Package edu.umd.cs.findbugs.ba.type

Class TypeAnalysis

java.lang.Object

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

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

edu.umd.cs.findbugs.ba.ForwardDataflowAnalysis<TypeFrame>

edu.umd.cs.findbugs.ba.FrameDataflowAnalysis<org.apache.bcel.generic.Type,TypeFrame>

edu.umd.cs.findbugs.ba.type.TypeAnalysis

All Implemented Interfaces:

DataflowAnalysis<TypeFrame>, EdgeTypes

public class TypeAnalysis
extends FrameDataflowAnalysis<org.apache.bcel.generic.Type,TypeFrame>
implements EdgeTypes

A forward dataflow analysis to determine the types of all values in the Java stack frame at all points in a Java method. The values include local variables and values on the Java operand stack.

As a side effect, the analysis computes the exception set throwable on each exception edge in the CFG. This information can be used to prune infeasible exception edges, and mark exception edges which propagate only implicit exceptions.

Author:

David Hovemeyer

See Also:

• Dataflow
• DataflowAnalysis
• TypeFrame

Field Summary

Fields

Modifier and Type	Field	Description
protected CFG	cfg
static final boolean	DEBUG
static final boolean	FORCE_ACCURATE_EXCEPTIONS	Force computation of accurate exceptions.
protected org.apache.bcel.generic.MethodGen	methodGen

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

Constructor Summary

Constructors

Constructor	Description
TypeAnalysis(org.apache.bcel.classfile.Method method, org.apache.bcel.generic.MethodGen methodGen, CFG cfg, DepthFirstSearch dfs, RepositoryLookupFailureCallback lookupFailureCallback, ExceptionSetFactory exceptionSetFactory)	Constructor which uses StandardTypeMerger.
TypeAnalysis(org.apache.bcel.classfile.Method method, org.apache.bcel.generic.MethodGen methodGen, CFG cfg, DepthFirstSearch dfs, TypeMerger typeMerger, RepositoryLookupFailureCallback lookupFailureCallback, ExceptionSetFactory exceptionSetFactory)	Constructor.
TypeAnalysis(org.apache.bcel.classfile.Method method, org.apache.bcel.generic.MethodGen methodGen, CFG cfg, DepthFirstSearch dfs, TypeMerger typeMerger, TypeFrameModelingVisitor visitor, RepositoryLookupFailureCallback lookupFailureCallback, ExceptionSetFactory exceptionSetFactory)	Constructor.

Method Summary

Modifier and Type	Method	Description
void	copy(TypeFrame source, TypeFrame dest)	Copy dataflow facts.
TypeFrame	createFact()	Create empty (uninitialized) dataflow facts for one program point.
ExceptionSet	getEdgeExceptionSet(Edge edge)	Get the set of exceptions that can be thrown on given edge.
void	initEntryFact(TypeFrame result)	Initialize the "entry" fact for the graph.
boolean	isFactValid(TypeFrame fact)	Determine whether the given fact is valid (neither top nor bottom).
boolean	isImpliedByGenericTypes(org.apache.bcel.generic.ReferenceType t)
void	makeFactTop(TypeFrame fact)	Make given fact the top value.
void	meetInto(TypeFrame fact, Edge edge, TypeFrame result)	Meet a dataflow fact associated with an incoming edge into another fact.
protected void	mergeValues(TypeFrame otherFrame, TypeFrame resultFrame, int slot)	Merge the values contained in a given slot of two Frames.
boolean	same(TypeFrame fact1, TypeFrame fact2)	Are given dataflow facts the same?
void	setFieldStoreTypeDatabase(FieldStoreTypeDatabase database)	Set the FieldStoreTypeDatabase.
void	setValueNumberDataflow(ValueNumberDataflow valueNumberDataflow)	Set the ValueNumberDataflow for the method being analyzed.
String	toString()
void	transfer(BasicBlock basicBlock, org.apache.bcel.generic.InstructionHandle end, TypeFrame start, TypeFrame result)	Transfer function for the analysis.
void	transferInstruction(org.apache.bcel.generic.InstructionHandle handle, BasicBlock basicBlock, TypeFrame fact)	Transfer function for a single instruction.

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

getFactAtPC, getFactBeforeExceptionCheck, getLastUpdateTimestamp, isTop, mergeInto, modifyFrame, 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, startIteration

Methods inherited from class java.lang.Object

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

Field Details

DEBUG

public static final boolean DEBUG

FORCE_ACCURATE_EXCEPTIONS

public static final boolean FORCE_ACCURATE_EXCEPTIONS

Force computation of accurate exceptions.

methodGen

protected org.apache.bcel.generic.MethodGen methodGen

cfg

protected CFG cfg

Constructor Details

TypeAnalysis

public TypeAnalysis(org.apache.bcel.classfile.Method method,
 org.apache.bcel.generic.MethodGen methodGen,
 CFG cfg,
 DepthFirstSearch dfs,
 TypeMerger typeMerger,
 TypeFrameModelingVisitor visitor,
 RepositoryLookupFailureCallback lookupFailureCallback,
 ExceptionSetFactory exceptionSetFactory)

Constructor.

Parameters:

method - TODO

methodGen - the MethodGen whose CFG we'll be analyzing

cfg - the control flow graph

dfs - DepthFirstSearch of the method

typeMerger - object to merge types

visitor - a TypeFrameModelingVisitor to use to model the effect of instructions

lookupFailureCallback - lookup failure callback

exceptionSetFactory - factory for creating ExceptionSet objects

TypeAnalysis

public TypeAnalysis(org.apache.bcel.classfile.Method method,
 org.apache.bcel.generic.MethodGen methodGen,
 CFG cfg,
 DepthFirstSearch dfs,
 TypeMerger typeMerger,
 RepositoryLookupFailureCallback lookupFailureCallback,
 ExceptionSetFactory exceptionSetFactory)

Constructor.

Parameters:

method - TODO

methodGen - the MethodGen whose CFG we'll be analyzing

cfg - the control flow graph

dfs - DepthFirstSearch of the method

typeMerger - object to merge types

lookupFailureCallback - lookup failure callback

exceptionSetFactory - factory for creating ExceptionSet objects

TypeAnalysis

public TypeAnalysis(org.apache.bcel.classfile.Method method,
 org.apache.bcel.generic.MethodGen methodGen,
 CFG cfg,
 DepthFirstSearch dfs,
 RepositoryLookupFailureCallback lookupFailureCallback,
 ExceptionSetFactory exceptionSetFactory)

Constructor which uses StandardTypeMerger.

Parameters:

method - TODO

methodGen - the MethodGen whose CFG we'll be analyzing

cfg - the control flow graph

dfs - DepthFirstSearch of the method

lookupFailureCallback - callback for Repository lookup failures

exceptionSetFactory - factory for creating ExceptionSet objects

Method Details

setValueNumberDataflow

public void setValueNumberDataflow(ValueNumberDataflow valueNumberDataflow)

Set the ValueNumberDataflow for the method being analyzed. This is optional; if set, it will be used to make instanceof instructions more precise.

Parameters:

valueNumberDataflow - the ValueNumberDataflow

setFieldStoreTypeDatabase

public void setFieldStoreTypeDatabase(FieldStoreTypeDatabase database)

Set the FieldStoreTypeDatabase. This can be used to get more accurate types for values loaded from fields.

Parameters:

database - the FieldStoreTypeDatabase

getEdgeExceptionSet

public ExceptionSet getEdgeExceptionSet(Edge edge)

Get the set of exceptions that can be thrown on given edge. This should only be called after the analysis completes.

Parameters:

edge - the Edge

Returns:

the ExceptionSet

createFact

public TypeFrame 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<TypeFrame>

initEntryFact

public void initEntryFact(TypeFrame result)

Description copied from interface: DataflowAnalysis

Initialize the "entry" fact for the graph.

Specified by:

initEntryFact in interface DataflowAnalysis<TypeFrame>

copy

public void copy(TypeFrame source,
 TypeFrame dest)

Description copied from interface: DataflowAnalysis

Copy dataflow facts.

Specified by:

copy in interface DataflowAnalysis<TypeFrame>

Overrides:

copy in class FrameDataflowAnalysis<org.apache.bcel.generic.Type,TypeFrame>

makeFactTop

public void makeFactTop(TypeFrame fact)

Description copied from interface: DataflowAnalysis

Make given fact the top value.

Specified by:

makeFactTop in interface DataflowAnalysis<TypeFrame>

Overrides:

makeFactTop in class FrameDataflowAnalysis<org.apache.bcel.generic.Type,TypeFrame>

isFactValid

public boolean isFactValid(TypeFrame fact)

Description copied from class: AbstractDataflowAnalysis

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

Overrides:

isFactValid in class FrameDataflowAnalysis<org.apache.bcel.generic.Type,TypeFrame>

same

public boolean same(TypeFrame fact1,
 TypeFrame fact2)

Description copied from interface: DataflowAnalysis

Are given dataflow facts the same?

Specified by:

same in interface DataflowAnalysis<TypeFrame>

Overrides:

same in class FrameDataflowAnalysis<org.apache.bcel.generic.Type,TypeFrame>

transferInstruction

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

Description copied from class: AbstractDataflowAnalysis

Transfer function for a single instruction.

Specified by:

transferInstruction in class AbstractDataflowAnalysis<TypeFrame>

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

transfer

public void transfer(BasicBlock basicBlock,
 @CheckForNull
 org.apache.bcel.generic.InstructionHandle end,
 TypeFrame start,
 TypeFrame 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<TypeFrame>

Overrides:

transfer in class AbstractDataflowAnalysis<TypeFrame>

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

meetInto

public void meetInto(TypeFrame fact,
 Edge edge,
 TypeFrame 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<TypeFrame>

Parameters:

fact - the predecessor fact (incoming edge)

edge - the edge from the predecessor

result - the result fact

Throws:

DataflowAnalysisException

mergeValues

protected void mergeValues(TypeFrame otherFrame,
 TypeFrame 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<org.apache.bcel.generic.Type,TypeFrame>

Parameters:

otherFrame - a Frame

resultFrame - a Frame which will contain the resulting merged value

slot - a slot in both frames

Throws:

DataflowAnalysisException

toString

public String toString()

Overrides:

toString in class Object

isImpliedByGenericTypes

public boolean isImpliedByGenericTypes(org.apache.bcel.generic.ReferenceType t)