using deadness_analysis_internal::ComputePredicates;
using deadness_analysis_internal::PredicateMapTy;

Status AnalyzeDeadness(Graph* graph,
                       std::unique_ptr<DeadnessAnalysis>* result) {
  FixupSourceAndSinkEdges(graph);
  return DeadnessAnalysis::Run(*graph, result);
}

ops::Switch CreateSwitch(const Scope& root, const string& prefix) {
  Output value = ops::Placeholder(root.WithOpName(prefix + "/value"), DT_FLOAT);

  Scope root = Scope::NewRootScope().ExitOnError();

  Node* read = MakeRead(root, "R");
  Node* write = MakeWrite(root, "W");

  root.graph()->AddControlEdge(read, write);

  FixupSourceAndSinkEdges(root.graph());
  std::unique_ptr<Graph> graph(new Graph(OpRegistry::Global()));
  TF_EXPECT_OK(root.ToGraph(graph.get()));
  TF_ASSERT_OK(MarkForCompilationPassTestHelper::MarkForCompilation(&graph));

  TF_RETURN_IF_ERROR(CopySubgraphEdges(node_images, &src_arg_pairs));
  MarkGuaranteedConstants(*graph_in_, src_arg_pairs);

  for (auto& entry : subgraphs_) {
    Subgraph& subgraph = entry.second;
    FixupSourceAndSinkEdges(subgraph.GetGraph());
  }

  if (VLOG_IS_ON(1)) {
    // Dump subgraphs.
    for (auto& entry : subgraphs_) {
      DumpGraphToFile(

  // connected but sometimes the incoming graph does not follow this invariant.
  // So fix up the source and sink edges before calling into deadness analysis.
  FixupSourceAndSinkEdges(graph);

  for (Node* n : graph->nodes()) {
    // See explanation on `kXlaAlreadyClustered`.
    if (n->attrs().Find(kXlaAlreadyClustered)) {
      return absl::OkStatus();
    }