classwriter.java

linux下建立JAVA虚拟机的源码KAFFE

  // --------------------------------------------------------------------------

  /**
   * Computes the instruction types of JVM opcodes.
   */

  static {
    int i;
    byte[] b = new byte[220];
    String s =
      "AAAAAAAAAAAAAAAABCKLLDDDDDEEEEEEEEEEEEEEEEEEEEAAAAAAAADDDDDEEEEEEEEE" +
      "EEEEEEEEEEEAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAMAAA" +
      "AAAAAAAAAAAAAAAAAIIIIIIIIIIIIIIIIDNOAAAAAAGGGGGGGHAFBFAAFFAAQPIIJJII" +
      "IIIIIIIIIIIIIIII";
    for (i = 0; i < b.length; ++i) {
      b[i] = (byte)(s.charAt(i) - 'A');
    }
    TYPE = b;

    /* code to generate the above string

    // SBYTE_INSN instructions
    b[Constants.NEWARRAY] = SBYTE_INSN;
    b[Constants.BIPUSH] = SBYTE_INSN;

    // SHORT_INSN instructions
    b[Constants.SIPUSH] = SHORT_INSN;

    // (IMPL)VAR_INSN instructions
    b[Constants.RET] = VAR_INSN;
    for (i = Constants.ILOAD; i <= Constants.ALOAD; ++i) {
      b[i] = VAR_INSN;
    }
    for (i = Constants.ISTORE; i <= Constants.ASTORE; ++i) {
      b[i] = VAR_INSN;
    }
    for (i = 26; i <= 45; ++i) { // ILOAD_0 to ALOAD_3
      b[i] = IMPLVAR_INSN;
    }
    for (i = 59; i <= 78; ++i) { // ISTORE_0 to ASTORE_3
      b[i] = IMPLVAR_INSN;
    }

    // TYPE_INSN instructions
    b[Constants.NEW] = TYPE_INSN;
    b[Constants.ANEWARRAY] = TYPE_INSN;
    b[Constants.CHECKCAST] = TYPE_INSN;
    b[Constants.INSTANCEOF] = TYPE_INSN;

    // (Set)FIELDORMETH_INSN instructions
    for (i = Constants.GETSTATIC; i <= Constants.INVOKESTATIC; ++i) {
      b[i] = FIELDORMETH_INSN;
    }
    b[Constants.INVOKEINTERFACE] = ITFMETH_INSN;

    // LABEL(W)_INSN instructions
    for (i = Constants.IFEQ; i <= Constants.JSR; ++i) {
      b[i] = LABEL_INSN;
    }
    b[Constants.IFNULL] = LABEL_INSN;
    b[Constants.IFNONNULL] = LABEL_INSN;
    b[200] = LABELW_INSN; // GOTO_W
    b[201] = LABELW_INSN; // JSR_W
    // temporary opcodes used internally by ASM - see Label and CodeWriter
    for (i = 202; i < 220; ++i) {
      b[i] = LABEL_INSN;
    }

    // LDC(_W) instructions
    b[Constants.LDC] = LDC_INSN;
    b[19] = LDCW_INSN; // LDC_W
    b[20] = LDCW_INSN; // LDC2_W

    // special instructions
    b[Constants.IINC] = IINC_INSN;
    b[Constants.TABLESWITCH] = TABL_INSN;
    b[Constants.LOOKUPSWITCH] = LOOK_INSN;
    b[Constants.MULTIANEWARRAY] = MANA_INSN;
    b[196] = WIDE_INSN; // WIDE

    for (i = 0; i < b.length; ++i) {
      System.err.print((char)('A' + b[i]));
    }
    System.err.println();
    */
  }

  // --------------------------------------------------------------------------
  // Constructor
  // --------------------------------------------------------------------------

  /**
   * Constructs a new {@link ClassWriter ClassWriter} object.
   *
   * @param computeMaxs <tt>true</tt> if the maximum stack size and the maximum
   *      number of local variables must be automatically computed. If this flag
   *      is <tt>true</tt>, then the arguments of the {@link
   *      CodeVisitor#visitMaxs visitMaxs} method of the {@link CodeVisitor
   *      CodeVisitor} returned by the {@link #visitMethod visitMethod} method
   *      will be ignored, and computed automatically from the signature and
   *      the bytecode of each method.
   */

  public ClassWriter (final boolean computeMaxs) {
    this(computeMaxs, false);
  }

  /**
   * Constructs a new {@link ClassWriter ClassWriter} object.
   *
   * @param computeMaxs <tt>true</tt> if the maximum stack size and the maximum
   *      number of local variables must be automatically computed. If this flag
   *      is <tt>true</tt>, then the arguments of the {@link
   *      CodeVisitor#visitMaxs visitMaxs} method of the {@link CodeVisitor
   *      CodeVisitor} returned by the {@link #visitMethod visitMethod} method
   *      will be ignored, and computed automatically from the signature and
   *      the bytecode of each method.
   * @param skipUnknownAttributes <tt>true</tt> to silently ignore unknown 
   *      attributes, or <tt>false</tt> to throw an exception if an unknown
   *      attribute is found.
   */

  public ClassWriter (
    final boolean computeMaxs, 
    final boolean skipUnknownAttributes) 
  {
    index = 1;
    pool = new ByteVector();
    items = new Item[64];
    threshold = (int)(0.75d*items.length);
    key = new Item();
    key2 = new Item();
    key3 = new Item();
    this.computeMaxs = computeMaxs;
    this.checkAttributes = !skipUnknownAttributes;
  }

  // --------------------------------------------------------------------------
  // Implementation of the ClassVisitor interface
  // --------------------------------------------------------------------------

  public void visit (
    final int version,
    final int access,
    final String name,
    final String superName,
    final String[] interfaces,
    final String sourceFile)
  {
    this.version = version;
    this.access = access;
    this.name = newClass(name);
    this.superName = superName == null ? 0 : newClass(superName);
    if (interfaces != null && interfaces.length > 0) {
      interfaceCount = interfaces.length;
      this.interfaces = new int[interfaceCount];
      for (int i = 0; i < interfaceCount; ++i) {
        this.interfaces[i] = newClass(interfaces[i]);
      }
    }
    if (sourceFile != null) {
      newUTF8("SourceFile");
      this.sourceFile = newUTF8(sourceFile);
    }
    if ((access & Constants.ACC_DEPRECATED) != 0) {
      newUTF8("Deprecated");
    }
    if ((access & Constants.ACC_SYNTHETIC) != 0) {
      newUTF8("Synthetic");
    }
  }

  public void visitInnerClass (
    final String name,
    final String outerName,
    final String innerName,
    final int access)
  {
    if (innerClasses == null) {
      newUTF8("InnerClasses");
      innerClasses = new ByteVector();
    }
    ++innerClassesCount;
    innerClasses.putShort(name == null ? 0 : newClass(name));
    innerClasses.putShort(outerName == null ? 0 : newClass(outerName));
    innerClasses.putShort(innerName == null ? 0 : newUTF8(innerName));
    innerClasses.putShort(access);
  }

  public void visitField (
    final int access,
    final String name,
    final String desc,
    final Object value,
    final Attribute attrs)
  {
    ++fieldCount;
    if (fields == null) {
      fields = new ByteVector();
    }
    fields.putShort(access).putShort(newUTF8(name)).putShort(newUTF8(desc));
    int attributeCount = 0;
    if (value != null) {
      ++attributeCount;
    }
    if ((access & Constants.ACC_SYNTHETIC) != 0) {
      ++attributeCount;
    }
    if ((access & Constants.ACC_DEPRECATED) != 0) {
      ++attributeCount;
    }
    if (attrs != null) {
      attributeCount += attrs.getCount();
    }
    fields.putShort(attributeCount);
    if (value != null) {
      fields.putShort(newUTF8("ConstantValue"));
      fields.putInt(2).putShort(newConstItem(value).index);
    }
    if ((access & Constants.ACC_SYNTHETIC) != 0) {
      fields.putShort(newUTF8("Synthetic")).putInt(0);
    }
    if ((access & Constants.ACC_DEPRECATED) != 0) {
      fields.putShort(newUTF8("Deprecated")).putInt(0);
    }
    if (attrs != null) {
      attrs.put(this, null, 0, -1, -1, fields);
    }
  }

  public CodeVisitor visitMethod (
    final int access,
    final String name,
    final String desc,
    final String[] exceptions,
    final Attribute attrs)
  {
    CodeWriter cw = new CodeWriter(this, computeMaxs);
    cw.init(access, name, desc, exceptions, attrs);
    return cw;
  }

  public void visitAttribute (final Attribute attr) {
    attr.next = attrs;
    attrs = attr;
  }

  public void visitEnd () {
  }

  // --------------------------------------------------------------------------
  // Other public methods
  // --------------------------------------------------------------------------

  /**
   * Returns the bytecode of the class that was build with this class writer.
   *
   * @return the bytecode of the class that was build with this class writer.
   */

  public byte[] toByteArray () {
    // computes the real size of the bytecode of this class
    int size = 24 + 2*interfaceCount;
    if (fields != null) {
      size += fields.length;
    }
    int nbMethods = 0;
    CodeWriter cb = firstMethod;
    while (cb != null) {
      ++nbMethods;
      size += cb.getSize();
      cb = cb.next;
    }
    int attributeCount = 0;
    if (sourceFile != 0) {
      ++attributeCount;
      size += 8;
    }
    if ((access & Constants.ACC_DEPRECATED) != 0) {
      ++attributeCount;
      size += 6;
    }
    if ((access & Constants.ACC_SYNTHETIC) != 0) {
      ++attributeCount;
      size += 6;
    }
    if (innerClasses != null) {
      ++attributeCount;
      size += 8 + innerClasses.length;
    }
    if (attrs != null) {
      attributeCount += attrs.getCount();
      size += attrs.getSize(this, null, 0, -1, -1);
    }
    size += pool.length;
    // allocates a byte vector of this size, in order to avoid unnecessary
    // arraycopy operations in the ByteVector.enlarge() method
    ByteVector out = new ByteVector(size);
    out.putInt(0xCAFEBABE).putInt(version);
    out.putShort(index).putByteArray(pool.data, 0, pool.length);
    out.putShort(access).putShort(name).putShort(superName);
    out.putShort(interfaceCount);
    for (int i = 0; i < interfaceCount; ++i) {
      out.putShort(interfaces[i]);
    }
    out.putShort(fieldCount);
    if (fields != null) {
      out.putByteArray(fields.data, 0, fields.length);
    }
    out.putShort(nbMethods);
    cb = firstMethod;
    while (cb != null) {
      cb.put(out);
      cb = cb.next;
    }
    out.putShort(attributeCount);
    if (sourceFile != 0) {
      out.putShort(newUTF8("SourceFile")).putInt(2).putShort(sourceFile);
    }
    if ((access & Constants.ACC_DEPRECATED) != 0) {
      out.putShort(newUTF8("Deprecated")).putInt(0);
    }
    if ((access & Constants.ACC_SYNTHETIC) != 0) {
      out.putShort(newUTF8("Synthetic")).putInt(0);
    }
    if (innerClasses != null) {
      out.putShort(newUTF8("InnerClasses"));
      out.putInt(innerClasses.length + 2).putShort(innerClassesCount);
      out.putByteArray(innerClasses.data, 0, innerClasses.length);
    }
    if (attrs != null) {
      attrs.put(this, null, 0, -1, -1, out);
    }
    return out.data;
  }

  // --------------------------------------------------------------------------
  // Utility methods: constant pool management
  // --------------------------------------------------------------------------

  /**
   * Adds a number or string constant to the constant pool of the class being
   * build. Does nothing if the constant pool already contains a similar item.
   *
   * @param cst the value of the constant to be added to the constant pool. This
   *      parameter must be an {@link java.lang.Integer Integer}, a {@link
   *      java.lang.Float Float}, a {@link java.lang.Long Long}, a {@link
   *      java.lang.Double Double}, a {@link String String} or a {@link Type}.
   * @return a new or already existing constant item with the given value.
   */

  Item newConstItem (final Object cst) {
    if (cst instanceof Integer) {
      int val = ((Integer)cst).intValue();
      return newInteger(val);
    } else if (cst instanceof Byte) {
      int val = ((Byte)cst).intValue();
      return newInteger(val);
    } else if (cst instanceof Character) {
      int val = ((Character)cst).charValue();
      return newInteger(val);
    } else if (cst instanceof Short) {
      int val = ((Short)cst).intValue();
      return newInteger(val);
    } else if (cst instanceof Boolean) {
      int val = ((Boolean)cst).booleanValue() ? 1 : 0;
      return newInteger(val);