Package com.tonic.analysis.simulation.state

Class SimValue

java.lang.Object

com.tonic.analysis.simulation.state.SimValue

public class SimValue
extends Object

Immutable simulated value carrying its type, defining instruction and, for references, a points-to set and null state; usable as a map key.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	SimValue.NullState	What is known about a reference value's nullness.

Method Summary

Modifier and Type	Method	Description
static SimValue	constant(Object value, IRType type, IRInstruction source)	Creates a value with a known constant.
boolean	equals(Object o)
static SimValue	fromSSA(Value value, IRInstruction source)	Wraps an SSA value, adopting its type when it is present.
Object	getConstantValue()
int	getId()
SimValue.NullState	getNullState()
Set<AllocationSite>	getPointsTo()
IRInstruction	getSourceInstruction()
Value	getSSAValue()
IRType	getType()
int	hashCode()
boolean	hasPointsTo()
boolean	isConstant()
boolean	isDefinitelyNotNull()
boolean	isDefinitelyNull()
boolean	isReference()
boolean	isUnknown()
boolean	isWide()
boolean	isWideSecondSlot()
boolean	mayBeNull()
SimValue	merge(SimValue other)	Merges another value into this one, unioning points-to sets and widening disagreeing null states to MAYBE_NULL.
static SimValue	merge(Collection<SimValue> values)	Folds a collection into one value, unioning points-to sets and widening disagreeing null states to MAYBE_NULL.
static SimValue	ofAllocation(AllocationSite site, IRType type, IRInstruction source)	Creates a definitely non-null reference pointing at one allocation site.
static SimValue	ofNull(IRType type, IRInstruction source)	Creates a definitely null reference with an empty points-to set.
static SimValue	ofReference(IRType type, IRInstruction source, Set<AllocationSite> pointsTo, SimValue.NullState nullState)	Creates a reference with a caller-supplied points-to set and null state.
static SimValue	ofType(IRType type, IRInstruction source)	Creates a value carrying only type information.
String	toString()
static SimValue	unknown(IRInstruction source)	Creates an untyped value about which nothing is known.
static SimValue	wideSecondSlot()
SimValue	withAdditionalPointsTo(AllocationSite site)	Copies this value with one more allocation site in its points-to set.
SimValue	withNullState(SimValue.NullState newNullState)	Copies this value with a replaced null state.
SimValue	withPointsTo(Set<AllocationSite> newPointsTo)	Copies this value with a replaced points-to set.

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Method Detail

fromSSA

public static SimValue fromSSA(Value value,
                               IRInstruction source)

Wraps an SSA value, adopting its type when it is present.

Parameters:

value - SSA value being simulated, may be null

source - instruction that produced the value

Returns:

the new simulated value

constant

public static SimValue constant(Object value,
                                IRType type,
                                IRInstruction source)

Creates a value with a known constant.

Parameters:

value - the constant

type - type of the constant

source - instruction that produced the value

Returns:

the new simulated value

ofType

public static SimValue ofType(IRType type,
                              IRInstruction source)

Creates a value carrying only type information.

Parameters:

type - type of the value

source - instruction that produced the value

Returns:

the new simulated value

unknown

public static SimValue unknown(IRInstruction source)

Creates an untyped value about which nothing is known.

Parameters:

source - instruction that produced the value

Returns:

the new simulated value

wideSecondSlot

public static SimValue wideSecondSlot()

Returns:

the placeholder occupying the second slot of a long or double

ofAllocation

public static SimValue ofAllocation(AllocationSite site,
                                    IRType type,
                                    IRInstruction source)

Creates a definitely non-null reference pointing at one allocation site.

Parameters:

site - site the reference points to

type - type of the allocated object

source - instruction that produced the value

Returns:

the new simulated value

ofNull

public static SimValue ofNull(IRType type,
                              IRInstruction source)

Creates a definitely null reference with an empty points-to set.

Parameters:

type - static type of the reference

source - instruction that produced the value

Returns:

the new simulated value

ofReference

public static SimValue ofReference(IRType type,
                                   IRInstruction source,
                                   Set<AllocationSite> pointsTo,
                                   SimValue.NullState nullState)

Creates a reference with a caller-supplied points-to set and null state.

Parameters:

type - static type of the reference

source - instruction that produced the value

pointsTo - allocation sites the reference may point to

nullState - what is known about its nullness

Returns:

the new simulated value

merge

public static SimValue merge(Collection<SimValue> values)

Folds a collection into one value, unioning points-to sets and widening disagreeing null states to MAYBE_NULL.

Parameters:

values - values to merge

Returns:

null if the collection is null or empty, the sole element if there is one, otherwise the merged value

getType

public IRType getType()

Returns:

the type, or null if untyped

getSourceInstruction

public IRInstruction getSourceInstruction()

Returns:

the instruction that produced this value

getSSAValue

public Value getSSAValue()

Returns:

the underlying SSA value, or null if there is none

getConstantValue

public Object getConstantValue()

Returns:

the constant, or null if the value is not constant

isConstant

public boolean isConstant()

Returns:

true if a constant is known and it is not the wide-slot placeholder

isWideSecondSlot

public boolean isWideSecondSlot()

Returns:

true if this is the second slot of a long or double

isWide

public boolean isWide()

Returns:

true if the type occupies two slots

isReference

public boolean isReference()

Returns:

true if the type is a reference type

isUnknown

public boolean isUnknown()

Returns:

true if there is no type, SSA value, constant, or wide-slot marker

getId

public int getId()

Returns:

the identity used by equals and hashCode

getPointsTo

public Set<AllocationSite> getPointsTo()

Returns:

an unmodifiable view of the allocation sites this reference may point to

hasPointsTo

public boolean hasPointsTo()

Returns:

true if the points-to set is non-empty

getNullState

public SimValue.NullState getNullState()

Returns:

what is known about this value's nullness

mayBeNull

public boolean mayBeNull()

Returns:

true unless the value is known to be non-null

isDefinitelyNull

public boolean isDefinitelyNull()

Returns:

true if the value is known to be null

isDefinitelyNotNull

public boolean isDefinitelyNotNull()

Returns:

true if the value is known to be non-null

withPointsTo

public SimValue withPointsTo(Set<AllocationSite> newPointsTo)

Copies this value with a replaced points-to set.

Parameters:

newPointsTo - allocation sites for the copy

Returns:

the copy

withAdditionalPointsTo

public SimValue withAdditionalPointsTo(AllocationSite site)

Copies this value with one more allocation site in its points-to set.

Parameters:

site - site to add

Returns:

the copy

withNullState

public SimValue withNullState(SimValue.NullState newNullState)

Copies this value with a replaced null state.

Parameters:

newNullState - null state for the copy

Returns:

the copy

merge

public SimValue merge(SimValue other)

Merges another value into this one, unioning points-to sets and widening disagreeing null states to MAYBE_NULL.

Parameters:

other - value to merge, may be null

Returns:

this value if the other is null or equal, otherwise the merged value

equals

public boolean equals(Object o)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object

toString

public String toString()

Overrides:

toString in class Object