FindBugs™ 1.3.9

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

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<org.apache.bcel.generic.Type,TypeFrame>
                  extended by 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
protected  CFG cfg
           
static boolean DEBUG
           
static 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
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
 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).
 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.
 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
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, toString, wait, wait, wait
 

Field Detail

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 Detail

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 Detail

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

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