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diff --git a/Source/JavaScriptCore/ftl/FTLLoweredNodeValue.h b/Source/JavaScriptCore/ftl/FTLLoweredNodeValue.h
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+++ b/Source/JavaScriptCore/ftl/FTLLoweredNodeValue.h
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+/*
+ * Copyright (C) 2013 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 FTLLoweredNodeValue_h
+#define FTLLoweredNodeValue_h
+
+#if ENABLE(FTL_JIT)
+
+#include "DFGBasicBlock.h"
+#include "FTLAbbreviatedTypes.h"
+
+namespace JSC { namespace FTL {
+
+// Represents the act of having lowered a DFG::Node to an LValue, and records the
+// DFG::BasicBlock that did the lowering. The LValue is what we use most often, but
+// we need to verify that we're in a block that is dominated by the one that did
+// the lowering. We're guaranteed that for each DFG::Node, there will be one
+// LoweredNodeValue that always dominates all uses of the DFG::Node; but there may
+// be others that don't dominate and we're effectively doing opportunistic GVN on
+// the lowering code.
+
+class LoweredNodeValue {
+public:
+    LoweredNodeValue()
+        : m_value(0)
+        , m_block(0)
+    {
+    }
+    
+    LoweredNodeValue(LValue value, DFG::BasicBlock* block)
+        : m_value(value)
+        , m_block(block)
+    {
+        ASSERT(m_value);
+        ASSERT(m_block);
+    }
+    
+    bool isSet() const { return !!m_value; }
+    bool operator!() const { return !isSet(); }
+    
+    LValue value() const { return m_value; }
+    DFG::BasicBlock* block() const { return m_block; }
+    
+private:
+    LValue m_value;
+    DFG::BasicBlock* m_block;
+};
+
+} } // namespace JSC::FTL
+
+#endif // ENABLE(FTL_JIT)
+
+#endif // FTLLoweredNodeValue_h
+