Prototype:
                     
i32 @__nv_popcll(i64 %x) 
Description:
                     
                     Count the number of bits that are set to 1 in x.
                     
                     
                     Returns:
                     Returns a value between 0 and 64 inclusive representing the number of set bits. 
                     
                     Library Availability:
                     
                     Compute 2.0: Yes
                     Compute 3.0: Yes
                     Compute 3.5: Yes