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vec_bench(stack value)
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use criterion::{criterion_group, criterion_main, Criterion}; | |
use rand::Rng; | |
/// # Safety | |
/// | |
/// * `ptr` must be [valid] for writes. | |
/// * `ptr` must be properly aligned. | |
#[inline(always)] | |
pub unsafe fn store_advance_aligned<T>(val: T, ptr: &mut *mut T) { | |
unsafe { | |
std::ptr::write(*ptr, val); | |
*ptr = ptr.add(1) | |
} | |
} | |
#[inline(always)] | |
pub unsafe fn store_advance<T>(val: &T, ptr: &mut *mut T) { | |
unsafe { | |
std::ptr::copy_nonoverlapping(val as *const T, *ptr, 1); | |
*ptr = ptr.add(1) | |
} | |
} | |
// /// # Safety | |
// /// | |
// /// * `(ptr as usize - vec.as_ptr() as usize) / std::mem::size_of::<T>()` must be | |
// /// less than or equal to the capacity of Vec. | |
#[inline(always)] | |
pub unsafe fn set_vec_len_by_ptr<T>(vec: &mut Vec<T>, ptr: *const T) { | |
unsafe { | |
vec.set_len((ptr as usize - vec.as_ptr() as usize) / std::mem::size_of::<T>()); | |
} | |
} | |
const N: usize = 1000; | |
const BATCH_SIZE: usize = 65536; | |
fn pointer_write() { | |
// avoid LLVM | |
let mut rng = rand::thread_rng(); | |
let random_idx: usize = rng.gen_range(0..BATCH_SIZE); | |
for round in 0..N { | |
let mut offsets: Vec<u64> = Vec::with_capacity(BATCH_SIZE); | |
let mut offsets_ptr = offsets.as_mut_ptr(); | |
let mut data_size = 0; | |
unsafe { | |
for i in 0..BATCH_SIZE { | |
data_size += (i + round) as u64; | |
store_advance_aligned::<u64>(data_size, &mut offsets_ptr); | |
} | |
set_vec_len_by_ptr(&mut offsets, offsets_ptr); | |
} | |
assert_eq!(offsets[random_idx], ((random_idx + 1) * round + random_idx * (random_idx + 1) / 2) as u64); | |
} | |
} | |
fn pointer_write_without_fn() { | |
// avoid LLVM | |
let mut rng = rand::thread_rng(); | |
let random_idx: usize = rng.gen_range(0..BATCH_SIZE); | |
for round in 0..N { | |
let mut offsets: Vec<u64> = Vec::with_capacity(BATCH_SIZE); | |
let mut offsets_ptr = offsets.as_mut_ptr(); | |
let mut data_size = 0; | |
unsafe { | |
for i in 0..BATCH_SIZE { | |
data_size += (i + round) as u64; | |
std::ptr::write(offsets_ptr, data_size); | |
offsets_ptr = offsets_ptr.add(1) | |
} | |
set_vec_len_by_ptr(&mut offsets, offsets_ptr); | |
} | |
assert_eq!(offsets[random_idx], ((random_idx + 1) * round + random_idx * (random_idx + 1) / 2) as u64); | |
} | |
} | |
fn slice_get_unchecked() { | |
// avoid LLVM | |
let mut rng = rand::thread_rng(); | |
let random_idx: usize = rng.gen_range(0..BATCH_SIZE); | |
for round in 0..N { | |
let mut offsets: Vec<u64> = Vec::with_capacity(BATCH_SIZE); | |
let mut data_size = 0; | |
unsafe { | |
let offsets = offsets.as_mut_slice(); | |
for i in 0..BATCH_SIZE { | |
data_size += (i + round) as u64; | |
*offsets.get_unchecked_mut(i) = data_size; | |
} | |
} | |
unsafe { | |
offsets.set_len(BATCH_SIZE); | |
} | |
assert_eq!(offsets[random_idx], ((random_idx + 1) * round + random_idx * (random_idx + 1) / 2) as u64); | |
} | |
} | |
fn vec_get_unchecked() { | |
// avoid LLVM | |
let mut rng = rand::thread_rng(); | |
let random_idx: usize = rng.gen_range(0..BATCH_SIZE); | |
for round in 0..N { | |
let mut offsets: Vec<u64> = Vec::with_capacity(BATCH_SIZE); | |
let mut data_size = 0; | |
unsafe { | |
for i in 0..BATCH_SIZE { | |
data_size += (i + round) as u64; | |
*offsets.get_unchecked_mut(i) = data_size; | |
} | |
offsets.set_len(BATCH_SIZE); | |
} | |
assert_eq!(offsets[random_idx], ((random_idx + 1) * round + random_idx * (random_idx + 1) / 2) as u64); | |
} | |
} | |
fn vec_push() { | |
// avoid LLVM | |
let mut rng = rand::thread_rng(); | |
let random_idx: usize = rng.gen_range(0..BATCH_SIZE); | |
for round in 0..N { | |
let mut offsets: Vec<u64> = Vec::with_capacity(BATCH_SIZE); | |
let mut data_size = 0; | |
for i in 0..BATCH_SIZE { | |
data_size += (i + round) as u64; | |
offsets.push(data_size); | |
} | |
assert_eq!(offsets[random_idx], ((random_idx + 1) * round + random_idx * (random_idx + 1) / 2) as u64); | |
} | |
} | |
fn pointer_copy() { | |
// avoid LLVM | |
let mut rng = rand::thread_rng(); | |
let random_idx: usize = rng.gen_range(0..BATCH_SIZE); | |
for round in 0..N { | |
let mut offsets: Vec<u64> = Vec::with_capacity(BATCH_SIZE); | |
let mut offsets_ptr = offsets.as_mut_ptr(); | |
let mut data_size = 0; | |
unsafe { | |
for i in 0..BATCH_SIZE { | |
data_size += (i + round) as u64; | |
store_advance::<u64>(&data_size, &mut offsets_ptr); | |
} | |
set_vec_len_by_ptr(&mut offsets, offsets_ptr); | |
} | |
assert_eq!(offsets[random_idx], ((random_idx + 1) * round + random_idx * (random_idx + 1) / 2) as u64); | |
} | |
} | |
fn extend_from_into_iter() { | |
// avoid LLVM | |
let mut rng = rand::thread_rng(); | |
let random_idx: usize = rng.gen_range(0..BATCH_SIZE); | |
for round in 0..N { | |
let mut offsets: Vec<u64> = Vec::with_capacity(BATCH_SIZE); | |
let mut data_size = 0; | |
offsets.extend((0..BATCH_SIZE).into_iter().map(|i| { data_size += (i + round) as u64; data_size })); | |
assert_eq!(offsets[random_idx], ((random_idx + 1) * round + random_idx * (random_idx + 1) / 2) as u64); | |
} | |
} | |
fn extend_from_iter() { | |
// avoid LLVM | |
let mut rng = rand::thread_rng(); | |
let random_idx: usize = rng.gen_range(0..BATCH_SIZE); | |
for round in 0..N { | |
let mut offsets: Vec<u64> = Vec::with_capacity(BATCH_SIZE); | |
let mut data_size = 0; | |
offsets.extend((0..BATCH_SIZE).map(|i| { data_size += (i + round) as u64; data_size })); | |
assert_eq!(offsets[random_idx], ((random_idx + 1) * round + random_idx * (random_idx + 1) / 2) as u64); | |
} | |
} | |
fn bench_vec(c: &mut Criterion) { | |
c.bench_function("pointer_write", |b| b.iter(|| pointer_write())); | |
c.bench_function("pointer_write_without_fn", |b| b.iter(|| pointer_write_without_fn())); | |
c.bench_function("slice_get_unchecked", |b| b.iter(|| slice_get_unchecked())); | |
c.bench_function("vec_get_unchecked", |b| b.iter(|| vec_get_unchecked())); | |
c.bench_function("pointer_copy", |b| b.iter(|| pointer_copy())); | |
c.bench_function("extend_from_into_iter", |b| b.iter(|| extend_from_into_iter())); | |
c.bench_function("extend_from_iter", |b| b.iter(|| extend_from_iter())); | |
c.bench_function("vec_push", |b| b.iter(|| vec_push())); | |
} | |
criterion_group!(benches, bench_vec); | |
criterion_main!(benches); |
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