// Whenever we find an Identity op that is unqualified, we remove this Identity
// op from the list `tpu_ops`. An unqualified Identity op indicates either its
// inputs or its outputs do not belong to the same cluster.
bool ExcludeIdentityOp(llvm::SmallDenseSet<Operation*>& tpu_ops,
                       llvm::StringRef& target_cluster_name, bool incoming) {
  for (auto iter = tpu_ops.begin(); iter != tpu_ops.end(); iter++) {