private static boolean isTrivialStackAssignment(Exprent first) {
    if (first.type == Exprent.EXPRENT_ASSIGNMENT) {
      AssignmentExprent asf = (AssignmentExprent)first;

      if (asf.getLeft().type == Exprent.EXPRENT_VAR && asf.getRight().type == Exprent.EXPRENT_VAR) {
        VarExprent left = (VarExprent)asf.getLeft();
        VarExprent right = (VarExprent)asf.getRight();
        return left.getIndex() == right.getIndex() && left.isStack() && right.isStack();
      }
    }

    return false;
  }
private static boolean isTrivialStackAssignment(Exprent first)