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From: al@mot.UUCP (Al Filipski)
Newsgroups: net.lang
Subject: Re: Recursion
Message-ID: <250@mot.UUCP>
Date: Tue, 10-Sep-85 13:55:57 EDT
Article-I.D.: mot.250
Posted: Tue Sep 10 13:55:57 1985
Date-Received: Tue, 10-Sep-85 21:19:09 EDT
References: <712@gitpyr.UUCP>
Organization: Motorola Microsystems, Phoenix AZ
Lines: 19

****Make my day, Line-Eater*****


>     I think that would be a good idea, but wouldnt it be limited to direct
> recursion ( i.e. routine A calls A as apposed to A calls B, B calls A ). I
> don't know PL/I, but I would think including such a check for anything other
> than direct recursion would be a royal pain for a compiler writter.
> 
Actually, it's not too bad.  You just set up an n-by-n Boolean matrix
where n is the number of subroutines under consideration and the
ij element is 1 iff routine i calls routine j.  Then take the
transitive closure by Warshall's algorithm.  1's on the diagonal of
the result indicate which routines are indirectly recursive.

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Alan Filipski, UNIX group, Motorola Microsystems, Tempe, AZ U.S.A
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