[Offload] Introduce dataFence plugin interface. (#153793)

The purpose of this fence is to ensure that any `dataSubmit`s inserted
into a queue before a `dataFence` finish before finish before any
`dataSubmit`s
inserted after it begin.

This is a no-op for most queues, since they are in-order, and by design
any operations inserted into them occur in order.

But the interface is supposed to be functional for out-of-order queues.

The addition of the interface means that any operations that rely on
such ordering (like ATTACH map-type support in #149036) can invoke it,
without worrying about whether the underlying queue is in-order or
out-of-order.

Once a plugin supports out-of-order queues, the plugin can implement
this function, without requiring any change at the libomptarget level.

---------

Co-authored-by: Alex Duran <alejandro.duran@intel.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/offload/plugins-nextgen/cuda/src/rtl.cpp b/offload/plugins-nextgen/cuda/src/rtl.cpp
index 155a580faee2..a99357a3adea 100644
--- a/offload/plugins-nextgen/cuda/src/rtl.cpp
+++ b/offload/plugins-nextgen/cuda/src/rtl.cpp
@@ -856,6 +856,13 @@ struct CUDADeviceTy : public GenericDeviceTy {
     return Plugin::success();
   }
 
+  /// Insert a data fence between previous data operations and the following
+  /// operations. This is a no-op for CUDA devices as operations inserted into
+  /// a queue are in-order.
+  Error dataFence(__tgt_async_info *Async) override {
+    return Plugin::success();
+  }
+
   /// Initialize the device info for interoperability purposes.
   Error initDeviceInfoImpl(__tgt_device_info *DeviceInfo) override {
     assert(Context && "Context is null");