Aliasing

Preston Briggs <preston@rice.edu>
Mon, 28 May 90 12:10:25 CDT

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Aliasing preston@rice.edu (Preston Briggs) (1990-05-28)
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Date: Mon, 28 May 90 12:10:25 CDT
From: Preston Briggs <preston@rice.edu>
Newsgroups: comp.compilers
In-Reply-To: <54866@microsoft.UUCP>
References: <4886@daffy.cs.wisc.edu>
Organization: Rice University, Houston
Keywords: code, C, Fortran, optimize

In article <54866@microsoft.UUCP> Mark Roberts write:
>Actually, it is possible to do a pretty decent job of alias analysis; it is
>just very computationaly expensive.


There's at least 3 kinds of aliasing I can think of:


    1) Aliasing caused by reference parameters (two parameters aliased or
a parameter and a global aliased). This is an interprocedural
problem and is addressed by Fortran's anti-aliasing restrictions.
It's also the problem addressed by the Cooper-Kennedy work.


    2) Aliasing caused by arrays (e.g., do A[i] and A[j] refer to the
same location?). This is the problem addressed by
dependence analysis. Reference Kuck, Bannerjee, Wolfe,
Allen, Kennedy, and many others.


    3) Aliasing caused by pointers (do *p and q->key refer to the
same location?). This is the one that doesn't occur in Fortran.
Reference Larus and Hilfinger, Sigplan '88 for example.
Also, Chase, Wegman, and Zadeck have a paper appearing in
Sigplan '90.


>[Now Preston can give us his 'why I like Fortran' spiel ;-) ]


How embarrassing. For the record, I dislike Fortran even more than C.
Too many people assume because I slam C's pointers that I must therefore
like Fortran. The language spectrum isn't so restricted! Support
your local alternative language -- SML, Oberon, Clu, Beta, ...


--
Preston Briggs looking for the great leap forward
preston@titan.rice.edu





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