Method InitializeNode

tensorflow/core/common_runtime/graph_view.cc:122–243

}

char* GraphView::InitializeNode(char* ptr, const Node* n) {
  const int id = n->id();
  CHECK(node_offsets_[id] == kuint32max);  // Initial value in constructor

  const size_t bytes = NodeItemBytes(n);
  constexpr size_t kItemAlignment = sizeof(NodeItem*);
  CHECK_EQ(reinterpret_cast<uintptr_t>(ptr) % kItemAlignment, 0);
  NodeItem* item = reinterpret_cast<NodeItem*>(ptr);

  // We store a 32-bit offset relative to the beginning of space_, so that we
  // only need an array of 32-bit values to map from node id to the NodeItem*,
  // (versus 64 bits on most machines if we just stored an array of NodeItem*
  // pointers). Casting to int64 is needed on 32bit CPU to avoid comparing
  // values as "int" vs "size_t" in CHECK_LE.
  CHECK_LE(static_cast<int64_t>(ptr - space_), kuint32max);
  const uint32 offset = static_cast<uint32>(ptr - space_);
  node_offsets_[id] = offset;
  ptr += bytes;

  int32_t num_output_edges;
  int32_t num_output_control_edges;
  std::tie(num_output_edges, num_output_control_edges) = CountOutputEdges(n);
  const int num_inputs = n->num_inputs();
  const int num_outputs = n->num_outputs();

  new (item) NodeItem();
  item->num_inputs = num_inputs;
  item->num_outputs = num_outputs;
  item->num_output_edges = num_output_edges;
  item->num_output_control_edges = num_output_control_edges;

  // Fill output edges.
  // Keep track of the last EdgeInfo in the EdgeInfo array that references
  // a given output slot.  For all but the last, we need to do a copy of the
  // Tensor when propagating results downstream in the graph, but for the
  // last one, we can just do a move of the Tensor object to propagate it.
  gtl::InlinedVector<EdgeInfo*, 4> last_indices(num_outputs, nullptr);
  EdgeInfo* dst_edge = item->output_edge_base();
  for (auto e : n->out_edges()) {
    if (e->IsControlEdge()) continue;
    dst_edge->dst_id = e->dst()->id();
    CHECK_LE(e->src_output(), 0x3FFFFFFF);  // Must fit in 31 bits
    dst_edge->output_slot = e->src_output();
    dst_edge->is_last = false;
    const int output_slot = dst_edge->output_slot;
    if (output_slot >= 0) {
      last_indices[output_slot] = dst_edge;
    }
    // NOTE: The `input_slot` will be rewritten to the frame-wide offset later
    // in `ExecutorImpl::Initialize()`.
    dst_edge->input_slot = e->dst_input();
    dst_edge++;
  }
  for (EdgeInfo* edge_info : last_indices) {
    if (edge_info != nullptr) {
      edge_info->is_last = true;
    }
  }