On Fri, 2007-09-21 at 13:37 -0500, Mike McCarty wrote: > Usually[*], the NOP is the smallest instruction, so it may be used > to nullify other instructions, all of which are made to be multiples > of the size of a NOP. A jump type instruction needs at least > an opcode and an address (even if only relative), so is usually > larger than a NOP. On some machines, some short form of jump > may be just one machine word (a couple of architectures come > to mind, like the Z8000 for instance). > > [*] I can't think of a counter example, and it wouldn't make sense > for it to be otherwise. The counter-example is a processor I used some time ago that included a short jump instruction that was one word in length. That is, the JMP instruction included the jump distance. I don't know if recent x86 has such a thing.
