Re: Question on Value vs. ValueBox

[Raja Vallee-Rai <kor@sable.mcgill.ca>]

"James C. Corbett" wrote:
> 
> I'm looking at example 3 (copy propagaton) in the Soot distribution.
> I understand the basic logic, but I'm a little confused by the
> representation.  What is the difference between a Value and a
> ValueBox?  What do each represent?

Yeah this is one of the things that sorely needs documentation.  A Value
is an object in the grammar, whereas a ValueBox is an object which
contains a Value.  It's basically an abstraction which represents a
pointer to a value.  It is useful when performing analyses so that you
can get the ValueBox's for all the uses or definitions in a statement
and modify them without knowing where they are exactly.  (which is a
technique used for copy/constant propagation)


Raja