1 /*
2 * Copyright (c) 1997, 2020, 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 // Copy super class's vtable to the first part (prefix) of this class's vtable,
132 // and return the number of entries copied. Expects that 'super' is the Java
133 // super class (arrays can have "array" super classes that must be skipped).
134 int klassVtable::initialize_from_super(Klass* super) {
135 if (super == NULL) {
136 return 0;
137 } else if (is_preinitialized_vtable()) {
138 // A shared class' vtable is preinitialized at dump time. No need to copy
139 // methods from super class for shared class, as that was already done
140 // during archiving time. However, if Jvmti has redefined a class,
141 // copy super class's vtable in case the super class has changed.
142 return super->vtable().length();
143 } else {
144 // copy methods from superKlass
145 klassVtable superVtable = super->vtable();
146 assert(superVtable.length() <= _length, "vtable too short");
147 #ifdef ASSERT
148 superVtable.verify(tty, true);
149 #endif
150 superVtable.copy_vtable_to(table());
151 if (log_develop_is_enabled(Trace, vtables)) {
152 ResourceMark rm;
153 log_develop_trace(vtables)("copy vtable from %s to %s size %d",
154 super->internal_name(), klass()->internal_name(),
155 _length);
156 }
157 return superVtable.length();
158 }
159 }
160
161 //
162 // Revised lookup semantics introduced 1.3 (Kestrel beta)
163 void klassVtable::initialize_vtable(bool checkconstraints, TRAPS) {
164
165 // Note: Arrays can have intermediate array supers. Use java_super to skip them.
166 InstanceKlass* super = _klass->java_super();
167
168 bool is_shared = _klass->is_shared();
169
170 if (!_klass->is_array_klass()) {
171 ResourceMark rm(THREAD);
172 log_develop_debug(vtables)("Initializing: %s", _klass->name()->as_C_string());
173 }
174
175 #ifdef ASSERT
176 oop* end_of_obj = (oop*)_klass + _klass->size();
177 oop* end_of_vtable = (oop*)&table()[_length];
178 assert(end_of_vtable <= end_of_obj, "vtable extends beyond end");
179 #endif
180
181 if (Universe::is_bootstrapping()) {
182 assert(!is_shared, "sanity");
183 // just clear everything
184 for (int i = 0; i < _length; i++) table()[i].clear();
185 return;
186 }
187
188 int super_vtable_len = initialize_from_super(super);
189 if (_klass->is_array_klass()) {
190 assert(super_vtable_len == _length, "arrays shouldn't introduce new methods");
191 } else {
192 assert(_klass->is_instance_klass(), "must be InstanceKlass");
193
194 Array<Method*>* methods = ik()->methods();
195 int len = methods->length();
196 int initialized = super_vtable_len;
197
198 // Check each of this class's methods against super;
199 // if override, replace in copy of super vtable, otherwise append to end
200 for (int i = 0; i < len; i++) {
201 // update_inherited_vtable can stop for gc - ensure using handles
202 HandleMark hm(THREAD);
203 assert(methods->at(i)->is_method(), "must be a Method*");
204 methodHandle mh(THREAD, methods->at(i));
205
206 bool needs_new_entry = update_inherited_vtable(ik(), mh, super_vtable_len, -1, checkconstraints, CHECK);
207
208 if (needs_new_entry) {
209 put_method_at(mh(), initialized);
210 mh()->set_vtable_index(initialized); // set primary vtable index
211 initialized++;
212 }
213 }
214
215 // update vtable with default_methods
216 Array<Method*>* default_methods = ik()->default_methods();
217 if (default_methods != NULL) {
218 len = default_methods->length();
219 if (len > 0) {
220 Array<int>* def_vtable_indices = NULL;
221 if ((def_vtable_indices = ik()->default_vtable_indices()) == NULL) {
222 assert(!is_shared, "shared class def_vtable_indices does not exist");
223 def_vtable_indices = ik()->create_new_default_vtable_indices(len, CHECK);
224 } else {
225 assert(def_vtable_indices->length() == len, "reinit vtable len?");
226 }
227 for (int i = 0; i < len; i++) {
228 HandleMark hm(THREAD);
229 assert(default_methods->at(i)->is_method(), "must be a Method*");
230 methodHandle mh(THREAD, default_methods->at(i));
231 assert(!mh->is_private(), "private interface method in the default method list");
232 bool needs_new_entry = update_inherited_vtable(ik(), mh, super_vtable_len, i, checkconstraints, CHECK);
233
234 // needs new entry
235 if (needs_new_entry) {
236 put_method_at(mh(), initialized);
237 if (is_preinitialized_vtable()) {
238 // At runtime initialize_vtable is rerun for a shared class
239 // (loaded by the non-boot loader) as part of link_class_impl().
240 // The dumptime vtable index should be the same as the runtime index.
241 assert(def_vtable_indices->at(i) == initialized,
242 "dump time vtable index is different from runtime index");
243 } else {
244 def_vtable_indices->at_put(i, initialized); //set vtable index
245 }
246 initialized++;
247 }
248 }
249 }
250 }
251
252 // add miranda methods; it will also return the updated initialized
253 // Interfaces do not need interface methods in their vtables
254 // This includes miranda methods and during later processing, default methods
255 if (!ik()->is_interface()) {
256 initialized = fill_in_mirandas(initialized, THREAD);
257 }
258
259 // In class hierarchies where the accessibility is not increasing (i.e., going from private ->
260 // package_private -> public/protected), the vtable might actually be smaller than our initial
261 // calculation, for classfile versions for which we do not do transitive override
262 // calculations.
263 if (ik()->major_version() >= VTABLE_TRANSITIVE_OVERRIDE_VERSION) {
264 assert(initialized == _length, "vtable initialization failed");
265 } else {
266 assert(initialized <= _length, "vtable initialization failed");
267 for(;initialized < _length; initialized++) {
268 table()[initialized].clear();
269 }
270 }
271 NOT_PRODUCT(verify(tty, true));
272 }
273 }
274
275 // Called for cases where a method does not override its superclass' vtable entry
276 // For bytecodes not produced by javac together it is possible that a method does not override
277 // the superclass's method, but might indirectly override a super-super class's vtable entry
278 // If none found, return a null superk, else return the superk of the method this does override
279 // For public and protected methods: if they override a superclass, they will
280 // also be overridden themselves appropriately.
281 // Private methods do not override, and are not overridden and are not in the vtable.
282 // Package Private methods are trickier:
283 // e.g. P1.A, pub m
284 // P2.B extends A, package private m
285 // P1.C extends B, public m
286 // P1.C.m needs to override P1.A.m and can not override P2.B.m
287 // Therefore: all package private methods need their own vtable entries for
288 // them to be the root of an inheritance overriding decision
289 // Package private methods may also override other vtable entries
290 InstanceKlass* klassVtable::find_transitive_override(InstanceKlass* initialsuper, const methodHandle& target_method,
291 int vtable_index, Handle target_loader, Symbol* target_classname, Thread * THREAD) {
292 InstanceKlass* superk = initialsuper;
293 while (superk != NULL && superk->super() != NULL) {
294 klassVtable ssVtable = (superk->super())->vtable();
295 if (vtable_index < ssVtable.length()) {
296 Method* super_method = ssVtable.method_at(vtable_index);
297 // get the class holding the matching method
298 // make sure you use that class for is_override
299 InstanceKlass* supermethodholder = super_method->method_holder();
300 #ifndef PRODUCT
301 Symbol* name= target_method()->name();
302 Symbol* signature = target_method()->signature();
303 assert(super_method->name() == name && super_method->signature() == signature, "vtable entry name/sig mismatch");
304 #endif
305
306 if (supermethodholder->is_override(methodHandle(THREAD, super_method), target_loader, target_classname, THREAD)) {
307 if (log_develop_is_enabled(Trace, vtables)) {
308 ResourceMark rm(THREAD);
309 LogTarget(Trace, vtables) lt;
310 LogStream ls(lt);
311 char* sig = target_method()->name_and_sig_as_C_string();
312 ls.print("transitive overriding superclass %s with %s index %d, original flags: ",
313 supermethodholder->internal_name(),
314 sig, vtable_index);
315 super_method->print_linkage_flags(&ls);
316 ls.print("overriders flags: ");
317 target_method->print_linkage_flags(&ls);
318 ls.cr();
319 }
320
321 break; // return found superk
322 }
323 } else {
324 // super class has no vtable entry here, stop transitive search
325 superk = (InstanceKlass*)NULL;
326 break;
327 }
328 // if no override found yet, continue to search up
329 superk = superk->super() == NULL ? NULL : InstanceKlass::cast(superk->super());
330 }
331
332 return superk;
333 }
334
335 static void log_vtables(int i, bool overrides, const methodHandle& target_method,
336 Klass* target_klass, Method* super_method,
337 Thread* thread) {
338 #ifndef PRODUCT
339 if (log_develop_is_enabled(Trace, vtables)) {
340 ResourceMark rm(thread);
341 LogTarget(Trace, vtables) lt;
342 LogStream ls(lt);
343 char* sig = target_method()->name_and_sig_as_C_string();
344 if (overrides) {
345 ls.print("overriding with %s index %d, original flags: ",
346 sig, i);
347 } else {
348 ls.print("NOT overriding with %s index %d, original flags: ",
349 sig, i);
350 }
351 super_method->print_linkage_flags(&ls);
352 ls.print("overriders flags: ");
353 target_method->print_linkage_flags(&ls);
354 ls.cr();
355 }
356 #endif
357 }
358
359 // Update child's copy of super vtable for overrides
360 // OR return true if a new vtable entry is required.
361 // Only called for InstanceKlass's, i.e. not for arrays
362 // If that changed, could not use _klass as handle for klass
363 bool klassVtable::update_inherited_vtable(InstanceKlass* klass, const methodHandle& target_method,
364 int super_vtable_len, int default_index,
365 bool checkconstraints, TRAPS) {
366 ResourceMark rm(THREAD);
367 bool allocate_new = true;
368 assert(klass->is_instance_klass(), "must be InstanceKlass");
369
370 Array<int>* def_vtable_indices = NULL;
371 bool is_default = false;
372
373 // default methods are non-private concrete methods in superinterfaces which are added
374 // to the vtable with their real method_holder.
375 // Since vtable and itable indices share the same storage, don't touch
376 // the default method's real vtable/itable index.
377 // default_vtable_indices stores the vtable value relative to this inheritor
378 if (default_index >= 0 ) {
379 is_default = true;
380 def_vtable_indices = klass->default_vtable_indices();
381 assert(!target_method()->is_private(), "private interface method flagged as default");
382 assert(def_vtable_indices != NULL, "def vtable alloc?");
383 assert(default_index <= def_vtable_indices->length(), "def vtable len?");
384 } else {
385 assert(klass == target_method()->method_holder(), "caller resp.");
386 // Initialize the method's vtable index to "nonvirtual".
387 // If we allocate a vtable entry, we will update it to a non-negative number.
388 target_method()->set_vtable_index(Method::nonvirtual_vtable_index);
389 }
390
391 // Private, static and <init> methods are never in
392 if (target_method()->is_private() || target_method()->is_static() ||
393 (target_method()->name()->fast_compare(vmSymbols::object_initializer_name()) == 0)) {
394 return false;
395 }
396
397 if (target_method->is_final_method(klass->access_flags())) {
398 // a final method never needs a new entry; final methods can be statically
399 // resolved and they have to be present in the vtable only if they override
400 // a super's method, in which case they re-use its entry
401 allocate_new = false;
402 } else if (klass->is_interface()) {
403 allocate_new = false; // see note below in needs_new_vtable_entry
404 // An interface never allocates new vtable slots, only inherits old ones.
405 // This method will either be assigned its own itable index later,
406 // or be assigned an inherited vtable index in the loop below.
407 // default methods inherited by classes store their vtable indices
408 // in the inheritor's default_vtable_indices.
409 // default methods inherited by interfaces may already have a
410 // valid itable index, if so, don't change it.
411 // Overpass methods in an interface will be assigned an itable index later
412 // by an inheriting class.
413 if ((!is_default || !target_method()->has_itable_index())) {
414 target_method()->set_vtable_index(Method::pending_itable_index);
415 }
416 }
417
418 // we need a new entry if there is no superclass
419 Klass* super = klass->super();
420 if (super == NULL) {
421 return allocate_new;
422 }
423
424 // search through the vtable and update overridden entries
425 // Since check_signature_loaders acquires SystemDictionary_lock
426 // which can block for gc, once we are in this loop, use handles
427 // For classfiles built with >= jdk7, we now look for transitive overrides
428
429 Symbol* name = target_method()->name();
430 Symbol* signature = target_method()->signature();
431
432 Klass* target_klass = target_method()->method_holder();
433 if (target_klass == NULL) {
434 target_klass = _klass;
435 }
436
437 Handle target_loader(THREAD, target_klass->class_loader());
438
439 Symbol* target_classname = target_klass->name();
440 for(int i = 0; i < super_vtable_len; i++) {
441 Method* super_method;
442 if (is_preinitialized_vtable()) {
443 // If this is a shared class, the vtable is already in the final state (fully
444 // initialized). Need to look at the super's vtable.
445 klassVtable superVtable = super->vtable();
446 super_method = superVtable.method_at(i);
447 } else {
448 super_method = method_at(i);
449 }
450 // Check if method name matches. Ignore match if klass is an interface and the
451 // matching method is a non-public java.lang.Object method. (See JVMS 5.4.3.4)
452 // This is safe because the method at this slot should never get invoked.
453 // (TBD: put in a method to throw NoSuchMethodError if this slot is ever used.)
454 if (super_method->name() == name && super_method->signature() == signature &&
455 (!_klass->is_interface() ||
456 !SystemDictionary::is_nonpublic_Object_method(super_method))) {
457
458 // get super_klass for method_holder for the found method
459 InstanceKlass* super_klass = super_method->method_holder();
460
461 // Whether the method is being overridden
462 bool overrides = false;
463
464 // private methods are also never overridden
465 if (!super_method->is_private() &&
466 (is_default
467 || ((super_klass->is_override(methodHandle(THREAD, super_method), target_loader, target_classname, THREAD))
468 || ((klass->major_version() >= VTABLE_TRANSITIVE_OVERRIDE_VERSION)
469 && ((super_klass = find_transitive_override(super_klass,
470 target_method, i, target_loader,
471 target_classname, THREAD))
472 != (InstanceKlass*)NULL)))))
473 {
474 // Package private methods always need a new entry to root their own
475 // overriding. They may also override other methods.
476 if (!target_method()->is_package_private()) {
477 allocate_new = false;
478 }
479
480 // Do not check loader constraints for overpass methods because overpass
481 // methods are created by the jvm to throw exceptions.
482 if (checkconstraints && !target_method()->is_overpass()) {
483 // Override vtable entry if passes loader constraint check
484 // if loader constraint checking requested
485 // No need to visit his super, since he and his super
486 // have already made any needed loader constraints.
487 // Since loader constraints are transitive, it is enough
488 // to link to the first super, and we get all the others.
489 Handle super_loader(THREAD, super_klass->class_loader());
490
491 if (target_loader() != super_loader()) {
492 ResourceMark rm(THREAD);
493 Symbol* failed_type_symbol =
494 SystemDictionary::check_signature_loaders(signature, _klass,
495 target_loader, super_loader,
496 true, CHECK_(false));
497 if (failed_type_symbol != NULL) {
498 stringStream ss;
499 ss.print("loader constraint violation for class %s: when selecting "
500 "overriding method '", klass->external_name());
501 target_method()->print_external_name(&ss),
502 ss.print("' the class loader %s of the "
503 "selected method's type %s, and the class loader %s for its super "
504 "type %s have different Class objects for the type %s used in the signature (%s; %s)",
505 target_klass->class_loader_data()->loader_name_and_id(),
506 target_klass->external_name(),
507 super_klass->class_loader_data()->loader_name_and_id(),
508 super_klass->external_name(),
509 failed_type_symbol->as_klass_external_name(),
510 target_klass->class_in_module_of_loader(false, true),
511 super_klass->class_in_module_of_loader(false, true));
512 THROW_MSG_(vmSymbols::java_lang_LinkageError(), ss.as_string(), false);
513 }
514 }
515 }
516
517 put_method_at(target_method(), i);
518 overrides = true;
519 if (!is_default) {
520 target_method()->set_vtable_index(i);
521 } else {
522 if (def_vtable_indices != NULL) {
523 if (is_preinitialized_vtable()) {
524 // At runtime initialize_vtable is rerun as part of link_class_impl()
525 // for a shared class loaded by the non-boot loader.
526 // The dumptime vtable index should be the same as the runtime index.
527 assert(def_vtable_indices->at(default_index) == i,
528 "dump time vtable index is different from runtime index");
529 } else {
530 def_vtable_indices->at_put(default_index, i);
531 }
532 }
533 assert(super_method->is_default_method() || super_method->is_overpass()
534 || super_method->is_abstract(), "default override error");
535 }
536 } else {
537 overrides = false;
538 }
539 log_vtables(i, overrides, target_method, target_klass, super_method, THREAD);
540 }
541 }
542 return allocate_new;
543 }
544
545 void klassVtable::put_method_at(Method* m, int index) {
546 assert(!m->is_private(), "private methods should not be in vtable");
547 if (is_preinitialized_vtable()) {
548 // At runtime initialize_vtable is rerun as part of link_class_impl()
549 // for shared class loaded by the non-boot loader to obtain the loader
550 // constraints based on the runtime classloaders' context. The dumptime
551 // method at the vtable index should be the same as the runtime method.
552 assert(table()[index].method() == m,
553 "archived method is different from the runtime method");
554 } else {
555 if (log_develop_is_enabled(Trace, vtables)) {
556 ResourceMark rm;
557 LogTarget(Trace, vtables) lt;
558 LogStream ls(lt);
559 const char* sig = (m != NULL) ? m->name_and_sig_as_C_string() : "<NULL>";
560 ls.print("adding %s at index %d, flags: ", sig, index);
561 if (m != NULL) {
562 m->print_linkage_flags(&ls);
563 }
564 ls.cr();
565 }
566 table()[index].set(m);
567 }
568 }
569
570 // Find out if a method "m" with superclass "super", loader "classloader" and
571 // name "classname" needs a new vtable entry. Let P be a class package defined
572 // by "classloader" and "classname".
573 // NOTE: The logic used here is very similar to the one used for computing
574 // the vtables indices for a method. We cannot directly use that function because,
575 // we allocate the InstanceKlass at load time, and that requires that the
576 // superclass has been loaded.
577 // However, the vtable entries are filled in at link time, and therefore
578 // the superclass' vtable may not yet have been filled in.
579 bool klassVtable::needs_new_vtable_entry(const methodHandle& target_method,
580 const Klass* super,
581 Handle classloader,
582 Symbol* classname,
583 AccessFlags class_flags,
584 u2 major_version,
585 TRAPS) {
586 if (class_flags.is_interface()) {
587 // Interfaces do not use vtables, except for java.lang.Object methods,
588 // so there is no point to assigning
589 // a vtable index to any of their local methods. If we refrain from doing this,
590 // we can use Method::_vtable_index to hold the itable index
591 return false;
592 }
593
594 if (target_method->is_final_method(class_flags) ||
595 // a final method never needs a new entry; final methods can be statically
596 // resolved and they have to be present in the vtable only if they override
597 // a super's method, in which case they re-use its entry
598 (target_method()->is_private()) ||
599 // private methods don't need to be in vtable
600 (target_method()->is_static()) ||
601 // static methods don't need to be in vtable
602 (target_method()->name()->fast_compare(vmSymbols::object_initializer_name()) == 0)
603 // <init> is never called dynamically-bound
604 ) {
605 return false;
606 }
607
608 // Concrete interface methods do not need new entries, they override
609 // abstract method entries using default inheritance rules
610 if (target_method()->method_holder() != NULL &&
611 target_method()->method_holder()->is_interface() &&
612 !target_method()->is_abstract()) {
613 assert(target_method()->is_default_method(),
614 "unexpected interface method type");
615 return false;
616 }
617
618 // we need a new entry if there is no superclass
619 if (super == NULL) {
620 return true;
621 }
622
623 // Package private methods always need a new entry to root their own
624 // overriding. This allows transitive overriding to work.
625 if (target_method()->is_package_private()) {
626 return true;
627 }
628
629 // search through the super class hierarchy to see if we need
630 // a new entry
631 ResourceMark rm(THREAD);
632 Symbol* name = target_method()->name();
633 Symbol* signature = target_method()->signature();
634 const Klass* k = super;
635 Method* super_method = NULL;
636 InstanceKlass *holder = NULL;
637 Method* recheck_method = NULL;
638 bool found_pkg_prvt_method = false;
639 while (k != NULL) {
640 // lookup through the hierarchy for a method with matching name and sign.
641 super_method = InstanceKlass::cast(k)->lookup_method(name, signature);
642 if (super_method == NULL) {
643 break; // we still have to search for a matching miranda method
644 }
645 // get the class holding the matching method
646 // make sure you use that class for is_override
647 InstanceKlass* superk = super_method->method_holder();
648 // we want only instance method matches
649 // ignore private methods found via lookup_method since they do not participate in overriding,
650 // and since we do override around them: e.g. a.m pub/b.m private/c.m pub,
651 // ignore private, c.m pub does override a.m pub
652 // For classes that were not javac'd together, we also do transitive overriding around
653 // methods that have less accessibility
654 if ((!super_method->is_static()) &&
655 (!super_method->is_private())) {
656 if (superk->is_override(methodHandle(THREAD, super_method), classloader, classname, THREAD)) {
657 return false;
658 // else keep looking for transitive overrides
659 }
660 // If we get here then one of the super classes has a package private method
661 // that will not get overridden because it is in a different package. But,
662 // that package private method does "override" any matching methods in super
663 // interfaces, so there will be no miranda vtable entry created. So, set flag
664 // to TRUE for use below, in case there are no methods in super classes that
665 // this target method overrides.
666 assert(super_method->is_package_private(), "super_method must be package private");
667 assert(!superk->is_same_class_package(classloader(), classname),
668 "Must be different packages");
669 found_pkg_prvt_method = true;
670 }
671
672 // Start with lookup result and continue to search up, for versions supporting transitive override
673 if (major_version >= VTABLE_TRANSITIVE_OVERRIDE_VERSION) {
674 k = superk->super(); // haven't found an override match yet; continue to look
675 } else {
676 break;
677 }
678 }
679
680 // If found_pkg_prvt_method is set, then the ONLY matching method in the
681 // superclasses is package private in another package. That matching method will
682 // prevent a miranda vtable entry from being created. Because the target method can not
683 // override the package private method in another package, then it needs to be the root
684 // for its own vtable entry.
685 if (found_pkg_prvt_method) {
686 return true;
687 }
688
689 // if the target method is public or protected it may have a matching
690 // miranda method in the super, whose entry it should re-use.
691 // Actually, to handle cases that javac would not generate, we need
692 // this check for all access permissions.
693 const InstanceKlass *sk = InstanceKlass::cast(super);
694 if (sk->has_miranda_methods()) {
695 if (sk->lookup_method_in_all_interfaces(name, signature, Klass::find_defaults) != NULL) {
696 return false; // found a matching miranda; we do not need a new entry
697 }
698 }
699 return true; // found no match; we need a new entry
700 }
701
702 // Support for miranda methods
703
704 // get the vtable index of a miranda method with matching "name" and "signature"
705 int klassVtable::index_of_miranda(Symbol* name, Symbol* signature) {
706 // search from the bottom, might be faster
707 for (int i = (length() - 1); i >= 0; i--) {
708 Method* m = table()[i].method();
709 if (is_miranda_entry_at(i) &&
710 m->name() == name && m->signature() == signature) {
711 return i;
712 }
713 }
714 return Method::invalid_vtable_index;
715 }
716
717 // check if an entry at an index is miranda
718 // requires that method m at entry be declared ("held") by an interface.
719 bool klassVtable::is_miranda_entry_at(int i) {
720 Method* m = method_at(i);
721 Klass* method_holder = m->method_holder();
722 InstanceKlass *mhk = InstanceKlass::cast(method_holder);
723
724 // miranda methods are public abstract instance interface methods in a class's vtable
725 if (mhk->is_interface()) {
726 assert(m->is_public(), "should be public");
727 assert(ik()->implements_interface(method_holder) , "this class should implement the interface");
728 if (is_miranda(m, ik()->methods(), ik()->default_methods(), ik()->super(), klass()->is_interface())) {
729 return true;
730 }
731 }
732 return false;
733 }
734
735 // Check if a method is a miranda method, given a class's methods array,
736 // its default_method table and its super class.
737 // "Miranda" means an abstract non-private method that would not be
738 // overridden for the local class.
739 // A "miranda" method should only include non-private interface
740 // instance methods, i.e. not private methods, not static methods,
741 // not default methods (concrete interface methods), not overpass methods.
742 // If a given class already has a local (including overpass) method, a
743 // default method, or any of its superclasses has the same which would have
744 // overridden an abstract method, then this is not a miranda method.
745 //
746 // Miranda methods are checked multiple times.
747 // Pass 1: during class load/class file parsing: before vtable size calculation:
748 // include superinterface abstract and default methods (non-private instance).
749 // We include potential default methods to give them space in the vtable.
750 // During the first run, the current instanceKlass has not yet been
751 // created, the superclasses and superinterfaces do have instanceKlasses
752 // but may not have vtables, the default_methods list is empty, no overpasses.
753 // Default method generation uses the all_mirandas array as the starter set for
754 // maximally-specific default method calculation. So, for both classes and
755 // interfaces, it is necessary that the first pass will find all non-private
756 // interface instance methods, whether or not they are concrete.
757 //
758 // Pass 2: recalculated during vtable initialization: only include abstract methods.
759 // The goal of pass 2 is to walk through the superinterfaces to see if any of
760 // the superinterface methods (which were all abstract pre-default methods)
761 // need to be added to the vtable.
762 // With the addition of default methods, we have three new challenges:
763 // overpasses, static interface methods and private interface methods.
764 // Static and private interface methods do not get added to the vtable and
765 // are not seen by the method resolution process, so we skip those.
766 // Overpass methods are already in the vtable, so vtable lookup will
767 // find them and we don't need to add a miranda method to the end of
768 // the vtable. So we look for overpass methods and if they are found we
769 // return false. Note that we inherit our superclasses vtable, so
770 // the superclass' search also needs to use find_overpass so that if
771 // one is found we return false.
772 // False means - we don't need a miranda method added to the vtable.
773 //
774 // During the second run, default_methods is set up, so concrete methods from
775 // superinterfaces with matching names/signatures to default_methods are already
776 // in the default_methods list and do not need to be appended to the vtable
777 // as mirandas. Abstract methods may already have been handled via
778 // overpasses - either local or superclass overpasses, which may be
779 // in the vtable already.
780 //
781 // Pass 3: They are also checked by link resolution and selection,
782 // for invocation on a method (not interface method) reference that
783 // resolves to a method with an interface as its method_holder.
784 // Used as part of walking from the bottom of the vtable to find
785 // the vtable index for the miranda method.
786 //
787 // Part of the Miranda Rights in the US mean that if you do not have
788 // an attorney one will be appointed for you.
789 bool klassVtable::is_miranda(Method* m, Array<Method*>* class_methods,
790 Array<Method*>* default_methods, const Klass* super,
791 bool is_interface) {
792 if (m->is_static() || m->is_private() || m->is_overpass()) {
793 return false;
794 }
795 Symbol* name = m->name();
796 Symbol* signature = m->signature();
797
798 // First look in local methods to see if already covered
799 if (InstanceKlass::find_local_method(class_methods, name, signature,
800 Klass::find_overpass, Klass::skip_static, Klass::skip_private) != NULL)
801 {
802 return false;
803 }
804
805 // Check local default methods
806 if ((default_methods != NULL) &&
807 (InstanceKlass::find_method(default_methods, name, signature) != NULL))
808 {
809 return false;
810 }
811
812 // Iterate on all superclasses, which should be InstanceKlasses.
813 // Note that we explicitly look for overpasses at each level.
814 // Overpasses may or may not exist for supers for pass 1,
815 // they should have been created for pass 2 and later.
816
817 for (const Klass* cursuper = super; cursuper != NULL; cursuper = cursuper->super())
818 {
819 Method* found_mth = InstanceKlass::cast(cursuper)->find_local_method(name, signature,
820 Klass::find_overpass, Klass::skip_static, Klass::skip_private);
821 // Ignore non-public methods in java.lang.Object if klass is an interface.
822 if (found_mth != NULL && (!is_interface ||
823 !SystemDictionary::is_nonpublic_Object_method(found_mth))) {
824 return false;
825 }
826 }
827
828 return true;
829 }
830
831 // Scans current_interface_methods for miranda methods that do not
832 // already appear in new_mirandas, or default methods, and are also not defined-and-non-private
833 // in super (superclass). These mirandas are added to all_mirandas if it is
834 // not null; in addition, those that are not duplicates of miranda methods
835 // inherited by super from its interfaces are added to new_mirandas.
836 // Thus, new_mirandas will be the set of mirandas that this class introduces,
837 // all_mirandas will be the set of all mirandas applicable to this class
838 // including all defined in superclasses.
839 void klassVtable::add_new_mirandas_to_lists(
840 GrowableArray<Method*>* new_mirandas, GrowableArray<Method*>* all_mirandas,
841 Array<Method*>* current_interface_methods, Array<Method*>* class_methods,
842 Array<Method*>* default_methods, const Klass* super, bool is_interface) {
843
844 // iterate thru the current interface's method to see if it a miranda
845 int num_methods = current_interface_methods->length();
846 for (int i = 0; i < num_methods; i++) {
847 Method* im = current_interface_methods->at(i);
848 bool is_duplicate = false;
849 int num_of_current_mirandas = new_mirandas->length();
850 // check for duplicate mirandas in different interfaces we implement
851 for (int j = 0; j < num_of_current_mirandas; j++) {
852 Method* miranda = new_mirandas->at(j);
853 if ((im->name() == miranda->name()) &&
854 (im->signature() == miranda->signature())) {
855 is_duplicate = true;
856 break;
857 }
858 }
859
860 if (!is_duplicate) { // we don't want duplicate miranda entries in the vtable
861 if (is_miranda(im, class_methods, default_methods, super, is_interface)) { // is it a miranda at all?
862 const InstanceKlass *sk = InstanceKlass::cast(super);
863 // check if it is a duplicate of a super's miranda
864 if (sk->lookup_method_in_all_interfaces(im->name(), im->signature(), Klass::find_defaults) == NULL) {
865 new_mirandas->append(im);
866 }
867 if (all_mirandas != NULL) {
868 all_mirandas->append(im);
869 }
870 }
871 }
872 }
873 }
874
875 void klassVtable::get_mirandas(GrowableArray<Method*>* new_mirandas,
876 GrowableArray<Method*>* all_mirandas,
877 const Klass* super,
878 Array<Method*>* class_methods,
879 Array<Method*>* default_methods,
880 Array<InstanceKlass*>* local_interfaces,
881 bool is_interface) {
882 assert((new_mirandas->length() == 0) , "current mirandas must be 0");
883
884 // iterate thru the local interfaces looking for a miranda
885 int num_local_ifs = local_interfaces->length();
886 for (int i = 0; i < num_local_ifs; i++) {
887 InstanceKlass *ik = InstanceKlass::cast(local_interfaces->at(i));
888 add_new_mirandas_to_lists(new_mirandas, all_mirandas,
889 ik->methods(), class_methods,
890 default_methods, super, is_interface);
891 // iterate thru each local's super interfaces
892 Array<InstanceKlass*>* super_ifs = ik->transitive_interfaces();
893 int num_super_ifs = super_ifs->length();
894 for (int j = 0; j < num_super_ifs; j++) {
895 InstanceKlass *sik = super_ifs->at(j);
896 add_new_mirandas_to_lists(new_mirandas, all_mirandas,
897 sik->methods(), class_methods,
898 default_methods, super, is_interface);
899 }
900 }
901 }
902
903 // Discover miranda methods ("miranda" = "interface abstract, no binding"),
904 // and append them into the vtable starting at index initialized,
905 // return the new value of initialized.
906 // Miranda methods use vtable entries, but do not get assigned a vtable_index
907 // The vtable_index is discovered by searching from the end of the vtable
908 int klassVtable::fill_in_mirandas(int initialized, TRAPS) {
909 ResourceMark rm(THREAD);
910 GrowableArray<Method*> mirandas(20);
911 get_mirandas(&mirandas, NULL, ik()->super(), ik()->methods(),
912 ik()->default_methods(), ik()->local_interfaces(),
913 klass()->is_interface());
914 for (int i = 0; i < mirandas.length(); i++) {
915 if (log_develop_is_enabled(Trace, vtables)) {
916 Method* meth = mirandas.at(i);
917 LogTarget(Trace, vtables) lt;
918 LogStream ls(lt);
919 if (meth != NULL) {
920 char* sig = meth->name_and_sig_as_C_string();
921 ls.print("fill in mirandas with %s index %d, flags: ",
922 sig, initialized);
923 meth->print_linkage_flags(&ls);
924 ls.cr();
925 }
926 }
927 put_method_at(mirandas.at(i), initialized);
928 ++initialized;
929 }
930 return initialized;
931 }
932
933 // Copy this class's vtable to the vtable beginning at start.
934 // Used to copy superclass vtable to prefix of subclass's vtable.
935 void klassVtable::copy_vtable_to(vtableEntry* start) {
936 Copy::disjoint_words((HeapWord*)table(), (HeapWord*)start, _length * vtableEntry::size());
937 }
938
939 #if INCLUDE_JVMTI
940 bool klassVtable::adjust_default_method(int vtable_index, Method* old_method, Method* new_method) {
941 // If old_method is default, find this vtable index in default_vtable_indices
942 // and replace that method in the _default_methods list
943 bool updated = false;
944
945 Array<Method*>* default_methods = ik()->default_methods();
946 if (default_methods != NULL) {
947 int len = default_methods->length();
948 for (int idx = 0; idx < len; idx++) {
949 if (vtable_index == ik()->default_vtable_indices()->at(idx)) {
950 if (default_methods->at(idx) == old_method) {
951 default_methods->at_put(idx, new_method);
952 updated = true;
953 }
954 break;
955 }
956 }
957 }
958 return updated;
959 }
960
961 // search the vtable for uses of either obsolete or EMCP methods
962 void klassVtable::adjust_method_entries(bool * trace_name_printed) {
963 int prn_enabled = 0;
964 ResourceMark rm;
965
966 for (int index = 0; index < length(); index++) {
967 Method* old_method = unchecked_method_at(index);
968 if (old_method == NULL || !old_method->is_old()) {
969 continue; // skip uninteresting entries
970 }
971 assert(!old_method->is_deleted(), "vtable methods may not be deleted");
972
973 Method* new_method = old_method->get_new_method();
974 put_method_at(new_method, index);
975
976 // For default methods, need to update the _default_methods array
977 // which can only have one method entry for a given signature
978 bool updated_default = false;
979 if (old_method->is_default_method()) {
980 updated_default = adjust_default_method(index, old_method, new_method);
981 }
982
983 if (!(*trace_name_printed)) {
984 log_info(redefine, class, update)
985 ("adjust: klassname=%s for methods from name=%s",
986 _klass->external_name(), old_method->method_holder()->external_name());
987 *trace_name_printed = true;
988 }
989 log_trace(redefine, class, update, vtables)
990 ("vtable method update: class: %s method: %s, updated default = %s",
991 _klass->external_name(), new_method->external_name(), updated_default ? "true" : "false");
992 }
993 }
994
995 // a vtable should never contain old or obsolete methods
996 bool klassVtable::check_no_old_or_obsolete_entries() {
997 ResourceMark rm;
998
999 for (int i = 0; i < length(); i++) {
1000 Method* m = unchecked_method_at(i);
1001 if (m != NULL &&
1002 (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) {
1003 log_trace(redefine, class, update, vtables)
1004 ("vtable check found old method entry: class: %s old: %d obsolete: %d, method: %s",
1005 _klass->external_name(), m->is_old(), m->is_obsolete(), m->external_name());
1006 return false;
1007 }
1008 }
1009 return true;
1010 }
1011
1012 void klassVtable::dump_vtable() {
1013 tty->print_cr("vtable dump --");
1014 for (int i = 0; i < length(); i++) {
1015 Method* m = unchecked_method_at(i);
1016 if (m != NULL) {
1017 tty->print(" (%5d) ", i);
1018 m->access_flags().print_on(tty);
1019 if (m->is_default_method()) {
1020 tty->print("default ");
1021 }
1022 if (m->is_overpass()) {
1023 tty->print("overpass");
1024 }
1025 tty->print(" -- ");
1026 m->print_name(tty);
1027 tty->cr();
1028 }
1029 }
1030 }
1031 #endif // INCLUDE_JVMTI
1032
1033 //-----------------------------------------------------------------------------------------
1034 // Itable code
1035
1036 // Initialize a itableMethodEntry
1037 void itableMethodEntry::initialize(Method* m) {
1038 if (m == NULL) return;
1039
1040 #ifdef ASSERT
1041 if (MetaspaceShared::is_in_shared_metaspace((void*)&_method) &&
1042 !MetaspaceShared::remapped_readwrite()) {
1043 // At runtime initialize_itable is rerun as part of link_class_impl()
1044 // for a shared class loaded by the non-boot loader.
1045 // The dumptime itable method entry should be the same as the runtime entry.
1046 assert(_method == m, "sanity");
1047 }
1048 #endif
1049 _method = m;
1050 }
1051
1052 klassItable::klassItable(InstanceKlass* klass) {
1053 _klass = klass;
1054
1055 if (klass->itable_length() > 0) {
1056 itableOffsetEntry* offset_entry = (itableOffsetEntry*)klass->start_of_itable();
1057 if (offset_entry != NULL && offset_entry->interface_klass() != NULL) { // Check that itable is initialized
1058 // First offset entry points to the first method_entry
1059 intptr_t* method_entry = (intptr_t *)(((address)klass) + offset_entry->offset());
1060 intptr_t* end = klass->end_of_itable();
1061
1062 _table_offset = (intptr_t*)offset_entry - (intptr_t*)klass;
1063 _size_offset_table = (method_entry - ((intptr_t*)offset_entry)) / itableOffsetEntry::size();
1064 _size_method_table = (end - method_entry) / itableMethodEntry::size();
1065 assert(_table_offset >= 0 && _size_offset_table >= 0 && _size_method_table >= 0, "wrong computation");
1066 return;
1067 }
1068 }
1069
1070 // The length of the itable was either zero, or it has not yet been initialized.
1071 _table_offset = 0;
1072 _size_offset_table = 0;
1073 _size_method_table = 0;
1074 }
1075
1076 static int initialize_count = 0;
1077
1078 // Initialization
1079 void klassItable::initialize_itable(bool checkconstraints, TRAPS) {
1080 if (_klass->is_interface()) {
1081 // This needs to go after vtable indices are assigned but
1082 // before implementors need to know the number of itable indices.
1083 assign_itable_indices_for_interface(InstanceKlass::cast(_klass), THREAD);
1084 }
1085
1086 // Cannot be setup doing bootstrapping, interfaces don't have
1087 // itables, and klass with only ones entry have empty itables
1088 if (Universe::is_bootstrapping() ||
1089 _klass->is_interface() ||
1090 _klass->itable_length() == itableOffsetEntry::size()) return;
1091
1092 // There's alway an extra itable entry so we can null-terminate it.
1093 guarantee(size_offset_table() >= 1, "too small");
1094 int num_interfaces = size_offset_table() - 1;
1095 if (num_interfaces > 0) {
1096 ResourceMark rm(THREAD);
1097 log_develop_debug(itables)("%3d: Initializing itables for %s", ++initialize_count,
1098 _klass->name()->as_C_string());
1099
1100
1101 // Iterate through all interfaces
1102 int i;
1103 for(i = 0; i < num_interfaces; i++) {
1104 itableOffsetEntry* ioe = offset_entry(i);
1105 HandleMark hm(THREAD);
1106 Klass* interf = ioe->interface_klass();
1107 assert(interf != NULL && ioe->offset() != 0, "bad offset entry in itable");
1108 initialize_itable_for_interface(ioe->offset(), InstanceKlass::cast(interf), checkconstraints, CHECK);
1109 }
1110
1111 }
1112 // Check that the last entry is empty
1113 itableOffsetEntry* ioe = offset_entry(size_offset_table() - 1);
1114 guarantee(ioe->interface_klass() == NULL && ioe->offset() == 0, "terminator entry missing");
1115 }
1116
1117
1118 inline bool interface_method_needs_itable_index(Method* m) {
1119 if (m->is_static()) return false; // e.g., Stream.empty
1120 if (m->is_initializer()) return false; // <init> or <clinit>
1121 if (m->is_private()) return false; // uses direct call
1122 // If an interface redeclares a method from java.lang.Object,
1123 // it should already have a vtable index, don't touch it.
1124 // e.g., CharSequence.toString (from initialize_vtable)
1125 // if (m->has_vtable_index()) return false; // NO!
1126 return true;
1127 }
1128
1129 int klassItable::assign_itable_indices_for_interface(InstanceKlass* klass, TRAPS) {
1130 // an interface does not have an itable, but its methods need to be numbered
1131 ResourceMark rm(THREAD);
1132 log_develop_debug(itables)("%3d: Initializing itable indices for interface %s",
1133 ++initialize_count, klass->name()->as_C_string());
1134 Array<Method*>* methods = klass->methods();
1135 int nof_methods = methods->length();
1136 int ime_num = 0;
1137 for (int i = 0; i < nof_methods; i++) {
1138 Method* m = methods->at(i);
1139 if (interface_method_needs_itable_index(m)) {
1140 assert(!m->is_final_method(), "no final interface methods");
1141 // If m is already assigned a vtable index, do not disturb it.
1142 if (log_develop_is_enabled(Trace, itables)) {
1143 LogTarget(Trace, itables) lt;
1144 LogStream ls(lt);
1145 assert(m != NULL, "methods can never be null");
1146 const char* sig = m->name_and_sig_as_C_string();
1147 if (m->has_vtable_index()) {
1148 ls.print("vtable index %d for method: %s, flags: ", m->vtable_index(), sig);
1149 } else {
1150 ls.print("itable index %d for method: %s, flags: ", ime_num, sig);
1151 }
1152 m->print_linkage_flags(&ls);
1153 ls.cr();
1154 }
1155 if (!m->has_vtable_index()) {
1156 // A shared method could have an initialized itable_index that
1157 // is < 0.
1158 assert(m->vtable_index() == Method::pending_itable_index ||
1159 m->is_shared(),
1160 "set by initialize_vtable");
1161 m->set_itable_index(ime_num);
1162 // Progress to next itable entry
1163 ime_num++;
1164 }
1165 }
1166 }
1167 assert(ime_num == method_count_for_interface(klass), "proper sizing");
1168 return ime_num;
1169 }
1170
1171 int klassItable::method_count_for_interface(InstanceKlass* interf) {
1172 assert(interf->is_interface(), "must be");
1173 Array<Method*>* methods = interf->methods();
1174 int nof_methods = methods->length();
1175 int length = 0;
1176 while (nof_methods > 0) {
1177 Method* m = methods->at(nof_methods-1);
1178 if (m->has_itable_index()) {
1179 length = m->itable_index() + 1;
1180 break;
1181 }
1182 nof_methods -= 1;
1183 }
1184 #ifdef ASSERT
1185 int nof_methods_copy = nof_methods;
1186 while (nof_methods_copy > 0) {
1187 Method* mm = methods->at(--nof_methods_copy);
1188 assert(!mm->has_itable_index() || mm->itable_index() < length, "");
1189 }
1190 #endif //ASSERT
1191 // return the rightmost itable index, plus one; or 0 if no methods have
1192 // itable indices
1193 return length;
1194 }
1195
1196
1197 void klassItable::initialize_itable_for_interface(int method_table_offset, InstanceKlass* interf, bool checkconstraints, TRAPS) {
1198 assert(interf->is_interface(), "must be");
1199 Array<Method*>* methods = interf->methods();
1200 int nof_methods = methods->length();
1201 HandleMark hm(THREAD);
1202 Handle interface_loader (THREAD, interf->class_loader());
1203
1204 int ime_count = method_count_for_interface(interf);
1205 for (int i = 0; i < nof_methods; i++) {
1206 Method* m = methods->at(i);
1207 Method* target = NULL;
1208 if (m->has_itable_index()) {
1209 // This search must match the runtime resolution, i.e. selection search for invokeinterface
1210 // to correctly enforce loader constraints for interface method inheritance.
1211 // Private methods are skipped as a private class method can never be the implementation
1212 // of an interface method.
1213 // Invokespecial does not perform selection based on the receiver, so it does not use
1214 // the cached itable.
1215 target = LinkResolver::lookup_instance_method_in_klasses(_klass, m->name(), m->signature(),
1216 Klass::skip_private, CHECK);
1217 }
1218 if (target == NULL || !target->is_public() || target->is_abstract() || target->is_overpass()) {
1219 assert(target == NULL || !target->is_overpass() || target->is_public(),
1220 "Non-public overpass method!");
1221 // Entry does not resolve. Leave it empty for AbstractMethodError or other error.
1222 if (!(target == NULL) && !target->is_public()) {
1223 // Stuff an IllegalAccessError throwing method in there instead.
1224 itableOffsetEntry::method_entry(_klass, method_table_offset)[m->itable_index()].
1225 initialize(Universe::throw_illegal_access_error());
1226 }
1227 } else {
1228 // Entry did resolve, check loader constraints before initializing
1229 // if checkconstraints requested
1230 if (checkconstraints) {
1231 Handle method_holder_loader (THREAD, target->method_holder()->class_loader());
1232 InstanceKlass* method_holder = target->method_holder();
1233 if (method_holder_loader() != interface_loader()) {
1234 ResourceMark rm(THREAD);
1235 Symbol* failed_type_symbol =
1236 SystemDictionary::check_signature_loaders(m->signature(),
1237 _klass,
1238 method_holder_loader,
1239 interface_loader,
1240 true, CHECK);
1241 if (failed_type_symbol != NULL) {
1242 stringStream ss;
1243 ss.print("loader constraint violation in interface itable"
1244 " initialization for class %s: when selecting method '",
1245 _klass->external_name());
1246 m->print_external_name(&ss),
1247 ss.print("' the class loader %s for super interface %s, and the class"
1248 " loader %s of the selected method's %s, %s have"
1249 " different Class objects for the type %s used in the signature (%s; %s)",
1250 interf->class_loader_data()->loader_name_and_id(),
1251 interf->external_name(),
1252 method_holder->class_loader_data()->loader_name_and_id(),
1253 method_holder->external_kind(),
1254 method_holder->external_name(),
1255 failed_type_symbol->as_klass_external_name(),
1256 interf->class_in_module_of_loader(false, true),
1257 method_holder->class_in_module_of_loader(false, true));
1258 THROW_MSG(vmSymbols::java_lang_LinkageError(), ss.as_string());
1259 }
1260 }
1261 }
1262
1263 // ime may have moved during GC so recalculate address
1264 int ime_num = m->itable_index();
1265 assert(ime_num < ime_count, "oob");
1266 itableOffsetEntry::method_entry(_klass, method_table_offset)[ime_num].initialize(target);
1267 if (log_develop_is_enabled(Trace, itables)) {
1268 ResourceMark rm(THREAD);
1269 if (target != NULL) {
1270 LogTarget(Trace, itables) lt;
1271 LogStream ls(lt);
1272 char* sig = target->name_and_sig_as_C_string();
1273 ls.print("interface: %s, ime_num: %d, target: %s, method_holder: %s ",
1274 interf->internal_name(), ime_num, sig,
1275 target->method_holder()->internal_name());
1276 ls.print("target_method flags: ");
1277 target->print_linkage_flags(&ls);
1278 ls.cr();
1279 }
1280 }
1281 }
1282 }
1283 }
1284
1285 #if INCLUDE_JVMTI
1286 // search the itable for uses of either obsolete or EMCP methods
1287 void klassItable::adjust_method_entries(bool * trace_name_printed) {
1288 ResourceMark rm;
1289 itableMethodEntry* ime = method_entry(0);
1290
1291 for (int i = 0; i < _size_method_table; i++, ime++) {
1292 Method* old_method = ime->method();
1293 if (old_method == NULL || !old_method->is_old()) {
1294 continue; // skip uninteresting entries
1295 }
1296 assert(!old_method->is_deleted(), "itable methods may not be deleted");
1297 Method* new_method = old_method->get_new_method();
1298 ime->initialize(new_method);
1299
1300 if (!(*trace_name_printed)) {
1301 log_info(redefine, class, update)("adjust: name=%s", old_method->method_holder()->external_name());
1302 *trace_name_printed = true;
1303 }
1304 log_trace(redefine, class, update, itables)
1305 ("itable method update: class: %s method: %s", _klass->external_name(), new_method->external_name());
1306 }
1307 }
1308
1309 // an itable should never contain old or obsolete methods
1310 bool klassItable::check_no_old_or_obsolete_entries() {
1311 ResourceMark rm;
1312 itableMethodEntry* ime = method_entry(0);
1313
1314 for (int i = 0; i < _size_method_table; i++) {
1315 Method* m = ime->method();
1316 if (m != NULL &&
1317 (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) {
1318 log_trace(redefine, class, update, itables)
1319 ("itable check found old method entry: class: %s old: %d obsolete: %d, method: %s",
1320 _klass->external_name(), m->is_old(), m->is_obsolete(), m->external_name());
1321 return false;
1322 }
1323 ime++;
1324 }
1325 return true;
1326 }
1327
1328 void klassItable::dump_itable() {
1329 itableMethodEntry* ime = method_entry(0);
1330 tty->print_cr("itable dump --");
1331 for (int i = 0; i < _size_method_table; i++) {
1332 Method* m = ime->method();
1333 if (m != NULL) {
1334 tty->print(" (%5d) ", i);
1335 m->access_flags().print_on(tty);
1336 if (m->is_default_method()) {
1337 tty->print("default ");
1338 }
1339 tty->print(" -- ");
1340 m->print_name(tty);
1341 tty->cr();
1342 }
1343 ime++;
1344 }
1345 }
1346 #endif // INCLUDE_JVMTI
1347
1348 // Setup
1349 class InterfaceVisiterClosure : public StackObj {
1350 public:
1351 virtual void doit(InstanceKlass* intf, int method_count) = 0;
1352 };
1353
1354 // Visit all interfaces with at least one itable method
1355 void visit_all_interfaces(Array<InstanceKlass*>* transitive_intf, InterfaceVisiterClosure *blk) {
1356 // Handle array argument
1357 for(int i = 0; i < transitive_intf->length(); i++) {
1358 InstanceKlass* intf = transitive_intf->at(i);
1359 assert(intf->is_interface(), "sanity check");
1360
1361 // Find no. of itable methods
1362 int method_count = 0;
1363 // method_count = klassItable::method_count_for_interface(intf);
1364 Array<Method*>* methods = intf->methods();
1365 if (methods->length() > 0) {
1366 for (int i = methods->length(); --i >= 0; ) {
1367 if (interface_method_needs_itable_index(methods->at(i))) {
1368 method_count++;
1369 }
1370 }
1371 }
1372
1373 // Visit all interfaces which either have any methods or can participate in receiver type check.
1374 // We do not bother to count methods in transitive interfaces, although that would allow us to skip
1375 // this step in the rare case of a zero-method interface extending another zero-method interface.
1376 if (method_count > 0 || intf->transitive_interfaces()->length() > 0) {
1377 blk->doit(intf, method_count);
1378 }
1379 }
1380 }
1381
1382 class CountInterfacesClosure : public InterfaceVisiterClosure {
1383 private:
1384 int _nof_methods;
1385 int _nof_interfaces;
1386 public:
1387 CountInterfacesClosure() { _nof_methods = 0; _nof_interfaces = 0; }
1388
1389 int nof_methods() const { return _nof_methods; }
1390 int nof_interfaces() const { return _nof_interfaces; }
1391
1392 void doit(InstanceKlass* intf, int method_count) { _nof_methods += method_count; _nof_interfaces++; }
1393 };
1394
1395 class SetupItableClosure : public InterfaceVisiterClosure {
1396 private:
1397 itableOffsetEntry* _offset_entry;
1398 itableMethodEntry* _method_entry;
1399 address _klass_begin;
1400 public:
1401 SetupItableClosure(address klass_begin, itableOffsetEntry* offset_entry, itableMethodEntry* method_entry) {
1402 _klass_begin = klass_begin;
1403 _offset_entry = offset_entry;
1404 _method_entry = method_entry;
1405 }
1406
1407 itableMethodEntry* method_entry() const { return _method_entry; }
1408
1409 void doit(InstanceKlass* intf, int method_count) {
1410 int offset = ((address)_method_entry) - _klass_begin;
1411 _offset_entry->initialize(intf, offset);
1412 _offset_entry++;
1413 _method_entry += method_count;
1414 }
1415 };
1416
1417 int klassItable::compute_itable_size(Array<InstanceKlass*>* transitive_interfaces) {
1418 // Count no of interfaces and total number of interface methods
1419 CountInterfacesClosure cic;
1420 visit_all_interfaces(transitive_interfaces, &cic);
1421
1422 // There's alway an extra itable entry so we can null-terminate it.
1423 int itable_size = calc_itable_size(cic.nof_interfaces() + 1, cic.nof_methods());
1424
1425 // Statistics
1426 update_stats(itable_size * wordSize);
1427
1428 return itable_size;
1429 }
1430
1431
1432 // Fill out offset table and interface klasses into the itable space
1433 void klassItable::setup_itable_offset_table(InstanceKlass* klass) {
1434 if (klass->itable_length() == 0) return;
1435 assert(!klass->is_interface(), "Should have zero length itable");
1436
1437 // Count no of interfaces and total number of interface methods
1438 CountInterfacesClosure cic;
1439 visit_all_interfaces(klass->transitive_interfaces(), &cic);
1440 int nof_methods = cic.nof_methods();
1441 int nof_interfaces = cic.nof_interfaces();
1442
1443 // Add one extra entry so we can null-terminate the table
1444 nof_interfaces++;
1445
1446 assert(compute_itable_size(klass->transitive_interfaces()) ==
1447 calc_itable_size(nof_interfaces, nof_methods),
1448 "mismatch calculation of itable size");
1449
1450 // Fill-out offset table
1451 itableOffsetEntry* ioe = (itableOffsetEntry*)klass->start_of_itable();
1452 itableMethodEntry* ime = (itableMethodEntry*)(ioe + nof_interfaces);
1453 intptr_t* end = klass->end_of_itable();
1454 assert((oop*)(ime + nof_methods) <= (oop*)klass->start_of_nonstatic_oop_maps(), "wrong offset calculation (1)");
1455 assert((oop*)(end) == (oop*)(ime + nof_methods), "wrong offset calculation (2)");
1456
1457 // Visit all interfaces and initialize itable offset table
1458 SetupItableClosure sic((address)klass, ioe, ime);
1459 visit_all_interfaces(klass->transitive_interfaces(), &sic);
1460
1461 #ifdef ASSERT
1462 ime = sic.method_entry();
1463 oop* v = (oop*) klass->end_of_itable();
1464 assert( (oop*)(ime) == v, "wrong offset calculation (2)");
1465 #endif
1466 }
1467
1468 void klassVtable::verify(outputStream* st, bool forced) {
1469 // make sure table is initialized
1470 if (!Universe::is_fully_initialized()) return;
1471 #ifndef PRODUCT
1472 // avoid redundant verifies
1473 if (!forced && _verify_count == Universe::verify_count()) return;
1474 _verify_count = Universe::verify_count();
1475 #endif
1476 oop* end_of_obj = (oop*)_klass + _klass->size();
1477 oop* end_of_vtable = (oop *)&table()[_length];
1478 if (end_of_vtable > end_of_obj) {
1479 ResourceMark rm;
1480 fatal("klass %s: klass object too short (vtable extends beyond end)",
1481 _klass->internal_name());
1482 }
1483
1484 for (int i = 0; i < _length; i++) table()[i].verify(this, st);
1485 // verify consistency with superKlass vtable
1486 Klass* super = _klass->super();
1487 if (super != NULL) {
1488 InstanceKlass* sk = InstanceKlass::cast(super);
1489 klassVtable vt = sk->vtable();
1490 for (int i = 0; i < vt.length(); i++) {
1491 verify_against(st, &vt, i);
1492 }
1493 }
1494 }
1495
1496 void klassVtable::verify_against(outputStream* st, klassVtable* vt, int index) {
1497 vtableEntry* vte = &vt->table()[index];
1498 if (vte->method()->name() != table()[index].method()->name() ||
1499 vte->method()->signature() != table()[index].method()->signature()) {
1500 fatal("mismatched name/signature of vtable entries");
1501 }
1502 }
1503
1504 #ifndef PRODUCT
1505 void klassVtable::print() {
1506 ResourceMark rm;
1507 tty->print("klassVtable for klass %s (length %d):\n", _klass->internal_name(), length());
1508 for (int i = 0; i < length(); i++) {
1509 table()[i].print();
1510 tty->cr();
1511 }
1512 }
1513 #endif
1514
1515 void vtableEntry::verify(klassVtable* vt, outputStream* st) {
1516 Klass* vtklass = vt->klass();
1517 if (vtklass->is_instance_klass() &&
1518 (InstanceKlass::cast(vtklass)->major_version() >= klassVtable::VTABLE_TRANSITIVE_OVERRIDE_VERSION)) {
1519 assert(method() != NULL, "must have set method");
1520 }
1521 if (method() != NULL) {
1522 method()->verify();
1523 // we sub_type, because it could be a miranda method
1524 if (!vtklass->is_subtype_of(method()->method_holder())) {
1525 #ifndef PRODUCT
1526 print();
1527 #endif
1528 fatal("vtableEntry " PTR_FORMAT ": method is from subclass", p2i(this));
1529 }
1530 }
1531 }
1532
1533 #ifndef PRODUCT
1534
1535 void vtableEntry::print() {
1536 ResourceMark rm;
1537 tty->print("vtableEntry %s: ", method()->name()->as_C_string());
1538 if (Verbose) {
1539 tty->print("m " PTR_FORMAT " ", p2i(method()));
1540 }
1541 }
1542
1543 class VtableStats : AllStatic {
1544 public:
1545 static int no_klasses; // # classes with vtables
1546 static int no_array_klasses; // # array classes
1547 static int no_instance_klasses; // # instanceKlasses
1548 static int sum_of_vtable_len; // total # of vtable entries
1549 static int sum_of_array_vtable_len; // total # of vtable entries in array klasses only
1550 static int fixed; // total fixed overhead in bytes
1551 static int filler; // overhead caused by filler bytes
1552 static int entries; // total bytes consumed by vtable entries
1553 static int array_entries; // total bytes consumed by array vtable entries
1554
1555 static void do_class(Klass* k) {
1556 Klass* kl = k;
1557 klassVtable vt = kl->vtable();
1558 no_klasses++;
1559 if (kl->is_instance_klass()) {
1560 no_instance_klasses++;
1561 kl->array_klasses_do(do_class);
1562 }
1563 if (kl->is_array_klass()) {
1564 no_array_klasses++;
1565 sum_of_array_vtable_len += vt.length();
1566 }
1567 sum_of_vtable_len += vt.length();
1568 }
1569
1570 static void compute() {
1571 LockedClassesDo locked_do_class(&do_class);
1572 ClassLoaderDataGraph::classes_do(&locked_do_class);
1573 fixed = no_klasses * oopSize; // vtable length
1574 // filler size is a conservative approximation
1575 filler = oopSize * (no_klasses - no_instance_klasses) * (sizeof(InstanceKlass) - sizeof(ArrayKlass) - 1);
1576 entries = sizeof(vtableEntry) * sum_of_vtable_len;
1577 array_entries = sizeof(vtableEntry) * sum_of_array_vtable_len;
1578 }
1579 };
1580
1581 int VtableStats::no_klasses = 0;
1582 int VtableStats::no_array_klasses = 0;
1583 int VtableStats::no_instance_klasses = 0;
1584 int VtableStats::sum_of_vtable_len = 0;
1585 int VtableStats::sum_of_array_vtable_len = 0;
1586 int VtableStats::fixed = 0;
1587 int VtableStats::filler = 0;
1588 int VtableStats::entries = 0;
1589 int VtableStats::array_entries = 0;
1590
1591 void klassVtable::print_statistics() {
1592 ResourceMark rm;
1593 VtableStats::compute();
1594 tty->print_cr("vtable statistics:");
1595 tty->print_cr("%6d classes (%d instance, %d array)", VtableStats::no_klasses, VtableStats::no_instance_klasses, VtableStats::no_array_klasses);
1596 int total = VtableStats::fixed + VtableStats::filler + VtableStats::entries;
1597 tty->print_cr("%6d bytes fixed overhead (refs + vtable object header)", VtableStats::fixed);
1598 tty->print_cr("%6d bytes filler overhead", VtableStats::filler);
1599 tty->print_cr("%6d bytes for vtable entries (%d for arrays)", VtableStats::entries, VtableStats::array_entries);
1600 tty->print_cr("%6d bytes total", total);
1601 }
1602
1603 int klassItable::_total_classes; // Total no. of classes with itables
1604 long klassItable::_total_size; // Total no. of bytes used for itables
1605
1606 void klassItable::print_statistics() {
1607 tty->print_cr("itable statistics:");
1608 tty->print_cr("%6d classes with itables", _total_classes);
1609 tty->print_cr("%6lu K uses for itables (average by class: %ld bytes)", _total_size / K, _total_size / _total_classes);
1610 }
1611
1612 #endif // PRODUCT