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Fixed potential danger with fixnum optimizations.

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(cherry picked from commit c0a6137c67)
This commit is contained in:
Vincent St-Amour 2010-11-04 11:21:40 -04:00 committed by Eli Barzilay
parent 8340ad7111
commit e36787bdeb
2 changed files with 17 additions and 3 deletions
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17
collects/typed-scheme/typecheck/tc-expr-unit.rkt
View File

@ -21,6 +21,17 @@
(import tc-if^ tc-lambda^ tc-app^ tc-let^ check-subforms^)
(export tc-expr^)
;; Is the number a fixnum on all the platforms Racket supports?
;; This check is done at compile time to typecheck literals.
;; Since a zo file compiled on a 64-bit system can be used on 32-bit
;; systems, we can't use the host fixnum? predicate, or large 64-bit
;; fixnums will typecheck as fixnums but not be actual fixnums on the
;; target system. In combination with fixnum typed optimizations, bad
;; things could happen.
(define (portable-fixnum? n)
(and (exact-integer? n)
(< n (expt 2 31))))
;; return the type of a literal value
;; scheme-value -> type
(define (tc-literal v-stx [expected #f])
@ -34,9 +45,9 @@
[i:boolean (-val (syntax-e #'i))]
[i:identifier (-val (syntax-e #'i))]
[0 -Zero]
[(~var i (3d (conjoin number? fixnum? positive?))) -PositiveFixnum]
[(~var i (3d (conjoin number? fixnum? negative?))) -NegativeFixnum]
[(~var i (3d (conjoin number? fixnum?))) -Fixnum]
[(~var i (3d (conjoin number? portable-fixnum? positive?))) -PositiveFixnum]
[(~var i (3d (conjoin number? portable-fixnum? negative?))) -NegativeFixnum]
[(~var i (3d (conjoin number? portable-fixnum?))) -Fixnum]
[(~var i (3d exact-positive-integer?)) -ExactPositiveInteger]
[(~var i (3d exact-nonnegative-integer?)) -ExactNonnegativeInteger]
[(~var i (3d exact-integer?)) -Integer]

3
collects/typed-scheme/types/abbrev.rkt
View File

@ -174,6 +174,9 @@
(define -ExactPositiveInteger
(make-Base 'Exact-Positive-Integer #'exact-positive-integer?))
;; We can safely use the fixnum? prediate here, unlike in tc-expr-unit.
;; The fixnum? here will be part of the generated contracts, which run
;; on the target system, so we're safe.
(define -PositiveFixnum
(make-Base 'Positive-Fixnum #'(and/c number? fixnum? positive?)))
(define -NegativeFixnum