Messages in this thread |  | | From | "H. Peter Anvin" <> | Date | 6 Jul 2001 17:16:57 -0700 |
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Followup to: <15174.20383.84051.790269@pizda.ninka.net> By author: "David S. Miller" <davem@redhat.com> In newsgroup: linux.dev.kernel > > Rick Hohensee writes: > > Forth chips aren't modern in the true-multi-user sense, but if an > > individual were to design such a beast they could get several of them, > > hundreds maybe, on FPGAs available now. Such things are coming, because a > > Forth chip IS something an individual can design. > > And I suppose this zero-cost call is also handling things like keeping > an N stage deep pipeline full during this call right? >
Believe it or not, that's actually a fairly simple part of the whole machinery. All you need for that is to maintain a call/return stack in the front end of the pipe. That way, a return that is indeed a return can be speculated properly; obviously, if the speculation doesn't work out when you get the return address in the execution stage you suffer a branch mispredict penalty.
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