edu.umd.cs.findbugs

Class OpcodeStack

java.lang.Object

edu.umd.cs.findbugs.OpcodeStack

public class OpcodeStack
extends java.lang.Object

tracks the types and numbers of objects that are currently on the operand stack throughout the execution of method. To use, a detector should instantiate one for each method, and call

stack.sawOpcode(this,seen);

at the bottom of their sawOpcode method. at any point you can then inspect the stack and see what the types of objects are on the stack, including constant values if they were pushed. The types described are of course, only the static types. There are some outstanding opcodes that have yet to be implemented, I couldn't find any code that actually generated these, so i didn't put them in because I couldn't test them:

• dup2_x2
• jsr_w
• wide

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	OpcodeStack.CustomUserValue You can put this annotation on a OpcodeStack detector to indicate that it uses OpcodeStack.Item.userValue, and thus should not reuse generic OpcodeStack information from an iterative evaluation of the opcode stack.
static class	OpcodeStack.Item
static class	OpcodeStack.JumpInfo
static class	OpcodeStack.JumpInfoFactory

Constructor Summary

Constructors

Constructor and Description
OpcodeStack()

Method Summary

Modifier and Type	Method and Description
void	clear()
static java.lang.String	getExceptionSig(DismantleBytecode dbc, org.apache.bcel.classfile.CodeException e)
OpcodeStack.Item	getItemMethodInvokedOn(DismantleBytecode dbc)
int	getLastUpdate(int reg)
OpcodeStack.Item	getLVValue(int index)
int	getNumLastUpdates()
int	getNumLocalValues()
int	getStackDepth()
OpcodeStack.Item	getStackItem(int stackOffset)
boolean	hasIncomingBranches(int pc)
void	initialize()
protected boolean	isJumpInfoChangedByNewTarget()
boolean	isJumpTarget(int pc)
boolean	isTop()
void	learnFrom(OpcodeStack.JumpInfo info)
void	mergeJumps(DismantleBytecode dbc)
void	precomputation(DismantleBytecode dbc)
void	printJumpEntries()
void	replace(int stackOffset, OpcodeStack.Item value)
void	replaceTop(OpcodeStack.Item newTop)
int	resetForMethodEntry(DismantleBytecode visitor)
void	sawOpcode(DismantleBytecode dbc, int seen)
void	setJumpInfoChangedByBackwardBranch(java.lang.String kind, int from, int to)
protected void	setJumpInfoChangedByNewTarget()
java.lang.String	toString()

Methods inherited from class java.lang.Object

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

Constructor Detail

OpcodeStack

public OpcodeStack()

Method Detail

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

hasIncomingBranches

public boolean hasIncomingBranches(int pc)

getExceptionSig

public static java.lang.String getExceptionSig(DismantleBytecode dbc,
                                               org.apache.bcel.classfile.CodeException e)

mergeJumps

public void mergeJumps(DismantleBytecode dbc)

getLastUpdate

public int getLastUpdate(int reg)

getNumLastUpdates

public int getNumLastUpdates()

sawOpcode

public void sawOpcode(DismantleBytecode dbc,
                      int seen)

precomputation

public void precomputation(DismantleBytecode dbc)

clear

public void clear()

printJumpEntries

public void printJumpEntries()

isJumpTarget

public boolean isJumpTarget(int pc)

learnFrom

public void learnFrom(OpcodeStack.JumpInfo info)

initialize

public void initialize()

resetForMethodEntry

public int resetForMethodEntry(DismantleBytecode visitor)

setJumpInfoChangedByBackwardBranch

public void setJumpInfoChangedByBackwardBranch(java.lang.String kind,
                                               int from,
                                               int to)

getStackDepth

public int getStackDepth()

getStackItem

public OpcodeStack.Item getStackItem(int stackOffset)

replace

public void replace(int stackOffset,
                    OpcodeStack.Item value)

replaceTop

public void replaceTop(OpcodeStack.Item newTop)

getItemMethodInvokedOn

public OpcodeStack.Item getItemMethodInvokedOn(DismantleBytecode dbc)

getLVValue

@Nonnull
public OpcodeStack.Item getLVValue(int index)

getNumLocalValues

public int getNumLocalValues()

isTop

public boolean isTop()

isJumpInfoChangedByNewTarget

protected boolean isJumpInfoChangedByNewTarget()

Returns:

Returns the jumpInfoChangedByNewTarget.

setJumpInfoChangedByNewTarget

protected void setJumpInfoChangedByNewTarget()