org.mmtk.plan.generational

Class GenConstraints

java.lang.Object

org.mmtk.plan.PlanConstraints

org.mmtk.plan.SimpleConstraints

org.mmtk.plan.StopTheWorldConstraints

org.mmtk.plan.generational.GenConstraints

Direct Known Subclasses:

GenCopyConstraints, GenImmixConstraints, GenMSConstraints

public class GenConstraints
extends StopTheWorldConstraints

This class and its subclasses communicate to the host VM/Runtime any features of the selected plan that it needs to know. This is separate from the main Plan/PlanLocal class in order to bypass any issues with ordering of static initialization.

Constructor Summary

Constructors

Constructor and Description
GenConstraints()

Method Summary

Modifier and Type	Method and Description
int	gcHeaderBits()
int	gcHeaderWords()
boolean	generational()
int	maxNonLOSDefaultAllocBytes()
boolean	movesObjects()
boolean	needsLogBitInHeader()
boolean	needsObjectReferenceNonHeapWriteBarrier()
boolean	needsObjectReferenceWriteBarrier()
int	numSpecializedScans()
boolean	objectReferenceBulkCopySupported()

Methods inherited from class org.mmtk.plan.PlanConstraints

addressBulkCopySupported, booleanBulkCopySupported, byteBulkCopySupported, charBulkCopySupported, doubleBulkCopySupported, extentBulkCopySupported, floatBulkCopySupported, generateGCTrace, intBulkCopySupported, longBulkCopySupported, maxNonLOSCopyBytes, maxNonLOSNonMovingAllocBytes, maxNumGCThreads, needsAddressReadBarrier, needsAddressWriteBarrier, needsBooleanReadBarrier, needsBooleanWriteBarrier, needsByteReadBarrier, needsByteWriteBarrier, needsCharReadBarrier, needsCharWriteBarrier, needsConcurrentWorkers, needsDoubleReadBarrier, needsDoubleWriteBarrier, needsExtentReadBarrier, needsExtentWriteBarrier, needsFloatReadBarrier, needsFloatWriteBarrier, needsForwardAfterLiveness, needsIntReadBarrier, needsIntWriteBarrier, needsJavaLangReferenceReadBarrier, needsLinearScan, needsLongReadBarrier, needsLongWriteBarrier, needsObjectReferenceNonHeapReadBarrier, needsObjectReferenceReadBarrier, needsOffsetReadBarrier, needsOffsetWriteBarrier, needsShortReadBarrier, needsShortWriteBarrier, needsWordReadBarrier, needsWordWriteBarrier, offsetBulkCopySupported, shortBulkCopySupported, withGCspy, wordBulkCopySupported

Methods inherited from class java.lang.Object

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

Constructor Detail

GenConstraints

public GenConstraints()

Method Detail

generational

public boolean generational()

Overrides:

generational in class PlanConstraints

Returns:

Is this plan generational in nature.

movesObjects

public boolean movesObjects()

Overrides:

movesObjects in class PlanConstraints

Returns:

true if this Plan moves objects.

gcHeaderBits

public int gcHeaderBits()

Specified by:

gcHeaderBits in class PlanConstraints

Returns:

The number of header bits that are required.

gcHeaderWords

public int gcHeaderWords()

Specified by:

gcHeaderWords in class PlanConstraints

Returns:

The number of header words that are required.

needsObjectReferenceWriteBarrier

public boolean needsObjectReferenceWriteBarrier()

Overrides:

needsObjectReferenceWriteBarrier in class PlanConstraints

Returns:

true if this Plan requires write barriers on object references.

needsObjectReferenceNonHeapWriteBarrier

public boolean needsObjectReferenceNonHeapWriteBarrier()

Overrides:

needsObjectReferenceNonHeapWriteBarrier in class PlanConstraints

Returns:

true if this Plan requires non-heap write barriers on object references.

objectReferenceBulkCopySupported

public boolean objectReferenceBulkCopySupported()

Overrides:

objectReferenceBulkCopySupported in class PlanConstraints

Returns:

true if this Plan can perform bulk object arraycopy barriers.

numSpecializedScans

public int numSpecializedScans()

Overrides:

numSpecializedScans in class PlanConstraints

Returns:

The specialized scan methods required

needsLogBitInHeader

public boolean needsLogBitInHeader()

Overrides:

needsLogBitInHeader in class PlanConstraints

Returns:

true if this Plan requires a header bit for object logging

maxNonLOSDefaultAllocBytes

public int maxNonLOSDefaultAllocBytes()

Overrides:

maxNonLOSDefaultAllocBytes in class PlanConstraints

Returns:

The maximum size of an object that may be allocated directly into the nursery