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From: ad@uwmacc.UUCP
Newsgroups: comp.arch
Subject: Re: subroutine frequency
Message-ID: <1093@uwmacc.UUCP>
Date: Thu, 19-Feb-87 16:22:08 EST
Article-I.D.: uwmacc.1093
Posted: Thu Feb 19 16:22:08 1987
Date-Received: Fri, 20-Feb-87 21:34:54 EST
References: <1881@homxc.UUCP> <898@moscom.UUCP> <476@mntgfx.MENTOR.COM> <430@cpocd2.UUCP>
Organization: UWisconsin-Madison Academic Comp Center
Lines: 20
Summary: more info requested

In article <430@cpocd2.UUCP>, howard@cpocd2.UUCP (Howard A. Landman) writes:
>Procedure calls are grotesquely expensive on the most common machines.  A good
>rule of thumb for a VAX is that a procedure call takes as long as executing
>about 100 computational instructions.  This is why so much of the stdio package
>is macros instead of procedures.  There are several ways to try to avoid this
>overhead.  One is hardware support for call/return, as in some RISC machines.
>Another way is to eliminate procedures from your language; this is what Forth
>did with its "threaded code", and is the main reason Forth is so fast.  On a
>machine with multiple register windows the speed advantage of Forth would
>evaporate; of course you could also implement a hardware stack, which might
>increase its advantage!

Please explain what you mean by multiple register windows and how they
impact Forth's speed.  Thanks.

Alan Dickman  608-262-9421
Arpa: ad@unix.macc.wisc.edu
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