src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/utilities/MarkBits.java

*** 39,50 ****
      MemRegion reserved = heap.reservedRegion();
      // Must cover "reserved" with one bit for each OopHandle
      start = reserved.start();
      end   = reserved.end();
      long numOopHandles = end.minus(start) / VM.getVM().getOopSize();
!     // FIXME: will have trouble with larger heap sizes
!     bits = new BitMap((int) numOopHandles);
    }
  
    public void clear() {
      bits.clear();
    }
--- 39,49 ----
      MemRegion reserved = heap.reservedRegion();
      // Must cover "reserved" with one bit for each OopHandle
      start = reserved.start();
      end   = reserved.end();
      long numOopHandles = end.minus(start) / VM.getVM().getOopSize();
!     bits = heap.createBitMap(numOopHandles);
    }
  
    public void clear() {
      bits.clear();
    }
*** 58,93 ****
        System.err.println("MarkBits: WARNING: null object, ignoring");
        return false;
      }
  
      OopHandle handle = obj.getHandle();
-     // FIXME: will have trouble with larger heap sizes
      long idx = handle.minus(start) / VM.getVM().getOopSize();
!     if ((idx < 0) || (idx >= bits.size())) {
!       System.err.println("MarkBits: WARNING: object " + handle + " outside of heap, ignoring");
!       return false;
!     }
!     int intIdx = (int) idx;
!     if (bits.at(intIdx)) {
        return false; // already marked
      }
!     bits.atPut(intIdx, true);
      return true;
    }
  
    /** Forces clearing of a given mark bit. */
    public void clear(Oop obj) {
      OopHandle handle = obj.getHandle();
-     // FIXME: will have trouble with larger heap sizes
      long idx = handle.minus(start) / VM.getVM().getOopSize();
!     if ((idx < 0) || (idx >= bits.size())) {
!       System.err.println("MarkBits: WARNING: object " + handle + " outside of heap, ignoring");
!       return;
!     }
!     int intIdx = (int) idx;
!     bits.atPut(intIdx, false);
    }
  
!   private BitMap  bits;
    private Address start;
    private Address end;
  }
--- 57,80 ----
        System.err.println("MarkBits: WARNING: null object, ignoring");
        return false;
      }
  
      OopHandle handle = obj.getHandle();
      long idx = handle.minus(start) / VM.getVM().getOopSize();
!     if (bits.at(idx)) {
        return false; // already marked
      }
!     bits.atPut(idx, true);
      return true;
    }
  
    /** Forces clearing of a given mark bit. */
    public void clear(Oop obj) {
      OopHandle handle = obj.getHandle();
      long idx = handle.minus(start) / VM.getVM().getOopSize();
!     bits.atPut(idx, false);
    }
  
!   private BitMapInterface bits;
    private Address start;
    private Address end;
  }