[Program Analysis] LiveVariableAnalysis in Soot

Setup of the Soot

We need to first set up the Soot variables. In target command line tools, the config is passed by args, e.g. java -cp soot-2.5.0.jar soot.Main -pp -f J -cp . Hello. The prepend file is set and the jar interpreter will pass the variable $CLASSPATH. In my implementation, these are passed into Options.v(). Noticeably, I have to switch off the optimization for java ByteCode, or it will do Dead Code Elimination to remove the intermediate process.

CallGraph for Debug

I iterate the CFG before and after the Liveness analysis to see the problem.

for (Unit unit : body.getUnits()) {
       System.out.println(unit.toString() + "[entry]" +lva.getFlowBefore(unit));
       System.out.println(unit.toString() + "[exit]" +lva.getFlowBefore(unit));



I record all the FlowSet<Local> to a enhanced AbstractBoundedFlowSet<Local> with liveVariable hash set. So that it has clone and record feature.


The Analysis extends BackwardFlow. The merge logic is union and copy logic is copy. The flowThrough part is first calculates the kill set and makes the difference of kills and destSet; then the gens are merely the union of the iterated kills.

Input and output of file

The soot.Main only accept className, so I remove the "./" and ".class" to pass. And the directory is created in the same folder of the class file to write the output.