Enable vectorization with half-packets

4 files changed, 29 insertions, 5 deletions

diff --git a/Eigen/src/Core/AssignEvaluator.h b/Eigen/src/Core/AssignEvaluator.h
index 9dbf2c063..2b00d355b 100644
--- a/Eigen/src/Core/AssignEvaluator.h
+++ b/Eigen/src/Core/AssignEvaluator.h
@@ -29,8 +29,8 @@ struct copy_using_evaluator_traits
 {
   typedef typename DstEvaluator::XprType Dst;
   typedef typename Dst::Scalar DstScalar;
-  // TODO recursively find best packet size
-  typedef typename packet_traits<DstScalar>::type PacketType;
+  // TODO distinguish between linear traversal and inner-traversals
+  typedef typename find_best_packet<DstScalar,Dst::SizeAtCompileTime>::type PacketType; 
   
   enum {
     DstFlags = DstEvaluator::Flags,
@@ -55,7 +55,7 @@ private:
               : int(DstFlags)&RowMajorBit ? int(Dst::MaxColsAtCompileTime)
               : int(Dst::MaxRowsAtCompileTime),
     MaxSizeAtCompileTime = Dst::SizeAtCompileTime,
-    PacketSize = packet_traits<DstScalar>::size
+    PacketSize = unpacket_traits<PacketType>::size
   };
 
   enum {
diff --git a/Eigen/src/Core/DenseBase.h b/Eigen/src/Core/DenseBase.h
index 6051f01ac..005f68aa5 100644
--- a/Eigen/src/Core/DenseBase.h
+++ b/Eigen/src/Core/DenseBase.h
@@ -76,7 +76,6 @@ template<typename Derived> class DenseBase
       * It is an alias for the Scalar type */
     typedef Scalar value_type;
     
-    typedef typename internal::packet_traits<Scalar>::type PacketScalar;
     typedef typename NumTraits<Scalar>::Real RealScalar;
 
     typedef internal::special_scalar_op_base<Derived,typename internal::traits<Derived>::Scalar,
@@ -178,6 +177,8 @@ template<typename Derived> class DenseBase
       InnerStrideAtCompileTime = internal::inner_stride_at_compile_time<Derived>::ret,
       OuterStrideAtCompileTime = internal::outer_stride_at_compile_time<Derived>::ret
     };
+    
+    typedef typename internal::find_best_packet<Scalar,SizeAtCompileTime>::type PacketScalar;
 
     enum { IsPlainObjectBase = 0 };
     
diff --git a/Eigen/src/Core/Matrix.h b/Eigen/src/Core/Matrix.h
index b7c90ae16..7221d89a6 100644
--- a/Eigen/src/Core/Matrix.h
+++ b/Eigen/src/Core/Matrix.h
@@ -141,7 +141,8 @@ struct traits<Matrix<_Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols> >
 {
 private:
   // TODO find ideal packet size
-  typedef typename packet_traits<_Scalar>::type PacketScalar;
+  enum { size = internal::size_at_compile_time<_Rows,_Cols>::ret };
+  typedef typename find_best_packet<_Scalar,size>::type PacketScalar;
   enum {
       row_major_bit = _Options&RowMajor ? RowMajorBit : 0,
       is_dynamic_size_storage = _MaxRows==Dynamic || _MaxCols==Dynamic,
diff --git a/Eigen/src/Core/util/XprHelper.h b/Eigen/src/Core/util/XprHelper.h
index 2808dfd6c..f1520e4e2 100644
--- a/Eigen/src/Core/util/XprHelper.h
+++ b/Eigen/src/Core/util/XprHelper.h
@@ -126,6 +126,28 @@ template<typename T> struct unpacket_traits
   };
 };
 
+template<int Size, typename PacketType,
+         bool Stop = (Size%unpacket_traits<PacketType>::size)==0 || is_same<PacketType,typename unpacket_traits<PacketType>::half>::value>
+struct find_best_packet_helper;
+
+template< int Size, typename PacketType>
+struct find_best_packet_helper<Size,PacketType,true>
+{
+  typedef PacketType type;
+};
+
+template<int Size, typename PacketType>
+struct find_best_packet_helper<Size,PacketType,false>
+{
+  typedef typename find_best_packet_helper<Size,typename unpacket_traits<PacketType>::half>::type type;
+};
+
+template<typename T, int Size>
+struct find_best_packet
+{
+  typedef typename find_best_packet_helper<Size,typename packet_traits<T>::type>::type type;
+};
+
 #if EIGEN_MAX_STATIC_ALIGN_BYTES>0
 template<int ArrayBytes, int AlignmentBytes,
          bool Match     =  bool((ArrayBytes%AlignmentBytes)==0),