Add utility functions for integration. This supports the calibration case that the model is initialized multiple times.

(1) quatization_wrapper is the external interface to help calibration and quantization. The interface is string and bool so the dependencies are minimal. It has two functions:
- CreateCalibrationModel copies a model to a new location and adds intermediate tensors if any of the op need that.
- CreateQuantizedModel quantizes a model in place.

(2) quatization wrapper_utils is the helper function for quatization_wrapper
- added function to load model
- added function to write model

PiperOrigin-RevId: 280510873
Change-Id: I58891d6e8d6d3b485242f321466ac91ce2fdffda

tensorflow/lite/tools/optimize/BUILD

@@ -13,9 +13,9 @@ exports_files(glob([
 ]))
 
 cc_library(
-    name = "add_intermediate_tensors",
-    srcs = ["add_intermediate_tensors.cc"],
-    hdrs = ["add_intermediate_tensors.h"],
+    name = "quantization_wrapper_utils",
+    srcs = ["quantization_wrapper_utils.cc"],
+    hdrs = ["quantization_wrapper_utils.h"],
     deps = [
         ":operator_property",
         "//tensorflow/lite:framework",
@@ -26,14 +26,14 @@ cc_library(
 )
 
 tf_cc_test(
-    name = "add_intermediate_tensors_test",
-    srcs = ["add_intermediate_tensors_test.cc"],
+    name = "quantization_wrapper_utils_test",
+    srcs = ["quantization_wrapper_utils_test.cc"],
     tags = [
         "tflite_not_portable_android",
         "tflite_not_portable_ios",
     ],
     deps = [
-        ":add_intermediate_tensors",
+        ":quantization_wrapper_utils",
         "//tensorflow/lite:framework",
         "//tensorflow/lite/schema:schema_fbs",
         "@com_google_absl//absl/memory",
@@ -42,6 +42,20 @@ tf_cc_test(
     ],
 )
 
+cc_library(
+    name = "quantization_wrapper",
+    srcs = ["quantization_wrapper.cc"],
+    hdrs = ["quantization_wrapper.h"],
+    deps = [
+        ":quantization_wrapper_utils",
+        "//tensorflow/lite:framework",
+        "//tensorflow/lite/core/api",
+        "//tensorflow/lite/schema:schema_fbs",
+        "//tensorflow/lite/tools/optimize:quantize_model",
+        "@flatbuffers",
+    ],
+)
+
 cc_library(
     name = "quantization_utils",
     srcs = ["quantization_utils.cc"],

tensorflow/lite/tools/optimize/quantization_wrapper.cc

@@ -0,0 +1,52 @@
+/* Copyright 2019 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/lite/tools/optimize/quantization_wrapper.h"
+
+#include "tensorflow/lite/tools/optimize/quantization_wrapper_utils.h"
+#include "tensorflow/lite/tools/optimize/quantize_model.h"
+
+namespace tflite {
+namespace optimize {
+
+bool CreateModelForCalibration(const std::string& input_path,
+                               const std::string& output_path) {
+  ModelT model;
+  if (LoadModel(input_path, &model) != kTfLiteOk) {
+    return false;
+  }
+  flatbuffers::FlatBufferBuilder builder;
+  if (AddIntemediateTensorsToFusedOp(&builder, &model) != kTfLiteOk) {
+    return false;
+  }
+  return WriteFile(output_path, builder.GetBufferPointer(), builder.GetSize());
+}
+
+bool CreateQuantizedModel(const std::string& path) {
+  ModelT model;
+  if (LoadModel(path, &model) != kTfLiteOk) {
+    return false;
+  }
+  flatbuffers::FlatBufferBuilder builder;
+  tflite::StderrReporter error_reporter;
+  if (tflite::optimize::QuantizeModel(
+          &builder, &model, tflite::TensorType_FLOAT32,
+          tflite::TensorType_FLOAT32, &error_reporter) != kTfLiteOk) {
+    return false;
+  }
+  return WriteFile(path, builder.GetBufferPointer(), builder.GetSize());
+}
+
+}  // namespace optimize
+}  // namespace tflite

tensorflow/lite/tools/optimize/quantization_wrapper.h

@@ -0,0 +1,39 @@
+/* Copyright 2019 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.
+==============================================================================*/
+#ifndef TENSORFLOW_LITE_TOOLS_OPTIMIZE_QUANTIZATION_WRAPPER_H_
+#define TENSORFLOW_LITE_TOOLS_OPTIMIZE_QUANTIZATION_WRAPPER_H_
+
+#include <string>
+
+namespace tflite {
+namespace optimize {
+
+// Makes an copy of the model at input_path and writes it to output_path, adding
+// tensors to the model needed for calibration.
+// Returns true if it is successful.
+// Example: a/b/c.tflite becomes a/b/c.calibrated.tflite and has
+// intermediate tensors added according to operator properties.
+bool CreateModelForCalibration(const std::string& input_path,
+                               const std::string& output_path);
+
+// Quantize a model in place. This function is only to be called after calling
+// CreateModelForCalibration and running calibration over data.
+// Returns true if it is successful.
+bool CreateQuantizedModel(const std::string& path);
+
+}  // namespace optimize
+}  // namespace tflite
+
+#endif  // TENSORFLOW_LITE_TOOLS_OPTIMIZE_QUANTIZATION_WRAPPER_H_

tensorflow/lite/tools/optimize/quantization_wrapper_utils.cc

@@ -12,10 +12,12 @@ 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/lite/tools/optimize/add_intermediate_tensors.h"
+#include "tensorflow/lite/tools/optimize/quantization_wrapper_utils.h"
 
+#include <fstream>
 #include <memory>
 
+#include "tensorflow/lite/schema/schema_generated.h"
 #include "tensorflow/lite/tools/optimize/operator_property.h"
 
 namespace tflite {
@@ -51,6 +53,19 @@ bool IntermediateTensorExists(ModelT* model) {
 }
 }  // namespace
 
+TfLiteStatus LoadModel(const string& path, ModelT* model) {
+  auto input_model = FlatBufferModel::BuildFromFile(path.c_str());
+  if (!input_model) {
+    return kTfLiteError;
+  }
+  auto readonly_model = input_model->GetModel();
+  if (!readonly_model) {
+    return kTfLiteError;
+  }
+  readonly_model->UnPackTo(model);
+  return kTfLiteOk;
+}
+
 TfLiteStatus AddIntemediateTensorsToFusedOp(
     flatbuffers::FlatBufferBuilder* builder, ModelT* model) {
   // Return early if the model already has intermediate tensors.
@@ -90,5 +105,14 @@ TfLiteStatus AddIntemediateTensorsToFusedOp(
   return kTfLiteOk;
 }
 
+bool WriteFile(const std::string& out_file, const uint8_t* bytes,
+               size_t num_bytes) {
+  std::fstream stream(out_file, std::ios::binary | std::ios::out);
+  for (size_t i = 0; i < num_bytes; i++) {
+    stream << bytes[i];
+  }
+  return (!stream.bad() && !stream.fail());
+}
+
 }  // namespace optimize
 }  // namespace tflite

tensorflow/lite/tools/optimize/quantization_wrapper_utils.h

@@ -12,8 +12,8 @@ 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.
 ==============================================================================*/
-#ifndef TENSORFLOW_LITE_TOOLS_OPTIMIZE_ADD_INTERMEDIATE_TENSORS_H_
-#define TENSORFLOW_LITE_TOOLS_OPTIMIZE_ADD_INTERMEDIATE_TENSORS_H_
+#ifndef TENSORFLOW_LITE_TOOLS_OPTIMIZE_QUANTIZATION_WRAPPER_UTILS_H_
+#define TENSORFLOW_LITE_TOOLS_OPTIMIZE_QUANTIZATION_WRAPPER_UTILS_H_
 
 #include "tensorflow/lite/core/api/error_reporter.h"
 #include "tensorflow/lite/model.h"
@@ -22,13 +22,20 @@ limitations under the License.
 namespace tflite {
 namespace optimize {
 
+// Load a tflite model from path.
+TfLiteStatus LoadModel(const string& path, ModelT* model);
+
 // Going through the model and add intermediates tensors if the ops have any.
 // Returns early if the model has already intermediate tensors. This is to
 // support cases where a model is initialized multiple times.
 TfLiteStatus AddIntemediateTensorsToFusedOp(
-    flatbuffers::FlatBufferBuilder* builder, ModelT* input_model);
+    flatbuffers::FlatBufferBuilder* builder, ModelT* model);
+
+// Write model to a given location.
+bool WriteFile(const std::string& out_file, const uint8_t* bytes,
+               size_t num_bytes);
 
 }  // namespace optimize
 }  // namespace tflite
 
-#endif  // TENSORFLOW_LITE_TOOLS_OPTIMIZE_ADD_INTERMEDIATE_TENSORS_H_
+#endif  // TENSORFLOW_LITE_TOOLS_OPTIMIZE_QUANTIZATION_WRAPPER_UTILS_H_

tensorflow/lite/tools/optimize/quantization_wrapper_utils_test.cc

@@ -12,7 +12,7 @@ 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/lite/tools/optimize/add_intermediate_tensors.h"
+#include "tensorflow/lite/tools/optimize/quantization_wrapper_utils.h"
 
 #include <gmock/gmock.h>
 #include <gtest/gtest.h>