RADV ACO Can Now Handle More Shaders With Mesa 20.1-devel

Prolific ACO shader compiler back-end developer Timur Kristóf has managed to land his latest improvements in Mesa 20.1-devel for this alternative to the AMDGPU LLVM back-end supported so far by the RADV Vulkan driver.

This latest addition to ACO is support for compiling tessellation control/evaluation shaders. This expanded support around tessellation shaders required a fair amount of reworking but ultimately appears to be in order and now all shader stages with ACO in RADV are enabled.

This merge request that was honored today outlines all of the changes this round to ACO. There is still some additional optimizations and other improvements planned for a follow-on MR.

Timur's testing doesn't indicate any performance or functionality regressions from his ACO testing thus far. ACO is in increasingly great shape for this Valve-backed shader compiler and helps allow AMD Radeon graphics to perform even better for gaming on Linux. RADV+ACO isn't enabled by default but requires setting the RADV_PERFTEST=aco environment variable for activation. We'll see if any upcoming Mesa 20.x release opts for enabling ACO by default.