amd_hip_cooperative_groups.h

/*
Copyright (c) 2015 - 2023 Advanced Micro Devices, Inc. All rights reserved.

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
*/

/**
 *  @file  amd_detail/hip_cooperative_groups.h
 *
 *  @brief Device side implementation of `Cooperative Group` feature.
 *
 *  Defines new types and device API wrappers related to `Cooperative Group`
 *  feature, which the programmer can directly use in his kernel(s) in order to
 *  make use of this feature.
 */
#ifndef HIP_INCLUDE_HIP_AMD_DETAIL_HIP_COOPERATIVE_GROUPS_H
#define HIP_INCLUDE_HIP_AMD_DETAIL_HIP_COOPERATIVE_GROUPS_H

#if __cplusplus
#if !defined(__HIPCC_RTC__)
#include <hip/amd_detail/hip_cooperative_groups_helper.h>
#endif

namespace cooperative_groups {

/** @brief The base type of all cooperative group types
 *
 *  \details Holds the key properties of a constructed cooperative group types
 *           object, like the group type, its size, etc
 *
 *  @note  Cooperative groups feature is implemented on Linux, under developement
 *  on Windows.
 */
class thread_group {
 protected:
  uint32_t _type;  // thread_group type
  uint32_t _size;  // total number of threads in the tread_group
  uint64_t _mask;  // Lanemask for coalesced and tiled partitioned group types,
                   // LSB represents lane 0, and MSB represents lane 63

  // Construct a thread group, and set thread group type and other essential
  // thread group properties. This generic thread group is directly constructed
  // only when the group is supposed to contain only the calling the thread
  // (throurh the API - `this_thread()`), and in all other cases, this thread
  // group object is a sub-object of some other derived thread group object
  __CG_QUALIFIER__ thread_group(internal::group_type type, uint32_t size = static_cast<uint64_t>(0),
                                uint64_t mask = static_cast<uint64_t>(0)) {
    _type = type;
    _size = size;
    _mask = mask;
  }

  struct _tiled_info {
    bool is_tiled;
    unsigned int size;
    unsigned int meta_group_rank;
    unsigned int meta_group_size;
  };

  struct _coalesced_info {
    lane_mask member_mask;
    unsigned int size;
    struct _tiled_info tiled_info;
  } coalesced_info;

  friend __CG_QUALIFIER__ thread_group tiled_partition(const thread_group& parent,
                                                       unsigned int tile_size);
  friend class thread_block;

 public:
  // Total number of threads in the thread group, and this serves the purpose
  // for all derived cooperative group types since their `size` is directly
  // saved during the construction
  __CG_QUALIFIER__ uint32_t size() const { return _size; }
  __CG_QUALIFIER__ unsigned int cg_type() const { return _type; }
  // Rank of the calling thread within [0, size())
  __CG_QUALIFIER__ uint32_t thread_rank() const;
  // Is this cooperative group type valid?
  __CG_QUALIFIER__ bool is_valid() const;
  // synchronize the threads in the thread group
  __CG_QUALIFIER__ void sync() const;
};
/**
 *-------------------------------------------------------------------------------------------------
 *-------------------------------------------------------------------------------------------------
 *  @defgroup CooperativeG Cooperative Groups
 *  @ingroup API
 *  @{
 *  This section describes the cooperative groups functions of HIP runtime API.
 *  
 *  The cooperative groups provides flexible thread parallel programming algorithms, threads
 *  cooperate and share data to perform collective computations.
 *
 *  @note  Cooperative groups feature is implemented on Linux, under developement
 *  on Windows.
 *
 */
/** \brief The multi-grid cooperative group type
 *
 *  \details Represents an inter-device cooperative group type where the
 *           participating threads within the group spans across multple
 *           devices, running the (same) kernel on these devices
 * @note  The multi-grid cooperative group type is implemented on Linux, under developement
 *  on Windows.
 */
class multi_grid_group : public thread_group {
  // Only these friend functions are allowed to construct an object of this class
  // and access its resources
  friend __CG_QUALIFIER__ multi_grid_group this_multi_grid();

 protected:
  // Construct mutli-grid thread group (through the API this_multi_grid())
  explicit __CG_QUALIFIER__ multi_grid_group(uint32_t size)
      : thread_group(internal::cg_multi_grid, size) {}

 public:
  // Number of invocations participating in this multi-grid group. In other
  // words, the number of GPUs
  __CG_QUALIFIER__ uint32_t num_grids() { return internal::multi_grid::num_grids(); }
  // Rank of this invocation. In other words, an ID number within the range
  // [0, num_grids()) of the GPU, this kernel is running on
  __CG_QUALIFIER__ uint32_t grid_rank() { return internal::multi_grid::grid_rank(); }
  __CG_QUALIFIER__ uint32_t thread_rank() const { return internal::multi_grid::thread_rank(); }
  __CG_QUALIFIER__ bool is_valid() const { return internal::multi_grid::is_valid(); }
  __CG_QUALIFIER__ void sync() const { internal::multi_grid::sync(); }
};

/** @brief User exposed API interface to construct multi-grid cooperative
 *         group type object - `multi_grid_group`
 *
 *  \details User is not allowed to directly construct an object of type
 *           `multi_grid_group`. Instead, he should construct it through this
 *           API function
 *  @note  This multi-grid cooperative API type is implemented on Linux, under developement
 *  on Windows.
 */
__CG_QUALIFIER__ multi_grid_group this_multi_grid() {
  return multi_grid_group(internal::multi_grid::size());
}

/** @brief The grid cooperative group type
 *
 *  \details Represents an inter-workgroup cooperative group type where the
 *           participating threads within the group spans across multiple
 *           workgroups running the (same) kernel on the same device
 *  @note  This is implemented on Linux, under developement
 *  on Windows.
 */
class grid_group : public thread_group {
  // Only these friend functions are allowed to construct an object of this class
  // and access its resources
  friend __CG_QUALIFIER__ grid_group this_grid();

 protected:
  // Construct grid thread group (through the API this_grid())
  explicit __CG_QUALIFIER__ grid_group(uint32_t size) : thread_group(internal::cg_grid, size) {}

 public:
  __CG_QUALIFIER__ uint32_t thread_rank() const { return internal::grid::thread_rank(); }
  __CG_QUALIFIER__ bool is_valid() const { return internal::grid::is_valid(); }
  __CG_QUALIFIER__ void sync() const { internal::grid::sync(); }
};

/** @brief User exposed API interface to construct grid cooperative group type
 *         object - `grid_group`
 *
 *  \details User is not allowed to directly construct an object of type
 *           `multi_grid_group`. Instead, he should construct it through this
 *           API function
 *  @note  This function is implemented on Linux, under developement
 *  on Windows.
 */
__CG_QUALIFIER__ grid_group this_grid() { return grid_group(internal::grid::size()); }

/** @brief   The workgroup (thread-block in CUDA terminology) cooperative group
 *           type
 *
 *  \details Represents an intra-workgroup cooperative group type where the
 *           participating threads within the group are exactly the same threads
 *           which are participated in the currently executing `workgroup`
 *  @note  This is implemented on Linux, under developement
 *  on Windows.
 */
class thread_block : public thread_group {
  // Only these friend functions are allowed to construct an object of thi
  // class and access its resources
  friend __CG_QUALIFIER__ thread_block this_thread_block();
  friend __CG_QUALIFIER__ thread_group tiled_partition(const thread_group& parent,
                                                       unsigned int tile_size);
  friend __CG_QUALIFIER__ thread_group tiled_partition(const thread_block& parent,
                                                       unsigned int tile_size);
 protected:
  // Construct a workgroup thread group (through the API this_thread_block())
  explicit __CG_QUALIFIER__ thread_block(uint32_t size)
      : thread_group(internal::cg_workgroup, size) {}

  __CG_QUALIFIER__ thread_group new_tiled_group(unsigned int tile_size) const {
    const bool pow2 = ((tile_size & (tile_size - 1)) == 0);
    // Invalid tile size, assert
    if (!tile_size || (tile_size > __AMDGCN_WAVEFRONT_SIZE) || !pow2) {
      __hip_assert(false && "invalid tile size");
    }
 
    auto block_size = size();
    auto rank = thread_rank();
    auto partitions = (block_size + tile_size - 1) / tile_size;
    auto tail = (partitions * tile_size) - block_size;
    auto partition_size = tile_size - tail * (rank >= (partitions - 1) * tile_size);
    thread_group tiledGroup = thread_group(internal::cg_tiled_group, partition_size);

    tiledGroup.coalesced_info.tiled_info.size = tile_size;
    tiledGroup.coalesced_info.tiled_info.is_tiled = true;
    tiledGroup.coalesced_info.tiled_info.meta_group_rank = rank / tile_size;
    tiledGroup.coalesced_info.tiled_info.meta_group_size = partitions;
    return tiledGroup;
  }

 public:
  // 3-dimensional block index within the grid
  __CG_STATIC_QUALIFIER__ dim3 group_index() { return internal::workgroup::group_index(); }
  // 3-dimensional thread index within the block
  __CG_STATIC_QUALIFIER__ dim3 thread_index() { return internal::workgroup::thread_index(); }
  __CG_STATIC_QUALIFIER__ uint32_t thread_rank() { return internal::workgroup::thread_rank(); }
  __CG_STATIC_QUALIFIER__ uint32_t size() { return internal::workgroup::size(); }
  __CG_STATIC_QUALIFIER__ bool is_valid() { return internal::workgroup::is_valid(); }
  __CG_STATIC_QUALIFIER__ void sync() { internal::workgroup::sync(); }
  __CG_QUALIFIER__ dim3 group_dim() { return internal::workgroup::block_dim(); }
};

/** \brief   User exposed API interface to construct workgroup cooperative
 *           group type object - `thread_block`.
 *
 *  \details User is not allowed to directly construct an object of type
 *           `thread_block`. Instead, he should construct it through this API
 *           function.
 *  @note  This function is implemented on Linux, under developement
 *  on Windows.
 */
__CG_QUALIFIER__ thread_block this_thread_block() {
  return thread_block(internal::workgroup::size());
}

/** \brief   The tiled_group cooperative group type
 *
 *  \details Represents one tiled thread group in a wavefront.
 *           This group type also supports sub-wave level intrinsics.
 *  @note  This is implemented on Linux, under developement
 *  on Windows.
 */

class tiled_group : public thread_group {
 private:
  friend __CG_QUALIFIER__ thread_group tiled_partition(const thread_group& parent,
                                                       unsigned int tile_size);
  friend __CG_QUALIFIER__ tiled_group tiled_partition(const tiled_group& parent,
                                                      unsigned int tile_size);

  __CG_QUALIFIER__ tiled_group new_tiled_group(unsigned int tile_size) const {
    const bool pow2 = ((tile_size & (tile_size - 1)) == 0);

    if (!tile_size || (tile_size > __AMDGCN_WAVEFRONT_SIZE) || !pow2) {
      __hip_assert(false && "invalid tile size");
    }

    if (size() <= tile_size) {
      return *this;
    }

    tiled_group tiledGroup = tiled_group(tile_size);
    tiledGroup.coalesced_info.tiled_info.is_tiled = true;
    return tiledGroup;
  }

 protected:
  explicit __CG_QUALIFIER__ tiled_group(unsigned int tileSize)
      : thread_group(internal::cg_tiled_group, tileSize) {
    coalesced_info.tiled_info.size = tileSize;
    coalesced_info.tiled_info.is_tiled = true;
  }

 public:
  __CG_QUALIFIER__ unsigned int size() const { return (coalesced_info.tiled_info.size); }

  __CG_QUALIFIER__ unsigned int thread_rank() const {
    return (internal::workgroup::thread_rank() & (coalesced_info.tiled_info.size - 1));
  }

  __CG_QUALIFIER__ void sync() const {
    internal::tiled_group::sync();
  }
};

/** \brief   The coalesced_group cooperative group type
 *
 *  \details Represents a active thread group in a wavefront.
 *           This group type also supports sub-wave level intrinsics.
 *  @note  This is implemented on Linux, under developement
 *  on Windows.
 */
class coalesced_group : public thread_group {
 private:
  friend __CG_QUALIFIER__ coalesced_group coalesced_threads();
  friend __CG_QUALIFIER__ thread_group tiled_partition(const thread_group& parent, unsigned int tile_size);
  friend __CG_QUALIFIER__ coalesced_group tiled_partition(const coalesced_group& parent, unsigned int tile_size);

  __CG_QUALIFIER__ coalesced_group new_tiled_group(unsigned int tile_size) const {
    const bool pow2 = ((tile_size & (tile_size - 1)) == 0);

    if (!tile_size || (tile_size > size()) || !pow2) {
      return coalesced_group(0);
    }

    // If a tiled group is passed to be partitioned further into a coalesced_group.
    // prepare a mask for further partitioning it so that it stays coalesced.
    if (coalesced_info.tiled_info.is_tiled) {
      unsigned int base_offset = (thread_rank() & (~(tile_size - 1)));
      unsigned int masklength = min(static_cast<unsigned int>(size()) - base_offset, tile_size);
      lane_mask member_mask = static_cast<lane_mask>(-1) >> (__AMDGCN_WAVEFRONT_SIZE - masklength);

      member_mask <<= (__lane_id() & ~(tile_size - 1));
      coalesced_group coalesced_tile = coalesced_group(member_mask);
      coalesced_tile.coalesced_info.tiled_info.is_tiled = true;
      coalesced_tile.coalesced_info.tiled_info.meta_group_rank = thread_rank() / tile_size;
      coalesced_tile.coalesced_info.tiled_info.meta_group_size = size() / tile_size;
      return coalesced_tile;
    }
    // Here the parent coalesced_group is not partitioned.
    else {
      lane_mask member_mask = 0;
      unsigned int tile_rank = 0;
      int lanes_to_skip = ((thread_rank()) / tile_size) * tile_size;

      for (unsigned int i = 0; i < __AMDGCN_WAVEFRONT_SIZE; i++) {
        lane_mask active = coalesced_info.member_mask & (1 << i);
        // Make sure the lane is active
        if (active) {
          if (lanes_to_skip <= 0 && tile_rank < tile_size) {
             // Prepare a member_mask that is appropriate for a tile
            member_mask |= active;
            tile_rank++;
          }
          lanes_to_skip--;
        }
      }
      coalesced_group coalesced_tile = coalesced_group(member_mask);
      coalesced_tile.coalesced_info.tiled_info.meta_group_rank = thread_rank() / tile_size;
      coalesced_tile.coalesced_info.tiled_info.meta_group_size =
                                                      (size() + tile_size - 1) / tile_size;
      return coalesced_tile;
    }
     return coalesced_group(0);
  }

 protected:
 // Constructor
  explicit __CG_QUALIFIER__ coalesced_group(lane_mask member_mask)
      : thread_group(internal::cg_coalesced_group) {
    coalesced_info.member_mask = member_mask; // Which threads are active
    coalesced_info.size = __popcll(coalesced_info.member_mask); // How many threads are active
    coalesced_info.tiled_info.is_tiled = false; // Not a partitioned group
    coalesced_info.tiled_info.meta_group_rank = 0;
    coalesced_info.tiled_info.meta_group_size = 1;
  }

 public:
   __CG_QUALIFIER__ unsigned int size() const {
     return coalesced_info.size;
   }

   __CG_QUALIFIER__ unsigned int thread_rank() const {
     return internal::coalesced_group::masked_bit_count(coalesced_info.member_mask);
    }

   __CG_QUALIFIER__ void sync() const {
       internal::coalesced_group::sync();
    }

   __CG_QUALIFIER__ unsigned int meta_group_rank() const {
       return coalesced_info.tiled_info.meta_group_rank;
    }

   __CG_QUALIFIER__ unsigned int meta_group_size() const {
       return coalesced_info.tiled_info.meta_group_size;
   }

  template <class T>
  __CG_QUALIFIER__ T shfl(T var, int srcRank) const {
    static_assert(is_valid_type<T>::value, "Neither an integer or float type.");

    srcRank = srcRank % static_cast<int>(size());

    int lane = (size() == __AMDGCN_WAVEFRONT_SIZE) ? srcRank
             : (__AMDGCN_WAVEFRONT_SIZE == 64)     ? __fns64(coalesced_info.member_mask, 0, (srcRank + 1))
                                          : __fns32(coalesced_info.member_mask, 0, (srcRank + 1));

    return __shfl(var, lane, __AMDGCN_WAVEFRONT_SIZE);
  }

  template <class T>
  __CG_QUALIFIER__ T shfl_down(T var, unsigned int lane_delta) const {
    static_assert(is_valid_type<T>::value, "Neither an integer or float type.");

    // Note: The cuda implementation appears to use the remainder of lane_delta
    // and WARP_SIZE as the shift value rather than lane_delta itself.
    // This is not described in the documentation and is not done here.

    if (size() == __AMDGCN_WAVEFRONT_SIZE) {
      return __shfl_down(var, lane_delta, __AMDGCN_WAVEFRONT_SIZE);
    }

    int lane;
    if (__AMDGCN_WAVEFRONT_SIZE == 64) {
      lane = __fns64(coalesced_info.member_mask, __lane_id(), lane_delta + 1);
    }
    else {
      lane = __fns32(coalesced_info.member_mask, __lane_id(), lane_delta + 1);
    }

    if (lane == -1) {
      lane = __lane_id();
    }

    return __shfl(var, lane, __AMDGCN_WAVEFRONT_SIZE);
  }

  template <class T>
  __CG_QUALIFIER__ T shfl_up(T var, unsigned int lane_delta) const {
    static_assert(is_valid_type<T>::value, "Neither an integer or float type.");

    // Note: The cuda implementation appears to use the remainder of lane_delta
    // and WARP_SIZE as the shift value rather than lane_delta itself.
    // This is not described in the documentation and is not done here.

    if (size() == __AMDGCN_WAVEFRONT_SIZE) {
      return __shfl_up(var, lane_delta, __AMDGCN_WAVEFRONT_SIZE);
    }

    int lane;
    if (__AMDGCN_WAVEFRONT_SIZE == 64) {
      lane = __fns64(coalesced_info.member_mask, __lane_id(), -(lane_delta + 1));
    }
    else if (__AMDGCN_WAVEFRONT_SIZE == 32) {
      lane = __fns32(coalesced_info.member_mask, __lane_id(), -(lane_delta + 1));
    }

    if (lane == -1) {
      lane = __lane_id();
    }

    return __shfl(var, lane, __AMDGCN_WAVEFRONT_SIZE);
  }
};

/** \brief   User exposed API to create coalesced groups.
 *
 *  \details A collective operation that groups  all active lanes into a new thread group.
 *  @note  This function is implemented on Linux, under developement
 *  on Windows.
 */

__CG_QUALIFIER__ coalesced_group coalesced_threads() {
    return cooperative_groups::coalesced_group(__builtin_amdgcn_read_exec());
}

/**
 *  Implemenation of all publicly exposed base class APIs
 *  @note  This function is implemented on Linux, under developement
 *  on Windows.
 */
__CG_QUALIFIER__ uint32_t thread_group::thread_rank() const {
  switch (this->_type) {
    case internal::cg_multi_grid: {
      return (static_cast<const multi_grid_group*>(this)->thread_rank());
    }
    case internal::cg_grid: {
      return (static_cast<const grid_group*>(this)->thread_rank());
    }
    case internal::cg_workgroup: {
      return (static_cast<const thread_block*>(this)->thread_rank());
    }
    case internal::cg_tiled_group: {
      return (static_cast<const tiled_group*>(this)->thread_rank());
    }
    case internal::cg_coalesced_group: {
      return (static_cast<const coalesced_group*>(this)->thread_rank());
    }
    default: {
      __hip_assert(false && "invalid cooperative group type");
      return -1;
    }
  }
}
/**
 *  Implemenation of all publicly exposed thread group API
 *  @note  This function is implemented on Linux, under developement
 *  on Windows.
 */
__CG_QUALIFIER__ bool thread_group::is_valid() const {
  switch (this->_type) {
    case internal::cg_multi_grid: {
      return (static_cast<const multi_grid_group*>(this)->is_valid());
    }
    case internal::cg_grid: {
      return (static_cast<const grid_group*>(this)->is_valid());
    }
    case internal::cg_workgroup: {
      return (static_cast<const thread_block*>(this)->is_valid());
    }
    case internal::cg_tiled_group: {
      return (static_cast<const tiled_group*>(this)->is_valid());
    }
    case internal::cg_coalesced_group: {
      return (static_cast<const coalesced_group*>(this)->is_valid());
    }
    default: {
      __hip_assert(false && "invalid cooperative group type");
      return false;
    }
  }
}
/**
 *  Implemenation of all publicly exposed thread group sync API
 *  @note  This function is implemented on Linux, under developement
 *  on Windows.
 */
__CG_QUALIFIER__ void thread_group::sync() const {
  switch (this->_type) {
    case internal::cg_multi_grid: {
      static_cast<const multi_grid_group*>(this)->sync();
      break;
    }
    case internal::cg_grid: {
      static_cast<const grid_group*>(this)->sync();
      break;
    }
    case internal::cg_workgroup: {
      static_cast<const thread_block*>(this)->sync();
      break;
    }
    case internal::cg_tiled_group: {
      static_cast<const tiled_group*>(this)->sync();
      break;
    }
    case internal::cg_coalesced_group: {
      static_cast<const coalesced_group*>(this)->sync();
      break;
    }
    default: {
      __hip_assert(false && "invalid cooperative group type");
    }
  }
}

/**
 *  Implemenation of publicly exposed `wrapper` API on top of basic cooperative
 *  group type APIs
 *  @note  This function is implemented on Linux, under developement
 *  on Windows.
 */
template <class CGTy> __CG_QUALIFIER__ uint32_t group_size(CGTy const& g) { return g.size(); }
/**
 *  Implemenation of publicly exposed `wrapper` API on top of basic cooperative
 *  group type APIs
 *  @note  This function is implemented on Linux, under developement
 *  on Windows.
 */
template <class CGTy> __CG_QUALIFIER__ uint32_t thread_rank(CGTy const& g) {
  return g.thread_rank();
}
/**
 *  Implemenation of publicly exposed `wrapper` API on top of basic cooperative
 *  group type APIs
 *  @note  This function is implemented on Linux, under developement
 *  on Windows.
 */
template <class CGTy> __CG_QUALIFIER__ bool is_valid(CGTy const& g) { return g.is_valid(); }
/**
 *  Implemenation of publicly exposed `wrapper` API on top of basic cooperative
 *  group type APIs
 *  @note  This function is implemented on Linux, under developement
 *  on Windows.
 */
template <class CGTy> __CG_QUALIFIER__ void sync(CGTy const& g) { g.sync(); }
/**
 * template class tile_base
 *  @note  This class is implemented on Linux, under developement
 *  on Windows.
 */
template <unsigned int tileSize> class tile_base {
 protected:
  _CG_STATIC_CONST_DECL_ unsigned int numThreads = tileSize;

 public:
  // Rank of the thread within this tile
  _CG_STATIC_CONST_DECL_ unsigned int thread_rank() {
    return (internal::workgroup::thread_rank() & (numThreads - 1));
  }

  // Number of threads within this tile
  __CG_STATIC_QUALIFIER__ unsigned int size() { return numThreads; }
};
/**
 * template class thread_block_tile_base
 *  @note  This class is implemented on Linux, under developement
 *  on Windows.
 */
template <unsigned int size> class thread_block_tile_base : public tile_base<size> {
  static_assert(is_valid_tile_size<size>::value,
                "Tile size is either not a power of 2 or greater than the wavefront size");
  using tile_base<size>::numThreads;

 public:
  __CG_STATIC_QUALIFIER__ void sync() {
    internal::tiled_group::sync();
  }

  template <class T> __CG_QUALIFIER__ T shfl(T var, int srcRank) const {
    static_assert(is_valid_type<T>::value, "Neither an integer or float type.");
    return (__shfl(var, srcRank, numThreads));
  }

  template <class T> __CG_QUALIFIER__ T shfl_down(T var, unsigned int lane_delta) const {
    static_assert(is_valid_type<T>::value, "Neither an integer or float type.");
    return (__shfl_down(var, lane_delta, numThreads));
  }

  template <class T> __CG_QUALIFIER__ T shfl_up(T var, unsigned int lane_delta) const {
    static_assert(is_valid_type<T>::value, "Neither an integer or float type.");
    return (__shfl_up(var, lane_delta, numThreads));
  }

  template <class T> __CG_QUALIFIER__ T shfl_xor(T var, unsigned int laneMask) const {
    static_assert(is_valid_type<T>::value, "Neither an integer or float type.");
    return (__shfl_xor(var, laneMask, numThreads));
  }
};
/** \brief   User exposed API that captures the state of the parent group pre-partition
 */
template <unsigned int tileSize, typename ParentCGTy>
class parent_group_info {
public:
  // Returns the linear rank of the group within the set of tiles partitioned
  // from a parent group (bounded by meta_group_size)
  __CG_STATIC_QUALIFIER__ unsigned int meta_group_rank() {
    return ParentCGTy::thread_rank() / tileSize;
  }

  // Returns the number of groups created when the parent group was partitioned.
  __CG_STATIC_QUALIFIER__ unsigned int meta_group_size() {
    return (ParentCGTy::size() + tileSize - 1) / tileSize;
  }
};

/** \brief   Group type - thread_block_tile
 *
 *  \details  Represents one tile of thread group.
 *  @note  This type is implemented on Linux, under developement
 *  on Windows.
 */
template <unsigned int tileSize, class ParentCGTy>
class thread_block_tile_type : public thread_block_tile_base<tileSize>,
                               public tiled_group,
                               public parent_group_info<tileSize, ParentCGTy> {
  _CG_STATIC_CONST_DECL_ unsigned int numThreads = tileSize;
  typedef thread_block_tile_base<numThreads> tbtBase;
  protected:
    __CG_QUALIFIER__ thread_block_tile_type() : tiled_group(numThreads) {
      coalesced_info.tiled_info.size = numThreads;
      coalesced_info.tiled_info.is_tiled = true;
    }
  public:
    using tbtBase::size;
    using tbtBase::sync;
    using tbtBase::thread_rank;
};

// Partial template specialization
template <unsigned int tileSize>
class thread_block_tile_type<tileSize, void> : public thread_block_tile_base<tileSize>,
                               public tiled_group
                             {
  _CG_STATIC_CONST_DECL_ unsigned int numThreads = tileSize;

  typedef thread_block_tile_base<numThreads> tbtBase;

 protected:

    __CG_QUALIFIER__ thread_block_tile_type(unsigned int meta_group_rank, unsigned int meta_group_size)
        : tiled_group(numThreads) {
    coalesced_info.tiled_info.size = numThreads;
    coalesced_info.tiled_info.is_tiled = true;
    coalesced_info.tiled_info.meta_group_rank = meta_group_rank;
    coalesced_info.tiled_info.meta_group_size = meta_group_size;
  }

 public:
  using tbtBase::size;
  using tbtBase::sync;
  using tbtBase::thread_rank;

  __CG_QUALIFIER__ unsigned int meta_group_rank() const {
    return coalesced_info.tiled_info.meta_group_rank;
  }

  __CG_QUALIFIER__ unsigned int meta_group_size() const {
    return coalesced_info.tiled_info.meta_group_size;
  }
// end of operative group
/**
* @}
*/
};


/** \brief   User exposed API to partition groups.
 *
 *  \details A collective operation that partitions the parent group into a one-dimensional,
 *           row-major, tiling of subgroups.
 */

__CG_QUALIFIER__ thread_group tiled_partition(const thread_group& parent, unsigned int tile_size) {
  if (parent.cg_type() == internal::cg_tiled_group) {
    const tiled_group* cg = static_cast<const tiled_group*>(&parent);
    return cg->new_tiled_group(tile_size);
  }
  else if(parent.cg_type() == internal::cg_coalesced_group) {
    const coalesced_group* cg = static_cast<const coalesced_group*>(&parent);
    return cg->new_tiled_group(tile_size);
  }
  else {
    const thread_block* tb = static_cast<const thread_block*>(&parent);
    return tb->new_tiled_group(tile_size);
  }
}

// Thread block type overload
__CG_QUALIFIER__ thread_group tiled_partition(const thread_block& parent, unsigned int tile_size) {
  return (parent.new_tiled_group(tile_size));
}

__CG_QUALIFIER__ tiled_group tiled_partition(const tiled_group& parent, unsigned int tile_size) {
  return (parent.new_tiled_group(tile_size));
}

// If a coalesced group is passed to be partitioned, it should remain coalesced
__CG_QUALIFIER__ coalesced_group tiled_partition(const coalesced_group& parent, unsigned int tile_size) {
    return (parent.new_tiled_group(tile_size));
}

template <unsigned int size, class ParentCGTy> class thread_block_tile;

namespace impl {
template <unsigned int size, class ParentCGTy> class thread_block_tile_internal;

template <unsigned int size, class ParentCGTy>
class thread_block_tile_internal : public thread_block_tile_type<size, ParentCGTy> {
 protected:
  template <unsigned int tbtSize, class tbtParentT>
  __CG_QUALIFIER__ thread_block_tile_internal(
      const thread_block_tile_internal<tbtSize, tbtParentT>& g)
      : thread_block_tile_type<size, ParentCGTy>(g.meta_group_rank(), g.meta_group_size()) {}

  __CG_QUALIFIER__ thread_block_tile_internal(const thread_block& g)
      : thread_block_tile_type<size, ParentCGTy>() {}
};
}  // namespace impl

template <unsigned int size, class ParentCGTy>
class thread_block_tile : public impl::thread_block_tile_internal<size, ParentCGTy> {
 protected:
  __CG_QUALIFIER__ thread_block_tile(const ParentCGTy& g)
      : impl::thread_block_tile_internal<size, ParentCGTy>(g) {}

 public:
  __CG_QUALIFIER__ operator thread_block_tile<size, void>() const {
    return thread_block_tile<size, void>(*this);
  }
};


template <unsigned int size>
class thread_block_tile<size, void> : public impl::thread_block_tile_internal<size, void> {
  template <unsigned int, class ParentCGTy> friend class thread_block_tile;

 protected:
 public:
  template <class ParentCGTy>
  __CG_QUALIFIER__ thread_block_tile(const thread_block_tile<size, ParentCGTy>& g)
      : impl::thread_block_tile_internal<size, void>(g) {}
};

template <unsigned int size, class ParentCGTy = void> class thread_block_tile;

namespace impl {
template <unsigned int size, class ParentCGTy> struct tiled_partition_internal;

template <unsigned int size>
struct tiled_partition_internal<size, thread_block> : public thread_block_tile<size, thread_block> {
  __CG_QUALIFIER__ tiled_partition_internal(const thread_block& g)
      : thread_block_tile<size, thread_block>(g) {}
};

}  // namespace impl

/** \brief   User exposed API to partition groups.
 *
 *  \details  This constructs a templated class derieved from thread_group.
 *            The template defines tile size of the new thread group at compile time.
 */
template <unsigned int size, class ParentCGTy>
__CG_QUALIFIER__ thread_block_tile<size, ParentCGTy> tiled_partition(const ParentCGTy& g) {
  static_assert(is_valid_tile_size<size>::value,
                "Tiled partition with size > wavefront size. Currently not supported ");
  return impl::tiled_partition_internal<size, ParentCGTy>(g);
}
}  // namespace cooperative_groups

#endif  // __cplusplus
#endif  // HIP_INCLUDE_HIP_AMD_DETAIL_HIP_COOPERATIVE_GROUPS_H