org.jikesrvm.classloader

Class TableBasedDynamicLinker

java.lang.Object

org.jikesrvm.classloader.TableBasedDynamicLinker

public class TableBasedDynamicLinker
extends Object

Dynamic linking via indirection tables.

The main idea for dynamic linking is that we maintain arrays of member offsets indexed by the member's dynamic linking id. The generated code at a dynamically linked site will load the appropriate value from the offset table and check to see if the value is valid. If it is, then no dynamic linking is required. If the value is invalid, then resolveDynamicLink is invoked to perform any required dynamic class loading. After member resolution and class loading completes, we can store the offset value in the offset table. Thus when resolve method returns, execution can be restarted by reloading/indexing the offset table.

NOTE: We believe that only use of invokespecial that could possibly require dynamic linking is that of invoking an object initializer.

Field Summary

Fields

Modifier and Type	Field and Description
private static int[]	memberOffsets Linking table keyed by member reference IDs.

Constructor Summary

Constructors

Constructor and Description
TableBasedDynamicLinker()

Method Summary

Modifier and Type	Method and Description
(package private) static void	ensureCapacity(int id) Method invoked from MemberReference to ensure that there is space in the dynamic linking table for the given member reference.
static int	resolveMember(int memberId) Cause dynamic linking of the RVMMember whose member reference id is given.
static int	resolveMember(MemberReference ref) Cause dynamic linking of the argument MemberReference

Methods inherited from class java.lang.Object

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

Field Detail

memberOffsets

private static int[] memberOffsets

Linking table keyed by member reference IDs. Value indicates offset of member or whether the member needs linking.

Constructor Detail

TableBasedDynamicLinker

public TableBasedDynamicLinker()

Method Detail

resolveMember

public static int resolveMember(int memberId)
                         throws NoClassDefFoundError

Cause dynamic linking of the RVMMember whose member reference id is given. Invoked directly from (baseline) compiled code.

Parameters:

memberId - the dynamicLinkingId of the method to link.

Returns:

returns the offset of the member.

Throws:

NoClassDefFoundError

resolveMember

public static int resolveMember(MemberReference ref)
                         throws NoClassDefFoundError

Cause dynamic linking of the argument MemberReference

Parameters:

ref - reference to the member to link

Returns:

returns the offset of the member.

Throws:

NoClassDefFoundError

ensureCapacity

static void ensureCapacity(int id)

Method invoked from MemberReference to ensure that there is space in the dynamic linking table for the given member reference.

Parameters:

id - id of the member reference