#ifndef Atomics_h
#define Atomics_h
#include <atomic>
#include <wtf/StdLibExtras.h>
#if OS(WINDOWS)
#if !COMPILER(GCC_OR_CLANG)
extern "C" void _ReadWriteBarrier(void);
#pragma intrinsic(_ReadWriteBarrier)
#endif
#include <windows.h>
#include <intrin.h>
#endif
namespace WTF {
ALWAYS_INLINE bool hasFence(std::memory_order order)
{
return order != std::memory_order_relaxed;
}
template<typename T>
struct Atomic {
ALWAYS_INLINE T load(std::memory_order order = std::memory_order_seq_cst) const { return value.load(order); }
ALWAYS_INLINE T loadRelaxed() const { return load(std::memory_order_relaxed); }
ALWAYS_INLINE T loadFullyFenced() const
{
Atomic<T>* ptr = const_cast<Atomic<T>*>(this);
return ptr->exchangeAdd(T());
}
ALWAYS_INLINE void store(T desired, std::memory_order order = std::memory_order_seq_cst) { value.store(desired, order); }
ALWAYS_INLINE void storeRelaxed(T desired) { store(desired, std::memory_order_relaxed); }
ALWAYS_INLINE void storeFullyFenced(T desired)
{
exchange(desired);
}
ALWAYS_INLINE bool compareExchangeWeak(T expected, T desired, std::memory_order order = std::memory_order_seq_cst)
{
T expectedOrActual = expected;
return value.compare_exchange_weak(expectedOrActual, desired, order);
}
ALWAYS_INLINE bool compareExchangeWeakRelaxed(T expected, T desired)
{
return compareExchangeWeak(expected, desired, std::memory_order_relaxed);
}
ALWAYS_INLINE bool compareExchangeWeak(T expected, T desired, std::memory_order order_success, std::memory_order order_failure)
{
T expectedOrActual = expected;
return value.compare_exchange_weak(expectedOrActual, desired, order_success, order_failure);
}
ALWAYS_INLINE T compareExchangeStrong(T expected, T desired, std::memory_order order = std::memory_order_seq_cst)
{
T expectedOrActual = expected;
value.compare_exchange_strong(expectedOrActual, desired, order);
return expectedOrActual;
}
ALWAYS_INLINE T compareExchangeStrong(T expected, T desired, std::memory_order order_success, std::memory_order order_failure)
{
T expectedOrActual = expected;
value.compare_exchange_strong(expectedOrActual, desired, order_success, order_failure);
return expectedOrActual;
}
template<typename U>
ALWAYS_INLINE T exchangeAdd(U operand, std::memory_order order = std::memory_order_seq_cst) { return value.fetch_add(operand, order); }
template<typename U>
ALWAYS_INLINE T exchangeAnd(U operand, std::memory_order order = std::memory_order_seq_cst) { return value.fetch_and(operand, order); }
template<typename U>
ALWAYS_INLINE T exchangeOr(U operand, std::memory_order order = std::memory_order_seq_cst) { return value.fetch_or(operand, order); }
template<typename U>
ALWAYS_INLINE T exchangeSub(U operand, std::memory_order order = std::memory_order_seq_cst) { return value.fetch_sub(operand, order); }
template<typename U>
ALWAYS_INLINE T exchangeXor(U operand, std::memory_order order = std::memory_order_seq_cst) { return value.fetch_xor(operand, order); }
ALWAYS_INLINE T exchange(T newValue, std::memory_order order = std::memory_order_seq_cst) { return value.exchange(newValue, order); }
template<typename Func>
ALWAYS_INLINE bool transaction(const Func& func, std::memory_order order = std::memory_order_seq_cst)
{
for (;;) {
T oldValue = load(std::memory_order_relaxed);
T newValue = oldValue;
if (!func(newValue))
return false;
if (compareExchangeWeak(oldValue, newValue, order))
return true;
}
}
template<typename Func>
ALWAYS_INLINE bool transactionRelaxed(const Func& func)
{
return transaction(func, std::memory_order_relaxed);
}
Atomic() = default;
constexpr Atomic(T initial)
: value(std::forward<T>(initial))
{
}
std::atomic<T> value;
};
template<typename T>
inline T atomicLoad(T* location, std::memory_order order = std::memory_order_seq_cst)
{
return bitwise_cast<Atomic<T>*>(location)->load(order);
}
template<typename T>
inline T atomicLoadFullyFenced(T* location)
{
return bitwise_cast<Atomic<T>*>(location)->loadFullyFenced();
}
template<typename T>
inline void atomicStore(T* location, T newValue, std::memory_order order = std::memory_order_seq_cst)
{
bitwise_cast<Atomic<T>*>(location)->store(newValue, order);
}
template<typename T>
inline void atomicStoreFullyFenced(T* location, T newValue)
{
bitwise_cast<Atomic<T>*>(location)->storeFullyFenced(newValue);
}
template<typename T>
inline bool atomicCompareExchangeWeak(T* location, T expected, T newValue, std::memory_order order = std::memory_order_seq_cst)
{
return bitwise_cast<Atomic<T>*>(location)->compareExchangeWeak(expected, newValue, order);
}
template<typename T>
inline bool atomicCompareExchangeWeakRelaxed(T* location, T expected, T newValue)
{
return bitwise_cast<Atomic<T>*>(location)->compareExchangeWeakRelaxed(expected, newValue);
}
template<typename T>
inline T atomicCompareExchangeStrong(T* location, T expected, T newValue, std::memory_order order = std::memory_order_seq_cst)
{
return bitwise_cast<Atomic<T>*>(location)->compareExchangeStrong(expected, newValue, order);
}
template<typename T, typename U>
inline T atomicExchangeAdd(T* location, U operand, std::memory_order order = std::memory_order_seq_cst)
{
return bitwise_cast<Atomic<T>*>(location)->exchangeAdd(operand, order);
}
template<typename T, typename U>
inline T atomicExchangeAnd(T* location, U operand, std::memory_order order = std::memory_order_seq_cst)
{
return bitwise_cast<Atomic<T>*>(location)->exchangeAnd(operand, order);
}
template<typename T, typename U>
inline T atomicExchangeOr(T* location, U operand, std::memory_order order = std::memory_order_seq_cst)
{
return bitwise_cast<Atomic<T>*>(location)->exchangeOr(operand, order);
}
template<typename T, typename U>
inline T atomicExchangeSub(T* location, U operand, std::memory_order order = std::memory_order_seq_cst)
{
return bitwise_cast<Atomic<T>*>(location)->exchangeSub(operand, order);
}
template<typename T, typename U>
inline T atomicExchangeXor(T* location, U operand, std::memory_order order = std::memory_order_seq_cst)
{
return bitwise_cast<Atomic<T>*>(location)->exchangeXor(operand, order);
}
template<typename T>
inline T atomicExchange(T* location, T newValue, std::memory_order order = std::memory_order_seq_cst)
{
return bitwise_cast<Atomic<T>*>(location)->exchange(newValue, order);
}
inline void compilerFence()
{
#if OS(WINDOWS) && !COMPILER(GCC_OR_CLANG)
_ReadWriteBarrier();
#else
asm volatile("" ::: "memory");
#endif
}
#if CPU(ARM_THUMB2) || CPU(ARM64)
inline void arm_dmb()
{
asm volatile("dmb ish" ::: "memory");
}
inline void arm_dmb_st()
{
asm volatile("dmb ishst" ::: "memory");
}
inline void arm_isb()
{
asm volatile("isb" ::: "memory");
}
inline void loadLoadFence() { arm_dmb(); }
inline void loadStoreFence() { arm_dmb(); }
inline void storeLoadFence() { arm_dmb(); }
inline void storeStoreFence() { arm_dmb_st(); }
inline void memoryBarrierAfterLock() { arm_dmb(); }
inline void memoryBarrierBeforeUnlock() { arm_dmb(); }
inline void crossModifyingCodeFence() { arm_isb(); }
inline void speculationFence() { arm_isb(); }
#elif CPU(X86) || CPU(X86_64)
inline void x86_lfence()
{
#if !OS(WINDOWS)
asm volatile("lfence" ::: "memory");
#endif
}
inline void x86_ortop()
{
#if OS(WINDOWS)
MemoryBarrier();
#elif CPU(X86_64)
asm volatile("lock; orl $0, (%%rsp)" ::: "memory");
#else
asm volatile("lock; orl $0, (%%esp)" ::: "memory");
#endif
}
inline void x86_cpuid()
{
#if OS(WINDOWS)
int info[4];
__cpuid(info, 0);
#else
intptr_t a = 0, b, c, d;
asm volatile(
"cpuid"
: "+a"(a), "=b"(b), "=c"(c), "=d"(d)
:
: "memory");
#endif
}
inline void loadLoadFence() { compilerFence(); }
inline void loadStoreFence() { compilerFence(); }
inline void storeLoadFence() { x86_ortop(); }
inline void storeStoreFence() { compilerFence(); }
inline void memoryBarrierAfterLock() { compilerFence(); }
inline void memoryBarrierBeforeUnlock() { compilerFence(); }
inline void crossModifyingCodeFence() { x86_cpuid(); }
inline void speculationFence() { x86_lfence(); }
#else
inline void loadLoadFence() { std::atomic_thread_fence(std::memory_order_seq_cst); }
inline void loadStoreFence() { std::atomic_thread_fence(std::memory_order_seq_cst); }
inline void storeLoadFence() { std::atomic_thread_fence(std::memory_order_seq_cst); }
inline void storeStoreFence() { std::atomic_thread_fence(std::memory_order_seq_cst); }
inline void memoryBarrierAfterLock() { std::atomic_thread_fence(std::memory_order_seq_cst); }
inline void memoryBarrierBeforeUnlock() { std::atomic_thread_fence(std::memory_order_seq_cst); }
inline void crossModifyingCodeFence() { std::atomic_thread_fence(std::memory_order_seq_cst); } inline void speculationFence() { }
#endif
typedef unsigned InternalDependencyType;
inline InternalDependencyType opaqueMixture()
{
return 0;
}
template<typename... Arguments, typename T>
inline InternalDependencyType opaqueMixture(T value, Arguments... arguments)
{
union {
InternalDependencyType copy;
T value;
} u;
u.copy = 0;
u.value = value;
return opaqueMixture(arguments...) + u.copy;
}
class Dependency {
public:
Dependency()
: m_value(0)
{
}
template<typename... Arguments>
static Dependency fence(Arguments... arguments)
{
InternalDependencyType input = opaqueMixture(arguments...);
InternalDependencyType output;
#if CPU(ARM64)
asm("eor %w[out], %w[in], %w[in]"
: [out] "=r"(output)
: [in] "r"(input));
#elif CPU(ARM)
asm("eor %[out], %[in], %[in]"
: [out] "=r"(output)
: [in] "r"(input));
#else
loadLoadFence();
output = 0;
UNUSED_PARAM(input);
#endif
Dependency result;
result.m_value = output;
return result;
}
template<typename T>
T* consume(T* pointer)
{
#if CPU(ARM64) || CPU(ARM)
return bitwise_cast<T*>(bitwise_cast<char*>(pointer) + m_value);
#else
UNUSED_PARAM(m_value);
return pointer;
#endif
}
private:
InternalDependencyType m_value;
};
template<typename InputType, typename ValueType>
struct InputAndValue {
InputAndValue() { }
InputAndValue(InputType input, ValueType value)
: input(input)
, value(value)
{
}
InputType input;
ValueType value;
};
template<typename InputType, typename ValueType>
InputAndValue<InputType, ValueType> inputAndValue(InputType input, ValueType value)
{
return InputAndValue<InputType, ValueType>(input, value);
}
template<typename T, typename Func>
ALWAYS_INLINE T& ensurePointer(Atomic<T*>& pointer, const Func& func)
{
for (;;) {
T* oldValue = pointer.load(std::memory_order_relaxed);
if (oldValue) {
return *oldValue;
}
T* newValue = func();
if (pointer.compareExchangeWeak(oldValue, newValue))
return *newValue;
delete newValue;
}
}
}
using WTF::Atomic;
using WTF::Dependency;
using WTF::InputAndValue;
using WTF::inputAndValue;
using WTF::ensurePointer;
using WTF::opaqueMixture;
#endif // Atomics_h