Chris Tate 4c3a1d9c98 Link the Linux release helpers against LLVM built with ThinLTO and a helper profile ...

The Linux helpers linked LLVM 22.1.8's release archive. The helper's code
generation is LLVM's code, so building that LLVM from its release sources
with ThinLTO and with a profile of the helper's own work makes code
generation 5-9% faster than the helper as released, with identical objects.

- native/llvm-codegen/llvm.profdata.gz is the profile, collected by
  scripts/refresh-llvm-profile.mjs: it builds LLVM with IR instrumentation
  and an instrumented helper, and runs that helper on tsc-ts, five Effect
  fixtures, the runtime benchmark workloads and every 50th corpus program
  (scripts/llvm-helper-inputs.mjs). It follows LLVM's sources, so it needs
  a refresh when LLVM is bumped.
- scripts/build-llvm-dist.mjs builds LLVM with that profile and ThinLTO,
  and packs it with a checksum. The llvm-dist workflow, run by hand, builds
  it for x64 and arm64, requires a helper linked against it to give the
  same objects as one linked against the release archive
  (scripts/check-llvm-dist.mjs), prints both helpers' times and the
  profile's mismatch count, and attaches the archive to the LLVM_DIST_TAG
  release of this repository.
- The release workflow's Linux jobs, and the wasm32-wasi job, which also
  uploads the x64 GNU helper, download that archive and build the helper
  with SCRIPTC_LLVM_THINLTO=1: clang, lld and ThinLTO, and the profile for
  the helper's own sources. Without the archive, or if that build fails,
  the helper links the release archive as before.
- The four Linux helper packages share their build in
  native/llvm-codegen/linux-helper.mjs. Without SCRIPTC_LLVM_THINLTO it
  builds the same executable as before.

2026-10-25 18:53:25 -05:00

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