1 /*
2 * Copyright (c) 1997, 2013, 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_implementation/shared/markSweep.inline.hpp"
29 #include "memory/gcLocker.hpp"
30 #include "memory/resourceArea.hpp"
31 #include "memory/universe.inline.hpp"
32 #include "oops/instanceKlass.hpp"
33 #include "oops/klassVtable.hpp"
34 #include "oops/method.hpp"
35 #include "oops/objArrayOop.hpp"
36 #include "oops/oop.inline.hpp"
37 #include "prims/jvmtiRedefineClassesTrace.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 Klass* k = _klass();
44 assert(k->oop_is_instance(), "not an InstanceKlass");
45 return (InstanceKlass*)k;
46 }
47
48
49 // this function computes the vtable size (including the size needed for miranda
50 // methods) and the number of miranda methods in this class
51 // Note on Miranda methods: Let's say there is a class C that implements
52 // interface I. Let's say there is a method m in I that neither C nor any
53 // of its super classes implement (i.e there is no method of any access, with
54 // the same name and signature as m), then m is a Miranda method which is
55 // entered as a public abstract method in C's vtable. From then on it should
56 // treated as any other public method in C for method over-ride purposes.
57 void klassVtable::compute_vtable_size_and_num_mirandas(
58 int* vtable_length_ret, int* num_new_mirandas,
59 GrowableArray<Method*>* all_mirandas, Klass* super,
60 Array<Method*>* methods, AccessFlags class_flags,
61 Handle classloader, Symbol* classname, Array<Klass*>* local_interfaces,
62 TRAPS) {
63 No_Safepoint_Verifier nsv;
64
65 // set up default result values
66 int vtable_length = 0;
67
68 // start off with super's vtable length
69 InstanceKlass* sk = (InstanceKlass*)super;
70 vtable_length = super == NULL ? 0 : sk->vtable_length();
71
72 // go thru each method in the methods table to see if it needs a new entry
73 int len = methods->length();
74 for (int i = 0; i < len; i++) {
75 assert(methods->at(i)->is_method(), "must be a Method*");
76 methodHandle mh(THREAD, methods->at(i));
77
78 if (needs_new_vtable_entry(mh, super, classloader, classname, class_flags, THREAD)) {
79 vtable_length += vtableEntry::size(); // we need a new entry
80 }
81 }
82
83 GrowableArray<Method*> new_mirandas(20);
84 // compute the number of mirandas methods that must be added to the end
85 get_mirandas(&new_mirandas, all_mirandas, super, methods, local_interfaces);
86 *num_new_mirandas = new_mirandas.length();
87
88 vtable_length += *num_new_mirandas * vtableEntry::size();
89
90 if (Universe::is_bootstrapping() && vtable_length == 0) {
91 // array classes don't have their superclass set correctly during
92 // bootstrapping
93 vtable_length = Universe::base_vtable_size();
94 }
95
96 if (super == NULL && !Universe::is_bootstrapping() &&
97 vtable_length != Universe::base_vtable_size()) {
98 // Someone is attempting to redefine java.lang.Object incorrectly. The
99 // only way this should happen is from
100 // SystemDictionary::resolve_from_stream(), which will detect this later
101 // and throw a security exception. So don't assert here to let
102 // the exception occur.
103 vtable_length = Universe::base_vtable_size();
104 }
105 assert(super != NULL || vtable_length == Universe::base_vtable_size(),
106 "bad vtable size for class Object");
107 assert(vtable_length % vtableEntry::size() == 0, "bad vtable length");
108 assert(vtable_length >= Universe::base_vtable_size(), "vtable too small");
109
110 *vtable_length_ret = vtable_length;
111 }
112
113 int klassVtable::index_of(Method* m, int len) const {
114 assert(m->vtable_index() >= 0, "do not ask this of non-vtable methods");
115 return m->vtable_index();
116 }
117
118 int klassVtable::initialize_from_super(KlassHandle super) {
119 if (super.is_null()) {
120 return 0;
121 } else {
122 // copy methods from superKlass
123 // can't inherit from array class, so must be InstanceKlass
124 assert(super->oop_is_instance(), "must be instance klass");
125 InstanceKlass* sk = (InstanceKlass*)super();
126 klassVtable* superVtable = sk->vtable();
127 assert(superVtable->length() <= _length, "vtable too short");
128 #ifdef ASSERT
129 superVtable->verify(tty, true);
130 #endif
131 superVtable->copy_vtable_to(table());
132 #ifndef PRODUCT
133 if (PrintVtables && Verbose) {
134 ResourceMark rm;
135 tty->print_cr("copy vtable from %s to %s size %d", sk->internal_name(), klass()->internal_name(), _length);
136 }
137 #endif
138 return superVtable->length();
139 }
140 }
141
142 // Revised lookup semantics introduced 1.3 (Kestral beta)
143 void klassVtable::initialize_vtable(bool checkconstraints, TRAPS) {
144
145 // Note: Arrays can have intermediate array supers. Use java_super to skip them.
146 KlassHandle super (THREAD, klass()->java_super());
147 int nofNewEntries = 0;
148
149
150 if (PrintVtables && !klass()->oop_is_array()) {
151 ResourceMark rm(THREAD);
152 tty->print_cr("Initializing: %s", _klass->name()->as_C_string());
153 }
154
155 #ifdef ASSERT
156 oop* end_of_obj = (oop*)_klass() + _klass()->size();
157 oop* end_of_vtable = (oop*)&table()[_length];
158 assert(end_of_vtable <= end_of_obj, "vtable extends beyond end");
159 #endif
160
161 if (Universe::is_bootstrapping()) {
162 // just clear everything
163 for (int i = 0; i < _length; i++) table()[i].clear();
164 return;
165 }
166
167 int super_vtable_len = initialize_from_super(super);
168 if (klass()->oop_is_array()) {
169 assert(super_vtable_len == _length, "arrays shouldn't introduce new methods");
170 } else {
171 assert(_klass->oop_is_instance(), "must be InstanceKlass");
172
173 Array<Method*>* methods = ik()->methods();
174 int len = methods->length();
175 int initialized = super_vtable_len;
176
177 // update_inherited_vtable can stop for gc - ensure using handles
178 for (int i = 0; i < len; i++) {
179 HandleMark hm(THREAD);
180 assert(methods->at(i)->is_method(), "must be a Method*");
181 methodHandle mh(THREAD, methods->at(i));
182
183 bool needs_new_entry = update_inherited_vtable(ik(), mh, super_vtable_len, checkconstraints, CHECK);
184
185 if (needs_new_entry) {
186 put_method_at(mh(), initialized);
187 mh()->set_vtable_index(initialized); // set primary vtable index
188 initialized++;
189 }
190 }
191
192 // add miranda methods; it will also update the value of initialized
193 fill_in_mirandas(&initialized);
194
195 // In class hierarchies where the accessibility is not increasing (i.e., going from private ->
196 // package_private -> publicprotected), the vtable might actually be smaller than our initial
197 // calculation.
198 assert(initialized <= _length, "vtable initialization failed");
199 for(;initialized < _length; initialized++) {
200 put_method_at(NULL, initialized);
201 }
202 NOT_PRODUCT(verify(tty, true));
203 }
204 }
205
206 // Called for cases where a method does not override its superclass' vtable entry
207 // For bytecodes not produced by javac together it is possible that a method does not override
208 // the superclass's method, but might indirectly override a super-super class's vtable entry
209 // If none found, return a null superk, else return the superk of the method this does override
210 InstanceKlass* klassVtable::find_transitive_override(InstanceKlass* initialsuper, methodHandle target_method,
211 int vtable_index, Handle target_loader, Symbol* target_classname, Thread * THREAD) {
212 InstanceKlass* superk = initialsuper;
213 while (superk != NULL && superk->super() != NULL) {
214 InstanceKlass* supersuperklass = InstanceKlass::cast(superk->super());
215 klassVtable* ssVtable = supersuperklass->vtable();
216 if (vtable_index < ssVtable->length()) {
217 Method* super_method = ssVtable->method_at(vtable_index);
218 #ifndef PRODUCT
219 Symbol* name= target_method()->name();
220 Symbol* signature = target_method()->signature();
221 assert(super_method->name() == name && super_method->signature() == signature, "vtable entry name/sig mismatch");
222 #endif
223 if (supersuperklass->is_override(super_method, target_loader, target_classname, THREAD)) {
224 #ifndef PRODUCT
225 if (PrintVtables && Verbose) {
226 ResourceMark rm(THREAD);
227 tty->print("transitive overriding superclass %s with %s::%s index %d, original flags: ",
228 supersuperklass->internal_name(),
229 _klass->internal_name(), (target_method() != NULL) ?
230 target_method()->name()->as_C_string() : "<NULL>", vtable_index);
231 super_method->access_flags().print_on(tty);
232 tty->print("overriders flags: ");
233 target_method->access_flags().print_on(tty);
234 tty->cr();
235 }
236 #endif /*PRODUCT*/
237 break; // return found superk
238 }
239 } else {
240 // super class has no vtable entry here, stop transitive search
241 superk = (InstanceKlass*)NULL;
242 break;
243 }
244 // if no override found yet, continue to search up
245 superk = InstanceKlass::cast(superk->super());
246 }
247
248 return superk;
249 }
250
251 // Methods that are "effectively" final don't need vtable entries.
252 bool method_is_effectively_final(
253 AccessFlags klass_flags, methodHandle target) {
254 return target->is_final() || klass_flags.is_final() && !target->is_overpass();
255 }
256
257 // Update child's copy of super vtable for overrides
258 // OR return true if a new vtable entry is required
259 // Only called for InstanceKlass's, i.e. not for arrays
260 // If that changed, could not use _klass as handle for klass
261 bool klassVtable::update_inherited_vtable(InstanceKlass* klass, methodHandle target_method, int super_vtable_len,
262 bool checkconstraints, TRAPS) {
263 ResourceMark rm;
264 bool allocate_new = true;
265 assert(klass->oop_is_instance(), "must be InstanceKlass");
266
267 // Initialize the method's vtable index to "nonvirtual".
268 // If we allocate a vtable entry, we will update it to a non-negative number.
269 target_method()->set_vtable_index(Method::nonvirtual_vtable_index);
270
271 // Static and <init> methods are never in
272 if (target_method()->is_static() || target_method()->name() == vmSymbols::object_initializer_name()) {
273 return false;
274 }
275
276 if (method_is_effectively_final(klass->access_flags(), target_method)) {
277 // a final method never needs a new entry; final methods can be statically
278 // resolved and they have to be present in the vtable only if they override
279 // a super's method, in which case they re-use its entry
280 allocate_new = false;
281 }
282
283 // we need a new entry if there is no superclass
284 if (klass->super() == NULL) {
285 return allocate_new;
286 }
287
288 // private methods always have a new entry in the vtable
289 // specification interpretation since classic has
290 // private methods not overriding
291 if (target_method()->is_private()) {
292 return allocate_new;
293 }
294
295 // search through the vtable and update overridden entries
296 // Since check_signature_loaders acquires SystemDictionary_lock
297 // which can block for gc, once we are in this loop, use handles
298 // For classfiles built with >= jdk7, we now look for transitive overrides
299
300 Symbol* name = target_method()->name();
301 Symbol* signature = target_method()->signature();
302 Handle target_loader(THREAD, _klass()->class_loader());
303 Symbol* target_classname = _klass->name();
304 for(int i = 0; i < super_vtable_len; i++) {
305 Method* super_method = method_at(i);
306 // Check if method name matches
307 if (super_method->name() == name && super_method->signature() == signature) {
308
309 // get super_klass for method_holder for the found method
310 InstanceKlass* super_klass = super_method->method_holder();
311
312 if ((super_klass->is_override(super_method, target_loader, target_classname, THREAD)) ||
313 ((klass->major_version() >= VTABLE_TRANSITIVE_OVERRIDE_VERSION)
314 && ((super_klass = find_transitive_override(super_klass, target_method, i, target_loader,
315 target_classname, THREAD)) != (InstanceKlass*)NULL))) {
316 // overriding, so no new entry
317 allocate_new = false;
318
319 if (checkconstraints) {
320 // Override vtable entry if passes loader constraint check
321 // if loader constraint checking requested
322 // No need to visit his super, since he and his super
323 // have already made any needed loader constraints.
324 // Since loader constraints are transitive, it is enough
325 // to link to the first super, and we get all the others.
326 Handle super_loader(THREAD, super_klass->class_loader());
327
328 if (target_loader() != super_loader()) {
329 ResourceMark rm(THREAD);
330 Symbol* failed_type_symbol =
331 SystemDictionary::check_signature_loaders(signature, target_loader,
332 super_loader, true,
333 CHECK_(false));
334 if (failed_type_symbol != NULL) {
335 const char* msg = "loader constraint violation: when resolving "
336 "overridden method \"%s\" the class loader (instance"
337 " of %s) of the current class, %s, and its superclass loader "
338 "(instance of %s), have different Class objects for the type "
339 "%s used in the signature";
340 char* sig = target_method()->name_and_sig_as_C_string();
341 const char* loader1 = SystemDictionary::loader_name(target_loader());
342 char* current = _klass->name()->as_C_string();
343 const char* loader2 = SystemDictionary::loader_name(super_loader());
344 char* failed_type_name = failed_type_symbol->as_C_string();
345 size_t buflen = strlen(msg) + strlen(sig) + strlen(loader1) +
346 strlen(current) + strlen(loader2) + strlen(failed_type_name);
347 char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen);
348 jio_snprintf(buf, buflen, msg, sig, loader1, current, loader2,
349 failed_type_name);
350 THROW_MSG_(vmSymbols::java_lang_LinkageError(), buf, false);
351 }
352 }
353 }
354
355 put_method_at(target_method(), i);
356 target_method()->set_vtable_index(i);
357 #ifndef PRODUCT
358 if (PrintVtables && Verbose) {
359 tty->print("overriding with %s::%s index %d, original flags: ",
360 _klass->internal_name(), (target_method() != NULL) ?
361 target_method()->name()->as_C_string() : "<NULL>", i);
362 super_method->access_flags().print_on(tty);
363 tty->print("overriders flags: ");
364 target_method->access_flags().print_on(tty);
365 tty->cr();
366 }
367 #endif /*PRODUCT*/
368 } else {
369 // allocate_new = true; default. We might override one entry,
370 // but not override another. Once we override one, not need new
371 #ifndef PRODUCT
372 if (PrintVtables && Verbose) {
373 tty->print("NOT overriding with %s::%s index %d, original flags: ",
374 _klass->internal_name(), (target_method() != NULL) ?
375 target_method()->name()->as_C_string() : "<NULL>", i);
376 super_method->access_flags().print_on(tty);
377 tty->print("overriders flags: ");
378 target_method->access_flags().print_on(tty);
379 tty->cr();
380 }
381 #endif /*PRODUCT*/
382 }
383 }
384 }
385 return allocate_new;
386 }
387
388 void klassVtable::put_method_at(Method* m, int index) {
389 #ifndef PRODUCT
390 if (PrintVtables && Verbose) {
391 ResourceMark rm;
392 tty->print_cr("adding %s::%s at index %d", _klass->internal_name(),
393 (m != NULL) ? m->name()->as_C_string() : "<NULL>", index);
394 }
395 #endif
396 table()[index].set(m);
397 }
398
399 // Find out if a method "m" with superclass "super", loader "classloader" and
400 // name "classname" needs a new vtable entry. Let P be a class package defined
401 // by "classloader" and "classname".
402 // NOTE: The logic used here is very similar to the one used for computing
403 // the vtables indices for a method. We cannot directly use that function because,
404 // we allocate the InstanceKlass at load time, and that requires that the
405 // superclass has been loaded.
406 // However, the vtable entries are filled in at link time, and therefore
407 // the superclass' vtable may not yet have been filled in.
408 bool klassVtable::needs_new_vtable_entry(methodHandle target_method,
409 Klass* super,
410 Handle classloader,
411 Symbol* classname,
412 AccessFlags class_flags,
413 TRAPS) {
414
415 if (method_is_effectively_final(class_flags, target_method) ||
416 // a final method never needs a new entry; final methods can be statically
417 // resolved and they have to be present in the vtable only if they override
418 // a super's method, in which case they re-use its entry
419 (target_method()->is_static()) ||
420 // static methods don't need to be in vtable
421 (target_method()->name() == vmSymbols::object_initializer_name())
422 // <init> is never called dynamically-bound
423 ) {
424 return false;
425 }
426
427 // we need a new entry if there is no superclass
428 if (super == NULL) {
429 return true;
430 }
431
432 // private methods always have a new entry in the vtable
433 // specification interpretation since classic has
434 // private methods not overriding
435 if (target_method()->is_private()) {
436 return true;
437 }
438
439 // search through the super class hierarchy to see if we need
440 // a new entry
441 ResourceMark rm;
442 Symbol* name = target_method()->name();
443 Symbol* signature = target_method()->signature();
444 Klass* k = super;
445 Method* super_method = NULL;
446 InstanceKlass *holder = NULL;
447 Method* recheck_method = NULL;
448 while (k != NULL) {
449 // lookup through the hierarchy for a method with matching name and sign.
450 super_method = InstanceKlass::cast(k)->lookup_method(name, signature);
451 if (super_method == NULL) {
452 break; // we still have to search for a matching miranda method
453 }
454 // get the class holding the matching method
455 // make sure you use that class for is_override
456 InstanceKlass* superk = super_method->method_holder();
457 // we want only instance method matches
458 // pretend private methods are not in the super vtable
459 // since we do override around them: e.g. a.m pub/b.m private/c.m pub,
460 // ignore private, c.m pub does override a.m pub
461 // For classes that were not javac'd together, we also do transitive overriding around
462 // methods that have less accessibility
463 if ((!super_method->is_static()) &&
464 (!super_method->is_private())) {
465 if (superk->is_override(super_method, classloader, classname, THREAD)) {
466 return false;
467 // else keep looking for transitive overrides
468 }
469 }
470
471 // Start with lookup result and continue to search up
472 k = superk->super(); // haven't found an override match yet; continue to look
473 }
474
475 // if the target method is public or protected it may have a matching
476 // miranda method in the super, whose entry it should re-use.
477 // Actually, to handle cases that javac would not generate, we need
478 // this check for all access permissions.
479 InstanceKlass *sk = InstanceKlass::cast(super);
480 if (sk->has_miranda_methods()) {
481 if (sk->lookup_method_in_all_interfaces(name, signature) != NULL) {
482 return false; // found a matching miranda; we do not need a new entry
483 }
484 }
485 return true; // found no match; we need a new entry
486 }
487
488 // Support for miranda methods
489
490 // get the vtable index of a miranda method with matching "name" and "signature"
491 int klassVtable::index_of_miranda(Symbol* name, Symbol* signature) {
492 // search from the bottom, might be faster
493 for (int i = (length() - 1); i >= 0; i--) {
494 Method* m = table()[i].method();
495 if (is_miranda_entry_at(i) &&
496 m->name() == name && m->signature() == signature) {
497 return i;
498 }
499 }
500 return Method::invalid_vtable_index;
501 }
502
503 // check if an entry is miranda
504 bool klassVtable::is_miranda_entry_at(int i) {
505 Method* m = method_at(i);
506 Klass* method_holder = m->method_holder();
507 InstanceKlass *mhk = InstanceKlass::cast(method_holder);
508
509 // miranda methods are interface methods in a class's vtable
510 if (mhk->is_interface()) {
511 assert(m->is_public(), "should be public");
512 assert(ik()->implements_interface(method_holder) , "this class should implement the interface");
513 assert(is_miranda(m, ik()->methods(), ik()->super()), "should be a miranda_method");
514 return true;
515 }
516 return false;
517 }
518
519 // check if a method is a miranda method, given a class's methods table and it's super
520 // the caller must make sure that the method belongs to an interface implemented by the class
521 bool klassVtable::is_miranda(Method* m, Array<Method*>* class_methods, Klass* super) {
522 if (m->is_static()) {
523 return false;
524 }
525 Symbol* name = m->name();
526 Symbol* signature = m->signature();
527 if (InstanceKlass::find_method(class_methods, name, signature) == NULL) {
528 // did not find it in the method table of the current class
529 if (super == NULL) {
530 // super doesn't exist
531 return true;
532 }
533
534 Method* mo = InstanceKlass::cast(super)->lookup_method(name, signature);
535 if (mo == NULL || mo->access_flags().is_private() ) {
536 // super class hierarchy does not implement it or protection is different
537 return true;
538 }
539 }
540
541 return false;
542 }
543
544 void klassVtable::add_new_mirandas_to_lists(
545 GrowableArray<Method*>* new_mirandas, GrowableArray<Method*>* all_mirandas,
546 Array<Method*>* current_interface_methods, Array<Method*>* class_methods,
547 Klass* super) {
548 // iterate thru the current interface's method to see if it a miranda
549 int num_methods = current_interface_methods->length();
550 for (int i = 0; i < num_methods; i++) {
551 Method* im = current_interface_methods->at(i);
552 bool is_duplicate = false;
553 int num_of_current_mirandas = new_mirandas->length();
554 // check for duplicate mirandas in different interfaces we implement
555 for (int j = 0; j < num_of_current_mirandas; j++) {
556 Method* miranda = new_mirandas->at(j);
557 if ((im->name() == miranda->name()) &&
558 (im->signature() == miranda->signature())) {
559 is_duplicate = true;
560 break;
561 }
562 }
563
564 if (!is_duplicate) { // we don't want duplicate miranda entries in the vtable
565 if (is_miranda(im, class_methods, super)) { // is it a miranda at all?
566 InstanceKlass *sk = InstanceKlass::cast(super);
567 // check if it is a duplicate of a super's miranda
568 if (sk->lookup_method_in_all_interfaces(im->name(), im->signature()) == NULL) {
569 new_mirandas->append(im);
570 }
571 if (all_mirandas != NULL) {
572 all_mirandas->append(im);
573 }
574 }
575 }
576 }
577 }
578
579 void klassVtable::get_mirandas(GrowableArray<Method*>* new_mirandas,
580 GrowableArray<Method*>* all_mirandas,
581 Klass* super, Array<Method*>* class_methods,
582 Array<Klass*>* local_interfaces) {
583 assert((new_mirandas->length() == 0) , "current mirandas must be 0");
584
585 // iterate thru the local interfaces looking for a miranda
586 int num_local_ifs = local_interfaces->length();
587 for (int i = 0; i < num_local_ifs; i++) {
588 InstanceKlass *ik = InstanceKlass::cast(local_interfaces->at(i));
589 add_new_mirandas_to_lists(new_mirandas, all_mirandas,
590 ik->methods(), class_methods, super);
591 // iterate thru each local's super interfaces
592 Array<Klass*>* super_ifs = ik->transitive_interfaces();
593 int num_super_ifs = super_ifs->length();
594 for (int j = 0; j < num_super_ifs; j++) {
595 InstanceKlass *sik = InstanceKlass::cast(super_ifs->at(j));
596 add_new_mirandas_to_lists(new_mirandas, all_mirandas,
597 sik->methods(), class_methods, super);
598 }
599 }
600 }
601
602 // fill in mirandas
603 void klassVtable::fill_in_mirandas(int* initialized) {
604 GrowableArray<Method*> mirandas(20);
605 get_mirandas(&mirandas, NULL, ik()->super(), ik()->methods(),
606 ik()->local_interfaces());
607 for (int i = 0; i < mirandas.length(); i++) {
608 put_method_at(mirandas.at(i), *initialized);
609 ++(*initialized);
610 }
611 }
612
613 void klassVtable::copy_vtable_to(vtableEntry* start) {
614 Copy::disjoint_words((HeapWord*)table(), (HeapWord*)start, _length * vtableEntry::size());
615 }
616
617 #if INCLUDE_JVMTI
618 void klassVtable::adjust_method_entries(Method** old_methods, Method** new_methods,
619 int methods_length, bool * trace_name_printed) {
620 // search the vtable for uses of either obsolete or EMCP methods
621 for (int j = 0; j < methods_length; j++) {
622 Method* old_method = old_methods[j];
623 Method* new_method = new_methods[j];
624
625 // In the vast majority of cases we could get the vtable index
626 // by using: old_method->vtable_index()
627 // However, there are rare cases, eg. sun.awt.X11.XDecoratedPeer.getX()
628 // in sun.awt.X11.XFramePeer where methods occur more than once in the
629 // vtable, so, alas, we must do an exhaustive search.
630 for (int index = 0; index < length(); index++) {
631 if (unchecked_method_at(index) == old_method) {
632 put_method_at(new_method, index);
633
634 if (RC_TRACE_IN_RANGE(0x00100000, 0x00400000)) {
635 if (!(*trace_name_printed)) {
636 // RC_TRACE_MESG macro has an embedded ResourceMark
637 RC_TRACE_MESG(("adjust: name=%s",
638 old_method->method_holder()->external_name()));
639 *trace_name_printed = true;
640 }
641 // RC_TRACE macro has an embedded ResourceMark
642 RC_TRACE(0x00100000, ("vtable method update: %s(%s)",
643 new_method->name()->as_C_string(),
644 new_method->signature()->as_C_string()));
645 }
646 // cannot 'break' here; see for-loop comment above.
647 }
648 }
649 }
650 }
651
652 // a vtable should never contain old or obsolete methods
653 bool klassVtable::check_no_old_or_obsolete_entries() {
654 for (int i = 0; i < length(); i++) {
655 Method* m = unchecked_method_at(i);
656 if (m != NULL &&
657 (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) {
658 return false;
659 }
660 }
661 return true;
662 }
663
664 void klassVtable::dump_vtable() {
665 tty->print_cr("vtable dump --");
666 for (int i = 0; i < length(); i++) {
667 Method* m = unchecked_method_at(i);
668 if (m != NULL) {
669 tty->print(" (%5d) ", i);
670 m->access_flags().print_on(tty);
671 tty->print(" -- ");
672 m->print_name(tty);
673 tty->cr();
674 }
675 }
676 }
677 #endif // INCLUDE_JVMTI
678
679 // CDS/RedefineClasses support - clear vtables so they can be reinitialized
680 void klassVtable::clear_vtable() {
681 for (int i = 0; i < _length; i++) table()[i].clear();
682 }
683
684 bool klassVtable::is_initialized() {
685 return _length == 0 || table()[0].method() != NULL;
686 }
687
688 //-----------------------------------------------------------------------------------------
689 // Itable code
690
691 // Initialize a itableMethodEntry
692 void itableMethodEntry::initialize(Method* m) {
693 if (m == NULL) return;
694
695 _method = m;
696 }
697
698 klassItable::klassItable(instanceKlassHandle klass) {
699 _klass = klass;
700
701 if (klass->itable_length() > 0) {
702 itableOffsetEntry* offset_entry = (itableOffsetEntry*)klass->start_of_itable();
703 if (offset_entry != NULL && offset_entry->interface_klass() != NULL) { // Check that itable is initialized
704 // First offset entry points to the first method_entry
705 intptr_t* method_entry = (intptr_t *)(((address)klass()) + offset_entry->offset());
706 intptr_t* end = klass->end_of_itable();
707
708 _table_offset = (intptr_t*)offset_entry - (intptr_t*)klass();
709 _size_offset_table = (method_entry - ((intptr_t*)offset_entry)) / itableOffsetEntry::size();
710 _size_method_table = (end - method_entry) / itableMethodEntry::size();
711 assert(_table_offset >= 0 && _size_offset_table >= 0 && _size_method_table >= 0, "wrong computation");
712 return;
713 }
714 }
715
716 // The length of the itable was either zero, or it has not yet been initialized.
717 _table_offset = 0;
718 _size_offset_table = 0;
719 _size_method_table = 0;
720 }
721
722 static int initialize_count = 0;
723
724 // Initialization
725 void klassItable::initialize_itable(bool checkconstraints, TRAPS) {
726 // Cannot be setup doing bootstrapping, interfaces don't have
727 // itables, and klass with only ones entry have empty itables
728 if (Universe::is_bootstrapping() ||
729 _klass->is_interface() ||
730 _klass->itable_length() == itableOffsetEntry::size()) return;
731
732 // There's alway an extra itable entry so we can null-terminate it.
733 guarantee(size_offset_table() >= 1, "too small");
734 int num_interfaces = size_offset_table() - 1;
735 if (num_interfaces > 0) {
736 if (TraceItables) tty->print_cr("%3d: Initializing itables for %s", ++initialize_count,
737 _klass->name()->as_C_string());
738
739
740 // Iterate through all interfaces
741 int i;
742 for(i = 0; i < num_interfaces; i++) {
743 itableOffsetEntry* ioe = offset_entry(i);
744 HandleMark hm(THREAD);
745 KlassHandle interf_h (THREAD, ioe->interface_klass());
746 assert(interf_h() != NULL && ioe->offset() != 0, "bad offset entry in itable");
747 initialize_itable_for_interface(ioe->offset(), interf_h, checkconstraints, CHECK);
748 }
749
750 }
751 // Check that the last entry is empty
752 itableOffsetEntry* ioe = offset_entry(size_offset_table() - 1);
753 guarantee(ioe->interface_klass() == NULL && ioe->offset() == 0, "terminator entry missing");
754 }
755
756
757 void klassItable::initialize_itable_for_interface(int method_table_offset, KlassHandle interf_h, bool checkconstraints, TRAPS) {
758 Array<Method*>* methods = InstanceKlass::cast(interf_h())->methods();
759 int nof_methods = methods->length();
760 HandleMark hm;
761 KlassHandle klass = _klass;
762 assert(nof_methods > 0, "at least one method must exist for interface to be in vtable");
763 Handle interface_loader (THREAD, InstanceKlass::cast(interf_h())->class_loader());
764 int ime_num = 0;
765
766 // Skip first Method* if it is a class initializer
767 int i = methods->at(0)->is_static_initializer() ? 1 : 0;
768
769 // m, method_name, method_signature, klass reset each loop so they
770 // don't need preserving across check_signature_loaders call
771 // methods needs a handle in case of gc from check_signature_loaders
772 for(; i < nof_methods; i++) {
773 Method* m = methods->at(i);
774 Symbol* method_name = m->name();
775 Symbol* method_signature = m->signature();
776
777 // This is same code as in Linkresolver::lookup_instance_method_in_klasses
778 Method* target = klass->uncached_lookup_method(method_name, method_signature);
779 while (target != NULL && target->is_static()) {
780 // continue with recursive lookup through the superclass
781 Klass* super = target->method_holder()->super();
782 target = (super == NULL) ? (Method*)NULL : super->uncached_lookup_method(method_name, method_signature);
783 }
784 if (target == NULL || !target->is_public() || target->is_abstract()) {
785 // Entry do not resolve. Leave it empty
786 } else {
787 // Entry did resolve, check loader constraints before initializing
788 // if checkconstraints requested
789 methodHandle target_h (THREAD, target); // preserve across gc
790 if (checkconstraints) {
791 Handle method_holder_loader (THREAD, target->method_holder()->class_loader());
792 if (method_holder_loader() != interface_loader()) {
793 ResourceMark rm(THREAD);
794 Symbol* failed_type_symbol =
795 SystemDictionary::check_signature_loaders(method_signature,
796 method_holder_loader,
797 interface_loader,
798 true, CHECK);
799 if (failed_type_symbol != NULL) {
800 const char* msg = "loader constraint violation in interface "
801 "itable initialization: when resolving method \"%s\" the class"
802 " loader (instance of %s) of the current class, %s, "
803 "and the class loader (instance of %s) for interface "
804 "%s have different Class objects for the type %s "
805 "used in the signature";
806 char* sig = target_h()->name_and_sig_as_C_string();
807 const char* loader1 = SystemDictionary::loader_name(method_holder_loader());
808 char* current = klass->name()->as_C_string();
809 const char* loader2 = SystemDictionary::loader_name(interface_loader());
810 char* iface = InstanceKlass::cast(interf_h())->name()->as_C_string();
811 char* failed_type_name = failed_type_symbol->as_C_string();
812 size_t buflen = strlen(msg) + strlen(sig) + strlen(loader1) +
813 strlen(current) + strlen(loader2) + strlen(iface) +
814 strlen(failed_type_name);
815 char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen);
816 jio_snprintf(buf, buflen, msg, sig, loader1, current, loader2,
817 iface, failed_type_name);
818 THROW_MSG(vmSymbols::java_lang_LinkageError(), buf);
819 }
820 }
821 }
822
823 // ime may have moved during GC so recalculate address
824 itableOffsetEntry::method_entry(_klass(), method_table_offset)[ime_num].initialize(target_h());
825 }
826 // Progress to next entry
827 ime_num++;
828 }
829 }
830
831 // Update entry for specific Method*
832 void klassItable::initialize_with_method(Method* m) {
833 itableMethodEntry* ime = method_entry(0);
834 for(int i = 0; i < _size_method_table; i++) {
835 if (ime->method() == m) {
836 ime->initialize(m);
837 }
838 ime++;
839 }
840 }
841
842 #if INCLUDE_JVMTI
843 void klassItable::adjust_method_entries(Method** old_methods, Method** new_methods,
844 int methods_length, bool * trace_name_printed) {
845 // search the itable for uses of either obsolete or EMCP methods
846 for (int j = 0; j < methods_length; j++) {
847 Method* old_method = old_methods[j];
848 Method* new_method = new_methods[j];
849 itableMethodEntry* ime = method_entry(0);
850
851 // The itable can describe more than one interface and the same
852 // method signature can be specified by more than one interface.
853 // This means we have to do an exhaustive search to find all the
854 // old_method references.
855 for (int i = 0; i < _size_method_table; i++) {
856 if (ime->method() == old_method) {
857 ime->initialize(new_method);
858
859 if (RC_TRACE_IN_RANGE(0x00100000, 0x00400000)) {
860 if (!(*trace_name_printed)) {
861 // RC_TRACE_MESG macro has an embedded ResourceMark
862 RC_TRACE_MESG(("adjust: name=%s",
863 old_method->method_holder()->external_name()));
864 *trace_name_printed = true;
865 }
866 // RC_TRACE macro has an embedded ResourceMark
867 RC_TRACE(0x00200000, ("itable method update: %s(%s)",
868 new_method->name()->as_C_string(),
869 new_method->signature()->as_C_string()));
870 }
871 // cannot 'break' here; see for-loop comment above.
872 }
873 ime++;
874 }
875 }
876 }
877
878 // an itable should never contain old or obsolete methods
879 bool klassItable::check_no_old_or_obsolete_entries() {
880 itableMethodEntry* ime = method_entry(0);
881 for (int i = 0; i < _size_method_table; i++) {
882 Method* m = ime->method();
883 if (m != NULL &&
884 (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) {
885 return false;
886 }
887 ime++;
888 }
889 return true;
890 }
891
892 void klassItable::dump_itable() {
893 itableMethodEntry* ime = method_entry(0);
894 tty->print_cr("itable dump --");
895 for (int i = 0; i < _size_method_table; i++) {
896 Method* m = ime->method();
897 if (m != NULL) {
898 tty->print(" (%5d) ", i);
899 m->access_flags().print_on(tty);
900 tty->print(" -- ");
901 m->print_name(tty);
902 tty->cr();
903 }
904 ime++;
905 }
906 }
907 #endif // INCLUDE_JVMTI
908
909
910 // Setup
911 class InterfaceVisiterClosure : public StackObj {
912 public:
913 virtual void doit(Klass* intf, int method_count) = 0;
914 };
915
916 // Visit all interfaces with at-least one method (excluding <clinit>)
917 void visit_all_interfaces(Array<Klass*>* transitive_intf, InterfaceVisiterClosure *blk) {
918 // Handle array argument
919 for(int i = 0; i < transitive_intf->length(); i++) {
920 Klass* intf = transitive_intf->at(i);
921 assert(intf->is_interface(), "sanity check");
922
923 // Find no. of methods excluding a <clinit>
924 int method_count = InstanceKlass::cast(intf)->methods()->length();
925 if (method_count > 0) {
926 Method* m = InstanceKlass::cast(intf)->methods()->at(0);
927 assert(m != NULL && m->is_method(), "sanity check");
928 if (m->name() == vmSymbols::object_initializer_name()) {
929 method_count--;
930 }
931 }
932
933 // Only count interfaces with at least one method
934 if (method_count > 0) {
935 blk->doit(intf, method_count);
936 }
937 }
938 }
939
940 class CountInterfacesClosure : public InterfaceVisiterClosure {
941 private:
942 int _nof_methods;
943 int _nof_interfaces;
944 public:
945 CountInterfacesClosure() { _nof_methods = 0; _nof_interfaces = 0; }
946
947 int nof_methods() const { return _nof_methods; }
948 int nof_interfaces() const { return _nof_interfaces; }
949
950 void doit(Klass* intf, int method_count) { _nof_methods += method_count; _nof_interfaces++; }
951 };
952
953 class SetupItableClosure : public InterfaceVisiterClosure {
954 private:
955 itableOffsetEntry* _offset_entry;
956 itableMethodEntry* _method_entry;
957 address _klass_begin;
958 public:
959 SetupItableClosure(address klass_begin, itableOffsetEntry* offset_entry, itableMethodEntry* method_entry) {
960 _klass_begin = klass_begin;
961 _offset_entry = offset_entry;
962 _method_entry = method_entry;
963 }
964
965 itableMethodEntry* method_entry() const { return _method_entry; }
966
967 void doit(Klass* intf, int method_count) {
968 int offset = ((address)_method_entry) - _klass_begin;
969 _offset_entry->initialize(intf, offset);
970 _offset_entry++;
971 _method_entry += method_count;
972 }
973 };
974
975 int klassItable::compute_itable_size(Array<Klass*>* transitive_interfaces) {
976 // Count no of interfaces and total number of interface methods
977 CountInterfacesClosure cic;
978 visit_all_interfaces(transitive_interfaces, &cic);
979
980 // There's alway an extra itable entry so we can null-terminate it.
981 int itable_size = calc_itable_size(cic.nof_interfaces() + 1, cic.nof_methods());
982
983 // Statistics
984 update_stats(itable_size * HeapWordSize);
985
986 return itable_size;
987 }
988
989
990 // Fill out offset table and interface klasses into the itable space
991 void klassItable::setup_itable_offset_table(instanceKlassHandle klass) {
992 if (klass->itable_length() == 0) return;
993 assert(!klass->is_interface(), "Should have zero length itable");
994
995 // Count no of interfaces and total number of interface methods
996 CountInterfacesClosure cic;
997 visit_all_interfaces(klass->transitive_interfaces(), &cic);
998 int nof_methods = cic.nof_methods();
999 int nof_interfaces = cic.nof_interfaces();
1000
1001 // Add one extra entry so we can null-terminate the table
1002 nof_interfaces++;
1003
1004 assert(compute_itable_size(klass->transitive_interfaces()) ==
1005 calc_itable_size(nof_interfaces, nof_methods),
1006 "mismatch calculation of itable size");
1007
1008 // Fill-out offset table
1009 itableOffsetEntry* ioe = (itableOffsetEntry*)klass->start_of_itable();
1010 itableMethodEntry* ime = (itableMethodEntry*)(ioe + nof_interfaces);
1011 intptr_t* end = klass->end_of_itable();
1012 assert((oop*)(ime + nof_methods) <= (oop*)klass->start_of_nonstatic_oop_maps(), "wrong offset calculation (1)");
1013 assert((oop*)(end) == (oop*)(ime + nof_methods), "wrong offset calculation (2)");
1014
1015 // Visit all interfaces and initialize itable offset table
1016 SetupItableClosure sic((address)klass(), ioe, ime);
1017 visit_all_interfaces(klass->transitive_interfaces(), &sic);
1018
1019 #ifdef ASSERT
1020 ime = sic.method_entry();
1021 oop* v = (oop*) klass->end_of_itable();
1022 assert( (oop*)(ime) == v, "wrong offset calculation (2)");
1023 #endif
1024 }
1025
1026
1027 // m must be a method in an interface
1028 int klassItable::compute_itable_index(Method* m) {
1029 InstanceKlass* intf = m->method_holder();
1030 assert(intf->is_interface(), "sanity check");
1031 Array<Method*>* methods = intf->methods();
1032 int index = 0;
1033 while(methods->at(index) != m) {
1034 index++;
1035 assert(index < methods->length(), "should find index for resolve_invoke");
1036 }
1037 // Adjust for <clinit>, which is left out of table if first method
1038 if (methods->length() > 0 && methods->at(0)->is_static_initializer()) {
1039 index--;
1040 }
1041 return index;
1042 }
1043
1044
1045 // inverse to compute_itable_index
1046 Method* klassItable::method_for_itable_index(Klass* intf, int itable_index) {
1047 assert(InstanceKlass::cast(intf)->is_interface(), "sanity check");
1048 Array<Method*>* methods = InstanceKlass::cast(intf)->methods();
1049
1050 int index = itable_index;
1051 // Adjust for <clinit>, which is left out of table if first method
1052 if (methods->length() > 0 && methods->at(0)->is_static_initializer()) {
1053 index++;
1054 }
1055
1056 if (itable_index < 0 || index >= methods->length())
1057 return NULL; // help caller defend against bad indexes
1058
1059 Method* m = methods->at(index);
1060 assert(compute_itable_index(m) == itable_index, "correct inverse");
1061
1062 return m;
1063 }
1064
1065 void klassVtable::verify(outputStream* st, bool forced) {
1066 // make sure table is initialized
1067 if (!Universe::is_fully_initialized()) return;
1068 #ifndef PRODUCT
1069 // avoid redundant verifies
1070 if (!forced && _verify_count == Universe::verify_count()) return;
1071 _verify_count = Universe::verify_count();
1072 #endif
1073 oop* end_of_obj = (oop*)_klass() + _klass()->size();
1074 oop* end_of_vtable = (oop *)&table()[_length];
1075 if (end_of_vtable > end_of_obj) {
1076 fatal(err_msg("klass %s: klass object too short (vtable extends beyond "
1077 "end)", _klass->internal_name()));
1078 }
1079
1080 for (int i = 0; i < _length; i++) table()[i].verify(this, st);
1081 // verify consistency with superKlass vtable
1082 Klass* super = _klass->super();
1083 if (super != NULL) {
1084 InstanceKlass* sk = InstanceKlass::cast(super);
1085 klassVtable* vt = sk->vtable();
1086 for (int i = 0; i < vt->length(); i++) {
1087 verify_against(st, vt, i);
1088 }
1089 }
1090 }
1091
1092 void klassVtable::verify_against(outputStream* st, klassVtable* vt, int index) {
1093 vtableEntry* vte = &vt->table()[index];
1094 if (vte->method()->name() != table()[index].method()->name() ||
1095 vte->method()->signature() != table()[index].method()->signature()) {
1096 fatal("mismatched name/signature of vtable entries");
1097 }
1098 }
1099
1100 #ifndef PRODUCT
1101 void klassVtable::print() {
1102 ResourceMark rm;
1103 tty->print("klassVtable for klass %s (length %d):\n", _klass->internal_name(), length());
1104 for (int i = 0; i < length(); i++) {
1105 table()[i].print();
1106 tty->cr();
1107 }
1108 }
1109 #endif
1110
1111 void vtableEntry::verify(klassVtable* vt, outputStream* st) {
1112 NOT_PRODUCT(FlagSetting fs(IgnoreLockingAssertions, true));
1113 assert(method() != NULL, "must have set method");
1114 method()->verify();
1115 // we sub_type, because it could be a miranda method
1116 if (!vt->klass()->is_subtype_of(method()->method_holder())) {
1117 #ifndef PRODUCT
1118 print();
1119 #endif
1120 fatal(err_msg("vtableEntry " PTR_FORMAT ": method is from subclass", this));
1121 }
1122 }
1123
1124 #ifndef PRODUCT
1125
1126 void vtableEntry::print() {
1127 ResourceMark rm;
1128 tty->print("vtableEntry %s: ", method()->name()->as_C_string());
1129 if (Verbose) {
1130 tty->print("m %#lx ", (address)method());
1131 }
1132 }
1133
1134 class VtableStats : AllStatic {
1135 public:
1136 static int no_klasses; // # classes with vtables
1137 static int no_array_klasses; // # array classes
1138 static int no_instance_klasses; // # instanceKlasses
1139 static int sum_of_vtable_len; // total # of vtable entries
1140 static int sum_of_array_vtable_len; // total # of vtable entries in array klasses only
1141 static int fixed; // total fixed overhead in bytes
1142 static int filler; // overhead caused by filler bytes
1143 static int entries; // total bytes consumed by vtable entries
1144 static int array_entries; // total bytes consumed by array vtable entries
1145
1146 static void do_class(Klass* k) {
1147 Klass* kl = k;
1148 klassVtable* vt = kl->vtable();
1149 if (vt == NULL) return;
1150 no_klasses++;
1151 if (kl->oop_is_instance()) {
1152 no_instance_klasses++;
1153 kl->array_klasses_do(do_class);
1154 }
1155 if (kl->oop_is_array()) {
1156 no_array_klasses++;
1157 sum_of_array_vtable_len += vt->length();
1158 }
1159 sum_of_vtable_len += vt->length();
1160 }
1161
1162 static void compute() {
1163 SystemDictionary::classes_do(do_class);
1164 fixed = no_klasses * oopSize; // vtable length
1165 // filler size is a conservative approximation
1166 filler = oopSize * (no_klasses - no_instance_klasses) * (sizeof(InstanceKlass) - sizeof(ArrayKlass) - 1);
1167 entries = sizeof(vtableEntry) * sum_of_vtable_len;
1168 array_entries = sizeof(vtableEntry) * sum_of_array_vtable_len;
1169 }
1170 };
1171
1172 int VtableStats::no_klasses = 0;
1173 int VtableStats::no_array_klasses = 0;
1174 int VtableStats::no_instance_klasses = 0;
1175 int VtableStats::sum_of_vtable_len = 0;
1176 int VtableStats::sum_of_array_vtable_len = 0;
1177 int VtableStats::fixed = 0;
1178 int VtableStats::filler = 0;
1179 int VtableStats::entries = 0;
1180 int VtableStats::array_entries = 0;
1181
1182 void klassVtable::print_statistics() {
1183 ResourceMark rm;
1184 HandleMark hm;
1185 VtableStats::compute();
1186 tty->print_cr("vtable statistics:");
1187 tty->print_cr("%6d classes (%d instance, %d array)", VtableStats::no_klasses, VtableStats::no_instance_klasses, VtableStats::no_array_klasses);
1188 int total = VtableStats::fixed + VtableStats::filler + VtableStats::entries;
1189 tty->print_cr("%6d bytes fixed overhead (refs + vtable object header)", VtableStats::fixed);
1190 tty->print_cr("%6d bytes filler overhead", VtableStats::filler);
1191 tty->print_cr("%6d bytes for vtable entries (%d for arrays)", VtableStats::entries, VtableStats::array_entries);
1192 tty->print_cr("%6d bytes total", total);
1193 }
1194
1195 int klassItable::_total_classes; // Total no. of classes with itables
1196 long klassItable::_total_size; // Total no. of bytes used for itables
1197
1198 void klassItable::print_statistics() {
1199 tty->print_cr("itable statistics:");
1200 tty->print_cr("%6d classes with itables", _total_classes);
1201 tty->print_cr("%6d K uses for itables (average by class: %d bytes)", _total_size / K, _total_size / _total_classes);
1202 }
1203
1204 #endif // PRODUCT