[clang] [llvm] [openmp] [OpenMP] Use generic IR for the OpenMP DeviceRTL (PR #119091)

[Matt Arsenault via cfe-commits]

arsenm wrote:

> Does wave32/wave64 affect the lowering from front end source code to middle end IR, if we don't use certain functions, such as wave level primitives?

Yes. This is a fixed ABI setting that can change the binary function signature (which then has knock on optimization effects). The IR is a representation of what goes on a final .o. It is not really intended to enable new features or make the program portable. 

https://github.com/llvm/llvm-project/pull/119091