Package proguard.analysis.cpa.bam

Class BamTransferRelation<CfaNodeT extends CfaNode<CfaEdgeT,​SignatureT>,​CfaEdgeT extends CfaEdge<CfaNodeT>,​SignatureT extends Signature>

  • All Implemented Interfaces:
    TransferRelation
    public class BamTransferRelation<CfaNodeT extends CfaNode<CfaEdgeT,​SignatureT>,​CfaEdgeT extends CfaEdge<CfaNodeT>,​SignatureT extends Signature>
extends java.lang.Object
implements TransferRelation
    This TransferRelation extends an analysis inter-procedurally. The transfer relation applies as close as possible the algorithms described in {@see https://dl.acm.org/doi/pdf/10.1145/3368089.3409718}. On a high level the task of this domain-independent transfer relation is to extend the intra-procedural domain-dependent transfer relation of a CpaWithBamOperators inter-procedurally. For more details on how the transfer relation works see generateAbstractSuccessors(AbstractState, Precision).

    • Constructor Detail

      • BamTransferRelation

        public BamTransferRelation​(CpaWithBamOperators<CfaNodeT,​CfaEdgeT,​SignatureT> wrappedCpa,
                           Cfa<CfaNodeT,​CfaEdgeT,​SignatureT> cfa,
                           SignatureT mainFunction,
                           BamCache<SignatureT> cache,
                           int maxCallStackDepth,
                           AbortOperator abortOperator)
        Create a BAM transfer relation with a specified maximum call stack depth. When the call stack meets its size limit the method call analysis is delegated to the wrapped intra-procedural transfer relation.
        Parameters:
        wrappedCpa - a wrapped CPA with BAM operators
        cfa - a control flow automaton
        mainFunction - the signature of the main function of an analyzed program
        cache - a cache for the block abstractions
        maxCallStackDepth - maximum depth of the call stack analyzed inter-procedurally. 0 means intra-procedural analysis. < 0 means no maximum depth.
        abortOperator - an abort operator used for computing block abstractions

    • Method Detail

      • generateAbstractSuccessors

        public java.util.Collection<? extends AbstractState> generateAbstractSuccessors​(AbstractState abstractState,
                                                                                Precision precision)
        In order to implement an inter-procedural analysis the abstract successors are calculated for the following cases:

        - Run the fixed point algorithm from the entry of the main method, continuing the analysis until a fixed point is reached (i.e. a function summary is provided for each function, also the recursive ones). If there are no recursive calls the fixed point is reached after the first iteration, while in case of recursive calls, depending on the domain-dependent transfer relation, they can be unrolled at each iteration until the fixed point is reached.

        - Run the applyBlockAbstraction algorithm at every known procedure call. This algorithm takes care of retrieving the summary of the procedure from the cache (if available) or calls CpaAlgorithm recursively on the new function to compute and store in the cache the summary of the procedure when called from the specified AbstractState (i.e. different parameters or global state result in a different summary). Since we have no information on the code of the target of SymbolicCall this type of calls is delegated to the intra-procedural transfer relation instead of being analyzed by the applyBlockAbstraction algorithm. The result of the block abstraction on the intra-procedural level is simply generating a successor (or successors in case there are multiple call edges, e.g. for unknown runtime type of an object) abstract state that has as location the next node of the Cfa. The recursion can be limited at a maximum call stack size. The intra-procedural transfer relation is also applied in case the max call stack size is reached.

        - Apply the underlying intra-procedural transfer relation to all the other non-exit nodes in order to act as the wrapped transfer relation when procedure calls are not involved.

        - Exit nodes reached are the base cases of the recursion (along with the stop operator), in this case the transfer relation returns with no successors.

        Specified by:
        generateAbstractSuccessors in interface TransferRelation

      • getMaxCallStackDepth

        public int getMaxCallStackDepth()
        Returns the maximal call stack depth. If negative the maximum call stack depth is unlimited.

      • getWaitlist

        protected Waitlist getWaitlist()
        By default the Waitlist used by the applyBlockAbstraction algorithm is a BreadthFirstWaitlist, this method can be overridden to provide a different waitlist.

      • getCache

        public BamCache<SignatureT> getCache()
        Returns BAM cache storing analysis result for various method calls.