2023-08-29.md

2023-08-29 Triage Log

A fairly quiet week, with improvements exceeding a small scattering of regressions. Memory usage and artifact size held fairly steady across the week, with no regressions or improvements.

Triage done by @simulacrum. Revision range: d4a881e1433cd10e424843353e1f939f5a798f4e..cedbe5c715c1fa9359683c5f108bed2054ac258b

Summary:

(instructions:u)	mean	range	count
Regressions ❌ (primary)	1.6%	[0.3%, 2.2%]	6
Regressions ❌ (secondary)	1.4%	[0.8%, 1.9%]	19
Improvements ✅ (primary)	-1.0%	[-8.0%, -0.3%]	70
Improvements ✅ (secondary)	-1.6%	[-4.2%, -0.2%]	56
All ❌✅ (primary)	-0.8%	[-8.0%, 2.2%]	76

2 Regressions, 3 Improvements, 2 Mixed; 0 of them in rollups 108 artifact comparisons made in total

Regressions

rustdoc: Add lint redundant_explicit_links #113167 (Comparison Link)

(instructions:u)	mean	range	count
Regressions ❌ (primary)	0.7%	[0.4%, 0.9%]	7
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.7%	[0.4%, 0.9%]	7

Small regression in libc compilation, primarily incremental non-doc scenarios. Unclear cause but sufficiently limited in scope that further investigation is not warranted.

Fix races conditions with SyntaxContext decoding #115082 (Comparison Link)

(instructions:u)	mean	range	count
Regressions ❌ (primary)	0.3%	[0.2%, 0.3%]	4
Regressions ❌ (secondary)	0.3%	[0.3%, 0.4%]	7
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.3%	[0.2%, 0.3%]	4

Some small regressions, but this is a correctness fix for parallel compilation so warranted. (Parallel compilation is not on here but the fix affects both non-parallel and parallel scenarios).

Improvements

Speed up compilation of type-system-chess #114611 (Comparison Link)

(instructions:u)	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-1.7%	[-1.7%, -1.7%]	1
Improvements ✅ (secondary)	-2.2%	[-4.2%, -0.7%]	28
All ❌✅ (primary)	-1.7%	[-1.7%, -1.7%]	1

Perf results look good, various small improvements in secondary benchmarks. The real driver was the type-system-chess program I mentioned above, where the walltime and max-rss changes were both about -85% when I measured them locally.

(rust-lang/rust#114611 (comment))

Add MIR validation for unwind out from nounwind functions + fixes to make validation pass #113124 (Comparison Link)

(instructions:u)	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.7%	[-1.1%, -0.5%]	6
Improvements ✅ (secondary)	-0.3%	[-0.6%, -0.2%]	3
All ❌✅ (primary)	-0.7%	[-1.1%, -0.5%]	6

Update x64 Linux host compiler to LLVM 17 #114297 (Comparison Link)

(instructions:u)	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.6%	[-1.0%, -0.2%]	41
Improvements ✅ (secondary)	-0.9%	[-1.5%, -0.2%]	22
All ❌✅ (primary)	-0.6%	[-1.0%, -0.2%]	41

Mixed

Remove references in VarDebugInfo #114904 (Comparison Link)

(instructions:u)	mean	range	count
Regressions ❌ (primary)	0.8%	[0.3%, 1.3%]	10
Regressions ❌ (secondary)	1.4%	[1.3%, 1.4%]	4
Improvements ✅ (primary)	-1.0%	[-7.3%, -0.3%]	32
Improvements ✅ (secondary)	-2.1%	[-2.4%, -1.6%]	4
All ❌✅ (primary)	-0.6%	[-7.3%, 1.3%]	42

Fixed a bug in codegen. The regressions appear to be within noise range for the relevant benchmarks.

Add a new helper to avoid calling io::Error::kind #115228 (Comparison Link)

(instructions:u)	mean	range	count
Regressions ❌ (primary)	0.3%	[0.3%, 0.3%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.6%	[-0.8%, -0.5%]	3
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-0.4%	[-0.8%, 0.3%]	4

Regression is within noise range of the relevant benchmark.