[Bug tree-optimization/97325] [11 Regression] wrong code with __builtin_ffs() at -O2

[jakub at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97325

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2020-10-07
     Ever confirmed|0                           |1
   Target Milestone|---                         |11.0
             Status|UNCONFIRMED                 |NEW
                 CC|                            |aldyh at gcc dot gnu.org,
                   |                            |amacleod at redhat dot com,
                   |                            |jakub at gcc dot gnu.org

--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Started with r11-3684 or r11-3685-gfcae5121154d1c3382b056bcc2c563cedac28e74
(the former commit doesn't build).

unsigned long long
foo (unsigned long long c)
{
  return c ? __builtin_ffs (-(unsigned short) c) : 0;
}

int
main ()
{
  if (foo (2) != 2)
    __builtin_abort ();
  return 0;
}