lib/sanitizer_common/sanitizer_atomic_clang.h

//===-- sanitizer_atomic_clang.h --------------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file is a part of ThreadSanitizer/AddressSanitizer runtime.
// Not intended for direct inclusion. Include sanitizer_atomic.h.
//
//===----------------------------------------------------------------------===//

#ifndef SANITIZER_ATOMIC_CLANG_H
#define SANITIZER_ATOMIC_CLANG_H

namespace __sanitizer {

// We use the compiler builtin atomic operations for loads and stores, which
// generates correct code for all architectures, but may require libatomic
// on platforms where e.g. 64-bit atomics are not supported natively.

// See http://www.cl.cam.ac.uk/~pes20/cpp/cpp0xmappings.html
// for mappings of the memory model to different processors.

inline void atomic_signal_fence(memory_order mo) { __atomic_signal_fence(mo); }

inline void atomic_thread_fence(memory_order mo) { __atomic_thread_fence(mo); }

inline void proc_yield(int cnt) {
  __asm__ __volatile__("" ::: "memory");
#if defined(__i386__) || defined(__x86_64__)
  for (int i = 0; i < cnt; i++) __asm__ __volatile__("pause");
  __asm__ __volatile__("" ::: "memory");
#endif
}

template <typename T>
inline typename T::Type atomic_load(const volatile T *a, memory_order mo) {
  DCHECK(mo == memory_order_relaxed || mo == memory_order_consume ||
         mo == memory_order_acquire || mo == memory_order_seq_cst);
  DCHECK(!((uptr)a % sizeof(*a)));
  return __atomic_load_n(&a->val_dont_use, mo);
}

template <typename T>
inline void atomic_store(volatile T *a, typename T::Type v, memory_order mo) {
  DCHECK(mo == memory_order_relaxed || mo == memory_order_release ||
         mo == memory_order_seq_cst);
  DCHECK(!((uptr)a % sizeof(*a)));
  __atomic_store_n(&a->val_dont_use, v, mo);
}

template <typename T>
inline typename T::Type atomic_fetch_add(volatile T *a, typename T::Type v,
                                         memory_order mo) {
  DCHECK(!((uptr)a % sizeof(*a)));
  return __atomic_fetch_add(&a->val_dont_use, v, mo);
}

template <typename T>
inline typename T::Type atomic_fetch_sub(volatile T *a, typename T::Type v,
                                         memory_order mo) {
  (void)mo;
  DCHECK(!((uptr)a % sizeof(*a)));
  return __atomic_fetch_sub(&a->val_dont_use, v, mo);
}

template <typename T>
inline typename T::Type atomic_exchange(volatile T *a, typename T::Type v,
                                        memory_order mo) {
  DCHECK(!((uptr)a % sizeof(*a)));
  return __atomic_exchange_n(&a->val_dont_use, v, mo);
}

template <typename T>
inline bool atomic_compare_exchange_strong(volatile T *a, typename T::Type *cmp,
                                           typename T::Type xchg,
                                           memory_order mo) {
  // Transitioned from __sync_val_compare_and_swap to support targets like
  // SPARC V8 that cannot inline atomic cmpxchg.  __atomic_compare_exchange
  // can then be resolved from libatomic.  __ATOMIC_SEQ_CST is used to best
  // match the __sync builtin memory order.
  return __atomic_compare_exchange(&a->val_dont_use, cmp, &xchg, false,
                                   __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST);
}

template <typename T>
inline bool atomic_compare_exchange_weak(volatile T *a, typename T::Type *cmp,
                                         typename T::Type xchg,
                                         memory_order mo) {
  return atomic_compare_exchange_strong(a, cmp, xchg, mo);
}

}  // namespace __sanitizer

#undef ATOMIC_ORDER

#endif  // SANITIZER_ATOMIC_CLANG_H