Eigen/src/Core/Assign.h

// This file is part of Eigen, a lightweight C++ template library
// for linear algebra. Eigen itself is part of the KDE project.
//
// Copyright (C) 2007 Michael Olbrich <michael.olbrich@gmx.net>
// Copyright (C) 2006-2008 Benoit Jacob <jacob.benoit.1@gmail.com>
// Copyright (C) 2008 Gael Guennebaud <g.gael@free.fr>
//
// Eigen is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 3 of the License, or (at your option) any later version.
//
// Alternatively, you can redistribute it and/or
// modify it under the terms of the GNU General Public License as
// published by the Free Software Foundation; either version 2 of
// the License, or (at your option) any later version.
//
// Eigen is distributed in the hope that it will be useful, but WITHOUT ANY
// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
// FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License or the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License and a copy of the GNU General Public License along with
// Eigen. If not, see <http://www.gnu.org/licenses/>.

#ifndef EIGEN_ASSIGN_H
#define EIGEN_ASSIGN_H

/***************************************************************************
* Part 1 : the logic deciding a strategy for vectorization and unrolling
***************************************************************************/

template <typename Derived, typename OtherDerived>
struct ei_assign_traits
{
public:
  enum {
    DstIsAligned = Derived::Flags & AlignedBit,
    SrcIsAligned = OtherDerived::Flags & AlignedBit,
    SrcAlignment = DstIsAligned && SrcIsAligned ? Aligned : Unaligned
  };

private:
  enum {
    InnerSize = int(Derived::Flags)&RowMajorBit
              ? Derived::ColsAtCompileTime
              : Derived::RowsAtCompileTime,
    InnerMaxSize = int(Derived::Flags)&RowMajorBit
              ? Derived::MaxColsAtCompileTime
              : Derived::MaxRowsAtCompileTime,
    PacketSize = ei_packet_traits<typename Derived::Scalar>::size
  };

  enum {
    MightVectorize = (int(Derived::Flags) & int(OtherDerived::Flags) & ActualPacketAccessBit)
                  && ((int(Derived::Flags)&RowMajorBit)==(int(OtherDerived::Flags)&RowMajorBit)),
    MayInnerVectorize  = MightVectorize && int(InnerSize)!=Dynamic && int(InnerSize)%int(PacketSize)==0
                       && int(DstIsAligned) && int(SrcIsAligned),
    MayLinearVectorize = MightVectorize && (int(Derived::Flags) & int(OtherDerived::Flags) & LinearAccessBit),
    MaySliceVectorize  = MightVectorize && int(InnerMaxSize)>=3*PacketSize /* slice vectorization can be slow, so we only
      want it if the slices are big, which is indicated by InnerMaxSize rather than InnerSize, think of the case
      of a dynamic block in a fixed-size matrix */
  };

public:
  enum {
    Vectorization = int(MayInnerVectorize)  ? int(InnerVectorization)
                  : int(MayLinearVectorize) ? int(LinearVectorization)
                  : int(MaySliceVectorize)  ? int(SliceVectorization)
                                            : int(NoVectorization)
  };

private:
  enum {
    UnrollingLimit      = EIGEN_UNROLLING_LIMIT * (int(Vectorization) == int(NoVectorization) ? 1 : int(PacketSize)),
    MayUnrollCompletely = int(Derived::SizeAtCompileTime) * int(OtherDerived::CoeffReadCost) <= int(UnrollingLimit),
    MayUnrollInner      = int(InnerSize * OtherDerived::CoeffReadCost) <= int(UnrollingLimit)
  };

public:
  enum {
    Unrolling = (int(Vectorization) == int(InnerVectorization) || int(Vectorization) == int(NoVectorization))
              ? (
                   int(MayUnrollCompletely) ? int(CompleteUnrolling)
                 : int(MayUnrollInner)      ? int(InnerUnrolling)
                                            : int(NoUnrolling)
                )
              : int(Vectorization) == int(LinearVectorization)
              ? ( int(MayUnrollCompletely) && int(DstIsAligned) ? int(CompleteUnrolling) : int(NoUnrolling) )
              : int(NoUnrolling)
  };
};

/***************************************************************************
* Part 2 : meta-unrollers
***************************************************************************/

/***********************
*** No vectorization ***
***********************/

template<typename Derived1, typename Derived2, int Index, int Stop>
struct ei_assign_novec_CompleteUnrolling
{
  enum {
    row = int(Derived1::Flags)&RowMajorBit
        ? Index / int(Derived1::ColsAtCompileTime)
        : Index % Derived1::RowsAtCompileTime,
    col = int(Derived1::Flags)&RowMajorBit
        ? Index % int(Derived1::ColsAtCompileTime)
        : Index / Derived1::RowsAtCompileTime
  };

  EIGEN_STRONG_INLINE static void run(Derived1 &dst, const Derived2 &src)
  {
    dst.copyCoeff(row, col, src);
    ei_assign_novec_CompleteUnrolling<Derived1, Derived2, Index+1, Stop>::run(dst, src);
  }
};

template<typename Derived1, typename Derived2, int Stop>
struct ei_assign_novec_CompleteUnrolling<Derived1, Derived2, Stop, Stop>
{
  EIGEN_STRONG_INLINE static void run(Derived1 &, const Derived2 &) {}
};

template<typename Derived1, typename Derived2, int Index, int Stop>
struct ei_assign_novec_InnerUnrolling
{
  EIGEN_STRONG_INLINE static void run(Derived1 &dst, const Derived2 &src, int row_or_col)
  {
    const bool rowMajor = int(Derived1::Flags)&RowMajorBit;
    const int row = rowMajor ? row_or_col : Index;
    const int col = rowMajor ? Index : row_or_col;
    dst.copyCoeff(row, col, src);
    ei_assign_novec_InnerUnrolling<Derived1, Derived2, Index+1, Stop>::run(dst, src, row_or_col);
  }
};

template<typename Derived1, typename Derived2, int Stop>
struct ei_assign_novec_InnerUnrolling<Derived1, Derived2, Stop, Stop>
{
  EIGEN_STRONG_INLINE static void run(Derived1 &, const Derived2 &, int) {}
};

/**************************
*** Inner vectorization ***
**************************/

template<typename Derived1, typename Derived2, int Index, int Stop>
struct ei_assign_innervec_CompleteUnrolling
{
  enum {
    row = int(Derived1::Flags)&RowMajorBit
        ? Index / int(Derived1::ColsAtCompileTime)
        : Index % Derived1::RowsAtCompileTime,
    col = int(Derived1::Flags)&RowMajorBit
        ? Index % int(Derived1::ColsAtCompileTime)
        : Index / Derived1::RowsAtCompileTime,
    SrcAlignment = ei_assign_traits<Derived1,Derived2>::SrcAlignment
  };

  EIGEN_STRONG_INLINE static void run(Derived1 &dst, const Derived2 &src)
  {
    dst.template copyPacket<Derived2, Aligned, SrcAlignment>(row, col, src);
    ei_assign_innervec_CompleteUnrolling<Derived1, Derived2,
      Index+ei_packet_traits<typename Derived1::Scalar>::size, Stop>::run(dst, src);
  }
};

template<typename Derived1, typename Derived2, int Stop>
struct ei_assign_innervec_CompleteUnrolling<Derived1, Derived2, Stop, Stop>
{
  EIGEN_STRONG_INLINE static void run(Derived1 &, const Derived2 &) {}
};

template<typename Derived1, typename Derived2, int Index, int Stop>
struct ei_assign_innervec_InnerUnrolling
{
  EIGEN_STRONG_INLINE static void run(Derived1 &dst, const Derived2 &src, int row_or_col)
  {
    const int row = int(Derived1::Flags)&RowMajorBit ? row_or_col : Index;
    const int col = int(Derived1::Flags)&RowMajorBit ? Index : row_or_col;
    dst.template copyPacket<Derived2, Aligned, Aligned>(row, col, src);
    ei_assign_innervec_InnerUnrolling<Derived1, Derived2,
      Index+ei_packet_traits<typename Derived1::Scalar>::size, Stop>::run(dst, src, row_or_col);
  }
};

template<typename Derived1, typename Derived2, int Stop>
struct ei_assign_innervec_InnerUnrolling<Derived1, Derived2, Stop, Stop>
{
  EIGEN_STRONG_INLINE static void run(Derived1 &, const Derived2 &, int) {}
};

/***************************************************************************
* Part 3 : implementation of all cases
***************************************************************************/

template<typename Derived1, typename Derived2,
         int Vectorization = ei_assign_traits<Derived1, Derived2>::Vectorization,
         int Unrolling = ei_assign_traits<Derived1, Derived2>::Unrolling>
struct ei_assign_impl;

/***********************
*** No vectorization ***
***********************/

template<typename Derived1, typename Derived2>
struct ei_assign_impl<Derived1, Derived2, NoVectorization, NoUnrolling>
{
  inline static void run(Derived1 &dst, const Derived2 &src)
  {
    const int innerSize = dst.innerSize();
    const int outerSize = dst.outerSize();
    for(int j = 0; j < outerSize; ++j)
      for(int i = 0; i < innerSize; ++i)
      {
        if(int(Derived1::Flags)&RowMajorBit)
          dst.copyCoeff(j, i, src);
        else
          dst.copyCoeff(i, j, src);
      }
  }
};

template<typename Derived1, typename Derived2>
struct ei_assign_impl<Derived1, Derived2, NoVectorization, CompleteUnrolling>
{
  EIGEN_STRONG_INLINE static void run(Derived1 &dst, const Derived2 &src)
  {
    ei_assign_novec_CompleteUnrolling<Derived1, Derived2, 0, Derived1::SizeAtCompileTime>
      ::run(dst, src);
  }
};

template<typename Derived1, typename Derived2>
struct ei_assign_impl<Derived1, Derived2, NoVectorization, InnerUnrolling>
{
  EIGEN_STRONG_INLINE static void run(Derived1 &dst, const Derived2 &src)
  {
    const bool rowMajor = int(Derived1::Flags)&RowMajorBit;
    const int innerSize = rowMajor ? Derived1::ColsAtCompileTime : Derived1::RowsAtCompileTime;
    const int outerSize = dst.outerSize();
    for(int j = 0; j < outerSize; ++j)
      ei_assign_novec_InnerUnrolling<Derived1, Derived2, 0, innerSize>
        ::run(dst, src, j);
  }
};

/**************************
*** Inner vectorization ***
**************************/

template<typename Derived1, typename Derived2>
struct ei_assign_impl<Derived1, Derived2, InnerVectorization, NoUnrolling>
{
  inline static void run(Derived1 &dst, const Derived2 &src)
  {
    const int innerSize = dst.innerSize();
    const int outerSize = dst.outerSize();
    const int packetSize = ei_packet_traits<typename Derived1::Scalar>::size;
    for(int j = 0; j < outerSize; ++j)
      for(int i = 0; i < innerSize; i+=packetSize)
      {
        if(int(Derived1::Flags)&RowMajorBit)
          dst.template copyPacket<Derived2, Aligned, Aligned>(j, i, src);
        else
          dst.template copyPacket<Derived2, Aligned, Aligned>(i, j, src);
      }
  }
};

template<typename Derived1, typename Derived2>
struct ei_assign_impl<Derived1, Derived2, InnerVectorization, CompleteUnrolling>
{
  EIGEN_STRONG_INLINE static void run(Derived1 &dst, const Derived2 &src)
  {
    ei_assign_innervec_CompleteUnrolling<Derived1, Derived2, 0, Derived1::SizeAtCompileTime>
      ::run(dst, src);
  }
};

template<typename Derived1, typename Derived2>
struct ei_assign_impl<Derived1, Derived2, InnerVectorization, InnerUnrolling>
{
  EIGEN_STRONG_INLINE static void run(Derived1 &dst, const Derived2 &src)
  {
    const bool rowMajor = int(Derived1::Flags)&RowMajorBit;
    const int innerSize = rowMajor ? Derived1::ColsAtCompileTime : Derived1::RowsAtCompileTime;
    const int outerSize = dst.outerSize();
    for(int j = 0; j < outerSize; ++j)
      ei_assign_innervec_InnerUnrolling<Derived1, Derived2, 0, innerSize>
        ::run(dst, src, j);
  }
};

/***************************
*** Linear vectorization ***
***************************/

template<typename Derived1, typename Derived2>
struct ei_assign_impl<Derived1, Derived2, LinearVectorization, NoUnrolling>
{
  inline static void run(Derived1 &dst, const Derived2 &src)
  {
    const int size = dst.size();
    const int packetSize = ei_packet_traits<typename Derived1::Scalar>::size;
    const int alignedStart = ei_assign_traits<Derived1,Derived2>::DstIsAligned ? 0
                           : ei_alignmentOffset(&dst.coeffRef(0), size);
    const int alignedEnd = alignedStart + ((size-alignedStart)/packetSize)*packetSize;

    for(int index = 0; index < alignedStart; ++index)
      dst.copyCoeff(index, src);

    for(int index = alignedStart; index < alignedEnd; index += packetSize)
    {
      dst.template copyPacket<Derived2, Aligned, ei_assign_traits<Derived1,Derived2>::SrcAlignment>(index, src);
    }

    for(int index = alignedEnd; index < size; ++index)
      dst.copyCoeff(index, src);
  }
};

template<typename Derived1, typename Derived2>
struct ei_assign_impl<Derived1, Derived2, LinearVectorization, CompleteUnrolling>
{
  EIGEN_STRONG_INLINE static void run(Derived1 &dst, const Derived2 &src)
  {
    const int size = Derived1::SizeAtCompileTime;
    const int packetSize = ei_packet_traits<typename Derived1::Scalar>::size;
    const int alignedSize = (size/packetSize)*packetSize;

    ei_assign_innervec_CompleteUnrolling<Derived1, Derived2, 0, alignedSize>::run(dst, src);
    ei_assign_novec_CompleteUnrolling<Derived1, Derived2, alignedSize, size>::run(dst, src);
  }
};

/**************************
*** Slice vectorization ***
***************************/

template<typename Derived1, typename Derived2>
struct ei_assign_impl<Derived1, Derived2, SliceVectorization, NoUnrolling>
{
  inline static void run(Derived1 &dst, const Derived2 &src)
  {
    const int packetSize = ei_packet_traits<typename Derived1::Scalar>::size;
    const int packetAlignedMask = packetSize - 1;
    const int innerSize = dst.innerSize();
    const int outerSize = dst.outerSize();
    const int alignedStep = (packetSize - dst.stride() % packetSize) & packetAlignedMask;
    int alignedStart = ei_assign_traits<Derived1,Derived2>::DstIsAligned ? 0
                     : ei_alignmentOffset(&dst.coeffRef(0), innerSize);

    for(int i = 0; i < outerSize; ++i)
    {
      const int alignedEnd = alignedStart + ((innerSize-alignedStart) & ~packetAlignedMask);

      // do the non-vectorizable part of the assignment
      for (int index = 0; index<alignedStart ; ++index)
      {
        if(Derived1::Flags&RowMajorBit)
          dst.copyCoeff(i, index, src);
        else
          dst.copyCoeff(index, i, src);
      }

      // do the vectorizable part of the assignment
      for (int index = alignedStart; index<alignedEnd; index+=packetSize)
      {
        if(Derived1::Flags&RowMajorBit)
          dst.template copyPacket<Derived2, Aligned, Unaligned>(i, index, src);
        else
          dst.template copyPacket<Derived2, Aligned, Unaligned>(index, i, src);
      }

      // do the non-vectorizable part of the assignment
      for (int index = alignedEnd; index<innerSize ; ++index)
      {
        if(Derived1::Flags&RowMajorBit)
          dst.copyCoeff(i, index, src);
        else
          dst.copyCoeff(index, i, src);
      }

      alignedStart = std::min<int>((alignedStart+alignedStep)%packetSize, innerSize);
    }
  }
};

/***************************************************************************
* Part 4 : implementation of MatrixBase methods
***************************************************************************/

template<typename Derived>
template<typename OtherDerived>
EIGEN_STRONG_INLINE Derived& MatrixBase<Derived>
  ::lazyAssign(const MatrixBase<OtherDerived>& other)
{
  EIGEN_STATIC_ASSERT_SAME_MATRIX_SIZE(Derived,OtherDerived)
  ei_assert(rows() == other.rows() && cols() == other.cols());
  ei_assign_impl<Derived, OtherDerived>::run(derived(),other.derived());
  return derived();
}

template<typename Derived, typename OtherDerived,
         bool EvalBeforeAssigning = (int(OtherDerived::Flags) & EvalBeforeAssigningBit) != 0,
         bool NeedToTranspose = Derived::IsVectorAtCompileTime
                && OtherDerived::IsVectorAtCompileTime
                && int(Derived::RowsAtCompileTime) == int(OtherDerived::ColsAtCompileTime)
                && int(Derived::ColsAtCompileTime) == int(OtherDerived::RowsAtCompileTime)
                && int(Derived::SizeAtCompileTime) != 1>
struct ei_assign_selector;

template<typename Derived, typename OtherDerived>
struct ei_assign_selector<Derived,OtherDerived,false,false> {
  EIGEN_STRONG_INLINE static Derived& run(Derived& dst, const OtherDerived& other) { return dst.lazyAssign(other.derived()); }
};
template<typename Derived, typename OtherDerived>
struct ei_assign_selector<Derived,OtherDerived,true,false> {
  EIGEN_STRONG_INLINE static Derived& run(Derived& dst, const OtherDerived& other) { return dst.lazyAssign(other.eval()); }
};
template<typename Derived, typename OtherDerived>
struct ei_assign_selector<Derived,OtherDerived,false,true> {
  EIGEN_STRONG_INLINE static Derived& run(Derived& dst, const OtherDerived& other) { return dst.lazyAssign(other.transpose()); }
};
template<typename Derived, typename OtherDerived>
struct ei_assign_selector<Derived,OtherDerived,true,true> {
  EIGEN_STRONG_INLINE static Derived& run(Derived& dst, const OtherDerived& other) { return dst.lazyAssign(other.transpose().eval()); }
};

template<typename Derived>
template<typename OtherDerived>
EIGEN_STRONG_INLINE Derived& MatrixBase<Derived>
  ::operator=(const MatrixBase<OtherDerived>& other)
{
  EIGEN_STATIC_ASSERT((ei_is_same_type<Scalar, typename OtherDerived::Scalar>::ret),
    YOU_MIXED_DIFFERENT_NUMERIC_TYPES__YOU_NEED_TO_USE_THE_CAST_METHOD_OF_MATRIXBASE_TO_CAST_NUMERIC_TYPES_EXPLICITLY)
  return ei_assign_selector<Derived,OtherDerived>::run(derived(), other.derived());
}

#endif // EIGEN_ASSIGN_H