Only inherit local hash for paths

[cjgillot]

DefPathHash, as the counterpart of DefId that is stable across compiler invocations, is comprised of 2 parts. The first one is the StableCrateId, stable form of CrateNum. The second is 64 complementary bits to identify the crate-local definition.

The current implementation always hashes the full 128 bits when (1) trying to create a new child DefPathHash or (2) hashing a CrateNum or a LocalDefId. But we only need half that information: LocalDefId means that the StableCrateId is always the current crate's ; CrateNum means that we do not care about the local part.

As stable hashing is very hot in the query system, in particular hashing definitions, this is a big deal.

We still want the local part to change when the StableCrateId changes, to make incr-compilation errors less painful, ie. increase the likelihood that if will magically disappear by changing some code.

This PR sprinkles some #[inline] attributes on small functions that appeared in profiles.

[cjgillot]

@bors try @rust-timer queue

[bors]

⌛ Trying commit 1b4a19d with merge 6e20539...

[bors]

☀️ Try build successful - checks-actions
Build commit: 6e20539 (6e20539f56d631fb16fbe744f76d3de64b76e278)

[rust-timer]

Finished benchmarking commit (6e20539): 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)	-0.4%	[-0.9%, -0.2%]	140
Improvements ✅ (secondary)	-0.5%	[-1.2%, -0.1%]	80
All ❌✅ (primary)	-0.4%	[-0.9%, -0.2%]	140

Max RSS (memory usage)

Results (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)	-	-	0
Regressions ❌ (secondary)	3.0%	[2.7%, 3.2%]	2
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Cycles

Results (secondary -2.1%)

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
Improvements ✅ (secondary)	-2.1%	[-2.1%, -2.1%]	2
All ❌✅ (primary)	-	-	0

Binary size

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

Bootstrap: 688.673s -> 689.15s (0.07%)
Artifact size: 371.94 MiB -> 372.00 MiB (0.02%)

[rustbot]

r? @fee1-dead

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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

[fee1-dead]

r? compiler

[compiler-errors]

@bors r+ rollup=never

[bors]

📌 Commit 068f3ac has been approved by compiler-errors

It is now in the queue for this repository.

[bors]

⌛ Testing commit 068f3ac with merge 8c12d76...

[bors]

☀️ Test successful - checks-actions
Approved by: compiler-errors
Pushing 8c12d76 to master...

[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 f8f6997 (parent) -> 8c12d76 (this PR)

Test differences

Show 2 test diffs

2 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 8c12d76304fcceaeaad0d67209e5727e94f5f2b8 --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-apple-1: 7195.6s -> 10214.9s (42.0%)
2. aarch64-apple: 4085.0s -> 5214.7s (27.7%)
3. dist-aarch64-apple: 5942.4s -> 5100.5s (-14.2%)
4. x86_64-gnu-stable: 7269.3s -> 8258.0s (13.6%)
5. x86_64-apple-2: 6696.5s -> 5787.5s (-13.6%)
6. dist-x86_64-apple: 10639.1s -> 11615.2s (9.2%)
7. tidy: 65.8s -> 69.9s (6.3%)
8. x86_64-gnu-llvm-19-1: 3622.5s -> 3399.8s (-6.1%)
9. dist-sparcv9-solaris: 4793.3s -> 5068.3s (5.7%)
10. aarch64-msvc-2: 4654.7s -> 4879.0s (4.8%)

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 (8c12d76): 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)	-0.4%	[-1.0%, -0.2%]	140
Improvements ✅ (secondary)	-0.5%	[-1.2%, -0.1%]	105
All ❌✅ (primary)	-0.4%	[-1.0%, -0.2%]	140

Max RSS (memory usage)

Results (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)	-	-	0
Regressions ❌ (secondary)	4.8%	[3.0%, 6.6%]	2
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-3.5%	[-3.5%, -3.5%]	1
All ❌✅ (primary)	-	-	0

Cycles

Results (secondary 2.1%)

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

Binary size

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

Bootstrap: 463.571s -> 463.461s (-0.02%)
Artifact size: 374.76 MiB -> 374.76 MiB (-0.00%)