sanitizer_atomic_clang_other.h revision 2d1fdb26e458c4ddc04155c1d421bced3ba90cd0 
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
18namespace __sanitizer {
19
20INLINE void proc_yield(int cnt) {
21  __asm__ __volatile__("" ::: "memory");
22}
23
24template<typename T>
25INLINE 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
62template<typename T>
63INLINE 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