--- a/graal/com.oracle.graal.hotspot/src/com/oracle/graal/hotspot/HotSpotReferenceMapBuilder.java	Fri Jul 31 15:07:27 2015 +0200
+++ b/graal/com.oracle.graal.hotspot/src/com/oracle/graal/hotspot/HotSpotReferenceMapBuilder.java	Fri Jul 31 16:23:42 2015 +0200
@@ -85,7 +85,7 @@
             LIRKind kind = obj.getLIRKind();
             int bytes = bytesPerElement(kind);
             if (kind.isUnknownReference()) {
-                throw JVMCIError.unimplemented("derived references not yet implemented");
+                throw JVMCIError.shouldNotReachHere("unknown reference alive across safepoint");
             } else {
                 Location base = null;
                 if (kind.isDerivedReference()) {

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/graal/com.oracle.graal.replacements.test/src/com/oracle/graal/replacements/test/PointerTrackingTest.java	Fri Jul 31 16:23:42 2015 +0200
@@ -0,0 +1,137 @@
+/*
+ * Copyright (c) 2015, 2015, 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.replacements.test;
+
+import jdk.internal.jvmci.common.*;
+import jdk.internal.jvmci.meta.*;
+
+import org.junit.*;
+
+import com.oracle.graal.api.directives.*;
+import com.oracle.graal.compiler.test.*;
+import com.oracle.graal.debug.*;
+import com.oracle.graal.graphbuilderconf.GraphBuilderConfiguration.Plugins;
+import com.oracle.graal.graphbuilderconf.*;
+import com.oracle.graal.graphbuilderconf.InvocationPlugins.Registration;
+import com.oracle.graal.nodes.*;
+import com.oracle.graal.replacements.*;
+import com.oracle.graal.word.*;
+
+public class PointerTrackingTest extends GraalCompilerTest implements Snippets {
+
+    @Test
+    public void testTracking() {
+        Result result = executeActual(getResolvedJavaMethod("trackingSnippet"), null, new Object());
+        assertEquals(new Result("OK", null), result);
+    }
+
+    public static String trackingSnippet(Object obj) {
+        long trackedBeforeGC = getTrackedPointer(obj);
+        long untrackedBeforeGC = getUntrackedPointer(obj);
+
+        int i = 0;
+        while (untrackedBeforeGC == getTrackedPointer(obj)) {
+            System.gc();
+            if (i++ > 100) {
+                return "Timeout! Object didn't move after 100 GCs.";
+            }
+        }
+
+        long trackedAfterGC = getTrackedPointer(obj);
+        long untrackedAfterGC = getUntrackedPointer(obj);
+
+        if (untrackedBeforeGC == untrackedAfterGC) {
+            /*
+             * The untracked pointer isn't supposed to be updated, so it should be different before
+             * and after GC.
+             */
+            return "untrackedBeforeGC == untrackedAfterGC";
+        }
+        if (trackedBeforeGC != trackedAfterGC) {
+            /*
+             * The trackedBeforeGC variable should be updated to the new location by the GC, so it
+             * should be equal to trackedAfterGC.
+             */
+            return "trackedBeforeGC != trackedAfterGC";
+        }
+
+        return "OK";
+    }
+
+    @Test(expected = JVMCIError.class)
+    public void testVerification() {
+        try (DebugConfigScope scope = Debug.disableIntercept()) {
+            compile(getResolvedJavaMethod("verificationSnippet"), null);
+        }
+    }
+
+    public static long verificationSnippet(Object obj) {
+        long value = getTrackedPointer(obj) * 7 + 3;
+
+        /*
+         * Ensure usage before and after GC to force the value to be alive across the safepoint.
+         * This should lead to a compiler error, since value can not be tracked in the reference
+         * map.
+         */
+        GraalDirectives.blackhole(value);
+        System.gc();
+        return value;
+    }
+
+    static long getTrackedPointer(@SuppressWarnings("unused") Object obj) {
+        throw JVMCIError.shouldNotReachHere("should be intrinsified");
+    }
+
+    static long getUntrackedPointer(@SuppressWarnings("unused") Object obj) {
+        throw JVMCIError.shouldNotReachHere("should be intrinsified");
+    }
+
+    static long getTrackedPointerIntrinsic(Object obj) {
+        return Word.objectToTrackedPointer(obj).rawValue();
+    }
+
+    static long getUntrackedPointerIntrinsic(Object obj) {
+        return Word.objectToUntrackedPointer(obj).rawValue();
+    }
+
+    private void register(Registration r, String fnName) {
+        ResolvedJavaMethod intrinsic = getResolvedJavaMethod(fnName + "Intrinsic");
+        r.register1(fnName, Object.class, new InvocationPlugin() {
+            public boolean apply(GraphBuilderContext b, ResolvedJavaMethod targetMethod, Receiver receiver, ValueNode arg) {
+                b.intrinsify(targetMethod, intrinsic, new ValueNode[]{arg});
+                return true;
+            }
+        });
+    }
+
+    @Override
+    protected Plugins getDefaultGraphBuilderPlugins() {
+        Plugins plugins = super.getDefaultGraphBuilderPlugins();
+        Registration r = new Registration(plugins.getInvocationPlugins(), PointerTrackingTest.class);
+
+        register(r, "getTrackedPointer");
+        register(r, "getUntrackedPointer");
+
+        return plugins;
+    }
+}