/** Returns a copy of the current operand. */
 public Operand copy() {
   RegisterOperand newBase = (base != null) ? (RegisterOperand) base.copy() : null;
   RegisterOperand newIndex = (index != null) ? (RegisterOperand) index.copy() : null;
   LocationOperand newLoc = (loc != null) ? (LocationOperand) loc.copy() : null;
   Operand newGuard = (guard != null) ? guard.copy() : null;
   return new MemoryOperand(newBase, newIndex, scale, disp, size, newLoc, newGuard);
 }