From 7caaf6453b7b1f58d953729380d596b2d9b27835 Mon Sep 17 00:00:00 2001
From: Benoit Steiner <benoit.steiner.goog@gmail.com>
Date: Wed, 1 Oct 2014 20:38:22 -0700
Subject: Added support for tensor reductions and concatenations

---
 .../Eigen/CXX11/src/Tensor/TensorConcatenation.h   | 217 +++++++++++++++++++++
 1 file changed, 217 insertions(+)
 create mode 100644 unsupported/Eigen/CXX11/src/Tensor/TensorConcatenation.h

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

diff --git a/unsupported/Eigen/CXX11/src/Tensor/TensorConcatenation.h b/unsupported/Eigen/CXX11/src/Tensor/TensorConcatenation.h
new file mode 100644
index 000000000..b8e43f484
--- /dev/null
+++ b/unsupported/Eigen/CXX11/src/Tensor/TensorConcatenation.h
@@ -0,0 +1,217 @@
+// This file is part of Eigen, a lightweight C++ template library
+// for linear algebra.
+//
+// Copyright (C) 2014 Benoit Steiner <benoit.steiner.goog@gmail.com>
+//
+// This Source Code Form is subject to the terms of the Mozilla
+// Public License v. 2.0. If a copy of the MPL was not distributed
+// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+#ifndef EIGEN_CXX11_TENSOR_TENSOR_CONCATENATION_H
+#define EIGEN_CXX11_TENSOR_TENSOR_CONCATENATION_H
+
+namespace Eigen {
+
+/** \class TensorConcatenationOp
+  * \ingroup CXX11_Tensor_Module
+  *
+  * \brief Tensor concatenation class.
+  *
+  *
+  */
+namespace internal {
+template<typename Axis, typename LhsXprType, typename RhsXprType>
+struct traits<TensorConcatenationOp<Axis, LhsXprType, RhsXprType> >
+{
+  // Type promotion to handle the case where the types of the lhs and the rhs are different.
+  typedef typename promote_storage_type<typename LhsXprType::Scalar,
+                                        typename RhsXprType::Scalar>::ret Scalar;
+  typedef typename packet_traits<Scalar>::type Packet;
+  typedef typename promote_storage_type<typename traits<LhsXprType>::StorageKind,
+                                        typename traits<RhsXprType>::StorageKind>::ret StorageKind;
+  typedef typename promote_index_type<typename traits<LhsXprType>::Index,
+                                      typename traits<RhsXprType>::Index>::type Index;
+  typedef typename LhsXprType::Nested LhsNested;
+  typedef typename RhsXprType::Nested RhsNested;
+  typedef typename remove_reference<LhsNested>::type _LhsNested;
+  typedef typename remove_reference<RhsNested>::type _RhsNested;
+  enum { Flags = 0 };
+};
+
+template<typename Axis, typename LhsXprType, typename RhsXprType>
+struct eval<TensorConcatenationOp<Axis, LhsXprType, RhsXprType>, Eigen::Dense>
+{
+  typedef const TensorConcatenationOp<Axis, LhsXprType, RhsXprType>& type;
+};
+
+template<typename Axis, typename LhsXprType, typename RhsXprType>
+struct nested<TensorConcatenationOp<Axis, LhsXprType, RhsXprType>, 1, typename eval<TensorConcatenationOp<Axis, LhsXprType, RhsXprType> >::type>
+{
+  typedef TensorConcatenationOp<Axis, LhsXprType, RhsXprType> type;
+};
+
+}  // end namespace internal
+
+
+template<typename Axis, typename LhsXprType, typename RhsXprType>
+class TensorConcatenationOp : public TensorBase<TensorConcatenationOp<Axis, LhsXprType, RhsXprType>, WriteAccessors>
+{
+  public:
+    typedef typename internal::traits<TensorConcatenationOp>::Scalar Scalar;
+    typedef typename internal::traits<TensorConcatenationOp>::Packet Packet;
+    typedef typename internal::traits<TensorConcatenationOp>::StorageKind StorageKind;
+    typedef typename internal::traits<TensorConcatenationOp>::Index Index;
+    typedef typename internal::nested<TensorConcatenationOp>::type Nested;
+    typedef typename internal::promote_storage_type<typename LhsXprType::CoeffReturnType,
+                                                    typename RhsXprType::CoeffReturnType>::ret CoeffReturnType;
+    typedef typename internal::promote_storage_type<typename LhsXprType::PacketReturnType,
+                                                    typename RhsXprType::PacketReturnType>::ret PacketReturnType;
+    typedef typename NumTraits<Scalar>::Real RealScalar;
+
+    EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE TensorConcatenationOp(const LhsXprType& lhs, const RhsXprType& rhs, Axis axis)
+        : m_lhs_xpr(lhs), m_rhs_xpr(rhs), m_axis(axis) {}
+
+    EIGEN_DEVICE_FUNC
+    const typename internal::remove_all<typename LhsXprType::Nested>::type&
+    lhsExpression() const { return m_lhs_xpr; }
+
+    EIGEN_DEVICE_FUNC
+    const typename internal::remove_all<typename RhsXprType::Nested>::type&
+    rhsExpression() const { return m_rhs_xpr; }
+
+    EIGEN_DEVICE_FUNC Axis axis() const { return m_axis; }
+
+  protected:
+    typename LhsXprType::Nested m_lhs_xpr;
+    typename RhsXprType::Nested m_rhs_xpr;
+    const Axis m_axis;
+};
+
+
+// Eval as rvalue
+template<typename Axis, typename LeftArgType, typename RightArgType, typename Device>
+struct TensorEvaluator<const TensorConcatenationOp<Axis, LeftArgType, RightArgType>, Device>
+{
+  typedef TensorConcatenationOp<Axis, LeftArgType, RightArgType> XprType;
+  typedef typename XprType::Index Index;
+  static const int NumDims = internal::array_size<typename TensorEvaluator<LeftArgType, Device>::Dimensions>::value;
+  static const int RightNumDims = internal::array_size<typename TensorEvaluator<RightArgType, Device>::Dimensions>::value;
+  typedef DSizes<Index, NumDims> Dimensions;
+  typedef typename XprType::Scalar Scalar;
+  typedef typename XprType::CoeffReturnType CoeffReturnType;
+  typedef typename XprType::PacketReturnType PacketReturnType;
+  enum {
+    IsAligned = false,
+    PacketAccess = TensorEvaluator<LeftArgType, Device>::PacketAccess & TensorEvaluator<RightArgType, Device>::PacketAccess,
+  };
+
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE TensorEvaluator(const XprType& op, const Device& device)
+    : m_leftImpl(op.lhsExpression(), device), m_rightImpl(op.rhsExpression(), device), m_axis(op.axis())
+  {
+    EIGEN_STATIC_ASSERT(NumDims == RightNumDims, YOU_MADE_A_PROGRAMMING_MISTAKE)
+    eigen_assert(0 <= m_axis && m_axis < NumDims);
+    const Dimensions& lhs_dims = m_leftImpl.dimensions();
+    const Dimensions& rhs_dims = m_rightImpl.dimensions();
+    int i = 0;
+    for (; i < m_axis; ++i) {
+      eigen_assert(lhs_dims[i] > 0);
+      eigen_assert(lhs_dims[i] == rhs_dims[i]);
+      m_dimensions[i] = lhs_dims[i];
+    }
+    eigen_assert(lhs_dims[i] > 0);  // Now i == m_axis.
+    eigen_assert(rhs_dims[i] > 0);
+    m_dimensions[i] = lhs_dims[i] + rhs_dims[i];
+    for (++i; i < NumDims; ++i) {
+      eigen_assert(lhs_dims[i] > 0);
+      eigen_assert(lhs_dims[i] == rhs_dims[i]);
+      m_dimensions[i] = lhs_dims[i];
+    }
+
+    m_leftStrides[0] = 1;
+    m_rightStrides[0] = 1;
+    m_outputStrides[0] = 1;
+    for (int i = 1; i < NumDims; ++i) {
+      m_leftStrides[i] = m_leftStrides[i-1] * lhs_dims[i-1];
+      m_rightStrides[i] = m_rightStrides[i-1] * rhs_dims[i-1];
+      m_outputStrides[i] = m_outputStrides[i-1] * m_dimensions[i-1];
+    }
+  }
+
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE const Dimensions& dimensions() const { return m_dimensions; }
+
+  // TODO(phli): Add short-circuit memcpy evaluation if underlying data are linear?
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE bool evalSubExprsIfNeeded(Scalar* data)
+  {
+    m_leftImpl.evalSubExprsIfNeeded(NULL);
+    m_rightImpl.evalSubExprsIfNeeded(NULL);
+    return true;
+  }
+
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE void cleanup()
+  {
+    m_leftImpl.cleanup();
+    m_rightImpl.cleanup();
+  }
+
+  // TODO(phli): attempt to speed this up. The integer divisions and modulo are slow.
+  // See CL/76180724 comments for more ideas.
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE CoeffReturnType coeff(Index index) const
+  {
+    // Collect dimension-wise indices (subs).
+    array<Index, NumDims> subs;
+    for (int i = NumDims - 1; i > 0; --i) {
+      subs[i] = index / m_outputStrides[i];
+      index -= subs[i] * m_outputStrides[i];
+    }
+    subs[0] = index;
+
+    const Dimensions& left_dims = m_leftImpl.dimensions();
+    if (subs[m_axis] < left_dims[m_axis]) {
+      Index left_index = subs[0];
+      for (int i = 1; i < NumDims; ++i) {
+        left_index += (subs[i] % left_dims[i]) * m_leftStrides[i];
+      }
+      return m_leftImpl.coeff(left_index);
+    } else {
+      subs[m_axis] -= left_dims[m_axis];
+      const Dimensions& right_dims = m_rightImpl.dimensions();
+      Index right_index = subs[0];
+      for (int i = 1; i < NumDims; ++i) {
+        right_index += (subs[i] % right_dims[i]) * m_rightStrides[i];
+      }
+      return m_rightImpl.coeff(right_index);
+    }
+  }
+
+  // TODO(phli): Add a real vectorization.
+  template<int LoadMode>
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE PacketReturnType packet(Index index) const
+  {
+    static 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 CoeffReturnType 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:
+    const Axis m_axis;
+    Dimensions m_dimensions;
+    array<Index, NumDims> m_outputStrides;
+    array<Index, NumDims> m_leftStrides;
+    array<Index, NumDims> m_rightStrides;
+    TensorEvaluator<LeftArgType, Device> m_leftImpl;
+    TensorEvaluator<RightArgType, Device> m_rightImpl;
+};
+
+
+} // end namespace Eigen
+
+#endif // EIGEN_CXX11_TENSOR_TENSOR_CONCATENATION_H
-- 
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