--- a/graal/com.oracle.graal.compiler/src/com/oracle/graal/compiler/gen/DebugInfoBuilder.java	Fri Mar 29 12:33:24 2013 +0100
+++ b/graal/com.oracle.graal.compiler/src/com/oracle/graal/compiler/gen/DebugInfoBuilder.java	Fri Mar 29 12:54:56 2013 +0100
@@ -106,6 +106,10 @@
         }
         objectStates.clear();
 
+        return newLIRFrameState(reason, exceptionEdge, frame, virtualObjectsArray);
+    }
+
+    protected LIRFrameState newLIRFrameState(short reason, LabelRef exceptionEdge, BytecodeFrame frame, VirtualObject[] virtualObjectsArray) {
         return new LIRFrameState(frame, virtualObjectsArray, exceptionEdge, reason);
     }
 

--- a/graal/com.oracle.graal.hotspot/src/com/oracle/graal/hotspot/HotSpotDebugInfoBuilder.java	Fri Mar 29 12:33:24 2013 +0100
+++ b/graal/com.oracle.graal.hotspot/src/com/oracle/graal/hotspot/HotSpotDebugInfoBuilder.java	Fri Mar 29 12:54:56 2013 +0100
@@ -26,6 +26,7 @@
 import com.oracle.graal.api.meta.*;
 import com.oracle.graal.compiler.gen.*;
 import com.oracle.graal.graph.*;
+import com.oracle.graal.lir.*;
 import com.oracle.graal.nodes.*;
 import com.oracle.graal.nodes.virtual.*;
 
@@ -57,4 +58,9 @@
         boolean eliminated = lock instanceof VirtualObjectNode;
         return new MonitorValue(object, slot, eliminated);
     }
+
+    @Override
+    protected LIRFrameState newLIRFrameState(short reason, LabelRef exceptionEdge, BytecodeFrame frame, VirtualObject[] virtualObjectsArray) {
+        return new HotSpotLIRFrameState(frame, virtualObjectsArray, exceptionEdge, reason);
+    }
 }

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/graal/com.oracle.graal.hotspot/src/com/oracle/graal/hotspot/HotSpotLIRFrameState.java	Fri Mar 29 12:54:56 2013 +0100
@@ -0,0 +1,52 @@
+/*
+ * Copyright (c) 2013, 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.hotspot;
+
+import com.oracle.graal.api.code.*;
+import com.oracle.graal.api.meta.*;
+import com.oracle.graal.lir.*;
+import com.oracle.graal.lir.LIRInstruction.OperandMode;
+import com.oracle.graal.lir.LIRInstruction.ValueProcedure;
+
+/**
+ * Extends {@link LIRFrameState} to handle {@link MonitorValue}s correctly.
+ */
+class HotSpotLIRFrameState extends LIRFrameState {
+
+    public HotSpotLIRFrameState(BytecodeFrame topFrame, VirtualObject[] virtualObjects, LabelRef exceptionEdge, short deoptimizationReason) {
+        super(topFrame, virtualObjects, exceptionEdge, deoptimizationReason);
+    }
+
+    @Override
+    protected Value processValue(ValueProcedure proc, Value value) {
+        if (value instanceof MonitorValue) {
+            MonitorValue monitor = (MonitorValue) value;
+            if (processed(monitor.getOwner())) {
+                monitor.setOwner(proc.doValue(monitor.getOwner(), OperandMode.ALIVE, STATE_FLAGS));
+            }
+            return value;
+        } else {
+            return super.processValue(proc, value);
+        }
+    }
+}

--- a/graal/com.oracle.graal.lir/src/com/oracle/graal/lir/LIRFrameState.java	Fri Mar 29 12:33:24 2013 +0100
+++ b/graal/com.oracle.graal.lir/src/com/oracle/graal/lir/LIRFrameState.java	Fri Mar 29 12:54:56 2013 +0100
@@ -80,24 +80,23 @@
      * We filter out constant and illegal values ourself before calling the procedure, so
      * {@link OperandFlag#CONST} and {@link OperandFlag#ILLEGAL} need not be set.
      */
-    private static final EnumSet<OperandFlag> STATE_FLAGS = EnumSet.of(OperandFlag.REG, OperandFlag.STACK);
+    protected static final EnumSet<OperandFlag> STATE_FLAGS = EnumSet.of(OperandFlag.REG, OperandFlag.STACK);
 
-    private void processValues(Value[] values, ValueProcedure proc) {
+    protected void processValues(Value[] values, ValueProcedure proc) {
         for (int i = 0; i < values.length; i++) {
             Value value = values[i];
-            if (value instanceof MonitorValue) {
-                MonitorValue monitor = (MonitorValue) value;
-                if (processed(monitor.getOwner())) {
-                    monitor.setOwner(proc.doValue(monitor.getOwner(), OperandMode.ALIVE, STATE_FLAGS));
-                }
-
-            } else if (processed(value)) {
-                values[i] = proc.doValue(value, OperandMode.ALIVE, STATE_FLAGS);
-            }
+            values[i] = processValue(proc, value);
         }
     }
 
-    private boolean processed(Value value) {
+    protected Value processValue(ValueProcedure proc, Value value) {
+        if (processed(value)) {
+            return proc.doValue(value, OperandMode.ALIVE, STATE_FLAGS);
+        }
+        return value;
+    }
+
+    protected boolean processed(Value value) {
         if (isIllegal(value)) {
             // Ignore dead local variables.
             return false;