From 698f8c2f01ea549d77d7dc3338a12e04c11057b9 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Wed, 17 Apr 2024 14:02:58 +0200 Subject: Adding upstream version 1.64.0+dfsg1. Signed-off-by: Daniel Baumann --- library/core/benches/iter.rs | 393 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 393 insertions(+) create mode 100644 library/core/benches/iter.rs (limited to 'library/core/benches/iter.rs') diff --git a/library/core/benches/iter.rs b/library/core/benches/iter.rs new file mode 100644 index 000000000..0abe20e4c --- /dev/null +++ b/library/core/benches/iter.rs @@ -0,0 +1,393 @@ +use core::iter::*; +use test::{black_box, Bencher}; + +#[bench] +fn bench_rposition(b: &mut Bencher) { + let it: Vec = (0..300).collect(); + b.iter(|| { + it.iter().rposition(|&x| x <= 150); + }); +} + +#[bench] +fn bench_skip_while(b: &mut Bencher) { + b.iter(|| { + let it = 0..100; + let mut sum = 0; + it.skip_while(|&x| { + sum += x; + sum < 4000 + }) + .all(|_| true); + }); +} + +#[bench] +fn bench_multiple_take(b: &mut Bencher) { + let mut it = (0..42).cycle(); + b.iter(|| { + let n = it.next().unwrap(); + for _ in 0..n { + it.clone().take(it.next().unwrap()).all(|_| true); + } + }); +} + +fn scatter(x: i32) -> i32 { + (x * 31) % 127 +} + +#[bench] +fn bench_max_by_key(b: &mut Bencher) { + b.iter(|| { + let it = 0..100; + it.map(black_box).max_by_key(|&x| scatter(x)) + }) +} + +// https://www.reddit.com/r/rust/comments/31syce/using_iterators_to_find_the_index_of_the_min_or/ +#[bench] +fn bench_max_by_key2(b: &mut Bencher) { + fn max_index_iter(array: &[i32]) -> usize { + array.iter().enumerate().max_by_key(|&(_, item)| item).unwrap().0 + } + + let mut data = vec![0; 1638]; + data[514] = 9999; + + b.iter(|| max_index_iter(&data)); +} + +#[bench] +fn bench_max(b: &mut Bencher) { + b.iter(|| { + let it = 0..100; + it.map(black_box).map(scatter).max() + }) +} + +pub fn copy_zip(xs: &[u8], ys: &mut [u8]) { + for (a, b) in ys.iter_mut().zip(xs) { + *a = *b; + } +} + +pub fn add_zip(xs: &[f32], ys: &mut [f32]) { + for (a, b) in ys.iter_mut().zip(xs) { + *a += *b; + } +} + +#[bench] +fn bench_zip_copy(b: &mut Bencher) { + let source = vec![0u8; 16 * 1024]; + let mut dst = black_box(vec![0u8; 16 * 1024]); + b.iter(|| copy_zip(&source, &mut dst)) +} + +#[bench] +fn bench_zip_add(b: &mut Bencher) { + let source = vec![1.; 16 * 1024]; + let mut dst = vec![0.; 16 * 1024]; + b.iter(|| add_zip(&source, &mut dst)); +} + +/// `Iterator::for_each` implemented as a plain loop. +fn for_each_loop(iter: I, mut f: F) +where + I: Iterator, + F: FnMut(I::Item), +{ + for item in iter { + f(item); + } +} + +/// `Iterator::for_each` implemented with `fold` for internal iteration. +/// (except when `by_ref()` effectively disables that optimization.) +fn for_each_fold(iter: I, mut f: F) +where + I: Iterator, + F: FnMut(I::Item), +{ + iter.fold((), move |(), item| f(item)); +} + +#[bench] +fn bench_for_each_chain_loop(b: &mut Bencher) { + b.iter(|| { + let mut acc = 0; + let iter = (0i64..1000000).chain(0..1000000).map(black_box); + for_each_loop(iter, |x| acc += x); + acc + }); +} + +#[bench] +fn bench_for_each_chain_fold(b: &mut Bencher) { + b.iter(|| { + let mut acc = 0; + let iter = (0i64..1000000).chain(0..1000000).map(black_box); + for_each_fold(iter, |x| acc += x); + acc + }); +} + +#[bench] +fn bench_for_each_chain_ref_fold(b: &mut Bencher) { + b.iter(|| { + let mut acc = 0; + let mut iter = (0i64..1000000).chain(0..1000000).map(black_box); + for_each_fold(iter.by_ref(), |x| acc += x); + acc + }); +} + +/// Helper to benchmark `sum` for iterators taken by value which +/// can optimize `fold`, and by reference which cannot. +macro_rules! bench_sums { + ($bench_sum:ident, $bench_ref_sum:ident, $iter:expr) => { + #[bench] + fn $bench_sum(b: &mut Bencher) { + b.iter(|| -> i64 { $iter.map(black_box).sum() }); + } + + #[bench] + fn $bench_ref_sum(b: &mut Bencher) { + b.iter(|| -> i64 { $iter.map(black_box).by_ref().sum() }); + } + }; +} + +bench_sums! { + bench_flat_map_sum, + bench_flat_map_ref_sum, + (0i64..1000).flat_map(|x| x..x+1000) +} + +bench_sums! { + bench_flat_map_chain_sum, + bench_flat_map_chain_ref_sum, + (0i64..1000000).flat_map(|x| once(x).chain(once(x))) +} + +bench_sums! { + bench_enumerate_sum, + bench_enumerate_ref_sum, + (0i64..1000000).enumerate().map(|(i, x)| x * i as i64) +} + +bench_sums! { + bench_enumerate_chain_sum, + bench_enumerate_chain_ref_sum, + (0i64..1000000).chain(0..1000000).enumerate().map(|(i, x)| x * i as i64) +} + +bench_sums! { + bench_filter_sum, + bench_filter_ref_sum, + (0i64..1000000).filter(|x| x % 3 == 0) +} + +bench_sums! { + bench_filter_chain_sum, + bench_filter_chain_ref_sum, + (0i64..1000000).chain(0..1000000).filter(|x| x % 3 == 0) +} + +bench_sums! { + bench_filter_map_sum, + bench_filter_map_ref_sum, + (0i64..1000000).filter_map(|x| x.checked_mul(x)) +} + +bench_sums! { + bench_filter_map_chain_sum, + bench_filter_map_chain_ref_sum, + (0i64..1000000).chain(0..1000000).filter_map(|x| x.checked_mul(x)) +} + +bench_sums! { + bench_fuse_sum, + bench_fuse_ref_sum, + (0i64..1000000).fuse() +} + +bench_sums! { + bench_fuse_chain_sum, + bench_fuse_chain_ref_sum, + (0i64..1000000).chain(0..1000000).fuse() +} + +bench_sums! { + bench_inspect_sum, + bench_inspect_ref_sum, + (0i64..1000000).inspect(|_| {}) +} + +bench_sums! { + bench_inspect_chain_sum, + bench_inspect_chain_ref_sum, + (0i64..1000000).chain(0..1000000).inspect(|_| {}) +} + +bench_sums! { + bench_peekable_sum, + bench_peekable_ref_sum, + (0i64..1000000).peekable() +} + +bench_sums! { + bench_peekable_chain_sum, + bench_peekable_chain_ref_sum, + (0i64..1000000).chain(0..1000000).peekable() +} + +bench_sums! { + bench_skip_sum, + bench_skip_ref_sum, + (0i64..1000000).skip(1000) +} + +bench_sums! { + bench_skip_chain_sum, + bench_skip_chain_ref_sum, + (0i64..1000000).chain(0..1000000).skip(1000) +} + +bench_sums! { + bench_skip_while_sum, + bench_skip_while_ref_sum, + (0i64..1000000).skip_while(|&x| x < 1000) +} + +bench_sums! { + bench_skip_while_chain_sum, + bench_skip_while_chain_ref_sum, + (0i64..1000000).chain(0..1000000).skip_while(|&x| x < 1000) +} + +bench_sums! { + bench_take_while_chain_sum, + bench_take_while_chain_ref_sum, + (0i64..1000000).chain(1000000..).take_while(|&x| x < 1111111) +} + +bench_sums! { + bench_cycle_take_sum, + bench_cycle_take_ref_sum, + (0..10000).cycle().take(1000000) +} + +bench_sums! { + bench_cycle_skip_take_sum, + bench_cycle_skip_take_ref_sum, + (0..100000).cycle().skip(1000000).take(1000000) +} + +bench_sums! { + bench_cycle_take_skip_sum, + bench_cycle_take_skip_ref_sum, + (0..100000).cycle().take(1000000).skip(100000) +} + +bench_sums! { + bench_skip_cycle_skip_zip_add_sum, + bench_skip_cycle_skip_zip_add_ref_sum, + (0..100000).skip(100).cycle().skip(100) + .zip((0..100000).cycle().skip(10)) + .map(|(a,b)| a+b) + .skip(100000) + .take(1000000) +} + +// Checks whether Skip> is as fast as Zip, Skip>, from +// https://users.rust-lang.org/t/performance-difference-between-iterator-zip-and-skip-order/15743 +#[bench] +fn bench_zip_then_skip(b: &mut Bencher) { + let v: Vec<_> = (0..100_000).collect(); + let t: Vec<_> = (0..100_000).collect(); + + b.iter(|| { + let s = v + .iter() + .zip(t.iter()) + .skip(10000) + .take_while(|t| *t.0 < 10100) + .map(|(a, b)| *a + *b) + .sum::(); + assert_eq!(s, 2009900); + }); +} +#[bench] +fn bench_skip_then_zip(b: &mut Bencher) { + let v: Vec<_> = (0..100_000).collect(); + let t: Vec<_> = (0..100_000).collect(); + + b.iter(|| { + let s = v + .iter() + .skip(10000) + .zip(t.iter().skip(10000)) + .take_while(|t| *t.0 < 10100) + .map(|(a, b)| *a + *b) + .sum::(); + assert_eq!(s, 2009900); + }); +} + +#[bench] +fn bench_filter_count(b: &mut Bencher) { + b.iter(|| (0i64..1000000).map(black_box).filter(|x| x % 3 == 0).count()) +} + +#[bench] +fn bench_filter_ref_count(b: &mut Bencher) { + b.iter(|| (0i64..1000000).map(black_box).by_ref().filter(|x| x % 3 == 0).count()) +} + +#[bench] +fn bench_filter_chain_count(b: &mut Bencher) { + b.iter(|| (0i64..1000000).chain(0..1000000).map(black_box).filter(|x| x % 3 == 0).count()) +} + +#[bench] +fn bench_filter_chain_ref_count(b: &mut Bencher) { + b.iter(|| { + (0i64..1000000).chain(0..1000000).map(black_box).by_ref().filter(|x| x % 3 == 0).count() + }) +} + +#[bench] +fn bench_partial_cmp(b: &mut Bencher) { + b.iter(|| (0..100000).map(black_box).partial_cmp((0..100000).map(black_box))) +} + +#[bench] +fn bench_lt(b: &mut Bencher) { + b.iter(|| (0..100000).map(black_box).lt((0..100000).map(black_box))) +} + +#[bench] +fn bench_trusted_random_access_adapters(b: &mut Bencher) { + let vec1: Vec<_> = (0usize..100000).collect(); + let vec2 = black_box(vec1.clone()); + b.iter(|| { + let mut iter = vec1 + .iter() + .copied() + .enumerate() + .map(|(idx, e)| idx.wrapping_add(e)) + .zip(vec2.iter().copied()) + .map(|(a, b)| a.wrapping_add(b)) + .fuse(); + let mut acc: usize = 0; + let size = iter.size(); + for i in 0..size { + // SAFETY: TRA requirements are satisfied by 0..size iteration and then dropping the + // iterator. + acc = acc.wrapping_add(unsafe { iter.__iterator_get_unchecked(i) }); + } + acc + }) +} -- cgit v1.2.3