--- /dev/null	2015-06-23 14:29:20.000000000 +0200
+++ new/src/java.base/share/classes/jdk/internal/jimage/PerfectHashBuilder.java	2015-06-23 14:29:20.000000000 +0200
@@ -0,0 +1,255 @@
+/*
+ * Copyright (c) 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.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * 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 jdk.internal.jimage;
+
+import java.lang.reflect.Array;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+
+public class PerfectHashBuilder<E> {
+    private final static int RETRY_LIMIT = 1000;
+
+    private Class<?> entryComponent;
+    private Class<?> bucketComponent;
+
+    private final Map<UTF8String, Entry<E>> map = new LinkedHashMap<>();
+    private int[] redirect;
+    private Entry<E>[] order;
+    private int count = 0;
+
+    @SuppressWarnings("EqualsAndHashcode")
+    public static class Entry<E> {
+        private final UTF8String key;
+        private final E value;
+
+        Entry() {
+            this("", null);
+        }
+
+        Entry(String key, E value) {
+            this(new UTF8String(key), value);
+        }
+
+        Entry(UTF8String key, E value) {
+            this.key = key;
+            this.value = value;
+        }
+
+        UTF8String getKey() {
+            return key;
+        }
+
+        E getValue() {
+            return value;
+        }
+
+        int hashCode(int seed) {
+            return key.hashCode(seed);
+        }
+
+        @Override
+        public int hashCode() {
+            return key.hashCode();
+        }
+    }
+
+    static class Bucket<E> implements Comparable<Bucket<E>> {
+        final List<Entry<E>> list = new ArrayList<>();
+
+        void add(Entry<E> entry) {
+            list.add(entry);
+        }
+
+        int getSize() {
+            return list.size();
+        }
+
+        List<Entry<E>> getList() {
+            return list;
+        }
+
+        Entry<E> getFirst() {
+            assert !list.isEmpty() : "bucket should never be empty";
+            return list.get(0);
+        }
+
+        @Override
+        public int hashCode() {
+            return getFirst().hashCode();
+        }
+
+        @Override
+        @SuppressWarnings("EqualsWhichDoesntCheckParameterClass")
+        public boolean equals(Object obj) {
+            return this == obj;
+        }
+
+        @Override
+        public int compareTo(Bucket<E> o) {
+            return o.getSize() - getSize();
+        }
+    }
+
+    public PerfectHashBuilder(Class<?> entryComponent, Class<?> bucketComponent) {
+        this.entryComponent = entryComponent;
+        this.bucketComponent = bucketComponent;
+    }
+
+    public int getCount() {
+        return map.size();
+    }
+
+    public int[] getRedirect() {
+        return redirect;
+    }
+
+    public Entry<E>[] getOrder() {
+        return order;
+    }
+
+    public Entry<E> put(String key, E value) {
+        return put(new UTF8String(key), value);
+    }
+
+    public Entry<E> put(UTF8String key, E value) {
+        return put(new Entry<>(key, value));
+    }
+
+    public Entry<E> put(Entry<E> entry) {
+        Entry<E> old = map.put(entry.key, entry);
+
+        if (old == null) {
+            count++;
+        }
+
+        return old;
+    }
+
+    @SuppressWarnings("unchecked")
+    public void generate() {
+        boolean redo = count != 0;
+        while (redo) {
+            redo = false;
+            redirect = new int[count];
+            order = (Entry<E>[])Array.newInstance(entryComponent, count);
+
+            Bucket<E>[] sorted = createBuckets();
+            int free = 0;
+
+            for (Bucket<E> bucket : sorted) {
+                if (bucket.getSize() != 1) {
+                    if (!collidedEntries(bucket, count)) {
+                        redo = true;
+                        break;
+                    }
+                } else {
+                    for ( ; free < count && order[free] != null; free++) {}
+
+                    if (free >= count) {
+                        redo = true;
+                        break;
+                    }
+
+                    order[free] = bucket.getFirst();
+                    redirect[bucket.hashCode() % count] = -1 - free;
+                    free++;
+                }
+            }
+
+            if (redo) {
+                count = (count + 1) | 1;
+            }
+        }
+    }
+
+    @SuppressWarnings("unchecked")
+    private Bucket<E>[] createBuckets() {
+        Bucket<E>[] buckets = (Bucket<E>[])Array.newInstance(bucketComponent, count);
+
+        map.values().stream().forEach((entry) -> {
+            int index = entry.hashCode() % count;
+            Bucket<E> bucket = buckets[index];
+
+            if (bucket == null) {
+                buckets[index] = bucket = new Bucket<>();
+            }
+
+            bucket.add(entry);
+        });
+
+        Bucket<E>[] sorted = Arrays.asList(buckets).stream()
+                .filter((bucket) -> (bucket != null))
+                .sorted()
+                .toArray((length) -> {
+                    return (Bucket<E>[])Array.newInstance(bucketComponent, length);
+                });
+
+        return sorted;
+    }
+
+    private boolean collidedEntries(Bucket<E> bucket, int count) {
+        List<Integer> undo = new ArrayList<>();
+        int seed = UTF8String.HASH_MULTIPLIER + 1;
+        int retry = 0;
+
+        redo:
+        while (true) {
+            for (Entry<E> entry : bucket.getList()) {
+                int index = entry.hashCode(seed) % count;
+                if (order[index] != null) {
+                    if (++retry > RETRY_LIMIT) {
+                        return false;
+                    }
+
+                    undo.stream().forEach((i) -> {
+                        order[i] = null;
+                    });
+
+                    undo.clear();
+                    seed++;
+
+                    if (seed == 0) {
+                        seed = 1;
+                    }
+
+                    continue redo;
+                }
+
+                order[index] = entry;
+                undo.add(index);
+            }
+
+            redirect[bucket.hashCode() % count] = seed;
+
+            break;
+        }
+
+        return true;
+    }
+ }