1 /*
2 * Copyright (c) 1997, 2017, 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/systemDictionary.hpp"
28 #include "classfile/vmSymbols.hpp"
29 #include "gc/shared/gcLocker.hpp"
30 #include "logging/log.hpp"
31 #include "logging/logStream.hpp"
32 #include "memory/metaspaceShared.hpp"
33 #include "memory/resourceArea.hpp"
34 #include "memory/universe.inline.hpp"
35 #include "oops/instanceKlass.hpp"
36 #include "oops/klassVtable.hpp"
37 #include "oops/method.hpp"
38 #include "oops/objArrayOop.hpp"
39 #include "oops/oop.inline.hpp"
40 #include "runtime/arguments.hpp"
41 #include "runtime/handles.inline.hpp"
42 #include "utilities/copy.hpp"
43
44 inline InstanceKlass* klassVtable::ik() const {
45 return InstanceKlass::cast(_klass);
46 }
47
48 bool klassVtable::is_preinitialized_vtable() {
49 return _klass->is_shared() && !MetaspaceShared::remapped_readwrite();
50 }
51
52
53 // this function computes the vtable size (including the size needed for miranda
54 // methods) and the number of miranda methods in this class.
55 // Note on Miranda methods: Let's say there is a class C that implements
56 // interface I, and none of C's superclasses implements I.
57 // Let's say there is an abstract method m in I that neither C
58 // nor any of its super classes implement (i.e there is no method of any access,
59 // with the same name and signature as m), then m is a Miranda method which is
60 // entered as a public abstract method in C's vtable. From then on it should
61 // treated as any other public method in C for method over-ride purposes.
62 void klassVtable::compute_vtable_size_and_num_mirandas(
63 int* vtable_length_ret, int* num_new_mirandas,
64 GrowableArray<Method*>* all_mirandas, const Klass* super,
65 Array<Method*>* methods, AccessFlags class_flags, u2 major_version,
66 Handle classloader, Symbol* classname, Array<Klass*>* local_interfaces,
67 TRAPS) {
68 NoSafepointVerifier nsv;
69
70 // set up default result values
71 int vtable_length = 0;
72
73 // start off with super's vtable length
74 vtable_length = super == NULL ? 0 : super->vtable_length();
75
76 // go thru each method in the methods table to see if it needs a new entry
77 int len = methods->length();
78 for (int i = 0; i < len; i++) {
79 assert(methods->at(i)->is_method(), "must be a Method*");
80 methodHandle mh(THREAD, methods->at(i));
81
82 if (needs_new_vtable_entry(mh, super, classloader, classname, class_flags, major_version, THREAD)) {
83 vtable_length += vtableEntry::size(); // we need a new entry
84 }
85 }
86
87 GrowableArray<Method*> new_mirandas(20);
88 // compute the number of mirandas methods that must be added to the end
89 get_mirandas(&new_mirandas, all_mirandas, super, methods, NULL, local_interfaces);
90 *num_new_mirandas = new_mirandas.length();
91
92 // Interfaces do not need interface methods in their vtables
93 // This includes miranda methods and during later processing, default methods
94 if (!class_flags.is_interface()) {
95 vtable_length += *num_new_mirandas * vtableEntry::size();
96 }
97
98 if (Universe::is_bootstrapping() && vtable_length == 0) {
99 // array classes don't have their superclass set correctly during
100 // bootstrapping
101 vtable_length = Universe::base_vtable_size();
102 }
103
104 if (super == NULL && vtable_length != Universe::base_vtable_size()) {
105 if (Universe::is_bootstrapping()) {
106 // Someone is attempting to override java.lang.Object incorrectly on the
107 // bootclasspath. The JVM cannot recover from this error including throwing
108 // an exception
109 vm_exit_during_initialization("Incompatible definition of java.lang.Object");
110 } else {
111 // Someone is attempting to redefine java.lang.Object incorrectly. The
112 // only way this should happen is from
113 // SystemDictionary::resolve_from_stream(), which will detect this later
114 // and throw a security exception. So don't assert here to let
115 // the exception occur.
116 vtable_length = Universe::base_vtable_size();
117 }
118 }
119 assert(vtable_length % vtableEntry::size() == 0, "bad vtable length");
120 assert(vtable_length >= Universe::base_vtable_size(), "vtable too small");
121
122 *vtable_length_ret = vtable_length;
123 }
124
125 int klassVtable::index_of(Method* m, int len) const {
126 assert(m->has_vtable_index(), "do not ask this of non-vtable methods");
127 return m->vtable_index();
128 }
129
130 // Copy super class's vtable to the first part (prefix) of this class's vtable,
131 // and return the number of entries copied. Expects that 'super' is the Java
132 // super class (arrays can have "array" super classes that must be skipped).
133 int klassVtable::initialize_from_super(Klass* super) {
134 if (super == NULL) {
135 return 0;
136 } else if (is_preinitialized_vtable()) {
137 // A shared class' vtable is preinitialized at dump time. No need to copy
138 // methods from super class for shared class, as that was already done
139 // during archiving time. However, if Jvmti has redefined a class,
140 // copy super class's vtable in case the super class has changed.
141 return super->vtable().length();
142 } else {
143 // copy methods from superKlass
144 klassVtable superVtable = super->vtable();
145 assert(superVtable.length() <= _length, "vtable too short");
146 #ifdef ASSERT
147 superVtable.verify(tty, true);
148 #endif
149 superVtable.copy_vtable_to(table());
150 if (log_develop_is_enabled(Trace, vtables)) {
151 ResourceMark rm;
152 log_develop_trace(vtables)("copy vtable from %s to %s size %d",
153 super->internal_name(), klass()->internal_name(),
154 _length);
155 }
156 return superVtable.length();
157 }
158 }
159
160 //
161 // Revised lookup semantics introduced 1.3 (Kestrel beta)
162 void klassVtable::initialize_vtable(bool checkconstraints, TRAPS) {
163
164 // Note: Arrays can have intermediate array supers. Use java_super to skip them.
165 Klass* super = _klass->java_super();
166 int nofNewEntries = 0;
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);
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.
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(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;
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 // Static and <init> methods are never in
389 if (target_method()->is_static() || target_method()->name() == vmSymbols::object_initializer_name()) {
390 return false;
391 }
392
393 if (target_method->is_final_method(klass->access_flags())) {
394 // a final method never needs a new entry; final methods can be statically
395 // resolved and they have to be present in the vtable only if they override
396 // a super's method, in which case they re-use its entry
397 allocate_new = false;
398 } else if (klass->is_interface()) {
399 allocate_new = false; // see note below in needs_new_vtable_entry
400 // An interface never allocates new vtable slots, only inherits old ones.
401 // This method will either be assigned its own itable index later,
402 // or be assigned an inherited vtable index in the loop below.
403 // default methods inherited by classes store their vtable indices
404 // in the inheritor's default_vtable_indices.
405 // default methods inherited by interfaces may already have a
406 // valid itable index, if so, don't change it.
407 // Overpass methods in an interface will be assigned an itable index later
408 // by an inheriting class.
409 // Private interface methods have no itable index and are always invoked nonvirtually,
410 // so they retain their nonvirtual_vtable_index value, and therefore can_be_statically_bound()
411 // will return true.
412 if ((!is_default || !target_method()->has_itable_index()) && !target_method()->is_private()) {
413 target_method()->set_vtable_index(Method::pending_itable_index);
414 }
415 }
416
417 // we need a new entry if there is no superclass
418 Klass* super = klass->super();
419 if (super == NULL) {
420 return allocate_new;
421 }
422
423 // private methods in classes always have a new entry in the vtable
424 // specification interpretation since classic has
425 // private methods not overriding
426 // JDK8 adds private methods in interfaces which require invokespecial
427 if (target_method()->is_private()) {
428 return allocate_new;
429 }
430
431 // search through the vtable and update overridden entries
432 // Since check_signature_loaders acquires SystemDictionary_lock
433 // which can block for gc, once we are in this loop, use handles
434 // For classfiles built with >= jdk7, we now look for transitive overrides
435
436 Symbol* name = target_method()->name();
437 Symbol* signature = target_method()->signature();
438
439 Klass* target_klass = target_method()->method_holder();
440 if (target_klass == NULL) {
441 target_klass = _klass;
442 }
443
444 Handle target_loader(THREAD, target_klass->class_loader());
445
446 Symbol* target_classname = target_klass->name();
447 for(int i = 0; i < super_vtable_len; i++) {
448 Method* super_method;
449 if (is_preinitialized_vtable()) {
450 // If this is a shared class, the vtable is already in the final state (fully
451 // initialized). Need to look at the super's vtable.
452 klassVtable superVtable = super->vtable();
453 super_method = superVtable.method_at(i);
454 } else {
455 super_method = method_at(i);
456 }
457 // Check if method name matches
458 if (super_method->name() == name && super_method->signature() == signature) {
459
460 // get super_klass for method_holder for the found method
461 InstanceKlass* super_klass = super_method->method_holder();
462
463 // Whether the method is being overridden
464 bool overrides = false;
465
466 // private methods are also never overridden
467 if (!super_method->is_private() &&
468 (is_default
469 || ((super_klass->is_override(super_method, target_loader, target_classname, THREAD))
470 || ((klass->major_version() >= VTABLE_TRANSITIVE_OVERRIDE_VERSION)
471 && ((super_klass = find_transitive_override(super_klass,
472 target_method, i, target_loader,
473 target_classname, THREAD))
474 != (InstanceKlass*)NULL)))))
475 {
476 // Package private methods always need a new entry to root their own
477 // overriding. They may also override other methods.
478 if (!target_method()->is_package_private()) {
479 allocate_new = false;
480 }
481
482 // Do not check loader constraints for overpass methods because overpass
483 // methods are created by the jvm to throw exceptions.
484 if (checkconstraints && !target_method()->is_overpass()) {
485 // Override vtable entry if passes loader constraint check
486 // if loader constraint checking requested
487 // No need to visit his super, since he and his super
488 // have already made any needed loader constraints.
489 // Since loader constraints are transitive, it is enough
490 // to link to the first super, and we get all the others.
491 Handle super_loader(THREAD, super_klass->class_loader());
492
493 if (target_loader() != super_loader()) {
494 ResourceMark rm(THREAD);
495 Symbol* failed_type_symbol =
496 SystemDictionary::check_signature_loaders(signature, target_loader,
497 super_loader, true,
498 CHECK_(false));
499 if (failed_type_symbol != NULL) {
500 const char* msg = "loader constraint violation for class %s: when selecting "
501 "overriding method \"%s\" the class loader (instance of %s) of the "
502 "selected method's type %s, and the class loader (instance of %s) for its super "
503 "type %s have different Class objects for the type %s used in the signature";
504 char* curr_class = klass->name()->as_C_string();
505 char* sig = target_method()->name_and_sig_as_C_string();
506 const char* loader1 = SystemDictionary::loader_name(target_loader());
507 char* sel_class = target_klass->name()->as_C_string();
508 const char* loader2 = SystemDictionary::loader_name(super_loader());
509 char* super_class = super_klass->name()->as_C_string();
510 char* failed_type_name = failed_type_symbol->as_C_string();
511 size_t buflen = strlen(msg) + strlen(curr_class) + strlen(sig) +
512 strlen(loader1) + strlen(sel_class) + strlen(loader2) +
513 strlen(super_class) + strlen(failed_type_name);
514 char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen);
515 jio_snprintf(buf, buflen, msg, curr_class, sig, loader1, sel_class, loader2,
516 super_class, failed_type_name);
517 THROW_MSG_(vmSymbols::java_lang_LinkageError(), buf, false);
518 }
519 }
520 }
521
522 put_method_at(target_method(), i);
523 overrides = true;
524 if (!is_default) {
525 target_method()->set_vtable_index(i);
526 } else {
527 if (def_vtable_indices != NULL) {
528 if (is_preinitialized_vtable()) {
529 // At runtime initialize_vtable is rerun as part of link_class_impl()
530 // for a shared class loaded by the non-boot loader.
531 // The dumptime vtable index should be the same as the runtime index.
532 assert(def_vtable_indices->at(default_index) == i,
533 "dump time vtable index is different from runtime index");
534 } else {
535 def_vtable_indices->at_put(default_index, i);
536 }
537 }
538 assert(super_method->is_default_method() || super_method->is_overpass()
539 || super_method->is_abstract(), "default override error");
540 }
541 } else {
542 overrides = false;
543 }
544 log_vtables(i, overrides, target_method, target_klass, super_method, THREAD);
545 }
546 }
547 return allocate_new;
548 }
549
550 void klassVtable::put_method_at(Method* m, int index) {
551 if (is_preinitialized_vtable()) {
552 // At runtime initialize_vtable is rerun as part of link_class_impl()
553 // for shared class loaded by the non-boot loader to obtain the loader
554 // constraints based on the runtime classloaders' context. The dumptime
555 // method at the vtable index should be the same as the runtime method.
556 assert(table()[index].method() == m,
557 "archived method is different from the runtime method");
558 } else {
559 if (log_develop_is_enabled(Trace, vtables)) {
560 ResourceMark rm;
561 LogTarget(Trace, vtables) lt;
562 LogStream ls(lt);
563 const char* sig = (m != NULL) ? m->name_and_sig_as_C_string() : "<NULL>";
564 ls.print("adding %s at index %d, flags: ", sig, index);
565 if (m != NULL) {
566 m->print_linkage_flags(&ls);
567 }
568 ls.cr();
569 }
570 table()[index].set(m);
571 }
572 }
573
574 // Find out if a method "m" with superclass "super", loader "classloader" and
575 // name "classname" needs a new vtable entry. Let P be a class package defined
576 // by "classloader" and "classname".
577 // NOTE: The logic used here is very similar to the one used for computing
578 // the vtables indices for a method. We cannot directly use that function because,
579 // we allocate the InstanceKlass at load time, and that requires that the
580 // superclass has been loaded.
581 // However, the vtable entries are filled in at link time, and therefore
582 // the superclass' vtable may not yet have been filled in.
583 bool klassVtable::needs_new_vtable_entry(const methodHandle& target_method,
584 const Klass* super,
585 Handle classloader,
586 Symbol* classname,
587 AccessFlags class_flags,
588 u2 major_version,
589 TRAPS) {
590 if (class_flags.is_interface()) {
591 // Interfaces do not use vtables, except for java.lang.Object methods,
592 // so there is no point to assigning
593 // a vtable index to any of their local methods. If we refrain from doing this,
594 // we can use Method::_vtable_index to hold the itable index
595 return false;
596 }
597
598 if (target_method->is_final_method(class_flags) ||
599 // a final method never needs a new entry; final methods can be statically
600 // resolved and they have to be present in the vtable only if they override
601 // a super's method, in which case they re-use its entry
602 (target_method()->is_static()) ||
603 // static methods don't need to be in vtable
604 (target_method()->name() == vmSymbols::object_initializer_name())
605 // <init> is never called dynamically-bound
606 ) {
607 return false;
608 }
609
610 // Concrete interface methods do not need new entries, they override
611 // abstract method entries using default inheritance rules
612 if (target_method()->method_holder() != NULL &&
613 target_method()->method_holder()->is_interface() &&
614 !target_method()->is_abstract()) {
615 assert(target_method()->is_default_method() || target_method()->is_private(),
616 "unexpected interface method type");
617 return false;
618 }
619
620 // we need a new entry if there is no superclass
621 if (super == NULL) {
622 return true;
623 }
624
625 // private methods in classes always have a new entry in the vtable.
626 // Specification interpretation since classic has private methods not overriding.
627 if (target_method()->is_private()) {
628 return true;
629 }
630
631 // Package private methods always need a new entry to root their own
632 // overriding. This allows transitive overriding to work.
633 if (target_method()->is_package_private()) {
634 return true;
635 }
636
637 // search through the super class hierarchy to see if we need
638 // a new entry
639 ResourceMark rm;
640 Symbol* name = target_method()->name();
641 Symbol* signature = target_method()->signature();
642 const Klass* k = super;
643 Method* super_method = NULL;
644 InstanceKlass *holder = NULL;
645 Method* recheck_method = NULL;
646 while (k != NULL) {
647 // lookup through the hierarchy for a method with matching name and sign.
648 super_method = InstanceKlass::cast(k)->lookup_method(name, signature);
649 if (super_method == NULL) {
650 break; // we still have to search for a matching miranda method
651 }
652 // get the class holding the matching method
653 // make sure you use that class for is_override
654 InstanceKlass* superk = super_method->method_holder();
655 // we want only instance method matches
656 // pretend private methods are not in the super vtable
657 // since we do override around them: e.g. a.m pub/b.m private/c.m pub,
658 // ignore private, c.m pub does override a.m pub
659 // For classes that were not javac'd together, we also do transitive overriding around
660 // methods that have less accessibility
661 if ((!super_method->is_static()) &&
662 (!super_method->is_private())) {
663 if (superk->is_override(super_method, classloader, classname, THREAD)) {
664 return false;
665 // else keep looking for transitive overrides
666 }
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 the target method is public or protected it may have a matching
678 // miranda method in the super, whose entry it should re-use.
679 // Actually, to handle cases that javac would not generate, we need
680 // this check for all access permissions.
681 const InstanceKlass *sk = InstanceKlass::cast(super);
682 if (sk->has_miranda_methods()) {
683 if (sk->lookup_method_in_all_interfaces(name, signature, Klass::find_defaults) != NULL) {
684 return false; // found a matching miranda; we do not need a new entry
685 }
686 }
687 return true; // found no match; we need a new entry
688 }
689
690 // Support for miranda methods
691
692 // get the vtable index of a miranda method with matching "name" and "signature"
693 int klassVtable::index_of_miranda(Symbol* name, Symbol* signature) {
694 // search from the bottom, might be faster
695 for (int i = (length() - 1); i >= 0; i--) {
696 Method* m = table()[i].method();
697 if (is_miranda_entry_at(i) &&
698 m->name() == name && m->signature() == signature) {
699 return i;
700 }
701 }
702 return Method::invalid_vtable_index;
703 }
704
705 // check if an entry at an index is miranda
706 // requires that method m at entry be declared ("held") by an interface.
707 bool klassVtable::is_miranda_entry_at(int i) {
708 Method* m = method_at(i);
709 Klass* method_holder = m->method_holder();
710 InstanceKlass *mhk = InstanceKlass::cast(method_holder);
711
712 // miranda methods are public abstract instance interface methods in a class's vtable
713 if (mhk->is_interface()) {
714 assert(m->is_public(), "should be public");
715 assert(ik()->implements_interface(method_holder) , "this class should implement the interface");
716 if (is_miranda(m, ik()->methods(), ik()->default_methods(), ik()->super())) {
717 return true;
718 }
719 }
720 return false;
721 }
722
723 // Check if a method is a miranda method, given a class's methods array,
724 // its default_method table and its super class.
725 // "Miranda" means an abstract non-private method that would not be
726 // overridden for the local class.
727 // A "miranda" method should only include non-private interface
728 // instance methods, i.e. not private methods, not static methods,
729 // not default methods (concrete interface methods), not overpass methods.
730 // If a given class already has a local (including overpass) method, a
731 // default method, or any of its superclasses has the same which would have
732 // overridden an abstract method, then this is not a miranda method.
733 //
734 // Miranda methods are checked multiple times.
735 // Pass 1: during class load/class file parsing: before vtable size calculation:
736 // include superinterface abstract and default methods (non-private instance).
737 // We include potential default methods to give them space in the vtable.
738 // During the first run, the current instanceKlass has not yet been
739 // created, the superclasses and superinterfaces do have instanceKlasses
740 // but may not have vtables, the default_methods list is empty, no overpasses.
741 // This is seen by default method creation.
742 //
743 // Pass 2: recalculated during vtable initialization: only include abstract methods.
744 // The goal of pass 2 is to walk through the superinterfaces to see if any of
745 // the superinterface methods (which were all abstract pre-default methods)
746 // need to be added to the vtable.
747 // With the addition of default methods, we have three new challenges:
748 // overpasses, static interface methods and private interface methods.
749 // Static and private interface methods do not get added to the vtable and
750 // are not seen by the method resolution process, so we skip those.
751 // Overpass methods are already in the vtable, so vtable lookup will
752 // find them and we don't need to add a miranda method to the end of
753 // the vtable. So we look for overpass methods and if they are found we
754 // return false. Note that we inherit our superclasses vtable, so
755 // the superclass' search also needs to use find_overpass so that if
756 // one is found we return false.
757 // False means - we don't need a miranda method added to the vtable.
758 //
759 // During the second run, default_methods is set up, so concrete methods from
760 // superinterfaces with matching names/signatures to default_methods are already
761 // in the default_methods list and do not need to be appended to the vtable
762 // as mirandas. Abstract methods may already have been handled via
763 // overpasses - either local or superclass overpasses, which may be
764 // in the vtable already.
765 //
766 // Pass 3: They are also checked by link resolution and selection,
767 // for invocation on a method (not interface method) reference that
768 // resolves to a method with an interface as its method_holder.
769 // Used as part of walking from the bottom of the vtable to find
770 // the vtable index for the miranda method.
771 //
772 // Part of the Miranda Rights in the US mean that if you do not have
773 // an attorney one will be appointed for you.
774 bool klassVtable::is_miranda(Method* m, Array<Method*>* class_methods,
775 Array<Method*>* default_methods, const Klass* super) {
776 if (m->is_static() || m->is_private() || m->is_overpass()) {
777 return false;
778 }
779 Symbol* name = m->name();
780 Symbol* signature = m->signature();
781
782 // First look in local methods to see if already covered
783 if (InstanceKlass::find_local_method(class_methods, name, signature,
784 Klass::find_overpass, Klass::skip_static, Klass::skip_private) != NULL)
785 {
786 return false;
787 }
788
789 // Check local default methods
790 if ((default_methods != NULL) &&
791 (InstanceKlass::find_method(default_methods, name, signature) != NULL))
792 {
793 return false;
794 }
795
796 // Iterate on all superclasses, which should be InstanceKlasses.
797 // Note that we explicitly look for overpasses at each level.
798 // Overpasses may or may not exist for supers for pass 1,
799 // they should have been created for pass 2 and later.
800
801 for (const Klass* cursuper = super; cursuper != NULL; cursuper = cursuper->super())
802 {
803 if (InstanceKlass::cast(cursuper)->find_local_method(name, signature,
804 Klass::find_overpass, Klass::skip_static, Klass::skip_private) != NULL) {
805 return false;
806 }
807 }
808
809 return true;
810 }
811
812 // Scans current_interface_methods for miranda methods that do not
813 // already appear in new_mirandas, or default methods, and are also not defined-and-non-private
814 // in super (superclass). These mirandas are added to all_mirandas if it is
815 // not null; in addition, those that are not duplicates of miranda methods
816 // inherited by super from its interfaces are added to new_mirandas.
817 // Thus, new_mirandas will be the set of mirandas that this class introduces,
818 // all_mirandas will be the set of all mirandas applicable to this class
819 // including all defined in superclasses.
820 void klassVtable::add_new_mirandas_to_lists(
821 GrowableArray<Method*>* new_mirandas, GrowableArray<Method*>* all_mirandas,
822 Array<Method*>* current_interface_methods, Array<Method*>* class_methods,
823 Array<Method*>* default_methods, const Klass* super) {
824
825 // iterate thru the current interface's method to see if it a miranda
826 int num_methods = current_interface_methods->length();
827 for (int i = 0; i < num_methods; i++) {
828 Method* im = current_interface_methods->at(i);
829 bool is_duplicate = false;
830 int num_of_current_mirandas = new_mirandas->length();
831 // check for duplicate mirandas in different interfaces we implement
832 for (int j = 0; j < num_of_current_mirandas; j++) {
833 Method* miranda = new_mirandas->at(j);
834 if ((im->name() == miranda->name()) &&
835 (im->signature() == miranda->signature())) {
836 is_duplicate = true;
837 break;
838 }
839 }
840
841 if (!is_duplicate) { // we don't want duplicate miranda entries in the vtable
842 if (is_miranda(im, class_methods, default_methods, super)) { // is it a miranda at all?
843 const InstanceKlass *sk = InstanceKlass::cast(super);
844 // check if it is a duplicate of a super's miranda
845 if (sk->lookup_method_in_all_interfaces(im->name(), im->signature(), Klass::find_defaults) == NULL) {
846 new_mirandas->append(im);
847 }
848 if (all_mirandas != NULL) {
849 all_mirandas->append(im);
850 }
851 }
852 }
853 }
854 }
855
856 void klassVtable::get_mirandas(GrowableArray<Method*>* new_mirandas,
857 GrowableArray<Method*>* all_mirandas,
858 const Klass* super,
859 Array<Method*>* class_methods,
860 Array<Method*>* default_methods,
861 Array<Klass*>* local_interfaces) {
862 assert((new_mirandas->length() == 0) , "current mirandas must be 0");
863
864 // iterate thru the local interfaces looking for a miranda
865 int num_local_ifs = local_interfaces->length();
866 for (int i = 0; i < num_local_ifs; i++) {
867 InstanceKlass *ik = InstanceKlass::cast(local_interfaces->at(i));
868 add_new_mirandas_to_lists(new_mirandas, all_mirandas,
869 ik->methods(), class_methods,
870 default_methods, super);
871 // iterate thru each local's super interfaces
872 Array<Klass*>* super_ifs = ik->transitive_interfaces();
873 int num_super_ifs = super_ifs->length();
874 for (int j = 0; j < num_super_ifs; j++) {
875 InstanceKlass *sik = InstanceKlass::cast(super_ifs->at(j));
876 add_new_mirandas_to_lists(new_mirandas, all_mirandas,
877 sik->methods(), class_methods,
878 default_methods, super);
879 }
880 }
881 }
882
883 // Discover miranda methods ("miranda" = "interface abstract, no binding"),
884 // and append them into the vtable starting at index initialized,
885 // return the new value of initialized.
886 // Miranda methods use vtable entries, but do not get assigned a vtable_index
887 // The vtable_index is discovered by searching from the end of the vtable
888 int klassVtable::fill_in_mirandas(int initialized) {
889 GrowableArray<Method*> mirandas(20);
890 get_mirandas(&mirandas, NULL, ik()->super(), ik()->methods(),
891 ik()->default_methods(), ik()->local_interfaces());
892 for (int i = 0; i < mirandas.length(); i++) {
893 if (log_develop_is_enabled(Trace, vtables)) {
894 Method* meth = mirandas.at(i);
895 ResourceMark rm(Thread::current());
896 LogTarget(Trace, vtables) lt;
897 LogStream ls(lt);
898 if (meth != NULL) {
899 char* sig = meth->name_and_sig_as_C_string();
900 ls.print("fill in mirandas with %s index %d, flags: ",
901 sig, initialized);
902 meth->print_linkage_flags(&ls);
903 ls.cr();
904 }
905 }
906 put_method_at(mirandas.at(i), initialized);
907 ++initialized;
908 }
909 return initialized;
910 }
911
912 // Copy this class's vtable to the vtable beginning at start.
913 // Used to copy superclass vtable to prefix of subclass's vtable.
914 void klassVtable::copy_vtable_to(vtableEntry* start) {
915 Copy::disjoint_words((HeapWord*)table(), (HeapWord*)start, _length * vtableEntry::size());
916 }
917
918 #if INCLUDE_JVMTI
919 bool klassVtable::adjust_default_method(int vtable_index, Method* old_method, Method* new_method) {
920 // If old_method is default, find this vtable index in default_vtable_indices
921 // and replace that method in the _default_methods list
922 bool updated = false;
923
924 Array<Method*>* default_methods = ik()->default_methods();
925 if (default_methods != NULL) {
926 int len = default_methods->length();
927 for (int idx = 0; idx < len; idx++) {
928 if (vtable_index == ik()->default_vtable_indices()->at(idx)) {
929 if (default_methods->at(idx) == old_method) {
930 default_methods->at_put(idx, new_method);
931 updated = true;
932 }
933 break;
934 }
935 }
936 }
937 return updated;
938 }
939
940 // search the vtable for uses of either obsolete or EMCP methods
941 void klassVtable::adjust_method_entries(InstanceKlass* holder, bool * trace_name_printed) {
942 int prn_enabled = 0;
943 for (int index = 0; index < length(); index++) {
944 Method* old_method = unchecked_method_at(index);
945 if (old_method == NULL || old_method->method_holder() != holder || !old_method->is_old()) {
946 continue; // skip uninteresting entries
947 }
948 assert(!old_method->is_deleted(), "vtable methods may not be deleted");
949
950 Method* new_method = holder->method_with_idnum(old_method->orig_method_idnum());
951
952 assert(new_method != NULL, "method_with_idnum() should not be NULL");
953 assert(old_method != new_method, "sanity check");
954
955 put_method_at(new_method, index);
956 // For default methods, need to update the _default_methods array
957 // which can only have one method entry for a given signature
958 bool updated_default = false;
959 if (old_method->is_default_method()) {
960 updated_default = adjust_default_method(index, old_method, new_method);
961 }
962
963 if (log_is_enabled(Info, redefine, class, update)) {
964 ResourceMark rm;
965 if (!(*trace_name_printed)) {
966 log_info(redefine, class, update)
967 ("adjust: klassname=%s for methods from name=%s",
968 _klass->external_name(), old_method->method_holder()->external_name());
969 *trace_name_printed = true;
970 }
971 log_debug(redefine, class, update, vtables)
972 ("vtable method update: %s(%s), updated default = %s",
973 new_method->name()->as_C_string(), new_method->signature()->as_C_string(), updated_default ? "true" : "false");
974 }
975 }
976 }
977
978 // a vtable should never contain old or obsolete methods
979 bool klassVtable::check_no_old_or_obsolete_entries() {
980 for (int i = 0; i < length(); i++) {
981 Method* m = unchecked_method_at(i);
982 if (m != NULL &&
983 (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) {
984 return false;
985 }
986 }
987 return true;
988 }
989
990 void klassVtable::dump_vtable() {
991 tty->print_cr("vtable dump --");
992 for (int i = 0; i < length(); i++) {
993 Method* m = unchecked_method_at(i);
994 if (m != NULL) {
995 tty->print(" (%5d) ", i);
996 m->access_flags().print_on(tty);
997 if (m->is_default_method()) {
998 tty->print("default ");
999 }
1000 if (m->is_overpass()) {
1001 tty->print("overpass");
1002 }
1003 tty->print(" -- ");
1004 m->print_name(tty);
1005 tty->cr();
1006 }
1007 }
1008 }
1009 #endif // INCLUDE_JVMTI
1010
1011 // CDS/RedefineClasses support - clear vtables so they can be reinitialized
1012 void klassVtable::clear_vtable() {
1013 for (int i = 0; i < _length; i++) table()[i].clear();
1014 }
1015
1016 bool klassVtable::is_initialized() {
1017 return _length == 0 || table()[0].method() != NULL;
1018 }
1019
1020 //-----------------------------------------------------------------------------------------
1021 // Itable code
1022
1023 // Initialize a itableMethodEntry
1024 void itableMethodEntry::initialize(Method* m) {
1025 if (m == NULL) return;
1026
1027 #ifdef ASSERT
1028 if (MetaspaceShared::is_in_shared_space((void*)&_method) &&
1029 !MetaspaceShared::remapped_readwrite()) {
1030 // At runtime initialize_itable is rerun as part of link_class_impl()
1031 // for a shared class loaded by the non-boot loader.
1032 // The dumptime itable method entry should be the same as the runtime entry.
1033 assert(_method == m, "sanity");
1034 }
1035 #endif
1036 _method = m;
1037 }
1038
1039 klassItable::klassItable(InstanceKlass* klass) {
1040 _klass = klass;
1041
1042 if (klass->itable_length() > 0) {
1043 itableOffsetEntry* offset_entry = (itableOffsetEntry*)klass->start_of_itable();
1044 if (offset_entry != NULL && offset_entry->interface_klass() != NULL) { // Check that itable is initialized
1045 // First offset entry points to the first method_entry
1046 intptr_t* method_entry = (intptr_t *)(((address)klass) + offset_entry->offset());
1047 intptr_t* end = klass->end_of_itable();
1048
1049 _table_offset = (intptr_t*)offset_entry - (intptr_t*)klass;
1050 _size_offset_table = (method_entry - ((intptr_t*)offset_entry)) / itableOffsetEntry::size();
1051 _size_method_table = (end - method_entry) / itableMethodEntry::size();
1052 assert(_table_offset >= 0 && _size_offset_table >= 0 && _size_method_table >= 0, "wrong computation");
1053 return;
1054 }
1055 }
1056
1057 // The length of the itable was either zero, or it has not yet been initialized.
1058 _table_offset = 0;
1059 _size_offset_table = 0;
1060 _size_method_table = 0;
1061 }
1062
1063 static int initialize_count = 0;
1064
1065 // Initialization
1066 void klassItable::initialize_itable(bool checkconstraints, TRAPS) {
1067 if (_klass->is_interface()) {
1068 // This needs to go after vtable indices are assigned but
1069 // before implementors need to know the number of itable indices.
1070 assign_itable_indices_for_interface(_klass);
1071 }
1072
1073 // Cannot be setup doing bootstrapping, interfaces don't have
1074 // itables, and klass with only ones entry have empty itables
1075 if (Universe::is_bootstrapping() ||
1076 _klass->is_interface() ||
1077 _klass->itable_length() == itableOffsetEntry::size()) return;
1078
1079 // There's alway an extra itable entry so we can null-terminate it.
1080 guarantee(size_offset_table() >= 1, "too small");
1081 int num_interfaces = size_offset_table() - 1;
1082 if (num_interfaces > 0) {
1083 log_develop_debug(itables)("%3d: Initializing itables for %s", ++initialize_count,
1084 _klass->name()->as_C_string());
1085
1086
1087 // Iterate through all interfaces
1088 int i;
1089 for(i = 0; i < num_interfaces; i++) {
1090 itableOffsetEntry* ioe = offset_entry(i);
1091 HandleMark hm(THREAD);
1092 Klass* interf = ioe->interface_klass();
1093 assert(interf != NULL && ioe->offset() != 0, "bad offset entry in itable");
1094 initialize_itable_for_interface(ioe->offset(), interf, checkconstraints, CHECK);
1095 }
1096
1097 }
1098 // Check that the last entry is empty
1099 itableOffsetEntry* ioe = offset_entry(size_offset_table() - 1);
1100 guarantee(ioe->interface_klass() == NULL && ioe->offset() == 0, "terminator entry missing");
1101 }
1102
1103
1104 inline bool interface_method_needs_itable_index(Method* m) {
1105 if (m->is_static()) return false; // e.g., Stream.empty
1106 if (m->is_initializer()) return false; // <init> or <clinit>
1107 if (m->is_private()) return false; // requires invokeSpecial
1108 // If an interface redeclares a method from java.lang.Object,
1109 // it should already have a vtable index, don't touch it.
1110 // e.g., CharSequence.toString (from initialize_vtable)
1111 // if (m->has_vtable_index()) return false; // NO!
1112 return true;
1113 }
1114
1115 int klassItable::assign_itable_indices_for_interface(Klass* klass) {
1116 // an interface does not have an itable, but its methods need to be numbered
1117 log_develop_debug(itables)("%3d: Initializing itable indices for interface %s",
1118 ++initialize_count, klass->name()->as_C_string());
1119 Array<Method*>* methods = InstanceKlass::cast(klass)->methods();
1120 int nof_methods = methods->length();
1121 int ime_num = 0;
1122 for (int i = 0; i < nof_methods; i++) {
1123 Method* m = methods->at(i);
1124 if (interface_method_needs_itable_index(m)) {
1125 assert(!m->is_final_method(), "no final interface methods");
1126 // If m is already assigned a vtable index, do not disturb it.
1127 if (log_develop_is_enabled(Trace, itables)) {
1128 ResourceMark rm;
1129 LogTarget(Trace, itables) lt;
1130 LogStream ls(lt);
1131 assert(m != NULL, "methods can never be null");
1132 const char* sig = m->name_and_sig_as_C_string();
1133 if (m->has_vtable_index()) {
1134 ls.print("vtable index %d for method: %s, flags: ", m->vtable_index(), sig);
1135 } else {
1136 ls.print("itable index %d for method: %s, flags: ", ime_num, sig);
1137 }
1138 m->print_linkage_flags(&ls);
1139 ls.cr();
1140 }
1141 if (!m->has_vtable_index()) {
1142 // A shared method could have an initialized itable_index that
1143 // is < 0.
1144 assert(m->vtable_index() == Method::pending_itable_index ||
1145 m->is_shared(),
1146 "set by initialize_vtable");
1147 m->set_itable_index(ime_num);
1148 // Progress to next itable entry
1149 ime_num++;
1150 }
1151 }
1152 }
1153 assert(ime_num == method_count_for_interface(klass), "proper sizing");
1154 return ime_num;
1155 }
1156
1157 int klassItable::method_count_for_interface(Klass* interf) {
1158 assert(interf->is_instance_klass(), "must be");
1159 assert(interf->is_interface(), "must be");
1160 Array<Method*>* methods = InstanceKlass::cast(interf)->methods();
1161 int nof_methods = methods->length();
1162 int length = 0;
1163 while (nof_methods > 0) {
1164 Method* m = methods->at(nof_methods-1);
1165 if (m->has_itable_index()) {
1166 length = m->itable_index() + 1;
1167 break;
1168 }
1169 nof_methods -= 1;
1170 }
1171 #ifdef ASSERT
1172 int nof_methods_copy = nof_methods;
1173 while (nof_methods_copy > 0) {
1174 Method* mm = methods->at(--nof_methods_copy);
1175 assert(!mm->has_itable_index() || mm->itable_index() < length, "");
1176 }
1177 #endif //ASSERT
1178 // return the rightmost itable index, plus one; or 0 if no methods have
1179 // itable indices
1180 return length;
1181 }
1182
1183
1184 void klassItable::initialize_itable_for_interface(int method_table_offset, Klass* interf, bool checkconstraints, TRAPS) {
1185 Array<Method*>* methods = InstanceKlass::cast(interf)->methods();
1186 int nof_methods = methods->length();
1187 HandleMark hm;
1188 assert(nof_methods > 0, "at least one method must exist for interface to be in vtable");
1189 Handle interface_loader (THREAD, InstanceKlass::cast(interf)->class_loader());
1190
1191 int ime_count = method_count_for_interface(interf);
1192 for (int i = 0; i < nof_methods; i++) {
1193 Method* m = methods->at(i);
1194 methodHandle target;
1195 if (m->has_itable_index()) {
1196 // This search must match the runtime resolution, i.e. selection search for invokeinterface
1197 // to correctly enforce loader constraints for interface method inheritance
1198 target = LinkResolver::lookup_instance_method_in_klasses(_klass, m->name(), m->signature(), CHECK);
1199 }
1200 if (target == NULL || !target->is_public() || target->is_abstract() || target->is_overpass()) {
1201 assert(target == NULL || !target->is_overpass() || target->is_public(),
1202 "Non-public overpass method!");
1203 // Entry does not resolve. Leave it empty for AbstractMethodError or other error.
1204 if (!(target == NULL) && !target->is_public()) {
1205 // Stuff an IllegalAccessError throwing method in there instead.
1206 itableOffsetEntry::method_entry(_klass, method_table_offset)[m->itable_index()].
1207 initialize(Universe::throw_illegal_access_error());
1208 }
1209 } else {
1210 // Entry did resolve, check loader constraints before initializing
1211 // if checkconstraints requested
1212 if (checkconstraints) {
1213 Handle method_holder_loader (THREAD, target->method_holder()->class_loader());
1214 if (method_holder_loader() != interface_loader()) {
1215 ResourceMark rm(THREAD);
1216 Symbol* failed_type_symbol =
1217 SystemDictionary::check_signature_loaders(m->signature(),
1218 method_holder_loader,
1219 interface_loader,
1220 true, CHECK);
1221 if (failed_type_symbol != NULL) {
1222 const char* msg = "loader constraint violation in interface itable"
1223 " initialization for class %s: when selecting method \"%s\" the"
1224 " class loader (instance of %s) for super interface %s, and the class"
1225 " loader (instance of %s) of the selected method's type, %s have"
1226 " different Class objects for the type %s used in the signature";
1227 char* current = _klass->name()->as_C_string();
1228 char* sig = m->name_and_sig_as_C_string();
1229 const char* loader1 = SystemDictionary::loader_name(interface_loader());
1230 char* iface = InstanceKlass::cast(interf)->name()->as_C_string();
1231 const char* loader2 = SystemDictionary::loader_name(method_holder_loader());
1232 char* mclass = target()->method_holder()->name()->as_C_string();
1233 char* failed_type_name = failed_type_symbol->as_C_string();
1234 size_t buflen = strlen(msg) + strlen(current) + strlen(sig) +
1235 strlen(loader1) + strlen(iface) + strlen(loader2) + strlen(mclass) +
1236 strlen(failed_type_name);
1237 char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen);
1238 jio_snprintf(buf, buflen, msg, current, sig, loader1, iface,
1239 loader2, mclass, failed_type_name);
1240 THROW_MSG(vmSymbols::java_lang_LinkageError(), buf);
1241 }
1242 }
1243 }
1244
1245 // ime may have moved during GC so recalculate address
1246 int ime_num = m->itable_index();
1247 assert(ime_num < ime_count, "oob");
1248 itableOffsetEntry::method_entry(_klass, method_table_offset)[ime_num].initialize(target());
1249 if (log_develop_is_enabled(Trace, itables)) {
1250 ResourceMark rm(THREAD);
1251 if (target() != NULL) {
1252 LogTarget(Trace, itables) lt;
1253 LogStream ls(lt);
1254 char* sig = target()->name_and_sig_as_C_string();
1255 ls.print("interface: %s, ime_num: %d, target: %s, method_holder: %s ",
1256 interf->internal_name(), ime_num, sig,
1257 target()->method_holder()->internal_name());
1258 ls.print("target_method flags: ");
1259 target()->print_linkage_flags(&ls);
1260 ls.cr();
1261 }
1262 }
1263 }
1264 }
1265 }
1266
1267 #if INCLUDE_JVMTI
1268 // search the itable for uses of either obsolete or EMCP methods
1269 void klassItable::adjust_method_entries(InstanceKlass* holder, bool * trace_name_printed) {
1270
1271 itableMethodEntry* ime = method_entry(0);
1272 for (int i = 0; i < _size_method_table; i++, ime++) {
1273 Method* old_method = ime->method();
1274 if (old_method == NULL || old_method->method_holder() != holder || !old_method->is_old()) {
1275 continue; // skip uninteresting entries
1276 }
1277 assert(!old_method->is_deleted(), "itable methods may not be deleted");
1278
1279 Method* new_method = holder->method_with_idnum(old_method->orig_method_idnum());
1280
1281 assert(new_method != NULL, "method_with_idnum() should not be NULL");
1282 assert(old_method != new_method, "sanity check");
1283
1284 ime->initialize(new_method);
1285
1286 if (log_is_enabled(Info, redefine, class, update)) {
1287 ResourceMark rm;
1288 if (!(*trace_name_printed)) {
1289 log_info(redefine, class, update)("adjust: name=%s", old_method->method_holder()->external_name());
1290 *trace_name_printed = true;
1291 }
1292 log_trace(redefine, class, update, itables)
1293 ("itable method update: %s(%s)", new_method->name()->as_C_string(), new_method->signature()->as_C_string());
1294 }
1295 }
1296 }
1297
1298 // an itable should never contain old or obsolete methods
1299 bool klassItable::check_no_old_or_obsolete_entries() {
1300 itableMethodEntry* ime = method_entry(0);
1301 for (int i = 0; i < _size_method_table; i++) {
1302 Method* m = ime->method();
1303 if (m != NULL &&
1304 (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) {
1305 return false;
1306 }
1307 ime++;
1308 }
1309 return true;
1310 }
1311
1312 void klassItable::dump_itable() {
1313 itableMethodEntry* ime = method_entry(0);
1314 tty->print_cr("itable dump --");
1315 for (int i = 0; i < _size_method_table; i++) {
1316 Method* m = ime->method();
1317 if (m != NULL) {
1318 tty->print(" (%5d) ", i);
1319 m->access_flags().print_on(tty);
1320 if (m->is_default_method()) {
1321 tty->print("default ");
1322 }
1323 tty->print(" -- ");
1324 m->print_name(tty);
1325 tty->cr();
1326 }
1327 ime++;
1328 }
1329 }
1330 #endif // INCLUDE_JVMTI
1331
1332 // Setup
1333 class InterfaceVisiterClosure : public StackObj {
1334 public:
1335 virtual void doit(Klass* intf, int method_count) = 0;
1336 };
1337
1338 // Visit all interfaces with at least one itable method
1339 void visit_all_interfaces(Array<Klass*>* transitive_intf, InterfaceVisiterClosure *blk) {
1340 // Handle array argument
1341 for(int i = 0; i < transitive_intf->length(); i++) {
1342 Klass* intf = transitive_intf->at(i);
1343 assert(intf->is_interface(), "sanity check");
1344
1345 // Find no. of itable methods
1346 int method_count = 0;
1347 // method_count = klassItable::method_count_for_interface(intf);
1348 Array<Method*>* methods = InstanceKlass::cast(intf)->methods();
1349 if (methods->length() > 0) {
1350 for (int i = methods->length(); --i >= 0; ) {
1351 if (interface_method_needs_itable_index(methods->at(i))) {
1352 method_count++;
1353 }
1354 }
1355 }
1356
1357 // Only count interfaces with at least one method
1358 if (method_count > 0) {
1359 blk->doit(intf, method_count);
1360 }
1361 }
1362 }
1363
1364 class CountInterfacesClosure : public InterfaceVisiterClosure {
1365 private:
1366 int _nof_methods;
1367 int _nof_interfaces;
1368 public:
1369 CountInterfacesClosure() { _nof_methods = 0; _nof_interfaces = 0; }
1370
1371 int nof_methods() const { return _nof_methods; }
1372 int nof_interfaces() const { return _nof_interfaces; }
1373
1374 void doit(Klass* intf, int method_count) { _nof_methods += method_count; _nof_interfaces++; }
1375 };
1376
1377 class SetupItableClosure : public InterfaceVisiterClosure {
1378 private:
1379 itableOffsetEntry* _offset_entry;
1380 itableMethodEntry* _method_entry;
1381 address _klass_begin;
1382 public:
1383 SetupItableClosure(address klass_begin, itableOffsetEntry* offset_entry, itableMethodEntry* method_entry) {
1384 _klass_begin = klass_begin;
1385 _offset_entry = offset_entry;
1386 _method_entry = method_entry;
1387 }
1388
1389 itableMethodEntry* method_entry() const { return _method_entry; }
1390
1391 void doit(Klass* intf, int method_count) {
1392 int offset = ((address)_method_entry) - _klass_begin;
1393 _offset_entry->initialize(intf, offset);
1394 _offset_entry++;
1395 _method_entry += method_count;
1396 }
1397 };
1398
1399 int klassItable::compute_itable_size(Array<Klass*>* transitive_interfaces) {
1400 // Count no of interfaces and total number of interface methods
1401 CountInterfacesClosure cic;
1402 visit_all_interfaces(transitive_interfaces, &cic);
1403
1404 // There's alway an extra itable entry so we can null-terminate it.
1405 int itable_size = calc_itable_size(cic.nof_interfaces() + 1, cic.nof_methods());
1406
1407 // Statistics
1408 update_stats(itable_size * wordSize);
1409
1410 return itable_size;
1411 }
1412
1413
1414 // Fill out offset table and interface klasses into the itable space
1415 void klassItable::setup_itable_offset_table(InstanceKlass* klass) {
1416 if (klass->itable_length() == 0) return;
1417 assert(!klass->is_interface(), "Should have zero length itable");
1418
1419 // Count no of interfaces and total number of interface methods
1420 CountInterfacesClosure cic;
1421 visit_all_interfaces(klass->transitive_interfaces(), &cic);
1422 int nof_methods = cic.nof_methods();
1423 int nof_interfaces = cic.nof_interfaces();
1424
1425 // Add one extra entry so we can null-terminate the table
1426 nof_interfaces++;
1427
1428 assert(compute_itable_size(klass->transitive_interfaces()) ==
1429 calc_itable_size(nof_interfaces, nof_methods),
1430 "mismatch calculation of itable size");
1431
1432 // Fill-out offset table
1433 itableOffsetEntry* ioe = (itableOffsetEntry*)klass->start_of_itable();
1434 itableMethodEntry* ime = (itableMethodEntry*)(ioe + nof_interfaces);
1435 intptr_t* end = klass->end_of_itable();
1436 assert((oop*)(ime + nof_methods) <= (oop*)klass->start_of_nonstatic_oop_maps(), "wrong offset calculation (1)");
1437 assert((oop*)(end) == (oop*)(ime + nof_methods), "wrong offset calculation (2)");
1438
1439 // Visit all interfaces and initialize itable offset table
1440 SetupItableClosure sic((address)klass, ioe, ime);
1441 visit_all_interfaces(klass->transitive_interfaces(), &sic);
1442
1443 #ifdef ASSERT
1444 ime = sic.method_entry();
1445 oop* v = (oop*) klass->end_of_itable();
1446 assert( (oop*)(ime) == v, "wrong offset calculation (2)");
1447 #endif
1448 }
1449
1450
1451 // inverse to itable_index
1452 Method* klassItable::method_for_itable_index(Klass* intf, int itable_index) {
1453 assert(InstanceKlass::cast(intf)->is_interface(), "sanity check");
1454 assert(intf->verify_itable_index(itable_index), "");
1455 Array<Method*>* methods = InstanceKlass::cast(intf)->methods();
1456
1457 if (itable_index < 0 || itable_index >= method_count_for_interface(intf))
1458 return NULL; // help caller defend against bad indices
1459
1460 int index = itable_index;
1461 Method* m = methods->at(index);
1462 int index2 = -1;
1463 while (!m->has_itable_index() ||
1464 (index2 = m->itable_index()) != itable_index) {
1465 assert(index2 < itable_index, "monotonic");
1466 if (++index == methods->length())
1467 return NULL;
1468 m = methods->at(index);
1469 }
1470 assert(m->itable_index() == itable_index, "correct inverse");
1471
1472 return m;
1473 }
1474
1475 void klassVtable::verify(outputStream* st, bool forced) {
1476 // make sure table is initialized
1477 if (!Universe::is_fully_initialized()) return;
1478 #ifndef PRODUCT
1479 // avoid redundant verifies
1480 if (!forced && _verify_count == Universe::verify_count()) return;
1481 _verify_count = Universe::verify_count();
1482 #endif
1483 oop* end_of_obj = (oop*)_klass + _klass->size();
1484 oop* end_of_vtable = (oop *)&table()[_length];
1485 if (end_of_vtable > end_of_obj) {
1486 fatal("klass %s: klass object too short (vtable extends beyond end)",
1487 _klass->internal_name());
1488 }
1489
1490 for (int i = 0; i < _length; i++) table()[i].verify(this, st);
1491 // verify consistency with superKlass vtable
1492 Klass* super = _klass->super();
1493 if (super != NULL) {
1494 InstanceKlass* sk = InstanceKlass::cast(super);
1495 klassVtable vt = sk->vtable();
1496 for (int i = 0; i < vt.length(); i++) {
1497 verify_against(st, &vt, i);
1498 }
1499 }
1500 }
1501
1502 void klassVtable::verify_against(outputStream* st, klassVtable* vt, int index) {
1503 vtableEntry* vte = &vt->table()[index];
1504 if (vte->method()->name() != table()[index].method()->name() ||
1505 vte->method()->signature() != table()[index].method()->signature()) {
1506 fatal("mismatched name/signature of vtable entries");
1507 }
1508 }
1509
1510 #ifndef PRODUCT
1511 void klassVtable::print() {
1512 ResourceMark rm;
1513 tty->print("klassVtable for klass %s (length %d):\n", _klass->internal_name(), length());
1514 for (int i = 0; i < length(); i++) {
1515 table()[i].print();
1516 tty->cr();
1517 }
1518 }
1519 #endif
1520
1521 void vtableEntry::verify(klassVtable* vt, outputStream* st) {
1522 NOT_PRODUCT(FlagSetting fs(IgnoreLockingAssertions, true));
1523 Klass* vtklass = vt->klass();
1524 if (vtklass->is_instance_klass() &&
1525 (InstanceKlass::cast(vtklass)->major_version() >= klassVtable::VTABLE_TRANSITIVE_OVERRIDE_VERSION)) {
1526 assert(method() != NULL, "must have set method");
1527 }
1528 if (method() != NULL) {
1529 method()->verify();
1530 // we sub_type, because it could be a miranda method
1531 if (!vtklass->is_subtype_of(method()->method_holder())) {
1532 #ifndef PRODUCT
1533 print();
1534 #endif
1535 fatal("vtableEntry " PTR_FORMAT ": method is from subclass", p2i(this));
1536 }
1537 }
1538 }
1539
1540 #ifndef PRODUCT
1541
1542 void vtableEntry::print() {
1543 ResourceMark rm;
1544 tty->print("vtableEntry %s: ", method()->name()->as_C_string());
1545 if (Verbose) {
1546 tty->print("m " PTR_FORMAT " ", p2i(method()));
1547 }
1548 }
1549
1550 class VtableStats : AllStatic {
1551 public:
1552 static int no_klasses; // # classes with vtables
1553 static int no_array_klasses; // # array classes
1554 static int no_instance_klasses; // # instanceKlasses
1555 static int sum_of_vtable_len; // total # of vtable entries
1556 static int sum_of_array_vtable_len; // total # of vtable entries in array klasses only
1557 static int fixed; // total fixed overhead in bytes
1558 static int filler; // overhead caused by filler bytes
1559 static int entries; // total bytes consumed by vtable entries
1560 static int array_entries; // total bytes consumed by array vtable entries
1561
1562 static void do_class(Klass* k) {
1563 Klass* kl = k;
1564 klassVtable vt = kl->vtable();
1565 no_klasses++;
1566 if (kl->is_instance_klass()) {
1567 no_instance_klasses++;
1568 kl->array_klasses_do(do_class);
1569 }
1570 if (kl->is_array_klass()) {
1571 no_array_klasses++;
1572 sum_of_array_vtable_len += vt.length();
1573 }
1574 sum_of_vtable_len += vt.length();
1575 }
1576
1577 static void compute() {
1578 ClassLoaderDataGraph::classes_do(do_class);
1579 fixed = no_klasses * oopSize; // vtable length
1580 // filler size is a conservative approximation
1581 filler = oopSize * (no_klasses - no_instance_klasses) * (sizeof(InstanceKlass) - sizeof(ArrayKlass) - 1);
1582 entries = sizeof(vtableEntry) * sum_of_vtable_len;
1583 array_entries = sizeof(vtableEntry) * sum_of_array_vtable_len;
1584 }
1585 };
1586
1587 int VtableStats::no_klasses = 0;
1588 int VtableStats::no_array_klasses = 0;
1589 int VtableStats::no_instance_klasses = 0;
1590 int VtableStats::sum_of_vtable_len = 0;
1591 int VtableStats::sum_of_array_vtable_len = 0;
1592 int VtableStats::fixed = 0;
1593 int VtableStats::filler = 0;
1594 int VtableStats::entries = 0;
1595 int VtableStats::array_entries = 0;
1596
1597 void klassVtable::print_statistics() {
1598 ResourceMark rm;
1599 HandleMark hm;
1600 VtableStats::compute();
1601 tty->print_cr("vtable statistics:");
1602 tty->print_cr("%6d classes (%d instance, %d array)", VtableStats::no_klasses, VtableStats::no_instance_klasses, VtableStats::no_array_klasses);
1603 int total = VtableStats::fixed + VtableStats::filler + VtableStats::entries;
1604 tty->print_cr("%6d bytes fixed overhead (refs + vtable object header)", VtableStats::fixed);
1605 tty->print_cr("%6d bytes filler overhead", VtableStats::filler);
1606 tty->print_cr("%6d bytes for vtable entries (%d for arrays)", VtableStats::entries, VtableStats::array_entries);
1607 tty->print_cr("%6d bytes total", total);
1608 }
1609
1610 int klassItable::_total_classes; // Total no. of classes with itables
1611 long klassItable::_total_size; // Total no. of bytes used for itables
1612
1613 void klassItable::print_statistics() {
1614 tty->print_cr("itable statistics:");
1615 tty->print_cr("%6d classes with itables", _total_classes);
1616 tty->print_cr("%6lu K uses for itables (average by class: %ld bytes)", _total_size / K, _total_size / _total_classes);
1617 }
1618
1619 #endif // PRODUCT