Generate only the basic implementations necessary to be able to operate efficiently on 128-bit
vectors on this platfrom. For x86-64, that would mean SSE2 and AVX.
Generate only the basic implementations necessary to be able to operate efficiently on 256-bit
vectors on this platfrom. For x86-64, that would mean SSE2, AVX, and AVX2.
Vec4 functions which may not be implemented yet for all Vec4 types.
NOTE: functions in this trait may be moved to Vec4 in any patch release. To avoid breakage,
import Vec4Ext only together with Vec4, and don’t qualify its methods.