[OpenMP] Make isDone lightweight without calling synchronize

~TaskAsyncInfoWrapperTy() calls isDone. With synchronize inside isDone, we need to handle the error return from synchronize in the destructor.
The consumers of TaskAsyncInfoWrapperTy, targetDataMapper and targetKernel, both call AsyncInfo.synchronize() before exiting.
For this reason in ~TaskAsyncInfoWrapperTy(), calling synchronize() via isDone() is redundant.
This patch removes synchronize() call inside isDone() and makes it a lightweight check.
__tgt_target_nowait_query needs to call synchronize() before checking isDone().

Differential Revision: https://reviews.llvm.org/D144315

Author: ye-luo

openmp/libomptarget/include/omptarget.h

@@ -17,7 +17,6 @@
 #include <cstdint>
 #include <deque>
 #include <functional>
-#include <optional>
 #include <stddef.h>
 #include <stdint.h>
 #include <type_traits>
@@ -244,12 +243,12 @@ class AsyncInfoTy {
 
   /// Check if all asynchronous operations are completed.
   ///
-  /// \note if the operations are completed, the registered post-processing
-  /// functions will be executed once and unregistered afterwards.
+  /// \note only a lightweight check. If needed, use synchronize() to query the
+  /// status of AsyncInfo before checking.
   ///
   /// \returns true if there is no pending asynchronous operations, false
-  /// otherwise. We return a null value in the case of an error from the plugin.
-  std::optional<bool> isDone();
+  /// otherwise.
+  bool isDone() const;
 
   /// Add a new post-processing function to be executed after synchronization.
   ///

openmp/libomptarget/src/interface.cpp

@@ -412,12 +412,11 @@ EXTERN void __tgt_target_nowait_query(void **AsyncHandle) {
   if (QueryCounter.isAboveThreshold())
     AsyncInfo->SyncType = AsyncInfoTy::SyncTy::BLOCKING;
 
-  auto DoneOrErr = AsyncInfo->isDone();
-  if (!DoneOrErr)
+  if (const int Rc = AsyncInfo->synchronize())
     FATAL_MESSAGE0(1, "Error while querying the async queue for completion.\n");
   // If there are device operations still pending, return immediately without
   // deallocating the handle and increase the current thread query count.
-  if (!*DoneOrErr) {
+  if (!AsyncInfo->isDone()) {
     QueryCounter.increment();
     return;
   }

openmp/libomptarget/src/omptarget.cpp

@@ -51,13 +51,7 @@ void *&AsyncInfoTy::getVoidPtrLocation() {
   return BufferLocations.back();
 }
 
-std::optional<bool> AsyncInfoTy::isDone() {
-  if (synchronize() == OFFLOAD_FAIL)
-    return std::nullopt;
-
-  // The async info operations are completed when the internal queue is empty.
-  return isQueueEmpty();
-}
+bool AsyncInfoTy::isDone() const { return isQueueEmpty(); }
 
 int32_t AsyncInfoTy::runPostProcessing() {
   size_t Size = PostProcessingFunctions.size();

openmp/libomptarget/src/private.h

@@ -250,13 +250,9 @@ class TaskAsyncInfoWrapperTy {
     if (AsyncInfo == &LocalAsyncInfo)
       return;
 
-    auto DoneOrErr = AsyncInfo->isDone();
-    if (!DoneOrErr)
-      FATAL_MESSAGE0(1,
-                     "Error while querying the async queue for completion.\n");
     // If the are device operations still pending, return immediately without
     // deallocating the handle.
-    if (!*DoneOrErr)
+    if (!AsyncInfo->isDone())
       return;
 
     // Delete the handle and unset it from the OpenMP task data.