rust/library/alloc
bors af9b508e1d Auto merge of #88717 - tabokie:vecdeque-fast-append, r=m-ou-se
Optimize VecDeque::append

Optimize `VecDeque::append` to do unsafe copy rather than iterating through each element.

On my `Intel(R) Xeon(R) CPU E5-2630 v4 @ 2.20GHz`, the benchmark shows 37% improvements:
```
Master:
custom-bench vec_deque_append 583164 ns/iter
custom-bench vec_deque_append 550040 ns/iter

Patched:
custom-bench vec_deque_append 349204 ns/iter
custom-bench vec_deque_append 368164 ns/iter
```

Additional notes on the context: this is the third attempt to implement a non-trivial version of `VecDeque::append`, the last two are reverted due to unsoundness or regression, see:
- https://github.com/rust-lang/rust/pull/52553, reverted in https://github.com/rust-lang/rust/pull/53571
- https://github.com/rust-lang/rust/pull/53564, reverted in https://github.com/rust-lang/rust/pull/54851

Both cases are covered by existing tests.

Signed-off-by: tabokie <xy.tao@outlook.com>
2021-10-15 12:51:31 +00:00
..
benches Rollup merge of #88452 - xu-cheng:vecdeque-from-array, r=m-ou-se 2021-10-04 13:58:08 -07:00
src Auto merge of #88717 - tabokie:vecdeque-fast-append, r=m-ou-se 2021-10-15 12:51:31 +00:00
tests Rollup merge of #87993 - kornelski:try_reserve_stable, r=joshtriplett 2021-10-04 21:12:33 -07:00
Cargo.toml rfc3052: Remove authors field from Cargo manifests 2021-07-29 14:56:05 -07:00