* fix multiple temporary copies for coeff based products

* introduce a lazy product version of the coefficient based implementation
  => flagged is not used anymore
  => small outer product are now lazy by default (aliasing is really unlikely for outer products)

Eigen/Core

@@ -205,7 +205,7 @@ struct Dense {};
 #include "src/Core/TriangularMatrix.h"
 #include "src/Core/SelfAdjointView.h"
 #include "src/Core/SolveTriangular.h"
-#include "src/Core/products/GeneralUnrolled.h"
+#include "src/Core/products/CoeffBasedProduct.h"
 #include "src/Core/products/GeneralBlockPanelKernel.h"
 #include "src/Core/products/GeneralMatrixVector.h"
 #include "src/Core/products/GeneralMatrixMatrix.h"

Eigen/src/Core/NoAlias.h

@@ -70,13 +70,13 @@ class NoAlias
     EIGEN_STRONG_INLINE ExpressionType& operator-=(const ProductBase<ProductDerived, Lhs,Rhs>& other)
     { other.derived().subTo(m_expression); return m_expression; }
 
-    template<typename Lhs, typename Rhs>
+    template<typename Lhs, typename Rhs, int NestingFlags>
-    EIGEN_STRONG_INLINE ExpressionType& operator+=(const GeneralProduct<Lhs,Rhs,CoeffBasedProduct>& other)
+    EIGEN_STRONG_INLINE ExpressionType& operator+=(const CoeffBasedProduct<Lhs,Rhs,NestingFlags>& other)
-    { return m_expression.derived() += other.template flagged<0,EvalBeforeAssigningBit|EvalBeforeNestingBit>(); }
+    { return m_expression.derived() += CoeffBasedProduct<Lhs,Rhs,0>(other.lhs(), other.rhs()); }
 
-    template<typename Lhs, typename Rhs>
+    template<typename Lhs, typename Rhs, int NestingFlags>
-    EIGEN_STRONG_INLINE ExpressionType& operator-=(const GeneralProduct<Lhs,Rhs,CoeffBasedProduct>& other)
+    EIGEN_STRONG_INLINE ExpressionType& operator-=(const CoeffBasedProduct<Lhs,Rhs,NestingFlags>& other)
-    { return m_expression.derived() -= other.template flagged<0,EvalBeforeAssigningBit|EvalBeforeNestingBit>(); }
+    { return m_expression.derived() -= CoeffBasedProduct<Lhs,Rhs,0>(other.lhs(), other.rhs()); }
 #endif
 
   protected:

Eigen/src/Core/Product.h

@@ -87,12 +87,12 @@ public:
 template<int Rows, int Cols>  struct ei_product_type_selector<Rows, Cols, 1>      { enum { ret = OuterProduct }; };
 template<int Depth>           struct ei_product_type_selector<1,    1,    Depth>  { enum { ret = InnerProduct }; };
 template<>                    struct ei_product_type_selector<1,    1,    1>      { enum { ret = InnerProduct }; };
-template<>                    struct ei_product_type_selector<Small,1,    Small>  { enum { ret = CoeffBasedProduct }; };
+template<>                    struct ei_product_type_selector<Small,1,    Small>  { enum { ret = CoeffBasedProductMode }; };
-template<>                    struct ei_product_type_selector<1,    Small,Small>  { enum { ret = CoeffBasedProduct }; };
+template<>                    struct ei_product_type_selector<1,    Small,Small>  { enum { ret = CoeffBasedProductMode }; };
-template<>                    struct ei_product_type_selector<Small,Small,Small>  { enum { ret = CoeffBasedProduct }; };
+template<>                    struct ei_product_type_selector<Small,Small,Small>  { enum { ret = CoeffBasedProductMode }; };
-template<>                    struct ei_product_type_selector<Small, Small, 1>    { enum { ret = CoeffBasedProduct }; };
+template<>                    struct ei_product_type_selector<Small, Small, 1>    { enum { ret = LazyCoeffBasedProductMode }; };
-template<>                    struct ei_product_type_selector<Small, Large, 1>    { enum { ret = CoeffBasedProduct }; };
+template<>                    struct ei_product_type_selector<Small, Large, 1>    { enum { ret = LazyCoeffBasedProductMode }; };
-template<>                    struct ei_product_type_selector<Large, Small, 1>    { enum { ret = CoeffBasedProduct }; };
+template<>                    struct ei_product_type_selector<Large, Small, 1>    { enum { ret = LazyCoeffBasedProductMode }; };
 template<>                    struct ei_product_type_selector<1,    Large,Small>  { enum { ret = GemvProduct }; };
 template<>                    struct ei_product_type_selector<1,    Large,Large>  { enum { ret = GemvProduct }; };
 template<>                    struct ei_product_type_selector<1,    Small,Large>  { enum { ret = GemvProduct }; };
@@ -134,11 +134,19 @@ struct ProductReturnType
 };
 
 template<typename Lhs, typename Rhs>
-struct ProductReturnType<Lhs,Rhs,CoeffBasedProduct>
+struct ProductReturnType<Lhs,Rhs,CoeffBasedProductMode>
 {
   typedef typename ei_nested<Lhs, Rhs::ColsAtCompileTime, typename ei_plain_matrix_type<Lhs>::type >::type LhsNested;
   typedef typename ei_nested<Rhs, Lhs::RowsAtCompileTime, typename ei_plain_matrix_type<Rhs>::type >::type RhsNested;
-  typedef GeneralProduct<LhsNested, RhsNested, CoeffBasedProduct> Type;
+  typedef CoeffBasedProduct<LhsNested, RhsNested, EvalBeforeAssigningBit | EvalBeforeNestingBit> Type;
+};
+
+template<typename Lhs, typename Rhs>
+struct ProductReturnType<Lhs,Rhs,LazyCoeffBasedProductMode>
+{
+  typedef typename ei_nested<Lhs, Rhs::ColsAtCompileTime, typename ei_plain_matrix_type<Lhs>::type >::type LhsNested;
+  typedef typename ei_nested<Rhs, Lhs::RowsAtCompileTime, typename ei_plain_matrix_type<Rhs>::type >::type RhsNested;
+  typedef CoeffBasedProduct<LhsNested, RhsNested, 0> Type;
 };
 
 

Eigen/src/Core/ProductBase.h

@@ -83,8 +83,7 @@ class ProductBase : public MatrixBase<Derived>
     typedef typename RhsBlasTraits::DirectLinearAccessType ActualRhsType;
     typedef typename ei_cleantype<ActualRhsType>::type _ActualRhsType;
 
-    typedef typename ProductReturnType<Lhs,Rhs,CoeffBasedProduct>::Type CoeffBaseProductType;
+    typedef typename ProductReturnType<Lhs,Rhs,LazyCoeffBasedProductMode>::Type LazyCoeffBaseProductType;
-    typedef Flagged<CoeffBaseProductType,0,EvalBeforeNestingBit> LazyCoeffBaseProductType;
   public:
 
     typedef typename Base::PlainMatrixType PlainMatrixType;
@@ -112,31 +111,28 @@ class ProductBase : public MatrixBase<Derived>
     template<typename Dest>
     inline void scaleAndAddTo(Dest& dst,Scalar alpha) const { derived().scaleAndAddTo(dst,alpha); }
 
-    EIGEN_DEPRECATED const Flagged<ProductBase, 0, EvalBeforeAssigningBit> lazy() const
-    { return *this; }
-
     const _LhsNested& lhs() const { return m_lhs; }
     const _RhsNested& rhs() const { return m_rhs; }
 
     const Diagonal<LazyCoeffBaseProductType,0> diagonal() const
-    { return Diagonal<LazyCoeffBaseProductType,0>(CoeffBaseProductType(m_lhs, m_rhs)); }
+    { return LazyCoeffBaseProductType(m_lhs, m_rhs); }
 
     Diagonal<LazyCoeffBaseProductType,0> diagonal()
-    { return Diagonal<LazyCoeffBaseProductType,0>(CoeffBaseProductType(m_lhs, m_rhs)); }
+    { return LazyCoeffBaseProductType(m_lhs, m_rhs); }
 
     template<int Index>
     const Diagonal<LazyCoeffBaseProductType,Index> diagonal() const
-    { return Diagonal<LazyCoeffBaseProductType,Index>(CoeffBaseProductType(m_lhs, m_rhs)); }
+    { return LazyCoeffBaseProductType(m_lhs, m_rhs); }
 
     template<int Index>
     Diagonal<LazyCoeffBaseProductType,Index> diagonal()
-    { return Diagonal<LazyCoeffBaseProductType,Index>(CoeffBaseProductType(m_lhs, m_rhs)); }
+    { return LazyCoeffBaseProductType(m_lhs, m_rhs); }
 
     const Diagonal<LazyCoeffBaseProductType,Dynamic> diagonal(int index) const
-    { return Diagonal<LazyCoeffBaseProductType,Dynamic>(LazyCoeffBaseProductType(CoeffBaseProductType(m_lhs, m_rhs))).diagonal(index); }
+    { return LazyCoeffBaseProductType(m_lhs, m_rhs).diagonal(index); }
 
     Diagonal<LazyCoeffBaseProductType,Dynamic> diagonal(int index)
-    { return Diagonal<LazyCoeffBaseProductType,Dynamic>(LazyCoeffBaseProductType(CoeffBaseProductType(m_lhs, m_rhs))).diagonal(index); }
+    { return LazyCoeffBaseProductType(m_lhs, m_rhs).diagonal(index); }
 
     // Implicit convertion to the nested type (trigger the evaluation of the product)
     operator const PlainMatrixType& () const

Eigen/src/Core/products/CoeffBasedProduct.h

@@ -23,11 +23,14 @@
 // License and a copy of the GNU General Public License along with
 // Eigen. If not, see <http://www.gnu.org/licenses/>.
 
-#ifndef EIGEN_GENERAL_UNROLLED_PRODUCT_H
+#ifndef EIGEN_COEFFBASED_PRODUCT_H
-#define EIGEN_GENERAL_UNROLLED_PRODUCT_H
+#define EIGEN_COEFFBASED_PRODUCT_H
 
 /*********************************************************************************
-*  Specialization of GeneralProduct<> for products with small fixed sizes
+*  Coefficient based product implementation.
+*  It is designed for the following use cases:
+*  - small fixed sizes
+*  - lazy products
 *********************************************************************************/
 
 /* Since the all the dimensions of the product are small, here we can rely
@@ -42,8 +45,8 @@ struct ei_product_coeff_impl;
 template<int StorageOrder, int Index, typename Lhs, typename Rhs, typename PacketScalar, int LoadMode>
 struct ei_product_packet_impl;
 
-template<typename LhsNested, typename RhsNested>
+template<typename LhsNested, typename RhsNested, int NestingFlags>
-struct ei_traits<GeneralProduct<LhsNested,RhsNested,CoeffBasedProduct> >
+struct ei_traits<CoeffBasedProduct<LhsNested,RhsNested,NestingFlags> >
 {
   typedef DenseStorageMatrix DenseStorageType;
   typedef typename ei_cleantype<LhsNested>::type _LhsNested;
@@ -79,14 +82,13 @@ struct ei_traits<GeneralProduct<LhsNested,RhsNested,CoeffBasedProduct> >
       RemovedBits = ~(EvalToRowMajor ? 0 : RowMajorBit),
 
       Flags = ((unsigned int)(LhsFlags | RhsFlags) & HereditaryBits & RemovedBits)
-            | EvalBeforeAssigningBit
+            | NestingFlags
-            | EvalBeforeNestingBit
             | (CanVectorizeLhs || CanVectorizeRhs ? PacketAccessBit : 0)
             | (LhsFlags & RhsFlags & AlignedBit),
 
-      CoeffReadCost = InnerSize == Dynamic ? Dynamic
+      CoeffReadCost = 1000,//InnerSize == Dynamic ? Dynamic
-                    : InnerSize * (NumTraits<Scalar>::MulCost + LhsCoeffReadCost + RhsCoeffReadCost)
+//                     : InnerSize * (NumTraits<Scalar>::MulCost + LhsCoeffReadCost + RhsCoeffReadCost)
-                      + (InnerSize - 1) * NumTraits<Scalar>::AddCost,
+//                       + (InnerSize - 1) * NumTraits<Scalar>::AddCost,
 
       /* CanVectorizeInner deserves special explanation. It does not affect the product flags. It is not used outside
       * of Product. If the Product itself is not a packet-access expression, there is still a chance that the inner
@@ -98,25 +100,27 @@ struct ei_traits<GeneralProduct<LhsNested,RhsNested,CoeffBasedProduct> >
     };
 };
 
-template<typename LhsNested, typename RhsNested> class GeneralProduct<LhsNested,RhsNested,CoeffBasedProduct>
+template<typename LhsNested, typename RhsNested, int NestingFlags>
+class CoeffBasedProduct
   : ei_no_assignment_operator,
-    public MatrixBase<GeneralProduct<LhsNested, RhsNested, CoeffBasedProduct> >
+    public MatrixBase<CoeffBasedProduct<LhsNested, RhsNested, NestingFlags> >
 {
   public:
 
-    typedef MatrixBase<GeneralProduct> Base;
+    typedef MatrixBase<CoeffBasedProduct> Base;
-    EIGEN_DENSE_PUBLIC_INTERFACE(GeneralProduct)
+    EIGEN_DENSE_PUBLIC_INTERFACE(CoeffBasedProduct)
+    typedef typename Base::PlainMatrixType PlainMatrixType;
 
   private:
 
-    typedef typename ei_traits<GeneralProduct>::_LhsNested _LhsNested;
+    typedef typename ei_traits<CoeffBasedProduct>::_LhsNested _LhsNested;
-    typedef typename ei_traits<GeneralProduct>::_RhsNested _RhsNested;
+    typedef typename ei_traits<CoeffBasedProduct>::_RhsNested _RhsNested;
 
     enum {
       PacketSize = ei_packet_traits<Scalar>::size,
-      InnerSize  = ei_traits<GeneralProduct>::InnerSize,
+      InnerSize  = ei_traits<CoeffBasedProduct>::InnerSize,
       Unroll = CoeffReadCost <= EIGEN_UNROLLING_LIMIT,
-      CanVectorizeInner = ei_traits<GeneralProduct>::CanVectorizeInner
+      CanVectorizeInner = ei_traits<CoeffBasedProduct>::CanVectorizeInner
     };
 
     typedef ei_product_coeff_impl<CanVectorizeInner ? InnerVectorizedTraversal : DefaultTraversal,
@@ -126,7 +130,7 @@ template<typename LhsNested, typename RhsNested> class GeneralProduct<LhsNested,
   public:
 
     template<typename Lhs, typename Rhs>
-    inline GeneralProduct(const Lhs& lhs, const Rhs& rhs)
+    inline CoeffBasedProduct(const Lhs& lhs, const Rhs& rhs)
       : m_lhs(lhs), m_rhs(rhs)
     {
       // we don't allow taking products of matrices of different real types, as that wouldn't be vectorizable.
@@ -171,11 +175,27 @@ template<typename LhsNested, typename RhsNested> class GeneralProduct<LhsNested,
       return res;
     }
 
+    // Implicit convertion to the nested type (trigger the evaluation of the product)
+    operator const PlainMatrixType& () const
+    {
+      m_result = *this;
+      return m_result;
+    }
+
   protected:
     const LhsNested m_lhs;
     const RhsNested m_rhs;
+
+    mutable PlainMatrixType m_result;
 };
 
+// here we need to overload the nested rule for products
+// such that the nested type is a const reference to a plain matrix
+template<typename Lhs, typename Rhs, int N, typename PlainMatrixType>
+struct ei_nested<CoeffBasedProduct<Lhs,Rhs,EvalBeforeNestingBit|EvalBeforeAssigningBit>, N, PlainMatrixType>
+{
+  typedef PlainMatrixType const& type;
+};
 
 /***************************************************************************
 * Normal product .coeff() implementation (with meta-unrolling)
@@ -386,4 +406,4 @@ struct ei_product_packet_impl<ColMajor, Dynamic, Lhs, Rhs, PacketScalar, LoadMod
   }
 };
 
-#endif // EIGEN_GENERAL_UNROLLED_PRODUCT_H
+#endif // EIGEN_COEFFBASED_PRODUCT_H

Eigen/src/Core/util/Constants.h

@@ -269,6 +269,6 @@ namespace Architecture
 enum DenseStorageMatrix {};
 enum DenseStorageArray {};
 
-enum { OuterProduct, InnerProduct, CoeffBasedProduct, GemvProduct, GemmProduct };
+enum { CoeffBasedProductMode, LazyCoeffBasedProductMode, OuterProduct, InnerProduct, GemvProduct, GemmProduct };
 
 #endif // EIGEN_CONSTANTS_H

Eigen/src/Core/util/ForwardDeclarations.h

@@ -52,6 +52,7 @@ template<typename BinaryOp,  typename Lhs, typename Rhs>  class CwiseBinaryOp;
 template<typename BinOp,     typename MatrixType>         class SelfCwiseBinaryOp;
 template<typename Derived,   typename Lhs, typename Rhs>  class ProductBase;
 template<typename Lhs, typename Rhs, int Mode>            class GeneralProduct;
+template<typename Lhs, typename Rhs, int NestingFlags>    class CoeffBasedProduct;
 
 template<typename Derived> class DiagonalBase;
 template<typename _DiagonalVectorType> class DiagonalWrapper;

Eigen/src/Core/util/StaticAssert.h

@@ -61,6 +61,7 @@
         THIS_METHOD_IS_ONLY_FOR_VECTORS_OF_A_SPECIFIC_SIZE,
         THIS_METHOD_IS_ONLY_FOR_MATRICES_OF_A_SPECIFIC_SIZE,
         YOU_MADE_A_PROGRAMMING_MISTAKE,
+        EIGEN_INTERNAL_COMPILATION_ERROR_OR_YOU_MADE_A_PROGRAMMING_MISTAKE,
         YOU_CALLED_A_FIXED_SIZE_METHOD_ON_A_DYNAMIC_SIZE_MATRIX_OR_VECTOR,
         YOU_CALLED_A_DYNAMIC_SIZE_METHOD_ON_A_FIXED_SIZE_MATRIX_OR_VECTOR,
         UNALIGNED_LOAD_AND_STORE_OPERATIONS_UNIMPLEMENTED_ON_ALTIVEC,