[apt.llvm.org] libclc packages should include the targets spirv-mesa3d- and spirv64-mesa3d-

[TheRealCuran]

Running RUSTICL_ENABLE=radeonsi clinfo with the latest llvm-toolchain-snapshot packages from apt.llvm.org results in the following error:

Libclc failed to load. Please make sure it is installed and provides spirv-mesa3d-.spv and/or spirv64-mesa3d-.spv

Later in the output clinfo reports, that no devices were found.

At the moment the llvm-toolchain-snapshot packages won't install any *.spv artifacts in libclc, see https://salsa.debian.org/pkg-llvm-team/llvm-toolchain/-/blob/snapshot/debian/libclc-X.Y.install.in#L2

On top of that non will be built, because debian/rules tests for the existence of llvm-spirv or llvm-spirv-$LLVM_VERSION in https://salsa.debian.org/pkg-llvm-team/llvm-toolchain/-/blob/snapshot/debian/rules#L359-L363 (which should never be true).

This is a bit of a hen egg issue, since you need LLVM/CLang headers available (besides the spirv-headers and the spirv-tools). Thus you could either do the libclc build extra and have the other parts built individually (first LLVM/CLang, then the headers, tools, then llvm-spirv and finally libclc) or, if I read https://github.com/llvm/llvm-project/blob/main/libclc/CMakeLists.txt#L109 correctly, by providing the required sources in the LLVM build tree.

llvm-spirv from https://github.com/KhronosGroup/SPIRV-LLVM-Translator must match the major version of LLVM (and usually needs to be pretty up-to-date for it to be buildable with HEAD of LLVM. So far Debian has an individual spirv-llvm-translator package, but that hasn't been updated in a while. And I have no idea what would be better with regards to the apt.llvm.org build of libclc (ie. providing llvm-spirv in-tree or building it extra).

Anyway: please provide the spirv-mesa3d- and spirv64-mesa3d- targets in the apt.llvm.org Debian package builds of llvm-toolchain-snapshot. Thanks!

[sylvestre]

How can I enable it? Thanks

[TheRealCuran]

As I wrote above: you need llvm-spirv from https://github.com/KhronosGroup/SPIRV-LLVM-Translator present. This means either reviving https://tracker.debian.org/pkg/spirv-llvm-translator or doing an in-tree build. Reviving spirv-llvm-translater would be nice in general (and starting with Mesa 25.2 more or less needed, if Debian wants to have OpenCL drivers), but it would mean a double build of the LLVM packages (at least partially): one time "normal" and one time for libclc. Therefore I would assume you would like to do the in-tree build (this should at least provide llvm-spirv, I have no idea if the libraries would also be created and one could just generate the binary packages spriv-llvm-translator once provided from this in-tree build.

If you want to do the in-tree build, you need to follow https://github.com/KhronosGroup/SPIRV-LLVM-Translator/blob/c3b8056b44acfd87837ae613da9520ae38751cd6/README.md#llvm-in-tree-build (basically: add the sources for SPIRV-LLVM-Translator to the LLVM tree and make sure you either pass spirv-mesa3d- and spirv64-mesa3d- or all as targets for libclc to your build from your debian/rules (at the moment that would only happen with a pre-installed llvm-spirv, I think). At the moment you construct the targets for libclc in LIBCLC_TARGETS_TO_BUILD in your debian/rules.

Once the libclc build generates the *.spv files, you will have to remove the # from the second line of debian/libclc-X.Y.install.in

I hope this helps?

[sylvestre]

OK. Thanks.

As it does not seem to be a one liner or a simple change I don't think i will time to work on this anytime soon.
However, happy to take a patch

[TheRealCuran]

OK; not sure if I have any time to work on it, but lets see.

As an aside: there is #135327, so there might be a chance for a simpler build, if the libclc developers can get that working.