mirror of
https://github.com/ilyakooo0/urbit.git
synced 2024-12-24 23:44:56 +03:00
27dd121d14
git-subtree-dir: outside/re2 git-subtree-mainline: f94738bfd171ae447133e0964843addbb497894f git-subtree-split: 539b44fc4c5a49c3453b80e3af85d297f4cab4bf
138 lines
3.7 KiB
C
138 lines
3.7 KiB
C
// 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.
|
|
|
|
#if (__clang_major__ * 100 + __clang_minor__ >= 303) || \
|
|
(__GNUC__ * 1000 + __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__)
|
|
|
|
static inline void WriteMemoryBarrier() {
|
|
__asm__ __volatile__("eieio" : : : "memory");
|
|
}
|
|
|
|
#elif defined(__alpha__)
|
|
|
|
static inline void WriteMemoryBarrier() {
|
|
__asm__ __volatile__("wmb" : : : "memory");
|
|
}
|
|
|
|
#elif defined(__aarch64__)
|
|
|
|
static inline void WriteMemoryBarrier() {
|
|
__asm__ __volatile__("dmb st" : : : "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);
|
|
}
|
|
|
|
/*
|
|
#error Need WriteMemoryBarrier for architecture.
|
|
|
|
// Windows
|
|
inline void WriteMemoryBarrier() {
|
|
LONG x;
|
|
::InterlockedExchange(&x, 0);
|
|
}
|
|
*/
|
|
|
|
#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(__aarch64__)
|
|
|
|
static inline void ReadMemoryBarrier() {
|
|
__asm__ __volatile__("dmb ld" : : : "memory");
|
|
}
|
|
|
|
#elif defined(__alpha__)
|
|
|
|
static inline void ReadMemoryBarrier() {
|
|
__asm__ __volatile__("mb" : : : "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__
|