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Numbers-style category dispatch for binary numeric ops

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Arithmetic and comparisons lowered to raw Chez ops, so an operand outside
Chez's tower (BigDecimal) crashed with a raw condition, and Chez contagion
leaked: (* 1.0 0) gave exact 0 where the JVM gives 0.0, (* ##Inf 0) gave 0
instead of ##NaN, (/ 1 0) raised an untyped error.

One seam now (host/chez/seq.ss): call position emits jolt-n* macros with the
both-Chez-numbers fast path open-coded; value position folds through the same
binary ops. Anything outside the tower falls to per-op slow hooks that
java/bigdec.ss extends, so bigdec arithmetic works in every position (the old
static-only :bigdec typing limitation is gone). JVM rules patched into the
fast path: a double operand wins, an exact zero divisor throws
ArithmeticException while a double zero divisor yields Inf/NaN, quot/rem/mod
cover ratios and doubles, min/max return the original operand with NaN
winning, a nil operand is NPE and a non-number CCE, zero-arg -// throw
ArityException at runtime instead of failing expansion.

Also: with-precision now binds *math-context* and bigdec results round with
real RoundingMode semantics (UNNECESSARY throws; division rounds to precision
instead of throwing); rationalize goes through the shortest decimal print
like BigDecimal.valueOf (the identity stub is gone); ratios coerce to bigdec
like Numbers.toBigDecimal; min/max int-literal operands no longer coerce to
flonum in the numeric pass.

Perf neutral: fib and seq benches unchanged (the fast path is two type checks
the optimizer folds); hinted fl/fx paths untouched. 19 JVM-certified corpus
rows; cts baseline 5614->5730 pass, 192->88 errors, 84->79 baselined
namespaces.
This commit is contained in:
Yogthos 2026-07-02 06:41:45 -04:00
parent 38abc1be84
commit e66a91750e
13 changed files with 1106 additions and 729 deletions
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212
host/chez/java/bigdec.ss
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@ -7,21 +7,19 @@
;;
;; Arithmetic follows java.math.BigDecimal's scale rules: add/sub align to the
;; larger scale; multiply adds scales; divide gives the exact quotient at minimal
;; scale or throws ArithmeticException on a non-terminating expansion. Clojure
;; contagion: a bigdec mixed with an integer stays a bigdec; a flonum operand wins
;; (the result is a double). jbd-add/-sub/-mul/-div, jbd-min/-max, the jbd-lt?/…
;; /zero? helpers, and jbd-quot/-rem are the shared engine. Two paths reach it, both
;; leaving the inlined native hot path untouched:
;; - value position ((reduce + bigs)/(apply * bigs)): the jolt-add/-sub/-mul/-div
;; and compare shims dispatch here when a bigdec operand is present.
;; - call position ((+ 1.5M 2.5M), (< a b), (zero? b)): jolt.passes.numeric tags
;; the invoke :num-kind :bigdec when every operand is statically a bigdec (M
;; literal or a let-bound copy, integer literals allowed), and the back end
;; lowers it to the jbd op. Non-bigdec code is unaffected.
;; Gaps (a runtime bigdec the analyzer can't see statically): a bigdec mixed with a
;; flonum in call position ((+ 1.5M 2.0)) and arithmetic over a bigdec the analyzer
;; types as :any ((+ (bigdec x) 1)) fall through to the raw op and throw; use value
;; position or a literal-typed let.
;; scale or throws ArithmeticException on a non-terminating expansion (a bound
;; *math-context* rounds instead). Clojure contagion: a bigdec mixed with an
;; integer or ratio stays a bigdec; a flonum operand wins (the result is a
;; double). jbd-add/-sub/-mul/-div, jbd-min/-max, the jbd-lt?/…/zero? helpers,
;; and jbd-quot/-rem are the shared engine. Two paths reach it, both leaving the
;; inlined fast path untouched:
;; - the seq.ss binary dispatch: every generic op (any position — (+ (bigdec x)
;; 1), (reduce + bigs), (quot 10.0 3M)) whose operand is outside Chez's tower
;; falls to the jolt-*-slow hooks extended below.
;; - static call position ((+ 1.5M 2.5M), (< a b), (zero? b)): jolt.passes.numeric
;; tags the invoke :num-kind :bigdec when every operand is statically a bigdec
;; (M literal or a let-bound copy, integer literals allowed), and the back end
;; lowers it directly to the jbd op.
(define-record-type jbigdec (fields unscaled scale) (nongenerative chez-jbigdec-v1))
@ -79,11 +77,13 @@
(define (jbigdec->flonum b)
(exact->inexact (/ (jbigdec-unscaled b) (expt 10 (jbigdec-scale b)))))
;; coerce an exact integer to a scale-0 bigdec; pass a bigdec through. Used on the
;; non-flonum mixed path (bigdec + long -> bigdec).
;; coerce an exact operand to a bigdec; pass a bigdec through. Used on the
;; non-flonum mixed path (bigdec + long -> bigdec). A Ratio converts like
;; Numbers.toBigDecimal — exact decimal expansion or throw on non-terminating.
(define (jbd-coerce x)
(cond ((jbigdec? x) x)
((and (number? x) (exact? x) (integer? x)) (make-jbigdec x 0))
((and (number? x) (exact? x) (rational? x)) (jbd-rational->bigdec x))
(else (error #f "bigdec arithmetic: cannot coerce operand" x))))
;; --- core arithmetic on the {unscaled, scale} pair --------------------------
@ -117,12 +117,39 @@
"java.lang.ArithmeticException"
"Non-terminating decimal expansion; no exact representable decimal result.")))))))
;; floor(log10 |r|) for a nonzero exact rational.
(define (jbd-exp10 r)
(let ((n (abs (numerator r))) (d (denominator r)))
(if (>= n d)
(- (jbd-digits (quotient n d)) 1)
(let loop ((x (* n 10)) (e -1))
(if (>= x d) e (loop (* x 10) (- e 1)))))))
;; round an exact rational to `prec` significant digits (the MathContext divide).
(define (jbd-rational-prec r prec mode)
(if (= r 0)
(make-jbigdec 0 0)
(let* ((neg (< r 0)) (ar (abs r))
(s (- prec 1 (jbd-exp10 ar)))
(scaled (* ar (expt 10 s)))
(q (floor scaled)) (frac (- scaled q))
(q2 (if (jbd-round-inc? q frac 1 mode neg) (+ q 1) q))
(res (make-jbigdec (if neg (- q2) q2) s)))
;; a carry can add a digit (9.99 -> 10.0); re-normalizing drops an exact
;; trailing zero, never re-rounds.
(if (> (jbd-digits q2) prec) (jbd-round-prec res prec mode) res))))
(define (jbd2-div a b)
(when (= 0 (jbigdec-unscaled b))
(jolt-throw (jolt-host-throwable "java.lang.ArithmeticException" "Divide by zero")))
;; a/b = (ua * 10^sb) / (ub * 10^sa) as an exact rational.
(jbd-rational->bigdec (/ (* (jbigdec-unscaled a) (expt 10 (jbigdec-scale b)))
(* (jbigdec-unscaled b) (expt 10 (jbigdec-scale a))))))
;; a/b = (ua * 10^sb) / (ub * 10^sa) as an exact rational. Unlimited context:
;; exact result at minimal scale or throw on a non-terminating expansion. A
;; bound *math-context* instead rounds to its precision.
(let ((r (/ (* (jbigdec-unscaled a) (expt 10 (jbigdec-scale b)))
(* (jbigdec-unscaled b) (expt 10 (jbigdec-scale a)))))
(mc (jbd-math-context)))
(if mc
(jbd-rational-prec r (jbd-mc-precision mc) (jbd-mc-mode mc))
(jbd-rational->bigdec r))))
;; integer-division semantics (quot/rem): truncate toward zero, scale 0.
(define (jbd-int-quot a b)
@ -139,13 +166,65 @@
(define (jbd-compare2 a b)
(let-values (((ua ub s) (jbd-align a b))) (cond ((< ua ub) -1) ((> ua ub) 1) (else 0))))
;; --- *math-context* (with-precision) -----------------------------------------
;; with-precision binds clojure.core/*math-context* to {:precision N :rounding
;; MODE}; every exact bigdec result rounds through it (java.math.MathContext).
(define jbd-kw-precision (keyword #f "precision"))
(define jbd-kw-rounding (keyword #f "rounding"))
(define (jbd-math-context)
(let ((mc (var-deref "clojure.core" "*math-context*")))
(if (jolt-nil? mc) #f mc)))
(define (jbd-mc-precision mc) (jolt-get mc jbd-kw-precision))
(define (jbd-mc-mode mc)
(let ((r (jolt-get mc jbd-kw-rounding)))
(cond ((symbol-t? r) (symbol-t-name r))
((string? r) r)
(else "HALF_UP"))))
;; should |value| = q + r/div (0 <= r < div) round up in magnitude? neg is the
;; value's sign; r/div may be exact rationals (the division path).
(define (jbd-round-inc? q r div mode neg)
(cond ((= r 0) #f)
((string=? mode "UP") #t)
((string=? mode "DOWN") #f)
((string=? mode "CEILING") (not neg))
((string=? mode "FLOOR") neg)
((string=? mode "HALF_DOWN") (> (* 2 r) div))
((string=? mode "HALF_EVEN")
(let ((c (- (* 2 r) div)))
(cond ((> c 0) #t) ((< c 0) #f) (else (odd? q)))))
((string=? mode "UNNECESSARY")
(jolt-throw (jolt-host-throwable "java.lang.ArithmeticException" "Rounding necessary")))
(else (>= (* 2 r) div)))) ; HALF_UP, the MathContext default
(define (jbd-digits n) (string-length (number->string (abs n))))
;; round a bigdec to `prec` significant digits with `mode` (a RoundingMode name).
(define (jbd-round-prec bd prec mode)
(let ((u (jbigdec-unscaled bd)) (s (jbigdec-scale bd)))
(if (= u 0)
bd
(let ((digs (jbd-digits u)))
(if (<= digs prec)
bd
(let* ((drop (- digs prec)) (div (expt 10 drop))
(neg (< u 0)) (au (abs u))
(q (quotient au div)) (r (remainder au div))
(q2 (if (jbd-round-inc? q r div mode neg) (+ q 1) q))
(res (make-jbigdec (if neg (- q2) q2) (- s drop))))
;; a carry can add a digit back (99 -> 100 at precision 2)
(if (> (jbd-digits q2) prec) (jbd-round-prec res prec mode) res)))))))
(define (jbd-mc-round x)
(let ((mc (and (jbigdec? x) (jbd-math-context))))
(if mc (jbd-round-prec x (jbd-mc-precision mc) (jbd-mc-mode mc)) x)))
;; A binary op over operands that may mix bigdec / integer / flonum. flonum-op is
;; the native fallback for the double-contagion path; bd-op is the exact bigdec op.
;; the native fallback for the double-contagion path; bd-op is the exact bigdec op
;; (its result rounds through a bound *math-context*).
(define (jbd-binop flonum-op bd-op a b)
(if (or (flonum? a) (flonum? b))
(flonum-op (if (jbigdec? a) (jbigdec->flonum a) a)
(if (jbigdec? b) (jbigdec->flonum b) b))
(bd-op (jbd-coerce a) (jbd-coerce b))))
(jbd-mc-round (bd-op (jbd-coerce a) (jbd-coerce b)))))
;; --- variadic engine ops (Phase-2 emit targets + value-position folds) -------
(define (jbd-fold flonum-op bd-op init xs)
@ -203,23 +282,78 @@
;; --- wire into the value model ----------------------------------------------
(def-var! "clojure.core" "bigdec" jolt-bigdec)
;; Value-position arithmetic: (reduce + bigs) / (apply * bigs) pass +/*/- // AS A
;; VALUE, which lowers to these shims (NOT the inlined hot-path native op). Extend
;; them to dispatch to the bigdec engine when a bigdec operand is present; ordinary
;; numeric folds hit the captured native path unchanged.
(define jbd-prev-add jolt-add)
(define jbd-prev-sub jolt-sub)
(define jbd-prev-mul jolt-mul)
(define jbd-prev-div jolt-div)
(define jbd-prev-min jolt-min)
(define jbd-prev-max jolt-max)
(define (jbd-any? xs) (and (pair? xs) (or (jbigdec? (car xs)) (jbd-any? (cdr xs)))))
(set! jolt-add (lambda xs (if (jbd-any? xs) (apply jbd-add xs) (apply jbd-prev-add xs))))
(set! jolt-sub (lambda xs (if (jbd-any? xs) (apply jbd-sub xs) (apply jbd-prev-sub xs))))
(set! jolt-mul (lambda xs (if (jbd-any? xs) (apply jbd-mul xs) (apply jbd-prev-mul xs))))
(set! jolt-div (lambda xs (if (jbd-any? xs) (apply jbd-div xs) (apply jbd-prev-div xs))))
(set! jolt-min (lambda xs (if (jbd-any? xs) (apply jbd-min xs) (apply jbd-prev-min xs))))
(set! jolt-max (lambda xs (if (jbd-any? xs) (apply jbd-max xs) (apply jbd-prev-max xs))))
;; The seq.ss binary numeric dispatch (jolt-add2/… and the jolt-n* macros) routes
;; any op whose operand is outside Chez's tower to the *-slow hooks; extend each
;; with a bigdec arm. Every arithmetic position (call, value, higher-order)
;; funnels through these, so contagion and *math-context* rounding apply
;; uniformly. min/max need no arm: the generic jolt-min2 compares through
;; jolt-num-cmp-slow and returns the original operand.
(set! jolt-num-slow?
(let ((prev jolt-num-slow?)) (lambda (x) (or (jbigdec? x) (prev x)))))
(define (jbd-extend-hook prev bd-op)
(lambda (a b)
(if (or (jbigdec? a) (jbigdec? b)) (bd-op a b) (prev a b))))
(set! jolt-add-slow (jbd-extend-hook jolt-add-slow (lambda (a b) (jbd-binop + jbd2+ a b))))
(set! jolt-sub-slow (jbd-extend-hook jolt-sub-slow (lambda (a b) (jbd-binop - jbd2- a b))))
(set! jolt-mul-slow (jbd-extend-hook jolt-mul-slow (lambda (a b) (jbd-binop * jbd2* a b))))
(set! jolt-div-slow (jbd-extend-hook jolt-div-slow (lambda (a b) (jbd-binop / jbd2-div a b))))
(set! jolt-num-cmp-slow
(let ((prev jolt-num-cmp-slow))
(lambda (a b)
(if (and (or (jbigdec? a) (jbigdec? b)) (jbd-numberish? a) (jbd-numberish? b))
(jbd-value-compare a b)
(prev a b)))))
;; quot/rem/mod: a double operand demotes to the double path; exact operands use
;; the integer-division bigdec ops (mod = rem, floor-adjusted to the divisor's sign).
(define (jbd->num x) (if (jbigdec? x) (jbigdec->flonum x) x))
(set! jolt-quot-slow
(jbd-extend-hook jolt-quot-slow
(lambda (a b) (if (or (flonum? a) (flonum? b))
(jolt-quot (jbd->num a) (jbd->num b))
(jbd-int-quot (jbd-coerce a) (jbd-coerce b))))))
(set! jolt-rem-slow
(jbd-extend-hook jolt-rem-slow
(lambda (a b) (if (or (flonum? a) (flonum? b))
(jolt-rem (jbd->num a) (jbd->num b))
(jbd-int-rem (jbd-coerce a) (jbd-coerce b))))))
(set! jolt-mod-slow
(jbd-extend-hook jolt-mod-slow
(lambda (a b)
(if (or (flonum? a) (flonum? b))
(jolt-mod (jbd->num a) (jbd->num b))
(let* ((bb (jbd-coerce b))
(m (jbd-int-rem (jbd-coerce a) bb)))
(if (or (jbd-zero? m) (eq? (jbd-neg? m) (jbd-neg? bb))) m (jbd2+ m bb)))))))
;; unary shims: inc/dec and the sign predicates take a bigdec arm. set! updates
;; call-position references; the re-def-var! updates the var cell AND claims the
;; wrapped proc's class name before the prelude's inc'/dec' aliases are defined
;; ((type inc) stays clojure.core$inc — first def wins in the class registry).
(define jbd-one (make-jbigdec 1 0))
(set! jolt-inc (let ((prev jolt-inc)) (lambda (x) (if (jbigdec? x) (jbd-mc-round (jbd2+ x jbd-one)) (prev x)))))
(set! jolt-dec (let ((prev jolt-dec)) (lambda (x) (if (jbigdec? x) (jbd-mc-round (jbd2- x jbd-one)) (prev x)))))
(set! jolt-zero? (let ((prev jolt-zero?)) (lambda (x) (if (jbigdec? x) (jbd-zero? x) (prev x)))))
(set! jolt-pos? (let ((prev jolt-pos?)) (lambda (x) (if (jbigdec? x) (jbd-pos? x) (prev x)))))
(set! jolt-neg? (let ((prev jolt-neg?)) (lambda (x) (if (jbigdec? x) (jbd-neg? x) (prev x)))))
(def-var! "clojure.core" "inc" jolt-inc)
(def-var! "clojure.core" "dec" jolt-dec)
(def-var! "clojure.core" "zero?" jolt-zero?)
(def-var! "clojure.core" "pos?" jolt-pos?)
(def-var! "clojure.core" "neg?" jolt-neg?)
;; rationalize: reference Clojure goes through BigDecimal.valueOf(double) — the
;; SHORTEST decimal print of the double, not its exact binary value — so
;; (rationalize 1.1) is 11/10. A bigdec is exact already; other exacts pass through.
(define (jolt-rationalize x)
(cond ((jbigdec? x) (/ (jbigdec-unscaled x) (expt 10 (jbigdec-scale x))))
((flonum? x)
(if (or (nan? x) (infinite? x))
(jolt-throw (jolt-host-throwable "java.lang.NumberFormatException"
(string-append "Invalid input: " (number->string x))))
(let ((bd (jolt-bigdec-from-string (jolt-num->string x))))
(/ (jbigdec-unscaled bd) (expt 10 (jbigdec-scale bd))))))
((number? x) x)
(else (jolt-num-cast-throw x))))
(def-var! "clojure.core" "rationalize" jolt-rationalize)
;; compare: add a bigdec arm (enables compare / sort / sorted collections). A
;; bigdec vs a plain number compares by value; bigdec vs bigdec is scale-independent.