[Bug tree-optimization/83171] __builtin_popcountl ((unsigned long long)unsigned_var) is not being optimized to __builtin_popcount (unsigned_var)

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83171

--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
A match.pd pattern would fix that I guess.  Similarly we can elide
conversions of args to ffs and ctz.