Not just in theory. Rust does now mark almost all references as `noalias`, the exception being `&T` where `T` contains an `UnsafeCell`. The equivalent safe Rust

Not just in theory. Rust does now mark almost all references as `noalias`, the exception being `&T` where `T` contains an `UnsafeCell`. The equivalent safe Rust function signature[1] would have all four references marked `noalias`, even though the `input` and `matrix` slices could alias. How much the optimizer can take advantage of that is another matter, due to what you said. Doing a quick translation to more idiomatic Rust[2], it does hoist the accesses to `matrix` out of the hot loop, and does also seem to be a bit less moving stuff around compared to the C version, which I think is putting the `matrix` values in the right places, which Rust did before the loop. [1] fn transform(output: &mut [f32], input: &[f32], matrix: &[f32], n: &i32); [2] https://godbolt.org/z/5PPn3eh19 https://godbolt.org/z/5PPn3eh19