On 2018-09-05 16:00:18 +0200, Torbjorn Granlund wrote:
> paul zimmermann <paul.zimmerm...@inria.fr> writes:
>
> void
> mpz_add_ui (mpz_t r, const mpz_t a, unsigned long b)
> {
> b = b % 0xffffffff;
> if (a->_mp_size >= 0)
> r->_mp_size = mpz_abs_add_ui (r, a, b);
> else
> r->_mp_size = -mpz_abs_sub_ui (r, a, b);
> }
>
> An interestng approach, patch the library to miscompute things in a way
> that the testsuite does not detect!
I intended to do that in MPFR to check that each MPFR_LIMB() macro
was really needed or something was missing in the test suite.
> Perhaps this can be automated and given a new, trendy name now that
> fuzzing has been on everybody's mind for so long? :-)
An interesting place is to check inequalities on integers, by adding
or subtracting 1 on one side. And some magic constants. But it could
also mean that there are several valid possibilities, and the language
would need to be extended to handle that.
--
Vincent Lefèvre <vinc...@vinc17.net> - Web: <https://www.vinc17.net/>
100% accessible validated (X)HTML - Blog: <https://www.vinc17.net/blog/>
Work: CR INRIA - computer arithmetic / AriC project (LIP, ENS-Lyon)
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