Move more code to `RawVec::finish_grow` #147124

a1phyr · 2025-09-28T13:25:02Z

This move a branch and more code into the cold method finish_grow, which means that less code is inlined at each try_reserve site. Additionally, this reduces the amount of parameters, so they can all be passed by registers.

This move a branch and more code into the cold method `finish_grow`, which means that less code is inlined at each `try_reserve` site. Additionally, this reduces the amount of parameters, so they can all be passed by registers.

rustbot · 2025-09-28T13:25:07Z

r? @Mark-Simulacrum

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Kobzol · 2025-09-28T13:27:02Z

@bors try @rust-timer queue

Move more code to `RawVec::finish_grow`

rust-bors · 2025-09-28T15:42:48Z

☀️ Try build successful (CI)
Build commit: 006e85f (006e85fa61b49abee68e8f45daa550ffd4a90c84, parent: 4ffeda10e10d4fa0c8edbd0dd9642d8ae7d3e66e)

rust-timer · 2025-09-28T16:53:38Z

Finished benchmarking commit (006e85f): comparison URL.

Overall result: ❌✅ regressions and improvements - please read the text below

Benchmarking this pull request means it may be perf-sensitive – we'll automatically label it not fit for rolling up. You can override this, but we strongly advise not to, due to possible changes in compiler perf.

Next Steps: If you can justify the regressions found in this try perf run, please do so in sufficient writing along with @rustbot label: +perf-regression-triaged. If not, please fix the regressions and do another perf run. If its results are neutral or positive, the label will be automatically removed.

@bors rollup=never
@rustbot label: -S-waiting-on-perf +perf-regression

Instruction count

Our most reliable metric. Used to determine the overall result above. However, even this metric can be noisy.

	mean	range	count
Regressions ❌ (primary)	3.0%	[3.0%, 3.0%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.2%	[-0.3%, -0.1%]	3
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.6%	[-0.3%, 3.0%]	4

Max RSS (memory usage)

Results (primary 0.1%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	2.3%	[2.3%, 2.3%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-2.0%	[-2.0%, -2.0%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.1%	[-2.0%, 2.3%]	2

Cycles

Results (primary 2.4%, secondary -3.0%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	2.4%	[2.4%, 2.4%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-3.0%	[-3.0%, -3.0%]	2
All ❌✅ (primary)	2.4%	[2.4%, 2.4%]	1

Binary size

Results (primary -0.3%, secondary -0.2%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	0.0%	[0.0%, 0.0%]	1
Improvements ✅ (primary)	-0.3%	[-1.3%, -0.0%]	19
Improvements ✅ (secondary)	-0.2%	[-1.1%, -0.1%]	42
All ❌✅ (primary)	-0.3%	[-1.3%, -0.0%]	19

Bootstrap: 469.714s -> 468.998s (-0.15%)
Artifact size: 387.67 MiB -> 387.45 MiB (-0.06%)

Mark-Simulacrum · 2025-10-11T18:58:03Z

Seems like this is a small binary size win at the cost of a few instruction count/cycle regressions, but very small ones (including when looking at the aggregate across all our benchmarks).

@bors r+

bors · 2025-10-11T18:58:06Z

📌 Commit e52fe65 has been approved by Mark-Simulacrum

It is now in the queue for this repository.

bors · 2025-10-11T19:40:55Z

⌛ Testing commit e52fe65 with merge be0ade2...

bors · 2025-10-11T22:44:22Z

☀️ Test successful - checks-actions
Approved by: Mark-Simulacrum
Pushing be0ade2 to master...

github-actions · 2025-10-11T22:47:46Z

What is this?

This is an experimental post-merge analysis report that shows differences in test outcomes between the merged PR and its parent PR.

Comparing 360a3a4 (parent) -> be0ade2 (this PR)

Test differences

No test diffs found

Test dashboard

Run

cargo run --manifest-path src/ci/citool/Cargo.toml -- \
    test-dashboard be0ade2b602bdfe37a3cc259fcc79e8624dcba94 --output-dir test-dashboard

And then open test-dashboard/index.html in your browser to see an overview of all executed tests.

Job duration changes

aarch64-apple: 9434.6s -> 7663.7s (-18.8%)
x86_64-gnu-llvm-20-2: 4925.6s -> 5648.1s (14.7%)
dist-apple-various: 3635.3s -> 4101.9s (12.8%)
dist-s390x-linux: 5460.0s -> 4920.2s (-9.9%)
x86_64-msvc-2: 7258.5s -> 6656.4s (-8.3%)
x86_64-gnu-aux: 6605.1s -> 6079.8s (-8.0%)
dist-sparcv9-solaris: 5256.9s -> 4847.2s (-7.8%)
dist-x86_64-apple: 6654.0s -> 7150.9s (7.5%)
x86_64-gnu-llvm-20-3: 6645.9s -> 6173.0s (-7.1%)
test-various: 4664.1s -> 4332.9s (-7.1%)

How to interpret the job duration changes?

Job durations can vary a lot, based on the actual runner instance
that executed the job, system noise, invalidated caches, etc. The table above is provided
mostly for t-infra members, for simpler debugging of potential CI slow-downs.

rust-timer · 2025-10-11T23:54:57Z

Finished benchmarking commit (be0ade2): comparison URL.

Overall result: ✅ improvements - no action needed

@rustbot label: -perf-regression

Instruction count

Our most reliable metric. Used to determine the overall result above. However, even this metric can be noisy.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.2%	[-0.4%, -0.1%]	5
Improvements ✅ (secondary)	-0.1%	[-0.2%, -0.0%]	7
All ❌✅ (primary)	-0.2%	[-0.4%, -0.1%]	5

Max RSS (memory usage)

Results (secondary -1.0%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-1.0%	[-1.0%, -1.0%]	1
All ❌✅ (primary)	-	-	0

Cycles

Results (primary -2.2%, secondary 0.8%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	2.5%	[1.9%, 3.2%]	2
Improvements ✅ (primary)	-2.2%	[-2.2%, -2.2%]	1
Improvements ✅ (secondary)	-2.7%	[-2.7%, -2.7%]	1
All ❌✅ (primary)	-2.2%	[-2.2%, -2.2%]	1

Binary size

Results (primary -0.3%, secondary -0.2%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.3%	[-1.2%, -0.0%]	19
Improvements ✅ (secondary)	-0.2%	[-0.9%, -0.2%]	39
All ❌✅ (primary)	-0.3%	[-1.2%, -0.0%]	19

Bootstrap: 473.775s -> 472.888s (-0.19%)
Artifact size: 388.16 MiB -> 388.10 MiB (-0.01%)

Move more code to RawVec::finish_grow

e52fe65

This move a branch and more code into the cold method `finish_grow`, which means that less code is inlined at each `try_reserve` site. Additionally, this reduces the amount of parameters, so they can all be passed by registers.

rustbot assigned Mark-Simulacrum Sep 28, 2025

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 Sep 28, 2025

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rust-bors bot added a commit that referenced this pull request Sep 28, 2025

Auto merge of #147124 - a1phyr:improve_finish_grow, r=<try>

006e85f

Move more code to `RawVec::finish_grow`

rustbot added the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Sep 28, 2025

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rustbot added perf-regression Performance regression. and removed S-waiting-on-perf Status: Waiting on a perf run to be completed. labels Sep 28, 2025

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 Oct 11, 2025

bors added the merged-by-bors This PR was explicitly merged by bors. label Oct 11, 2025

bors merged commit be0ade2 into rust-lang:master Oct 11, 2025
12 checks passed

rustbot added this to the 1.92.0 milestone Oct 11, 2025

rustbot removed the perf-regression Performance regression. label Oct 11, 2025

github-actions bot mentioned this pull request Oct 21, 2025

Toolchain upgrade to nightly-2025-10-26 flux-rs/flux#1345

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Move more code to RawVec::finish_grow #147124

Move more code to RawVec::finish_grow #147124

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a1phyr commented Sep 28, 2025

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rust-timer commented Sep 28, 2025

Overall result: ❌✅ regressions and improvements - please read the text below

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Mark-Simulacrum commented Oct 11, 2025

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bors commented Oct 11, 2025

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github-actions bot commented Oct 11, 2025

Test differences

Job duration changes

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rust-timer commented Oct 11, 2025

Overall result: ✅ improvements - no action needed

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Move more code to `RawVec::finish_grow` #147124

Move more code to `RawVec::finish_grow` #147124