org.mmtk.plan.markcompact

Class MCConstraints

java.lang.Object

org.mmtk.plan.PlanConstraints

org.mmtk.plan.SimpleConstraints

org.mmtk.plan.StopTheWorldConstraints

org.mmtk.plan.markcompact.MCConstraints

public class MCConstraints
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
MCConstraints()

Method Summary

Modifier and Type	Method and Description
int	gcHeaderBits()
int	gcHeaderWords()
int	maxNonLOSDefaultAllocBytes()
boolean	movesObjects()
boolean	needsForwardAfterLiveness()
boolean	needsLinearScan()
int	numSpecializedScans()

Methods inherited from class org.mmtk.plan.PlanConstraints

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

Methods inherited from class java.lang.Object

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

Constructor Detail

MCConstraints

public MCConstraints()

Method Detail

movesObjects

public boolean movesObjects()

Overrides:

movesObjects in class PlanConstraints

Returns:

true if this Plan moves objects.

needsForwardAfterLiveness

public boolean needsForwardAfterLiveness()

Overrides:

needsForwardAfterLiveness in class PlanConstraints

Returns:

true if this object forwards objects after determining global object liveness (e.g. many compacting collectors).

needsLinearScan

public boolean needsLinearScan()

Overrides:

needsLinearScan in class PlanConstraints

Returns:

true if this Plan requires linear scanning.

maxNonLOSDefaultAllocBytes

public int maxNonLOSDefaultAllocBytes()

Overrides:

maxNonLOSDefaultAllocBytes in class PlanConstraints

Returns:

Size (in bytes) beyond which new regular objects must be allocated to the LOS

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.

numSpecializedScans

public int numSpecializedScans()

Overrides:

numSpecializedScans in class PlanConstraints

Returns:

The specialized scan methods required