a448f88b69
This implements support for applying PGO to the rustc compilation step (not standard library or any tooling, including rustdoc). Expanding PGO to more tools is not terribly difficult but will involve more work and greater CI time commitment. For the same reason of avoiding greater time commitment, this currently avoids implementing for platforms outside of x86_64-unknown-linux-gnu, though in practice it should be quite simple to extend over time to more platforms. The initial implementation is intentionally minimal here to avoid too much work investment before we start seeing wins for a subset of Rust users. The choice of workloads to profile here is somewhat arbitrary, but the general rationale was to aim for a small set that largely avoided time regressions on perf.rust-lang.org's full suite of crates. The set chosen is libcore, cargo (and its dependencies), and a few ad-hoc stress tests from perf.rlo. The stress tests are arguably the most controversial, but they benefit those cases (avoiding regressions) and do not really remove wins from other benchmarks. The primary next step after this PR lands is to implement support for PGO in LLVM. It is unclear whether we can afford a full LLVM rebuild in CI, though, so the approach taken there may need to be more staggered. rustc-only PGO seems well affordable on linux at least, giving us up to 20% wall time wins on some crates for 15 minutes of extra CI time (1 hour up from 45 minutes). The PGO data is uploaded to allow others to reuse it if attempting to reproduce the CI build or potentially, in the future, on other platforms where an off-by-one strategy is used for dist builds at minimal performance cost. |
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| .. | ||
| bootstrap | ||
| build_helper | ||
| ci | ||
| doc | ||
| etc | ||
| librustdoc | ||
| llvm-project@8d78ad1389 | ||
| test | ||
| tools | ||
| README.md | ||
| stage0.txt | ||
| version | ||
This directory contains the source code of the rust project, including:
- The test suite
- The bootstrapping build system
- Various submodules for tools, like rustdoc, rls, etc.
For more information on how various parts of the compiler work, see the rustc dev guide.