perf triage for this week.

triage/2022-10-04.md

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+# 2022-10-04 Triage Log
+
+A great week, with 170 primary benchmark scenarios seeing improvement. Every PR
+flagged by perf provided at least some wins, and perhaps more impressive: No
+rollup PR's were flagged by perf this week! Furthermore, cjgillot fixed an issue
+where incremental compilation was being unnecessarily hindered by our span and
+lint system. Great work everyone!
+
+Triage done by **@pnkfelix**.
+Revision range: [d9297d22..02cd79af](https://perf.rust-lang.org/?start=d9297d22ad9edc2b56f0dd8734c1187a0c88be69&end=02cd79afb8080fce8c8ce35533c54d8ecf8f390e&absolute=false&stat=instructions%3Au)
+
+**Summary**:
+
+| (instructions:u) | mean | range | count |
+|:----------------:|:----:|:-----:|:-----:|
+| Regressions ❌ <br /> (primary) | 1.2% | [0.4%, 1.9%] | 2     |
+| Regressions ❌ <br /> (secondary) | 0.5% | [0.4%, 0.6%] | 6     |
+| Improvements ✅ <br /> (primary) | -2.4% | [-31.0%, -0.2%] | 170   |
+| Improvements ✅ <br /> (secondary) | -1.5% | [-5.8%, -0.3%] | 159   |
+| All ❌✅ (primary) | -2.4% | [-31.0%, 1.9%] | 172   |
+
+
+0 Regressions, 2 Improvements, 7 Mixed; 0 of them in rollups
+54 artifact comparisons made in total
+
+#### Regressions
+
+
+
+#### Improvements
+
+More lexer improvements [#102302](https://github.com/rust-lang/rust/pull/102302) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=837bf370de144a682041e68bb67469b9f68a55ce&end=6201eabde85db854c1ebb57624be5ec699246b50&stat=instructions:u)
+
+| (instructions:u) | mean | range | count |
+|:----------------:|:----:|:-----:|:-----:|
+| Regressions ❌ <br /> (primary) | -    | -     | 0     |
+| Regressions ❌ <br /> (secondary) | 2.2% | [2.2%, 2.2%] | 1     |
+| Improvements ✅ <br /> (primary) | -0.5% | [-1.0%, -0.2%] | 80    |
+| Improvements ✅ <br /> (secondary) | -0.8% | [-1.8%, -0.3%] | 75    |
+| All ❌✅ (primary) | -0.5% | [-1.0%, -0.2%] | 80    |
+
+
+Inline a few functions. [#102387](https://github.com/rust-lang/rust/pull/102387) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=b3aa4997d4817c5ea2b33ba20f6fe7c695e4f64c&end=4a0ee3cdc66573c8b46471462db7088a89d25183&stat=instructions:u)
+
+| (instructions:u) | mean | range | count |
+|:----------------:|:----:|:-----:|:-----:|
+| Regressions ❌ <br /> (primary) | -    | -     | 0     |
+| Regressions ❌ <br /> (secondary) | -    | -     | 0     |
+| Improvements ✅ <br /> (primary) | -0.4% | [-1.0%, -0.2%] | 60    |
+| Improvements ✅ <br /> (secondary) | -0.8% | [-2.3%, -0.3%] | 42    |
+| All ❌✅ (primary) | -0.4% | [-1.0%, -0.2%] | 60    |
+
+
+#### Mixed
+
+Rewrite and refactor format_args!() builtin macro. [#100996](https://github.com/rust-lang/rust/pull/100996) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=90c34fafcfa1d00ae25a165dc006e688761a5776&end=d6734be398fde0b078cde298e0d84eeccd71d08e&stat=instructions:u)
+
+| (instructions:u) | mean | range | count |
+|:----------------:|:----:|:-----:|:-----:|
+| Regressions ❌ <br /> (primary) | -    | -     | 0     |
+| Regressions ❌ <br /> (secondary) | 1.5% | [1.1%, 2.0%] | 6     |
+| Improvements ✅ <br /> (primary) | -0.3% | [-0.7%, -0.2%] | 7     |
+| Improvements ✅ <br /> (secondary) | -1.2% | [-1.5%, -0.6%] | 7     |
+| All ❌✅ (primary) | -0.3% | [-0.7%, -0.2%] | 7     |
+
+* [already triaged](https://github.com/rust-lang/rust/pull/100996#issuecomment-1260438437)
+
+rustdoc: Remove `clean::TraitWithExtraInfo` and queryify `is_notable_trait` [#102384](https://github.com/rust-lang/rust/pull/102384) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=ce7f0f1aa0f02c45cad0749e63f3086234b1f422&end=b30c88623cf1f8f3e67b189fb2c5df5a0d89aaed&stat=instructions:u)
+
+| (instructions:u) | mean | range | count |
+|:----------------:|:----:|:-----:|:-----:|
+| Regressions ❌ <br /> (primary) | 0.3% | [0.3%, 0.3%] | 1     |
+| Regressions ❌ <br /> (secondary) | 2.7% | [2.7%, 2.7%] | 1     |
+| Improvements ✅ <br /> (primary) | -    | -     | 0     |
+| Improvements ✅ <br /> (secondary) | -1.4% | [-1.7%, -1.2%] | 12    |
+| All ❌✅ (primary) | 0.3% | [0.3%, 0.3%] | 1     |
+
+* [already triaged](https://github.com/rust-lang/rust/pull/102384#issuecomment-1261912595)
+
+Fix perf regression from TypeVisitor changes [#101893](https://github.com/rust-lang/rust/pull/101893) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=65445a571c11f07f4ca1ed0f63bad247ae295bd0&end=9f1a21ae2bd41b3dd335c44f38f29a1fb8712ddc&stat=instructions:u)
+
+| (instructions:u) | mean | range | count |
+|:----------------:|:----:|:-----:|:-----:|
+| Regressions ❌ <br /> (primary) | -    | -     | 0     |
+| Regressions ❌ <br /> (secondary) | 1.4% | [1.2%, 1.6%] | 6     |
+| Improvements ✅ <br /> (primary) | -    | -     | 0     |
+| Improvements ✅ <br /> (secondary) | -1.3% | [-2.9%, -0.5%] | 9     |
+| All ❌✅ (primary) | -    | -     | 0     |
+
+* [already triaged](https://github.com/rust-lang/rust/pull/101893#issuecomment-1262863099)
+
+Shrink `hir::def::Res` [#101887](https://github.com/rust-lang/rust/pull/101887) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=9c56d9d6fec6262bbb1549cfe466a812ae2c6523&end=1bb8d276c94c77a5fada815c5fad3b8d324adac4&stat=instructions:u)
+
+| (instructions:u) | mean | range | count |
+|:----------------:|:----:|:-----:|:-----:|
+| Regressions ❌ <br /> (primary) | -    | -     | 0     |
+| Regressions ❌ <br /> (secondary) | 1.2% | [0.6%, 1.6%] | 7     |
+| Improvements ✅ <br /> (primary) | -0.2% | [-0.3%, -0.2%] | 5     |
+| Improvements ✅ <br /> (secondary) | -0.3% | [-0.4%, -0.3%] | 2     |
+| All ❌✅ (primary) | -0.2% | [-0.3%, -0.2%] | 5     |
+
+* [already triaged](https://github.com/rust-lang/rust/pull/101887#issuecomment-1263228790)
+
+Move lint level source explanation to the bottom [#101986](https://github.com/rust-lang/rust/pull/101986) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=277bb6653b55475b5fbce6309e9852fa2100dabe&end=744e397d8855f7da87d70aa8d0bd9e0f5f0b51a1&stat=instructions:u)
+
+| (instructions:u) | mean | range | count |
+|:----------------:|:----:|:-----:|:-----:|
+| Regressions ❌ <br /> (primary) | -    | -     | 0     |
+| Regressions ❌ <br /> (secondary) | 1.0% | [0.9%, 1.0%] | 2     |
+| Improvements ✅ <br /> (primary) | -0.3% | [-0.3%, -0.2%] | 3     |
+| Improvements ✅ <br /> (secondary) | -0.9% | [-1.4%, -0.3%] | 8     |
+| All ❌✅ (primary) | -0.3% | [-0.3%, -0.2%] | 3     |
+
+* [already triaged](https://github.com/rust-lang/rust/pull/101986#issuecomment-1264764911)
+
+Compute lint levels by definition [#102236](https://github.com/rust-lang/rust/pull/102236) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=56a35bc906be1250a76fdb9a4b70e9261e10aec5&end=57f097ea25f2c05f424fc9b9dc50dbd6d399845c&stat=instructions:u)
+
+| (instructions:u) | mean | range | count |
+|:----------------:|:----:|:-----:|:-----:|
+| Regressions ❌ <br /> (primary) | 0.6% | [0.3%, 0.9%] | 14    |
+| Regressions ❌ <br /> (secondary) | 1.0% | [0.2%, 2.0%] | 20    |
+| Improvements ✅ <br /> (primary) | -3.2% | [-30.2%, -0.2%] | 84    |
+| Improvements ✅ <br /> (secondary) | -1.1% | [-2.8%, -0.3%] | 52    |
+| All ❌✅ (primary) | -2.7% | [-30.2%, 0.9%] | 98    |
+
+
+* based on reading of [#101620](https://github.com/rust-lang/rust/issues/101620), this was an important step for making incremental compilation apply to a much broader set of input code.
+* the performance gains reported by perf seem well worth the cost that it registered.
+* marked as triaged.
+
+Mark Cell::replace() as #[inline] [#102548](https://github.com/rust-lang/rust/pull/102548) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=c2590e6e892cce1105cc57b480aa07a51ae95fe5&end=756e7be5eb923ec955dfd8dec2a0d3ac81cfdf55&stat=instructions:u)
+
+| (instructions:u) | mean | range | count |
+|:----------------:|:----:|:-----:|:-----:|
+| Regressions ❌ <br /> (primary) | 0.9% | [0.4%, 1.8%] | 3     |
+| Regressions ❌ <br /> (secondary) | 0.9% | [0.2%, 1.3%] | 10    |
+| Improvements ✅ <br /> (primary) | -0.3% | [-1.2%, -0.2%] | 14    |
+| Improvements ✅ <br /> (secondary) | -0.4% | [-1.9%, -0.2%] | 12    |
+| All ❌✅ (primary) | -0.1% | [-1.2%, 1.8%] | 17    |
+
+* PR had intermediate perf run reported stats that are somewhat better than what we actually ended up with in the end.
+* did not mark as triaged; pinged a reviewer to confirm that this still meets acceptable criteria from their POV.
+
+
+#### Untriaged Pull Requests
+
+- [#102548 Mark Cell::replace() as #[inline]](https://github.com/rust-lang/rust/pull/102548)
+- [#102236 Compute lint levels by definition](https://github.com/rust-lang/rust/pull/102236)
+- [#101858 derive various impls instead of hand-rolling them](https://github.com/rust-lang/rust/pull/101858)
+- [#101857 change `FnMutDelegate` to trait objects](https://github.com/rust-lang/rust/pull/101857)
+- [#101620 Compute lint levels by definition](https://github.com/rust-lang/rust/pull/101620)
+- [#101433 Emit a note that static bounds from HRTBs are a bug](https://github.com/rust-lang/rust/pull/101433)
+- [#100982 Require `#[const_trait]` on `Trait` for `impl const Trait`](https://github.com/rust-lang/rust/pull/100982)
+- [#100963 Rollup of 15 pull requests](https://github.com/rust-lang/rust/pull/100963)
+- [#100869 Replace `rustc_data_structures::thin_vec::ThinVec` with `thin_vec::ThinVec`](https://github.com/rust-lang/rust/pull/100869)
+- [#100841 update Miri](https://github.com/rust-lang/rust/pull/100841)
+- [#100759 Make `const_eval_select` a real intrinsic](https://github.com/rust-lang/rust/pull/100759)
+- [#100748 add `depth_limit` in `QueryVTable` to avoid entering a new tcx in `layout_of`](https://github.com/rust-lang/rust/pull/100748)
+- [#100676 implied bounds: explicitly state which types are assumed to be wf](https://github.com/rust-lang/rust/pull/100676)
+- [#100652 Remove deferred sized checks (make them eager)](https://github.com/rust-lang/rust/pull/100652)
+- [#100497 Avoid cloning a collection only to iterate over it](https://github.com/rust-lang/rust/pull/100497)
+- [#100429 rustdoc: Merge source code pages HTML elements together](https://github.com/rust-lang/rust/pull/100429)
+- [#100293 Add inline-llvm option for disabling/enabling LLVM inlining](https://github.com/rust-lang/rust/pull/100293)
+- [#100096 a fn pointer doesn't implement `Fn`/`FnMut`/`FnOnce` if its return type isn't sized](https://github.com/rust-lang/rust/pull/100096)
+- [#99792 Rollup of 8 pull requests](https://github.com/rust-lang/rust/pull/99792)
+- [#99520 Rollup of 9 pull requests](https://github.com/rust-lang/rust/pull/99520)
+- [#99251 Upgrade indexmap and thorin-dwp to use hashbrown 0.12](https://github.com/rust-lang/rust/pull/99251)
+- [#99231 Rollup of 5 pull requests](https://github.com/rust-lang/rust/pull/99231)
+- [#99210 Rollup of 5 pull requests](https://github.com/rust-lang/rust/pull/99210)
+- [#99126 remove allow(rustc::potential_query_instability) in rustc_span](https://github.com/rust-lang/rust/pull/99126)
+- [#99123 proc_macro: use crossbeam channels for the proc_macro cross-thread bridge](https://github.com/rust-lang/rust/pull/99123)
+- [#99102 Rework definition of MIR phases to more closely reflect semantic concerns](https://github.com/rust-lang/rust/pull/99102)
+- [#99047 Rollup of 6 pull requests](https://github.com/rust-lang/rust/pull/99047)
+- [#99014 Rollup of 8 pull requests](https://github.com/rust-lang/rust/pull/99014)
+- [#98987 Rollup of 7 pull requests](https://github.com/rust-lang/rust/pull/98987)
+- [#98957  don't allow ZST in ScalarInt ](https://github.com/rust-lang/rust/pull/98957)