Package EDU.purdue.cs.bloat.cfg

Class Subroutine

  • public class Subroutine
extends java.lang.Object
    Subroutine represents a subroutine (target of a jsr instruction) in java bytecode. Subroutines are used to implement the finally part of a try-catch-finally block.

    Each Subroutine belongs in a control flow graph, has an entry and exit block, and has a local variable that contains its return address. Additionally, it maintains a list of paths from blocks in which the subroutine is called to block that is executed after the subroutine returns.

    Note that it is assumed that each subroutine ends with a ret. While this is true for bytecode generated by javac, it is not required.

    See Also:
    AddressStoreStmt, Block

    • Constructor Summary

      Constructors 
      Constructor Description
      Subroutine​(FlowGraph graph)
      Constructor.

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      void addPath​(Block callerBlock, Block returnBlock)
      Adds a path from the block before a Subroutine is called to a block after the subroutine is called.
      Block entry()
      Returns the first Block in the subroutine.
      Block exit()
      Returns the last Block in the subroutine.
      FlowGraph graph()
      Returns the CFG that contains this subroutine.
      int numPaths()
      Returns the number of places that this subroutine is called.
      java.util.Collection paths()
      Returns the paths (a Collection of two-element arrays of Blocks) that represent the Blocks that end in a call to this subroutine and the block that begin with the return address from this subroutine.
      Block pathSource​(Block block)
      Returns the "caller block" for a given "return block".
      Block pathTarget​(Block block)
      Returns the "return block" for a given "caller block".
      void print​(java.io.PrintStream out)
      Prints a textual representation of this Subroutine.
      void removeAllPaths()
      Removes all caller-return paths.
      void removePath​(Block callerBlock, Block returnBlock)
      Removes a path between a caller Block and a return Block.
      void removePathsContaining​(Block block)
      Removes all paths involving block regardless of whether it is a calling (source) block or a returning (target) block.
      LocalVariable returnAddress()
      Returns the local variable containing the return address of this subroutine.
      void setEntry​(Block entry)
      Sets the entry Block for this Subroutine.
      void setExit​(Block exit)
      Sets the exit Block for this Subroutine.
      void setReturnAddress​(LocalVariable returnAddress)
      Sets the address (stored in a LocalVariable) to which this subroutine will return once it is finished.
      java.lang.String toString()  

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

    • Constructor Detail

      • Subroutine

        public Subroutine​(FlowGraph graph)
        Constructor.
        Parameters:
        graph - The CFG containing the block.

    • Method Detail

      • returnAddress

        public LocalVariable returnAddress()
        Returns the local variable containing the return address of this subroutine.

      • setReturnAddress

        public void setReturnAddress​(LocalVariable returnAddress)
        Sets the address (stored in a LocalVariable) to which this subroutine will return once it is finished.
        Parameters:
        returnAddress - Local variable that stores the address to which the subroutine returns when it is completed.
        See Also:
        Tree.visit_astore(EDU.purdue.cs.bloat.editor.Instruction)

      • numPaths

        public int numPaths()
        Returns the number of places that this subroutine is called.

      • paths

        public java.util.Collection paths()
        Returns the paths (a Collection of two-element arrays of Blocks) that represent the Blocks that end in a call to this subroutine and the block that begin with the return address from this subroutine.

      • graph

        public FlowGraph graph()
        Returns the CFG that contains this subroutine.

      • removePathsContaining

        public void removePathsContaining​(Block block)
        Removes all paths involving block regardless of whether it is a calling (source) block or a returning (target) block.

      • removePath

        public void removePath​(Block callerBlock,
                       Block returnBlock)
        Removes a path between a caller Block and a return Block.

      • removeAllPaths

        public void removeAllPaths()
        Removes all caller-return paths.

      • addPath

        public void addPath​(Block callerBlock,
                    Block returnBlock)
        Adds a path from the block before a Subroutine is called to a block after the subroutine is called. If the callerBlock is already associated with a returnBlock, the old returnBlock is replaced.
        Parameters:
        callerBlock - The block in which the subroutine is called. This Block ends with a jsr to this subroutine.
        returnBlock - The block to which the subroutine returns. This Block begins at the return address of this subroutine.

      • pathTarget

        public Block pathTarget​(Block block)
        Returns the "return block" for a given "caller block".

      • pathSource

        public Block pathSource​(Block block)
        Returns the "caller block" for a given "return block".

      • setEntry

        public void setEntry​(Block entry)
        Sets the entry Block for this Subroutine.

      • setExit

        public void setExit​(Block exit)
        Sets the exit Block for this Subroutine.

      • entry

        public Block entry()
        Returns the first Block in the subroutine.

      • exit

        public Block exit()
        Returns the last Block in the subroutine.

      • print

        public void print​(java.io.PrintStream out)
        Prints a textual representation of this Subroutine.
        Parameters:
        out - The PrintStream to which to print.

      • toString

        public java.lang.String toString()
        Overrides:
        toString in class java.lang.Object