::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 Heap::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.blocks[startBlock]->marked.count(startCell);
+    for (size_t i = startBlock + 1; i < m_heap.usedBlocks; ++i)
+        result += m_heap.blocks[i]->marked.count();
+
+    return result;
+}
+
+void Heap::sweep()
+{
+    ASSERT(m_heap.operationInProgress == NoOperation);
+    if (m_heap.operationInProgress != NoOperation)
+        CRASH();
+    m_heap.operationInProgress = Collection;
+    
+#if !ENABLE(JSC_ZOMBIES)
+    Structure* dummyMarkableCellStructure = m_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
+    }
+
+    m_heap.operationInProgress = NoOperation;
+}
+
+void Heap::markRoots()
+{
+#ifndef NDEBUG
+    if (m_globalData->isSharedInstance()) {
+        ASSERT(JSLock::lockCount() > 0);
+        ASSERT(JSLock::currentThreadIsHoldingLock());
+    }
+#endif
+
+    ASSERT(m_heap.operationInProgress == NoOperation);
+    if (m_heap.operationInProgress != NoOperation)
+        CRASH();
+
+    m_heap.operationInProgress = Collection;
+
+    MarkStack& markStack = m_globalData->markStack;
+
+    // Reset mark bits.
+    clearMarkBits();
+
+    // Mark stack roots.
+    markStackObjectsConservatively(markStack);
+    m_globalData->interpreter->registerFile().markCallFrames(markStack, this);
+
+    // Mark explicitly registered roots.
+    markProtectedObjects(markStack);
+
+    // Mark misc. other roots.
+    if (m_markListSet && m_markListSet->size())
+        MarkedArgumentBuffer::markLists(markStack, *m_markListSet);
+    if (m_globalData->exception)
+        markStack.append(m_globalData->exception);
+    if (m_globalData->functionCodeBlockBeingReparsed)
+        m_globalData->functionCodeBlockBeingReparsed->markAggregate(markStack);
+    if (m_globalData->firstStringifierToMark)
+        JSONObject::markStringifiers(markStack, m_globalData->firstStringifierToMark);
+
+    // Mark the small strings cache last, since it will clear itself if nothing
+    // else has marked it.
+    m_globalData->smallStrings.markChildren(markStack);
+
+    markStack.drain();
+    markStack.compact();
+
+    m_heap.operationInProgress = NoOperation;
+}
+
+size_t Heap::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 Heap::addToStatistics(Heap::Statistics& statistics) const
+{
+    statistics.size += m_heap.usedBlocks * BLOCK_SIZE;
+    statistics.free += m_heap.usedBlocks * BLOCK_SIZE - (objectCount() * HeapConstants::cellSize);
+}
+
+Heap::Statistics Heap::statistics() const
+{
+    Statistics statistics = { 0, 0 };
+    addToStatistics(statistics);
+    return statistics;
+}
+
+size_t Heap::size() const
+{
+    return m_heap.usedBlocks * BLOCK_SIZE;
+}
+
+size_t Heap::globalObjectCount()
+{
+    size_t count = 0;
+    if (JSGlobalObject* head = m_globalData->head) {
+        JSGlobalObject* o = head;
+        do {
+            ++count;
+            o = o->next();
+        } while (o != head);
+    }
+    return count;
+}
+
+size_t Heap::protectedGlobalObjectCount()
+{
+    size_t count = 0;
+    if (JSGlobalObject* head = m_globalData->head) {
+        JSGlobalObject* o = head;
+        do {
+            if (m_protectedValues.contains(o))
+                ++count;
+            o = o->next();
+        } while (o != head);
+    }
+
+    return count;
+}
+
+size_t Heap::protectedObjectCount()
+{
+    return m_protectedValues.size();
+}
+
+static const char* typeName(JSCell* cell)
+{
+    if (cell->isString())
+        return "string";
+#if USE(JSVALUE32)
+    if (cell->isNumber())
+        return "number";
+#endif
+    if (cell->isGetterSetter())
+        return "Getter-Setter";
+    if (cell->isAPIValueWrapper())
+        return "API wrapper";
+    if (cell->isPropertyNameIterator())
+        return "For-in iterator";
+    if (!cell->isObject())
+        return "[empty cell]";
+    const ClassInfo* info = cell->classInfo();
+    return info ? info->className : "Object";
+}
+
+HashCountedSet<const char*>* Heap::protectedObjectTypeCounts()
+{
+    HashCountedSet<const char*>* counts = new HashCountedSet<const char*>;
+
+    ProtectCountSet::iterator end = m_protectedValues.end();
+    for (ProtectCountSet::iterator it = m_protectedValues.begin(); it != end; ++it)
+        counts->add(typeName(it->first));
+
+    return counts;
+}
+
+HashCountedSet<const char*>* Heap::objectTypeCounts()
+{
+    HashCountedSet<const char*>* counts = new HashCountedSet<const char*>;
+
+    LiveObjectIterator it = primaryHeapBegin();
+    LiveObjectIterator heapEnd = primaryHeapEnd();
+    for ( ; it != heapEnd; ++it)
+        counts->add(typeName(*it));
+
+    return counts;
+}
+
+bool Heap::isBusy()
+{
+    return m_heap.operationInProgress != NoOperation;
+}
+
+void Heap::reset()
+{
+    JAVASCRIPTCORE_GC_BEGIN();
+
+    markRoots();
+
+    JAVASCRIPTCORE_GC_MARKED();
+
+    m_heap.nextCell = 0;
+    m_heap.nextBlock = 0;
+    m_heap.nextNumber = 0;
+    m_heap.extraCost = 0;
+#if ENABLE(JSC_ZOMBIES)
+    sweep();
+#endif
+    resizeBlocks();
+
+    JAVASCRIPTCORE_GC_END();
+}
+
+void Heap::collectAllGarbage()
+{
+    JAVASCRIPTCORE_GC_BEGIN();
+
+    // If the last iteration through the heap deallocated blocks, we need
+    // to clean up remaining garbage before marking. Otherwise, the conservative
+    // marking mechanism might follow a pointer to unmapped memory.
+    if (m_heap.didShrink)
+        sweep();
+
+    markRoots();
+
+    JAVASCRIPTCORE_GC_MARKED();
+
+    m_heap.nextCell = 0;
+    m_heap.nextBlock = 0;
+    m_heap.nextNumber = 0;
+    m_heap.extraCost = 0;
+    sweep();
+    resizeBlocks();
+
+    JAVASCRIPTCORE_GC_END();
+}
+
+LiveObjectIterator Heap::primaryHeapBegin()
+{
+    return LiveObjectIterator(m_heap, 0);
+}
+
+LiveObjectIterator Heap::primaryHeapEnd()
+{
+    return LiveObjectIterator(m_heap, m_heap.usedBlocks);
+}
+
+} // namespace JSC