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perf(release): ship PGO builds of the tsc - #8
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The npm tsc was a plain fat-LTO build. The release job now also builds it with PGO on each platform: build-pgo.sh with an instrumented build, the training set of the new scripts/goport/pgo-train.sh (the gate's 4 projects and 3 realworld4 configs at fixed commits), llvm-profdata from the toolchain's llvm-tools, and a -Cprofile-use build. The job fails unless the PGO tsc gives the same stdout, stderr, exit code and emitted files as the plain tsc on that set. build-pgo.sh gets PGO_TARGET, PGO_BINS, PGO_TRAIN and PGO_CARGO, Linux-only ELF steps and link args, a profile file named by its hash, a check that the training wrote a profile, and help. Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
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Included review availability: This review used your included allowance. Your plan provides up to 10 included reviews per hour; 3 remain after this review. WalkthroughThe release workflow now builds a plain compiler reference and a PGO compiler using a training set. The training script prepares eight pinned projects and compares compiler outputs. The PGO build script supports configurable training, targets, binaries, Cargo commands, and linker settings. ChangesPGO release build
Priority: ➖ Normal Estimated code review effort: 3 (Moderate) | ~25 minutes Change: Feature Sequence Diagram(s)sequenceDiagram
participant ReleaseWorkflow
participant PgoTrain as pgo-train.sh
participant BuildPgo as build-pgo.sh
participant Cargo
ReleaseWorkflow->>Cargo: Build plain reference compiler
Cargo-->>ReleaseWorkflow: Return plain compiler
ReleaseWorkflow->>PgoTrain: Prepare training projects
ReleaseWorkflow->>BuildPgo: Start PGO build with training directory
BuildPgo->>Cargo: Build with generated profile
Cargo-->>BuildPgo: Return PGO compiler
ReleaseWorkflow->>PgoTrain: Compare compiler outputs
PgoTrain-->>ReleaseWorkflow: Return comparison result
Suggested reviewers: Merge Risk: ⚪ Minimal · up to The reviewed release changes are mergeable subject to normal checks; neither the training-set count nor the proposed cache setting requires a change. 🚥 Pre-merge checks | ✅ 4 | ❌ 1❌ Failed checks (1 warning)
✅ Passed checks (4 passed)
Full details: Docstring CoverageExplanation Docstring coverage is 70.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 10 functions across 2 files. (3 skipped: 3 unsupported.)
✨ Finishing Touches 💡 1🧪 Generate unit tests (beta)
🛠️ Fix failing CI checks 💡
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Review comments at @scripts/goport/pgo-train.sh:
- Around line 140-146: Update the exit-status handling in one() to fail on every
tsc status except success and the expected diagnostic statuses 1 and 2; retain
the existing handling for signal-killed runs and reject unexpected codes such as
127 before training or comparison continues.
- Around line 103-105: Update the dependency installation in setup so the full
training dependency tree is reproducible: generate and use a lockfile for the
created manifest, or install from the applicable project lockfiles. Remove the
no-package-lock option so npm honors the lockfile.
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.github/workflows/release.ymlcrates/ts_goport/scripts/build-pgo.shscripts/goport/pgo-train.sh
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pgo-train.sh installs with npm --before, so the packages that its lists do not name resolve to the same versions in every setup. A training or compare run that exits with anything but 0, 1 or 2 now stops the script. build-pgo.sh keeps the cargo command as an array, so a path with spaces works. Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
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PGO is great but as you can see build times blow up. Same applies to BOLT, except BOLT sometimes introduces crashes in my experience. Consider looking into AutoFDO and Propeller, although not sure how mature the latter is for rust. Can probably do some LLVM hacks. |
Build time overhead with PGO/BOLT is okay if we do it only for the actually released binaries - that's how PGO and BOLT are used by the Rustc compiler. Regarding new crashes from BOLT - yes, sometimes it's true, but each of them should be considered just as a bug in BOLT and reported to the upstream. Rustc uses BOLT for large-scale deployments, and it's still worth it. So I kindly suggest to not afraid to use it (however, from limitations point of view, PGO is much more stable compared to BOLT).
I think no need to use AutoFDO (Sampling PGO) if "regular" PGO (Instrumentation PGO) is already used sine AutoFDO has much more limitations (e.g. requires external tooling to convert profiles format, worse platform support, a bit less aggressive optimizations due to the nature of "sampled" profiles, etc.). Regarding Proppeller - it could be a promising one but no one in the Rust ecosystem tested it for Rust (I guess only Google tried to do it internally). So If you want to investigate it further - go ahead. But if you want to get the job done - just use BOLT instead (if you can). |
…lugin Since PR #4 the effect training config lists @effect/language-service, so PGO trained only the Effect path there. Training it both ways (pgotrain2 study, PGO-only bins on alvin) is 0.5% faster with and without the plugin; dropping the plugin from training instead makes plugin runs 2.3% slower. Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
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Note 🤖 Claude Opus 5.5 responding on behalf of Theo Pushed 08c2893: the training now runs the effect project twice, with and without the |
release.yml: the Build environment step writes CC_<target>=musl-gcc for the matrix target, and JEMALLOC_SYS_WITH_LG_PAGE=16 for aarch64, so the plain and the PGO build of both Linux tsc use them. The header keeps the PGO text and the arm64 platform line. Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
npm/README.md and the root README said the CI builds have no PGO. They now say each platform's tsc is a PGO build without BOLT, and that 0.1.0 has neither. Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
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Note 🤖 Claude Opus 5.5 responding on behalf of Theo I took this over after #10 landed. Changes:
All checks pass on 4d91ed9. The first |
…er, --singleThreaded tsc -b and watch carry ids, value_symbol_links newtype) followups38 is main 8ac70c6 plus 7 commits, so this merge also brings main's PR code (pingdotgg#8, pingdotgg#10, pingdotgg#19, pingdotgg#30) and the light flake fix bf57472. Conflict: crates/ts_goport/tests/early_emit.rs. - ours (int56, eeflake1): the full K2 test change; build_emit_only_solution uses Solution and waits with Solution::wait_for_a_later_mtime. - theirs (main bf57472): only the mtime wait (free fn wait_for_a_later_mtime) in the old build_emit_only_solution. Took ours, as state note main-flake-fix-2026-10-09 says (int56 carries the full eeflake1 change, which includes the mtime wait). Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
3 participants
The npm tsc has no PGO. A PGO build of the same source is 9% to 15% faster, and PGO + BOLT 20% to 22% on T3 Code.
How. The release build job now builds the tsc twice on each platform (linux-x64 and linux-arm64 static musl non-PIE, darwin-arm64):
crates/ts_goport/scripts/build-pgo.sh: an instrumented build, the training set,llvm-profdata merge, then a-Cprofile-usebuild. The workflow installsllvm-toolsfor the toolchain, and build-pgo.sh checks that itsllvm-profdatamatches rustc's LLVM. Each platform trains on its own profile.scripts/goport/pgo-train.sh compareruns the plain and the PGO tsc on the training set. The job fails when any stdout, stderr, exit code, emitted file or build info file differs. The PGO tsc is what gets packed.The training set (new
scripts/goport/pgo-train.sh) is the gate's 4 projects (query-core, hono, zod, effect) and 3 realworld4 configs: playcanvas (JS with JSDoc types and declaration emit), umami (a React TSX app) and nestjs-cqrs (decorators). Each one is a git checkout at a fixed commit, with the npm packages its config reads at the versions of its lock file, without install scripts.npm --beforepins the other packages to one date. The check run uses--noEmiton all 7; query, hono, playcanvas and nestjs-cqrs also emit into a temp dir. There is no editor session: build-release.sh uses those only for BOLT, because in PGO they made CLI runs slower.build-pgo.sh gets
PGO_TARGET,PGO_BINS,PGO_TRAINandPGO_CARGO, Linux-only ELF checks and link args, a profile file named by its hash (cargo does not see a changed profile with the same name), a check that the training wrote a profile,help, and bash 3.2 syntax for the Mac. Its default local use does not change.No BOLT. BOLT refuses the static Linux bin (decision D4: a dynamic link would allow it). BOLT's Mach-O support is experimental, and macOS has no perf branch sampling for its profile.
Verification (zbook, the Linux steps of the job: 1.95.0, x86_64-unknown-linux-musl, static non-PIE,
noembed):The PGO tsc is equal to the plain tsc on the training set (1,989 files: stdout, stderr, exit code, emit, build info), on the 4 gate project inputs (
--noEmit), and on the 2 T3 Code workspaces below.Timing on mini-743d (8 cores), plain against PGO tsc, both sides interleaved in one run:
T3 Code: median of 10,
tsc -p tsconfig.noeffect.json --noEmit(the bunperf1 configs without Effect), CPU time 0.869 and 0.877, peak RSS +4 MiB. Gate projects (they are in the training set):scripts/goport/perf.sh(median of 3) with--noEmit, peak RSS +0.3% to +3%. Output was equal on both T3 Code workspaces.CI on this PR (run 37911443049, on main with ci: build, test and release tsc-rs for linux-arm64 #10): all 3 build jobs pass. Each trains on its own platform (Linux 1 raw profile each, macOS 5) with the toolchain's
llvm-profdata(LLVM 22), and the compare step reports the same output on 1,993 files on all 3 platforms. The 3 verify jobs pass.CI cost. The build job goes from about 5 to 16 minutes on Linux x64, 17 minutes on macOS, and from about 11 to 39 minutes on Linux arm64 (the arm64 runner builds about 2.5 times slower): 2 more fat-LTO builds (about 10.5 minutes; their own target dirs, not cached), 30 to 45 seconds to fetch and install the training set (1.4 GB, most of it umami), and seconds for the training and the compare. The tsc file grows from 39.3 to 44.8 MB on Linux.
Linux arm64 (#10). #10 added the linux-arm64 build, so this branch merges main. The
Build environmentstep now writesCC_<target>=musl-gccfor the matrix target andJEMALLOC_SYS_WITH_LG_PAGE=16on aarch64, so the plain and the PGO build of both Linux tsc use them. arm64 gets PGO too. It needs no other change: the aarch64 musl rust-std has the profiler runtime, andllvm-toolsexists for the aarch64 Linux host. The cost is CI time only, and the arm64 job runs beside the other two. The arm64 speedup is not timed (we have no arm64 Linux timing host). The compare step checks that its output is equal to the plain build.The docs now say that the CI builds are PGO builds without BOLT (
npm/README.md, root README).Made by Claude Opus 5.5 in Claude Code (workflow subagent).
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Note
Ship PGO-trained tsc builds in the release workflow
Macroscope summarized 4d91ed9.
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