1 /*
2 * Copyright (c) 1997, 2019, 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/classLoaderDataGraph.hpp"
28 #include "classfile/javaClasses.hpp"
29 #include "classfile/systemDictionary.hpp"
30 #include "classfile/vmSymbols.hpp"
31 #include "interpreter/linkResolver.hpp"
32 #include "logging/log.hpp"
33 #include "logging/logStream.hpp"
34 #include "memory/metaspaceShared.hpp"
35 #include "memory/resourceArea.hpp"
36 #include "memory/universe.hpp"
37 #include "oops/instanceKlass.hpp"
38 #include "oops/klassVtable.hpp"
39 #include "oops/method.hpp"
40 #include "oops/objArrayOop.hpp"
41 #include "oops/oop.inline.hpp"
42 #include "runtime/arguments.hpp"
43 #include "runtime/flags/flagSetting.hpp"
44 #include "runtime/handles.inline.hpp"
45 #include "runtime/safepointVerifiers.hpp"
46 #include "utilities/copy.hpp"
47
48 inline InstanceKlass* klassVtable::ik() const {
49 return InstanceKlass::cast(_klass);
50 }
51
52 bool klassVtable::is_preinitialized_vtable() {
53 return _klass->is_shared() && !MetaspaceShared::remapped_readwrite();
54 }
55
56
57 // this function computes the vtable size (including the size needed for miranda
58 // methods) and the number of miranda methods in this class.
59 // Note on Miranda methods: Let's say there is a class C that implements
60 // interface I, and none of C's superclasses implements I.
61 // Let's say there is an abstract method m in I that neither C
62 // nor any of its super classes implement (i.e there is no method of any access,
63 // with the same name and signature as m), then m is a Miranda method which is
64 // entered as a public abstract method in C's vtable. From then on it should
65 // treated as any other public method in C for method over-ride purposes.
66 void klassVtable::compute_vtable_size_and_num_mirandas(
67 int* vtable_length_ret, int* num_new_mirandas,
68 GrowableArray<Method*>* all_mirandas, const Klass* super,
69 Array<Method*>* methods, AccessFlags class_flags, u2 major_version,
70 Handle classloader, Symbol* classname, Array<InstanceKlass*>* local_interfaces,
71 TRAPS) {
72 NoSafepointVerifier nsv;
73
74 // set up default result values
75 int vtable_length = 0;
76
77 // start off with super's vtable length
78 vtable_length = super == NULL ? 0 : super->vtable_length();
79
80 // go thru each method in the methods table to see if it needs a new entry
81 int len = methods->length();
82 for (int i = 0; i < len; i++) {
83 assert(methods->at(i)->is_method(), "must be a Method*");
84 methodHandle mh(THREAD, methods->at(i));
85
86 if (needs_new_vtable_entry(mh, super, classloader, classname, class_flags, major_version, THREAD)) {
87 assert(!methods->at(i)->is_private(), "private methods should not need a vtable entry");
88 vtable_length += vtableEntry::size(); // we need a new entry
89 }
90 }
91
92 GrowableArray<Method*> new_mirandas(20);
93 // compute the number of mirandas methods that must be added to the end
94 get_mirandas(&new_mirandas, all_mirandas, super, methods, NULL, local_interfaces,
95 class_flags.is_interface());
96 *num_new_mirandas = new_mirandas.length();
97
98 // Interfaces do not need interface methods in their vtables
99 // This includes miranda methods and during later processing, default methods
100 if (!class_flags.is_interface()) {
101 vtable_length += *num_new_mirandas * vtableEntry::size();
102 }
103
104 if (Universe::is_bootstrapping() && vtable_length == 0) {
105 // array classes don't have their superclass set correctly during
106 // bootstrapping
107 vtable_length = Universe::base_vtable_size();
108 }
109
110 if (super == NULL && vtable_length != Universe::base_vtable_size()) {
111 if (Universe::is_bootstrapping()) {
112 // Someone is attempting to override java.lang.Object incorrectly on the
113 // bootclasspath. The JVM cannot recover from this error including throwing
114 // an exception
115 vm_exit_during_initialization("Incompatible definition of java.lang.Object");
116 } else {
117 // Someone is attempting to redefine java.lang.Object incorrectly. The
118 // only way this should happen is from
119 // SystemDictionary::resolve_from_stream(), which will detect this later
120 // and throw a security exception. So don't assert here to let
121 // the exception occur.
122 vtable_length = Universe::base_vtable_size();
123 }
124 }
125 assert(vtable_length % vtableEntry::size() == 0, "bad vtable length");
126 assert(vtable_length >= Universe::base_vtable_size(), "vtable too small");
127
128 *vtable_length_ret = vtable_length;
129 }
130
131 int klassVtable::index_of(Method* m, int len) const {
132 assert(m->has_vtable_index(), "do not ask this of non-vtable methods");
133 return m->vtable_index();
134 }
135
136 // Copy super class's vtable to the first part (prefix) of this class's vtable,
137 // and return the number of entries copied. Expects that 'super' is the Java
138 // super class (arrays can have "array" super classes that must be skipped).
139 int klassVtable::initialize_from_super(Klass* super) {
140 if (super == NULL) {
141 return 0;
142 } else if (is_preinitialized_vtable()) {
143 // A shared class' vtable is preinitialized at dump time. No need to copy
144 // methods from super class for shared class, as that was already done
145 // during archiving time. However, if Jvmti has redefined a class,
146 // copy super class's vtable in case the super class has changed.
147 return super->vtable().length();
148 } else {
149 // copy methods from superKlass
150 klassVtable superVtable = super->vtable();
151 assert(superVtable.length() <= _length, "vtable too short");
152 #ifdef ASSERT
153 superVtable.verify(tty, true);
154 #endif
155 superVtable.copy_vtable_to(table());
156 if (log_develop_is_enabled(Trace, vtables)) {
157 ResourceMark rm;
158 log_develop_trace(vtables)("copy vtable from %s to %s size %d",
159 super->internal_name(), klass()->internal_name(),
160 _length);
161 }
162 return superVtable.length();
163 }
164 }
165
166 //
167 // Revised lookup semantics introduced 1.3 (Kestrel beta)
168 void klassVtable::initialize_vtable(bool checkconstraints, TRAPS) {
169
170 // Note: Arrays can have intermediate array supers. Use java_super to skip them.
171 InstanceKlass* super = _klass->java_super();
172 int nofNewEntries = 0;
173
174 bool is_shared = _klass->is_shared();
175
176 if (!_klass->is_array_klass()) {
177 ResourceMark rm(THREAD);
178 log_develop_debug(vtables)("Initializing: %s", _klass->name()->as_C_string());
179 }
180
181 #ifdef ASSERT
182 oop* end_of_obj = (oop*)_klass + _klass->size();
183 oop* end_of_vtable = (oop*)&table()[_length];
184 assert(end_of_vtable <= end_of_obj, "vtable extends beyond end");
185 #endif
186
187 if (Universe::is_bootstrapping()) {
188 assert(!is_shared, "sanity");
189 // just clear everything
190 for (int i = 0; i < _length; i++) table()[i].clear();
191 return;
192 }
193
194 int super_vtable_len = initialize_from_super(super);
195 if (_klass->is_array_klass()) {
196 assert(super_vtable_len == _length, "arrays shouldn't introduce new methods");
197 } else {
198 assert(_klass->is_instance_klass(), "must be InstanceKlass");
199
200 Array<Method*>* methods = ik()->methods();
201 int len = methods->length();
202 int initialized = super_vtable_len;
203
204 // Check each of this class's methods against super;
205 // if override, replace in copy of super vtable, otherwise append to end
206 for (int i = 0; i < len; i++) {
207 // update_inherited_vtable can stop for gc - ensure using handles
208 HandleMark hm(THREAD);
209 assert(methods->at(i)->is_method(), "must be a Method*");
210 methodHandle mh(THREAD, methods->at(i));
211
212 bool needs_new_entry = update_inherited_vtable(ik(), mh, super_vtable_len, -1, checkconstraints, CHECK);
213
214 if (needs_new_entry) {
215 put_method_at(mh(), initialized);
216 mh()->set_vtable_index(initialized); // set primary vtable index
217 initialized++;
218 }
219 }
220
221 // update vtable with default_methods
222 Array<Method*>* default_methods = ik()->default_methods();
223 if (default_methods != NULL) {
224 len = default_methods->length();
225 if (len > 0) {
226 Array<int>* def_vtable_indices = NULL;
227 if ((def_vtable_indices = ik()->default_vtable_indices()) == NULL) {
228 assert(!is_shared, "shared class def_vtable_indices does not exist");
229 def_vtable_indices = ik()->create_new_default_vtable_indices(len, CHECK);
230 } else {
231 assert(def_vtable_indices->length() == len, "reinit vtable len?");
232 }
233 for (int i = 0; i < len; i++) {
234 HandleMark hm(THREAD);
235 assert(default_methods->at(i)->is_method(), "must be a Method*");
236 methodHandle mh(THREAD, default_methods->at(i));
237 assert(!mh->is_private(), "private interface method in the default method list");
238 bool needs_new_entry = update_inherited_vtable(ik(), mh, super_vtable_len, i, checkconstraints, CHECK);
239
240 // needs new entry
241 if (needs_new_entry) {
242 put_method_at(mh(), initialized);
243 if (is_preinitialized_vtable()) {
244 // At runtime initialize_vtable is rerun for a shared class
245 // (loaded by the non-boot loader) as part of link_class_impl().
246 // The dumptime vtable index should be the same as the runtime index.
247 assert(def_vtable_indices->at(i) == initialized,
248 "dump time vtable index is different from runtime index");
249 } else {
250 def_vtable_indices->at_put(i, initialized); //set vtable index
251 }
252 initialized++;
253 }
254 }
255 }
256 }
257
258 // add miranda methods; it will also return the updated initialized
259 // Interfaces do not need interface methods in their vtables
260 // This includes miranda methods and during later processing, default methods
261 if (!ik()->is_interface()) {
262 initialized = fill_in_mirandas(initialized, THREAD);
263 }
264
265 // In class hierarchies where the accessibility is not increasing (i.e., going from private ->
266 // package_private -> public/protected), the vtable might actually be smaller than our initial
267 // calculation, for classfile versions for which we do not do transitive override
268 // calculations.
269 if (ik()->major_version() >= VTABLE_TRANSITIVE_OVERRIDE_VERSION) {
270 assert(initialized == _length, "vtable initialization failed");
271 } else {
272 assert(initialized <= _length, "vtable initialization failed");
273 for(;initialized < _length; initialized++) {
274 table()[initialized].clear();
275 }
276 }
277 NOT_PRODUCT(verify(tty, true));
278 }
279 }
280
281 // Called for cases where a method does not override its superclass' vtable entry
282 // For bytecodes not produced by javac together it is possible that a method does not override
283 // the superclass's method, but might indirectly override a super-super class's vtable entry
284 // If none found, return a null superk, else return the superk of the method this does override
285 // For public and protected methods: if they override a superclass, they will
286 // also be overridden themselves appropriately.
287 // Private methods do not override, and are not overridden and are not in the vtable.
288 // Package Private methods are trickier:
289 // e.g. P1.A, pub m
290 // P2.B extends A, package private m
291 // P1.C extends B, public m
292 // P1.C.m needs to override P1.A.m and can not override P2.B.m
293 // Therefore: all package private methods need their own vtable entries for
294 // them to be the root of an inheritance overriding decision
295 // Package private methods may also override other vtable entries
296 InstanceKlass* klassVtable::find_transitive_override(InstanceKlass* initialsuper, const methodHandle& target_method,
297 int vtable_index, Handle target_loader, Symbol* target_classname, Thread * THREAD) {
298 InstanceKlass* superk = initialsuper;
299 while (superk != NULL && superk->super() != NULL) {
300 InstanceKlass* supersuperklass = InstanceKlass::cast(superk->super());
301 klassVtable ssVtable = supersuperklass->vtable();
302 if (vtable_index < ssVtable.length()) {
303 Method* super_method = ssVtable.method_at(vtable_index);
304 #ifndef PRODUCT
305 Symbol* name= target_method()->name();
306 Symbol* signature = target_method()->signature();
307 assert(super_method->name() == name && super_method->signature() == signature, "vtable entry name/sig mismatch");
308 #endif
309 if (supersuperklass->is_override(super_method, target_loader, target_classname, THREAD)) {
310 if (log_develop_is_enabled(Trace, vtables)) {
311 ResourceMark rm(THREAD);
312 LogTarget(Trace, vtables) lt;
313 LogStream ls(lt);
314 char* sig = target_method()->name_and_sig_as_C_string();
315 ls.print("transitive overriding superclass %s with %s index %d, original flags: ",
316 supersuperklass->internal_name(),
317 sig, vtable_index);
318 super_method->print_linkage_flags(&ls);
319 ls.print("overriders flags: ");
320 target_method->print_linkage_flags(&ls);
321 ls.cr();
322 }
323
324 break; // return found superk
325 }
326 } else {
327 // super class has no vtable entry here, stop transitive search
328 superk = (InstanceKlass*)NULL;
329 break;
330 }
331 // if no override found yet, continue to search up
332 superk = superk->super() == NULL ? NULL : InstanceKlass::cast(superk->super());
333 }
334
335 return superk;
336 }
337
338 static void log_vtables(int i, bool overrides, const methodHandle& target_method,
339 Klass* target_klass, Method* super_method,
340 Thread* thread) {
341 #ifndef PRODUCT
342 if (log_develop_is_enabled(Trace, vtables)) {
343 ResourceMark rm(thread);
344 LogTarget(Trace, vtables) lt;
345 LogStream ls(lt);
346 char* sig = target_method()->name_and_sig_as_C_string();
347 if (overrides) {
348 ls.print("overriding with %s index %d, original flags: ",
349 sig, i);
350 } else {
351 ls.print("NOT overriding with %s index %d, original flags: ",
352 sig, i);
353 }
354 super_method->print_linkage_flags(&ls);
355 ls.print("overriders flags: ");
356 target_method->print_linkage_flags(&ls);
357 ls.cr();
358 }
359 #endif
360 }
361
362 // Update child's copy of super vtable for overrides
363 // OR return true if a new vtable entry is required.
364 // Only called for InstanceKlass's, i.e. not for arrays
365 // If that changed, could not use _klass as handle for klass
366 bool klassVtable::update_inherited_vtable(InstanceKlass* klass, const methodHandle& target_method,
367 int super_vtable_len, int default_index,
368 bool checkconstraints, TRAPS) {
369 ResourceMark rm(THREAD);
370 bool allocate_new = true;
371 assert(klass->is_instance_klass(), "must be InstanceKlass");
372
373 Array<int>* def_vtable_indices = NULL;
374 bool is_default = false;
375
376 // default methods are non-private concrete methods in superinterfaces which are added
377 // to the vtable with their real method_holder.
378 // Since vtable and itable indices share the same storage, don't touch
379 // the default method's real vtable/itable index.
380 // default_vtable_indices stores the vtable value relative to this inheritor
381 if (default_index >= 0 ) {
382 is_default = true;
383 def_vtable_indices = klass->default_vtable_indices();
384 assert(!target_method()->is_private(), "private interface method flagged as default");
385 assert(def_vtable_indices != NULL, "def vtable alloc?");
386 assert(default_index <= def_vtable_indices->length(), "def vtable len?");
387 } else {
388 assert(klass == target_method()->method_holder(), "caller resp.");
389 // Initialize the method's vtable index to "nonvirtual".
390 // If we allocate a vtable entry, we will update it to a non-negative number.
391 target_method()->set_vtable_index(Method::nonvirtual_vtable_index);
392 }
393
394 // Private, static and <init> methods are never in
395 if (target_method()->is_private() || target_method()->is_static() ||
396 (target_method()->name()->fast_compare(vmSymbols::object_initializer_name()) == 0)) {
397 return false;
398 }
399
400 if (target_method->is_final_method(klass->access_flags())) {
401 // a final method never needs a new entry; final methods can be statically
402 // resolved and they have to be present in the vtable only if they override
403 // a super's method, in which case they re-use its entry
404 allocate_new = false;
405 } else if (klass->is_interface()) {
406 allocate_new = false; // see note below in needs_new_vtable_entry
407 // An interface never allocates new vtable slots, only inherits old ones.
408 // This method will either be assigned its own itable index later,
409 // or be assigned an inherited vtable index in the loop below.
410 // default methods inherited by classes store their vtable indices
411 // in the inheritor's default_vtable_indices.
412 // default methods inherited by interfaces may already have a
413 // valid itable index, if so, don't change it.
414 // Overpass methods in an interface will be assigned an itable index later
415 // by an inheriting class.
416 if ((!is_default || !target_method()->has_itable_index())) {
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 // search through the vtable and update overridden entries
428 // Since check_signature_loaders acquires SystemDictionary_lock
429 // which can block for gc, once we are in this loop, use handles
430 // For classfiles built with >= jdk7, we now look for transitive overrides
431
432 Symbol* name = target_method()->name();
433 Symbol* signature = target_method()->signature();
434
435 Klass* target_klass = target_method()->method_holder();
436 if (target_klass == NULL) {
437 target_klass = _klass;
438 }
439
440 Handle target_loader(THREAD, target_klass->class_loader());
441
442 Symbol* target_classname = target_klass->name();
443 for(int i = 0; i < super_vtable_len; i++) {
444 Method* super_method;
445 if (is_preinitialized_vtable()) {
446 // If this is a shared class, the vtable is already in the final state (fully
447 // initialized). Need to look at the super's vtable.
448 klassVtable superVtable = super->vtable();
449 super_method = superVtable.method_at(i);
450 } else {
451 super_method = method_at(i);
452 }
453 // Check if method name matches. Ignore match if klass is an interface and the
454 // matching method is a non-public java.lang.Object method. (See JVMS 5.4.3.4)
455 // This is safe because the method at this slot should never get invoked.
456 // (TBD: put in a method to throw NoSuchMethodError if this slot is ever used.)
457 if (super_method->name() == name && super_method->signature() == signature &&
458 (!_klass->is_interface() ||
459 !SystemDictionary::is_nonpublic_Object_method(super_method))) {
460
461 // get super_klass for method_holder for the found method
462 InstanceKlass* super_klass = super_method->method_holder();
463
464 // Whether the method is being overridden
465 bool overrides = false;
466
467 // private methods are also never overridden
468 if (!super_method->is_private() &&
469 (is_default
470 || ((super_klass->is_override(super_method, target_loader, target_classname, THREAD))
471 || ((klass->major_version() >= VTABLE_TRANSITIVE_OVERRIDE_VERSION)
472 && ((super_klass = find_transitive_override(super_klass,
473 target_method, i, target_loader,
474 target_classname, THREAD))
475 != (InstanceKlass*)NULL)))))
476 {
477 // Package private methods always need a new entry to root their own
478 // overriding. They may also override other methods.
479 if (!target_method()->is_package_private()) {
480 allocate_new = false;
481 }
482
483 // Do not check loader constraints for overpass methods because overpass
484 // methods are created by the jvm to throw exceptions.
485 if (checkconstraints && !target_method()->is_overpass()) {
486 // Override vtable entry if passes loader constraint check
487 // if loader constraint checking requested
488 // No need to visit his super, since he and his super
489 // have already made any needed loader constraints.
490 // Since loader constraints are transitive, it is enough
491 // to link to the first super, and we get all the others.
492 Handle super_loader(THREAD, super_klass->class_loader());
493
494 if (!oopDesc::equals(target_loader(), super_loader())) {
495 ResourceMark rm(THREAD);
496 Symbol* failed_type_symbol =
497 SystemDictionary::check_signature_loaders(signature, target_loader,
498 super_loader, true,
499 CHECK_(false));
500 if (failed_type_symbol != NULL) {
501 stringStream ss;
502 ss.print("loader constraint violation for class %s: when selecting "
503 "overriding method '", klass->external_name());
504 target_method()->print_external_name(&ss),
505 ss.print("' the class loader %s of the "
506 "selected method's type %s, and the class loader %s for its super "
507 "type %s have different Class objects for the type %s used in the signature (%s; %s)",
508 target_klass->class_loader_data()->loader_name_and_id(),
509 target_klass->external_name(),
510 super_klass->class_loader_data()->loader_name_and_id(),
511 super_klass->external_name(),
512 failed_type_symbol->as_klass_external_name(),
513 target_klass->class_in_module_of_loader(false, true),
514 super_klass->class_in_module_of_loader(false, true));
515 THROW_MSG_(vmSymbols::java_lang_LinkageError(), ss.as_string(), false);
516 }
517 }
518 }
519
520 put_method_at(target_method(), i);
521 overrides = true;
522 if (!is_default) {
523 target_method()->set_vtable_index(i);
524 } else {
525 if (def_vtable_indices != NULL) {
526 if (is_preinitialized_vtable()) {
527 // At runtime initialize_vtable is rerun as part of link_class_impl()
528 // for a shared class loaded by the non-boot loader.
529 // The dumptime vtable index should be the same as the runtime index.
530 assert(def_vtable_indices->at(default_index) == i,
531 "dump time vtable index is different from runtime index");
532 } else {
533 def_vtable_indices->at_put(default_index, i);
534 }
535 }
536 assert(super_method->is_default_method() || super_method->is_overpass()
537 || super_method->is_abstract(), "default override error");
538 }
539 } else {
540 overrides = false;
541 }
542 log_vtables(i, overrides, target_method, target_klass, super_method, THREAD);
543 }
544 }
545 return allocate_new;
546 }
547
548 void klassVtable::put_method_at(Method* m, int index) {
549 assert(!m->is_private(), "private methods should not be in vtable");
550 if (is_preinitialized_vtable()) {
551 // At runtime initialize_vtable is rerun as part of link_class_impl()
552 // for shared class loaded by the non-boot loader to obtain the loader
553 // constraints based on the runtime classloaders' context. The dumptime
554 // method at the vtable index should be the same as the runtime method.
555 assert(table()[index].method() == m,
556 "archived method is different from the runtime method");
557 } else {
558 if (log_develop_is_enabled(Trace, vtables)) {
559 ResourceMark rm;
560 LogTarget(Trace, vtables) lt;
561 LogStream ls(lt);
562 const char* sig = (m != NULL) ? m->name_and_sig_as_C_string() : "<NULL>";
563 ls.print("adding %s at index %d, flags: ", sig, index);
564 if (m != NULL) {
565 m->print_linkage_flags(&ls);
566 }
567 ls.cr();
568 }
569 table()[index].set(m);
570 }
571 }
572
573 // Find out if a method "m" with superclass "super", loader "classloader" and
574 // name "classname" needs a new vtable entry. Let P be a class package defined
575 // by "classloader" and "classname".
576 // NOTE: The logic used here is very similar to the one used for computing
577 // the vtables indices for a method. We cannot directly use that function because,
578 // we allocate the InstanceKlass at load time, and that requires that the
579 // superclass has been loaded.
580 // However, the vtable entries are filled in at link time, and therefore
581 // the superclass' vtable may not yet have been filled in.
582 bool klassVtable::needs_new_vtable_entry(const methodHandle& target_method,
583 const Klass* super,
584 Handle classloader,
585 Symbol* classname,
586 AccessFlags class_flags,
587 u2 major_version,
588 TRAPS) {
589 if (class_flags.is_interface()) {
590 // Interfaces do not use vtables, except for java.lang.Object methods,
591 // so there is no point to assigning
592 // a vtable index to any of their local methods. If we refrain from doing this,
593 // we can use Method::_vtable_index to hold the itable index
594 return false;
595 }
596
597 if (target_method->is_final_method(class_flags) ||
598 // a final method never needs a new entry; final methods can be statically
599 // resolved and they have to be present in the vtable only if they override
600 // a super's method, in which case they re-use its entry
601 (target_method()->is_private()) ||
602 // private methods don't need to be in vtable
603 (target_method()->is_static()) ||
604 // static methods don't need to be in vtable
605 (target_method()->name()->fast_compare(vmSymbols::object_initializer_name()) == 0)
606 // <init> is never called dynamically-bound
607 ) {
608 return false;
609 }
610
611 // Concrete interface methods do not need new entries, they override
612 // abstract method entries using default inheritance rules
613 if (target_method()->method_holder() != NULL &&
614 target_method()->method_holder()->is_interface() &&
615 !target_method()->is_abstract()) {
616 assert(target_method()->is_default_method(),
617 "unexpected interface method type");
618 return false;
619 }
620
621 // we need a new entry if there is no superclass
622 if (super == NULL) {
623 return true;
624 }
625
626 // Package private methods always need a new entry to root their own
627 // overriding. This allows transitive overriding to work.
628 if (target_method()->is_package_private()) {
629 return true;
630 }
631
632 // search through the super class hierarchy to see if we need
633 // a new entry
634 ResourceMark rm;
635 Symbol* name = target_method()->name();
636 Symbol* signature = target_method()->signature();
637 const Klass* k = super;
638 Method* super_method = NULL;
639 InstanceKlass *holder = NULL;
640 Method* recheck_method = NULL;
641 while (k != NULL) {
642 // lookup through the hierarchy for a method with matching name and sign.
643 super_method = InstanceKlass::cast(k)->lookup_method(name, signature);
644 if (super_method == NULL) {
645 break; // we still have to search for a matching miranda method
646 }
647 // get the class holding the matching method
648 // make sure you use that class for is_override
649 InstanceKlass* superk = super_method->method_holder();
650 // we want only instance method matches
651 // ignore private methods found via lookup_method since they do not participate in overriding,
652 // and since we do override around them: e.g. a.m pub/b.m private/c.m pub,
653 // ignore private, c.m pub does override a.m pub
654 // For classes that were not javac'd together, we also do transitive overriding around
655 // methods that have less accessibility
656 if ((!super_method->is_static()) &&
657 (!super_method->is_private())) {
658 if (superk->is_override(super_method, classloader, classname, THREAD)) {
659 return false;
660 // else keep looking for transitive overrides
661 }
662 }
663
664 // Start with lookup result and continue to search up, for versions supporting transitive override
665 if (major_version >= VTABLE_TRANSITIVE_OVERRIDE_VERSION) {
666 k = superk->super(); // haven't found an override match yet; continue to look
667 } else {
668 break;
669 }
670 }
671
672 // if the target method is public or protected it may have a matching
673 // miranda method in the super, whose entry it should re-use.
674 // Actually, to handle cases that javac would not generate, we need
675 // this check for all access permissions.
676 const InstanceKlass *sk = InstanceKlass::cast(super);
677 if (sk->has_miranda_methods()) {
678 if (sk->lookup_method_in_all_interfaces(name, signature, Klass::find_defaults) != NULL) {
679 return false; // found a matching miranda; we do not need a new entry
680 }
681 }
682 return true; // found no match; we need a new entry
683 }
684
685 // Support for miranda methods
686
687 // get the vtable index of a miranda method with matching "name" and "signature"
688 int klassVtable::index_of_miranda(Symbol* name, Symbol* signature) {
689 // search from the bottom, might be faster
690 for (int i = (length() - 1); i >= 0; i--) {
691 Method* m = table()[i].method();
692 if (is_miranda_entry_at(i) &&
693 m->name() == name && m->signature() == signature) {
694 return i;
695 }
696 }
697 return Method::invalid_vtable_index;
698 }
699
700 // check if an entry at an index is miranda
701 // requires that method m at entry be declared ("held") by an interface.
702 bool klassVtable::is_miranda_entry_at(int i) {
703 Method* m = method_at(i);
704 Klass* method_holder = m->method_holder();
705 InstanceKlass *mhk = InstanceKlass::cast(method_holder);
706
707 // miranda methods are public abstract instance interface methods in a class's vtable
708 if (mhk->is_interface()) {
709 assert(m->is_public(), "should be public");
710 assert(ik()->implements_interface(method_holder) , "this class should implement the interface");
711 if (is_miranda(m, ik()->methods(), ik()->default_methods(), ik()->super(), klass()->is_interface())) {
712 return true;
713 }
714 }
715 return false;
716 }
717
718 // Check if a method is a miranda method, given a class's methods array,
719 // its default_method table and its super class.
720 // "Miranda" means an abstract non-private method that would not be
721 // overridden for the local class.
722 // A "miranda" method should only include non-private interface
723 // instance methods, i.e. not private methods, not static methods,
724 // not default methods (concrete interface methods), not overpass methods.
725 // If a given class already has a local (including overpass) method, a
726 // default method, or any of its superclasses has the same which would have
727 // overridden an abstract method, then this is not a miranda method.
728 //
729 // Miranda methods are checked multiple times.
730 // Pass 1: during class load/class file parsing: before vtable size calculation:
731 // include superinterface abstract and default methods (non-private instance).
732 // We include potential default methods to give them space in the vtable.
733 // During the first run, the current instanceKlass has not yet been
734 // created, the superclasses and superinterfaces do have instanceKlasses
735 // but may not have vtables, the default_methods list is empty, no overpasses.
736 // Default method generation uses the all_mirandas array as the starter set for
737 // maximally-specific default method calculation. So, for both classes and
738 // interfaces, it is necessary that the first pass will find all non-private
739 // interface instance methods, whether or not they are concrete.
740 //
741 // Pass 2: recalculated during vtable initialization: only include abstract methods.
742 // The goal of pass 2 is to walk through the superinterfaces to see if any of
743 // the superinterface methods (which were all abstract pre-default methods)
744 // need to be added to the vtable.
745 // With the addition of default methods, we have three new challenges:
746 // overpasses, static interface methods and private interface methods.
747 // Static and private interface methods do not get added to the vtable and
748 // are not seen by the method resolution process, so we skip those.
749 // Overpass methods are already in the vtable, so vtable lookup will
750 // find them and we don't need to add a miranda method to the end of
751 // the vtable. So we look for overpass methods and if they are found we
752 // return false. Note that we inherit our superclasses vtable, so
753 // the superclass' search also needs to use find_overpass so that if
754 // one is found we return false.
755 // False means - we don't need a miranda method added to the vtable.
756 //
757 // During the second run, default_methods is set up, so concrete methods from
758 // superinterfaces with matching names/signatures to default_methods are already
759 // in the default_methods list and do not need to be appended to the vtable
760 // as mirandas. Abstract methods may already have been handled via
761 // overpasses - either local or superclass overpasses, which may be
762 // in the vtable already.
763 //
764 // Pass 3: They are also checked by link resolution and selection,
765 // for invocation on a method (not interface method) reference that
766 // resolves to a method with an interface as its method_holder.
767 // Used as part of walking from the bottom of the vtable to find
768 // the vtable index for the miranda method.
769 //
770 // Part of the Miranda Rights in the US mean that if you do not have
771 // an attorney one will be appointed for you.
772 bool klassVtable::is_miranda(Method* m, Array<Method*>* class_methods,
773 Array<Method*>* default_methods, const Klass* super,
774 bool is_interface) {
775 if (m->is_static() || m->is_private() || m->is_overpass()) {
776 return false;
777 }
778 Symbol* name = m->name();
779 Symbol* signature = m->signature();
780
781 // First look in local methods to see if already covered
782 if (InstanceKlass::find_local_method(class_methods, name, signature,
783 Klass::find_overpass, Klass::skip_static, Klass::skip_private) != NULL)
784 {
785 return false;
786 }
787
788 // Check local default methods
789 if ((default_methods != NULL) &&
790 (InstanceKlass::find_method(default_methods, name, signature) != NULL))
791 {
792 return false;
793 }
794
795 // Iterate on all superclasses, which should be InstanceKlasses.
796 // Note that we explicitly look for overpasses at each level.
797 // Overpasses may or may not exist for supers for pass 1,
798 // they should have been created for pass 2 and later.
799
800 for (const Klass* cursuper = super; cursuper != NULL; cursuper = cursuper->super())
801 {
802 Method* found_mth = InstanceKlass::cast(cursuper)->find_local_method(name, signature,
803 Klass::find_overpass, Klass::skip_static, Klass::skip_private);
804 // Ignore non-public methods in java.lang.Object if klass is an interface.
805 if (found_mth != NULL && (!is_interface ||
806 !SystemDictionary::is_nonpublic_Object_method(found_mth))) {
807 return false;
808 }
809 }
810
811 return true;
812 }
813
814 // Scans current_interface_methods for miranda methods that do not
815 // already appear in new_mirandas, or default methods, and are also not defined-and-non-private
816 // in super (superclass). These mirandas are added to all_mirandas if it is
817 // not null; in addition, those that are not duplicates of miranda methods
818 // inherited by super from its interfaces are added to new_mirandas.
819 // Thus, new_mirandas will be the set of mirandas that this class introduces,
820 // all_mirandas will be the set of all mirandas applicable to this class
821 // including all defined in superclasses.
822 void klassVtable::add_new_mirandas_to_lists(
823 GrowableArray<Method*>* new_mirandas, GrowableArray<Method*>* all_mirandas,
824 Array<Method*>* current_interface_methods, Array<Method*>* class_methods,
825 Array<Method*>* default_methods, const Klass* super, bool is_interface) {
826
827 // iterate thru the current interface's method to see if it a miranda
828 int num_methods = current_interface_methods->length();
829 for (int i = 0; i < num_methods; i++) {
830 Method* im = current_interface_methods->at(i);
831 bool is_duplicate = false;
832 int num_of_current_mirandas = new_mirandas->length();
833 // check for duplicate mirandas in different interfaces we implement
834 for (int j = 0; j < num_of_current_mirandas; j++) {
835 Method* miranda = new_mirandas->at(j);
836 if ((im->name() == miranda->name()) &&
837 (im->signature() == miranda->signature())) {
838 is_duplicate = true;
839 break;
840 }
841 }
842
843 if (!is_duplicate) { // we don't want duplicate miranda entries in the vtable
844 if (is_miranda(im, class_methods, default_methods, super, is_interface)) { // is it a miranda at all?
845 const InstanceKlass *sk = InstanceKlass::cast(super);
846 // check if it is a duplicate of a super's miranda
847 if (sk->lookup_method_in_all_interfaces(im->name(), im->signature(), Klass::find_defaults) == NULL) {
848 new_mirandas->append(im);
849 }
850 if (all_mirandas != NULL) {
851 all_mirandas->append(im);
852 }
853 }
854 }
855 }
856 }
857
858 void klassVtable::get_mirandas(GrowableArray<Method*>* new_mirandas,
859 GrowableArray<Method*>* all_mirandas,
860 const Klass* super,
861 Array<Method*>* class_methods,
862 Array<Method*>* default_methods,
863 Array<InstanceKlass*>* local_interfaces,
864 bool is_interface) {
865 assert((new_mirandas->length() == 0) , "current mirandas must be 0");
866
867 // iterate thru the local interfaces looking for a miranda
868 int num_local_ifs = local_interfaces->length();
869 for (int i = 0; i < num_local_ifs; i++) {
870 InstanceKlass *ik = InstanceKlass::cast(local_interfaces->at(i));
871 add_new_mirandas_to_lists(new_mirandas, all_mirandas,
872 ik->methods(), class_methods,
873 default_methods, super, is_interface);
874 // iterate thru each local's super interfaces
875 Array<InstanceKlass*>* super_ifs = ik->transitive_interfaces();
876 int num_super_ifs = super_ifs->length();
877 for (int j = 0; j < num_super_ifs; j++) {
878 InstanceKlass *sik = super_ifs->at(j);
879 add_new_mirandas_to_lists(new_mirandas, all_mirandas,
880 sik->methods(), class_methods,
881 default_methods, super, is_interface);
882 }
883 }
884 }
885
886 // Discover miranda methods ("miranda" = "interface abstract, no binding"),
887 // and append them into the vtable starting at index initialized,
888 // return the new value of initialized.
889 // Miranda methods use vtable entries, but do not get assigned a vtable_index
890 // The vtable_index is discovered by searching from the end of the vtable
891 int klassVtable::fill_in_mirandas(int initialized, TRAPS) {
892 ResourceMark rm(THREAD);
893 GrowableArray<Method*> mirandas(20);
894 get_mirandas(&mirandas, NULL, ik()->super(), ik()->methods(),
895 ik()->default_methods(), ik()->local_interfaces(),
896 klass()->is_interface());
897 for (int i = 0; i < mirandas.length(); i++) {
898 if (log_develop_is_enabled(Trace, vtables)) {
899 Method* meth = mirandas.at(i);
900 LogTarget(Trace, vtables) lt;
901 LogStream ls(lt);
902 if (meth != NULL) {
903 char* sig = meth->name_and_sig_as_C_string();
904 ls.print("fill in mirandas with %s index %d, flags: ",
905 sig, initialized);
906 meth->print_linkage_flags(&ls);
907 ls.cr();
908 }
909 }
910 put_method_at(mirandas.at(i), initialized);
911 ++initialized;
912 }
913 return initialized;
914 }
915
916 // Copy this class's vtable to the vtable beginning at start.
917 // Used to copy superclass vtable to prefix of subclass's vtable.
918 void klassVtable::copy_vtable_to(vtableEntry* start) {
919 Copy::disjoint_words((HeapWord*)table(), (HeapWord*)start, _length * vtableEntry::size());
920 }
921
922 #if INCLUDE_JVMTI
923 bool klassVtable::adjust_default_method(int vtable_index, Method* old_method, Method* new_method) {
924 // If old_method is default, find this vtable index in default_vtable_indices
925 // and replace that method in the _default_methods list
926 bool updated = false;
927
928 Array<Method*>* default_methods = ik()->default_methods();
929 if (default_methods != NULL) {
930 int len = default_methods->length();
931 for (int idx = 0; idx < len; idx++) {
932 if (vtable_index == ik()->default_vtable_indices()->at(idx)) {
933 if (default_methods->at(idx) == old_method) {
934 default_methods->at_put(idx, new_method);
935 updated = true;
936 }
937 break;
938 }
939 }
940 }
941 return updated;
942 }
943
944 // search the vtable for uses of either obsolete or EMCP methods
945 void klassVtable::adjust_method_entries(bool * trace_name_printed) {
946 int prn_enabled = 0;
947 for (int index = 0; index < length(); index++) {
948 Method* old_method = unchecked_method_at(index);
949 if (old_method == NULL || !old_method->is_old()) {
950 continue; // skip uninteresting entries
951 }
952 assert(!old_method->is_deleted(), "vtable methods may not be deleted");
953
954 Method* new_method = old_method->get_new_method();
955 put_method_at(new_method, index);
956
957 // For default methods, need to update the _default_methods array
958 // which can only have one method entry for a given signature
959 bool updated_default = false;
960 if (old_method->is_default_method()) {
961 updated_default = adjust_default_method(index, old_method, new_method);
962 }
963
964 if (log_is_enabled(Info, redefine, class, update)) {
965 ResourceMark rm;
966 if (!(*trace_name_printed)) {
967 log_info(redefine, class, update)
968 ("adjust: klassname=%s for methods from name=%s",
969 _klass->external_name(), old_method->method_holder()->external_name());
970 *trace_name_printed = true;
971 }
972 log_debug(redefine, class, update, vtables)
973 ("vtable method update: %s(%s), updated default = %s",
974 new_method->name()->as_C_string(), new_method->signature()->as_C_string(), updated_default ? "true" : "false");
975 }
976 }
977 }
978
979 // a vtable should never contain old or obsolete methods
980 bool klassVtable::check_no_old_or_obsolete_entries() {
981 for (int i = 0; i < length(); i++) {
982 Method* m = unchecked_method_at(i);
983 if (m != NULL &&
984 (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) {
985 return false;
986 }
987 }
988 return true;
989 }
990
991 void klassVtable::dump_vtable() {
992 tty->print_cr("vtable dump --");
993 for (int i = 0; i < length(); i++) {
994 Method* m = unchecked_method_at(i);
995 if (m != NULL) {
996 tty->print(" (%5d) ", i);
997 m->access_flags().print_on(tty);
998 if (m->is_default_method()) {
999 tty->print("default ");
1000 }
1001 if (m->is_overpass()) {
1002 tty->print("overpass");
1003 }
1004 tty->print(" -- ");
1005 m->print_name(tty);
1006 tty->cr();
1007 }
1008 }
1009 }
1010 #endif // INCLUDE_JVMTI
1011
1012 // CDS/RedefineClasses support - clear vtables so they can be reinitialized
1013 void klassVtable::clear_vtable() {
1014 for (int i = 0; i < _length; i++) table()[i].clear();
1015 }
1016
1017 bool klassVtable::is_initialized() {
1018 return _length == 0 || table()[0].method() != NULL;
1019 }
1020
1021 //-----------------------------------------------------------------------------------------
1022 // Itable code
1023
1024 // Initialize a itableMethodEntry
1025 void itableMethodEntry::initialize(Method* m) {
1026 if (m == NULL) return;
1027
1028 #ifdef ASSERT
1029 if (MetaspaceShared::is_in_shared_metaspace((void*)&_method) &&
1030 !MetaspaceShared::remapped_readwrite()) {
1031 // At runtime initialize_itable is rerun as part of link_class_impl()
1032 // for a shared class loaded by the non-boot loader.
1033 // The dumptime itable method entry should be the same as the runtime entry.
1034 assert(_method == m, "sanity");
1035 }
1036 #endif
1037 _method = m;
1038 }
1039
1040 klassItable::klassItable(InstanceKlass* klass) {
1041 _klass = klass;
1042
1043 if (klass->itable_length() > 0) {
1044 itableOffsetEntry* offset_entry = (itableOffsetEntry*)klass->start_of_itable();
1045 if (offset_entry != NULL && offset_entry->interface_klass() != NULL) { // Check that itable is initialized
1046 // First offset entry points to the first method_entry
1047 intptr_t* method_entry = (intptr_t *)(((address)klass) + offset_entry->offset());
1048 intptr_t* end = klass->end_of_itable();
1049
1050 _table_offset = (intptr_t*)offset_entry - (intptr_t*)klass;
1051 _size_offset_table = (method_entry - ((intptr_t*)offset_entry)) / itableOffsetEntry::size();
1052 _size_method_table = (end - method_entry) / itableMethodEntry::size();
1053 assert(_table_offset >= 0 && _size_offset_table >= 0 && _size_method_table >= 0, "wrong computation");
1054 return;
1055 }
1056 }
1057
1058 // The length of the itable was either zero, or it has not yet been initialized.
1059 _table_offset = 0;
1060 _size_offset_table = 0;
1061 _size_method_table = 0;
1062 }
1063
1064 static int initialize_count = 0;
1065
1066 // Initialization
1067 void klassItable::initialize_itable(bool checkconstraints, TRAPS) {
1068 if (_klass->is_interface()) {
1069 // This needs to go after vtable indices are assigned but
1070 // before implementors need to know the number of itable indices.
1071 assign_itable_indices_for_interface(InstanceKlass::cast(_klass), THREAD);
1072 }
1073
1074 // Cannot be setup doing bootstrapping, interfaces don't have
1075 // itables, and klass with only ones entry have empty itables
1076 if (Universe::is_bootstrapping() ||
1077 _klass->is_interface() ||
1078 _klass->itable_length() == itableOffsetEntry::size()) return;
1079
1080 // There's alway an extra itable entry so we can null-terminate it.
1081 guarantee(size_offset_table() >= 1, "too small");
1082 int num_interfaces = size_offset_table() - 1;
1083 if (num_interfaces > 0) {
1084 ResourceMark rm(THREAD);
1085 log_develop_debug(itables)("%3d: Initializing itables for %s", ++initialize_count,
1086 _klass->name()->as_C_string());
1087
1088
1089 // Iterate through all interfaces
1090 int i;
1091 for(i = 0; i < num_interfaces; i++) {
1092 itableOffsetEntry* ioe = offset_entry(i);
1093 HandleMark hm(THREAD);
1094 Klass* interf = ioe->interface_klass();
1095 assert(interf != NULL && ioe->offset() != 0, "bad offset entry in itable");
1096 initialize_itable_for_interface(ioe->offset(), InstanceKlass::cast(interf), checkconstraints, CHECK);
1097 }
1098
1099 }
1100 // Check that the last entry is empty
1101 itableOffsetEntry* ioe = offset_entry(size_offset_table() - 1);
1102 guarantee(ioe->interface_klass() == NULL && ioe->offset() == 0, "terminator entry missing");
1103 }
1104
1105
1106 inline bool interface_method_needs_itable_index(Method* m) {
1107 if (m->is_static()) return false; // e.g., Stream.empty
1108 if (m->is_initializer()) return false; // <init> or <clinit>
1109 if (m->is_private()) return false; // uses direct call
1110 // If an interface redeclares a method from java.lang.Object,
1111 // it should already have a vtable index, don't touch it.
1112 // e.g., CharSequence.toString (from initialize_vtable)
1113 // if (m->has_vtable_index()) return false; // NO!
1114 return true;
1115 }
1116
1117 int klassItable::assign_itable_indices_for_interface(InstanceKlass* klass, TRAPS) {
1118 // an interface does not have an itable, but its methods need to be numbered
1119 ResourceMark rm(THREAD);
1120 log_develop_debug(itables)("%3d: Initializing itable indices for interface %s",
1121 ++initialize_count, klass->name()->as_C_string());
1122 Array<Method*>* methods = klass->methods();
1123 int nof_methods = methods->length();
1124 int ime_num = 0;
1125 for (int i = 0; i < nof_methods; i++) {
1126 Method* m = methods->at(i);
1127 if (interface_method_needs_itable_index(m)) {
1128 assert(!m->is_final_method(), "no final interface methods");
1129 // If m is already assigned a vtable index, do not disturb it.
1130 if (log_develop_is_enabled(Trace, itables)) {
1131 LogTarget(Trace, itables) lt;
1132 LogStream ls(lt);
1133 assert(m != NULL, "methods can never be null");
1134 const char* sig = m->name_and_sig_as_C_string();
1135 if (m->has_vtable_index()) {
1136 ls.print("vtable index %d for method: %s, flags: ", m->vtable_index(), sig);
1137 } else {
1138 ls.print("itable index %d for method: %s, flags: ", ime_num, sig);
1139 }
1140 m->print_linkage_flags(&ls);
1141 ls.cr();
1142 }
1143 if (!m->has_vtable_index()) {
1144 // A shared method could have an initialized itable_index that
1145 // is < 0.
1146 assert(m->vtable_index() == Method::pending_itable_index ||
1147 m->is_shared(),
1148 "set by initialize_vtable");
1149 m->set_itable_index(ime_num);
1150 // Progress to next itable entry
1151 ime_num++;
1152 }
1153 }
1154 }
1155 assert(ime_num == method_count_for_interface(klass), "proper sizing");
1156 return ime_num;
1157 }
1158
1159 int klassItable::method_count_for_interface(InstanceKlass* interf) {
1160 assert(interf->is_interface(), "must be");
1161 Array<Method*>* methods = interf->methods();
1162 int nof_methods = methods->length();
1163 int length = 0;
1164 while (nof_methods > 0) {
1165 Method* m = methods->at(nof_methods-1);
1166 if (m->has_itable_index()) {
1167 length = m->itable_index() + 1;
1168 break;
1169 }
1170 nof_methods -= 1;
1171 }
1172 #ifdef ASSERT
1173 int nof_methods_copy = nof_methods;
1174 while (nof_methods_copy > 0) {
1175 Method* mm = methods->at(--nof_methods_copy);
1176 assert(!mm->has_itable_index() || mm->itable_index() < length, "");
1177 }
1178 #endif //ASSERT
1179 // return the rightmost itable index, plus one; or 0 if no methods have
1180 // itable indices
1181 return length;
1182 }
1183
1184
1185 void klassItable::initialize_itable_for_interface(int method_table_offset, InstanceKlass* interf, bool checkconstraints, TRAPS) {
1186 assert(interf->is_interface(), "must be");
1187 Array<Method*>* methods = interf->methods();
1188 int nof_methods = methods->length();
1189 HandleMark hm;
1190 Handle interface_loader (THREAD, interf->class_loader());
1191
1192 int ime_count = method_count_for_interface(interf);
1193 for (int i = 0; i < nof_methods; i++) {
1194 Method* m = methods->at(i);
1195 methodHandle target;
1196 if (m->has_itable_index()) {
1197 // This search must match the runtime resolution, i.e. selection search for invokeinterface
1198 // to correctly enforce loader constraints for interface method inheritance.
1199 // Private methods are skipped as a private class method can never be the implementation
1200 // of an interface method.
1201 // Invokespecial does not perform selection based on the receiver, so it does not use
1202 // the cached itable.
1203 target = LinkResolver::lookup_instance_method_in_klasses(_klass, m->name(), m->signature(),
1204 Klass::skip_private, CHECK);
1205 }
1206 if (target == NULL || !target->is_public() || target->is_abstract() || target->is_overpass()) {
1207 assert(target == NULL || !target->is_overpass() || target->is_public(),
1208 "Non-public overpass method!");
1209 // Entry does not resolve. Leave it empty for AbstractMethodError or other error.
1210 if (!(target == NULL) && !target->is_public()) {
1211 // Stuff an IllegalAccessError throwing method in there instead.
1212 itableOffsetEntry::method_entry(_klass, method_table_offset)[m->itable_index()].
1213 initialize(Universe::throw_illegal_access_error());
1214 }
1215 } else {
1216 // Entry did resolve, check loader constraints before initializing
1217 // if checkconstraints requested
1218 if (checkconstraints) {
1219 Handle method_holder_loader (THREAD, target->method_holder()->class_loader());
1220 if (!oopDesc::equals(method_holder_loader(), interface_loader())) {
1221 ResourceMark rm(THREAD);
1222 Symbol* failed_type_symbol =
1223 SystemDictionary::check_signature_loaders(m->signature(),
1224 method_holder_loader,
1225 interface_loader,
1226 true, CHECK);
1227 if (failed_type_symbol != NULL) {
1228 stringStream ss;
1229 ss.print("loader constraint violation in interface itable"
1230 " initialization for class %s: when selecting method '",
1231 _klass->external_name());
1232 m->print_external_name(&ss),
1233 ss.print("' the class loader %s for super interface %s, and the class"
1234 " loader %s of the selected method's %s, %s have"
1235 " different Class objects for the type %s used in the signature (%s; %s)",
1236 interf->class_loader_data()->loader_name_and_id(),
1237 interf->external_name(),
1238 target()->method_holder()->class_loader_data()->loader_name_and_id(),
1239 target()->method_holder()->external_kind(),
1240 target()->method_holder()->external_name(),
1241 failed_type_symbol->as_klass_external_name(),
1242 interf->class_in_module_of_loader(false, true),
1243 target()->method_holder()->class_in_module_of_loader(false, true));
1244 THROW_MSG(vmSymbols::java_lang_LinkageError(), ss.as_string());
1245 }
1246 }
1247 }
1248
1249 // ime may have moved during GC so recalculate address
1250 int ime_num = m->itable_index();
1251 assert(ime_num < ime_count, "oob");
1252 itableOffsetEntry::method_entry(_klass, method_table_offset)[ime_num].initialize(target());
1253 if (log_develop_is_enabled(Trace, itables)) {
1254 ResourceMark rm(THREAD);
1255 if (target() != NULL) {
1256 LogTarget(Trace, itables) lt;
1257 LogStream ls(lt);
1258 char* sig = target()->name_and_sig_as_C_string();
1259 ls.print("interface: %s, ime_num: %d, target: %s, method_holder: %s ",
1260 interf->internal_name(), ime_num, sig,
1261 target()->method_holder()->internal_name());
1262 ls.print("target_method flags: ");
1263 target()->print_linkage_flags(&ls);
1264 ls.cr();
1265 }
1266 }
1267 }
1268 }
1269 }
1270
1271 #if INCLUDE_JVMTI
1272 // search the itable for uses of either obsolete or EMCP methods
1273 void klassItable::adjust_method_entries(bool * trace_name_printed) {
1274
1275 itableMethodEntry* ime = method_entry(0);
1276 for (int i = 0; i < _size_method_table; i++, ime++) {
1277 Method* old_method = ime->method();
1278 if (old_method == NULL || !old_method->is_old()) {
1279 continue; // skip uninteresting entries
1280 }
1281 assert(!old_method->is_deleted(), "itable methods may not be deleted");
1282 Method* new_method = old_method->get_new_method();
1283 ime->initialize(new_method);
1284
1285 if (log_is_enabled(Info, redefine, class, update)) {
1286 ResourceMark rm;
1287 if (!(*trace_name_printed)) {
1288 log_info(redefine, class, update)("adjust: name=%s", old_method->method_holder()->external_name());
1289 *trace_name_printed = true;
1290 }
1291 log_trace(redefine, class, update, itables)
1292 ("itable method update: %s(%s)", new_method->name()->as_C_string(), new_method->signature()->as_C_string());
1293 }
1294 }
1295 }
1296
1297 // an itable should never contain old or obsolete methods
1298 bool klassItable::check_no_old_or_obsolete_entries() {
1299 itableMethodEntry* ime = method_entry(0);
1300 for (int i = 0; i < _size_method_table; i++) {
1301 Method* m = ime->method();
1302 if (m != NULL &&
1303 (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) {
1304 return false;
1305 }
1306 ime++;
1307 }
1308 return true;
1309 }
1310
1311 void klassItable::dump_itable() {
1312 itableMethodEntry* ime = method_entry(0);
1313 tty->print_cr("itable dump --");
1314 for (int i = 0; i < _size_method_table; i++) {
1315 Method* m = ime->method();
1316 if (m != NULL) {
1317 tty->print(" (%5d) ", i);
1318 m->access_flags().print_on(tty);
1319 if (m->is_default_method()) {
1320 tty->print("default ");
1321 }
1322 tty->print(" -- ");
1323 m->print_name(tty);
1324 tty->cr();
1325 }
1326 ime++;
1327 }
1328 }
1329 #endif // INCLUDE_JVMTI
1330
1331 // Setup
1332 class InterfaceVisiterClosure : public StackObj {
1333 public:
1334 virtual void doit(InstanceKlass* intf, int method_count) = 0;
1335 };
1336
1337 // Visit all interfaces with at least one itable method
1338 void visit_all_interfaces(Array<InstanceKlass*>* transitive_intf, InterfaceVisiterClosure *blk) {
1339 // Handle array argument
1340 for(int i = 0; i < transitive_intf->length(); i++) {
1341 InstanceKlass* intf = transitive_intf->at(i);
1342 assert(intf->is_interface(), "sanity check");
1343
1344 // Find no. of itable methods
1345 int method_count = 0;
1346 // method_count = klassItable::method_count_for_interface(intf);
1347 Array<Method*>* methods = intf->methods();
1348 if (methods->length() > 0) {
1349 for (int i = methods->length(); --i >= 0; ) {
1350 if (interface_method_needs_itable_index(methods->at(i))) {
1351 method_count++;
1352 }
1353 }
1354 }
1355
1356 // Visit all interfaces which either have any methods or can participate in receiver type check.
1357 // We do not bother to count methods in transitive interfaces, although that would allow us to skip
1358 // this step in the rare case of a zero-method interface extending another zero-method interface.
1359 if (method_count > 0 || intf->transitive_interfaces()->length() > 0) {
1360 blk->doit(intf, method_count);
1361 }
1362 }
1363 }
1364
1365 class CountInterfacesClosure : public InterfaceVisiterClosure {
1366 private:
1367 int _nof_methods;
1368 int _nof_interfaces;
1369 public:
1370 CountInterfacesClosure() { _nof_methods = 0; _nof_interfaces = 0; }
1371
1372 int nof_methods() const { return _nof_methods; }
1373 int nof_interfaces() const { return _nof_interfaces; }
1374
1375 void doit(InstanceKlass* intf, int method_count) { _nof_methods += method_count; _nof_interfaces++; }
1376 };
1377
1378 class SetupItableClosure : public InterfaceVisiterClosure {
1379 private:
1380 itableOffsetEntry* _offset_entry;
1381 itableMethodEntry* _method_entry;
1382 address _klass_begin;
1383 public:
1384 SetupItableClosure(address klass_begin, itableOffsetEntry* offset_entry, itableMethodEntry* method_entry) {
1385 _klass_begin = klass_begin;
1386 _offset_entry = offset_entry;
1387 _method_entry = method_entry;
1388 }
1389
1390 itableMethodEntry* method_entry() const { return _method_entry; }
1391
1392 void doit(InstanceKlass* intf, int method_count) {
1393 int offset = ((address)_method_entry) - _klass_begin;
1394 _offset_entry->initialize(intf, offset);
1395 _offset_entry++;
1396 _method_entry += method_count;
1397 }
1398 };
1399
1400 int klassItable::compute_itable_size(Array<InstanceKlass*>* transitive_interfaces) {
1401 // Count no of interfaces and total number of interface methods
1402 CountInterfacesClosure cic;
1403 visit_all_interfaces(transitive_interfaces, &cic);
1404
1405 // There's alway an extra itable entry so we can null-terminate it.
1406 int itable_size = calc_itable_size(cic.nof_interfaces() + 1, cic.nof_methods());
1407
1408 // Statistics
1409 update_stats(itable_size * wordSize);
1410
1411 return itable_size;
1412 }
1413
1414
1415 // Fill out offset table and interface klasses into the itable space
1416 void klassItable::setup_itable_offset_table(InstanceKlass* klass) {
1417 if (klass->itable_length() == 0) return;
1418 assert(!klass->is_interface(), "Should have zero length itable");
1419
1420 // Count no of interfaces and total number of interface methods
1421 CountInterfacesClosure cic;
1422 visit_all_interfaces(klass->transitive_interfaces(), &cic);
1423 int nof_methods = cic.nof_methods();
1424 int nof_interfaces = cic.nof_interfaces();
1425
1426 // Add one extra entry so we can null-terminate the table
1427 nof_interfaces++;
1428
1429 assert(compute_itable_size(klass->transitive_interfaces()) ==
1430 calc_itable_size(nof_interfaces, nof_methods),
1431 "mismatch calculation of itable size");
1432
1433 // Fill-out offset table
1434 itableOffsetEntry* ioe = (itableOffsetEntry*)klass->start_of_itable();
1435 itableMethodEntry* ime = (itableMethodEntry*)(ioe + nof_interfaces);
1436 intptr_t* end = klass->end_of_itable();
1437 assert((oop*)(ime + nof_methods) <= (oop*)klass->start_of_nonstatic_oop_maps(), "wrong offset calculation (1)");
1438 assert((oop*)(end) == (oop*)(ime + nof_methods), "wrong offset calculation (2)");
1439
1440 // Visit all interfaces and initialize itable offset table
1441 SetupItableClosure sic((address)klass, ioe, ime);
1442 visit_all_interfaces(klass->transitive_interfaces(), &sic);
1443
1444 #ifdef ASSERT
1445 ime = sic.method_entry();
1446 oop* v = (oop*) klass->end_of_itable();
1447 assert( (oop*)(ime) == v, "wrong offset calculation (2)");
1448 #endif
1449 }
1450
1451
1452 // inverse to itable_index
1453 Method* klassItable::method_for_itable_index(InstanceKlass* intf, int itable_index) {
1454 assert(intf->is_interface(), "sanity check");
1455 assert(intf->verify_itable_index(itable_index), "");
1456 Array<Method*>* methods = InstanceKlass::cast(intf)->methods();
1457
1458 if (itable_index < 0 || itable_index >= method_count_for_interface(intf))
1459 return NULL; // help caller defend against bad indices
1460
1461 int index = itable_index;
1462 Method* m = methods->at(index);
1463 int index2 = -1;
1464 while (!m->has_itable_index() ||
1465 (index2 = m->itable_index()) != itable_index) {
1466 assert(index2 < itable_index, "monotonic");
1467 if (++index == methods->length())
1468 return NULL;
1469 m = methods->at(index);
1470 }
1471 assert(m->itable_index() == itable_index, "correct inverse");
1472
1473 return m;
1474 }
1475
1476 void klassVtable::verify(outputStream* st, bool forced) {
1477 // make sure table is initialized
1478 if (!Universe::is_fully_initialized()) return;
1479 #ifndef PRODUCT
1480 // avoid redundant verifies
1481 if (!forced && _verify_count == Universe::verify_count()) return;
1482 _verify_count = Universe::verify_count();
1483 #endif
1484 oop* end_of_obj = (oop*)_klass + _klass->size();
1485 oop* end_of_vtable = (oop *)&table()[_length];
1486 if (end_of_vtable > end_of_obj) {
1487 ResourceMark rm;
1488 fatal("klass %s: klass object too short (vtable extends beyond end)",
1489 _klass->internal_name());
1490 }
1491
1492 for (int i = 0; i < _length; i++) table()[i].verify(this, st);
1493 // verify consistency with superKlass vtable
1494 Klass* super = _klass->super();
1495 if (super != NULL) {
1496 InstanceKlass* sk = InstanceKlass::cast(super);
1497 klassVtable vt = sk->vtable();
1498 for (int i = 0; i < vt.length(); i++) {
1499 verify_against(st, &vt, i);
1500 }
1501 }
1502 }
1503
1504 void klassVtable::verify_against(outputStream* st, klassVtable* vt, int index) {
1505 vtableEntry* vte = &vt->table()[index];
1506 if (vte->method()->name() != table()[index].method()->name() ||
1507 vte->method()->signature() != table()[index].method()->signature()) {
1508 fatal("mismatched name/signature of vtable entries");
1509 }
1510 }
1511
1512 #ifndef PRODUCT
1513 void klassVtable::print() {
1514 ResourceMark rm;
1515 tty->print("klassVtable for klass %s (length %d):\n", _klass->internal_name(), length());
1516 for (int i = 0; i < length(); i++) {
1517 table()[i].print();
1518 tty->cr();
1519 }
1520 }
1521 #endif
1522
1523 void vtableEntry::verify(klassVtable* vt, outputStream* st) {
1524 NOT_PRODUCT(FlagSetting fs(IgnoreLockingAssertions, true));
1525 Klass* vtklass = vt->klass();
1526 if (vtklass->is_instance_klass() &&
1527 (InstanceKlass::cast(vtklass)->major_version() >= klassVtable::VTABLE_TRANSITIVE_OVERRIDE_VERSION)) {
1528 assert(method() != NULL, "must have set method");
1529 }
1530 if (method() != NULL) {
1531 method()->verify();
1532 // we sub_type, because it could be a miranda method
1533 if (!vtklass->is_subtype_of(method()->method_holder())) {
1534 #ifndef PRODUCT
1535 print();
1536 #endif
1537 fatal("vtableEntry " PTR_FORMAT ": method is from subclass", p2i(this));
1538 }
1539 }
1540 }
1541
1542 #ifndef PRODUCT
1543
1544 void vtableEntry::print() {
1545 ResourceMark rm;
1546 tty->print("vtableEntry %s: ", method()->name()->as_C_string());
1547 if (Verbose) {
1548 tty->print("m " PTR_FORMAT " ", p2i(method()));
1549 }
1550 }
1551
1552 class VtableStats : AllStatic {
1553 public:
1554 static int no_klasses; // # classes with vtables
1555 static int no_array_klasses; // # array classes
1556 static int no_instance_klasses; // # instanceKlasses
1557 static int sum_of_vtable_len; // total # of vtable entries
1558 static int sum_of_array_vtable_len; // total # of vtable entries in array klasses only
1559 static int fixed; // total fixed overhead in bytes
1560 static int filler; // overhead caused by filler bytes
1561 static int entries; // total bytes consumed by vtable entries
1562 static int array_entries; // total bytes consumed by array vtable entries
1563
1564 static void do_class(Klass* k) {
1565 Klass* kl = k;
1566 klassVtable vt = kl->vtable();
1567 no_klasses++;
1568 if (kl->is_instance_klass()) {
1569 no_instance_klasses++;
1570 kl->array_klasses_do(do_class);
1571 }
1572 if (kl->is_array_klass()) {
1573 no_array_klasses++;
1574 sum_of_array_vtable_len += vt.length();
1575 }
1576 sum_of_vtable_len += vt.length();
1577 }
1578
1579 static void compute() {
1580 LockedClassesDo locked_do_class(&do_class);
1581 ClassLoaderDataGraph::classes_do(&locked_do_class);
1582 fixed = no_klasses * oopSize; // vtable length
1583 // filler size is a conservative approximation
1584 filler = oopSize * (no_klasses - no_instance_klasses) * (sizeof(InstanceKlass) - sizeof(ArrayKlass) - 1);
1585 entries = sizeof(vtableEntry) * sum_of_vtable_len;
1586 array_entries = sizeof(vtableEntry) * sum_of_array_vtable_len;
1587 }
1588 };
1589
1590 int VtableStats::no_klasses = 0;
1591 int VtableStats::no_array_klasses = 0;
1592 int VtableStats::no_instance_klasses = 0;
1593 int VtableStats::sum_of_vtable_len = 0;
1594 int VtableStats::sum_of_array_vtable_len = 0;
1595 int VtableStats::fixed = 0;
1596 int VtableStats::filler = 0;
1597 int VtableStats::entries = 0;
1598 int VtableStats::array_entries = 0;
1599
1600 void klassVtable::print_statistics() {
1601 ResourceMark rm;
1602 HandleMark hm;
1603 VtableStats::compute();
1604 tty->print_cr("vtable statistics:");
1605 tty->print_cr("%6d classes (%d instance, %d array)", VtableStats::no_klasses, VtableStats::no_instance_klasses, VtableStats::no_array_klasses);
1606 int total = VtableStats::fixed + VtableStats::filler + VtableStats::entries;
1607 tty->print_cr("%6d bytes fixed overhead (refs + vtable object header)", VtableStats::fixed);
1608 tty->print_cr("%6d bytes filler overhead", VtableStats::filler);
1609 tty->print_cr("%6d bytes for vtable entries (%d for arrays)", VtableStats::entries, VtableStats::array_entries);
1610 tty->print_cr("%6d bytes total", total);
1611 }
1612
1613 int klassItable::_total_classes; // Total no. of classes with itables
1614 long klassItable::_total_size; // Total no. of bytes used for itables
1615
1616 void klassItable::print_statistics() {
1617 tty->print_cr("itable statistics:");
1618 tty->print_cr("%6d classes with itables", _total_classes);
1619 tty->print_cr("%6lu K uses for itables (average by class: %ld bytes)", _total_size / K, _total_size / _total_classes);
1620 }
1621
1622 #endif // PRODUCT