[Bug target/81759] Improve data tracking for _pext_u64 and __builtin_ffsll

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81759

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2017-08-08
     Ever confirmed|0                           |1

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
extern __inline unsigned long long
__attribute__((__gnu_inline__, __always_inline__, __artificial__))
_pext_u64 (unsigned long long __X, unsigned long long __Y)
{
  return __builtin_ia32_pext_di (__X, __Y);
}

so it's transparent to the optimizers and thus a target or RTL optimization
issue issue.