1 files changed, 39 insertions, 0 deletions
diff --git a/tensorflow/contrib/lite/toco/tflite/operator.cc b/tensorflow/contrib/lite/toco/tflite/operator.cc
index ed37535fe0..e08a61d357 100644
--- a/tensorflow/contrib/lite/toco/tflite/operator.cc
+++ b/tensorflow/contrib/lite/toco/tflite/operator.cc
@@ -741,6 +741,42 @@ class Lstm : public BuiltinOperator<LstmCellOperator, ::tflite::LSTMOptions,
   }
 };
 
+class UnidirectionalSequenceLstm
+    : public BuiltinOperator<
+          UnidirectionalSequenceLstmOperator,
+          ::tflite::UnidirectionalSequenceLSTMOptions,
+          ::tflite::BuiltinOptions_UnidirectionalSequenceLSTMOptions> {
+ public:
+  using BuiltinOperator::BuiltinOperator;
+  flatbuffers::Offset<TfLiteOptions> WriteOptions(
+      const TocoOperator& op,
+      flatbuffers::FlatBufferBuilder* builder) const override {
+    // Current toco converter only supports tanh, no clip.
+    return ::tflite::CreateUnidirectionalSequenceLSTMOptions(
+        *builder, /*fused_activation_function=*/
+        ::tflite::ActivationFunctionType_TANH,
+        /*cell_clip=*/0.0,
+        /*proj_clip=*/0.0);
+  }
+
+  void ReadOptions(const TfLiteOptions& options,
+                   TocoOperator* op) const override {
+    // Only support tanh activation, so check that tflite type is tanh.
+    DCHECK(options.fused_activation_function() ==
+           ::tflite::ActivationFunctionType_TANH);
+  }
+
+  int GetVersion(const Operator& op) const override { return 1; }
+
+  std::vector<bool> GetMutatingInputVariables(
+      const Operator& op) const override {
+    std::vector<bool> mutating_input_variables(op.inputs.size(), false);
+    mutating_input_variables[kInputActivationStateTensor] = true;
+    mutating_input_variables[kInputCellStateTensor] = true;
+    return mutating_input_variables;
+  }
+};
+
 class Mean : public BuiltinOperator<MeanOperator, ::tflite::ReducerOptions,
                                     ::tflite::BuiltinOptions_ReducerOptions> {
  public:
@@ -1435,6 +1471,9 @@ std::vector<std::unique_ptr<BaseOperator>> BuildOperatorList(
                                       OperatorType::kFakeQuant));
   ops.push_back(
       MakeUnique<Pack>(::tflite::BuiltinOperator_PACK, OperatorType::kPack));
+  ops.emplace_back(MakeUnique<UnidirectionalSequenceLstm>(
+      ::tflite::BuiltinOperator_UNIDIRECTIONAL_SEQUENCE_LSTM,
+      OperatorType::kUnidirectionalSequenceLstm));
   ops.push_back(MakeUnique<OneHot>(::tflite::BuiltinOperator_ONE_HOT,
                                    OperatorType::kOneHot));
   ops.push_back(MakeUnique<Unpack>(::tflite::BuiltinOperator_UNPACK,