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a5544970 | 1 | /* Copyright (C) 2012-2019 Free Software Foundation, Inc. |
48310492 RH |
2 | Contributed by Richard Henderson <rth@redhat.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 | /* If we natively support the exchange, and if we're unconcerned with extra | |
29 | barriers (e.g. fully in-order cpu for which barriers are a nop), then | |
30 | go ahead and expand the operation inline. */ | |
31 | #if !defined(WANT_SPECIALCASE_RELAXED) && !defined(__OPTIMIZE_SIZE__) | |
32 | # define EXACT_INLINE(N) \ | |
33 | if (C2(HAVE_ATOMIC_EXCHANGE_,N)) \ | |
34 | { \ | |
35 | *PTR(N,rptr) = __atomic_exchange_n \ | |
94f3ccc8 | 36 | (PTR(N,mptr), *PTR(N,vptr), __ATOMIC_SEQ_CST); \ |
48310492 RH |
37 | return; \ |
38 | } | |
39 | #else | |
40 | # define EXACT_INLINE(N) | |
41 | #endif | |
42 | ||
43 | ||
44 | #define EXACT(N) \ | |
45 | do { \ | |
46 | if (!C2(HAVE_INT,N)) break; \ | |
47 | if ((uintptr_t)mptr & (N - 1)) break; \ | |
48 | EXACT_INLINE (N); \ | |
49 | *PTR(N,rptr) = C3(local_,exchange_,N) \ | |
50 | (PTR(N,mptr), *PTR(N,vptr), smodel); \ | |
51 | return; \ | |
52 | } while (0) | |
53 | ||
54 | ||
55 | #define LARGER(N) \ | |
56 | do { \ | |
57 | if (!C2(HAVE_INT,N)) break; \ | |
58 | if (!C2(MAYBE_HAVE_ATOMIC_CAS_,N)) break; \ | |
59 | r = (uintptr_t)mptr & (N - 1); \ | |
60 | a = (uintptr_t)mptr & -N; \ | |
61 | if (r + n <= N) \ | |
62 | { \ | |
63 | pre_barrier (smodel); \ | |
64 | u.C2(i,N) = *PTR(N,a); \ | |
65 | do { \ | |
66 | v = u; \ | |
67 | memcpy (v.b + r, vptr, n); \ | |
68 | } while (!(C2(HAVE_ATOMIC_CAS_,N) \ | |
69 | ? __atomic_compare_exchange_n (PTR(N,a), \ | |
70 | &u.C2(i,N), v.C2(i,N), true, \ | |
71 | __ATOMIC_RELAXED, __ATOMIC_RELAXED) \ | |
72 | : C3(local_,compare_exchange_,N) (PTR(N,a), \ | |
73 | &u.C2(i,N), v.C2(i,N), \ | |
74 | __ATOMIC_RELAXED, __ATOMIC_RELAXED))); \ | |
75 | goto Lfinish; \ | |
76 | } \ | |
77 | } while (0) | |
78 | ||
79 | ||
80 | static void __attribute__((noinline)) | |
81 | libat_exchange_large_inplace (size_t n, void *mptr, void *vptr) | |
82 | { | |
83 | #define BUF 1024 | |
84 | ||
85 | char temp[BUF]; | |
86 | size_t i = 0; | |
87 | ||
88 | for (i = 0; n >= BUF; i += BUF, n -= BUF) | |
89 | { | |
90 | memcpy (temp, mptr + i, BUF); | |
91 | memcpy (mptr + i, vptr + i, BUF); | |
92 | memcpy (vptr + i, temp, BUF); | |
93 | } | |
94 | if (n > 0) | |
95 | { | |
96 | memcpy (temp, mptr + i, n); | |
97 | memcpy (mptr + i, vptr + i, n); | |
98 | memcpy (vptr + i, temp, n); | |
99 | } | |
100 | ||
101 | #undef BUF | |
102 | } | |
103 | ||
104 | void | |
105 | libat_exchange (size_t n, void *mptr, void *vptr, void *rptr, int smodel) | |
106 | { | |
107 | union max_size_u u, v; | |
108 | uintptr_t r, a; | |
109 | ||
110 | switch (n) | |
111 | { | |
112 | case 0: return; | |
113 | case 1: EXACT(1); goto L4; | |
114 | case 2: EXACT(2); goto L4; | |
115 | case 4: EXACT(4); goto L8; | |
116 | case 8: EXACT(8); goto L16; | |
117 | case 16: EXACT(16); break; | |
118 | ||
119 | case 3: L4: LARGER(4); /* FALLTHRU */ | |
120 | case 5 ... 7: L8: LARGER(8); /* FALLTHRU */ | |
121 | case 9 ... 15: L16: LARGER(16); break; | |
122 | ||
123 | Lfinish: | |
124 | post_barrier (smodel); | |
125 | memcpy (rptr, u.b + r, n); | |
126 | return; | |
127 | } | |
128 | ||
129 | pre_seq_barrier (smodel); | |
130 | libat_lock_n (mptr, n); | |
131 | ||
132 | if (vptr != rptr) | |
133 | { | |
134 | memcpy (rptr, mptr, n); | |
135 | memcpy (mptr, vptr, n); | |
136 | } | |
137 | else | |
138 | libat_exchange_large_inplace (n, mptr, vptr); | |
139 | ||
140 | libat_unlock_n (mptr, n); | |
141 | post_seq_barrier (smodel); | |
142 | } | |
143 | ||
144 | EXPORT_ALIAS (exchange); |