It depends on the CPU, though in most CPUs, the comparison is a separate instruction from the branch. For example, on x86, CMP RAX, RBX JL label woul

It depends on the CPU, though in most CPUs, the comparison is a separate instruction from the branch. For example, on x86, CMP RAX, RBX JL label would jump if RAX < RBX. Similarly, on ARM: CMP r1, r2 BLT label /* jump if r1<r2 */ Some processors do have a conditional jump that takes the registers to compare though, such as the PDP-10's bewildering array of skip instructions: CAML A, B ADDI C, 100 ; This instruction will be skipped if A < B Finally, it's also fairly common to have branch instructions that compare against 0, such as PDP-10: JUMPL A, label ; jump if A<0 That said, off the top of my head, I don't know of any real processors with something equivalent to the fantasy CPU's JL, which combines a comparison between two registers with a jump to an arbitrary immediate.