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Fix rb_fix_mul_fix on OpenBSD/mips64

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This fixes invalid and inconsistent results for the Fixnum*Fixnum case
where the result of the multiplication does not fit in 64-bit
on OpenBSD/mips64.  For example:

  $  for x in 1 23; do ruby31 -e 'p(54306000000000*86400)'; done
  14409380628474329524
  11410664325873689790

Cases where an argument was Bignum, as well as cases where the result
of the multiplication fits in 64-bit are fine:

  $ for x in 1 23; do ruby31 -e 'p(54306000*86400)'; done
  4692038400000
  4692038400000

  $ for x in 1 23; do ruby31 -e 'p(5430600000000000000000*86400)'; done
  469203840000000000000000000
  469203840000000000000000000

This was originally discovered by running the tests for the openssl gem
on OpenBSD/mips64 and having one test fail for a date far in the future.
I eventually traced this to the generic multiplication issue.

The underlying cause is using the int128_t type. This avoids use of the
int128_t type in this case, falling back to the slower conversion code,
which in the overflow case, turns the Fixnums into Bignums, then
performs the multiplication.
This commit is contained in:
Jeremy Evans 2022-07-03 09:42:44 -07:00
parent cd34f56d45
commit fe6245b430
1 changed files with 1 additions and 1 deletions
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2
internal/fixnum.h
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@ -18,7 +18,7 @@
#if HAVE_LONG_LONG && SIZEOF_LONG * 2 <= SIZEOF_LONG_LONG
# define DLONG LONG_LONG
# define DL2NUM(x) LL2NUM(x)
#elif defined(HAVE_INT128_T)
#elif defined(HAVE_INT128_T) && !(defined(__OpenBSD__) && defined(__mips64__))
# define DLONG int128_t
# define DL2NUM(x) (RB_FIXABLE(x) ? LONG2FIX(x) : rb_int128t2big(x))
VALUE rb_int128t2big(int128_t n); /* in bignum.c */