external_libraries/boost-lockfree/boost/lockfree/detail/branch_hints.hpp

   1 //  branch hints
   2 //  Copyright (C) 2007, 2008 Tim Blechmann
   3 //
   4 //  Distributed under the Boost Software License, Version 1.0. (See
   5 //  accompanying file LICENSE_1_0.txt or copy at
   6 //  http://www.boost.org/LICENSE_1_0.txt)
   7
   8 #ifndef BOOST_LOCKFREE_BRANCH_HINTS_HPP_INCLUDED
   9 #define BOOST_LOCKFREE_BRANCH_HINTS_HPP_INCLUDED
  10
  11 namespace boost    {
  12 namespace lockfree {
  13 namespace detail   {
  14 /** \brief hint for the branch prediction */
  15 inline bool likely(bool expr)
  16 {
  17 #ifdef __GNUC__
  18     return __builtin_expect(expr, true);
  19 #else
  20     return expr;
  21 #endif
  22     }
  23
  24 /** \brief hint for the branch prediction */
  25 inline bool unlikely(bool expr)
  26 {
  27 #ifdef __GNUC__
  28     return __builtin_expect(expr, false);
  29 #else
  30     return expr;
  31 #endif
  32 }
  33
  34 } /* namespace detail */
  35 } /* namespace lockfree */
  36 } /* namespace boost */
  37
  38 #endif /* BOOST_LOCKFREE_BRANCH_HINTS_HPP_INCLUDED */