--- /dev/null	2016-05-31 09:42:47.975716356 -0700
+++ new/src/jdk.vm.compiler/share/classes/org.graalvm.compiler.debug/src/org/graalvm/compiler/debug/internal/DebugValueMap.java	2016-12-07 13:49:05.790404487 -0800
@@ -0,0 +1,176 @@
+/*
+ * Copyright (c) 2012, 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.debug.internal;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * A node in a tree of {@link DebugValue}s.
+ */
+public class DebugValueMap {
+
+    private static final List<DebugValueMap> topLevelMaps = new ArrayList<>();
+
+    private long[] values;
+    private List<DebugValueMap> children;
+    private String name;
+
+    public DebugValueMap(String name) {
+        this.name = name;
+    }
+
+    public void setCurrentValue(int index, long l) {
+        ensureSize(index);
+        values[index] = l;
+    }
+
+    public long getCurrentValue(int index) {
+        ensureSize(index);
+        return values[index];
+    }
+
+    public void clearChildren() {
+        if (children != null) {
+            children.clear();
+        }
+    }
+
+    public void reset() {
+        if (values != null) {
+            Arrays.fill(values, 0L);
+        }
+        if (children != null) {
+            for (DebugValueMap child : children) {
+                child.reset();
+            }
+        }
+    }
+
+    private void ensureSize(int index) {
+        if (values == null) {
+            values = new long[index + 1];
+        }
+        if (values.length <= index) {
+            values = Arrays.copyOf(values, index + 1);
+        }
+    }
+
+    private int capacity() {
+        return (values == null) ? 0 : values.length;
+    }
+
+    public void addChild(DebugValueMap map) {
+        if (children == null) {
+            children = new ArrayList<>(4);
+        }
+        children.add(map);
+    }
+
+    public List<DebugValueMap> getChildren() {
+        if (children == null) {
+            return Collections.emptyList();
+        } else {
+            return Collections.unmodifiableList(children);
+        }
+    }
+
+    public boolean hasChildren() {
+        return children != null && !children.isEmpty();
+    }
+
+    public String getName() {
+        return this.name;
+    }
+
+    @Override
+    public String toString() {
+        return "DebugValueMap<" + getName() + ">";
+    }
+
+    public static synchronized void registerTopLevel(DebugValueMap map) {
+        topLevelMaps.add(map);
+    }
+
+    public static synchronized List<DebugValueMap> getTopLevelMaps() {
+        return topLevelMaps;
+    }
+
+    public void normalize() {
+        if (hasChildren()) {
+            Map<String, DebugValueMap> occurred = new HashMap<>();
+            for (DebugValueMap map : children) {
+                String mapName = map.getName();
+                if (!occurred.containsKey(mapName)) {
+                    occurred.put(mapName, map);
+                    map.normalize();
+                } else {
+                    occurred.get(mapName).mergeWith(map);
+                    occurred.get(mapName).normalize();
+                }
+            }
+
+            if (occurred.values().size() < children.size()) {
+                // At least one duplicate was found.
+                children.clear();
+                for (DebugValueMap map : occurred.values()) {
+                    addChild(map);
+                    map.normalize();
+                }
+            }
+        }
+    }
+
+    private void mergeWith(DebugValueMap map) {
+        if (map.hasChildren()) {
+            if (hasChildren()) {
+                children.addAll(map.children);
+            } else {
+                children = map.children;
+            }
+            map.children = null;
+        }
+
+        int size = Math.max(this.capacity(), map.capacity());
+        ensureSize(size);
+        for (int i = 0; i < size; ++i) {
+            long curValue = getCurrentValue(i);
+            long otherValue = map.getCurrentValue(i);
+            setCurrentValue(i, curValue + otherValue);
+        }
+    }
+
+    public void group() {
+        if (this.hasChildren()) {
+            List<DebugValueMap> oldChildren = new ArrayList<>(this.children);
+            this.children.clear();
+            for (DebugValueMap map : oldChildren) {
+                mergeWith(map);
+            }
+        }
+    }
+}