/***
* ASM: a very small and fast Java bytecode manipulation framework
* Copyright (c) 2000-2005 INRIA, France Telecom
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the copyright holders nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
* THE POSSIBILITY OF SUCH DAMAGE.
*/
package clojure.asm;
/**
* 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 implements MethodVisitor{
/**
* Pseudo access flag used to denote constructors.
*/
final static int ACC_CONSTRUCTOR = 262144;
/**
* Frame has exactly the same locals as the previous stack map frame and
* number of stack items is zero.
*/
final static 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
*/
final static int SAME_LOCALS_1_STACK_ITEM_FRAME = 64; // to 127 (40-7f)
/**
* Reserved for future use
*/
final static 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;
*/
final static 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.
*/
final static 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;
*/
final static 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.
*/
final static int APPEND_FRAME = 252; // to 254 // fc-fe
/**
* Full frame
*/
final static 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 #compute
*/
private final static int FRAMES = 0;
/**
* Indicates that the maximum stack size and number of local variables must
* be automatically computed.
*
* @see #compute
*/
private final static int MAXS = 1;
/**
* Indicates that nothing must be automatically computed.
*
* @see #compute
*/
private final static int NOTHING = 2;
/**
* Next method writer (see {@link ClassWriter#firstMethod firstMethod}).
*/
MethodWriter next;
/**
* The class writer to which this method must be added.
*/
ClassWriter cw;
/**
* Access flags of this method.
*/
private int access;
/**
* The index of the constant pool item that contains the name of this
* method.
*/
private int name;
/**
* The index of the constant pool item that contains the descriptor of this
* method.
*/
private int desc;
/**
* The descriptor of this method.
*/
private String descriptor;
/**
* 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 <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 <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.
*/
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.
*/
int[] exceptions;
/**
* The annotation default attribute of this method. May be <tt>null</tt>.
*/
private ByteVector annd;
/**
* The runtime visible annotations of this method. May be <tt>null</tt>.
*/
private AnnotationWriter anns;
/**
* 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
* <tt>null</tt>.
*/
private AnnotationWriter[] panns;
/**
* The runtime invisible parameter annotations of this method. May be
* <tt>null</tt>.
*/
private AnnotationWriter[] ipanns;
/**
* The non standard attributes of the method.
*/
private Attribute attrs;
/**
* The bytecode of this method.
*/
private ByteVector code = new ByteVector();
/**
* Maximum stack size of this method.
*/
private int maxStack;
/**
* Maximum number of local variables for this method.
*/
private int maxLocals;
/**
* Number of stack map frames in the StackMapTable attribute.
*/
private int frameCount;
/**
* The StackMapTable attribute.
*/
private ByteVector stackMap;
/**
* 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 #frame
*/
private int[] previousFrame;
/**
* Index of the next element to be added in {@link #frame}.
*/
private int frameIndex;
/**
* 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.
*/
private int handlerCount;
/**
* The first element in the exception handler list.
*/
private Handler firstHandler;
/**
* The last element in the exception handler list.
*/
private Handler lastHandler;
/**
* Number of entries in the LocalVariableTable attribute.
*/
private int localVarCount;
/**
* The LocalVariableTable attribute.
*/
private ByteVector localVar;
/**
* Number of entries in the LocalVariableTypeTable attribute.
*/
private int localVarTypeCount;
/**
* The LocalVariableTypeTable attribute.
*/
private ByteVector localVarType;
/**
* Number of entries in the LineNumberTable attribute.
*/
private int lineNumberCount;
/**
* The LineNumberTable attribute.
*/
private ByteVector lineNumber;
/**
* 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.
*/
private boolean resize;
/**
* Indicates if the instructions contain at least one JSR instruction.
*/
private boolean jsr;
// ------------------------------------------------------------------------
/*
* 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 FRAMES
* @see MAXS
* @see NOTHING
*/
private 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
* {@link Label#successor} field, in the order they are visited by
* {@link visitLabel}, and starting with the first basic block.
*/
private Label labels;
/**
* The previous basic block.
*/
private Label previousBlock;
/**
* 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
* {@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 {@link Label#inputStackTop beginStackSize} of the current basic
* block plus <tt>stackSize</tt>.
*/
private int maxStackSize;
// ------------------------------------------------------------------------
// Constructor
// ------------------------------------------------------------------------
/**
* 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){
if(cw.firstMethod == null)
{
cw.firstMethod = this;
}
else
{
cw.lastMethod.next = this;
}
cw.lastMethod = this;
this.cw = cw;
this.access = access;
this.name = cw.newUTF8(name);
this.desc = cw.newUTF8(desc);
this.descriptor = desc;
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)
{
if(computeFrames && name.equals("<init>"))
{
this.access |= ACC_CONSTRUCTOR;
}
// updates maxLocals
int size = getArgumentsAndReturnSizes(descriptor) >> 2;
if((access & Opcodes.ACC_STATIC) != 0)
{
--size;
}
maxLocals = size;
// creates and visits the label for the first basic block
labels = new Label();
labels.status |= Label.PUSHED;
visitLabel(labels);
}
}
// ------------------------------------------------------------------------
// Implementation of the MethodVisitor interface
// ------------------------------------------------------------------------
public AnnotationVisitor visitAnnotationDefault(){
annd = new ByteVector();
return new AnnotationWriter(cw, false, annd, null, 0);
}
public AnnotationVisitor visitAnnotation(
final String desc,
final boolean visible){
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;
}
public AnnotationVisitor visitParameterAnnotation(
final int parameter,
final String desc,
final boolean visible){
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)
{
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;
}
public void visitAttribute(final Attribute attr){
if(attr.isCodeAttribute())
{
attr.next = cattrs;
cattrs = attr;
}
else
{
attr.next = attrs;
attrs = attr;
}
}
public void visitCode(){
}
public void visitFrame(
final int type,
final int nLocal,
final Object[] local,
final int nStack,
final Object[] stack){
if(compute == FRAMES)
{
return;
}
if(type == Opcodes.F_NEW)
{
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;
}
switch(type)
{
case Opcodes.F_FULL:
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:
stackMap.putByte(SAME_FRAME_EXTENDED + nLocal)
.putShort(delta);
for(int i = 0; i < nLocal; ++i)
{
writeFrameType(local[i]);
}
break;
case Opcodes.F_CHOP:
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;
}
}
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();
}
}
}
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);
}
}
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());
}
}
public void visitTypeInsn(final int opcode, final String desc){
Item i = cw.newClassItem(desc);
// 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);
}
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);
}
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 = 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 = getArgumentsAndReturnSizes(desc);
i.intVal = argSize;
}
code.put12(Opcodes.INVOKEINTERFACE, i.index).put11(argSize >> 2, 0);
}
else
{
code.put12(opcode, i.index);
}
}
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)
{
jsr = true;
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();
}
}
}
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;
}
}
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);
}
}
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);
}
}
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.length += (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);
}
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.length += (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();
}
}
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);
}
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;
}
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;
}
}
}
public void visitLineNumber(final int line, final Label start){
if(lineNumber == null)
{
lineNumber = new ByteVector();
}
++lineNumberCount;
lineNumber.putShort(start.position);
lineNumber.putShort(line);
}
public void visitMaxs(final int maxStack, final int maxLocals){
if(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 reacheable jump target must be stored in the stack map
if((l.status & Label.TARGET) != 0)
{
l.status |= Label.STORE;
}
// all visited labels are reacheable, 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;
}
}
this.maxStack = max;
// 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)
{
// 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
startFrame(start, 0, 1);
frame[frameIndex++] = Frame.OBJECT
| cw.addType("java/lang/Throwable");
endFrame();
}
}
l = l.successor;
}
}
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)
{
// 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;
}
else
{
b.next = l.successors;
l.successors = b;
}
// goes to the next label
l = l.successor;
}
handler = handler.next;
}
if(jsr)
{
// 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, and
* stores this set as a bit set in the {@link Label#status}
* field. Subroutines are numbered with powers of two, from
* 0x1000 to 0x80000000 (so there must be at most 20 subroutines
* in a method).
*/
// finds the basic blocks that belong to the "main" subroutine
int id = 0x1000;
findSubroutine(labels, id);
// 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 does not have an id yet...
if((subroutine.status & ~0xFFF) == 0)
{
// ...assigns it a new id and finds its basic blocks
id = id << 1;
findSubroutine(subroutine, id);
}
}
l = l.successor;
}
// second step: finds the successors of RET blocks
findSubroutineSuccessors(0x1000, new Label[10], 0);
}
/*
* 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;
}
// analyses 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 = max;
}
else
{
this.maxStack = maxStack;
this.maxLocals = maxLocals;
}
}
public void visitEnd(){
}
// ------------------------------------------------------------------------
// Utility methods: control flow analysis algorithm
// ------------------------------------------------------------------------
/**
* Computes the size of the arguments and of the return value of a method.
*
* @param desc the descriptor of a method.
* @return the size of the arguments of the method (plus one for the
* implicit this argument), argSize, and the size of its return
* value, retSize, packed into a single int i =
* <tt>(argSize << 2) | retSize</tt> (argSize is therefore equal
* to <tt>i >> 2</tt>, and retSize to <tt>i & 0x03</tt>).
*/
static int getArgumentsAndReturnSizes(final String desc){
int n = 1;
int c = 1;
while(true)
{
char car = desc.charAt(c++);
if(car == ')')
{
car = desc.charAt(c);
return n << 2
| (car == 'V' ? 0 : (car == 'D' || car == 'J' ? 2 : 1));
}
else if(car == 'L')
{
while(desc.charAt(c++) != ';')
{
}
n += 1;
}
else if(car == '[')
{
while((car = desc.charAt(c)) == '[')
{
++c;
}
if(car == 'D' || car == 'J')
{
n -= 1;
}
}
else if(car == 'D' || car == 'J')
{
n += 2;
}
else
{
n += 1;
}
}
}
/**
* 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.
*/
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;
}
/**
* Finds the basic blocks that belong to a given subroutine, and marks these
* blocks as belonging to this subroutine (by using {@link Label#status} as
* a bit set (see {@link #visitMaxs}). This recursive method follows the
* control flow graph to find all the blocks that are reachable from the
* given block WITHOUT following any JSR target.
*
* @param block a block that belongs to the subroutine
* @param id the id of this subroutine
*/
private void findSubroutine(final Label block, final int id){
// if 'block' is already marked as belonging to subroutine 'id', returns
if((block.status & id) != 0)
{
return;
}
// marks 'block' as belonging to subroutine 'id'
block.status |= id;
// calls this method recursively on each successor, except JSR targets
Edge e = block.successors;
while(e != null)
{
// if 'block' is a JSR block, then 'block.successors.next' leads
// to the JSR target (see {@link #visitJumpInsn}) and must therefore
// not be followed
if((block.status & Label.JSR) == 0 || e != block.successors.next)
{
findSubroutine(e.successor, id);
}
e = e.next;
}
}
/**
* Finds the successors of the RET blocks of the specified subroutine, and
* of any nested subroutine it calls.
*
* @param id id of the subroutine whose RET block successors must be found.
* @param JSRs the JSR blocks that were followed to reach this subroutine.
* @param nJSRs number of JSR blocks in the JSRs array.
*/
private void findSubroutineSuccessors(
final int id,
final Label[] JSRs,
final int nJSRs){
// iterates over all the basic blocks...
Label l = labels;
while(l != null)
{
// for those that belong to subroutine 'id'...
if((l.status & id) != 0)
{
if((l.status & Label.JSR) != 0)
{
// finds the subroutine to which 'l' leads by following the
// second edge of l.successors (see {@link #visitJumpInsn})
int nId = l.successors.next.successor.status & ~0xFFF;
if(nId != id)
{
// calls this method recursively with l pushed onto the
// JSRs stack to find the successors of the RET blocks
// of this nested subroutine 'nId'
JSRs[nJSRs] = l;
findSubroutineSuccessors(nId, JSRs, nJSRs + 1);
}
}
else if((l.status & Label.RET) != 0)
{
/*
* finds the JSR block in the JSRs stack that corresponds to
* this RET block, and updates the successors of this RET
* block accordingly. This corresponding JSR is the one that
* leads to the subroutine to which the RET block belongs.
* But the RET block can belong to several subroutines (if a
* nested subroutine returns to its parent subroutine
* implicitely, without a RET). So, in fact, the JSR that
* corresponds to this RET is the first block in the JSRs
* stack, starting from the bottom of the stack, that leads
* to a subroutine to which the RET block belongs.
*/
for(int i = 0; i < nJSRs; ++i)
{
int JSRstatus = JSRs[i].successors.next.successor.status;
if(((JSRstatus & ~0xFFF) & (l.status & ~0xFFF)) != 0)
{
Edge e = new Edge();
e.info = l.inputStackTop;
e.successor = JSRs[i].successors.successor;
e.next = l.successors;
l.successors = e;
break;
}
}
}
}
l = l.successor;
}
}
// ------------------------------------------------------------------------
// Utility methods: stack map frames
// ------------------------------------------------------------------------
/**
* 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
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();
}
/**
* 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.
*/
private void 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;
frameIndex = 3;
}
/**
* 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 {@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 {@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.
*
* @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.
resizeInstructions();
}
int size = 8;
if(code.length > 0)
{
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
&& (cw.version & 0xffff) < Opcodes.V1_5)
{
cw.newUTF8("Synthetic");
size += 6;
}
if((access & Opcodes.ACC_DEPRECATED) != 0)
{
cw.newUTF8("Deprecated");
size += 6;
}
if(signature != null)
{
cw.newUTF8("Signature");
cw.newUTF8(signature);
size += 8;
}
if(annd != null)
{
cw.newUTF8("AnnotationDefault");
size += 6 + annd.length;
}
if(anns != null)
{
cw.newUTF8("RuntimeVisibleAnnotations");
size += 8 + anns.getSize();
}
if(ianns != null)
{
cw.newUTF8("RuntimeInvisibleAnnotations");
size += 8 + ianns.getSize();
}
if(panns != null)
{
cw.newUTF8("RuntimeVisibleParameterAnnotations");
size += 7 + 2 * panns.length;
for(int i = panns.length - 1; i >= 0; --i)
{
size += panns[i] == null ? 0 : panns[i].getSize();
}
}
if(ipanns != null)
{
cw.newUTF8("RuntimeInvisibleParameterAnnotations");
size += 7 + 2 * ipanns.length;
for(int i = ipanns.length - 1; i >= 0; --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.
*
* @param out the byte vector into which the bytecode of this method must be
* copied.
*/
final void put(final ByteVector out){
out.putShort(access).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
&& (cw.version & 0xffff) < Opcodes.V1_5)
{
++attributeCount;
}
if((access & Opcodes.ACC_DEPRECATED) != 0)
{
++attributeCount;
}
if(signature != null)
{
++attributeCount;
}
if(annd != null)
{
++attributeCount;
}
if(anns != null)
{
++attributeCount;
}
if(ianns != null)
{
++attributeCount;
}
if(panns != null)
{
++attributeCount;
}
if(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
&& (cw.version & 0xffff) < Opcodes.V1_5)
{
out.putShort(cw.newUTF8("Synthetic")).putInt(0);
}
if((access & Opcodes.ACC_DEPRECATED) != 0)
{
out.putShort(cw.newUTF8("Deprecated")).putInt(0);
}
if(signature != null)
{
out.putShort(cw.newUTF8("Signature"))
.putInt(2)
.putShort(cw.newUTF8(signature));
}
if(annd != null)
{
out.putShort(cw.newUTF8("AnnotationDefault"));
out.putInt(annd.length);
out.putByteArray(annd.data, 0, annd.length);
}
if(anns != null)
{
out.putShort(cw.newUTF8("RuntimeVisibleAnnotations"));
anns.put(out);
}
if(ianns != null)
{
out.putShort(cw.newUTF8("RuntimeInvisibleAnnotations"));
ianns.put(out);
}
if(panns != null)
{
out.putShort(cw.newUTF8("RuntimeVisibleParameterAnnotations"));
AnnotationWriter.put(panns, out);
}
if(ipanns != null)
{
out.putShort(cw.newUTF8("RuntimeInvisibleParameterAnnotations"));
AnnotationWriter.put(ipanns, 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
* {@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:
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.length += (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.length += (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:
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.
*
* @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.
*
* @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.
*
* @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.
*
* @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. <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.
*
* @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;
}
}
}