Package edu.umd.cs.findbugs.ba.npe2
Class DefinitelyNullSetAnalysis
- java.lang.Object
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- edu.umd.cs.findbugs.ba.BasicAbstractDataflowAnalysis<Fact>
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- edu.umd.cs.findbugs.ba.AbstractDataflowAnalysis<Fact>
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- edu.umd.cs.findbugs.ba.ForwardDataflowAnalysis<DefinitelyNullSet>
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- edu.umd.cs.findbugs.ba.npe2.DefinitelyNullSetAnalysis
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- All Implemented Interfaces:
DataflowAnalysis<DefinitelyNullSet>
public class DefinitelyNullSetAnalysis extends ForwardDataflowAnalysis<DefinitelyNullSet>
A simple null-pointer analysis that keeps track of which value numbers are definitely known to be null.- Author:
- David Hovemeyer
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Constructor Summary
Constructors Constructor Description DefinitelyNullSetAnalysis(DepthFirstSearch dfs, ValueNumberDataflow vnaDataflow, CompactLocationNumbering compactLocationNumbering)
Constructor.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description void
copy(DefinitelyNullSet source, DefinitelyNullSet dest)
Copy dataflow facts.DefinitelyNullSet
createFact()
Create empty (uninitialized) dataflow facts for one program point.void
edgeTransfer(Edge edge, DefinitelyNullSet fact)
Edge transfer function.void
initEntryFact(DefinitelyNullSet result)
Initialize the "entry" fact for the graph.boolean
isFactValid(DefinitelyNullSet fact)
Determine whether the given fact is valid (neither top nor bottom).boolean
isTop(DefinitelyNullSet fact)
Is the given fact the top value.void
makeFactTop(DefinitelyNullSet fact)
Make given fact the top value.void
meetInto(DefinitelyNullSet fact, Edge edge, DefinitelyNullSet result)
Meet a dataflow fact associated with an incoming edge into another fact.boolean
same(DefinitelyNullSet fact1, DefinitelyNullSet fact2)
Are given dataflow facts the same?void
transferInstruction(org.apache.bcel.generic.InstructionHandle handle, BasicBlock basicBlock, DefinitelyNullSet fact)
Transfer function for a single instruction.-
Methods inherited from class edu.umd.cs.findbugs.ba.ForwardDataflowAnalysis
getBlockOrder, getDepthFirstSearch, isForwards
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Methods inherited from class edu.umd.cs.findbugs.ba.AbstractDataflowAnalysis
getFactAfterLocation, getFactAtLocation, transfer
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Methods inherited from class edu.umd.cs.findbugs.ba.BasicAbstractDataflowAnalysis
factToString, finishIteration, getFactOnEdge, getLastUpdateTimestamp, getResultFact, getStartFact, resultFactIterator, setLastUpdateTimestamp, startIteration
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Constructor Detail
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DefinitelyNullSetAnalysis
public DefinitelyNullSetAnalysis(DepthFirstSearch dfs, ValueNumberDataflow vnaDataflow, CompactLocationNumbering compactLocationNumbering)
Constructor.- Parameters:
dfs
- DepthFirstSearch for the methodvnaDataflow
- value number dataflow for the methodcompactLocationNumbering
- CompactLocationNumbering for the method
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Method Detail
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isFactValid
public boolean isFactValid(DefinitelyNullSet fact)
Description copied from class:AbstractDataflowAnalysis
Determine whether the given fact is valid (neither top nor bottom).- Specified by:
isFactValid
in classAbstractDataflowAnalysis<DefinitelyNullSet>
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transferInstruction
public void transferInstruction(org.apache.bcel.generic.InstructionHandle handle, BasicBlock basicBlock, DefinitelyNullSet fact) throws DataflowAnalysisException
Description copied from class:AbstractDataflowAnalysis
Transfer function for a single instruction.- Specified by:
transferInstruction
in classAbstractDataflowAnalysis<DefinitelyNullSet>
- Parameters:
handle
- the instructionbasicBlock
- the BasicBlock containing the instruction; needed to disambiguate instructions in inlined JSR subroutinesfact
- which should be modified based on the instruction- Throws:
DataflowAnalysisException
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edgeTransfer
public void edgeTransfer(Edge edge, DefinitelyNullSet fact) throws DataflowAnalysisException
Description copied from interface:DataflowAnalysis
Edge transfer function. Modify the given fact that is true on the (logical) edge source to modify it so that it is true at the (logical) edge target.A do-nothing implementation is legal, and appropriate for analyses where branches are not significant.
- Specified by:
edgeTransfer
in interfaceDataflowAnalysis<DefinitelyNullSet>
- Overrides:
edgeTransfer
in classBasicAbstractDataflowAnalysis<DefinitelyNullSet>
- Parameters:
edge
- the Edgefact
- a dataflow fact- Throws:
DataflowAnalysisException
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copy
public void copy(DefinitelyNullSet source, DefinitelyNullSet dest)
Description copied from interface:DataflowAnalysis
Copy dataflow facts.
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createFact
public DefinitelyNullSet 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.
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initEntryFact
public void initEntryFact(DefinitelyNullSet result) throws DataflowAnalysisException
Description copied from interface:DataflowAnalysis
Initialize the "entry" fact for the graph.- Throws:
DataflowAnalysisException
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makeFactTop
public void makeFactTop(DefinitelyNullSet fact)
Description copied from interface:DataflowAnalysis
Make given fact the top value.
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isTop
public boolean isTop(DefinitelyNullSet fact)
Description copied from interface:DataflowAnalysis
Is the given fact the top value.
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meetInto
public void meetInto(DefinitelyNullSet fact, Edge edge, DefinitelyNullSet 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 predecessorresult
- the result fact- Throws:
DataflowAnalysisException
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same
public boolean same(DefinitelyNullSet fact1, DefinitelyNullSet fact2)
Description copied from interface:DataflowAnalysis
Are given dataflow facts the same?
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