With https://github.com/rust-lang/rust/pull/121793 and https://github.com/rust-lang/rust/pull/118217, most float functions are now documented to have varying precision, so using host floats for them in Miri is actually fine. The only exceptions are mul_add (tracked at https://github.com/rust-lang/miri/issues/2995) and sqrt -- those guarantee an infinite-precision result, so we should ideally use softfloats. (That said, using host floats is not wrong here since the host functions are in fact guaranteeing the infinite-precision result we are supposed to be emulating. Still, it seems cleaner to use softfloats for everything where precision is guaranteed.)
With https://github.com/rust-lang/rust/pull/121793 and https://github.com/rust-lang/rust/pull/118217, most float functions are now documented to have varying precision, so using host floats for them in Miri is actually fine. The only exceptions are mul_add (tracked at https://github.com/rust-lang/miri/issues/2995) and sqrt -- those guarantee an infinite-precision result, so we should ideally use softfloats. (That said, using host floats is not wrong here since the host functions are in fact guaranteeing the infinite-precision result we are supposed to be emulating. Still, it seems cleaner to use softfloats for everything where precision is guaranteed.)
This is blocked on https://github.com/rust-lang/rustc_apfloat/issues/14.