libstdc++-v3/config/cpu/ia64/atomic_word.h

   1 // Low-level type for atomic operations -*- C++ -*-
   2
   3 // Copyright (C) 2004, 2005, 2006, 2007, 2009 Free Software Foundation, Inc.
   4 //
   5 // This file is part of the GNU ISO C++ Library.  This library is free
   6 // software; you can redistribute it and/or modify it under the
   7 // terms of the GNU General Public License as published by the
   8 // Free Software Foundation; either version 3, or (at your option)
   9 // any later version.
  10
  11 // This library is distributed in the hope that it will be useful,
  12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 // GNU General Public License for more details.
  15
  16 // Under Section 7 of GPL version 3, you are granted additional
  17 // permissions described in the GCC Runtime Library Exception, version
  18 // 3.1, as published by the Free Software Foundation.
  19
  20 // You should have received a copy of the GNU General Public License and
  21 // a copy of the GCC Runtime Library Exception along with this program;
  22 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  23 // <http://www.gnu.org/licenses/>.
  24
  25 #ifndef _GLIBCXX_ATOMIC_WORD_H
  26 #define _GLIBCXX_ATOMIC_WORD_H  1
  27
  28 #include <bits/cxxabi_tweaks.h>
  29
  30 typedef int _Atomic_word;
  31
  32 namespace __gnu_cxx
  33 {
  34   // Test the first byte of __g and ensure that no loads are hoisted across
  35   // the test.
  36   inline bool
  37   __test_and_acquire (__cxxabiv1::__guard *__g)
  38   {
  39     unsigned char __c;
  40     unsigned char *__p = reinterpret_cast<unsigned char *>(__g);
  41     // ldN.acq is a load with an implied hoist barrier.
  42     // would ld8+mask be faster than just doing an ld1?
  43     __asm __volatile ("ld1.acq %0 = %1" : "=r"(__c) : "m"(*__p) : "memory");
  44     return __c != 0;
  45   }
  46
  47   // Set the first byte of __g to 1 and ensure that no stores are sunk
  48   // across the store.
  49   inline void
  50   __set_and_release (__cxxabiv1::__guard *__g)
  51   {
  52     unsigned char *__p = reinterpret_cast<unsigned char *>(__g);
  53     // stN.rel is a store with an implied sink barrier.
  54     // could load word, set flag, and CAS it back
  55     __asm __volatile ("st1.rel %0 = %1" : "=m"(*__p) : "r"(1) : "memory");
  56   }
  57
  58   // We don't define the _BARRIER macros on ia64 because the barriers are
  59   // included in the test and set, above.
  60 #define _GLIBCXX_GUARD_TEST_AND_ACQUIRE(G) __gnu_cxx::__test_and_acquire (G)
  61 #define _GLIBCXX_GUARD_SET_AND_RELEASE(G) __gnu_cxx::__set_and_release (G)
  62 }
  63
  64 #endif