potential problem in Vc::Memory

[Sandro Wenzel]

Hi,

I have observed a strange problem with Vc::Memory which I am using in a
little cartesian vector class like below ( branch Vc 0.8, gcc >= 4.7 ).
The problem was observed in the copy or assignment operator of this class.
To copy the internal data I tried the operator= of Vc::memory.
Apparently this results in non-optimal code in particular in a function
call and bad performance when I copy/assign a lot of Vectors.

My workaround of looping over the individual vectors in the Vc::memory
resolves this problem but is of course ugly.

Did someone see a similar issue?


class Vector3D
{

private:

  Vc::Memory<Vc::Vector<double>, 3> mem;

public:
// ...
  Vector3D & operator=( Vector3D const & rhs )
   {

      for( int i=0; i < 1 + 3/Vc::Vector<double>::Size; i++ )
      {
         Vc::Vector<double> v1 = rhs.mem.vector(i);
         this->mem.vector(i)=v1;
       }
      // the following line must not be used: this is a bug in Vc


      // this->mem = rhs.mem;


     return *this;
   }
}

-- 
Dr. Sandro Wenzel
PH / SFT
CERN
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