perf: Lock-free root fast paths for hygiene queries

[xmakro]

normalize_to_macros_2_0, normalize_to_macro_rules and outer_expn_is_descendant_of take the HygieneData lock even for the root syntax context, the common case, where the answer is fixed: the root normalizes to itself, and everything descends from the root expansion. This PR avoids the lock, like the existing fast paths in ExpnId::is_descendant_of.

[rustbot]

⚠️ Warning ⚠️

• This PR is based on an upstream commit that is older than 28 days.

  It's recommended to update your branch according to the rustc-dev-guide.

[petrochenkov]

Yeah, it's good to apply this fast path consistently.
@bors try @rust-timer queue

[rust-bors]

☀️ Try build successful (CI)
Build commit: 51cbd2b (51cbd2b75321f7f1e1ca27962356a92e2d7f1d9e)
Base parent: c9ff496 (c9ff496891c278ad660bc0ab85c1f0b72059464a)

[rust-timer]

Finished benchmarking commit (51cbd2b): comparison URL.

Overall result: ✅ improvements - no action needed

Benchmarking means the PR may be perf-sensitive. It's automatically marked not fit for rolling up. Overriding is possible but disadvised: it risks changing compiler perf.

@bors rollup=never rustc-perf
@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%, -0.2%]	75
Improvements ✅ (secondary)	-0.8%	[-2.2%, -0.2%]	39
All ❌✅ (primary)	-0.3%	[-0.6%, -0.2%]	75

Max RSS (memory usage)

Results (secondary -0.7%)

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)	4.7%	[4.7%, 4.7%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-3.4%	[-5.0%, -1.8%]	2
All ❌✅ (primary)	-	-	0

Cycles

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)	1.2%	[0.4%, 2.6%]	7
Regressions ❌ (secondary)	1.3%	[0.7%, 1.7%]	4
Improvements ✅ (primary)	-2.0%	[-7.0%, -0.4%]	6
Improvements ✅ (secondary)	-1.2%	[-3.1%, -0.4%]	6
All ❌✅ (primary)	-0.3%	[-7.0%, 2.6%]	13

Binary size

Results (primary -0.1%, secondary -0.1%)

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)	-	-	0
Improvements ✅ (primary)	-0.1%	[-0.1%, -0.0%]	75
Improvements ✅ (secondary)	-0.1%	[-0.1%, -0.0%]	39
All ❌✅ (primary)	-0.1%	[-0.1%, -0.0%]	75

Bootstrap: 489.838s -> 496.142s (1.29%)
Artifact size: 390.28 MiB -> 390.17 MiB (-0.03%)

[petrochenkov]

@bors r+

[rust-bors]

📌 Commit 7c901eb has been approved by petrochenkov

It is now in the queue for this repository.

🌲 The tree is currently closed for pull requests below priority 10. This pull request will be tested once the tree is reopened.

Reason for tree closure: manually handling queue due to backlog

[rust-bors]

☀️ Test successful - CI
Approved by: petrochenkov
Duration: 3h 12m 55s
Pushing f73951d 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 26bfbf2 (parent) -> f73951d (this PR)

Test differences

Show 18 test diffs

18 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 f73951df0a5566d94d13b7954acd9f4ab1fa3734 --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. x86_64-gnu-gcc: 41m 54s -> 1h 14m (+76.7%)
2. x86_64-gnu-gcc-core-tests: 8m 20s -> 14m 44s (+76.6%)
3. i686-msvc-1: 1h 49m -> 2h 57m (+62.8%)
4. dist-i586-gnu-i586-i686-musl: 16m 54s -> 24m 41s (+46.0%)
5. test-various: 1h 33m -> 2h 5m (+33.9%)
6. x86_64-msvc-ext2: 1h 54m -> 1h 23m (-27.3%)
7. dist-powerpc64le-linux-musl: 1h 14m -> 1h 34m (+26.3%)
8. optional-x86_64-gnu-autodiff: 43m 35s -> 54m 54s (+26.0%)
9. dist-powerpc64-linux-musl: 1h 32m -> 1h 9m (-25.0%)
10. x86_64-msvc-1: 2h 36m -> 1h 58m (-24.0%)

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 (f73951d): 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)	-0.3%	[-0.7%, -0.2%]	61
Improvements ✅ (secondary)	-0.8%	[-2.3%, -0.1%]	42
All ❌✅ (primary)	-0.3%	[-0.7%, -0.2%]	61

Max RSS (memory usage)

Results (primary 2.5%, secondary 6.1%)

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)	6.1%	[6.1%, 6.1%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	2.5%	[2.5%, 2.5%]	1

Cycles

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

Binary size

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

Bootstrap: 459.691s -> 460.81s (0.24%)
Artifact size: 398.70 MiB -> 398.76 MiB (0.01%)