1 //===-- sanitizer_atomic_clang_other.h --------------------------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file is a part of ThreadSanitizer/AddressSanitizer runtime.
10 // Not intended for direct inclusion. Include sanitizer_atomic.h.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #ifndef SANITIZER_ATOMIC_CLANG_OTHER_H
15 #define SANITIZER_ATOMIC_CLANG_OTHER_H
16 
17 namespace __sanitizer {
18 
19 
20 inline void proc_yield(int cnt) {
21   __asm__ __volatile__("" ::: "memory");
22 }
23 
24 template<typename T>
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     __atomic_load(const_cast<typename T::Type volatile *>(&a->val_dont_use), &v,
54                   __ATOMIC_SEQ_CST);
55   }
56   return v;
57 }
58 
59 template<typename T>
60 inline void atomic_store(volatile T *a, typename T::Type v, memory_order mo) {
61   DCHECK(mo & (memory_order_relaxed | memory_order_release
62       | memory_order_seq_cst));
63   DCHECK(!((uptr)a % sizeof(*a)));
64 
65   if (sizeof(*a) < 8 || sizeof(void*) == 8) {
66     // Assume that aligned loads are atomic.
67     if (mo == memory_order_relaxed) {
68       a->val_dont_use = v;
69     } else if (mo == memory_order_release) {
70       __sync_synchronize();
71       a->val_dont_use = v;
72       __asm__ __volatile__("" ::: "memory");
73     } else {  // seq_cst
74       __sync_synchronize();
75       a->val_dont_use = v;
76       __sync_synchronize();
77     }
78   } else {
79     __atomic_store(&a->val_dont_use, &v, __ATOMIC_SEQ_CST);
80   }
81 }
82 
83 }  // namespace __sanitizer
84 
85 #endif  // #ifndef SANITIZER_ATOMIC_CLANG_OTHER_H
86