From e12ed6864b99f6b4eae0be9b6068774dcb6be753 Mon Sep 17 00:00:00 2001
From: Daniel Frey <d.frey@gmx.de>
Date: Tue, 22 Apr 2008 06:31:32 +0000
Subject: [PATCH] Avoid unneccessary increment/decrement of reference count

[SVN r44711]
---
 include/boost/detail/shared_count.hpp | 20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)

diff --git a/include/boost/detail/shared_count.hpp b/include/boost/detail/shared_count.hpp
index 4a71f20..2745649 100644
--- a/include/boost/detail/shared_count.hpp
+++ b/include/boost/detail/shared_count.hpp
@@ -324,9 +324,13 @@ public:
     weak_count & operator= (shared_count const & r) // nothrow
     {
         sp_counted_base * tmp = r.pi_;
-        if(tmp != 0) tmp->weak_add_ref();
-        if(pi_ != 0) pi_->weak_release();
-        pi_ = tmp;
+
+        if( tmp != pi_ )
+        {
+            if(tmp != 0) tmp->weak_add_ref();
+            if(pi_ != 0) pi_->weak_release();
+            pi_ = tmp;
+        }
 
         return *this;
     }
@@ -334,9 +338,13 @@ public:
     weak_count & operator= (weak_count const & r) // nothrow
     {
         sp_counted_base * tmp = r.pi_;
-        if(tmp != 0) tmp->weak_add_ref();
-        if(pi_ != 0) pi_->weak_release();
-        pi_ = tmp;
+
+        if( tmp != pi_ )
+        {
+            if(tmp != 0) tmp->weak_add_ref();
+            if(pi_ != 0) pi_->weak_release();
+            pi_ = tmp;
+        }
 
         return *this;
     }