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BigDecimal call-position arithmetic via :bigdec type (Phase 2)

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A direct (+ 1.5M 2.5M) emits a raw Chez + that rejects the bigdec record. Rather
than guard every arithmetic call site (measured 2-4x on unhinted fixnum loops),
let the analyzer dispatch where it can prove the type.

jolt.passes.numeric seeds a :bigdec kind from the M-literal and flows it through
let/loop/if like the existing :double/:long kinds; an arithmetic/comparison invoke
whose operands are all bigdec (integer literals allowed) gets :num-kind :bigdec.
The back end (bd-ops + emit-numeric) lowers those to the bigdec.ss engine
(jbd-add/-sub/-mul/-div, jbd-lt?/…, jbd-zero?/-pos?/-neg?, jbd-quot/-rem).

Zero cost on non-bigdec code: with no bigdec literals present the kind never
arises, so emission is byte-identical — the re-mint leaves prelude.ss unchanged,
only image.ss (the compiler) moves. Gaps (filed): a bigdec mixed with a flonum in
call position, and a bigdec the analyzer types :any, still hit the raw op and
throw; use value position or a literal-typed let.

Re-mint (numeric/backend are seed sources). 16 JVM-certified corpus rows.
This commit is contained in:
Yogthos 2026-06-25 19:49:17 -04:00
parent bd7b75fb5d
commit 6fcc9fa8e6
5 changed files with 240 additions and 180 deletions
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16
test/chez/corpus.edn
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@ -1325,6 +1325,22 @@
{:suite "numbers / bigdec arithmetic" :label "compare is scale-independent" :expected "0" :actual "(compare 1.0M 1.00M)"}
{:suite "numbers / bigdec arithmetic" :label "compare orders by value" :expected "-1" :actual "(compare 1.5M 2.5M)"}
{:suite "numbers / bigdec arithmetic" :label "sort uses bigdec compare" :expected "[1M 2M 3M]" :actual "(vec (sort [3M 1M 2M]))"}
{:suite "numbers / bigdec call position" :label "add" :expected "4.0M" :actual "(+ 1.5M 2.5M)"}
{:suite "numbers / bigdec call position" :label "multiply adds scales" :expected "\"3.0000\"" :actual "(str (* 1.50M 2.00M))"}
{:suite "numbers / bigdec call position" :label "subtract" :expected "3.5M" :actual "(- 5M 1.5M)"}
{:suite "numbers / bigdec call position" :label "negate" :expected "-1.5M" :actual "(- 1.5M)"}
{:suite "numbers / bigdec call position" :label "long contagion" :expected "3.5M" :actual "(+ 1.5M 2)"}
{:suite "numbers / bigdec call position" :label "exact divide" :expected "0.25M" :actual "(/ 1M 4M)"}
{:suite "numbers / bigdec call position" :label "less-than" :expected "true" :actual "(< 1.5M 2.5M)"}
{:suite "numbers / bigdec call position" :label "greater-than false" :expected "false" :actual "(> 1.5M 2.5M)"}
{:suite "numbers / bigdec call position" :label "zero?" :expected "true" :actual "(zero? 0M)"}
{:suite "numbers / bigdec call position" :label "pos?" :expected "true" :actual "(pos? 1.5M)"}
{:suite "numbers / bigdec call position" :label "neg? false" :expected "false" :actual "(neg? 1.5M)"}
{:suite "numbers / bigdec call position" :label "quot truncates to scale 0" :expected "3M" :actual "(quot 7M 2M)"}
{:suite "numbers / bigdec call position" :label "rem" :expected "1M" :actual "(rem 7M 2M)"}
{:suite "numbers / bigdec call position" :label "let-bound operands" :expected "4.0M" :actual "(let [a 1.5M b 2.5M] (+ a b))"}
{:suite "numbers / bigdec call position" :label "nested arithmetic propagates" :expected "6.0M" :actual "(+ (* 1.5M 2M) 3M)"}
{:suite "numbers / bigdec call position" :label "non-terminating divide throws" :expected ":nonterm" :actual "(try (/ 1M 3M) (catch ArithmeticException _ :nonterm))"}
{:suite "numbers / literal syntax" :label "ratio -> double" :expected "1/2" :actual "1/2"}
{:suite "numbers / literal syntax" :label "ratio 3/4" :expected "3/4" :actual "3/4"}
{:suite "numbers / literal syntax" :label "neg ratio" :expected "-1/2" :actual "-1/2"}