Kokkos_ScratchSpace.hpp

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#ifndef KOKKOS_SCRATCHSPACE_HPP
#define KOKKOS_SCRATCHSPACE_HPP

#include <cstdio>
#include <Kokkos_Core_fwd.hpp>
#include <Kokkos_Concepts.hpp>

/*--------------------------------------------------------------------------*/

namespace Kokkos {

template <class ExecSpace>
class ScratchMemorySpace {
  static_assert(
      is_execution_space<ExecSpace>::value,
      "Instantiating ScratchMemorySpace on non-execution-space type.");

 public:
  // Alignment of memory chunks returned by 'get'
  // must be a power of two
  enum { ALIGN = 8 };

 private:
  mutable char* m_iter_L0;
  char* m_end_L0;
  mutable char* m_iter_L1;
  char* m_end_L1;

  mutable int m_multiplier;
  mutable int m_offset;
  mutable int m_default_level;

  ScratchMemorySpace();
  ScratchMemorySpace& operator=(const ScratchMemorySpace&);

  enum { MASK = ALIGN - 1 };  // Alignment used by View::shmem_size

 public:
  typedef ScratchMemorySpace memory_space;
  typedef ExecSpace execution_space;
  typedef Kokkos::Device<execution_space, memory_space> device_type;

  typedef typename ExecSpace::array_layout array_layout;
  typedef typename ExecSpace::size_type size_type;

  static constexpr const char* name() { return "ScratchMemorySpace"; }

  template <typename IntType>
  KOKKOS_INLINE_FUNCTION static IntType align(const IntType& size) {
    return (size + MASK) & ~MASK;
  }

  template <typename IntType>
  KOKKOS_INLINE_FUNCTION void* get_shmem(const IntType& size,
                                         int level = -1) const {
    if (level == -1) level = m_default_level;
    if (level == 0) {
      void* tmp = m_iter_L0 + m_offset * align(size);
      if (m_end_L0 < (m_iter_L0 += align(size) * m_multiplier)) {
        m_iter_L0 -= align(size) * m_multiplier;  // put it back like it was
#ifdef KOKKOS_DEBUG
        // mfh 23 Jun 2015: printf call consumes 25 registers
        // in a CUDA build, so only print in debug mode.  The
        // function still returns nullptr if not enough memory.
        printf(
            "ScratchMemorySpace<...>::get_shmem: Failed to allocate "
            "%ld byte(s); remaining capacity is %ld byte(s)\n",
            long(size), long(m_end_L0 - m_iter_L0));
#endif  // KOKKOS_DEBUG
        tmp = nullptr;
      }
      return tmp;
    } else {
      void* tmp = m_iter_L1 + m_offset * align(size);
      if (m_end_L1 < (m_iter_L1 += align(size) * m_multiplier)) {
        m_iter_L1 -= align(size) * m_multiplier;  // put it back like it was
#ifdef KOKKOS_DEBUG
        // mfh 23 Jun 2015: printf call consumes 25 registers
        // in a CUDA build, so only print in debug mode.  The
        // function still returns nullptr if not enough memory.
        printf(
            "ScratchMemorySpace<...>::get_shmem: Failed to allocate "
            "%ld byte(s); remaining capacity is %ld byte(s)\n",
            long(size), long(m_end_L1 - m_iter_L1));
#endif  // KOKKOS_DEBUG
        tmp = nullptr;
      }
      return tmp;
    }
  }

  KOKKOS_INLINE_FUNCTION
  void* get_shmem_aligned(const ptrdiff_t size, const ptrdiff_t alignment,
                          int level = -1) const {
    if (level == -1) level = m_default_level;
    if (level == 0) {
      char* previous            = m_iter_L0;
      const ptrdiff_t missalign = size_t(m_iter_L0) % alignment;
      if (missalign) m_iter_L0 += alignment - missalign;

      void* tmp = m_iter_L0 + m_offset * size;
      if (m_end_L0 < (m_iter_L0 += size * m_multiplier)) {
        m_iter_L0 = previous;  // put it back like it was
#ifdef KOKKOS_DEBUG
        // mfh 23 Jun 2015: printf call consumes 25 registers
        // in a CUDA build, so only print in debug mode.  The
        // function still returns nullptr if not enough memory.
        printf(
            "ScratchMemorySpace<...>::get_shmem: Failed to allocate "
            "%ld byte(s); remaining capacity is %ld byte(s)\n",
            long(size), long(m_end_L0 - m_iter_L0));
#endif  // KOKKOS_DEBUG
        tmp = nullptr;
      }
      return tmp;
    } else {
      char* previous            = m_iter_L1;
      const ptrdiff_t missalign = size_t(m_iter_L1) % alignment;
      if (missalign) m_iter_L1 += alignment - missalign;

      void* tmp = m_iter_L1 + m_offset * size;
      if (m_end_L1 < (m_iter_L1 += size * m_multiplier)) {
        m_iter_L1 = previous;  // put it back like it was
#ifdef KOKKOS_DEBUG
        // mfh 23 Jun 2015: printf call consumes 25 registers
        // in a CUDA build, so only print in debug mode.  The
        // function still returns nullptr if not enough memory.
        printf(
            "ScratchMemorySpace<...>::get_shmem: Failed to allocate "
            "%ld byte(s); remaining capacity is %ld byte(s)\n",
            long(size), long(m_end_L1 - m_iter_L1));
#endif  // KOKKOS_DEBUG
        tmp = nullptr;
      }
      return tmp;
    }
  }

  template <typename IntType>
  KOKKOS_INLINE_FUNCTION ScratchMemorySpace(void* ptr_L0,
                                            const IntType& size_L0,
                                            void* ptr_L1           = nullptr,
                                            const IntType& size_L1 = 0)
      : m_iter_L0((char*)ptr_L0),
        m_end_L0(m_iter_L0 + size_L0),
        m_iter_L1((char*)ptr_L1),
        m_end_L1(m_iter_L1 + size_L1),
        m_multiplier(1),
        m_offset(0),
        m_default_level(0) {}

  KOKKOS_INLINE_FUNCTION
  const ScratchMemorySpace& set_team_thread_mode(const int& level,
                                                 const int& multiplier,
                                                 const int& offset) const {
    m_default_level = level;
    m_multiplier    = multiplier;
    m_offset        = offset;
    return *this;
  }
};

}  // namespace Kokkos

#endif /* #ifndef KOKKOS_SCRATCHSPACE_HPP */