--- old/src/share/vm/oops/klassVtable.cpp 2015-07-31 13:27:30.921975719 -0400 +++ new/src/share/vm/oops/klassVtable.cpp 2015-07-31 13:27:30.805975723 -0400 @@ -683,7 +683,6 @@ 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; } @@ -691,25 +690,42 @@ 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* class_methods, Array* default_methods, Klass* super) { if (m->is_static() || m->is_private() || m->is_overpass()) { @@ -717,44 +733,36 @@ } 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; - } - - 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) - { - 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; - } - } + // 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; } - return false; + // Check local default methods + if ((default_methods != NULL) && + (InstanceKlass::find_method(default_methods, name, signature) != NULL)) + { + 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 true; } // Scans current_interface_methods for miranda methods that do not