LLVM_ENABLE_RUNTIMES=flang-rt for flang-runtime-cuda-*

[Meinersbur]

Add depends_on_projects=['flang-rt'] to the flang-runtime-cuda-gcc and flang-runtime-cuda-clang builders. This prepares the removal of the "projects" build of the flang runtime in llvm/llvm-project#124126.

Split off from #333

Affected builders:

• flang-runtime-cuda-gcc
  This previously only built the runtime using the top-level CMakeLists.txt in flang/runtime/CMakeLists.txt. This is going to be replaced with the "standalone runtimes build", with the top-level runtimes/CMakeLists.txt. This still needs Flang to successed, hence replacing with a bootstrap-build where the FLANG_RT_* options are internally forwarded to the runtimes build.
• flang-runtime-cuda-clang
  This is a manual bootstrapping build which first compiles Clang, then the runtime out-of-tree. This is replaced with a standalone runtimes build as described above. Because it needs Flang, also adding Flang to the enabled projects of the stage1 build.

Neither build runs the check-* targets, probably due to the lack of actual CUDA hardware which running the runtime unittests require.

Affected workers:

• as-builder-7

Admins listed for those workers:

• Galina Kistanova gkistanova@accesssoftek.com

[vzakhari]

Thank you, Michael! For flang-runtime-cuda-gcc build, does it imply that flang will be always rebuilt? If yes, then we will need to decide what to do about the increased time required by the build. I think there is some limit, but I do not know for sure.

[Meinersbur]

Thank you, Michael! For flang-runtime-cuda-gcc build, does it imply that flang will be always rebuilt?

Yes, but it uses ccache so re-builds usually don't take the maximum time.

If yes, then we will need to decide what to do about the increased time required by the build. I think there is some limit, but I do not know for sure.

LLVM's Buildbot is configured without absolute timeout. There are much slower workers in labs.llvm.org, taking up 16 hours to build.

If the as-builder-7 is becoming too slow¹, I can combine flang-runtime-cuda-gcc and flang-runtime-cuda-clang so Flang is built only once. For Polly builders, I tricked it to use the same ccache cache for all builders.

Footnotes

1. as-builder-7 is also building llvm-nvptx-nvidia-ubuntu and llvm-nvptx64-nvidia-ubuntu. ↩

[vzakhari]

Thanks for the explanation, Michael! It looks good to me, but I am not the one to approve it.

[vvereschaka]

LGTM