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diff --git a/Source/JavaScriptCore/b3/B3HeapRange.h b/Source/JavaScriptCore/b3/B3HeapRange.h
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+++ b/Source/JavaScriptCore/b3/B3HeapRange.h
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+/*
+ * Copyright (C) 2015 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. ``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
+ * 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. 
+ */
+
+#pragma once
+
+#if ENABLE(B3_JIT)
+
+#include <limits.h>
+#include <wtf/MathExtras.h>
+#include <wtf/PrintStream.h>
+
+namespace JSC { namespace B3 {
+
+// Alias analysis in B3 is done by checking if two integer ranges overlap. This is powerful enough
+// to be used for TBAA-style alias analysis used by the DFG, FTL, and LLVM: you just turn each node
+// in the tree of abstract heaps into a pre/post range.
+//
+// Note that the 'begin' is inclusive, while the 'end' is exclusive. These two ranges are non-
+// overlapping:
+//
+//     rangeA = 0...8
+//     rangeB = 8...16
+
+class HeapRange {
+public:
+    typedef unsigned Type;
+    
+    HeapRange()
+        : m_begin(0)
+        , m_end(0)
+    {
+    }
+
+    explicit HeapRange(unsigned value)
+        : m_begin(value)
+        , m_end(value + 1)
+    {
+        ASSERT(m_end >= m_begin);
+    }
+
+    HeapRange(unsigned begin, unsigned end)
+        : m_begin(begin)
+        , m_end(end)
+    {
+        ASSERT(m_end >= m_begin);
+        if (m_begin == m_end) {
+            // Canonicalize empty ranges.
+            m_begin = 0;
+            m_end = 0;
+        }
+    }
+
+    static HeapRange top()
+    {
+        return HeapRange(0, UINT_MAX);
+    }
+
+    bool operator==(const HeapRange& other) const
+    {
+        return m_begin == other.m_begin
+            && m_end == other.m_end;
+    }
+
+    bool operator!=(const HeapRange& other) const
+    {
+        return !(*this == other);
+    }
+    
+    explicit operator bool() const { return m_begin != m_end; }
+
+    unsigned begin() const { return m_begin; }
+    unsigned end() const { return m_end; }
+
+    bool overlaps(const HeapRange& other) const
+    {
+        return WTF::rangesOverlap(m_begin, m_end, other.m_begin, other.m_end);
+    }
+
+    JS_EXPORT_PRIVATE void dump(PrintStream& out) const;
+
+private:
+    unsigned m_begin;
+    unsigned m_end;
+};
+
+} } // namespace JSC::B3
+
+#endif // ENABLE(B3_JIT)