--- a/src/share/vm/opto/cfgnode.cpp	Thu Jul 30 16:05:56 2009 -0700
+++ b/src/share/vm/opto/cfgnode.cpp	Fri Jul 31 12:04:07 2009 -0700
@@ -1792,15 +1792,12 @@
   if (UseCompressedOops && can_reshape && progress == NULL) {
     bool may_push = true;
     bool has_decodeN = false;
-    Node* in_decodeN = NULL;
     for (uint i=1; i<req(); ++i) {// For all paths in
       Node *ii = in(i);
       if (ii->is_DecodeN() && ii->bottom_type() == bottom_type()) {
-        // Note: in_decodeN is used only to define the type of new phi.
-        // Find a non dead path otherwise phi type will be wrong.
+        // Do optimization if a non dead path exist.
         if (ii->in(1)->bottom_type() != Type::TOP) {
           has_decodeN = true;
-          in_decodeN = ii->in(1);
         }
       } else if (!ii->is_Phi()) {
         may_push = false;
@@ -1809,7 +1806,9 @@
 
     if (has_decodeN && may_push) {
       PhaseIterGVN *igvn = phase->is_IterGVN();
-      PhiNode *new_phi = PhiNode::make_blank(in(0), in_decodeN);
+      // Make narrow type for new phi.
+      const Type* narrow_t = TypeNarrowOop::make(this->bottom_type()->is_ptr());
+      PhiNode* new_phi = new (phase->C, r->req()) PhiNode(r, narrow_t);
       uint orig_cnt = req();
       for (uint i=1; i<req(); ++i) {// For all paths in
         Node *ii = in(i);
@@ -1822,7 +1821,7 @@
           if (ii->as_Phi() == this) {
             new_ii = new_phi;
           } else {
-            new_ii = new (phase->C, 2) EncodePNode(ii, in_decodeN->bottom_type());
+            new_ii = new (phase->C, 2) EncodePNode(ii, narrow_t);
             igvn->register_new_node_with_optimizer(new_ii);
           }
         }

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/compiler/6865031/Test.java	Fri Jul 31 12:04:07 2009 -0700
@@ -0,0 +1,650 @@
+/*
+ * Copyright 2009 Goldman Sachs International.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ *
+ */
+
+/*
+ * @test
+ * @bug 6865031
+ * @summary Application gives bad result (throws bad exception) with compressed oops
+ * @run main/othervm -XX:+UseCompressedOops -XX:HeapBaseMinAddress=32g -XX:-LoopUnswitching -XX:CompileCommand=inline,AbstractMemoryEfficientList.equals Test hello goodbye
+ */
+
+import java.lang.ref.ReferenceQueue;
+import java.lang.ref.WeakReference;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+interface MyList {
+    public int size();
+    public Object set(final int index, final Object element);
+    public Object get(final int index);
+}
+
+abstract class AbstractMemoryEfficientList implements MyList {
+    abstract public int size();
+    abstract public Object get(final int index);
+    abstract public Object set(final int index, final Object element);
+
+    public boolean equals(Object o) {
+        if (o == this) {
+            return true;
+        }
+
+        if (!(o instanceof MyList)) {
+            return false;
+        }
+
+        final MyList that = (MyList) o;
+        if (this.size() != that.size()) {
+            return false;
+        }
+
+        for (int i = 0; i < this.size(); i++) {
+            try {
+                if (!((this.get(i)).equals(that.get(i)))) {
+                    return false;
+                }
+            } catch (IndexOutOfBoundsException e) {
+                System.out.println("THROWING RT EXC");
+                System.out.println("concurrent modification of this:" + this.getClass() + ":" + System.identityHashCode(this) + "; that:" + that.getClass() + ":" + System.identityHashCode(that) + "; i:" + i);
+                e.printStackTrace();
+                System.exit(97);
+                throw new RuntimeException("concurrent modification of this:" + this.getClass() + ":" + System.identityHashCode(this) + "; that:" + that.getClass() + ":" + System.identityHashCode(that) + "; i:" + i, e);
+            }
+        }
+        return true;
+    }
+
+    public int hashCode() {
+        int hashCode = 1;
+        for (int i = 0; i < this.size(); i++) {
+            Object obj = this.get(i);
+            hashCode = 31 * hashCode + (obj == null ? 0 : obj.hashCode());
+        }
+        return hashCode;
+    }
+}
+
+final class SingletonList extends AbstractMemoryEfficientList {
+    private Object element1;
+
+    SingletonList(final Object obj1) {
+        super();
+        this.element1 = obj1;
+    }
+
+    public int size() {
+        return 1;
+    }
+
+    public Object get(final int index) {
+        if (index == 0) {
+            return this.element1;
+        } else {
+            throw new IndexOutOfBoundsException("Index: " + index + ", Size: " + this.size());
+        }
+    }
+
+    public Object set(final int index, final Object element) {
+        if (index == 0) {
+            final Object previousElement = this.element1;
+            this.element1 = element;
+            return previousElement;
+        } else {
+            throw new IndexOutOfBoundsException("Index: " + index + ", Size: " + this.size());
+        }
+    }
+}
+
+final class DoubletonList extends AbstractMemoryEfficientList {
+    private Object element1;
+    private Object element2;
+
+    DoubletonList(final Object obj1, final Object obj2) {
+        this.element1 = obj1;
+        this.element2 = obj2;
+    }
+
+    public int size() {
+        return 2;
+    }
+
+    public Object get(final int index) {
+        switch (index) {
+            case 0 : return this.element1;
+            case 1 : return this.element2;
+            default: throw new IndexOutOfBoundsException("Index: " + index + ", Size: " + this.size());
+        }
+    }
+
+    public Object set(final int index, final Object element) {
+        switch (index) {
+            case 0 :
+            {
+                final Object previousElement = this.element1;
+                this.element1 = element;
+                return previousElement;
+            }
+            case 1 :
+            {
+                final Object previousElement = this.element2;
+                this.element2 = element;
+                return previousElement;
+            }
+            default : throw new IndexOutOfBoundsException("Index: " + index + ", Size: " + this.size());
+        }
+    }
+}
+
+class WeakPool<V> {
+    protected static final int DEFAULT_INITIAL_CAPACITY = 16;
+    private static final int MAXIMUM_CAPACITY = 1 << 30;
+    private static final float DEFAULT_LOAD_FACTOR = 0.75f;
+
+    protected Entry<V>[] table;
+
+    private int size;
+    protected int threshold;
+    private final float loadFactor;
+    private final ReferenceQueue<V> queue = new ReferenceQueue<V>();
+
+    public WeakPool()
+    {
+        this.loadFactor = DEFAULT_LOAD_FACTOR;
+        threshold = DEFAULT_INITIAL_CAPACITY;
+        table = new Entry[DEFAULT_INITIAL_CAPACITY];
+    }
+
+    /**
+     * Check for equality of non-null reference x and possibly-null y.  By
+     * default uses Object.equals.
+     */
+    private boolean eq(Object x, Object y)
+    {
+        return x == y || x.equals(y);
+    }
+
+    /**
+     * Return index for hash code h.
+     */
+    private int indexFor(int h, int length)
+    {
+        return h & length - 1;
+    }
+
+    /**
+     * Expunge stale entries from the table.
+     */
+    private void expungeStaleEntries()
+    {
+        Object r;
+        while ((r = queue.poll()) != null)
+        {
+            Entry e = (Entry) r;
+            int h = e.hash;
+            int i = indexFor(h, table.length);
+
+            // System.out.println("EXPUNGING " + h);
+            Entry<V> prev = table[i];
+            Entry<V> p = prev;
+            while (p != null)
+            {
+                Entry<V> next = p.next;
+                if (p == e)
+                {
+                    if (prev == e)
+                    {
+                        table[i] = next;
+                    }
+                    else
+                    {
+                        prev.next = next;
+                    }
+                    e.next = null;  // Help GC
+                    size--;
+                    break;
+                }
+                prev = p;
+                p = next;
+            }
+        }
+    }
+
+    /**
+     * Return the table after first expunging stale entries
+     */
+    private Entry<V>[] getTable()
+    {
+        expungeStaleEntries();
+        return table;
+    }
+
+    /**
+     * Returns the number of key-value mappings in this map.
+     * This result is a snapshot, and may not reflect unprocessed
+     * entries that will be removed before next attempted access
+     * because they are no longer referenced.
+     */
+    public int size()
+    {
+        if (size == 0)
+        {
+            return 0;
+        }
+        expungeStaleEntries();
+        return size;
+    }
+
+    /**
+     * Returns <tt>true</tt> if this map contains no key-value mappings.
+     * This result is a snapshot, and may not reflect unprocessed
+     * entries that will be removed before next attempted access
+     * because they are no longer referenced.
+     */
+    public boolean isEmpty()
+    {
+        return size() == 0;
+    }
+
+    /**
+     * Returns the value stored in the pool that equals the requested key
+     * or <tt>null</tt> if the map contains no mapping for
+     * this key (or the key is null)
+     *
+     * @param key the key whose equals value is to be returned.
+     * @return the object that is equal the specified key, or
+     *         <tt>null</tt> if key is null or no object in the pool equals the key.
+     */
+    public V get(V key)
+    {
+        if (key == null)
+        {
+            return null;
+        }
+        int h = key.hashCode();
+        Entry<V>[] tab = getTable();
+        int index = indexFor(h, tab.length);
+        Entry<V> e = tab[index];
+        while (e != null)
+        {
+            V candidate = e.get();
+            if (e.hash == h && eq(key, candidate))
+            {
+                return candidate;
+            }
+            e = e.next;
+        }
+        return null;
+    }
+
+    /**
+     * Returns the entry associated with the specified key in the HashMap.
+     * Returns null if the HashMap contains no mapping for this key.
+     */
+    Entry getEntry(Object key)
+    {
+        int h = key.hashCode();
+        Entry[] tab = getTable();
+        int index = indexFor(h, tab.length);
+        Entry e = tab[index];
+        while (e != null && !(e.hash == h && eq(key, e.get())))
+        {
+            e = e.next;
+        }
+        return e;
+    }
+
+    /**
+     * Places the object into the pool. If the object is null, nothing happens.
+     * If an equal object already exists, it is not replaced.
+     *
+     * @param key the object to put into the pool. key may be null.
+     * @return the object in the pool that is equal to the key, or the newly placed key if no such object existed when put was called
+     */
+    public V put(V key)
+    {
+        if (key == null)
+        {
+            return null;
+        }
+        int h = key.hashCode();
+        Entry<V>[] tab = getTable();
+        int i = indexFor(h, tab.length);
+
+        for (Entry<V> e = tab[i]; e != null; e = e.next)
+        {
+            V candidate = e.get();
+            if (h == e.hash && eq(key, candidate))
+            {
+                return candidate;
+            }
+        }
+
+        tab[i] = new Entry<V>(key, queue, h, tab[i]);
+
+        if (++size >= threshold)
+        {
+            resize(tab.length * 2);
+        }
+
+    // System.out.println("Added " + key + " to pool");
+        return key;
+    }
+
+    /**
+     * Rehashes the contents of this map into a new array with a
+     * larger capacity.  This method is called automatically when the
+     * number of keys in this map reaches its threshold.
+     * <p/>
+     * If current capacity is MAXIMUM_CAPACITY, this method does not
+     * resize the map, but but sets threshold to Integer.MAX_VALUE.
+     * This has the effect of preventing future calls.
+     *
+     * @param newCapacity the new capacity, MUST be a power of two;
+     *                    must be greater than current capacity unless current
+     *                    capacity is MAXIMUM_CAPACITY (in which case value
+     *                    is irrelevant).
+     */
+    void resize(int newCapacity)
+    {
+        Entry<V>[] oldTable = getTable();
+        int oldCapacity = oldTable.length;
+        if (oldCapacity == MAXIMUM_CAPACITY)
+        {
+            threshold = Integer.MAX_VALUE;
+            return;
+        }
+
+        Entry<V>[] newTable = new Entry[newCapacity];
+        transfer(oldTable, newTable);
+        table = newTable;
+
+        /*
+         * If ignoring null elements and processing ref queue caused massive
+         * shrinkage, then restore old table.  This should be rare, but avoids
+         * unbounded expansion of garbage-filled tables.
+         */
+        if (size >= threshold / 2)
+        {
+            threshold = (int) (newCapacity * loadFactor);
+        }
+        else
+        {
+            expungeStaleEntries();
+            transfer(newTable, oldTable);
+            table = oldTable;
+        }
+    }
+
+    /**
+     * Transfer all entries from src to dest tables
+     */
+    private void transfer(Entry[] src, Entry[] dest)
+    {
+        for (int j = 0; j < src.length; ++j)
+        {
+            Entry e = src[j];
+            src[j] = null;
+            while (e != null)
+            {
+                Entry next = e.next;
+                Object key = e.get();
+                if (key == null)
+                {
+                    e.next = null;  // Help GC
+                    size--;
+                }
+                else
+                {
+                    int i = indexFor(e.hash, dest.length);
+                    e.next = dest[i];
+                    dest[i] = e;
+                }
+                e = next;
+            }
+        }
+    }
+
+    /**
+     * Removes the object in the pool that equals the key.
+     *
+     * @param key
+     * @return previous value associated with specified key, or <tt>null</tt>
+     *         if there was no mapping for key or the key is null.
+     */
+    public V removeFromPool(V key)
+    {
+        if (key == null)
+        {
+            return null;
+        }
+        int h = key.hashCode();
+        Entry<V>[] tab = getTable();
+        int i = indexFor(h, tab.length);
+        Entry<V> prev = tab[i];
+        Entry<V> e = prev;
+
+        while (e != null)
+        {
+            Entry<V> next = e.next;
+            V candidate = e.get();
+            if (h == e.hash && eq(key, candidate))
+            {
+                size--;
+                if (prev == e)
+                {
+                    tab[i] = next;
+                }
+                else
+                {
+                    prev.next = next;
+                }
+                return candidate;
+            }
+            prev = e;
+            e = next;
+        }
+
+        return null;
+    }
+
+    /**
+     * Removes all mappings from this map.
+     */
+    public void clear()
+    {
+        // clear out ref queue. We don't need to expunge entries
+        // since table is getting cleared.
+        while (queue.poll() != null)
+        {
+            // nop
+        }
+
+        table = new Entry[DEFAULT_INITIAL_CAPACITY];
+        threshold = DEFAULT_INITIAL_CAPACITY;
+        size = 0;
+
+        // Allocation of array may have caused GC, which may have caused
+        // additional entries to go stale.  Removing these entries from the
+        // reference queue will make them eligible for reclamation.
+        while (queue.poll() != null)
+        {
+            // nop
+        }
+    }
+
+    /**
+     * The entries in this hash table extend WeakReference, using its main ref
+     * field as the key.
+     */
+    protected static class Entry<V>
+    extends WeakReference<V>
+    {
+        private final int hash;
+        private Entry<V> next;
+
+        /**
+         * Create new entry.
+         */
+        Entry(final V key, final ReferenceQueue<V> queue, final int hash, final Entry<V> next)
+        {
+            super(key, queue);
+            this.hash = hash;
+            this.next = next;
+        }
+
+        public V getKey()
+        {
+            return super.get();
+        }
+
+        public boolean equals(Object o)
+        {
+            if (!(o instanceof WeakPool.Entry))
+            {
+                return false;
+            }
+            WeakPool.Entry<V> that = (WeakPool.Entry<V>) o;
+            V k1 = this.getKey();
+            V k2 = that.getKey();
+            return (k1==k2 || k1.equals(k2));
+        }
+
+        public int hashCode()
+        {
+            return this.hash;
+        }
+
+        public String toString()
+        {
+            return String.valueOf(this.getKey());
+        }
+    }
+}
+
+final class MultiSynonymKey {
+    private List<MyList> keys;
+
+    public MultiSynonymKey() {
+        keys = new ArrayList<MyList>();
+    }
+
+    public MultiSynonymKey(MyList... arg) {
+        keys = Arrays.asList(arg);
+    }
+
+    public List<MyList> getKeys() {
+        return keys;
+    }
+
+    public int hashCode() {
+        return this.getKeys().hashCode();
+    }
+
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+
+        if (!(obj instanceof MultiSynonymKey)) {
+            return false;
+        }
+
+        MultiSynonymKey that = (MultiSynonymKey) obj;
+        return this.getKeys().equals(that.getKeys());
+    }
+
+    public String toString() {
+        return this.getClass().getName() + this.getKeys().toString();
+    }
+}
+
+public class Test extends Thread {
+    static public Test test;
+    static private byte[] arg1;
+    static private byte[] arg2;
+    static public WeakPool<MultiSynonymKey> wp;
+    public volatile MultiSynonymKey ml1;
+    public volatile MultiSynonymKey ml2;
+    private volatile MultiSynonymKey ml3;
+
+    public void run() {
+        int count=0;
+        while (true) {
+            try {
+                Thread.sleep(10);
+            } catch (Exception e) {}
+            synchronized (wp) {
+                ml2 = new MultiSynonymKey(new DoubletonList(new String(arg1), new String(arg2)));
+                wp.put(ml2);
+                ml3 = new MultiSynonymKey(new DoubletonList(new String(arg1), new String(arg2)));
+            }
+            try {
+                Thread.sleep(10);
+            } catch (Exception e) {}
+            synchronized (wp) {
+                ml1 = new MultiSynonymKey(new SingletonList(new String(arg1)));
+                wp.put(ml1);
+                ml3 = new MultiSynonymKey(new SingletonList(new String(arg1)));
+            }
+            if (count++==100)
+                System.exit(95);
+        }
+    }
+
+    public static void main(String[] args) throws Exception {
+        wp = new WeakPool<MultiSynonymKey>();
+        test = new Test();
+
+        test.arg1 = args[0].getBytes();
+        test.arg2 = args[1].getBytes();
+
+        test.ml1 = new MultiSynonymKey(new SingletonList(new String(test.arg1)));
+        test.ml2 = new MultiSynonymKey(new DoubletonList(new String(test.arg1), new String(test.arg2)));
+        test.ml3 = new MultiSynonymKey(new DoubletonList(new String(test.arg1), new String(test.arg2)));
+
+        wp.put(test.ml1);
+        wp.put(test.ml2);
+
+        test.setDaemon(true);
+        test.start();
+
+        int counter = 0;
+        while (true) {
+            synchronized (wp) {
+                MultiSynonymKey foo = test.ml3;
+
+                if (wp.put(foo) == foo) {
+                    // System.out.println("foo " + counter);
+                    // System.out.println(foo);
+                }
+            }
+            counter++;
+        }
+    }
+
+    private boolean eq(Object x, Object y) {
+        return x == y || x.equals(y);
+    }
+}