OpenCL on amdgpu for Arch, also in the AUR.
This package allows the usage of AMD's proprietary user-space OpenCL driver along with the free amdgpu stack. It should work with upstream amdgpu and Mesa. Inspired by this blog post.
This should work with amdgpu-enabled GCN GPUs. Newer GPUs, starting with Vega (GCN Gen. 5+), support OpenCL via PAL and might work since commit f5838ef too, however I don't have the hardware to test it.
If you are using SI (Southern Islands, GCN Gen. 1) or CIK (Sea Islands, GCN Gen. 2), you'll need to enable the amdgpu and disable the radeon kernel module. Check the Arch Wiki for the exact steps.
Currently tested with Kernel 4.16 and Hawaii. Blender Cycles, Luxmark, F@H and ethminer seem to work without any problems.
You are not getting Vulkan support, faster 3D rendering or unicorns.
If you are looking for the full amdgpu-pro stack, including proprietary OpenGL and Vulkan implementations, move over to the AUR.
Expect maintenance of this package to be dropped when there is free OpenCL support on top of the ROC stack or the PAL.