Reducers for Tagged operators give wrong answer

[crtrott]

Reproducer:

#include<Kokkos_Core.hpp>

struct TagMin {};
struct functor {
  Kokkos::View<double*> a;

  functor(Kokkos::View<double*> a_):a(a_) {}

  KOKKOS_INLINE_FUNCTION
  void operator() (const TagMin, const int& i, double& val) const {
    if(a(i) < val) val = a(i);
  }
};

int main(int argc, char* argv[]) {
  Kokkos::initialize(argc,argv);

  Kokkos::View<double*> a("A", 100);
  Kokkos::deep_copy(a,5.0);
  a(5) = 3.0;
  a(7) = 6.0;

  double result = 100;
  Kokkos::parallel_reduce(Kokkos::RangePolicy<TagMin>(0,100), functor(a), Kokkos::Experimental::Min<double>(result));

  printf("Result: %lf\n",result);

  Kokkos::finalize();
}

Prints 0 for building with openmp on SNB with GCC 5.3

[crtrott]

Works without the tag.

[crtrott]

Ok got a handle on this: the ValueInit specialisation layer needs to take void instead of the tag if a reducer is provided instead of the functor.

[crtrott]

I have added a unit test which catches this issues.