[llvm] [Offload] Add OFFLOAD_FORCE_SYNC_OPS force-synchronization escape hatch (PR #222635)

[Joseph Huber via llvm-commits]

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@@ -1399,6 +1408,13 @@ struct GenericDeviceTy : public DeviceAllocatorTy {
   BoolEnvar OMPX_TrackAllocationTraces =
       BoolEnvar("OFFLOAD_TRACK_ALLOCATION_TRACES", false);
 
+  /// Environment flag that forces every device operation to be synchronized,
+  /// draining the queue after each operation. Debugging escape hatch.
+  BoolEnvar OF_ForceSyncOps = BoolEnvar("OFFLOAD_FORCE_SYNC_OPS", false);
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jhuber6 wrote:

Just `OFFLOAD_FORCE_BLOCKING` would probably be fine.

https://github.com/llvm/llvm-project/pull/222635