Package edu.umd.cs.findbugs.ba

Class AbstractDominatorsAnalysis

java.lang.Object
edu.umd.cs.findbugs.ba.BasicAbstractDataflowAnalysis<BitSet>
edu.umd.cs.findbugs.ba.AbstractDominatorsAnalysis
All Implemented Interfaces:
DataflowAnalysis<BitSet>
Direct Known Subclasses:
DominatorsAnalysis, PostDominatorsAnalysis
public abstract class AbstractDominatorsAnalysis extends BasicAbstractDataflowAnalysis<BitSet>

A dataflow analysis to compute dominator relationships between basic blocks. Use the BasicAbstractDataflowAnalysis.getResultFact(edu.umd.cs.findbugs.ba.BasicBlock) method to get the dominator set for a given basic block. The dominator sets are represented using the BitSet class, with the individual bits corresponding to the IDs of basic blocks.

Subclasses extend this class to compute either dominators or postdominators.

An EdgeChooser may be specified to select which edges to take into account. For example, exception edges could be ignored.

Author:
David Hovemeyer
See Also:

  • Constructor Details

    • AbstractDominatorsAnalysis

      public AbstractDominatorsAnalysis(CFG cfg, boolean ignoreExceptionEdges)
      Constructor.
      Parameters:
      cfg - the CFG to compute dominator relationships for
      ignoreExceptionEdges - true if exception edges should be ignored

    • AbstractDominatorsAnalysis

      public AbstractDominatorsAnalysis(CFG cfg, EdgeChooser edgeChooser)
      Constructor.
      Parameters:
      cfg - the CFG to compute dominator relationships for
      edgeChooser - EdgeChooser to choose which Edges to consider significant

  • Method Details

    • createFact

      public BitSet 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.

    • copy

      public void copy(BitSet source, BitSet dest)
      Description copied from interface: DataflowAnalysis
      Copy dataflow facts.

    • initEntryFact

      public void initEntryFact(BitSet result)
      Description copied from interface: DataflowAnalysis
      Initialize the "entry" fact for the graph.

    • isTop

      public boolean isTop(BitSet fact)
      Description copied from interface: DataflowAnalysis
      Is the given fact the top value.

    • makeFactTop

      public void makeFactTop(BitSet fact)
      Description copied from interface: DataflowAnalysis
      Make given fact the top value.

    • same

      public boolean same(BitSet fact1, BitSet fact2)
      Description copied from interface: DataflowAnalysis
      Are given dataflow facts the same?

    • transfer

      public void transfer(BasicBlock basicBlock, @CheckForNull org.apache.bcel.generic.InstructionHandle end, BitSet start, BitSet 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.
      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(BitSet fact, Edge edge, BitSet 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.
      Parameters:
      fact - the predecessor fact (incoming edge)
      edge - the edge from the predecessor
      result - the result fact
      Throws:
      DataflowAnalysisException

    • getAllDominatorsOf

      public BitSet getAllDominatorsOf(BasicBlock block)
      Get a bitset containing the unique IDs of all blocks which dominate (or postdominate) the given block.
      Parameters:
      block - a BasicBlock
      Returns:
      BitSet of the unique IDs of all blocks that dominate (or postdominate) the BasicBlock

    • getAllDominatedBy

      public BitSet getAllDominatedBy(BasicBlock dominator)
      Get a bitset containing the unique IDs of all blocks in CFG dominated (or postdominated, depending on how the analysis was done) by given block.
      Parameters:
      dominator - we want to get all blocks dominated (or postdominated) by this block
      Returns:
      BitSet of the ids of all blocks dominated by the given block