Kokkos_Layout.hpp

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//@HEADER
// ************************************************************************
//
//                        Kokkos v. 4.0
//       Copyright (2022) National Technology & Engineering
//               Solutions of Sandia, LLC (NTESS).
//
// Under the terms of Contract DE-NA0003525 with NTESS,
// the U.S. Government retains certain rights in this software.
//
// Part of Kokkos, under the Apache License v2.0 with LLVM Exceptions.
// See https://kokkos.org/LICENSE for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//@HEADER


#ifndef KOKKOS_IMPL_PUBLIC_INCLUDE
#include <Kokkos_Macros.hpp>
static_assert(false,
              "Including non-public Kokkos header files is not allowed.");
#endif
#ifndef KOKKOS_LAYOUT_HPP
#define KOKKOS_LAYOUT_HPP

#include <cstddef>
#include <impl/Kokkos_Traits.hpp>

namespace Kokkos {

enum { ARRAY_LAYOUT_MAX_RANK = 8 };

//----------------------------------------------------------------------------
struct LayoutLeft {
  using array_layout = LayoutLeft;

  size_t dimension[ARRAY_LAYOUT_MAX_RANK];
  // we don't have a constructor to set the stride directly
  // but we will deprecate the class anyway (or at least using an instance of
  // this class) when switching the internal implementation to use mdspan
  size_t stride;

  enum : bool { is_extent_constructible = true };

  LayoutLeft(LayoutLeft const&)            = default;
  LayoutLeft(LayoutLeft&&)                 = default;
  LayoutLeft& operator=(LayoutLeft const&) = default;
  LayoutLeft& operator=(LayoutLeft&&)      = default;

  KOKKOS_INLINE_FUNCTION
  explicit constexpr LayoutLeft(size_t N0 = KOKKOS_IMPL_CTOR_DEFAULT_ARG,
                                size_t N1 = KOKKOS_IMPL_CTOR_DEFAULT_ARG,
                                size_t N2 = KOKKOS_IMPL_CTOR_DEFAULT_ARG,
                                size_t N3 = KOKKOS_IMPL_CTOR_DEFAULT_ARG,
                                size_t N4 = KOKKOS_IMPL_CTOR_DEFAULT_ARG,
                                size_t N5 = KOKKOS_IMPL_CTOR_DEFAULT_ARG,
                                size_t N6 = KOKKOS_IMPL_CTOR_DEFAULT_ARG,
                                size_t N7 = KOKKOS_IMPL_CTOR_DEFAULT_ARG)
      : dimension{N0, N1, N2, N3, N4, N5, N6, N7},
        stride(KOKKOS_IMPL_CTOR_DEFAULT_ARG) {}

  friend bool operator==(const LayoutLeft& left, const LayoutLeft& right) {
    for (unsigned int rank = 0; rank < ARRAY_LAYOUT_MAX_RANK; ++rank)
      if (left.dimension[rank] != right.dimension[rank]) return false;
    return true;
  }

  friend bool operator!=(const LayoutLeft& left, const LayoutLeft& right) {
    return !(left == right);
  }
};

//----------------------------------------------------------------------------
struct LayoutRight {
  using array_layout = LayoutRight;

  size_t dimension[ARRAY_LAYOUT_MAX_RANK];
  // we don't have a constructor to set the stride directly
  // but we will deprecate the class anyway (or at least using an instance of
  // this class) when switching the internal implementation to use mdspan
  size_t stride;

  enum : bool { is_extent_constructible = true };

  LayoutRight(LayoutRight const&)            = default;
  LayoutRight(LayoutRight&&)                 = default;
  LayoutRight& operator=(LayoutRight const&) = default;
  LayoutRight& operator=(LayoutRight&&)      = default;

  KOKKOS_INLINE_FUNCTION
  explicit constexpr LayoutRight(size_t N0 = KOKKOS_IMPL_CTOR_DEFAULT_ARG,
                                 size_t N1 = KOKKOS_IMPL_CTOR_DEFAULT_ARG,
                                 size_t N2 = KOKKOS_IMPL_CTOR_DEFAULT_ARG,
                                 size_t N3 = KOKKOS_IMPL_CTOR_DEFAULT_ARG,
                                 size_t N4 = KOKKOS_IMPL_CTOR_DEFAULT_ARG,
                                 size_t N5 = KOKKOS_IMPL_CTOR_DEFAULT_ARG,
                                 size_t N6 = KOKKOS_IMPL_CTOR_DEFAULT_ARG,
                                 size_t N7 = KOKKOS_IMPL_CTOR_DEFAULT_ARG)
      : dimension{N0, N1, N2, N3, N4, N5, N6, N7},
        stride{KOKKOS_IMPL_CTOR_DEFAULT_ARG} {}

  friend bool operator==(const LayoutRight& left, const LayoutRight& right) {
    for (unsigned int rank = 0; rank < ARRAY_LAYOUT_MAX_RANK; ++rank)
      if (left.dimension[rank] != right.dimension[rank]) return false;
    return true;
  }

  friend bool operator!=(const LayoutRight& left, const LayoutRight& right) {
    return !(left == right);
  }
};

//----------------------------------------------------------------------------
struct LayoutStride {
  using array_layout = LayoutStride;

  size_t dimension[ARRAY_LAYOUT_MAX_RANK];
  size_t stride[ARRAY_LAYOUT_MAX_RANK];

  enum : bool { is_extent_constructible = false };

  LayoutStride(LayoutStride const&)            = default;
  LayoutStride(LayoutStride&&)                 = default;
  LayoutStride& operator=(LayoutStride const&) = default;
  LayoutStride& operator=(LayoutStride&&)      = default;

  template <typename iTypeOrder, typename iTypeDimen>
  KOKKOS_INLINE_FUNCTION static LayoutStride order_dimensions(
      int const rank, iTypeOrder const* const order,
      iTypeDimen const* const dimen) {
    LayoutStride tmp;
    // Verify valid rank order:
    int check_input = ARRAY_LAYOUT_MAX_RANK < rank ? 0 : int(1 << rank) - 1;
    for (int r = 0; r < ARRAY_LAYOUT_MAX_RANK; ++r) {
      tmp.dimension[r] = KOKKOS_IMPL_CTOR_DEFAULT_ARG;
      tmp.stride[r]    = 0;
    }
    for (int r = 0; r < rank; ++r) {
      check_input &= ~int(1 << order[r]);
    }
    if (0 == check_input) {
      size_t n = 1;
      for (int r = 0; r < rank; ++r) {
        tmp.stride[order[r]] = n;
        n *= (dimen[order[r]]);
        tmp.dimension[r] = dimen[r];
      }
    }
    return tmp;
  }

  KOKKOS_INLINE_FUNCTION
  explicit constexpr LayoutStride(
      size_t N0 = KOKKOS_IMPL_CTOR_DEFAULT_ARG, size_t S0 = 0,
      size_t N1 = KOKKOS_IMPL_CTOR_DEFAULT_ARG, size_t S1 = 0,
      size_t N2 = KOKKOS_IMPL_CTOR_DEFAULT_ARG, size_t S2 = 0,
      size_t N3 = KOKKOS_IMPL_CTOR_DEFAULT_ARG, size_t S3 = 0,
      size_t N4 = KOKKOS_IMPL_CTOR_DEFAULT_ARG, size_t S4 = 0,
      size_t N5 = KOKKOS_IMPL_CTOR_DEFAULT_ARG, size_t S5 = 0,
      size_t N6 = KOKKOS_IMPL_CTOR_DEFAULT_ARG, size_t S6 = 0,
      size_t N7 = KOKKOS_IMPL_CTOR_DEFAULT_ARG, size_t S7 = 0)
      : dimension{N0, N1, N2, N3, N4, N5, N6, N7},
        stride{S0, S1, S2, S3, S4, S5, S6, S7} {}

  friend bool operator==(const LayoutStride& left, const LayoutStride& right) {
    for (unsigned int rank = 0; rank < ARRAY_LAYOUT_MAX_RANK; ++rank)
      if (left.dimension[rank] != right.dimension[rank] ||
          left.stride[rank] != right.stride[rank])
        return false;
    return true;
  }

  friend bool operator!=(const LayoutStride& left, const LayoutStride& right) {
    return !(left == right);
  }
};

// ===================================================================================


enum class Iterate {
  Default,
  Left,  // Left indices stride fastest
  Right  // Right indices stride fastest
};

#ifdef KOKKOS_ENABLE_DEPRECATED_CODE_4
template <typename Layout, class Enable = void>
struct KOKKOS_DEPRECATED is_layouttiled : std::false_type {};
#endif

namespace Impl {
// For use with view_copy
template <typename... Layout>
struct layout_iterate_type_selector {
  static const Kokkos::Iterate outer_iteration_pattern =
      Kokkos::Iterate::Default;
  static const Kokkos::Iterate inner_iteration_pattern =
      Kokkos::Iterate::Default;
};

template <>
struct layout_iterate_type_selector<Kokkos::LayoutRight> {
  static const Kokkos::Iterate outer_iteration_pattern = Kokkos::Iterate::Right;
  static const Kokkos::Iterate inner_iteration_pattern = Kokkos::Iterate::Right;
};

template <>
struct layout_iterate_type_selector<Kokkos::LayoutLeft> {
  static const Kokkos::Iterate outer_iteration_pattern = Kokkos::Iterate::Left;
  static const Kokkos::Iterate inner_iteration_pattern = Kokkos::Iterate::Left;
};

template <>
struct layout_iterate_type_selector<Kokkos::LayoutStride> {
  static const Kokkos::Iterate outer_iteration_pattern =
      Kokkos::Iterate::Default;
  static const Kokkos::Iterate inner_iteration_pattern =
      Kokkos::Iterate::Default;
};
}  // namespace Impl

#ifdef KOKKOS_ENABLE_DEPRECATED_CODE_4
template <typename... Layout>
using layout_iterate_type_selector KOKKOS_DEPRECATED =
    Impl::layout_iterate_type_selector<Layout...>;
#endif

}  // namespace Kokkos

#endif  // #ifndef KOKKOS_LAYOUT_HPP