// Euclid's algorithm: if you repeatedly subtract
// the smaller of two numbers from the larger,
// you'll eventually get to the GCD of the two.
while (a != b) {
    if (a < b) {
        a -= b;
    } else {
        b -= a;
    }
}

/*
beg:
    if (a == b) goto end

    if (a >= b) goto else
    a -= b
    goto endif
else:
    b -= a
endif:

    goto beg
end:
*/


/*
variables: (I picked these at random)
    a in 0x80
    b in 0x81

a -= b      b = -b; a += b; b = -b;
if !!a <= 0 goto end
*/

/*
variables: (I picked these at random)
    a in 0x80
    b in 0x81

r0 = mem[0x80]  (6, 0, 3) 80
r1 = mem[0x81]  (6, 1, 3) 81
r1 = -r1        (5, 1, 1)
r0 += r1        (1, 0, 1)
r1 = -r1        (5, 1, 1)
r0 = !r0        (5, 0, 2)
r0 = !r0        (5, 0, 2)
r3 = end****
if r0 <= 0 goto end (7, 0, 3)
a -= b      b = -b; a += b; b = -b;
if !!a <= 0 goto end
*/