Many algorithms need to enumerate the set of nodes within a graph, while excluding the special Sink and Source nodes. The checks for skipping Source and Sink are duplicated in dozens of loops.

This CL adds a new Graph::op_nodes() method, which returns an enumerable range of all operation nodes, excluding Sink and Source.  This allows many for loops to be simplified.

This simplification is being done mainly for readability / reliability.  There may be a tiny performance difference owing to this change (as well as making the Graph::nodes() and Graph::op_nodes() methods inlineable), but the measured difference is not reliably large enough to be significant.

The changes to graph.h and graph.cc are quite minimal.  I updated all of the uses of Graph::nodes() that I could reliably determine were unaffected by the change.  Most uses immediately checked node->IsOp().  Some compared node->type_string() against literal strings, none of which were "_SINK" or "_SOURCE", and so using op_nodes() was more appropriate than nodes().  In some cases, it was not obvious whether an existing use of Graph::node() wanted to enumerate Sink / Source, so I left those uses unaffected.

PiperOrigin-RevId: 156782112

1 files changed, 0 insertions, 6 deletions

diff --git a/tensorflow/core/graph/graph.cc b/tensorflow/core/graph/graph.cc
index 9066de5668..80161ceb56 100644
--- a/tensorflow/core/graph/graph.cc
+++ b/tensorflow/core/graph/graph.cc
@@ -488,12 +488,6 @@ string Graph::NewName(StringPiece prefix) {
   return strings::StrCat(prefix, "/_", name_counter_++);
 }
 
-gtl::iterator_range<NodeIter> Graph::nodes() const {
-  // Note that NodeId 0 is always valid since we don't let the source
-  // node be removed from the graph.
-  return gtl::make_range(NodeIter(this, 0), NodeIter(this, num_node_ids()));
-}
-
 bool Graph::IsValidNode(Node* node) const {
   if (node == nullptr) return false;
   const int id = node->id();