35648b4572
2008-04-24 Benjamin Kosnik <bkoz@redhat.com> * acinclude.m4 (GLIBCXX_ENABLE_ATOMIC_BUILTINS): Check for set of all used __sync builtins, in two sizes. * config.h.in: Regenerate. * configure: Regenerate. * src/atomic.cc: Use _GLIBCXX_ATOMIC_BUILTINS_1. * include/ext/atomicity.h: Use _GLIBCXX_ATOMIC_BUILTINS_4. * libsupc++/guard.cc: Use _GLIBCXX_ATOMIC_BUILTINS_4. * doc/xml/manual/concurrency.xm: Update docs. From-SVN: r134629
119 lines
3.7 KiB
C++
119 lines
3.7 KiB
C++
// Support for atomic operations -*- C++ -*-
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// Copyright (C) 2004, 2005, 2006, 2008 Free Software Foundation, Inc.
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//
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// This file is part of the GNU ISO C++ Library. This library is free
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// software; you can redistribute it and/or modify it under the
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// terms of the GNU General Public License as published by the
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// Free Software Foundation; either version 2, or (at your option)
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// any later version.
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// You should have received a copy of the GNU General Public License along
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// with this library; see the file COPYING. If not, write to the Free
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// Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
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// USA.
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// As a special exception, you may use this file as part of a free software
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// library without restriction. Specifically, if other files instantiate
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// templates or use macros or inline functions from this file, or you compile
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// this file and link it with other files to produce an executable, this
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// file does not by itself cause the resulting executable to be covered by
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// the GNU General Public License. This exception does not however
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// invalidate any other reasons why the executable file might be covered by
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// the GNU General Public License.
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/** @file atomicity.h
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* This is an internal header file, included by other library headers.
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* You should not attempt to use it directly.
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*/
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#ifndef _GLIBCXX_ATOMICITY_H
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#define _GLIBCXX_ATOMICITY_H 1
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#include <bits/c++config.h>
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#include <bits/gthr.h>
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#include <bits/atomic_word.h>
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_GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
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// Functions for portable atomic access.
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// To abstract locking primitives across all thread policies, use:
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// __exchange_and_add_dispatch
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// __atomic_add_dispatch
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#ifdef _GLIBCXX_ATOMIC_BUILTINS_4
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static inline _Atomic_word
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__exchange_and_add(volatile _Atomic_word* __mem, int __val)
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{ return __sync_fetch_and_add(__mem, __val); }
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static inline void
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__atomic_add(volatile _Atomic_word* __mem, int __val)
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{ __sync_fetch_and_add(__mem, __val); }
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#else
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_Atomic_word
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__attribute__ ((__unused__))
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__exchange_and_add(volatile _Atomic_word*, int);
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void
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__attribute__ ((__unused__))
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__atomic_add(volatile _Atomic_word*, int);
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#endif
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static inline _Atomic_word
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__exchange_and_add_single(_Atomic_word* __mem, int __val)
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{
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_Atomic_word __result = *__mem;
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*__mem += __val;
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return __result;
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}
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static inline void
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__atomic_add_single(_Atomic_word* __mem, int __val)
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{ *__mem += __val; }
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static inline _Atomic_word
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__attribute__ ((__unused__))
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__exchange_and_add_dispatch(_Atomic_word* __mem, int __val)
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{
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#ifdef __GTHREADS
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if (__gthread_active_p())
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return __exchange_and_add(__mem, __val);
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else
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return __exchange_and_add_single(__mem, __val);
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#else
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return __exchange_and_add_single(__mem, __val);
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#endif
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}
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static inline void
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__attribute__ ((__unused__))
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__atomic_add_dispatch(_Atomic_word* __mem, int __val)
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{
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#ifdef __GTHREADS
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if (__gthread_active_p())
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__atomic_add(__mem, __val);
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else
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__atomic_add_single(__mem, __val);
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#else
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__atomic_add_single(__mem, __val);
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#endif
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}
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_GLIBCXX_END_NAMESPACE
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// Even if the CPU doesn't need a memory barrier, we need to ensure
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// that the compiler doesn't reorder memory accesses across the
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// barriers.
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#ifndef _GLIBCXX_READ_MEM_BARRIER
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#define _GLIBCXX_READ_MEM_BARRIER __asm __volatile ("":::"memory")
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#endif
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#ifndef _GLIBCXX_WRITE_MEM_BARRIER
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#define _GLIBCXX_WRITE_MEM_BARRIER __asm __volatile ("":::"memory")
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#endif
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#endif
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