[flang-commits] [flang] Parallel runtime library design doc (PRIF) (PR #76088)

[Jeff Hammond via flang-commits]

jeffhammond wrote:

Put with notification is nigh impossible to implement efficiently as specified.  Notification variables must be in coarrays.  Having the only argument in `prif_put(_raw)` be `notify_ptr` requires an MPI-based implementation (or any other that can't do remote atomic writes to virtual memory directly) to do an expensive lookup on the critical path of what is supposed to be a high-performance operation.

You should implement the put+notify with a separate function that has a second 
`type(prif_coarray_handle)` argument for the notification variable.

https://github.com/llvm/llvm-project/pull/76088