src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/oops/Oop.java

*** 45,12 ***
  
    private static synchronized void initialize(TypeDataBase db) throws WrongTypeException {
      Type type  = db.lookupType("oopDesc");
      mark       = new CIntField(type.getCIntegerField("_mark"), 0);
      if (VM.getVM().isCompactObjectHeadersEnabled()) {
!       Type markType = db.lookupType("markWord");
-       headerSize = markType.getSize();
      } else {
        headerSize = type.getSize();
        klass      = new MetadataField(type.getAddressField("_metadata._klass"), 0);
        compressedKlass  = new NarrowKlassField(type.getAddressField("_metadata._compressed_klass"), 0);
      }
--- 45,11 ---
  
    private static synchronized void initialize(TypeDataBase db) throws WrongTypeException {
      Type type  = db.lookupType("oopDesc");
      mark       = new CIntField(type.getCIntegerField("_mark"), 0);
      if (VM.getVM().isCompactObjectHeadersEnabled()) {
!       headerSize = 4;
      } else {
        headerSize = type.getSize();
        klass      = new MetadataField(type.getAddressField("_metadata._klass"), 0);
        compressedKlass  = new NarrowKlassField(type.getAddressField("_metadata._compressed_klass"), 0);
      }

*** 130,10 ***
--- 129,14 ---
  
    public int hashCode() { return getHandle().hashCode(); }
  
    /** Identity hash in the target VM */
    public long identityHash() {
+     if (VM.getVM().isCompactObjectHeadersEnabled()) {
+       System.exit(-23);
+         throw new InternalError("Not yet implemented");
+     }
      Mark mark = getMark();
      if (mark.isUnlocked() && (!mark.hasNoHash())) {
        return (int) mark.hash();
      } else if (mark.isMarked()) {
        return (int) mark.hash();