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