// Dumps the MLIR module to disk.
// This require the TF_DUMP_GRAPH_PREFIX to be set to a path that exist (or can
// be created).
static void DumpModule(mlir::ModuleOp module, std::string file_prefix) {
  std::string prefix = GetDumpDirFromEnvVar();
  if (prefix.empty()) return;

  auto* env = tensorflow::Env::Default();
  auto status = env->RecursivelyCreateDir(prefix);
  if (!status.ok()) {
    LOG(WARNING) << "cannot create directory '" << prefix