FindBugs™ 1.3.9

edu.umd.cs.findbugs.ba.npe
Class IsNullValueAnalysis

java.lang.Object
  extended by edu.umd.cs.findbugs.ba.BasicAbstractDataflowAnalysis<Fact>
      extended by edu.umd.cs.findbugs.ba.AbstractDataflowAnalysis<Fact>
          extended by edu.umd.cs.findbugs.ba.ForwardDataflowAnalysis<FrameType>
              extended by edu.umd.cs.findbugs.ba.FrameDataflowAnalysis<IsNullValue,IsNullValueFrame>
                  extended by edu.umd.cs.findbugs.ba.npe.IsNullValueAnalysis
All Implemented Interfaces:
DataflowAnalysis<IsNullValueFrame>, EdgeTypes, IsNullValueAnalysisFeatures

public class IsNullValueAnalysis
extends FrameDataflowAnalysis<IsNullValue,IsNullValueFrame>
implements EdgeTypes, IsNullValueAnalysisFeatures

A dataflow analysis to detect potential null pointer dereferences.

Author:
David Hovemeyer
See Also:
IsNullValue, IsNullValueFrame, IsNullValueFrameModelingVisitor

Nested Class Summary
static class IsNullValueAnalysis.PointerEqualityCheck
           
 
Field Summary
 
Fields inherited from interface edu.umd.cs.findbugs.ba.EdgeTypes
BACKEDGE_SOURCE_EDGE, BACKEDGE_TARGET_EDGE, CHECKED_EXCEPTIONS_FLAG, EXIT_EDGE, EXPLICIT_EXCEPTIONS_FLAG, FALL_THROUGH_EDGE, GOTO_EDGE, HANDLED_EXCEPTION_EDGE, IFCMP_EDGE, JSR_EDGE, RET_EDGE, RETURN_EDGE, START_EDGE, SWITCH_DEFAULT_EDGE, SWITCH_EDGE, UNHANDLED_EXCEPTION_EDGE, UNKNOWN_EDGE
 
Fields inherited from interface edu.umd.cs.findbugs.ba.npe.IsNullValueAnalysisFeatures
NCP_EXTRA_BRANCH, NO_SPLIT_DOWNGRADE_NSP, NO_SWITCH_DEFAULT_AS_EXCEPTION, UNKNOWN_VALUES_ARE_NSP, USE_TYPE_QUALIFIERS
 
Constructor Summary
IsNullValueAnalysis(MethodDescriptor descriptor, org.apache.bcel.generic.MethodGen methodGen, CFG cfg, ValueNumberDataflow vnaDataflow, TypeDataflow typeDataflow, DepthFirstSearch dfs, AssertionMethods assertionMethods)
           
 
Method Summary
 void addLocationWhereValueBecomesNull(LocationWhereValueBecomesNull locationWhereValueBecomesNull)
           
 IsNullValueFrame createFact()
          Create empty (uninitialized) dataflow facts for one program point.
 void endTransfer(BasicBlock basicBlock, org.apache.bcel.generic.InstructionHandle end, IsNullValueFrame result)
           
 JavaClassAndMethod getClassAndMethod()
           
 IsNullValueFrame getFactAtMidEdge(Edge edge)
           
static IsNullValueAnalysis.PointerEqualityCheck getForPointerEqualityCheck(CFG cfg, ValueNumberDataflow vna)
           
 java.util.Set<LocationWhereValueBecomesNull> getLocationWhereValueBecomesNullSet()
           
 void initEntryFact(IsNullValueFrame result)
          Initialize the "entry" fact for the graph.
 void meetInto(IsNullValueFrame fact, Edge edge, IsNullValueFrame result)
          Meet a dataflow fact associated with an incoming edge into another fact.
 void meetInto(IsNullValueFrame fact, Edge edge, IsNullValueFrame result, boolean propagatePhiNodeInformation)
           
protected  void mergeInto(IsNullValueFrame other, IsNullValueFrame result)
          Merge one frame into another.
protected  void mergeValues(IsNullValueFrame otherFrame, IsNullValueFrame resultFrame, int slot)
          Merge the values contained in a given slot of two Frames.
 void setClassAndMethod(JavaClassAndMethod classAndMethod)
           
 void startIteration()
          Called before beginning an iteration of analysis.
 void startTransfer()
           
 void transfer(BasicBlock basicBlock, org.apache.bcel.generic.InstructionHandle end, IsNullValueFrame start, IsNullValueFrame result)
          Transfer function for the analysis.
 void transferInstruction(org.apache.bcel.generic.InstructionHandle handle, BasicBlock basicBlock, IsNullValueFrame fact)
          Transfer function for a single instruction.
 
Methods inherited from class edu.umd.cs.findbugs.ba.FrameDataflowAnalysis
copy, getLastUpdateTimestamp, isFactValid, isTop, makeFactTop, modifyFrame, same, setLastUpdateTimestamp
 
Methods inherited from class edu.umd.cs.findbugs.ba.ForwardDataflowAnalysis
getBlockOrder, getDepthFirstSearch, isForwards
 
Methods inherited from class edu.umd.cs.findbugs.ba.AbstractDataflowAnalysis
getFactAfterLocation, getFactAtLocation
 
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, toString, wait, wait, wait
 

Constructor Detail

IsNullValueAnalysis

public IsNullValueAnalysis(MethodDescriptor descriptor,
                           org.apache.bcel.generic.MethodGen methodGen,
                           CFG cfg,
                           ValueNumberDataflow vnaDataflow,
                           TypeDataflow typeDataflow,
                           DepthFirstSearch dfs,
                           AssertionMethods assertionMethods)
Method Detail

getForPointerEqualityCheck

@CheckForNull
public static IsNullValueAnalysis.PointerEqualityCheck getForPointerEqualityCheck(CFG cfg,
                                                                                               ValueNumberDataflow vna)

setClassAndMethod

public void setClassAndMethod(JavaClassAndMethod classAndMethod)

getClassAndMethod

public JavaClassAndMethod getClassAndMethod()

createFact

public IsNullValueFrame 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.

Specified by:
createFact in interface DataflowAnalysis<IsNullValueFrame>

initEntryFact

public void initEntryFact(IsNullValueFrame result)
Description copied from interface: DataflowAnalysis
Initialize the "entry" fact for the graph.

Specified by:
initEntryFact in interface DataflowAnalysis<IsNullValueFrame>

transfer

public void transfer(BasicBlock basicBlock,
                     @CheckForNull
                     org.apache.bcel.generic.InstructionHandle end,
                     IsNullValueFrame start,
                     IsNullValueFrame result)
              throws DataflowAnalysisException
Description copied from interface: DataflowAnalysis
Transfer function for the analysis. Taking dataflow facts at start (which might be either the entry or exit of the block, depending on whether the analysis is forwards or backwards), modify result to be the facts at the other end of the block.

Specified by:
transfer in interface DataflowAnalysis<IsNullValueFrame>
Overrides:
transfer in class AbstractDataflowAnalysis<IsNullValueFrame>
Parameters:
basicBlock - the basic block
end - if nonnull, stop before considering this instruction; otherwise, consider all of the instructions in the basic block
start - dataflow facts at beginning of block (if forward analysis) or end of block (if backwards analysis)
result - resulting dataflow facts at other end of block
Throws:
DataflowAnalysisException

startTransfer

public void startTransfer()
                   throws DataflowAnalysisException
Throws:
DataflowAnalysisException

endTransfer

public void endTransfer(BasicBlock basicBlock,
                        @CheckForNull
                        org.apache.bcel.generic.InstructionHandle end,
                        IsNullValueFrame result)
                 throws DataflowAnalysisException
Throws:
DataflowAnalysisException

transferInstruction

public void transferInstruction(org.apache.bcel.generic.InstructionHandle handle,
                                BasicBlock basicBlock,
                                IsNullValueFrame fact)
                         throws DataflowAnalysisException
Description copied from class: AbstractDataflowAnalysis
Transfer function for a single instruction.

Specified by:
transferInstruction in class AbstractDataflowAnalysis<IsNullValueFrame>
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

meetInto

public void meetInto(IsNullValueFrame fact,
                     Edge edge,
                     IsNullValueFrame 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.

Specified by:
meetInto in interface DataflowAnalysis<IsNullValueFrame>
Parameters:
fact - the predecessor fact (incoming edge)
edge - the edge from the predecessor
result - the result fact
Throws:
DataflowAnalysisException

meetInto

public void meetInto(IsNullValueFrame fact,
                     Edge edge,
                     IsNullValueFrame result,
                     boolean propagatePhiNodeInformation)
              throws DataflowAnalysisException
Throws:
DataflowAnalysisException

mergeInto

protected void mergeInto(IsNullValueFrame other,
                         IsNullValueFrame result)
                  throws DataflowAnalysisException
Description copied from class: FrameDataflowAnalysis
Merge one frame into another.

Overrides:
mergeInto in class FrameDataflowAnalysis<IsNullValue,IsNullValueFrame>
Parameters:
other - the frame to merge with the result
result - the result frame, which is modified to be the merge of the two frames
Throws:
DataflowAnalysisException

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<IsNullValueFrame>
Overrides:
startIteration in class BasicAbstractDataflowAnalysis<IsNullValueFrame>

addLocationWhereValueBecomesNull

public void addLocationWhereValueBecomesNull(LocationWhereValueBecomesNull locationWhereValueBecomesNull)

getLocationWhereValueBecomesNullSet

public java.util.Set<LocationWhereValueBecomesNull> getLocationWhereValueBecomesNullSet()

mergeValues

protected void mergeValues(IsNullValueFrame otherFrame,
                           IsNullValueFrame resultFrame,
                           int slot)
                    throws DataflowAnalysisException
Description copied from class: FrameDataflowAnalysis
Merge the values contained in a given slot of two Frames.

Specified by:
mergeValues in class FrameDataflowAnalysis<IsNullValue,IsNullValueFrame>
Parameters:
otherFrame - a Frame
resultFrame - a Frame which will contain the resulting merged value
slot - a slot in both frames
Throws:
DataflowAnalysisException

getFactAtMidEdge

public IsNullValueFrame getFactAtMidEdge(Edge edge)
                                  throws DataflowAnalysisException
Throws:
DataflowAnalysisException

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