Low Level Tools/2019Q2
Implement "pipelined" rustc compilation (compiler side).
- 100% completed.
- Don't generate unnecessary rmeta files. A precursor.
- In JSON output, emit a directive after metadata is generated. The part that lets rustc tell Cargo when metadata has been written.
- Emit metadata files earlier. So that significant crate overlapping can occur.
- Tracking issue for stabilizing "pipelined compilation" has been opened.
- Announcement email to dev-platform
- Speed-ups depend on program structure and configuration, but up to 1.84x has been observed.
- Speedups for opt builds of notable projects on my 14-core Linux box:
- webrender: 1.27x
- cranelift-codegen: 1.20x
- Firefox: 1.07x
- script-servo: 1.07x
- style-servo: 1.06x
Ship GWP in Nightly.
Land 5 changes that speed up or reduce peak memory usage of rustc.
- 100%+ completed.
- Increase `Span` from 4 bytes to 8 bytes. A big win across lots of workloads, especially larger crates: some script-servo builds are 15% faster.
- Avoid `hygiene_data` lookups. Up to 10% speed-up on packed-simd, up to 3% on numerous others.
- Special-case literals in `parse_bottom_expr`. Up to 7% win on programs with large constants.
- Avoid more hygiene lookups. Up to 2% speed-up on many benchmarks.
- Reduce the `DepNode` pre-allocation ratio. Reduces peak memory use by 20 MiB on some workloads.
- Use `Symbol` more. Up to 1% speed-up, as well as making the code nicer. Should also help with parallel rustc.
- Use `Symbol` even more. Up to 1% speed-up. Should also help with parallel rustc.