ASM: a very small and fast Java bytecode manipulation framework
Copyright (c) 2000-2011 INRIA, France Telecom
All rights reserved.
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   this software without specific prior written permission.
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/***
 * ASM: a very small and fast Java bytecode manipulation framework
 * Copyright (c) 2000-2011 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;

A MethodVisitor that generates methods in bytecode form. Each visit method of this class appends the bytecode corresponding to the visited instruction to a byte vector, in the order these methods are called. 
Author:
Eric Bruneton, Eugene Kuleshov/**
 * A {@link MethodVisitor} that generates methods in bytecode form. Each visit
 * method of this class appends the bytecode corresponding to the visited
 * instruction to a byte vector, in the order these methods are called.
 * 
 * @author Eric Bruneton
 * @author Eugene Kuleshov
 */
class MethodWriter extends MethodVisitor {

    
Pseudo access flag used to denote constructors.
/**
     * Pseudo access flag used to denote constructors.
     */
    static final int ACC_CONSTRUCTOR = 0x80000;
    
    
Frame has exactly the same locals as the previous stack map frame and
number of stack items is zero.
/**
     * Frame has exactly the same locals as the previous stack map frame and
     * number of stack items is zero.
     */
    static final int SAME_FRAME = 0; // to 63 (0-3f)

    
Frame has exactly the same locals as the previous stack map frame and
number of stack items is 1
/**
     * Frame has exactly the same locals as the previous stack map frame and
     * number of stack items is 1
     */
    static final int SAME_LOCALS_1_STACK_ITEM_FRAME = 64; // to 127 (40-7f)

    
Reserved for future use
/**
     * Reserved for future use
     */
    static final int RESERVED = 128;

    
Frame has exactly the same locals as the previous stack map frame and
number of stack items is 1. Offset is bigger then 63;
/**
     * Frame has exactly the same locals as the previous stack map frame and
     * number of stack items is 1. Offset is bigger then 63;
     */
    static final int SAME_LOCALS_1_STACK_ITEM_FRAME_EXTENDED = 247; // f7

    
Frame where current locals are the same as the locals in the previous
frame, except that the k last locals are absent. The value of k is given
by the formula 251-frame_type.
/**
     * Frame where current locals are the same as the locals in the previous
     * frame, except that the k last locals are absent. The value of k is given
     * by the formula 251-frame_type.
     */
    static final int CHOP_FRAME = 248; // to 250 (f8-fA)

    
Frame has exactly the same locals as the previous stack map frame and
number of stack items is zero. Offset is bigger then 63;
/**
     * Frame has exactly the same locals as the previous stack map frame and
     * number of stack items is zero. Offset is bigger then 63;
     */
    static final int SAME_FRAME_EXTENDED = 251; // fb

    
Frame where current locals are the same as the locals in the previous
frame, except that k additional locals are defined. The value of k is
given by the formula frame_type-251.
/**
     * Frame where current locals are the same as the locals in the previous
     * frame, except that k additional locals are defined. The value of k is
     * given by the formula frame_type-251.
     */
    static final int APPEND_FRAME = 252; // to 254 // fc-fe

    
Full frame
/**
     * Full frame
     */
    static final int FULL_FRAME = 255; // ff

    
Indicates that the stack map frames must be recomputed from scratch. In
this case the maximum stack size and number of local variables is also
recomputed from scratch.
See Also:
compute/**
     * Indicates that the stack map frames must be recomputed from scratch. In
     * this case the maximum stack size and number of local variables is also
     * recomputed from scratch.
     * 
     * @see #compute
     */
    private static final int FRAMES = 0;

    
Indicates that the maximum stack size and number of local variables must
be automatically computed.
See Also:
compute/**
     * Indicates that the maximum stack size and number of local variables must
     * be automatically computed.
     * 
     * @see #compute
     */
    private static final int MAXS = 1;

    
Indicates that nothing must be automatically computed.
See Also:
compute/**
     * Indicates that nothing must be automatically computed.
     * 
     * @see #compute
     */
    private static final int NOTHING = 2;

    
The class writer to which this method must be added.
/**
     * The class writer to which this method must be added.
     */
    final ClassWriter cw;

    
Access flags of this method.
/**
     * Access flags of this method.
     */
    private int access;

    
The index of the constant pool item that contains the name of this
method.
/**
     * The index of the constant pool item that contains the name of this
     * method.
     */
    private final int name;

    
The index of the constant pool item that contains the descriptor of this
method.
/**
     * The index of the constant pool item that contains the descriptor of this
     * method.
     */
    private final int desc;

    
The descriptor of this method.
/**
     * The descriptor of this method.
     */
    private final String descriptor;

    
The signature of this method.
/**
     * The signature of this method.
     */
    String signature;

    
If not zero, indicates that the code of this method must be copied from
the ClassReader associated to this writer in cw.cr. More
precisely, this field gives the index of the first byte to copied from
cw.cr.b.
/**
     * If not zero, indicates that the code of this method must be copied from
     * the ClassReader associated to this writer in <code>cw.cr</code>. More
     * precisely, this field gives the index of the first byte to copied from
     * <code>cw.cr.b</code>.
     */
    int classReaderOffset;

    
If not zero, indicates that the code of this method must be copied from
the ClassReader associated to this writer in cw.cr. More
precisely, this field gives the number of bytes to copied from
cw.cr.b.
/**
     * If not zero, indicates that the code of this method must be copied from
     * the ClassReader associated to this writer in <code>cw.cr</code>. More
     * precisely, this field gives the number of bytes to copied from
     * <code>cw.cr.b</code>.
     */
    int classReaderLength;

    
Number of exceptions that can be thrown by this method.
/**
     * Number of exceptions that can be thrown by this method.
     */
    int exceptionCount;

    
The exceptions that can be thrown by this method. More precisely, this
array contains the indexes of the constant pool items that contain the
internal names of these exception classes.
/**
     * The exceptions that can be thrown by this method. More precisely, this
     * array contains the indexes of the constant pool items that contain the
     * internal names of these exception classes.
     */
    int[] exceptions;

    
The annotation default attribute of this method. May be null.
/**
     * The annotation default attribute of this method. May be <tt>null</tt>.
     */
    private ByteVector annd;

    
The runtime visible annotations of this method. May be null.
/**
     * The runtime visible annotations of this method. May be <tt>null</tt>.
     */
    private AnnotationWriter anns;

    
The runtime invisible annotations of this method. May be null.
/**
     * The runtime invisible annotations of this method. May be <tt>null</tt>.
     */
    private AnnotationWriter ianns;

    
The runtime visible parameter annotations of this method. May be
null.
/**
     * The runtime visible parameter annotations of this method. May be
     * <tt>null</tt>.
     */
    private AnnotationWriter[] panns;

    
The runtime invisible parameter annotations of this method. May be
null.
/**
     * The runtime invisible parameter annotations of this method. May be
     * <tt>null</tt>.
     */
    private AnnotationWriter[] ipanns;

    
The number of synthetic parameters of this method.
/**
     * The number of synthetic parameters of this method.
     */
    private int synthetics;

    
The non standard attributes of the method.
/**
     * The non standard attributes of the method.
     */
    private Attribute attrs;

    
The bytecode of this method.
/**
     * The bytecode of this method.
     */
    private ByteVector code = new ByteVector();

    
Maximum stack size of this method.
/**
     * Maximum stack size of this method.
     */
    private int maxStack;

    
Maximum number of local variables for this method.
/**
     * Maximum number of local variables for this method.
     */
    private int maxLocals;

    
Number of local variables in the current stack map frame.
/**
     * Number of local variables in the current stack map frame.
     */
    private int currentLocals;

    
Number of stack map frames in the StackMapTable attribute.
/**
     * Number of stack map frames in the StackMapTable attribute.
     */
    private int frameCount;

    
The StackMapTable attribute.
/**
     * The StackMapTable attribute.
     */
    private ByteVector stackMap;

    
The offset of the last frame that was written in the StackMapTable
attribute.
/**
     * The offset of the last frame that was written in the StackMapTable
     * attribute.
     */
    private int previousFrameOffset;

    
The last frame that was written in the StackMapTable attribute.
See Also:
frame/**
     * The last frame that was written in the StackMapTable attribute.
     * 
     * @see #frame
     */
    private int[] previousFrame;

    
The current stack map frame. The first element contains the offset of the instruction to which the frame corresponds, the second element is the number of locals and the third one is the number of stack elements. The local variables start at index 3 and are followed by the operand stack values. In summary frame[0] = offset, frame[1] = nLocal, frame[2] = nStack, frame[3] = nLocal. All types are encoded as integers, with the same format as the one used in Label, but limited to BASE types. /**
     * The current stack map frame. The first element contains the offset of the
     * instruction to which the frame corresponds, the second element is the
     * number of locals and the third one is the number of stack elements. The
     * local variables start at index 3 and are followed by the operand stack
     * values. In summary frame[0] = offset, frame[1] = nLocal, frame[2] =
     * nStack, frame[3] = nLocal. All types are encoded as integers, with the
     * same format as the one used in {@link Label}, but limited to BASE types.
     */
    private int[] frame;

    
Number of elements in the exception handler list.
/**
     * Number of elements in the exception handler list.
     */
    private int handlerCount;

    
The first element in the exception handler list.
/**
     * The first element in the exception handler list.
     */
    private Handler firstHandler;

    
The last element in the exception handler list.
/**
     * The last element in the exception handler list.
     */
    private Handler lastHandler;

    
Number of entries in the LocalVariableTable attribute.
/**
     * Number of entries in the LocalVariableTable attribute.
     */
    private int localVarCount;

    
The LocalVariableTable attribute.
/**
     * The LocalVariableTable attribute.
     */
    private ByteVector localVar;

    
Number of entries in the LocalVariableTypeTable attribute.
/**
     * Number of entries in the LocalVariableTypeTable attribute.
     */
    private int localVarTypeCount;

    
The LocalVariableTypeTable attribute.
/**
     * The LocalVariableTypeTable attribute.
     */
    private ByteVector localVarType;

    
Number of entries in the LineNumberTable attribute.
/**
     * Number of entries in the LineNumberTable attribute.
     */
    private int lineNumberCount;

    
The LineNumberTable attribute.
/**
     * The LineNumberTable attribute.
     */
    private ByteVector lineNumber;

    
The non standard attributes of the method's code.
/**
     * The non standard attributes of the method's code.
     */
    private Attribute cattrs;

    
Indicates if some jump instructions are too small and need to be resized.
/**
     * Indicates if some jump instructions are too small and need to be resized.
     */
    private boolean resize;

    
The number of subroutines in this method.
/**
     * The number of subroutines in this method.
     */
    private int subroutines;

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

    /*
     * Fields for the control flow graph analysis algorithm (used to compute the
     * maximum stack size). A control flow graph contains one node per "basic
     * block", and one edge per "jump" from one basic block to another. Each
     * node (i.e., each basic block) is represented by the Label object that
     * corresponds to the first instruction of this basic block. Each node also
     * stores the list of its successors in the graph, as a linked list of Edge
     * objects.
     */

    
Indicates what must be automatically computed.
See Also:
FRAMES
MAXS
NOTHING/**
     * Indicates what must be automatically computed.
     * 
     * @see #FRAMES
     * @see #MAXS
     * @see #NOTHING
     */
    private final int compute;

    
A list of labels. This list is the list of basic blocks in the method, i.e. a list of Label objects linked to each other by their Label.successor field, in the order they are visited by MethodVisitor.visitLabel, and starting with the first basic block. /**
     * A list of labels. This list is the list of basic blocks in the method,
     * i.e. a list of Label objects linked to each other by their
     * {@link Label#successor} field, in the order they are visited by
     * {@link MethodVisitor#visitLabel}, and starting with the first basic
     * block.
     */
    private Label labels;

    
The previous basic block.
/**
     * The previous basic block.
     */
    private Label previousBlock;

    
The current basic block.
/**
     * The current basic block.
     */
    private Label currentBlock;

    
The (relative) stack size after the last visited instruction. This size is relative to the beginning of the current basic block, i.e., the true stack size after the last visited instruction is equal to the beginStackSize of the current basic block plus stackSize.
/**
     * The (relative) stack size after the last visited instruction. This size
     * is relative to the beginning of the current basic block, i.e., the true
     * stack size after the last visited instruction is equal to the
     * {@link Label#inputStackTop beginStackSize} of the current basic block
     * plus <tt>stackSize</tt>.
     */
    private int stackSize;

    
The (relative) maximum stack size after the last visited instruction. This size is relative to the beginning of the current basic block, i.e., the true maximum stack size after the last visited instruction is equal to the beginStackSize of the current basic block plus stackSize.
/**
     * The (relative) maximum stack size after the last visited instruction.
     * This size is relative to the beginning of the current basic block, i.e.,
     * the true maximum stack size after the last visited instruction is equal
     * to the {@link Label#inputStackTop beginStackSize} of the current basic
     * block plus <tt>stackSize</tt>.
     */
    private int maxStackSize;

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

    
Constructs a new MethodWriter. 
Params:
cw – 
           the class writer in which the method must be added.
access –  the method's access flags (see Opcodes).
name – 
           the method's name.
desc –  the method's descriptor (see Type).
signature – 
           the method's signature. May be null.
exceptions – 
           the internal names of the method's exceptions. May be
           null.
computeMaxs – 
           true if the maximum stack size and number of local
           variables must be automatically computed.
computeFrames – 
           true if the stack map tables must be recomputed from
           scratch./**
     * Constructs a new {@link MethodWriter}.
     * 
     * @param cw
     *            the class writer in which the method must be added.
     * @param access
     *            the method's access flags (see {@link Opcodes}).
     * @param name
     *            the method's name.
     * @param desc
     *            the method's descriptor (see {@link Type}).
     * @param signature
     *            the method's signature. May be <tt>null</tt>.
     * @param exceptions
     *            the internal names of the method's exceptions. May be
     *            <tt>null</tt>.
     * @param computeMaxs
     *            <tt>true</tt> if the maximum stack size and number of local
     *            variables must be automatically computed.
     * @param computeFrames
     *            <tt>true</tt> if the stack map tables must be recomputed from
     *            scratch.
     */
    MethodWriter(final ClassWriter cw, final int access, final String name,
            final String desc, final String signature,
            final String[] exceptions, final boolean computeMaxs,
            final boolean computeFrames) {
        super(Opcodes.ASM4);
        if (cw.firstMethod == null) {
            cw.firstMethod = this;
        } else {
            cw.lastMethod.mv = this;
        }
        cw.lastMethod = this;
        this.cw = cw;
        this.access = access;
        if ("<init>".equals(name)) {
            this.access |= ACC_CONSTRUCTOR;
        }
        this.name = cw.newUTF8(name);
        this.desc = cw.newUTF8(desc);
        this.descriptor = desc;
        if (ClassReader.SIGNATURES) {
            this.signature = signature;
        }
        if (exceptions != null && exceptions.length > 0) {
            exceptionCount = exceptions.length;
            this.exceptions = new int[exceptionCount];
            for (int i = 0; i < exceptionCount; ++i) {
                this.exceptions[i] = cw.newClass(exceptions[i]);
            }
        }
        this.compute = computeFrames ? FRAMES : (computeMaxs ? MAXS : NOTHING);
        if (computeMaxs || computeFrames) {
            // updates maxLocals
            int size = Type.getArgumentsAndReturnSizes(descriptor) >> 2;
            if ((access & Opcodes.ACC_STATIC) != 0) {
                --size;
            }
            maxLocals = size;
            currentLocals = size;
            // creates and visits the label for the first basic block
            labels = new Label();
            labels.status |= Label.PUSHED;
            visitLabel(labels);
        }
    }

    // ------------------------------------------------------------------------
    // Implementation of the MethodVisitor abstract class
    // ------------------------------------------------------------------------

    @Override
    public AnnotationVisitor visitAnnotationDefault() {
        if (!ClassReader.ANNOTATIONS) {
            return null;
        }
        annd = new ByteVector();
        return new AnnotationWriter(cw, false, annd, null, 0);
    }

    @Override
    public AnnotationVisitor visitAnnotation(final String desc,
            final boolean visible) {
        if (!ClassReader.ANNOTATIONS) {
            return null;
        }
        ByteVector bv = new ByteVector();
        // write type, and reserve space for values count
        bv.putShort(cw.newUTF8(desc)).putShort(0);
        AnnotationWriter aw = new AnnotationWriter(cw, true, bv, bv, 2);
        if (visible) {
            aw.next = anns;
            anns = aw;
        } else {
            aw.next = ianns;
            ianns = aw;
        }
        return aw;
    }

    @Override
    public AnnotationVisitor visitParameterAnnotation(final int parameter,
            final String desc, final boolean visible) {
        if (!ClassReader.ANNOTATIONS) {
            return null;
        }
        ByteVector bv = new ByteVector();
        if ("Ljava/lang/Synthetic;".equals(desc)) {
            // workaround for a bug in javac with synthetic parameters
            // see ClassReader.readParameterAnnotations
            synthetics = Math.max(synthetics, parameter + 1);
            return new AnnotationWriter(cw, false, bv, null, 0);
        }
        // write type, and reserve space for values count
        bv.putShort(cw.newUTF8(desc)).putShort(0);
        AnnotationWriter aw = new AnnotationWriter(cw, true, bv, bv, 2);
        if (visible) {
            if (panns == null) {
                panns = new AnnotationWriter[Type.getArgumentTypes(descriptor).length];
            }
            aw.next = panns[parameter];
            panns[parameter] = aw;
        } else {
            if (ipanns == null) {
                ipanns = new AnnotationWriter[Type.getArgumentTypes(descriptor).length];
            }
            aw.next = ipanns[parameter];
            ipanns[parameter] = aw;
        }
        return aw;
    }

    @Override
    public void visitAttribute(final Attribute attr) {
        if (attr.isCodeAttribute()) {
            attr.next = cattrs;
            cattrs = attr;
        } else {
            attr.next = attrs;
            attrs = attr;
        }
    }

    @Override
    public void visitCode() {
    }

    @Override
    public void visitFrame(final int type, final int nLocal,
            final Object[] local, final int nStack, final Object[] stack) {
        if (!ClassReader.FRAMES || compute == FRAMES) {
            return;
        }

        if (type == Opcodes.F_NEW) {
            if (previousFrame == null) {
                visitImplicitFirstFrame();
            }
            currentLocals = nLocal;
            int frameIndex = startFrame(code.length, nLocal, nStack);
            for (int i = 0; i < nLocal; ++i) {
                if (local[i] instanceof String) {
                    frame[frameIndex++] = Frame.OBJECT
                            | cw.addType((String) local[i]);
                } else if (local[i] instanceof Integer) {
                    frame[frameIndex++] = ((Integer) local[i]).intValue();
                } else {
                    frame[frameIndex++] = Frame.UNINITIALIZED
                            | cw.addUninitializedType("",
                                    ((Label) local[i]).position);
                }
            }
            for (int i = 0; i < nStack; ++i) {
                if (stack[i] instanceof String) {
                    frame[frameIndex++] = Frame.OBJECT
                            | cw.addType((String) stack[i]);
                } else if (stack[i] instanceof Integer) {
                    frame[frameIndex++] = ((Integer) stack[i]).intValue();
                } else {
                    frame[frameIndex++] = Frame.UNINITIALIZED
                            | cw.addUninitializedType("",
                                    ((Label) stack[i]).position);
                }
            }
            endFrame();
        } else {
            int delta;
            if (stackMap == null) {
                stackMap = new ByteVector();
                delta = code.length;
            } else {
                delta = code.length - previousFrameOffset - 1;
                if (delta < 0) {
                    if (type == Opcodes.F_SAME) {
                        return;
                    } else {
                        throw new IllegalStateException();
                    }
                }
            }

            switch (type) {
            case Opcodes.F_FULL:
                currentLocals = nLocal;
                stackMap.putByte(FULL_FRAME).putShort(delta).putShort(nLocal);
                for (int i = 0; i < nLocal; ++i) {
                    writeFrameType(local[i]);
                }
                stackMap.putShort(nStack);
                for (int i = 0; i < nStack; ++i) {
                    writeFrameType(stack[i]);
                }
                break;
            case Opcodes.F_APPEND:
                currentLocals += nLocal;
                stackMap.putByte(SAME_FRAME_EXTENDED + nLocal).putShort(delta);
                for (int i = 0; i < nLocal; ++i) {
                    writeFrameType(local[i]);
                }
                break;
            case Opcodes.F_CHOP:
                currentLocals -= nLocal;
                stackMap.putByte(SAME_FRAME_EXTENDED - nLocal).putShort(delta);
                break;
            case Opcodes.F_SAME:
                if (delta < 64) {
                    stackMap.putByte(delta);
                } else {
                    stackMap.putByte(SAME_FRAME_EXTENDED).putShort(delta);
                }
                break;
            case Opcodes.F_SAME1:
                if (delta < 64) {
                    stackMap.putByte(SAME_LOCALS_1_STACK_ITEM_FRAME + delta);
                } else {
                    stackMap.putByte(SAME_LOCALS_1_STACK_ITEM_FRAME_EXTENDED)
                            .putShort(delta);
                }
                writeFrameType(stack[0]);
                break;
            }

            previousFrameOffset = code.length;
            ++frameCount;
        }

        maxStack = Math.max(maxStack, nStack);
        maxLocals = Math.max(maxLocals, currentLocals);
    }

    @Override
    public void visitInsn(final int opcode) {
        // adds the instruction to the bytecode of the method
        code.putByte(opcode);
        // update currentBlock
        // Label currentBlock = this.currentBlock;
        if (currentBlock != null) {
            if (compute == FRAMES) {
                currentBlock.frame.execute(opcode, 0, null, null);
            } else {
                // updates current and max stack sizes
                int size = stackSize + Frame.SIZE[opcode];
                if (size > maxStackSize) {
                    maxStackSize = size;
                }
                stackSize = size;
            }
            // if opcode == ATHROW or xRETURN, ends current block (no successor)
            if ((opcode >= Opcodes.IRETURN && opcode <= Opcodes.RETURN)
                    || opcode == Opcodes.ATHROW) {
                noSuccessor();
            }
        }
    }

    @Override
    public void visitIntInsn(final int opcode, final int operand) {
        // Label currentBlock = this.currentBlock;
        if (currentBlock != null) {
            if (compute == FRAMES) {
                currentBlock.frame.execute(opcode, operand, null, null);
            } else if (opcode != Opcodes.NEWARRAY) {
                // updates current and max stack sizes only for NEWARRAY
                // (stack size variation = 0 for BIPUSH or SIPUSH)
                int size = stackSize + 1;
                if (size > maxStackSize) {
                    maxStackSize = size;
                }
                stackSize = size;
            }
        }
        // adds the instruction to the bytecode of the method
        if (opcode == Opcodes.SIPUSH) {
            code.put12(opcode, operand);
        } else { // BIPUSH or NEWARRAY
            code.put11(opcode, operand);
        }
    }

    @Override
    public void visitVarInsn(final int opcode, final int var) {
        // Label currentBlock = this.currentBlock;
        if (currentBlock != null) {
            if (compute == FRAMES) {
                currentBlock.frame.execute(opcode, var, null, null);
            } else {
                // updates current and max stack sizes
                if (opcode == Opcodes.RET) {
                    // no stack change, but end of current block (no successor)
                    currentBlock.status |= Label.RET;
                    // save 'stackSize' here for future use
                    // (see {@link #findSubroutineSuccessors})
                    currentBlock.inputStackTop = stackSize;
                    noSuccessor();
                } else { // xLOAD or xSTORE
                    int size = stackSize + Frame.SIZE[opcode];
                    if (size > maxStackSize) {
                        maxStackSize = size;
                    }
                    stackSize = size;
                }
            }
        }
        if (compute != NOTHING) {
            // updates max locals
            int n;
            if (opcode == Opcodes.LLOAD || opcode == Opcodes.DLOAD
                    || opcode == Opcodes.LSTORE || opcode == Opcodes.DSTORE) {
                n = var + 2;
            } else {
                n = var + 1;
            }
            if (n > maxLocals) {
                maxLocals = n;
            }
        }
        // adds the instruction to the bytecode of the method
        if (var < 4 && opcode != Opcodes.RET) {
            int opt;
            if (opcode < Opcodes.ISTORE) {
                /* ILOAD_0 */
                opt = 26 + ((opcode - Opcodes.ILOAD) << 2) + var;
            } else {
                /* ISTORE_0 */
                opt = 59 + ((opcode - Opcodes.ISTORE) << 2) + var;
            }
            code.putByte(opt);
        } else if (var >= 256) {
            code.putByte(196 /* WIDE */).put12(opcode, var);
        } else {
            code.put11(opcode, var);
        }
        if (opcode >= Opcodes.ISTORE && compute == FRAMES && handlerCount > 0) {
            visitLabel(new Label());
        }
    }

    @Override
    public void visitTypeInsn(final int opcode, final String type) {
        Item i = cw.newClassItem(type);
        // Label currentBlock = this.currentBlock;
        if (currentBlock != null) {
            if (compute == FRAMES) {
                currentBlock.frame.execute(opcode, code.length, cw, i);
            } else if (opcode == Opcodes.NEW) {
                // updates current and max stack sizes only if opcode == NEW
                // (no stack change for ANEWARRAY, CHECKCAST, INSTANCEOF)
                int size = stackSize + 1;
                if (size > maxStackSize) {
                    maxStackSize = size;
                }
                stackSize = size;
            }
        }
        // adds the instruction to the bytecode of the method
        code.put12(opcode, i.index);
    }

    @Override
    public void visitFieldInsn(final int opcode, final String owner,
            final String name, final String desc) {
        Item i = cw.newFieldItem(owner, name, desc);
        // Label currentBlock = this.currentBlock;
        if (currentBlock != null) {
            if (compute == FRAMES) {
                currentBlock.frame.execute(opcode, 0, cw, i);
            } else {
                int size;
                // computes the stack size variation
                char c = desc.charAt(0);
                switch (opcode) {
                case Opcodes.GETSTATIC:
                    size = stackSize + (c == 'D' || c == 'J' ? 2 : 1);
                    break;
                case Opcodes.PUTSTATIC:
                    size = stackSize + (c == 'D' || c == 'J' ? -2 : -1);
                    break;
                case Opcodes.GETFIELD:
                    size = stackSize + (c == 'D' || c == 'J' ? 1 : 0);
                    break;
                // case Constants.PUTFIELD:
                default:
                    size = stackSize + (c == 'D' || c == 'J' ? -3 : -2);
                    break;
                }
                // updates current and max stack sizes
                if (size > maxStackSize) {
                    maxStackSize = size;
                }
                stackSize = size;
            }
        }
        // adds the instruction to the bytecode of the method
        code.put12(opcode, i.index);
    }

    @Override
    public void visitMethodInsn(final int opcode, final String owner,
            final String name, final String desc) {
        boolean itf = opcode == Opcodes.INVOKEINTERFACE;
        Item i = cw.newMethodItem(owner, name, desc, itf);
        int argSize = i.intVal;
        // Label currentBlock = this.currentBlock;
        if (currentBlock != null) {
            if (compute == FRAMES) {
                currentBlock.frame.execute(opcode, 0, cw, i);
            } else {
                /*
                 * computes the stack size variation. In order not to recompute
                 * several times this variation for the same Item, we use the
                 * intVal field of this item to store this variation, once it
                 * has been computed. More precisely this intVal field stores
                 * the sizes of the arguments and of the return value
                 * corresponding to desc.
                 */
                if (argSize == 0) {
                    // the above sizes have not been computed yet,
                    // so we compute them...
                    argSize = Type.getArgumentsAndReturnSizes(desc);
                    // ... and we save them in order
                    // not to recompute them in the future
                    i.intVal = argSize;
                }
                int size;
                if (opcode == Opcodes.INVOKESTATIC) {
                    size = stackSize - (argSize >> 2) + (argSize & 0x03) + 1;
                } else {
                    size = stackSize - (argSize >> 2) + (argSize & 0x03);
                }
                // updates current and max stack sizes
                if (size > maxStackSize) {
                    maxStackSize = size;
                }
                stackSize = size;
            }
        }
        // adds the instruction to the bytecode of the method
        if (itf) {
            if (argSize == 0) {
                argSize = Type.getArgumentsAndReturnSizes(desc);
                i.intVal = argSize;
            }
            code.put12(Opcodes.INVOKEINTERFACE, i.index).put11(argSize >> 2, 0);
        } else {
            code.put12(opcode, i.index);
        }
    }

    @Override
    public void visitInvokeDynamicInsn(final String name, final String desc,
            final Handle bsm, final Object... bsmArgs) {
        Item i = cw.newInvokeDynamicItem(name, desc, bsm, bsmArgs);
        int argSize = i.intVal;
        // Label currentBlock = this.currentBlock;
        if (currentBlock != null) {
            if (compute == FRAMES) {
                currentBlock.frame.execute(Opcodes.INVOKEDYNAMIC, 0, cw, i);
            } else {
                /*
                 * computes the stack size variation. In order not to recompute
                 * several times this variation for the same Item, we use the
                 * intVal field of this item to store this variation, once it
                 * has been computed. More precisely this intVal field stores
                 * the sizes of the arguments and of the return value
                 * corresponding to desc.
                 */
                if (argSize == 0) {
                    // the above sizes have not been computed yet,
                    // so we compute them...
                    argSize = Type.getArgumentsAndReturnSizes(desc);
                    // ... and we save them in order
                    // not to recompute them in the future
                    i.intVal = argSize;
                }
                int size = stackSize - (argSize >> 2) + (argSize & 0x03) + 1;

                // updates current and max stack sizes
                if (size > maxStackSize) {
                    maxStackSize = size;
                }
                stackSize = size;
            }
        }
        // adds the instruction to the bytecode of the method
        code.put12(Opcodes.INVOKEDYNAMIC, i.index);
        code.putShort(0);
    }

    @Override
    public void visitJumpInsn(final int opcode, final Label label) {
        Label nextInsn = null;
        // Label currentBlock = this.currentBlock;
        if (currentBlock != null) {
            if (compute == FRAMES) {
                currentBlock.frame.execute(opcode, 0, null, null);
                // 'label' is the target of a jump instruction
                label.getFirst().status |= Label.TARGET;
                // adds 'label' as a successor of this basic block
                addSuccessor(Edge.NORMAL, label);
                if (opcode != Opcodes.GOTO) {
                    // creates a Label for the next basic block
                    nextInsn = new Label();
                }
            } else {
                if (opcode == Opcodes.JSR) {
                    if ((label.status & Label.SUBROUTINE) == 0) {
                        label.status |= Label.SUBROUTINE;
                        ++subroutines;
                    }
                    currentBlock.status |= Label.JSR;
                    addSuccessor(stackSize + 1, label);
                    // creates a Label for the next basic block
                    nextInsn = new Label();
                    /*
                     * note that, by construction in this method, a JSR block
                     * has at least two successors in the control flow graph:
                     * the first one leads the next instruction after the JSR,
                     * while the second one leads to the JSR target.
                     */
                } else {
                    // updates current stack size (max stack size unchanged
                    // because stack size variation always negative in this
                    // case)
                    stackSize += Frame.SIZE[opcode];
                    addSuccessor(stackSize, label);
                }
            }
        }
        // adds the instruction to the bytecode of the method
        if ((label.status & Label.RESOLVED) != 0
                && label.position - code.length < Short.MIN_VALUE) {
            /*
             * case of a backward jump with an offset < -32768. In this case we
             * automatically replace GOTO with GOTO_W, JSR with JSR_W and IFxxx
             * <l> with IFNOTxxx <l'> GOTO_W <l>, where IFNOTxxx is the
             * "opposite" opcode of IFxxx (i.e., IFNE for IFEQ) and where <l'>
             * designates the instruction just after the GOTO_W.
             */
            if (opcode == Opcodes.GOTO) {
                code.putByte(200); // GOTO_W
            } else if (opcode == Opcodes.JSR) {
                code.putByte(201); // JSR_W
            } else {
                // if the IF instruction is transformed into IFNOT GOTO_W the
                // next instruction becomes the target of the IFNOT instruction
                if (nextInsn != null) {
                    nextInsn.status |= Label.TARGET;
                }
                code.putByte(opcode <= 166 ? ((opcode + 1) ^ 1) - 1
                        : opcode ^ 1);
                code.putShort(8); // jump offset
                code.putByte(200); // GOTO_W
            }
            label.put(this, code, code.length - 1, true);
        } else {
            /*
             * case of a backward jump with an offset >= -32768, or of a forward
             * jump with, of course, an unknown offset. In these cases we store
             * the offset in 2 bytes (which will be increased in
             * resizeInstructions, if needed).
             */
            code.putByte(opcode);
            label.put(this, code, code.length - 1, false);
        }
        if (currentBlock != null) {
            if (nextInsn != null) {
                // if the jump instruction is not a GOTO, the next instruction
                // is also a successor of this instruction. Calling visitLabel
                // adds the label of this next instruction as a successor of the
                // current block, and starts a new basic block
                visitLabel(nextInsn);
            }
            if (opcode == Opcodes.GOTO) {
                noSuccessor();
            }
        }
    }

    @Override
    public void visitLabel(final Label label) {
        // resolves previous forward references to label, if any
        resize |= label.resolve(this, code.length, code.data);
        // updates currentBlock
        if ((label.status & Label.DEBUG) != 0) {
            return;
        }
        if (compute == FRAMES) {
            if (currentBlock != null) {
                if (label.position == currentBlock.position) {
                    // successive labels, do not start a new basic block
                    currentBlock.status |= (label.status & Label.TARGET);
                    label.frame = currentBlock.frame;
                    return;
                }
                // ends current block (with one new successor)
                addSuccessor(Edge.NORMAL, label);
            }
            // begins a new current block
            currentBlock = label;
            if (label.frame == null) {
                label.frame = new Frame();
                label.frame.owner = label;
            }
            // updates the basic block list
            if (previousBlock != null) {
                if (label.position == previousBlock.position) {
                    previousBlock.status |= (label.status & Label.TARGET);
                    label.frame = previousBlock.frame;
                    currentBlock = previousBlock;
                    return;
                }
                previousBlock.successor = label;
            }
            previousBlock = label;
        } else if (compute == MAXS) {
            if (currentBlock != null) {
                // ends current block (with one new successor)
                currentBlock.outputStackMax = maxStackSize;
                addSuccessor(stackSize, label);
            }
            // begins a new current block
            currentBlock = label;
            // resets the relative current and max stack sizes
            stackSize = 0;
            maxStackSize = 0;
            // updates the basic block list
            if (previousBlock != null) {
                previousBlock.successor = label;
            }
            previousBlock = label;
        }
    }

    @Override
    public void visitLdcInsn(final Object cst) {
        Item i = cw.newConstItem(cst);
        // Label currentBlock = this.currentBlock;
        if (currentBlock != null) {
            if (compute == FRAMES) {
                currentBlock.frame.execute(Opcodes.LDC, 0, cw, i);
            } else {
                int size;
                // computes the stack size variation
                if (i.type == ClassWriter.LONG || i.type == ClassWriter.DOUBLE) {
                    size = stackSize + 2;
                } else {
                    size = stackSize + 1;
                }
                // updates current and max stack sizes
                if (size > maxStackSize) {
                    maxStackSize = size;
                }
                stackSize = size;
            }
        }
        // adds the instruction to the bytecode of the method
        int index = i.index;
        if (i.type == ClassWriter.LONG || i.type == ClassWriter.DOUBLE) {
            code.put12(20 /* LDC2_W */, index);
        } else if (index >= 256) {
            code.put12(19 /* LDC_W */, index);
        } else {
            code.put11(Opcodes.LDC, index);
        }
    }

    @Override
    public void visitIincInsn(final int var, final int increment) {
        if (currentBlock != null) {
            if (compute == FRAMES) {
                currentBlock.frame.execute(Opcodes.IINC, var, null, null);
            }
        }
        if (compute != NOTHING) {
            // updates max locals
            int n = var + 1;
            if (n > maxLocals) {
                maxLocals = n;
            }
        }
        // adds the instruction to the bytecode of the method
        if ((var > 255) || (increment > 127) || (increment < -128)) {
            code.putByte(196 /* WIDE */).put12(Opcodes.IINC, var)
                    .putShort(increment);
        } else {
            code.putByte(Opcodes.IINC).put11(var, increment);
        }
    }

    @Override
    public void visitTableSwitchInsn(final int min, final int max,
            final Label dflt, final Label... labels) {
        // adds the instruction to the bytecode of the method
        int source = code.length;
        code.putByte(Opcodes.TABLESWITCH);
        code.putByteArray(null, 0, (4 - code.length % 4) % 4);
        dflt.put(this, code, source, true);
        code.putInt(min).putInt(max);
        for (int i = 0; i < labels.length; ++i) {
            labels[i].put(this, code, source, true);
        }
        // updates currentBlock
        visitSwitchInsn(dflt, labels);
    }

    @Override
    public void visitLookupSwitchInsn(final Label dflt, final int[] keys,
            final Label[] labels) {
        // adds the instruction to the bytecode of the method
        int source = code.length;
        code.putByte(Opcodes.LOOKUPSWITCH);
        code.putByteArray(null, 0, (4 - code.length % 4) % 4);
        dflt.put(this, code, source, true);
        code.putInt(labels.length);
        for (int i = 0; i < labels.length; ++i) {
            code.putInt(keys[i]);
            labels[i].put(this, code, source, true);
        }
        // updates currentBlock
        visitSwitchInsn(dflt, labels);
    }

    private void visitSwitchInsn(final Label dflt, final Label[] labels) {
        // Label currentBlock = this.currentBlock;
        if (currentBlock != null) {
            if (compute == FRAMES) {
                currentBlock.frame.execute(Opcodes.LOOKUPSWITCH, 0, null, null);
                // adds current block successors
                addSuccessor(Edge.NORMAL, dflt);
                dflt.getFirst().status |= Label.TARGET;
                for (int i = 0; i < labels.length; ++i) {
                    addSuccessor(Edge.NORMAL, labels[i]);
                    labels[i].getFirst().status |= Label.TARGET;
                }
            } else {
                // updates current stack size (max stack size unchanged)
                --stackSize;
                // adds current block successors
                addSuccessor(stackSize, dflt);
                for (int i = 0; i < labels.length; ++i) {
                    addSuccessor(stackSize, labels[i]);
                }
            }
            // ends current block
            noSuccessor();
        }
    }

    @Override
    public void visitMultiANewArrayInsn(final String desc, final int dims) {
        Item i = cw.newClassItem(desc);
        // Label currentBlock = this.currentBlock;
        if (currentBlock != null) {
            if (compute == FRAMES) {
                currentBlock.frame.execute(Opcodes.MULTIANEWARRAY, dims, cw, i);
            } else {
                // updates current stack size (max stack size unchanged because
                // stack size variation always negative or null)
                stackSize += 1 - dims;
            }
        }
        // adds the instruction to the bytecode of the method
        code.put12(Opcodes.MULTIANEWARRAY, i.index).putByte(dims);
    }

    @Override
    public void visitTryCatchBlock(final Label start, final Label end,
            final Label handler, final String type) {
        ++handlerCount;
        Handler h = new Handler();
        h.start = start;
        h.end = end;
        h.handler = handler;
        h.desc = type;
        h.type = type != null ? cw.newClass(type) : 0;
        if (lastHandler == null) {
            firstHandler = h;
        } else {
            lastHandler.next = h;
        }
        lastHandler = h;
    }

    @Override
    public void visitLocalVariable(final String name, final String desc,
            final String signature, final Label start, final Label end,
            final int index) {
        if (signature != null) {
            if (localVarType == null) {
                localVarType = new ByteVector();
            }
            ++localVarTypeCount;
            localVarType.putShort(start.position)
                    .putShort(end.position - start.position)
                    .putShort(cw.newUTF8(name)).putShort(cw.newUTF8(signature))
                    .putShort(index);
        }
        if (localVar == null) {
            localVar = new ByteVector();
        }
        ++localVarCount;
        localVar.putShort(start.position)
                .putShort(end.position - start.position)
                .putShort(cw.newUTF8(name)).putShort(cw.newUTF8(desc))
                .putShort(index);
        if (compute != NOTHING) {
            // updates max locals
            char c = desc.charAt(0);
            int n = index + (c == 'J' || c == 'D' ? 2 : 1);
            if (n > maxLocals) {
                maxLocals = n;
            }
        }
    }

    @Override
    public void visitLineNumber(final int line, final Label start) {
        if (lineNumber == null) {
            lineNumber = new ByteVector();
        }
        ++lineNumberCount;
        lineNumber.putShort(start.position);
        lineNumber.putShort(line);
    }

    @Override
    public void visitMaxs(final int maxStack, final int maxLocals) {
        if (ClassReader.FRAMES && compute == FRAMES) {
            // completes the control flow graph with exception handler blocks
            Handler handler = firstHandler;
            while (handler != null) {
                Label l = handler.start.getFirst();
                Label h = handler.handler.getFirst();
                Label e = handler.end.getFirst();
                // computes the kind of the edges to 'h'
                String t = handler.desc == null ? "java/lang/Throwable"
                        : handler.desc;
                int kind = Frame.OBJECT | cw.addType(t);
                // h is an exception handler
                h.status |= Label.TARGET;
                // adds 'h' as a successor of labels between 'start' and 'end'
                while (l != e) {
                    // creates an edge to 'h'
                    Edge b = new Edge();
                    b.info = kind;
                    b.successor = h;
                    // adds it to the successors of 'l'
                    b.next = l.successors;
                    l.successors = b;
                    // goes to the next label
                    l = l.successor;
                }
                handler = handler.next;
            }

            // creates and visits the first (implicit) frame
            Frame f = labels.frame;
            Type[] args = Type.getArgumentTypes(descriptor);
            f.initInputFrame(cw, access, args, this.maxLocals);
            visitFrame(f);

            /*
             * fix point algorithm: mark the first basic block as 'changed'
             * (i.e. put it in the 'changed' list) and, while there are changed
             * basic blocks, choose one, mark it as unchanged, and update its
             * successors (which can be changed in the process).
             */
            int max = 0;
            Label changed = labels;
            while (changed != null) {
                // removes a basic block from the list of changed basic blocks
                Label l = changed;
                changed = changed.next;
                l.next = null;
                f = l.frame;
                // a reachable jump target must be stored in the stack map
                if ((l.status & Label.TARGET) != 0) {
                    l.status |= Label.STORE;
                }
                // all visited labels are reachable, by definition
                l.status |= Label.REACHABLE;
                // updates the (absolute) maximum stack size
                int blockMax = f.inputStack.length + l.outputStackMax;
                if (blockMax > max) {
                    max = blockMax;
                }
                // updates the successors of the current basic block
                Edge e = l.successors;
                while (e != null) {
                    Label n = e.successor.getFirst();
                    boolean change = f.merge(cw, n.frame, e.info);
                    if (change && n.next == null) {
                        // if n has changed and is not already in the 'changed'
                        // list, adds it to this list
                        n.next = changed;
                        changed = n;
                    }
                    e = e.next;
                }
            }

            // visits all the frames that must be stored in the stack map
            Label l = labels;
            while (l != null) {
                f = l.frame;
                if ((l.status & Label.STORE) != 0) {
                    visitFrame(f);
                }
                if ((l.status & Label.REACHABLE) == 0) {
                    // finds start and end of dead basic block
                    Label k = l.successor;
                    int start = l.position;
                    int end = (k == null ? code.length : k.position) - 1;
                    // if non empty basic block
                    if (end >= start) {
                        max = Math.max(max, 1);
                        // replaces instructions with NOP ... NOP ATHROW
                        for (int i = start; i < end; ++i) {
                            code.data[i] = Opcodes.NOP;
                        }
                        code.data[end] = (byte) Opcodes.ATHROW;
                        // emits a frame for this unreachable block
                        int frameIndex = startFrame(start, 0, 1);
                        frame[frameIndex] = Frame.OBJECT
                                | cw.addType("java/lang/Throwable");
                        endFrame();
                        // removes the start-end range from the exception
                        // handlers
                        firstHandler = Handler.remove(firstHandler, l, k);
                    }
                }
                l = l.successor;
            }

            handler = firstHandler;
            handlerCount = 0;
            while (handler != null) {
                handlerCount += 1;
                handler = handler.next;
            }

            this.maxStack = max;
        } else if (compute == MAXS) {
            // completes the control flow graph with exception handler blocks
            Handler handler = firstHandler;
            while (handler != null) {
                Label l = handler.start;
                Label h = handler.handler;
                Label e = handler.end;
                // adds 'h' as a successor of labels between 'start' and 'end'
                while (l != e) {
                    // creates an edge to 'h'
                    Edge b = new Edge();
                    b.info = Edge.EXCEPTION;
                    b.successor = h;
                    // adds it to the successors of 'l'
                    if ((l.status & Label.JSR) == 0) {
                        b.next = l.successors;
                        l.successors = b;
                    } else {
                        // if l is a JSR block, adds b after the first two edges
                        // to preserve the hypothesis about JSR block successors
                        // order (see {@link #visitJumpInsn})
                        b.next = l.successors.next.next;
                        l.successors.next.next = b;
                    }
                    // goes to the next label
                    l = l.successor;
                }
                handler = handler.next;
            }

            if (subroutines > 0) {
                // completes the control flow graph with the RET successors
                /*
                 * first step: finds the subroutines. This step determines, for
                 * each basic block, to which subroutine(s) it belongs.
                 */
                // finds the basic blocks that belong to the "main" subroutine
                int id = 0;
                labels.visitSubroutine(null, 1, subroutines);
                // finds the basic blocks that belong to the real subroutines
                Label l = labels;
                while (l != null) {
                    if ((l.status & Label.JSR) != 0) {
                        // the subroutine is defined by l's TARGET, not by l
                        Label subroutine = l.successors.next.successor;
                        // if this subroutine has not been visited yet...
                        if ((subroutine.status & Label.VISITED) == 0) {
                            // ...assigns it a new id and finds its basic blocks
                            id += 1;
                            subroutine.visitSubroutine(null, (id / 32L) << 32
                                    | (1L << (id % 32)), subroutines);
                        }
                    }
                    l = l.successor;
                }
                // second step: finds the successors of RET blocks
                l = labels;
                while (l != null) {
                    if ((l.status & Label.JSR) != 0) {
                        Label L = labels;
                        while (L != null) {
                            L.status &= ~Label.VISITED2;
                            L = L.successor;
                        }
                        // the subroutine is defined by l's TARGET, not by l
                        Label subroutine = l.successors.next.successor;
                        subroutine.visitSubroutine(l, 0, subroutines);
                    }
                    l = l.successor;
                }
            }

            /*
             * control flow analysis algorithm: while the block stack is not
             * empty, pop a block from this stack, update the max stack size,
             * compute the true (non relative) begin stack size of the
             * successors of this block, and push these successors onto the
             * stack (unless they have already been pushed onto the stack).
             * Note: by hypothesis, the {@link Label#inputStackTop} of the
             * blocks in the block stack are the true (non relative) beginning
             * stack sizes of these blocks.
             */
            int max = 0;
            Label stack = labels;
            while (stack != null) {
                // pops a block from the stack
                Label l = stack;
                stack = stack.next;
                // computes the true (non relative) max stack size of this block
                int start = l.inputStackTop;
                int blockMax = start + l.outputStackMax;
                // updates the global max stack size
                if (blockMax > max) {
                    max = blockMax;
                }
                // analyzes the successors of the block
                Edge b = l.successors;
                if ((l.status & Label.JSR) != 0) {
                    // ignores the first edge of JSR blocks (virtual successor)
                    b = b.next;
                }
                while (b != null) {
                    l = b.successor;
                    // if this successor has not already been pushed...
                    if ((l.status & Label.PUSHED) == 0) {
                        // computes its true beginning stack size...
                        l.inputStackTop = b.info == Edge.EXCEPTION ? 1 : start
                                + b.info;
                        // ...and pushes it onto the stack
                        l.status |= Label.PUSHED;
                        l.next = stack;
                        stack = l;
                    }
                    b = b.next;
                }
            }
            this.maxStack = Math.max(maxStack, max);
        } else {
            this.maxStack = maxStack;
            this.maxLocals = maxLocals;
        }
    }

    @Override
    public void visitEnd() {
    }

    // ------------------------------------------------------------------------
    // Utility methods: control flow analysis algorithm
    // ------------------------------------------------------------------------

    
Adds a successor to the currentBlock block. 
Params:
info – 
           information about the control flow edge to be added.
successor – 
           the successor block to be added to the current block./**
     * Adds a successor to the {@link #currentBlock currentBlock} block.
     * 
     * @param info
     *            information about the control flow edge to be added.
     * @param successor
     *            the successor block to be added to the current block.
     */
    private void addSuccessor(final int info, final Label successor) {
        // creates and initializes an Edge object...
        Edge b = new Edge();
        b.info = info;
        b.successor = successor;
        // ...and adds it to the successor list of the currentBlock block
        b.next = currentBlock.successors;
        currentBlock.successors = b;
    }

    
Ends the current basic block. This method must be used in the case where
the current basic block does not have any successor.
/**
     * Ends the current basic block. This method must be used in the case where
     * the current basic block does not have any successor.
     */
    private void noSuccessor() {
        if (compute == FRAMES) {
            Label l = new Label();
            l.frame = new Frame();
            l.frame.owner = l;
            l.resolve(this, code.length, code.data);
            previousBlock.successor = l;
            previousBlock = l;
        } else {
            currentBlock.outputStackMax = maxStackSize;
        }
        currentBlock = null;
    }

    // ------------------------------------------------------------------------
    // Utility methods: stack map frames
    // ------------------------------------------------------------------------

    
Visits a frame that has been computed from scratch.
Params:
f – 
           the frame that must be visited./**
     * Visits a frame that has been computed from scratch.
     * 
     * @param f
     *            the frame that must be visited.
     */
    private void visitFrame(final Frame f) {
        int i, t;
        int nTop = 0;
        int nLocal = 0;
        int nStack = 0;
        int[] locals = f.inputLocals;
        int[] stacks = f.inputStack;
        // computes the number of locals (ignores TOP types that are just after
        // a LONG or a DOUBLE, and all trailing TOP types)
        for (i = 0; i < locals.length; ++i) {
            t = locals[i];
            if (t == Frame.TOP) {
                ++nTop;
            } else {
                nLocal += nTop + 1;
                nTop = 0;
            }
            if (t == Frame.LONG || t == Frame.DOUBLE) {
                ++i;
            }
        }
        // computes the stack size (ignores TOP types that are just after
        // a LONG or a DOUBLE)
        for (i = 0; i < stacks.length; ++i) {
            t = stacks[i];
            ++nStack;
            if (t == Frame.LONG || t == Frame.DOUBLE) {
                ++i;
            }
        }
        // visits the frame and its content
        int frameIndex = startFrame(f.owner.position, nLocal, nStack);
        for (i = 0; nLocal > 0; ++i, --nLocal) {
            t = locals[i];
            frame[frameIndex++] = t;
            if (t == Frame.LONG || t == Frame.DOUBLE) {
                ++i;
            }
        }
        for (i = 0; i < stacks.length; ++i) {
            t = stacks[i];
            frame[frameIndex++] = t;
            if (t == Frame.LONG || t == Frame.DOUBLE) {
                ++i;
            }
        }
        endFrame();
    }

    
Visit the implicit first frame of this method.
/**
     * Visit the implicit first frame of this method.
     */
    private void visitImplicitFirstFrame() {
        // There can be at most descriptor.length() + 1 locals
        int frameIndex = startFrame(0, descriptor.length() + 1, 0);
        if ((access & Opcodes.ACC_STATIC) == 0) {
            if ((access & ACC_CONSTRUCTOR) == 0) {
                frame[frameIndex++] = Frame.OBJECT | cw.addType(cw.thisName);
            } else {
                frame[frameIndex++] = 6; // Opcodes.UNINITIALIZED_THIS;
            }
        }
        int i = 1;
        loop: while (true) {
            int j = i;
            switch (descriptor.charAt(i++)) {
            case 'Z':
            case 'C':
            case 'B':
            case 'S':
            case 'I':
                frame[frameIndex++] = 1; // Opcodes.INTEGER;
                break;
            case 'F':
                frame[frameIndex++] = 2; // Opcodes.FLOAT;
                break;
            case 'J':
                frame[frameIndex++] = 4; // Opcodes.LONG;
                break;
            case 'D':
                frame[frameIndex++] = 3; // Opcodes.DOUBLE;
                break;
            case '[':
                while (descriptor.charAt(i) == '[') {
                    ++i;
                }
                if (descriptor.charAt(i) == 'L') {
                    ++i;
                    while (descriptor.charAt(i) != ';') {
                        ++i;
                    }
                }
                frame[frameIndex++] = Frame.OBJECT
                        | cw.addType(descriptor.substring(j, ++i));
                break;
            case 'L':
                while (descriptor.charAt(i) != ';') {
                    ++i;
                }
                frame[frameIndex++] = Frame.OBJECT
                        | cw.addType(descriptor.substring(j + 1, i++));
                break;
            default:
                break loop;
            }
        }
        frame[1] = frameIndex - 3;
        endFrame();
    }

    
Starts the visit of a stack map frame.
Params:
offset – 
           the offset of the instruction to which the frame corresponds.
nLocal – 
           the number of local variables in the frame.
nStack – 
           the number of stack elements in the frame.
Returns:
the index of the next element to be written in this frame./**
     * Starts the visit of a stack map frame.
     * 
     * @param offset
     *            the offset of the instruction to which the frame corresponds.
     * @param nLocal
     *            the number of local variables in the frame.
     * @param nStack
     *            the number of stack elements in the frame.
     * @return the index of the next element to be written in this frame.
     */
    private int startFrame(final int offset, final int nLocal, final int nStack) {
        int n = 3 + nLocal + nStack;
        if (frame == null || frame.length < n) {
            frame = new int[n];
        }
        frame[0] = offset;
        frame[1] = nLocal;
        frame[2] = nStack;
        return 3;
    }

    
Checks if the visit of the current frame frame is finished, and if yes, write it in the StackMapTable attribute. /**
     * Checks if the visit of the current frame {@link #frame} is finished, and
     * if yes, write it in the StackMapTable attribute.
     */
    private void endFrame() {
        if (previousFrame != null) { // do not write the first frame
            if (stackMap == null) {
                stackMap = new ByteVector();
            }
            writeFrame();
            ++frameCount;
        }
        previousFrame = frame;
        frame = null;
    }

    
Compress and writes the current frame frame in the StackMapTable attribute. /**
     * Compress and writes the current frame {@link #frame} in the StackMapTable
     * attribute.
     */
    private void writeFrame() {
        int clocalsSize = frame[1];
        int cstackSize = frame[2];
        if ((cw.version & 0xFFFF) < Opcodes.V1_6) {
            stackMap.putShort(frame[0]).putShort(clocalsSize);
            writeFrameTypes(3, 3 + clocalsSize);
            stackMap.putShort(cstackSize);
            writeFrameTypes(3 + clocalsSize, 3 + clocalsSize + cstackSize);
            return;
        }
        int localsSize = previousFrame[1];
        int type = FULL_FRAME;
        int k = 0;
        int delta;
        if (frameCount == 0) {
            delta = frame[0];
        } else {
            delta = frame[0] - previousFrame[0] - 1;
        }
        if (cstackSize == 0) {
            k = clocalsSize - localsSize;
            switch (k) {
            case -3:
            case -2:
            case -1:
                type = CHOP_FRAME;
                localsSize = clocalsSize;
                break;
            case 0:
                type = delta < 64 ? SAME_FRAME : SAME_FRAME_EXTENDED;
                break;
            case 1:
            case 2:
            case 3:
                type = APPEND_FRAME;
                break;
            }
        } else if (clocalsSize == localsSize && cstackSize == 1) {
            type = delta < 63 ? SAME_LOCALS_1_STACK_ITEM_FRAME
                    : SAME_LOCALS_1_STACK_ITEM_FRAME_EXTENDED;
        }
        if (type != FULL_FRAME) {
            // verify if locals are the same
            int l = 3;
            for (int j = 0; j < localsSize; j++) {
                if (frame[l] != previousFrame[l]) {
                    type = FULL_FRAME;
                    break;
                }
                l++;
            }
        }
        switch (type) {
        case SAME_FRAME:
            stackMap.putByte(delta);
            break;
        case SAME_LOCALS_1_STACK_ITEM_FRAME:
            stackMap.putByte(SAME_LOCALS_1_STACK_ITEM_FRAME + delta);
            writeFrameTypes(3 + clocalsSize, 4 + clocalsSize);
            break;
        case SAME_LOCALS_1_STACK_ITEM_FRAME_EXTENDED:
            stackMap.putByte(SAME_LOCALS_1_STACK_ITEM_FRAME_EXTENDED).putShort(
                    delta);
            writeFrameTypes(3 + clocalsSize, 4 + clocalsSize);
            break;
        case SAME_FRAME_EXTENDED:
            stackMap.putByte(SAME_FRAME_EXTENDED).putShort(delta);
            break;
        case CHOP_FRAME:
            stackMap.putByte(SAME_FRAME_EXTENDED + k).putShort(delta);
            break;
        case APPEND_FRAME:
            stackMap.putByte(SAME_FRAME_EXTENDED + k).putShort(delta);
            writeFrameTypes(3 + localsSize, 3 + clocalsSize);
            break;
        // case FULL_FRAME:
        default:
            stackMap.putByte(FULL_FRAME).putShort(delta).putShort(clocalsSize);
            writeFrameTypes(3, 3 + clocalsSize);
            stackMap.putShort(cstackSize);
            writeFrameTypes(3 + clocalsSize, 3 + clocalsSize + cstackSize);
        }
    }

    
Writes some types of the current frame frame into the StackMapTableAttribute. This method converts types from the format used in Label to the format used in StackMapTable attributes. In particular, it converts type table indexes to constant pool indexes. 
Params:
start –  index of the first type in frame to write.
end –  index of last type in frame to write (exclusive)./**
     * Writes some types of the current frame {@link #frame} into the
     * StackMapTableAttribute. This method converts types from the format used
     * in {@link Label} to the format used in StackMapTable attributes. In
     * particular, it converts type table indexes to constant pool indexes.
     * 
     * @param start
     *            index of the first type in {@link #frame} to write.
     * @param end
     *            index of last type in {@link #frame} to write (exclusive).
     */
    private void writeFrameTypes(final int start, final int end) {
        for (int i = start; i < end; ++i) {
            int t = frame[i];
            int d = t & Frame.DIM;
            if (d == 0) {
                int v = t & Frame.BASE_VALUE;
                switch (t & Frame.BASE_KIND) {
                case Frame.OBJECT:
                    stackMap.putByte(7).putShort(
                            cw.newClass(cw.typeTable[v].strVal1));
                    break;
                case Frame.UNINITIALIZED:
                    stackMap.putByte(8).putShort(cw.typeTable[v].intVal);
                    break;
                default:
                    stackMap.putByte(v);
                }
            } else {
                StringBuffer buf = new StringBuffer();
                d >>= 28;
                while (d-- > 0) {
                    buf.append('[');
                }
                if ((t & Frame.BASE_KIND) == Frame.OBJECT) {
                    buf.append('L');
                    buf.append(cw.typeTable[t & Frame.BASE_VALUE].strVal1);
                    buf.append(';');
                } else {
                    switch (t & 0xF) {
                    case 1:
                        buf.append('I');
                        break;
                    case 2:
                        buf.append('F');
                        break;
                    case 3:
                        buf.append('D');
                        break;
                    case 9:
                        buf.append('Z');
                        break;
                    case 10:
                        buf.append('B');
                        break;
                    case 11:
                        buf.append('C');
                        break;
                    case 12:
                        buf.append('S');
                        break;
                    default:
                        buf.append('J');
                    }
                }
                stackMap.putByte(7).putShort(cw.newClass(buf.toString()));
            }
        }
    }

    private void writeFrameType(final Object type) {
        if (type instanceof String) {
            stackMap.putByte(7).putShort(cw.newClass((String) type));
        } else if (type instanceof Integer) {
            stackMap.putByte(((Integer) type).intValue());
        } else {
            stackMap.putByte(8).putShort(((Label) type).position);
        }
    }

    // ------------------------------------------------------------------------
    // Utility methods: dump bytecode array
    // ------------------------------------------------------------------------

    
Returns the size of the bytecode of this method.
Returns:
the size of the bytecode of this method./**
     * Returns the size of the bytecode of this method.
     * 
     * @return the size of the bytecode of this method.
     */
    final int getSize() {
        if (classReaderOffset != 0) {
            return 6 + classReaderLength;
        }
        if (resize) {
            // replaces the temporary jump opcodes introduced by Label.resolve.
            if (ClassReader.RESIZE) {
                resizeInstructions();
            } else {
                throw new RuntimeException("Method code too large!");
            }
        }
        int size = 8;
        if (code.length > 0) {
            if (code.length > 65536) {
                throw new RuntimeException("Method code too large!");
            }
            cw.newUTF8("Code");
            size += 18 + code.length + 8 * handlerCount;
            if (localVar != null) {
                cw.newUTF8("LocalVariableTable");
                size += 8 + localVar.length;
            }
            if (localVarType != null) {
                cw.newUTF8("LocalVariableTypeTable");
                size += 8 + localVarType.length;
            }
            if (lineNumber != null) {
                cw.newUTF8("LineNumberTable");
                size += 8 + lineNumber.length;
            }
            if (stackMap != null) {
                boolean zip = (cw.version & 0xFFFF) >= Opcodes.V1_6;
                cw.newUTF8(zip ? "StackMapTable" : "StackMap");
                size += 8 + stackMap.length;
            }
            if (cattrs != null) {
                size += cattrs.getSize(cw, code.data, code.length, maxStack,
                        maxLocals);
            }
        }
        if (exceptionCount > 0) {
            cw.newUTF8("Exceptions");
            size += 8 + 2 * exceptionCount;
        }
        if ((access & Opcodes.ACC_SYNTHETIC) != 0) {
            if ((cw.version & 0xFFFF) < Opcodes.V1_5
                    || (access & ClassWriter.ACC_SYNTHETIC_ATTRIBUTE) != 0) {
                cw.newUTF8("Synthetic");
                size += 6;
            }
        }
        if ((access & Opcodes.ACC_DEPRECATED) != 0) {
            cw.newUTF8("Deprecated");
            size += 6;
        }
        if (ClassReader.SIGNATURES && signature != null) {
            cw.newUTF8("Signature");
            cw.newUTF8(signature);
            size += 8;
        }
        if (ClassReader.ANNOTATIONS && annd != null) {
            cw.newUTF8("AnnotationDefault");
            size += 6 + annd.length;
        }
        if (ClassReader.ANNOTATIONS && anns != null) {
            cw.newUTF8("RuntimeVisibleAnnotations");
            size += 8 + anns.getSize();
        }
        if (ClassReader.ANNOTATIONS && ianns != null) {
            cw.newUTF8("RuntimeInvisibleAnnotations");
            size += 8 + ianns.getSize();
        }
        if (ClassReader.ANNOTATIONS && panns != null) {
            cw.newUTF8("RuntimeVisibleParameterAnnotations");
            size += 7 + 2 * (panns.length - synthetics);
            for (int i = panns.length - 1; i >= synthetics; --i) {
                size += panns[i] == null ? 0 : panns[i].getSize();
            }
        }
        if (ClassReader.ANNOTATIONS && ipanns != null) {
            cw.newUTF8("RuntimeInvisibleParameterAnnotations");
            size += 7 + 2 * (ipanns.length - synthetics);
            for (int i = ipanns.length - 1; i >= synthetics; --i) {
                size += ipanns[i] == null ? 0 : ipanns[i].getSize();
            }
        }
        if (attrs != null) {
            size += attrs.getSize(cw, null, 0, -1, -1);
        }
        return size;
    }

    
Puts the bytecode of this method in the given byte vector.
Params:
out – 
           the byte vector into which the bytecode of this method must be
           copied./**
     * Puts the bytecode of this method in the given byte vector.
     * 
     * @param out
     *            the byte vector into which the bytecode of this method must be
     *            copied.
     */
    final void put(final ByteVector out) {
        final int FACTOR = ClassWriter.TO_ACC_SYNTHETIC;
        int mask = ACC_CONSTRUCTOR | Opcodes.ACC_DEPRECATED
                | ClassWriter.ACC_SYNTHETIC_ATTRIBUTE
                | ((access & ClassWriter.ACC_SYNTHETIC_ATTRIBUTE) / FACTOR);
        out.putShort(access & ~mask).putShort(name).putShort(desc);
        if (classReaderOffset != 0) {
            out.putByteArray(cw.cr.b, classReaderOffset, classReaderLength);
            return;
        }
        int attributeCount = 0;
        if (code.length > 0) {
            ++attributeCount;
        }
        if (exceptionCount > 0) {
            ++attributeCount;
        }
        if ((access & Opcodes.ACC_SYNTHETIC) != 0) {
            if ((cw.version & 0xFFFF) < Opcodes.V1_5
                    || (access & ClassWriter.ACC_SYNTHETIC_ATTRIBUTE) != 0) {
                ++attributeCount;
            }
        }
        if ((access & Opcodes.ACC_DEPRECATED) != 0) {
            ++attributeCount;
        }
        if (ClassReader.SIGNATURES && signature != null) {
            ++attributeCount;
        }
        if (ClassReader.ANNOTATIONS && annd != null) {
            ++attributeCount;
        }
        if (ClassReader.ANNOTATIONS && anns != null) {
            ++attributeCount;
        }
        if (ClassReader.ANNOTATIONS && ianns != null) {
            ++attributeCount;
        }
        if (ClassReader.ANNOTATIONS && panns != null) {
            ++attributeCount;
        }
        if (ClassReader.ANNOTATIONS && ipanns != null) {
            ++attributeCount;
        }
        if (attrs != null) {
            attributeCount += attrs.getCount();
        }
        out.putShort(attributeCount);
        if (code.length > 0) {
            int size = 12 + code.length + 8 * handlerCount;
            if (localVar != null) {
                size += 8 + localVar.length;
            }
            if (localVarType != null) {
                size += 8 + localVarType.length;
            }
            if (lineNumber != null) {
                size += 8 + lineNumber.length;
            }
            if (stackMap != null) {
                size += 8 + stackMap.length;
            }
            if (cattrs != null) {
                size += cattrs.getSize(cw, code.data, code.length, maxStack,
                        maxLocals);
            }
            out.putShort(cw.newUTF8("Code")).putInt(size);
            out.putShort(maxStack).putShort(maxLocals);
            out.putInt(code.length).putByteArray(code.data, 0, code.length);
            out.putShort(handlerCount);
            if (handlerCount > 0) {
                Handler h = firstHandler;
                while (h != null) {
                    out.putShort(h.start.position).putShort(h.end.position)
                            .putShort(h.handler.position).putShort(h.type);
                    h = h.next;
                }
            }
            attributeCount = 0;
            if (localVar != null) {
                ++attributeCount;
            }
            if (localVarType != null) {
                ++attributeCount;
            }
            if (lineNumber != null) {
                ++attributeCount;
            }
            if (stackMap != null) {
                ++attributeCount;
            }
            if (cattrs != null) {
                attributeCount += cattrs.getCount();
            }
            out.putShort(attributeCount);
            if (localVar != null) {
                out.putShort(cw.newUTF8("LocalVariableTable"));
                out.putInt(localVar.length + 2).putShort(localVarCount);
                out.putByteArray(localVar.data, 0, localVar.length);
            }
            if (localVarType != null) {
                out.putShort(cw.newUTF8("LocalVariableTypeTable"));
                out.putInt(localVarType.length + 2).putShort(localVarTypeCount);
                out.putByteArray(localVarType.data, 0, localVarType.length);
            }
            if (lineNumber != null) {
                out.putShort(cw.newUTF8("LineNumberTable"));
                out.putInt(lineNumber.length + 2).putShort(lineNumberCount);
                out.putByteArray(lineNumber.data, 0, lineNumber.length);
            }
            if (stackMap != null) {
                boolean zip = (cw.version & 0xFFFF) >= Opcodes.V1_6;
                out.putShort(cw.newUTF8(zip ? "StackMapTable" : "StackMap"));
                out.putInt(stackMap.length + 2).putShort(frameCount);
                out.putByteArray(stackMap.data, 0, stackMap.length);
            }
            if (cattrs != null) {
                cattrs.put(cw, code.data, code.length, maxLocals, maxStack, out);
            }
        }
        if (exceptionCount > 0) {
            out.putShort(cw.newUTF8("Exceptions")).putInt(
                    2 * exceptionCount + 2);
            out.putShort(exceptionCount);
            for (int i = 0; i < exceptionCount; ++i) {
                out.putShort(exceptions[i]);
            }
        }
        if ((access & Opcodes.ACC_SYNTHETIC) != 0) {
            if ((cw.version & 0xFFFF) < Opcodes.V1_5
                    || (access & ClassWriter.ACC_SYNTHETIC_ATTRIBUTE) != 0) {
                out.putShort(cw.newUTF8("Synthetic")).putInt(0);
            }
        }
        if ((access & Opcodes.ACC_DEPRECATED) != 0) {
            out.putShort(cw.newUTF8("Deprecated")).putInt(0);
        }
        if (ClassReader.SIGNATURES && signature != null) {
            out.putShort(cw.newUTF8("Signature")).putInt(2)
                    .putShort(cw.newUTF8(signature));
        }
        if (ClassReader.ANNOTATIONS && annd != null) {
            out.putShort(cw.newUTF8("AnnotationDefault"));
            out.putInt(annd.length);
            out.putByteArray(annd.data, 0, annd.length);
        }
        if (ClassReader.ANNOTATIONS && anns != null) {
            out.putShort(cw.newUTF8("RuntimeVisibleAnnotations"));
            anns.put(out);
        }
        if (ClassReader.ANNOTATIONS && ianns != null) {
            out.putShort(cw.newUTF8("RuntimeInvisibleAnnotations"));
            ianns.put(out);
        }
        if (ClassReader.ANNOTATIONS && panns != null) {
            out.putShort(cw.newUTF8("RuntimeVisibleParameterAnnotations"));
            AnnotationWriter.put(panns, synthetics, out);
        }
        if (ClassReader.ANNOTATIONS && ipanns != null) {
            out.putShort(cw.newUTF8("RuntimeInvisibleParameterAnnotations"));
            AnnotationWriter.put(ipanns, synthetics, out);
        }
        if (attrs != null) {
            attrs.put(cw, null, 0, -1, -1, out);
        }
    }

    // ------------------------------------------------------------------------
    // Utility methods: instruction resizing (used to handle GOTO_W and JSR_W)
    // ------------------------------------------------------------------------

    
Resizes and replaces the temporary instructions inserted by Label.resolve for wide forward jumps, while keeping jump offsets and instruction addresses consistent. This may require to resize other existing instructions, or even to introduce new instructions: for example, increasing the size of an instruction by 2 at the middle of a method can increases the offset of an IFEQ instruction from 32766 to 32768, in which case IFEQ 32766 must be replaced with IFNEQ 8 GOTO_W 32765. This, in turn, may require to increase the size of another jump instruction, and so on... All these operations are handled automatically by this method. 

This method must be called after all the method that is being built
has been visited. In particular, the Label objects used to construct the method are no longer valid after this method has been called. /**
     * Resizes and replaces the temporary instructions inserted by
     * {@link Label#resolve} for wide forward jumps, while keeping jump offsets
     * and instruction addresses consistent. This may require to resize other
     * existing instructions, or even to introduce new instructions: for
     * example, increasing the size of an instruction by 2 at the middle of a
     * method can increases the offset of an IFEQ instruction from 32766 to
     * 32768, in which case IFEQ 32766 must be replaced with IFNEQ 8 GOTO_W
     * 32765. This, in turn, may require to increase the size of another jump
     * instruction, and so on... All these operations are handled automatically
     * by this method.
     * <p>
     * <i>This method must be called after all the method that is being built
     * has been visited</i>. In particular, the {@link Label Label} objects used
     * to construct the method are no longer valid after this method has been
     * called.
     */
    private void resizeInstructions() {
        byte[] b = code.data; // bytecode of the method
        int u, v, label; // indexes in b
        int i, j; // loop indexes
        /*
         * 1st step: As explained above, resizing an instruction may require to
         * resize another one, which may require to resize yet another one, and
         * so on. The first step of the algorithm consists in finding all the
         * instructions that need to be resized, without modifying the code.
         * This is done by the following "fix point" algorithm:
         * 
         * Parse the code to find the jump instructions whose offset will need
         * more than 2 bytes to be stored (the future offset is computed from
         * the current offset and from the number of bytes that will be inserted
         * or removed between the source and target instructions). For each such
         * instruction, adds an entry in (a copy of) the indexes and sizes
         * arrays (if this has not already been done in a previous iteration!).
         * 
         * If at least one entry has been added during the previous step, go
         * back to the beginning, otherwise stop.
         * 
         * In fact the real algorithm is complicated by the fact that the size
         * of TABLESWITCH and LOOKUPSWITCH instructions depends on their
         * position in the bytecode (because of padding). In order to ensure the
         * convergence of the algorithm, the number of bytes to be added or
         * removed from these instructions is over estimated during the previous
         * loop, and computed exactly only after the loop is finished (this
         * requires another pass to parse the bytecode of the method).
         */
        int[] allIndexes = new int[0]; // copy of indexes
        int[] allSizes = new int[0]; // copy of sizes
        boolean[] resize; // instructions to be resized
        int newOffset; // future offset of a jump instruction

        resize = new boolean[code.length];

        // 3 = loop again, 2 = loop ended, 1 = last pass, 0 = done
        int state = 3;
        do {
            if (state == 3) {
                state = 2;
            }
            u = 0;
            while (u < b.length) {
                int opcode = b[u] & 0xFF; // opcode of current instruction
                int insert = 0; // bytes to be added after this instruction

                switch (ClassWriter.TYPE[opcode]) {
                case ClassWriter.NOARG_INSN:
                case ClassWriter.IMPLVAR_INSN:
                    u += 1;
                    break;
                case ClassWriter.LABEL_INSN:
                    if (opcode > 201) {
                        // converts temporary opcodes 202 to 217, 218 and
                        // 219 to IFEQ ... JSR (inclusive), IFNULL and
                        // IFNONNULL
                        opcode = opcode < 218 ? opcode - 49 : opcode - 20;
                        label = u + readUnsignedShort(b, u + 1);
                    } else {
                        label = u + readShort(b, u + 1);
                    }
                    newOffset = getNewOffset(allIndexes, allSizes, u, label);
                    if (newOffset < Short.MIN_VALUE
                            || newOffset > Short.MAX_VALUE) {
                        if (!resize[u]) {
                            if (opcode == Opcodes.GOTO || opcode == Opcodes.JSR) {
                                // two additional bytes will be required to
                                // replace this GOTO or JSR instruction with
                                // a GOTO_W or a JSR_W
                                insert = 2;
                            } else {
                                // five additional bytes will be required to
                                // replace this IFxxx <l> instruction with
                                // IFNOTxxx <l'> GOTO_W <l>, where IFNOTxxx
                                // is the "opposite" opcode of IFxxx (i.e.,
                                // IFNE for IFEQ) and where <l'> designates
                                // the instruction just after the GOTO_W.
                                insert = 5;
                            }
                            resize[u] = true;
                        }
                    }
                    u += 3;
                    break;
                case ClassWriter.LABELW_INSN:
                    u += 5;
                    break;
                case ClassWriter.TABL_INSN:
                    if (state == 1) {
                        // true number of bytes to be added (or removed)
                        // from this instruction = (future number of padding
                        // bytes - current number of padding byte) -
                        // previously over estimated variation =
                        // = ((3 - newOffset%4) - (3 - u%4)) - u%4
                        // = (-newOffset%4 + u%4) - u%4
                        // = -(newOffset & 3)
                        newOffset = getNewOffset(allIndexes, allSizes, 0, u);
                        insert = -(newOffset & 3);
                    } else if (!resize[u]) {
                        // over estimation of the number of bytes to be
                        // added to this instruction = 3 - current number
                        // of padding bytes = 3 - (3 - u%4) = u%4 = u & 3
                        insert = u & 3;
                        resize[u] = true;
                    }
                    // skips instruction
                    u = u + 4 - (u & 3);
                    u += 4 * (readInt(b, u + 8) - readInt(b, u + 4) + 1) + 12;
                    break;
                case ClassWriter.LOOK_INSN:
                    if (state == 1) {
                        // like TABL_INSN
                        newOffset = getNewOffset(allIndexes, allSizes, 0, u);
                        insert = -(newOffset & 3);
                    } else if (!resize[u]) {
                        // like TABL_INSN
                        insert = u & 3;
                        resize[u] = true;
                    }
                    // skips instruction
                    u = u + 4 - (u & 3);
                    u += 8 * readInt(b, u + 4) + 8;
                    break;
                case ClassWriter.WIDE_INSN:
                    opcode = b[u + 1] & 0xFF;
                    if (opcode == Opcodes.IINC) {
                        u += 6;
                    } else {
                        u += 4;
                    }
                    break;
                case ClassWriter.VAR_INSN:
                case ClassWriter.SBYTE_INSN:
                case ClassWriter.LDC_INSN:
                    u += 2;
                    break;
                case ClassWriter.SHORT_INSN:
                case ClassWriter.LDCW_INSN:
                case ClassWriter.FIELDORMETH_INSN:
                case ClassWriter.TYPE_INSN:
                case ClassWriter.IINC_INSN:
                    u += 3;
                    break;
                case ClassWriter.ITFMETH_INSN:
                case ClassWriter.INDYMETH_INSN:
                    u += 5;
                    break;
                // case ClassWriter.MANA_INSN:
                default:
                    u += 4;
                    break;
                }
                if (insert != 0) {
                    // adds a new (u, insert) entry in the allIndexes and
                    // allSizes arrays
                    int[] newIndexes = new int[allIndexes.length + 1];
                    int[] newSizes = new int[allSizes.length + 1];
                    System.arraycopy(allIndexes, 0, newIndexes, 0,
                            allIndexes.length);
                    System.arraycopy(allSizes, 0, newSizes, 0, allSizes.length);
                    newIndexes[allIndexes.length] = u;
                    newSizes[allSizes.length] = insert;
                    allIndexes = newIndexes;
                    allSizes = newSizes;
                    if (insert > 0) {
                        state = 3;
                    }
                }
            }
            if (state < 3) {
                --state;
            }
        } while (state != 0);

        // 2nd step:
        // copies the bytecode of the method into a new bytevector, updates the
        // offsets, and inserts (or removes) bytes as requested.

        ByteVector newCode = new ByteVector(code.length);

        u = 0;
        while (u < code.length) {
            int opcode = b[u] & 0xFF;
            switch (ClassWriter.TYPE[opcode]) {
            case ClassWriter.NOARG_INSN:
            case ClassWriter.IMPLVAR_INSN:
                newCode.putByte(opcode);
                u += 1;
                break;
            case ClassWriter.LABEL_INSN:
                if (opcode > 201) {
                    // changes temporary opcodes 202 to 217 (inclusive), 218
                    // and 219 to IFEQ ... JSR (inclusive), IFNULL and
                    // IFNONNULL
                    opcode = opcode < 218 ? opcode - 49 : opcode - 20;
                    label = u + readUnsignedShort(b, u + 1);
                } else {
                    label = u + readShort(b, u + 1);
                }
                newOffset = getNewOffset(allIndexes, allSizes, u, label);
                if (resize[u]) {
                    // replaces GOTO with GOTO_W, JSR with JSR_W and IFxxx
                    // <l> with IFNOTxxx <l'> GOTO_W <l>, where IFNOTxxx is
                    // the "opposite" opcode of IFxxx (i.e., IFNE for IFEQ)
                    // and where <l'> designates the instruction just after
                    // the GOTO_W.
                    if (opcode == Opcodes.GOTO) {
                        newCode.putByte(200); // GOTO_W
                    } else if (opcode == Opcodes.JSR) {
                        newCode.putByte(201); // JSR_W
                    } else {
                        newCode.putByte(opcode <= 166 ? ((opcode + 1) ^ 1) - 1
                                : opcode ^ 1);
                        newCode.putShort(8); // jump offset
                        newCode.putByte(200); // GOTO_W
                        // newOffset now computed from start of GOTO_W
                        newOffset -= 3;
                    }
                    newCode.putInt(newOffset);
                } else {
                    newCode.putByte(opcode);
                    newCode.putShort(newOffset);
                }
                u += 3;
                break;
            case ClassWriter.LABELW_INSN:
                label = u + readInt(b, u + 1);
                newOffset = getNewOffset(allIndexes, allSizes, u, label);
                newCode.putByte(opcode);
                newCode.putInt(newOffset);
                u += 5;
                break;
            case ClassWriter.TABL_INSN:
                // skips 0 to 3 padding bytes
                v = u;
                u = u + 4 - (v & 3);
                // reads and copies instruction
                newCode.putByte(Opcodes.TABLESWITCH);
                newCode.putByteArray(null, 0, (4 - newCode.length % 4) % 4);
                label = v + readInt(b, u);
                u += 4;
                newOffset = getNewOffset(allIndexes, allSizes, v, label);
                newCode.putInt(newOffset);
                j = readInt(b, u);
                u += 4;
                newCode.putInt(j);
                j = readInt(b, u) - j + 1;
                u += 4;
                newCode.putInt(readInt(b, u - 4));
                for (; j > 0; --j) {
                    label = v + readInt(b, u);
                    u += 4;
                    newOffset = getNewOffset(allIndexes, allSizes, v, label);
                    newCode.putInt(newOffset);
                }
                break;
            case ClassWriter.LOOK_INSN:
                // skips 0 to 3 padding bytes
                v = u;
                u = u + 4 - (v & 3);
                // reads and copies instruction
                newCode.putByte(Opcodes.LOOKUPSWITCH);
                newCode.putByteArray(null, 0, (4 - newCode.length % 4) % 4);
                label = v + readInt(b, u);
                u += 4;
                newOffset = getNewOffset(allIndexes, allSizes, v, label);
                newCode.putInt(newOffset);
                j = readInt(b, u);
                u += 4;
                newCode.putInt(j);
                for (; j > 0; --j) {
                    newCode.putInt(readInt(b, u));
                    u += 4;
                    label = v + readInt(b, u);
                    u += 4;
                    newOffset = getNewOffset(allIndexes, allSizes, v, label);
                    newCode.putInt(newOffset);
                }
                break;
            case ClassWriter.WIDE_INSN:
                opcode = b[u + 1] & 0xFF;
                if (opcode == Opcodes.IINC) {
                    newCode.putByteArray(b, u, 6);
                    u += 6;
                } else {
                    newCode.putByteArray(b, u, 4);
                    u += 4;
                }
                break;
            case ClassWriter.VAR_INSN:
            case ClassWriter.SBYTE_INSN:
            case ClassWriter.LDC_INSN:
                newCode.putByteArray(b, u, 2);
                u += 2;
                break;
            case ClassWriter.SHORT_INSN:
            case ClassWriter.LDCW_INSN:
            case ClassWriter.FIELDORMETH_INSN:
            case ClassWriter.TYPE_INSN:
            case ClassWriter.IINC_INSN:
                newCode.putByteArray(b, u, 3);
                u += 3;
                break;
            case ClassWriter.ITFMETH_INSN:
            case ClassWriter.INDYMETH_INSN:
                newCode.putByteArray(b, u, 5);
                u += 5;
                break;
            // case MANA_INSN:
            default:
                newCode.putByteArray(b, u, 4);
                u += 4;
                break;
            }
        }

        // recomputes the stack map frames
        if (frameCount > 0) {
            if (compute == FRAMES) {
                frameCount = 0;
                stackMap = null;
                previousFrame = null;
                frame = null;
                Frame f = new Frame();
                f.owner = labels;
                Type[] args = Type.getArgumentTypes(descriptor);
                f.initInputFrame(cw, access, args, maxLocals);
                visitFrame(f);
                Label l = labels;
                while (l != null) {
                    /*
                     * here we need the original label position. getNewOffset
                     * must therefore never have been called for this label.
                     */
                    u = l.position - 3;
                    if ((l.status & Label.STORE) != 0 || (u >= 0 && resize[u])) {
                        getNewOffset(allIndexes, allSizes, l);
                        // TODO update offsets in UNINITIALIZED values
                        visitFrame(l.frame);
                    }
                    l = l.successor;
                }
            } else {
                /*
                 * Resizing an existing stack map frame table is really hard.
                 * Not only the table must be parsed to update the offets, but
                 * new frames may be needed for jump instructions that were
                 * inserted by this method. And updating the offsets or
                 * inserting frames can change the format of the following
                 * frames, in case of packed frames. In practice the whole table
                 * must be recomputed. For this the frames are marked as
                 * potentially invalid. This will cause the whole class to be
                 * reread and rewritten with the COMPUTE_FRAMES option (see the
                 * ClassWriter.toByteArray method). This is not very efficient
                 * but is much easier and requires much less code than any other
                 * method I can think of.
                 */
                cw.invalidFrames = true;
            }
        }
        // updates the exception handler block labels
        Handler h = firstHandler;
        while (h != null) {
            getNewOffset(allIndexes, allSizes, h.start);
            getNewOffset(allIndexes, allSizes, h.end);
            getNewOffset(allIndexes, allSizes, h.handler);
            h = h.next;
        }
        // updates the instructions addresses in the
        // local var and line number tables
        for (i = 0; i < 2; ++i) {
            ByteVector bv = i == 0 ? localVar : localVarType;
            if (bv != null) {
                b = bv.data;
                u = 0;
                while (u < bv.length) {
                    label = readUnsignedShort(b, u);
                    newOffset = getNewOffset(allIndexes, allSizes, 0, label);
                    writeShort(b, u, newOffset);
                    label += readUnsignedShort(b, u + 2);
                    newOffset = getNewOffset(allIndexes, allSizes, 0, label)
                            - newOffset;
                    writeShort(b, u + 2, newOffset);
                    u += 10;
                }
            }
        }
        if (lineNumber != null) {
            b = lineNumber.data;
            u = 0;
            while (u < lineNumber.length) {
                writeShort(
                        b,
                        u,
                        getNewOffset(allIndexes, allSizes, 0,
                                readUnsignedShort(b, u)));
                u += 4;
            }
        }
        // updates the labels of the other attributes
        Attribute attr = cattrs;
        while (attr != null) {
            Label[] labels = attr.getLabels();
            if (labels != null) {
                for (i = labels.length - 1; i >= 0; --i) {
                    getNewOffset(allIndexes, allSizes, labels[i]);
                }
            }
            attr = attr.next;
        }

        // replaces old bytecodes with new ones
        code = newCode;
    }

    
Reads an unsigned short value in the given byte array.
Params:
b – 
           a byte array.
index – 
           the start index of the value to be read.
Returns:
the read value./**
     * Reads an unsigned short value in the given byte array.
     * 
     * @param b
     *            a byte array.
     * @param index
     *            the start index of the value to be read.
     * @return the read value.
     */
    static int readUnsignedShort(final byte[] b, final int index) {
        return ((b[index] & 0xFF) << 8) | (b[index + 1] & 0xFF);
    }

    
Reads a signed short value in the given byte array.
Params:
b – 
           a byte array.
index – 
           the start index of the value to be read.
Returns:
the read value./**
     * Reads a signed short value in the given byte array.
     * 
     * @param b
     *            a byte array.
     * @param index
     *            the start index of the value to be read.
     * @return the read value.
     */
    static short readShort(final byte[] b, final int index) {
        return (short) (((b[index] & 0xFF) << 8) | (b[index + 1] & 0xFF));
    }

    
Reads a signed int value in the given byte array.
Params:
b – 
           a byte array.
index – 
           the start index of the value to be read.
Returns:
the read value./**
     * Reads a signed int value in the given byte array.
     * 
     * @param b
     *            a byte array.
     * @param index
     *            the start index of the value to be read.
     * @return the read value.
     */
    static int readInt(final byte[] b, final int index) {
        return ((b[index] & 0xFF) << 24) | ((b[index + 1] & 0xFF) << 16)
                | ((b[index + 2] & 0xFF) << 8) | (b[index + 3] & 0xFF);
    }

    
Writes a short value in the given byte array.
Params:
b – 
           a byte array.
index – 
           where the first byte of the short value must be written.
s – 
           the value to be written in the given byte array./**
     * Writes a short value in the given byte array.
     * 
     * @param b
     *            a byte array.
     * @param index
     *            where the first byte of the short value must be written.
     * @param s
     *            the value to be written in the given byte array.
     */
    static void writeShort(final byte[] b, final int index, final int s) {
        b[index] = (byte) (s >>> 8);
        b[index + 1] = (byte) s;
    }

    
Computes the future value of a bytecode offset.

Note: it is possible to have several entries for the same instruction in
the indexes and sizes: two entries (index=a,size=b) and
(index=a,size=b') are equivalent to a single entry (index=a,size=b+b').
Params:
indexes – 
           current positions of the instructions to be resized. Each
           instruction must be designated by the index of its last
           byte, plus one (or, in other words, by the index of the
           first byte of the next instruction).
sizes – 
           the number of bytes to be added to the above
           instructions. More precisely, for each i < len,
           sizes[i] bytes will be added at the end of the
           instruction designated by indexes[i] or, if
           sizes[i] is negative, the last |
           sizes[i]| bytes of the instruction will be removed
           (the instruction size must not become negative or
           null).
begin – 
           index of the first byte of the source instruction.
end – 
           index of the first byte of the target instruction.
Returns:
the future value of the given bytecode offset./**
     * Computes the future value of a bytecode offset.
     * <p>
     * Note: it is possible to have several entries for the same instruction in
     * the <tt>indexes</tt> and <tt>sizes</tt>: two entries (index=a,size=b) and
     * (index=a,size=b') are equivalent to a single entry (index=a,size=b+b').
     * 
     * @param indexes
     *            current positions of the instructions to be resized. Each
     *            instruction must be designated by the index of its <i>last</i>
     *            byte, plus one (or, in other words, by the index of the
     *            <i>first</i> byte of the <i>next</i> instruction).
     * @param sizes
     *            the number of bytes to be <i>added</i> to the above
     *            instructions. More precisely, for each i < <tt>len</tt>,
     *            <tt>sizes</tt>[i] bytes will be added at the end of the
     *            instruction designated by <tt>indexes</tt>[i] or, if
     *            <tt>sizes</tt>[i] is negative, the <i>last</i> |
     *            <tt>sizes[i]</tt>| bytes of the instruction will be removed
     *            (the instruction size <i>must not</i> become negative or
     *            null).
     * @param begin
     *            index of the first byte of the source instruction.
     * @param end
     *            index of the first byte of the target instruction.
     * @return the future value of the given bytecode offset.
     */
    static int getNewOffset(final int[] indexes, final int[] sizes,
            final int begin, final int end) {
        int offset = end - begin;
        for (int i = 0; i < indexes.length; ++i) {
            if (begin < indexes[i] && indexes[i] <= end) {
                // forward jump
                offset += sizes[i];
            } else if (end < indexes[i] && indexes[i] <= begin) {
                // backward jump
                offset -= sizes[i];
            }
        }
        return offset;
    }

    
Updates the offset of the given label.
Params:
indexes – 
           current positions of the instructions to be resized. Each
           instruction must be designated by the index of its last
           byte, plus one (or, in other words, by the index of the
           first byte of the next instruction).
sizes – 
           the number of bytes to be added to the above
           instructions. More precisely, for each i < len,
           sizes[i] bytes will be added at the end of the
           instruction designated by indexes[i] or, if
           sizes[i] is negative, the last |
           sizes[i]| bytes of the instruction will be removed
           (the instruction size must not become negative or
           null).
label – 
           the label whose offset must be updated./**
     * Updates the offset of the given label.
     * 
     * @param indexes
     *            current positions of the instructions to be resized. Each
     *            instruction must be designated by the index of its <i>last</i>
     *            byte, plus one (or, in other words, by the index of the
     *            <i>first</i> byte of the <i>next</i> instruction).
     * @param sizes
     *            the number of bytes to be <i>added</i> to the above
     *            instructions. More precisely, for each i < <tt>len</tt>,
     *            <tt>sizes</tt>[i] bytes will be added at the end of the
     *            instruction designated by <tt>indexes</tt>[i] or, if
     *            <tt>sizes</tt>[i] is negative, the <i>last</i> |
     *            <tt>sizes[i]</tt>| bytes of the instruction will be removed
     *            (the instruction size <i>must not</i> become negative or
     *            null).
     * @param label
     *            the label whose offset must be updated.
     */
    static void getNewOffset(final int[] indexes, final int[] sizes,
            final Label label) {
        if ((label.status & Label.RESIZED) == 0) {
            label.position = getNewOffset(indexes, sizes, 0, label.position);
            label.status |= Label.RESIZED;
        }
    }
}