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libobs/util: Various atomic improvements

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Add exchange functions to alias the poorly named set functions.

Add store without reading previous. Faster on non-x86 processors.

Add compare-exchange that updates previous to avoid redundant fetch.

On Windows, load bool without conversion from char.

On Windows, load using mov with compiler barrier. Still seq_cst.

On POSIX, use GCC __atomic builtins.
This commit is contained in:
jpark37 2021-02-02 22:37:08 -08:00 committed by Jim
parent 31a9dc384d
commit 1f90f0e36b
2 changed files with 103 additions and 9 deletions
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38
libobs/util/threading-posix.h
View File

@ -18,17 +18,27 @@
static inline long os_atomic_inc_long(volatile long *val)
{
return __sync_add_and_fetch(val, 1);
return __atomic_add_fetch(val, 1, __ATOMIC_SEQ_CST);
}
static inline long os_atomic_dec_long(volatile long *val)
{
return __sync_sub_and_fetch(val, 1);
return __atomic_sub_fetch(val, 1, __ATOMIC_SEQ_CST);
}
static inline void os_atomic_store_long(volatile long *ptr, long val)
{
__atomic_store_n(ptr, val, __ATOMIC_SEQ_CST);
}
static inline long os_atomic_set_long(volatile long *ptr, long val)
{
return __sync_lock_test_and_set(ptr, val);
return __atomic_exchange_n(ptr, val, __ATOMIC_SEQ_CST);
}
static inline long os_atomic_exchange_long(volatile long *ptr, long val)
{
return os_atomic_set_long(ptr, val);
}
static inline long os_atomic_load_long(const volatile long *ptr)
@ -39,12 +49,30 @@ static inline long os_atomic_load_long(const volatile long *ptr)
static inline bool os_atomic_compare_swap_long(volatile long *val, long old_val,
long new_val)
{
return __sync_bool_compare_and_swap(val, old_val, new_val);
return __atomic_compare_exchange_n(val, &old_val, new_val, false,
__ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST);
}
static inline bool os_atomic_compare_exchange_long(volatile long *val,
long *old_val, long new_val)
{
return __atomic_compare_exchange_n(val, old_val, new_val, false,
__ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST);
}
static inline void os_atomic_store_bool(volatile bool *ptr, bool val)
{
__atomic_store_n(ptr, val, __ATOMIC_SEQ_CST);
}
static inline bool os_atomic_set_bool(volatile bool *ptr, bool val)
{
return __sync_lock_test_and_set(ptr, val);
return __atomic_exchange_n(ptr, val, __ATOMIC_SEQ_CST);
}
static inline bool os_atomic_exchange_bool(volatile bool *ptr, bool val)
{
return os_atomic_set_bool(ptr, val);
}
static inline bool os_atomic_load_bool(const volatile bool *ptr)

74
libobs/util/threading-windows.h
View File

@ -17,6 +17,12 @@
#pragma once
#include <intrin.h>
#include <string.h>
#if !defined(_M_IX86) && !defined(_M_X64) && !defined(_M_ARM) && \
!defined(_M_ARM64)
#error Processor not supported
#endif
static inline long os_atomic_inc_long(volatile long *val)
{
@ -28,14 +34,36 @@ static inline long os_atomic_dec_long(volatile long *val)
return _InterlockedDecrement(val);
}
static inline void os_atomic_store_long(volatile long *ptr, long val)
{
#if defined(_M_ARM) || defined(_M_ARM64)
__dmb(_ARM64_BARRIER_ISH);
__iso_volatile_store32((volatile __int32 *)ptr, val);
__dmb(_ARM64_BARRIER_ISH);
#else
_InterlockedExchange(ptr, val);
#endif
}
static inline long os_atomic_set_long(volatile long *ptr, long val)
{
return (long)_InterlockedExchange((volatile long *)ptr, (long)val);
return _InterlockedExchange(ptr, val);
}
static inline long os_atomic_exchange_long(volatile long *ptr, long val)
{
return os_atomic_set_long(ptr, val);
}
static inline long os_atomic_load_long(const volatile long *ptr)
{
return (long)_InterlockedOr((volatile long *)ptr, 0);
const long val = __iso_volatile_load32((const volatile __int32 *)ptr);
#if defined(_M_ARM) || defined(_M_ARM64)
__dmb(_ARM64_BARRIER_ISH);
#else
_ReadWriteBarrier();
#endif
return val;
}
static inline bool os_atomic_compare_swap_long(volatile long *val, long old_val,
@ -44,12 +72,50 @@ static inline bool os_atomic_compare_swap_long(volatile long *val, long old_val,
return _InterlockedCompareExchange(val, new_val, old_val) == old_val;
}
static inline bool os_atomic_compare_exchange_long(volatile long *val,
long *old_ptr, long new_val)
{
const long old_val = *old_ptr;
const long previous =
_InterlockedCompareExchange(val, new_val, old_val);
*old_ptr = previous;
return previous == old_val;
}
static inline void os_atomic_store_bool(volatile bool *ptr, bool val)
{
#if defined(_M_ARM) || defined(_M_ARM64)
__dmb(_ARM64_BARRIER_ISH);
__iso_volatile_store8((volatile char *)ptr, val);
__dmb(_ARM64_BARRIER_ISH);
#else
_InterlockedExchange8((volatile char *)ptr, (char)val);
#endif
}
static inline bool os_atomic_set_bool(volatile bool *ptr, bool val)
{
return !!_InterlockedExchange8((volatile char *)ptr, (char)val);
const char c = _InterlockedExchange8((volatile char *)ptr, (char)val);
bool b;
/* Avoid unnecesary char to bool conversion. Value known 0 or 1. */
memcpy(&b, &c, sizeof(b));
return b;
}
static inline bool os_atomic_exchange_bool(volatile bool *ptr, bool val)
{
return os_atomic_set_bool(ptr, val);
}
static inline bool os_atomic_load_bool(const volatile bool *ptr)
{
return !!_InterlockedOr8((volatile char *)ptr, 0);
const char val = __iso_volatile_load8((const volatile char *)ptr);
#if defined(_M_ARM) || defined(_M_ARM64)
__dmb(_ARM64_BARRIER_ISH);
#else
_ReadWriteBarrier();
#endif
return val;
}