const char *unw_regname(unw_regnum_t
The unw_regname() routine returns a printable name for register regnum. If regnum is an invalid or otherwise unrecognized register number, a string consisting of three question marks is returned. The returned string is statically allocated and therefore guaranteed to remain valid until the application terminates.
The unw_regname() routine cannot fail and always returns a valid (non-NULL) string.
THREAD AND SIGNAL SAFETY
The unw_regname() routine is thread-safe as well as safe to use from a signal handler.