1 /*
2 * Copyright (c) 1997, 2016, 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 "classfile/systemDictionary.hpp"
27 #include "classfile/vmSymbols.hpp"
28 #include "gc/shared/gcLocker.hpp"
29 #include "logging/log.hpp"
30 #include "memory/metaspaceShared.hpp"
31 #include "memory/resourceArea.hpp"
32 #include "memory/universe.inline.hpp"
33 #include "oops/instanceKlass.hpp"
34 #include "oops/klassVtable.hpp"
35 #include "oops/method.hpp"
36 #include "oops/objArrayOop.hpp"
37 #include "oops/oop.inline.hpp"
38 #include "runtime/arguments.hpp"
39 #include "runtime/handles.inline.hpp"
40 #include "utilities/copy.hpp"
41
42 inline InstanceKlass* klassVtable::ik() const {
43 return InstanceKlass::cast(_klass());
44 }
45
46 bool klassVtable::is_preinitialized_vtable() {
47 return _klass->is_shared() && !MetaspaceShared::remapped_readwrite();
48 }
49
50
51 // this function computes the vtable size (including the size needed for miranda
52 // methods) and the number of miranda methods in this class.
53 // Note on Miranda methods: Let's say there is a class C that implements
54 // interface I, and none of C's superclasses implements I.
55 // Let's say there is an abstract method m in I that neither C
56 // nor any of its super classes implement (i.e there is no method of any access,
57 // with the same name and signature as m), then m is a Miranda method which is
58 // entered as a public abstract method in C's vtable. From then on it should
59 // treated as any other public method in C for method over-ride purposes.
60 void klassVtable::compute_vtable_size_and_num_mirandas(
61 int* vtable_length_ret, int* num_new_mirandas,
62 GrowableArray<Method*>* all_mirandas, const Klass* super,
63 Array<Method*>* methods, AccessFlags class_flags,
64 Handle classloader, Symbol* classname, Array<Klass*>* local_interfaces,
65 TRAPS) {
66 NoSafepointVerifier nsv;
67
68 // set up default result values
69 int vtable_length = 0;
70
71 // start off with super's vtable length
72 vtable_length = super == NULL ? 0 : super->vtable_length();
73
74 // go thru each method in the methods table to see if it needs a new entry
75 int len = methods->length();
76 for (int i = 0; i < len; i++) {
77 assert(methods->at(i)->is_method(), "must be a Method*");
78 methodHandle mh(THREAD, methods->at(i));
79
80 if (needs_new_vtable_entry(mh, super, classloader, classname, class_flags, THREAD)) {
81 vtable_length += vtableEntry::size(); // we need a new entry
82 }
83 }
84
85 GrowableArray<Method*> new_mirandas(20);
86 // compute the number of mirandas methods that must be added to the end
87 get_mirandas(&new_mirandas, all_mirandas, super, methods, NULL, local_interfaces);
88 *num_new_mirandas = new_mirandas.length();
89
90 // Interfaces do not need interface methods in their vtables
91 // This includes miranda methods and during later processing, default methods
92 if (!class_flags.is_interface()) {
93 vtable_length += *num_new_mirandas * vtableEntry::size();
94 }
95
96 if (Universe::is_bootstrapping() && vtable_length == 0) {
97 // array classes don't have their superclass set correctly during
98 // bootstrapping
99 vtable_length = Universe::base_vtable_size();
100 }
101
102 if (super == NULL && vtable_length != Universe::base_vtable_size()) {
103 if (Universe::is_bootstrapping()) {
104 // Someone is attempting to override java.lang.Object incorrectly on the
105 // bootclasspath. The JVM cannot recover from this error including throwing
106 // an exception
107 vm_exit_during_initialization("Incompatible definition of java.lang.Object");
108 } else {
109 // Someone is attempting to redefine java.lang.Object incorrectly. The
110 // only way this should happen is from
111 // SystemDictionary::resolve_from_stream(), which will detect this later
112 // and throw a security exception. So don't assert here to let
113 // the exception occur.
114 vtable_length = Universe::base_vtable_size();
115 }
116 }
117 assert(vtable_length % vtableEntry::size() == 0, "bad vtable length");
118 assert(vtable_length >= Universe::base_vtable_size(), "vtable too small");
119
120 *vtable_length_ret = vtable_length;
121 }
122
123 int klassVtable::index_of(Method* m, int len) const {
124 assert(m->has_vtable_index(), "do not ask this of non-vtable methods");
125 return m->vtable_index();
126 }
127
128 // Copy super class's vtable to the first part (prefix) of this class's vtable,
129 // and return the number of entries copied. Expects that 'super' is the Java
130 // super class (arrays can have "array" super classes that must be skipped).
131 int klassVtable::initialize_from_super(KlassHandle super) {
132 if (super.is_null()) {
133 return 0;
134 } else if (is_preinitialized_vtable()) {
135 // A shared class' vtable is preinitialized at dump time. No need to copy
136 // methods from super class for shared class, as that was already done
137 // during archiving time. However, if Jvmti has redefined a class,
138 // copy super class's vtable in case the super class has changed.
139 return super->vtable()->length();
140 } else {
141 // copy methods from superKlass
142 klassVtable* superVtable = super->vtable();
143 assert(superVtable->length() <= _length, "vtable too short");
144 #ifdef ASSERT
145 superVtable->verify(tty, true);
146 #endif
147 superVtable->copy_vtable_to(table());
148 if (log_develop_is_enabled(Trace, vtables)) {
149 ResourceMark rm;
150 log_develop_trace(vtables)("copy vtable from %s to %s size %d",
151 super->internal_name(), klass()->internal_name(),
152 _length);
153 }
154 return superVtable->length();
155 }
156 }
157
158 //
159 // Revised lookup semantics introduced 1.3 (Kestrel beta)
160 void klassVtable::initialize_vtable(bool checkconstraints, TRAPS) {
161
162 // Note: Arrays can have intermediate array supers. Use java_super to skip them.
163 KlassHandle super (THREAD, klass()->java_super());
164 int nofNewEntries = 0;
165
166 bool is_shared = _klass->is_shared();
167
168 if (!klass()->is_array_klass()) {
169 ResourceMark rm(THREAD);
170 log_develop_debug(vtables)("Initializing: %s", _klass->name()->as_C_string());
171 }
172
173 #ifdef ASSERT
174 oop* end_of_obj = (oop*)_klass() + _klass()->size();
175 oop* end_of_vtable = (oop*)&table()[_length];
176 assert(end_of_vtable <= end_of_obj, "vtable extends beyond end");
177 #endif
178
179 if (Universe::is_bootstrapping()) {
180 assert(!is_shared, "sanity");
181 // just clear everything
182 for (int i = 0; i < _length; i++) table()[i].clear();
183 return;
184 }
185
186 int super_vtable_len = initialize_from_super(super);
187 if (klass()->is_array_klass()) {
188 assert(super_vtable_len == _length, "arrays shouldn't introduce new methods");
189 } else {
190 assert(_klass->is_instance_klass(), "must be InstanceKlass");
191
192 Array<Method*>* methods = ik()->methods();
193 int len = methods->length();
194 int initialized = super_vtable_len;
195
196 // Check each of this class's methods against super;
197 // if override, replace in copy of super vtable, otherwise append to end
198 for (int i = 0; i < len; i++) {
199 // update_inherited_vtable can stop for gc - ensure using handles
200 HandleMark hm(THREAD);
201 assert(methods->at(i)->is_method(), "must be a Method*");
202 methodHandle mh(THREAD, methods->at(i));
203
204 bool needs_new_entry = update_inherited_vtable(ik(), mh, super_vtable_len, -1, checkconstraints, CHECK);
205
206 if (needs_new_entry) {
207 put_method_at(mh(), initialized);
208 mh()->set_vtable_index(initialized); // set primary vtable index
209 initialized++;
210 }
211 }
212
213 // update vtable with default_methods
214 Array<Method*>* default_methods = ik()->default_methods();
215 if (default_methods != NULL) {
216 len = default_methods->length();
217 if (len > 0) {
218 Array<int>* def_vtable_indices = NULL;
219 if ((def_vtable_indices = ik()->default_vtable_indices()) == NULL) {
220 assert(!is_shared, "shared class def_vtable_indices does not exist");
221 def_vtable_indices = ik()->create_new_default_vtable_indices(len, CHECK);
222 } else {
223 assert(def_vtable_indices->length() == len, "reinit vtable len?");
224 }
225 for (int i = 0; i < len; i++) {
226 HandleMark hm(THREAD);
227 assert(default_methods->at(i)->is_method(), "must be a Method*");
228 methodHandle mh(THREAD, default_methods->at(i));
229
230 bool needs_new_entry = update_inherited_vtable(ik(), mh, super_vtable_len, i, checkconstraints, CHECK);
231
232 // needs new entry
233 if (needs_new_entry) {
234 put_method_at(mh(), initialized);
235 if (is_preinitialized_vtable()) {
236 // At runtime initialize_vtable is rerun for a shared class
237 // (loaded by the non-boot loader) as part of link_class_impl().
238 // The dumptime vtable index should be the same as the runtime index.
239 assert(def_vtable_indices->at(i) == initialized,
240 "dump time vtable index is different from runtime index");
241 } else {
242 def_vtable_indices->at_put(i, initialized); //set vtable index
243 }
244 initialized++;
245 }
246 }
247 }
248 }
249
250 // add miranda methods; it will also return the updated initialized
251 // Interfaces do not need interface methods in their vtables
252 // This includes miranda methods and during later processing, default methods
253 if (!ik()->is_interface()) {
254 initialized = fill_in_mirandas(initialized);
255 }
256
257 // In class hierarchies where the accessibility is not increasing (i.e., going from private ->
258 // package_private -> public/protected), the vtable might actually be smaller than our initial
259 // calculation.
260 assert(initialized <= _length, "vtable initialization failed");
261 for(;initialized < _length; initialized++) {
262 put_method_at(NULL, initialized);
263 }
264 NOT_PRODUCT(verify(tty, true));
265 }
266 }
267
268 // Called for cases where a method does not override its superclass' vtable entry
269 // For bytecodes not produced by javac together it is possible that a method does not override
270 // the superclass's method, but might indirectly override a super-super class's vtable entry
271 // If none found, return a null superk, else return the superk of the method this does override
272 // For public and protected methods: if they override a superclass, they will
273 // also be overridden themselves appropriately.
274 // Private methods do not override and are not overridden.
275 // Package Private methods are trickier:
276 // e.g. P1.A, pub m
277 // P2.B extends A, package private m
278 // P1.C extends B, public m
279 // P1.C.m needs to override P1.A.m and can not override P2.B.m
280 // Therefore: all package private methods need their own vtable entries for
281 // them to be the root of an inheritance overriding decision
282 // Package private methods may also override other vtable entries
283 InstanceKlass* klassVtable::find_transitive_override(InstanceKlass* initialsuper, methodHandle target_method,
284 int vtable_index, Handle target_loader, Symbol* target_classname, Thread * THREAD) {
285 InstanceKlass* superk = initialsuper;
286 while (superk != NULL && superk->super() != NULL) {
287 InstanceKlass* supersuperklass = InstanceKlass::cast(superk->super());
288 klassVtable* ssVtable = supersuperklass->vtable();
289 if (vtable_index < ssVtable->length()) {
290 Method* super_method = ssVtable->method_at(vtable_index);
291 #ifndef PRODUCT
292 Symbol* name= target_method()->name();
293 Symbol* signature = target_method()->signature();
294 assert(super_method->name() == name && super_method->signature() == signature, "vtable entry name/sig mismatch");
295 #endif
296 if (supersuperklass->is_override(super_method, target_loader, target_classname, THREAD)) {
297 if (log_develop_is_enabled(Trace, vtables)) {
298 ResourceMark rm(THREAD);
299 outputStream* logst = Log(vtables)::trace_stream();
300 char* sig = target_method()->name_and_sig_as_C_string();
301 logst->print("transitive overriding superclass %s with %s::%s index %d, original flags: ",
302 supersuperklass->internal_name(),
303 _klass->internal_name(), sig, vtable_index);
304 super_method->print_linkage_flags(logst);
305 logst->print("overriders flags: ");
306 target_method->print_linkage_flags(logst);
307 logst->cr();
308 }
309
310 break; // return found superk
311 }
312 } else {
313 // super class has no vtable entry here, stop transitive search
314 superk = (InstanceKlass*)NULL;
315 break;
316 }
317 // if no override found yet, continue to search up
318 superk = superk->super() == NULL ? NULL : InstanceKlass::cast(superk->super());
319 }
320
321 return superk;
322 }
323
324 static void log_vtables(int i, bool overrides, methodHandle target_method,
325 KlassHandle target_klass, Method* super_method,
326 Thread* thread) {
327 #ifndef PRODUCT
328 if (log_develop_is_enabled(Trace, vtables)) {
329 ResourceMark rm(thread);
330 outputStream* logst = Log(vtables)::trace_stream();
331 char* sig = target_method()->name_and_sig_as_C_string();
332 if (overrides) {
333 logst->print("overriding with %s::%s index %d, original flags: ",
334 target_klass->internal_name(), sig, i);
335 } else {
336 logst->print("NOT overriding with %s::%s index %d, original flags: ",
337 target_klass->internal_name(), sig, i);
338 }
339 super_method->print_linkage_flags(logst);
340 logst->print("overriders flags: ");
341 target_method->print_linkage_flags(logst);
342 logst->cr();
343 }
344 #endif
345 }
346
347 // Update child's copy of super vtable for overrides
348 // OR return true if a new vtable entry is required.
349 // Only called for InstanceKlass's, i.e. not for arrays
350 // If that changed, could not use _klass as handle for klass
351 bool klassVtable::update_inherited_vtable(InstanceKlass* klass, methodHandle target_method,
352 int super_vtable_len, int default_index,
353 bool checkconstraints, TRAPS) {
354 ResourceMark rm;
355 bool allocate_new = true;
356 assert(klass->is_instance_klass(), "must be InstanceKlass");
357
358 Array<int>* def_vtable_indices = NULL;
359 bool is_default = false;
360 // default methods are concrete methods in superinterfaces which are added to the vtable
361 // with their real method_holder
362 // Since vtable and itable indices share the same storage, don't touch
363 // the default method's real vtable/itable index
364 // default_vtable_indices stores the vtable value relative to this inheritor
365 if (default_index >= 0 ) {
366 is_default = true;
367 def_vtable_indices = klass->default_vtable_indices();
368 assert(def_vtable_indices != NULL, "def vtable alloc?");
369 assert(default_index <= def_vtable_indices->length(), "def vtable len?");
370 } else {
371 assert(klass == target_method()->method_holder(), "caller resp.");
372 // Initialize the method's vtable index to "nonvirtual".
373 // If we allocate a vtable entry, we will update it to a non-negative number.
374 target_method()->set_vtable_index(Method::nonvirtual_vtable_index);
375 }
376
377 // Static and <init> methods are never in
378 if (target_method()->is_static() || target_method()->name() == vmSymbols::object_initializer_name()) {
379 return false;
380 }
381
382 if (target_method->is_final_method(klass->access_flags())) {
383 // a final method never needs a new entry; final methods can be statically
384 // resolved and they have to be present in the vtable only if they override
385 // a super's method, in which case they re-use its entry
386 allocate_new = false;
387 } else if (klass->is_interface()) {
388 allocate_new = false; // see note below in needs_new_vtable_entry
389 // An interface never allocates new vtable slots, only inherits old ones.
390 // This method will either be assigned its own itable index later,
391 // or be assigned an inherited vtable index in the loop below.
392 // default methods inherited by classes store their vtable indices
393 // in the inheritor's default_vtable_indices
394 // default methods inherited by interfaces may already have a
395 // valid itable index, if so, don't change it
396 // overpass methods in an interface will be assigned an itable index later
397 // by an inheriting class
398 if (!is_default || !target_method()->has_itable_index()) {
399 target_method()->set_vtable_index(Method::pending_itable_index);
400 }
401 }
402
403 // we need a new entry if there is no superclass
404 Klass* super = klass->super();
405 if (super == NULL) {
406 return allocate_new;
407 }
408
409 // private methods in classes always have a new entry in the vtable
410 // specification interpretation since classic has
411 // private methods not overriding
412 // JDK8 adds private methods in interfaces which require invokespecial
413 if (target_method()->is_private()) {
414 return allocate_new;
415 }
416
417 // search through the vtable and update overridden entries
418 // Since check_signature_loaders acquires SystemDictionary_lock
419 // which can block for gc, once we are in this loop, use handles
420 // For classfiles built with >= jdk7, we now look for transitive overrides
421
422 Symbol* name = target_method()->name();
423 Symbol* signature = target_method()->signature();
424
425 KlassHandle target_klass(THREAD, target_method()->method_holder());
426 if (target_klass == NULL) {
427 target_klass = _klass;
428 }
429
430 Handle target_loader(THREAD, target_klass->class_loader());
431
432 Symbol* target_classname = target_klass->name();
433 for(int i = 0; i < super_vtable_len; i++) {
434 Method* super_method;
435 if (is_preinitialized_vtable()) {
436 // If this is a shared class, the vtable is already in the final state (fully
437 // initialized). Need to look at the super's vtable.
438 klassVtable* superVtable = super->vtable();
439 super_method = superVtable->method_at(i);
440 } else {
441 super_method = method_at(i);
442 }
443 // Check if method name matches
444 if (super_method->name() == name && super_method->signature() == signature) {
445
446 // get super_klass for method_holder for the found method
447 InstanceKlass* super_klass = super_method->method_holder();
448
449 // Whether the method is being overridden
450 bool overrides = false;
451
452 // private methods are also never overridden
453 if (!super_method->is_private() &&
454 (is_default
455 || ((super_klass->is_override(super_method, target_loader, target_classname, THREAD))
456 || ((klass->major_version() >= VTABLE_TRANSITIVE_OVERRIDE_VERSION)
457 && ((super_klass = find_transitive_override(super_klass,
458 target_method, i, target_loader,
459 target_classname, THREAD))
460 != (InstanceKlass*)NULL)))))
461 {
462 // Package private methods always need a new entry to root their own
463 // overriding. They may also override other methods.
464 if (!target_method()->is_package_private()) {
465 allocate_new = false;
466 }
467
468 if (checkconstraints) {
469 // Override vtable entry if passes loader constraint check
470 // if loader constraint checking requested
471 // No need to visit his super, since he and his super
472 // have already made any needed loader constraints.
473 // Since loader constraints are transitive, it is enough
474 // to link to the first super, and we get all the others.
475 Handle super_loader(THREAD, super_klass->class_loader());
476
477 if (target_loader() != super_loader()) {
478 ResourceMark rm(THREAD);
479 Symbol* failed_type_symbol =
480 SystemDictionary::check_signature_loaders(signature, target_loader,
481 super_loader, true,
482 CHECK_(false));
483 if (failed_type_symbol != NULL) {
484 const char* msg = "loader constraint violation: when resolving "
485 "overridden method \"%s\" the class loader (instance"
486 " of %s) of the current class, %s, and its superclass loader "
487 "(instance of %s), have different Class objects for the type "
488 "%s used in the signature";
489 char* sig = target_method()->name_and_sig_as_C_string();
490 const char* loader1 = SystemDictionary::loader_name(target_loader());
491 char* current = target_klass->name()->as_C_string();
492 const char* loader2 = SystemDictionary::loader_name(super_loader());
493 char* failed_type_name = failed_type_symbol->as_C_string();
494 size_t buflen = strlen(msg) + strlen(sig) + strlen(loader1) +
495 strlen(current) + strlen(loader2) + strlen(failed_type_name);
496 char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen);
497 jio_snprintf(buf, buflen, msg, sig, loader1, current, loader2,
498 failed_type_name);
499 THROW_MSG_(vmSymbols::java_lang_LinkageError(), buf, false);
500 }
501 }
502 }
503
504 put_method_at(target_method(), i);
505 overrides = true;
506 if (!is_default) {
507 target_method()->set_vtable_index(i);
508 } else {
509 if (def_vtable_indices != NULL) {
510 if (is_preinitialized_vtable()) {
511 // At runtime initialize_vtable is rerun as part of link_class_impl()
512 // for a shared class loaded by the non-boot loader.
513 // The dumptime vtable index should be the same as the runtime index.
514 assert(def_vtable_indices->at(default_index) == i,
515 "dump time vtable index is different from runtime index");
516 } else {
517 def_vtable_indices->at_put(default_index, i);
518 }
519 }
520 assert(super_method->is_default_method() || super_method->is_overpass()
521 || super_method->is_abstract(), "default override error");
522 }
523 } else {
524 overrides = false;
525 }
526 log_vtables(i, overrides, target_method, target_klass, super_method, THREAD);
527 }
528 }
529 return allocate_new;
530 }
531
532 void klassVtable::put_method_at(Method* m, int index) {
533 if (is_preinitialized_vtable()) {
534 // At runtime initialize_vtable is rerun as part of link_class_impl()
535 // for shared class loaded by the non-boot loader to obtain the loader
536 // constraints based on the runtime classloaders' context. The dumptime
537 // method at the vtable index should be the same as the runtime method.
538 assert(table()[index].method() == m,
539 "archived method is different from the runtime method");
540 } else {
541 if (log_develop_is_enabled(Trace, vtables)) {
542 ResourceMark rm;
543 outputStream* logst = Log(vtables)::trace_stream();
544 const char* sig = (m != NULL) ? m->name_and_sig_as_C_string() : "<NULL>";
545 logst->print("adding %s at index %d, flags: ", sig, index);
546 if (m != NULL) {
547 m->print_linkage_flags(logst);
548 }
549 logst->cr();
550 }
551 table()[index].set(m);
552 }
553 }
554
555 // Find out if a method "m" with superclass "super", loader "classloader" and
556 // name "classname" needs a new vtable entry. Let P be a class package defined
557 // by "classloader" and "classname".
558 // NOTE: The logic used here is very similar to the one used for computing
559 // the vtables indices for a method. We cannot directly use that function because,
560 // we allocate the InstanceKlass at load time, and that requires that the
561 // superclass has been loaded.
562 // However, the vtable entries are filled in at link time, and therefore
563 // the superclass' vtable may not yet have been filled in.
564 bool klassVtable::needs_new_vtable_entry(methodHandle target_method,
565 const Klass* super,
566 Handle classloader,
567 Symbol* classname,
568 AccessFlags class_flags,
569 TRAPS) {
570 if (class_flags.is_interface()) {
571 // Interfaces do not use vtables, except for java.lang.Object methods,
572 // so there is no point to assigning
573 // a vtable index to any of their local methods. If we refrain from doing this,
574 // we can use Method::_vtable_index to hold the itable index
575 return false;
576 }
577
578 if (target_method->is_final_method(class_flags) ||
579 // a final method never needs a new entry; final methods can be statically
580 // resolved and they have to be present in the vtable only if they override
581 // a super's method, in which case they re-use its entry
582 (target_method()->is_static()) ||
583 // static methods don't need to be in vtable
584 (target_method()->name() == vmSymbols::object_initializer_name())
585 // <init> is never called dynamically-bound
586 ) {
587 return false;
588 }
589
590 // Concrete interface methods do not need new entries, they override
591 // abstract method entries using default inheritance rules
592 if (target_method()->method_holder() != NULL &&
593 target_method()->method_holder()->is_interface() &&
594 !target_method()->is_abstract() ) {
595 return false;
596 }
597
598 // we need a new entry if there is no superclass
599 if (super == NULL) {
600 return true;
601 }
602
603 // private methods in classes always have a new entry in the vtable
604 // specification interpretation since classic has
605 // private methods not overriding
606 // JDK8 adds private methods in interfaces which require invokespecial
607 if (target_method()->is_private()) {
608 return true;
609 }
610
611 // Package private methods always need a new entry to root their own
612 // overriding. This allows transitive overriding to work.
613 if (target_method()->is_package_private()) {
614 return true;
615 }
616
617 // search through the super class hierarchy to see if we need
618 // a new entry
619 ResourceMark rm;
620 Symbol* name = target_method()->name();
621 Symbol* signature = target_method()->signature();
622 const Klass* k = super;
623 Method* super_method = NULL;
624 InstanceKlass *holder = NULL;
625 Method* recheck_method = NULL;
626 while (k != NULL) {
627 // lookup through the hierarchy for a method with matching name and sign.
628 super_method = InstanceKlass::cast(k)->lookup_method(name, signature);
629 if (super_method == NULL) {
630 break; // we still have to search for a matching miranda method
631 }
632 // get the class holding the matching method
633 // make sure you use that class for is_override
634 InstanceKlass* superk = super_method->method_holder();
635 // we want only instance method matches
636 // pretend private methods are not in the super vtable
637 // since we do override around them: e.g. a.m pub/b.m private/c.m pub,
638 // ignore private, c.m pub does override a.m pub
639 // For classes that were not javac'd together, we also do transitive overriding around
640 // methods that have less accessibility
641 if ((!super_method->is_static()) &&
642 (!super_method->is_private())) {
643 if (superk->is_override(super_method, classloader, classname, THREAD)) {
644 return false;
645 // else keep looking for transitive overrides
646 }
647 }
648
649 // Start with lookup result and continue to search up
650 k = superk->super(); // haven't found an override match yet; continue to look
651 }
652
653 // if the target method is public or protected it may have a matching
654 // miranda method in the super, whose entry it should re-use.
655 // Actually, to handle cases that javac would not generate, we need
656 // this check for all access permissions.
657 const InstanceKlass *sk = InstanceKlass::cast(super);
658 if (sk->has_miranda_methods()) {
659 if (sk->lookup_method_in_all_interfaces(name, signature, Klass::find_defaults) != NULL) {
660 return false; // found a matching miranda; we do not need a new entry
661 }
662 }
663 return true; // found no match; we need a new entry
664 }
665
666 // Support for miranda methods
667
668 // get the vtable index of a miranda method with matching "name" and "signature"
669 int klassVtable::index_of_miranda(Symbol* name, Symbol* signature) {
670 // search from the bottom, might be faster
671 for (int i = (length() - 1); i >= 0; i--) {
672 Method* m = table()[i].method();
673 if (is_miranda_entry_at(i) &&
674 m->name() == name && m->signature() == signature) {
675 return i;
676 }
677 }
678 return Method::invalid_vtable_index;
679 }
680
681 // check if an entry at an index is miranda
682 // requires that method m at entry be declared ("held") by an interface.
683 bool klassVtable::is_miranda_entry_at(int i) {
684 Method* m = method_at(i);
685 Klass* method_holder = m->method_holder();
686 InstanceKlass *mhk = InstanceKlass::cast(method_holder);
687
688 // miranda methods are public abstract instance interface methods in a class's vtable
689 if (mhk->is_interface()) {
690 assert(m->is_public(), "should be public");
691 assert(ik()->implements_interface(method_holder) , "this class should implement the interface");
692 if (is_miranda(m, ik()->methods(), ik()->default_methods(), ik()->super())) {
693 return true;
694 }
695 }
696 return false;
697 }
698
699 // Check if a method is a miranda method, given a class's methods array,
700 // its default_method table and its super class.
701 // "Miranda" means an abstract non-private method that would not be
702 // overridden for the local class.
703 // A "miranda" method should only include non-private interface
704 // instance methods, i.e. not private methods, not static methods,
705 // not default methods (concrete interface methods), not overpass methods.
706 // If a given class already has a local (including overpass) method, a
707 // default method, or any of its superclasses has the same which would have
708 // overridden an abstract method, then this is not a miranda method.
709 //
710 // Miranda methods are checked multiple times.
711 // Pass 1: during class load/class file parsing: before vtable size calculation:
712 // include superinterface abstract and default methods (non-private instance).
713 // We include potential default methods to give them space in the vtable.
714 // During the first run, the current instanceKlass has not yet been
715 // created, the superclasses and superinterfaces do have instanceKlasses
716 // but may not have vtables, the default_methods list is empty, no overpasses.
717 // This is seen by default method creation.
718 //
719 // Pass 2: recalculated during vtable initialization: only include abstract methods.
720 // The goal of pass 2 is to walk through the superinterfaces to see if any of
721 // the superinterface methods (which were all abstract pre-default methods)
722 // need to be added to the vtable.
723 // With the addition of default methods, we have three new challenges:
724 // overpasses, static interface methods and private interface methods.
725 // Static and private interface methods do not get added to the vtable and
726 // are not seen by the method resolution process, so we skip those.
727 // Overpass methods are already in the vtable, so vtable lookup will
728 // find them and we don't need to add a miranda method to the end of
729 // the vtable. So we look for overpass methods and if they are found we
730 // return false. Note that we inherit our superclasses vtable, so
731 // the superclass' search also needs to use find_overpass so that if
732 // one is found we return false.
733 // False means - we don't need a miranda method added to the vtable.
734 //
735 // During the second run, default_methods is set up, so concrete methods from
736 // superinterfaces with matching names/signatures to default_methods are already
737 // in the default_methods list and do not need to be appended to the vtable
738 // as mirandas. Abstract methods may already have been handled via
739 // overpasses - either local or superclass overpasses, which may be
740 // in the vtable already.
741 //
742 // Pass 3: They are also checked by link resolution and selection,
743 // for invocation on a method (not interface method) reference that
744 // resolves to a method with an interface as its method_holder.
745 // Used as part of walking from the bottom of the vtable to find
746 // the vtable index for the miranda method.
747 //
748 // Part of the Miranda Rights in the US mean that if you do not have
749 // an attorney one will be appointed for you.
750 bool klassVtable::is_miranda(Method* m, Array<Method*>* class_methods,
751 Array<Method*>* default_methods, const Klass* super) {
752 if (m->is_static() || m->is_private() || m->is_overpass()) {
753 return false;
754 }
755 Symbol* name = m->name();
756 Symbol* signature = m->signature();
757
758 // First look in local methods to see if already covered
759 if (InstanceKlass::find_local_method(class_methods, name, signature,
760 Klass::find_overpass, Klass::skip_static, Klass::skip_private) != NULL)
761 {
762 return false;
763 }
764
765 // Check local default methods
766 if ((default_methods != NULL) &&
767 (InstanceKlass::find_method(default_methods, name, signature) != NULL))
768 {
769 return false;
770 }
771
772 // Iterate on all superclasses, which should be InstanceKlasses.
773 // Note that we explicitly look for overpasses at each level.
774 // Overpasses may or may not exist for supers for pass 1,
775 // they should have been created for pass 2 and later.
776
777 for (const Klass* cursuper = super; cursuper != NULL; cursuper = cursuper->super())
778 {
779 if (InstanceKlass::cast(cursuper)->find_local_method(name, signature,
780 Klass::find_overpass, Klass::skip_static, Klass::skip_private) != NULL) {
781 return false;
782 }
783 }
784
785 return true;
786 }
787
788 // Scans current_interface_methods for miranda methods that do not
789 // already appear in new_mirandas, or default methods, and are also not defined-and-non-private
790 // in super (superclass). These mirandas are added to all_mirandas if it is
791 // not null; in addition, those that are not duplicates of miranda methods
792 // inherited by super from its interfaces are added to new_mirandas.
793 // Thus, new_mirandas will be the set of mirandas that this class introduces,
794 // all_mirandas will be the set of all mirandas applicable to this class
795 // including all defined in superclasses.
796 void klassVtable::add_new_mirandas_to_lists(
797 GrowableArray<Method*>* new_mirandas, GrowableArray<Method*>* all_mirandas,
798 Array<Method*>* current_interface_methods, Array<Method*>* class_methods,
799 Array<Method*>* default_methods, const Klass* super) {
800
801 // iterate thru the current interface's method to see if it a miranda
802 int num_methods = current_interface_methods->length();
803 for (int i = 0; i < num_methods; i++) {
804 Method* im = current_interface_methods->at(i);
805 bool is_duplicate = false;
806 int num_of_current_mirandas = new_mirandas->length();
807 // check for duplicate mirandas in different interfaces we implement
808 for (int j = 0; j < num_of_current_mirandas; j++) {
809 Method* miranda = new_mirandas->at(j);
810 if ((im->name() == miranda->name()) &&
811 (im->signature() == miranda->signature())) {
812 is_duplicate = true;
813 break;
814 }
815 }
816
817 if (!is_duplicate) { // we don't want duplicate miranda entries in the vtable
818 if (is_miranda(im, class_methods, default_methods, super)) { // is it a miranda at all?
819 const InstanceKlass *sk = InstanceKlass::cast(super);
820 // check if it is a duplicate of a super's miranda
821 if (sk->lookup_method_in_all_interfaces(im->name(), im->signature(), Klass::find_defaults) == NULL) {
822 new_mirandas->append(im);
823 }
824 if (all_mirandas != NULL) {
825 all_mirandas->append(im);
826 }
827 }
828 }
829 }
830 }
831
832 void klassVtable::get_mirandas(GrowableArray<Method*>* new_mirandas,
833 GrowableArray<Method*>* all_mirandas,
834 const Klass* super,
835 Array<Method*>* class_methods,
836 Array<Method*>* default_methods,
837 Array<Klass*>* local_interfaces) {
838 assert((new_mirandas->length() == 0) , "current mirandas must be 0");
839
840 // iterate thru the local interfaces looking for a miranda
841 int num_local_ifs = local_interfaces->length();
842 for (int i = 0; i < num_local_ifs; i++) {
843 InstanceKlass *ik = InstanceKlass::cast(local_interfaces->at(i));
844 add_new_mirandas_to_lists(new_mirandas, all_mirandas,
845 ik->methods(), class_methods,
846 default_methods, super);
847 // iterate thru each local's super interfaces
848 Array<Klass*>* super_ifs = ik->transitive_interfaces();
849 int num_super_ifs = super_ifs->length();
850 for (int j = 0; j < num_super_ifs; j++) {
851 InstanceKlass *sik = InstanceKlass::cast(super_ifs->at(j));
852 add_new_mirandas_to_lists(new_mirandas, all_mirandas,
853 sik->methods(), class_methods,
854 default_methods, super);
855 }
856 }
857 }
858
859 // Discover miranda methods ("miranda" = "interface abstract, no binding"),
860 // and append them into the vtable starting at index initialized,
861 // return the new value of initialized.
862 // Miranda methods use vtable entries, but do not get assigned a vtable_index
863 // The vtable_index is discovered by searching from the end of the vtable
864 int klassVtable::fill_in_mirandas(int initialized) {
865 GrowableArray<Method*> mirandas(20);
866 get_mirandas(&mirandas, NULL, ik()->super(), ik()->methods(),
867 ik()->default_methods(), ik()->local_interfaces());
868 for (int i = 0; i < mirandas.length(); i++) {
869 if (log_develop_is_enabled(Trace, vtables)) {
870 Method* meth = mirandas.at(i);
871 ResourceMark rm(Thread::current());
872 outputStream* logst = Log(vtables)::trace_stream();
873 if (meth != NULL) {
874 char* sig = meth->name_and_sig_as_C_string();
875 logst->print("fill in mirandas with %s index %d, flags: ",
876 sig, initialized);
877 meth->print_linkage_flags(logst);
878 logst->cr();
879 }
880 }
881 put_method_at(mirandas.at(i), initialized);
882 ++initialized;
883 }
884 return initialized;
885 }
886
887 // Copy this class's vtable to the vtable beginning at start.
888 // Used to copy superclass vtable to prefix of subclass's vtable.
889 void klassVtable::copy_vtable_to(vtableEntry* start) {
890 Copy::disjoint_words((HeapWord*)table(), (HeapWord*)start, _length * vtableEntry::size());
891 }
892
893 #if INCLUDE_JVMTI
894 bool klassVtable::adjust_default_method(int vtable_index, Method* old_method, Method* new_method) {
895 // If old_method is default, find this vtable index in default_vtable_indices
896 // and replace that method in the _default_methods list
897 bool updated = false;
898
899 Array<Method*>* default_methods = ik()->default_methods();
900 if (default_methods != NULL) {
901 int len = default_methods->length();
902 for (int idx = 0; idx < len; idx++) {
903 if (vtable_index == ik()->default_vtable_indices()->at(idx)) {
904 if (default_methods->at(idx) == old_method) {
905 default_methods->at_put(idx, new_method);
906 updated = true;
907 }
908 break;
909 }
910 }
911 }
912 return updated;
913 }
914
915 // search the vtable for uses of either obsolete or EMCP methods
916 void klassVtable::adjust_method_entries(InstanceKlass* holder, bool * trace_name_printed) {
917 int prn_enabled = 0;
918 for (int index = 0; index < length(); index++) {
919 Method* old_method = unchecked_method_at(index);
920 if (old_method == NULL || old_method->method_holder() != holder || !old_method->is_old()) {
921 continue; // skip uninteresting entries
922 }
923 assert(!old_method->is_deleted(), "vtable methods may not be deleted");
924
925 Method* new_method = holder->method_with_idnum(old_method->orig_method_idnum());
926
927 assert(new_method != NULL, "method_with_idnum() should not be NULL");
928 assert(old_method != new_method, "sanity check");
929
930 put_method_at(new_method, index);
931 // For default methods, need to update the _default_methods array
932 // which can only have one method entry for a given signature
933 bool updated_default = false;
934 if (old_method->is_default_method()) {
935 updated_default = adjust_default_method(index, old_method, new_method);
936 }
937
938 if (log_is_enabled(Info, redefine, class, update)) {
939 ResourceMark rm;
940 if (!(*trace_name_printed)) {
941 log_info(redefine, class, update)
942 ("adjust: klassname=%s for methods from name=%s",
943 klass()->external_name(), old_method->method_holder()->external_name());
944 *trace_name_printed = true;
945 }
946 log_debug(redefine, class, update, vtables)
947 ("vtable method update: %s(%s), updated default = %s",
948 new_method->name()->as_C_string(), new_method->signature()->as_C_string(), updated_default ? "true" : "false");
949 }
950 }
951 }
952
953 // a vtable should never contain old or obsolete methods
954 bool klassVtable::check_no_old_or_obsolete_entries() {
955 for (int i = 0; i < length(); i++) {
956 Method* m = unchecked_method_at(i);
957 if (m != NULL &&
958 (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) {
959 return false;
960 }
961 }
962 return true;
963 }
964
965 void klassVtable::dump_vtable() {
966 tty->print_cr("vtable dump --");
967 for (int i = 0; i < length(); i++) {
968 Method* m = unchecked_method_at(i);
969 if (m != NULL) {
970 tty->print(" (%5d) ", i);
971 m->access_flags().print_on(tty);
972 if (m->is_default_method()) {
973 tty->print("default ");
974 }
975 if (m->is_overpass()) {
976 tty->print("overpass");
977 }
978 tty->print(" -- ");
979 m->print_name(tty);
980 tty->cr();
981 }
982 }
983 }
984 #endif // INCLUDE_JVMTI
985
986 // CDS/RedefineClasses support - clear vtables so they can be reinitialized
987 void klassVtable::clear_vtable() {
988 for (int i = 0; i < _length; i++) table()[i].clear();
989 }
990
991 bool klassVtable::is_initialized() {
992 return _length == 0 || table()[0].method() != NULL;
993 }
994
995 //-----------------------------------------------------------------------------------------
996 // Itable code
997
998 // Initialize a itableMethodEntry
999 void itableMethodEntry::initialize(Method* m) {
1000 if (m == NULL) return;
1001
1002 if (MetaspaceShared::is_in_shared_space((void*)&_method) &&
1003 !MetaspaceShared::remapped_readwrite()) {
1004 // At runtime initialize_itable is rerun as part of link_class_impl()
1005 // for a shared class loaded by the non-boot loader.
1006 // The dumptime itable method entry should be the same as the runtime entry.
1007 assert(_method == m, "sanity");
1008 } else {
1009 _method = m;
1010 }
1011 }
1012
1013 klassItable::klassItable(instanceKlassHandle klass) {
1014 _klass = klass;
1015
1016 if (klass->itable_length() > 0) {
1017 itableOffsetEntry* offset_entry = (itableOffsetEntry*)klass->start_of_itable();
1018 if (offset_entry != NULL && offset_entry->interface_klass() != NULL) { // Check that itable is initialized
1019 // First offset entry points to the first method_entry
1020 intptr_t* method_entry = (intptr_t *)(((address)klass()) + offset_entry->offset());
1021 intptr_t* end = klass->end_of_itable();
1022
1023 _table_offset = (intptr_t*)offset_entry - (intptr_t*)klass();
1024 _size_offset_table = (method_entry - ((intptr_t*)offset_entry)) / itableOffsetEntry::size();
1025 _size_method_table = (end - method_entry) / itableMethodEntry::size();
1026 assert(_table_offset >= 0 && _size_offset_table >= 0 && _size_method_table >= 0, "wrong computation");
1027 return;
1028 }
1029 }
1030
1031 // The length of the itable was either zero, or it has not yet been initialized.
1032 _table_offset = 0;
1033 _size_offset_table = 0;
1034 _size_method_table = 0;
1035 }
1036
1037 static int initialize_count = 0;
1038
1039 // Initialization
1040 void klassItable::initialize_itable(bool checkconstraints, TRAPS) {
1041 if (_klass->is_interface()) {
1042 // This needs to go after vtable indices are assigned but
1043 // before implementors need to know the number of itable indices.
1044 assign_itable_indices_for_interface(_klass());
1045 }
1046
1047 // Cannot be setup doing bootstrapping, interfaces don't have
1048 // itables, and klass with only ones entry have empty itables
1049 if (Universe::is_bootstrapping() ||
1050 _klass->is_interface() ||
1051 _klass->itable_length() == itableOffsetEntry::size()) return;
1052
1053 // There's alway an extra itable entry so we can null-terminate it.
1054 guarantee(size_offset_table() >= 1, "too small");
1055 int num_interfaces = size_offset_table() - 1;
1056 if (num_interfaces > 0) {
1057 log_develop_debug(itables)("%3d: Initializing itables for %s", ++initialize_count,
1058 _klass->name()->as_C_string());
1059
1060
1061 // Iterate through all interfaces
1062 int i;
1063 for(i = 0; i < num_interfaces; i++) {
1064 itableOffsetEntry* ioe = offset_entry(i);
1065 HandleMark hm(THREAD);
1066 KlassHandle interf_h (THREAD, ioe->interface_klass());
1067 assert(interf_h() != NULL && ioe->offset() != 0, "bad offset entry in itable");
1068 initialize_itable_for_interface(ioe->offset(), interf_h, checkconstraints, CHECK);
1069 }
1070
1071 }
1072 // Check that the last entry is empty
1073 itableOffsetEntry* ioe = offset_entry(size_offset_table() - 1);
1074 guarantee(ioe->interface_klass() == NULL && ioe->offset() == 0, "terminator entry missing");
1075 }
1076
1077
1078 inline bool interface_method_needs_itable_index(Method* m) {
1079 if (m->is_static()) return false; // e.g., Stream.empty
1080 if (m->is_initializer()) return false; // <init> or <clinit>
1081 // If an interface redeclares a method from java.lang.Object,
1082 // it should already have a vtable index, don't touch it.
1083 // e.g., CharSequence.toString (from initialize_vtable)
1084 // if (m->has_vtable_index()) return false; // NO!
1085 return true;
1086 }
1087
1088 int klassItable::assign_itable_indices_for_interface(Klass* klass) {
1089 // an interface does not have an itable, but its methods need to be numbered
1090 log_develop_debug(itables)("%3d: Initializing itable indices for interface %s",
1091 ++initialize_count, klass->name()->as_C_string());
1092 Array<Method*>* methods = InstanceKlass::cast(klass)->methods();
1093 int nof_methods = methods->length();
1094 int ime_num = 0;
1095 for (int i = 0; i < nof_methods; i++) {
1096 Method* m = methods->at(i);
1097 if (interface_method_needs_itable_index(m)) {
1098 assert(!m->is_final_method(), "no final interface methods");
1099 // If m is already assigned a vtable index, do not disturb it.
1100 if (log_develop_is_enabled(Trace, itables)) {
1101 ResourceMark rm;
1102 outputStream* logst = Log(itables)::trace_stream();
1103 assert(m != NULL, "methods can never be null");
1104 const char* sig = m->name_and_sig_as_C_string();
1105 if (m->has_vtable_index()) {
1106 logst->print("vtable index %d for method: %s, flags: ", m->vtable_index(), sig);
1107 } else {
1108 logst->print("itable index %d for method: %s, flags: ", ime_num, sig);
1109 }
1110 m->print_linkage_flags(logst);
1111 logst->cr();
1112 }
1113 if (!m->has_vtable_index()) {
1114 // A shared method could have an initialized itable_index that
1115 // is < 0.
1116 assert(m->vtable_index() == Method::pending_itable_index ||
1117 m->is_shared(),
1118 "set by initialize_vtable");
1119 m->set_itable_index(ime_num);
1120 // Progress to next itable entry
1121 ime_num++;
1122 }
1123 }
1124 }
1125 assert(ime_num == method_count_for_interface(klass), "proper sizing");
1126 return ime_num;
1127 }
1128
1129 int klassItable::method_count_for_interface(Klass* interf) {
1130 assert(interf->is_instance_klass(), "must be");
1131 assert(interf->is_interface(), "must be");
1132 Array<Method*>* methods = InstanceKlass::cast(interf)->methods();
1133 int nof_methods = methods->length();
1134 int length = 0;
1135 while (nof_methods > 0) {
1136 Method* m = methods->at(nof_methods-1);
1137 if (m->has_itable_index()) {
1138 length = m->itable_index() + 1;
1139 break;
1140 }
1141 nof_methods -= 1;
1142 }
1143 #ifdef ASSERT
1144 int nof_methods_copy = nof_methods;
1145 while (nof_methods_copy > 0) {
1146 Method* mm = methods->at(--nof_methods_copy);
1147 assert(!mm->has_itable_index() || mm->itable_index() < length, "");
1148 }
1149 #endif //ASSERT
1150 // return the rightmost itable index, plus one; or 0 if no methods have
1151 // itable indices
1152 return length;
1153 }
1154
1155
1156 void klassItable::initialize_itable_for_interface(int method_table_offset, KlassHandle interf_h, bool checkconstraints, TRAPS) {
1157 Array<Method*>* methods = InstanceKlass::cast(interf_h())->methods();
1158 int nof_methods = methods->length();
1159 HandleMark hm;
1160 assert(nof_methods > 0, "at least one method must exist for interface to be in vtable");
1161 Handle interface_loader (THREAD, InstanceKlass::cast(interf_h())->class_loader());
1162
1163 int ime_count = method_count_for_interface(interf_h());
1164 for (int i = 0; i < nof_methods; i++) {
1165 Method* m = methods->at(i);
1166 methodHandle target;
1167 if (m->has_itable_index()) {
1168 // This search must match the runtime resolution, i.e. selection search for invokeinterface
1169 // to correctly enforce loader constraints for interface method inheritance
1170 target = LinkResolver::lookup_instance_method_in_klasses(_klass, m->name(), m->signature(), CHECK);
1171 }
1172 if (target == NULL || !target->is_public() || target->is_abstract()) {
1173 // Entry does not resolve. Leave it empty for AbstractMethodError.
1174 if (!(target == NULL) && !target->is_public()) {
1175 // Stuff an IllegalAccessError throwing method in there instead.
1176 itableOffsetEntry::method_entry(_klass(), method_table_offset)[m->itable_index()].
1177 initialize(Universe::throw_illegal_access_error());
1178 }
1179 } else {
1180 // Entry did resolve, check loader constraints before initializing
1181 // if checkconstraints requested
1182 if (checkconstraints) {
1183 Handle method_holder_loader (THREAD, target->method_holder()->class_loader());
1184 if (method_holder_loader() != interface_loader()) {
1185 ResourceMark rm(THREAD);
1186 Symbol* failed_type_symbol =
1187 SystemDictionary::check_signature_loaders(m->signature(),
1188 method_holder_loader,
1189 interface_loader,
1190 true, CHECK);
1191 if (failed_type_symbol != NULL) {
1192 const char* msg = "loader constraint violation in interface "
1193 "itable initialization: when resolving method \"%s\" the class"
1194 " loader (instance of %s) of the current class, %s, "
1195 "and the class loader (instance of %s) for interface "
1196 "%s have different Class objects for the type %s "
1197 "used in the signature";
1198 char* sig = target()->name_and_sig_as_C_string();
1199 const char* loader1 = SystemDictionary::loader_name(method_holder_loader());
1200 char* current = _klass->name()->as_C_string();
1201 const char* loader2 = SystemDictionary::loader_name(interface_loader());
1202 char* iface = InstanceKlass::cast(interf_h())->name()->as_C_string();
1203 char* failed_type_name = failed_type_symbol->as_C_string();
1204 size_t buflen = strlen(msg) + strlen(sig) + strlen(loader1) +
1205 strlen(current) + strlen(loader2) + strlen(iface) +
1206 strlen(failed_type_name);
1207 char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen);
1208 jio_snprintf(buf, buflen, msg, sig, loader1, current, loader2,
1209 iface, failed_type_name);
1210 THROW_MSG(vmSymbols::java_lang_LinkageError(), buf);
1211 }
1212 }
1213 }
1214
1215 // ime may have moved during GC so recalculate address
1216 int ime_num = m->itable_index();
1217 assert(ime_num < ime_count, "oob");
1218 itableOffsetEntry::method_entry(_klass(), method_table_offset)[ime_num].initialize(target());
1219 if (log_develop_is_enabled(Trace, itables)) {
1220 ResourceMark rm(THREAD);
1221 if (target() != NULL) {
1222 outputStream* logst = Log(itables)::trace_stream();
1223 char* sig = target()->name_and_sig_as_C_string();
1224 logst->print("interface: %s, ime_num: %d, target: %s, method_holder: %s ",
1225 interf_h()->internal_name(), ime_num, sig,
1226 target()->method_holder()->internal_name());
1227 logst->print("target_method flags: ");
1228 target()->print_linkage_flags(logst);
1229 logst->cr();
1230 }
1231 }
1232 }
1233 }
1234 }
1235
1236 // Update entry for specific Method*
1237 void klassItable::initialize_with_method(Method* m) {
1238 itableMethodEntry* ime = method_entry(0);
1239 for(int i = 0; i < _size_method_table; i++) {
1240 if (ime->method() == m) {
1241 ime->initialize(m);
1242 }
1243 ime++;
1244 }
1245 }
1246
1247 #if INCLUDE_JVMTI
1248 // search the itable for uses of either obsolete or EMCP methods
1249 void klassItable::adjust_method_entries(InstanceKlass* holder, bool * trace_name_printed) {
1250
1251 itableMethodEntry* ime = method_entry(0);
1252 for (int i = 0; i < _size_method_table; i++, ime++) {
1253 Method* old_method = ime->method();
1254 if (old_method == NULL || old_method->method_holder() != holder || !old_method->is_old()) {
1255 continue; // skip uninteresting entries
1256 }
1257 assert(!old_method->is_deleted(), "itable methods may not be deleted");
1258
1259 Method* new_method = holder->method_with_idnum(old_method->orig_method_idnum());
1260
1261 assert(new_method != NULL, "method_with_idnum() should not be NULL");
1262 assert(old_method != new_method, "sanity check");
1263
1264 ime->initialize(new_method);
1265
1266 if (log_is_enabled(Info, redefine, class, update)) {
1267 ResourceMark rm;
1268 if (!(*trace_name_printed)) {
1269 log_info(redefine, class, update)("adjust: name=%s", old_method->method_holder()->external_name());
1270 *trace_name_printed = true;
1271 }
1272 log_trace(redefine, class, update, itables)
1273 ("itable method update: %s(%s)", new_method->name()->as_C_string(), new_method->signature()->as_C_string());
1274 }
1275 }
1276 }
1277
1278 // an itable should never contain old or obsolete methods
1279 bool klassItable::check_no_old_or_obsolete_entries() {
1280 itableMethodEntry* ime = method_entry(0);
1281 for (int i = 0; i < _size_method_table; i++) {
1282 Method* m = ime->method();
1283 if (m != NULL &&
1284 (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) {
1285 return false;
1286 }
1287 ime++;
1288 }
1289 return true;
1290 }
1291
1292 void klassItable::dump_itable() {
1293 itableMethodEntry* ime = method_entry(0);
1294 tty->print_cr("itable dump --");
1295 for (int i = 0; i < _size_method_table; i++) {
1296 Method* m = ime->method();
1297 if (m != NULL) {
1298 tty->print(" (%5d) ", i);
1299 m->access_flags().print_on(tty);
1300 if (m->is_default_method()) {
1301 tty->print("default ");
1302 }
1303 tty->print(" -- ");
1304 m->print_name(tty);
1305 tty->cr();
1306 }
1307 ime++;
1308 }
1309 }
1310 #endif // INCLUDE_JVMTI
1311
1312 // Setup
1313 class InterfaceVisiterClosure : public StackObj {
1314 public:
1315 virtual void doit(Klass* intf, int method_count) = 0;
1316 };
1317
1318 // Visit all interfaces with at least one itable method
1319 void visit_all_interfaces(Array<Klass*>* transitive_intf, InterfaceVisiterClosure *blk) {
1320 // Handle array argument
1321 for(int i = 0; i < transitive_intf->length(); i++) {
1322 Klass* intf = transitive_intf->at(i);
1323 assert(intf->is_interface(), "sanity check");
1324
1325 // Find no. of itable methods
1326 int method_count = 0;
1327 // method_count = klassItable::method_count_for_interface(intf);
1328 Array<Method*>* methods = InstanceKlass::cast(intf)->methods();
1329 if (methods->length() > 0) {
1330 for (int i = methods->length(); --i >= 0; ) {
1331 if (interface_method_needs_itable_index(methods->at(i))) {
1332 method_count++;
1333 }
1334 }
1335 }
1336
1337 // Only count interfaces with at least one method
1338 if (method_count > 0) {
1339 blk->doit(intf, method_count);
1340 }
1341 }
1342 }
1343
1344 class CountInterfacesClosure : public InterfaceVisiterClosure {
1345 private:
1346 int _nof_methods;
1347 int _nof_interfaces;
1348 public:
1349 CountInterfacesClosure() { _nof_methods = 0; _nof_interfaces = 0; }
1350
1351 int nof_methods() const { return _nof_methods; }
1352 int nof_interfaces() const { return _nof_interfaces; }
1353
1354 void doit(Klass* intf, int method_count) { _nof_methods += method_count; _nof_interfaces++; }
1355 };
1356
1357 class SetupItableClosure : public InterfaceVisiterClosure {
1358 private:
1359 itableOffsetEntry* _offset_entry;
1360 itableMethodEntry* _method_entry;
1361 address _klass_begin;
1362 public:
1363 SetupItableClosure(address klass_begin, itableOffsetEntry* offset_entry, itableMethodEntry* method_entry) {
1364 _klass_begin = klass_begin;
1365 _offset_entry = offset_entry;
1366 _method_entry = method_entry;
1367 }
1368
1369 itableMethodEntry* method_entry() const { return _method_entry; }
1370
1371 void doit(Klass* intf, int method_count) {
1372 int offset = ((address)_method_entry) - _klass_begin;
1373 _offset_entry->initialize(intf, offset);
1374 _offset_entry++;
1375 _method_entry += method_count;
1376 }
1377 };
1378
1379 int klassItable::compute_itable_size(Array<Klass*>* transitive_interfaces) {
1380 // Count no of interfaces and total number of interface methods
1381 CountInterfacesClosure cic;
1382 visit_all_interfaces(transitive_interfaces, &cic);
1383
1384 // There's alway an extra itable entry so we can null-terminate it.
1385 int itable_size = calc_itable_size(cic.nof_interfaces() + 1, cic.nof_methods());
1386
1387 // Statistics
1388 update_stats(itable_size * wordSize);
1389
1390 return itable_size;
1391 }
1392
1393
1394 // Fill out offset table and interface klasses into the itable space
1395 void klassItable::setup_itable_offset_table(instanceKlassHandle klass) {
1396 if (klass->itable_length() == 0) return;
1397 assert(!klass->is_interface(), "Should have zero length itable");
1398
1399 // Count no of interfaces and total number of interface methods
1400 CountInterfacesClosure cic;
1401 visit_all_interfaces(klass->transitive_interfaces(), &cic);
1402 int nof_methods = cic.nof_methods();
1403 int nof_interfaces = cic.nof_interfaces();
1404
1405 // Add one extra entry so we can null-terminate the table
1406 nof_interfaces++;
1407
1408 assert(compute_itable_size(klass->transitive_interfaces()) ==
1409 calc_itable_size(nof_interfaces, nof_methods),
1410 "mismatch calculation of itable size");
1411
1412 // Fill-out offset table
1413 itableOffsetEntry* ioe = (itableOffsetEntry*)klass->start_of_itable();
1414 itableMethodEntry* ime = (itableMethodEntry*)(ioe + nof_interfaces);
1415 intptr_t* end = klass->end_of_itable();
1416 assert((oop*)(ime + nof_methods) <= (oop*)klass->start_of_nonstatic_oop_maps(), "wrong offset calculation (1)");
1417 assert((oop*)(end) == (oop*)(ime + nof_methods), "wrong offset calculation (2)");
1418
1419 // Visit all interfaces and initialize itable offset table
1420 SetupItableClosure sic((address)klass(), ioe, ime);
1421 visit_all_interfaces(klass->transitive_interfaces(), &sic);
1422
1423 #ifdef ASSERT
1424 ime = sic.method_entry();
1425 oop* v = (oop*) klass->end_of_itable();
1426 assert( (oop*)(ime) == v, "wrong offset calculation (2)");
1427 #endif
1428 }
1429
1430
1431 // inverse to itable_index
1432 Method* klassItable::method_for_itable_index(Klass* intf, int itable_index) {
1433 assert(InstanceKlass::cast(intf)->is_interface(), "sanity check");
1434 assert(intf->verify_itable_index(itable_index), "");
1435 Array<Method*>* methods = InstanceKlass::cast(intf)->methods();
1436
1437 if (itable_index < 0 || itable_index >= method_count_for_interface(intf))
1438 return NULL; // help caller defend against bad indices
1439
1440 int index = itable_index;
1441 Method* m = methods->at(index);
1442 int index2 = -1;
1443 while (!m->has_itable_index() ||
1444 (index2 = m->itable_index()) != itable_index) {
1445 assert(index2 < itable_index, "monotonic");
1446 if (++index == methods->length())
1447 return NULL;
1448 m = methods->at(index);
1449 }
1450 assert(m->itable_index() == itable_index, "correct inverse");
1451
1452 return m;
1453 }
1454
1455 void klassVtable::verify(outputStream* st, bool forced) {
1456 // make sure table is initialized
1457 if (!Universe::is_fully_initialized()) return;
1458 #ifndef PRODUCT
1459 // avoid redundant verifies
1460 if (!forced && _verify_count == Universe::verify_count()) return;
1461 _verify_count = Universe::verify_count();
1462 #endif
1463 oop* end_of_obj = (oop*)_klass() + _klass()->size();
1464 oop* end_of_vtable = (oop *)&table()[_length];
1465 if (end_of_vtable > end_of_obj) {
1466 fatal("klass %s: klass object too short (vtable extends beyond end)",
1467 _klass->internal_name());
1468 }
1469
1470 for (int i = 0; i < _length; i++) table()[i].verify(this, st);
1471 // verify consistency with superKlass vtable
1472 Klass* super = _klass->super();
1473 if (super != NULL) {
1474 InstanceKlass* sk = InstanceKlass::cast(super);
1475 klassVtable* vt = sk->vtable();
1476 for (int i = 0; i < vt->length(); i++) {
1477 verify_against(st, vt, i);
1478 }
1479 }
1480 }
1481
1482 void klassVtable::verify_against(outputStream* st, klassVtable* vt, int index) {
1483 vtableEntry* vte = &vt->table()[index];
1484 if (vte->method()->name() != table()[index].method()->name() ||
1485 vte->method()->signature() != table()[index].method()->signature()) {
1486 fatal("mismatched name/signature of vtable entries");
1487 }
1488 }
1489
1490 #ifndef PRODUCT
1491 void klassVtable::print() {
1492 ResourceMark rm;
1493 tty->print("klassVtable for klass %s (length %d):\n", _klass->internal_name(), length());
1494 for (int i = 0; i < length(); i++) {
1495 table()[i].print();
1496 tty->cr();
1497 }
1498 }
1499 #endif
1500
1501 void vtableEntry::verify(klassVtable* vt, outputStream* st) {
1502 NOT_PRODUCT(FlagSetting fs(IgnoreLockingAssertions, true));
1503 assert(method() != NULL, "must have set method");
1504 method()->verify();
1505 // we sub_type, because it could be a miranda method
1506 if (!vt->klass()->is_subtype_of(method()->method_holder())) {
1507 #ifndef PRODUCT
1508 print();
1509 #endif
1510 fatal("vtableEntry " PTR_FORMAT ": method is from subclass", p2i(this));
1511 }
1512 }
1513
1514 #ifndef PRODUCT
1515
1516 void vtableEntry::print() {
1517 ResourceMark rm;
1518 tty->print("vtableEntry %s: ", method()->name()->as_C_string());
1519 if (Verbose) {
1520 tty->print("m " PTR_FORMAT " ", p2i(method()));
1521 }
1522 }
1523
1524 class VtableStats : AllStatic {
1525 public:
1526 static int no_klasses; // # classes with vtables
1527 static int no_array_klasses; // # array classes
1528 static int no_instance_klasses; // # instanceKlasses
1529 static int sum_of_vtable_len; // total # of vtable entries
1530 static int sum_of_array_vtable_len; // total # of vtable entries in array klasses only
1531 static int fixed; // total fixed overhead in bytes
1532 static int filler; // overhead caused by filler bytes
1533 static int entries; // total bytes consumed by vtable entries
1534 static int array_entries; // total bytes consumed by array vtable entries
1535
1536 static void do_class(Klass* k) {
1537 Klass* kl = k;
1538 klassVtable* vt = kl->vtable();
1539 if (vt == NULL) return;
1540 no_klasses++;
1541 if (kl->is_instance_klass()) {
1542 no_instance_klasses++;
1543 kl->array_klasses_do(do_class);
1544 }
1545 if (kl->is_array_klass()) {
1546 no_array_klasses++;
1547 sum_of_array_vtable_len += vt->length();
1548 }
1549 sum_of_vtable_len += vt->length();
1550 }
1551
1552 static void compute() {
1553 SystemDictionary::classes_do(do_class);
1554 fixed = no_klasses * oopSize; // vtable length
1555 // filler size is a conservative approximation
1556 filler = oopSize * (no_klasses - no_instance_klasses) * (sizeof(InstanceKlass) - sizeof(ArrayKlass) - 1);
1557 entries = sizeof(vtableEntry) * sum_of_vtable_len;
1558 array_entries = sizeof(vtableEntry) * sum_of_array_vtable_len;
1559 }
1560 };
1561
1562 int VtableStats::no_klasses = 0;
1563 int VtableStats::no_array_klasses = 0;
1564 int VtableStats::no_instance_klasses = 0;
1565 int VtableStats::sum_of_vtable_len = 0;
1566 int VtableStats::sum_of_array_vtable_len = 0;
1567 int VtableStats::fixed = 0;
1568 int VtableStats::filler = 0;
1569 int VtableStats::entries = 0;
1570 int VtableStats::array_entries = 0;
1571
1572 void klassVtable::print_statistics() {
1573 ResourceMark rm;
1574 HandleMark hm;
1575 VtableStats::compute();
1576 tty->print_cr("vtable statistics:");
1577 tty->print_cr("%6d classes (%d instance, %d array)", VtableStats::no_klasses, VtableStats::no_instance_klasses, VtableStats::no_array_klasses);
1578 int total = VtableStats::fixed + VtableStats::filler + VtableStats::entries;
1579 tty->print_cr("%6d bytes fixed overhead (refs + vtable object header)", VtableStats::fixed);
1580 tty->print_cr("%6d bytes filler overhead", VtableStats::filler);
1581 tty->print_cr("%6d bytes for vtable entries (%d for arrays)", VtableStats::entries, VtableStats::array_entries);
1582 tty->print_cr("%6d bytes total", total);
1583 }
1584
1585 int klassItable::_total_classes; // Total no. of classes with itables
1586 long klassItable::_total_size; // Total no. of bytes used for itables
1587
1588 void klassItable::print_statistics() {
1589 tty->print_cr("itable statistics:");
1590 tty->print_cr("%6d classes with itables", _total_classes);
1591 tty->print_cr("%6lu K uses for itables (average by class: %ld bytes)", _total_size / K, _total_size / _total_classes);
1592 }
1593
1594 #endif // PRODUCT