Path: utzoo!attcan!uunet!munnari.oz.au!cluster!andrewt
From: andrewt@cs.su.oz (Andrew Taylor)
Newsgroups: comp.lang.prolog
Subject: Re: Re : incrementing values
Message-ID: <703@cluster.cs.su.oz>
Date: 7 Feb 90 23:11:29 GMT
References: <1833@kulcs.kulcs.uucp>
Sender: news@cluster.cs.su.oz
Reply-To: andrewt@cluster.cs.su.oz (Andrew Taylor)
Organization: Basser Dept of Computer Science, University of Sydney, Australia
Lines: 15

>The efficiency of 'X1 is X0 + 1' can substantially be increased
>if at compile time we known that it is actually destructive assignment
>and that we can safely reuse the memory cel of X0 for X1.
>This kind of information can be derived by doing global analysis of the 
>PROLOG program.  At our department a framework for abstract interpretation
>has been developed and one of the applications is concerned with detecting
>opportunities for compile time garbage collection, as is required for the 
>example at hand.

I don't think this is relevant.  Expressions like this can be compiled
efficiently,  re-using memory-locations/registers without global
analaysis for  compile-time garbage collection. This analysis
becomes useful when compund terms are involved.

Andrew