libclc was vendored at recipes/dev/llvm21/source/libclc/ as a
build artifact of the llvm21 fork. This promoted it from an
implicit Mesa dependency (the CLC bitcode Mesa consumes) to a
first-class local project, mirroring how tlc, redbear-*, cub, etc.
are organized per local/AGENTS.md.
Local layout follows the existing in-house pattern:
recipes/dev/libclc -> ../../local/recipes/dev/libclc
local/recipes/dev/libclc/recipe.toml
local/recipes/dev/libclc/source/ (vendored from llvm-project)
The recipe builds libclc as a host-side CMake project using the
cookbook-sysroot clang21 binary (not the cross-compiler) to compile
OpenCL kernels to .bc bitcode. Output targets are amdgcn, amdgcn-amdhsa,
r600, generic, and spirv — the union that Mesa's clc tool consumes
for the iris/radeonsi/llvmpipe drivers. ptx-nvidiacl and clspv are
excluded because they don't map onto any Mesa hardware driver.
The recipe also wires the cookbook's native-cmake generation with
an override that points CMAKE_C_COMPILER etc. at the cookbook
sysroot's clang-21 binary. This is needed because libclc must
run on the build host (output is bitcode, not a Redox binary),
and the cookbook's default cross-toolchain would link the build
against relibc instead of host glibc.
libclc.pc is installed at usr/lib/pkgconfig/, satisfying Mesa's
dependency('libclc') lookup. The .bc files are installed under
usr/share/clc/, which is what the libclc.pc libexecdir pointer
(libexecdir=<prefix>/share/clc) expects.
This is the prerequisite for re-enabling iris, radeonsi, and the
Intel Vulkan driver in the Mesa recipe (Phase 4-6 of
local/docs/3D-DRIVER-PLAN.md). With libclc available in the
cross-sysroot, mesa's meson '-Dwith_clc -> dependency(libclc)'
resolves and the gallium drivers compile.
