[clang] [flang] [llvm] [openmp] [Flang] Move builtin .mod generation into runtimes (PR #137828)

[Håkon Strandenes via llvm-commits]

hakostra wrote:

Hi @Meinersbur, I don't know if this is the right way to approach this (I could open a new issue also), but I'm trying here first. I have been waiting for this to be merged as I believe it would possibly solve my issue #146876 (I think there are at least two other related issue in the tracker as well). I have now build the commit 86fbaef99a form the main branch, and I see the module files in `<prefix>/lib/clang/22/finclude/flang/x86_64-unknown-linux-gnu`. However, I do not see any module files for nvptx64 (or any other targets for that matter). And trying to use any module file when targeting the GPU gives me an error message `error: Cannot parse module file for module 'ieee_arithmetic': Source file 'ieee_arithmetic.mod' was not found` (which is correct - the file is not there).

Do I miss something obvious? Do we need to set some new CMake flags/options compared to previous for this to be built correctly?

https://github.com/llvm/llvm-project/pull/137828