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