gov.nasa.jpf.vm

Class Instruction

java.lang.Object

gov.nasa.jpf.vm.Instruction

All Implemented Interfaces:

Attributable, InstructionInterface, java.lang.Cloneable

Direct Known Subclasses:

ACONST_NULL, ArrayElementInstruction, ARRAYLENGTH, ATHROW, BIPUSH, CHECKCAST, D2F, D2I, D2L, DADD, DCONST, DDIV, DMUL, DNEG, DoubleCompareInstruction, DREM, DSUB, DUP, DUP_X1, DUP_X2, DUP2, DUP2_X1, DUP2_X2, EXECUTENATIVE, F2D, F2I, F2L, FADD, FCMPG, FCMPL, FCONST, FDIV, FieldInstruction, FINISHCLINIT, FMUL, FNEG, FREM, FSUB, GOTO, I2B, I2C, I2D, I2F, I2L, I2S, IADD, IAND, ICONST, IDIV, IfInstruction, IINC, IMUL, INEG, INSTANCEOF, INVOKECG, INVOKEDYNAMIC, InvokeInstruction, IOR, IREM, ISHL, ISHR, ISUB, IUSHR, IXOR, JSR, JSR_W, JVMLocalVariableInstruction, L2D, L2F, L2I, LADD, LAND, LCMP, LCONST, LDC, LDC2_W, LDIV, LMUL, LNEG, LockInstruction, LOR, LREM, LSHL, LSHR, LSUB, LUSHR, LXOR, MULTIANEWARRAY, NewInstruction, NOP, POP, POP2, RET, ReturnInstruction, RUNSTART, SIPUSH, SWAP, SwitchInstruction, WIDE

public abstract class Instruction
extends java.lang.Object
implements java.lang.Cloneable, InstructionInterface

common root of all JPF bytecode instruction classes

Field Summary

Fields

Modifier and Type	Field and Description
protected java.lang.Object	attr
protected int	insnIndex
protected MethodInfo	mi
protected int	position

Constructor Summary

Constructors

Constructor and Description
Instruction()

Method Summary

Modifier and Type	Method and Description
void	addAttr(java.lang.Object a)
Instruction	asInstruction() this is for cases where we need the Instruction type.
ObjectList.Iterator	attrIterator()
<T> ObjectList.TypedIterator<T>	attrIterator(java.lang.Class<T> attrType)
void	cleanupTransients() this method can be overridden if instruction classes have to store information for instructionExecuted() notifications, and this information should not be stored persistent to avoid memory leaks (e.g.
abstract Instruction	execute(ThreadInfo ti) this is the real workhorse returns next instruction to enter in this thread <2do> it's unfortunate we roll every side effect into this method, because it diminishes the value of the 'executeInstruction' notification: all insns that require some sort of late binding (InvokeVirtual, GetField, ..) are not yet fully analyzable (e.g.
java.lang.Object	getAttr() this returns all of them - use either if you know there will be only one attribute at a time, or check/process result with ObjectList
<T> T	getAttr(java.lang.Class<T> attrType) this only returns the first attr of this type, there can be more if you don't use client private types or the provided type is too general
java.lang.String	getFileLocation() this returns a "pathname:line" string
java.lang.String	getFilePos() this returns a "filename:line" string
int	getInstructionIndex()
int	getLength() return the length in bytes of this instruction.
int	getLineNumber()
MethodInfo	getMethodInfo()
java.lang.String	getMnemonic()
Instruction	getNext() this returns the instruction at the following code insnIndex within the same method, which might or might not be the next one to enter (branches, overlay calls etc.).
Instruction	getNext(ThreadInfo ti) this is returning the next Instruction to enter, to be called to obtain the return value of enter() if this is not a branch insn Be aware of that we might have had exceptions caused by our execution (-> lower frame), or we might have had overlaid calls (-> higher frame), i.e.
<T> T	getNextAttr(java.lang.Class<T> attrType, java.lang.Object prev)
int	getPosition()
Instruction	getPrev()
java.lang.String	getSourceLine()
java.lang.String	getSourceLocation() this returns a "class.method(line)" string
java.lang.String	getSourceOrLocation() this is for debugging/logging if we always want something back telling us where this insn came from
boolean	hasAttr()
boolean	hasAttr(java.lang.Class<?> attrType)
void	init(MethodInfo mi, int offset, int position)
boolean	isBackJump() answer if this is a potential loop closing jump
boolean	isCompleted(ThreadInfo ti) this is for listeners that process instructionExecuted(), but need to determine if there was a CG registration, an overlayed direct call (like clinit) etc.
boolean	isExtendedInstruction() is this one of our own, artificial insns?
boolean	isFirstInstruction() is this the first instruction in a method
boolean	isMonitorEnterPrologue() is this instruction part of a monitorenter code pattern
boolean	isSchedulingRelevant(SystemState ss, KernelState ks, ThreadInfo ti)
void	removeAttr(java.lang.Object a)
void	replaceAttr(java.lang.Object oldAttr, java.lang.Object newAttr)
boolean	requiresClinitExecution(ThreadInfo ti, ClassInfo ci) this is a misnomer - we actually push the clinit calls here in case we need some.
void	setAttr(java.lang.Object a) this replaces all of them - use only if you know - there will be only one attribute at a time - you obtained the value you set by a previous getXAttr() - you constructed a multi value list with ObjectList.createList()
void	setContext(java.lang.String className, java.lang.String methodName, int lineNumber, int offset)
void	setLocation(int insnIdx, int pos)
void	setMethodInfo(MethodInfo mi) that's used for explicit construction of MethodInfos (synthetic methods)
java.lang.String	toPostExecString() this can contain additional info that was gathered/cached during execution
java.lang.String	toString()
Instruction	typeSafeClone(MethodInfo mi) this is overridden by any Instruction that use a cache for class or method to provide a type safe cloning

Methods inherited from class java.lang.Object

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

Methods inherited from interface gov.nasa.jpf.vm.bytecode.InstructionInterface

getByteCode

Field Detail

insnIndex

protected int insnIndex

position

protected int position

mi

protected MethodInfo mi

attr

protected java.lang.Object attr

Constructor Detail

Instruction

public Instruction()

Method Detail

asInstruction

public Instruction asInstruction()

Description copied from interface: InstructionInterface

this is for cases where we need the Instruction type. Try to use InstructionInterface in clients

Specified by:

asInstruction in interface InstructionInterface

setContext

public void setContext(java.lang.String className,
                       java.lang.String methodName,
                       int lineNumber,
                       int offset)

isFirstInstruction

public boolean isFirstInstruction()

is this the first instruction in a method

Specified by:

isFirstInstruction in interface InstructionInterface

isBackJump

public boolean isBackJump()

answer if this is a potential loop closing jump

Specified by:

isBackJump in interface InstructionInterface

isMonitorEnterPrologue

public boolean isMonitorEnterPrologue()

is this instruction part of a monitorenter code pattern

isExtendedInstruction

public boolean isExtendedInstruction()

is this one of our own, artificial insns?

Specified by:

isExtendedInstruction in interface InstructionInterface

getMethodInfo

public MethodInfo getMethodInfo()

Specified by:

getMethodInfo in interface InstructionInterface

setMethodInfo

public void setMethodInfo(MethodInfo mi)

that's used for explicit construction of MethodInfos (synthetic methods)

getNext

public Instruction getNext()

this returns the instruction at the following code insnIndex within the same method, which might or might not be the next one to enter (branches, overlay calls etc.).

Specified by:

getNext in interface InstructionInterface

getInstructionIndex

public int getInstructionIndex()

Specified by:

getInstructionIndex in interface InstructionInterface

getPosition

public int getPosition()

Specified by:

getPosition in interface InstructionInterface

setLocation

public void setLocation(int insnIdx,
                        int pos)

getLength

public int getLength()

return the length in bytes of this instruction. override if this is not 1

Specified by:

getLength in interface InstructionInterface

getPrev

public Instruction getPrev()

Specified by:

getPrev in interface InstructionInterface

isCompleted

public boolean isCompleted(ThreadInfo ti)

this is for listeners that process instructionExecuted(), but need to determine if there was a CG registration, an overlayed direct call (like clinit) etc. The easy case is the instruction not having been executed yet, in which case ti.getNextPC() == null There are two cases for re-execution: either nextPC was set to the same insn (which is what CG creators usually use), or somebody just pushed another stackframe that executes something which will return to the same insn (that is what automatic calls and the like do - we call it overlays)

Specified by:

isCompleted in interface InstructionInterface

cleanupTransients

public void cleanupTransients()

this method can be overridden if instruction classes have to store information for instructionExecuted() notifications, and this information should not be stored persistent to avoid memory leaks (e.g. via traces). Called by ThreadInfo.executeInstruction

isSchedulingRelevant

public boolean isSchedulingRelevant(SystemState ss,
                                    KernelState ks,
                                    ThreadInfo ti)

execute

public abstract Instruction execute(ThreadInfo ti)

this is the real workhorse returns next instruction to enter in this thread <2do> it's unfortunate we roll every side effect into this method, because it diminishes the value of the 'executeInstruction' notification: all insns that require some sort of late binding (InvokeVirtual, GetField, ..) are not yet fully analyzable (e.g. the callee of InvokeVirtuals is not known yet), putting the burden of duplicating the related code of enter() in the listener. It would be better if we factor this 'prepareExecution' out of enter()

Specified by:

execute in interface InstructionInterface

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

toPostExecString

public java.lang.String toPostExecString()

this can contain additional info that was gathered/cached during execution

Specified by:

toPostExecString in interface InstructionInterface

getMnemonic

public java.lang.String getMnemonic()

Specified by:

getMnemonic in interface InstructionInterface

getLineNumber

public int getLineNumber()

Specified by:

getLineNumber in interface InstructionInterface

getSourceLine

public java.lang.String getSourceLine()

Specified by:

getSourceLine in interface InstructionInterface

getSourceOrLocation

public java.lang.String getSourceOrLocation()

this is for debugging/logging if we always want something back telling us where this insn came from

getFileLocation

public java.lang.String getFileLocation()

this returns a "pathname:line" string

Specified by:

getFileLocation in interface InstructionInterface

getFilePos

public java.lang.String getFilePos()

this returns a "filename:line" string

Specified by:

getFilePos in interface InstructionInterface

getSourceLocation

public java.lang.String getSourceLocation()

this returns a "class.method(line)" string

Specified by:

getSourceLocation in interface InstructionInterface

init

public void init(MethodInfo mi,
                 int offset,
                 int position)

requiresClinitExecution

public boolean requiresClinitExecution(ThreadInfo ti,
                                       ClassInfo ci)

this is a misnomer - we actually push the clinit calls here in case we need some. 'causedClinitCalls' might be more appropriate, but it is used in a number of external projects

getNext

public Instruction getNext(ThreadInfo ti)

this is returning the next Instruction to enter, to be called to obtain the return value of enter() if this is not a branch insn Be aware of that we might have had exceptions caused by our execution (-> lower frame), or we might have had overlaid calls (-> higher frame), i.e. we can't simply assume it's the following insn. We have to acquire this through the top frame of the ThreadInfo. note: the System.exit() problem should be gone, now that it is implemented as ThreadInfo state (TERMINATED), rather than purged stacks

Specified by:

getNext in interface InstructionInterface

hasAttr

public boolean hasAttr()

Specified by:

hasAttr in interface Attributable

hasAttr

public boolean hasAttr(java.lang.Class<?> attrType)

Specified by:

hasAttr in interface Attributable

getAttr

public java.lang.Object getAttr()

this returns all of them - use either if you know there will be only one attribute at a time, or check/process result with ObjectList

Specified by:

getAttr in interface Attributable

setAttr

public void setAttr(java.lang.Object a)

this replaces all of them - use only if you know - there will be only one attribute at a time - you obtained the value you set by a previous getXAttr() - you constructed a multi value list with ObjectList.createList()

Specified by:

setAttr in interface Attributable

addAttr

public void addAttr(java.lang.Object a)

Specified by:

addAttr in interface Attributable

removeAttr

public void removeAttr(java.lang.Object a)

Specified by:

removeAttr in interface Attributable

replaceAttr

public void replaceAttr(java.lang.Object oldAttr,
                        java.lang.Object newAttr)

Specified by:

replaceAttr in interface Attributable

getAttr

public <T> T getAttr(java.lang.Class<T> attrType)

this only returns the first attr of this type, there can be more if you don't use client private types or the provided type is too general

Specified by:

getAttr in interface Attributable

getNextAttr

public <T> T getNextAttr(java.lang.Class<T> attrType,
                         java.lang.Object prev)

Specified by:

getNextAttr in interface Attributable

attrIterator

public ObjectList.Iterator attrIterator()

Specified by:

attrIterator in interface Attributable

attrIterator

public <T> ObjectList.TypedIterator<T> attrIterator(java.lang.Class<T> attrType)

Specified by:

attrIterator in interface Attributable

typeSafeClone

public Instruction typeSafeClone(MethodInfo mi)

this is overridden by any Instruction that use a cache for class or method to provide a type safe cloning