com.videobug.agent.weaver.method

Class MethodTransformer

java.lang.Object

org.objectweb.asm.MethodVisitor

org.objectweb.asm.commons.LocalVariablesSorter

com.videobug.agent.weaver.method.MethodTransformer

public class MethodTransformer
extends org.objectweb.asm.commons.LocalVariablesSorter

This class is the main implementation of the weaving process for each method. This class extends LocalVariablesSorter because this class insert additional local variables to temporarily preserves method parameters.

Field Summary

Fields

Modifier and Type	Field and Description
static String	LOGGER_CLASS
static String	METHOD_RECORD_EVENT

Fields inherited from class org.objectweb.asm.commons.LocalVariablesSorter

firstLocal, nextLocal

Fields inherited from class org.objectweb.asm.MethodVisitor

api, mv

Constructor Summary

Constructors

Constructor and Description
MethodTransformer(WeaveLog w, WeaveConfig config, String sourceFileName, String className, String outerClassName, int access, String methodName, String methodDesc, String signature, String[] exceptions, org.objectweb.asm.MethodVisitor mv) Initialize the instance

Method Summary

Modifier and Type	Method and Description
void	setup(List<?> localVariableNodes, org.objectweb.asm.tree.InsnList instructions) Receives local variables and instructions in this method.
void	visitCode() Visiting a method body.
void	visitEnd() End the weaving.
void	visitFieldInsn(int opcode, String owner, String name, String desc) Insert logging code for field access instruction.
void	visitFrame(int type, int numLocal, Object[] local, int numStack, Object[] stack) Visits the current state of the local variables and operand stack elements.
void	visitIincInsn(int var, int increment) Insert logging code for an IINC instruction.
void	visitInsn(int opcode) Insert logging code for various instructions.
void	visitIntInsn(int opcode, int operand) Insert logging code for a NEWARRAY instruction.
void	visitInvokeDynamicInsn(String name, String desc, org.objectweb.asm.Handle bsm, Object... bsmArgs) Insert logging code for INVOKEDYNAMIC instruction.
void	visitJumpInsn(int opcode, org.objectweb.asm.Label label) Store a location for LABEL event if recordLabel is enabled.
void	visitLabel(org.objectweb.asm.Label label) Logging a jump instruction if recordLabel is enabled.
void	visitLdcInsn(Object cst) Insert logging code for a Load Constant instruction in order to record the constant object.
void	visitLineNumber(int line, org.objectweb.asm.Label start)
void	visitLookupSwitchInsn(org.objectweb.asm.Label dflt, int[] keys, org.objectweb.asm.Label[] labels) No additional actions but count the number of instructions.
void	visitMaxs(int maxStack, int maxLocals) Finalize the method.
void	visitMethodInsn(int opcode, String owner, String name, String desc, boolean itf) Insert logging code for INVOKE instructions.
void	visitMultiANewArrayInsn(String desc, int dims) Insert logging code for a MultiANewArray instruction.
void	visitTableSwitchInsn(int min, int max, org.objectweb.asm.Label dflt, org.objectweb.asm.Label... labels) No additional actions but count the number of instructions.
void	visitTryCatchBlock(org.objectweb.asm.Label start, org.objectweb.asm.Label end, org.objectweb.asm.Label handler, String type) Store entry points of catch blocks for later visit* methods.
void	visitTypeInsn(int opcode, String type) Insert logging code for NEW, ANEWARRAY, INSTANCEOF instructions.
void	visitVarInsn(int opcode, int var) Insert logging code for local variable and RET instructions.

Methods inherited from class org.objectweb.asm.commons.LocalVariablesSorter

newLocal, newLocalMapping, setLocalType, updateNewLocals, visitLocalVariable, visitLocalVariableAnnotation

Methods inherited from class org.objectweb.asm.MethodVisitor

visitAnnotableParameterCount, visitAnnotation, visitAnnotationDefault, visitAttribute, visitInsnAnnotation, visitMethodInsn, visitParameter, visitParameterAnnotation, visitTryCatchAnnotation, visitTypeAnnotation

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

LOGGER_CLASS

public static final String LOGGER_CLASS

See Also:

Constant Field Values

METHOD_RECORD_EVENT

public static final String METHOD_RECORD_EVENT

See Also:

Constant Field Values

Constructor Detail

MethodTransformer

public MethodTransformer(WeaveLog w,
                         WeaveConfig config,
                         String sourceFileName,
                         String className,
                         String outerClassName,
                         int access,
                         String methodName,
                         String methodDesc,
                         String signature,
                         String[] exceptions,
                         org.objectweb.asm.MethodVisitor mv)

Initialize the instance

Parameters:

w - is to log the progress

config - is the configuration of the weaving

sourceFileName - is a source file name (just for logging the progress)

className - is a class name

outerClassName - is outer class name if this class is ineer class

access - is modifiers of the method

methodName - is a method name

methodDesc - is a descriptor (parameter types and a return type)

signature - is a generics signature

exceptions - represents a throws clause

mv - is the object for writing bytecode

Method Detail

setup

public void setup(List<?> localVariableNodes,
                  org.objectweb.asm.tree.InsnList instructions)

Receives local variables and instructions in this method. This method must be called before weaving because local variable names and instruction indices are necessary to generate textual information for DataId.

Parameters:

localVariableNodes - list of LocalVariableNode

instructions - list of instructions for which information is to be collected

visitEnd

public void visitEnd()

End the weaving.

Overrides:

visitEnd in class org.objectweb.asm.MethodVisitor

visitLineNumber

public void visitLineNumber(int line,
                            org.objectweb.asm.Label start)

Overrides:

visitLineNumber in class org.objectweb.asm.MethodVisitor

Parameters:

line - line number from the source code

start - the current label under which this line number comes Record current line number for other visit methods

visitCode

public void visitCode()

Visiting a method body. Generate try { recordEntryEvent; recordParams; body(); } catch (Throwable t) { ... }.

Overrides:

visitCode in class org.objectweb.asm.MethodVisitor

visitTryCatchBlock

public void visitTryCatchBlock(org.objectweb.asm.Label start,
                               org.objectweb.asm.Label end,
                               org.objectweb.asm.Label handler,
                               String type)

Store entry points of catch blocks for later visit* methods. The method is called BEFORE visit* methods for other instructions, according to the implementation of MethodNode class.

Overrides:

visitTryCatchBlock in class org.objectweb.asm.MethodVisitor

Parameters:

start - start label of the try catch block

end - end label of the try catch block

handler - label of the catch handler of the try catch block

type - try catch block has a finally block or not

visitLabel

public void visitLabel(org.objectweb.asm.Label label)

Logging a jump instruction if recordLabel is enabled. Logging a catch event for a method call.

Overrides:

visitLabel in class org.objectweb.asm.MethodVisitor

Parameters:

label - the label instruction being visited

visitFrame

public void visitFrame(int type,
                       int numLocal,
                       Object[] local,
                       int numStack,
                       Object[] stack)

Visits the current state of the local variables and operand stack elements. This method must(*) be called just before any instruction i that follows an unconditional branch instruction such as GOTO or THROW, that is the target of a jump instruction, or that starts an exception handler block. The visited types must describe the values of the local variables and of the operand stack elements just before i is executed.

(*) this is mandatory only for classes whose version is greater than or equal to Opcodes.V1_6.

The frames of a method must be given either in expanded form, or in compressed form (all frames must use the same format, i.e. you must not mix expanded and compressed frames within a single method):

• In expanded form, all frames must have the F_NEW type.
• In compressed form, frames are basically "deltas" from the state of the previous frame:
  • Opcodes.F_SAME representing frame with exactly the same locals as the previous frame and with the empty stack.
  • Opcodes.F_SAME1 representing frame with exactly the same locals as the previous frame and with single value on the stack ( numStack is 1 and stack[0] contains value for the type of the stack item).
  • Opcodes.F_APPEND representing frame with current locals are the same as the locals in the previous frame, except that additional locals are defined ( numLocal is 1, 2 or 3 and local elements contains values representing added types).
  • Opcodes.F_CHOP representing frame with current locals are the same as the locals in the previous frame, except that the last 1-3 locals are absent and with the empty stack (numLocal is 1, 2 or 3).
  • Opcodes.F_FULL representing complete frame data.

In both cases the first frame, corresponding to the method's parameters and access flags, is implicit and must not be visited. Also, it is illegal to visit two or more frames for the same code location (i.e., at least one instruction must be visited between two calls to visitFrame).

Overrides:

visitFrame in class org.objectweb.asm.commons.LocalVariablesSorter

Parameters:

type - the type of this stack map frame. Must be Opcodes.F_NEW for expanded frames, or Opcodes.F_FULL, Opcodes.F_APPEND, Opcodes.F_CHOP, Opcodes.F_SAME or Opcodes.F_APPEND, Opcodes.F_SAME1 for compressed frames.

numLocal - the number of local variables in the visited frame.

local - the local variable types in this frame. This array must not be modified. Primitive types are represented by Opcodes.TOP, Opcodes.INTEGER, Opcodes.FLOAT, Opcodes.LONG, Opcodes.DOUBLE, Opcodes.NULL or Opcodes.UNINITIALIZED_THIS (long and double are represented by a single element). Reference types are represented by String objects (representing internal names), and uninitialized types by Label objects (this label designates the NEW instruction that created this uninitialized value).

numStack - the number of operand stack elements in the visited frame.

stack - the operand stack types in this frame. This array must not be modified. Its content has the same format as the "local" array.

Throws:

IllegalStateException - if a frame is visited just after another one, without any instruction between the two (unless this frame is a Opcodes#F_SAME frame, in which case it is silently ignored).

visitJumpInsn

public void visitJumpInsn(int opcode,
                          org.objectweb.asm.Label label)

Store a location for LABEL event if recordLabel is enabled.

Overrides:

visitJumpInsn in class org.objectweb.asm.MethodVisitor

visitMaxs

public void visitMaxs(int maxStack,
                      int maxLocals)

Finalize the method. Generate a finally block for exceptional exit.

Overrides:

visitMaxs in class org.objectweb.asm.commons.LocalVariablesSorter

visitTypeInsn

public void visitTypeInsn(int opcode,
                          String type)

Insert logging code for NEW, ANEWARRAY, INSTANCEOF instructions.

Overrides:

visitTypeInsn in class org.objectweb.asm.MethodVisitor

visitIntInsn

public void visitIntInsn(int opcode,
                         int operand)

Insert logging code for a NEWARRAY instruction. It records the array size and a created array.

Overrides:

visitIntInsn in class org.objectweb.asm.MethodVisitor

visitMethodInsn

public void visitMethodInsn(int opcode,
                            String owner,
                            String name,
                            String desc,
                            boolean itf)

Insert logging code for INVOKE instructions.

Overrides:

visitMethodInsn in class org.objectweb.asm.MethodVisitor

visitMultiANewArrayInsn

public void visitMultiANewArrayInsn(String desc,
                                    int dims)

Insert logging code for a MultiANewArray instruction. It records a created array and its elements.

Overrides:

visitMultiANewArrayInsn in class org.objectweb.asm.MethodVisitor

visitIincInsn

public void visitIincInsn(int var,
                          int increment)

Insert logging code for an IINC instruction. It records a value after increment.

Overrides:

visitIincInsn in class org.objectweb.asm.commons.LocalVariablesSorter

visitInsn

public void visitInsn(int opcode)

Insert logging code for various instructions.

Overrides:

visitInsn in class org.objectweb.asm.MethodVisitor

visitInvokeDynamicInsn

public void visitInvokeDynamicInsn(String name,
                                   String desc,
                                   org.objectweb.asm.Handle bsm,
                                   Object... bsmArgs)

Insert logging code for INVOKEDYNAMIC instruction.

Overrides:

visitInvokeDynamicInsn in class org.objectweb.asm.MethodVisitor

visitLookupSwitchInsn

public void visitLookupSwitchInsn(org.objectweb.asm.Label dflt,
                                  int[] keys,
                                  org.objectweb.asm.Label[] labels)

No additional actions but count the number of instructions.

Overrides:

visitLookupSwitchInsn in class org.objectweb.asm.MethodVisitor

visitTableSwitchInsn

public void visitTableSwitchInsn(int min,
                                 int max,
                                 org.objectweb.asm.Label dflt,
                                 org.objectweb.asm.Label... labels)

No additional actions but count the number of instructions.

Overrides:

visitTableSwitchInsn in class org.objectweb.asm.MethodVisitor

visitLdcInsn

public void visitLdcInsn(Object cst)

Insert logging code for a Load Constant instruction in order to record the constant object.

Overrides:

visitLdcInsn in class org.objectweb.asm.MethodVisitor

visitFieldInsn

public void visitFieldInsn(int opcode,
                           String owner,
                           String name,
                           String desc)

Insert logging code for field access instruction.

Overrides:

visitFieldInsn in class org.objectweb.asm.MethodVisitor

visitVarInsn

public void visitVarInsn(int opcode,
                         int var)

Insert logging code for local variable and RET instructions.

Overrides:

visitVarInsn in class org.objectweb.asm.commons.LocalVariablesSorter