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#ifndef KOKKOS_OPENMPTARGETEXEC_HPP
#define KOKKOS_OPENMPTARGETEXEC_HPP

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

#include <Kokkos_Atomic.hpp>
#include <iostream>
#include <sstream>
#include <fstream>
namespace Kokkos {
namespace Impl {

//----------------------------------------------------------------------------
/** \brief  Data for OpenMPTarget thread execution */

class OpenMPTargetExec {
 public:
  enum { MAX_ACTIVE_THREADS = 256 * 8 * 56 * 4 };
  enum { MAX_ACTIVE_TEAMS = MAX_ACTIVE_THREADS / 32 };

 private:
  static void* scratch_ptr;

 public:
  static void verify_is_process(const char* const);
  static void verify_initialized(const char* const);

  static void* get_scratch_ptr();
  static void clear_scratch();
  static void resize_scratch(int64_t reduce_bytes, int64_t team_reduce_bytes,
                             int64_t team_shared_bytes,
                             int64_t thread_local_bytes);

  static void* m_scratch_ptr;
  static int64_t m_scratch_size;
};

}  // namespace Impl
}  // namespace Kokkos

//----------------------------------------------------------------------------
//----------------------------------------------------------------------------

namespace Kokkos {
namespace Impl {

class OpenMPTargetExecTeamMember {
 public:
  enum { TEAM_REDUCE_SIZE = 512 };

  /** \brief  Thread states for team synchronization */
  enum { Active = 0, Rendezvous = 1 };

  typedef Kokkos::Experimental::OpenMPTarget execution_space;
  typedef execution_space::scratch_memory_space scratch_memory_space;

  scratch_memory_space m_team_shared;
  int m_team_scratch_size[2];
  int m_team_rank;
  int m_team_size;
  int m_league_rank;
  int m_league_size;
  int m_vector_length;
  int m_vector_lane;
  void* m_glb_scratch;

  /*
  // Fan-in team threads, root of the fan-in which does not block returns true
  inline
  bool team_fan_in() const
    {
      memory_fence();
      for ( int n = 1 , j ; ( ( j = m_team_rank_rev + n ) < m_team_size ) && ! (
  m_team_rank_rev & n ) ; n <<= 1 ) {

        m_exec.pool_rev( m_team_base_rev + j )->state_wait( Active );
      }

      if ( m_team_rank_rev ) {
        m_exec.state_set( Rendezvous );
        memory_fence();
        m_exec.state_wait( Rendezvous );
      }

      return 0 == m_team_rank_rev ;
    }

  inline
  void team_fan_out() const
    {
      memory_fence();
      for ( int n = 1 , j ; ( ( j = m_team_rank_rev + n ) < m_team_size ) && ! (
  m_team_rank_rev & n ) ; n <<= 1 ) { m_exec.pool_rev( m_team_base_rev + j
  )->state_set( Active ); memory_fence();
      }
    }
  */
 public:
  KOKKOS_INLINE_FUNCTION
  const execution_space::scratch_memory_space& team_shmem() const {
    return m_team_shared.set_team_thread_mode(0, 1, 0);
  }

  KOKKOS_INLINE_FUNCTION
  const execution_space::scratch_memory_space& team_scratch(int) const {
    return m_team_shared.set_team_thread_mode(0, 1, 0);
  }

  KOKKOS_INLINE_FUNCTION
  const execution_space::scratch_memory_space& thread_scratch(int) const {
    return m_team_shared.set_team_thread_mode(0, team_size(), team_rank());
  }

  KOKKOS_INLINE_FUNCTION int league_rank() const { return m_league_rank; }
  KOKKOS_INLINE_FUNCTION int league_size() const { return m_league_size; }
  KOKKOS_INLINE_FUNCTION int team_rank() const { return m_team_rank; }
  KOKKOS_INLINE_FUNCTION int team_size() const { return m_team_size; }

  KOKKOS_INLINE_FUNCTION void team_barrier() const {
#pragma omp barrier
  }

  template <class ValueType>
  KOKKOS_INLINE_FUNCTION void team_broadcast(ValueType& value,
                                             const int& thread_id) const {
    /*#if ! defined( KOKKOS_ACTIVE_EXECUTION_MEMORY_SPACE_HOST )
        { }
    #else
        // Make sure there is enough scratch space:
        typedef typename if_c< sizeof(ValueType) < TEAM_REDUCE_SIZE
                             , ValueType , void >::type type ;

        type * const local_value = ((type*) m_exec.scratch_thread());
        if(team_rank() == thread_id)
          *local_value = value;
        memory_fence();
        team_barrier();
        value = *local_value;
    #endif*/
  }

  template <class ValueType, class JoinOp>
  KOKKOS_INLINE_FUNCTION ValueType team_reduce(const ValueType& value,
                                               const JoinOp& op_in) const {
#pragma omp barrier

    typedef ValueType value_type;
    const JoinLambdaAdapter<value_type, JoinOp> op(op_in);

    // Make sure there is enough scratch space:
    typedef typename if_c<sizeof(value_type) < TEAM_REDUCE_SIZE, value_type,
                          void>::type type;

    const int n_values = TEAM_REDUCE_SIZE / sizeof(value_type);
    type* team_scratch =
        (type*)((char*)m_glb_scratch + TEAM_REDUCE_SIZE * omp_get_team_num());
    for (int i = m_team_rank; i < n_values; i += m_team_size) {
      team_scratch[i] = value_type();
    }

#pragma omp barrier

    for (int k = 0; k < m_team_size; k += n_values) {
      if ((k <= m_team_rank) && (k + n_values > m_team_rank))
        team_scratch[m_team_rank % n_values] += value;
#pragma omp barrier
    }

    for (int d = 1; d < n_values; d *= 2) {
      if ((m_team_rank + d < n_values) && (m_team_rank % (2 * d) == 0)) {
        team_scratch[m_team_rank] += team_scratch[m_team_rank + d];
      }
#pragma omp barrier
    }
    return team_scratch[0];
  }
  /** \brief  Intra-team exclusive prefix sum with team_rank() ordering
   *          with intra-team non-deterministic ordering accumulation.
   *
   *  The global inter-team accumulation value will, at the end of the
   *  league's parallel execution, be the scan's total.
   *  Parallel execution ordering of the league's teams is non-deterministic.
   *  As such the base value for each team's scan operation is similarly
   *  non-deterministic.
   */
  template <typename ArgType>
  KOKKOS_INLINE_FUNCTION ArgType team_scan(const ArgType& value,
                                           ArgType* const global_accum) const {
    /*  // Make sure there is enough scratch space:
      typedef typename if_c< sizeof(ArgType) < TEAM_REDUCE_SIZE , ArgType , void
      >::type type ;

      volatile type * const work_value  = ((type*) m_exec.scratch_thread());

      *work_value = value ;

      memory_fence();

      if ( team_fan_in() ) {
        // The last thread to synchronize returns true, all other threads wait
      for team_fan_out()
        // m_team_base[0]                 == highest ranking team member
        // m_team_base[ m_team_size - 1 ] == lowest ranking team member
        //
        // 1) copy from lower to higher rank, initialize lowest rank to zero
        // 2) prefix sum from lowest to highest rank, skipping lowest rank

        type accum = 0 ;

        if ( global_accum ) {
          for ( int i = m_team_size ; i-- ; ) {
            type & val = *((type*) m_exec.pool_rev( m_team_base_rev + i
      )->scratch_thread()); accum += val ;
          }
          accum = atomic_fetch_add( global_accum , accum );
        }

        for ( int i = m_team_size ; i-- ; ) {
          type & val = *((type*) m_exec.pool_rev( m_team_base_rev + i
      )->scratch_thread()); const type offset = accum ; accum += val ; val =
      offset ;
        }

        memory_fence();
      }

      team_fan_out();

      return *work_value ;*/
    return ArgType();
  }

  /** \brief  Intra-team exclusive prefix sum with team_rank() ordering.
   *
   *  The highest rank thread can compute the reduction total as
   *    reduction_total = dev.team_scan( value ) + value ;
   */
  template <typename Type>
  KOKKOS_INLINE_FUNCTION Type team_scan(const Type& value) const {
    return this->template team_scan<Type>(value, 0);
  }

  //----------------------------------------
  // Private for the driver

 private:
  typedef execution_space::scratch_memory_space space;

 public:
  inline OpenMPTargetExecTeamMember(
      const int league_rank, const int league_size, const int team_size,
      const int vector_length  // const TeamPolicyInternal< OpenMPTarget,
                               // Properties ...> & team
      ,
      void* const glb_scratch, const int shmem_size_L1, const int shmem_size_L2)
      : m_team_shared(0, 0),
        m_team_scratch_size{shmem_size_L1, shmem_size_L2},
        m_team_rank(0),
        m_vector_length(vector_length),
        m_team_size(team_size),
        m_league_rank(league_rank),
        m_league_size(league_size),
        m_glb_scratch(glb_scratch) {
    const int omp_tid = omp_get_thread_num();
    m_league_rank     = league_rank;
    m_team_rank       = omp_tid / m_vector_length;
    m_vector_lane     = omp_tid % m_vector_length;
  }

  static inline int team_reduce_size() { return TEAM_REDUCE_SIZE; }
};

template <class... Properties>
class TeamPolicyInternal<Kokkos::Experimental::OpenMPTarget, Properties...>
    : public PolicyTraits<Properties...> {
 public:
  //! Tag this class as a kokkos execution policy
  typedef TeamPolicyInternal execution_policy;

  typedef PolicyTraits<Properties...> traits;

  TeamPolicyInternal& operator=(const TeamPolicyInternal& p) {
    m_league_size            = p.m_league_size;
    m_team_size              = p.m_team_size;
    m_vector_length          = p.m_vector_length;
    m_team_alloc             = p.m_team_alloc;
    m_team_iter              = p.m_team_iter;
    m_team_scratch_size[0]   = p.m_team_scratch_size[0];
    m_thread_scratch_size[0] = p.m_thread_scratch_size[0];
    m_team_scratch_size[1]   = p.m_team_scratch_size[1];
    m_thread_scratch_size[1] = p.m_thread_scratch_size[1];
    m_chunk_size             = p.m_chunk_size;
    return *this;
  }

  //----------------------------------------

  template <class FunctorType>
  inline static int team_size_max(const FunctorType&, const ParallelForTag&) {
    return 256;
  }

  template <class FunctorType>
  inline static int team_size_max(const FunctorType&,
                                  const ParallelReduceTag&) {
    return 256;
  }

  template <class FunctorType, class ReducerType>
  inline static int team_size_max(const FunctorType&, const ReducerType&,
                                  const ParallelReduceTag&) {
    return 256;
  }

  template <class FunctorType>
  inline static int team_size_recommended(const FunctorType&,
                                          const ParallelForTag&) {
    return 128;
  }

  template <class FunctorType>
  inline static int team_size_recommended(const FunctorType&,
                                          const ParallelReduceTag&) {
    return 128;
  }

  template <class FunctorType, class ReducerType>
  inline static int team_size_recommended(const FunctorType&,
                                          const ReducerType&,
                                          const ParallelReduceTag&) {
    return 128;
  }

  //----------------------------------------

 private:
  int m_league_size;
  int m_team_size;
  int m_vector_length;
  int m_team_alloc;
  int m_team_iter;

  size_t m_team_scratch_size[2];
  size_t m_thread_scratch_size[2];

  int m_chunk_size;

  inline void init(const int league_size_request, const int team_size_request,
                   const int vector_length_request) {
    m_league_size = league_size_request;

    m_team_size = team_size_request;

    m_vector_length = vector_length_request;

    set_auto_chunk_size();
  }

 public:
  inline int vector_length() const { return m_vector_length; }
  inline int team_size() const { return m_team_size; }
  inline int league_size() const { return m_league_size; }
  inline size_t scratch_size(const int& level, int team_size_ = -1) const {
    if (team_size_ < 0) team_size_ = m_team_size;
    return m_team_scratch_size[level] +
           team_size_ * m_thread_scratch_size[level];
  }

  inline Kokkos::Experimental::OpenMPTarget space() const {
    return Kokkos::Experimental::OpenMPTarget();
  }

  /** \brief  Specify league size, request team size */
  TeamPolicyInternal(typename traits::execution_space&, int league_size_request,
                     int team_size_request, int vector_length_request = 1)
      : m_team_scratch_size{0, 0},
        m_thread_scratch_size{0, 0},
        m_chunk_size(0) {
    init(league_size_request, team_size_request, vector_length_request);
  }

  TeamPolicyInternal(typename traits::execution_space&, int league_size_request,
                     const Kokkos::AUTO_t& /* team_size_request */
                     ,
                     int vector_length_request = 1)
      : m_team_scratch_size{0, 0},
        m_thread_scratch_size{0, 0},
        m_chunk_size(0) {
    init(league_size_request, 256 / vector_length_request,
         vector_length_request);
  }

  TeamPolicyInternal(int league_size_request, int team_size_request,
                     int vector_length_request = 1)
      : m_team_scratch_size{0, 0},
        m_thread_scratch_size{0, 0},
        m_chunk_size(0) {
    init(league_size_request, team_size_request, vector_length_request);
  }

  TeamPolicyInternal(int league_size_request,
                     const Kokkos::AUTO_t& /* team_size_request */
                     ,
                     int vector_length_request = 1)
      : m_team_scratch_size{0, 0},
        m_thread_scratch_size{0, 0},
        m_chunk_size(0) {
    init(league_size_request, 256 / vector_length_request,
         vector_length_request);
  }

  inline int team_alloc() const { return m_team_alloc; }
  inline int team_iter() const { return m_team_iter; }

  inline int chunk_size() const { return m_chunk_size; }

#ifdef KOKKOS_ENABLE_DEPRECATED_CODE
  /** \brief set chunk_size to a discrete value*/
  inline TeamPolicyInternal set_chunk_size(
      typename traits::index_type chunk_size_) const {
    TeamPolicyInternal p = *this;
    p.m_chunk_size       = chunk_size_;
    return p;
  }

  inline TeamPolicyInternal set_scratch_size(
      const int& level, const PerTeamValue& per_team) const {
    TeamPolicyInternal p         = *this;
    p.m_team_scratch_size[level] = per_team.value;
    return p;
  }

  inline TeamPolicyInternal set_scratch_size(
      const int& level, const PerThreadValue& per_thread) const {
    TeamPolicyInternal p           = *this;
    p.m_thread_scratch_size[level] = per_thread.value;
    return p;
  }

  inline TeamPolicyInternal set_scratch_size(
      const int& level, const PerTeamValue& per_team,
      const PerThreadValue& per_thread) const {
    TeamPolicyInternal p           = *this;
    p.m_team_scratch_size[level]   = per_team.value;
    p.m_thread_scratch_size[level] = per_thread.value;
    return p;
  }
#else
  /** \brief set chunk_size to a discrete value*/
  inline TeamPolicyInternal& set_chunk_size(
      typename traits::index_type chunk_size_) {
    m_chunk_size = chunk_size_;
    return *this;
  }

  /** \brief set per team scratch size for a specific level of the scratch
   * hierarchy */
  inline TeamPolicyInternal& set_scratch_size(const int& level,
                                              const PerTeamValue& per_team) {
    m_team_scratch_size[level] = per_team.value;
    return *this;
  }

  /** \brief set per thread scratch size for a specific level of the scratch
   * hierarchy */
  inline TeamPolicyInternal& set_scratch_size(
      const int& level, const PerThreadValue& per_thread) {
    m_thread_scratch_size[level] = per_thread.value;
    return *this;
  }

  /** \brief set per thread and per team scratch size for a specific level of
   * the scratch hierarchy */
  inline TeamPolicyInternal& set_scratch_size(
      const int& level, const PerTeamValue& per_team,
      const PerThreadValue& per_thread) {
    m_team_scratch_size[level]   = per_team.value;
    m_thread_scratch_size[level] = per_thread.value;
    return *this;
  }
#endif

 protected:
#ifdef KOKKOS_ENABLE_DEPRECATED_CODE
  /** \brief set chunk_size to a discrete value*/
  inline TeamPolicyInternal internal_set_chunk_size(
      typename traits::index_type chunk_size_) {
    m_chunk_size = chunk_size_;
    return *this;
  }

  /** \brief set per team scratch size for a specific level of the scratch
   * hierarchy */
  inline TeamPolicyInternal internal_set_scratch_size(
      const int& level, const PerTeamValue& per_team) {
    m_team_scratch_size[level] = per_team.value;
    return *this;
  }

  /** \brief set per thread scratch size for a specific level of the scratch
   * hierarchy */
  inline TeamPolicyInternal internal_set_scratch_size(
      const int& level, const PerThreadValue& per_thread) {
    m_thread_scratch_size[level] = per_thread.value;
    return *this;
  }

  /** \brief set per thread and per team scratch size for a specific level of
   * the scratch hierarchy */
  inline TeamPolicyInternal internal_set_scratch_size(
      const int& level, const PerTeamValue& per_team,
      const PerThreadValue& per_thread) {
    m_team_scratch_size[level]   = per_team.value;
    m_thread_scratch_size[level] = per_thread.value;
    return *this;
  }
#endif

 private:
  /** \brief finalize chunk_size if it was set to AUTO*/
  inline void set_auto_chunk_size() {
    int concurrency = 2048 * 128;

    if (concurrency == 0) concurrency = 1;

    if (m_chunk_size > 0) {
      if (!Impl::is_integral_power_of_two(m_chunk_size))
        Kokkos::abort("TeamPolicy blocking granularity must be power of two");
    }

    int new_chunk_size = 1;
    while (new_chunk_size * 100 * concurrency < m_league_size)
      new_chunk_size *= 2;
    if (new_chunk_size < 128) {
      new_chunk_size = 1;
      while ((new_chunk_size * 40 * concurrency < m_league_size) &&
             (new_chunk_size < 128))
        new_chunk_size *= 2;
    }
    m_chunk_size = new_chunk_size;
  }

 public:
  typedef Impl::OpenMPTargetExecTeamMember member_type;
};
}  // namespace Impl

}  // namespace Kokkos

namespace Kokkos {

template <typename iType>
KOKKOS_INLINE_FUNCTION Impl::TeamThreadRangeBoundariesStruct<
    iType, Impl::OpenMPTargetExecTeamMember>
TeamThreadRange(const Impl::OpenMPTargetExecTeamMember& thread,
                const iType& count) {
  return Impl::TeamThreadRangeBoundariesStruct<
      iType, Impl::OpenMPTargetExecTeamMember>(thread, count);
}

template <typename iType>
KOKKOS_INLINE_FUNCTION Impl::TeamThreadRangeBoundariesStruct<
    iType, Impl::OpenMPTargetExecTeamMember>
TeamThreadRange(const Impl::OpenMPTargetExecTeamMember& thread,
                const iType& begin, const iType& end) {
  return Impl::TeamThreadRangeBoundariesStruct<
      iType, Impl::OpenMPTargetExecTeamMember>(thread, begin, end);
}

template <typename iType>
KOKKOS_INLINE_FUNCTION Impl::ThreadVectorRangeBoundariesStruct<
    iType, Impl::OpenMPTargetExecTeamMember>
ThreadVectorRange(const Impl::OpenMPTargetExecTeamMember& thread,
                  const iType& count) {
  return Impl::ThreadVectorRangeBoundariesStruct<
      iType, Impl::OpenMPTargetExecTeamMember>(thread, count);
}

template <typename iType>
KOKKOS_INLINE_FUNCTION Impl::ThreadVectorRangeBoundariesStruct<
    iType, Impl::OpenMPTargetExecTeamMember>
ThreadVectorRange(const Impl::OpenMPTargetExecTeamMember& thread,
                  const iType& arg_begin, const iType& arg_end) {
  return Impl::ThreadVectorRangeBoundariesStruct<
      iType, Impl::OpenMPTargetExecTeamMember>(thread, arg_begin, arg_end);
}

KOKKOS_INLINE_FUNCTION
Impl::ThreadSingleStruct<Impl::OpenMPTargetExecTeamMember> PerTeam(
    const Impl::OpenMPTargetExecTeamMember& thread) {
  return Impl::ThreadSingleStruct<Impl::OpenMPTargetExecTeamMember>(thread);
}

KOKKOS_INLINE_FUNCTION
Impl::VectorSingleStruct<Impl::OpenMPTargetExecTeamMember> PerThread(
    const Impl::OpenMPTargetExecTeamMember& thread) {
  return Impl::VectorSingleStruct<Impl::OpenMPTargetExecTeamMember>(thread);
}
}  // namespace Kokkos

namespace Kokkos {

/** \brief  Inter-thread parallel_for. Executes lambda(iType i) for each
 * i=0..N-1.
 *
 * The range i=0..N-1 is mapped to all threads of the the calling thread team.
 * This functionality requires C++11 support.*/
template <typename iType, class Lambda>
KOKKOS_INLINE_FUNCTION void parallel_for(
    const Impl::TeamThreadRangeBoundariesStruct<
        iType, Impl::OpenMPTargetExecTeamMember>& loop_boundaries,
    const Lambda& lambda) {
  for (iType i = loop_boundaries.start; i < loop_boundaries.end;
       i += loop_boundaries.increment)
    lambda(i);
}

/** \brief  Inter-thread vector parallel_reduce. Executes lambda(iType i,
 * ValueType & val) for each i=0..N-1.
 *
 * The range i=0..N-1 is mapped to all threads of the the calling thread team
 * and a summation of val is performed and put into result. This functionality
 * requires C++11 support.*/
template <typename iType, class Lambda, typename ValueType>
KOKKOS_INLINE_FUNCTION void parallel_reduce(
    const Impl::TeamThreadRangeBoundariesStruct<
        iType, Impl::OpenMPTargetExecTeamMember>& loop_boundaries,
    const Lambda& lambda, ValueType& result) {
  result = ValueType();

  for (iType i = loop_boundaries.start; i < loop_boundaries.end;
       i += loop_boundaries.increment) {
    ValueType tmp = ValueType();
    lambda(i, tmp);
    result += tmp;
  }

  // result =
  // loop_boundaries.thread.team_reduce(result,Impl::JoinAdd<ValueType>());
}

/** \brief  Intra-thread vector parallel_reduce. Executes lambda(iType i,
 * ValueType & val) for each i=0..N-1.
 *
 * The range i=0..N-1 is mapped to all vector lanes of the the calling thread
 * and a reduction of val is performed using JoinType(ValueType& val, const
 * ValueType& update) and put into init_result. The input value of init_result
 * is used as initializer for temporary variables of ValueType. Therefore the
 * input value should be the neutral element with respect to the join operation
 * (e.g. '0 for +-' or '1 for *'). This functionality requires C++11 support.*/
template <typename iType, class Lambda, typename ValueType, class JoinType>
KOKKOS_INLINE_FUNCTION void parallel_reduce(
    const Impl::TeamThreadRangeBoundariesStruct<
        iType, Impl::OpenMPTargetExecTeamMember>& loop_boundaries,
    const Lambda& lambda, const JoinType& join, ValueType& init_result) {
  ValueType result = init_result;

  for (iType i = loop_boundaries.start; i < loop_boundaries.end;
       i += loop_boundaries.increment) {
    ValueType tmp = ValueType();
    lambda(i, tmp);
    join(result, tmp);
  }

  // init_result = loop_boundaries.thread.team_reduce(result,join);
}

}  // namespace Kokkos

namespace Kokkos {
/** \brief  Intra-thread vector parallel_for. Executes lambda(iType i) for each
 * i=0..N-1.
 *
 * The range i=0..N-1 is mapped to all vector lanes of the the calling thread.
 * This functionality requires C++11 support.*/
template <typename iType, class Lambda>
KOKKOS_INLINE_FUNCTION void parallel_for(
    const Impl::ThreadVectorRangeBoundariesStruct<
        iType, Impl::OpenMPTargetExecTeamMember>& loop_boundaries,
    const Lambda& lambda) {
  for (iType i = loop_boundaries.start; i < loop_boundaries.end;
       i += loop_boundaries.increment)
    lambda(i);
}

/** \brief  Intra-thread vector parallel_reduce. Executes lambda(iType i,
 * ValueType & val) for each i=0..N-1.
 *
 * The range i=0..N-1 is mapped to all vector lanes of the the calling thread
 * and a summation of val is performed and put into result. This functionality
 * requires C++11 support.*/
template <typename iType, class Lambda, typename ValueType>
KOKKOS_INLINE_FUNCTION void parallel_reduce(
    const Impl::ThreadVectorRangeBoundariesStruct<
        iType, Impl::OpenMPTargetExecTeamMember>& loop_boundaries,
    const Lambda& lambda, ValueType& result) {
  result = ValueType();
  for (iType i = loop_boundaries.start; i < loop_boundaries.end;
       i += loop_boundaries.increment) {
    ValueType tmp = ValueType();
    lambda(i, tmp);
    result += tmp;
  }
}

/** \brief  Intra-thread vector parallel_reduce. Executes lambda(iType i,
 * ValueType & val) for each i=0..N-1.
 *
 * The range i=0..N-1 is mapped to all vector lanes of the the calling thread
 * and a reduction of val is performed using JoinType(ValueType& val, const
 * ValueType& update) and put into init_result. The input value of init_result
 * is used as initializer for temporary variables of ValueType. Therefore the
 * input value should be the neutral element with respect to the join operation
 * (e.g. '0 for +-' or '1 for *'). This functionality requires C++11 support.*/
template <typename iType, class Lambda, typename ValueType, class JoinType>
KOKKOS_INLINE_FUNCTION void parallel_reduce(
    const Impl::ThreadVectorRangeBoundariesStruct<
        iType, Impl::OpenMPTargetExecTeamMember>& loop_boundaries,
    const Lambda& lambda, const JoinType& join, ValueType& init_result) {
  ValueType result = init_result;
#ifdef KOKKOS_ENABLE_PRAGMA_IVDEP
#pragma ivdep
#endif
  for (iType i = loop_boundaries.start; i < loop_boundaries.end;
       i += loop_boundaries.increment) {
    ValueType tmp = ValueType();
    lambda(i, tmp);
    join(result, tmp);
  }
  init_result = result;
}

/** \brief  Intra-thread vector parallel exclusive prefix sum. Executes
 * lambda(iType i, ValueType & val, bool final) for each i=0..N-1.
 *
 * The range i=0..N-1 is mapped to all vector lanes in the thread and a scan
 * operation is performed. Depending on the target execution space the operator
 * might be called twice: once with final=false and once with final=true. When
 * final==true val contains the prefix sum value. The contribution of this "i"
 * needs to be added to val no matter whether final==true or not. In a serial
 * execution (i.e. team_size==1) the operator is only called once with
 * final==true. Scan_val will be set to the final sum value over all vector
 * lanes. This functionality requires C++11 support.*/
template <typename iType, class FunctorType>
KOKKOS_INLINE_FUNCTION void parallel_scan(
    const Impl::ThreadVectorRangeBoundariesStruct<
        iType, Impl::OpenMPTargetExecTeamMember>& loop_boundaries,
    const FunctorType& lambda) {
  typedef Kokkos::Impl::FunctorValueTraits<FunctorType, void> ValueTraits;
  typedef typename ValueTraits::value_type value_type;

  value_type scan_val = value_type();

#ifdef KOKKOS_ENABLE_PRAGMA_IVDEP
#pragma ivdep
#endif
  for (iType i = loop_boundaries.start; i < loop_boundaries.end;
       i += loop_boundaries.increment) {
    lambda(i, scan_val, true);
  }
}

}  // namespace Kokkos

namespace Kokkos {

template <class FunctorType>
KOKKOS_INLINE_FUNCTION void single(
    const Impl::VectorSingleStruct<Impl::OpenMPTargetExecTeamMember>&
        single_struct,
    const FunctorType& lambda) {
  lambda();
}

template <class FunctorType>
KOKKOS_INLINE_FUNCTION void single(
    const Impl::ThreadSingleStruct<Impl::OpenMPTargetExecTeamMember>&
        single_struct,
    const FunctorType& lambda) {
  if (single_struct.team_member.team_rank() == 0) lambda();
}

template <class FunctorType, class ValueType>
KOKKOS_INLINE_FUNCTION void single(
    const Impl::VectorSingleStruct<Impl::OpenMPTargetExecTeamMember>&
        single_struct,
    const FunctorType& lambda, ValueType& val) {
  lambda(val);
}

template <class FunctorType, class ValueType>
KOKKOS_INLINE_FUNCTION void single(
    const Impl::ThreadSingleStruct<Impl::OpenMPTargetExecTeamMember>&
        single_struct,
    const FunctorType& lambda, ValueType& val) {
  if (single_struct.team_member.team_rank() == 0) {
    lambda(val);
  }
  single_struct.team_member.team_broadcast(val, 0);
}
}  // namespace Kokkos

#endif /* #ifndef KOKKOS_OPENMPTARGETEXEC_HPP */
