Replace RE2 import with a dependency

third_party/re2/util/atomicops.h

-// Copyright 2006-2008 The RE2 Authors.  All Rights Reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-#ifndef RE2_UTIL_ATOMICOPS_H__
-#define RE2_UTIL_ATOMICOPS_H__
-
-// The memory ordering constraints resemble the ones in C11.
-// RELAXED - no memory ordering, just an atomic operation.
-// CONSUME - data-dependent ordering.
-// ACQUIRE - prevents memory accesses from hoisting above the operation.
-// RELEASE - prevents memory accesses from sinking below the operation.
-
-#ifndef __has_builtin
-#define __has_builtin(x) 0
-#endif
-
-#if !defined(OS_NACL) && (__has_builtin(__atomic_load_n) || (__GNUC__*10000 + __GNUC_MINOR__*100 + __GNUC_PATCHLEVEL__ >= 40801))
-
-#define ATOMIC_LOAD_RELAXED(x, p) do { (x) = __atomic_load_n((p), __ATOMIC_RELAXED); } while (0)
-#define ATOMIC_LOAD_CONSUME(x, p) do { (x) = __atomic_load_n((p), __ATOMIC_CONSUME); } while (0)
-#define ATOMIC_LOAD_ACQUIRE(x, p) do { (x) = __atomic_load_n((p), __ATOMIC_ACQUIRE); } while (0)
-#define ATOMIC_STORE_RELAXED(p, v) __atomic_store_n((p), (v), __ATOMIC_RELAXED)
-#define ATOMIC_STORE_RELEASE(p, v) __atomic_store_n((p), (v), __ATOMIC_RELEASE)
-
-#else  // old compiler
-
-#define ATOMIC_LOAD_RELAXED(x, p) do { (x) = *(p); } while (0)
-#define ATOMIC_LOAD_CONSUME(x, p) do { (x) = *(p); MaybeReadMemoryBarrier(); } while (0)
-#define ATOMIC_LOAD_ACQUIRE(x, p) do { (x) = *(p); ReadMemoryBarrier(); } while (0)
-#define ATOMIC_STORE_RELAXED(p, v) do { *(p) = (v); } while (0)
-#define ATOMIC_STORE_RELEASE(p, v) do { WriteMemoryBarrier(); *(p) = (v); } while (0)
-
-// WriteMemoryBarrier(), ReadMemoryBarrier() and MaybeReadMemoryBarrier()
-// are an implementation detail and must not be used in the rest of the code.
-
-#if defined(__i386__)
-
-static inline void WriteMemoryBarrier() {
-  int x;
-  __asm__ __volatile__("xchgl (%0),%0"  // The lock prefix is implicit for xchg.
-                       :: "r" (&x));
-}
-
-#elif defined(__x86_64__)
-
-// 64-bit implementations of memory barrier can be simpler, because
-// "sfence" is guaranteed to exist.
-static inline void WriteMemoryBarrier() {
-  __asm__ __volatile__("sfence" : : : "memory");
-}
-
-#elif defined(__ppc__) || defined(__powerpc64__)
-
-static inline void WriteMemoryBarrier() {
-  __asm__ __volatile__("lwsync" : : : "memory");
-}
-
-#elif defined(__aarch64__)
-
-static inline void WriteMemoryBarrier() {
-  __asm__ __volatile__("dmb st" : : : "memory");
-}
-
-#elif defined(__alpha__)
-
-static inline void WriteMemoryBarrier() {
-  __asm__ __volatile__("wmb" : : : "memory");
-}
-
-#elif defined(__arm__) && defined(__linux__)
-
-// Linux on ARM puts a suitable memory barrier at a magic address for us to call.
-static inline void WriteMemoryBarrier() {
-  ((void(*)(void))0xffff0fa0)();
-}
-
-#elif defined(__windows__) || defined(_WIN32)
-
-#include <intrin.h>
-#include <windows.h>
-
-static inline void WriteMemoryBarrier() {
-#if defined(_M_IX86) || defined(_M_X64)
-  // x86 and x64 CPUs have a strong memory model that prohibits most types of
-  // reordering, so a non-instruction intrinsic to suppress compiler reordering
-  // is sufficient. _WriteBarrier is deprecated, but is still appropriate for
-  // the "old compiler" path (pre C++11).
-  _WriteBarrier();
-#else
-  LONG x;
-  ::InterlockedExchange(&x, 0);
-#endif
-}
-
-#elif defined(OS_NACL)
-
-static inline void WriteMemoryBarrier() {
-  __sync_synchronize();
-}
-
-#elif defined(__mips__)
-
-static inline void WriteMemoryBarrier() {
-  __asm__ __volatile__("sync" : : : "memory");
-}
-
-#else
-
-#include "util/mutex.h"
-
-static inline void WriteMemoryBarrier() {
-  // Slight overkill, but good enough:
-  // any mutex implementation must have
-  // a read barrier after the lock operation and
-  // a write barrier before the unlock operation.
-  //
-  // It may be worthwhile to write architecture-specific
-  // barriers for the common platforms, as above, but
-  // this is a correct fallback.
-  re2::Mutex mu;
-  re2::MutexLock l(&mu);
-}
-
-#endif
-
-// Alpha has very weak memory ordering. If relying on WriteBarriers, one must
-// use read barriers for the readers too.
-#if defined(__alpha__)
-
-static inline void MaybeReadMemoryBarrier() {
-  __asm__ __volatile__("mb" : : : "memory");
-}
-
-#else
-
-static inline void MaybeReadMemoryBarrier() {}
-
-#endif  // __alpha__
-
-// Read barrier for various targets.
-
-#if defined(__ppc__) || defined(__powerpc64__)
-
-static inline void ReadMemoryBarrier() {
-  __asm__ __volatile__("lwsync" : : : "memory");
-}
-
-#elif defined(__aarch64__)
-
-static inline void ReadMemoryBarrier() {
-  __asm__ __volatile__("dmb ld" : : : "memory");
-}
-
-#elif defined(__alpha__)
-
-static inline void ReadMemoryBarrier() {
-  __asm__ __volatile__("mb" : : : "memory");
-}
-
-#elif defined(__mips__)
-
-static inline void ReadMemoryBarrier() {
-  __asm__ __volatile__("sync" : : : "memory");
-}
-
-#else
-
-static inline void ReadMemoryBarrier() {}
-
-#endif
-
-#endif  // old compiler
-
-#ifndef NO_THREAD_SAFETY_ANALYSIS
-#define NO_THREAD_SAFETY_ANALYSIS
-#endif
-
-#endif  // RE2_UTIL_ATOMICOPS_H__