[Soot-list] ExceptionalGraph no longer handles Block graphs (was How to specify the type of control flow graph?)

[John Jorgensen]

>>>>> "cbqios" == bq chan <cbqios at gmail.com> writes:

    cbqios> I wonder that if we can specify the type of
    cbqios> control flow graph to be dumped.  I can just get dot
    cbqios> files of jimple unitgraphs, but what I really want is
    cbqios> those jimple blockgraphs.

I was going to suggest trying "java soot.util.CFGViewer --help"
(with the classpath that you use to run Soot) to see if that will
do what you want.  CFGViewer allows you to specify the type of
graph and the intermediate representation, but I don't remember
what analyses and transformations are performed on the analyzed
code before its CFG is produced. ("soot --dump-cfg" on the other
hand, was intended as a debugging tool for soot itself, so it
only dumps visualizations of CFGs that Soot produces for itself
anyway;  "--dump-cfg ALL" reveals that very few analyses generate
block graphs, and those few seem to be baf, rather than jimple,
graphs).

But ... I've just discovered that CFGViewer's ability to produce
visualizations of ExceptionalBlockGraphs has been broken by
revision 2852 to
soot/trunk/src/soot/util/cfgcmd/CFGToDotGraph.java, with the
result that my attempt just now to run

  CFGViewer --graph=ExceptionalBlockGraph --ir=jimple CFGEg

died with

  Exception in thread "main" java.lang.ClassCastException:
  soot.toolkits.graph.Block cannot be cast to soot.Unit
        at
        soot.util.cfgcmd.CFGToDotGraph.drawCFG(CFGToDotGraph.java:345)

The proximate cause of the failure is that an iterator over the
graph's nodes has been changed from an Iterator over Objects to
an Iterator<Unit>, but that is part of a larger change which
involved tighening the types returned by ExceptionalGraph's
methods.

Eric, from the svn logs it looks like these changes were part of
your "genericizing" the dataflow analysis, but it's not clear
whether you didn't realize that the ExceptionalGraph classes were
intended to provide an interface to Block graphs as well as Unit
graphs, or if you decided that there were benefits to restricting
the interface to Unit graphs which justified sacrificing the
ability to access Block graphs through the ExceptionalGraph
interface.

I'll let somebody explain the intent of the changes before I suggest
reverting them :-).  I suppose the Right Thing would be to create
some sort of GraphNode interface that both Unit and Block could
implement, but my knowledge of soot is far too rusty to judge how
feasible such a solution is.

-- 
John Jorgensen	LCD System Administrator  jorgnsn at lcd.uregina.ca
                                          306.337.2344