From d586686924c2783f56bd514c9365afeecc3e84f6 Mon Sep 17 00:00:00 2001
From: Gael Guennebaud <g.gael@free.fr>
Date: Wed, 30 Jan 2019 16:48:01 +0100
Subject: [PATCH] Workaround lack of support for arbitrary packet-type in
 Tensor by manually loading half/quarter packets in tensor contraction mapper.

---
 .../src/Tensor/TensorContractionMapper.h      | 29 +++++++++++++++++--
 1 file changed, 27 insertions(+), 2 deletions(-)

diff --git a/unsupported/Eigen/CXX11/src/Tensor/TensorContractionMapper.h b/unsupported/Eigen/CXX11/src/Tensor/TensorContractionMapper.h
index 64dfcd297..142492603 100644
--- a/unsupported/Eigen/CXX11/src/Tensor/TensorContractionMapper.h
+++ b/unsupported/Eigen/CXX11/src/Tensor/TensorContractionMapper.h
@@ -241,8 +241,10 @@ class BaseTensorContractionMapper : public SimpleTensorContractionMapper<Scalar,
   ParentMapper(tensor, nocontract_strides, ij_strides, contract_strides, k_strides) { }
 
   template <typename PacketT,int AlignmentType>
-  EIGEN_DEVICE_FUNC
-  EIGEN_STRONG_INLINE PacketT load(Index i, Index j) const {
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE
+  typename internal::enable_if<internal::unpacket_traits<PacketT>::size==packet_size,PacketT>::type
+  load(Index i, Index j) const
+  {
     // whole method makes column major assumption
 
     // don't need to add offsets for now (because operator handles that)
@@ -283,6 +285,29 @@ class BaseTensorContractionMapper : public SimpleTensorContractionMapper<Scalar,
     return pload<PacketT>(data);
   }
 
+  template <typename PacketT,int AlignmentType>
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE
+  typename internal::enable_if<internal::unpacket_traits<PacketT>::size!=packet_size,PacketT>::type
+  load(Index i, Index j) const
+  {
+    const Index requested_packet_size = internal::unpacket_traits<PacketT>::size;
+    EIGEN_ALIGN_MAX Scalar data[requested_packet_size];
+
+    const IndexPair<Index> indexPair = this->computeIndexPair(i, j, requested_packet_size - 1);
+    const Index first = indexPair.first;
+    const Index lastIdx = indexPair.second;
+
+    data[0] = this->m_tensor.coeff(first);
+    for (Index k = 1; k < requested_packet_size - 1; k += 2) {
+      const IndexPair<Index> internal_pair = this->computeIndexPair(i + k, j, 1);
+      data[k] = this->m_tensor.coeff(internal_pair.first);
+      data[k + 1] = this->m_tensor.coeff(internal_pair.second);
+    }
+    data[requested_packet_size - 1] = this->m_tensor.coeff(lastIdx);
+
+    return pload<PacketT>(data);
+  }
+
   template <typename PacketT,int AlignmentType>
   EIGEN_DEVICE_FUNC
   EIGEN_STRONG_INLINE PacketT loadPacket(Index i, Index j) const {