1 files changed, 20 insertions, 4 deletions
diff --git a/offload/liboffload/src/OffloadImpl.cpp b/offload/liboffload/src/OffloadImpl.cpp
index 6486b2b..272a12a 100644
--- a/offload/liboffload/src/OffloadImpl.cpp
+++ b/offload/liboffload/src/OffloadImpl.cpp
@@ -72,6 +72,8 @@ struct ol_queue_impl_t {
 struct ol_event_impl_t {
   ol_event_impl_t(void *EventInfo, ol_queue_handle_t Queue)
       : EventInfo(EventInfo), Queue(Queue) {}
+  // EventInfo may be null, in which case the event should be considered always
+  // complete
   void *EventInfo;
   ol_queue_handle_t Queue;
 };
@@ -509,8 +511,8 @@ Error olWaitEvents_impl(ol_queue_handle_t Queue, ol_event_handle_t *Events,
       return Plugin::error(ErrorCode::INVALID_NULL_HANDLE,
                            "olWaitEvents asked to wait on a NULL event");
 
-    // Do nothing if the event is for this queue
-    if (Event->Queue == Queue)
+    // Do nothing if the event is for this queue or the event is always complete
+    if (Event->Queue == Queue || !Event->EventInfo)
       continue;
 
     if (auto Err = Device->waitEvent(Event->EventInfo, Queue->AsyncInfo))
@@ -548,6 +550,10 @@ Error olGetQueueInfoSize_impl(ol_queue_handle_t Queue, ol_queue_info_t PropName,
 }
 
 Error olSyncEvent_impl(ol_event_handle_t Event) {
+  if (!Event->EventInfo)
+    // Event always complete
+    return Plugin::success();
+
   if (auto Res = Event->Queue->Device->Device->syncEvent(Event->EventInfo))
     return Res;
 
@@ -555,8 +561,9 @@ Error olSyncEvent_impl(ol_event_handle_t Event) {
 }
 
 Error olDestroyEvent_impl(ol_event_handle_t Event) {
-  if (auto Res = Event->Queue->Device->Device->destroyEvent(Event->EventInfo))
-    return Res;
+  if (Event->EventInfo)
+    if (auto Res = Event->Queue->Device->Device->destroyEvent(Event->EventInfo))
+      return Res;
 
   return olDestroy(Event);
 }
@@ -590,7 +597,16 @@ Error olGetEventInfoSize_impl(ol_event_handle_t Event, ol_event_info_t PropName,
 }
 
 Error olCreateEvent_impl(ol_queue_handle_t Queue, ol_event_handle_t *EventOut) {
+  auto Pending = Queue->Device->Device->hasPendingWork(Queue->AsyncInfo);
+  if (auto Err = Pending.takeError())
+    return Err;
+
   *EventOut = new ol_event_impl_t(nullptr, Queue);
+  if (!*Pending)
+    // Queue is empty, don't record an event and consider the event always
+    // complete
+    return Plugin::success();
+
   if (auto Res = Queue->Device->Device->createEvent(&(*EventOut)->EventInfo))
     return Res;