From 36a5b82a339293066bc0eb4042bb55f239496dbb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ion=20Gazta=C3=B1aga?= <igaztanaga@gmail.com>
Date: Sun, 9 Feb 2014 23:19:09 +0100
Subject: [PATCH] Fixed bug in 64 bit GCC implementations in floor_log2 and
 __builtin_clz dispatching

---
 include/boost/intrusive/bstree_algorithms.hpp |  3 +-
 include/boost/intrusive/detail/utilities.hpp  | 35 ++++++++++++++-----
 2 files changed, 28 insertions(+), 10 deletions(-)

diff --git a/include/boost/intrusive/bstree_algorithms.hpp b/include/boost/intrusive/bstree_algorithms.hpp
index 0a7cef0..d155d6d 100644
--- a/include/boost/intrusive/bstree_algorithms.hpp
+++ b/include/boost/intrusive/bstree_algorithms.hpp
@@ -1831,7 +1831,8 @@ class bstree_algorithms
 
    static void vine_to_subtree(const node_ptr & super_root, std::size_t count)
    {
-      std::size_t leaf_nodes = count + 1 - ((std::size_t) 1 << detail::floor_log2(count + 1));
+      const std::size_t one_szt = 1u;
+      std::size_t leaf_nodes = count + one_szt - std::size_t(one_szt << detail::floor_log2(count + one_szt));
       compress_subtree(super_root, leaf_nodes);  //create deepest leaves
       std::size_t vine_nodes = count - leaf_nodes;
       while(vine_nodes > 1){
diff --git a/include/boost/intrusive/detail/utilities.hpp b/include/boost/intrusive/detail/utilities.hpp
index 6b4ef26..31bb6e2 100644
--- a/include/boost/intrusive/detail/utilities.hpp
+++ b/include/boost/intrusive/detail/utilities.hpp
@@ -416,21 +416,38 @@ void destructor_impl(Hook &, detail::link_dispatch<normal_link>)
 
 #elif defined(__GNUC__) && ((__GNUC__ >= 4) || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)) //GCC >=3.4
 
-   #if SIZE_MAX > UINT_MAX
-      #define BOOST_INTRUSIVE_CLZ_INTRINSIC __builtin_clzll
-   #elif SIZE_MAX > UINT_MAX
-      #define BOOST_INTRUSIVE_CLZ_INTRINSIC __builtin_clzl
-   #else
-      #define BOOST_INTRUSIVE_CLZ_INTRINSIC __builtin_clz
+   //Compile-time error in case of missing specialization
+   template<class Uint>
+   struct builtin_clz_dispatch;
+
+   #if defined(BOOST_HAS_LONG_LONG)
+   template<>
+   struct builtin_clz_dispatch<unsigned long long>
+   {
+      static const unsigned long long call(unsigned long long n)
+      {  return __builtin_clzll(n); }
+   };
    #endif
 
+   template<>
+   struct builtin_clz_dispatch<unsigned long>
+   {
+      static const unsigned long call(unsigned long n)
+      {  return __builtin_clzl(n); }
+   };
+
+   template<>
+   struct builtin_clz_dispatch<unsigned int>
+   {
+      static const unsigned int call(unsigned int n)
+      {  return __builtin_clz(n); }
+   };
+
    inline std::size_t floor_log2(std::size_t n)
    {
-      return sizeof(std::size_t)*CHAR_BIT - 1 - BOOST_INTRUSIVE_CLZ_INTRINSIC(n);
+      return sizeof(std::size_t)*CHAR_BIT - std::size_t(1) - builtin_clz_dispatch<std::size_t>::call(n);
    }
 
-   #undef BOOST_INTRUSIVE_CLZ_INTRINSIC
-
 #else //Portable methods
 
 ////////////////////////////