Improve `DocStrings` perf by GuillaumeGomez · Pull Request #163535 · rust-lang/rust

GuillaumeGomez · 2026-09-30T10:36:30Z

Follow-up of #162862.

r? ghost

GuillaumeGomez · 2026-09-30T10:36:49Z

Improve `DocStrings` perf

rust-bors · 2026-09-30T11:36:35Z

☀️ Try build successful (CI)
Build commit: cfeb8d7 (cfeb8d7e074c05323974a20f46f30b5d7ba60f77)
Base parent: 7d2cd0f (7d2cd0fbc092625ea371da704f15f80216d2220e)

rust-timer · 2026-09-30T17:41:26Z

Finished benchmarking commit (cfeb8d7): comparison URL.

Overall result: ❌✅ regressions and improvements - no action needed

Benchmarking means the PR may be perf-sensitive. Consider adding rollup=never if this change is not fit for rolling up.

@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)	0.3%	[0.3%, 0.3%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.2%	[-0.2%, -0.2%]	1
All ❌✅ (primary)	0.3%	[0.3%, 0.3%]	1

Max RSS (memory usage)

This perf run didn't have relevant results for this metric.

Cycles

Results (secondary -3.4%)

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)	-3.4%	[-3.8%, -3.1%]	2
All ❌✅ (primary)	-	-	0

Binary size

Results (primary -0.0%, secondary -0.0%)

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)	-0.0%	[-0.0%, -0.0%]	4
Improvements ✅ (secondary)	-0.0%	[-0.0%, -0.0%]	1
All ❌✅ (primary)	-0.0%	[-0.0%, -0.0%]	4

Bootstrap: 489.84s -> 487.931s (-0.39%)
Artifact size: 406.54 MiB -> 406.55 MiB (0.00%)

GuillaumeGomez · 2026-09-30T17:49:38Z

Hum, not there yet. Maybe the indexing thing?

GuillaumeGomez · 2026-10-01T11:04:06Z

@bors try @rust-timer queue

Improve `DocStrings` perf

rust-bors · 2026-10-01T12:10:38Z

☀️ Try build successful (CI)
Build commit: af91cbc (af91cbc4d7653cd1b02758a45e33d96defd69055)
Base parent: 837b18a (837b18aae097503892d7aab6c7ddce332a991a21)

rust-timer · 2026-10-01T13:15:03Z

Finished benchmarking commit (af91cbc): comparison URL.

Overall result: ❌✅ regressions and improvements - no action needed

Benchmarking means the PR may be perf-sensitive. Consider adding rollup=never if this change is not fit for rolling up.

@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)	0.4%	[0.3%, 0.4%]	2
Improvements ✅ (primary)	-0.1%	[-0.1%, -0.1%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-0.1%	[-0.1%, -0.1%]	1

Max RSS (memory usage)

Results (secondary 4.2%)

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)	4.2%	[4.2%, 4.2%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Cycles

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)	2.8%	[2.8%, 2.8%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-2.3%	[-2.5%, -2.1%]	3
All ❌✅ (primary)	-	-	0

Binary size

This perf run didn't have relevant results for this metric.

Bootstrap: 490.365s -> 490.056s (-0.06%)
Artifact size: 406.38 MiB -> 406.48 MiB (0.02%)

GuillaumeGomez · 2026-10-01T13:43:05Z

I'm starting to wonder if it isn't all just noise...

r? @nnethercote

nnethercote · 2026-10-01T23:30:29Z

Commit 1 is fine. I don't think commit 2 (extra code) and commit 3 (unsafety) are worth it when there is ~zero perf benefit :/

GuillaumeGomez · 2026-10-02T09:29:18Z

Yeah agreed. Removed the last two commits.

@rustbot ready

nnethercote · 2026-10-02T11:22:50Z

@bors r+ rollup

rust-bors · 2026-10-02T11:22:53Z

📌 Commit 13035c1 has been tentatively approved by nnethercote

It will be put into the queue for this repository once PR CI succeeds.

…-perf, r=nnethercote Improve `DocStrings` perf Follow-up of rust-lang#162862. r? ghost

…uwer Rollup of 13 pull requests Successful merges: - #163317 (Fix incremental compilation for fat LTO) - #163582 (Reapply "bootstrap: Enable rustdoc mergeable CCI for std and internal docs") - #151793 (Add mul_add_relaxed methods for floating-point types) - #162782 (Fix rustdoc ICE caused by mishandling of ambiguity errors) - #163010 (Miri can do dirfd now) - #163535 (Improve `DocStrings` perf) - #163576 (Fix `TypeOutlives` fast-path) - #163587 (Several small span improvements) - #163612 (fix `ValidateBoundVars`) - #163632 (bump rustc-build-sysroot) - #163635 (Revert note about signum of NaN) - #163644 (Add mailmap entry) - #163651 (Remove variants from `feature-gate-autodiff-use` test)

…uwer Rollup of 14 pull requests Successful merges: - #163582 (Reapply "bootstrap: Enable rustdoc mergeable CCI for std and internal docs") - #151793 (Add mul_add_relaxed methods for floating-point types) - #162782 (Fix rustdoc ICE caused by mishandling of ambiguity errors) - #163010 (Miri can do dirfd now) - #163535 (Improve `DocStrings` perf) - #163576 (Fix `TypeOutlives` fast-path) - #163587 (Several small span improvements) - #163603 (Reorganise reflection intrinsics) - #163612 (fix `ValidateBoundVars`) - #163632 (bump rustc-build-sysroot) - #163635 (Revert note about signum of NaN) - #163644 (Add mailmap entry) - #163647 (Rename `rustc_driver::run_compiler` to `compiler_entrypoint`) - #163651 (Remove variants from `feature-gate-autodiff-use` test)

Rollup merge of #163535 - GuillaumeGomez:improve-doc-strings-perf, r=nnethercote Improve `DocStrings` perf Follow-up of #162862. r? ghost

…uwer Rollup of 14 pull requests Successful merges: - rust-lang/rust#163582 (Reapply "bootstrap: Enable rustdoc mergeable CCI for std and internal docs") - rust-lang/rust#151793 (Add mul_add_relaxed methods for floating-point types) - rust-lang/rust#162782 (Fix rustdoc ICE caused by mishandling of ambiguity errors) - rust-lang/rust#163010 (Miri can do dirfd now) - rust-lang/rust#163535 (Improve `DocStrings` perf) - rust-lang/rust#163576 (Fix `TypeOutlives` fast-path) - rust-lang/rust#163587 (Several small span improvements) - rust-lang/rust#163603 (Reorganise reflection intrinsics) - rust-lang/rust#163612 (fix `ValidateBoundVars`) - rust-lang/rust#163632 (bump rustc-build-sysroot) - rust-lang/rust#163635 (Revert note about signum of NaN) - rust-lang/rust#163644 (Add mailmap entry) - rust-lang/rust#163647 (Rename `rustc_driver::run_compiler` to `compiler_entrypoint`) - rust-lang/rust#163651 (Remove variants from `feature-gate-autodiff-use` test)

Iterate only once to get module inner attributes position

13035c1

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. T-rustdoc Relevant to the rustdoc team, which will review and decide on the PR/issue. labels Sep 30, 2026