com.oracle.svm.core.genscavenge

Class ObjectHeaderImpl

java.lang.Object

com.oracle.svm.core.heap.ObjectHeader

com.oracle.svm.core.genscavenge.ObjectHeaderImpl

public final class ObjectHeaderImpl
extends ObjectHeader

The pointer to the hub is either an uncompressed absolute reference or a heap-base-relative reference without a shift. This limits the address space where all hubs must be placed to 32/64 bits but due to the object alignment, the 3 least-significant bits can be reserved for the GC. Image heap objects are not marked explicitly, but must be treated differently in some regards. In places where it is necessary to distinguish image heap objects, it is necessary to call Heap.isInImageHeap(java.lang.Object).

Method Summary

Modifier and Type	Method and Description
static org.graalvm.word.UnsignedWord	clearBits(org.graalvm.word.UnsignedWord header) Clear the object header bits from a header.
DynamicHub	dynamicHubFromObjectHeader(org.graalvm.word.UnsignedWord header)
long	encodeAsImageHeapObjectHeader(ImageHeapObject obj, long hubOffsetFromHeapBase)
static org.graalvm.compiler.word.Word	encodeAsObjectHeader(DynamicHub hub, boolean rememberedSet, boolean unaligned)
org.graalvm.compiler.word.Word	encodeAsTLABObjectHeader(DynamicHub hub)
org.graalvm.compiler.word.Word	encodeAsUnmanagedObjectHeader(DynamicHub hub)
static ObjectHeaderImpl	getObjectHeaderImpl()
int	getReservedBitsMask() Returns a mask where all reserved bits are set.
static boolean	hasRememberedSet(org.graalvm.word.UnsignedWord header)
void	initializeHeaderOfNewObject(org.graalvm.word.Pointer objectPointer, org.graalvm.compiler.word.Word encodedHub)
static boolean	isAlignedHeader(org.graalvm.word.UnsignedWord header)
static boolean	isAlignedObject(Object o)
static boolean	isConsumedHeapChunkZapped(org.graalvm.word.UnsignedWord header)
static boolean	isForwardedHeader(org.graalvm.word.UnsignedWord header)
static boolean	isPointerToForwardedObject(org.graalvm.word.Pointer p)
static boolean	isProducedHeapChunkZapped(org.graalvm.word.UnsignedWord header)
static boolean	isUnalignedHeader(org.graalvm.word.UnsignedWord header)
static boolean	isUnalignedObject(Object obj)
DynamicHub	readDynamicHubFromPointer(org.graalvm.word.Pointer ptr)
static org.graalvm.word.UnsignedWord	readHeaderFromObject(Object o)
static org.graalvm.word.UnsignedWord	readHeaderFromObjectCarefully(Object o)
static org.graalvm.word.UnsignedWord	readHeaderFromPointer(org.graalvm.word.Pointer objectPointer) Read the header of the object at the specified address.
org.graalvm.word.Pointer	readPotentialDynamicHubFromPointer(org.graalvm.word.Pointer ptr)
static void	setRememberedSetBit(Object o)

Methods inherited from class com.oracle.svm.core.heap.ObjectHeader

pointsToObjectHeader, readDynamicHubFromObject

Methods inherited from class java.lang.Object

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

Method Detail

getObjectHeaderImpl

public static ObjectHeaderImpl getObjectHeaderImpl()

getReservedBitsMask

public int getReservedBitsMask()

Description copied from class: ObjectHeader

Returns a mask where all reserved bits are set.

Specified by:

getReservedBitsMask in class ObjectHeader

readHeaderFromPointer

public static org.graalvm.word.UnsignedWord readHeaderFromPointer(org.graalvm.word.Pointer objectPointer)

Read the header of the object at the specified address. When compressed references are enabled, the specified address must be the uncompressed absolute address of the object in memory.

readHeaderFromObject

public static org.graalvm.word.UnsignedWord readHeaderFromObject(Object o)

readHeaderFromObjectCarefully

public static org.graalvm.word.UnsignedWord readHeaderFromObjectCarefully(Object o)

readDynamicHubFromPointer

public DynamicHub readDynamicHubFromPointer(org.graalvm.word.Pointer ptr)

Specified by:

readDynamicHubFromPointer in class ObjectHeader

dynamicHubFromObjectHeader

public DynamicHub dynamicHubFromObjectHeader(org.graalvm.word.UnsignedWord header)

Specified by:

dynamicHubFromObjectHeader in class ObjectHeader

readPotentialDynamicHubFromPointer

public org.graalvm.word.Pointer readPotentialDynamicHubFromPointer(org.graalvm.word.Pointer ptr)

Specified by:

readPotentialDynamicHubFromPointer in class ObjectHeader

encodeAsUnmanagedObjectHeader

public org.graalvm.compiler.word.Word encodeAsUnmanagedObjectHeader(DynamicHub hub)

Specified by:

encodeAsUnmanagedObjectHeader in class ObjectHeader

initializeHeaderOfNewObject

public void initializeHeaderOfNewObject(org.graalvm.word.Pointer objectPointer,
                                        org.graalvm.compiler.word.Word encodedHub)

Specified by:

initializeHeaderOfNewObject in class ObjectHeader

encodeAsTLABObjectHeader

public org.graalvm.compiler.word.Word encodeAsTLABObjectHeader(DynamicHub hub)

Specified by:

encodeAsTLABObjectHeader in class ObjectHeader

encodeAsObjectHeader

public static org.graalvm.compiler.word.Word encodeAsObjectHeader(DynamicHub hub,
                                                                  boolean rememberedSet,
                                                                  boolean unaligned)

clearBits

public static org.graalvm.word.UnsignedWord clearBits(org.graalvm.word.UnsignedWord header)

Clear the object header bits from a header.

isProducedHeapChunkZapped

public static boolean isProducedHeapChunkZapped(org.graalvm.word.UnsignedWord header)

isConsumedHeapChunkZapped

public static boolean isConsumedHeapChunkZapped(org.graalvm.word.UnsignedWord header)

encodeAsImageHeapObjectHeader

public long encodeAsImageHeapObjectHeader(ImageHeapObject obj,
                                          long hubOffsetFromHeapBase)

Specified by:

encodeAsImageHeapObjectHeader in class ObjectHeader

isAlignedObject

public static boolean isAlignedObject(Object o)

isAlignedHeader

public static boolean isAlignedHeader(org.graalvm.word.UnsignedWord header)

isUnalignedObject

public static boolean isUnalignedObject(Object obj)

isUnalignedHeader

public static boolean isUnalignedHeader(org.graalvm.word.UnsignedWord header)

setRememberedSetBit

public static void setRememberedSetBit(Object o)

hasRememberedSet

public static boolean hasRememberedSet(org.graalvm.word.UnsignedWord header)

isPointerToForwardedObject

public static boolean isPointerToForwardedObject(org.graalvm.word.Pointer p)

isForwardedHeader

public static boolean isForwardedHeader(org.graalvm.word.UnsignedWord header)