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a1ec8ff493
Naturally, fixed-width integer arithmetics can overflow. Chibi handles it pretty well in general, but one case was missing: it is negation of the minimal negative number that can be represented as a fixnum. That is, sexp_fx_neg() must not be applied to sexp_make_fixnum(SEXP_MIN_FIXNUM) because it overflows and returns an identical fixnum back. sexp_fx_neg() itself seems to be used right in the current code, but sexp_fx_abs()--which is defined in terms of sexp_fx_neg()--could be applied to the forbidden number when used to retrieve an unboxed value via the sexp_unbox_fixnum(sexp_fx_abs(x)) pattern. So I have added a separate macro that safely calculates unboxed absolute value of a fixnum, and replaced sexp_unbox_fixnum(sexp_fx_abs(x)) usages with it. Current implementation uses two-bit tag for fixnums, plus we need one bit for the sign, so fixnums have (machine word - 3) significant bits. Regression tests cover word sizes of 16, 32, 64, and 128 bits (for the sake of past- and future-proofness). sexp_bignum_expt() does not have a regression test because we need to check it with negative exponents like -2^29, so the base must be over at least 2^(2^29) for the differences to be visible. Fun fact: bignum representation of such number takes around 1/32 of the available user- space memory, which makes testing on anything except 32-bit systems unreasonable (4 TB of RAM anyone?) |
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| .. | ||
| basic | ||
| build | ||
| ffi | ||
| foreign | ||
| install | ||
| memory | ||
| base64-tests.scm | ||
| division-tests.scm | ||
| filesystem-tests.scm | ||
| flonum-tests.scm | ||
| generic-tests.scm | ||
| hash-tests.scm | ||
| io-tests.scm | ||
| iset-tests.scm | ||
| lib-tests.scm | ||
| loop-tests.scm | ||
| match-tests.scm | ||
| md5-tests.scm | ||
| memoize-tests.scm | ||
| mime-tests.scm | ||
| numeric-tests.scm | ||
| parse-tests.scm | ||
| path-tests.scm | ||
| prime-tests.scm | ||
| process-tests.scm | ||
| r5rs-tests.scm | ||
| r7rs-tests.scm | ||
| re-tests.txt | ||
| record-tests.scm | ||
| regexp-tests.scm | ||
| rsa-tests.scm | ||
| scribble-tests.scm | ||
| sha-tests.scm | ||
| show-tests.scm | ||
| sort-tests.scm | ||
| srfi-1-tests.scm | ||
| srfi-2-tests.scm | ||
| srfi-16-tests.scm | ||
| srfi-26-tests.scm | ||
| srfi-27-tests.scm | ||
| srfi-33-tests.scm | ||
| srfi-38-tests.scm | ||
| string-tests.scm | ||
| system-tests.scm | ||
| tar-tests.scm | ||
| term-ansi-tests.scm | ||
| thread-tests.scm | ||
| unicode-tests.scm | ||
| uri-tests.scm | ||
| weak-tests.scm | ||