edu.umd.cs.findbugs.ba.vna

Class ValueNumberAnalysis

public class ValueNumberAnalysis extends FrameDataflowAnalysis<ValueNumber,ValueNumberFrame>

A dataflow analysis to track the production and flow of values in the Java stack frame. See the ValueNumber class for an explanation of what the value numbers mean, and when they can be compared.

This class is still experimental.

Author: David Hovemeyer

Field Summary
static boolean	DEBUG

Constructor Summary
	ValueNumberAnalysis(MethodGen methodGen, DepthFirstSearch dfs, LoadedFieldSet loadedFieldSet, RepositoryLookupFailureCallback lookupFailureCallback)

Method Summary
void	compactValueNumbers(Dataflow<ValueNumberFrame,ValueNumberAnalysis> dataflow) Compact the value numbers assigned.
ValueNumberFrame	createFact()
Iterator<ValueNumberFrame>	factIterator() Get an Iterator over all dataflow facts that we've recorded for the Locations in the CFG.
ValueNumber	getClassObjectValue(String className)
ValueNumber	getEntryValue(int local)
ValueNumberFactory	getFactory()
MergeTree	getMergeTree()
int	getNumValuesAllocated()
ValueNumber	getThisValue()
void	initEntryFact(ValueNumberFrame result)
boolean	isThisValue(ValueNumber value)
static void	main(String[] argv) Test driver.
void	meetInto(ValueNumberFrame fact, Edge edge, ValueNumberFrame result)
void	setMergeTree(MergeTree mergeTree)

Constructor Detail

ValueNumberAnalysis

public ValueNumberAnalysis(MethodGen methodGen, DepthFirstSearch dfs, LoadedFieldSet loadedFieldSet, RepositoryLookupFailureCallback lookupFailureCallback)

Method Detail

compactValueNumbers

public void compactValueNumbers(Dataflow<ValueNumberFrame,ValueNumberAnalysis> dataflow)

Compact the value numbers assigned. This should be done only after the dataflow algorithm has executed. This works by modifying the actual ValueNumber objects assigned. After this method is called, the getNumValuesAllocated() method of this object will return a value less than or equal to the value it would have returned before the call to this method.

This method should be called at most once.

Parameters: dataflow the Dataflow object which executed this analysis (and has all of the block result values)

createFact

public ValueNumberFrame createFact()

factIterator

public Iterator<ValueNumberFrame> factIterator()

Get an Iterator over all dataflow facts that we've recorded for the Locations in the CFG. Note that this does not include result facts (since there are no Locations corresponding to the end of basic blocks).