Comment 2 for bug 411439

FTR, that's what mono does (for an equivalent to sync_instruction_memory (code, size);):
 guint64 *p = (guint64*)code;
 guint64 *end = (guint64*)(code + ((size + 8) /8));

 /*
  * FIXME: Flushing code in dword chunks in _slow_.
  */
 while (p < end)
#ifdef __GNUC__
  __asm__ __volatile__ ("iflush %0"::"r"(p++));
#else
   flushi (p ++);
#endif