simon/jolt
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Bare-index field reads for statically-known records (#228)

Browse source 
When the inference types a keyword-lookup receiver as a record — it carries the
field-order :shape and :hint :struct from the whole-program fixpoint — the back
end reads the field by its declared slot via jrec-field-at instead of jolt-get.
That skips the jolt-get case-lambda, the dispatch fn, and the field-key
hashtable lookup, leaving a jrec? check + a static-index vector-ref.

jrec-field-at falls back to jolt-get when the receiver isn't the expected record
(a map downgraded by dissoc, or a value the inference mistyped), so it stays
correct if the static type is wrong. Only the no-default form takes the bare
path (a declared field is always present).

Sound only for non-nil records: a self-recursive param that can be nil (e.g.
binary-trees check-tree, whose untagged child is nil at leaves) types :any and
keeps jolt-get — the whole-program fixpoint demotes it. The target is non-nil
record params, like a Vec3 dot product (~5% there; boxed-flonum arithmetic
dominates the rest, a separate numeric lever).

run-fieldread.ss gate: emitted form uses jrec-field-at at the right slot and
matches jolt-get for each declared field; a non-field key and a default-arg form
keep the generic path. make test / shakesmoke green, 0 new divergences.

Co-authored-by: Yogthos <yogthos@gmail.com>
This commit is contained in:
Dmitri Sotnikov 2026-06-26 11:29:14 +00:00 • committed by GitHub
parent af11aaa7ff
commit de31221573
No known key found for this signature in database
GPG key ID: B5690EEEBB952194
5 changed files with 188 additions and 80 deletions
Download patch file Download diff file Expand all files Collapse all files

11
host/chez/records.ss
View file

@ -146,6 +146,17 @@
=> (lambda (m) (jolt-invoke m coll k d)))
(else d))
v))))))
;; bare-index field read for a statically-known record field — emitted by `jolt
;; build --opt` for a struct-typed receiver, where i is the field's declared slot.
;; When r is the expected record it reads the value vector directly: no field-key
;; hashtable lookup, no jolt-get dispatch. Falls back to jolt-get otherwise (a map
;; downgraded by dissoc, or a value the inference mistyped), so it stays correct
;; even if the static type is wrong.
(define (jrec-field-at r i k)
(if (and (jrec? r) (fx< i (vector-length (jrec-vals r))))
(vector-ref (jrec-vals r) i)
(jolt-get r k)))
;; mutate a deftype's mutable field in place: the value vector is mutable, so
;; vector-set! updates the field. (set! field v) inside a method lowers to this;
;; returns v, as set! does.