| # 2022-05-03 Triage Log |
| |
| Performance overall improved in the last week, but some of this is due to fixing |
| regressions from prior weeks. This week also brings an average of 4% improvement |
| in memory usage across all profiles due to |
| [#95171](https://github.com/rust-lang/rust/pull/95171) bumping the LLVM/clang |
| used on x86_64-unknown-linux-gnu to compile C and C++ code linked into rustc. |
| |
| Triage done by **@simulacrum**. |
| Revision range: [1c988cfa0b7f4d3bc5b1cb40dc5002f5adbfb9ad..468492c2af3993f18b1fe98052200575c4a2e678](https://perf.rust-lang.org/?start=1c988cfa0b7f4d3bc5b1cb40dc5002f5adbfb9ad&end=468492c2af3993f18b1fe98052200575c4a2e678&absolute=false&stat=instructions%3Au) |
| |
| **Summary**: |
| | | Regressions 😿 <br />(primary) | Regressions 😿 <br />(secondary) | Improvements 🎉 <br />(primary) | Improvements 🎉 <br />(secondary) | All 😿 🎉 <br />(primary) | |
| |:----------:|:------------------------------:|:--------------------------------:|:-------------------------------:|:---------------------------------:|:------------------------:| |
| | count | 13 | 1 | 78 | 29 | 91 | |
| | mean | 0.8% | 0.3% | -0.9% | -0.8% | -0.7% | |
| | max | 1.5% | 0.3% | -2.7% | -2.1% | -2.7% | |
| |
| |
| 4 Regressions, 3 Improvements, 1 Mixed; 1 of them in rollups |
| 52 artifact comparisons made in total |
| |
| #### Regressions |
| |
| Rollup of 8 pull requests [#96428](https://github.com/rust-lang/rust/pull/96428) |
| [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=3d237ab52920924694f6fc3e47ee8588514bfa70&end=082e4ca49770ebc9cb0ee616f3726a67471be8cb&stat=instructions:u) |
| | | Regressions 😿 <br />(primary) | Regressions 😿 <br />(secondary) | Improvements 🎉 <br />(primary) | Improvements 🎉 <br />(secondary) | All 😿 🎉 <br />(primary) | |
| |:----------:|:------------------------------:|:--------------------------------:|:-------------------------------:|:---------------------------------:|:------------------------:| |
| | count | 7 | 2 | 1 | 0 | 8 | |
| | mean | 1.3% | 0.3% | -0.4% | N/A | 1.1% | |
| | max | 1.8% | 0.3% | -0.4% | N/A | 1.8% | |
| |
| Looks likely to be related to the new [`impl Default for |
| AssertUnwindSafe`](https://github.com/rust-lang/rust/pull/95949), though |
| detailed query pages do not reflect the regressions. Marking the regression as |
| triaged, because it's unlikely we would want to revert the impl at this point. |
| However, it's probably the case that impls for public standard library types may |
| want to avoid being rolled up, as they can influence downstream performance |
| across both rustdoc and regular compilation. |
| |
| Enforce Copy bounds for repeat elements while considering lifetimes [#95819](https://github.com/rust-lang/rust/pull/95819) |
| [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=1c8966e5e9dc099b55206f34af81242d03bdb413&end=a707f401074bc769bab4efb2bfdde7f6c5a4068d&stat=instructions:u) |
| | | Regressions 😿 <br />(primary) | Regressions 😿 <br />(secondary) | Improvements 🎉 <br />(primary) | Improvements 🎉 <br />(secondary) | All 😿 🎉 <br />(primary) | |
| |:----------:|:------------------------------:|:--------------------------------:|:-------------------------------:|:---------------------------------:|:------------------------:| |
| | count | 2 | 0 | 0 | 0 | 2 | |
| | mean | 0.8% | N/A | N/A | N/A | 0.8% | |
| | max | 1.0% | N/A | N/A | N/A | 1.0% | |
| |
| Incremental-only regressions in a single benchmark. Looks likely to be a |
| somewhat real change, but not one we can do much about: the extra enforcement |
| naturally adds dependency edges which require re-computing. |
| |
| Handle generic bounds in a uniform way in HIR [#93803](https://github.com/rust-lang/rust/pull/93803) |
| [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=76d4862fdd131b6f79dc0a31857f888d26bcdb27&end=d201c812d40932509b2b5307c0b20c1ce78d21da&stat=instructions:u) |
| | | Regressions 😿 <br />(primary) | Regressions 😿 <br />(secondary) | Improvements 🎉 <br />(primary) | Improvements 🎉 <br />(secondary) | All 😿 🎉 <br />(primary) | |
| |:----------:|:------------------------------:|:--------------------------------:|:-------------------------------:|:---------------------------------:|:------------------------:| |
| | count | 11 | 4 | 0 | 0 | 11 | |
| | mean | 0.3% | 0.3% | N/A | N/A | 0.3% | |
| | max | 0.5% | 0.3% | N/A | N/A | 0.5% | |
| |
| A regression primarily to diesel (quite common this week), but relatively slight |
| and with a relatively good tradeoff to code maintenance. Earlier PR runs had |
| some slight improvements which were used as a justification for regresions on |
| benchmarks; this doesn't seem to be the case anymore, so asked for an updated |
| justification on the regression. |
| |
| Inline core::panic::Location methods [#96348](https://github.com/rust-lang/rust/pull/96348) |
| [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=d201c812d40932509b2b5307c0b20c1ce78d21da&end=579d26876ddc5426be32cca1a026b6fd7fc5be24&stat=instructions:u) |
| | | Regressions 😿 <br />(primary) | Regressions 😿 <br />(secondary) | Improvements 🎉 <br />(primary) | Improvements 🎉 <br />(secondary) | All 😿 🎉 <br />(primary) | |
| |:----------:|:------------------------------:|:--------------------------------:|:-------------------------------:|:---------------------------------:|:------------------------:| |
| | count | 0 | 11 | 0 | 0 | 0 | |
| | mean | N/A | 0.5% | N/A | N/A | N/A | |
| | max | N/A | 0.8% | N/A | N/A | N/A | |
| |
| Secondary-only regressions, most likely due to slightly different codegen in |
| relatively hot code (e.g., due to increased or decreased register pressure). Not |
| likely to be an important change. |
| |
| #### Improvements |
| |
| Fix incremental perf regression unsafety checking [#96425](https://github.com/rust-lang/rust/pull/96425) |
| [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=082e4ca49770ebc9cb0ee616f3726a67471be8cb&end=a7197189cd0e3a86d1b661d1dceb8bdff021d0b8&stat=instructions:u) |
| | | Regressions 😿 <br />(primary) | Regressions 😿 <br />(secondary) | Improvements 🎉 <br />(primary) | Improvements 🎉 <br />(secondary) | All 😿 🎉 <br />(primary) | |
| |:----------:|:------------------------------:|:--------------------------------:|:-------------------------------:|:---------------------------------:|:------------------------:| |
| | count | 0 | 0 | 48 | 0 | 48 | |
| | mean | N/A | N/A | -1.2% | N/A | -1.2% | |
| | max | N/A | N/A | -2.8% | N/A | -2.8% | |
| |
| Reduce duplication of RPO calculation of mir [#96500](https://github.com/rust-lang/rust/pull/96500) |
| [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=0c8e520b3e0d9fbdafb8311f1b18a1f847531051&end=9a98c63b30bd8419be662b8fb3f3b22ba33d72c5&stat=instructions:u) |
| | | Regressions 😿 <br />(primary) | Regressions 😿 <br />(secondary) | Improvements 🎉 <br />(primary) | Improvements 🎉 <br />(secondary) | All 😿 🎉 <br />(primary) | |
| |:----------:|:------------------------------:|:--------------------------------:|:-------------------------------:|:---------------------------------:|:------------------------:| |
| | count | 0 | 0 | 43 | 17 | 43 | |
| | mean | N/A | N/A | -0.5% | -0.7% | -0.5% | |
| | max | N/A | N/A | -0.9% | -1.4% | -0.9% | |
| |
| Move Derefer before Retag [#96549](https://github.com/rust-lang/rust/pull/96549) |
| [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=508e0584e384556b7e66f57b62e4feeba864b6da&end=6eda7642bd284d3d2bc6a1d57b68e2ef2b65e062&stat=instructions:u) |
| | | Regressions 😿 <br />(primary) | Regressions 😿 <br />(secondary) | Improvements 🎉 <br />(primary) | Improvements 🎉 <br />(secondary) | All 😿 🎉 <br />(primary) | |
| |:----------:|:------------------------------:|:--------------------------------:|:-------------------------------:|:---------------------------------:|:------------------------:| |
| | count | 0 | 0 | 20 | 18 | 20 | |
| | mean | N/A | N/A | -0.4% | -0.4% | -0.4% | |
| | max | N/A | N/A | -0.4% | -0.6% | -0.4% | |
| |
| |
| #### Mixed |
| |
| Inline `__iterator_get_unchecked` for some iterator adapters. [#92566](https://github.com/rust-lang/rust/pull/92566) |
| [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=bed05e996e37e44b1a3980b84754af621fd3c4ce&end=3d0ac7ea23888438752957eeeb5aa2b73b4fda72&stat=instructions:u) |
| | | Regressions 😿 <br />(primary) | Regressions 😿 <br />(secondary) | Improvements 🎉 <br />(primary) | Improvements 🎉 <br />(secondary) | All 😿 🎉 <br />(primary) | |
| |:----------:|:------------------------------:|:--------------------------------:|:-------------------------------:|:---------------------------------:|:------------------------:| |
| | count | 1 | 2 | 3 | 1 | 4 | |
| | mean | 0.2% | 0.3% | -0.4% | -0.2% | -0.2% | |
| | max | 0.2% | 0.3% | -0.4% | -0.2% | -0.4% | |
| |
| Update LLVM used for building rustc in CI for x64 [#95171](https://github.com/rust-lang/rust/pull/95171) |
| [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=b2c2a32870e15af02eb89de434c36535439dbf5a&end=1388b38c52d1ca9fbc80bf42fa007504fb0b1b41) |
| | | Regressions 😿 <br />(primary) | Regressions 😿 <br />(secondary) | Improvements 🎉 <br />(primary) | Improvements 🎉 <br />(secondary) | All 😿 🎉 <br />(primary) | |
| |:----------:|:------------------------------:|:--------------------------------:|:-------------------------------:|:---------------------------------:|:------------------------:| |
| | count | 0 | 0 | 1 | 0 | 1 | |
| | mean | N/A | N/A | -0.5% | N/A | -0.5% | |
| | max | N/A | N/A | -0.5% | N/A | -0.5% | |
| |
| A solid improvement in memory usage, with a rough average of 4% less memory used |
| across many check, debug, and opt builds, presumably due to better |
| optimizations when compiling C and C++ code linked into rustc. |
| |
