[Bug middle-end/50481] builtin to reverse the bit order

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=50481

--- Comment #11 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
The builtins I am going to implement to be similar to clang:
__builtin_bitreverse{8,16,32,64,g}

The g one is not part of clang but will be used for _BitInt types.