Method OptimizeGraph

tensorflow/core/grappler/optimizers/meta_optimizer.cc:429–583

}

Status MetaOptimizer::OptimizeGraph(Cluster* cluster, const GrapplerItem& item,
                                    GraphDef* optimized_graph) {
  int min_graph_nodes = cfg_.min_graph_nodes() == 0 ? kDefaultMinGraphNodes
                                                    : cfg_.min_graph_nodes();
  if (item.graph.node_size() < min_graph_nodes) {
    VLOG(3) << "Skipping optimization, graph has less than " << min_graph_nodes
            << " nodes.";
    *optimized_graph = item.graph;
    return Status::OK();
  }

  std::vector<std::unique_ptr<GraphOptimizer>> optimizers;
  if (cfg_.optimizers().empty()) {
    TF_RETURN_IF_ERROR(InitializeOptimizers(&optimizers));
  } else {
    TF_RETURN_IF_ERROR(InitializeOptimizersByName(&optimizers));
  }

  // Initialize the configured verifiers.
  std::vector<std::unique_ptr<GraphVerifier>> inter_optimizer_verifiers;
  std::vector<std::unique_ptr<GraphVerifier>> post_optimization_verifiers;
  InitializeVerifiers(&inter_optimizer_verifiers, &post_optimization_verifiers);
  if (inter_optimizer_verifiers.empty()) {
    VLOG(2) << "No inter optimizer verifiers have been configured";
  } else {
    VLOG(2) << inter_optimizer_verifiers.size()
            << " inter optimizer verifiers have been configured";
  }
  if (post_optimization_verifiers.empty()) {
    VLOG(2) << "No post optimization verifiers have been configured";
  } else {
    VLOG(2) << post_optimization_verifiers.size()
            << " post optimization verifiers have been configured";
  }

  VLOG(2) << "Optimize GrapplerItem: item.id=" << item.id
          << " num_optimizers=" << optimizers.size()
          << ", num nodes = " << item.graph.node_size();

  if (optimizers.empty()) {
    VLOG(3) << "Skipping graph optimization, no optimizers registered";
    *optimized_graph = item.graph;
    return Status::OK();
  }

  // Invariant: optimized_graph contains the most recently optimized version of
  // the graph.
  GrapplerItem optimized_item = item;
  optimized_graph->Swap(&optimized_item.graph);

  GraphOptimizationResult optimization_result(item.id);
  GraphOptimizer* sa_optimizer = nullptr;
  GraphOptimizer* multi_stream_optimizer = nullptr;

  // Constants in the graph are normally compressed after model_pruner.
  // Do it here if model pruner is disabled.
  if (cfg_.disable_model_pruning()) {
    CompressConstants(optimized_graph);