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From: johnson@uiucdcsp.CS.UIUC.EDU
Newsgroups: net.lang.st80
Subject: Re: Native code Smalltalk compilers
Message-ID: <9000005@uiucdcsp>
Date: Tue, 13-May-86 10:26:00 EDT
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Posted: Tue May 13 10:26:00 1986
Date-Received: Fri, 16-May-86 04:58:19 EDT
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Nf-From: uiucdcsp.CS.UIUC.EDU!johnson    May 13 09:26:00 1986


The best paper on Smalltalk implementations is the one by Peter Deutsch
and Allan Schiffman in the 10'th POPL conference.  There is also a paper
by Suzuki and Terada in that same proceedings that talks about
implementation issues.  One of the things that is apparent from the
Deutsch and Schiffman paper is that interpretation alone is not the
reason why Smalltalk is slow, so just compiling Smalltalk to machine
language will not improve the speed much.  However, certain optimizations
can make a big difference.  In order to optimize Smalltalk programs the
compiler must know the particular methods that are being invoked by a given
message.  A type system is necessary to do this. Suzuki describes one type
system in the 8'th POPL conference proceedings, while Borning and Ingalls
described a more complete type system in the 9'th POPL conference proceedings.
I am having a paper in the Object-oriented Programming Languages, 
Applications, and Systems conference next October that explains why these
type systems are not suficient for code-optimization and that presents a
type system for Smalltalk that (I claim) is.  There will probably be a lot of
papers on compilation and other implementation techniques at this conference,
so anyone who is interested in implementing object-oriented languages should
certainly attend.

I have been looking at optimizing Smalltalk programs for a couple of years
and am in the early stages of an implementation of an optimizing compiler.
Smalltalk was not really designed to be optimized because it is typeless.
Retrofitting a type system to Smalltalk is tricky and inevitably requires
some modification to some of the primitives.  It might be better to just
start over and design a language that is well integrated with a type system.
Building an optimizing compiler for Smalltalk is interesting research but
it is by no means obvious that such a project will be a success.

Ralph Johnson