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 bool found_pkg_prvt_method = false;
642 while (k != NULL) {
643 // lookup through the hierarchy for a method with matching name and sign.
644 super_method = InstanceKlass::cast(k)->lookup_method(name, signature);
645 if (super_method == NULL) {
646 break; // we still have to search for a matching miranda method
647 }
648 // get the class holding the matching method
649 // make sure you use that class for is_override
650 InstanceKlass* superk = super_method->method_holder();
651 // we want only instance method matches
652 // ignore private methods found via lookup_method since they do not participate in overriding,
653 // and since we do override around them: e.g. a.m pub/b.m private/c.m pub,
654 // ignore private, c.m pub does override a.m pub
655 // For classes that were not javac'd together, we also do transitive overriding around
656 // methods that have less accessibility
657 if ((!super_method->is_static()) &&
658 (!super_method->is_private())) {
659 if (superk->is_override(super_method, classloader, classname, THREAD)) {
660 return false;
661 // else keep looking for transitive overrides
662 }
663 // If we get here then one of the super classes has a package private method
664 // that will not get overridden because it is in a different package. But,
665 // that package private method does "override" any matching methods in super
666 // interfaces, so there will be no miranda vtable entry created. So, set flag
667 // to TRUE for use below, in case there are no methods in super classes that
668 // this target method overrides.
669 assert(super_method->is_package_private(), "super_method must be package private");
670 assert(!superk->is_same_class_package(classloader(), classname),
671 "Must be different packages");
672 found_pkg_prvt_method = true;
673 }
674
675 // Start with lookup result and continue to search up, for versions supporting transitive override
676 if (major_version >= VTABLE_TRANSITIVE_OVERRIDE_VERSION) {
677 k = superk->super(); // haven't found an override match yet; continue to look
678 } else {
679 break;
680 }
681 }
682
683 // If found_pkg_prvt_method is set, then the ONLY matching method in the
684 // superclasses is package private in another package. That matching method will
685 // prevent a miranda vtable entry from being created. Because the target method can not
686 // override the package private method in another package, then it needs to be the root
687 // for its own vtable entry.
688 if (found_pkg_prvt_method) {
689 return true;
690 }
691
692 // if the target method is public or protected it may have a matching
693 // miranda method in the super, whose entry it should re-use.
694 // Actually, to handle cases that javac would not generate, we need
695 // this check for all access permissions.
696 const InstanceKlass *sk = InstanceKlass::cast(super);
697 if (sk->has_miranda_methods()) {
698 if (sk->lookup_method_in_all_interfaces(name, signature, Klass::find_defaults) != NULL) {
699 return false; // found a matching miranda; we do not need a new entry
700 }
701 }
702 return true; // found no match; we need a new entry
703 }
704
705 // Support for miranda methods
706
707 // get the vtable index of a miranda method with matching "name" and "signature"
708 int klassVtable::index_of_miranda(Symbol* name, Symbol* signature) {
709 // search from the bottom, might be faster
710 for (int i = (length() - 1); i >= 0; i--) {
711 Method* m = table()[i].method();
712 if (is_miranda_entry_at(i) &&
713 m->name() == name && m->signature() == signature) {
714 return i;
715 }
716 }
717 return Method::invalid_vtable_index;
718 }
719
720 // check if an entry at an index is miranda
721 // requires that method m at entry be declared ("held") by an interface.
722 bool klassVtable::is_miranda_entry_at(int i) {
723 Method* m = method_at(i);
724 Klass* method_holder = m->method_holder();
725 InstanceKlass *mhk = InstanceKlass::cast(method_holder);
726
727 // miranda methods are public abstract instance interface methods in a class's vtable
728 if (mhk->is_interface()) {
729 assert(m->is_public(), "should be public");
730 assert(ik()->implements_interface(method_holder) , "this class should implement the interface");
731 if (is_miranda(m, ik()->methods(), ik()->default_methods(), ik()->super(), klass()->is_interface())) {
732 return true;
733 }
734 }
735 return false;
736 }
737
738 // Check if a method is a miranda method, given a class's methods array,
739 // its default_method table and its super class.
740 // "Miranda" means an abstract non-private method that would not be
741 // overridden for the local class.
742 // A "miranda" method should only include non-private interface
743 // instance methods, i.e. not private methods, not static methods,
744 // not default methods (concrete interface methods), not overpass methods.
745 // If a given class already has a local (including overpass) method, a
746 // default method, or any of its superclasses has the same which would have
747 // overridden an abstract method, then this is not a miranda method.
748 //
749 // Miranda methods are checked multiple times.
750 // Pass 1: during class load/class file parsing: before vtable size calculation:
751 // include superinterface abstract and default methods (non-private instance).
752 // We include potential default methods to give them space in the vtable.
753 // During the first run, the current instanceKlass has not yet been
754 // created, the superclasses and superinterfaces do have instanceKlasses
755 // but may not have vtables, the default_methods list is empty, no overpasses.
756 // Default method generation uses the all_mirandas array as the starter set for
757 // maximally-specific default method calculation. So, for both classes and
758 // interfaces, it is necessary that the first pass will find all non-private
759 // interface instance methods, whether or not they are concrete.
760 //
761 // Pass 2: recalculated during vtable initialization: only include abstract methods.
762 // The goal of pass 2 is to walk through the superinterfaces to see if any of
763 // the superinterface methods (which were all abstract pre-default methods)
764 // need to be added to the vtable.
765 // With the addition of default methods, we have three new challenges:
766 // overpasses, static interface methods and private interface methods.
767 // Static and private interface methods do not get added to the vtable and
768 // are not seen by the method resolution process, so we skip those.
769 // Overpass methods are already in the vtable, so vtable lookup will
770 // find them and we don't need to add a miranda method to the end of
771 // the vtable. So we look for overpass methods and if they are found we
772 // return false. Note that we inherit our superclasses vtable, so
773 // the superclass' search also needs to use find_overpass so that if
774 // one is found we return false.
775 // False means - we don't need a miranda method added to the vtable.
776 //
777 // During the second run, default_methods is set up, so concrete methods from
778 // superinterfaces with matching names/signatures to default_methods are already
779 // in the default_methods list and do not need to be appended to the vtable
780 // as mirandas. Abstract methods may already have been handled via
781 // overpasses - either local or superclass overpasses, which may be
782 // in the vtable already.
783 //
784 // Pass 3: They are also checked by link resolution and selection,
785 // for invocation on a method (not interface method) reference that
786 // resolves to a method with an interface as its method_holder.
787 // Used as part of walking from the bottom of the vtable to find
788 // the vtable index for the miranda method.
789 //
790 // Part of the Miranda Rights in the US mean that if you do not have
791 // an attorney one will be appointed for you.
792 bool klassVtable::is_miranda(Method* m, Array<Method*>* class_methods,
793 Array<Method*>* default_methods, const Klass* super,
794 bool is_interface) {
795 if (m->is_static() || m->is_private() || m->is_overpass()) {
796 return false;
797 }
798 Symbol* name = m->name();
799 Symbol* signature = m->signature();
800
801 // First look in local methods to see if already covered
802 if (InstanceKlass::find_local_method(class_methods, name, signature,
803 Klass::find_overpass, Klass::skip_static, Klass::skip_private) != NULL)
804 {
805 return false;
806 }
807
808 // Check local default methods
809 if ((default_methods != NULL) &&
810 (InstanceKlass::find_method(default_methods, name, signature) != NULL))
811 {
812 return false;
813 }
814
815 // Iterate on all superclasses, which should be InstanceKlasses.
816 // Note that we explicitly look for overpasses at each level.
817 // Overpasses may or may not exist for supers for pass 1,
818 // they should have been created for pass 2 and later.
819
820 for (const Klass* cursuper = super; cursuper != NULL; cursuper = cursuper->super())
821 {
822 Method* found_mth = InstanceKlass::cast(cursuper)->find_local_method(name, signature,
823 Klass::find_overpass, Klass::skip_static, Klass::skip_private);
824 // Ignore non-public methods in java.lang.Object if klass is an interface.
825 if (found_mth != NULL && (!is_interface ||
826 !SystemDictionary::is_nonpublic_Object_method(found_mth))) {
827 return false;
828 }
829 }
830
831 return true;
832 }
833
834 // Scans current_interface_methods for miranda methods that do not
835 // already appear in new_mirandas, or default methods, and are also not defined-and-non-private
836 // in super (superclass). These mirandas are added to all_mirandas if it is
837 // not null; in addition, those that are not duplicates of miranda methods
838 // inherited by super from its interfaces are added to new_mirandas.
839 // Thus, new_mirandas will be the set of mirandas that this class introduces,
840 // all_mirandas will be the set of all mirandas applicable to this class
841 // including all defined in superclasses.
842 void klassVtable::add_new_mirandas_to_lists(
843 GrowableArray<Method*>* new_mirandas, GrowableArray<Method*>* all_mirandas,
844 Array<Method*>* current_interface_methods, Array<Method*>* class_methods,
845 Array<Method*>* default_methods, const Klass* super, bool is_interface) {
846
847 // iterate thru the current interface's method to see if it a miranda
848 int num_methods = current_interface_methods->length();
849 for (int i = 0; i < num_methods; i++) {
850 Method* im = current_interface_methods->at(i);
851 bool is_duplicate = false;
852 int num_of_current_mirandas = new_mirandas->length();
853 // check for duplicate mirandas in different interfaces we implement
854 for (int j = 0; j < num_of_current_mirandas; j++) {
855 Method* miranda = new_mirandas->at(j);
856 if ((im->name() == miranda->name()) &&
857 (im->signature() == miranda->signature())) {
858 is_duplicate = true;
859 break;
860 }
861 }
862
863 if (!is_duplicate) { // we don't want duplicate miranda entries in the vtable
864 if (is_miranda(im, class_methods, default_methods, super, is_interface)) { // is it a miranda at all?
865 const InstanceKlass *sk = InstanceKlass::cast(super);
866 // check if it is a duplicate of a super's miranda
867 if (sk->lookup_method_in_all_interfaces(im->name(), im->signature(), Klass::find_defaults) == NULL) {
868 new_mirandas->append(im);
869 }
870 if (all_mirandas != NULL) {
871 all_mirandas->append(im);
872 }
873 }
874 }
875 }
876 }
877
878 void klassVtable::get_mirandas(GrowableArray<Method*>* new_mirandas,
879 GrowableArray<Method*>* all_mirandas,
880 const Klass* super,
881 Array<Method*>* class_methods,
882 Array<Method*>* default_methods,
883 Array<InstanceKlass*>* local_interfaces,
884 bool is_interface) {
885 assert((new_mirandas->length() == 0) , "current mirandas must be 0");
886
887 // iterate thru the local interfaces looking for a miranda
888 int num_local_ifs = local_interfaces->length();
889 for (int i = 0; i < num_local_ifs; i++) {
890 InstanceKlass *ik = InstanceKlass::cast(local_interfaces->at(i));
891 add_new_mirandas_to_lists(new_mirandas, all_mirandas,
892 ik->methods(), class_methods,
893 default_methods, super, is_interface);
894 // iterate thru each local's super interfaces
895 Array<InstanceKlass*>* super_ifs = ik->transitive_interfaces();
896 int num_super_ifs = super_ifs->length();
897 for (int j = 0; j < num_super_ifs; j++) {
898 InstanceKlass *sik = super_ifs->at(j);
899 add_new_mirandas_to_lists(new_mirandas, all_mirandas,
900 sik->methods(), class_methods,
901 default_methods, super, is_interface);
902 }
903 }
904 }
905
906 // Discover miranda methods ("miranda" = "interface abstract, no binding"),
907 // and append them into the vtable starting at index initialized,
908 // return the new value of initialized.
909 // Miranda methods use vtable entries, but do not get assigned a vtable_index
910 // The vtable_index is discovered by searching from the end of the vtable
911 int klassVtable::fill_in_mirandas(int initialized, TRAPS) {
912 ResourceMark rm(THREAD);
913 GrowableArray<Method*> mirandas(20);
914 get_mirandas(&mirandas, NULL, ik()->super(), ik()->methods(),
915 ik()->default_methods(), ik()->local_interfaces(),
916 klass()->is_interface());
917 for (int i = 0; i < mirandas.length(); i++) {
918 if (log_develop_is_enabled(Trace, vtables)) {
919 Method* meth = mirandas.at(i);
920 LogTarget(Trace, vtables) lt;
921 LogStream ls(lt);
922 if (meth != NULL) {
923 char* sig = meth->name_and_sig_as_C_string();
924 ls.print("fill in mirandas with %s index %d, flags: ",
925 sig, initialized);
926 meth->print_linkage_flags(&ls);
927 ls.cr();
928 }
929 }
930 put_method_at(mirandas.at(i), initialized);
931 ++initialized;
932 }
933 return initialized;
934 }
935
936 // Copy this class's vtable to the vtable beginning at start.
937 // Used to copy superclass vtable to prefix of subclass's vtable.
938 void klassVtable::copy_vtable_to(vtableEntry* start) {
939 Copy::disjoint_words((HeapWord*)table(), (HeapWord*)start, _length * vtableEntry::size());
940 }
941
942 #if INCLUDE_JVMTI
943 bool klassVtable::adjust_default_method(int vtable_index, Method* old_method, Method* new_method) {
944 // If old_method is default, find this vtable index in default_vtable_indices
945 // and replace that method in the _default_methods list
946 bool updated = false;
947
948 Array<Method*>* default_methods = ik()->default_methods();
949 if (default_methods != NULL) {
950 int len = default_methods->length();
951 for (int idx = 0; idx < len; idx++) {
952 if (vtable_index == ik()->default_vtable_indices()->at(idx)) {
953 if (default_methods->at(idx) == old_method) {
954 default_methods->at_put(idx, new_method);
955 updated = true;
956 }
957 break;
958 }
959 }
960 }
961 return updated;
962 }
963
964 // search the vtable for uses of either obsolete or EMCP methods
965 void klassVtable::adjust_method_entries(bool * trace_name_printed) {
966 int prn_enabled = 0;
967 for (int index = 0; index < length(); index++) {
968 Method* old_method = unchecked_method_at(index);
969 if (old_method == NULL || !old_method->is_old()) {
970 continue; // skip uninteresting entries
971 }
972 assert(!old_method->is_deleted(), "vtable methods may not be deleted");
973
974 Method* new_method = old_method->get_new_method();
975 put_method_at(new_method, index);
976
977 // For default methods, need to update the _default_methods array
978 // which can only have one method entry for a given signature
979 bool updated_default = false;
980 if (old_method->is_default_method()) {
981 updated_default = adjust_default_method(index, old_method, new_method);
982 }
983
984 if (log_is_enabled(Info, redefine, class, update)) {
985 ResourceMark rm;
986 if (!(*trace_name_printed)) {
987 log_info(redefine, class, update)
988 ("adjust: klassname=%s for methods from name=%s",
989 _klass->external_name(), old_method->method_holder()->external_name());
990 *trace_name_printed = true;
991 }
992 log_debug(redefine, class, update, vtables)
993 ("vtable method update: %s(%s), updated default = %s",
994 new_method->name()->as_C_string(), new_method->signature()->as_C_string(), updated_default ? "true" : "false");
995 }
996 }
997 }
998
999 // a vtable should never contain old or obsolete methods
1000 bool klassVtable::check_no_old_or_obsolete_entries() {
1001 for (int i = 0; i < length(); i++) {
1002 Method* m = unchecked_method_at(i);
1003 if (m != NULL &&
1004 (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) {
1005 return false;
1006 }
1007 }
1008 return true;
1009 }
1010
1011 void klassVtable::dump_vtable() {
1012 tty->print_cr("vtable dump --");
1013 for (int i = 0; i < length(); i++) {
1014 Method* m = unchecked_method_at(i);
1015 if (m != NULL) {
1016 tty->print(" (%5d) ", i);
1017 m->access_flags().print_on(tty);
1018 if (m->is_default_method()) {
1019 tty->print("default ");
1020 }
1021 if (m->is_overpass()) {
1022 tty->print("overpass");
1023 }
1024 tty->print(" -- ");
1025 m->print_name(tty);
1026 tty->cr();
1027 }
1028 }
1029 }
1030 #endif // INCLUDE_JVMTI
1031
1032 // CDS/RedefineClasses support - clear vtables so they can be reinitialized
1033 void klassVtable::clear_vtable() {
1034 for (int i = 0; i < _length; i++) table()[i].clear();
1035 }
1036
1037 bool klassVtable::is_initialized() {
1038 return _length == 0 || table()[0].method() != NULL;
1039 }
1040
1041 //-----------------------------------------------------------------------------------------
1042 // Itable code
1043
1044 // Initialize a itableMethodEntry
1045 void itableMethodEntry::initialize(Method* m) {
1046 if (m == NULL) return;
1047
1048 #ifdef ASSERT
1049 if (MetaspaceShared::is_in_shared_metaspace((void*)&_method) &&
1050 !MetaspaceShared::remapped_readwrite()) {
1051 // At runtime initialize_itable is rerun as part of link_class_impl()
1052 // for a shared class loaded by the non-boot loader.
1053 // The dumptime itable method entry should be the same as the runtime entry.
1054 assert(_method == m, "sanity");
1055 }
1056 #endif
1057 _method = m;
1058 }
1059
1060 klassItable::klassItable(InstanceKlass* klass) {
1061 _klass = klass;
1062
1063 if (klass->itable_length() > 0) {
1064 itableOffsetEntry* offset_entry = (itableOffsetEntry*)klass->start_of_itable();
1065 if (offset_entry != NULL && offset_entry->interface_klass() != NULL) { // Check that itable is initialized
1066 // First offset entry points to the first method_entry
1067 intptr_t* method_entry = (intptr_t *)(((address)klass) + offset_entry->offset());
1068 intptr_t* end = klass->end_of_itable();
1069
1070 _table_offset = (intptr_t*)offset_entry - (intptr_t*)klass;
1071 _size_offset_table = (method_entry - ((intptr_t*)offset_entry)) / itableOffsetEntry::size();
1072 _size_method_table = (end - method_entry) / itableMethodEntry::size();
1073 assert(_table_offset >= 0 && _size_offset_table >= 0 && _size_method_table >= 0, "wrong computation");
1074 return;
1075 }
1076 }
1077
1078 // The length of the itable was either zero, or it has not yet been initialized.
1079 _table_offset = 0;
1080 _size_offset_table = 0;
1081 _size_method_table = 0;
1082 }
1083
1084 static int initialize_count = 0;
1085
1086 // Initialization
1087 void klassItable::initialize_itable(bool checkconstraints, TRAPS) {
1088 if (_klass->is_interface()) {
1089 // This needs to go after vtable indices are assigned but
1090 // before implementors need to know the number of itable indices.
1091 assign_itable_indices_for_interface(InstanceKlass::cast(_klass), THREAD);
1092 }
1093
1094 // Cannot be setup doing bootstrapping, interfaces don't have
1095 // itables, and klass with only ones entry have empty itables
1096 if (Universe::is_bootstrapping() ||
1097 _klass->is_interface() ||
1098 _klass->itable_length() == itableOffsetEntry::size()) return;
1099
1100 // There's alway an extra itable entry so we can null-terminate it.
1101 guarantee(size_offset_table() >= 1, "too small");
1102 int num_interfaces = size_offset_table() - 1;
1103 if (num_interfaces > 0) {
1104 ResourceMark rm(THREAD);
1105 log_develop_debug(itables)("%3d: Initializing itables for %s", ++initialize_count,
1106 _klass->name()->as_C_string());
1107
1108
1109 // Iterate through all interfaces
1110 int i;
1111 for(i = 0; i < num_interfaces; i++) {
1112 itableOffsetEntry* ioe = offset_entry(i);
1113 HandleMark hm(THREAD);
1114 Klass* interf = ioe->interface_klass();
1115 assert(interf != NULL && ioe->offset() != 0, "bad offset entry in itable");
1116 initialize_itable_for_interface(ioe->offset(), InstanceKlass::cast(interf), checkconstraints, CHECK);
1117 }
1118
1119 }
1120 // Check that the last entry is empty
1121 itableOffsetEntry* ioe = offset_entry(size_offset_table() - 1);
1122 guarantee(ioe->interface_klass() == NULL && ioe->offset() == 0, "terminator entry missing");
1123 }
1124
1125
1126 inline bool interface_method_needs_itable_index(Method* m) {
1127 if (m->is_static()) return false; // e.g., Stream.empty
1128 if (m->is_initializer()) return false; // <init> or <clinit>
1129 if (m->is_private()) return false; // uses direct call
1130 // If an interface redeclares a method from java.lang.Object,
1131 // it should already have a vtable index, don't touch it.
1132 // e.g., CharSequence.toString (from initialize_vtable)
1133 // if (m->has_vtable_index()) return false; // NO!
1134 return true;
1135 }
1136
1137 int klassItable::assign_itable_indices_for_interface(InstanceKlass* klass, TRAPS) {
1138 // an interface does not have an itable, but its methods need to be numbered
1139 ResourceMark rm(THREAD);
1140 log_develop_debug(itables)("%3d: Initializing itable indices for interface %s",
1141 ++initialize_count, klass->name()->as_C_string());
1142 Array<Method*>* methods = klass->methods();
1143 int nof_methods = methods->length();
1144 int ime_num = 0;
1145 for (int i = 0; i < nof_methods; i++) {
1146 Method* m = methods->at(i);
1147 if (interface_method_needs_itable_index(m)) {
1148 assert(!m->is_final_method(), "no final interface methods");
1149 // If m is already assigned a vtable index, do not disturb it.
1150 if (log_develop_is_enabled(Trace, itables)) {
1151 LogTarget(Trace, itables) lt;
1152 LogStream ls(lt);
1153 assert(m != NULL, "methods can never be null");
1154 const char* sig = m->name_and_sig_as_C_string();
1155 if (m->has_vtable_index()) {
1156 ls.print("vtable index %d for method: %s, flags: ", m->vtable_index(), sig);
1157 } else {
1158 ls.print("itable index %d for method: %s, flags: ", ime_num, sig);
1159 }
1160 m->print_linkage_flags(&ls);
1161 ls.cr();
1162 }
1163 if (!m->has_vtable_index()) {
1164 // A shared method could have an initialized itable_index that
1165 // is < 0.
1166 assert(m->vtable_index() == Method::pending_itable_index ||
1167 m->is_shared(),
1168 "set by initialize_vtable");
1169 m->set_itable_index(ime_num);
1170 // Progress to next itable entry
1171 ime_num++;
1172 }
1173 }
1174 }
1175 assert(ime_num == method_count_for_interface(klass), "proper sizing");
1176 return ime_num;
1177 }
1178
1179 int klassItable::method_count_for_interface(InstanceKlass* interf) {
1180 assert(interf->is_interface(), "must be");
1181 Array<Method*>* methods = interf->methods();
1182 int nof_methods = methods->length();
1183 int length = 0;
1184 while (nof_methods > 0) {
1185 Method* m = methods->at(nof_methods-1);
1186 if (m->has_itable_index()) {
1187 length = m->itable_index() + 1;
1188 break;
1189 }
1190 nof_methods -= 1;
1191 }
1192 #ifdef ASSERT
1193 int nof_methods_copy = nof_methods;
1194 while (nof_methods_copy > 0) {
1195 Method* mm = methods->at(--nof_methods_copy);
1196 assert(!mm->has_itable_index() || mm->itable_index() < length, "");
1197 }
1198 #endif //ASSERT
1199 // return the rightmost itable index, plus one; or 0 if no methods have
1200 // itable indices
1201 return length;
1202 }
1203
1204
1205 void klassItable::initialize_itable_for_interface(int method_table_offset, InstanceKlass* interf, bool checkconstraints, TRAPS) {
1206 assert(interf->is_interface(), "must be");
1207 Array<Method*>* methods = interf->methods();
1208 int nof_methods = methods->length();
1209 HandleMark hm;
1210 Handle interface_loader (THREAD, interf->class_loader());
1211
1212 int ime_count = method_count_for_interface(interf);
1213 for (int i = 0; i < nof_methods; i++) {
1214 Method* m = methods->at(i);
1215 methodHandle target;
1216 if (m->has_itable_index()) {
1217 // This search must match the runtime resolution, i.e. selection search for invokeinterface
1218 // to correctly enforce loader constraints for interface method inheritance.
1219 // Private methods are skipped as a private class method can never be the implementation
1220 // of an interface method.
1221 // Invokespecial does not perform selection based on the receiver, so it does not use
1222 // the cached itable.
1223 target = LinkResolver::lookup_instance_method_in_klasses(_klass, m->name(), m->signature(),
1224 Klass::skip_private, CHECK);
1225 }
1226 if (target == NULL || !target->is_public() || target->is_abstract() || target->is_overpass()) {
1227 assert(target == NULL || !target->is_overpass() || target->is_public(),
1228 "Non-public overpass method!");
1229 // Entry does not resolve. Leave it empty for AbstractMethodError or other error.
1230 if (!(target == NULL) && !target->is_public()) {
1231 // Stuff an IllegalAccessError throwing method in there instead.
1232 itableOffsetEntry::method_entry(_klass, method_table_offset)[m->itable_index()].
1233 initialize(Universe::throw_illegal_access_error());
1234 }
1235 } else {
1236 // Entry did resolve, check loader constraints before initializing
1237 // if checkconstraints requested
1238 if (checkconstraints) {
1239 Handle method_holder_loader (THREAD, target->method_holder()->class_loader());
1240 if (!oopDesc::equals(method_holder_loader(), interface_loader())) {
1241 ResourceMark rm(THREAD);
1242 Symbol* failed_type_symbol =
1243 SystemDictionary::check_signature_loaders(m->signature(),
1244 method_holder_loader,
1245 interface_loader,
1246 true, CHECK);
1247 if (failed_type_symbol != NULL) {
1248 stringStream ss;
1249 ss.print("loader constraint violation in interface itable"
1250 " initialization for class %s: when selecting method '",
1251 _klass->external_name());
1252 m->print_external_name(&ss),
1253 ss.print("' the class loader %s for super interface %s, and the class"
1254 " loader %s of the selected method's %s, %s have"
1255 " different Class objects for the type %s used in the signature (%s; %s)",
1256 interf->class_loader_data()->loader_name_and_id(),
1257 interf->external_name(),
1258 target()->method_holder()->class_loader_data()->loader_name_and_id(),
1259 target()->method_holder()->external_kind(),
1260 target()->method_holder()->external_name(),
1261 failed_type_symbol->as_klass_external_name(),
1262 interf->class_in_module_of_loader(false, true),
1263 target()->method_holder()->class_in_module_of_loader(false, true));
1264 THROW_MSG(vmSymbols::java_lang_LinkageError(), ss.as_string());
1265 }
1266 }
1267 }
1268
1269 // ime may have moved during GC so recalculate address
1270 int ime_num = m->itable_index();
1271 assert(ime_num < ime_count, "oob");
1272 itableOffsetEntry::method_entry(_klass, method_table_offset)[ime_num].initialize(target());
1273 if (log_develop_is_enabled(Trace, itables)) {
1274 ResourceMark rm(THREAD);
1275 if (target() != NULL) {
1276 LogTarget(Trace, itables) lt;
1277 LogStream ls(lt);
1278 char* sig = target()->name_and_sig_as_C_string();
1279 ls.print("interface: %s, ime_num: %d, target: %s, method_holder: %s ",
1280 interf->internal_name(), ime_num, sig,
1281 target()->method_holder()->internal_name());
1282 ls.print("target_method flags: ");
1283 target()->print_linkage_flags(&ls);
1284 ls.cr();
1285 }
1286 }
1287 }
1288 }
1289 }
1290
1291 #if INCLUDE_JVMTI
1292 // search the itable for uses of either obsolete or EMCP methods
1293 void klassItable::adjust_method_entries(bool * trace_name_printed) {
1294
1295 itableMethodEntry* ime = method_entry(0);
1296 for (int i = 0; i < _size_method_table; i++, ime++) {
1297 Method* old_method = ime->method();
1298 if (old_method == NULL || !old_method->is_old()) {
1299 continue; // skip uninteresting entries
1300 }
1301 assert(!old_method->is_deleted(), "itable methods may not be deleted");
1302 Method* new_method = old_method->get_new_method();
1303 ime->initialize(new_method);
1304
1305 if (log_is_enabled(Info, redefine, class, update)) {
1306 ResourceMark rm;
1307 if (!(*trace_name_printed)) {
1308 log_info(redefine, class, update)("adjust: name=%s", old_method->method_holder()->external_name());
1309 *trace_name_printed = true;
1310 }
1311 log_trace(redefine, class, update, itables)
1312 ("itable method update: %s(%s)", new_method->name()->as_C_string(), new_method->signature()->as_C_string());
1313 }
1314 }
1315 }
1316
1317 // an itable should never contain old or obsolete methods
1318 bool klassItable::check_no_old_or_obsolete_entries() {
1319 itableMethodEntry* ime = method_entry(0);
1320 for (int i = 0; i < _size_method_table; i++) {
1321 Method* m = ime->method();
1322 if (m != NULL &&
1323 (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) {
1324 return false;
1325 }
1326 ime++;
1327 }
1328 return true;
1329 }
1330
1331 void klassItable::dump_itable() {
1332 itableMethodEntry* ime = method_entry(0);
1333 tty->print_cr("itable dump --");
1334 for (int i = 0; i < _size_method_table; i++) {
1335 Method* m = ime->method();
1336 if (m != NULL) {
1337 tty->print(" (%5d) ", i);
1338 m->access_flags().print_on(tty);
1339 if (m->is_default_method()) {
1340 tty->print("default ");
1341 }
1342 tty->print(" -- ");
1343 m->print_name(tty);
1344 tty->cr();
1345 }
1346 ime++;
1347 }
1348 }
1349 #endif // INCLUDE_JVMTI
1350
1351 // Setup
1352 class InterfaceVisiterClosure : public StackObj {
1353 public:
1354 virtual void doit(InstanceKlass* intf, int method_count) = 0;
1355 };
1356
1357 // Visit all interfaces with at least one itable method
1358 void visit_all_interfaces(Array<InstanceKlass*>* transitive_intf, InterfaceVisiterClosure *blk) {
1359 // Handle array argument
1360 for(int i = 0; i < transitive_intf->length(); i++) {
1361 InstanceKlass* intf = transitive_intf->at(i);
1362 assert(intf->is_interface(), "sanity check");
1363
1364 // Find no. of itable methods
1365 int method_count = 0;
1366 // method_count = klassItable::method_count_for_interface(intf);
1367 Array<Method*>* methods = intf->methods();
1368 if (methods->length() > 0) {
1369 for (int i = methods->length(); --i >= 0; ) {
1370 if (interface_method_needs_itable_index(methods->at(i))) {
1371 method_count++;
1372 }
1373 }
1374 }
1375
1376 // Visit all interfaces which either have any methods or can participate in receiver type check.
1377 // We do not bother to count methods in transitive interfaces, although that would allow us to skip
1378 // this step in the rare case of a zero-method interface extending another zero-method interface.
1379 if (method_count > 0 || intf->transitive_interfaces()->length() > 0) {
1380 blk->doit(intf, method_count);
1381 }
1382 }
1383 }
1384
1385 class CountInterfacesClosure : public InterfaceVisiterClosure {
1386 private:
1387 int _nof_methods;
1388 int _nof_interfaces;
1389 public:
1390 CountInterfacesClosure() { _nof_methods = 0; _nof_interfaces = 0; }
1391
1392 int nof_methods() const { return _nof_methods; }
1393 int nof_interfaces() const { return _nof_interfaces; }
1394
1395 void doit(InstanceKlass* intf, int method_count) { _nof_methods += method_count; _nof_interfaces++; }
1396 };
1397
1398 class SetupItableClosure : public InterfaceVisiterClosure {
1399 private:
1400 itableOffsetEntry* _offset_entry;
1401 itableMethodEntry* _method_entry;
1402 address _klass_begin;
1403 public:
1404 SetupItableClosure(address klass_begin, itableOffsetEntry* offset_entry, itableMethodEntry* method_entry) {
1405 _klass_begin = klass_begin;
1406 _offset_entry = offset_entry;
1407 _method_entry = method_entry;
1408 }
1409
1410 itableMethodEntry* method_entry() const { return _method_entry; }
1411
1412 void doit(InstanceKlass* intf, int method_count) {
1413 int offset = ((address)_method_entry) - _klass_begin;
1414 _offset_entry->initialize(intf, offset);
1415 _offset_entry++;
1416 _method_entry += method_count;
1417 }
1418 };
1419
1420 int klassItable::compute_itable_size(Array<InstanceKlass*>* transitive_interfaces) {
1421 // Count no of interfaces and total number of interface methods
1422 CountInterfacesClosure cic;
1423 visit_all_interfaces(transitive_interfaces, &cic);
1424
1425 // There's alway an extra itable entry so we can null-terminate it.
1426 int itable_size = calc_itable_size(cic.nof_interfaces() + 1, cic.nof_methods());
1427
1428 // Statistics
1429 update_stats(itable_size * wordSize);
1430
1431 return itable_size;
1432 }
1433
1434
1435 // Fill out offset table and interface klasses into the itable space
1436 void klassItable::setup_itable_offset_table(InstanceKlass* klass) {
1437 if (klass->itable_length() == 0) return;
1438 assert(!klass->is_interface(), "Should have zero length itable");
1439
1440 // Count no of interfaces and total number of interface methods
1441 CountInterfacesClosure cic;
1442 visit_all_interfaces(klass->transitive_interfaces(), &cic);
1443 int nof_methods = cic.nof_methods();
1444 int nof_interfaces = cic.nof_interfaces();
1445
1446 // Add one extra entry so we can null-terminate the table
1447 nof_interfaces++;
1448
1449 assert(compute_itable_size(klass->transitive_interfaces()) ==
1450 calc_itable_size(nof_interfaces, nof_methods),
1451 "mismatch calculation of itable size");
1452
1453 // Fill-out offset table
1454 itableOffsetEntry* ioe = (itableOffsetEntry*)klass->start_of_itable();
1455 itableMethodEntry* ime = (itableMethodEntry*)(ioe + nof_interfaces);
1456 intptr_t* end = klass->end_of_itable();
1457 assert((oop*)(ime + nof_methods) <= (oop*)klass->start_of_nonstatic_oop_maps(), "wrong offset calculation (1)");
1458 assert((oop*)(end) == (oop*)(ime + nof_methods), "wrong offset calculation (2)");
1459
1460 // Visit all interfaces and initialize itable offset table
1461 SetupItableClosure sic((address)klass, ioe, ime);
1462 visit_all_interfaces(klass->transitive_interfaces(), &sic);
1463
1464 #ifdef ASSERT
1465 ime = sic.method_entry();
1466 oop* v = (oop*) klass->end_of_itable();
1467 assert( (oop*)(ime) == v, "wrong offset calculation (2)");
1468 #endif
1469 }
1470
1471
1472 // inverse to itable_index
1473 Method* klassItable::method_for_itable_index(InstanceKlass* intf, int itable_index) {
1474 assert(intf->is_interface(), "sanity check");
1475 assert(intf->verify_itable_index(itable_index), "");
1476 Array<Method*>* methods = InstanceKlass::cast(intf)->methods();
1477
1478 if (itable_index < 0 || itable_index >= method_count_for_interface(intf))
1479 return NULL; // help caller defend against bad indices
1480
1481 int index = itable_index;
1482 Method* m = methods->at(index);
1483 int index2 = -1;
1484 while (!m->has_itable_index() ||
1485 (index2 = m->itable_index()) != itable_index) {
1486 assert(index2 < itable_index, "monotonic");
1487 if (++index == methods->length())
1488 return NULL;
1489 m = methods->at(index);
1490 }
1491 assert(m->itable_index() == itable_index, "correct inverse");
1492
1493 return m;
1494 }
1495
1496 void klassVtable::verify(outputStream* st, bool forced) {
1497 // make sure table is initialized
1498 if (!Universe::is_fully_initialized()) return;
1499 #ifndef PRODUCT
1500 // avoid redundant verifies
1501 if (!forced && _verify_count == Universe::verify_count()) return;
1502 _verify_count = Universe::verify_count();
1503 #endif
1504 oop* end_of_obj = (oop*)_klass + _klass->size();
1505 oop* end_of_vtable = (oop *)&table()[_length];
1506 if (end_of_vtable > end_of_obj) {
1507 ResourceMark rm;
1508 fatal("klass %s: klass object too short (vtable extends beyond end)",
1509 _klass->internal_name());
1510 }
1511
1512 for (int i = 0; i < _length; i++) table()[i].verify(this, st);
1513 // verify consistency with superKlass vtable
1514 Klass* super = _klass->super();
1515 if (super != NULL) {
1516 InstanceKlass* sk = InstanceKlass::cast(super);
1517 klassVtable vt = sk->vtable();
1518 for (int i = 0; i < vt.length(); i++) {
1519 verify_against(st, &vt, i);
1520 }
1521 }
1522 }
1523
1524 void klassVtable::verify_against(outputStream* st, klassVtable* vt, int index) {
1525 vtableEntry* vte = &vt->table()[index];
1526 if (vte->method()->name() != table()[index].method()->name() ||
1527 vte->method()->signature() != table()[index].method()->signature()) {
1528 fatal("mismatched name/signature of vtable entries");
1529 }
1530 }
1531
1532 #ifndef PRODUCT
1533 void klassVtable::print() {
1534 ResourceMark rm;
1535 tty->print("klassVtable for klass %s (length %d):\n", _klass->internal_name(), length());
1536 for (int i = 0; i < length(); i++) {
1537 table()[i].print();
1538 tty->cr();
1539 }
1540 }
1541 #endif
1542
1543 void vtableEntry::verify(klassVtable* vt, outputStream* st) {
1544 NOT_PRODUCT(FlagSetting fs(IgnoreLockingAssertions, true));
1545 Klass* vtklass = vt->klass();
1546 if (vtklass->is_instance_klass() &&
1547 (InstanceKlass::cast(vtklass)->major_version() >= klassVtable::VTABLE_TRANSITIVE_OVERRIDE_VERSION)) {
1548 assert(method() != NULL, "must have set method");
1549 }
1550 if (method() != NULL) {
1551 method()->verify();
1552 // we sub_type, because it could be a miranda method
1553 if (!vtklass->is_subtype_of(method()->method_holder())) {
1554 #ifndef PRODUCT
1555 print();
1556 #endif
1557 fatal("vtableEntry " PTR_FORMAT ": method is from subclass", p2i(this));
1558 }
1559 }
1560 }
1561
1562 #ifndef PRODUCT
1563
1564 void vtableEntry::print() {
1565 ResourceMark rm;
1566 tty->print("vtableEntry %s: ", method()->name()->as_C_string());
1567 if (Verbose) {
1568 tty->print("m " PTR_FORMAT " ", p2i(method()));
1569 }
1570 }
1571
1572 class VtableStats : AllStatic {
1573 public:
1574 static int no_klasses; // # classes with vtables
1575 static int no_array_klasses; // # array classes
1576 static int no_instance_klasses; // # instanceKlasses
1577 static int sum_of_vtable_len; // total # of vtable entries
1578 static int sum_of_array_vtable_len; // total # of vtable entries in array klasses only
1579 static int fixed; // total fixed overhead in bytes
1580 static int filler; // overhead caused by filler bytes
1581 static int entries; // total bytes consumed by vtable entries
1582 static int array_entries; // total bytes consumed by array vtable entries
1583
1584 static void do_class(Klass* k) {
1585 Klass* kl = k;
1586 klassVtable vt = kl->vtable();
1587 no_klasses++;
1588 if (kl->is_instance_klass()) {
1589 no_instance_klasses++;
1590 kl->array_klasses_do(do_class);
1591 }
1592 if (kl->is_array_klass()) {
1593 no_array_klasses++;
1594 sum_of_array_vtable_len += vt.length();
1595 }
1596 sum_of_vtable_len += vt.length();
1597 }
1598
1599 static void compute() {
1600 LockedClassesDo locked_do_class(&do_class);
1601 ClassLoaderDataGraph::classes_do(&locked_do_class);
1602 fixed = no_klasses * oopSize; // vtable length
1603 // filler size is a conservative approximation
1604 filler = oopSize * (no_klasses - no_instance_klasses) * (sizeof(InstanceKlass) - sizeof(ArrayKlass) - 1);
1605 entries = sizeof(vtableEntry) * sum_of_vtable_len;
1606 array_entries = sizeof(vtableEntry) * sum_of_array_vtable_len;
1607 }
1608 };
1609
1610 int VtableStats::no_klasses = 0;
1611 int VtableStats::no_array_klasses = 0;
1612 int VtableStats::no_instance_klasses = 0;
1613 int VtableStats::sum_of_vtable_len = 0;
1614 int VtableStats::sum_of_array_vtable_len = 0;
1615 int VtableStats::fixed = 0;
1616 int VtableStats::filler = 0;
1617 int VtableStats::entries = 0;
1618 int VtableStats::array_entries = 0;
1619
1620 void klassVtable::print_statistics() {
1621 ResourceMark rm;
1622 HandleMark hm;
1623 VtableStats::compute();
1624 tty->print_cr("vtable statistics:");
1625 tty->print_cr("%6d classes (%d instance, %d array)", VtableStats::no_klasses, VtableStats::no_instance_klasses, VtableStats::no_array_klasses);
1626 int total = VtableStats::fixed + VtableStats::filler + VtableStats::entries;
1627 tty->print_cr("%6d bytes fixed overhead (refs + vtable object header)", VtableStats::fixed);
1628 tty->print_cr("%6d bytes filler overhead", VtableStats::filler);
1629 tty->print_cr("%6d bytes for vtable entries (%d for arrays)", VtableStats::entries, VtableStats::array_entries);
1630 tty->print_cr("%6d bytes total", total);
1631 }
1632
1633 int klassItable::_total_classes; // Total no. of classes with itables
1634 long klassItable::_total_size; // Total no. of bytes used for itables
1635
1636 void klassItable::print_statistics() {
1637 tty->print_cr("itable statistics:");
1638 tty->print_cr("%6d classes with itables", _total_classes);
1639 tty->print_cr("%6lu K uses for itables (average by class: %ld bytes)", _total_size / K, _total_size / _total_classes);
1640 }
1641
1642 #endif // PRODUCT