Package soot.jimple.toolkits.scalar

Class FastAvailableExpressionsAnalysis

java.lang.Object

soot.toolkits.scalar.AbstractFlowAnalysis<N,A>

soot.toolkits.scalar.FlowAnalysis<N,A>

soot.toolkits.scalar.ForwardFlowAnalysis<Unit,FlowSet<Value>>

soot.jimple.toolkits.scalar.FastAvailableExpressionsAnalysis

public class FastAvailableExpressionsAnalysis
extends ForwardFlowAnalysis<Unit,FlowSet<Value>>

Implements an available expressions analysis on local variables. The current implementation is slow but correct. A better implementation would use an implicit universe and the kill rule would be computed on-the-fly for each statement.

Nested Class Summary

Nested classes/interfaces inherited from class soot.toolkits.scalar.FlowAnalysis

FlowAnalysis.Flow

Field Summary

Fields

Modifier and Type	Field	Description
protected FlowSet<Value>	emptySet
protected Map<Value,Unit>	rhsToContainingStmt	maps an rhs to its containing stmt.
protected SideEffectTester	st
protected Map<Unit,FlowSet<Value>>	unitToGenerateSet

Fields inherited from class soot.toolkits.scalar.FlowAnalysis

filterUnitToAfterFlow, unitToAfterFlow

Fields inherited from class soot.toolkits.scalar.AbstractFlowAnalysis

filterUnitToBeforeFlow, graph, unitToBeforeFlow

Constructor Summary

Constructors

Constructor	Description
FastAvailableExpressionsAnalysis(DirectedGraph<Unit> dg, SootMethod m, SideEffectTester st)

Method Summary

Modifier and Type	Method	Description
protected void	copy(FlowSet<Value> sourceSet, FlowSet<Value> destSet)	Creates a copy of the source flow object in dest.
protected FlowSet<Value>	entryInitialFlow()	Returns the initial flow value for entry/exit graph nodes.
protected void	flowThrough(FlowSet<Value> in, Unit u, FlowSet<Value> out)	Given the merge of the out sets, compute the in set for s (or in to out, depending on direction).
protected void	merge(FlowSet<Value> inSet1, FlowSet<Value> inSet2, FlowSet<Value> outSet)	Compute the merge of the in1 and in2 sets, putting the result into out.
protected FlowSet<Value>	newInitialFlow()	Returns the flow object corresponding to the initial values for each graph node.

Methods inherited from class soot.toolkits.scalar.ForwardFlowAnalysis

doAnalysis, isForward

Methods inherited from class soot.toolkits.scalar.FlowAnalysis

copyFreshToExisting, getFlow, getFlowAfter, getFlowBefore, omissible

Methods inherited from class soot.toolkits.scalar.AbstractFlowAnalysis

merge, mergeInto, treatTrapHandlersAsEntries

Methods inherited from class java.lang.Object

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

Field Detail

emptySet

protected final FlowSet<Value> emptySet

st

protected final SideEffectTester st

rhsToContainingStmt

protected final Map<Value,Unit> rhsToContainingStmt

maps an rhs to its containing stmt. object equality in rhs.

unitToGenerateSet

protected final Map<Unit,FlowSet<Value>> unitToGenerateSet

Constructor Detail

FastAvailableExpressionsAnalysis

public FastAvailableExpressionsAnalysis(DirectedGraph<Unit> dg,
                                        SootMethod m,
                                        SideEffectTester st)

Method Detail

newInitialFlow

protected FlowSet<Value> newInitialFlow()

Description copied from class: AbstractFlowAnalysis

Returns the flow object corresponding to the initial values for each graph node.

Specified by:

newInitialFlow in class AbstractFlowAnalysis<Unit,FlowSet<Value>>

entryInitialFlow

protected FlowSet<Value> entryInitialFlow()

Description copied from class: AbstractFlowAnalysis

Returns the initial flow value for entry/exit graph nodes. This is equal to AbstractFlowAnalysis.newInitialFlow()

Overrides:

entryInitialFlow in class AbstractFlowAnalysis<Unit,FlowSet<Value>>

flowThrough

protected void flowThrough(FlowSet<Value> in,
                           Unit u,
                           FlowSet<Value> out)

Description copied from class: FlowAnalysis

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).

Specified by:

flowThrough in class FlowAnalysis<Unit,FlowSet<Value>>

Parameters:

in - the input flow

u - the current node

out - the returned flow

merge

protected void merge(FlowSet<Value> inSet1,
                     FlowSet<Value> inSet2,
                     FlowSet<Value> outSet)

Description copied from class: AbstractFlowAnalysis

Compute the merge of the in1 and in2 sets, putting the result into out. The behavior of this function depends on the implementation ( it may be necessary to check whether in1 and in2 are equal or aliased ). Used by the doAnalysis method.

Specified by:

merge in class AbstractFlowAnalysis<Unit,FlowSet<Value>>

copy

protected void copy(FlowSet<Value> sourceSet,
                    FlowSet<Value> destSet)

Description copied from class: AbstractFlowAnalysis

Creates a copy of the source flow object in dest.

Specified by:

copy in class AbstractFlowAnalysis<Unit,FlowSet<Value>>