1 /*
2 * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "jvm.h"
27 #include "classfile/javaClasses.hpp"
28 #include "classfile/systemDictionary.hpp"
29 #include "classfile/vmSymbols.hpp"
30 #include "interpreter/linkResolver.hpp"
31 #include "logging/log.hpp"
32 #include "logging/logStream.hpp"
33 #include "memory/metaspaceShared.hpp"
34 #include "memory/resourceArea.hpp"
35 #include "memory/universe.hpp"
36 #include "oops/instanceKlass.hpp"
37 #include "oops/klassVtable.hpp"
38 #include "oops/method.hpp"
39 #include "oops/objArrayOop.hpp"
40 #include "oops/oop.inline.hpp"
41 #include "runtime/arguments.hpp"
42 #include "runtime/flags/flagSetting.hpp"
43 #include "runtime/handles.inline.hpp"
44 #include "runtime/safepointVerifiers.hpp"
45 #include "utilities/copy.hpp"
46
47 inline InstanceKlass* klassVtable::ik() const {
48 return InstanceKlass::cast(_klass);
49 }
50
51 bool klassVtable::is_preinitialized_vtable() {
52 return _klass->is_shared() && !MetaspaceShared::remapped_readwrite();
53 }
54
55
56 // this function computes the vtable size (including the size needed for miranda
57 // methods) and the number of miranda methods in this class.
58 // Note on Miranda methods: Let's say there is a class C that implements
59 // interface I, and none of C's superclasses implements I.
60 // Let's say there is an abstract method m in I that neither C
61 // nor any of its super classes implement (i.e there is no method of any access,
62 // with the same name and signature as m), then m is a Miranda method which is
63 // entered as a public abstract method in C's vtable. From then on it should
64 // treated as any other public method in C for method over-ride purposes.
65 void klassVtable::compute_vtable_size_and_num_mirandas(
66 int* vtable_length_ret, int* num_new_mirandas,
67 GrowableArray<Method*>* all_mirandas, const Klass* super,
68 Array<Method*>* methods, AccessFlags class_flags, u2 major_version,
69 Handle classloader, Symbol* classname, Array<Klass*>* local_interfaces,
70 TRAPS) {
71 NoSafepointVerifier nsv;
72
73 // set up default result values
74 int vtable_length = 0;
75
76 // start off with super's vtable length
77 vtable_length = super == NULL ? 0 : super->vtable_length();
78
79 // go thru each method in the methods table to see if it needs a new entry
80 int len = methods->length();
81 for (int i = 0; i < len; i++) {
82 assert(methods->at(i)->is_method(), "must be a Method*");
83 methodHandle mh(THREAD, methods->at(i));
84
85 if (needs_new_vtable_entry(mh, super, classloader, classname, class_flags, major_version, THREAD)) {
86 vtable_length += vtableEntry::size(); // we need a new entry
87 }
88 }
89
90 GrowableArray<Method*> new_mirandas(20);
91 // compute the number of mirandas methods that must be added to the end
92 get_mirandas(&new_mirandas, all_mirandas, super, methods, NULL, local_interfaces,
93 class_flags.is_interface());
94 *num_new_mirandas = new_mirandas.length();
95
96 // Interfaces do not need interface methods in their vtables
97 // This includes miranda methods and during later processing, default methods
98 if (!class_flags.is_interface()) {
99 vtable_length += *num_new_mirandas * vtableEntry::size();
100 }
101
102 if (Universe::is_bootstrapping() && vtable_length == 0) {
103 // array classes don't have their superclass set correctly during
104 // bootstrapping
105 vtable_length = Universe::base_vtable_size();
106 }
107
108 if (super == NULL && vtable_length != Universe::base_vtable_size()) {
109 if (Universe::is_bootstrapping()) {
110 // Someone is attempting to override java.lang.Object incorrectly on the
111 // bootclasspath. The JVM cannot recover from this error including throwing
112 // an exception
113 vm_exit_during_initialization("Incompatible definition of java.lang.Object");
114 } else {
115 // Someone is attempting to redefine java.lang.Object incorrectly. The
116 // only way this should happen is from
117 // SystemDictionary::resolve_from_stream(), which will detect this later
118 // and throw a security exception. So don't assert here to let
119 // the exception occur.
120 vtable_length = Universe::base_vtable_size();
121 }
122 }
123 assert(vtable_length % vtableEntry::size() == 0, "bad vtable length");
124 assert(vtable_length >= Universe::base_vtable_size(), "vtable too small");
125
126 *vtable_length_ret = vtable_length;
127 }
128
129 int klassVtable::index_of(Method* m, int len) const {
130 assert(m->has_vtable_index(), "do not ask this of non-vtable methods");
131 return m->vtable_index();
132 }
133
134 // Copy super class's vtable to the first part (prefix) of this class's vtable,
135 // and return the number of entries copied. Expects that 'super' is the Java
136 // super class (arrays can have "array" super classes that must be skipped).
137 int klassVtable::initialize_from_super(Klass* super) {
138 if (super == NULL) {
139 return 0;
140 } else if (is_preinitialized_vtable()) {
141 // A shared class' vtable is preinitialized at dump time. No need to copy
142 // methods from super class for shared class, as that was already done
143 // during archiving time. However, if Jvmti has redefined a class,
144 // copy super class's vtable in case the super class has changed.
145 return super->vtable().length();
146 } else {
147 // copy methods from superKlass
148 klassVtable superVtable = super->vtable();
149 assert(superVtable.length() <= _length, "vtable too short");
150 #ifdef ASSERT
151 superVtable.verify(tty, true);
152 #endif
153 superVtable.copy_vtable_to(table());
154 if (log_develop_is_enabled(Trace, vtables)) {
155 ResourceMark rm;
156 log_develop_trace(vtables)("copy vtable from %s to %s size %d",
157 super->internal_name(), klass()->internal_name(),
158 _length);
159 }
160 return superVtable.length();
161 }
162 }
163
164 //
165 // Revised lookup semantics introduced 1.3 (Kestrel beta)
166 void klassVtable::initialize_vtable(bool checkconstraints, TRAPS) {
167
168 // Note: Arrays can have intermediate array supers. Use java_super to skip them.
169 Klass* super = _klass->java_super();
170 int nofNewEntries = 0;
171
172 bool is_shared = _klass->is_shared();
173
174 if (!_klass->is_array_klass()) {
175 ResourceMark rm(THREAD);
176 log_develop_debug(vtables)("Initializing: %s", _klass->name()->as_C_string());
177 }
178
179 #ifdef ASSERT
180 oop* end_of_obj = (oop*)_klass + _klass->size();
181 oop* end_of_vtable = (oop*)&table()[_length];
182 assert(end_of_vtable <= end_of_obj, "vtable extends beyond end");
183 #endif
184
185 if (Universe::is_bootstrapping()) {
186 assert(!is_shared, "sanity");
187 // just clear everything
188 for (int i = 0; i < _length; i++) table()[i].clear();
189 return;
190 }
191
192 int super_vtable_len = initialize_from_super(super);
193 if (_klass->is_array_klass()) {
194 assert(super_vtable_len == _length, "arrays shouldn't introduce new methods");
195 } else {
196 assert(_klass->is_instance_klass(), "must be InstanceKlass");
197
198 Array<Method*>* methods = ik()->methods();
199 int len = methods->length();
200 int initialized = super_vtable_len;
201
202 // Check each of this class's methods against super;
203 // if override, replace in copy of super vtable, otherwise append to end
204 for (int i = 0; i < len; i++) {
205 // update_inherited_vtable can stop for gc - ensure using handles
206 HandleMark hm(THREAD);
207 assert(methods->at(i)->is_method(), "must be a Method*");
208 methodHandle mh(THREAD, methods->at(i));
209
210 bool needs_new_entry = update_inherited_vtable(ik(), mh, super_vtable_len, -1, checkconstraints, CHECK);
211
212 if (needs_new_entry) {
213 put_method_at(mh(), initialized);
214 mh()->set_vtable_index(initialized); // set primary vtable index
215 initialized++;
216 }
217 }
218
219 // update vtable with default_methods
220 Array<Method*>* default_methods = ik()->default_methods();
221 if (default_methods != NULL) {
222 len = default_methods->length();
223 if (len > 0) {
224 Array<int>* def_vtable_indices = NULL;
225 if ((def_vtable_indices = ik()->default_vtable_indices()) == NULL) {
226 assert(!is_shared, "shared class def_vtable_indices does not exist");
227 def_vtable_indices = ik()->create_new_default_vtable_indices(len, CHECK);
228 } else {
229 assert(def_vtable_indices->length() == len, "reinit vtable len?");
230 }
231 for (int i = 0; i < len; i++) {
232 HandleMark hm(THREAD);
233 assert(default_methods->at(i)->is_method(), "must be a Method*");
234 methodHandle mh(THREAD, default_methods->at(i));
235 assert(!mh->is_private(), "private interface method in the default method list");
236 bool needs_new_entry = update_inherited_vtable(ik(), mh, super_vtable_len, i, checkconstraints, CHECK);
237
238 // needs new entry
239 if (needs_new_entry) {
240 put_method_at(mh(), initialized);
241 if (is_preinitialized_vtable()) {
242 // At runtime initialize_vtable is rerun for a shared class
243 // (loaded by the non-boot loader) as part of link_class_impl().
244 // The dumptime vtable index should be the same as the runtime index.
245 assert(def_vtable_indices->at(i) == initialized,
246 "dump time vtable index is different from runtime index");
247 } else {
248 def_vtable_indices->at_put(i, initialized); //set vtable index
249 }
250 initialized++;
251 }
252 }
253 }
254 }
255
256 // add miranda methods; it will also return the updated initialized
257 // Interfaces do not need interface methods in their vtables
258 // This includes miranda methods and during later processing, default methods
259 if (!ik()->is_interface()) {
260 initialized = fill_in_mirandas(initialized);
261 }
262
263 // In class hierarchies where the accessibility is not increasing (i.e., going from private ->
264 // package_private -> public/protected), the vtable might actually be smaller than our initial
265 // calculation, for classfile versions for which we do not do transitive override
266 // calculations.
267 if (ik()->major_version() >= VTABLE_TRANSITIVE_OVERRIDE_VERSION) {
268 assert(initialized == _length, "vtable initialization failed");
269 } else {
270 assert(initialized <= _length, "vtable initialization failed");
271 for(;initialized < _length; initialized++) {
272 table()[initialized].clear();
273 }
274 }
275 NOT_PRODUCT(verify(tty, true));
276 }
277 }
278
279 // Called for cases where a method does not override its superclass' vtable entry
280 // For bytecodes not produced by javac together it is possible that a method does not override
281 // the superclass's method, but might indirectly override a super-super class's vtable entry
282 // If none found, return a null superk, else return the superk of the method this does override
283 // For public and protected methods: if they override a superclass, they will
284 // also be overridden themselves appropriately.
285 // Private methods do not override and are not overridden.
286 // Package Private methods are trickier:
287 // e.g. P1.A, pub m
288 // P2.B extends A, package private m
289 // P1.C extends B, public m
290 // P1.C.m needs to override P1.A.m and can not override P2.B.m
291 // Therefore: all package private methods need their own vtable entries for
292 // them to be the root of an inheritance overriding decision
293 // Package private methods may also override other vtable entries
294 InstanceKlass* klassVtable::find_transitive_override(InstanceKlass* initialsuper, const methodHandle& target_method,
295 int vtable_index, Handle target_loader, Symbol* target_classname, Thread * THREAD) {
296 InstanceKlass* superk = initialsuper;
297 while (superk != NULL && superk->super() != NULL) {
298 InstanceKlass* supersuperklass = InstanceKlass::cast(superk->super());
299 klassVtable ssVtable = supersuperklass->vtable();
300 if (vtable_index < ssVtable.length()) {
301 Method* super_method = ssVtable.method_at(vtable_index);
302 #ifndef PRODUCT
303 Symbol* name= target_method()->name();
304 Symbol* signature = target_method()->signature();
305 assert(super_method->name() == name && super_method->signature() == signature, "vtable entry name/sig mismatch");
306 #endif
307 if (supersuperklass->is_override(super_method, target_loader, target_classname, THREAD)) {
308 if (log_develop_is_enabled(Trace, vtables)) {
309 ResourceMark rm(THREAD);
310 LogTarget(Trace, vtables) lt;
311 LogStream ls(lt);
312 char* sig = target_method()->name_and_sig_as_C_string();
313 ls.print("transitive overriding superclass %s with %s index %d, original flags: ",
314 supersuperklass->internal_name(),
315 sig, vtable_index);
316 super_method->print_linkage_flags(&ls);
317 ls.print("overriders flags: ");
318 target_method->print_linkage_flags(&ls);
319 ls.cr();
320 }
321
322 break; // return found superk
323 }
324 } else {
325 // super class has no vtable entry here, stop transitive search
326 superk = (InstanceKlass*)NULL;
327 break;
328 }
329 // if no override found yet, continue to search up
330 superk = superk->super() == NULL ? NULL : InstanceKlass::cast(superk->super());
331 }
332
333 return superk;
334 }
335
336 static void log_vtables(int i, bool overrides, const methodHandle& target_method,
337 Klass* target_klass, Method* super_method,
338 Thread* thread) {
339 #ifndef PRODUCT
340 if (log_develop_is_enabled(Trace, vtables)) {
341 ResourceMark rm(thread);
342 LogTarget(Trace, vtables) lt;
343 LogStream ls(lt);
344 char* sig = target_method()->name_and_sig_as_C_string();
345 if (overrides) {
346 ls.print("overriding with %s index %d, original flags: ",
347 sig, i);
348 } else {
349 ls.print("NOT overriding with %s index %d, original flags: ",
350 sig, i);
351 }
352 super_method->print_linkage_flags(&ls);
353 ls.print("overriders flags: ");
354 target_method->print_linkage_flags(&ls);
355 ls.cr();
356 }
357 #endif
358 }
359
360 // Update child's copy of super vtable for overrides
361 // OR return true if a new vtable entry is required.
362 // Only called for InstanceKlass's, i.e. not for arrays
363 // If that changed, could not use _klass as handle for klass
364 bool klassVtable::update_inherited_vtable(InstanceKlass* klass, const methodHandle& target_method,
365 int super_vtable_len, int default_index,
366 bool checkconstraints, TRAPS) {
367 ResourceMark rm;
368 bool allocate_new = true;
369 assert(klass->is_instance_klass(), "must be InstanceKlass");
370
371 Array<int>* def_vtable_indices = NULL;
372 bool is_default = false;
373
374 // default methods are non-private concrete methods in superinterfaces which are added
375 // to the vtable with their real method_holder.
376 // Since vtable and itable indices share the same storage, don't touch
377 // the default method's real vtable/itable index.
378 // default_vtable_indices stores the vtable value relative to this inheritor
379 if (default_index >= 0 ) {
380 is_default = true;
381 def_vtable_indices = klass->default_vtable_indices();
382 assert(!target_method()->is_private(), "private interface method flagged as default");
383 assert(def_vtable_indices != NULL, "def vtable alloc?");
384 assert(default_index <= def_vtable_indices->length(), "def vtable len?");
385 } else {
386 assert(klass == target_method()->method_holder(), "caller resp.");
387 // Initialize the method's vtable index to "nonvirtual".
388 // If we allocate a vtable entry, we will update it to a non-negative number.
389 target_method()->set_vtable_index(Method::nonvirtual_vtable_index);
390 }
391
392 // Static and <init> methods are never in
393 if (target_method()->is_static() || target_method()->name() == vmSymbols::object_initializer_name()) {
394 return false;
395 }
396
397 if (target_method->is_final_method(klass->access_flags())) {
398 // a final method never needs a new entry; final methods can be statically
399 // resolved and they have to be present in the vtable only if they override
400 // a super's method, in which case they re-use its entry
401 allocate_new = false;
402 } else if (klass->is_interface()) {
403 allocate_new = false; // see note below in needs_new_vtable_entry
404 // An interface never allocates new vtable slots, only inherits old ones.
405 // This method will either be assigned its own itable index later,
406 // or be assigned an inherited vtable index in the loop below.
407 // default methods inherited by classes store their vtable indices
408 // in the inheritor's default_vtable_indices.
409 // default methods inherited by interfaces may already have a
410 // valid itable index, if so, don't change it.
411 // Overpass methods in an interface will be assigned an itable index later
412 // by an inheriting class.
413 // Private interface methods have no itable index and are always invoked nonvirtually,
414 // so they retain their nonvirtual_vtable_index value, and therefore can_be_statically_bound()
415 // will return true.
416 if ((!is_default || !target_method()->has_itable_index()) && !target_method()->is_private()) {
417 target_method()->set_vtable_index(Method::pending_itable_index);
418 }
419 }
420
421 // we need a new entry if there is no superclass
422 Klass* super = klass->super();
423 if (super == NULL) {
424 return allocate_new;
425 }
426
427 // private methods in classes always have a new entry in the vtable
428 // specification interpretation since classic has
429 // private methods not overriding
430 // JDK8 adds private methods in interfaces which require invokespecial
431 if (target_method()->is_private()) {
432 return allocate_new;
433 }
434
435 // search through the vtable and update overridden entries
436 // Since check_signature_loaders acquires SystemDictionary_lock
437 // which can block for gc, once we are in this loop, use handles
438 // For classfiles built with >= jdk7, we now look for transitive overrides
439
440 Symbol* name = target_method()->name();
441 Symbol* signature = target_method()->signature();
442
443 Klass* target_klass = target_method()->method_holder();
444 if (target_klass == NULL) {
445 target_klass = _klass;
446 }
447
448 Handle target_loader(THREAD, target_klass->class_loader());
449
450 Symbol* target_classname = target_klass->name();
451 for(int i = 0; i < super_vtable_len; i++) {
452 Method* super_method;
453 if (is_preinitialized_vtable()) {
454 // If this is a shared class, the vtable is already in the final state (fully
455 // initialized). Need to look at the super's vtable.
456 klassVtable superVtable = super->vtable();
457 super_method = superVtable.method_at(i);
458 } else {
459 super_method = method_at(i);
460 }
461 // Check if method name matches. Ignore match if klass is an interface and the
462 // matching method is a non-public java.lang.Object method. (See JVMS 5.4.3.4)
463 // This is safe because the method at this slot should never get invoked.
464 // (TBD: put in a method to throw NoSuchMethodError if this slot is ever used.)
465 if (super_method->name() == name && super_method->signature() == signature &&
466 (!_klass->is_interface() ||
467 !SystemDictionary::is_nonpublic_Object_method(super_method))) {
468
469 // get super_klass for method_holder for the found method
470 InstanceKlass* super_klass = super_method->method_holder();
471
472 // Whether the method is being overridden
473 bool overrides = false;
474
475 // private methods are also never overridden
476 if (!super_method->is_private() &&
477 (is_default
478 || ((super_klass->is_override(super_method, target_loader, target_classname, THREAD))
479 || ((klass->major_version() >= VTABLE_TRANSITIVE_OVERRIDE_VERSION)
480 && ((super_klass = find_transitive_override(super_klass,
481 target_method, i, target_loader,
482 target_classname, THREAD))
483 != (InstanceKlass*)NULL)))))
484 {
485 // Package private methods always need a new entry to root their own
486 // overriding. They may also override other methods.
487 if (!target_method()->is_package_private()) {
488 allocate_new = false;
489 }
490
491 // Do not check loader constraints for overpass methods because overpass
492 // methods are created by the jvm to throw exceptions.
493 if (checkconstraints && !target_method()->is_overpass()) {
494 // Override vtable entry if passes loader constraint check
495 // if loader constraint checking requested
496 // No need to visit his super, since he and his super
497 // have already made any needed loader constraints.
498 // Since loader constraints are transitive, it is enough
499 // to link to the first super, and we get all the others.
500 Handle super_loader(THREAD, super_klass->class_loader());
501
502 if (!oopDesc::equals(target_loader(), super_loader())) {
503 ResourceMark rm(THREAD);
504 Symbol* failed_type_symbol =
505 SystemDictionary::check_signature_loaders(signature, target_loader,
506 super_loader, true,
507 CHECK_(false));
508 if (failed_type_symbol != NULL) {
509 ResourceMark rm(THREAD);
510 stringStream ss;
511 ss.print("loader constraint violation for class %s: when selecting "
512 "overriding method %s the class loader %s of the "
513 "selected method's type %s, and the class loader %s for its super "
514 "type %s have different Class objects for the type %s used in the signature",
515 klass->external_name(),
516 target_method()->name_and_sig_as_C_string(),
517 java_lang_ClassLoader::describe_external(target_loader()),
518 target_klass->external_name(),
519 java_lang_ClassLoader::describe_external(super_loader()),
520 super_klass->external_name(),
521 failed_type_symbol->as_klass_external_name());
522 THROW_MSG_(vmSymbols::java_lang_LinkageError(), ss.as_string(), false);
523 }
524 }
525 }
526
527 put_method_at(target_method(), i);
528 overrides = true;
529 if (!is_default) {
530 target_method()->set_vtable_index(i);
531 } else {
532 if (def_vtable_indices != NULL) {
533 if (is_preinitialized_vtable()) {
534 // At runtime initialize_vtable is rerun as part of link_class_impl()
535 // for a shared class loaded by the non-boot loader.
536 // The dumptime vtable index should be the same as the runtime index.
537 assert(def_vtable_indices->at(default_index) == i,
538 "dump time vtable index is different from runtime index");
539 } else {
540 def_vtable_indices->at_put(default_index, i);
541 }
542 }
543 assert(super_method->is_default_method() || super_method->is_overpass()
544 || super_method->is_abstract(), "default override error");
545 }
546 } else {
547 overrides = false;
548 }
549 log_vtables(i, overrides, target_method, target_klass, super_method, THREAD);
550 }
551 }
552 return allocate_new;
553 }
554
555 void klassVtable::put_method_at(Method* m, int index) {
556 if (is_preinitialized_vtable()) {
557 // At runtime initialize_vtable is rerun as part of link_class_impl()
558 // for shared class loaded by the non-boot loader to obtain the loader
559 // constraints based on the runtime classloaders' context. The dumptime
560 // method at the vtable index should be the same as the runtime method.
561 assert(table()[index].method() == m,
562 "archived method is different from the runtime method");
563 } else {
564 if (log_develop_is_enabled(Trace, vtables)) {
565 ResourceMark rm;
566 LogTarget(Trace, vtables) lt;
567 LogStream ls(lt);
568 const char* sig = (m != NULL) ? m->name_and_sig_as_C_string() : "<NULL>";
569 ls.print("adding %s at index %d, flags: ", sig, index);
570 if (m != NULL) {
571 m->print_linkage_flags(&ls);
572 }
573 ls.cr();
574 }
575 table()[index].set(m);
576 }
577 }
578
579 // Find out if a method "m" with superclass "super", loader "classloader" and
580 // name "classname" needs a new vtable entry. Let P be a class package defined
581 // by "classloader" and "classname".
582 // NOTE: The logic used here is very similar to the one used for computing
583 // the vtables indices for a method. We cannot directly use that function because,
584 // we allocate the InstanceKlass at load time, and that requires that the
585 // superclass has been loaded.
586 // However, the vtable entries are filled in at link time, and therefore
587 // the superclass' vtable may not yet have been filled in.
588 bool klassVtable::needs_new_vtable_entry(const methodHandle& target_method,
589 const Klass* super,
590 Handle classloader,
591 Symbol* classname,
592 AccessFlags class_flags,
593 u2 major_version,
594 TRAPS) {
595 if (class_flags.is_interface()) {
596 // Interfaces do not use vtables, except for java.lang.Object methods,
597 // so there is no point to assigning
598 // a vtable index to any of their local methods. If we refrain from doing this,
599 // we can use Method::_vtable_index to hold the itable index
600 return false;
601 }
602
603 if (target_method->is_final_method(class_flags) ||
604 // a final method never needs a new entry; final methods can be statically
605 // resolved and they have to be present in the vtable only if they override
606 // a super's method, in which case they re-use its entry
607 (target_method()->is_static()) ||
608 // static methods don't need to be in vtable
609 (target_method()->name() == vmSymbols::object_initializer_name())
610 // <init> is never called dynamically-bound
611 ) {
612 return false;
613 }
614
615 // Concrete interface methods do not need new entries, they override
616 // abstract method entries using default inheritance rules
617 if (target_method()->method_holder() != NULL &&
618 target_method()->method_holder()->is_interface() &&
619 !target_method()->is_abstract()) {
620 assert(target_method()->is_default_method() || target_method()->is_private(),
621 "unexpected interface method type");
622 return false;
623 }
624
625 // we need a new entry if there is no superclass
626 if (super == NULL) {
627 return true;
628 }
629
630 // private methods in classes always have a new entry in the vtable.
631 // Specification interpretation since classic has private methods not overriding.
632 if (target_method()->is_private()) {
633 return true;
634 }
635
636 // Package private methods always need a new entry to root their own
637 // overriding. This allows transitive overriding to work.
638 if (target_method()->is_package_private()) {
639 return true;
640 }
641
642 // search through the super class hierarchy to see if we need
643 // a new entry
644 ResourceMark rm;
645 Symbol* name = target_method()->name();
646 Symbol* signature = target_method()->signature();
647 const Klass* k = super;
648 Method* super_method = NULL;
649 InstanceKlass *holder = NULL;
650 Method* recheck_method = NULL;
651 while (k != NULL) {
652 // lookup through the hierarchy for a method with matching name and sign.
653 super_method = InstanceKlass::cast(k)->lookup_method(name, signature);
654 if (super_method == NULL) {
655 break; // we still have to search for a matching miranda method
656 }
657 // get the class holding the matching method
658 // make sure you use that class for is_override
659 InstanceKlass* superk = super_method->method_holder();
660 // we want only instance method matches
661 // pretend private methods are not in the super vtable
662 // since we do override around them: e.g. a.m pub/b.m private/c.m pub,
663 // ignore private, c.m pub does override a.m pub
664 // For classes that were not javac'd together, we also do transitive overriding around
665 // methods that have less accessibility
666 if ((!super_method->is_static()) &&
667 (!super_method->is_private())) {
668 if (superk->is_override(super_method, classloader, classname, THREAD)) {
669 return false;
670 // else keep looking for transitive overrides
671 }
672 }
673
674 // Start with lookup result and continue to search up, for versions supporting transitive override
675 if (major_version >= VTABLE_TRANSITIVE_OVERRIDE_VERSION) {
676 k = superk->super(); // haven't found an override match yet; continue to look
677 } else {
678 break;
679 }
680 }
681
682 // if the target method is public or protected it may have a matching
683 // miranda method in the super, whose entry it should re-use.
684 // Actually, to handle cases that javac would not generate, we need
685 // this check for all access permissions.
686 const InstanceKlass *sk = InstanceKlass::cast(super);
687 if (sk->has_miranda_methods()) {
688 if (sk->lookup_method_in_all_interfaces(name, signature, Klass::find_defaults) != NULL) {
689 return false; // found a matching miranda; we do not need a new entry
690 }
691 }
692 return true; // found no match; we need a new entry
693 }
694
695 // Support for miranda methods
696
697 // get the vtable index of a miranda method with matching "name" and "signature"
698 int klassVtable::index_of_miranda(Symbol* name, Symbol* signature) {
699 // search from the bottom, might be faster
700 for (int i = (length() - 1); i >= 0; i--) {
701 Method* m = table()[i].method();
702 if (is_miranda_entry_at(i) &&
703 m->name() == name && m->signature() == signature) {
704 return i;
705 }
706 }
707 return Method::invalid_vtable_index;
708 }
709
710 // check if an entry at an index is miranda
711 // requires that method m at entry be declared ("held") by an interface.
712 bool klassVtable::is_miranda_entry_at(int i) {
713 Method* m = method_at(i);
714 Klass* method_holder = m->method_holder();
715 InstanceKlass *mhk = InstanceKlass::cast(method_holder);
716
717 // miranda methods are public abstract instance interface methods in a class's vtable
718 if (mhk->is_interface()) {
719 assert(m->is_public(), "should be public");
720 assert(ik()->implements_interface(method_holder) , "this class should implement the interface");
721 if (is_miranda(m, ik()->methods(), ik()->default_methods(), ik()->super(), klass()->is_interface())) {
722 return true;
723 }
724 }
725 return false;
726 }
727
728 // Check if a method is a miranda method, given a class's methods array,
729 // its default_method table and its super class.
730 // "Miranda" means an abstract non-private method that would not be
731 // overridden for the local class.
732 // A "miranda" method should only include non-private interface
733 // instance methods, i.e. not private methods, not static methods,
734 // not default methods (concrete interface methods), not overpass methods.
735 // If a given class already has a local (including overpass) method, a
736 // default method, or any of its superclasses has the same which would have
737 // overridden an abstract method, then this is not a miranda method.
738 //
739 // Miranda methods are checked multiple times.
740 // Pass 1: during class load/class file parsing: before vtable size calculation:
741 // include superinterface abstract and default methods (non-private instance).
742 // We include potential default methods to give them space in the vtable.
743 // During the first run, the current instanceKlass has not yet been
744 // created, the superclasses and superinterfaces do have instanceKlasses
745 // but may not have vtables, the default_methods list is empty, no overpasses.
746 // Default method generation uses the all_mirandas array as the starter set for
747 // maximally-specific default method calculation. So, for both classes and
748 // interfaces, it is necessary that the first pass will find all non-private
749 // interface instance methods, whether or not they are concrete.
750 //
751 // Pass 2: recalculated during vtable initialization: only include abstract methods.
752 // The goal of pass 2 is to walk through the superinterfaces to see if any of
753 // the superinterface methods (which were all abstract pre-default methods)
754 // need to be added to the vtable.
755 // With the addition of default methods, we have three new challenges:
756 // overpasses, static interface methods and private interface methods.
757 // Static and private interface methods do not get added to the vtable and
758 // are not seen by the method resolution process, so we skip those.
759 // Overpass methods are already in the vtable, so vtable lookup will
760 // find them and we don't need to add a miranda method to the end of
761 // the vtable. So we look for overpass methods and if they are found we
762 // return false. Note that we inherit our superclasses vtable, so
763 // the superclass' search also needs to use find_overpass so that if
764 // one is found we return false.
765 // False means - we don't need a miranda method added to the vtable.
766 //
767 // During the second run, default_methods is set up, so concrete methods from
768 // superinterfaces with matching names/signatures to default_methods are already
769 // in the default_methods list and do not need to be appended to the vtable
770 // as mirandas. Abstract methods may already have been handled via
771 // overpasses - either local or superclass overpasses, which may be
772 // in the vtable already.
773 //
774 // Pass 3: They are also checked by link resolution and selection,
775 // for invocation on a method (not interface method) reference that
776 // resolves to a method with an interface as its method_holder.
777 // Used as part of walking from the bottom of the vtable to find
778 // the vtable index for the miranda method.
779 //
780 // Part of the Miranda Rights in the US mean that if you do not have
781 // an attorney one will be appointed for you.
782 bool klassVtable::is_miranda(Method* m, Array<Method*>* class_methods,
783 Array<Method*>* default_methods, const Klass* super,
784 bool is_interface) {
785 if (m->is_static() || m->is_private() || m->is_overpass()) {
786 return false;
787 }
788 Symbol* name = m->name();
789 Symbol* signature = m->signature();
790
791 // First look in local methods to see if already covered
792 if (InstanceKlass::find_local_method(class_methods, name, signature,
793 Klass::find_overpass, Klass::skip_static, Klass::skip_private) != NULL)
794 {
795 return false;
796 }
797
798 // Check local default methods
799 if ((default_methods != NULL) &&
800 (InstanceKlass::find_method(default_methods, name, signature) != NULL))
801 {
802 return false;
803 }
804
805 // Iterate on all superclasses, which should be InstanceKlasses.
806 // Note that we explicitly look for overpasses at each level.
807 // Overpasses may or may not exist for supers for pass 1,
808 // they should have been created for pass 2 and later.
809
810 for (const Klass* cursuper = super; cursuper != NULL; cursuper = cursuper->super())
811 {
812 Method* found_mth = InstanceKlass::cast(cursuper)->find_local_method(name, signature,
813 Klass::find_overpass, Klass::skip_static, Klass::skip_private);
814 // Ignore non-public methods in java.lang.Object if klass is an interface.
815 if (found_mth != NULL && (!is_interface ||
816 !SystemDictionary::is_nonpublic_Object_method(found_mth))) {
817 return false;
818 }
819 }
820
821 return true;
822 }
823
824 // Scans current_interface_methods for miranda methods that do not
825 // already appear in new_mirandas, or default methods, and are also not defined-and-non-private
826 // in super (superclass). These mirandas are added to all_mirandas if it is
827 // not null; in addition, those that are not duplicates of miranda methods
828 // inherited by super from its interfaces are added to new_mirandas.
829 // Thus, new_mirandas will be the set of mirandas that this class introduces,
830 // all_mirandas will be the set of all mirandas applicable to this class
831 // including all defined in superclasses.
832 void klassVtable::add_new_mirandas_to_lists(
833 GrowableArray<Method*>* new_mirandas, GrowableArray<Method*>* all_mirandas,
834 Array<Method*>* current_interface_methods, Array<Method*>* class_methods,
835 Array<Method*>* default_methods, const Klass* super, bool is_interface) {
836
837 // iterate thru the current interface's method to see if it a miranda
838 int num_methods = current_interface_methods->length();
839 for (int i = 0; i < num_methods; i++) {
840 Method* im = current_interface_methods->at(i);
841 bool is_duplicate = false;
842 int num_of_current_mirandas = new_mirandas->length();
843 // check for duplicate mirandas in different interfaces we implement
844 for (int j = 0; j < num_of_current_mirandas; j++) {
845 Method* miranda = new_mirandas->at(j);
846 if ((im->name() == miranda->name()) &&
847 (im->signature() == miranda->signature())) {
848 is_duplicate = true;
849 break;
850 }
851 }
852
853 if (!is_duplicate) { // we don't want duplicate miranda entries in the vtable
854 if (is_miranda(im, class_methods, default_methods, super, is_interface)) { // is it a miranda at all?
855 const InstanceKlass *sk = InstanceKlass::cast(super);
856 // check if it is a duplicate of a super's miranda
857 if (sk->lookup_method_in_all_interfaces(im->name(), im->signature(), Klass::find_defaults) == NULL) {
858 new_mirandas->append(im);
859 }
860 if (all_mirandas != NULL) {
861 all_mirandas->append(im);
862 }
863 }
864 }
865 }
866 }
867
868 void klassVtable::get_mirandas(GrowableArray<Method*>* new_mirandas,
869 GrowableArray<Method*>* all_mirandas,
870 const Klass* super,
871 Array<Method*>* class_methods,
872 Array<Method*>* default_methods,
873 Array<Klass*>* local_interfaces,
874 bool is_interface) {
875 assert((new_mirandas->length() == 0) , "current mirandas must be 0");
876
877 // iterate thru the local interfaces looking for a miranda
878 int num_local_ifs = local_interfaces->length();
879 for (int i = 0; i < num_local_ifs; i++) {
880 InstanceKlass *ik = InstanceKlass::cast(local_interfaces->at(i));
881 add_new_mirandas_to_lists(new_mirandas, all_mirandas,
882 ik->methods(), class_methods,
883 default_methods, super, is_interface);
884 // iterate thru each local's super interfaces
885 Array<Klass*>* super_ifs = ik->transitive_interfaces();
886 int num_super_ifs = super_ifs->length();
887 for (int j = 0; j < num_super_ifs; j++) {
888 InstanceKlass *sik = InstanceKlass::cast(super_ifs->at(j));
889 add_new_mirandas_to_lists(new_mirandas, all_mirandas,
890 sik->methods(), class_methods,
891 default_methods, super, is_interface);
892 }
893 }
894 }
895
896 // Discover miranda methods ("miranda" = "interface abstract, no binding"),
897 // and append them into the vtable starting at index initialized,
898 // return the new value of initialized.
899 // Miranda methods use vtable entries, but do not get assigned a vtable_index
900 // The vtable_index is discovered by searching from the end of the vtable
901 int klassVtable::fill_in_mirandas(int initialized) {
902 GrowableArray<Method*> mirandas(20);
903 get_mirandas(&mirandas, NULL, ik()->super(), ik()->methods(),
904 ik()->default_methods(), ik()->local_interfaces(),
905 klass()->is_interface());
906 for (int i = 0; i < mirandas.length(); i++) {
907 if (log_develop_is_enabled(Trace, vtables)) {
908 Method* meth = mirandas.at(i);
909 ResourceMark rm(Thread::current());
910 LogTarget(Trace, vtables) lt;
911 LogStream ls(lt);
912 if (meth != NULL) {
913 char* sig = meth->name_and_sig_as_C_string();
914 ls.print("fill in mirandas with %s index %d, flags: ",
915 sig, initialized);
916 meth->print_linkage_flags(&ls);
917 ls.cr();
918 }
919 }
920 put_method_at(mirandas.at(i), initialized);
921 ++initialized;
922 }
923 return initialized;
924 }
925
926 // Copy this class's vtable to the vtable beginning at start.
927 // Used to copy superclass vtable to prefix of subclass's vtable.
928 void klassVtable::copy_vtable_to(vtableEntry* start) {
929 Copy::disjoint_words((HeapWord*)table(), (HeapWord*)start, _length * vtableEntry::size());
930 }
931
932 #if INCLUDE_JVMTI
933 bool klassVtable::adjust_default_method(int vtable_index, Method* old_method, Method* new_method) {
934 // If old_method is default, find this vtable index in default_vtable_indices
935 // and replace that method in the _default_methods list
936 bool updated = false;
937
938 Array<Method*>* default_methods = ik()->default_methods();
939 if (default_methods != NULL) {
940 int len = default_methods->length();
941 for (int idx = 0; idx < len; idx++) {
942 if (vtable_index == ik()->default_vtable_indices()->at(idx)) {
943 if (default_methods->at(idx) == old_method) {
944 default_methods->at_put(idx, new_method);
945 updated = true;
946 }
947 break;
948 }
949 }
950 }
951 return updated;
952 }
953
954 // search the vtable for uses of either obsolete or EMCP methods
955 void klassVtable::adjust_method_entries(InstanceKlass* holder, bool * trace_name_printed) {
956 int prn_enabled = 0;
957 for (int index = 0; index < length(); index++) {
958 Method* old_method = unchecked_method_at(index);
959 if (old_method == NULL || old_method->method_holder() != holder || !old_method->is_old()) {
960 continue; // skip uninteresting entries
961 }
962 assert(!old_method->is_deleted(), "vtable methods may not be deleted");
963
964 Method* new_method = holder->method_with_idnum(old_method->orig_method_idnum());
965
966 assert(new_method != NULL, "method_with_idnum() should not be NULL");
967 assert(old_method != new_method, "sanity check");
968
969 put_method_at(new_method, index);
970 // For default methods, need to update the _default_methods array
971 // which can only have one method entry for a given signature
972 bool updated_default = false;
973 if (old_method->is_default_method()) {
974 updated_default = adjust_default_method(index, old_method, new_method);
975 }
976
977 if (log_is_enabled(Info, redefine, class, update)) {
978 ResourceMark rm;
979 if (!(*trace_name_printed)) {
980 log_info(redefine, class, update)
981 ("adjust: klassname=%s for methods from name=%s",
982 _klass->external_name(), old_method->method_holder()->external_name());
983 *trace_name_printed = true;
984 }
985 log_debug(redefine, class, update, vtables)
986 ("vtable method update: %s(%s), updated default = %s",
987 new_method->name()->as_C_string(), new_method->signature()->as_C_string(), updated_default ? "true" : "false");
988 }
989 }
990 }
991
992 // a vtable should never contain old or obsolete methods
993 bool klassVtable::check_no_old_or_obsolete_entries() {
994 for (int i = 0; i < length(); i++) {
995 Method* m = unchecked_method_at(i);
996 if (m != NULL &&
997 (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) {
998 return false;
999 }
1000 }
1001 return true;
1002 }
1003
1004 void klassVtable::dump_vtable() {
1005 tty->print_cr("vtable dump --");
1006 for (int i = 0; i < length(); i++) {
1007 Method* m = unchecked_method_at(i);
1008 if (m != NULL) {
1009 tty->print(" (%5d) ", i);
1010 m->access_flags().print_on(tty);
1011 if (m->is_default_method()) {
1012 tty->print("default ");
1013 }
1014 if (m->is_overpass()) {
1015 tty->print("overpass");
1016 }
1017 tty->print(" -- ");
1018 m->print_name(tty);
1019 tty->cr();
1020 }
1021 }
1022 }
1023 #endif // INCLUDE_JVMTI
1024
1025 // CDS/RedefineClasses support - clear vtables so they can be reinitialized
1026 void klassVtable::clear_vtable() {
1027 for (int i = 0; i < _length; i++) table()[i].clear();
1028 }
1029
1030 bool klassVtable::is_initialized() {
1031 return _length == 0 || table()[0].method() != NULL;
1032 }
1033
1034 //-----------------------------------------------------------------------------------------
1035 // Itable code
1036
1037 // Initialize a itableMethodEntry
1038 void itableMethodEntry::initialize(Method* m) {
1039 if (m == NULL) return;
1040
1041 #ifdef ASSERT
1042 if (MetaspaceShared::is_in_shared_metaspace((void*)&_method) &&
1043 !MetaspaceShared::remapped_readwrite()) {
1044 // At runtime initialize_itable is rerun as part of link_class_impl()
1045 // for a shared class loaded by the non-boot loader.
1046 // The dumptime itable method entry should be the same as the runtime entry.
1047 assert(_method == m, "sanity");
1048 }
1049 #endif
1050 _method = m;
1051 }
1052
1053 klassItable::klassItable(InstanceKlass* klass) {
1054 _klass = klass;
1055
1056 if (klass->itable_length() > 0) {
1057 itableOffsetEntry* offset_entry = (itableOffsetEntry*)klass->start_of_itable();
1058 if (offset_entry != NULL && offset_entry->interface_klass() != NULL) { // Check that itable is initialized
1059 // First offset entry points to the first method_entry
1060 intptr_t* method_entry = (intptr_t *)(((address)klass) + offset_entry->offset());
1061 intptr_t* end = klass->end_of_itable();
1062
1063 _table_offset = (intptr_t*)offset_entry - (intptr_t*)klass;
1064 _size_offset_table = (method_entry - ((intptr_t*)offset_entry)) / itableOffsetEntry::size();
1065 _size_method_table = (end - method_entry) / itableMethodEntry::size();
1066 assert(_table_offset >= 0 && _size_offset_table >= 0 && _size_method_table >= 0, "wrong computation");
1067 return;
1068 }
1069 }
1070
1071 // The length of the itable was either zero, or it has not yet been initialized.
1072 _table_offset = 0;
1073 _size_offset_table = 0;
1074 _size_method_table = 0;
1075 }
1076
1077 static int initialize_count = 0;
1078
1079 // Initialization
1080 void klassItable::initialize_itable(bool checkconstraints, TRAPS) {
1081 if (_klass->is_interface()) {
1082 // This needs to go after vtable indices are assigned but
1083 // before implementors need to know the number of itable indices.
1084 assign_itable_indices_for_interface(_klass);
1085 }
1086
1087 // Cannot be setup doing bootstrapping, interfaces don't have
1088 // itables, and klass with only ones entry have empty itables
1089 if (Universe::is_bootstrapping() ||
1090 _klass->is_interface() ||
1091 _klass->itable_length() == itableOffsetEntry::size()) return;
1092
1093 // There's alway an extra itable entry so we can null-terminate it.
1094 guarantee(size_offset_table() >= 1, "too small");
1095 int num_interfaces = size_offset_table() - 1;
1096 if (num_interfaces > 0) {
1097 log_develop_debug(itables)("%3d: Initializing itables for %s", ++initialize_count,
1098 _klass->name()->as_C_string());
1099
1100
1101 // Iterate through all interfaces
1102 int i;
1103 for(i = 0; i < num_interfaces; i++) {
1104 itableOffsetEntry* ioe = offset_entry(i);
1105 HandleMark hm(THREAD);
1106 Klass* interf = ioe->interface_klass();
1107 assert(interf != NULL && ioe->offset() != 0, "bad offset entry in itable");
1108 initialize_itable_for_interface(ioe->offset(), interf, checkconstraints, CHECK);
1109 }
1110
1111 }
1112 // Check that the last entry is empty
1113 itableOffsetEntry* ioe = offset_entry(size_offset_table() - 1);
1114 guarantee(ioe->interface_klass() == NULL && ioe->offset() == 0, "terminator entry missing");
1115 }
1116
1117
1118 inline bool interface_method_needs_itable_index(Method* m) {
1119 if (m->is_static()) return false; // e.g., Stream.empty
1120 if (m->is_initializer()) return false; // <init> or <clinit>
1121 if (m->is_private()) return false; // uses direct call
1122 // If an interface redeclares a method from java.lang.Object,
1123 // it should already have a vtable index, don't touch it.
1124 // e.g., CharSequence.toString (from initialize_vtable)
1125 // if (m->has_vtable_index()) return false; // NO!
1126 return true;
1127 }
1128
1129 int klassItable::assign_itable_indices_for_interface(Klass* klass) {
1130 // an interface does not have an itable, but its methods need to be numbered
1131 log_develop_debug(itables)("%3d: Initializing itable indices for interface %s",
1132 ++initialize_count, klass->name()->as_C_string());
1133 Array<Method*>* methods = InstanceKlass::cast(klass)->methods();
1134 int nof_methods = methods->length();
1135 int ime_num = 0;
1136 for (int i = 0; i < nof_methods; i++) {
1137 Method* m = methods->at(i);
1138 if (interface_method_needs_itable_index(m)) {
1139 assert(!m->is_final_method(), "no final interface methods");
1140 // If m is already assigned a vtable index, do not disturb it.
1141 if (log_develop_is_enabled(Trace, itables)) {
1142 ResourceMark rm;
1143 LogTarget(Trace, itables) lt;
1144 LogStream ls(lt);
1145 assert(m != NULL, "methods can never be null");
1146 const char* sig = m->name_and_sig_as_C_string();
1147 if (m->has_vtable_index()) {
1148 ls.print("vtable index %d for method: %s, flags: ", m->vtable_index(), sig);
1149 } else {
1150 ls.print("itable index %d for method: %s, flags: ", ime_num, sig);
1151 }
1152 m->print_linkage_flags(&ls);
1153 ls.cr();
1154 }
1155 if (!m->has_vtable_index()) {
1156 // A shared method could have an initialized itable_index that
1157 // is < 0.
1158 assert(m->vtable_index() == Method::pending_itable_index ||
1159 m->is_shared(),
1160 "set by initialize_vtable");
1161 m->set_itable_index(ime_num);
1162 // Progress to next itable entry
1163 ime_num++;
1164 }
1165 }
1166 }
1167 assert(ime_num == method_count_for_interface(klass), "proper sizing");
1168 return ime_num;
1169 }
1170
1171 int klassItable::method_count_for_interface(Klass* interf) {
1172 assert(interf->is_instance_klass(), "must be");
1173 assert(interf->is_interface(), "must be");
1174 Array<Method*>* methods = InstanceKlass::cast(interf)->methods();
1175 int nof_methods = methods->length();
1176 int length = 0;
1177 while (nof_methods > 0) {
1178 Method* m = methods->at(nof_methods-1);
1179 if (m->has_itable_index()) {
1180 length = m->itable_index() + 1;
1181 break;
1182 }
1183 nof_methods -= 1;
1184 }
1185 #ifdef ASSERT
1186 int nof_methods_copy = nof_methods;
1187 while (nof_methods_copy > 0) {
1188 Method* mm = methods->at(--nof_methods_copy);
1189 assert(!mm->has_itable_index() || mm->itable_index() < length, "");
1190 }
1191 #endif //ASSERT
1192 // return the rightmost itable index, plus one; or 0 if no methods have
1193 // itable indices
1194 return length;
1195 }
1196
1197
1198 void klassItable::initialize_itable_for_interface(int method_table_offset, Klass* interf, bool checkconstraints, TRAPS) {
1199 Array<Method*>* methods = InstanceKlass::cast(interf)->methods();
1200 int nof_methods = methods->length();
1201 HandleMark hm;
1202 Handle interface_loader (THREAD, InstanceKlass::cast(interf)->class_loader());
1203
1204 int ime_count = method_count_for_interface(interf);
1205 for (int i = 0; i < nof_methods; i++) {
1206 Method* m = methods->at(i);
1207 methodHandle target;
1208 if (m->has_itable_index()) {
1209 // This search must match the runtime resolution, i.e. selection search for invokeinterface
1210 // to correctly enforce loader constraints for interface method inheritance.
1211 // Private methods are skipped as a private class method can never be the implementation
1212 // of an interface method.
1213 // Invokespecial does not perform selection based on the receiver, so it does not use
1214 // the cached itable.
1215 target = LinkResolver::lookup_instance_method_in_klasses(_klass, m->name(), m->signature(),
1216 Klass::skip_private, CHECK);
1217 }
1218 if (target == NULL || !target->is_public() || target->is_abstract() || target->is_overpass()) {
1219 assert(target == NULL || !target->is_overpass() || target->is_public(),
1220 "Non-public overpass method!");
1221 // Entry does not resolve. Leave it empty for AbstractMethodError or other error.
1222 if (!(target == NULL) && !target->is_public()) {
1223 // Stuff an IllegalAccessError throwing method in there instead.
1224 itableOffsetEntry::method_entry(_klass, method_table_offset)[m->itable_index()].
1225 initialize(Universe::throw_illegal_access_error());
1226 }
1227 } else {
1228 // Entry did resolve, check loader constraints before initializing
1229 // if checkconstraints requested
1230 if (checkconstraints) {
1231 Handle method_holder_loader (THREAD, target->method_holder()->class_loader());
1232 if (!oopDesc::equals(method_holder_loader(), interface_loader())) {
1233 ResourceMark rm(THREAD);
1234 Symbol* failed_type_symbol =
1235 SystemDictionary::check_signature_loaders(m->signature(),
1236 method_holder_loader,
1237 interface_loader,
1238 true, CHECK);
1239 if (failed_type_symbol != NULL) {
1240 ResourceMark rm(THREAD);
1241 stringStream ss;
1242 ss.print("loader constraint violation in interface itable"
1243 " initialization for class %s: when selecting method %s the"
1244 " class loader %s for super interface %s, and the class"
1245 " loader %s of the selected method's type, %s have"
1246 " different Class objects for the type %s used in the signature",
1247 _klass->external_name(),
1248 m->name_and_sig_as_C_string(),
1249 java_lang_ClassLoader::describe_external(interface_loader()),
1250 InstanceKlass::cast(interf)->external_name(),
1251 java_lang_ClassLoader::describe_external(method_holder_loader()),
1252 target()->method_holder()->external_name(),
1253 failed_type_symbol->as_klass_external_name());
1254 THROW_MSG(vmSymbols::java_lang_LinkageError(), ss.as_string());
1255 }
1256 }
1257 }
1258
1259 // ime may have moved during GC so recalculate address
1260 int ime_num = m->itable_index();
1261 assert(ime_num < ime_count, "oob");
1262 itableOffsetEntry::method_entry(_klass, method_table_offset)[ime_num].initialize(target());
1263 if (log_develop_is_enabled(Trace, itables)) {
1264 ResourceMark rm(THREAD);
1265 if (target() != NULL) {
1266 LogTarget(Trace, itables) lt;
1267 LogStream ls(lt);
1268 char* sig = target()->name_and_sig_as_C_string();
1269 ls.print("interface: %s, ime_num: %d, target: %s, method_holder: %s ",
1270 interf->internal_name(), ime_num, sig,
1271 target()->method_holder()->internal_name());
1272 ls.print("target_method flags: ");
1273 target()->print_linkage_flags(&ls);
1274 ls.cr();
1275 }
1276 }
1277 }
1278 }
1279 }
1280
1281 #if INCLUDE_JVMTI
1282 // search the itable for uses of either obsolete or EMCP methods
1283 void klassItable::adjust_method_entries(InstanceKlass* holder, bool * trace_name_printed) {
1284
1285 itableMethodEntry* ime = method_entry(0);
1286 for (int i = 0; i < _size_method_table; i++, ime++) {
1287 Method* old_method = ime->method();
1288 if (old_method == NULL || old_method->method_holder() != holder || !old_method->is_old()) {
1289 continue; // skip uninteresting entries
1290 }
1291 assert(!old_method->is_deleted(), "itable methods may not be deleted");
1292
1293 Method* new_method = holder->method_with_idnum(old_method->orig_method_idnum());
1294
1295 assert(new_method != NULL, "method_with_idnum() should not be NULL");
1296 assert(old_method != new_method, "sanity check");
1297
1298 ime->initialize(new_method);
1299
1300 if (log_is_enabled(Info, redefine, class, update)) {
1301 ResourceMark rm;
1302 if (!(*trace_name_printed)) {
1303 log_info(redefine, class, update)("adjust: name=%s", old_method->method_holder()->external_name());
1304 *trace_name_printed = true;
1305 }
1306 log_trace(redefine, class, update, itables)
1307 ("itable method update: %s(%s)", new_method->name()->as_C_string(), new_method->signature()->as_C_string());
1308 }
1309 }
1310 }
1311
1312 // an itable should never contain old or obsolete methods
1313 bool klassItable::check_no_old_or_obsolete_entries() {
1314 itableMethodEntry* ime = method_entry(0);
1315 for (int i = 0; i < _size_method_table; i++) {
1316 Method* m = ime->method();
1317 if (m != NULL &&
1318 (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) {
1319 return false;
1320 }
1321 ime++;
1322 }
1323 return true;
1324 }
1325
1326 void klassItable::dump_itable() {
1327 itableMethodEntry* ime = method_entry(0);
1328 tty->print_cr("itable dump --");
1329 for (int i = 0; i < _size_method_table; i++) {
1330 Method* m = ime->method();
1331 if (m != NULL) {
1332 tty->print(" (%5d) ", i);
1333 m->access_flags().print_on(tty);
1334 if (m->is_default_method()) {
1335 tty->print("default ");
1336 }
1337 tty->print(" -- ");
1338 m->print_name(tty);
1339 tty->cr();
1340 }
1341 ime++;
1342 }
1343 }
1344 #endif // INCLUDE_JVMTI
1345
1346 // Setup
1347 class InterfaceVisiterClosure : public StackObj {
1348 public:
1349 virtual void doit(Klass* intf, int method_count) = 0;
1350 };
1351
1352 // Visit all interfaces with at least one itable method
1353 void visit_all_interfaces(Array<Klass*>* transitive_intf, InterfaceVisiterClosure *blk) {
1354 // Handle array argument
1355 for(int i = 0; i < transitive_intf->length(); i++) {
1356 Klass* intf = transitive_intf->at(i);
1357 assert(intf->is_interface(), "sanity check");
1358
1359 // Find no. of itable methods
1360 int method_count = 0;
1361 // method_count = klassItable::method_count_for_interface(intf);
1362 Array<Method*>* methods = InstanceKlass::cast(intf)->methods();
1363 if (methods->length() > 0) {
1364 for (int i = methods->length(); --i >= 0; ) {
1365 if (interface_method_needs_itable_index(methods->at(i))) {
1366 method_count++;
1367 }
1368 }
1369 }
1370
1371 // Visit all interfaces which either have any methods or can participate in receiver type check.
1372 // We do not bother to count methods in transitive interfaces, although that would allow us to skip
1373 // this step in the rare case of a zero-method interface extending another zero-method interface.
1374 if (method_count > 0 || InstanceKlass::cast(intf)->transitive_interfaces()->length() > 0) {
1375 blk->doit(intf, method_count);
1376 }
1377 }
1378 }
1379
1380 class CountInterfacesClosure : public InterfaceVisiterClosure {
1381 private:
1382 int _nof_methods;
1383 int _nof_interfaces;
1384 public:
1385 CountInterfacesClosure() { _nof_methods = 0; _nof_interfaces = 0; }
1386
1387 int nof_methods() const { return _nof_methods; }
1388 int nof_interfaces() const { return _nof_interfaces; }
1389
1390 void doit(Klass* intf, int method_count) { _nof_methods += method_count; _nof_interfaces++; }
1391 };
1392
1393 class SetupItableClosure : public InterfaceVisiterClosure {
1394 private:
1395 itableOffsetEntry* _offset_entry;
1396 itableMethodEntry* _method_entry;
1397 address _klass_begin;
1398 public:
1399 SetupItableClosure(address klass_begin, itableOffsetEntry* offset_entry, itableMethodEntry* method_entry) {
1400 _klass_begin = klass_begin;
1401 _offset_entry = offset_entry;
1402 _method_entry = method_entry;
1403 }
1404
1405 itableMethodEntry* method_entry() const { return _method_entry; }
1406
1407 void doit(Klass* intf, int method_count) {
1408 int offset = ((address)_method_entry) - _klass_begin;
1409 _offset_entry->initialize(intf, offset);
1410 _offset_entry++;
1411 _method_entry += method_count;
1412 }
1413 };
1414
1415 int klassItable::compute_itable_size(Array<Klass*>* transitive_interfaces) {
1416 // Count no of interfaces and total number of interface methods
1417 CountInterfacesClosure cic;
1418 visit_all_interfaces(transitive_interfaces, &cic);
1419
1420 // There's alway an extra itable entry so we can null-terminate it.
1421 int itable_size = calc_itable_size(cic.nof_interfaces() + 1, cic.nof_methods());
1422
1423 // Statistics
1424 update_stats(itable_size * wordSize);
1425
1426 return itable_size;
1427 }
1428
1429
1430 // Fill out offset table and interface klasses into the itable space
1431 void klassItable::setup_itable_offset_table(InstanceKlass* klass) {
1432 if (klass->itable_length() == 0) return;
1433 assert(!klass->is_interface(), "Should have zero length itable");
1434
1435 // Count no of interfaces and total number of interface methods
1436 CountInterfacesClosure cic;
1437 visit_all_interfaces(klass->transitive_interfaces(), &cic);
1438 int nof_methods = cic.nof_methods();
1439 int nof_interfaces = cic.nof_interfaces();
1440
1441 // Add one extra entry so we can null-terminate the table
1442 nof_interfaces++;
1443
1444 assert(compute_itable_size(klass->transitive_interfaces()) ==
1445 calc_itable_size(nof_interfaces, nof_methods),
1446 "mismatch calculation of itable size");
1447
1448 // Fill-out offset table
1449 itableOffsetEntry* ioe = (itableOffsetEntry*)klass->start_of_itable();
1450 itableMethodEntry* ime = (itableMethodEntry*)(ioe + nof_interfaces);
1451 intptr_t* end = klass->end_of_itable();
1452 assert((oop*)(ime + nof_methods) <= (oop*)klass->start_of_nonstatic_oop_maps(), "wrong offset calculation (1)");
1453 assert((oop*)(end) == (oop*)(ime + nof_methods), "wrong offset calculation (2)");
1454
1455 // Visit all interfaces and initialize itable offset table
1456 SetupItableClosure sic((address)klass, ioe, ime);
1457 visit_all_interfaces(klass->transitive_interfaces(), &sic);
1458
1459 #ifdef ASSERT
1460 ime = sic.method_entry();
1461 oop* v = (oop*) klass->end_of_itable();
1462 assert( (oop*)(ime) == v, "wrong offset calculation (2)");
1463 #endif
1464 }
1465
1466
1467 // inverse to itable_index
1468 Method* klassItable::method_for_itable_index(Klass* intf, int itable_index) {
1469 assert(InstanceKlass::cast(intf)->is_interface(), "sanity check");
1470 assert(intf->verify_itable_index(itable_index), "");
1471 Array<Method*>* methods = InstanceKlass::cast(intf)->methods();
1472
1473 if (itable_index < 0 || itable_index >= method_count_for_interface(intf))
1474 return NULL; // help caller defend against bad indices
1475
1476 int index = itable_index;
1477 Method* m = methods->at(index);
1478 int index2 = -1;
1479 while (!m->has_itable_index() ||
1480 (index2 = m->itable_index()) != itable_index) {
1481 assert(index2 < itable_index, "monotonic");
1482 if (++index == methods->length())
1483 return NULL;
1484 m = methods->at(index);
1485 }
1486 assert(m->itable_index() == itable_index, "correct inverse");
1487
1488 return m;
1489 }
1490
1491 void klassVtable::verify(outputStream* st, bool forced) {
1492 // make sure table is initialized
1493 if (!Universe::is_fully_initialized()) return;
1494 #ifndef PRODUCT
1495 // avoid redundant verifies
1496 if (!forced && _verify_count == Universe::verify_count()) return;
1497 _verify_count = Universe::verify_count();
1498 #endif
1499 oop* end_of_obj = (oop*)_klass + _klass->size();
1500 oop* end_of_vtable = (oop *)&table()[_length];
1501 if (end_of_vtable > end_of_obj) {
1502 fatal("klass %s: klass object too short (vtable extends beyond end)",
1503 _klass->internal_name());
1504 }
1505
1506 for (int i = 0; i < _length; i++) table()[i].verify(this, st);
1507 // verify consistency with superKlass vtable
1508 Klass* super = _klass->super();
1509 if (super != NULL) {
1510 InstanceKlass* sk = InstanceKlass::cast(super);
1511 klassVtable vt = sk->vtable();
1512 for (int i = 0; i < vt.length(); i++) {
1513 verify_against(st, &vt, i);
1514 }
1515 }
1516 }
1517
1518 void klassVtable::verify_against(outputStream* st, klassVtable* vt, int index) {
1519 vtableEntry* vte = &vt->table()[index];
1520 if (vte->method()->name() != table()[index].method()->name() ||
1521 vte->method()->signature() != table()[index].method()->signature()) {
1522 fatal("mismatched name/signature of vtable entries");
1523 }
1524 }
1525
1526 #ifndef PRODUCT
1527 void klassVtable::print() {
1528 ResourceMark rm;
1529 tty->print("klassVtable for klass %s (length %d):\n", _klass->internal_name(), length());
1530 for (int i = 0; i < length(); i++) {
1531 table()[i].print();
1532 tty->cr();
1533 }
1534 }
1535 #endif
1536
1537 void vtableEntry::verify(klassVtable* vt, outputStream* st) {
1538 NOT_PRODUCT(FlagSetting fs(IgnoreLockingAssertions, true));
1539 Klass* vtklass = vt->klass();
1540 if (vtklass->is_instance_klass() &&
1541 (InstanceKlass::cast(vtklass)->major_version() >= klassVtable::VTABLE_TRANSITIVE_OVERRIDE_VERSION)) {
1542 assert(method() != NULL, "must have set method");
1543 }
1544 if (method() != NULL) {
1545 method()->verify();
1546 // we sub_type, because it could be a miranda method
1547 if (!vtklass->is_subtype_of(method()->method_holder())) {
1548 #ifndef PRODUCT
1549 print();
1550 #endif
1551 fatal("vtableEntry " PTR_FORMAT ": method is from subclass", p2i(this));
1552 }
1553 }
1554 }
1555
1556 #ifndef PRODUCT
1557
1558 void vtableEntry::print() {
1559 ResourceMark rm;
1560 tty->print("vtableEntry %s: ", method()->name()->as_C_string());
1561 if (Verbose) {
1562 tty->print("m " PTR_FORMAT " ", p2i(method()));
1563 }
1564 }
1565
1566 class VtableStats : AllStatic {
1567 public:
1568 static int no_klasses; // # classes with vtables
1569 static int no_array_klasses; // # array classes
1570 static int no_instance_klasses; // # instanceKlasses
1571 static int sum_of_vtable_len; // total # of vtable entries
1572 static int sum_of_array_vtable_len; // total # of vtable entries in array klasses only
1573 static int fixed; // total fixed overhead in bytes
1574 static int filler; // overhead caused by filler bytes
1575 static int entries; // total bytes consumed by vtable entries
1576 static int array_entries; // total bytes consumed by array vtable entries
1577
1578 static void do_class(Klass* k) {
1579 Klass* kl = k;
1580 klassVtable vt = kl->vtable();
1581 no_klasses++;
1582 if (kl->is_instance_klass()) {
1583 no_instance_klasses++;
1584 kl->array_klasses_do(do_class);
1585 }
1586 if (kl->is_array_klass()) {
1587 no_array_klasses++;
1588 sum_of_array_vtable_len += vt.length();
1589 }
1590 sum_of_vtable_len += vt.length();
1591 }
1592
1593 static void compute() {
1594 ClassLoaderDataGraph::classes_do(do_class);
1595 fixed = no_klasses * oopSize; // vtable length
1596 // filler size is a conservative approximation
1597 filler = oopSize * (no_klasses - no_instance_klasses) * (sizeof(InstanceKlass) - sizeof(ArrayKlass) - 1);
1598 entries = sizeof(vtableEntry) * sum_of_vtable_len;
1599 array_entries = sizeof(vtableEntry) * sum_of_array_vtable_len;
1600 }
1601 };
1602
1603 int VtableStats::no_klasses = 0;
1604 int VtableStats::no_array_klasses = 0;
1605 int VtableStats::no_instance_klasses = 0;
1606 int VtableStats::sum_of_vtable_len = 0;
1607 int VtableStats::sum_of_array_vtable_len = 0;
1608 int VtableStats::fixed = 0;
1609 int VtableStats::filler = 0;
1610 int VtableStats::entries = 0;
1611 int VtableStats::array_entries = 0;
1612
1613 void klassVtable::print_statistics() {
1614 ResourceMark rm;
1615 HandleMark hm;
1616 VtableStats::compute();
1617 tty->print_cr("vtable statistics:");
1618 tty->print_cr("%6d classes (%d instance, %d array)", VtableStats::no_klasses, VtableStats::no_instance_klasses, VtableStats::no_array_klasses);
1619 int total = VtableStats::fixed + VtableStats::filler + VtableStats::entries;
1620 tty->print_cr("%6d bytes fixed overhead (refs + vtable object header)", VtableStats::fixed);
1621 tty->print_cr("%6d bytes filler overhead", VtableStats::filler);
1622 tty->print_cr("%6d bytes for vtable entries (%d for arrays)", VtableStats::entries, VtableStats::array_entries);
1623 tty->print_cr("%6d bytes total", total);
1624 }
1625
1626 int klassItable::_total_classes; // Total no. of classes with itables
1627 long klassItable::_total_size; // Total no. of bytes used for itables
1628
1629 void klassItable::print_statistics() {
1630 tty->print_cr("itable statistics:");
1631 tty->print_cr("%6d classes with itables", _total_classes);
1632 tty->print_cr("%6lu K uses for itables (average by class: %ld bytes)", _total_size / K, _total_size / _total_classes);
1633 }
1634
1635 #endif // PRODUCT