[SYCL][NFC] Reduce ambiguity between discarding SYCL and PI events

sycl/source/detail/queue_impl.cpp

@@ -354,7 +354,7 @@ event queue_impl::submitMemOpHelper(const std::shared_ptr<queue_impl> &Self,
         getExtendDependencyList(DepEvents, MutableDepEvents, Lock);
 
     if (areEventsSafeForSchedulerBypass(ExpandedDepEvents, MContext)) {
-      if (MHasDiscardEventsSupport) {
+      if (MSupportsDiscardingPiEvents) {
         MemOpFunc(MemOpArgs..., getPIEvents(ExpandedDepEvents),
                   /*PiEvent*/ nullptr, /*EventImplPtr*/ nullptr);
         return createDiscardedEvent();

sycl/source/detail/queue_impl.hpp

@@ -113,8 +113,8 @@ class queue_impl {
         MDiscardEvents(
             has_property<ext::oneapi::property::queue::discard_events>()),
         MIsProfilingEnabled(has_property<property::queue::enable_profiling>()),
-        MHasDiscardEventsSupport(MDiscardEvents &&
-                                 (MHostQueue ? true : MIsInorder)),
+        MSupportsDiscardingPiEvents(MDiscardEvents &&
+                                    (MHostQueue ? true : MIsInorder)),
         MQueueID{
             MNextAvailableQueueID.fetch_add(1, std::memory_order_relaxed)} {
     if (has_property<property::queue::enable_profiling>()) {
@@ -288,8 +288,8 @@ class queue_impl {
         MDiscardEvents(
             has_property<ext::oneapi::property::queue::discard_events>()),
         MIsProfilingEnabled(has_property<property::queue::enable_profiling>()),
-        MHasDiscardEventsSupport(MDiscardEvents &&
-                                 (MHostQueue ? true : MIsInorder)),
+        MSupportsDiscardingPiEvents(MDiscardEvents &&
+                                    (MHostQueue ? true : MIsInorder)),
         MQueueID{
             MNextAvailableQueueID.fetch_add(1, std::memory_order_relaxed)} {
     queue_impl_interop(PiQueue);
@@ -310,8 +310,8 @@ class queue_impl {
         MDiscardEvents(
             has_property<ext::oneapi::property::queue::discard_events>()),
         MIsProfilingEnabled(has_property<property::queue::enable_profiling>()),
-        MHasDiscardEventsSupport(MDiscardEvents &&
-                                 (MHostQueue ? true : MIsInorder)) {
+        MSupportsDiscardingPiEvents(MDiscardEvents &&
+                                    (MHostQueue ? true : MIsInorder)) {
     queue_impl_interop(PiQueue);
   }
 
@@ -367,7 +367,9 @@ class queue_impl {
   bool is_host() const { return MHostQueue; }
 
   /// \return true if this queue has discard_events support.
-  bool has_discard_events_support() const { return MHasDiscardEventsSupport; }
+  bool supportsDiscardingPiEvents() const {
+    return MSupportsDiscardingPiEvents;
+  }
 
   bool isInOrder() const { return MIsInorder; }
 
@@ -959,12 +961,11 @@ class queue_impl {
   const bool MIsProfilingEnabled;
 
 protected:
-  // This flag says if we can discard events based on a queue "setup" which will
-  // be common for all operations submitted to the queue. This is a must
-  // condition for discarding, but even if it's true, in some cases, we won't be
-  // able to discard events, because the final decision is made right before the
-  // operation itself.
-  const bool MHasDiscardEventsSupport;
+  // Indicates whether the queue supports discarding PI events for tasks
+  // submitted to it. This condition is necessary but not sufficient, PI events
+  // should be discarded only if they also don't represent potential implicit
+  // dependencies for future tasks in other queues.
+  const bool MSupportsDiscardingPiEvents;
 
   // Command graph which is associated with this queue for the purposes of
   // recording commands to it.

sycl/source/detail/scheduler/commands.cpp

@@ -2678,7 +2678,7 @@ pi_int32 ExecCGCommand::enqueueImpCommandBuffer() {
   }
 
   sycl::detail::pi::PiEvent *Event =
-      (MQueue->has_discard_events_support() &&
+      (MQueue->supportsDiscardingPiEvents() &&
        MCommandGroup->getRequirements().size() == 0)
           ? nullptr
           : &MEvent->getHandleRef();
@@ -2825,11 +2825,11 @@ pi_int32 ExecCGCommand::enqueueImpQueue() {
   auto RawEvents = getPiEvents(EventImpls);
   flushCrossQueueDeps(EventImpls, getWorkerQueue());
 
-  bool DiscardEvent = (MQueue->has_discard_events_support() &&
-                       MCommandGroup->getRequirements().size() == 0);
+  bool DiscardPiEvent = (MQueue->supportsDiscardingPiEvents() &&
+                         MCommandGroup->getRequirements().size() == 0);
   sycl::detail::pi::PiEvent *Event =
-      DiscardEvent ? nullptr : &MEvent->getHandleRef();
-  detail::EventImplPtr EventImpl = DiscardEvent ? nullptr : MEvent;
+      DiscardPiEvent ? nullptr : &MEvent->getHandleRef();
+  detail::EventImplPtr EventImpl = DiscardPiEvent ? nullptr : MEvent;
 
   switch (MCommandGroup->getType()) {
 

sycl/source/handler.cpp

@@ -292,7 +292,7 @@ event handler::finalize() {
       };
 
       bool DiscardEvent = false;
-      if (MQueue->has_discard_events_support()) {
+      if (MQueue->supportsDiscardingPiEvents()) {
         // Kernel only uses assert if it's non interop one
         bool KernelUsesAssert =
             !(MKernel && MKernel->isInterop()) &&