[Bug libstdc++/81706] std::sin vectorization bug

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81706

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |missed-optimization
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2017-08-04
                 CC|                            |jakub at gcc dot gnu.org,
                   |                            |rguenth at gcc dot gnu.org
          Component|c++                         |libstdc++
            Version|unknown                     |7.1.1
     Ever confirmed|0                           |1

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
The C library sin is vectorized by being appropriately annotated with OpenMP
SIMD attributes.  This isn't the case for the libstdc++ variant which ends up
calling
__builtin_sinf:

  using ::sin;

  inline float
  sin(float __x)
  { return __builtin_sinf(__x); }

why the using ::sin and then still dispatching to the builtin?