org.jikesrvm.compilers.opt.inlining

Class InvalidationDatabase

java.lang.Object

org.jikesrvm.compilers.opt.inlining.InvalidationDatabase

public final class InvalidationDatabase
extends Object

This class holds the dependencies that define invalidation requirements for the opt compiled methods.

Currently we only support 2 kinds of dependencies: The set of compiled method id's that depend on a RVMMethod not being overridden. The set of compiled method id's that depend on a RVMClass having no subclasses

Note we track by compiled method ids instead of pointers to compiled methods because we don't have weak pointers. We don't want the invalidaton database to keep code alive! This would be an ideal use of weak references if we had them.

TODO: In the future, we should think about implementing a general dependency mechanism. See Chambers, Dean, Grove in ICSE-17 (1995) for one possible design and pointers to related work.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
(package private) static class	InvalidationDatabase.MethodSet The following defines a set of methods that share a common "key"

Field Summary

Fields

Modifier and Type	Field and Description
private HashMapRVM<RVMMethod,InvalidationDatabase.MethodSet>	nonOverriddenHash A mapping from RVMMethod to MethodSet: holds the set of methods which depend on a particular method being "final"
private HashMapRVM<RVMClass,InvalidationDatabase.MethodSet>	noSubclassHash A mapping from RVMClass to MethodSet: holds the set of methods which depend on a particular class being "final"

Constructor Summary

Constructors

Constructor and Description
InvalidationDatabase()

Method Summary

Modifier and Type	Method and Description
void	addNoSubclassDependency(RVMClass source, int dependent_cmid) Records that if a particular RVMClass ever has a subclass, then the CompiledMethod encoded by the cmid must be invalidated.
void	addNotOverriddenDependency(RVMMethod source, int dependent_cmid) Records that if a particular RVMMethod method is ever overridden, then the CompiledMethod encoded by the cmid must be invalidated.
private <T> InvalidationDatabase.MethodSet	findOrCreateMethodSet(HashMapRVM<T,InvalidationDatabase.MethodSet> hash, T key) Looks up the MethodSet corresponding to a given key in the database.
Iterator<Integer>	invalidatedByOverriddenMethod(RVMMethod m) Returns an iteration of CMID's (compiled method ids) that are dependent on the argument RVMMethod not being overridden.
Iterator<Integer>	invalidatedBySubclass(RVMClass m) Returns an iteration of CMID's (compiled method ids) that are dependent on the argument RVMMethod not having any subclasses.
void	removeNoSubclassDependency(RVMClass source) Deletes all NoSubclass dependencies on the argument RVMClass.
void	removeNoSubclassDependency(RVMClass source, int dependent_cmid) Delete as NoSubclassDependency.
void	removeNotOverriddenDependency(RVMMethod source) Delete all NotOverridden dependencies on the argument RVMMethod
void	removeNotOverriddenDependency(RVMMethod source, int dependent_cmid) Deletes a NotOverriddenDependency.

Methods inherited from class java.lang.Object

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

Field Detail

nonOverriddenHash

private final HashMapRVM<RVMMethod,InvalidationDatabase.MethodSet> nonOverriddenHash

A mapping from RVMMethod to MethodSet: holds the set of methods which depend on a particular method being "final"

noSubclassHash

private final HashMapRVM<RVMClass,InvalidationDatabase.MethodSet> noSubclassHash

A mapping from RVMClass to MethodSet: holds the set of methods which depend on a particular class being "final"

Constructor Detail

InvalidationDatabase

public InvalidationDatabase()

Method Detail

invalidatedByOverriddenMethod

public Iterator<Integer> invalidatedByOverriddenMethod(RVMMethod m)

Returns an iteration of CMID's (compiled method ids) that are dependent on the argument RVMMethod not being overridden. If there are no dependent methods, null will be returned.

NOTE: null is used instead of EmptyIterator.getInstance as part of delicate dance to avoid recursive classloading.

Parameters:

m - a method that can be overridden

Returns:

an iterator of CMIDs or null

addNotOverriddenDependency

public void addNotOverriddenDependency(RVMMethod source,
                                       int dependent_cmid)

Records that if a particular RVMMethod method is ever overridden, then the CompiledMethod encoded by the cmid must be invalidated.

Parameters:

source - a method

dependent_cmid - id of the method that must be invalidated

removeNotOverriddenDependency

public void removeNotOverriddenDependency(RVMMethod source,
                                          int dependent_cmid)

Deletes a NotOverriddenDependency. No effect if the dependency doesn't exist..

Parameters:

source - a method

dependent_cmid - id of the method that must be invalidated

removeNotOverriddenDependency

public void removeNotOverriddenDependency(RVMMethod source)

Delete all NotOverridden dependencies on the argument RVMMethod

Parameters:

source - a method

invalidatedBySubclass

public Iterator<Integer> invalidatedBySubclass(RVMClass m)

Returns an iteration of CMID's (compiled method ids) that are dependent on the argument RVMMethod not having any subclasses. If there are no dependent methods, null will be returned.

NOTE: null is used instead of EmptyIterator.getInstance as part of delicate dance to avoid recursive classloading.

Parameters:

m - a method that can be overridden

Returns:

an iterator of CMIDs or null

addNoSubclassDependency

public void addNoSubclassDependency(RVMClass source,
                                    int dependent_cmid)

Records that if a particular RVMClass ever has a subclass, then the CompiledMethod encoded by the cmid must be invalidated.

Parameters:

source - a class

dependent_cmid - id of the method that must be invalidated

removeNoSubclassDependency

public void removeNoSubclassDependency(RVMClass source,
                                       int dependent_cmid)

Delete as NoSubclassDependency. No effect if the dependency doesn't exist..

Parameters:

source - a class

dependent_cmid - id of the method that must be invalidated

removeNoSubclassDependency

public void removeNoSubclassDependency(RVMClass source)

Deletes all NoSubclass dependencies on the argument RVMClass.

Parameters:

source - class whose dependencies are to be removed

findOrCreateMethodSet

private <T> InvalidationDatabase.MethodSet findOrCreateMethodSet(HashMapRVM<T,InvalidationDatabase.MethodSet> hash,
                                                                 T key)

Looks up the MethodSet corresponding to a given key in the database.

Type Parameters:

T - type of the key in the database

Parameters:

hash - the database

key - the key

Returns:

the method set for the given key