From a6ed8f268a80be33aa0de10a7e2812536bcab0f9 Mon Sep 17 00:00:00 2001
From: Dmitry Kurtaev <dmitry.kurtaev+github@gmail.com>
Date: Tue, 30 Apr 2019 19:18:41 +0300
Subject: [PATCH] Remove extra weights cloning from TensorFlow importer

---
 .../src/tensorflow/tf_graph_simplifier.cpp    | 28 +++++++++++--------
 .../src/tensorflow/tf_graph_simplifier.hpp    |  2 +-
 modules/dnn/src/tensorflow/tf_importer.cpp    |  4 +--
 3 files changed, 19 insertions(+), 15 deletions(-)

diff --git a/modules/dnn/src/tensorflow/tf_graph_simplifier.cpp b/modules/dnn/src/tensorflow/tf_graph_simplifier.cpp
index 7f1001888a..a40da7e174 100644
--- a/modules/dnn/src/tensorflow/tf_graph_simplifier.cpp
+++ b/modules/dnn/src/tensorflow/tf_graph_simplifier.cpp
@@ -747,43 +747,47 @@ void RemoveIdentityOps(tensorflow::GraphDef& net)
     }
 }
 
-Mat getTensorContent(const tensorflow::TensorProto &tensor)
+Mat getTensorContent(const tensorflow::TensorProto &tensor, bool copy)
 {
     const std::string& content = tensor.tensor_content();
+    Mat m;
     switch (tensor.dtype())
     {
         case tensorflow::DT_FLOAT:
         {
             if (!content.empty())
-                return Mat(1, content.size() / sizeof(float), CV_32FC1, (void*)content.c_str()).clone();
+                m = Mat(1, content.size() / sizeof(float), CV_32FC1, (void*)content.c_str());
             else
             {
                 const RepeatedField<float>& field = tensor.float_val();
                 CV_Assert(!field.empty());
-                return Mat(1, field.size(), CV_32FC1, (void*)field.data()).clone();
+                m = Mat(1, field.size(), CV_32FC1, (void*)field.data());
             }
+            break;
         }
         case tensorflow::DT_DOUBLE:
         {
             if (!content.empty())
-                return Mat(1, content.size() / sizeof(double), CV_64FC1, (void*)content.c_str()).clone();
+                m = Mat(1, content.size() / sizeof(double), CV_64FC1, (void*)content.c_str());
             else
             {
                 const RepeatedField<double>& field = tensor.double_val();
                 CV_Assert(!field.empty());
-                return Mat(1, field.size(), CV_64FC1, (void*)field.data()).clone();
+                m = Mat(1, field.size(), CV_64FC1, (void*)field.data());
             }
+            break;
         }
         case tensorflow::DT_INT32:
         {
             if (!content.empty())
-                return Mat(1, content.size() / sizeof(int32_t), CV_32SC1, (void*)content.c_str()).clone();
+                m = Mat(1, content.size() / sizeof(int32_t), CV_32SC1, (void*)content.c_str());
             else
             {
                 const RepeatedField<int32_t>& field = tensor.int_val();
                 CV_Assert(!field.empty());
-                return Mat(1, field.size(), CV_32SC1, (void*)field.data()).clone();
+                m = Mat(1, field.size(), CV_32SC1, (void*)field.data());
             }
+            break;
         }
         case tensorflow::DT_HALF:
         {
@@ -802,20 +806,20 @@ Mat getTensorContent(const tensorflow::TensorProto &tensor)
             }
             // Reinterpret as a signed shorts just for a convertFp16 call.
             Mat halfsSigned(halfs.size(), CV_16SC1, halfs.data);
-            Mat floats(halfs.size(), CV_32FC1);
-            convertFp16(halfsSigned, floats);
-            return floats;
+            convertFp16(halfsSigned, m);
+            break;
         }
         case tensorflow::DT_QUINT8:
         {
             CV_Assert(!content.empty());
-            return Mat(1, content.size(), CV_8UC1, (void*)content.c_str()).clone();
+            m = Mat(1, content.size(), CV_8UC1, (void*)content.c_str());
+            break;
         }
         default:
             CV_Error(Error::StsError, "Tensor's data type is not supported");
             break;
     }
-    return Mat();
+    return copy ? m.clone() : m;
 }
 
 void releaseTensor(tensorflow::TensorProto* tensor)
diff --git a/modules/dnn/src/tensorflow/tf_graph_simplifier.hpp b/modules/dnn/src/tensorflow/tf_graph_simplifier.hpp
index 5929d1f857..55f36cdb44 100644
--- a/modules/dnn/src/tensorflow/tf_graph_simplifier.hpp
+++ b/modules/dnn/src/tensorflow/tf_graph_simplifier.hpp
@@ -21,7 +21,7 @@ void RemoveIdentityOps(tensorflow::GraphDef& net);
 
 void simplifySubgraphs(tensorflow::GraphDef& net);
 
-Mat getTensorContent(const tensorflow::TensorProto &tensor);
+Mat getTensorContent(const tensorflow::TensorProto &tensor, bool copy = true);
 
 void releaseTensor(tensorflow::TensorProto* tensor);
 
diff --git a/modules/dnn/src/tensorflow/tf_importer.cpp b/modules/dnn/src/tensorflow/tf_importer.cpp
index a7a681c140..8acaaf8f7a 100644
--- a/modules/dnn/src/tensorflow/tf_importer.cpp
+++ b/modules/dnn/src/tensorflow/tf_importer.cpp
@@ -109,7 +109,7 @@ void parseTensor(const tensorflow::TensorProto &tensor, Mat &dstBlob)
 
     dstBlob.create(shape, CV_32F);
 
-    Mat tensorContent = getTensorContent(tensor);
+    Mat tensorContent = getTensorContent(tensor, /*no copy*/false);
     int size = tensorContent.total();
     CV_Assert(size == (int)dstBlob.total());
 
@@ -509,7 +509,7 @@ void TFImporter::kernelFromTensor(const tensorflow::TensorProto &tensor, Mat &ds
 
     dstBlob.create(shape, CV_32F);
 
-    Mat tensorContent = getTensorContent(tensor);
+    Mat tensorContent = getTensorContent(tensor, /*no copy*/false);
     int size = tensorContent.total();
     CV_Assert(size == (int)dstBlob.total());