Add triage for this week

triage/2024-09-16.md

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+# 2024-09-16 Triage Log
+
+A relatively quiet week, with overall neutral performance across our set of key
+metrics (instructions, cycles, memory).
+
+Triage done by **@simulacrum**.
+Revision range: [263a3aee..170d6cb8](https://perf.rust-lang.org/?start=263a3aeeb8f2d0e9cc85eee61774d1f5f23dc3f5&end=170d6cb845c8c3f0dcec5cdd4210df9ecf990244&absolute=false&stat=instructions%3Au)
+
+**Summary**:
+
+| (instructions:u)                   | mean  | range          | count |
+|:----------------------------------:|:-----:|:--------------:|:-----:|
+| Regressions ❌ <br /> (primary)    | 0.7%  | [0.2%, 4.0%]   | 52    |
+| Regressions ❌ <br /> (secondary)  | 0.7%  | [0.2%, 1.4%]   | 48    |
+| Improvements ✅ <br /> (primary)   | -0.8% | [-2.6%, -0.2%] | 46    |
+| Improvements ✅ <br /> (secondary) | -0.5% | [-1.1%, -0.1%] | 25    |
+| All ❌✅ (primary)                 | 0.0%  | [-2.6%, 4.0%]  | 98    |
+
+
+2 Regressions, 3 Improvements, 4 Mixed; 2 of them in rollups
+54 artifact comparisons made in total
+
+#### Regressions
+
+interpret: make typed copies lossy wrt provenance and padding [#129778](https://github.com/rust-lang/rust/pull/129778) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=712463de61c65033a6f333f0a14fbb65e34efc50&end=304b7f801bab31233680879ca4fb6eb294706a59&stat=instructions:u)
+
+| (instructions:u)                   | mean | range        | count |
+|:----------------------------------:|:----:|:------------:|:-----:|
+| Regressions ❌ <br /> (primary)    | -    | -            | 0     |
+| Regressions ❌ <br /> (secondary)  | 2.1% | [0.2%, 4.7%] | 13    |
+| Improvements ✅ <br /> (primary)   | -    | -            | 0     |
+| Improvements ✅ <br /> (secondary) | -    | -            | 0     |
+| All ❌✅ (primary)                 | -    | -            | 0     |
+
+Most of the performance is recovered in https://github.com/rust-lang/rust/pull/130197.
+
+generalize: track relevant info in cache key [#130194](https://github.com/rust-lang/rust/pull/130194) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=4c5fc2c334f1cc305eea79ed0b8fdb276342d101&end=5a2dd7d4f3210629e65879aeecbe643ba3b86bb4&stat=instructions:u)
+
+| (instructions:u)                   | mean  | range          | count |
+|:----------------------------------:|:-----:|:--------------:|:-----:|
+| Regressions ❌ <br /> (primary)    | -     | -              | 0     |
+| Regressions ❌ <br /> (secondary)  | 1.0%  | [0.4%, 1.3%]   | 16    |
+| Improvements ✅ <br /> (primary)   | -     | -              | 0     |
+| Improvements ✅ <br /> (secondary) | -0.2% | [-0.2%, -0.2%] | 1     |
+| All ❌✅ (primary)                 | -     | -              | 0     |
+
+Soundness fix and regressions only in secondary benchmarks.
+
+#### Improvements
+
+rustdoc: use strategic boxing to shrink `clean::Item` [#129789](https://github.com/rust-lang/rust/pull/129789) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=c2f74c3f928aeb503f15b4e9ef5778e77f3058b8&end=712463de61c65033a6f333f0a14fbb65e34efc50&stat=instructions:u)
+
+| (instructions:u)                   | mean  | range          | count |
+|:----------------------------------:|:-----:|:--------------:|:-----:|
+| Regressions ❌ <br /> (primary)    | -     | -              | 0     |
+| Regressions ❌ <br /> (secondary)  | -     | -              | 0     |
+| Improvements ✅ <br /> (primary)   | -0.5% | [-1.0%, -0.2%] | 15    |
+| Improvements ✅ <br /> (secondary) | -0.5% | [-0.6%, -0.3%] | 19    |
+| All ❌✅ (primary)                 | -0.5% | [-1.0%, -0.2%] | 15    |
+
+
+rustdoc: unify the short-circuit on all lints [#129975](https://github.com/rust-lang/rust/pull/129975) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=6f7229c4da0471f1470bb1f86071848cba3a23d9&end=a9fb00bfa4b3038c855b2097b54e05e8c198c183&stat=instructions:u)
+
+| (instructions:u)                   | mean  | range          | count |
+|:----------------------------------:|:-----:|:--------------:|:-----:|
+| Regressions ❌ <br /> (primary)    | -     | -              | 0     |
+| Regressions ❌ <br /> (secondary)  | -     | -              | 0     |
+| Improvements ✅ <br /> (primary)   | -0.7% | [-2.0%, -0.2%] | 10    |
+| Improvements ✅ <br /> (secondary) | -0.4% | [-0.4%, -0.4%] | 1     |
+| All ❌✅ (primary)                 | -0.7% | [-2.0%, -0.2%] | 10    |
+
+
+Rollup of 10 pull requests [#130253](https://github.com/rust-lang/rust/pull/130253) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=8d6b88b168e45ee1624699c19443c49665322a91&end=3afb2bb76ce56e860e45d8858ef5b5f00059e1b1&stat=instructions:u)
+
+| (instructions:u)                   | mean  | range          | count |
+|:----------------------------------:|:-----:|:--------------:|:-----:|
+| Regressions ❌ <br /> (primary)    | 0.2%  | [0.2%, 0.2%]   | 1     |
+| Regressions ❌ <br /> (secondary)  | -     | -              | 0     |
+| Improvements ✅ <br /> (primary)   | -0.8% | [-1.5%, -0.2%] | 13    |
+| Improvements ✅ <br /> (secondary) | -     | -              | 0     |
+| All ❌✅ (primary)                 | -0.7% | [-1.5%, 0.2%]  | 14    |
+
+
+#### Mixed
+
+Revert "Stabilize `-Znext-solver=coherence`" [#130249](https://github.com/rust-lang/rust/pull/130249) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=7c7372b6a1b9a8d6b787a3e5a10e4f8325b1fdfc&end=f753bc769b16ca9673f11a4cc06e5cc681efd84e&stat=instructions:u)
+
+| (instructions:u)                   | mean  | range          | count |
+|:----------------------------------:|:-----:|:--------------:|:-----:|
+| Regressions ❌ <br /> (primary)    | 3.7%  | [2.9%, 4.5%]   | 7     |
+| Regressions ❌ <br /> (secondary)  | -     | -              | 0     |
+| Improvements ✅ <br /> (primary)   | -0.5% | [-0.9%, -0.2%] | 13    |
+| Improvements ✅ <br /> (secondary) | -0.5% | [-0.7%, -0.1%] | 9     |
+| All ❌✅ (primary)                 | 1.0%  | [-0.9%, 4.5%]  | 20    |
+
+Largely resets to the previous state on a couple benchmarks. Expected given the revert.
+
+Rollup of 5 pull requests [#130281](https://github.com/rust-lang/rust/pull/130281) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=8c0ec05f7dc9ef185eea9f36c5638e74e43935bf&end=2e8db5e9e39c2bf7729113b3041ef4011d90ac5a&stat=instructions:u)
+
+| (instructions:u)                   | mean  | range          | count |
+|:----------------------------------:|:-----:|:--------------:|:-----:|
+| Regressions ❌ <br /> (primary)    | 0.6%  | [0.6%, 0.6%]   | 1     |
+| Regressions ❌ <br /> (secondary)  | 0.2%  | [0.2%, 0.2%]   | 1     |
+| Improvements ✅ <br /> (primary)   | -0.2% | [-0.2%, -0.2%] | 1     |
+| Improvements ✅ <br /> (secondary) | -1.8% | [-2.0%, -1.6%] | 6     |
+| All ❌✅ (primary)                 | 0.2%  | [-0.2%, 0.6%]  | 2     |
+
+Regressions are minor enough that given the rollup and lack of obviously
+relevant PRs I'm just marking as triaged. The primary regressed benchmark is
+webrender and only in full LLVM builds which doesn't seem like it maps well
+onto the contained PRs.
+
+Rescope temp lifetime in if-let into IfElse with migration lint [#107251](https://github.com/rust-lang/rust/pull/107251) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=d3a8524e80244d66968ab4522d31145ccba610f4&end=a5efa01895e82fa705146507d15311b29c715450&stat=instructions:u)
+
+| (instructions:u)                   | mean  | range          | count |
+|:----------------------------------:|:-----:|:--------------:|:-----:|
+| Regressions ❌ <br /> (primary)    | -     | -              | 0     |
+| Regressions ❌ <br /> (secondary)  | 0.6%  | [0.2%, 1.3%]   | 19    |
+| Improvements ✅ <br /> (primary)   | -0.2% | [-0.2%, -0.2%] | 1     |
+| Improvements ✅ <br /> (secondary) | -     | -              | 0     |
+| All ❌✅ (primary)                 | -0.2% | [-0.2%, -0.2%] | 1     |
+
+Seems like the regression is primarily looking like a revert of #127313...
+@cjgillot do you have thoughts on what the delta here might be? I don't see a
+very obvious cause here. Regressions are minor enough that I'm not worried, but
+just checking if there's an easy explanation.
+
+Simplify the canonical clone method and the copy-like forms to copy [#128299](https://github.com/rust-lang/rust/pull/128299) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=02b1be16c65e5716ade771afde7116ebdfbf9b4a&end=e7386b361dda8c2222bee7a1ae79faba7e9a0351&stat=instructions:u)
+
+| (instructions:u)                   | mean  | range          | count |
+|:----------------------------------:|:-----:|:--------------:|:-----:|
+| Regressions ❌ <br /> (primary)    | 0.4%  | [0.2%, 0.8%]   | 6     |
+| Regressions ❌ <br /> (secondary)  | 0.4%  | [0.2%, 2.1%]   | 16    |
+| Improvements ✅ <br /> (primary)   | -0.8% | [-1.7%, -0.3%] | 12    |
+| Improvements ✅ <br /> (secondary) | -     | -              | 0     |
+| All ❌✅ (primary)                 | -0.4% | [-1.7%, 0.8%]  | 18    |
+
+Likely expected regressions from direct changes to codegen, possibly giving
+LLVM more freedom to optimize:
+
+> This pass improves performance by reducing the amount of MIR. The generated
+> copies will get merged/expanded/whatever by LLVM, with a completely different
+> heuristic.
+
+(https://github.com/rust-lang/rust/pull/128299#pullrequestreview-2217057820)
+
+