auto iter = op_to_parallel_ids_.find(op);
  if (iter != op_to_parallel_ids_.end()) branches = iter->second;
  return branches;
}

absl::flat_hash_set<Operation*> SideEffectAnalysisInfo::GetLastWrites(
    ResourceId resource_id) {
  PerResourceAccessInfo info = per_resource_access_info_[resource_id];
  absl::flat_hash_set<Operation*> last_writes;
  if (!info.reads_since_last_write.empty())

  // to a set of last accesses for use with other parallel ids. Reads/writes
  // between parallel ids are conservatively approximated as writes.
  absl::flat_hash_set<Operation*> GetLastWrites(ResourceId resource_id);

  // Sets the read/write state for ops within the same parallel id.
  void SetLastWrites(ResourceId resource_id,
                     absl::flat_hash_set<Operation*> last_writes);