xref: /freebsd/contrib/jemalloc/include/jemalloc/internal/atomic.h (revision c43cad87172039ccf38172129c79755ea79e6102)

#ifndef JEMALLOC_INTERNAL_ATOMIC_H
#define JEMALLOC_INTERNAL_ATOMIC_H

#define ATOMIC_INLINE JEMALLOC_ALWAYS_INLINE

#define JEMALLOC_U8_ATOMICS
#if defined(JEMALLOC_GCC_ATOMIC_ATOMICS)
#  include "jemalloc/internal/atomic_gcc_atomic.h"
#  if !defined(JEMALLOC_GCC_U8_ATOMIC_ATOMICS)
#    undef JEMALLOC_U8_ATOMICS
#  endif
#elif defined(JEMALLOC_GCC_SYNC_ATOMICS)
#  include "jemalloc/internal/atomic_gcc_sync.h"
#  if !defined(JEMALLOC_GCC_U8_SYNC_ATOMICS)
#    undef JEMALLOC_U8_ATOMICS
#  endif
#elif defined(_MSC_VER)
#  include "jemalloc/internal/atomic_msvc.h"
#elif defined(JEMALLOC_C11_ATOMICS)
#  include "jemalloc/internal/atomic_c11.h"
#else
#  error "Don't have atomics implemented on this platform."
#endif

/*
 * This header gives more or less a backport of C11 atomics. The user can write
 * JEMALLOC_GENERATE_ATOMICS(type, short_type, lg_sizeof_type); to generate
 * counterparts of the C11 atomic functions for type, as so:
 *   JEMALLOC_GENERATE_ATOMICS(int *, pi, 3);
 * and then write things like:
 *   int *some_ptr;
 *   atomic_pi_t atomic_ptr_to_int;
 *   atomic_store_pi(&atomic_ptr_to_int, some_ptr, ATOMIC_RELAXED);
 *   int *prev_value = atomic_exchange_pi(&ptr_to_int, NULL, ATOMIC_ACQ_REL);
 *   assert(some_ptr == prev_value);
 * and expect things to work in the obvious way.
 *
 * Also included (with naming differences to avoid conflicts with the standard
 * library):
 *   atomic_fence(atomic_memory_order_t) (mimics C11's atomic_thread_fence).
 *   ATOMIC_INIT (mimics C11's ATOMIC_VAR_INIT).
 */

/*
 * Pure convenience, so that we don't have to type "atomic_memory_order_"
 * quite so often.
 */
#define ATOMIC_RELAXED atomic_memory_order_relaxed
#define ATOMIC_ACQUIRE atomic_memory_order_acquire
#define ATOMIC_RELEASE atomic_memory_order_release
#define ATOMIC_ACQ_REL atomic_memory_order_acq_rel
#define ATOMIC_SEQ_CST atomic_memory_order_seq_cst

/*
 * Another convenience -- simple atomic helper functions.
 */
#define JEMALLOC_GENERATE_EXPANDED_INT_ATOMICS(type, short_type,	\
    lg_size)								\
    JEMALLOC_GENERATE_INT_ATOMICS(type, short_type, lg_size)		\
    ATOMIC_INLINE void							\
    atomic_load_add_store_##short_type(atomic_##short_type##_t *a,	\
	type inc) {							\
	    type oldval = atomic_load_##short_type(a, ATOMIC_RELAXED);	\
	    type newval = oldval + inc;					\
	    atomic_store_##short_type(a, newval, ATOMIC_RELAXED);	\
	}								\
    ATOMIC_INLINE void							\
    atomic_load_sub_store_##short_type(atomic_##short_type##_t *a,	\
	type inc) {							\
	    type oldval = atomic_load_##short_type(a, ATOMIC_RELAXED);	\
	    type newval = oldval - inc;					\
	    atomic_store_##short_type(a, newval, ATOMIC_RELAXED);	\
	}

/*
 * Not all platforms have 64-bit atomics.  If we do, this #define exposes that
 * fact.
 */
#if (LG_SIZEOF_PTR == 3 || LG_SIZEOF_INT == 3)
#  define JEMALLOC_ATOMIC_U64
#endif

JEMALLOC_GENERATE_ATOMICS(void *, p, LG_SIZEOF_PTR)

/*
 * There's no actual guarantee that sizeof(bool) == 1, but it's true on the only
 * platform that actually needs to know the size, MSVC.
 */
JEMALLOC_GENERATE_ATOMICS(bool, b, 0)

JEMALLOC_GENERATE_EXPANDED_INT_ATOMICS(unsigned, u, LG_SIZEOF_INT)

JEMALLOC_GENERATE_EXPANDED_INT_ATOMICS(size_t, zu, LG_SIZEOF_PTR)

JEMALLOC_GENERATE_EXPANDED_INT_ATOMICS(ssize_t, zd, LG_SIZEOF_PTR)

JEMALLOC_GENERATE_EXPANDED_INT_ATOMICS(uint8_t, u8, 0)

JEMALLOC_GENERATE_EXPANDED_INT_ATOMICS(uint32_t, u32, 2)

#ifdef JEMALLOC_ATOMIC_U64
JEMALLOC_GENERATE_EXPANDED_INT_ATOMICS(uint64_t, u64, 3)
#endif

#undef ATOMIC_INLINE

#endif /* JEMALLOC_INTERNAL_ATOMIC_H */