[compiler-rt] [llvm] [openmp] [Runtimes] Default build must use its own output dirs (PR #168266)

[Michael Kruse via llvm-commits]

Meinersbur wrote:

> Unfortunately, the latest version causes regressions in offload tests:
> 
> ```
> # | '/usr/lib/llvm/22/bin/llvm-offload-device-info': command not found
> # | '/usr/lib/llvm/22/bin/offload-tblgen': command not found
> ```
> 
> i.e. it's using system LLVM binary directory for just-built tools.

I didn't notice these are locally-built, i.e. `LLVM_RUNTIME_OUTPUT_INTDIR` is the expected path.

The "CMake-proper" way for locally built files is `$<TARGET_FILE:llvm-offload-device-info>` and `add_custom_command(COMMAND offload-tblgen)`. The former requires to use `file(GENERATE ...)` instead of `configure_file(...)`.

I don't get how `offload-tblgen` is supposed to work in a runtime. Unless compiling to the native platform, it cannot be executed.

https://github.com/llvm/llvm-project/pull/168266