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7adcbafe | 1 | /* Copyright (C) 2015-2022 Free Software Foundation, Inc. |
fa499995 AS |
2 | Contributed by Mentor Embedded. |
3 | ||
4 | This file is part of the GNU Offloading and Multi Processing Library | |
5 | (libgomp). | |
6 | ||
7 | Libgomp is free software; you can redistribute it and/or modify it | |
8 | under the terms of the GNU General Public License as published by | |
9 | the Free Software Foundation; either version 3, or (at your option) | |
10 | any later version. | |
11 | ||
12 | Libgomp is distributed in the hope that it will be useful, but WITHOUT ANY | |
13 | WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS | |
14 | FOR A PARTICULAR PURPOSE. See the GNU General Public License for | |
15 | more details. | |
16 | ||
17 | Under Section 7 of GPL version 3, you are granted additional | |
18 | permissions described in the GCC Runtime Library Exception, version | |
19 | 3.1, as published by the Free Software Foundation. | |
20 | ||
21 | You should have received a copy of the GNU General Public License and | |
22 | a copy of the GCC Runtime Library Exception along with this program; | |
23 | see the files COPYING3 and COPYING.RUNTIME respectively. If not, see | |
24 | <http://www.gnu.org/licenses/>. */ | |
25 | ||
26 | /* This is the AMD GCN implementation of doacross spinning. */ | |
27 | ||
28 | #ifndef GOMP_DOACROSS_H | |
29 | #define GOMP_DOACROSS_H 1 | |
30 | ||
31 | #include "libgomp.h" | |
32 | ||
33 | static inline int | |
34 | cpu_relax (void) | |
35 | { | |
36 | /* This can be implemented as just a memory barrier, but a sleep seems | |
37 | like it should allow the wavefront to yield (maybe?) | |
38 | Use the shortest possible sleep time of 1*64 cycles. */ | |
39 | asm volatile ("s_sleep\t1" ::: "memory"); | |
40 | return 0; | |
41 | } | |
42 | ||
43 | static inline void doacross_spin (unsigned long *addr, unsigned long expected, | |
44 | unsigned long cur) | |
45 | { | |
46 | /* Prevent compiler from optimizing based on bounds of containing object. */ | |
47 | asm ("" : "+r" (addr)); | |
48 | do | |
49 | { | |
50 | /* An alternative implementation might use s_setprio to lower the | |
51 | priority temporarily, and then restore it after. */ | |
52 | int i = cpu_relax (); | |
53 | cur = addr[i]; | |
54 | } | |
55 | while (cur <= expected); | |
56 | } | |
57 | ||
58 | #endif /* GOMP_DOACROSS_H */ |