public IsNullValueAnalysis(MethodGen methodGen, ValueNumberDataflow vnaDataflow) {
public IsNullValueAnalysis(MethodGen methodGen, CFG cfg, ValueNumberDataflow vnaDataflow) {
	public IsNullValueAnalysis(MethodGen methodGen, ValueNumberDataflow vnaDataflow) {		this.methodGen = methodGen;		this.vnaDataflow = vnaDataflow;	}