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diff --git a/Source/JavaScriptCore/dfg/DFGLazyJSValue.h b/Source/JavaScriptCore/dfg/DFGLazyJSValue.h
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+/*
+ * Copyright (C) 2013, 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. ``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. 
+ */
+
+#ifndef DFGLazyJSValue_h
+#define DFGLazyJSValue_h
+
+#if ENABLE(DFG_JIT)
+
+#include "DFGCommon.h"
+#include "DFGFrozenValue.h"
+#include <wtf/text/StringImpl.h>
+
+namespace JSC { namespace DFG {
+
+// Represents either a JSValue, or for JSValues that require allocation in the heap,
+// it tells you everything you'd need to know in order to allocate it.
+
+enum LazinessKind {
+    KnownValue,
+    SingleCharacterString,
+    KnownStringImpl
+};
+
+class LazyJSValue {
+public:
+    LazyJSValue(FrozenValue* value = FrozenValue::emptySingleton())
+        : m_kind(KnownValue)
+    {
+        u.value = value;
+    }
+    
+    static LazyJSValue singleCharacterString(UChar character)
+    {
+        LazyJSValue result;
+        result.m_kind = SingleCharacterString;
+        result.u.character = character;
+        return result;
+    }
+    
+    static LazyJSValue knownStringImpl(StringImpl* string)
+    {
+        LazyJSValue result;
+        result.m_kind = KnownStringImpl;
+        result.u.stringImpl = string;
+        return result;
+    }
+    
+    FrozenValue* tryGetValue(Graph&) const
+    {
+        if (m_kind == KnownValue)
+            return value();
+        return nullptr;
+    }
+    
+    JSValue getValue(VM&) const;
+    
+    FrozenValue* value() const
+    {
+        ASSERT(m_kind == KnownValue);
+        return u.value;
+    }
+    
+    UChar character() const
+    {
+        ASSERT(m_kind == SingleCharacterString);
+        return u.character;
+    }
+    
+    StringImpl* stringImpl() const
+    {
+        ASSERT(m_kind == KnownStringImpl);
+        return u.stringImpl;
+    }
+    
+    TriState strictEqual(const LazyJSValue& other) const;
+    
+    uintptr_t switchLookupValue(SwitchKind) const;
+    
+    void dump(PrintStream&) const;
+    void dumpInContext(PrintStream&, DumpContext*) const;
+    
+private:
+    union {
+        FrozenValue* value;
+        UChar character;
+        StringImpl* stringImpl;
+    } u;
+    LazinessKind m_kind;
+};
+
+} } // namespace JSC::DFG
+
+#endif // ENABLE(DFG_JIT)
+
+#endif // DFGLazyJSValue_h
+