| # 2021-08-25 Triage Log |
| |
| A few regressions but largely an improvement this week, mostly due to the |
| upgrade to LLVM 13. |
| |
| Triage done by **@simulacrum**. |
| Revision range: [aa8f27bf4d980023a8b245ceb25a490a18041eb2..33fdb797f59421c7bbecaa4588ed5d7a31a9494a](https://perf.rust-lang.org/?start=aa8f27bf4d980023a8b245ceb25a490a18041eb2&end=33fdb797f59421c7bbecaa4588ed5d7a31a9494a&absolute=false&stat=instructions%3Au) |
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| 2 Regressions, 1 Improvements, 2 Mixed; 0 of them in rollups |
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| #### Regressions |
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| Update the backtrace crate in libstd [#88151](https://github.com/rust-lang/rust/issues/88151) |
| - Large regression in [instruction counts](https://perf.rust-lang.org/compare.html?start=2451f42c1deb9379d5e8e5fa86b0bf857ae048ec&end=7960030d6915a771f5ab72c3897a7ed50c3ed4bd&stat=instructions:u) (up to 2.6% on `incr-patched: u8 3072` builds of `issue-46449`) |
| - Standard regression from an increase in std/core size due to added items. |
| |
| Add fast path for Path::cmp that skips over long shared prefixes [#86898](https://github.com/rust-lang/rust/issues/86898) |
| - Small improvement in [instruction counts](https://perf.rust-lang.org/compare.html?start=7611fe438dae91084d17022e705bf64374d5ba4b&end=bcfd3f7e88084850f87b8e34b4dcb9fceb872d00&stat=instructions:u) (up to -0.3% on `incr-unchanged` builds of `helloworld`) |
| - Moderate regression in [instruction counts](https://perf.rust-lang.org/compare.html?start=7611fe438dae91084d17022e705bf64374d5ba4b&end=bcfd3f7e88084850f87b8e34b4dcb9fceb872d00&stat=instructions:u) (up to 1.2% on `incr-patched: println` builds of `ripgrep`) |
| - Largely in -doc builds, seems to be a small but real regression. |
| |
| #### Improvements |
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| Reenable RemoveZsts [#88176](https://github.com/rust-lang/rust/issues/88176) |
| - Large improvement in [instruction counts](https://perf.rust-lang.org/compare.html?start=d77dcbc5993a06d200fc1fa5554778bc8fb67d36&end=914a1e2c517dfbaa23a4ec4a3eebefb3e2c253c2&stat=instructions:u) (up to -4.2% on `incr-unchanged` builds of `deeply-nested-async`) |
| |
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| #### Mixed |
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| Revert "Auto merge of #83417 - erikdesjardins:enableremovezsts, r=oli-obk" [#88056](https://github.com/rust-lang/rust/issues/88056) |
| - Small improvement in [instruction counts](https://perf.rust-lang.org/compare.html?start=aa8f27bf4d980023a8b245ceb25a490a18041eb2&end=806b3995b8f622d5de10afcc11c10a028a7b876a&stat=instructions:u) (up to -0.5% on `incr-patched: println` builds of `cargo`) |
| - Large regression in [instruction counts](https://perf.rust-lang.org/compare.html?start=aa8f27bf4d980023a8b245ceb25a490a18041eb2&end=806b3995b8f622d5de10afcc11c10a028a7b876a&stat=instructions:u) (up to 4.5% on `incr-unchanged` builds of `deeply-nested-async`) |
| - Regression is canceled out by the later #88176 (see improvements above). |
| |
| |
| Upgrade to LLVM 13 [#87570](https://github.com/rust-lang/rust/issues/87570) |
| - Very large improvement in [instruction counts](https://perf.rust-lang.org/compare.html?start=e7f7fe462a54b1caeb804a974cd43ba9fd7bee5c&end=db002a06ae9154a35d410550bc5132df883d7baa&stat=instructions:u) (up to -10.4% on `incr-unchanged` builds of `helloworld`) |
| - Very large regression in [instruction counts](https://perf.rust-lang.org/compare.html?start=e7f7fe462a54b1caeb804a974cd43ba9fd7bee5c&end=db002a06ae9154a35d410550bc5132df883d7baa&stat=instructions:u) (up to 9.6% on `full` builds of `match-stress-enum`) |
| - Overall an improvement, regressions are significantly more limited to just a |
| few cases compared to the improvements seen across the board. |
| |
| #### Untriaged Pull Requests |
| |
| - [#87815 encode `generics_of` for fields and ty params](https://github.com/rust-lang/rust/pull/87815) |
| - [#87781 Remove box syntax from compiler and tools](https://github.com/rust-lang/rust/pull/87781) |
| - [#87640 Rollup of 9 pull requests](https://github.com/rust-lang/rust/pull/87640) |
| - [#87587 Various refactorings of the TAIT infrastructure](https://github.com/rust-lang/rust/pull/87587) |
| - [#87570 Upgrade to LLVM 13](https://github.com/rust-lang/rust/pull/87570) |
| - [#87244 Better diagnostics with mismatched types due to implicit static lifetime](https://github.com/rust-lang/rust/pull/87244) |
| - [#86777 Include terminators in instance size estimate](https://github.com/rust-lang/rust/pull/86777) |
| - [#86698 Move OnDiskCache to rustc_query_impl.](https://github.com/rust-lang/rust/pull/86698) |
| - [#86588 Rollup of 8 pull requests](https://github.com/rust-lang/rust/pull/86588) |
| - [#86034 Change entry point to 🛡️ against 💥 💥-payloads](https://github.com/rust-lang/rust/pull/86034) |
| - [#84560 Inline Iterator as IntoIterator.](https://github.com/rust-lang/rust/pull/84560) |
| - [#80357 Introduce `hir::ExprKind::Let` - Take 2](https://github.com/rust-lang/rust/pull/80357) |
