/*

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code 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

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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 */

#ifndef OS_CPU_LINUX_X86_VM_ORDERACCESS_LINUX_X86_INLINE_HPP

#define OS_CPU_LINUX_X86_VM_ORDERACCESS_LINUX_X86_INLINE_HPP

#include "runtime/atomic.hpp"

#include "runtime/orderAccess.hpp"

#include "runtime/os.hpp"

// Compiler version last used for testing: gcc 4.8.2

// Please update this information when this file changes

// Implementation of class OrderAccess.

// A compiler barrier, forcing the C++ compiler to invalidate all memory assumptions

static inline void compiler_barrier() {

  __asm__ volatile ("" : : : "memory");

}

inline void OrderAccess::loadload()   { compiler_barrier(); }

inline void OrderAccess::storestore() { compiler_barrier(); }

inline void OrderAccess::loadstore()  { compiler_barrier(); }

inline void OrderAccess::storeload()  { fence();            }

inline void OrderAccess::acquire()    { compiler_barrier(); }

inline void OrderAccess::release()    { compiler_barrier(); }

inline void OrderAccess::fence() {

  if (os::is_MP()) {

    // always use locked addl since mfence is sometimes expensive

#ifdef AMD64

    __asm__ volatile ("lock; addl $0,0(%%rsp)" : : : "cc", "memory");

#else

    __asm__ volatile ("lock; addl $0,0(%%esp)" : : : "cc", "memory");

#endif

  }

  compiler_barrier();

}

template<>

struct OrderAccess::PlatformOrderedStore<1, RELEASE_X_FENCE>

{

  template <typename T>

  void operator()(T v, volatile T* p) const {

    __asm__ volatile (  "xchgb (%2),%0"

                      : "=q" (v)

                      : "0" (v), "r" (p)

                      : "memory");

  }

};

template<>

struct OrderAccess::PlatformOrderedStore<2, RELEASE_X_FENCE>

{

  template <typename T>

  void operator()(T v, volatile T* p) const {

    __asm__ volatile (  "xchgw (%2),%0"

                      : "=r" (v)

                      : "0" (v), "r" (p)

                      : "memory");

  }

};

template<>

struct OrderAccess::PlatformOrderedStore<4, RELEASE_X_FENCE>

{

  template <typename T>

  void operator()(T v, volatile T* p) const {

    __asm__ volatile (  "xchgl (%2),%0"

                      : "=r" (v)

                      : "0" (v), "r" (p)

                      : "memory");

  }

};

#ifdef AMD64

template<>

struct OrderAccess::PlatformOrderedStore<8, RELEASE_X_FENCE>

{

  template <typename T>

  void operator()(T v, volatile T* p) const {

    __asm__ volatile (  "xchgq (%2), %0"

                      : "=r" (v)

                      : "0" (v), "r" (p)

                      : "memory");

  }

};

#endif // AMD64

#endif // OS_CPU_LINUX_X86_VM_ORDERACCESS_LINUX_X86_INLINE_HPP