From efc7c2121a88657a62ab967e52222d0f60eaefb9 Mon Sep 17 00:00:00 2001
From: Gael Guennebaud <g.gael@free.fr>
Date: Wed, 16 Dec 2015 09:42:56 +0100
Subject: [PATCH] Backport early cut return for empty matrix product

---
 Eigen/src/Core/products/GeneralMatrixMatrix.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Eigen/src/Core/products/GeneralMatrixMatrix.h b/Eigen/src/Core/products/GeneralMatrixMatrix.h
index 2ac805ec8..649bd3f96 100644
--- a/Eigen/src/Core/products/GeneralMatrixMatrix.h
+++ b/Eigen/src/Core/products/GeneralMatrixMatrix.h
@@ -401,6 +401,8 @@ class GeneralProduct<Lhs, Rhs, GemmProduct>
     template<typename Dest> void scaleAndAddTo(Dest& dst, const Scalar& alpha) const
     {
       eigen_assert(dst.rows()==m_lhs.rows() && dst.cols()==m_rhs.cols());
+      if(a_lhs.cols()==0 || a_lhs.rows()==0 || a_rhs.cols()==0)
+        return;
 
       typename internal::add_const_on_value_type<ActualLhsType>::type lhs = LhsBlasTraits::extract(m_lhs);
       typename internal::add_const_on_value_type<ActualRhsType>::type rhs = RhsBlasTraits::extract(m_rhs);