LLVM_ENABLE_RUNTIMES=flang-rt for amdgpu-offload-*

[Meinersbur]

Add depends_on_projects=['flang-rt'], and checks=['check-flang-rt'] to the amdgpu-offload-* builders. The prepares the removal of the "projects" build of the flang runtime in llvm/llvm-project#124126.

The corresponding change in the LLVM repository is llvm/llvm-project#129692

Affected builders (production):

• amdgpu-offload-ubuntu-22-cmake-build-only
• amdgpu-offload-rhel-9-cmake-build-only
• amdgpu-offload-rhel-8-cmake-build-only

Affected workers (production):

• rocm-docker-ubu-22
• rocm-docker-rhel-9
• rocm-docker-rhel-8

Admins listed for those workers:

• AMD dl.gcr.lightning.buildbot@amd.com

[Meinersbur]

Unfortunately, the annotated builders are impossible to check locally using instructions from https://llvm.org/docs/HowToAddABuilder.html#testing-a-builder-config-locally, as the build instructions are taken directly from multiple main directories on github.com:

• The buildbot master takes the builder configuration which contain the instruction for the worker to execute amdgpu-offload-cmake.py.
• The worker checks out llvm-zorg from its public repository and executes amdgpu-offload-cmake.py from there (NOT the locally modified version of it). It contains instructions to pre-populate the CMake cache from file AMDGPUBot.cmake.
• The worker also checks out llvm-project from its public repository which contains the AMDGPUBot.cmake file.

Running the unchanged/main worktree gets me the following error:

Running: cmake ../llvm-project/llvm -GNinja "-C ../llvm-project/offload/cmake/caches/AMDGPUBot.cmake"
Current working directory cannot be established.
['cmake', '../llvm-project/llvm', '-GNinja', '-C ../llvm-project/offload/cmake/caches/AMDGPUBot.cmake'] exited with return code 1.

I think this is because amdgpu-offload-cmake.py is deleting its own current work directory [sic!], after which the cwd file descriptor refers to a non-existing directory which CMake cannot cope with. I cannot verify this assumption without modifying the upstream repositories.

The in-production buildbot workers may not see the issue because the rmtree fails deleting some file, keeping the cwd file descriptor the same.

[jplehr]

I have a setup for local testing and can take a swing at it for a test.

[jplehr]

I think this is because amdgpu-offload-cmake.py is deleting its own current work directory [sic!], after which the cwd file descriptor refers to a non-existing directory which CMake cannot cope with.

That is not quite the intended behavior, but after looking at the code, I believe you are right. Let me put up a patch that does what it should do more reasonably.

[jplehr]

LGTM
Depending on the activity with the flang-rt, we may want to land this prior to the change to the CMake cache, such that the scheduler is already aware of the dependency.