// result types. This is only done for the While op for now.
    llvm::SmallVector<Type, 4> element_types;
    int64_t num_results = op.getNumResults();
    if constexpr (std::is_same<DstOpT, mhlo::WhileOp>::value) {
      element_types.reserve(num_results);
      for (Value value : adaptor.getOperands()) {
        element_types.push_back(getElementTypeOrSelf(value.getType()));
      }
    }

        pack_op.getValuesCount() != input_unpack_op.getNum())
      return failure();

    const int total_pack_inputs = pack_op.getNumOperands();
    const int num_results = input_unpack_op.getNumResults();
    if (total_pack_inputs != num_results) return failure();
    for (auto input_output :
         llvm::zip(pack_op.getOperands(), input_unpack_op.getResults())) {
      Value pack_input = std::get<0>(input_output);