rust/src/libcore/tests, branch try

mv std libs to library/

2020-07-28T00:51:13+00:00

Auto merge of #74510 - LukasKalbertodt:fix-range-from-index-panic, r=hanna-kruppe

2020-07-25T16:27:24+00:00

Fix panic message when `RangeFrom` index is out of bounds Before, the `Range` method was called with `end = slice.len()`. Unfortunately, because `Range::index` first checks the order of the indices (start has to be smaller than end), an out of bounds index leads to `core::slice::slice_index_order_fail` being called. This prints the message 'slice index starts at 27 but ends at 10', which is worse than 'index 27 out of range for slice of length 10'. This is not only useful to normal users reading panic messages, but also for people inspecting assembly and being confused by `slice_index_order_fail` calls. You can see the produced assembly [here](https://rust.godbolt.org/z/GzMGWf) and try on Playground [here](https://play.rust-lang.org/?version=stable&mode=debug&edition=2018&gist=aada5996b2f3848075a6d02cf4055743). (By the way. this is only about which panic function is called; I'm pretty sure it does not improve anything about performance).

Rollup merge of #74367 - Neutron3529:patch-1, r=nagisa

2020-07-24T17:01:30+00:00

Rearrange the pipeline of `pow` to gain efficiency The check of the `exp` parameter seems useless if we execute the while-loop more than once. The original implementation of `pow` function using one more comparison if the `exp==0` and may break the pipeline of the cpu, which may generate a slower code. The performance gap between the old and the new implementation may be small, but IMO, at least the newer one looks more beautiful. --- bench prog: ``` #![feature(test)] extern crate test; #[macro_export]macro_rules! timing{ ($a:expr)=>{let time=std::time::Instant::now();{$a;}print!("{:?} ",time.elapsed())}; ($a:expr,$b:literal)=>{let time=std::time::Instant::now();let mut a=0;for _ in 0..$b{a^=$a;}print!("{:?} {} ",time.elapsed(),a)} } #[inline] pub fn pow_rust(x:i64, mut exp: u32) -> i64 { let mut base = x; let mut acc = 1; while exp > 1 { if (exp & 1) == 1 { acc = acc * base; } exp /= 2; base = base * base; } if exp == 1 { acc = acc * base; } acc } #[inline] pub fn pow_new(x:i64, mut exp: u32) -> i64 { if exp==0{ 1 }else{ let mut base = x; let mut acc = 1; while exp > 1 { if (exp & 1) == 1 { acc = acc * base; } exp >>= 1; base = base * base; } acc * base } } fn main(){ let a=2i64; let b=1_u32; println!(); timing!(test::black_box(a).pow(test::black_box(b)),100000000); timing!(pow_new(test::black_box(a),test::black_box(b)),100000000); timing!(pow_rust(test::black_box(a),test::black_box(b)),100000000); println!(); timing!(test::black_box(a).pow(test::black_box(b)),100000000); timing!(pow_new(test::black_box(a),test::black_box(b)),100000000); timing!(pow_rust(test::black_box(a),test::black_box(b)),100000000); println!(); timing!(test::black_box(a).pow(test::black_box(b)),100000000); timing!(pow_new(test::black_box(a),test::black_box(b)),100000000); timing!(pow_rust(test::black_box(a),test::black_box(b)),100000000); println!(); timing!(test::black_box(a).pow(test::black_box(b)),100000000); timing!(pow_new(test::black_box(a),test::black_box(b)),100000000); timing!(pow_rust(test::black_box(a),test::black_box(b)),100000000); println!(); timing!(test::black_box(a).pow(test::black_box(b)),100000000); timing!(pow_new(test::black_box(a),test::black_box(b)),100000000); timing!(pow_rust(test::black_box(a),test::black_box(b)),100000000); println!(); timing!(test::black_box(a).pow(test::black_box(b)),100000000); timing!(pow_new(test::black_box(a),test::black_box(b)),100000000); timing!(pow_rust(test::black_box(a),test::black_box(b)),100000000); println!(); timing!(test::black_box(a).pow(test::black_box(b)),100000000); timing!(pow_new(test::black_box(a),test::black_box(b)),100000000); timing!(pow_rust(test::black_box(a),test::black_box(b)),100000000); println!(); timing!(test::black_box(a).pow(test::black_box(b)),100000000); timing!(pow_new(test::black_box(a),test::black_box(b)),100000000); timing!(pow_rust(test::black_box(a),test::black_box(b)),100000000); println!(); } ``` bench in my laptop: ``` neutron@Neutron:/me/rust$ rc commit.rs rustc commit.rs && ./commit 3.978419716s 0 4.079765171s 0 3.964630622s 0 3.997127013s 0 4.260304804s 0 3.997638211s 0 3.963195544s 0 4.11657718s 0 4.176054164s 0 3.830128579s 0 3.980396122s 0 3.937258567s 0 3.986055948s 0 4.127804162s 0 4.018943411s 0 4.185568857s 0 4.217512517s 0 3.98313603s 0 3.863018225s 0 4.030447988s 0 3.694878237s 0 4.206987927s 0 4.137608047s 0 4.115564664s 0 neutron@Neutron:/me/rust$ rc commit.rs -O rustc commit.rs -O && ./commit 162.111993ms 0 165.107125ms 0 166.26924ms 0 175.20479ms 0 205.062565ms 0 176.278791ms 0 174.408975ms 0 166.526899ms 0 201.857604ms 0 146.190062ms 0 168.592821ms 0 154.61411ms 0 199.678912ms 0 168.411598ms 0 162.129996ms 0 147.420765ms 0 209.759326ms 0 154.807907ms 0 165.507134ms 0 188.476239ms 0 157.351524ms 0 121.320123ms 0 126.401229ms 0 114.86428ms 0 ```

Rearrange the pipeline of `pow` to gain efficiency

2020-07-23T06:55:15+00:00

The check of the `exp` parameter seems useless if we execute the while-loop more than once. The original implementation of `pow` function using one more comparison if the `exp==0` and may break the pipeline of the cpu, which may generate a slower code. The performance gap between the old and the new implementation may be small, but IMO, at least the newer one looks more beautiful. --- bench prog: ``` extern crate test; ($a:expr)=>{let time=std::time::Instant::now();{$a;}print!("{:?} ",time.elapsed())}; ($a:expr,$b:literal)=>{let time=std::time::Instant::now();let mut a=0;for _ in 0..$b{a^=$a;}print!("{:?} {} ",time.elapsed(),a)} } pub fn pow_rust(x:i64, mut exp: u32) -> i64 { let mut base = x; let mut acc = 1; while exp > 1 { if (exp & 1) == 1 { acc = acc * base; } exp /= 2; base = base * base; } if exp == 1 { acc = acc * base; } acc } pub fn pow_new(x:i64, mut exp: u32) -> i64 { if exp==0{ 1 }else{ let mut base = x; let mut acc = 1; while exp > 1 { if (exp & 1) == 1 { acc = acc * base; } exp >>= 1; base = base * base; } acc * base } } fn main(){ let a=2i64; let b=1_u32; println!(); timing!(test::black_box(a).pow(test::black_box(b)),100000000); timing!(pow_new(test::black_box(a),test::black_box(b)),100000000); timing!(pow_rust(test::black_box(a),test::black_box(b)),100000000); println!(); timing!(test::black_box(a).pow(test::black_box(b)),100000000); timing!(pow_new(test::black_box(a),test::black_box(b)),100000000); timing!(pow_rust(test::black_box(a),test::black_box(b)),100000000); println!(); timing!(test::black_box(a).pow(test::black_box(b)),100000000); timing!(pow_new(test::black_box(a),test::black_box(b)),100000000); timing!(pow_rust(test::black_box(a),test::black_box(b)),100000000); println!(); timing!(test::black_box(a).pow(test::black_box(b)),100000000); timing!(pow_new(test::black_box(a),test::black_box(b)),100000000); timing!(pow_rust(test::black_box(a),test::black_box(b)),100000000); println!(); timing!(test::black_box(a).pow(test::black_box(b)),100000000); timing!(pow_new(test::black_box(a),test::black_box(b)),100000000); timing!(pow_rust(test::black_box(a),test::black_box(b)),100000000); println!(); timing!(test::black_box(a).pow(test::black_box(b)),100000000); timing!(pow_new(test::black_box(a),test::black_box(b)),100000000); timing!(pow_rust(test::black_box(a),test::black_box(b)),100000000); println!(); timing!(test::black_box(a).pow(test::black_box(b)),100000000); timing!(pow_new(test::black_box(a),test::black_box(b)),100000000); timing!(pow_rust(test::black_box(a),test::black_box(b)),100000000); println!(); timing!(test::black_box(a).pow(test::black_box(b)),100000000); timing!(pow_new(test::black_box(a),test::black_box(b)),100000000); timing!(pow_rust(test::black_box(a),test::black_box(b)),100000000); println!(); } ``` bench in my laptop: ``` neutron@Neutron:/me/rust$ rc commit.rs rustc commit.rs && ./commit 3.978419716s 0 4.079765171s 0 3.964630622s 0 3.997127013s 0 4.260304804s 0 3.997638211s 0 3.963195544s 0 4.11657718s 0 4.176054164s 0 3.830128579s 0 3.980396122s 0 3.937258567s 0 3.986055948s 0 4.127804162s 0 4.018943411s 0 4.185568857s 0 4.217512517s 0 3.98313603s 0 3.863018225s 0 4.030447988s 0 3.694878237s 0 4.206987927s 0 4.137608047s 0 4.115564664s 0 neutron@Neutron:/me/rust$ rc commit.rs -O rustc commit.rs -O && ./commit 162.111993ms 0 165.107125ms 0 166.26924ms 0 175.20479ms 0 205.062565ms 0 176.278791ms 0 174.408975ms 0 166.526899ms 0 201.857604ms 0 146.190062ms 0 168.592821ms 0 154.61411ms 0 199.678912ms 0 168.411598ms 0 162.129996ms 0 147.420765ms 0 209.759326ms 0 154.807907ms 0 165.507134ms 0 188.476239ms 0 157.351524ms 0 121.320123ms 0 126.401229ms 0 114.86428ms 0 ``` delete an unnecessary semicolon... Sorry for the typo. delete trailing whitespace Sorry, too.. Sorry for the missing... I checked all the implementations, and finally found that there is one function that does not check whether `exp == 0` add extra tests add extra tests. finished adding the extra tests to prevent further typo add pow(2) to negative exp add whitespace. add whitespace add whitespace delete extra line

Fix panic message when `RangeFrom` index is out of bounds

2020-07-19T14:11:07+00:00

Before, the `Range` method was called with `end = slice.len()`. Unfortunately, because `Range::index` first checks the order of the indices (start has to be smaller than end), an out of bounds index leads to `core::slice::slice_index_order_fail` being called. This prints the message 'slice index starts at 27 but ends at 10', which is worse than 'index 27 out of range for slice of length 10'. This is not only useful to normal users reading panic messages, but also for people inspecting assembly and being confused by `slice_index_order_fail` calls.

integrate Lazy into std layout

2020-07-16T21:25:32+00:00

This commit refactors the initial implementation to fit into std and makes some other changes: - use MaybeUninit internally in SyncOnceCell - correctly impl Drop for lazy::Once - port Lazy::take from once_cell from: https://github.com/matklad/once_cell/pull/100 Co-Authored-By: Paul Dicker

Rollup merge of #74066 - thomcc:optimize-is-ascii, r=nagisa

2020-07-11T15:53:16+00:00

Optimize is_ascii for str and [u8]. This optimizes the `is_ascii` function for `[u8]` and `str`. I've been surprised this wasn't done for a while, so I just did it. Benchmarks comparing before/after look like: ``` test ascii::long_readonly::is_ascii_slice_iter_all ... bench: 174 ns/iter (+/- 79) = 40172 MB/s test ascii::long_readonly::is_ascii_slice_libcore ... bench: 16 ns/iter (+/- 5) = 436875 MB/s test ascii::medium_readonly::is_ascii_slice_iter_all ... bench: 12 ns/iter (+/- 3) = 2666 MB/s test ascii::medium_readonly::is_ascii_slice_libcore ... bench: 2 ns/iter (+/- 0) = 16000 MB/s test ascii::short_readonly::is_ascii_slice_iter_all ... bench: 3 ns/iter (+/- 0) = 2333 MB/s test ascii::short_readonly::is_ascii_slice_libcore ... bench: 4 ns/iter (+/- 0) = 1750 MB/s ``` (Taken on a x86_64 macbook 2.9 GHz Intel Core i9 with 6 cores) Where `is_ascii_slice_iter_all` is the old version, and `is_ascii_slice_libcore` is the new. I tried to document the code well, so hopefully it's understandable. It has fairly exhaustive tests ensuring size/align doesn't get violated -- because `miri` doesn't really help a lot for this sort of code right now, I tried to `debug_assert` all the safety invariants I'm depending on. (Of course, none of them are required for correctness or soundness -- just allows us to test that this sort of pointer manipulation is sound and such). Anyway, thanks. Let me know if you have questions/desired changes.

Rollup merge of #73887 - DutchGhost:master, r=oli-obk

2020-07-11T06:26:28+00:00

stabilize const mem::forget Stabilizes const `mem::forget` as implemented in https://github.com/rust-lang/rust/pull/69617 and tracked in https://github.com/rust-lang/rust/issues/69616. Closes https://github.com/rust-lang/rust/issues/69616

Optimize is_ascii for &str and &[u8]

2020-07-05T17:23:50+00:00

Deny unsafe ops in unsafe fns, part 3

2020-06-30T15:06:16+00:00