absl::flat_hash_map<int32_t, const tflite::OperatorT*> defining_op;
  for (const auto& op : subgraph.operators) {
    for (int32_t output : op->outputs) {
      if (!llvm::is_contained(input_indices, output)) {
        defining_op[output] = op.get();
      }
    }
  }

  std::vector<const tflite::OperatorT*> queue;
  for (int32_t output : output_indices) {