while_op.getInput());
      }
      return;
    }
    if (auto while_op = dyn_cast<TF::WhileRegionOp>(op)) {
      PropagatePotentiallyWrittenUpFromCallee(while_op.getCond(),
                                              while_op.getInput());
      PropagatePotentiallyWrittenUpFromCallee(while_op.getBody(),
                                              while_op.getInput());
      return;