analyzer.java

asm的源码包 并且包含英文的文档

/***
 * ASM: a very small and fast Java bytecode manipulation framework
 * Copyright (c) 2000-2005 INRIA, France Telecom
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the copyright holders nor the names of its
 *    contributors may be used to endorse or promote products derived from
 *    this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 * THE POSSIBILITY OF SUCH DAMAGE.
 */
package org.objectweb.asm.tree.analysis;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.objectweb.asm.Opcodes;
import org.objectweb.asm.Type;
import org.objectweb.asm.tree.AbstractInsnNode;
import org.objectweb.asm.tree.IincInsnNode;
import org.objectweb.asm.tree.InsnList;
import org.objectweb.asm.tree.JumpInsnNode;
import org.objectweb.asm.tree.LabelNode;
import org.objectweb.asm.tree.LookupSwitchInsnNode;
import org.objectweb.asm.tree.MethodNode;
import org.objectweb.asm.tree.TableSwitchInsnNode;
import org.objectweb.asm.tree.TryCatchBlockNode;
import org.objectweb.asm.tree.VarInsnNode;

/**
 * A semantic bytecode analyzer. <i>This class does not fully check that JSR and
 * RET instructions are valid.</i>
 * 
 * @author Eric Bruneton
 */
public class Analyzer implements Opcodes {

    private Interpreter interpreter;

    private int n;

    private InsnList insns;

    private List[] handlers;

    private Frame[] frames;

    private Subroutine[] subroutines;

    private boolean[] queued;

    private int[] queue;

    private int top;

    /**
     * Constructs a new {@link Analyzer}.
     * 
     * @param interpreter the interpreter to be used to symbolically interpret
     *        the bytecode instructions.
     */
    public Analyzer(final Interpreter interpreter) {
        this.interpreter = interpreter;
    }

    /**
     * Analyzes the given method.
     * 
     * @param owner the internal name of the class to which the method belongs.
     * @param m the method to be analyzed.
     * @return the symbolic state of the execution stack frame at each bytecode
     *         instruction of the method. The size of the returned array is
     *         equal to the number of instructions (and labels) of the method. A
     *         given frame is <tt>null</tt> if and only if the corresponding
     *         instruction cannot be reached (dead code).
     * @throws AnalyzerException if a problem occurs during the analysis.
     */
    public Frame[] analyze(final String owner, final MethodNode m)
            throws AnalyzerException
    {
        if ((m.access & (ACC_ABSTRACT | ACC_NATIVE)) != 0) {
            frames = new Frame[0];
            return frames;
        }
        n = m.instructions.size();
        insns = m.instructions;
        handlers = new List[n];
        frames = new Frame[n];
        subroutines = new Subroutine[n];
        queued = new boolean[n];
        queue = new int[n];
        top = 0;

        // computes exception handlers for each instruction
        for (int i = 0; i < m.tryCatchBlocks.size(); ++i) {
            TryCatchBlockNode tcb = (TryCatchBlockNode) m.tryCatchBlocks.get(i);
            int begin = insns.indexOf(tcb.start);
            int end = insns.indexOf(tcb.end);
            for (int j = begin; j < end; ++j) {
                List insnHandlers = handlers[j];
                if (insnHandlers == null) {
                    insnHandlers = new ArrayList();
                    handlers[j] = insnHandlers;
                }
                insnHandlers.add(tcb);
            }
        }

        // computes the subroutine for each instruction:
        Subroutine main = new Subroutine(null, m.maxLocals, null);
        List subroutineCalls = new ArrayList();
        Map subroutineHeads = new HashMap();
        findSubroutine(0, main, subroutineCalls);
        while (subroutineCalls.size() > 0) {
            JumpInsnNode jsr = (JumpInsnNode) subroutineCalls.remove(0);
            Subroutine sub = (Subroutine) subroutineHeads.get(jsr.label);
            if (sub == null) {
                sub = new Subroutine(jsr.label, m.maxLocals, jsr);
                subroutineHeads.put(jsr.label, sub);
                findSubroutine(insns.indexOf(jsr.label), sub, subroutineCalls);
            } else {
                sub.callers.add(jsr);
            }
        }
        for (int i = 0; i < n; ++i) {
            if (subroutines[i] != null && subroutines[i].start == null) {
                subroutines[i] = null;
            }
        }

        // initializes the data structures for the control flow analysis
        Frame current = newFrame(m.maxLocals, m.maxStack);
        Frame handler = newFrame(m.maxLocals, m.maxStack);
        Type[] args = Type.getArgumentTypes(m.desc);
        int local = 0;
        if ((m.access & ACC_STATIC) == 0) {
            Type ctype = Type.getObjectType(owner);
            current.setLocal(local++, interpreter.newValue(ctype));
        }
        for (int i = 0; i < args.length; ++i) {
            current.setLocal(local++, interpreter.newValue(args[i]));
            if (args[i].getSize() == 2) {
                current.setLocal(local++, interpreter.newValue(null));
            }
        }
        while (local < m.maxLocals) {
            current.setLocal(local++, interpreter.newValue(null));
        }
        merge(0, current, null);

        // control flow analysis
        while (top > 0) {
            int insn = queue[--top];
            Frame f = frames[insn];
            Subroutine subroutine = subroutines[insn];
            queued[insn] = false;

            try {
                AbstractInsnNode insnNode = m.instructions.get(insn);
                int insnOpcode = insnNode.getOpcode();
                int insnType = insnNode.getType();

                if (insnType == AbstractInsnNode.LABEL
                        || insnType == AbstractInsnNode.LINE
                        || insnType == AbstractInsnNode.FRAME)
                {
                    merge(insn + 1, f, subroutine);
                    newControlFlowEdge(insn, insn + 1);
                } else {
                    current.init(f).execute(insnNode, interpreter);
                    subroutine = subroutine == null ? null : subroutine.copy();

                    if (insnNode instanceof JumpInsnNode) {
                        JumpInsnNode j = (JumpInsnNode) insnNode;
                        if (insnOpcode != GOTO && insnOpcode != JSR) {
                            merge(insn + 1, current, subroutine);
                            newControlFlowEdge(insn, insn + 1);
                        }
                        int jump = insns.indexOf(j.label);
                        if (insnOpcode == JSR) {
                            merge(jump, current, new Subroutine(j.label,
                                    m.maxLocals,
                                    j));
                        } else {
                            merge(jump, current, subroutine);
                        }
                        newControlFlowEdge(insn, jump);
                    } else if (insnNode instanceof LookupSwitchInsnNode) {
                        LookupSwitchInsnNode lsi = (LookupSwitchInsnNode) insnNode;
                        int jump = insns.indexOf(lsi.dflt);
                        merge(jump, current, subroutine);
                        newControlFlowEdge(insn, jump);
                        for (int j = 0; j < lsi.labels.size(); ++j) {
                            LabelNode label = (LabelNode) lsi.labels.get(j);
                            jump = insns.indexOf(label);
                            merge(jump, current, subroutine);
                            newControlFlowEdge(insn, jump);
                        }
                    } else if (insnNode instanceof TableSwitchInsnNode) {
                        TableSwitchInsnNode tsi = (TableSwitchInsnNode) insnNode;
                        int jump = insns.indexOf(tsi.dflt);
                        merge(jump, current, subroutine);
                        newControlFlowEdge(insn, jump);
                        for (int j = 0; j < tsi.labels.size(); ++j) {
                            LabelNode label = (LabelNode) tsi.labels.get(j);
                            jump = insns.indexOf(label);
                            merge(jump, current, subroutine);
                            newControlFlowEdge(insn, jump);
                        }
                    } else if (insnOpcode == RET) {
                        if (subroutine == null) {
                            throw new AnalyzerException("RET instruction outside of a sub routine");
                        }
                        for (int i = 0; i < subroutine.callers.size(); ++i) {
                            Object caller = subroutine.callers.get(i);
                            int call = insns.indexOf((AbstractInsnNode) caller);
                            if (frames[call] != null) {
                                merge(call + 1,
                                        frames[call],
                                        current,
                                        subroutines[call],
                                        subroutine.access);
                                newControlFlowEdge(insn, call + 1);
                            }
                        }
                    } else if (insnOpcode != ATHROW
                            && (insnOpcode < IRETURN || insnOpcode > RETURN))
                    {
                        if (subroutine != null) {
                            if (insnNode instanceof VarInsnNode) {
                                int var = ((VarInsnNode) insnNode).var;
                                subroutine.access[var] = true;
                                if (insnOpcode == LLOAD || insnOpcode == DLOAD
                                        || insnOpcode == LSTORE