Package it.unive.lisa.program.cfg.fixpoints

Class BackwardCFGFixpoint<A extends AbstractState<A>>

java.lang.Object

it.unive.lisa.program.cfg.fixpoints.BackwardCFGFixpoint<A>

Type Parameters:

A - the type of AbstractState contained into the analysis state computed by the fixpoint

All Implemented Interfaces:

Fixpoint.FixpointImplementation<Statement,Edge,CFGFixpoint.CompoundState<A>>

Direct Known Subclasses:

BackwardAscendingFixpoint, BackwardDescendingGLBFixpoint, BackwardDescendingNarrowingFixpoint

public abstract class BackwardCFGFixpoint<A extends AbstractState<A>>
extends java.lang.Object
implements Fixpoint.FixpointImplementation<Statement,Edge,CFGFixpoint.CompoundState<A>>

A Fixpoint.FixpointImplementation for CFGs.

Field Summary

Fields

Modifier and Type	Field	Description
protected CFG	graph	The graph targeted by this implementation.
protected InterproceduralAnalysis<A>	interprocedural	The InterproceduralAnalysis to use for semantics invocations.

Constructor Summary

Constructors

Constructor	Description
BackwardCFGFixpoint(CFG graph, InterproceduralAnalysis<A> interprocedural)	Builds the fixpoint implementation.

Method Summary

Modifier and Type	Method	Description
CFGFixpoint.CompoundState<A>	semantics(Statement node, CFGFixpoint.CompoundState<A> entrystate)	Given a node and its entry state, computes its exit state relying on its semantics. This callback is invoked after the overall entry state for a node has been computed through Fixpoint.FixpointImplementation.union(Object, Object, Object) of the exit states of its predecessors.
CFGFixpoint.CompoundState<A>	traverse(Edge edge, CFGFixpoint.CompoundState<A> entrystate)	Given an edge and a state, computes a new state by modifying the given one assuming that the edge gets traversed. This callback is invoked while computing the overall entry state for a node to filter a state according to the logic of the edge (an edge might be always traversed, or only if a condition holds).
CFGFixpoint.CompoundState<A>	union(Statement node, CFGFixpoint.CompoundState<A> left, CFGFixpoint.CompoundState<A> right)	Given a node and two states, computes their union (i.e.

Methods inherited from class java.lang.Object

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

Methods inherited from interface it.unive.lisa.util.datastructures.graph.algorithms.Fixpoint.FixpointImplementation

equality, operation

Field Detail

graph

protected final CFG graph

The graph targeted by this implementation.

interprocedural

protected final InterproceduralAnalysis<A extends AbstractState<A>> interprocedural

The InterproceduralAnalysis to use for semantics invocations.

Constructor Detail

BackwardCFGFixpoint

public BackwardCFGFixpoint(CFG graph,
                           InterproceduralAnalysis<A> interprocedural)

Builds the fixpoint implementation.

Parameters:

graph - the graph targeted by this implementation

interprocedural - the InterproceduralAnalysis to use for semantics invocation

Method Detail

semantics

public CFGFixpoint.CompoundState<A> semantics(Statement node,
                                              CFGFixpoint.CompoundState<A> entrystate)
                                       throws SemanticException

Description copied from interface: Fixpoint.FixpointImplementation

Given a node and its entry state, computes its exit state relying on its semantics.

This callback is invoked after the overall entry state for a node has been computed through Fixpoint.FixpointImplementation.union(Object, Object, Object) of the exit states of its predecessors.

Specified by:

semantics in interface Fixpoint.FixpointImplementation<Statement,Edge,CFGFixpoint.CompoundState<A extends AbstractState<A>>>

Parameters:

node - the node where the computation takes place

entrystate - the computed state before the computation

Returns:

the exit state

Throws:

SemanticException

traverse

public CFGFixpoint.CompoundState<A> traverse(Edge edge,
                                             CFGFixpoint.CompoundState<A> entrystate)
                                      throws SemanticException

Description copied from interface: Fixpoint.FixpointImplementation

Given an edge and a state, computes a new state by modifying the given one assuming that the edge gets traversed.

This callback is invoked while computing the overall entry state for a node to filter a state according to the logic of the edge (an edge might be always traversed, or only if a condition holds).

Specified by:

traverse in interface Fixpoint.FixpointImplementation<Statement,Edge,CFGFixpoint.CompoundState<A extends AbstractState<A>>>

Parameters:

edge - the edge where the computation takes place

entrystate - the state before traversing

Returns:

the state after traversing

Throws:

SemanticException

union

public CFGFixpoint.CompoundState<A> union(Statement node,
                                          CFGFixpoint.CompoundState<A> left,
                                          CFGFixpoint.CompoundState<A> right)
                                   throws SemanticException

Description copied from interface: Fixpoint.FixpointImplementation

Given a node and two states, computes their union (i.e. least upper bound, not widening).

This callback is invoked for the computation of the overall entry state for a node to merge the exit states of its predecessors, after traversing the edges connecting them through Fixpoint.FixpointImplementation.traverse(Object, Object).

Specified by:

union in interface Fixpoint.FixpointImplementation<Statement,Edge,CFGFixpoint.CompoundState<A extends AbstractState<A>>>

Parameters:

node - the node where the computation takes place

left - the first state

right - the second state

Returns:

the union of the states

Throws:

SemanticException