rmb
#define rmb() __asm volatile("lock; addl $0,-4(%%esp)" : : : "memory", "cc")
#define rmb() __membar("lfence")
#define rmb() __membar("dsb ld")
#define rmb() __membar("dsb sy")
#define rmb() mips_sync()
#define rmb() __membar("sync")
#define rmb() __membar("sync")
#define rmb() __membar("fence ir,ir")
#define rmb() membar_sync()