8065366: Better private method resolution
Reviewed-by: hseigel, lfoltan, coleenp, ahgross
--- a/hotspot/src/share/vm/classfile/defaultMethods.cpp Sun Oct 19 20:23:12 2014 -0700
+++ b/hotspot/src/share/vm/classfile/defaultMethods.cpp Fri Dec 19 11:48:50 2014 -0800
@@ -731,10 +731,12 @@
Method* m = iklass->find_method(_method_name, _method_signature);
// private interface methods are not candidates for default methods
// invokespecial to private interface methods doesn't use default method logic
+ // private class methods are not candidates for default methods,
+ // private methods do not override default methods, so need to perform
+ // default method inheritance without including private methods
// The overpasses are your supertypes' errors, we do not include them
// future: take access controls into account for superclass methods
- if (m != NULL && !m->is_static() && !m->is_overpass() &&
- (!iklass->is_interface() || m->is_public())) {
+ if (m != NULL && !m->is_static() && !m->is_overpass() && !m->is_private()) {
if (_family == NULL) {
_family = new StatefulMethodFamily();
}
@@ -745,6 +747,9 @@
} else {
// This is the rule that methods in classes "win" (bad word) over
// methods in interfaces. This works because of single inheritance
+ // private methods in classes do not "win", they will be found
+ // first on searching, but overriding for invokevirtual needs
+ // to find default method candidates for the same signature
_family->set_target_if_empty(m);
}
}
--- a/hotspot/src/share/vm/oops/klassVtable.cpp Sun Oct 19 20:23:12 2014 -0700
+++ b/hotspot/src/share/vm/oops/klassVtable.cpp Fri Dec 19 11:48:50 2014 -0800
@@ -404,13 +404,15 @@
// get super_klass for method_holder for the found method
InstanceKlass* super_klass = super_method->method_holder();
- if (is_default
+ // private methods are also never overridden
+ if (!super_method->is_private() &&
+ (is_default
|| ((super_klass->is_override(super_method, target_loader, target_classname, THREAD))
|| ((klass->major_version() >= VTABLE_TRANSITIVE_OVERRIDE_VERSION)
&& ((super_klass = find_transitive_override(super_klass,
target_method, i, target_loader,
target_classname, THREAD))
- != (InstanceKlass*)NULL))))
+ != (InstanceKlass*)NULL)))))
{
// Package private methods always need a new entry to root their own
// overriding. They may also override other methods.
@@ -692,9 +694,15 @@
// check if a method is a miranda method, given a class's methods table,
// its default_method table and its super
// Miranda methods are calculated twice:
-// first: before vtable size calculation: including abstract and default
+// first: before vtable size calculation: including abstract and superinterface default
+// We include potential default methods to give them space in the vtable.
+// During the first run, the default_methods list is empty
// This is seen by default method creation
-// Second: recalculated during vtable initialization: only abstract
+// Second: recalculated during vtable initialization: only include abstract methods.
+// During the second run, default_methods is set up, so concrete methods from
+// superinterfaces with matching names/signatures to default_methods are already
+// in the default_methods list and do not need to be appended to the vtable
+// as mirandas
// This is seen by link resolution and selection.
// "miranda" means not static, not defined by this class.
// private methods in interfaces do not belong in the miranda list.
@@ -709,8 +717,9 @@
}
Symbol* name = m->name();
Symbol* signature = m->signature();
+ Method* mo;
- if (InstanceKlass::find_instance_method(class_methods, name, signature) == NULL) {
+ if ((mo = InstanceKlass::find_instance_method(class_methods, name, signature)) == NULL) {
// did not find it in the method table of the current class
if ((default_methods == NULL) ||
InstanceKlass::find_method(default_methods, name, signature) == NULL) {
@@ -719,7 +728,7 @@
return true;
}
- Method* mo = InstanceKlass::cast(super)->lookup_method(name, signature);
+ mo = InstanceKlass::cast(super)->lookup_method(name, signature);
while (mo != NULL && mo->access_flags().is_static()
&& mo->method_holder() != NULL
&& mo->method_holder()->super() != NULL)
@@ -731,6 +740,18 @@
return true;
}
}
+ } else {
+ // if the local class has a private method, the miranda will not
+ // override it, so a vtable slot is needed
+ if (mo->access_flags().is_private()) {
+
+ // Second round, weed out any superinterface methods that turned
+ // into default methods, i.e. were concrete not abstract in the end
+ if ((default_methods == NULL) ||
+ InstanceKlass::find_method(default_methods, name, signature) == NULL) {
+ return true;
+ }
+ }
}
return false;