overload operartor* with a ProductBase such that "scalar * (mat * mat)" is optimized

as one could naturally expect

7 files changed, 70 insertions, 15 deletions

diff --git a/Eigen/src/Core/Product.h b/Eigen/src/Core/Product.h
index 18f14f75a..610d5c84a 100644
--- a/Eigen/src/Core/Product.h
+++ b/Eigen/src/Core/Product.h
@@ -153,7 +153,7 @@ class GeneralProduct<Lhs, Rhs, InnerProduct>
 
     GeneralProduct(const Lhs& lhs, const Rhs& rhs) : Base(lhs,rhs) {}
 
-    template<typename Dest> void addTo(Dest& dst, Scalar alpha) const
+    template<typename Dest> void scaleAndAddTo(Dest& dst, Scalar alpha) const
     {
       ei_assert(dst.rows()==1 && dst.cols()==1);
       dst.coeffRef(0,0) += alpha * (m_lhs.cwise()*m_rhs).sum();
@@ -179,7 +179,7 @@ class GeneralProduct<Lhs, Rhs, OuterProduct>
 
     GeneralProduct(const Lhs& lhs, const Rhs& rhs) : Base(lhs,rhs) {}
 
-    template<typename Dest> void addTo(Dest& dest, Scalar alpha) const
+    template<typename Dest> void scaleAndAddTo(Dest& dest, Scalar alpha) const
     {
       ei_outer_product_selector<Dest::Flags&RowMajorBit>::run(*this, dest, alpha);
     }
@@ -236,7 +236,7 @@ class GeneralProduct<Lhs, Rhs, GemvProduct>
     enum { Side = Lhs::IsVectorAtCompileTime ? OnTheLeft : OnTheRight };
     typedef typename ei_meta_if<int(Side)==OnTheRight,_LhsNested,_RhsNested>::ret MatrixType;
 
-    template<typename Dest> void addTo(Dest& dst, Scalar alpha) const
+    template<typename Dest> void scaleAndAddTo(Dest& dst, Scalar alpha) const
     {
       ei_assert(m_lhs.rows() == dst.rows() && m_rhs.cols() == dst.cols());
       ei_gemv_selector<Side,int(MatrixType::Flags)&RowMajorBit,
diff --git a/Eigen/src/Core/ProductBase.h b/Eigen/src/Core/ProductBase.h
index bae2302b3..0da046b1e 100644
--- a/Eigen/src/Core/ProductBase.h
+++ b/Eigen/src/Core/ProductBase.h
@@ -100,16 +100,16 @@ class ProductBase : public MatrixBase<Derived>
     inline int cols() const { return m_rhs.cols(); }
 
     template<typename Dest>
-    inline void evalTo(Dest& dst) const { dst.setZero(); addTo(dst,1); }
+    inline void evalTo(Dest& dst) const { dst.setZero(); scaleAndAddTo(dst,1); }
 
     template<typename Dest>
-    inline void addTo(Dest& dst) const { addTo(dst,1); }
+    inline void addTo(Dest& dst) const { scaleAndAddTo(dst,1); }
 
     template<typename Dest>
-    inline void subTo(Dest& dst) const { addTo(dst,-1); }
+    inline void subTo(Dest& dst) const { scaleAndAddTo(dst,-1); }
 
     template<typename Dest>
-    inline void addTo(Dest& dst,Scalar alpha) const { derived().addTo(dst,alpha); }
+    inline void scaleAndAddTo(Dest& dst,Scalar alpha) const { derived().scaleAndAddTo(dst,alpha); }
 
     PlainMatrixType eval() const
     {
@@ -141,13 +141,68 @@ class ProductBase : public MatrixBase<Derived>
     void coeffRef(int);
 };
 
+template<typename NestedProduct>
+class ScaledProduct;
+
+// Note that these two operator* functions are not defined as member
+// functions of ProductBase, because, otherwise we would have to
+// define all overloads defined in MatrixBase. Furthermore, Using
+// "using Base::operator*" would not work with MSVC.
+template<typename Derived,typename Lhs,typename Rhs>
+const ScaledProduct<Derived> operator*(const ProductBase<Derived,Lhs,Rhs>& prod, typename Derived::Scalar x)
+{ return ScaledProduct<Derived>(prod.derived(), x); }
+
+template<typename Derived,typename Lhs,typename Rhs>
+const ScaledProduct<Derived> operator*(typename Derived::Scalar x,const ProductBase<Derived,Lhs,Rhs>& prod)
+{ return ScaledProduct<Derived>(prod.derived(), x); }
+
+template<typename NestedProduct>
+struct ei_traits<ScaledProduct<NestedProduct> >
+ : ei_traits<ProductBase<ScaledProduct<NestedProduct>,
+                         typename NestedProduct::_LhsNested,
+                         typename NestedProduct::_RhsNested> >
+{};
+
+template<typename NestedProduct>
+class ScaledProduct
+  : public ProductBase<ScaledProduct<NestedProduct>,
+                       typename NestedProduct::_LhsNested,
+                       typename NestedProduct::_RhsNested>
+{
+  public:
+    typedef ProductBase<ScaledProduct<NestedProduct>,
+                       typename NestedProduct::_LhsNested,
+                       typename NestedProduct::_RhsNested> Base;
+    typedef typename Base::Scalar Scalar;
+//     EIGEN_PRODUCT_PUBLIC_INTERFACE(ScaledProduct)
+
+    ScaledProduct(const NestedProduct& prod, Scalar& x)
+    : Base(prod.lhs(),prod.rhs()), m_prod(prod), m_alpha(x) {}
+
+    template<typename Dest>
+    inline void evalTo(Dest& dst) const { dst.setZero(); scaleAndAddTo(dst,m_alpha); }
+
+    template<typename Dest>
+    inline void addTo(Dest& dst) const { scaleAndAddTo(dst,m_alpha); }
+
+    template<typename Dest>
+    inline void subTo(Dest& dst) const { scaleAndAddTo(dst,-m_alpha); }
+
+    template<typename Dest>
+    inline void scaleAndAddTo(Dest& dst,Scalar alpha) const { m_prod.derived().scaleAndAddTo(dst,alpha); }
+
+  protected:
+    const NestedProduct& m_prod;
+    Scalar m_alpha;
+};
+
 /** \internal
   * Overloaded to perform an efficient C = (A*B).lazy() */
 template<typename Derived>
 template<typename ProductDerived, typename Lhs, typename Rhs>
 Derived& MatrixBase<Derived>::lazyAssign(const ProductBase<ProductDerived, Lhs,Rhs>& other)
 {
-  other.evalTo(derived()); return derived();
+  other.derived().evalTo(derived()); return derived();
 }
 
 /** \internal
@@ -157,7 +212,7 @@ template<typename ProductDerived, typename Lhs, typename Rhs>
 Derived& MatrixBase<Derived>::operator+=(const Flagged<ProductBase<ProductDerived, Lhs,Rhs>, 0,
                                                        EvalBeforeNestingBit | EvalBeforeAssigningBit>& other)
 {
-  other._expression().addTo(derived()); return derived();
+  other._expression().derived().addTo(derived()); return derived();
 }
 
 /** \internal
@@ -167,7 +222,7 @@ template<typename ProductDerived, typename Lhs, typename Rhs>
 Derived& MatrixBase<Derived>::operator-=(const Flagged<ProductBase<ProductDerived, Lhs,Rhs>, 0,
                                                        EvalBeforeNestingBit | EvalBeforeAssigningBit>& other)
 {
-  other._expression().subTo(derived()); return derived();
+  other._expression().derived().subTo(derived()); return derived();
 }
 
 #endif // EIGEN_PRODUCTBASE_H
diff --git a/Eigen/src/Core/products/GeneralMatrixMatrix.h b/Eigen/src/Core/products/GeneralMatrixMatrix.h
index ff0f2c1b4..8b3b13266 100644
--- a/Eigen/src/Core/products/GeneralMatrixMatrix.h
+++ b/Eigen/src/Core/products/GeneralMatrixMatrix.h
@@ -137,7 +137,7 @@ class GeneralProduct<Lhs, Rhs, GemmProduct>
 
     GeneralProduct(const Lhs& lhs, const Rhs& rhs) : Base(lhs,rhs) {}
 
-    template<typename Dest> void addTo(Dest& dst, Scalar alpha) const
+    template<typename Dest> void scaleAndAddTo(Dest& dst, Scalar alpha) const
     {
       ei_assert(dst.rows()==m_lhs.rows() && dst.cols()==m_rhs.cols());
 
diff --git a/Eigen/src/Core/products/SelfadjointMatrixMatrix.h b/Eigen/src/Core/products/SelfadjointMatrixMatrix.h
index 358da3752..5e025b90b 100644
--- a/Eigen/src/Core/products/SelfadjointMatrixMatrix.h
+++ b/Eigen/src/Core/products/SelfadjointMatrixMatrix.h
@@ -375,7 +375,7 @@ struct SelfadjointProductMatrix<Lhs,LhsMode,false,Rhs,RhsMode,false>
     RhsIsSelfAdjoint = (RhsMode&SelfAdjointBit)==SelfAdjointBit
   };
 
-  template<typename Dest> void addTo(Dest& dst, Scalar alpha) const
+  template<typename Dest> void scaleAndAddTo(Dest& dst, Scalar alpha) const
   {
     ei_assert(dst.rows()==m_lhs.rows() && dst.cols()==m_rhs.cols());
 
diff --git a/Eigen/src/Core/products/SelfadjointMatrixVector.h b/Eigen/src/Core/products/SelfadjointMatrixVector.h
index f0004cdb9..c2c33d5b8 100644
--- a/Eigen/src/Core/products/SelfadjointMatrixVector.h
+++ b/Eigen/src/Core/products/SelfadjointMatrixVector.h
@@ -175,7 +175,7 @@ struct SelfadjointProductMatrix<Lhs,LhsMode,false,Rhs,0,true>
 
   SelfadjointProductMatrix(const Lhs& lhs, const Rhs& rhs) : Base(lhs,rhs) {}
 
-  template<typename Dest> void addTo(Dest& dst, Scalar alpha) const
+  template<typename Dest> void scaleAndAddTo(Dest& dst, Scalar alpha) const
   {
     ei_assert(dst.rows()==m_lhs.rows() && dst.cols()==m_rhs.cols());
 
diff --git a/Eigen/src/Core/products/TriangularMatrixMatrix.h b/Eigen/src/Core/products/TriangularMatrixMatrix.h
index c2ee39e79..701ccb644 100644
--- a/Eigen/src/Core/products/TriangularMatrixMatrix.h
+++ b/Eigen/src/Core/products/TriangularMatrixMatrix.h
@@ -333,7 +333,7 @@ struct TriangularProduct<Mode,LhsIsTriangular,Lhs,false,Rhs,false>
 
   TriangularProduct(const Lhs& lhs, const Rhs& rhs) : Base(lhs,rhs) {}
 
-  template<typename Dest> void addTo(Dest& dst, Scalar alpha) const
+  template<typename Dest> void scaleAndAddTo(Dest& dst, Scalar alpha) const
   {
     const ActualLhsType lhs = LhsBlasTraits::extract(m_lhs);
     const ActualRhsType rhs = RhsBlasTraits::extract(m_rhs);
diff --git a/Eigen/src/Core/products/TriangularMatrixVector.h b/Eigen/src/Core/products/TriangularMatrixVector.h
index a21afa2f6..620b090b9 100644
--- a/Eigen/src/Core/products/TriangularMatrixVector.h
+++ b/Eigen/src/Core/products/TriangularMatrixVector.h
@@ -130,7 +130,7 @@ struct TriangularProduct<Mode,true,Lhs,false,Rhs,true>
 
   TriangularProduct(const Lhs& lhs, const Rhs& rhs) : Base(lhs,rhs) {}
 
-  template<typename Dest> void addTo(Dest& dst, Scalar alpha) const
+  template<typename Dest> void scaleAndAddTo(Dest& dst, Scalar alpha) const
   {
     ei_assert(dst.rows()==m_lhs.rows() && dst.cols()==m_rhs.cols());