Package org.apache.bcel.verifier.structurals

Class ControlFlowGraph.InstructionContextImpl

java.lang.Object
org.apache.bcel.verifier.structurals.ControlFlowGraph.InstructionContextImpl
All Implemented Interfaces:
InstructionContext
Enclosing class:
ControlFlowGraph
private final class ControlFlowGraph.InstructionContextImpl extends Object implements InstructionContext
Objects of this class represent a node in a ControlFlowGraph. These nodes are instructions, not basic blocks.

  • Field Details

    • TAG

      private int TAG
      The TAG field is here for external temporary flagging, such as graph coloring.
      See Also:

    • instruction

      private final InstructionHandle instruction
      The InstructionHandle this InstructionContext is wrapped around.

    • inFrames

      private final Map<InstructionContext,Frame> inFrames
      The 'incoming' execution Frames.

    • outFrames

      private final Map<InstructionContext,Frame> outFrames
      The 'outgoing' execution Frames.

    • executionPredecessors

      private List<InstructionContext> executionPredecessors
      The 'execution predecessors' - a list of type InstructionContext of those instances that have been execute()d before in that order.

  • Constructor Details

    • InstructionContextImpl

      public InstructionContextImpl(InstructionHandle inst)
      Creates an InstructionHandleImpl object from an InstructionHandle. Creation of one per InstructionHandle suffices. Don't create more.

  • Method Details

    • _getSuccessors

      private InstructionHandle[] _getSuccessors()
      A utility method that calculates the successors of a given InstructionHandle That means, a RET does have successors as defined here. A JsrInstruction has its target as its successor (opposed to its physical successor) as defined here.

    • execute

      public boolean execute(Frame inFrame, ArrayList<InstructionContext> execPreds, InstConstraintVisitor icv, ExecutionVisitor ev)
      "Merges in" (vmspec2, page 146) the "incoming" frame situation; executes the instructions symbolically and therefore calculates the "outgoing" frame situation. Returns: True iff the "incoming" frame situation changed after merging with "inFrame". The execPreds ArrayList must contain the InstructionContext objects executed so far in the correct order. This is just one execution path [out of many]. This is needed to correctly "merge" in the special case of a RET's successor. The InstConstraintVisitor and ExecutionVisitor instances must be set up correctly.
      Specified by:
      execute in interface InstructionContext
      Returns:
      true - if and only if the "outgoing" frame situation changed from the one before execute()ing.
      See Also:

    • extendMessageWithFlow

      private void extendMessageWithFlow(StructuralCodeConstraintException e)
      Extends the StructuralCodeConstraintException ("e") object with an at-the-end-extended message. This extended message will then reflect the execution flow needed to get to the constraint violation that triggered the throwing of the "e" object.

    • getExceptionHandlers

      public ExceptionHandler[] getExceptionHandlers()
      Returns the exception handlers of this instruction.
      Specified by:
      getExceptionHandlers in interface InstructionContext

    • getExecutionChain

      private String getExecutionChain()
      Returns the control flow execution chain. This is built while execute(Frame, ArrayList)-ing the code represented by the surrounding ControlFlowGraph.

    • getInFrame

      public Frame getInFrame()
      Specified by:
      getInFrame in interface InstructionContext

    • getInstruction

      public InstructionHandle getInstruction()
      Description copied from interface: InstructionContext
      Returns the InstructionHandle this InstructionContext is wrapped around.
      Specified by:
      getInstruction in interface InstructionContext
      Returns:
      The InstructionHandle this InstructionContext is wrapped around.

    • getOutFrame

      public Frame getOutFrame(ArrayList<InstructionContext> execChain)
      Returns a clone of the "outgoing" frame situation with respect to the given ExecutionChain.
      Specified by:
      getOutFrame in interface InstructionContext
      See Also:

    • getSuccessors

      public InstructionContext[] getSuccessors()
      Description copied from interface: InstructionContext
      Returns the usual control flow successors.
      Specified by:
      getSuccessors in interface InstructionContext
      See Also:

    • getTag

      public int getTag()
      Description copied from interface: InstructionContext
      The getTag and setTag methods may be used for temporary flagging, such as graph coloring. Nothing in the InstructionContext object depends on the value of the tag. JustIce does not use it.
      Specified by:
      getTag in interface InstructionContext
      See Also:

    • lastExecutionJSR

      private ControlFlowGraph.InstructionContextImpl lastExecutionJSR()
      Returns the InstructionContextImpl with an JSR/JSR_W that was last in the ExecutionChain, without a corresponding RET, i.e. we were called by this one. Returns null if we were called from the top level.

    • mergeInFrames

      private boolean mergeInFrames(Frame inFrame)
      Does the actual merging (vmspec2, page 146). Returns true IFF this.inFrame was changed in course of merging with inFrame.

    • setTag

      public void setTag(int tag)
      Description copied from interface: InstructionContext
      The getTag and setTag methods may be used for temporary flagging, such as graph coloring. Nothing in the InstructionContext object depends on the value of the tag. JustIce does not use it.
      Specified by:
      setTag in interface InstructionContext
      See Also:

    • toString

      public String toString()
      Returns a simple String representation of this InstructionContext.
      Overrides:
      toString in class Object