[SYCL] Fix memory leak in piEnqueueEventsWaitWithBarrier with discarded output event (#7229)

Fix memory leak piEnqueueEventsWaitWithBarrier for the Level Zero
backend when output event is discarded. Take into account IsInternal
flag when creating an event which is used as the output event.

Author: againull

sycl/plugins/level_zero/pi_level_zero.cpp

@@ -6465,15 +6465,15 @@ pi_result piEnqueueEventsWaitWithBarrier(pi_queue Queue,
     }
   }
 
-  // Insert a barrier into each unique command queue using the available
-  // command-lists.
-  std::vector<pi_event> EventWaitVector(CmdLists.size());
-  for (size_t I = 0; I < CmdLists.size(); ++I)
-    if (auto Res = insertBarrierIntoCmdList(CmdLists[I], _pi_ze_event_list_t{},
-                                            EventWaitVector[I], false))
-      return Res;
-
   if (CmdLists.size() > 1) {
+    // Insert a barrier into each unique command queue using the available
+    // command-lists.
+    std::vector<pi_event> EventWaitVector(CmdLists.size());
+    for (size_t I = 0; I < CmdLists.size(); ++I)
+      if (auto Res = insertBarrierIntoCmdList(
+              CmdLists[I], _pi_ze_event_list_t{}, EventWaitVector[I], false))
+        return Res;
+
     // If there were multiple queues we need to create a "convergence" event to
     // be our active barrier. This convergence event is signalled by a barrier
     // on all the events from the barriers we have inserted into each queue.
@@ -6497,10 +6497,13 @@ pi_result piEnqueueEventsWaitWithBarrier(pi_queue Queue,
                                             *Event, IsInternal))
       return Res;
   } else {
-    // If there is only a single queue we have inserted all the barriers we need
-    // and the single result event can be used as our active barrier and used as
-    // the return event.
-    *Event = EventWaitVector[0];
+    PI_ASSERT(CmdLists.size() == 1, PI_ERROR_INVALID_QUEUE);
+    // If there is only a single queue then insert a barrier and the single
+    // result event can be used as our active barrier and used as the return
+    // event. Take into account whether output event is discarded or not.
+    if (auto Res = insertBarrierIntoCmdList(CmdLists[0], _pi_ze_event_list_t{},
+                                            *Event, IsInternal))
+      return Res;
   }
 
   // Execute each command list so the barriers can be encountered.