Remove extra weights cloning from TensorFlow importer

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, m);
-            convertFp16(halfsSigned, floats);
+            break;
-            return floats;
         }
         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)

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);
 

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());