[flang] [llvm] [flang][OpenMP] Decompose compound constructs, do recursive lowering (PR #90098)

[Krzysztof Parzyszek via llvm-commits]

kparzysz wrote:

> I'll work on getting a small reproducer.

@psteinfeld Could you check if adding `-fopenmp-version=52` changes anything?

https://github.com/llvm/llvm-project/pull/90098