8b2be06b68
jank's ray tracer benchmark (examples/ray-tracer) drops from 165.6s to
15.8s per render (10.5x) — from 118x JVM Clojure to 11x. The changes
mirror the optimizations in jank's June 2026 post, adapted to the
janet backend (jolt-4vr, jolt-h79):
- (:kw m) emits an inline lookup instead of variadic jolt-call ->
core-get's predicate chain. The guard is (get m :jolt/type): janet
compiles get to an opcode (~17ns) where a struct? cfunction call
costs ~85ns/lookup. :jolt/type is reserved (the reader rejects it in
map literals) and every table rep that must not be raw-indexed
carries it — phm tables now tagged too — so tagged values route to
core-get and everything else gets janet get, which matches core-get
for keyword keys on structs/records/nil/arrays. 929ns -> 90ns.
- {:k v ...} literals with scalar const keys emit let-bound values, an
`and` truthiness test (pure branch opcodes), and a native (struct ...)
call instead of variadic build-map-literal + runtime kv re-scan. nil
or false values fall back to build-map-literal, which keeps Clojure's
nil-entry semantics via the phm rep. 890ns -> 246ns.
- native-op additions: min/max (janet's are variadic with the same
numeric semantics), nil?/some? lowered to janet's fastfun = / not=
against nil, and not.
- clojure.math (Clojure 1.11) installed as a namespace whose vars hold
janet's math natives directly, so calls direct-link. Math/sqrt-style
interop stays in the frozen interpret-only punt set (~5us/call); this
is the compiled route (~30ns).
- reduce over pvec/tuple/array iterates indexed in place — it was
copying the whole pvec into a fresh array on every reduce call — and
stops at `reduced` instead of scanning the tail.
- interpreter coll-lookup gains the sorted-coll arm: (:k (sorted-map ..))
was nil in interpret mode (compiled mode had it right).
map-fastpath-spec pins keyword-invoke/map-literal semantics (16+15
rows incl. nil-value maps, records, sorted, vectors-of-internals) and
clojure.math (10 rows). Two pre-existing bugs found and filed while
writing it: map literals evaluate entries in reader-hash order
(jolt-p3c), and an attempted local-callee call inline that breaks
overlay lazy self-recursion is parked with a repro (jolt-507).
Gate green, conformance 335/335 x3, suite 4718 steady, core bench even
with main back-to-back.
57 lines
3.3 KiB
Text
57 lines
3.3 KiB
Text
# Specification: keyword-invoke and map-literal semantics that the compiled
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# fast paths (jolt-4vr: inlined keyword lookup, inlined struct construction)
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# must preserve. Written BEFORE the optimization; every row passes on the
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# generic jolt-call/build-map-literal paths and must keep passing on the
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# inlined ones.
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(use ../support/harness)
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(defspec "maps / keyword invoke"
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["hit" "1" "(:a {:a 1 :b 2})"]
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["miss" "nil" "(:z {:a 1})"]
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["miss with default" ":d" "(:z {:a 1} :d)"]
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["hit with default" "1" "(:a {:a 1} :d)"]
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["on nil" "nil" "(:a nil)"]
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["on nil with default" ":d" "(:a nil :d)"]
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["nil value is present" "nil" "(:a {:a nil} :d)"]
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["false value is present" "false" "(:a {:a false} :d)"]
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["on a vector" "nil" "(:a [1 2 3])"]
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["on a number" "nil" "(:a 42)"]
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["on a sorted map" "2" "(:b (sorted-map :a 1 :b 2))"]
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["on assoc result" "3" "(:c (assoc {:a 1} :c 3))"]
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["on a record field" "5" "(do (defrecord KFP [x]) (:x (->KFP 5)))"]
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["qualified keyword" "1" "(:n/a {:n/a 1})"]
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["nested in expr" "6" "(+ (:a {:a 1}) (:b {:b 2}) (:c {:c 3}))"]
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["evaluates map expr once" "[2 1]"
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"(do (def cnt (atom 0)) (let [v (:a (do (swap! cnt inc) {:a 2}))] [v @cnt]))"])
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(defspec "maps / literal construction"
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["basic" "{:a 1, :b 2}" "{:a 1 :b 2}"]
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["empty" "{}" "{}"]
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["computed values" "{:a 3}" "{:a (+ 1 2)}"]
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["nil value kept" "true" "(contains? {:a nil} :a)"]
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["nil value lookup" "nil" "(get {:a nil} :a :d)"]
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["string key" "1" "(get {\"k\" 1} \"k\")"]
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["number key" ":one" "(get {1 :one} 1)"]
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["collection key" ":v" "(get {[1 2] :v} [1 2])"]
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["collection value-equal key" ":v" "(get {[1 2] :v} (vector 1 2))"]
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["computed key" "1" "(get {(keyword \"a\") 1} :a)"]
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# NOTE: entry ORDER is reader-hash order today, not source order (Clojure
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# evaluates array-map literals left-to-right) — pinned loosely; see jolt-p3c
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["values evaluate exactly once each" "[1 2 3]"
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"(do (def log (atom [])) {:a (swap! log conj 1) :b (swap! log conj 2) :c (swap! log conj 3)} (vec (sort (deref log))))"]
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["count" "3" "(count {:a 1 :b 2 :c 3})"]
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["equality with phm" "true" "(= {:a 1 :b 2} (assoc {:a 1} :b 2))"]
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["keys work after assoc" "2" "(:b (assoc {:a 1 :b 2} :c 3))"]
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["literal in fn body" "12" "(do (defn mfp-mk [x] {:v (* x 2)}) (:v (mfp-mk 6)))"])
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(defspec "clojure.math (jolt-h79)"
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["sqrt" "true" "(< 1.4142 (clojure.math/sqrt 2) 1.4143)"]
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["pow" "1024" "(long (clojure.math/pow 2 10))"]
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["tan of 0" "0" "(long (clojure.math/tan 0))"]
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["round" "3" "(clojure.math/round 2.6)"]
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["floor" "2" "(clojure.math/floor 2.9)"]
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["signum" "-1" "(clojure.math/signum -7.2)"]
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["to-radians" "true" "(< 3.14 (clojure.math/to-radians 180) 3.15)"]
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["PI" "true" "(< 3.14 clojure.math/PI 3.15)"]
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["require + alias" "5" "(do (require '[clojure.math :as m]) (long (m/hypot 3 4)))"]
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["as a value" "[1 2]" "(mapv (comp long clojure.math/sqrt) [1 4])"])
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