R0(x0, x1), R1(x0, x1)
R2(x1, x2), R3(x1, x2), R4(x0, x2), R5(x0, x2)
R6(x2, x3), R7(x0, x3), R8(x1, x3), R9(x0, x3), R10(x0, x3), R11(x2, x3), R12(x0, x3), R13(x2, x3)
