getBoxesPointingToThis()

[Patrick LAM <plam@sable.mcgill.ca>]

Hi Venkatesh,

> It is my understanding that q.getBoxesPointingToThis(), where q is a
> Stmt, should return a list of UnitBoxes which may transfer control to
> the statement, q.  Is this correct?

This is not quite correct.  getBoxesPointingToThis returns a list of
UnitBoxes of statements which *jump* to this statement and need a pointer
in order to make this jump.  So the target $t$ of the IfStmt or GotoStmt
$s$ returns $s$ in $t$.getBoxesPointingToThis.  In particular,
getBoxesPointingToThis never contains predecessors of a statement;
statements are unaware of where they live in the chain of statements and
the control-flow graph.

getBoxesPointingToThis is used to do fixups when we remove statements.

>   for (Iterator i =
>         ((Stmt)v.getDefaultTarget()).getBoxesPointingToThis().iterator();
>         i.hasNext();)

The code which you wrote iterates on the default: target of the switch's
getBoxesPointingToThis.  That's probably not what you want.  In fact I'm
surprised that the default target has more than one box pointing to it.

I think that what you actually want is to construct 
a soot.toolkits.graph.CompleteUnitGraph from your JimpleBody and to use
that to navigate around the control-flow graph.

By the way, soot 1.0.0 is quite old.  I recommend a newer version of Soot,
although that doesn't change anything in the above.

pat