2 * Copyright (c) 2003 Hewlett-Packard Development Company, L.P.
4 * Permission is hereby granted, free of charge, to any person obtaining a copy
5 * of this software and associated documentation files (the "Software"), to deal
6 * in the Software without restriction, including without limitation the rights
7 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
8 * copies of the Software, and to permit persons to whom the Software is
9 * furnished to do so, subject to the following conditions:
11 * The above copyright notice and this permission notice shall be included in
12 * all copies or substantial portions of the Software.
14 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
15 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
16 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
17 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
18 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
19 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
24 * This file adds definitions appropriate for environments in which an AO_t
25 * volatile load has acquire semantics, and an AO_t volatile store has release
26 * semantics. This is arguably supposed to be true with the standard Itanium
27 * software conventions.
31 * Empirically gcc/ia64 does some reordering of ordinary operations around volatiles
32 * even when we think it shouldn't. Gcc 3.3 and earlier could reorder a volatile store
33 * with another store. As of March 2005, gcc pre-4 reused previously computed
34 * common subexpressions across a volatile load.
35 * Hence we now add compiler barriers for gcc.
37 #if !defined(AO_GCC_BARRIER)
38 # if defined(__GNUC__)
39 # define AO_GCC_BARRIER() AO_compiler_barrier()
41 # define AO_GCC_BARRIER()
46 AO_load_acquire(const volatile AO_t *p)
49 /* A normal volatile load generates an ld.acq */
53 #define AO_HAVE_load_acquire
56 AO_store_release(volatile AO_t *p, AO_t val)
59 /* A normal volatile store generates an st.rel */
62 #define AO_HAVE_store_release