Floating point rounding mode

It looks like the last discussion on rounding modes was in 2015.

  1. Can I set the rounding mode in Rust? Is it undefined behavior to change the rounding mode in a program?
  2. What is the status of AVX-512 intrinsics? I'd be sort of happy if I could just use intrinsics with explicit rounding modes, but it looks like these are still experimental.