edu.umd.cs.findbugs.ba
Interface DataflowAnalysis<Fact>

All Known Implementing Classes:

AbstractDataflowAnalysis, AbstractDominatorsAnalysis, BackwardDataflowAnalysis, BetterTypeAnalysis, BlockTypeAnalysis, CallListAnalysis, ConstantAnalysis, DominatorsAnalysis, FieldSetAnalysis, ForwardDataflowAnalysis, FrameDataflowAnalysis, IsNullValueAnalysis, LiveLocalStoreAnalysis, LoadAnalysis, LockAnalysis, ObligationAnalysis, PostDominatorsAnalysis, ResourceValueAnalysis, ReturnPathAnalysis, StackDepthAnalysis, StoreAnalysis, TypeAnalysis, UnconditionalDerefAnalysis, ValueNumberAnalysis, WillBeDereferencedAnalysis

public interface DataflowAnalysis<Fact>

A dataflow analysis to be used with the Dataflow class.

Author:

David Hovemeyer

See Also:

Dataflow

Method Summary

void	copy(Fact source, Fact dest) Copy dataflow facts.
Fact	createFact() Create empty (uninitialized) dataflow facts for one program point.
BlockOrder	getBlockOrder(CFG cfg) Return the BlockOrder specifying the order in which BasicBlocks should be visited in the main dataflow loop.
Fact	getResultFact(BasicBlock block) Get the result fact for given basic block.
Fact	getStartFact(BasicBlock block) Get the start fact for given basic block.
void	initEntryFact(Fact result) Initialize the "entry" fact for the graph.
void	initResultFact(Fact result) Initialize result fact for block.
boolean	isForwards() Returns true if the analysis is forwards, false if backwards.
void	makeFactTop(Fact fact) Make given fact the top value.
void	meetInto(Fact fact, Edge edge, Fact result) Meet a dataflow fact associated with an incoming edge into another fact.
boolean	same(Fact fact1, Fact fact2) Are given dataflow facts the same?
void	transfer(BasicBlock basicBlock, org.apache.bcel.generic.InstructionHandle end, Fact start, Fact result) Transfer function for the analysis.

Method Detail

createFact

Fact createFact()

Create empty (uninitialized) dataflow facts for one program point. A valid value will be copied into it before it is used.

getStartFact

Fact getStartFact(BasicBlock block)

Get the start fact for given basic block.

Parameters:

block - the basic block

getResultFact

Fact getResultFact(BasicBlock block)

Get the result fact for given basic block.

Parameters:

block - the basic block

copy

void copy(Fact source,
          Fact dest)

Copy dataflow facts.

initEntryFact

void initEntryFact(Fact result)
                   throws DataflowAnalysisException

Initialize the "entry" fact for the graph.

Throws:

DataflowAnalysisException

initResultFact

void initResultFact(Fact result)

Initialize result fact for block. The start facts for a block are initialized as the meet of the "logical" predecessor's result facts. Note that a "logical predecessor" is actually a CFG successor if the analysis is backwards.

makeFactTop

void makeFactTop(Fact fact)

Make given fact the top value.

isForwards

boolean isForwards()

Returns true if the analysis is forwards, false if backwards.

getBlockOrder

BlockOrder getBlockOrder(CFG cfg)

Return the BlockOrder specifying the order in which BasicBlocks should be visited in the main dataflow loop.

Parameters:

cfg - the CFG upon which we're performing dataflow analysis

same

boolean same(Fact fact1,
             Fact fact2)

Are given dataflow facts the same?

transfer

void transfer(BasicBlock basicBlock,
              @Nullable
              org.apache.bcel.generic.InstructionHandle end,
              Fact start,
              Fact result)
              throws DataflowAnalysisException

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.

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

void meetInto(Fact fact,
              Edge edge,
              Fact result)
              throws DataflowAnalysisException

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