--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/graal/GraalCompiler/src/com/sun/c1x/util/ArrayMap.java	Wed Apr 27 11:50:44 2011 +0200
@@ -0,0 +1,117 @@
+/*
+ * Copyright (c) 2009, 2010, 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 com.sun.c1x.util;
+
+/**
+ * The {@code ArrayMap} class implements an efficient one-level map which is implemented
+ * as an array. Note that because of the one-level array inside, this data structure performs best
+ * when the range of integer keys is small and densely used. Note that the implementation can
+ * handle arbitrary intervals, including negative numbers, up to intervals of size 2^31 - 1.
+ *
+ * @author Ben L. Titzer
+ */
+public class ArrayMap<T> {
+
+    private static final int INITIAL_SIZE = 5; // how big the initial array should be
+    private static final int EXTRA = 2; // how far on the left or right of a new element to grow
+
+    Object[] map;
+    int low;
+
+    /**
+     * Constructs a new {@code ArrayMap} with no initial assumptions.
+     */
+    public ArrayMap() {
+    }
+
+    /**
+     * Constructs a new {@code ArrayMap} that initially covers the specified interval.
+     * Note that this map will automatically expand if necessary later.
+     * @param low the low index, inclusive
+     * @param high the high index, exclusive
+     */
+    public ArrayMap(int low, int high) {
+        this.low = low;
+        this.map = new Object[high - low + 1];
+    }
+
+    /**
+     * Puts a new value in the map at the specified index.
+     * @param i the index at which to store the value
+     * @param value the value to store at the specified index
+     */
+    public void put(int i, T value) {
+        int index = i - low;
+        if (map == null) {
+            // no map yet
+            map = new Object[INITIAL_SIZE];
+            low = index - 2;
+            map[INITIAL_SIZE / 2] = value;
+        } else if (index < 0) {
+            // grow backwards
+            growBackward(i, value);
+        } else if (index >= map.length) {
+            // grow forwards
+            growForward(i, value);
+        } else {
+            // no growth necessary
+            map[index] = value;
+        }
+    }
+
+    /**
+     * Gets the value at the specified index in the map.
+     * @param i the index
+     * @return the value at the specified index; {@code null} if there is no value at the specified index,
+     * or if the index is out of the currently stored range
+     */
+    public T get(int i) {
+        int index = i - low;
+        if (map == null || index < 0 || index >= map.length) {
+            return null;
+        }
+        Class<T> type = null;
+        return Util.uncheckedCast(type, map[index]);
+    }
+
+    public int length() {
+        return map.length;
+    }
+
+    private void growBackward(int i, T value) {
+        int nlow = i - EXTRA;
+        Object[] nmap = new Object[low - nlow + map.length];
+        System.arraycopy(map, 0, nmap, low - nlow, map.length);
+        map = nmap;
+        low = nlow;
+        map[i - low] = value;
+    }
+
+    private void growForward(int i, T value) {
+        int nlen = i - low + 1 + EXTRA;
+        Object[] nmap = new Object[nlen];
+        System.arraycopy(map, 0, nmap, 0, map.length);
+        map = nmap;
+        map[i - low] = value;
+    }
+}