Triage 2024 03 19

triage/2024-03-19.md

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+# 2024-03-19 Triage Log
+
+Even though the summary might not look like it, this was actually a relatively quiet week,
+with a few small regressions. The large regression that is also shown in the summary table was
+caused by extending the verification of incremental compilation results.
+However, this verification is not actually fully enabled by default, so these regressions are mostly
+only visible in our benchmarking suite, which enables the verification to achieve more deterministic
+benchmarking results. One small regression was also caused by enabling frame pointers for the Rust
+standard library, which should improve profiling of Rust programs.
+
+Triage done by **@kobzol**.
+Revision
+range: [e919669d..21d94a3d](https://perf.rust-lang.org/?start=e919669d42dfb8950866d4cb268c5359eb3f7c54&end=21d94a3d2c63cacf8eaf9d0ca770c0b450c558d4&absolute=false&stat=instructions%3Au)
+
+**Summary**:
+
+|         (instructions:u)          | mean  |     range      | count |
+|:---------------------------------:|:-----:|:--------------:|:-----:|
+|  Regressions ❌ <br /> (primary)   | 2.5%  |  [0.4%, 7.8%]  |  207  |
+| Regressions ❌ <br /> (secondary)  | 2.9%  |  [0.2%, 8.3%]  |  128  |
+|  Improvements ✅ <br /> (primary)  |   -   |       -        |   0   |
+| Improvements ✅ <br /> (secondary) | -1.0% | [-1.3%, -0.4%] |   4   |
+|         All ❌✅ (primary)          | 2.5%  |  [0.4%, 7.8%]  |  207  |
+
+4 Regressions, 1 Improvements, 6 Mixed; 4 of them in rollups
+67 artifact comparisons made in total
+
+#### Regressions
+
+Make `DefiningAnchor::Bind` only store the opaque types that may be constrained, instead of the
+current infcx root
+item. [#121796](https://github.com/rust-lang/rust/pull/121796) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=6554a5645a13e4d9331fd028960d69be91d7492d&end=4ccbb7dc95596c7fc0c5756fdc47a17a56c085d3&stat=instructions:u)
+
+|         (instructions:u)          | mean |    range     | count |
+|:---------------------------------:|:----:|:------------:|:-----:|
+|  Regressions ❌ <br /> (primary)   | 0.6% | [0.2%, 1.8%] |  112  |
+| Regressions ❌ <br /> (secondary)  | 0.7% | [0.2%, 1.8%] |  27   |
+|  Improvements ✅ <br /> (primary)  |  -   |      -       |   0   |
+| Improvements ✅ <br /> (secondary) |  -   |      -       |   0   |
+|         All ❌✅ (primary)          | 0.6% | [0.2%, 1.8%] |  112  |
+
+* This is a refactoring of the "old" trait solver that was necessary for follow-up compiler changes.
+
+Rollup of 12 pull
+requests [#122389](https://github.com/rust-lang/rust/pull/122389) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=7de1a1f6db26cf7af43cca74819118428e6317ee&end=6b1e5d9db3b0d569bd847fdcb98c85ee8f7a8ef1&stat=instructions:u)
+
+|         (instructions:u)          | mean |    range     | count |
+|:---------------------------------:|:----:|:------------:|:-----:|
+|  Regressions ❌ <br /> (primary)   | 0.7% | [0.7%, 0.7%] |   3   |
+| Regressions ❌ <br /> (secondary)  | 1.1% | [0.5%, 2.1%] |   3   |
+|  Improvements ✅ <br /> (primary)  |  -   |      -       |   0   |
+| Improvements ✅ <br /> (secondary) |  -   |      -       |   0   |
+|         All ❌✅ (primary)          | 0.7% | [0.7%, 0.7%] |   3   |
+
+* Noise, marked as triaged.
+
+Verify that query keys result in unique dep
+nodes [#122227](https://github.com/rust-lang/rust/pull/122227) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=e61dcc7a0ac33ef054d76453307124233edcf545&end=d3555f3d8e555ce488bbf8eee5eccdb66a464e14&stat=instructions:u)
+
+|         (instructions:u)          | mean  |     range      | count |
+|:---------------------------------:|:-----:|:--------------:|:-----:|
+|  Regressions ❌ <br /> (primary)   | 2.0%  |  [0.2%, 7.8%]  |  193  |
+| Regressions ❌ <br /> (secondary)  | 2.4%  |  [0.3%, 7.8%]  |  153  |
+|  Improvements ✅ <br /> (primary)  |   -   |       -        |   0   |
+| Improvements ✅ <br /> (secondary) | -1.3% | [-1.3%, -1.3%] |   1   |
+|         All ❌✅ (primary)          | 2.0%  |  [0.2%, 7.8%]  |  193  |
+
+* This PR adds additional verification to the compiler that checks if incremental compilation didn't
+  encounter problems.
+* This result looks quite bad, but that is mostly caused by the configuration of our benchmark
+  suite, which fully enables this verification to make benchmarking more deterministic.
+* Normal builds of user code should not be affected by this change.
+
+Enable frame pointers for the standard
+library [#122646](https://github.com/rust-lang/rust/pull/122646) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=13abc0ac9b2b77299cf02d634fc409e26a180ef3&end=3cdcdaf31b45f8045164aae9604573d23091970b&stat=instructions:u)
+
+|         (instructions:u)          | mean  |     range      | count |
+|:---------------------------------:|:-----:|:--------------:|:-----:|
+|  Regressions ❌ <br /> (primary)   | 0.3%  |  [0.2%, 0.6%]  |  70   |
+| Regressions ❌ <br /> (secondary)  | 0.3%  |  [0.2%, 0.5%]  |  22   |
+|  Improvements ✅ <br /> (primary)  |   -   |       -        |   0   |
+| Improvements ✅ <br /> (secondary) | -2.0% | [-2.0%, -2.0%] |   1   |
+|         All ❌✅ (primary)          | 0.3%  |  [0.2%, 0.6%]  |  70   |
+
+* This PR has a small instruction count cost across the board, but cycles and walltime were affected
+  much less.
+* It enables frame pointers for the Rust standard library, which should make profiling of Rust code
+  more robust and accurate, which should be worth this small perf. hit.
+* Marked as triaged.
+
+#### Improvements
+
+Rollup of 15 pull
+requests [#122338](https://github.com/rust-lang/rust/pull/122338) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=65cd843ae06ad00123c131a431ed5304e4cd577a&end=6554a5645a13e4d9331fd028960d69be91d7492d&stat=instructions:u)
+
+|         (instructions:u)          | mean  |     range      | count |
+|:---------------------------------:|:-----:|:--------------:|:-----:|
+|  Regressions ❌ <br /> (primary)   |   -   |       -        |   0   |
+| Regressions ❌ <br /> (secondary)  |   -   |       -        |   0   |
+|  Improvements ✅ <br /> (primary)  | -1.2% | [-1.2%, -1.1%] |   4   |
+| Improvements ✅ <br /> (secondary) | -0.8% | [-1.2%, -0.4%] |  13   |
+|         All ❌✅ (primary)          | -1.2% | [-1.2%, -1.1%] |   4   |
+
+#### Mixed
+
+Update
+cargo [#122394](https://github.com/rust-lang/rust/pull/122394) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=6b1e5d9db3b0d569bd847fdcb98c85ee8f7a8ef1&end=a165f1f65015b1bd4afd2ec50700aaacf2e0c485&stat=instructions:u)
+
+|         (instructions:u)          | mean  |     range      | count |
+|:---------------------------------:|:-----:|:--------------:|:-----:|
+|  Regressions ❌ <br /> (primary)   |   -   |       -        |   0   |
+| Regressions ❌ <br /> (secondary)  | 1.1%  |  [1.1%, 1.1%]  |   1   |
+|  Improvements ✅ <br /> (primary)  | -0.7% | [-0.7%, -0.7%] |   3   |
+| Improvements ✅ <br /> (secondary) | -0.5% | [-0.6%, -0.3%] |   5   |
+|         All ❌✅ (primary)          | -0.7% | [-0.7%, -0.7%] |   3   |
+
+* Most likely noise.
+
+more eagerly instantiate
+binders [#119849](https://github.com/rust-lang/rust/pull/119849) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=30f74ff0dc4d66debc8b50724c446f817e5f75f4&end=fd27e8745f0f04dc7c289893ef54a618c7c9e1da&stat=instructions:u)
+
+|         (instructions:u)          | mean  |     range      | count |
+|:---------------------------------:|:-----:|:--------------:|:-----:|
+|  Regressions ❌ <br /> (primary)   | 0.7%  |  [0.2%, 1.1%]  |  14   |
+| Regressions ❌ <br /> (secondary)  | 0.5%  |  [0.4%, 1.0%]  |   7   |
+|  Improvements ✅ <br /> (primary)  |   -   |       -        |   0   |
+| Improvements ✅ <br /> (secondary) | -1.2% | [-1.4%, -1.1%] |   6   |
+|         All ❌✅ (primary)          | 0.7%  |  [0.2%, 1.1%]  |  14   |
+
+* A small regression for trait-heavy crates, caused by a fix to the trait solver.
+* Marked as triaged.
+
+Rollup of 9 pull
+requests [#122607](https://github.com/rust-lang/rust/pull/122607) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=4c1b9c3e2f402efe27a24e424c9b59aa2fa5c83f&end=c8813ddd6d2602ae5473752031fd16ba70a6e4a7&stat=instructions:u)
+
+|         (instructions:u)          | mean  |     range      | count |
+|:---------------------------------:|:-----:|:--------------:|:-----:|
+|  Regressions ❌ <br /> (primary)   | 1.7%  |  [1.7%, 1.7%]  |   1   |
+| Regressions ❌ <br /> (secondary)  | 2.7%  |  [2.7%, 2.7%]  |   1   |
+|  Improvements ✅ <br /> (primary)  |   -   |       -        |   0   |
+| Improvements ✅ <br /> (secondary) | -5.3% | [-5.3%, -5.3%] |   1   |
+|         All ❌✅ (primary)          | 1.7%  |  [1.7%, 1.7%]  |   1   |
+
+* The largest regression was caused by [#122601](https://github.com/rust-lang/rust/pull/122601),
+  which should enable more LLVM optimizations, so some regressions to `opt` benchmarks is expected.
+* Marked as triaged.
+
+Move generic `NonZero` `rustc_layout_scalar_valid_range_start` attribute to inner
+type. [#121885](https://github.com/rust-lang/rust/pull/121885) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=c8813ddd6d2602ae5473752031fd16ba70a6e4a7&end=a615cea3339046c7ab2d75cd253727d1fd42dd0b&stat=instructions:u)
+
+|         (instructions:u)          | mean  |     range      | count |
+|:---------------------------------:|:-----:|:--------------:|:-----:|
+|  Regressions ❌ <br /> (primary)   | 0.4%  |  [0.3%, 0.6%]  |   9   |
+| Regressions ❌ <br /> (secondary)  | 0.2%  |  [0.2%, 0.2%]  |   1   |
+|  Improvements ✅ <br /> (primary)  |   -   |       -        |   0   |
+| Improvements ✅ <br /> (secondary) | -2.8% | [-2.8%, -2.8%] |   1   |
+|         All ❌✅ (primary)          | 0.4%  |  [0.3%, 0.6%]  |   9   |
+
+* A small regression caused by internal refactoring in the compiler. Marked as triaged.
+
+Rollup of 8 pull
+requests [#122690](https://github.com/rust-lang/rust/pull/122690) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=3cdcdaf31b45f8045164aae9604573d23091970b&end=d31b6fb8c06b43536ac5be38462d2a55784e2199&stat=instructions:u)
+
+|         (instructions:u)          | mean  |     range      | count |
+|:---------------------------------:|:-----:|:--------------:|:-----:|
+|  Regressions ❌ <br /> (primary)   |   -   |       -        |   0   |
+| Regressions ❌ <br /> (secondary)  | 2.7%  |  [0.2%, 5.3%]  |   2   |
+|  Improvements ✅ <br /> (primary)  | -0.2% | [-0.3%, -0.2%] |   7   |
+| Improvements ✅ <br /> (secondary) | -0.4% | [-0.5%, -0.3%] |   9   |
+|         All ❌✅ (primary)          | -0.2% | [-0.3%, -0.2%] |   7   |
+
+* Most likely noise, marked as triaged.
+
+Rollup of 11 pull
+requests [#122713](https://github.com/rust-lang/rust/pull/122713) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=d31b6fb8c06b43536ac5be38462d2a55784e2199&end=3c85e56249b0b1942339a6a989a971bf6f1c9e0f&stat=instructions:u)
+
+|         (instructions:u)          | mean  |     range      | count |
+|:---------------------------------:|:-----:|:--------------:|:-----:|
+|  Regressions ❌ <br /> (primary)   | 1.0%  |  [0.5%, 1.4%]  |   3   |
+| Regressions ❌ <br /> (secondary)  |   -   |       -        |   0   |
+|  Improvements ✅ <br /> (primary)  |   -   |       -        |   0   |
+| Improvements ✅ <br /> (secondary) | -0.5% | [-0.9%, -0.4%] |   7   |
+|         All ❌✅ (primary)          | 1.0%  |  [0.5%, 1.4%]  |   3   |
+
+* Small regression in match checking caused
+  by [#121823](https://github.com/rust-lang/rust/pull/121823),
+  which improves compiler diagnostics.
+* Marked as triaged.