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 CardTable and the FirstObjectTable and the start of the Objects are just computed addresses. The two tables each need the same fraction of the size of the space for Objects. I conservatively compute them as a fraction of the size of the entire chunk.

Nested Class Summary

Nested Classes

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

Method Summary

Modifier and Type	Method and Description
static void	dirtyCardForObject(Object object, boolean verifyOnly) Dirty the card corresponding to the given Object.

Methods inherited from class java.lang.Object

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

Method Detail

dirtyCardForObject

public static void dirtyCardForObject(Object object,
                                      boolean verifyOnly)

Dirty the card corresponding to the given Object. This has to be fast, because it is used by the post-write barrier.