src/share/vm/oops/klassVtable.cpp
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@@ -681,82 +681,90 @@
// miranda methods are public abstract instance interface methods in a class's vtable
if (mhk->is_interface()) {
assert(m->is_public(), "should be public");
assert(ik()->implements_interface(method_holder) , "this class should implement the interface");
- // the search could find a miranda or a default method
if (is_miranda(m, ik()->methods(), ik()->default_methods(), ik()->super())) {
return true;
}
}
return false;
}
-// 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 superinterface default
+// Check if a method is a miranda method, given a class's methods array,
+// its default_method table and its super class.
+// "Miranda" means an abstract non-private method that would not be
+// overridden for the local class.
+// A "miranda" method should only include non-private interface
+// instance methods, i.e. not private methods, not static methods,
+// not default methods (concrete interface methods), not overpass methods.
+// If a given class already has a local (including overpass) method, a
+// default method, or any of its superclasses has the same which would have
+// overridden an abstract method, then this is not a miranda method.
+//
+// Miranda methods are checked multiple times.
+// Pass 1: during class load/class file parsing: before vtable size calculation:
+// include superinterface abstract and default methods (non-private instance).
// 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 include abstract methods.
+// During the first run, the current instanceKlass has not yet been
+// created, the superclasses and superinterfaces do have instanceKlasses
+// but may not have vtables, the default_methods list is empty, no overpasses.
+// This is seen by default method creation.
+//
+// Pass 2: 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.
-// the caller must make sure that the method belongs to an interface implemented by the class
-// Miranda methods only include public interface instance methods
-// Not private methods, not static methods, not default == concrete abstract
-// Miranda methods also do not include overpass methods in interfaces
+// as mirandas. Abstract methods may already have been handled via
+// overpasses - either local or superclass overpasses, which may be
+// in the vtable already.
+//
+// Pass 3: They are also checked by link resolution and selection,
+// for invocation on a method (not interface method) reference that
+// resolves to a method with an interface as its method_holder.
+// Used as part of walking from the bottom of the vtable to find
+// the vtable index for the miranda method.
+//
+// Part of the Miranda Rights in the US mean that if you do not have
+// an attorney one will be appointed for you.
bool klassVtable::is_miranda(Method* m, Array<Method*>* class_methods,
Array<Method*>* default_methods, Klass* super) {
if (m->is_static() || m->is_private() || m->is_overpass()) {
return false;
}
Symbol* name = m->name();
Symbol* signature = m->signature();
- Method* mo;
- 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) {
- if (super == NULL) {
- // super doesn't exist
- return true;
+ // First look in local methods to see if already covered
+ if (InstanceKlass::find_local_method(class_methods, name, signature,
+ Klass::find_overpass, Klass::skip_static, Klass::skip_private) != NULL)
+ {
+ return false;
}
- 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)
+ // Check local default methods
+ if ((default_methods != NULL) &&
+ (InstanceKlass::find_method(default_methods, name, signature) != NULL))
{
- mo = mo->method_holder()->super()->uncached_lookup_method(name, signature, Klass::find_overpass);
- }
- if (mo == NULL || mo->access_flags().is_private() ) {
- // super class hierarchy does not implement it or protection is different
- 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;
}
+
+ InstanceKlass* cursuper;
+ // Iterate on all superclasses, which should have instanceKlasses
+ // Note that we explicitly look for overpasses at each level.
+ // Overpasses may or may not exist for supers for pass 1,
+ // they should have been created for pass 2 and later.
+
+ for (cursuper = InstanceKlass::cast(super); cursuper != NULL; cursuper = (InstanceKlass*)cursuper->super())
+ {
+ if (cursuper->find_local_method(name, signature,
+ Klass::find_overpass, Klass::skip_static, Klass::skip_private) != NULL) {
+ return false;
}
}
- return false;
+ return true;
}
// Scans current_interface_methods for miranda methods that do not
// already appear in new_mirandas, or default methods, and are also not defined-and-non-private
// in super (superclass). These mirandas are added to all_mirandas if it is