improve the implementation of the overload of =

source/tensor/XTensor.cpp

@@ -38,6 +38,7 @@
 #include "XMem.h"
 #include "XHeap.h"
 #include "XBLAS.h"
+#include "XName.h"
 #include "core/shape/MergeBlockLists.h"
 #include "core/movement/CopyValues.h"
 #include "core/arithmetic/Sum.h"
@@ -45,6 +46,7 @@
 #include "core/arithmetic/Sub.h"
 #include "core/arithmetic/Div.h"
 #include "core/math/ScaleAndShift.h"
+#include "function/Identity.h"
 
 #ifdef USE_CUDA
 
@@ -290,7 +292,8 @@ void XTensor::ShallowCopy(const XTensor &tensor)
 /* overloading of the equal-sign */
 XTensor& XTensor::operator= (const XTensor& tensor)
 {
-    /* we must make a hard copy of the tensor if it is the input 
+    
+    /* we must make a hard copy of the tensor if it is the input
        of another node. */
     if(outgo.tailNum > 0){
         int dims[MAX_TENSOR_DIM_NUM];
@@ -312,38 +315,54 @@ XTensor& XTensor::operator= (const XTensor& tensor)
         dataHost = NULL;
     }
 
-    /* hard copy of the data array */
-    int size = unitNum * unitSize;
-    if( isInit && !isSparse && !tensor.isSparse &&
-        size == tensor.unitNum * tensor.unitSize &&
-      ((devID < 0 && tensor.devID < 0) && devID == tensor.devID) &&
-        data != NULL)
-    {
-        XMemCopy(data, devID, tensor.data, tensor.devID, size);
-        if(dataHost != NULL && tensor.dataHost != NULL)
-            XMemCopy(dataHost, -1, tensor.dataHost, tensor.devID, size);
+    if(false && !tensor.isTmp){
+        /* NOTE: this might lead to additional data copy on Mac machines */
+        /* we make an identity transformation here */
+        
+        if(outgo.tailNum > 0)
+            XLink::ClearOutgoing(this);
+        XLink::ClearIncoming(this);
+        
+        if(!IsSameShaped(this, &tensor))
+            Resize(tensor.order, tensor.dimSize, tensor.dataType, tensor.denseRatio);
+        
+        _Identity(&tensor, this);
+        XLink::MakeLink(&tensor, NULL, this, FUNC_IDENTITY);
     }
     else{
-        DestroyData();
-        if(!isInit){
-            devID = tensor.devID;
-            mem = tensor.mem;
+        /* hard copy of the data array */
+        int size = unitNum * unitSize;
+        if( isInit && !isSparse && !tensor.isSparse &&
+            size == tensor.unitNum * tensor.unitSize &&
+          ((devID < 0 && tensor.devID < 0) && devID == tensor.devID) &&
+            data != NULL)
+        {
+            XMemCopy(data, devID, tensor.data, tensor.devID, size);
+            if(dataHost != NULL && tensor.dataHost != NULL)
+                XMemCopy(dataHost, -1, tensor.dataHost, tensor.devID, size);
         }
+        else{
+            DestroyData();
+            if(!isInit){
+                devID = tensor.devID;
+                mem = tensor.mem;
+            }
 
-        Resize(tensor.order, tensor.dimSize, tensor.dataType, tensor.denseRatio);
-        _CopyValues(&tensor, this);
-    }
+            Resize(tensor.order, tensor.dimSize, tensor.dataType, tensor.denseRatio);
+            _CopyValues(&tensor, this);
+        }
 
-    /* copy member variables */
-    ShallowCopy(tensor);
+        /* copy member variables */
+        ShallowCopy(tensor);
 
-    isInit = true;
-    isTmp  = false;
+        isInit = true;
+        isTmp  = false;
 
-    CheckNTErrors(outgo.tailNum == 0, "The node has outgoing edge to other nodes!");
+        CheckNTErrors(outgo.tailNum == 0, "The node has outgoing edge to other nodes!");
 
-    /* create tensor links for the new tensor */
-    XLink::Replace(&tensor, this);
+        /* create tensor links for the new tensor */
+        XLink::Replace(&tensor, this);
+    }
 
     return *this;
 }