code generation for bitwise shift and rotate
code generation for bitwise shift and rotate

Ignore-this: 65e295e4642b8298383eb42d550c813b
- may be prudent to modify the front-end to expose left/right primops, rather
  than having the generalised version and assuming compiler optimisation

darcs-hash:20100622052234-dcabc-f36c749fb8cf9d458f3f8b27eddbbac9bac64f87.gz

robeverest/accelerate,sjfloat/accelerate,robeverest/accelerate,wilbowma/accelerate,wilbowma/accelerate,rrnewton/accelerate