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jolt/host/chez/seed
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Dmitri Sotnikov 8bea1abe12
Native record representation + inline nil?/some? (#222) 
Records were a jrec holding an alist of (kw . val) conses: ~113B/node, built
fresh per construction, field reads a list scan. Replace that with a shared
per-type descriptor (tag + field keywords + an eq?-keyed keyword->index table)
plus a flat per-instance value vector and an extension map for any non-field
keys assoc'd on (jolt-nil when there are none). Construction now allocates one
vector instead of a cons chain and a field read is an index lookup. binary-trees
construction allocation drops 2.085GB -> 1.19GB.

That alone barely moved binary-trees wall-time: profiling showed the read loop,
not allocation, dominates, and the read loop's own allocation came from (nil? l)
lowering to (jolt-invoke (var-deref "clojure.core" "nil?") l), which conses its
args every call. Add nil?/some? to the backend native-op table so they inline to
jolt-nil?/jolt-some? (and drop the truthy wrapper, like the other predicates).
check-tree's read loop goes from 1.476GB allocated to zero; binary-trees 18.9x
-> 9.7x vs JVM. The remaining gap is the field-read dispatch chain (jolt-c3mw).

Two JVM divergences fixed along the way, both certified:
- dissoc of a declared field downgrades a record to a plain map (was kept as a
  record); an extension key still drops cleanly.
- map->R keeps extension keys (was dropping anything outside the declared basis).

16 new corpus rows pin assoc/dissoc/count/keys/seq/=/hash/extension-field
behavior against JVM Clojure.

Co-authored-by: Yogthos <yogthos@gmail.com>
2026-06-26 05:42:24 +00:00
..
image.ss Native record representation + inline nil?/some? (#222) 2026-06-26 05:42:24 +00:00
prelude.ss Native record representation + inline nil?/some? (#222) 2026-06-26 05:42:24 +00:00
README.md Docs: Chez-only, drop the Janet-era references and obsolete migration notes 2026-06-22 09:05:35 -04:00

README.md

Chez bootstrap seed

These two files are the bootstrap compiler for jolt — the seed that makes the build self-hosting:

  • prelude.ss — the clojure.core prelude (all tiers + clojure.string/walk/ template/edn/set/pprint) as Scheme def-var! forms.
  • image.ss — the compiler image (jolt.ir + jolt.analyzer + jolt.backend-scheme) as Scheme def-var! forms.

Both are generated, not hand-written. They are checked in because a fresh checkout must be able to build jolt-on-Chez using only Chez: host/chez/bootstrap.ss loads this seed, then rebuilds the prelude + image from the .clj/.ss sources via the on-Chez compiler (read → analyze → emit, all on Chez). The seed is a joint byte-fixpoint: rebuilding from an up-to-date seed reproduces it exactly. make selfhost (host/chez/selfcheck.sh) runs host/chez/bootstrap.ss and diffs the rebuilt artifacts against the checked-in seed.

Re-minting

When the seed sources change (the core tiers, the compiler namespaces, the host contract, the reader, emit-image.ss), the seed drifts and make selfhost fails. Re-mint it by running host/chez/bootstrap.ss and writing the freshly rebuilt prelude/image back to host/chez/seed/prelude.ss / host/chez/seed/image.ss, then commit the refreshed files.