| # 2024-08-06 Triage Log |
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| This week saw several large improvements caused mostly by the [update to LLVM 19](https://github.com/rust-lang/rust/pull/127513). There were some regressions in several pull requests, but most of them were immediately fixed in a follow-up PR. |
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| Triage done by **@kobzol**. |
| Revision range: [7e3a9718..8c7e0e16](https://perf.rust-lang.org/?start=7e3a971870f23c94f7aceb53b490fb37333150ff&end=8c7e0e160831866bc1a40691a39455aac21271c0&absolute=false&stat=instructions%3Au) |
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| **Summary**: |
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| | (instructions:u) | mean | range | count | |
| |:----------------------------------:|:-----:|:---------------:|:-----:| |
| | Regressions ❌ <br /> (primary) | 1.0% | [0.2%, 3.8%] | 91 | |
| | Regressions ❌ <br /> (secondary) | 1.9% | [0.2%, 19.2%] | 104 | |
| | Improvements ✅ <br /> (primary) | -4.4% | [-15.8%, -0.3%] | 120 | |
| | Improvements ✅ <br /> (secondary) | -3.3% | [-10.4%, -0.2%] | 70 | |
| | All ❌✅ (primary) | -2.1% | [-15.8%, 3.8%] | 211 | |
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| 6 Regressions, 3 Improvements, 5 Mixed; 4 of them in rollups |
| 51 artifact comparisons made in total |
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| #### Regressions |
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| Rollup of 7 pull requests [#128413](https://github.com/rust-lang/rust/pull/128413) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=f8060d282d42770fadd73905e3eefb85660d3278&end=249cf71f11a29b3fb68e8a35969569d8bb7958ee&stat=instructions:u) |
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| | (instructions:u) | mean | range | count | |
| |:----------------------------------:|:----:|:------------:|:-----:| |
| | Regressions ❌ <br /> (primary) | 0.6% | [0.2%, 1.9%] | 28 | |
| | Regressions ❌ <br /> (secondary) | 0.3% | [0.2%, 0.4%] | 7 | |
| | Improvements ✅ <br /> (primary) | - | - | 0 | |
| | Improvements ✅ <br /> (secondary) | - | - | 0 | |
| | All ❌✅ (primary) | 0.6% | [0.2%, 1.9%] | 28 | |
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| - The regression was caused by https://github.com/rust-lang/rust/pull/128357. |
| - The regression should be fixed by https://github.com/rust-lang/rust/pull/128550. |
| - Marked as triaged. |
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| Rollup of 6 pull requests [#128469](https://github.com/rust-lang/rust/pull/128469) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=28a58f2fa7f0c46b8fab8237c02471a915924fe5&end=71b211609605590423a68ba3f503e53404d4fdb4&stat=instructions:u) |
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| | (instructions:u) | mean | range | count | |
| |:----------------------------------:|:-----:|:--------------:|:-----:| |
| | Regressions ❌ <br /> (primary) | 0.3% | [0.2%, 0.7%] | 10 | |
| | Regressions ❌ <br /> (secondary) | 1.0% | [0.2%, 2.1%] | 36 | |
| | Improvements ✅ <br /> (primary) | -0.2% | [-0.2%, -0.2%] | 1 | |
| | Improvements ✅ <br /> (secondary) | -2.5% | [-2.5%, -2.5%] | 1 | |
| | All ❌✅ (primary) | 0.3% | [-0.2%, 0.7%] | 11 | |
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| - The regression was caused by https://github.com/rust-lang/rust/pull/128443. |
| - The regression was later fixed in https://github.com/rust-lang/rust/pull/128544. |
| - Marked as triaged. |
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| Rewrite binary search implementation [#128254](https://github.com/rust-lang/rust/pull/128254) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=2cec7a85ed4868c90194a2187d2751788e298197&end=19326022d243f487b5752661cd9b597d620a489e&stat=instructions:u) |
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| | (instructions:u) | mean | range | count | |
| |:----------------------------------:|:-----:|:--------------:|:-----:| |
| | Regressions ❌ <br /> (primary) | 0.5% | [0.2%, 1.7%] | 16 | |
| | Regressions ❌ <br /> (secondary) | 6.2% | [0.2%, 19.5%] | 6 | |
| | Improvements ✅ <br /> (primary) | - | - | 0 | |
| | Improvements ✅ <br /> (secondary) | -4.1% | [-4.1%, -4.1%] | 1 | |
| | All ❌✅ (primary) | 0.5% | [0.2%, 1.7%] | 16 | |
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| - This PR optimized the standard library implementation of binary search. |
| - The regression is caused by LLVM spending more time in optimizing the new binary search, because it is now more amenable to unrolling and other optimizations. |
| - Marked as triaged. |
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| Rollup of 7 pull requests [#128614](https://github.com/rust-lang/rust/pull/128614) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=bbf60c897e18a72923129c63ff33ce2de2968815&end=64ebd39da5ec28caa3bd7cbb3f22f5949432fe2b&stat=instructions:u) |
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| | (instructions:u) | mean | range | count | |
| |:----------------------------------:|:----:|:------------:|:-----:| |
| | Regressions ❌ <br /> (primary) | - | - | 0 | |
| | Regressions ❌ <br /> (secondary) | 0.8% | [0.4%, 1.3%] | 10 | |
| | Improvements ✅ <br /> (primary) | - | - | 0 | |
| | Improvements ✅ <br /> (secondary) | - | - | 0 | |
| | All ❌✅ (primary) | - | - | 0 | |
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| - The regression was caused by https://github.com/rust-lang/rust/pull/127921. |
| - The compiler now performs more work, so a small regression is expected. |
| - Marked as triaged. |
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| Update the stdarch submodule [#128466](https://github.com/rust-lang/rust/pull/128466) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=8f63e9f8732d8688f2b5e1c816569f65ee185c7e&end=b389b0ab72cb0aa9acf4df0ae0c0e12090782da9&stat=instructions:u) |
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| | (instructions:u) | mean | range | count | |
| |:----------------------------------:|:----:|:------------:|:-----:| |
| | Regressions ❌ <br /> (primary) | 0.7% | [0.2%, 2.6%] | 13 | |
| | Regressions ❌ <br /> (secondary) | 1.0% | [0.2%, 4.3%] | 32 | |
| | Improvements ✅ <br /> (primary) | - | - | 0 | |
| | Improvements ✅ <br /> (secondary) | - | - | 0 | |
| | All ❌✅ (primary) | 0.7% | [0.2%, 2.6%] | 13 | |
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| - Small regression on several benchmarks, caused by the standard library becoming larger. |
| - Marked as triaged. |
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| Enforce supertrait outlives obligations hold when confirming impl [#124336](https://github.com/rust-lang/rust/pull/124336) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=83e9b93c90bcd7f52d17d09b52e3a2eff707c46a&end=2b78d920964e1d70927bcd208529bda0e11120d0&stat=instructions:u) |
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| | (instructions:u) | mean | range | count | |
| |:----------------------------------:|:----:|:------------:|:-----:| |
| | Regressions ❌ <br /> (primary) | 0.6% | [0.2%, 1.5%] | 95 | |
| | Regressions ❌ <br /> (secondary) | 1.8% | [0.2%, 4.2%] | 38 | |
| | Improvements ✅ <br /> (primary) | - | - | 0 | |
| | Improvements ✅ <br /> (secondary) | - | - | 0 | |
| | All ❌✅ (primary) | 0.6% | [0.2%, 1.5%] | 95 | |
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| - Medium regression on a lot of primary benchmarks. |
| - Not marking as triaged yet, investigation ongoing. |
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| #### Improvements |
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| Rollup of 6 pull requests [#128504](https://github.com/rust-lang/rust/pull/128504) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=e60ebb2f2c1facba87e7971798f3cbdfd309cd23&end=a886938671e1fde9d7271dce8ca3d6938bae9d2e&stat=instructions:u) |
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| | (instructions:u) | mean | range | count | |
| |:----------------------------------:|:-----:|:--------------:|:-----:| |
| | Regressions ❌ <br /> (primary) | - | - | 0 | |
| | Regressions ❌ <br /> (secondary) | - | - | 0 | |
| | Improvements ✅ <br /> (primary) | - | - | 0 | |
| | Improvements ✅ <br /> (secondary) | -0.4% | [-0.5%, -0.3%] | 12 | |
| | All ❌✅ (primary) | - | - | 0 | |
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| Delegation: second attempt to improve perf [#128441](https://github.com/rust-lang/rust/pull/128441) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=64ebd39da5ec28caa3bd7cbb3f22f5949432fe2b&end=8f63e9f8732d8688f2b5e1c816569f65ee185c7e&stat=instructions:u) |
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| | (instructions:u) | mean | range | count | |
| |:----------------------------------:|:-----:|:--------------:|:-----:| |
| | Regressions ❌ <br /> (primary) | - | - | 0 | |
| | Regressions ❌ <br /> (secondary) | - | - | 0 | |
| | Improvements ✅ <br /> (primary) | -0.4% | [-0.7%, -0.2%] | 9 | |
| | Improvements ✅ <br /> (secondary) | -0.5% | [-1.1%, -0.1%] | 9 | |
| | All ❌✅ (primary) | -0.4% | [-0.7%, -0.2%] | 9 | |
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| Check divergence value first before doing span operations in `warn_if_unreachable` [#128544](https://github.com/rust-lang/rust/pull/128544) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=ebd08d8ed5c8904de8700def78adc1dbd5727684&end=ab1527f1d6560168f9fd36fa8cd7ba677c1d36ad&stat=instructions:u) |
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| | (instructions:u) | mean | range | count | |
| |:----------------------------------:|:-----:|:--------------:|:-----:| |
| | Regressions ❌ <br /> (primary) | - | - | 0 | |
| | Regressions ❌ <br /> (secondary) | - | - | 0 | |
| | Improvements ✅ <br /> (primary) | -0.3% | [-0.5%, -0.2%] | 21 | |
| | Improvements ✅ <br /> (secondary) | -1.0% | [-2.1%, -0.2%] | 34 | |
| | All ❌✅ (primary) | -0.3% | [-0.5%, -0.2%] | 21 | |
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| #### Mixed |
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| Delegation: support generics for delegation from free functions [#125929](https://github.com/rust-lang/rust/pull/125929) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=e69c19ea0b8cf29ab8188a0eb5e899655464a1ff&end=1ddedbaa5919b7b3e70d984660e21e844c615c97&stat=instructions:u) |
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| | (instructions:u) | mean | range | count | |
| |:----------------------------------:|:-----:|:--------------:|:-----:| |
| | Regressions ❌ <br /> (primary) | 0.4% | [0.2%, 0.8%] | 11 | |
| | Regressions ❌ <br /> (secondary) | 0.5% | [0.1%, 1.2%] | 10 | |
| | Improvements ✅ <br /> (primary) | - | - | 0 | |
| | Improvements ✅ <br /> (secondary) | -0.3% | [-0.4%, -0.2%] | 2 | |
| | All ❌✅ (primary) | 0.4% | [0.2%, 0.8%] | 11 | |
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| - The regression was resolved in https://github.com/rust-lang/rust/pull/128441. |
| - Marked as triaged. |
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| Update to LLVM 19 [#127513](https://github.com/rust-lang/rust/pull/127513) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=e552c168c72c95dc28950a9aae8ed7030199aa0d&end=0b5eb7ba7bd796fb39c8bb6acd9ef6c140f28b65&stat=instructions:u) |
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| | (instructions:u) | mean | range | count | |
| |:----------------------------------:|:-----:|:---------------:|:-----:| |
| | Regressions ❌ <br /> (primary) | 1.3% | [0.2%, 3.6%] | 13 | |
| | Regressions ❌ <br /> (secondary) | 0.9% | [0.2%, 3.4%] | 37 | |
| | Improvements ✅ <br /> (primary) | -3.2% | [-15.8%, -0.2%] | 172 | |
| | Improvements ✅ <br /> (secondary) | -2.6% | [-10.5%, -0.2%] | 82 | |
| | All ❌✅ (primary) | -2.9% | [-15.8%, 3.6%] | 185 | |
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| - This was a large performance increase caused by an update to LLVM 19. |
| - Improvement far outweigh the regressions. |
| - Marked as triaged. |
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| Accelerate GVN a little [#126991](https://github.com/rust-lang/rust/pull/126991) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=99322d84c4e216940621c356787331d8ae362326&end=28a58f2fa7f0c46b8fab8237c02471a915924fe5&stat=instructions:u) |
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| | (instructions:u) | mean | range | count | |
| |:----------------------------------:|:-----:|:--------------:|:-----:| |
| | Regressions ❌ <br /> (primary) | 0.3% | [0.3%, 0.3%] | 1 | |
| | Regressions ❌ <br /> (secondary) | 2.1% | [2.1%, 2.1%] | 1 | |
| | Improvements ✅ <br /> (primary) | -0.4% | [-0.4%, -0.3%] | 2 | |
| | Improvements ✅ <br /> (secondary) | -0.7% | [-1.0%, -0.4%] | 6 | |
| | All ❌✅ (primary) | -0.2% | [-0.4%, 0.3%] | 3 | |
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| - More improvements than regressions. |
| - Marked as triaged. |
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| Revert recent changes to dead code analysis [#128404](https://github.com/rust-lang/rust/pull/128404) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=ad0a2b7180c06514370c4c7a7a73ee75158e88fa&end=1f47624f9abad7974afe1c016a4e8b07f4254ee4&stat=instructions:u) |
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| | (instructions:u) | mean | range | count | |
| |:----------------------------------:|:-----:|:---------------:|:-----:| |
| | Regressions ❌ <br /> (primary) | - | - | 0 | |
| | Regressions ❌ <br /> (secondary) | 1.1% | [0.7%, 1.7%] | 9 | |
| | Improvements ✅ <br /> (primary) | -0.4% | [-1.2%, -0.2%] | 47 | |
| | Improvements ✅ <br /> (secondary) | -2.9% | [-10.7%, -0.2%] | 15 | |
| | All ❌✅ (primary) | -0.4% | [-1.2%, -0.2%] | 47 | |
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| - More improvements than regressions. |
| - Marked as triaged. |
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| Change output normalization logic to be linear against size of output [#128200](https://github.com/rust-lang/rust/pull/128200) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=c9687a95a602091777e28703aa5abf20f1ce1797&end=8c7e0e160831866bc1a40691a39455aac21271c0&stat=instructions:u) |
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| | (instructions:u) | mean | range | count | |
| |:----------------------------------:|:-----:|:--------------:|:-----:| |
| | Regressions ❌ <br /> (primary) | - | - | 0 | |
| | Regressions ❌ <br /> (secondary) | 0.4% | [0.3%, 0.5%] | 6 | |
| | Improvements ✅ <br /> (primary) | -0.9% | [-2.6%, -0.2%] | 19 | |
| | Improvements ✅ <br /> (secondary) | -0.5% | [-0.7%, -0.3%] | 10 | |
| | All ❌✅ (primary) | -0.9% | [-2.6%, -0.2%] | 19 | |
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| - This PR fixed a small regression from https://github.com/rust-lang/rust/pull/127528. |
| - More improvements than regressions. |
| - Marked as triaged. |
