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MethodWriter.java
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2685 lines (2555 loc) · 101 KB
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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 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 extends MethodVisitor {
/**
* 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.
*/
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
*/
static final int SAME_LOCALS_1_STACK_ITEM_FRAME = 64; // to 127 (40-7f)
/**
* 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;
*/
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.
*/
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;
*/
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.
*/
static final int APPEND_FRAME = 252; // to 254 // fc-fe
/**
* 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 #compute
*/
private static final int FRAMES = 0;
/**
* 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 #compute
*/
private static final int NOTHING = 2;
/**
* The class writer to which this method must be added.
*/
final 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 final int name;
/**
* The index of the constant pool item that contains the descriptor of this
* method.
*/
private final int desc;
/**
* The descriptor of this method.
*/
private final 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 number of synthetic parameters of this method.
*/
private int synthetics;
/**
* 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 local variables in the current stack map frame.
*/
private int currentLocals;
/**
* 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;
/**
* 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;
/**
* 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 #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
* {@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.
*/
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) {
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) {