--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/graal/com.oracle.truffle.api.test/src/com/oracle/truffle/api/test/ThreadSafetyTest.java	Thu Mar 20 01:29:19 2014 +0100
@@ -0,0 +1,196 @@
+/*
+ * Copyright (c) 2014, 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.
+ *
+ * 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.truffle.api.test;
+
+import static org.junit.Assert.*;
+
+import java.io.*;
+import java.util.*;
+import java.util.concurrent.*;
+import java.util.concurrent.atomic.*;
+
+import org.junit.*;
+
+import com.oracle.truffle.api.*;
+import com.oracle.truffle.api.frame.*;
+import com.oracle.truffle.api.nodes.*;
+
+/**
+ * Test node rewriting in a tree shared across multiple threads (run with -ea).
+ */
+public class ThreadSafetyTest {
+
+    @Test
+    public void test() throws InterruptedException {
+        TruffleRuntime runtime = Truffle.getRuntime();
+        TestRootNode rootNode1 = new TestRootNode(new RewritingNode(new RewritingNode(new RewritingNode(new RewritingNode(new RewritingNode(new ConstNode(42)))))));
+        final CallTarget target1 = runtime.createCallTarget(rootNode1);
+        NodeUtil.verify(rootNode1);
+
+        RecursiveCallNode callNode = new RecursiveCallNode(new ConstNode(42));
+        TestRootNode rootNode2 = new TestRootNode(new RewritingNode(new RewritingNode(new RewritingNode(new RewritingNode(new RewritingNode(callNode))))));
+        final CallTarget target2 = runtime.createCallTarget(rootNode2);
+        callNode.setCallNode(runtime.createCallNode(target2));
+        NodeUtil.verify(rootNode2);
+
+        testTarget(target1, 47, 1_000_000);
+        testTarget(target2, 72, 1_000_000);
+    }
+
+    private static void testTarget(final CallTarget target, final int expectedResult, final int numberOfIterations) throws InterruptedException {
+        ExecutorService executorService = Executors.newFixedThreadPool(20);
+        final AtomicInteger ai = new AtomicInteger();
+        for (int i = 0; i < numberOfIterations; i++) {
+            executorService.submit(new Runnable() {
+                public void run() {
+                    try {
+                        Object result = target.call(new TestArguments(5));
+                        assertEquals(expectedResult, result);
+                        ai.incrementAndGet();
+                    } catch (Throwable t) {
+                        PrintStream out = System.out;
+                        out.println(t);
+                    }
+                }
+            });
+        }
+        executorService.shutdown();
+        executorService.awaitTermination(30, TimeUnit.SECONDS);
+        assertEquals(numberOfIterations, ai.get());
+    }
+
+    static class TestArguments extends Arguments {
+        final int arg;
+
+        public TestArguments(int arg) {
+            this.arg = arg;
+        }
+    }
+
+    static class TestRootNode extends RootNode {
+
+        @Child private ValueNode child;
+
+        public TestRootNode(ValueNode child) {
+            super(null);
+            this.child = child;
+        }
+
+        @Override
+        public Object execute(VirtualFrame frame) {
+            return child.execute(frame);
+        }
+    }
+
+    abstract static class ValueNode extends Node {
+
+        public ValueNode() {
+            super(null);
+        }
+
+        abstract int execute(VirtualFrame frame);
+    }
+
+    static class RewritingNode extends ValueNode {
+
+        @Child private ValueNode child;
+        private final Random random;
+
+        public RewritingNode(ValueNode child) {
+            this(child, new Random());
+        }
+
+        public RewritingNode(ValueNode child, Random random) {
+            this.child = child;
+            this.random = random;
+        }
+
+        @Override
+        int execute(VirtualFrame frame) {
+            boolean replace = random.nextBoolean();
+            if (replace) {
+                ValueNode newNode = this.replace(new OtherRewritingNode(child, random));
+                return newNode.execute(frame);
+            }
+            return 1 + child.execute(frame);
+        }
+    }
+
+    static class OtherRewritingNode extends ValueNode {
+
+        @Child private ValueNode child;
+        private final Random random;
+
+        public OtherRewritingNode(ValueNode child, Random random) {
+            this.child = child;
+            this.random = random;
+        }
+
+        @Override
+        int execute(VirtualFrame frame) {
+            boolean replace = random.nextBoolean();
+            if (replace) {
+                ValueNode newNode = this.replace(new RewritingNode(child, random));
+                return newNode.execute(frame);
+            }
+            return 1 + child.execute(frame);
+        }
+    }
+
+    static class ConstNode extends ValueNode {
+
+        private final int value;
+
+        ConstNode(int value) {
+            this.value = value;
+        }
+
+        @Override
+        int execute(VirtualFrame frame) {
+            return value;
+        }
+    }
+
+    static class RecursiveCallNode extends ValueNode {
+        @Child CallNode callNode;
+        @Child private ValueNode valueNode;
+
+        RecursiveCallNode(ValueNode value) {
+            this.valueNode = value;
+        }
+
+        @Override
+        int execute(VirtualFrame frame) {
+            int arg = frame.getArguments(TestArguments.class).arg;
+            if (arg > 0) {
+                return (int) callNode.call(frame.pack(), new TestArguments(arg - 1));
+            } else {
+                return valueNode.execute(frame);
+            }
+        }
+
+        void setCallNode(CallNode callNode) {
+            this.callNode = insert(callNode);
+        }
+    }
+}