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From: gudeman@cs.arizona.edu (David Gudeman)
Newsgroups: comp.lang.misc
Subject: Re: Pointers as 3-tuples
Message-ID: <20144@megaron.cs.arizona.edu>
Date: 11 Apr 90 22:29:16 GMT
Organization: U of Arizona CS Dept, Tucson
Lines: 21

In article  <14332@lambda.UUCP> jlg@lambda.UUCP (Jim Giles) writes:
]From article <20080@megaron.cs.arizona.edu>, by gudeman@cs.arizona.edu (David Gudeman):
]> [...]
]> 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.
]
]No, the number increases combinatorially.  Aliasing occurs pairwise
]between arguments (an/or global data).  So, the number of potentially
]aliased pairs is N choose 2, ie. a binomial coefficient.  Here, N is the
]number of variables in the pool of potentially aliased objects.

Oops.  I was simplifying to the assumption that each argument was
either potentially aliased or it was not.  I suppose that the
combinatorial analysis would allow better code generation in some
cases, but no one want to compile more than two versions anyway.
-- 
					David Gudeman
Department of Computer Science
The University of Arizona        gudeman@cs.arizona.edu
Tucson, AZ 85721                 noao!arizona!gudeman