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3e6a2e37 | 1 | /* Copyright (C) 2012-2014 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 load, 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, DEST, SRC, DONE) \ | |
33 | if (C2(HAVE_ATOMIC_LDST_,N)) \ | |
34 | { \ | |
94f3ccc8 | 35 | DEST = __atomic_load_n (SRC, __ATOMIC_SEQ_CST); \ |
48310492 RH |
36 | DONE; \ |
37 | } | |
38 | #else | |
39 | # define EXACT_INLINE(N, DEST, SRC, DONE) | |
40 | #endif | |
41 | ||
42 | ||
43 | #define EXACT_(N, DEST, SRC, DONE) \ | |
44 | do { \ | |
45 | EXACT_INLINE (N, DEST, SRC, DONE); \ | |
46 | DEST = C3(local_,load_,N) (SRC, smodel); \ | |
47 | DONE; \ | |
48 | } while (0) | |
49 | ||
50 | #define EXACT(N) \ | |
51 | do { \ | |
52 | if (!C2(HAVE_INT,N)) break; \ | |
53 | if ((uintptr_t)mptr & (N - 1)) break; \ | |
54 | EXACT_(N, *PTR(N,rptr), PTR(N,mptr), return); \ | |
55 | } while (0) | |
56 | ||
57 | #define LARGER(N) \ | |
58 | do { \ | |
59 | if (!C2(HAVE_INT,N)) break; \ | |
60 | r = (uintptr_t)mptr & (N - 1); \ | |
61 | a = (uintptr_t)mptr & -N; \ | |
62 | if (r + n <= N) \ | |
63 | EXACT_ (N, u.C2(i,N), PTR(N,a), goto Lfinish); \ | |
64 | } while (0) | |
65 | ||
66 | ||
67 | void | |
68 | libat_load (size_t n, void *mptr, void *rptr, int smodel) | |
69 | { | |
70 | union max_size_u u; | |
71 | uintptr_t r, a; | |
72 | ||
73 | switch (n) | |
74 | { | |
75 | case 0: return; | |
76 | case 1: EXACT(1); goto L4; | |
77 | case 2: EXACT(2); goto L4; | |
78 | case 4: EXACT(4); goto L8; | |
79 | case 8: EXACT(8); goto L16; | |
80 | case 16: EXACT(16); break; | |
81 | ||
82 | case 3: L4: LARGER(4); /* FALLTHRU */ | |
83 | case 5 ... 7: L8: LARGER(8); /* FALLTHRU */ | |
84 | case 9 ... 15: L16: LARGER(16); break; | |
85 | ||
86 | Lfinish: | |
87 | memcpy (rptr, u.b + r, n); | |
88 | return; | |
89 | } | |
90 | ||
91 | pre_seq_barrier (smodel); | |
92 | libat_lock_n (mptr, n); | |
93 | ||
94 | memcpy (rptr, mptr, n); | |
95 | ||
96 | libat_unlock_n (mptr, n); | |
97 | post_seq_barrier (smodel); | |
98 | } | |
99 | ||
100 | EXPORT_ALIAS (load); |