Path: utzoo!attcan!uunet!lll-winken!lll-tis!ames!ll-xn!mit-eddie!uw-beaver!cornell!batcomputer!itsgw!nyser!cmx!billo
From: billo@cmx.npac.syr.edu (Bill O)
Newsgroups: comp.arch
Subject: Re: hardware for late-binding languages (Was: negative addresses)
Message-ID: <495@cmx.npac.syr.edu>
Date: 18 May 88 02:37:37 GMT
References: <11571@ut-sally.UUCP> <28200145@urbsdc> <11618@ut-sally.UUCP> <493@cmx.npac.syr.edu> <4926@june.cs.washington.edu>
Reply-To: billo@cmx.npac.syr.edu (Bill O)
Organization: Northeast Parallel Architectures Center, Syracuse NY
Lines: 28

In article <4926@june.cs.washington.edu> pardo@uw-june.UUCP (David Keppel) writes:

>I like architectures to support late-binding languages.  A relevant
>note, however:  I saw a video by somebody from Symbolics (the video is
>a year or more old, I think).  During the Q&A section, one of the
>questions was something along the line of "how much faster does a
>program run on a machine w/ hardware support?"  His answer was
>essentially that if you had a fixed program (e.g., you weren't trying
>to debug it), that compiler technology would give you a program that
>ran just as fast on an architecture w/o support for late-binding
>languages.  The real wins of the extra hardware, he said, were during
>development, etc.
>
>Any comments on this?

He's probably right, if by "fixed program" you mean one that had
all types fully declared. In that case, run-time type checking gets
you essentially nothing.  On the other hand, if you had to do 
run-time type checking on a machine with no support for it, then
your compiled code would be so burdened down that it would probably
be much slower.

Of course, with RISC designers doubling the speed of their chips
every year or so, it could be that just putting in the extra code
and running on a risc will be the most cost-effective way of 
getting run-time typing.

Bill O'Farrell, Northeast Parallel Architectures Center at Syracuse University
(billo@cmx.npac.syr.edu)