--- /dev/null	2016-05-31 09:42:47.975716356 -0700
+++ new/src/jdk.vm.compiler/share/classes/org.graalvm.compiler.graph/src/org/graalvm/compiler/graph/CachedGraph.java	2016-12-09 00:48:23.248400703 -0800
@@ -0,0 +1,68 @@
+/*
+ * Copyright (c) 2015, 2015, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+package org.graalvm.compiler.graph;
+
+import java.util.Map;
+import java.util.function.Consumer;
+
+/**
+ * This class is a container of a graph that needs to be readonly and optionally a lazily created
+ * mutable copy of the graph.
+ */
+public final class CachedGraph<G extends Graph> {
+
+    private final G readonlyCopy;
+    private G mutableCopy;
+
+    private CachedGraph(G readonlyCopy, G mutableCopy) {
+        this.readonlyCopy = readonlyCopy;
+        this.mutableCopy = mutableCopy;
+    }
+
+    public static <G extends Graph> CachedGraph<G> fromReadonlyCopy(G graph) {
+        return new CachedGraph<>(graph, null);
+    }
+
+    public static <G extends Graph> CachedGraph<G> fromMutableCopy(G graph) {
+        return new CachedGraph<>(graph, graph);
+    }
+
+    public G getReadonlyCopy() {
+        if (hasMutableCopy()) {
+            return mutableCopy;
+        }
+        return readonlyCopy;
+    }
+
+    public boolean hasMutableCopy() {
+        return mutableCopy != null;
+    }
+
+    @SuppressWarnings("unchecked")
+    public G getMutableCopy(Consumer<Map<Node, Node>> duplicationMapCallback) {
+        if (!hasMutableCopy()) {
+            mutableCopy = (G) readonlyCopy.copy(duplicationMapCallback);
+        }
+        return mutableCopy;
+    }
+}