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

@@ -44,13 +44,18 @@
    }
  
    private static synchronized void initialize(TypeDataBase db) throws WrongTypeException {
      Type type  = db.lookupType("oopDesc");
      mark       = new CIntField(type.getCIntegerField("_mark"), 0);
-     klass      = new MetadataField(type.getAddressField("_metadata._klass"), 0);
-     compressedKlass  = new NarrowKlassField(type.getAddressField("_metadata._compressed_klass"), 0);
-     headerSize = type.getSize();
+     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);
+     }
    }
  
    private OopHandle  handle;
    private ObjectHeap heap;
  

@@ -73,12 +78,21 @@
    private static MetadataField  klass;
    private static NarrowKlassField compressedKlass;
  
    // Accessors for declared fields
    public Mark  getMark()   { return new Mark(getHandle()); }
+ 
+   private static Klass getKlass(Mark mark) {
+     assert(VM.getVM().isCompactObjectHeadersEnabled());
+     return mark.getKlass();
+   }
+ 
    public Klass getKlass() {
-     if (VM.getVM().isCompressedKlassPointersEnabled()) {
+     if (VM.getVM().isCompactObjectHeadersEnabled()) {
+       assert(VM.getVM().isCompressedKlassPointersEnabled());
+       return getKlass(getMark());
+     } else if (VM.getVM().isCompressedKlassPointersEnabled()) {
        return (Klass)compressedKlass.getValue(getHandle());
      } else {
        return (Klass)klass.getValue(getHandle());
      }
    }

@@ -145,14 +159,16 @@
    }
  
    void iterateFields(OopVisitor visitor, boolean doVMFields) {
      if (doVMFields) {
        visitor.doCInt(mark, true);
-       if (VM.getVM().isCompressedKlassPointersEnabled()) {
-         visitor.doMetadata(compressedKlass, true);
-       } else {
-         visitor.doMetadata(klass, true);
+       if (!VM.getVM().isCompactObjectHeadersEnabled()) {
+         if (VM.getVM().isCompressedKlassPointersEnabled()) {
+           visitor.doMetadata(compressedKlass, true);
+         } else {
+           visitor.doMetadata(klass, true);
+         }
        }
      }
    }
  
    public void print()      { printOn(System.out); }

@@ -204,11 +220,14 @@
  
    public static Klass getKlassForOopHandle(OopHandle handle) {
      if (handle == null) {
        return null;
      }
-     if (VM.getVM().isCompressedKlassPointersEnabled()) {
+     if (VM.getVM().isCompactObjectHeadersEnabled()) {
+       Mark mark = new Mark(handle);
+       return getKlass(mark);
+     } else if (VM.getVM().isCompressedKlassPointersEnabled()) {
        return (Klass)Metadata.instantiateWrapperFor(handle.getCompKlassAddressAt(compressedKlass.getOffset()));
      } else {
        return (Klass)Metadata.instantiateWrapperFor(handle.getAddressAt(klass.getOffset()));
      }
    }