rustdoc: microoptimize render_item, move stuff out of common path

[lolbinarycat]

No description provided.

[lolbinarycat]

@bors2 try @rust-timer queue

[rust-bors]

💥 Test timed out after 21600s

[lolbinarycat]

Well that's weird.

@bors try

[rust-bors]

☀️ Try build successful (CI)
Build commit: 6b58920 (6b589205722c3dd266a9917cb1ea3210eda969db, parent: af5c5b74c8f2c0b1dfd9a201453bf2df538e93e0)

[rust-timer]

Finished benchmarking commit (6b58920): comparison URL.

Overall result: ✅ improvements - no action needed

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.

@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)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-1.7%	[-3.1%, -0.4%]	2
Improvements ✅ (secondary)	-1.5%	[-3.0%, -1.2%]	7
All ❌✅ (primary)	-1.7%	[-3.1%, -0.4%]	2

Max RSS (memory usage)

Results (primary -2.3%)

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)	-2.3%	[-2.3%, -2.3%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-2.3%	[-2.3%, -2.3%]	1

Cycles

Results (primary 2.4%, secondary 2.0%)

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)	2.0%	[1.7%, 2.4%]	2
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	2.4%	[2.4%, 2.4%]	1

Binary size

This benchmark run did not return any relevant results for this metric.

Bootstrap: 475.694s -> 475.403s (-0.06%)
Artifact size: 388.39 MiB -> 388.40 MiB (0.00%)

[lolbinarycat]

Finally managed to find a simple optimization that actually leads to statistically significant improvements!

[rustbot]

r? @GuillaumeGomez

rustbot has assigned @GuillaumeGomez.
They will have a look at your PR within the next two weeks and either review your PR or reassign to another reviewer.

Use r? to explicitly pick a reviewer

[GuillaumeGomez]

Nicely done, thanks!

@bors r+

[bors]

📌 Commit 3008626 has been approved by GuillaumeGomez

It is now in the queue for this repository.

[bors]

⌛ Testing commit 3008626 with merge e65b983...

[bors]

☀️ Test successful - checks-actions
Approved by: GuillaumeGomez
Pushing e65b983 to main...

[github-actions]

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 f35a2be (parent) -> e65b983 (this PR)

Test differences

Show 1 test diff

1 doctest diff were found. These are ignored, as they are noisy.

Test dashboard

Run

cargo run --manifest-path src/ci/citool/Cargo.toml -- \
    test-dashboard e65b983161d52688ff8e05245ed5dc70ef01a904 --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

1. dist-apple-various: 3288.5s -> 4036.1s (+22.7%)
2. dist-x86_64-apple: 6387.2s -> 7820.7s (+22.4%)
3. tidy: 151.4s -> 167.7s (+10.8%)
4. aarch64-apple: 6956.0s -> 7704.2s (+10.8%)
5. i686-gnu-nopt-1: 7596.9s -> 6840.3s (-10.0%)
6. x86_64-gnu-llvm-21-3: 5837.1s -> 6387.5s (+9.4%)
7. x86_64-msvc-1: 8531.7s -> 9286.9s (+8.9%)
8. aarch64-gnu-llvm-20-2: 2367.7s -> 2182.8s (-7.8%)
9. dist-powerpc64le-linux-musl: 5617.3s -> 5202.8s (-7.4%)
10. dist-ohos-x86_64: 4078.5s -> 4374.0s (+7.2%)

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]

Finished benchmarking commit (e65b983): 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)	-1.5%	[-3.0%, -0.3%]	3
Improvements ✅ (secondary)	-1.1%	[-2.9%, -0.1%]	4
All ❌✅ (primary)	-1.5%	[-3.0%, -0.3%]	3

Max RSS (memory usage)

This benchmark run did not return any relevant results for this metric.

Cycles

Results (secondary 3.1%)

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)	3.1%	[2.7%, 3.7%]	3
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Binary size

This benchmark run did not return any relevant results for this metric.

Bootstrap: 474.05s -> 474.286s (0.05%)
Artifact size: 388.66 MiB -> 388.66 MiB (-0.00%)