2024-12-23.md

2024-12-23 Triage Log

We missed triage last week due to some process issues, so this triage includes two weeks of data. The overall result is positive, due to parser optimizations (#133793), trait solving optimizations (#134501, #132325) and bumping the cc crate (#134505), which improved the performance of C/C++ dependencies of the compiler.

Triage done by @kobzol. Revision range: 1b3fb316..0eca4dd3

Summary:

(instructions:u)	mean	range	count
Regressions ❌ (primary)	0.5%	[0.3%, 0.8%]	3
Regressions ❌ (secondary)	1.0%	[1.0%, 1.0%]	1
Improvements ✅ (primary)	-1.8%	[-7.5%, -0.3%]	254
Improvements ✅ (secondary)	-1.3%	[-5.4%, -0.3%]	224
All ❌✅ (primary)	-1.8%	[-7.5%, 0.8%]	257

4 Regressions, 10 Improvements, 12 Mixed; 9 of them in rollups 90 artifact comparisons made in total

Regressions

Rollup of 6 pull requests #134296 (Comparison Link)

(instructions:u)	mean	range	count
Regressions ❌ (primary)	0.3%	[0.2%, 0.4%]	7
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.3%	[0.2%, 0.4%]	7

• The regressions were caused by #134081.
• It was not deemed worthy to fix them, because of added maintenance burden.
• Marked as triaged.

Remove queries from the driver interface #134302 (Comparison Link)

(instructions:u)	mean	range	count
Regressions ❌ (primary)	0.3%	[0.1%, 0.6%]	11
Regressions ❌ (secondary)	0.5%	[0.2%, 0.7%]	18
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.3%	[0.1%, 0.6%]	11

• A few tiny regressions in doc builds, caused by a cleanup of the compiler driver interface.
• Marked as triaged.

Rollup of 8 pull requests #134582 (Comparison Link)

(instructions:u)	mean	range	count
Regressions ❌ (primary)	0.2%	[0.2%, 0.2%]	6
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.2%	[0.2%, 0.2%]	6

• Tiny regression on a single benchmark, I don't think that it's worthy to investigate further.
• Marked as triaged.

Asserts the maximum value that can be returned from Vec::len #131193 (Comparison Link)

(instructions:u)	mean	range	count
Regressions ❌ (primary)	0.3%	[0.2%, 1.2%]	104
Regressions ❌ (secondary)	0.3%	[0.1%, 0.8%]	38
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.3%	[0.2%, 1.2%]	104

• The post-merge regression seems to be much larger than originally expected.
• Asked the PR author about this.
• Not marking as triaged yet.

Improvements

Rollup of 9 pull requests #134137 (Comparison Link)

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

Rollup of 4 pull requests #134349 (Comparison Link)

(instructions:u)	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.3%	[-0.8%, -0.1%]	4
Improvements ✅ (secondary)	-0.2%	[-0.2%, -0.2%]	4
All ❌✅ (primary)	-0.3%	[-0.8%, -0.1%]	4

Rollup of 9 pull requests #134395 (Comparison Link)

(instructions:u)	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.3%	[-0.7%, -0.2%]	9
All ❌✅ (primary)	-	-	0

rework winnowing to sensibly handle global where-bounds #132325 (Comparison Link)

(instructions:u)	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.4%	[-1.0%, -0.2%]	64
Improvements ✅ (secondary)	-1.6%	[-2.1%, -0.7%]	9
All ❌✅ (primary)	-0.4%	[-1.0%, -0.2%]	64

Try to fix perf regression in rustdoc after hir attributes #134376 (Comparison Link)

(instructions:u)	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.3%	[-0.6%, -0.2%]	10
Improvements ✅ (secondary)	-0.4%	[-0.6%, -0.2%]	18
All ❌✅ (primary)	-0.3%	[-0.6%, -0.2%]	10

Speed up Parser::expected_tokens #133793 (Comparison Link)

(instructions:u)	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.9%	[-2.5%, -0.2%]	213
Improvements ✅ (secondary)	-0.8%	[-2.5%, -0.1%]	105
All ❌✅ (primary)	-0.9%	[-2.5%, -0.2%]	213

Rollup of 5 pull requests #134559 (Comparison Link)

(instructions:u)	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.5%	[-1.4%, -0.1%]	17
Improvements ✅ (secondary)	-3.1%	[-4.7%, -1.5%]	3
All ❌✅ (primary)	-0.5%	[-1.4%, -0.1%]	17

handle member constraints directly in the mir type checker #134501 (Comparison Link)

(instructions:u)	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.4%	[-0.5%, -0.2%]	65
Improvements ✅ (secondary)	-0.3%	[-0.6%, -0.0%]	58
All ❌✅ (primary)	-0.4%	[-0.5%, -0.2%]	65

Bump compiler cc to 1.2.5 #134505 (Comparison Link)

(instructions:u)	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.7%	[-7.6%, -0.1%]	244
Improvements ✅ (secondary)	-0.7%	[-1.4%, -0.1%]	196
All ❌✅ (primary)	-0.7%	[-7.6%, -0.1%]	244

• The improvements were probably caused by rust-lang/cc-rs#1279.

cleanup TypeVerifier #134465 (Comparison Link)

(instructions:u)	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.3%	[-0.4%, -0.2%]	6
Improvements ✅ (secondary)	-0.4%	[-0.5%, -0.1%]	16
All ❌✅ (primary)	-0.3%	[-0.4%, -0.2%]	6

Mixed

Introduce MixedBitSet #133891 (Comparison Link)

(instructions:u)	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	0.6%	[0.2%, 1.0%]	8
Improvements ✅ (primary)	-0.6%	[-1.3%, -0.2%]	67
Improvements ✅ (secondary)	-0.7%	[-2.0%, -0.2%]	28
All ❌✅ (primary)	-0.6%	[-1.3%, -0.2%]	67

• More improvements than regressions, especially on primary benchmarks.
• Already marked as triaged.

Rollup of 10 pull requests #134108 (Comparison Link)

(instructions:u)	mean	range	count
Regressions ❌ (primary)	0.3%	[0.2%, 0.8%]	9
Regressions ❌ (secondary)	0.3%	[0.2%, 0.3%]	7
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.4%	[-0.7%, -0.2%]	6
All ❌✅ (primary)	0.3%	[0.2%, 0.8%]	9

• Perf. runs for the most suspect PRs in the rollup haven't shown anything, but the regression is tiny, so it does not seem to be worthy of further investigation.
• Marked as triaged.

We don't need NonNull::as_ptr debuginfo #133899 (Comparison Link)

(instructions:u)	mean	range	count
Regressions ❌ (primary)	0.6%	[0.2%, 0.9%]	2
Regressions ❌ (secondary)	0.5%	[0.2%, 1.1%]	4
Improvements ✅ (primary)	-0.9%	[-2.1%, -0.3%]	34
Improvements ✅ (secondary)	-2.7%	[-3.0%, -2.5%]	2
All ❌✅ (primary)	-0.9%	[-2.1%, 0.9%]	36

• More improvements than regressions, and in particular very nice binary size wins.
• Marked as triaged.

Switch inline(always) in core/src/fmt/rt.rs to plain inline #134047 (Comparison Link)

(instructions:u)	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	0.5%	[0.5%, 0.5%]	1
Improvements ✅ (primary)	-0.4%	[-0.5%, -0.3%]	6
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-0.4%	[-0.5%, -0.3%]	6

• More improvements than regressions.
• Marked as triaged.

Move impl constness into impl trait header #134122 (Comparison Link)

(instructions:u)	mean	range	count
Regressions ❌ (primary)	0.8%	[0.8%, 0.8%]	1
Regressions ❌ (secondary)	1.7%	[1.6%, 1.9%]	6
Improvements ✅ (primary)	-0.3%	[-1.1%, -0.1%]	59
Improvements ✅ (secondary)	-0.7%	[-2.5%, -0.2%]	41
All ❌✅ (primary)	-0.3%	[-1.1%, 0.8%]	60

• More improvements than regressions.
• Marked as triaged.

Bounds-check with PtrMetadata instead of Len in MIR #133734 (Comparison Link)

(instructions:u)	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	0.3%	[0.2%, 0.3%]	2
Improvements ✅ (primary)	-1.4%	[-1.4%, -1.4%]	1
Improvements ✅ (secondary)	-0.6%	[-0.8%, -0.4%]	6
All ❌✅ (primary)	-1.4%	[-1.4%, -1.4%]	1

• Single tiny regression, otherwise tiny improvements.
• Marked as triaged.

Remove support for specializing ToString outside the standard library #134258 (Comparison Link)

(instructions:u)	mean	range	count
Regressions ❌ (primary)	0.3%	[0.2%, 0.5%]	3
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.4%	[-0.4%, -0.4%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.1%	[-0.4%, 0.5%]	4

• Tiny regression that was deemed acceptable.
• Marked as triaged.

Modifies the index instruction from gep [0 x %Type] to gep %Type #134117 (Comparison Link)

(instructions:u)	mean	range	count
Regressions ❌ (primary)	0.1%	[0.1%, 0.2%]	2
Regressions ❌ (secondary)	0.6%	[0.2%, 1.1%]	17
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-1.3%	[-1.4%, -1.2%]	4
All ❌✅ (primary)	0.1%	[0.1%, 0.2%]	2

• The post-merge perf. is very similar to the previous perf. runs, which were deemed acceptable during review.
• Marked as triaged.

Hir attributes #131808 (Comparison Link)

(instructions:u)	mean	range	count
Regressions ❌ (primary)	0.4%	[0.2%, 1.1%]	9
Regressions ❌ (secondary)	0.4%	[0.1%, 0.6%]	20
Improvements ✅ (primary)	-0.2%	[-0.4%, -0.2%]	3
Improvements ✅ (secondary)	-0.3%	[-0.7%, -0.2%]	5
All ❌✅ (primary)	0.3%	[-0.4%, 1.1%]	12

• The regression was fixed in #134376.
• Marked as triaged.

Rollup of 11 pull requests #134470 (Comparison Link)

(instructions:u)	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	0.2%	[0.1%, 0.4%]	7
Improvements ✅ (primary)	-0.2%	[-0.3%, -0.1%]	3
Improvements ✅ (secondary)	-0.5%	[-0.5%, -0.3%]	5
All ❌✅ (primary)	-0.2%	[-0.3%, -0.1%]	3

• Regressions seem to be balanced with improvements.
• Marked as triaged.

Rollup of 8 pull requests #134492 (Comparison Link)

(instructions:u)	mean	range	count
Regressions ❌ (primary)	0.4%	[0.2%, 0.7%]	10
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.1%	[-0.1%, -0.1%]	1
All ❌✅ (primary)	0.4%	[0.2%, 0.7%]	10

• The regressions seem to have blipped back soon after
• Marked as triaged.

Delete Rvalue::Len 🎉 #134330 (Comparison Link)

(instructions:u)	mean	range	count
Regressions ❌ (primary)	0.3%	[0.3%, 0.4%]	2
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.3%	[-0.8%, -0.2%]	7
Improvements ✅ (secondary)	-0.3%	[-0.4%, -0.2%]	2
All ❌✅ (primary)	-0.2%	[-0.8%, 0.4%]	9

• More improvements than regressions.
• Marked as triaged.