[SYCL][UR] Add UR_QUEUE_INFO_EMPTY support for OpenCL (#19151)

To fix CTS test
(https://github.com/KhronosGroup/SYCL-CTS/blob/b5cf985ecc497f82045165e9309fdc7a990c7e60/tests/extension/khr_queue_empty_query/queue_empty.cpp)
failures for the `sycl_khr_queue_empty_query` extension (implemented in
#18799), which are caused by the error
`UR_RESULT_ERROR_UNSUPPORTED_ENUMERATION` emitted in the old code.

---------

Signed-off-by: Hu, Peisen <peisen.hu@intel.com>

Author: HPS-1

sycl/test-e2e/Basic/out_of_order_queue_status_ext_oneapi_empty.cpp

@@ -73,9 +73,5 @@ int main() {
     ExceptionThrown = true;
   }
 
-  // Feature is not supported for OpenCL, exception must be thrown.
-  if (Q.get_device().get_backend() == backend::opencl)
-    return ExceptionThrown ? 0 : -1;
-
-  return 0;
+  return ExceptionThrown ? -1 : 0;
 }

sycl/test-e2e/Basic/out_of_order_queue_status_khr_empty.cpp

@@ -74,9 +74,5 @@ int main() {
     ExceptionThrown = true;
   }
 
-  // Feature is not supported for OpenCL, exception must be thrown.
-  if (Q.get_device().get_backend() == backend::opencl)
-    return ExceptionThrown ? 0 : -1;
-
-  return 0;
+  return ExceptionThrown ? -1 : 0;
 }

unified-runtime/source/adapters/opencl/queue.cpp

@@ -7,6 +7,7 @@
 //===-----------------------------------------------------------------===//
 
 #include "queue.hpp"
+#include "CL/cl.h"
 #include "common.hpp"
 #include "context.hpp"
 #include "device.hpp"
@@ -172,8 +173,19 @@ UR_APIEXPORT ur_result_t UR_APICALL urQueueGetInfo(ur_queue_handle_t hQueue,
   UrReturnHelper ReturnValue(propSize, pPropValue, pPropSizeRet);
   if (propName == UR_QUEUE_INFO_EMPTY) {
     if (!hQueue->LastEvent) {
-      // OpenCL doesn't provide API to check the status of the queue.
-      return UR_RESULT_ERROR_UNSUPPORTED_ENUMERATION;
+      // Check the status of the queue under OpenCL backend.
+      cl_event Event;
+      CL_RETURN_ON_FAILURE(
+          clEnqueueMarkerWithWaitList(hQueue->CLQueue, 0, nullptr, &Event));
+      cl_int QueryResult;
+      CL_RETURN_ON_FAILURE(
+          clGetEventInfo(Event, CL_EVENT_COMMAND_EXECUTION_STATUS,
+                         sizeof(QueryResult), &QueryResult, nullptr));
+      CL_RETURN_ON_FAILURE(clReleaseEvent(Event));
+      if (QueryResult == CL_COMPLETE) {
+        return ReturnValue(true);
+      }
+      return ReturnValue(false);
     } else {
       ur_event_status_t Status;
       UR_RETURN_ON_FAILURE(urEventGetInfo(