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From: mathew@mantis.co.uk (mathew)
Newsgroups: comp.lang.misc,comp.object
Subject: Re: Type Systems and Dynamic Binding
Message-ID: <7w4813w164w@mantis.co.uk>
Date: 30 Apr 91 15:37:29 GMT
References: <3618@sequent.cs.qmw.ac.uk>
Organization: Mantis Consultants, Cambridge. UK.
Lines: 24

eliot@cs.qmw.ac.uk (Eliot Miranda) writes:
> In article <1991Apr19.132239.9252@daffy.cs.wisc.edu> quale@saavik.cs.wisc.edu
> >     A compiler for a dynamically typed language can dedicate a register to
> >     hold a bitmask that will speed type tag operations.  A C program would
> >     either use an immediate value or a global variable, either of which is
> >     slower and bulkier on many architectures.
>
> I have tried this in my Smalltalk VM. On both 68020 & SPARC there is no
> significant difference in performance attributable to dedicating a register
> to tag detection. Add a register here loose it there.

You're saying that you've tried keeping the tags in memory vs. keeping them
in a register on a 68020, and you've not noticed any difference?  I find this
a little hard to believe.

Exactly what changes did you make to the code in order to use register-based
tags rather than memory-based tags, and what sort of program did you run in
order to test the result?


mathew

-- 
mathew - mathew@mantis.co.uk or mcsun!ukc!ibmpcug!mantis!mathew