`Experimental::simd`#

Header File: Kokkos_SIMD.hpp

Usage:

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

Interface#

namespace Experimental {
template <class T, class Abi>
class simd;
}

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.

Typedefs#

value_type: Equal to T
reference: This type should be convertible to value_type and value_type should be assignable to reference. It may be a plain reference or it may be an implementation-defined type that calls vector intrinsics to extract or fill in one vector lane.
mask_type: Equal to simd_mask<T, Abi>
abi_type: Equal to Abi

Width#

static constexpr std::size_t size(): simd<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.

Constructors#

simd(): Default Constructor. The vector values are not initialized by this constructor.
template <class U> simd(U&&): Single-value constructor. The argument will be converted to value_type and all the vector values will be set equal to that value.
template <class G> simd(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 value_type. Vector lane i will be initialized to the value of gen(std::integral_constant<std::size_t, i>()).
template <class U, class Flags> simd(const U* mem, Flags): loads the vector values from memory based on the guidance represented by the Flags. The only supported type for Flags is Kokkos::Experimental::element_aligned_tag.

Load/Store Methods#

template <class U, class Flags> void copy_from(const U* mem, Flags flags): Loads the full vector of contiguous values starting at the address mem. The only valid type for Flags is Kokkos::Experimental::element_aligned_tag.
template <class U, class Flags> void copy_to(U* mem, Flags flags): Stores the full vector of contiguous values starting at the address mem. The only valid type for Flags is Kokkos::Experimental::element_aligned_tag.

Value Access Methods#

reference operator[](std::size_t): returns a reference to vector value i that can be modified.
value_type operator[](std::size_t) const: returns the vector value i.

Arithmetic Operators#

simd simd::operator-() const
simd operator+(const simd& lhs, const simd& rhs)
simd operator-(const simd& lhs, const simd& rhs)
simd operator*(const simd& lhs, const simd& rhs)
simd operator/(const simd& lhs, const simd& rhs)
simd operator>>(const simd& lhs, const simd& rhs)
simd operator<<(const simd& lhs, const simd& rhs)
simd operator+=(simd& lhs, const simd& rhs)
simd operator-=(simd& lhs, const simd& rhs)
simd operator*=(simd& lhs, const simd& rhs)
simd operator/=(simd& lhs, const simd& rhs)

Comparison Operators#

mask_type operator==(const simd& lhs, const simd& rhs)
mask_type operator!=(const simd& lhs, const simd& rhs)
mask_type operator>=(const simd& lhs, const simd& rhs)
mask_type operator<=(const simd& lhs, const simd& rhs)
mask_type operator>(const simd& lhs, const simd& rhs)
mask_type operator<(const simd& lhs, const simd& rhs)

Min/Max Functions#

These functions are defined for all supported value_types.

simd Kokkos::min(const simd& lhs, const simd& rhs)
simd Kokkos::max(const simd& lhs, const simd& rhs)

`<cmath>` Functions#

These functions are only defined for value_type=double.

simd Kokkos::abs(const simd& lhs)
simd Kokkos::exp(const simd& lhs)
simd Kokkos::exp2(const simd& lhs)
simd Kokkos::log(const simd& lhs)
simd Kokkos::log10(const simd& lhs)
simd Kokkos::sqrt(const simd& lhs)
simd Kokkos::cbrt(const simd& lhs)
simd Kokkos::sin(const simd& lhs)
simd Kokkos::cos(const simd& lhs)
simd Kokkos::tan(const simd& lhs)
simd Kokkos::asin(const simd& lhs)
simd Kokkos::acos(const simd& lhs)
simd Kokkos::atan(const simd& lhs)
simd Kokkos::sinh(const simd& lhs)
simd Kokkos::cosh(const simd& lhs)
simd Kokkos::tanh(const simd& lhs)
simd Kokkos::asinh(const simd& lhs)
simd Kokkos::acosh(const simd& lhs)
simd Kokkos::atanh(const simd& lhs)
simd Kokkos::erf(const simd& lhs)
simd Kokkos::erfc(const simd& lhs)
simd Kokkos::tgamma(const simd& lhs)
simd Kokkos::lgamma(const simd& lhs)
simd Kokkos::pow(const simd& lhs, const simd& rhs)
simd Kokkos::hypot(const simd& x, const simd& y)
simd Kokkos::hypot(const simd& x, const simd& y, const simd& z)
simd Kokkos::atan2(const simd& x, const simd& y)
simd Kokkos::copysign(const simd& mag, const simd& sgn)
simd Kokkos::fma(const simd& x, const simd& y, const simd& z)

Global Typedefs#

template <class T> Kokkos::Experimental::native_simd: Alias for Kokkos::Experimental::simd<T, Kokkos::Experimental::simd_abi::native<T>>.

Examples#

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

int main(int argc, char* argv[]) {
  Kokkos::initialize(argc,argv);
  {
  using simd_type = Kokkos::Experimental::native_simd<double>;
  simd_type a([] (std::size_t i) { return 0.1 * i; });
  simd_type b(2.0);
  simd_type c = Kokkos::sqrt(a * a + b * b);
  for (std::size_t i = 0; i < simd_type::size(); ++i) {
    printf("[%zu] = %g\n", i, c[i]);
  }
  }
  Kokkos::finalize();
}

Experimental::simd#