For SWAR algorithms, calculating floor(64/n) for 0 < n < 65 has always been crucial, so I spent a lot of time developing fast division algorithms. But since the Ryzen 7000 series, the fastest approach has been to simply cast 64/n to an integer.

I'm kind of sad that all those algorithms have become obsolete, but at the same time, I'm happy that integer division has finally become fast enough in hardware.