Conflicts with !450 but can probably go upstream before it since backend changes here are minimal.
-- v6: vkd3d-shader/dxil: Handle the DXIL SWITCH instruction. vkd3d-shader: Rename shader_instruction_array_add_icb() to shader_instruction_array_add_opaque_param(). vkd3d-shader/dxil: Handle the DXIL PHI instruction. vkd3d-shader/dxil: Handle the DXIL BR instruction conditional variant. vkd3d-shader/dxil: Handle the DXIL BR instruction unconditional variant.