TEST_F(RematTest, RematExtendsInputAndRecreatesOutput) {
  r_.AddUse(/*ioperation=*/r_.AddOperation(/*is_stateful=*/false),
            /*itensor=*/r_.AddTensor(1));
  r_.AddUse(/*ioperation=*/r_.AddOperation(/*is_stateful=*/false),
            /*itensor=*/r_.AddTensor(100));
  r_.AddUse(/*ioperation=*/1, 0);
  r_.AddOperation(/*is_stateful=*/false);
  r_.AddOperation(/*is_stateful=*/false);

  // /* before: */
  // %0 = f1()

  // Returns a contiguous increasing index for each new object, starting at 0.
  int AddOperation(bool is_stateful);

  // The operator with index `ioperation` will be assumed to produce and/or
  // consume the tensor with index `itensor`. NoOp if that's already the case.
  // The arguments must be valid indices (i.e., obtained with
  // `AddOperation`/`AddTensor`).
  void AddUse(int ioperation, int itensor);

}

void Erase(const int item, std::vector<int>& items) {
  const auto [iter, found] = Find(item, items);
  if (found) items.erase(iter);
}

}  // namespace

int Rematerializer::AddOperation(const bool is_stateful) {
  operations_.emplace_back();
  operations_.back().is_stateful = is_stateful;
  return operations_.size() - 1;
}

int Rematerializer::AddTensor(const SizeT size) {