Path: utzoo!mnetor!tmsoft!torsqnt!jarvis.csri.toronto.edu!rutgers!gatech!mcnc!decvax!ima!esegue!compilers-sender
From: preston@titan.rice.edu (Preston Briggs)
Newsgroups: comp.compilers
Subject: use-def chains
Message-ID: <1989Sep19.050839.1255@esegue.segue.boston.ma.us>
Date: 19 Sep 89 05:08:39 GMT
Sender: compilers-sender@esegue.segue.boston.ma.us
Reply-To: Preston Briggs <preston@titan.rice.edu>
Organization: Compilers Central
Lines: 26
Approved: compilers@esegue.segue.boston.ma.us

Howdy,

I'm curious about how many people actually build
use-def chains for optimization.

(That is, for each variable reference, a list of all the instructions
 that might have set the variable.  Alternatively, def-use chains
 link a definition with all the uses.)

They are mentioned often in the literature, but seem expensive in
time and space to build.  On the other hand, Wegman and Zadeck (and
others) have been playing with a form called Static Single Assignment
(SSA) which seems reasonably space efficient.  They also have methods
to construct the form quickly, at least for reducible flow graphs.

So, any experience out there?  I'm especially interested in
space-efficient representations (think BIG fortran routines), so
ideas for compact representation are welcome too.

Thanks,
Preston Briggs
preston@titan.rice.edu
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