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diff --git a/Source/JavaScriptCore/dfg/DFGPhiChildren.h b/Source/JavaScriptCore/dfg/DFGPhiChildren.h
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+++ b/Source/JavaScriptCore/dfg/DFGPhiChildren.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. ``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(DFG_JIT)
+
+#include "DFGNode.h"
+#include <wtf/HashSet.h>
+#include <wtf/Vector.h>
+
+namespace JSC { namespace DFG {
+
+class Graph;
+
+class PhiChildren {
+    WTF_MAKE_FAST_ALLOCATED;
+public:
+    typedef Vector<Node*, 3> List;
+    
+    PhiChildren();
+    PhiChildren(Graph&);
+    ~PhiChildren();
+    
+    // The list of Upsilons that point to the children of the Phi.
+    const List& upsilonsOf(Node*) const;
+    
+    template<typename Functor>
+    void forAllIncomingValues(Node* node, const Functor& functor)
+    {
+        for (Node* upsilon : upsilonsOf(node))
+            functor(upsilon->child1().node());
+    }
+    
+    // This walks the Phi graph.
+    template<typename Functor>
+    void forAllTransitiveIncomingValues(Node* node, const Functor& functor)
+    {
+        if (node->op() != Phi) {
+            functor(node);
+            return;
+        }
+        HashSet<Node*> seen;
+        Vector<Node*> worklist;
+        seen.add(node);
+        worklist.append(node);
+        while (!worklist.isEmpty()) {
+            Node* currentNode = worklist.takeLast();
+            forAllIncomingValues(
+                currentNode,
+                [&] (Node* incomingNode) {
+                    if (incomingNode->op() == Phi) {
+                        if (seen.add(incomingNode).isNewEntry)
+                            worklist.append(incomingNode);
+                    } else
+                        functor(incomingNode);
+                });
+        }
+    }
+    
+private:
+    HashMap<Node*, List> m_children;
+};
+
+} } // namespace JSC::DFG
+
+#endif // ENABLE(DFG_JIT)