__asm__ __volatile__()

in src/postgres/include/port/atomics/arch-x86.h [37:60]

• 15 lines of code
• 2 McCabe index (conditional complexity)

	__asm__ __volatile__ ("lock; addl $0,0(%%esp)" : : : "memory", "cc")
#elif defined(__x86_64__)
#define pg_memory_barrier_impl()		\
	__asm__ __volatile__ ("lock; addl $0,0(%%rsp)" : : : "memory", "cc")
#endif
#endif /* defined(__GNUC__) || defined(__INTEL_COMPILER) */

#define pg_read_barrier_impl()		pg_compiler_barrier_impl()
#define pg_write_barrier_impl()		pg_compiler_barrier_impl()

/*
 * Provide implementation for atomics using inline assembly on x86 gcc. It's
 * nice to support older gcc's and the compare/exchange implementation here is
 * actually more efficient than the * __sync variant.
 */
#if defined(HAVE_ATOMICS)

#if defined(__GNUC__) || defined(__INTEL_COMPILER)

#define PG_HAVE_ATOMIC_FLAG_SUPPORT
typedef struct pg_atomic_flag
{
	volatile char value;
} pg_atomic_flag;