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Github Add NonZeroUn::is_power_of_two by scottmcm · Pull Request #81107 · rust-l...

 3 years ago
source link: https://github.com/rust-lang/rust/pull/81107
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scottmcm commented 14 days ago •

edited

This saves instructions on both new and old machines https://rust.godbolt.org/z/4fjTMz

  • On the default x64 target (with no fancy instructions available) it saves a few instructions by not needing to also check for zero.
  • On newer targets (with BMI1) it uses BLSR for super-short assembly.

This can be used for things like checks against alignments stored in NonZeroUsize.

EDIT: New demonstration now that this is available on nightly: https://rust.godbolt.org/z/7bPWxx


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