From a147500dee85092fbfbf755123553f412a218ec2 Mon Sep 17 00:00:00 2001
From: Pavel Holoborodko <pavel@holoborodko.com>
Date: Sun, 25 Aug 2013 18:00:28 +0900
Subject: [PATCH] Added smart_memmove with support of non-POD scalars (e.g.
 needed in SparseBlock.h).

---
 Eigen/src/Core/util/Memory.h | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/Eigen/src/Core/util/Memory.h b/Eigen/src/Core/util/Memory.h
index 451535a0c..3a357e079 100644
--- a/Eigen/src/Core/util/Memory.h
+++ b/Eigen/src/Core/util/Memory.h
@@ -6,6 +6,7 @@
 // Copyright (C) 2009 Kenneth Riddile <kfriddile@yahoo.com>
 // Copyright (C) 2010 Hauke Heibel <hauke.heibel@gmail.com>
 // Copyright (C) 2010 Thomas Capricelli <orzel@freehackers.org>
+// Copyright (C) 2013 Pavel Holoborodko <pavel@holoborodko.com>
 //
 // This Source Code Form is subject to the terms of the Mozilla
 // Public License v. 2.0. If a copy of the MPL was not distributed
@@ -514,6 +515,34 @@ template<typename T> struct smart_copy_helper<T,false> {
   { std::copy(start, end, target); }
 };
 
+// intelligent memmove. falls back to std::memmove for POD types, uses std::copy otherwise. 
+template<typename T, bool UseMemmove> struct smart_memmove_helper;
+
+template<typename T> void smart_memmove(const T* start, const T* end, T* target)
+{
+    smart_memmove_helper<T,!NumTraits<T>::RequireInitialization>::run(start, end, target);
+}
+
+template<typename T> struct smart_memmove_helper<T,true> {
+    static inline void run(const T* start, const T* end, T* target)
+    { std::memmove(target, start, std::ptrdiff_t(end)-std::ptrdiff_t(start)); }
+};
+
+template<typename T> struct smart_memmove_helper<T,false> {
+    static inline void run(const T* start, const T* end, T* target)
+    { 
+        if (uintptr_t(target) < uintptr_t(start))
+        {
+            std::copy(start, end, target);
+        }
+        else                                 
+        {
+            std::ptrdiff_t count = (std::ptrdiff_t(end)-std::ptrdiff_t(start)) / sizeof(T);
+            std::copy_backward(start, end, target + count); 
+        }
+    }
+};
+
 
 /*****************************************************************************
 *** Implementation of runtime stack allocation (falling back to malloc)    ***