About

Many of the functions in math.bits translate directly to a small number of CPU instruction.  On other architectures the GO compiler inserts these code sequences directly into the calling function and there's no need to call a generic function that performs the computation using a sequence of bit manipulations.  This instrinsification of math/bits is not currently performed on riscv64, even though RVA22U64 gives us the instructions we need to do this.  In short we need to add riscv64 instrinsics to the math/bits package where appropriate.