Hi, I believe they can be done for 32 bit platforms also with the multiword division in Knuth https://skanthak.homepage.t-online.de/division.html what I've chosen for fallback if not x86_64 platform.

I will try to implement the same optimizations in Rust in the upcoming weeks

UPD And we opened an issue :) https://github.com/rust-lang/compiler-builtins/issues/368