if (rw.getNumResults() != 1 || rw.getInputs().size() != 1 ||
        rw.getInitValues().size() != 1)
      return failure();

    if (failed(MatchBinaryReduceFunction<BinaryOp>(rw.getBody())))
      return failure();

    // Ensure that initial_values are as expected.
    auto const_op = llvm::dyn_cast_or_null<mhlo::ConstantOp>(
        rw.getInitValues()[0].getDefiningOp());
    if (!const_op) return failure();

  const auto &inputs_ty = op.getInputs().getType();
  int n_inputs = inputs_ty.size();
  if (n_inputs < 1) return op.emitOpError() << "No inputs";

  const auto &init_values_ty = op.getInitValues().getType();
  int n_init_values = init_values_ty.size();
  if (n_init_values != n_inputs) {
    return op.emitOpError() << "Number of inputs (" << n_inputs