RE: RFC: /usr/bin/hipcxx for system default HIP compiler
[Public]
This will be challenging if the upstream both AMD and CMAKE do not adopt this proposal.
Fedora and by extension OpenSUSE has by and large gone with whatever the upstream has been using (we are a little slow on going to amdclang++), but have not had imo problems either using or supporting hipcc or <path-to>/rocm-llvm/clang directly.
Tom
-----Original Message-----
From: Cordell Bloor <cgmb@slerp.xyz>
Sent: Monday, July 21, 2025 7:19 AM
To: Debian ROCm Team <debian-ai@lists.debian.org>
Subject: RFC: /usr/bin/hipcxx for system default HIP compiler
I'd like to propose adding a symlink for the system HIP compiler at /usr/bin/hipcxx that can be managed through the Debian Alternatives system [1]. The purpose of this is twofold. First, it would provide a constant name for the system HIP compiler so that packages are tools no longer need to know which amdclang++ / clang++ / clang++-NN compiler is used for building HIP programs on that particular version of Debian.
Second, it would allow for the possibility of supporting multiple different HIP compilers (e.g., both upstream LLVM and the AMD fork).
This mechanism would be quite similar to the C, C++, and Fortran, where the following compilers are available through the alternatives mechanism:
/usr/bin/cc
/usr/bin/c89
/usr/bin/c99
/usr/bin/c++
/usr/bin/f77
/usr/bin/f95
The HIP language compiler would fit right in as:
/usr/bin/hipcxx
This path avoids conflicts with the /usr/bin/hipcc wrapper script. The hipcxx name is consistent with the HIPCXX environment variable used to manually specify which clang++ compiler for CMake to use for the HIP language [2]. If this name is chosen, I would contribute a patch to CMake to add hipcxx to the list of compiler names considered when
enable_language(hip) is called.
At the moment, users and packagers need to manually specify the HIPCXX environment variable to let CMake know the name of the clang++ compiler to use for HIP. This is very confusing, because the name is different on every release of Debian. Users currently must know to specify clang++-15 in Debian 12, clang++-17 in Debian 13, and soon something new in Debian 14. It would be nice to get enable_language(hip) to 'just work' and thereby make it easier for folks to transition from using hipcc to using the built-in support for HIP in CMake. A stable name for the system HIP compiler would allow us to achieve that.
When CMake understands that it's building HIP code, there's a lot of things that will become better for us in packaging HIP libraries and applications. It then means that we can use mechanisms like HIPFLAGS set globally in dpkg-buildflags for all HIP language packages, rather than having to fuss with modifying CXXFLAGS when the CXX compiler is hipcc. I believe this enhancement would help to make the HIP language a first-class citizen within Debian tooling.
Sincerely,
Cory Bloor
[1]: https://wiki.debian.org/DebianAlternatives
[2]: https://cmake.org/cmake/help/v4.1/envvar/HIPCXX.html
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