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Unchecked / *unchecked-math* arithmetic wraps to signed 64-bit

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clojure.core's unchecked-* (and +/-/*/inc/dec under *unchecked-math*) are long
ops that WRAP on overflow; jolt's checked arithmetic is arbitrary-precision and
its unchecked-* were plain non-wrapping (+ x y), diverging from the JVM. Now they
truncate to the low 64 bits as a signed long, matching Clojure:

  (unchecked-add 9223372036854775807 1)        => -9223372036854775808
  (unchecked-multiply 9223372036854775807 …)   => 1

- host/chez/seq.ss: jolt-wrap64 + binary jolt-unc{add,sub,mul,inc,dec,neg}2 and
  the variadic clojure.core/unchecked-* fns (def-var!'d in natives-seq.ss, where
  def-var! is bound). The overlay's plain unchecked-* defns are removed.
- backend lng-ops: unchecked-+/-/* emit the wrapping jolt-unc* helpers (the
  raising fx ops can't wrap on Chez's 61-bit fixnums); unchecked-inc/dec too.
- *unchecked-math* is honored: the analyzer reads it (jolt.host/unchecked-math?)
  and rewrites +/-/*/inc/dec to their unchecked-* for the rest of a file that
  (set!)s it, like the JVM.
- jolt->fx: a ^long value that overflows the 61-bit fixnum range passes through
  as an exact integer instead of erroring (a full-width long from wrapping math).

Also adds Long/bitCount / numberOfLeadingZeros / reverse and Math/getExponent /
scalb (test.check's splittable PRNG uses them).

This lets clojure.test.check load and run quick-check on jolt. re-mint (analyzer/
backend/overlay are seed sources). make test green (+6 corpus rows, 0 new
divergences, numeric gate updated), shakesmoke byte-identical.
This commit is contained in:
Yogthos 2026-06-27 15:41:35 -04:00
parent 86dd9650b6
commit a028cab04f
12 changed files with 588 additions and 517 deletions
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4
test/chez/numeric-test.ss
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@ -45,7 +45,9 @@
(ok "long inc lowers to fx1+" (has? (emitf "u" "(fn* ([^long n] (inc n)))") "(fx1+"))
(ok "double inc lowers to fl+ 1.0" (has? (emitf "u" "(fn* ([^double x] (inc x)))") "(fl+"))
(ok "long dec lowers to fx1-" (has? (emitf "u" "(fn* ([^long n] (dec n)))") "(fx1-"))
(ok "unchecked-add lowers to fx+" (has? (emitf "u" "(fn* ([^long n] (unchecked-add n 1)))") "(fx+"))
;; unchecked-* WRAP to signed 64 bits (Java long), so they emit the wrapping
;; jolt-unc* helpers, not the raising fx ops.
(ok "unchecked-add lowers to jolt-uncadd2" (has? (emitf "u" "(fn* ([^long n] (unchecked-add n 1)))") "(jolt-uncadd2"))
(ok "long quot lowers to fxquotient" (has? (emitf "u" "(fn* ([^long a ^long b] (quot a b)))") "(fxquotient"))
(ok "double == lowers to fl=?" (has? (emitf "u" "(fn* ([^double a ^double b] (== a b)))") "(fl=?"))