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63 lines
2.6 KiB
C
63 lines
2.6 KiB
C
/*
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* Copyright (c) 2003-2004 Hewlett-Packard Development Company, L.P.
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*/
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/* This file adds definitions appropriate for environments in which */
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/* volatile load of a given type has acquire semantics, and volatile */
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/* store of a given type has release semantics. This is arguably */
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/* supposed to be true with the standard Itanium software conventions. */
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/* Empirically gcc/ia64 does some reordering of ordinary operations */
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/* around volatiles even when we think it should not. GCC v3.3 and */
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/* earlier could reorder a volatile store with another store. As of */
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/* March 2005, gcc pre-4 reuses some previously computed common */
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/* subexpressions across a volatile load; hence, we now add compiler */
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/* barriers for gcc. */
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#ifndef AO_HAVE_GCC_BARRIER
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/* TODO: Check GCC version (if workaround not needed for modern GCC). */
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# if defined(__GNUC__)
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# define AO_GCC_BARRIER() AO_compiler_barrier()
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# else
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# define AO_GCC_BARRIER() (void)0
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# endif
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# define AO_HAVE_GCC_BARRIER
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#endif
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AO_INLINE unsigned
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AO_int_load_acquire(const volatile unsigned *addr)
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{
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unsigned result = *addr;
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/* A normal volatile load generates an ld.acq (on IA-64). */
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AO_GCC_BARRIER();
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return result;
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}
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#define AO_HAVE_int_load_acquire
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AO_INLINE void
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AO_int_store_release(volatile unsigned *addr, unsigned new_val)
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{
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AO_GCC_BARRIER();
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/* A normal volatile store generates an st.rel (on IA-64). */
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*addr = new_val;
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}
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#define AO_HAVE_int_store_release
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