Graph.java

package us.brtm.cfg;

import org.objectweb.asm.tree.AbstractInsnNode;
import org.objectweb.asm.tree.LabelNode;
import org.objectweb.asm.tree.MethodNode;
import org.objectweb.asm.tree.analysis.*;

/**
 * @author Pedro Daia Cardoso
 */
public class Graph {
    /**
     * The analyzer instance.
     */
    public Analyzer<BasicValue> analyzer;
    /**
     * The primitive method.
     */
    public MethodNode method;
    /**
     * All frames (nodes) created in this graph.
     */
    public Frame<BasicValue>[] frames;

    public Graph(String supername, MethodNode node) {
        this.method = node;
        analyzer = new Analyzer<BasicValue>(new BasicInterpreter()) {
            protected Frame<BasicValue> newFrame(int nLocals, int nStack) {
                return new Node<>(nLocals, nStack);
            }

            protected Frame<BasicValue> newFrame(Frame<? extends BasicValue> src) {
                return new Node<>(src);
            }

            protected void newControlFlowEdge(int src, int dst) {
                Node<BasicValue> s = (Node<BasicValue>) getFrames()[src];
                s.successors.add((Node<BasicValue>) getFrames()[dst]);
            }
        };
        try {
            analyzer.analyze(supername, method);
            frames = analyzer.getFrames();
            optimizeMethod();
        } catch (AnalyzerException e) {
            e.printStackTrace();
        }
    }

    /**
     * Removes useless instructions from the method.
     */
    public void optimizeMethod() {
        AbstractInsnNode[] instructions = method.instructions.toArray();
        for (int i = 0; i < frames.length; i++) {
            AbstractInsnNode instruction = instructions[i];
            if (frames[i] == null && !(instruction instanceof LabelNode)) {
                method.instructions.remove(instructions[i]);
            }
        }
    }

}

Node.java

package us.brtm.cfg;

import org.objectweb.asm.tree.analysis.BasicValue;
import org.objectweb.asm.tree.analysis.Frame;
import org.objectweb.asm.tree.analysis.Value;

import java.util.HashSet;
import java.util.Set;

/**
 * @author Pedro Daia Cardoso
 */
public class Node<V extends Value> extends Frame<BasicValue> {
    public Set<Node<V>> successors = new HashSet<>();

    public Node(Frame<? extends BasicValue> src) {
        super(src);
    }

    public Node(int nLocals, int nStack) {
        super(nLocals, nStack);
    }

}