1 files changed, 81 insertions, 0 deletions
diff --git a/tensorflow/contrib/lite/toco/graph_transformations/convert_trivial_pack_to_reshape.cc b/tensorflow/contrib/lite/toco/graph_transformations/convert_trivial_pack_to_reshape.cc
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index 0000000000..75113a2a8c
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+++ b/tensorflow/contrib/lite/toco/graph_transformations/convert_trivial_pack_to_reshape.cc
@@ -0,0 +1,81 @@
+/* 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 <memory>
+#include <string>
+#include <unordered_map>
+#include <vector>
+
+#include "absl/strings/str_cat.h"
+#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 ConvertTrivialPackToReshape::Run(Model* model, std::size_t op_index) {
+  auto pack_it = model->operators.begin() + op_index;
+  if (pack_it->get()->type != OperatorType::kPack) {
+    return false;
+  }
+  auto* pack_op = static_cast<PackOperator*>(pack_it->get());
+  if (pack_op->inputs.size() > 1) {
+    // Not trivial.
+    return false;
+  }
+  CHECK_EQ(pack_op->outputs.size(), 1);
+
+  const auto& input_array = model->GetArray(pack_op->inputs[0]);
+  if (!input_array.has_shape()) {
+    // Yield until input dims have been resolved.
+    return false;
+  }
+  if (input_array.shape().dimensions_count() == 0) {
+    // Input array cannot be 0-D.
+    // (Unsure if this is TF behavior, but was required to get a test to pass.)
+    return false;
+  }
+
+  AddMessageF("Converting trivial %s to a reshape", LogName(*pack_op));
+
+  // Note that we could convert to ExpandDims but toco prefers reshapes.
+  auto* reshape_op = new TensorFlowReshapeOperator;
+  reshape_op->inputs = {pack_op->inputs[0]};
+  reshape_op->outputs = pack_op->outputs;
+
+  // Create shape param.
+  string shape_array_name =
+      AvailableArrayName(*model, pack_op->outputs[0] + "_shape");
+  Array& shape_array = model->GetOrCreateArray(shape_array_name);
+  *(shape_array.mutable_shape()->mutable_dims()) = {
+      1 + input_array.shape().dimensions_count()};
+  reshape_op->inputs.push_back(shape_array_name);
+  shape_array.data_type = ArrayDataType::kInt32;
+  auto& shape_buffer = shape_array.GetMutableBuffer<ArrayDataType::kInt32>();
+  shape_buffer.data.push_back(1);
+  for (int dim : input_array.shape().dims()) {
+    shape_buffer.data.push_back(dim);
+  }
+
+  // Replace the operator in the graph.
+  const auto reshape_it = model->operators.emplace(pack_it, reshape_op);
+  pack_it = reshape_it + 1;
+  CHECK_EQ(pack_it->get(), pack_op);
+  model->operators.erase(pack_it);
+
+  return true;
+}
+
+}  // namespace toco