public static void initializeHeader(VM_Address ref, Object[] tib, int size, boolean isScalar)
public static void initializeHeader(VM_Address ref, Object[] tib, int size)
  public static void initializeHeader(VM_Address ref, Object[] tib, int size,                                      boolean isScalar)    throws VM_PragmaUninterruptible, VM_PragmaInline {    VM_Word oldValue = VM_Interface.readAvailableBitsWord(VM_Magic.objectAsAddress(ref));    VM_Word newValue = oldValue.and(GC_BITS_MASK.not()).or(Plan.getInitialHeaderValue(size));    VM_Interface.writeAvailableBitsWord(VM_Magic.objectAsAddress(ref),newValue);  }