instructionfactory.java

Java Bytecode Editor 是一个 JAVA 的字节码反汇编和修改器。它可以很方便的修改已经编译成 Class 文件的 JAVA 文件。

    case '*' : return LMUL;
    case '/' : return LDIV;
    case '&' : return LAND;
    case '|' : return LOR;
    case '^' : return LXOR;
    case '<' : return LSHL;
    case '>' : return op.equals(">>>")? (ArithmeticInstruction)LUSHR :
      (ArithmeticInstruction)LSHR;
    default: throw new RuntimeException("Invalid operand " + op);
    }
  }

  private static final ArithmeticInstruction createBinaryFloatOp(char op) {
    switch(op) {
    case '-' : return FSUB;
    case '+' : return FADD;
    case '*' : return FMUL;
    case '/' : return FDIV;
    default: throw new RuntimeException("Invalid operand " + op);
    }
  }

  private static final ArithmeticInstruction createBinaryDoubleOp(char op) {
    switch(op) {
    case '-' : return DSUB;
    case '+' : return DADD;
    case '*' : return DMUL;
    case '/' : return DDIV;
    default: throw new RuntimeException("Invalid operand " + op);
    }
  }

  /**
   * Create binary operation for simple basic types, such as int and float.
   *
   * @param op operation, such as "+", "*", "<<", etc.
   */
  public static ArithmeticInstruction createBinaryOperation(String op, Type type) {
    char first = op.toCharArray()[0];

    switch(type.getType()) {
    case Constants.T_BYTE:
    case Constants.T_SHORT:
    case Constants.T_INT:
    case Constants.T_CHAR:    return createBinaryIntOp(first, op);
    case Constants.T_LONG:    return createBinaryLongOp(first, op);
    case Constants.T_FLOAT:   return createBinaryFloatOp(first);
    case Constants.T_DOUBLE:  return createBinaryDoubleOp(first);
    default:        throw new RuntimeException("Invalid type " + type);
    }
  }

  /**
   * @param size size of operand, either 1 (int, e.g.) or 2 (double)
   */
  public static StackInstruction createPop(int size) {
    return (size == 2)? (StackInstruction)POP2 :
      (StackInstruction)POP;
  }

  /**
   * @param size size of operand, either 1 (int, e.g.) or 2 (double)
   */
  public static StackInstruction createDup(int size) {
    return (size == 2)? (StackInstruction)DUP2 :
      (StackInstruction)DUP;
  }

  /**
   * @param size size of operand, either 1 (int, e.g.) or 2 (double)
   */
  public static StackInstruction createDup_2(int size) {
    return (size == 2)? (StackInstruction)DUP2_X2 :
      (StackInstruction)DUP_X2;
  }

  /**
   * @param size size of operand, either 1 (int, e.g.) or 2 (double)
   */
  public static StackInstruction createDup_1(int size) {
    return (size == 2)? (StackInstruction)DUP2_X1 :
      (StackInstruction)DUP_X1;
  }

  /**
   * @param index index of local variable
   */
  public static LocalVariableInstruction createStore(Type type, int index) {
    switch(type.getType()) {
    case Constants.T_BOOLEAN:
    case Constants.T_CHAR:
    case Constants.T_BYTE:
    case Constants.T_SHORT:
    case Constants.T_INT:    return new ISTORE(index);
    case Constants.T_FLOAT:  return new FSTORE(index);
    case Constants.T_DOUBLE: return new DSTORE(index);
    case Constants.T_LONG:   return new LSTORE(index);
    case Constants.T_ARRAY:
    case Constants.T_OBJECT: return new ASTORE(index);
    default:       throw new RuntimeException("Invalid type " + type);
    }
  }

  /**
   * @param index index of local variable
   */
  public static LocalVariableInstruction createLoad(Type type, int index) {
    switch(type.getType()) {
    case Constants.T_BOOLEAN:
    case Constants.T_CHAR:
    case Constants.T_BYTE:
    case Constants.T_SHORT:
    case Constants.T_INT:    return new ILOAD(index);
    case Constants.T_FLOAT:  return new FLOAD(index);
    case Constants.T_DOUBLE: return new DLOAD(index);
    case Constants.T_LONG:   return new LLOAD(index);
    case Constants.T_ARRAY:
    case Constants.T_OBJECT: return new ALOAD(index);
    default:       throw new RuntimeException("Invalid type " + type);
    }
  }

  /**
   * @param type type of elements of array, i.e., array.getElementType()
   */
  public static ArrayInstruction createArrayLoad(Type type) {
    switch(type.getType()) {
    case Constants.T_BOOLEAN:
    case Constants.T_BYTE:   return BALOAD;
    case Constants.T_CHAR:   return CALOAD;
    case Constants.T_SHORT:  return SALOAD;
    case Constants.T_INT:    return IALOAD;
    case Constants.T_FLOAT:  return FALOAD;
    case Constants.T_DOUBLE: return DALOAD;
    case Constants.T_LONG:   return LALOAD;
    case Constants.T_ARRAY:
    case Constants.T_OBJECT: return AALOAD;
    default:       throw new RuntimeException("Invalid type " + type);
    }
  }

  /**
   * @param type type of elements of array, i.e., array.getElementType()
   */
  public static ArrayInstruction createArrayStore(Type type) {
    switch(type.getType()) {
    case Constants.T_BOOLEAN:
    case Constants.T_BYTE:   return BASTORE;
    case Constants.T_CHAR:   return CASTORE;
    case Constants.T_SHORT:  return SASTORE;
    case Constants.T_INT:    return IASTORE;
    case Constants.T_FLOAT:  return FASTORE;
    case Constants.T_DOUBLE: return DASTORE;
    case Constants.T_LONG:   return LASTORE;
    case Constants.T_ARRAY:
    case Constants.T_OBJECT: return AASTORE;
    default:       throw new RuntimeException("Invalid type " + type);
    }
  }


  /** Create conversion operation for two stack operands, this may be an I2C, instruction, e.g.,
   * if the operands are basic types and CHECKCAST if they are reference types.
   */
  public Instruction createCast(Type src_type, Type dest_type) {
    if((src_type instanceof BasicType) && (dest_type instanceof BasicType)) {
      byte dest = dest_type.getType();
      byte src  = src_type.getType();

      if(dest == Constants.T_LONG && (src == Constants.T_CHAR || src == Constants.T_BYTE ||
				      src == Constants.T_SHORT))
	src = Constants.T_INT;

      String[] short_names = { "C", "F", "D", "B", "S", "I", "L" };

      String name = "org.apache.bcel.generic." + short_names[src - Constants.T_CHAR] +
	"2" + short_names[dest - Constants.T_CHAR];
      
      Instruction i = null;
      try {
	i = (Instruction)java.lang.Class.forName(name).newInstance();
      } catch(Exception e) {
	throw new RuntimeException("Could not find instruction: " + name);
      }

      return i;
    } else if((src_type instanceof ReferenceType) && (dest_type instanceof ReferenceType)) {
      if(dest_type instanceof ArrayType)
	return new CHECKCAST(cp.addArrayClass((ArrayType)dest_type));
      else
	return new CHECKCAST(cp.addClass(((ObjectType)dest_type).getClassName()));
    }
    else
      throw new RuntimeException("Can not cast " + src_type + " to " + dest_type);
  }

  public GETFIELD createGetField(String class_name, String name, Type t) {
    return new GETFIELD(cp.addFieldref(class_name, name, t.getSignature()));
  }

  public GETSTATIC createGetStatic(String class_name, String name, Type t) {
    return new GETSTATIC(cp.addFieldref(class_name, name, t.getSignature()));
  }

  public PUTFIELD createPutField(String class_name, String name, Type t) {
    return new PUTFIELD(cp.addFieldref(class_name, name, t.getSignature()));
  }

  public PUTSTATIC createPutStatic(String class_name, String name, Type t) {
    return new PUTSTATIC(cp.addFieldref(class_name, name, t.getSignature()));
  }

  public CHECKCAST createCheckCast(ReferenceType t) {
    if(t instanceof ArrayType)
      return new CHECKCAST(cp.addArrayClass((ArrayType)t));
    else
      return new CHECKCAST(cp.addClass((ObjectType)t));
  }

  public INSTANCEOF createInstanceOf(ReferenceType t) {
    if(t instanceof ArrayType)
      return new INSTANCEOF(cp.addArrayClass((ArrayType)t));
    else
      return new INSTANCEOF(cp.addClass((ObjectType)t));
  }

  public NEW createNew(ObjectType t) {
    return new NEW(cp.addClass(t));
  }

  public NEW createNew(String s) {
    return createNew(new ObjectType(s));
  }

  /** Create new array of given size and type.
   * @return an instruction that creates the corresponding array at runtime, i.e. is an AllocationInstruction
   */
  public Instruction createNewArray(Type t, short dim) {
    if(dim == 1) {
      if(t instanceof ObjectType)
	return new ANEWARRAY(cp.addClass((ObjectType)t));
      else if(t instanceof ArrayType)
	return new ANEWARRAY(cp.addArrayClass((ArrayType)t));
      else
	return new NEWARRAY(((BasicType)t).getType());
    } else {
      ArrayType at;

      if(t instanceof ArrayType)
	at = (ArrayType)t;
      else
	at = new ArrayType(t, dim);

      return new MULTIANEWARRAY(cp.addArrayClass(at), dim);
    }
  }

  /** Create "null" value for reference types, 0 for basic types like int
   */
  public static Instruction createNull(Type type) {
    switch(type.getType()) {
    case Constants.T_ARRAY:
    case Constants.T_OBJECT:  return ACONST_NULL;
    case Constants.T_INT:
    case Constants.T_SHORT:
    case Constants.T_BOOLEAN:
    case Constants.T_CHAR: 
    case Constants.T_BYTE:    return ICONST_0;
    case Constants.T_FLOAT:   return FCONST_0;
    case Constants.T_DOUBLE:  return DCONST_0;
    case Constants.T_LONG:    return LCONST_0;
    case Constants.T_VOID:    return NOP;

    default:
      throw new RuntimeException("Invalid type: " + type);
    }
  }

  /** Create branch instruction by given opcode, except LOOKUPSWITCH and TABLESWITCH.
   * For those you should use the SWITCH compound instruction.
   */
  public static BranchInstruction createBranchInstruction(short opcode, InstructionHandle target) {
    switch(opcode) {
    case Constants.IFEQ:      return new IFEQ(target);
    case Constants.IFNE:      return new IFNE(target);
    case Constants.IFLT:      return new IFLT(target);
    case Constants.IFGE:      return new IFGE(target);
    case Constants.IFGT:      return new IFGT(target);
    case Constants.IFLE:      return new IFLE(target);
    case Constants.IF_ICMPEQ: return new IF_ICMPEQ(target);
    case Constants.IF_ICMPNE: return new IF_ICMPNE(target);
    case Constants.IF_ICMPLT: return new IF_ICMPLT(target);
    case Constants.IF_ICMPGE: return new IF_ICMPGE(target);
    case Constants.IF_ICMPGT: return new IF_ICMPGT(target);
    case Constants.IF_ICMPLE: return new IF_ICMPLE(target);
    case Constants.IF_ACMPEQ: return new IF_ACMPEQ(target);
    case Constants.IF_ACMPNE: return new IF_ACMPNE(target);
    case Constants.GOTO:      return new GOTO(target);
    case Constants.JSR:       return new JSR(target);
    case Constants.IFNULL:    return new IFNULL(target);
    case Constants.IFNONNULL: return new IFNONNULL(target);
    case Constants.GOTO_W:    return new GOTO_W(target);
    case Constants.JSR_W:     return new JSR_W(target);
    default:
	throw new RuntimeException("Invalid opcode: " + opcode);
    }
  }

  public void            setClassGen(ClassGen c)            { cg = c; }
  public ClassGen        getClassGen()                      { return cg; }
  public void            setConstantPool(ConstantPoolGen c) { cp = c; }
  public ConstantPoolGen getConstantPool()                  { return cp; }
}