tile_iterator_tensor_op.h

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#pragma once

#include "cutlass/array.h"
#include "cutlass/layout/matrix.h"
#include "cutlass/layout/pitch_linear.h"

#include "cutlass/epilogue/warp/tensor_op_policy.h"


namespace cutlass {
namespace epilogue {
namespace warp {


template <
  typename WarpShape,     
  typename OperatorShape, 
  typename Element,       
  typename Layout         
>
class TileIteratorTensorOp;


template <
  typename WarpShape_,     
  typename OperatorShape_, 
  typename Element_        
>
class TileIteratorTensorOp<WarpShape_, OperatorShape_, Element_, layout::RowMajor> {
public:

  using WarpShape = WarpShape_;
  using OperatorShape = OperatorShape_;
  using Element = Element_;
  using Layout = layout::RowMajor;

  using TensorRef = TensorRef<Element, Layout>;         
  using TensorCoord = MatrixCoord;                      
  using Index = typename TensorRef::Index;
  using LongIndex = typename TensorRef::LongIndex;

  using Policy = TensorOpPolicy<WarpShape, OperatorShape, Layout>;

  using Shape = MatrixShape<
    Policy::kRowsPerIteration,
    WarpShape::kN
  >;

  using Fragment = Array<
    Element, 
    Policy::OperatorCount::kColumn * Policy::kElementsPerAccess>;

  //using AccumulatorTile = typename Operator::FragmentC;

  static int const kIterations = Policy::kIterations;

  // Internal constants
  struct Detail {
    static int const kLanesInQuad = 4;
  };

  using Padding = MatrixShape<
    0,
    Detail::kLanesInQuad * Policy::kElementsPerAccess>;

private:

  using AccessType = AlignedArray<Element, Policy::kElementsPerAccess>;

  //
  // Data members
  //

  AccessType *pointer_;

  Layout layout_;

public:

  CUTLASS_HOST_DEVICE
  TileIteratorTensorOp(): pointer_(nullptr) { }

  CUTLASS_HOST_DEVICE
  TileIteratorTensorOp(
    TensorRef const &ref,
    unsigned lane_id
  ):
    pointer_(reinterpret_cast<AccessType *>(ref.data())),
    layout_(ref.stride()[0] / Policy::kElementsPerAccess) { 

    int quad_id = (lane_id / Detail::kLanesInQuad); 
    int lane_in_quad = (lane_id % Detail::kLanesInQuad);

    pointer_ += layout_({quad_id, lane_in_quad});
  }

  CUTLASS_HOST_DEVICE
  TileIteratorTensorOp & add_pointer_offset(Index pointer_offset) {
    pointer_ += pointer_offset / Policy::kElementsPerAccess;
    return *this;
  }

  CUTLASS_HOST_DEVICE
  TileIteratorTensorOp & add_tile_offset(TensorCoord const &tile_offset) {

    pointer_ += layout_({
      tile_offset.row() * Shape::kRow, 
      (tile_offset.column() * Shape::kColumn / Policy::kElementsPerAccess)
    });

    return *this;
  }

  CUTLASS_HOST_DEVICE
  TileIteratorTensorOp & operator+=(TensorCoord const &tile_offset) {
    add_tile_offset(tile_offset);
    return *this;
  }

  CUTLASS_HOST_DEVICE
  void store_with_pointer_offset(Fragment const &frag, Index pointer_offset) {

    AccessType const *frag_ptr = reinterpret_cast<AccessType const *>(&frag);

    CUTLASS_PRAGMA_UNROLL
    for (int n = 0; n < Policy::OperatorCount::kColumn; ++n) {
      pointer_[n * Detail::kLanesInQuad + pointer_offset / Policy::kElementsPerAccess] = frag_ptr[n];
    }
  }

  CUTLASS_HOST_DEVICE
  void store(Fragment const &frag) {
    store_with_pointer_offset(frag, 0);
  }

  CUTLASS_HOST_DEVICE
  void load_with_pointer_offset(Fragment &frag, Index pointer_offset) const {

    AccessType *frag_ptr = reinterpret_cast<AccessType *>(&frag);

    CUTLASS_PRAGMA_UNROLL
    for (int n = 0; n < Policy::OperatorCount::kColumn; ++n) {
      frag_ptr[n] = pointer_[n * Detail::kLanesInQuad + pointer_offset / Policy::kElementsPerAccess];
    }
  }

  CUTLASS_HOST_DEVICE
  void load(Fragment &frag) const {
    load_with_pointer_offset(frag, 0);
  }
};


} // namespace warp
} // namespace epilogue
} // namespace cutlass