MCLOCK8 — Time function (64-bit) ¶Returns the number of clock ticks since the start of the process, based
on the function clock(3) in the C standard library.
Warning: this intrinsic does not increase the range of the timing
values over that returned by clock(3). On a system with a 32-bit
clock(3), MCLOCK8 will return a 32-bit value, even though
it is converted to a 64-bit INTEGER(8) value. That means
overflows of the 32-bit value can still occur. Therefore, the values
returned by this intrinsic might be or become negative or numerically
less than previous values during a single run of the compiled program.
GNU extension
Function
RESULT = MCLOCK8()
The return value is a scalar of type INTEGER(8), equal to the
number of clock ticks since the start of the process, or -1 if
the system does not support clock(3).
CTIME — Convert a time into a string, 
GMTIME — Convert time to GMT info, 
LTIME — Convert time to local time info, 
MCLOCK — Time function, 
TIME8 — Time function (64-bit)