1 //===-- sanitizer_atomic_clang_other.h --------------------------*- C++ -*-===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file is a part of ThreadSanitizer/AddressSanitizer runtime.
11 // Not intended for direct inclusion. Include sanitizer_atomic.h.
12 //
13 //===----------------------------------------------------------------------===//
14
15 #ifndef SANITIZER_ATOMIC_CLANG_OTHER_H
16 #define SANITIZER_ATOMIC_CLANG_OTHER_H
17
18 namespace __sanitizer {
19
proc_yield(int cnt)20 INLINE void proc_yield(int cnt) {
21 __asm__ __volatile__("" ::: "memory");
22 }
23
24 template<typename T>
atomic_load(const volatile T * a,memory_order mo)25 INLINE typename T::Type atomic_load(
26 const volatile T *a, memory_order mo) {
27 DCHECK(mo & (memory_order_relaxed | memory_order_consume
28 | memory_order_acquire | memory_order_seq_cst));
29 DCHECK(!((uptr)a % sizeof(*a)));
30 typename T::Type v;
31
32 if (sizeof(*a) < 8 || sizeof(void*) == 8) {
33 // Assume that aligned loads are atomic.
34 if (mo == memory_order_relaxed) {
35 v = a->val_dont_use;
36 } else if (mo == memory_order_consume) {
37 // Assume that processor respects data dependencies
38 // (and that compiler won't break them).
39 __asm__ __volatile__("" ::: "memory");
40 v = a->val_dont_use;
41 __asm__ __volatile__("" ::: "memory");
42 } else if (mo == memory_order_acquire) {
43 __asm__ __volatile__("" ::: "memory");
44 v = a->val_dont_use;
45 __sync_synchronize();
46 } else { // seq_cst
47 // E.g. on POWER we need a hw fence even before the store.
48 __sync_synchronize();
49 v = a->val_dont_use;
50 __sync_synchronize();
51 }
52 } else {
53 // 64-bit load on 32-bit platform.
54 // Gross, but simple and reliable.
55 // Assume that it is not in read-only memory.
56 v = __sync_fetch_and_add(
57 const_cast<typename T::Type volatile *>(&a->val_dont_use), 0);
58 }
59 return v;
60 }
61
62 template<typename T>
atomic_store(volatile T * a,typename T::Type v,memory_order mo)63 INLINE void atomic_store(volatile T *a, typename T::Type v, memory_order mo) {
64 DCHECK(mo & (memory_order_relaxed | memory_order_release
65 | memory_order_seq_cst));
66 DCHECK(!((uptr)a % sizeof(*a)));
67
68 if (sizeof(*a) < 8 || sizeof(void*) == 8) {
69 // Assume that aligned loads are atomic.
70 if (mo == memory_order_relaxed) {
71 a->val_dont_use = v;
72 } else if (mo == memory_order_release) {
73 __sync_synchronize();
74 a->val_dont_use = v;
75 __asm__ __volatile__("" ::: "memory");
76 } else { // seq_cst
77 __sync_synchronize();
78 a->val_dont_use = v;
79 __sync_synchronize();
80 }
81 } else {
82 // 64-bit store on 32-bit platform.
83 // Gross, but simple and reliable.
84 typename T::Type cmp = a->val_dont_use;
85 typename T::Type cur;
86 for (;;) {
87 cur = __sync_val_compare_and_swap(&a->val_dont_use, cmp, v);
88 if (cmp == v)
89 break;
90 cmp = cur;
91 }
92 }
93 }
94
95 } // namespace __sanitizer
96
97 #endif // #ifndef SANITIZER_ATOMIC_CLANG_OTHER_H
98