edu.umd.cs.findbugs.ba.constant
Class ConstantAnalysis

java.lang.Object
  edu.umd.cs.findbugs.ba.BasicAbstractDataflowAnalysis<Fact>
      edu.umd.cs.findbugs.ba.AbstractDataflowAnalysis<Fact>
          edu.umd.cs.findbugs.ba.ForwardDataflowAnalysis<FrameType>
              edu.umd.cs.findbugs.ba.FrameDataflowAnalysis<Constant,ConstantFrame>
                  edu.umd.cs.findbugs.ba.constant.ConstantAnalysis

All Implemented Interfaces:

DataflowAnalysis<ConstantFrame>

public class ConstantAnalysis
extends FrameDataflowAnalysis<Constant,ConstantFrame>

Dataflow analysis to find constant values.

Author:

David Hovemeyer

See Also:

Constant

Constructor Summary

ConstantAnalysis(org.apache.bcel.generic.MethodGen methodGen, DepthFirstSearch dfs)

Method Summary

ConstantFrame	createFact() Create empty (uninitialized) dataflow facts for one program point.
void	initEntryFact(ConstantFrame frame) Initialize the "entry" fact for the graph.
void	meetInto(ConstantFrame fact, Edge edge, ConstantFrame result) Meet a dataflow fact associated with an incoming edge into another fact.
protected void	mergeValues(ConstantFrame otherFrame, ConstantFrame resultFrame, int slot) Merge the values contained in a given slot of two Frames.
void	transferInstruction(org.apache.bcel.generic.InstructionHandle handle, BasicBlock basicBlock, ConstantFrame frame) Transfer function for a single instruction.

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

copy, getLastUpdateTimestamp, isFactValid, isTop, makeFactTop, mergeInto, 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, transfer

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

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

Methods inherited from class java.lang.Object

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

Constructor Detail

ConstantAnalysis

public ConstantAnalysis(org.apache.bcel.generic.MethodGen methodGen,
                        DepthFirstSearch dfs)

Method Detail

createFact

public ConstantFrame 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(ConstantFrame frame)

Description copied from interface: DataflowAnalysis

Initialize the "entry" fact for the graph.

transferInstruction

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

Description copied from class: AbstractDataflowAnalysis

Transfer function for a single instruction.

Specified by:

transferInstruction in class AbstractDataflowAnalysis<ConstantFrame>

Parameters:

handle - the instruction

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

frame - which should be modified based on the instruction

Throws:

DataflowAnalysisException

meetInto

public void meetInto(ConstantFrame fact,
                     Edge edge,
                     ConstantFrame 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

mergeValues

protected void mergeValues(ConstantFrame otherFrame,
                           ConstantFrame 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<Constant,ConstantFrame>

Parameters:

otherFrame - a Frame

resultFrame - a Frame which will contain the resulting merged value

slot - a slot in both frames

Throws:

DataflowAnalysisException