Package sootup.analysis.intraprocedural

Class FlowAnalysis<A>

java.lang.Object

sootup.analysis.intraprocedural.AbstractFlowAnalysis<A>

sootup.analysis.intraprocedural.FlowAnalysis<A>

Direct Known Subclasses:

BackwardFlowAnalysis, ForwardFlowAnalysis

public abstract class FlowAnalysis<A>
extends AbstractFlowAnalysis<A>

An abstract class providing a framework for carrying out dataflow analysis. Subclassing either BackwardFlowAnalysis or ForwardFlowAnalysis and providing implementations for the abstract methods will allow Soot to compute the corresponding flow analysis.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static enum	FlowAnalysis.Flow

Field Summary

Fields

Modifier and Type	Field	Description
protected Map<Stmt,A>	filterStmtToAfterFlow	Filtered: Maps graph nodes to OUT sets.
protected final Map<Stmt,A>	stmtToAfterFlow	Maps graph nodes to OUT sets.

Fields inherited from class sootup.analysis.intraprocedural.AbstractFlowAnalysis

graph, stmtToBeforeFlow

Constructor Summary

Constructors

Constructor	Description
FlowAnalysis(StmtGraph<? extends BasicBlock<?>> graph)	Constructs a flow analysis on the given DirectedGraph.

Method Summary

Modifier and Type	Method	Description
protected abstract void	flowThrough(A in, Stmt d, A out)	Given the merge of the out sets, compute the in set for s (or in to out, depending on direction).
protected FlowAnalysis.Flow	getFlow(Stmt from, Stmt mergeNode)	You can specify which flow set you would like to use of node from
A	getFlowAfter(Stmt s)	Accessor function returning value of OUT set for s.
A	getFlowBefore(Stmt s)	Accessor function returning value of IN set for s.
protected boolean	omissible(Stmt stmt)	If a flow node can be omitted return true, otherwise false.

Methods inherited from class sootup.analysis.intraprocedural.AbstractFlowAnalysis

copy, entryInitialFlow, execute, isForward, merge, merge, mergeInto, newInitialFlow, treatTrapHandlersAsEntries

Methods inherited from class java.lang.Object

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

Field Details

stmtToAfterFlow

@Nonnull
protected final Map<Stmt,A> stmtToAfterFlow

Maps graph nodes to OUT sets.

filterStmtToAfterFlow

@Nonnull
protected Map<Stmt,A> filterStmtToAfterFlow

Filtered: Maps graph nodes to OUT sets.

Constructor Details

FlowAnalysis

public FlowAnalysis(@Nonnull
 StmtGraph<? extends BasicBlock<?>> graph)

Constructs a flow analysis on the given DirectedGraph.

Method Details

flowThrough

protected abstract void flowThrough(@Nonnull
 A in,
 Stmt d,
 @Nonnull
 A out)

Given the merge of the out sets, compute the in set for s (or in to out, depending on direction).

This function often causes confusion, because the same interface is used for both forward and backward flow analyses. The first parameter is always the argument to the flow function (i.e. it is the "in" set in a forward analysis and the "out" set in a backward analysis), and the third parameter is always the result of the flow function (i.e. it is the "out" set in a forward analysis and the "in" set in a backward analysis).

Parameters:

in - the input flow

d - the current node

out - the returned flow

getFlowAfter

public A getFlowAfter(@Nonnull
 Stmt s)

Accessor function returning value of OUT set for s.

getFlowBefore

@Nonnull
public A getFlowBefore(@Nonnull
 Stmt s)

Description copied from class: AbstractFlowAnalysis

Accessor function returning value of IN set for s.

Overrides:

getFlowBefore in class AbstractFlowAnalysis<A>

omissible

protected boolean omissible(@Nonnull
 Stmt stmt)

If a flow node can be omitted return true, otherwise false. There is no guarantee a node will be omitted. A omissible node does not influence the result of an analysis.

If you are unsure, don't overwrite this method

Parameters:

stmt - the node to check

Returns:

false

getFlow

protected FlowAnalysis.Flow getFlow(@Nonnull
 Stmt from,
 @Nonnull
 Stmt mergeNode)

You can specify which flow set you would like to use of node from

Parameters:

from -

mergeNode -

Returns:

Flow.OUT