--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/graal/com.oracle.graal.graph/src/com/oracle/graal/graph/iterators/DistinctFilteredNodeIterable.java	Thu Jun 21 16:29:56 2012 +0200
@@ -0,0 +1,45 @@
+/*
+ * 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 com.oracle.graal.graph.iterators;
+
+import java.util.*;
+
+import com.oracle.graal.graph.*;
+
+
+public class DistinctFilteredNodeIterable<T extends Node> extends FilteredNodeIterable<T> {
+
+    public DistinctFilteredNodeIterable(NodeIterable<T> nodeIterable) {
+        super(nodeIterable);
+    }
+
+    @Override
+    public DistinctFilteredNodeIterable<T> distinct() {
+        return this;
+    }
+
+    @Override
+    public Iterator<T> iterator() {
+        return new DistinctPredicatedProxyNodeIterator<>(until, nodeIterable.iterator(), predicate);
+    }
+}

--- a/graal/com.oracle.graal.graph/src/com/oracle/graal/graph/iterators/FilteredNodeIterable.java	Thu Jun 21 16:29:14 2012 +0200
+++ b/graal/com.oracle.graal.graph/src/com/oracle/graal/graph/iterators/FilteredNodeIterable.java	Thu Jun 21 16:29:56 2012 +0200
@@ -27,10 +27,9 @@
 import com.oracle.graal.graph.*;
 
 public class FilteredNodeIterable<T extends Node> extends AbstractNodeIterable<T> {
-    private final NodeIterable<T> nodeIterable;
-    private NodePredicate predicate = NodePredicates.alwaysTrue();
-    private NodePredicate until = NodePredicates.isNull();
-    private boolean distinct;
+    protected final NodeIterable<T> nodeIterable;
+    protected NodePredicate predicate = NodePredicates.alwaysTrue();
+    protected NodePredicate until = NodePredicates.isNull();
     public FilteredNodeIterable(NodeIterable<T> nodeIterable) {
         this.nodeIterable = nodeIterable;
     }
@@ -58,18 +57,15 @@
         return this;
     }
     @Override
-    public FilteredNodeIterable<T> distinct() {
-        distinct = true;
-        return this;
+    public DistinctFilteredNodeIterable<T> distinct() {
+        DistinctFilteredNodeIterable<T> distinct = new DistinctFilteredNodeIterable<>(nodeIterable);
+        distinct.predicate = predicate;
+        distinct.until = until;
+        return distinct;
     }
     @Override
     public Iterator<T> iterator() {
-        final Iterator<T> iterator = nodeIterable.iterator();
-        if (distinct) {
-            return new DistinctPredicatedProxyNodeIterator<>(until, iterator, predicate);
-        } else {
-            return new PredicatedProxyNodeIterator<>(until, iterator, predicate);
-        }
+        return new PredicatedProxyNodeIterator<>(until, nodeIterable.iterator(), predicate);
     }
 
     @SuppressWarnings("unchecked")