!7941 fix pynative grad error

From: @kisnwang
Reviewed-by: @jjfeing,@chujinjin
Signed-off-by: @jjfeing

mindspore/ccsrc/backend/session/session_basic.cc

@@ -999,16 +999,16 @@ void SessionBasic::LoadInputData(const std::shared_ptr<KernelGraph> &kernel_grap
     MS_EXCEPTION_IF_NULL(input_node);
     if (input_node->isa<Parameter>() && AnfAlgo::OutputAddrExist(input_node, 0) && TensorNeedSync(input_node, tensor)) {
       auto device_address = AnfAlgo::GetMutableOutputAddr(input_node, 0);
-      if (ms_context->get_param<int>(MS_CTX_EXECUTION_MODE) == kPynativeMode ||
-          AnfAlgo::IsParameterWeight(input_node->cast<ParameterPtr>())) {
-        tensor->set_device_address(device_address);
-      }
       MS_EXCEPTION_IF_NULL(device_address);
       if (!device_address->SyncHostToDevice(trans::GetRuntimePaddingShape(input_node, 0),
                                             LongToSize(tensor->data().nbytes()), tensor->data_type(),
                                             tensor->data_c())) {
         MS_LOG(EXCEPTION) << "SyncHostToDevice failed.";
       }
+      if (ms_context->get_param<int>(MS_CTX_EXECUTION_MODE) == kPynativeMode ||
+          AnfAlgo::IsParameterWeight(input_node->cast<ParameterPtr>())) {
+        tensor->set_device_address(device_address);
+      }
     }
     tensor->set_sync_status(kNoNeedSync);
   }

mindspore/core/ir/tensor.cc

@@ -581,7 +581,8 @@ void Tensor::data_sync(bool need_wait) const {
   if (device_sync_ == nullptr) {
     return;
   }
-  if (!device_sync_->SyncDeviceToHost(shape(), static_cast<size_t>(data().nbytes()), data_type(), data_c())) {
+  auto address = device_sync_;
+  if (!address->SyncDeviceToHost(shape(), static_cast<size_t>(data().nbytes()), data_type(), data_c())) {
     MS_LOG(EXCEPTION) << "SyncDeviceToHost failed.";
   }
   sync_status_ = kNeedSyncHostToDevice;