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cs: use black hole for unsafe-undefined representation

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This commit is contained in:
Matthew Flatt 2020-01-30 20:18:12 -07:00
parent ad9dc342f8
commit 8da6e9bd6b
1 changed files with 4 additions and 2 deletions
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6
racket/src/cs/rumble/unsafe.ss
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@ -172,8 +172,10 @@
(define (unsafe-flimag-part c) (define (unsafe-flimag-part c)
(#3%imag-part c)) (#3%imag-part c))
(define unsafe-undefined (let ([p (make-record-type "undefined" '())]) ;; The black hole object is an immediate in Chez Scheme,
((record-constructor p)))) ;; so a use is compact and the optimize can recognize
;; comparsions to itself:
(define unsafe-undefined '#0=#0#)
(define (check-not-unsafe-undefined v sym) (define (check-not-unsafe-undefined v sym)
(when (eq? v unsafe-undefined) (when (eq? v unsafe-undefined)