1 files changed, 67 insertions, 0 deletions
diff --git a/tensorflow/compiler/tf2xla/side_effect_util.cc b/tensorflow/compiler/tf2xla/side_effect_util.cc
new file mode 100644
index 0000000000..6cd7b24592
--- /dev/null
+++ b/tensorflow/compiler/tf2xla/side_effect_util.cc
@@ -0,0 +1,67 @@
+/* Copyright 2018 The TensorFlow Authors. All Rights Reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+==============================================================================*/
+
+#include "tensorflow/compiler/tf2xla/side_effect_util.h"
+
+#include "tensorflow/core/graph/algorithm.h"
+
+namespace tensorflow {
+
+const char kXlaTokenInputNodesAttrName[] = "_xla_token_input_nodes";
+
+const char kXlaTokenArgNodeName[] = "_xla_token_arg_node";
+
+std::set<std::string> CalculateTokenInputsForOutputToken(const Graph& g) {
+  std::set<std::string> results;
+  Node* first_side_effecting_node_on_path = nullptr;
+  ReverseDFS(g,
+             [&](Node* n) {
+               std::vector<string> token_input_nodes;
+               if (!GetNodeAttr(n->attrs(), kXlaTokenInputNodesAttrName,
+                                &token_input_nodes)
+                        .ok() ||
+                   token_input_nodes.empty()) {
+                 return;
+               }
+
+               if (first_side_effecting_node_on_path != nullptr) {
+                 return;
+               }
+
+               first_side_effecting_node_on_path = n;
+               results.insert(n->name());
+             },
+             [&](Node* n) {
+               if (first_side_effecting_node_on_path == n) {
+                 first_side_effecting_node_on_path = nullptr;
+               }
+             },
+             NodeComparatorName());
+  return results;
+}
+
+bool HasSideEffectingNodes(const Graph& g) {
+  for (Node* n : g.nodes()) {
+    std::vector<string> token_input_nodes;
+    if (GetNodeAttr(n->attrs(), kXlaTokenInputNodesAttrName, &token_input_nodes)
+            .ok() &&
+        !token_input_nodes.empty()) {
+      return true;
+    }
+  }
+  return false;
+}
+
+}  // namespace tensorflow