clflushopt and clwb can not be opened

[ypluo]

Thanks for your wonderful project on memory allocation on persistent memory.

Note that there is some problem on opening optimized flush -- clflushopt and clwb.

the code in file <src/util.h> use Micro to open them but seems not in the right way (suppose we just want to define a HAS_CLWB to select clwb as persistent method)

#ifdef NOFLUSH
    /* Completely disable flushes */
    #define PERSIST(ptr)            do { } while (0)
    #define PERSIST_RANGE(ptr, len) do { } while (0)
#elif HAS_CLWB
    /* CLWB is the preferred instruction, not invalidating any cache lines */
    #define PERSIST(ptr)            do { sfence() clwb(ptr); sfence(); } while (0)
    #define PERSIST_RANGE(ptr, len) do { sfence(); clwb_range(ptr, len); sfence(); } while (0)
#elif HAS_CLFLUSHOPT
    /* CLFLUSHOPT is preferred over CLFLUSH as only dirty cache lines will be evicted */
    #define PERSIST(ptr)            do { sfence(); clflushopt(ptr); sfence(); } while (0)
    #define PERSIST_RANGE(ptr, len) do { sfence(); clflushopt_range(ptr, len); sfence(); } while (0)
#else
    /* If neither CLWB nor CLFLUSHOPT are available, default to CLFLUSH */
    #define PERSIST(ptr)            do { mfence(); clflush(ptr); mfence(); } while (0)
    #define PERSIST_RANGE(ptr, len) do { mfence(); clflush_range(ptr, len); mfence(); } while (0)
#endif

however, the following snippet, in my test, is the correct one:

#ifdef NOFLUSH
     xxx0
#elif defined(HAS_CLWB)
     xxx1
#elif defined(HAS_CLFLUSHOPT)
     xxx2
#else
     xxx3
#endif