2023-08-14 Triage Log

A light week. Main thing to report is we got some improvements from telling LLVM that the negation in <*const T>::sub cannot overflow.

Triage done by @pnkfelix. Revision range: 443c3161..e8459109

Summary:

(instructions:u)	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.7%	[-1.6%, -0.4%]	11
Improvements ✅ (secondary)	-0.5%	[-1.6%, -0.3%]	8
All ❌✅ (primary)	-0.7%	[-1.6%, -0.4%]	11

0 Regressions, 1 Improvements, 4 Mixed; 1 of them in rollups 49 artifact comparisons made in total

Tell LLVM that the negation in <*const T>::sub cannot overflow #114720 (Comparison Link)

(instructions:u)	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.3%	[-0.3%, -0.2%]	9
Improvements ✅ (secondary)	-0.4%	[-0.5%, -0.3%]	4
All ❌✅ (primary)	-0.3%	[-0.3%, -0.2%]	9

Rollup of 7 pull requests #114604 (Comparison Link)

(instructions:u)	mean	range	count
Regressions ❌ (primary)	1.4%	[0.4%, 2.0%]	3
Regressions ❌ (secondary)	1.2%	[1.1%, 1.3%]	6
Improvements ✅ (primary)	-0.7%	[-0.9%, -0.4%]	2
Improvements ✅ (secondary)	-1.0%	[-1.5%, -0.5%]	2
All ❌✅ (primary)	0.5%	[-0.9%, 2.0%]	5

Only resolve target type in try_coerce in new solver #114648 (Comparison Link)

(instructions:u)	mean	range	count
Regressions ❌ (primary)	1.0%	[1.0%, 1.0%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-1.7%	[-1.8%, -1.6%]	2
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-0.8%	[-1.8%, 1.0%]	3

This was specifically added to undo regressions flagged in PR #114604
it did indeed undo the big changes: e.g. cranelift-codegen-0.82.1 had regressed by {2%, 1.7%}, and this improved it back by {-1.84%, -1.59%}
likewise cargo-0.60.0 had improved by -0.93%, and this regressed it back by 0.99%. (I.e. we returned to prior status quo.)
some other effects were not addressed by this PR, but they are all minor.
marking as triaged.

Only check outlives goals on impl compared to trait #109356 (Comparison Link)

(instructions:u)	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	0.4%	[0.4%, 0.4%]	2
Improvements ✅ (primary)	-0.9%	[-1.6%, -0.6%]	6
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-0.9%	[-1.6%, -0.6%]	6

regression is solely to the opt and debug profiles externs secondary benchmark, by a small amount.
marked as triaged

Respect #[expect] the same way #[allow] is with the dead_code lint #114710 (Comparison Link)

(instructions:u)	mean	range	count
Regressions ❌ (primary)	0.5%	[0.3%, 0.7%]	2
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.6%	[-0.8%, -0.5%]	3
All ❌✅ (primary)	0.5%	[0.3%, 0.7%]	2