From b71ee76d8d2597ef91a78f489e77d18b22e846b4 Mon Sep 17 00:00:00 2001
From: Gael Guennebaud <g.gael@free.fr>
Date: Fri, 19 Feb 2016 22:58:52 +0100
Subject: [PATCH] bug #1170: skip calls to memcpy/memmove for empty imput.

---
 Eigen/src/Core/util/Memory.h | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/Eigen/src/Core/util/Memory.h b/Eigen/src/Core/util/Memory.h
index bc1ea69ed..c3871dbd3 100644
--- a/Eigen/src/Core/util/Memory.h
+++ b/Eigen/src/Core/util/Memory.h
@@ -507,7 +507,12 @@ template<typename T> void smart_copy(const T* start, const T* end, T* target)
 
 template<typename T> struct smart_copy_helper<T,true> {
   static inline void run(const T* start, const T* end, T* target)
-  { memcpy(target, start, std::ptrdiff_t(end)-std::ptrdiff_t(start)); }
+  {
+    std::ptrdiff_t size = std::ptrdiff_t(end)-std::ptrdiff_t(start);
+    if(size==0) return;
+    eigen_internal_assert(start!=0 && end!=0 && target!=0);
+    memcpy(target, start, size);
+  }
 };
 
 template<typename T> struct smart_copy_helper<T,false> {
@@ -515,7 +520,6 @@ template<typename T> struct smart_copy_helper<T,false> {
   { std::copy(start, end, target); }
 };
 
-
 /*****************************************************************************
 *** Implementation of runtime stack allocation (falling back to malloc)    ***
 *****************************************************************************/