edu.umd.cs.findbugs.ba.deref

Class UnconditionalValueDerefAnalysis

java.lang.Object

edu.umd.cs.findbugs.ba.BasicAbstractDataflowAnalysis<Fact>

edu.umd.cs.findbugs.ba.AbstractDataflowAnalysis<Fact>

edu.umd.cs.findbugs.ba.BackwardDataflowAnalysis<UnconditionalValueDerefSet>

edu.umd.cs.findbugs.ba.deref.UnconditionalValueDerefAnalysis

All Implemented Interfaces:

DataflowAnalysis<UnconditionalValueDerefSet>

public class UnconditionalValueDerefAnalysis
extends BackwardDataflowAnalysis<UnconditionalValueDerefSet>

Dataflow analysis to find values unconditionally dereferenced in the future.

Author:

David Hovemeyer

Field Summary

Fields

Modifier and Type	Field and Description
static boolean	ASSUME_NONZERO_TRIP_LOOPS
static boolean	CHECK_ANNOTATIONS
static boolean	CHECK_CALLS
static boolean	DEBUG
static boolean	DEBUG_CHECK_CALLS
static boolean	IGNORE_DEREF_OF_NCP
static boolean	VERBOSE_NULLARG_DEBUG

Constructor Summary

Constructors

Constructor and Description
UnconditionalValueDerefAnalysis(ReverseDepthFirstSearch rdfs, DepthFirstSearch dfs, CFG cfg, org.apache.bcel.classfile.Method method, org.apache.bcel.generic.MethodGen methodGen, ValueNumberDataflow vnaDataflow, AssertionMethods assertionMethods) Constructor.

Method Summary

Methods

Modifier and Type	Method and Description
static java.util.Set<ValueNumber>	checkAllNonNullParams(Location location, ValueNumberFrame vnaFrame, org.apache.bcel.generic.ConstantPoolGen constantPool, org.apache.bcel.classfile.Method method, IsNullValueDataflow invDataflow, TypeDataflow typeDataflow)
static java.util.Set<ValueNumber>	checkNonNullParams(Location location, ValueNumberFrame vnaFrame, org.apache.bcel.generic.ConstantPoolGen constantPool, org.apache.bcel.classfile.Method method, IsNullValueFrame invFrame)
static java.util.Set<ValueNumber>	checkUnconditionalDerefDatabase(Location location, ValueNumberFrame vnaFrame, org.apache.bcel.generic.ConstantPoolGen constantPool, IsNullValueFrame invFrame, TypeDataflow typeDataflow)
void	clearDerefsOnNonNullBranches(IsNullValueDataflow invDataflow) HACK: use the given is-null dataflow to clear deref sets for values that are known to be definitely non-null on a branch.
void	copy(UnconditionalValueDerefSet source, UnconditionalValueDerefSet dest) Copy dataflow facts.
UnconditionalValueDerefSet	createFact() Create empty (uninitialized) dataflow facts for one program point.
int	getLastUpdateTimestamp(UnconditionalValueDerefSet fact)
void	initEntryFact(UnconditionalValueDerefSet result) Initialize the "entry" fact for the graph.
boolean	isFactValid(UnconditionalValueDerefSet fact) Determine whether the given fact is valid (neither top nor bottom).
static boolean	isNullCheck(org.apache.bcel.generic.InstructionHandle h, org.apache.bcel.generic.ConstantPoolGen cpg)
boolean	isTop(UnconditionalValueDerefSet fact) Is the given fact the top value.
void	makeFactTop(UnconditionalValueDerefSet fact) Make given fact the top value.
void	meetInto(UnconditionalValueDerefSet fact, Edge edge, UnconditionalValueDerefSet result) Meet a dataflow fact associated with an incoming edge into another fact.
void	meetInto(UnconditionalValueDerefSet fact, Edge edge, UnconditionalValueDerefSet result, boolean onlyEdge)
static boolean	reportPotentialDereference(Location location, IsNullValueFrame invFrame)
boolean	same(UnconditionalValueDerefSet fact1, UnconditionalValueDerefSet fact2) Are given dataflow facts the same?
void	setLastUpdateTimestamp(UnconditionalValueDerefSet fact, int lastUpdate)
void	setTypeDataflow(TypeDataflow typeDataflow)
void	startIteration() Called before beginning an iteration of analysis.
java.lang.String	toString()
void	transferInstruction(org.apache.bcel.generic.InstructionHandle handle, BasicBlock basicBlock, UnconditionalValueDerefSet fact) Transfer function for a single instruction.

Methods inherited from class edu.umd.cs.findbugs.ba.BackwardDataflowAnalysis

getBlockOrder, getReverseDepthFirstSearch, isForwards

Methods inherited from class edu.umd.cs.findbugs.ba.AbstractDataflowAnalysis

getFactAfterLocation, getFactAtLocation, transfer

Methods inherited from class edu.umd.cs.findbugs.ba.BasicAbstractDataflowAnalysis

edgeTransfer, factToString, finishIteration, getFactOnEdge, getResultFact, getStartFact, resultFactIterator

Methods inherited from class java.lang.Object

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

Field Detail

DEBUG

public static final boolean DEBUG

ASSUME_NONZERO_TRIP_LOOPS

public static final boolean ASSUME_NONZERO_TRIP_LOOPS

IGNORE_DEREF_OF_NCP

public static final boolean IGNORE_DEREF_OF_NCP

CHECK_ANNOTATIONS

public static final boolean CHECK_ANNOTATIONS

CHECK_CALLS

public static final boolean CHECK_CALLS

DEBUG_CHECK_CALLS

public static final boolean DEBUG_CHECK_CALLS

VERBOSE_NULLARG_DEBUG

public static final boolean VERBOSE_NULLARG_DEBUG

Constructor Detail

UnconditionalValueDerefAnalysis

public UnconditionalValueDerefAnalysis(ReverseDepthFirstSearch rdfs,
                               DepthFirstSearch dfs,
                               CFG cfg,
                               org.apache.bcel.classfile.Method method,
                               org.apache.bcel.generic.MethodGen methodGen,
                               ValueNumberDataflow vnaDataflow,
                               AssertionMethods assertionMethods)

Constructor.

Parameters:

rdfs - the reverse depth-first-search (for the block order)

cfg - the CFG for the method

methodGen - the MethodGen for the method

vnaDataflow -

assertionMethods - AssertionMethods for the analyzed class

Method Detail

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

clearDerefsOnNonNullBranches

public void clearDerefsOnNonNullBranches(IsNullValueDataflow invDataflow)

HACK: use the given is-null dataflow to clear deref sets for values that are known to be definitely non-null on a branch.

Parameters:

invDataflow - the IsNullValueDataflow to use

setTypeDataflow

public void setTypeDataflow(TypeDataflow typeDataflow)

isFactValid

public boolean isFactValid(UnconditionalValueDerefSet fact)

Description copied from class: AbstractDataflowAnalysis

Determine whether the given fact is valid (neither top nor bottom).

Specified by:

isFactValid in class AbstractDataflowAnalysis<UnconditionalValueDerefSet>

isNullCheck

public static boolean isNullCheck(org.apache.bcel.generic.InstructionHandle h,
                  org.apache.bcel.generic.ConstantPoolGen cpg)

reportPotentialDereference

public static boolean reportPotentialDereference(Location location,
                                 IsNullValueFrame invFrame)
                                          throws DataflowAnalysisException

Throws:

DataflowAnalysisException

transferInstruction

public void transferInstruction(org.apache.bcel.generic.InstructionHandle handle,
                       BasicBlock basicBlock,
                       UnconditionalValueDerefSet fact)
                         throws DataflowAnalysisException

Description copied from class: AbstractDataflowAnalysis

Transfer function for a single instruction.

Specified by:

transferInstruction in class AbstractDataflowAnalysis<UnconditionalValueDerefSet>

Parameters:

handle - the instruction

basicBlock - the BasicBlock containing the instruction; needed to disambiguate instructions in inlined JSR subroutines

fact - which should be modified based on the instruction

Throws:

DataflowAnalysisException

checkUnconditionalDerefDatabase

public static java.util.Set<ValueNumber> checkUnconditionalDerefDatabase(Location location,
                                                         ValueNumberFrame vnaFrame,
                                                         org.apache.bcel.generic.ConstantPoolGen constantPool,
                                                         @CheckForNull
                                                         IsNullValueFrame invFrame,
                                                         TypeDataflow typeDataflow)
                                                                  throws DataflowAnalysisException

Throws:

DataflowAnalysisException

checkAllNonNullParams

public static java.util.Set<ValueNumber> checkAllNonNullParams(Location location,
                                               ValueNumberFrame vnaFrame,
                                               org.apache.bcel.generic.ConstantPoolGen constantPool,
                                               @CheckForNull
                                               org.apache.bcel.classfile.Method method,
                                               @CheckForNull
                                               IsNullValueDataflow invDataflow,
                                               TypeDataflow typeDataflow)
                                                        throws DataflowAnalysisException

Throws:

DataflowAnalysisException

checkNonNullParams

public static java.util.Set<ValueNumber> checkNonNullParams(Location location,
                                            ValueNumberFrame vnaFrame,
                                            org.apache.bcel.generic.ConstantPoolGen constantPool,
                                            @CheckForNull
                                            org.apache.bcel.classfile.Method method,
                                            @CheckForNull
                                            IsNullValueFrame invFrame)
                                                     throws DataflowAnalysisException

Throws:

DataflowAnalysisException

copy

public void copy(UnconditionalValueDerefSet source,
        UnconditionalValueDerefSet dest)

Description copied from interface: DataflowAnalysis

Copy dataflow facts.

createFact

public UnconditionalValueDerefSet createFact()

Description copied from interface: DataflowAnalysis

Create empty (uninitialized) dataflow facts for one program point. A valid value will be copied into it before it is used.

initEntryFact

public void initEntryFact(UnconditionalValueDerefSet result)
                   throws DataflowAnalysisException

Description copied from interface: DataflowAnalysis

Initialize the "entry" fact for the graph.

Throws:

DataflowAnalysisException

makeFactTop

public void makeFactTop(UnconditionalValueDerefSet fact)

Description copied from interface: DataflowAnalysis

Make given fact the top value.

isTop

public boolean isTop(UnconditionalValueDerefSet fact)

Description copied from interface: DataflowAnalysis

Is the given fact the top value.

meetInto

public void meetInto(UnconditionalValueDerefSet fact,
            Edge edge,
            UnconditionalValueDerefSet result)
              throws DataflowAnalysisException

Description copied from interface: DataflowAnalysis

Meet a dataflow fact associated with an incoming edge into another fact. This is used to determine the start fact for a basic block.

Parameters:

fact - the predecessor fact (incoming edge)

edge - the edge from the predecessor

result - the result fact

Throws:

DataflowAnalysisException

meetInto

public void meetInto(UnconditionalValueDerefSet fact,
            Edge edge,
            UnconditionalValueDerefSet result,
            boolean onlyEdge)

same

public boolean same(UnconditionalValueDerefSet fact1,
           UnconditionalValueDerefSet fact2)

Description copied from interface: DataflowAnalysis

Are given dataflow facts the same?

startIteration

public void startIteration()

Description copied from interface: DataflowAnalysis

Called before beginning an iteration of analysis. Each iteration visits every basic block in the CFG.

Specified by:

startIteration in interface DataflowAnalysis<UnconditionalValueDerefSet>

Overrides:

startIteration in class BasicAbstractDataflowAnalysis<UnconditionalValueDerefSet>

getLastUpdateTimestamp

public int getLastUpdateTimestamp(UnconditionalValueDerefSet fact)

Specified by:

getLastUpdateTimestamp in interface DataflowAnalysis<UnconditionalValueDerefSet>

Overrides:

getLastUpdateTimestamp in class BasicAbstractDataflowAnalysis<UnconditionalValueDerefSet>

setLastUpdateTimestamp

public void setLastUpdateTimestamp(UnconditionalValueDerefSet fact,
                          int lastUpdate)

Specified by:

setLastUpdateTimestamp in interface DataflowAnalysis<UnconditionalValueDerefSet>

Overrides:

setLastUpdateTimestamp in class BasicAbstractDataflowAnalysis<UnconditionalValueDerefSet>