RADV Vulkan Driver Adds Option For Sisched

The RADV Vulkan driver now has an option for being able to enable the LLVM SI machine scheduler.

The LLVM SI machine instruction scheduler for AMDGPU has in the past showed the potential for benefiting the performance of the RadeonSI OpenGL driver. With the RADV Vulkan driver also making use of the AMDGPU LLVM back-end, the optional "sisched" can be easily taken advantage of.

David Airlie has added a toggle for easily making use of the SI scheduler. While R600_DEBUG=sisched is the environment variable to set for using it with the RadeonSI Gallium3D driver, RADV_PERFTEST=sisched is the environment variable to now set if wanting to make use of it for testing purposes in RADV.

I'll run some benchmarks on my end shortly.