--- /dev/null	2016-05-31 09:42:47.975716356 -0700
+++ new/src/jdk.vm.compiler/share/classes/org.graalvm.compiler.lir/src/org/graalvm/compiler/lir/constopt/VariableMap.java	2016-12-09 00:54:20.430145441 -0800
@@ -0,0 +1,88 @@
+/*
+ * Copyright (c) 2014, 2014, 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.lir.constopt;
+
+import java.util.ArrayList;
+import java.util.function.Consumer;
+import java.util.function.Predicate;
+
+import org.graalvm.compiler.lir.Variable;
+
+/**
+ * Maps variables to a generic type.
+ *
+ * TODO (je) evaluate data structure
+ */
+class VariableMap<T> {
+
+    private final ArrayList<T> content;
+
+    VariableMap() {
+        content = new ArrayList<>();
+    }
+
+    public T get(Variable key) {
+        if (key == null || key.index >= content.size()) {
+            return null;
+        }
+        return content.get(key.index);
+    }
+
+    public T put(Variable key, T value) {
+        assert key != null : "Key cannot be null";
+        assert value != null : "Value cannot be null";
+        while (key.index >= content.size()) {
+            content.add(null);
+        }
+        return content.set(key.index, value);
+    }
+
+    public T remove(Variable key) {
+        assert key != null : "Key cannot be null";
+        if (key.index >= content.size()) {
+            return null;
+        }
+        return content.set(key.index, null);
+    }
+
+    public void forEach(Consumer<T> action) {
+        for (T e : content) {
+            if (e != null) {
+                action.accept(e);
+            }
+        }
+    }
+
+    /**
+     * Keeps only keys which match the given predicate.
+     */
+    public void filter(Predicate<T> predicate) {
+        for (int i = 0; i < content.size(); i++) {
+            T e = content.get(i);
+            if (e != null && !predicate.test(e)) {
+                content.set(i, null);
+            }
+        }
+    }
+
+}