3 ms·
Back when I did IBM 370 BAL Assembly Language, we did the same thing to clear a register to zero. XR 15,15 XOR REGISTER 15 WITH REGISTER 15 vs
by fortran77 11mo ago
Back when I did IBM 370 BAL Assembly Language, we did the same thing to clear a register to zero.
XR 15,15 XOR REGISTER 15 WITH REGISTER 15
vs
L 15,=F'0' LOAD REGISTER 15 WITH 0
This was alleged to be faster on the 370 because because XR operated entirely within the CPU registers, and L (Load) fetched data from memory (i.e.., the constant came from program memory).