add note about rustc

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nora 2022-07-23 21:17:54 +02:00
parent c73b099eb7
commit 6632848833

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@ -212,7 +212,7 @@ There is one clear potential benefit from this box behaviour: ✨Optimizations
that can bring clear performance wins (for `noalias` on `&mut T`, those were measureable). So the only question remains: that can bring clear performance wins (for `noalias` on `&mut T`, those were measureable). So the only question remains:
**How much performance does `noalias` on `Box<T>` give us now, and how many potential performance improvements could we get in the **How much performance does `noalias` on `Box<T>` give us now, and how many potential performance improvements could we get in the
future?** For the latter, there is no simple answer. For the former, there is. `rustc` has [_no_ performance improvements](https://github.com/rust-lang/rust/pull/99527) future?** For the latter, there is no simple answer. For the former, there is. `rustc` has [_no_ performance improvements](https://github.com/rust-lang/rust/pull/99527)
from being compiled with `noalias` on `Box<T>`. from being compiled with `noalias` on `Box<T>`, but this isn't really representative since rustc mostly uses arenas instead of box internally.
I have also benchmarked a few crates from the ecosystem with and without noalias on box, and the [results](https://gist.github.com/Nilstrieb/9a0751fb9fd1044a30ab55cef9a7d335) I have also benchmarked a few crates from the ecosystem with and without noalias on box, and the [results](https://gist.github.com/Nilstrieb/9a0751fb9fd1044a30ab55cef9a7d335)
were inconclusive. (At the time of writing, only regex-syntax, tokio, and syn have been benchmarked.) regex-syntax showed no changes. Tokio showed a few improvements without noalias were inconclusive. (At the time of writing, only regex-syntax, tokio, and syn have been benchmarked.) regex-syntax showed no changes. Tokio showed a few improvements without noalias