2024-07-09 Triage Log

More regressions than improvements this week, caused by a combination of fixes, refactorings, third-party dependency updates and in general the compiler doing slightly more work.

Triage done by @kobzol. Revision range: cf2df68d..a2d58197

Summary:

(instructions:u)	mean	range	count
Regressions ❌ (primary)	0.7%	[0.2%, 2.5%]	53
Regressions ❌ (secondary)	1.0%	[0.4%, 1.5%]	31
Improvements ✅ (primary)	-0.6%	[-1.2%, -0.2%]	10
Improvements ✅ (secondary)	-1.7%	[-2.4%, -1.4%]	4
All ❌✅ (primary)	0.5%	[-1.2%, 2.5%]	63

1 Regression, 2 Improvements, 7 Mixed; 3 of them in rollups 62 artifact comparisons made in total

Regressions

Make can_eq process obligations (almost) everywhere #127172 (Comparison Link)

(instructions:u)	mean	range	count
Regressions ❌ (primary)	0.3%	[0.2%, 0.6%]	25
Regressions ❌ (secondary)	0.8%	[0.7%, 0.9%]	7
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.3%	[0.2%, 0.6%]	25

Small regression across several benchmarks.
Not marking as triaged yet, https://github.com/rust-lang/rust/pull/127473 has been opened to investigate a potential performance fix.

Improvements

Make jump threading state sparse #127036 (Comparison Link)

(instructions:u)	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.8%	[-1.1%, -0.5%]	5
Improvements ✅ (secondary)	-0.4%	[-0.4%, -0.4%]	1
All ❌✅ (primary)	-0.8%	[-1.1%, -0.5%]	5

Cache hir_owner_nodes in ParentHirIterator. #127421 (Comparison Link)

(instructions:u)	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.3%	[-1.0%, -0.2%]	16
Improvements ✅ (secondary)	-0.1%	[-0.1%, -0.1%]	3
All ❌✅ (primary)	-0.3%	[-1.0%, -0.2%]	16

Mixed

Check alias args for WF even if they have escaping bound vars #123737 (Comparison Link)

(instructions:u)	mean	range	count
Regressions ❌ (primary)	0.5%	[0.5%, 0.5%]	1
Regressions ❌ (secondary)	0.7%	[0.4%, 1.1%]	4
Improvements ✅ (primary)	-0.2%	[-0.2%, -0.2%]	2
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.0%	[-0.2%, 0.5%]	3

This change is required for further improvements of the type system, the compiler does a bit more work.
The regression is limited to one stress test and one cargo benchmark.
Marked as triaged.

Re-implement a type-size based limit #125507 (Comparison Link)

(instructions:u)	mean	range	count
Regressions ❌ (primary)	1.3%	[0.3%, 1.9%]	5
Regressions ❌ (secondary)	0.9%	[0.9%, 0.9%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.4%	[-0.4%, -0.4%]	1
All ❌✅ (primary)	1.3%	[0.3%, 1.9%]	5

This PR re-enabled a type size limit check that was not working for a long time.
It heavily regressed a stress test that contains very deeply nested types, this regression has been resolved in https://github.com/rust-lang/rust/pull/127288.
It seems like the PR is causing issues for various projects, and it might be reverted, but the perf. regression itself has been fixed by https://github.com/rust-lang/rust/pull/127288.
Marked as triaged.

rustdoc: update to pulldown-cmark 0.11 #127127 (Comparison Link)

(instructions:u)	mean	range	count
Regressions ❌ (primary)	0.8%	[0.2%, 1.8%]	16
Regressions ❌ (secondary)	0.5%	[0.3%, 0.6%]	7
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.2%	[-0.2%, -0.2%]	1
All ❌✅ (primary)	0.8%	[0.2%, 1.8%]	16

This PR updated the used version of pulldown-cmark, which resolves several bugs in handling doc blocks.
It caused a small regression in doc builds.
Marked as triaged.

cache type sizes in type-size limit visitor #127288 (Comparison Link)

(instructions:u)	mean	range	count
Regressions ❌ (primary)	0.3%	[0.2%, 0.3%]	9
Regressions ❌ (secondary)	0.7%	[0.6%, 0.8%]	3
Improvements ✅ (primary)	-1.3%	[-1.6%, -0.4%]	4
Improvements ✅ (secondary)	-85.4%	[-99.8%, -1.9%]	7
All ❌✅ (primary)	-0.2%	[-1.6%, 0.3%]	13

Resolved a perf. regression from https://github.com/rust-lang/rust/pull/125507.

Rollup of 8 pull requests #127403 (Comparison Link)

(instructions:u)	mean	range	count
Regressions ❌ (primary)	0.2%	[0.2%, 0.3%]	3
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.9%	[-1.3%, -0.6%]	9
All ❌✅ (primary)	0.2%	[0.2%, 0.3%]	3

Small regression on a single benchmark, but only in incremental unchanged build.
Improvements outweigh the regressions.
Marked as triaged.

Rollup of 10 pull requests #127476 (Comparison Link)

(instructions:u)	mean	range	count
Regressions ❌ (primary)	0.5%	[0.2%, 1.7%]	15
Regressions ❌ (secondary)	0.3%	[0.1%, 0.7%]	3
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.2%	[-0.2%, -0.2%]	1
All ❌✅ (primary)	0.5%	[0.2%, 1.7%]	15

Small regressions on doc builds caused by https://github.com/rust-lang/rust/pull/127439.
This is a necessary refactoring, and the author has deemed the small perf. hit to be worth it.
Marked as triaged.

Rollup of 5 pull requests #127486 (Comparison Link)

(instructions:u)	mean	range	count
Regressions ❌ (primary)	0.4%	[0.2%, 0.4%]	7
Regressions ❌ (secondary)	0.2%	[0.2%, 0.2%]	1
Improvements ✅ (primary)	-0.8%	[-0.8%, -0.8%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.2%	[-0.8%, 0.4%]	8

Unclear which PR has caused the (small) regression.
Not marking as triaged yet.