From 53cc52127bda021bb545f0ff2b37fcbc593046ef Mon Sep 17 00:00:00 2001
From: Peter Dimov <pdimov@pdimov.com>
Date: Tue, 10 Feb 2004 23:17:12 +0000
Subject: [PATCH] Self-assignment optimization

[SVN r22233]
---
 include/boost/detail/shared_count.hpp | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/include/boost/detail/shared_count.hpp b/include/boost/detail/shared_count.hpp
index 2d14179..a9ba4d2 100644
--- a/include/boost/detail/shared_count.hpp
+++ b/include/boost/detail/shared_count.hpp
@@ -395,9 +395,13 @@ public:
     shared_count & operator= (shared_count const & r) // nothrow
     {
         sp_counted_base * tmp = r.pi_;
-        if(tmp != 0) tmp->add_ref_copy();
-        if(pi_ != 0) pi_->release();
-        pi_ = tmp;
+
+        if(tmp != pi_)
+        {
+            if(tmp != 0) tmp->add_ref_copy();
+            if(pi_ != 0) pi_->release();
+            pi_ = tmp;
+        }
 
         return *this;
     }