com.oracle.svm.core.genscavenge

Class AlignedHeapChunk

java.lang.Object

com.oracle.svm.core.genscavenge.AlignedHeapChunk

public final class AlignedHeapChunk
extends Object

An AlignedHeapChunk can hold many Objects.

This is the key to the chunk-allocated heap: Because these chunks are allocated on aligned boundaries, I can map from a Pointer to (or into) an Object to the AlignedChunk that contains it. From there I can get to the meta-data the AlignedChunk contains, without a table lookup on the Pointer.

Most allocation within a AlignedHeapChunk is via fast-path allocation snippets, but a slow-path allocation method is available.

Objects in a AlignedHeapChunk have to be promoted by copying from their current HeapChunk to a destination HeapChunk.

An AlignedHeapChunk is laid out:

 +===============+-------+--------+----------------------+
 | AlignedHeader | Card  | First  | Object ...           |
 | Fields        | Table | Object |                      |
 |               |       | Table  |                      |
 +===============+-------+--------+----------------------+
 

The size of both the CardTable and the FirstObjectTable depends on the used RememberedSet implementation and may even be zero.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	AlignedHeapChunk.AlignedHeader Additional fields beyond what is in HeapChunk.Header.

Method Summary

Modifier and Type	Method and Description
static AlignedHeapChunk.AlignedHeader	getEnclosingChunk(Object obj)
static AlignedHeapChunk.AlignedHeader	getEnclosingChunkFromObjectPointer(org.graalvm.word.Pointer ptr)
static org.graalvm.word.UnsignedWord	getObjectOffset(AlignedHeapChunk.AlignedHeader that, org.graalvm.word.Pointer objectPointer) Return the offset of an object within the objects part of a chunk.
static org.graalvm.word.Pointer	getObjectsEnd(AlignedHeapChunk.AlignedHeader that)
static org.graalvm.word.Pointer	getObjectsStart(AlignedHeapChunk.AlignedHeader that)
static org.graalvm.word.UnsignedWord	getObjectsStartOffset()
static void	initialize(AlignedHeapChunk.AlignedHeader chunk, org.graalvm.word.UnsignedWord chunkSize)
static void	reset(AlignedHeapChunk.AlignedHeader chunk)

Methods inherited from class java.lang.Object

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

Method Detail

initialize

public static void initialize(AlignedHeapChunk.AlignedHeader chunk,
                              org.graalvm.word.UnsignedWord chunkSize)

reset

public static void reset(AlignedHeapChunk.AlignedHeader chunk)

getObjectsStart

public static org.graalvm.word.Pointer getObjectsStart(AlignedHeapChunk.AlignedHeader that)

getObjectsEnd

public static org.graalvm.word.Pointer getObjectsEnd(AlignedHeapChunk.AlignedHeader that)

getEnclosingChunk

public static AlignedHeapChunk.AlignedHeader getEnclosingChunk(Object obj)

getEnclosingChunkFromObjectPointer

public static AlignedHeapChunk.AlignedHeader getEnclosingChunkFromObjectPointer(org.graalvm.word.Pointer ptr)

getObjectOffset

public static org.graalvm.word.UnsignedWord getObjectOffset(AlignedHeapChunk.AlignedHeader that,
                                                            org.graalvm.word.Pointer objectPointer)

Return the offset of an object within the objects part of a chunk.

getObjectsStartOffset

public static org.graalvm.word.UnsignedWord getObjectsStartOffset()