resolve: Use `Macros20NormalizedIdent` in more interfaces #150741

petrochenkov · 2026-01-06T22:42:19Z

It allows to avoid expensive double normalization in some cases.
This is an attempt to fix the perf regressions from #149681.

rustbot · 2026-01-06T22:42:24Z

r? @SparrowLii

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petrochenkov · 2026-01-06T22:43:11Z

@bors try @rust-timer queue

resolve: Use `Macros20NormalizedIdent` in more interfaces

rust-bors · 2026-01-07T01:10:27Z

☀️ Try build successful (CI)
Build commit: e520b01 (e520b01b98bd6455f6d47eded6e6c5b14be22ce7, parent: 4d73a008eaf6ba3ca067a3221e5c00602e33a5f2)

rust-timer · 2026-01-07T01:51:33Z

Finished benchmarking commit (e520b01): 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)	-0.3%	[-0.6%, -0.1%]	120
Improvements ✅ (secondary)	-0.4%	[-1.1%, -0.1%]	55
All ❌✅ (primary)	-0.3%	[-0.6%, -0.1%]	120

Max RSS (memory usage)

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

Cycles

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

Binary size

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

Bootstrap: 473.709s -> 471.656s (-0.43%)
Artifact size: 390.82 MiB -> 390.89 MiB (0.02%)

petrochenkov · 2026-01-07T13:43:44Z

How often resolve_ident_in_scope_set is used with different scope sets:

Module:        1015781
All:            445512
Macro:          217256
ExternPrelude:     649

So, ScopeSet::Module is the new dominating mode of use for resolve_ident_in_scope_set, it's not surprising that it's stressing it.

It allows to avoid expensive double normalization in some cases

In practice it was already normalized because `visit_scopes` normalized it

Also evaluate one cheap and often-false condition first

rustbot · 2026-01-07T14:33:19Z

This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

petrochenkov · 2026-01-07T14:34:08Z

@bors try @rust-timer queue

resolve: Use `Macros20NormalizedIdent` in more interfaces

rust-bors · 2026-01-07T16:58:18Z

☀️ Try build successful (CI)
Build commit: d6b68ca (d6b68ca4b912a0e27bcdf1f604470687653b8d16, parent: d9617c8d9a55773a96b61ba3a4acb107d65615c1)

rust-timer · 2026-01-07T17:39:45Z

Finished benchmarking commit (d6b68ca): 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)	2.2%	[2.2%, 2.2%]	1
Improvements ✅ (primary)	-0.3%	[-0.6%, -0.1%]	116
Improvements ✅ (secondary)	-0.4%	[-1.2%, -0.1%]	53
All ❌✅ (primary)	-0.3%	[-0.6%, -0.1%]	116

Max RSS (memory usage)

Results (primary -1.2%, 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)	0.8%	[0.8%, 0.8%]	3
Improvements ✅ (primary)	-1.2%	[-2.0%, -0.5%]	4
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-1.2%	[-2.0%, -0.5%]	4

Cycles

Results (primary 3.0%, secondary 1.5%)

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

	mean	range	count
Regressions ❌ (primary)	3.0%	[2.1%, 3.9%]	2
Regressions ❌ (secondary)	2.4%	[1.3%, 3.5%]	4
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-2.0%	[-2.0%, -2.0%]	1
All ❌✅ (primary)	3.0%	[2.1%, 3.9%]	2

Binary size

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

Bootstrap: 474.542s -> 478.609s (0.86%)
Artifact size: 390.84 MiB -> 390.88 MiB (0.01%)

petrochenkov · 2026-01-07T21:16:20Z

The large-workspace regression is spurious (llvm codegen time regresses, which is unrelated to this PR).

petrochenkov · 2026-01-07T21:19:29Z

This recovers roughly a half of performance lost in #149681.
I have a couple more ideas about speeding up resolve_ident_in_scope_set, but I'm less sure in them and would rather benchmark them separately.

@rustbot ready
r? @nnethercote maybe?

nnethercote · 2026-01-08T04:10:55Z

@bors r+

rust-bors · 2026-01-08T04:10:58Z

📌 Commit 99a7d28 has been approved by nnethercote

It is now in the queue for this repository.

rust-bors · 2026-01-11T22:38:47Z

☀️ Test successful - CI
Approved by: nnethercote
Pushing b68e16c to main...

github-actions · 2026-01-11T22:41:34Z

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 7c41ee6 (parent) -> b68e16c (this PR)

Test differences

Show 22 test diffs

22 doctest diffs were found. These are ignored, as they are noisy.

Test dashboard

Run

cargo run --manifest-path src/ci/citool/Cargo.toml -- \
    test-dashboard b68e16cfc0e9f8b29c9ec41bfa6ab0a637eff19c --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: 10208.2s -> 8437.9s (-17.3%)
test-various: 7812.9s -> 6458.2s (-17.3%)
pr-check-1: 1496.1s -> 1676.0s (+12.0%)
dist-apple-various: 3768.8s -> 4167.0s (+10.6%)
i686-msvc-1: 9489.4s -> 10367.2s (+9.3%)
x86_64-gnu-miri: 4152.0s -> 4459.0s (+7.4%)
dist-i686-mingw: 8956.2s -> 9559.9s (+6.7%)
dist-armhf-linux: 5173.4s -> 4825.2s (-6.7%)
aarch64-gnu: 7276.1s -> 7750.9s (+6.5%)
x86_64-gnu-nopt: 8483.9s -> 7984.5s (-5.9%)

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 · 2026-01-11T23:22:03Z

Finished benchmarking commit (b68e16c): 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)	0.6%	[0.6%, 0.6%]	1
Improvements ✅ (primary)	-0.3%	[-0.6%, -0.1%]	114
Improvements ✅ (secondary)	-0.4%	[-1.2%, -0.1%]	63
All ❌✅ (primary)	-0.3%	[-0.6%, -0.1%]	114

Max RSS (memory usage)

Results (primary 0.5%, secondary 2.7%)

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

	mean	range	count
Regressions ❌ (primary)	2.5%	[2.5%, 2.5%]	1
Regressions ❌ (secondary)	2.7%	[2.2%, 3.1%]	2
Improvements ✅ (primary)	-1.5%	[-1.5%, -1.5%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.5%	[-1.5%, 2.5%]	2

Cycles

Results (secondary -3.8%)

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)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-3.8%	[-3.8%, -3.8%]	1
All ❌✅ (primary)	-	-	0

Binary size

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

Bootstrap: 473.762s -> 473.667s (-0.02%)
Artifact size: 391.43 MiB -> 391.39 MiB (-0.01%)

rustbot assigned SparrowLii Jan 6, 2026

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. labels Jan 6, 2026

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Auto merge of #150741 - petrochenkov:modsplitfast, r=<try>

e520b01

resolve: Use `Macros20NormalizedIdent` in more interfaces

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resolve: Split Scope::Module into two scopes for non-glob and glob bindings #149681

Merged

petrochenkov added 4 commits January 7, 2026 16:53

resolve: Do not query edition too eagerly in visit_scopes

87195e7

resolve: Use Macros20NormalizedIdent in more interfaces

1200773

It allows to avoid expensive double normalization in some cases

resolve: Pass a normalized ident to resolve_ident_in_scope

888e28b

In practice it was already normalized because `visit_scopes` normalized it

resolve: Avoid most allocations in resolve_ident_in_scope_set

99a7d28

Also evaluate one cheap and often-false condition first

petrochenkov force-pushed the modsplitfast branch from 32c0a85 to 99a7d28 Compare January 7, 2026 14:33

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rust-bors bot added a commit that referenced this pull request Jan 7, 2026

Auto merge of #150741 - petrochenkov:modsplitfast, r=<try>

d6b68ca

resolve: Use `Macros20NormalizedIdent` in more interfaces

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rust-bors bot added the merged-by-bors This PR was explicitly merged by bors. label Jan 11, 2026

rust-bors bot merged commit b68e16c into rust-lang:main Jan 11, 2026
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resolve: Refactor away the side table decl_parent_modules #150877

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resolve: Use Macros20NormalizedIdent in more interfaces #150741

resolve: Use Macros20NormalizedIdent in more interfaces #150741

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Overall result: ✅ improvements - no action needed

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Test differences

Job duration changes

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Overall result: ✅ improvements - no action needed

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resolve: Use `Macros20NormalizedIdent` in more interfaces #150741

resolve: Use `Macros20NormalizedIdent` in more interfaces #150741