Package org.checkerframework.dataflow.analysis

Class ForwardAnalysisImpl<V extends AbstractValue<V>,S extends Store<S>,T extends ForwardTransferFunction<V,S>>

java.lang.Object
org.checkerframework.dataflow.analysis.AbstractAnalysis<V,S,T>
org.checkerframework.dataflow.analysis.ForwardAnalysisImpl<V,S,T>
Type Parameters:
V - the abstract value type to be tracked by the analysis
S - the store type used in the analysis
T - the transfer function type that is used to approximate runtime behavior
All Implemented Interfaces:
Analysis<V,S,T>, ForwardAnalysis<V,S,T>
public class ForwardAnalysisImpl<V extends AbstractValue<V>,S extends Store<S>,T extends ForwardTransferFunction<V,S>> extends AbstractAnalysis<V,S,T> implements ForwardAnalysis<V,S,T>
An implementation of a forward analysis to solve a org.checkerframework.dataflow problem given a control flow graph and a forward transfer function.

  • Field Details

    • blockCount

      protected final @Nullable IdentityHashMap<Block,Integer> blockCount
      Number of times each block has been analyzed since the last time widening was applied. Null if maxCountBeforeWidening is -1, which implies widening isn't used for this analysis.

    • maxCountBeforeWidening

      protected final int maxCountBeforeWidening
      Number of times a block can be analyzed before widening. -1 implies that widening shouldn't be used.

    • thenStores

      protected final IdentityHashMap<Block,S extends Store<S>> thenStores
      Then stores before every basic block (assumed to be 'no information' if not present).

    • elseStores

      protected final IdentityHashMap<Block,S extends Store<S>> elseStores
      Else stores before every basic block (assumed to be 'no information' if not present).

    • storesAtReturnStatements

      protected final IdentityHashMap<ReturnNode,TransferResult<V extends AbstractValue<V>,S extends Store<S>>> storesAtReturnStatements
      The stores after every return statement.

  • Constructor Details

    • ForwardAnalysisImpl

      public ForwardAnalysisImpl(int maxCountBeforeWidening)
      Construct an object that can perform a org.checkerframework.dataflow forward analysis over a control flow graph. When using this constructor, the transfer function is set later by the subclass, e.g., org.checkerframework.framework.flow.CFAbstractAnalysis.
      Parameters:
      maxCountBeforeWidening - number of times a block can be analyzed before widening

    • ForwardAnalysisImpl

      public ForwardAnalysisImpl(T transferFunction)
      Construct an object that can perform a org.checkerframework.dataflow forward analysis over a control flow graph given a transfer function.
      Parameters:
      transferFunction - the transfer function

  • Method Details

    • performAnalysis

      public void performAnalysis(ControlFlowGraph cfg)
      Description copied from interface: Analysis
      Perform the actual analysis.
      Specified by:
      performAnalysis in interface Analysis<V extends AbstractValue<V>,S extends Store<S>,T extends ForwardTransferFunction<V,S>>
      Parameters:
      cfg - the control flow graph

    • performAnalysisBlock

      public void performAnalysisBlock(Block b)
      Description copied from interface: Analysis
      Perform the actual analysis on one block.
      Specified by:
      performAnalysisBlock in interface Analysis<V extends AbstractValue<V>,S extends Store<S>,T extends ForwardTransferFunction<V,S>>
      Parameters:
      b - the block to analyze

    • getInput

      public @Nullable TransferInput<V,S> getInput(Block b)
      Description copied from interface: Analysis
      Get the transfer input of a given Block b.
      Specified by:
      getInput in interface Analysis<V extends AbstractValue<V>,S extends Store<S>,T extends ForwardTransferFunction<V,S>>
      Parameters:
      b - a given Block
      Returns:
      the transfer input of this Block

    • getReturnStatementStores

      @RequiresNonNull("cfg") public List<org.plumelib.util.IPair<ReturnNode,@Nullable TransferResult<V,S>>> getReturnStatementStores()
      Description copied from interface: ForwardAnalysis
      Get stores at return statements. These stores are transfer results at return node. Thus for a forward analysis, these stores contain the analyzed flow information from entry nodes to return nodes.
      Specified by:
      getReturnStatementStores in interface ForwardAnalysis<V extends AbstractValue<V>,S extends Store<S>,T extends ForwardTransferFunction<V,S>>
      Returns:
      the transfer results for each return node in the CFG

    • runAnalysisFor

      public S runAnalysisFor(@FindDistinct Node node, Analysis.BeforeOrAfter preOrPost, TransferInput<V,S> blockTransferInput, IdentityHashMap<Node,V> nodeValues, @Nullable Map<TransferInput<V,S>,IdentityHashMap<Node,TransferResult<V,S>>> analysisCaches)
      Description copied from interface: Analysis
      Runs the analysis again within the block of node and returns the store at the location of node. If before is true, then the store immediately before the Node node is returned. Otherwise, the store immediately after node is returned. If analysisCaches is not null, this method uses a cache. analysisCaches is a map of a block of node to the cached analysis result. If the cache for transferInput is not in analysisCaches, this method creates new cache and stores it in analysisCaches. The cache is a map of nodes to the analysis results of the nodes.
      Specified by:
      runAnalysisFor in interface Analysis<V extends AbstractValue<V>,S extends Store<S>,T extends ForwardTransferFunction<V,S>>
      Parameters:
      node - the node to analyze
      preOrPost - which store to return: the store immediately before node or the store after node
      blockTransferInput - the transfer input of the block of this node
      nodeValues - abstract values of nodes
      analysisCaches - caches of analysis results
      Returns:
      the store before or after node (depends on the value of before) after running the analysis

    • initFields

      protected void initFields(ControlFlowGraph cfg)
      Description copied from class: AbstractAnalysis
      Initialize fields of this object based on a given control flow graph. Sub-class may override this method to initialize customized fields.
      Overrides:
      initFields in class AbstractAnalysis<V extends AbstractValue<V>,S extends Store<S>,T extends ForwardTransferFunction<V,S>>
      Parameters:
      cfg - a given control flow graph

    • initInitialInputs

      @RequiresNonNull("cfg") protected void initInitialInputs()
      Description copied from class: AbstractAnalysis
      Initialize the transfer inputs of every basic block before performing the analysis.
      Specified by:
      initInitialInputs in class AbstractAnalysis<V extends AbstractValue<V>,S extends Store<S>,T extends ForwardTransferFunction<V,S>>

    • callTransferFunction

      protected TransferResult<V,S> callTransferFunction(Node node, TransferInput<V,S> input)
      Description copied from class: AbstractAnalysis
      Call the transfer function for node node, and set that node as current node first. This method requires a transferInput that the method can modify.
      Overrides:
      callTransferFunction in class AbstractAnalysis<V extends AbstractValue<V>,S extends Store<S>,T extends ForwardTransferFunction<V,S>>
      Parameters:
      node - the given node
      input - the transfer input
      Returns:
      the output of the transfer function

    • propagateStoresTo

      protected void propagateStoresTo(Block succ, @Nullable Node node, TransferInput<V,S> currentInput, Store.FlowRule flowRule, boolean addToWorklistAgain)
      Description copied from class: AbstractAnalysis
      Propagate the stores in currentInput to the next block in the direction of analysis, according to the flowRule.
      Specified by:
      propagateStoresTo in class AbstractAnalysis<V extends AbstractValue<V>,S extends Store<S>,T extends ForwardTransferFunction<V,S>>
      Parameters:
      succ - the target block to propagate the stores to
      node - the node of the target block
      currentInput - the current transfer input
      flowRule - the flow rule being used
      addToWorklistAgain - whether the block should be added to AbstractAnalysis.worklist again

    • addStoreBefore

      protected void addStoreBefore(Block b, @Nullable Node node, S s, Store.Kind kind, boolean addBlockToWorklist)
      Add a store before the basic block b by merging with the existing stores for that location.
      Parameters:
      b - a basic block
      node - the node of the basic block b
      s - the store being added
      kind - the kind of store s
      addBlockToWorklist - whether the basic block b should be added back to Worklist

    • getStoreBefore

      protected @Nullable S getStoreBefore(Block b, Store.Kind kind)
      Return the store corresponding to the location right before the basic block b.
      Parameters:
      b - a block
      kind - the kind of store which will be returned
      Returns:
      the store corresponding to the location right before the basic block b

    • getInputBefore

      protected @Nullable TransferInput<V,S> getInputBefore(Block b)
      Returns the transfer input corresponding to the location right before the basic block b.
      Parameters:
      b - a block
      Returns:
      the transfer input corresponding to the location right before the basic block b