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/* ----------------------------------------------------------------------------
Copyright (c) 2018-2023 Microsoft Research, Daan Leijen
This is free software; you can redistribute it and/or modify it under the
terms of the MIT license. A copy of the license can be found in the file
"LICENSE" at the root of this distribution.
-----------------------------------------------------------------------------*/
#pragma once
#ifndef MIMALLOC_ATOMIC_H
#define MIMALLOC_ATOMIC_H
// --------------------------------------------------------------------------------------------
// Atomics
// We need to be portable between C, C++, and MSVC.
// We base the primitives on the C/C++ atomics and create a minimal wrapper for MSVC in C compilation mode.
// This is why we try to use only `uintptr_t` and `<type>*` as atomic types.
// To gain better insight in the range of used atomics, we use explicitly named memory order operations
// instead of passing the memory order as a parameter.
// -----------------------------------------------------------------------------------------------
#if defined(__cplusplus)
// Use C++ atomics
#include <atomic>
#define _Atomic(tp) std::atomic<tp>
#define mi_atomic(name) std::atomic_##name
#define mi_memory_order(name) std::memory_order_##name
#if (__cplusplus >= 202002L) // c++20, see issue #571
#define MI_ATOMIC_VAR_INIT(x) x
#elif !defined(ATOMIC_VAR_INIT)
#define MI_ATOMIC_VAR_INIT(x) x
#else
#define MI_ATOMIC_VAR_INIT(x) ATOMIC_VAR_INIT(x)
#endif
#elif defined(_MSC_VER)
// Use MSVC C wrapper for C11 atomics
#define _Atomic(tp) tp
#define MI_ATOMIC_VAR_INIT(x) x
#define mi_atomic(name) mi_atomic_##name
#define mi_memory_order(name) mi_memory_order_##name
#else
// Use C11 atomics
#include <stdatomic.h>
#define mi_atomic(name) atomic_##name
#define mi_memory_order(name) memory_order_##name
#if (__STDC_VERSION__ >= 201710L) // c17, see issue #735
#define MI_ATOMIC_VAR_INIT(x) x
#elif !defined(ATOMIC_VAR_INIT)
#define MI_ATOMIC_VAR_INIT(x) x
#else
#define MI_ATOMIC_VAR_INIT(x) ATOMIC_VAR_INIT(x)
#endif
#endif
// Various defines for all used memory orders in mimalloc
#define mi_atomic_cas_weak(p,expected,desired,mem_success,mem_fail) \
mi_atomic(compare_exchange_weak_explicit)(p,expected,desired,mem_success,mem_fail)
#define mi_atomic_cas_strong(p,expected,desired,mem_success,mem_fail) \
mi_atomic(compare_exchange_strong_explicit)(p,expected,desired,mem_success,mem_fail)
#define mi_atomic_load_acquire(p) mi_atomic(load_explicit)(p,mi_memory_order(acquire))
#define mi_atomic_load_relaxed(p) mi_atomic(load_explicit)(p,mi_memory_order(relaxed))
#define mi_atomic_store_release(p,x) mi_atomic(store_explicit)(p,x,mi_memory_order(release))
#define mi_atomic_store_relaxed(p,x) mi_atomic(store_explicit)(p,x,mi_memory_order(relaxed))
#define mi_atomic_exchange_release(p,x) mi_atomic(exchange_explicit)(p,x,mi_memory_order(release))
#define mi_atomic_exchange_acq_rel(p,x) mi_atomic(exchange_explicit)(p,x,mi_memory_order(acq_rel))
#define mi_atomic_cas_weak_release(p,exp,des) mi_atomic_cas_weak(p,exp,des,mi_memory_order(release),mi_memory_order(relaxed))
#define mi_atomic_cas_weak_acq_rel(p,exp,des) mi_atomic_cas_weak(p,exp,des,mi_memory_order(acq_rel),mi_memory_order(acquire))
#define mi_atomic_cas_strong_release(p,exp,des) mi_atomic_cas_strong(p,exp,des,mi_memory_order(release),mi_memory_order(relaxed))
#define mi_atomic_cas_strong_acq_rel(p,exp,des) mi_atomic_cas_strong(p,exp,des,mi_memory_order(acq_rel),mi_memory_order(acquire))
#define mi_atomic_add_relaxed(p,x) mi_atomic(fetch_add_explicit)(p,x,mi_memory_order(relaxed))
#define mi_atomic_sub_relaxed(p,x) mi_atomic(fetch_sub_explicit)(p,x,mi_memory_order(relaxed))
#define mi_atomic_add_acq_rel(p,x) mi_atomic(fetch_add_explicit)(p,x,mi_memory_order(acq_rel))
#define mi_atomic_sub_acq_rel(p,x) mi_atomic(fetch_sub_explicit)(p,x,mi_memory_order(acq_rel))
#define mi_atomic_and_acq_rel(p,x) mi_atomic(fetch_and_explicit)(p,x,mi_memory_order(acq_rel))
#define mi_atomic_or_acq_rel(p,x) mi_atomic(fetch_or_explicit)(p,x,mi_memory_order(acq_rel))
#define mi_atomic_increment_relaxed(p) mi_atomic_add_relaxed(p,(uintptr_t)1)
#define mi_atomic_decrement_relaxed(p) mi_atomic_sub_relaxed(p,(uintptr_t)1)
#define mi_atomic_increment_acq_rel(p) mi_atomic_add_acq_rel(p,(uintptr_t)1)
#define mi_atomic_decrement_acq_rel(p) mi_atomic_sub_acq_rel(p,(uintptr_t)1)
static inline void mi_atomic_yield(void);
static inline intptr_t mi_atomic_addi(_Atomic(intptr_t)*p, intptr_t add);
static inline intptr_t mi_atomic_subi(_Atomic(intptr_t)*p, intptr_t sub);
#if defined(__cplusplus) || !defined(_MSC_VER)
// In C++/C11 atomics we have polymorphic atomics so can use the typed `ptr` variants (where `tp` is the type of atomic value)
// We use these macros so we can provide a typed wrapper in MSVC in C compilation mode as well
#define mi_atomic_load_ptr_acquire(tp,p) mi_atomic_load_acquire(p)
#define mi_atomic_load_ptr_relaxed(tp,p) mi_atomic_load_relaxed(p)
// In C++ we need to add casts to help resolve templates if NULL is passed
#if defined(__cplusplus)
#define mi_atomic_store_ptr_release(tp,p,x) mi_atomic_store_release(p,(tp*)x)
#define mi_atomic_store_ptr_relaxed(tp,p,x) mi_atomic_store_relaxed(p,(tp*)x)
#define mi_atomic_cas_ptr_weak_release(tp,p,exp,des) mi_atomic_cas_weak_release(p,exp,(tp*)des)
#define mi_atomic_cas_ptr_weak_acq_rel(tp,p,exp,des) mi_atomic_cas_weak_acq_rel(p,exp,(tp*)des)
#define mi_atomic_cas_ptr_strong_release(tp,p,exp,des) mi_atomic_cas_strong_release(p,exp,(tp*)des)
#define mi_atomic_exchange_ptr_release(tp,p,x) mi_atomic_exchange_release(p,(tp*)x)
#define mi_atomic_exchange_ptr_acq_rel(tp,p,x) mi_atomic_exchange_acq_rel(p,(tp*)x)
#else
#define mi_atomic_store_ptr_release(tp,p,x) mi_atomic_store_release(p,x)
#define mi_atomic_store_ptr_relaxed(tp,p,x) mi_atomic_store_relaxed(p,x)
#define mi_atomic_cas_ptr_weak_release(tp,p,exp,des) mi_atomic_cas_weak_release(p,exp,des)
#define mi_atomic_cas_ptr_weak_acq_rel(tp,p,exp,des) mi_atomic_cas_weak_acq_rel(p,exp,des)
#define mi_atomic_cas_ptr_strong_release(tp,p,exp,des) mi_atomic_cas_strong_release(p,exp,des)
#define mi_atomic_exchange_ptr_release(tp,p,x) mi_atomic_exchange_release(p,x)
#define mi_atomic_exchange_ptr_acq_rel(tp,p,x) mi_atomic_exchange_acq_rel(p,x)
#endif
// These are used by the statistics
static inline int64_t mi_atomic_addi64_relaxed(volatile int64_t* p, int64_t add) {
return mi_atomic(fetch_add_explicit)((_Atomic(int64_t)*)p, add, mi_memory_order(relaxed));
}
static inline void mi_atomic_maxi64_relaxed(volatile int64_t* p, int64_t x) {
int64_t current = mi_atomic_load_relaxed((_Atomic(int64_t)*)p);
while (current < x && !mi_atomic_cas_weak_release((_Atomic(int64_t)*)p, ¤t, x)) { /* nothing */ };
}
// Used by timers
#define mi_atomic_loadi64_acquire(p) mi_atomic(load_explicit)(p,mi_memory_order(acquire))
#define mi_atomic_loadi64_relaxed(p) mi_atomic(load_explicit)(p,mi_memory_order(relaxed))
#define mi_atomic_storei64_release(p,x) mi_atomic(store_explicit)(p,x,mi_memory_order(release))
#define mi_atomic_storei64_relaxed(p,x) mi_atomic(store_explicit)(p,x,mi_memory_order(relaxed))
#define mi_atomic_casi64_strong_acq_rel(p,e,d) mi_atomic_cas_strong_acq_rel(p,e,d)
#define mi_atomic_addi64_acq_rel(p,i) mi_atomic_add_acq_rel(p,i)
#elif defined(_MSC_VER)
// MSVC C compilation wrapper that uses Interlocked operations to model C11 atomics.
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#include <intrin.h>
#ifdef _WIN64
typedef LONG64 msc_intptr_t;
#define MI_64(f) f##64
#else
typedef LONG msc_intptr_t;
#define MI_64(f) f
#endif
typedef enum mi_memory_order_e {
mi_memory_order_relaxed,
mi_memory_order_consume,
mi_memory_order_acquire,
mi_memory_order_release,
mi_memory_order_acq_rel,
mi_memory_order_seq_cst
} mi_memory_order;
static inline uintptr_t mi_atomic_fetch_add_explicit(_Atomic(uintptr_t)*p, uintptr_t add, mi_memory_order mo) {
(void)(mo);
return (uintptr_t)MI_64(_InterlockedExchangeAdd)((volatile msc_intptr_t*)p, (msc_intptr_t)add);
}
static inline uintptr_t mi_atomic_fetch_sub_explicit(_Atomic(uintptr_t)*p, uintptr_t sub, mi_memory_order mo) {
(void)(mo);
return (uintptr_t)MI_64(_InterlockedExchangeAdd)((volatile msc_intptr_t*)p, -((msc_intptr_t)sub));
}
static inline uintptr_t mi_atomic_fetch_and_explicit(_Atomic(uintptr_t)*p, uintptr_t x, mi_memory_order mo) {
(void)(mo);
return (uintptr_t)MI_64(_InterlockedAnd)((volatile msc_intptr_t*)p, (msc_intptr_t)x);
}
static inline uintptr_t mi_atomic_fetch_or_explicit(_Atomic(uintptr_t)*p, uintptr_t x, mi_memory_order mo) {
(void)(mo);
return (uintptr_t)MI_64(_InterlockedOr)((volatile msc_intptr_t*)p, (msc_intptr_t)x);
}
static inline bool mi_atomic_compare_exchange_strong_explicit(_Atomic(uintptr_t)*p, uintptr_t* expected, uintptr_t desired, mi_memory_order mo1, mi_memory_order mo2) {
(void)(mo1); (void)(mo2);
uintptr_t read = (uintptr_t)MI_64(_InterlockedCompareExchange)((volatile msc_intptr_t*)p, (msc_intptr_t)desired, (msc_intptr_t)(*expected));
if (read == *expected) {
return true;
}
else {
*expected = read;
return false;
}
}
static inline bool mi_atomic_compare_exchange_weak_explicit(_Atomic(uintptr_t)*p, uintptr_t* expected, uintptr_t desired, mi_memory_order mo1, mi_memory_order mo2) {
return mi_atomic_compare_exchange_strong_explicit(p, expected, desired, mo1, mo2);
}
static inline uintptr_t mi_atomic_exchange_explicit(_Atomic(uintptr_t)*p, uintptr_t exchange, mi_memory_order mo) {
(void)(mo);
return (uintptr_t)MI_64(_InterlockedExchange)((volatile msc_intptr_t*)p, (msc_intptr_t)exchange);
}
static inline void mi_atomic_thread_fence(mi_memory_order mo) {
(void)(mo);
_Atomic(uintptr_t) x = 0;
mi_atomic_exchange_explicit(&x, 1, mo);
}
static inline uintptr_t mi_atomic_load_explicit(_Atomic(uintptr_t) const* p, mi_memory_order mo) {
(void)(mo);
#if defined(_M_IX86) || defined(_M_X64)
return *p;
#else
uintptr_t x = *p;
if (mo > mi_memory_order_relaxed) {
while (!mi_atomic_compare_exchange_weak_explicit((_Atomic(uintptr_t)*)p, &x, x, mo, mi_memory_order_relaxed)) { /* nothing */ };
}
return x;
#endif
}
static inline void mi_atomic_store_explicit(_Atomic(uintptr_t)*p, uintptr_t x, mi_memory_order mo) {
(void)(mo);
#if defined(_M_IX86) || defined(_M_X64)
*p = x;
#else
mi_atomic_exchange_explicit(p, x, mo);
#endif
}
static inline int64_t mi_atomic_loadi64_explicit(_Atomic(int64_t)*p, mi_memory_order mo) {
(void)(mo);
#if defined(_M_X64)
return *p;
#else
int64_t old = *p;
int64_t x = old;
while ((old = InterlockedCompareExchange64(p, x, old)) != x) {
x = old;
}
return x;
#endif
}
static inline void mi_atomic_storei64_explicit(_Atomic(int64_t)*p, int64_t x, mi_memory_order mo) {
(void)(mo);
#if defined(x_M_IX86) || defined(_M_X64)
*p = x;
#else
InterlockedExchange64(p, x);
#endif
}
// These are used by the statistics
static inline int64_t mi_atomic_addi64_relaxed(volatile _Atomic(int64_t)*p, int64_t add) {
#ifdef _WIN64
return (int64_t)mi_atomic_addi((int64_t*)p, add);
#else
int64_t current;
int64_t sum;
do {
current = *p;
sum = current + add;
} while (_InterlockedCompareExchange64(p, sum, current) != current);
return current;
#endif
}
static inline void mi_atomic_maxi64_relaxed(volatile _Atomic(int64_t)*p, int64_t x) {
int64_t current;
do {
current = *p;
} while (current < x && _InterlockedCompareExchange64(p, x, current) != current);
}
static inline void mi_atomic_addi64_acq_rel(volatile _Atomic(int64_t*)p, int64_t i) {
mi_atomic_addi64_relaxed(p, i);
}
static inline bool mi_atomic_casi64_strong_acq_rel(volatile _Atomic(int64_t*)p, int64_t* exp, int64_t des) {
int64_t read = _InterlockedCompareExchange64(p, des, *exp);
if (read == *exp) {
return true;
}
else {
*exp = read;
return false;
}
}
// The pointer macros cast to `uintptr_t`.
#define mi_atomic_load_ptr_acquire(tp,p) (tp*)mi_atomic_load_acquire((_Atomic(uintptr_t)*)(p))
#define mi_atomic_load_ptr_relaxed(tp,p) (tp*)mi_atomic_load_relaxed((_Atomic(uintptr_t)*)(p))
#define mi_atomic_store_ptr_release(tp,p,x) mi_atomic_store_release((_Atomic(uintptr_t)*)(p),(uintptr_t)(x))
#define mi_atomic_store_ptr_relaxed(tp,p,x) mi_atomic_store_relaxed((_Atomic(uintptr_t)*)(p),(uintptr_t)(x))
#define mi_atomic_cas_ptr_weak_release(tp,p,exp,des) mi_atomic_cas_weak_release((_Atomic(uintptr_t)*)(p),(uintptr_t*)exp,(uintptr_t)des)
#define mi_atomic_cas_ptr_weak_acq_rel(tp,p,exp,des) mi_atomic_cas_weak_acq_rel((_Atomic(uintptr_t)*)(p),(uintptr_t*)exp,(uintptr_t)des)
#define mi_atomic_cas_ptr_strong_release(tp,p,exp,des) mi_atomic_cas_strong_release((_Atomic(uintptr_t)*)(p),(uintptr_t*)exp,(uintptr_t)des)
#define mi_atomic_exchange_ptr_release(tp,p,x) (tp*)mi_atomic_exchange_release((_Atomic(uintptr_t)*)(p),(uintptr_t)x)
#define mi_atomic_exchange_ptr_acq_rel(tp,p,x) (tp*)mi_atomic_exchange_acq_rel((_Atomic(uintptr_t)*)(p),(uintptr_t)x)
#define mi_atomic_loadi64_acquire(p) mi_atomic(loadi64_explicit)(p,mi_memory_order(acquire))
#define mi_atomic_loadi64_relaxed(p) mi_atomic(loadi64_explicit)(p,mi_memory_order(relaxed))
#define mi_atomic_storei64_release(p,x) mi_atomic(storei64_explicit)(p,x,mi_memory_order(release))
#define mi_atomic_storei64_relaxed(p,x) mi_atomic(storei64_explicit)(p,x,mi_memory_order(relaxed))
#endif
// Atomically add a signed value; returns the previous value.
static inline intptr_t mi_atomic_addi(_Atomic(intptr_t)*p, intptr_t add) {
return (intptr_t)mi_atomic_add_acq_rel((_Atomic(uintptr_t)*)p, (uintptr_t)add);
}
// Atomically subtract a signed value; returns the previous value.
static inline intptr_t mi_atomic_subi(_Atomic(intptr_t)*p, intptr_t sub) {
return (intptr_t)mi_atomic_addi(p, -sub);
}
typedef _Atomic(uintptr_t) mi_atomic_once_t;
// Returns true only on the first invocation
static inline bool mi_atomic_once( mi_atomic_once_t* once ) {
if (mi_atomic_load_relaxed(once) != 0) return false; // quick test
uintptr_t expected = 0;
return mi_atomic_cas_strong_acq_rel(once, &expected, (uintptr_t)1); // try to set to 1
}
typedef _Atomic(uintptr_t) mi_atomic_guard_t;
// Allows only one thread to execute at a time
#define mi_atomic_guard(guard) \
uintptr_t _mi_guard_expected = 0; \
for(bool _mi_guard_once = true; \
_mi_guard_once && mi_atomic_cas_strong_acq_rel(guard,&_mi_guard_expected,(uintptr_t)1); \
(mi_atomic_store_release(guard,(uintptr_t)0), _mi_guard_once = false) )
// Yield
#if defined(__cplusplus)
#include <thread>
static inline void mi_atomic_yield(void) {
std::this_thread::yield();
}
#elif defined(_WIN32)
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
static inline void mi_atomic_yield(void) {
YieldProcessor();
}
#elif defined(__SSE2__)
#include <emmintrin.h>
static inline void mi_atomic_yield(void) {
_mm_pause();
}
#elif (defined(__GNUC__) || defined(__clang__)) && \
(defined(__x86_64__) || defined(__i386__) || defined(__arm__) || defined(__armel__) || defined(__ARMEL__) || \
defined(__aarch64__) || defined(__powerpc__) || defined(__ppc__) || defined(__PPC__)) || defined(__POWERPC__)
#if defined(__x86_64__) || defined(__i386__)
static inline void mi_atomic_yield(void) {
__asm__ volatile ("pause" ::: "memory");
}
#elif defined(__aarch64__)
static inline void mi_atomic_yield(void) {
__asm__ volatile("wfe");
}
#elif (defined(__arm__) && __ARM_ARCH__ >= 7)
static inline void mi_atomic_yield(void) {
__asm__ volatile("yield" ::: "memory");
}
#elif defined(__powerpc__) || defined(__ppc__) || defined(__PPC__) || defined(__POWERPC__)
#ifdef __APPLE__
static inline void mi_atomic_yield(void) {
__asm__ volatile ("or r27,r27,r27" ::: "memory");
}
#else
static inline void mi_atomic_yield(void) {
__asm__ __volatile__ ("or 27,27,27" ::: "memory");
}
#endif
#elif defined(__armel__) || defined(__ARMEL__)
static inline void mi_atomic_yield(void) {
__asm__ volatile ("nop" ::: "memory");
}
#endif
#elif defined(__sun)
// Fallback for other archs
#include <synch.h>
static inline void mi_atomic_yield(void) {
smt_pause();
}
#elif defined(__wasi__)
#include <sched.h>
static inline void mi_atomic_yield(void) {
sched_yield();
}
#else
#include <unistd.h>
static inline void mi_atomic_yield(void) {
sleep(0);
}
#endif
#endif // __MIMALLOC_ATOMIC_H