md-atomic.hpp

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/* src/vm/jit/x86_64/atomic.hpp - x86_64 atomic instructions

   Copyright (C) 1996-2013
   CACAOVM - Verein zur Foerderung der freien virtuellen Maschine CACAO

   This file is part of CACAO.

   This program is free software; you can redistribute it and/or
   modify it under the terms of the GNU General Public License as
   published by the Free Software Foundation; either version 2, or (at
   your option) any later version.

   This program is distributed in the hope that it will be useful, but
   WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
   02110-1301, USA.

*/


#ifndef MD_ATOMIC_HPP_
#define MD_ATOMIC_HPP_ 1

#include "config.h"

#include <stdint.h>

#include "threads/atomic.hpp"

namespace Atomic_md {

/**
 * An atomic compare and swap for 32-bit integer values.
 *
 * @param p      Pointer to memory address.
 * @param oldval Old value to be expected.
 * @param newval New value to be stored.
 *
 * @return value of the memory location before the store
 */
inline uint32_t compare_and_swap(volatile uint32_t *p, uint32_t oldval, uint32_t newval)
{
    uint32_t result;

    __asm__ __volatile__ ("lock; cmpxchgl %2, %1"
                          : "=a" (result), "=m" (*p)
                          : "r" (newval), "m" (*p), "0" (oldval)
                          : "cc");

    return result;
}


/**
 * An atomic compare and swap for 64-bit integer values.
 *
 * @param p      Pointer to memory address.
 * @param oldval Old value to be expected.
 * @param newval New value to be stored.
 *
 * @return value of the memory location before the store
 */
inline uint64_t compare_and_swap(volatile uint64_t *p, uint64_t oldval, uint64_t newval)
{
    uint64_t result;

    __asm__ __volatile__ ("lock; cmpxchgq %2, %1"
                          : "=a" (result), "=m" (*p)
                          : "r" (newval), "m" (*p), "0" (oldval)
                          : "cc");

    return result;
}


/**
 * A memory barrier.
 */
inline void memory_barrier(void)
{
    __asm__ __volatile__ ("mfence" : : : "memory");
}


/**
 * A write memory barrier.
 */
inline void write_memory_barrier(void)
{
    __asm__ __volatile__ ("" : : : "memory");
}


/**
 * An instruction barrier.
 */
inline void instruction_barrier(void)
{
    // We need the "memory" constraint here because compare_and_swap does not
    // have it.
    __asm__ __volatile__ ("" : : : "memory");
}

}

#endif // MD_ATOMIC_HPP_


/*
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 * Please do not remove this and leave it at the end of the file, where
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