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Fix benchmarks in library/core with black_box #107598

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Merged
merged 1 commit into from
Feb 3, 2023
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Fix benchmarks in library/core with black_box #107598

merged 1 commit into from
Feb 3, 2023

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chenyukang
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Fixes #107590

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rustbot commented Feb 2, 2023

r? @thomcc

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@rustbot rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-libs Relevant to the library team, which will review and decide on the PR/issue. labels Feb 2, 2023
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rustbot commented Feb 2, 2023

Hey! It looks like you've submitted a new PR for the library teams!

If this PR contains changes to any rust-lang/rust public library APIs then please comment with @rustbot label +T-libs-api -T-libs to tag it appropriately. If this PR contains changes to any unstable APIs please edit the PR description to add a link to the relevant API Change Proposal or create one if you haven't already. If you're unsure where your change falls no worries, just leave it as is and the reviewer will take a look and make a decision to forward on if necessary.

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gendx
gendx reviewed Feb 2, 2023
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library/core/benches/char/methods.rs Outdated

const CHARS: [char; 9] = ['0', 'x', '2', '5', 'A', 'f', '7', '8', '9'];
const RADIX: [u32; 5] = [2, 8, 10, 16, 32];

#[bench]
fn bench_to_digit_radix_2(b: &mut Bencher) {
b.iter(|| CHARS.iter().cycle().take(10_000).map(|c| c.to_digit(2)).min())
b.iter(|| black_box(CHARS.iter().cycle().take(10_000).map(|c| black_box(c).to_digit(2)).min()))
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There is no need to put a black_box on the output, as it is automatically added by the Bencher interface: https://github.com/rust-lang/rust/blob/1.67.0/library/test/src/bench.rs#L117. The important part (for the output) is that the lambda function passed as argument to .iter() returns a non-() result (which is already the case here).

The black_box is definitely relevant for the input though :)

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thomcc commented Feb 2, 2023

I agree with @gendx's comment. Can you move black_box to be on the inputs only? (Then comment with at-rustbot ready to put it back in my queue).

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@rustbot rustbot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Feb 2, 2023
@chenyukang chenyukang force-pushed the yukang/fix-core-bench branch from 080e851 to fe84cec Compare February 3, 2023 01:21
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@rustbot ready

@rustbot rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Feb 3, 2023
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thomcc commented Feb 3, 2023

Looks good.

@bors r+ rollup

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bors commented Feb 3, 2023

📌 Commit fe84cec has been approved by thomcc

It is now in the queue for this repository.

@bors bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Feb 3, 2023
@matthiaskrgr matthiaskrgr mentioned this pull request Feb 3, 2023
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bors added a commit to rust-lang-ci/rust that referenced this pull request Feb 3, 2023
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Auto merge of rust-lang#107625 - matthiaskrgr:rollup-xr9oldy, r=matth…
7c46fb2 
…iaskrgr

Rollup of 6 pull requests

Successful merges:

 - rust-lang#106575 (Suggest `move` in nested closure when appropriate)
 - rust-lang#106805 (Suggest `{var:?}` when finding `{?:var}` in inline format strings)
 - rust-lang#107500 (Add tests to assert current behavior of large future sizes)
 - rust-lang#107598 (Fix benchmarks in library/core with black_box)
 - rust-lang#107602 (Parse and recover from type ascription in patterns)
 - rust-lang#107608 (Use triple rather than arch for fuchsia test-runner)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup
@bors bors merged commit 8601551 into rust-lang:master Feb 3, 2023
@rustbot rustbot added this to the 1.69.0 milestone Feb 3, 2023
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Successfully merging this pull request may close these issues.

Wrong benchmarks in library/core/benches/char/methods.rs and possibly other places
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