1 files changed, 63 insertions, 0 deletions
diff --git a/tensorflow/contrib/lite/toco/graph_transformations/resolve_tensorflow_merge.cc b/tensorflow/contrib/lite/toco/graph_transformations/resolve_tensorflow_merge.cc
new file mode 100644
index 0000000000..cfa5ce0716
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+++ b/tensorflow/contrib/lite/toco/graph_transformations/resolve_tensorflow_merge.cc
@@ -0,0 +1,63 @@
+/* Copyright 2017 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 <memory>
+#include <string>
+#include <unordered_map>
+#include <vector>
+
+#include "tensorflow/contrib/lite/toco/graph_transformations/graph_transformations.h"
+#include "tensorflow/contrib/lite/toco/model.h"
+#include "tensorflow/contrib/lite/toco/tooling_util.h"
+#include "tensorflow/core/platform/logging.h"
+
+namespace toco {
+
+bool ResolveTensorFlowMerge::Run(Model* model, std::size_t op_index) {
+  const auto merge_it = model->operators.begin() + op_index;
+  const auto* merge_op = merge_it->get();
+  if (merge_op->type != OperatorType::kTensorFlowMerge) {
+    return false;
+  }
+
+  // We need to yield until this Merge node has only 1 input, which will mean
+  // that that is the selected input. Other graph transformations on other nodes
+  // such as ResolveTensorFlowSwitch, will take care of trimming the
+  // non-selected inputs, so that at some point there will be only 1 input left.
+  if (merge_op->inputs.size() > 1) {
+    AddMessageF("Waiting for %s to be resolved", LogName(*merge_op));
+    return false;
+  }
+
+  // Now that the merge node has 1 input exactly, it is the same as an Identity
+  // node and can be resolved trivially.
+  CHECK_EQ(merge_op->inputs.size(), 1);
+
+  // Update the edges of the graph ahead of removing the node.
+  for (const auto& other_op : model->operators) {
+    for (auto& input : other_op->inputs) {
+      if (input == merge_op->outputs[0]) {
+        input = merge_op->inputs[0];
+      }
+    }
+  }
+
+  // Remove the node and its output array.
+  AddMessageF("Removing already-resolved %s", LogName(*merge_op));
+  model->arrays.erase(merge_op->outputs[0]);
+  model->operators.erase(merge_it);
+  return true;
+}
+
+}  // namespace toco