Header File: Kokkos_SIMD.hpp


Kokkos::Experimental::simd_mask is an abstraction over platform-specific vector masks and calls platform-specific vector intrinsics. It is based on the simd_mask type proposed for ISO C++ in this document


namespace Experimental {
template <class T, class Abi>
class simd_mask;

Template Parameters#

The first template parameter T should be a C++ fundamental type for which the current platform supports vector intrinsics. Kokkos supports the following types for T:

  • double

  • std::int32_t

  • std::int64_t

  • std::uint32_t

  • std::uint64_t

The second template parameter Abi is one of the pre-defined ABI types in the namespace Kokkos::Experimental::simd_abi. This type determines the size of the vector and what architecture-specific intrinsics will be used. The following types are always available in that namespace:

  • scalar: a fallback ABI which always has vector size of 1 and uses no special intrinsics.

  • native: the “best” ABI for the architecture for which Kokkos was compiled.


  • value_type: Equal to bool

  • reference: This type should be convertible to bool and bool should be assignable to reference. It may be a plain reference or it may be a special class that calls vector intrinsics to extract or fill in one mask bit.

  • simd_type: Equal to simd<T, Abi>

  • abi_type: Equal to Abi


  • static constexpr std::size_t size(): simd_mask<T, Abi>::size() is a compile-time constant of the width of the vector, i.e. the number of values of type T in the vector.


  • simd_mask(): Default Constructor. The vector values are not initialized by this constructor.

  • simd_mask(bool): Single-value constructor. All values in the mask will be set to the value of the argument.

  • template <class G> simd_mask(G&& gen): Generator constructor. The generator gen should be a callable type (e.g. functor) that can accept std::integral_constant<std::size_t, i>() as an argument and return something convertible to bool. Vector mask value i will be initialized to the value of gen(std::integral_constant<std::size_t, i>()).

Value Access Methods#

  • reference operator[](std::size_t): returns a reference to mask value i that can be modified.

  • bool operator[](std::size_t) const: returns the mask value i.

Boolean Operators#

  • simd_mask simd_mask::operator!() const

  • simd_mask operator&&(const simd_mask& lhs, const simd_mask& rhs)

  • simd_mask operator||(const simd_mask& lhs, const simd_mask& rhs)

Comparison Operators#

  • simd_mask operator==(const simd_mask& lhs, const simd_mask& rhs)

  • simd_mask operator!=(const simd_mask& lhs, const simd_mask& rhs)


  • bool all_of(const simd_mask&): returns true iff all of the vector values in the mask are true

  • bool any_of(const simd_mask&): returns true iff any of the vector values in the mask are true

  • bool none_of(const simd_mask&): returns true iff none of the vector values in the mask are true

Global Typedefs#

  • template <class T> Kokkos::Experimental::native_simd_mask: Alias for Kokkos::Experimental::simd_mask<T, Kokkos::Experimental::simd_abi::native<T>>.


#include <Kokkos_SIMD.hpp>
#include <cstdio>

int main(int argc, char* argv[]) {
  using mask_type = Kokkos::Experimental::native_simd_mask<double>;
  mask_type a([] (std::size_t i) { return i == 0; });
  mask_type b([] (std::size_t i) { return i == 1; });
  mask_type c([] (std::size_t i) { return i == 0 || i == 1; });
  if (all_of(c == (a || b))) {
    printf("Kokkos simd_mask works as expected!");