2020-08-24 Triage Log

See the README for details on how this log was gathered.

This week saw an upgrade to LLVM 11, which resulted in large speedups to optimized builds. This offsets the slowdown we observed as part of the upgrade to LLVM 10. Many thanks to rust-lang and LLVM contributor @nikic for their work to measure LLVM performance. That upgrade did cause slight regressions to check and debug builds, but on the whole it is a significant win for compile times.

Triage done by @ecstaticmorse. Revision range: 67e7b9b8cf776222825dbbd4cb1e39b7765ef27c..03017003c77d782cf7ed841a05d7c628a9b93f25

1 Regression, 4 Improvements, 0 of them in rollups.

Regressions

#75555 Cargo update (almost) all the things!

• A very small regression

Improvements

#75145 Reference lang items during AST lowering

• An improvement of ~3% on await-call-tree
• Coupled with small improvements across the board

#75590 Add a packed/tagged pointer abstraction and utilize it for ParamEnv

• A small improvement on keccak/inflate

#73526 Upgrade to LLVM 11 (rc2)

• An improvement on optimized builds
• Tempered by a small regression on debug and check builds.

#75813 Lazy decoding of DefPathTable from crate metadata (non-incremental case)

• A major improvement on small crates, especially on check builds

Nags requiring follow up

None