> it will let a function jump to another function ... isn't that what's essentially described here?
Not exactly, they're describing doing it without a jump - the first function simply ends at the start of the second function, so the CPU starts running the second function directly after the first with no jump necessary.
Edit: If you're saying a tail call could enable such an optimization, you're right, but it still requires placing the functions in the right spots to eliminate the jump entirely, which is hard.
hey, thanks a lot for the elaboration / clearing up. my wording on jump was bad, but this comment drives that into my brain nicely :D...
i think your edit is on point. optimizations exist, but the hard thing is to know when to apply them and them restructuring the binary etc. - you can imagine you might optimize one bit only to find its impossible to run further code etc. because the optimization breaks it. or even different phases of optimization either feeding eachother more optimization opportunities or negating them(how to order optimizations). compilers and optimizers are such magic really, how far weve come in there. i got one book bigger and fatter than any ive ever seen, more thick than an oldksool bible. and its on compilers :'). its so big im afraid to start it!
Where it mattered for me was on an ARM core managing a much larger DSP. The DSP consumed most of the memory bandwidth, so fetching a cacheline of instructions or an MMU mapping into the ARM had long and variable latency as it had to wait for the DSP to finish a large burst to or from the shared memory.
Not exactly, they're describing doing it without a jump - the first function simply ends at the start of the second function, so the CPU starts running the second function directly after the first with no jump necessary.
Edit: If you're saying a tail call could enable such an optimization, you're right, but it still requires placing the functions in the right spots to eliminate the jump entirely, which is hard.