1 files changed, 87 insertions, 0 deletions
diff --git a/tensorflow/contrib/lite/toco/graph_transformations/remove_trivial_quantized_activation_func.cc b/tensorflow/contrib/lite/toco/graph_transformations/remove_trivial_quantized_activation_func.cc
new file mode 100644
index 0000000000..28f76c9d36
--- /dev/null
+++ b/tensorflow/contrib/lite/toco/graph_transformations/remove_trivial_quantized_activation_func.cc
@@ -0,0 +1,87 @@
+/* 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 <vector>
+
+#include "tensorflow/contrib/lite/toco/graph_transformations/graph_transformations.h"
+#include "tensorflow/contrib/lite/toco/model.h"
+#include "tensorflow/contrib/lite/toco/runtime/types.h"
+#include "tensorflow/contrib/lite/toco/toco_types.h"
+#include "tensorflow/contrib/lite/toco/tooling_util.h"
+#include "tensorflow/core/platform/logging.h"
+
+namespace toco {
+
+bool RemoveTrivialQuantizedActivationFunc::Run(Model* model,
+                                               std::size_t op_index) {
+  const auto it = model->operators.begin() + op_index;
+  auto* op = it->get();
+  if (op->fused_activation_function != FusedActivationFunctionType::kRelu &&
+      op->fused_activation_function != FusedActivationFunctionType::kRelu6) {
+    return false;
+  }
+  const auto& output_array = model->GetArray(op->outputs[0]);
+  if (!output_array.quantization_params) {
+    return false;
+  }
+  if (output_array.data_type != ArrayDataType::kUint8) {
+    return false;
+  }
+  const auto& quantization_params = output_array.GetQuantizationParams();
+
+  bool has_nontrivial_min_bound = false;
+  bool has_nontrivial_max_bound = false;
+
+  if (op->fused_activation_function == FusedActivationFunctionType::kRelu ||
+      op->fused_activation_function == FusedActivationFunctionType::kRelu6) {
+    double lowest_representable_output =
+        (0. - quantization_params.zero_point) * quantization_params.scale;
+    if (lowest_representable_output < 0.) {
+      has_nontrivial_min_bound = true;
+      AddMessageF(
+          "Quantized activation function is not trivial: "
+          "the lowest representable output value %g"
+          " less than the clamp min bound.",
+          lowest_representable_output);
+    }
+  }
+  if (op->fused_activation_function == FusedActivationFunctionType::kRelu6) {
+    double highest_representable_output =
+        (255. - quantization_params.zero_point) * quantization_params.scale;
+    if (highest_representable_output > 6.) {
+      has_nontrivial_max_bound = true;
+      AddMessageF(
+          "Quantized activation function is not trivial: "
+          "the highest representable output value %g"
+          " is greater than the clamp max bound.",
+          highest_representable_output);
+    }
+  }
+
+  if (has_nontrivial_min_bound || has_nontrivial_max_bound) {
+    return false;
+  }
+
+  op->fused_activation_function = FusedActivationFunctionType::kNone;
+  AddMessageF(
+      "Removing trivial quantized activation function on %s"
+      " because the output quantization parameters imply at least as tight"
+      " a clamp anyway.",
+      LogName(*op));
+  return true;
+}
+
+}  // namespace toco