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use core::ptr::NonNull;
use test::{Bencher, black_box};
enum Cache {
L1,
L2,
L3,
}
impl Cache {
fn size(&self) -> usize {
match self {
Cache::L1 => 1000, // 8kb
Cache::L2 => 10_000, // 80kb
Cache::L3 => 1_000_000, // 8Mb
}
}
}
fn binary_search<F>(b: &mut Bencher, cache: Cache, mapper: F)
where
F: Fn(usize) -> usize,
{
let size = cache.size();
let v = (0..size).map(&mapper).collect::<Vec<_>>();
let mut r = 0usize;
b.iter(move || {
// LCG constants from https://en.wikipedia.org/wiki/Numerical_Recipes.
r = r.wrapping_mul(1664525).wrapping_add(1013904223);
// Lookup the whole range to get 50% hits and 50% misses.
let i = mapper(r % size);
black_box(v.binary_search(&i).is_ok());
});
}
fn binary_search_worst_case(b: &mut Bencher, cache: Cache) {
let size = cache.size();
let mut v = vec![0; size];
let i = 1;
v[size - 1] = i;
b.iter(move || {
black_box(v.binary_search(&i).is_ok());
});
}
#[bench]
fn binary_search_l1(b: &mut Bencher) {
binary_search(b, Cache::L1, |i| i * 2);
}
#[bench]
fn binary_search_l2(b: &mut Bencher) {
binary_search(b, Cache::L2, |i| i * 2);
}
#[bench]
fn binary_search_l3(b: &mut Bencher) {
binary_search(b, Cache::L3, |i| i * 2);
}
#[bench]
fn binary_search_l1_with_dups(b: &mut Bencher) {
binary_search(b, Cache::L1, |i| i / 16 * 16);
}
#[bench]
fn binary_search_l2_with_dups(b: &mut Bencher) {
binary_search(b, Cache::L2, |i| i / 16 * 16);
}
#[bench]
fn binary_search_l3_with_dups(b: &mut Bencher) {
binary_search(b, Cache::L3, |i| i / 16 * 16);
}
#[bench]
fn binary_search_l1_worst_case(b: &mut Bencher) {
binary_search_worst_case(b, Cache::L1);
}
#[bench]
fn binary_search_l2_worst_case(b: &mut Bencher) {
binary_search_worst_case(b, Cache::L2);
}
#[bench]
fn binary_search_l3_worst_case(b: &mut Bencher) {
binary_search_worst_case(b, Cache::L3);
}
#[derive(Clone)]
struct Rgb(#[allow(dead_code)] u8, #[allow(dead_code)] u8, #[allow(dead_code)] u8);
impl Rgb {
fn gen(i: usize) -> Self {
Rgb(i as u8, (i as u8).wrapping_add(7), (i as u8).wrapping_add(42))
}
}
macro_rules! rotate {
($fn:ident, $n:expr, $mapper:expr) => {
#[bench]
fn $fn(b: &mut Bencher) {
let mut x = (0usize..$n).map(&$mapper).collect::<Vec<_>>();
b.iter(|| {
for s in 0..x.len() {
x[..].rotate_right(s);
}
black_box(x[0].clone())
})
}
};
}
rotate!(rotate_u8, 32, |i| i as u8);
rotate!(rotate_rgb, 32, Rgb::gen);
rotate!(rotate_usize, 32, |i| i);
rotate!(rotate_16_usize_4, 16, |i| [i; 4]);
rotate!(rotate_16_usize_5, 16, |i| [i; 5]);
rotate!(rotate_64_usize_4, 64, |i| [i; 4]);
rotate!(rotate_64_usize_5, 64, |i| [i; 5]);
macro_rules! swap_with_slice {
($fn:ident, $n:expr, $mapper:expr) => {
#[bench]
fn $fn(b: &mut Bencher) {
let mut x = (0usize..$n).map(&$mapper).collect::<Vec<_>>();
let mut y = ($n..($n * 2)).map(&$mapper).collect::<Vec<_>>();
let mut skip = 0;
b.iter(|| {
for _ in 0..32 {
x[skip..].swap_with_slice(&mut y[..($n - skip)]);
skip = black_box(skip + 1) % 8;
}
black_box((x[$n / 3].clone(), y[$n * 2 / 3].clone()))
})
}
};
}
swap_with_slice!(swap_with_slice_u8_30, 30, |i| i as u8);
swap_with_slice!(swap_with_slice_u8_3000, 3000, |i| i as u8);
swap_with_slice!(swap_with_slice_rgb_30, 30, Rgb::gen);
swap_with_slice!(swap_with_slice_rgb_3000, 3000, Rgb::gen);
swap_with_slice!(swap_with_slice_usize_30, 30, |i| i);
swap_with_slice!(swap_with_slice_usize_3000, 3000, |i| i);
swap_with_slice!(swap_with_slice_4x_usize_30, 30, |i| [i; 4]);
swap_with_slice!(swap_with_slice_4x_usize_3000, 3000, |i| [i; 4]);
swap_with_slice!(swap_with_slice_5x_usize_30, 30, |i| [i; 5]);
swap_with_slice!(swap_with_slice_5x_usize_3000, 3000, |i| [i; 5]);
#[bench]
fn fill_byte_sized(b: &mut Bencher) {
#[derive(Copy, Clone)]
struct NewType(#[allow(dead_code)] u8);
let mut ary = [NewType(0); 1024];
b.iter(|| {
let slice = &mut ary[..];
black_box(slice.fill(black_box(NewType(42))));
});
}
// Tests the ability of the compiler to recognize that only the last slice item is needed
// based on issue #106288
#[bench]
fn fold_to_last(b: &mut Bencher) {
let slice: &[i32] = &[0; 1024];
b.iter(|| black_box(slice).iter().fold(None, |_, r| Some(NonNull::from(r))));
}
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