Suggest faster .contains() instead of .iter().any() for [u8] and [i8] slices
#13353
Labels
A-lint
Area: New lints
Comments
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If anyone wants to try it, run this with [dev-dependencies]
criterion = { version = "0.5", features = ["html_reports"] }
[[bench]]
name = "my_benchmark"
harness = false// benches/my_benchmark.rs
use std::hint::black_box;
use criterion::{criterion_group, criterion_main, Criterion};
#[inline(never)]
pub fn contains(values: &[u8]) -> bool {
values.contains(&10)
}
#[inline(never)]
pub fn has_any(values: &[u8]) -> bool {
values.iter().any(|x| *x == 10)
}
fn criterion_benchmark(c: &mut Criterion) {
let data = vec![20u8; 1000];
let slice = &data[..];
c.bench_function("ref_zero", |b| b.iter(|| contains(black_box(slice))));
c.bench_function("has_any", |b| b.iter(|| has_any(black_box(slice))));
}
criterion_group!(benches, criterion_benchmark);
criterion_main!(benches); |
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This is from specialization for |
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@Jarcho ah, thx, i missed the specialization. Thus, it makes perfect sense to do this as a lint for u8 and i8 |
nyurik
changed the title
.iter().any() with .contains().iter().any() with .contains()
nyurik
changed the title
.iter().any() with .contains().contains() instead of .iter().any() for [u8] and [i8] slices
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What it does
Suggest to replace
values.iter().any(|&x| x == 10)withvalues.contains(&10)as shown in the example for x beingu8or ani8. Contains uses specialization, thus gains 8-10x in performance.The generated assembly is significantly different too (see here).
Advantage
Drawbacks
Example
Could be written as:
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