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diff --git a/Source/JavaScriptCore/heap/GCSegmentedArray.h b/Source/JavaScriptCore/heap/GCSegmentedArray.h
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+++ b/Source/JavaScriptCore/heap/GCSegmentedArray.h
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+/*
+ * Copyright (C) 2014 Apple Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
+ * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
+ * THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef GCSegmentedArray_h
+#define GCSegmentedArray_h
+
+#include <wtf/DoublyLinkedList.h>
+#include <wtf/Vector.h>
+
+namespace JSC {
+
+template <typename T>
+class GCArraySegment : public DoublyLinkedListNode<GCArraySegment<T>> {
+    friend class WTF::DoublyLinkedListNode<GCArraySegment<T>>;
+public:
+    GCArraySegment()
+        : DoublyLinkedListNode<GCArraySegment<T>>()
+#if !ASSERT_DISABLED
+        , m_top(0)
+#endif
+    {
+    }
+
+    static GCArraySegment* create();
+    static void destroy(GCArraySegment*);
+
+    T* data()
+    {
+        return bitwise_cast<T*>(this + 1);
+    }
+
+    static const size_t blockSize = 4 * KB;
+
+    GCArraySegment* m_prev;
+    GCArraySegment* m_next;
+#if !ASSERT_DISABLED
+    size_t m_top;
+#endif
+};
+
+template <typename T> class GCSegmentedArrayIterator;
+
+template <typename T>
+class GCSegmentedArray {
+    friend class GCSegmentedArrayIterator<T>;
+    friend class GCSegmentedArrayIterator<const T>;
+public:
+    GCSegmentedArray();
+    ~GCSegmentedArray();
+
+    void append(T);
+
+    bool canRemoveLast();
+    const T removeLast();
+    bool refill();
+    
+    size_t size();
+    bool isEmpty();
+
+    void fillVector(Vector<T>&);
+    void clear();
+
+    typedef GCSegmentedArrayIterator<T> iterator;
+    iterator begin() const { return GCSegmentedArrayIterator<T>(m_segments.head(), m_top); }
+    iterator end() const { return GCSegmentedArrayIterator<T>(); }
+
+protected:
+    template <size_t size> struct CapacityFromSize {
+        static const size_t value = (size - sizeof(GCArraySegment<T>)) / sizeof(T);
+    };
+
+    void expand();
+    
+    size_t postIncTop();
+    size_t preDecTop();
+    void setTopForFullSegment();
+    void setTopForEmptySegment();
+    size_t top();
+    
+    void validatePrevious();
+
+    DoublyLinkedList<GCArraySegment<T>> m_segments;
+
+    JS_EXPORT_PRIVATE static const size_t s_segmentCapacity = CapacityFromSize<GCArraySegment<T>::blockSize>::value;
+    size_t m_top;
+    size_t m_numberOfSegments;
+};
+
+template <typename T>
+class GCSegmentedArrayIterator {
+    friend class GCSegmentedArray<T>;
+public:
+    GCSegmentedArrayIterator()
+        : m_currentSegment(0)
+        , m_currentOffset(0)
+    {
+    }
+
+    T& get() { return m_currentSegment->data()[m_currentOffset]; }
+    T& operator*() { return get(); }
+    T& operator->() { return get(); }
+
+    bool operator==(const GCSegmentedArrayIterator& other)
+    {
+        return m_currentSegment == other.m_currentSegment && m_currentOffset == other.m_currentOffset;
+    }
+
+    bool operator!=(const GCSegmentedArrayIterator& other)
+    {
+        return !(*this == other);
+    }
+
+    GCSegmentedArrayIterator& operator++()
+    {
+        ASSERT(m_currentSegment);
+
+        m_currentOffset++;
+
+        if (m_currentOffset >= m_offsetLimit) {
+            m_currentSegment = m_currentSegment->next();
+            m_currentOffset = 0;
+            m_offsetLimit = GCSegmentedArray<T>::s_segmentCapacity;
+        }
+
+        return *this;
+    }
+
+private:
+    GCSegmentedArrayIterator(GCArraySegment<T>* start, size_t top)
+        : m_currentSegment(start)
+        , m_currentOffset(0)
+        , m_offsetLimit(top)
+    {
+        if (!m_offsetLimit)
+            m_currentSegment = nullptr;
+    }
+
+    GCArraySegment<T>* m_currentSegment;
+    size_t m_currentOffset;
+    size_t m_offsetLimit;
+};
+
+} // namespace JSC
+
+#endif // GCSegmentedArray_h