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Clean up Vec's benchmarks #83458

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Mar 30, 2021
Merged

Clean up Vec's benchmarks #83458

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93 changes: 25 additions & 68 deletions library/alloc/benches/vec.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -4,23 +4,13 @@ use test::{black_box, Bencher};

#[bench]
fn bench_new(b: &mut Bencher) {
b.iter(|| {
let v: Vec<u32> = Vec::new();
assert_eq!(v.len(), 0);
assert_eq!(v.capacity(), 0);
v
})
b.iter(|| Vec::<u32>::new())
}

fn do_bench_with_capacity(b: &mut Bencher, src_len: usize) {
b.bytes = src_len as u64;

b.iter(|| {
let v: Vec<u32> = Vec::with_capacity(src_len);
assert_eq!(v.len(), 0);
assert_eq!(v.capacity(), src_len);
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note that benchmarks are also executed when you run ./x.py test, i.e. they can double as test-cases. If you remove those asserts here because they get in the way of measuring things you'll have to check if there are roughtly equivalent proper tests somewhere.

They seem to be quite trivial, so hopefully this isn't the only place where this stuff is tested, but I'd still check.

v
})
b.iter(|| Vec::<u32>::with_capacity(src_len))
}

#[bench]
Expand All @@ -46,12 +36,7 @@ fn bench_with_capacity_1000(b: &mut Bencher) {
fn do_bench_from_fn(b: &mut Bencher, src_len: usize) {
b.bytes = src_len as u64;

b.iter(|| {
let dst = (0..src_len).collect::<Vec<_>>();
assert_eq!(dst.len(), src_len);
assert!(dst.iter().enumerate().all(|(i, x)| i == *x));
dst
})
b.iter(|| (0..src_len).collect::<Vec<_>>())
}

#[bench]
Expand All @@ -77,12 +62,7 @@ fn bench_from_fn_1000(b: &mut Bencher) {
fn do_bench_from_elem(b: &mut Bencher, src_len: usize) {
b.bytes = src_len as u64;

b.iter(|| {
let dst: Vec<usize> = repeat(5).take(src_len).collect();
assert_eq!(dst.len(), src_len);
assert!(dst.iter().all(|x| *x == 5));
dst
})
b.iter(|| repeat(5).take(src_len).collect::<Vec<usize>>())
}

#[bench]
Expand Down Expand Up @@ -110,12 +90,7 @@ fn do_bench_from_slice(b: &mut Bencher, src_len: usize) {

b.bytes = src_len as u64;

b.iter(|| {
let dst = src.clone()[..].to_vec();
assert_eq!(dst.len(), src_len);
assert!(dst.iter().enumerate().all(|(i, x)| i == *x));
dst
});
b.iter(|| src.as_slice().to_vec());
}

#[bench]
Expand Down Expand Up @@ -144,9 +119,7 @@ fn do_bench_from_iter(b: &mut Bencher, src_len: usize) {
b.bytes = src_len as u64;

b.iter(|| {
let dst: Vec<_> = FromIterator::from_iter(src.clone());
assert_eq!(dst.len(), src_len);
assert!(dst.iter().enumerate().all(|(i, x)| i == *x));
let dst: Vec<_> = FromIterator::from_iter(src.iter().cloned());
dst
});
}
Expand Down Expand Up @@ -180,8 +153,6 @@ fn do_bench_extend(b: &mut Bencher, dst_len: usize, src_len: usize) {
b.iter(|| {
let mut dst = dst.clone();
dst.extend(src.clone());
assert_eq!(dst.len(), dst_len + src_len);
assert!(dst.iter().enumerate().all(|(i, x)| i == *x));
dst
});
}
Expand Down Expand Up @@ -230,8 +201,6 @@ fn do_bench_extend_from_slice(b: &mut Bencher, dst_len: usize, src_len: usize) {
b.iter(|| {
let mut dst = dst.clone();
dst.extend_from_slice(&src);
assert_eq!(dst.len(), dst_len + src_len);
assert!(dst.iter().enumerate().all(|(i, x)| i == *x));
dst
});
}
Expand Down Expand Up @@ -290,12 +259,7 @@ fn do_bench_clone(b: &mut Bencher, src_len: usize) {

b.bytes = src_len as u64;

b.iter(|| {
let dst = src.clone();
assert_eq!(dst.len(), src_len);
assert!(dst.iter().enumerate().all(|(i, x)| i == *x));
dst
});
b.iter(|| src.clone());
}

#[bench]
Expand Down Expand Up @@ -329,8 +293,7 @@ fn do_bench_clone_from(b: &mut Bencher, times: usize, dst_len: usize, src_len: u

for _ in 0..times {
dst.clone_from(&src);
assert_eq!(dst.len(), src_len);
assert!(dst.iter().enumerate().all(|(i, x)| dst_len + i == *x));
dst = black_box(dst);
}
dst
});
Expand Down Expand Up @@ -463,11 +426,10 @@ macro_rules! bench_in_place {
fn $fname(b: &mut Bencher) {
b.iter(|| {
let src: Vec<$type> = black_box(vec![$init; $count]);
let mut sink = src.into_iter()
src.into_iter()
.enumerate()
.map(|(idx, e)| idx as $type ^ e)
.collect::<Vec<$type>>();
black_box(sink.as_mut_ptr())
.collect::<Vec<$type>>()
});
}
)+
Expand Down Expand Up @@ -527,7 +489,6 @@ fn bench_in_place_zip_recycle(b: &mut Bencher) {
.enumerate()
.map(|(i, (d, s))| d.wrapping_add(i as u8) ^ s)
.collect::<Vec<_>>();
assert_eq!(mangled.len(), 1000);
data = black_box(mangled);
});
}
Expand Down Expand Up @@ -614,23 +575,6 @@ fn bench_nest_chain_chain_collect(b: &mut Bencher) {
});
}

pub fn example_plain_slow(l: &[u32]) -> Vec<u32> {
let mut result = Vec::with_capacity(l.len());
result.extend(l.iter().rev());
result
}

pub fn map_fast(l: &[(u32, u32)]) -> Vec<u32> {
let mut result = Vec::with_capacity(l.len());
for i in 0..l.len() {
unsafe {
*result.get_unchecked_mut(i) = l[i].0;
result.set_len(i);
}
}
result
}

#[bench]
fn bench_range_map_collect(b: &mut Bencher) {
b.iter(|| (0..LEN).map(|_| u32::default()).collect::<Vec<_>>());
Expand Down Expand Up @@ -669,7 +613,11 @@ fn bench_rev_1(b: &mut Bencher) {
#[bench]
fn bench_rev_2(b: &mut Bencher) {
let data = black_box([0; LEN]);
b.iter(|| example_plain_slow(&data));
b.iter(|| {
let mut v = Vec::<u32>::with_capacity(data.len());
v.extend(data.iter().rev());
v
});
}

#[bench]
Expand All @@ -685,7 +633,16 @@ fn bench_map_regular(b: &mut Bencher) {
#[bench]
fn bench_map_fast(b: &mut Bencher) {
let data = black_box([(0, 0); LEN]);
b.iter(|| map_fast(&data));
b.iter(|| {
let mut result = Vec::with_capacity(data.len());
for i in 0..data.len() {
unsafe {
*result.get_unchecked_mut(i) = data[i].0;
result.set_len(i);
}
}
result
});
}

fn random_sorted_fill(mut seed: u32, buf: &mut [u32]) {
Expand Down