[PATCH] D97340: [HIP] Support Spack packages

[Yaxun Liu via Phabricator via cfe-commits]

yaxunl added a comment.

In D97340#2778073 <https://reviews.llvm.org/D97340#2778073>, @haampie wrote:

> Hi Yaxunl,
>
>> The patch should not cause circular dependency on HIP or device library.
>
> I'm not saying this patch introduces a circular dependency, I'm saying you are trying to solve an already existing circular dependency (clang needs device libs at runtime, but device libs need llvm to compile).
>
> Let's talk about my PR here: https://github.com/spack/spack/pull/23859. It's building rocm-device-libs as part of llvm-amdgpu by configuring llvm with `-DLLVM_EXTERNAL_PROJECTS=device-libs`.
>
> If you checkout that pr, run `spack install hip at 4.2.0`, what you get is get is:
>
>   $ spack find -p llvm-amdgpu at 4.2.0
>   llvm-amdgpu at 4.2.0  /spack/opt/spack/linux-ubuntu20.04-zen2/gcc-10.2.0/llvm-amdgpu-4.2.0-a7jwajhh2cmn7p5djyx42lpcdfluk7wi
>
> And indeed the bitcode is there:
>
>   $ find /spack/opt/spack/linux-ubuntu20.04-zen2/gcc-10.2.0/llvm-amdgpu-4.2.0-a7jwajhh2cmn7p5djyx42lpcdfluk7wi -iname '*.bc'
>   /spack/opt/spack/linux-ubuntu20.04-zen2/gcc-10.2.0/llvm-amdgpu-4.2.0-a7jwajhh2cmn7p5djyx42lpcdfluk7wi/amdgcn/bitcode/oclc_isa_version_1033.bc
>   /spack/opt/spack/linux-ubuntu20.04-zen2/gcc-10.2.0/llvm-amdgpu-4.2.0-a7jwajhh2cmn7p5djyx42lpcdfluk7wi/amdgcn/bitcode/ocml.bc
>   /spack/opt/spack/linux-ubuntu20.04-zen2/gcc-10.2.0/llvm-amdgpu-4.2.0-a7jwajhh2cmn7p5djyx42lpcdfluk7wi/amdgcn/bitcode/hip.bc
>   ...
>
> Now when I used this `--print-rocm-search-dirs` flag on clang without other flags, what I see is:
>
>   $ /spack/opt/spack/linux-ubuntu20.04-zen2/gcc-10.2.0/llvm-amdgpu-4.2.0-a7jwajhh2cmn7p5djyx42lpcdfluk7wi/bin/clang++ --print-rocm-search-dirs -x hip hi.cc 
>   ROCm installation search path (Spack 4.2.0): /spack/opt/spack/linux-ubuntu20.04-zen2/gcc-10.2.0
>   ROCm installation search path: /spack/opt/spack/linux-ubuntu20.04-zen2/gcc-10.2.0/llvm-amdgpu-4.2.0-a7jwajhh2cmn7p5djyx42lpcdfluk7wi/lib/clang/12.0.0
>   ROCm installation search path: /opt/rocm
>   ...
>   clang-12: error: cannot find ROCm device library. Provide its path via --rocm-path or --rocm-device-lib-path, or pass -nogpulib to build without ROCm device library.
>
> Now can you make it such that clang will search the llvm prefix itself?

Yes I can make clang to search that path for device libs. I will open a review for that and remove the old detection of device libs for spack.

I still think auto detection of HIP path is a desirable feature, especially for interactive use of clang in a shell. This also allows clang to maintain certain level of backward compatibility with old HIP runtime by detecting HIP version.


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https://reviews.llvm.org/D97340