// 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()));
      }
    }