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7adcbafe | 1 | /* Copyright (C) 2018-2022 Free Software Foundation, Inc. |
a4c6bd08 AK |
2 | Contributed by Andreas Krebbel <krebbel@linux.vnet.ibm.com> |
3 | ||
4 | This file is part of the GNU Atomic Library (libatomic). | |
5 | ||
6 | Libatomic is free software; you can redistribute it and/or modify it | |
7 | under the terms of the GNU General Public License as published by | |
8 | the Free Software Foundation; either version 3 of the License, or | |
9 | (at your option) any later version. | |
10 | ||
11 | Libatomic is distributed in the hope that it will be useful, but WITHOUT ANY | |
12 | WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS | |
13 | FOR A PARTICULAR PURPOSE. See the GNU General Public License for | |
14 | more details. | |
15 | ||
16 | Under Section 7 of GPL version 3, you are granted additional | |
17 | permissions described in the GCC Runtime Library Exception, version | |
18 | 3.1, as published by the Free Software Foundation. | |
19 | ||
20 | You should have received a copy of the GNU General Public License and | |
21 | a copy of the GCC Runtime Library Exception along with this program; | |
22 | see the files COPYING3 and COPYING.RUNTIME respectively. If not, see | |
23 | <http://www.gnu.org/licenses/>. */ | |
24 | ||
25 | #include <libatomic_i.h> | |
26 | ||
27 | ||
28 | /* The compiler builtin will use the hardware instruction cdsg if the | |
29 | memory operand is properly aligned and will fall back to the | |
30 | library call otherwise. | |
31 | ||
32 | In case the compiler for one part is able to detect that the | |
33 | location is aligned and fails to do so for another usage of the hw | |
34 | instruction and the sw fall back would be mixed on the same memory | |
35 | location. To avoid this the library fall back also has to use the | |
36 | hardware instruction if possible. */ | |
37 | ||
38 | #if !DONE && N == 16 | |
39 | UTYPE | |
40 | SIZE(libat_exchange) (UTYPE *mptr, UTYPE newval, int smodel UNUSED) | |
41 | { | |
42 | if (!((uintptr_t)mptr & 0xf)) | |
43 | { | |
44 | /* Use the builtin only if the memory operand is 16 byte | |
45 | aligned. */ | |
46 | return __atomic_exchange_n ((UTYPE *)__builtin_assume_aligned (mptr, 16), | |
47 | newval, __ATOMIC_SEQ_CST); | |
48 | } | |
49 | else | |
50 | { | |
51 | UTYPE oldval; | |
52 | UWORD magic; | |
53 | ||
54 | pre_seq_barrier (smodel); | |
55 | magic = protect_start (mptr); | |
56 | ||
57 | oldval = *mptr; | |
58 | *mptr = newval; | |
59 | ||
60 | protect_end (mptr, magic); | |
61 | post_seq_barrier (smodel); | |
62 | ||
63 | return oldval; | |
64 | } | |
65 | } | |
66 | #define DONE 1 | |
67 | #endif /* N == 16 */ | |
68 | ||
69 | #include "../../exch_n.c" |