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/*
* %CopyrightBegin%
*
* Copyright Ericsson AB 2011. All Rights Reserved.
*
* The contents of this file are subject to the Erlang Public License,
* Version 1.1, (the "License"); you may not use this file except in
* compliance with the License. You should have received a copy of the
* Erlang Public License along with this software. If not, it can be
* retrieved online at http://www.erlang.org/.
*
* Software distributed under the License is distributed on an "AS IS"
* basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
* the License for the specific language governing rights and limitations
* under the License.
*
* %CopyrightEnd%
*/
/*
* Description: Memory barriers when using gcc's builtins
* Author: Rickard Green
*/
#ifndef ETHR_GCC_MEMBAR_H__
#define ETHR_GCC_MEMBAR_H__
#define ETHR_LoadLoad (1 << 0)
#define ETHR_LoadStore (1 << 1)
#define ETHR_StoreLoad (1 << 2)
#define ETHR_StoreStore (1 << 3)
/*
* According to the documentation __sync_synchronize() will
* issue a full memory barrier. However, __sync_synchronize()
* is known to erroneously be a noop on at least some
* platforms with some gcc versions. This has suposedly been
* fixed in some gcc version, but we don't know from which
* version. Therefore, we only use it when it has been
* verified to work. Otherwise we use the workaround
* below.
*/
#if defined(ETHR_HAVE___SYNC_VAL_COMPARE_AND_SWAP32)
# define ETHR_MB_T__ ethr_sint32_t
#elif defined(ETHR_HAVE___SYNC_VAL_COMPARE_AND_SWAP64)
# define ETHR_MB_T__ ethr_sint64_t
#else
# error "No __sync_val_compare_and_swap"
#endif
#define ETHR_SYNC_SYNCHRONIZE_WORKAROUND__ \
do { \
volatile ETHR_MB_T__ x___ = 0; \
(void) __sync_val_compare_and_swap(&x___, (ETHR_MB_T__) 0, (ETHR_MB_T__) 1); \
} while (0)
#define ETHR_COMPILER_BARRIER __asm__ __volatile__("" : : : "memory")
#if defined(__mips__) && ETHR_AT_LEAST_GCC_VSN__(4, 2, 0)
# define ETHR_MEMBAR(B) __sync_synchronize()
# define ETHR_READ_DEPEND_MEMORY_BARRIER __sync_synchronize()
#elif ((defined(__powerpc__) || defined(__ppc__)) \
&& ETHR_AT_LEAST_GCC_VSN__(4, 1, 2))
# define ETHR_MEMBAR(B) __sync_synchronize()
#else /* Use workaround */
# define ETHR_MEMBAR(B) \
ETHR_SYNC_SYNCHRONIZE_WORKAROUND__
# define ETHR_READ_DEPEND_MEMORY_BARRIER \
ETHR_SYNC_SYNCHRONIZE_WORKAROUND__
#endif
#endif /* ETHR_GCC_MEMBAR_H__ */
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