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
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 __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>
atomic_store(volatile T * a,typename T::Type v,memory_order mo)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