[Offload] Replace "EventOut" parameters with `olCreateEvent` (#150217)

Rather than having every "enqueue"-type function have an output pointer
specifically for an output event, just provide an `olCreateEvent`
entrypoint which pushes an event to the queue.

For example, replace:
```cpp
olMemcpy(Queue, ..., EventOut);
```
with
```cpp
olMemcpy(Queue, ...);
olCreateEvent(Queue, EventOut);
```

4 files changed, 24 insertions, 28 deletions

diff --git a/offload/liboffload/API/Event.td b/offload/liboffload/API/Event.td
index ea38b82ee145..9d217ae23038 100644
--- a/offload/liboffload/API/Event.td
+++ b/offload/liboffload/API/Event.td
@@ -11,6 +11,19 @@
 //===----------------------------------------------------------------------===//
 
 def : Function {
+    let name = "olCreateEvent";
+    let desc = "Enqueue an event to `Queue` and return it.";
+    let details = [
+      "This event can be used with `olSyncEvent` and `olWaitEvents` and will be complete once all enqueued work prior to the `olCreateEvent` call is complete.",
+    ];
+    let params = [
+        Param<"ol_queue_handle_t", "Queue", "queue to create the event for", PARAM_IN>,
+        Param<"ol_event_handle_t*", "Event", "output pointer for the created event", PARAM_OUT>
+    ];
+    let returns = [];
+}
+
+def : Function {
     let name = "olDestroyEvent";
     let desc = "Destroy the event and free all underlying resources.";
     let details = [];
diff --git a/offload/liboffload/API/Kernel.td b/offload/liboffload/API/Kernel.td
index 1e9537452820..502fb36467db 100644
--- a/offload/liboffload/API/Kernel.td
+++ b/offload/liboffload/API/Kernel.td
@@ -35,10 +35,8 @@ def : Function {
         Param<"const void*", "ArgumentsData", "pointer to the kernel argument struct", PARAM_IN_OPTIONAL>,
         Param<"size_t", "ArgumentsSize", "size of the kernel argument struct", PARAM_IN>,
         Param<"const ol_kernel_launch_size_args_t*", "LaunchSizeArgs", "pointer to the struct containing launch size parameters", PARAM_IN>,
-        Param<"ol_event_handle_t*", "EventOut", "optional recorded event for the enqueued operation", PARAM_OUT_OPTIONAL>
     ];
     let returns = [
-        Return<"OL_ERRC_INVALID_ARGUMENT", ["`Queue == NULL && EventOut != NULL`"]>,
         Return<"OL_ERRC_INVALID_ARGUMENT", ["`ArgumentsSize > 0 && ArgumentsData == NULL`"]>,
         Return<"OL_ERRC_INVALID_DEVICE", ["If Queue is non-null but does not belong to Device"]>,
         Return<"OL_ERRC_SYMBOL_KIND", ["The provided symbol is not a kernel"]>,
diff --git a/offload/liboffload/API/Memory.td b/offload/liboffload/API/Memory.td
index 029975c44829..5f7158588bc7 100644
--- a/offload/liboffload/API/Memory.td
+++ b/offload/liboffload/API/Memory.td
@@ -60,9 +60,6 @@ def : Function {
         Param<"const void*", "SrcPtr", "pointer to copy from", PARAM_IN>,
         Param<"ol_device_handle_t", "SrcDevice", "device that SrcPtr belongs to", PARAM_IN>,
         Param<"size_t", "Size", "size in bytes of data to copy", PARAM_IN>,
-        Param<"ol_event_handle_t*", "EventOut", "optional recorded event for the enqueued operation", PARAM_OUT_OPTIONAL>
-    ];
-    let returns = [
-        Return<"OL_ERRC_INVALID_ARGUMENT", ["`Queue == NULL && EventOut != NULL`"]>
     ];
+    let returns = [];
 }
diff --git a/offload/liboffload/src/OffloadImpl.cpp b/offload/liboffload/src/OffloadImpl.cpp
index 87f924168272..8f316b87fc47 100644
--- a/offload/liboffload/src/OffloadImpl.cpp
+++ b/offload/liboffload/src/OffloadImpl.cpp
@@ -591,26 +591,21 @@ Error olGetEventInfoSize_impl(ol_event_handle_t Event, ol_event_info_t PropName,
   return olGetEventInfoImplDetail(Event, PropName, 0, nullptr, PropSizeRet);
 }
 
-ol_event_handle_t makeEvent(ol_queue_handle_t Queue) {
-  auto EventImpl = std::make_unique<ol_event_impl_t>(nullptr, Queue);
-  if (auto Res = Queue->Device->Device->createEvent(&EventImpl->EventInfo)) {
-    llvm::consumeError(std::move(Res));
-    return nullptr;
-  }
+Error olCreateEvent_impl(ol_queue_handle_t Queue, ol_event_handle_t *EventOut) {
+  *EventOut = new ol_event_impl_t(nullptr, Queue);
+  if (auto Res = Queue->Device->Device->createEvent(&(*EventOut)->EventInfo))
+    return Res;
 
-  if (auto Res = Queue->Device->Device->recordEvent(EventImpl->EventInfo,
-                                                    Queue->AsyncInfo)) {
-    llvm::consumeError(std::move(Res));
-    return nullptr;
-  }
+  if (auto Res = Queue->Device->Device->recordEvent((*EventOut)->EventInfo,
+                                                    Queue->AsyncInfo))
+    return Res;
 
-  return EventImpl.release();
+  return Plugin::success();
 }
 
 Error olMemcpy_impl(ol_queue_handle_t Queue, void *DstPtr,
                     ol_device_handle_t DstDevice, const void *SrcPtr,
-                    ol_device_handle_t SrcDevice, size_t Size,
-                    ol_event_handle_t *EventOut) {
+                    ol_device_handle_t SrcDevice, size_t Size) {
   auto Host = OffloadContext::get().HostDevice();
   if (DstDevice == Host && SrcDevice == Host) {
     if (!Queue) {
@@ -641,9 +636,6 @@ Error olMemcpy_impl(ol_queue_handle_t Queue, void *DstPtr,
       return Res;
   }
 
-  if (EventOut)
-    *EventOut = makeEvent(Queue);
-
   return Error::success();
 }
 
@@ -690,8 +682,7 @@ Error olDestroyProgram_impl(ol_program_handle_t Program) {
 Error olLaunchKernel_impl(ol_queue_handle_t Queue, ol_device_handle_t Device,
                           ol_symbol_handle_t Kernel, const void *ArgumentsData,
                           size_t ArgumentsSize,
-                          const ol_kernel_launch_size_args_t *LaunchSizeArgs,
-                          ol_event_handle_t *EventOut) {
+                          const ol_kernel_launch_size_args_t *LaunchSizeArgs) {
   auto *DeviceImpl = Device->Device;
   if (Queue && Device != Queue->Device) {
     return createOffloadError(
@@ -729,9 +720,6 @@ Error olLaunchKernel_impl(ol_queue_handle_t Queue, ol_device_handle_t Device,
   if (Err)
     return Err;
 
-  if (EventOut)
-    *EventOut = makeEvent(Queue);
-
   return Error::success();
 }