1//===-- sanitizer_atomic_clang.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_H
15#define SANITIZER_ATOMIC_CLANG_H
16
17#if defined(__i386__) || defined(__x86_64__)
18# include "sanitizer_atomic_clang_x86.h"
19#else
20# include "sanitizer_atomic_clang_other.h"
21#endif
22
23namespace __sanitizer {
24
25// We would like to just use compiler builtin atomic operations
26// for loads and stores, but they are mostly broken in clang:
27// - they lead to vastly inefficient code generation
28// (http://llvm.org/bugs/show_bug.cgi?id=17281)
29// - 64-bit atomic operations are not implemented on x86_32
30// (http://llvm.org/bugs/show_bug.cgi?id=15034)
31// - they are not implemented on ARM
32// error: undefined reference to '__atomic_load_4'
33
34// See http://www.cl.cam.ac.uk/~pes20/cpp/cpp0xmappings.html
35// for mappings of the memory model to different processors.
36
37INLINE void atomic_signal_fence(memory_order) {
38  __asm__ __volatile__("" ::: "memory");
39}
40
41INLINE void atomic_thread_fence(memory_order) {
42  __sync_synchronize();
43}
44
45template<typename T>
46INLINE typename T::Type atomic_fetch_add(volatile T *a,
47    typename T::Type v, memory_order mo) {
48  (void)mo;
49  DCHECK(!((uptr)a % sizeof(*a)));
50  return __sync_fetch_and_add(&a->val_dont_use, v);
51}
52
53template<typename T>
54INLINE typename T::Type atomic_fetch_sub(volatile T *a,
55    typename T::Type v, memory_order mo) {
56  (void)mo;
57  DCHECK(!((uptr)a % sizeof(*a)));
58  return __sync_fetch_and_add(&a->val_dont_use, -v);
59}
60
61template<typename T>
62INLINE typename T::Type atomic_exchange(volatile T *a,
63    typename T::Type v, memory_order mo) {
64  DCHECK(!((uptr)a % sizeof(*a)));
65  if (mo & (memory_order_release | memory_order_acq_rel | memory_order_seq_cst))
66    __sync_synchronize();
67  v = __sync_lock_test_and_set(&a->val_dont_use, v);
68  if (mo == memory_order_seq_cst)
69    __sync_synchronize();
70  return v;
71}
72
73template <typename T>
74INLINE bool atomic_compare_exchange_strong(volatile T *a, typename T::Type *cmp,
75                                           typename T::Type xchg,
76                                           memory_order mo) {
77  typedef typename T::Type Type;
78  Type cmpv = *cmp;
79  Type prev;
80  prev = __sync_val_compare_and_swap(&a->val_dont_use, cmpv, xchg);
81  if (prev == cmpv) return true;
82  *cmp = prev;
83  return false;
84}
85
86template<typename T>
87INLINE bool atomic_compare_exchange_weak(volatile T *a,
88                                         typename T::Type *cmp,
89                                         typename T::Type xchg,
90                                         memory_order mo) {
91  return atomic_compare_exchange_strong(a, cmp, xchg, mo);
92}
93
94}  // namespace __sanitizer
95
96// This include provides explicit template instantiations for atomic_uint64_t
97// on MIPS32, which does not directly support 8 byte atomics. It has to
98// proceed the template definitions above.
99#if defined(_MIPS_SIM) && defined(_ABIO32)
100  #include "sanitizer_atomic_clang_mips.h"
101#endif
102
103#undef ATOMIC_ORDER
104
105#endif  // SANITIZER_ATOMIC_CLANG_H
106