ceph/src/boost/boost/smart_ptr/detail/sp_counted_base_gcc_x86.hpp

   1 #ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_GCC_X86_HPP_INCLUDED
   2 #define BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_GCC_X86_HPP_INCLUDED
   3
   4 // MS compatible compilers support #pragma once
   5
   6 #if defined(_MSC_VER) && (_MSC_VER >= 1020)
   7 # pragma once
   8 #endif
   9
  10 //
  11 //  detail/sp_counted_base_gcc_x86.hpp - g++ on 486+ or AMD64
  12 //
  13 //  Copyright (c) 2001, 2002, 2003 Peter Dimov and Multi Media Ltd.
  14 //  Copyright 2004-2005 Peter Dimov
  15 //
  16 //  Distributed under the Boost Software License, Version 1.0. (See
  17 //  accompanying file LICENSE_1_0.txt or copy at
  18 //  http://www.boost.org/LICENSE_1_0.txt)
  19 //
  20 //
  21 //  Lock-free algorithm by Alexander Terekhov
  22 //
  23 //  Thanks to Ben Hitchings for the #weak + (#shared != 0)
  24 //  formulation
  25 //
  26
  27 #include <boost/smart_ptr/detail/sp_typeinfo_.hpp>
  28 #include <boost/smart_ptr/detail/sp_obsolete.hpp>
  29 #include <boost/config.hpp>
  30
  31 #if defined(BOOST_SP_REPORT_IMPLEMENTATION)
  32
  33 #include <boost/config/pragma_message.hpp>
  34 BOOST_PRAGMA_MESSAGE("Using g++/x86 sp_counted_base")
  35
  36 #endif
  37
  38 BOOST_SP_OBSOLETE()
  39
  40 namespace boost
  41 {
  42
  43 namespace detail
  44 {
  45
  46 inline int atomic_exchange_and_add( int * pw, int dv )
  47 {
  48     // int r = *pw;
  49     // *pw += dv;
  50     // return r;
  51
  52     int r;
  53
  54     __asm__ __volatile__
  55     (
  56         "lock\n\t"
  57         "xadd %1, %0":
  58         "=m"( *pw ), "=r"( r ): // outputs (%0, %1)
  59         "m"( *pw ), "1"( dv ): // inputs (%2, %3 == %1)
  60         "memory", "cc" // clobbers
  61     );
  62
  63     return r;
  64 }
  65
  66 inline void atomic_increment( int * pw )
  67 {
  68     //atomic_exchange_and_add( pw, 1 );
  69
  70     __asm__
  71     (
  72         "lock\n\t"
  73         "incl %0":
  74         "=m"( *pw ): // output (%0)
  75         "m"( *pw ): // input (%1)
  76         "cc" // clobbers
  77     );
  78 }
  79
  80 inline int atomic_conditional_increment( int * pw )
  81 {
  82     // int rv = *pw;
  83     // if( rv != 0 ) ++*pw;
  84     // return rv;
  85
  86     int rv, tmp;
  87
  88     __asm__
  89     (
  90         "movl %0, %%eax\n\t"
  91         "0:\n\t"
  92         "test %%eax, %%eax\n\t"
  93         "je 1f\n\t"
  94         "movl %%eax, %2\n\t"
  95         "incl %2\n\t"
  96         "lock\n\t"
  97         "cmpxchgl %2, %0\n\t"
  98         "jne 0b\n\t"
  99         "1:":
 100         "=m"( *pw ), "=&a"( rv ), "=&r"( tmp ): // outputs (%0, %1, %2)
 101         "m"( *pw ): // input (%3)
 102         "cc" // clobbers
 103     );
 104
 105     return rv;
 106 }
 107
 108 class BOOST_SYMBOL_VISIBLE sp_counted_base
 109 {
 110 private:
 111
 112     sp_counted_base( sp_counted_base const & );
 113     sp_counted_base & operator= ( sp_counted_base const & );
 114
 115     int use_count_;        // #shared
 116     int weak_count_;       // #weak + (#shared != 0)
 117
 118 public:
 119
 120     sp_counted_base(): use_count_( 1 ), weak_count_( 1 )
 121     {
 122     }
 123
 124     virtual ~sp_counted_base() // nothrow
 125     {
 126     }
 127
 128     // dispose() is called when use_count_ drops to zero, to release
 129     // the resources managed by *this.
 130
 131     virtual void dispose() = 0; // nothrow
 132
 133     // destroy() is called when weak_count_ drops to zero.
 134
 135     virtual void destroy() // nothrow
 136     {
 137         delete this;
 138     }
 139
 140     virtual void * get_deleter( sp_typeinfo_ const & ti ) = 0;
 141     virtual void * get_local_deleter( sp_typeinfo_ const & ti ) = 0;
 142     virtual void * get_untyped_deleter() = 0;
 143
 144     void add_ref_copy()
 145     {
 146         atomic_increment( &use_count_ );
 147     }
 148
 149     bool add_ref_lock() // true on success
 150     {
 151         return atomic_conditional_increment( &use_count_ ) != 0;
 152     }
 153
 154     void release() // nothrow
 155     {
 156         if( atomic_exchange_and_add( &use_count_, -1 ) == 1 )
 157         {
 158             dispose();
 159             weak_release();
 160         }
 161     }
 162
 163     void weak_add_ref() // nothrow
 164     {
 165         atomic_increment( &weak_count_ );
 166     }
 167
 168     void weak_release() // nothrow
 169     {
 170         if( atomic_exchange_and_add( &weak_count_, -1 ) == 1 )
 171         {
 172             destroy();
 173         }
 174     }
 175
 176     long use_count() const // nothrow
 177     {
 178         return static_cast<int const volatile &>( use_count_ );
 179     }
 180 };
 181
 182 } // namespace detail
 183
 184 } // namespace boost
 185
 186 #endif  // #ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_GCC_X86_HPP_INCLUDED