instructionsequencereplacer.java

ProGuard 是一个免费的 Java类文件的压缩

/*
 * ProGuard -- shrinking, optimization, obfuscation, and preverification
 *             of Java bytecode.
 *
 * Copyright (c) 2002-2007 Eric Lafortune ([e-mail])
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 2 of the License, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */
package proguard.optimize.peephole;

import proguard.classfile.instruction.visitor.InstructionVisitor;
import proguard.classfile.instruction.*;
import proguard.classfile.editor.CodeAttributeEditor;
import proguard.classfile.*;
import proguard.classfile.util.SimplifiedVisitor;
import proguard.classfile.constant.*;
import proguard.classfile.constant.visitor.ConstantVisitor;
import proguard.classfile.attribute.CodeAttribute;

/**
 * This InstructionVisitor replaces a given pattern instruction sequence by
 * another given replacement instruction sequence. The arguments of the
 * instruction sequences can be wildcards that are matched and replaced.
 *
 * @author Eric Lafortune
 */
public class InstructionSequenceReplacer
extends      SimplifiedVisitor
implements   InstructionVisitor,
             ConstantVisitor
{
    private static final boolean DEBUG = false;


    public static final int X = 0x40000000;
    public static final int Y = 0x40000001;
    public static final int Z = 0x40000002;

    public static final int A = 0x40000003;
    public static final int B = 0x40000004;
    public static final int C = 0x40000005;
    public static final int D = 0x40000006;


    private Constant[]          patternConstants;
    private Instruction[]       patternInstructions;
    private Instruction[]       replacementInstructions;
    private BranchTargetFinder  branchTargetFinder;
    private CodeAttributeEditor codeAttributeEditor;
    private InstructionVisitor  extraInstructionVisitor;

    private MyReplacementInstructionFactory replacementInstructionFactory = new MyReplacementInstructionFactory();


    private int   patternInstructionIndex;
    private int[] matchedInstructionOffsets;
    private int   matchedArgumentFlags;
    private int[] matchedArguments = new int[7];
    private int   matchedConstantFlags;
    private int[] matchedConstantIndices;

    // Fields acting as a parameter and a return value for visitor methods.
    private Constant patternConstant;
    private boolean  matchingConstant;


    /**
     * Creates a new InstructionSequenceReplacer.
     * @param patternConstants        any constants referenced by the pattern
     *                                instruction.
     * @param patternInstructions     the pattern instruction sequence.
     * @param replacementInstructions the replacement instruction sequence.
     * @param branchTargetFinder      a branch target finder that has been
     *                                initialized to indicate branch targets
     *                                in the visited code.
     * @param codeAttributeEditor     a code editor that can be used for
     *                                accumulating changes to the code.
     */
    public InstructionSequenceReplacer(Constant[]          patternConstants,
                                       Instruction[]       patternInstructions,
                                       Instruction[]       replacementInstructions,
                                       BranchTargetFinder  branchTargetFinder,
                                       CodeAttributeEditor codeAttributeEditor)
    {
        this(patternConstants,
             patternInstructions,
             replacementInstructions,
             branchTargetFinder,
             codeAttributeEditor,
             null);
    }


    /**
     * Creates a new InstructionSequenceReplacer.
     * @param patternConstants        any constants referenced by the pattern
     *                                instruction.
     * @param branchTargetFinder      a branch target finder that has been
     *                                initialized to indicate branch targets
     *                                in the visited code.
     * @param codeAttributeEditor     a code editor that can be used for
     *                                accumulating changes to the code.
     * @param extraInstructionVisitor an optional extra visitor for all deleted
     *                                load instructions.
     */
    public InstructionSequenceReplacer(Constant[]          patternConstants,
                                       Instruction[]       patternInstructions,
                                       Instruction[]       replacementInstructions,
                                       BranchTargetFinder  branchTargetFinder,
                                       CodeAttributeEditor codeAttributeEditor,
                                       InstructionVisitor  extraInstructionVisitor)
    {
        this.patternConstants        = patternConstants;
        this.patternInstructions     = patternInstructions;
        this.replacementInstructions = replacementInstructions;
        this.branchTargetFinder      = branchTargetFinder;
        this.codeAttributeEditor     = codeAttributeEditor;
        this.extraInstructionVisitor = extraInstructionVisitor;

        matchedInstructionOffsets = new int[patternInstructions.length];
        matchedConstantIndices    = new int[patternConstants.length];
    }


    // Implementations for InstructionVisitor.

    public void visitSimpleInstruction(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, SimpleInstruction simpleInstruction)
    {
        Instruction patternInstruction = patternInstructions[patternInstructionIndex];

        // Check if the instruction matches the next instruction in the from
        // sequence.
        boolean condition =
            acceptableOffset(offset) &&
            matchingOpcodes(simpleInstruction, patternInstruction) &&
            matchingArguments(simpleInstruction.constant,
                              ((SimpleInstruction)patternInstruction).constant);

        // Act on it.
        matchInstruction(condition,
                         clazz,
                         method,
                         codeAttribute,
                         offset,
                         simpleInstruction);
    }


    public void visitVariableInstruction(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, VariableInstruction variableInstruction)
    {
        Instruction patternInstruction = patternInstructions[patternInstructionIndex];

        // Check if the instruction matches the next instruction in the from
        // sequence.
        boolean condition =
            acceptableOffset(offset) &&
            matchingOpcodes(variableInstruction, patternInstruction) &&
            matchingArguments(variableInstruction.variableIndex,
                              ((VariableInstruction)patternInstruction).variableIndex) &&
            matchingArguments(variableInstruction.constant,
                              ((VariableInstruction)patternInstruction).constant);

        // Act on it.
        matchInstruction(condition,
                         clazz,
                         method,
                         codeAttribute,
                         offset,
                         variableInstruction);
    }


    public void visitConstantInstruction(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, ConstantInstruction constantInstruction)
    {
        Instruction patternInstruction = patternInstructions[patternInstructionIndex];

        // Check if the instruction matches the next instruction in the from
        // sequence.
        boolean condition =
            acceptableOffset(offset) &&
            matchingOpcodes(constantInstruction, patternInstruction) &&
            matchingConstantIndices(clazz,
                                    constantInstruction.constantIndex,
                                    ((ConstantInstruction)patternInstruction).constantIndex) &&
            matchingArguments(constantInstruction.constant,
                              ((ConstantInstruction)patternInstruction).constant);

        // Act on it.
        matchInstruction(condition,
                         clazz,
                         method,
                         codeAttribute,
                         offset,
                         constantInstruction);
    }


    public void visitBranchInstruction(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, BranchInstruction branchInstruction)
    {
        Instruction patternInstruction = patternInstructions[patternInstructionIndex];

        // Check if the instruction matches the next instruction in the from
        // sequence.
        boolean condition =
            acceptableOffset(offset) &&
            matchingOpcodes(branchInstruction, patternInstruction) &&
            matchingBranchOffsets(offset,
                                  branchInstruction.branchOffset,
                                  ((BranchInstruction)patternInstruction).branchOffset);

        // Act on it.
        matchInstruction(condition,
                         clazz,
                         method,
                         codeAttribute,
                         offset,
                         branchInstruction);
    }


    public void visitTableSwitchInstruction(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, TableSwitchInstruction tableSwitchInstruction)
    {
        Instruction patternInstruction = patternInstructions[patternInstructionIndex];

        // Check if the instruction matches the next instruction in the from
        // sequence.
        boolean condition =
            acceptableOffset(offset) &&
            matchingOpcodes(tableSwitchInstruction, patternInstruction) &&
            matchingArguments(offset + tableSwitchInstruction.defaultOffset,
                              ((TableSwitchInstruction)patternInstruction).defaultOffset) &&
            matchingArguments(tableSwitchInstruction.lowCase,
                              ((TableSwitchInstruction)patternInstruction).lowCase)  &&
            matchingArguments(tableSwitchInstruction.highCase,
                              ((TableSwitchInstruction)patternInstruction).highCase) &&
            matchingArguments(tableSwitchInstruction.jumpOffsetCount,
                              ((TableSwitchInstruction)patternInstruction).jumpOffsetCount) &&
            matchingJumpOffsets(offset,
                                tableSwitchInstruction.jumpOffsets,
                                ((TableSwitchInstruction)patternInstruction).jumpOffsets,
                                tableSwitchInstruction.jumpOffsetCount);

        // Act on it.
        matchInstruction(condition,
                         clazz,
                         method,
                         codeAttribute,
                         offset,
                         tableSwitchInstruction);