!9285 Fix GPU stream assign bug that StreamSwitch node is not found.

From: @zpac
Reviewed-by: @kisnwang,@limingqi107
Signed-off-by: @limingqi107

mindspore/ccsrc/runtime/device/gpu/gpu_stream_assign.cc

@@ -71,28 +71,32 @@ bool FindAllReduceStreamSwitchPos(const std::shared_ptr<session::KernelGraph> &k
       std::vector<CNodePtr>::iterator mock_send_node_iter =
         FindSendNodePos(iter_begin, iter + 1, *iter, kAllReduceStreamSwitch);
       if (mock_send_node_iter == iter + 1) {
-        MS_LOG(WARNING) << "Can't find send node place before AllReduce node.";
-        continue;
-      }
-      if (AnfAlgo::GetCNodeName(*mock_send_node_iter) != kAllReduceOpName) {
+        MS_LOG(INFO) << "Can't find send node place before AllReduce node.";
+      } else if (AnfAlgo::GetCNodeName(*mock_send_node_iter) != kAllReduceOpName) {
         SendRecvPair pair1 = {kAllReduceStreamSwitch, *mock_send_node_iter, *iter,
                               IntToSize(mock_send_node_iter - iter_begin + 1), IntToSize(iter - iter_begin)};
         send_recv_pairs->push_back(pair1);
+      } else {
+        MS_LOG(INFO) << "mock_send_node is AllReduce, no need to add stream switch node.";
       }
       // Find node which uses AllReduce as input[0].
       std::vector<CNodePtr>::iterator mock_recv_node_iter =
         FindRecvNodePos(iter, iter_end, *iter, kAllReduceStreamSwitch);
       if (mock_recv_node_iter == iter_end) {
-        MS_LOG(WARNING) << "Can't find recv node place after AllReduce node.";
-        return false;
-      }
-      if (AnfAlgo::GetCNodeName(*mock_recv_node_iter) != kAllReduceOpName) {
+        MS_LOG(INFO) << "Can't find recv node place after AllReduce node.";
+      } else if (AnfAlgo::GetCNodeName(*mock_recv_node_iter) != kAllReduceOpName) {
         SendRecvPair pair2 = {kAllReduceStreamSwitch, *iter, *mock_recv_node_iter, IntToSize(iter - iter_begin + 1),
                               IntToSize(mock_recv_node_iter - iter_begin)};
         send_recv_pairs->push_back(pair2);
+      } else {
+        MS_LOG(INFO) << "mock_recv_node is AllReduce, no need to add stream switch node.";
       }
     }
   }
+  if (send_recv_pairs->empty()) {
+    MS_LOG(INFO) << "No stream switch node is found.";
+    return false;
+  }
   return true;
 }