[flang-commits] [flang] [flang][OpenMP][RFC] Add support for COPYPRIVATE (PR #73128)

[via flang-commits]

https://github.com/jeanPerier commented:

I am a bit rusty with OpenMP, but how do you ensure that the sync variable is shared by all the threads when this is a single in a subprogram without a parallel?

I would expect the alloca for the buffer to be "private" to each threads that entered the subprogram in a call from.

e.g: do all threads print `1` in the program below?

```
subroutine foo(i)
 !$omp single
 i = 1
 !$omp end single copyprivate(i)
end subroutine

  integer, save :: i = 0
  !$omp threadprivate(i)
  !$omp parallel
  call foo(i)
  !$omp critical
  print *, i
  !$omp end critical 
  !$omp end parallel
end
```

>From a design point of view, would there be advantages to keep the copyprivate implementation abstract in the IR (e.g, to not make the buffer/barriers/copies explicit yet)?

https://github.com/llvm/llvm-project/pull/73128