From d43f737b4ad52e84a3b4d954d9bfb4c40cf9e819 Mon Sep 17 00:00:00 2001
From: Benoit Steiner <benoit.steiner.goog@gmail.com>
Date: Thu, 4 Sep 2014 20:02:28 -0700
Subject: Added support for evaluation of tensor shuffling operations as
 lvalues

---
 .../Eigen/CXX11/src/Tensor/TensorShuffling.h       | 104 ++++++++++++++++-----
 1 file changed, 83 insertions(+), 21 deletions(-)

(limited to 'unsupported/Eigen/CXX11/src/Tensor/TensorShuffling.h')

diff --git a/unsupported/Eigen/CXX11/src/Tensor/TensorShuffling.h b/unsupported/Eigen/CXX11/src/Tensor/TensorShuffling.h
index 4dfc99203..f7e7fc107 100644
--- a/unsupported/Eigen/CXX11/src/Tensor/TensorShuffling.h
+++ b/unsupported/Eigen/CXX11/src/Tensor/TensorShuffling.h
@@ -48,7 +48,7 @@ struct nested<TensorShufflingOp<Shuffle, XprType>, 1, typename eval<TensorShuffl
 
 
 template<typename Shuffle, typename XprType>
-class TensorShufflingOp : public TensorBase<TensorShufflingOp<Shuffle, XprType>, WriteAccessors>
+class TensorShufflingOp : public TensorBase<TensorShufflingOp<Shuffle, XprType> >
 {
   public:
   typedef typename Eigen::internal::traits<TensorShufflingOp>::Scalar Scalar;
@@ -94,33 +94,38 @@ struct TensorEvaluator<const TensorShufflingOp<Shuffle, ArgType>, Device>
   typedef typename XprType::Index Index;
   static const int NumDims = internal::array_size<typename TensorEvaluator<ArgType, Device>::Dimensions>::value;
   typedef DSizes<Index, NumDims> Dimensions;
+  typedef typename XprType::Scalar Scalar;
 
   enum {
-    IsAligned = /*TensorEvaluator<ArgType, Device>::IsAligned*/false,
-    PacketAccess = /*TensorEvaluator<ArgType, Device>::PacketAccess*/false,
+    IsAligned = true,
+    PacketAccess = (internal::packet_traits<Scalar>::size > 1),
   };
 
   EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE TensorEvaluator(const XprType& op, const Device& device)
-      : m_impl(op.expression(), device), m_shuffle(op.shuffle())
+      : m_impl(op.expression(), device)
   {
     const typename TensorEvaluator<ArgType, Device>::Dimensions& input_dims = m_impl.dimensions();
+    const Shuffle& shuffle = op.shuffle();
     for (int i = 0; i < NumDims; ++i) {
-      m_dimensions[i] = input_dims[m_shuffle[i]];
+      m_dimensions[i] = input_dims[shuffle[i]];
     }
 
+    array<Index, NumDims> inputStrides;
+
     for (int i = 0; i < NumDims; ++i) {
       if (i > 0) {
-        m_inputStrides[i] = m_inputStrides[i-1] * input_dims[i-1];
+        inputStrides[i] = inputStrides[i-1] * input_dims[i-1];
         m_outputStrides[i] = m_outputStrides[i-1] * m_dimensions[i-1];
       } else {
-        m_inputStrides[0] = 1;
+        inputStrides[0] = 1;
         m_outputStrides[0] = 1;
       }
     }
+    for (int i = 0; i < NumDims; ++i) {
+      m_inputStrides[i] = inputStrides[shuffle[i]];
+    }
   }
 
-  //  typedef typename XprType::Index Index;
-  typedef typename XprType::Scalar Scalar;
   typedef typename XprType::CoeffReturnType CoeffReturnType;
   typedef typename XprType::PacketReturnType PacketReturnType;
 
@@ -136,33 +141,90 @@ struct TensorEvaluator<const TensorShufflingOp<Shuffle, ArgType>, Device>
 
   EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE CoeffReturnType coeff(Index index) const
   {
-    Index inputIndex = 0;
-    for (int i = NumDims - 1; i > 0; --i) {
-      const Index idx = index / m_outputStrides[i];
-      inputIndex += idx * m_inputStrides[m_shuffle[i]];
-      index -= idx * m_outputStrides[i];
-    }
-    inputIndex += index * m_inputStrides[m_shuffle[0]];
-    return m_impl.coeff(inputIndex);
+    return m_impl.coeff(srcCoeff(index));
   }
 
-  /*  template<int LoadMode>
+  template<int LoadMode>
   EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE PacketReturnType packet(Index index) const
   {
-    return m_impl.template packet<LoadMode>(index);
-    }*/
+    const int packetSize = internal::unpacket_traits<PacketReturnType>::size;
+    EIGEN_STATIC_ASSERT(packetSize > 1, YOU_MADE_A_PROGRAMMING_MISTAKE)
+    eigen_assert(index+packetSize-1 < dimensions().TotalSize());
+
+    EIGEN_ALIGN_DEFAULT typename internal::remove_const<CoeffReturnType>::type values[packetSize];
+    for (int i = 0; i < packetSize; ++i) {
+      values[i] = coeff(index+i);
+    }
+    PacketReturnType rslt = internal::pload<PacketReturnType>(values);
+    return rslt;
+  }
 
   Scalar* data() const { return NULL; }
 
  protected:
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE Index srcCoeff(Index index) const
+  {
+    Index inputIndex = 0;
+    for (int i = NumDims - 1; i > 0; --i) {
+      const Index idx = index / m_outputStrides[i];
+      inputIndex += idx * m_inputStrides[i];
+      index -= idx * m_outputStrides[i];
+    }
+    return inputIndex + index * m_inputStrides[0];
+  }
+
   Dimensions m_dimensions;
-  Shuffle m_shuffle;
   array<Index, NumDims> m_outputStrides;
   array<Index, NumDims> m_inputStrides;
   TensorEvaluator<ArgType, Device> m_impl;
 };
 
 
+// Eval as lvalue
+template<typename Shuffle, typename ArgType, typename Device>
+struct TensorEvaluator<TensorShufflingOp<Shuffle, ArgType>, Device>
+    : public TensorEvaluator<const TensorShufflingOp<Shuffle, ArgType>, Device>
+{
+  typedef TensorEvaluator<const TensorShufflingOp<Shuffle, ArgType>, Device> Base;
+
+  typedef TensorShufflingOp<Shuffle, ArgType> XprType;
+  typedef typename XprType::Index Index;
+  static const int NumDims = internal::array_size<typename TensorEvaluator<ArgType, Device>::Dimensions>::value;
+  typedef DSizes<Index, NumDims> Dimensions;
+  typedef typename XprType::Scalar Scalar;
+
+  enum {
+    IsAligned = true,
+    PacketAccess = (internal::packet_traits<Scalar>::size > 1),
+  };
+
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE TensorEvaluator(const XprType& op, const Device& device)
+      : Base(op, device)
+  { }
+
+  typedef typename XprType::CoeffReturnType CoeffReturnType;
+  typedef typename XprType::PacketReturnType PacketReturnType;
+
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE CoeffReturnType& coeffRef(Index index)
+  {
+    return this->m_impl.coeffRef(this->srcCoeff(index));
+  }
+
+  template <int StoreMode> EIGEN_STRONG_INLINE
+  void writePacket(Index index, const PacketReturnType& x)
+  {
+    static const int packetSize = internal::unpacket_traits<PacketReturnType>::size;
+    EIGEN_STATIC_ASSERT(packetSize > 1, YOU_MADE_A_PROGRAMMING_MISTAKE)
+
+    EIGEN_ALIGN_DEFAULT typename internal::remove_const<CoeffReturnType>::type values[packetSize];
+    internal::pstore<CoeffReturnType, PacketReturnType>(values, x);
+    for (int i = 0; i < packetSize; ++i) {
+      this->coeffRef(index+i) = values[i];
+    }
+  }
+};
+
+
 } // end namespace Eigen
 
 #endif // EIGEN_CXX11_TENSOR_TENSOR_SHUFFLING_H
-- 
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