libsanitizer/sanitizer_common/sanitizer_atomic_clang_other.h

   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