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From: gudeman@cs.arizona.edu (David Gudeman)
Newsgroups: comp.lang.misc
Subject: Re: Pointers as 3-tuples
Message-ID: <20080@megaron.cs.arizona.edu>
Date: 11 Apr 90 00:32:16 GMT
Organization: U of Arizona CS Dept, Tucson
Lines: 21

In article  <14324@lambda.UUCP> jlg@lambda.UUCP (Jim Giles) writes:
[about compiling different versions of procedures for different
aliasing patterns...]
>Actually, I recommended it as something _NOT_ to do.  The only way
>to make it genuinely useful is to have special versions of the code
>code each combination of aliased/non-aliased arguments.  Since this
>increases combinatorially (by the definition of combinatorial :-)
>with the number of _prtentially_ aliased items, this leads to an
>unacceptably large number of alternatives.

Actually, it increases exponentially with the number of aliasing
patterns in the arguments of the functions.  For a function of 3
array arguments, the maximum number of versions needed is 2^3 = 8.
Just how many array arguments do your functions have?  And I wouldn't
even consider trying to compile a seperate function for _every_
possibility.  Just 2 or so, maybe a worst case and an average case.
-- 
					David Gudeman
Department of Computer Science
The University of Arizona        gudeman@cs.arizona.edu
Tucson, AZ 85721                 noao!arizona!gudeman