Without the overload constrain lowering would go with a default path which would later result in a crash in case if for example AMDGPU asm is inlined (for example v_ would be Unknown). Overload sets ConstraintType to be always RegClass for SPIR-V.
Without the overload constrain lowering would go with a default path which would later result in a crash in case if for example AMDGPU asm is inlined (for example v_ would be Unknown). Overload sets ConstraintType to be always RegClass for SPIR-V.