org.graalvm.word

Class LocationIdentity

java.lang.Object

org.graalvm.word.LocationIdentity

public abstract class LocationIdentity
extends Object

Marker interface for location identities. A different location identity of two memory accesses guarantees that the two accesses do not interfere.

Clients of LocationIdentity must use Object.equals(Object), not ==, when comparing two LocationIdentity values for equality. Likewise, they must not use IdentityHashMaps with LocationIdentity values as keys.

Since:

19.0

Field Summary

Fields

Modifier and Type	Field and Description
static LocationIdentity	ANY_LOCATION Indicates that the given location is the union of all possible mutable locations.
static LocationIdentity	INIT_LOCATION Location only allowed to be used for writes.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	LocationIdentity() Creates a new location identity.

Method Summary

Modifier and Type	Method and Description
static LocationIdentity	any() Indicates that the given location is the union of all possible mutable locations.
static LocationIdentity	init() Location only allowed to be used for writes.
boolean	isAny() Returns true if this location identity is LocationIdentity.any().
abstract boolean	isImmutable() Denotes a location is unchanging in all cases.
boolean	isInit() Returns true if this location identity is LocationIdentity.init().
boolean	isMutable() The inversion of LocationIdentity.isImmutable().
boolean	isSingle() Returns true if this location identity is not LocationIdentity.any().
boolean	overlaps(LocationIdentity other) Returns true if the memory slice denoted by this location identity may overlap with the provided other location identity.

Methods inherited from class java.lang.Object

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

Field Detail

ANY_LOCATION

public static final LocationIdentity ANY_LOCATION

Indicates that the given location is the union of all possible mutable locations. A write to such a location kill all reads from mutable locations and a read from this location is killed by any write (except for initialization writes).

Since:

19.0

INIT_LOCATION

public static final LocationIdentity INIT_LOCATION

Location only allowed to be used for writes. Indicates that a completely new memory location is written. Kills no read. The previous value at the given location must be either uninitialized or null. Writes to this location do not need a GC pre-barrier.

Since:

19.0

Constructor Detail

LocationIdentity

protected LocationIdentity()

Creates a new location identity. Subclasses are responsible to provide proper implementations of Object.equals(java.lang.Object) and Object.hashCode().

Since:

19.0

Method Detail

any

public static LocationIdentity any()

Indicates that the given location is the union of all possible mutable locations. A write to such a location kill all reads from mutable locations and a read from this location is killed by any write (except for initialization writes).

Since:

19.0

init

public static LocationIdentity init()

Location only allowed to be used for writes. Indicates that a completely new memory location is written. Kills no read. The previous value at the given location must be either uninitialized or null. Writes to this location do not need a GC pre-barrier.

Since:

19.0

isImmutable

public abstract boolean isImmutable()

Denotes a location is unchanging in all cases. Not that this is different than the Java notion of final which only requires definite assignment.

Since:

19.0

isMutable

public final boolean isMutable()

The inversion of LocationIdentity.isImmutable().

Since:

19.0

isAny

public final boolean isAny()

Returns true if this location identity is LocationIdentity.any().

Since:

19.0

isInit

public final boolean isInit()

Returns true if this location identity is LocationIdentity.init().

Since:

19.0

isSingle

public final boolean isSingle()

Returns true if this location identity is not LocationIdentity.any().

Since:

19.0

overlaps

public final boolean overlaps(LocationIdentity other)

Returns true if the memory slice denoted by this location identity may overlap with the provided other location identity.

Since:

19.0