1 /*
2 * Copyright (c) 1997, 2015, 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 "memory/resourceArea.hpp"
30 #include "memory/universe.inline.hpp"
31 #include "oops/instanceKlass.hpp"
32 #include "oops/klassVtable.hpp"
33 #include "oops/method.hpp"
34 #include "oops/objArrayOop.hpp"
35 #include "oops/oop.inline.hpp"
36 #include "prims/jvmtiRedefineClassesTrace.hpp"
37 #include "runtime/arguments.hpp"
38 #include "runtime/handles.inline.hpp"
39 #include "utilities/copy.hpp"
40
41 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
42
43 inline InstanceKlass* klassVtable::ik() const {
44 Klass* k = _klass();
45 assert(k->oop_is_instance(), "not an InstanceKlass");
46 return (InstanceKlass*)k;
47 }
48
49
50 // this function computes the vtable size (including the size needed for miranda
51 // methods) and the number of miranda methods in this class.
52 // Note on Miranda methods: Let's say there is a class C that implements
53 // interface I, and none of C's superclasses implements I.
54 // Let's say there is an abstract method m in I that neither C
55 // nor any of its super classes implement (i.e there is no method of any access,
56 // with the same name and signature as m), then m is a Miranda method which is
57 // entered as a public abstract method in C's vtable. From then on it should
58 // treated as any other public method in C for method over-ride purposes.
59 void klassVtable::compute_vtable_size_and_num_mirandas(
60 int* vtable_length_ret, int* num_new_mirandas,
61 GrowableArray<Method*>* all_mirandas, Klass* super,
62 Array<Method*>* methods, AccessFlags class_flags,
63 Handle classloader, Symbol* classname, Array<Klass*>* local_interfaces,
64 TRAPS) {
65 No_Safepoint_Verifier nsv;
66
67 // set up default result values
68 int vtable_length = 0;
69
70 // start off with super's vtable length
71 InstanceKlass* sk = (InstanceKlass*)super;
72 vtable_length = super == NULL ? 0 : sk->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 {
135 // copy methods from superKlass
136 // can't inherit from array class, so must be InstanceKlass
137 assert(super->oop_is_instance(), "must be instance klass");
138 InstanceKlass* sk = (InstanceKlass*)super();
139 klassVtable* superVtable = sk->vtable();
140 assert(superVtable->length() <= _length, "vtable too short");
141 #ifdef ASSERT
142 superVtable->verify(tty, true);
143 #endif
144 superVtable->copy_vtable_to(table());
145 #ifndef PRODUCT
146 if (PrintVtables && Verbose) {
147 ResourceMark rm;
148 tty->print_cr("copy vtable from %s to %s size %d", sk->internal_name(), klass()->internal_name(), _length);
149 }
150 #endif
151 return superVtable->length();
152 }
153 }
154
155 //
156 // Revised lookup semantics introduced 1.3 (Kestrel beta)
157 void klassVtable::initialize_vtable(bool checkconstraints, TRAPS) {
158
159 // Note: Arrays can have intermediate array supers. Use java_super to skip them.
160 KlassHandle super (THREAD, klass()->java_super());
161 int nofNewEntries = 0;
162
163 if (PrintVtables && !klass()->oop_is_array()) {
164 ResourceMark rm(THREAD);
165 tty->print_cr("Initializing: %s", _klass->name()->as_C_string());
166 }
167
168 #ifdef ASSERT
169 oop* end_of_obj = (oop*)_klass() + _klass()->size();
170 oop* end_of_vtable = (oop*)&table()[_length];
171 assert(end_of_vtable <= end_of_obj, "vtable extends beyond end");
172 #endif
173
174 if (Universe::is_bootstrapping()) {
175 // just clear everything
176 for (int i = 0; i < _length; i++) table()[i].clear();
177 return;
178 }
179
180 int super_vtable_len = initialize_from_super(super);
181 if (klass()->oop_is_array()) {
182 assert(super_vtable_len == _length, "arrays shouldn't introduce new methods");
183 } else {
184 assert(_klass->oop_is_instance(), "must be InstanceKlass");
185
186 Array<Method*>* methods = ik()->methods();
187 int len = methods->length();
188 int initialized = super_vtable_len;
189
190 // Check each of this class's methods against super;
191 // if override, replace in copy of super vtable, otherwise append to end
192 for (int i = 0; i < len; i++) {
193 // update_inherited_vtable can stop for gc - ensure using handles
194 HandleMark hm(THREAD);
195 assert(methods->at(i)->is_method(), "must be a Method*");
196 methodHandle mh(THREAD, methods->at(i));
197
198 bool needs_new_entry = update_inherited_vtable(ik(), mh, super_vtable_len, -1, checkconstraints, CHECK);
199
200 if (needs_new_entry) {
201 put_method_at(mh(), initialized);
202 mh()->set_vtable_index(initialized); // set primary vtable index
203 initialized++;
204 }
205 }
206
207 // update vtable with default_methods
208 Array<Method*>* default_methods = ik()->default_methods();
209 if (default_methods != NULL) {
210 len = default_methods->length();
211 if (len > 0) {
212 Array<int>* def_vtable_indices = NULL;
213 if ((def_vtable_indices = ik()->default_vtable_indices()) == NULL) {
214 def_vtable_indices = ik()->create_new_default_vtable_indices(len, CHECK);
215 } else {
216 assert(def_vtable_indices->length() == len, "reinit vtable len?");
217 }
218 for (int i = 0; i < len; i++) {
219 HandleMark hm(THREAD);
220 assert(default_methods->at(i)->is_method(), "must be a Method*");
221 methodHandle mh(THREAD, default_methods->at(i));
222
223 bool needs_new_entry = update_inherited_vtable(ik(), mh, super_vtable_len, i, checkconstraints, CHECK);
224
225 // needs new entry
226 if (needs_new_entry) {
227 put_method_at(mh(), initialized);
228 def_vtable_indices->at_put(i, initialized); //set vtable index
229 initialized++;
230 }
231 }
232 }
233 }
234
235 // add miranda methods; it will also return the updated initialized
236 // Interfaces do not need interface methods in their vtables
237 // This includes miranda methods and during later processing, default methods
238 if (!ik()->is_interface()) {
239 initialized = fill_in_mirandas(initialized);
240 }
241
242 // In class hierarchies where the accessibility is not increasing (i.e., going from private ->
243 // package_private -> public/protected), the vtable might actually be smaller than our initial
244 // calculation.
245 assert(initialized <= _length, "vtable initialization failed");
246 for(;initialized < _length; initialized++) {
247 put_method_at(NULL, initialized);
248 }
249 NOT_PRODUCT(verify(tty, true));
250 }
251 }
252
253 // Called for cases where a method does not override its superclass' vtable entry
254 // For bytecodes not produced by javac together it is possible that a method does not override
255 // the superclass's method, but might indirectly override a super-super class's vtable entry
256 // If none found, return a null superk, else return the superk of the method this does override
257 // For public and protected methods: if they override a superclass, they will
258 // also be overridden themselves appropriately.
259 // Private methods do not override and are not overridden.
260 // Package Private methods are trickier:
261 // e.g. P1.A, pub m
262 // P2.B extends A, package private m
263 // P1.C extends B, public m
264 // P1.C.m needs to override P1.A.m and can not override P2.B.m
265 // Therefore: all package private methods need their own vtable entries for
266 // them to be the root of an inheritance overriding decision
267 // Package private methods may also override other vtable entries
268 InstanceKlass* klassVtable::find_transitive_override(InstanceKlass* initialsuper, methodHandle target_method,
269 int vtable_index, Handle target_loader, Symbol* target_classname, Thread * THREAD) {
270 InstanceKlass* superk = initialsuper;
271 while (superk != NULL && superk->super() != NULL) {
272 InstanceKlass* supersuperklass = InstanceKlass::cast(superk->super());
273 klassVtable* ssVtable = supersuperklass->vtable();
274 if (vtable_index < ssVtable->length()) {
275 Method* super_method = ssVtable->method_at(vtable_index);
276 #ifndef PRODUCT
277 Symbol* name= target_method()->name();
278 Symbol* signature = target_method()->signature();
279 assert(super_method->name() == name && super_method->signature() == signature, "vtable entry name/sig mismatch");
280 #endif
281 if (supersuperklass->is_override(super_method, target_loader, target_classname, THREAD)) {
282 #ifndef PRODUCT
283 if (PrintVtables && Verbose) {
284 ResourceMark rm(THREAD);
285 char* sig = target_method()->name_and_sig_as_C_string();
286 tty->print("transitive overriding superclass %s with %s::%s index %d, original flags: ",
287 supersuperklass->internal_name(),
288 _klass->internal_name(), sig, vtable_index);
289 super_method->access_flags().print_on(tty);
290 if (super_method->is_default_method()) {
291 tty->print("default ");
292 }
293 tty->print("overriders flags: ");
294 target_method->access_flags().print_on(tty);
295 if (target_method->is_default_method()) {
296 tty->print("default ");
297 }
298 }
299 #endif /*PRODUCT*/
300 break; // return found superk
301 }
302 } else {
303 // super class has no vtable entry here, stop transitive search
304 superk = (InstanceKlass*)NULL;
305 break;
306 }
307 // if no override found yet, continue to search up
308 superk = InstanceKlass::cast(superk->super());
309 }
310
311 return superk;
312 }
313
314 // Update child's copy of super vtable for overrides
315 // OR return true if a new vtable entry is required.
316 // Only called for InstanceKlass's, i.e. not for arrays
317 // If that changed, could not use _klass as handle for klass
318 bool klassVtable::update_inherited_vtable(InstanceKlass* klass, methodHandle target_method,
319 int super_vtable_len, int default_index,
320 bool checkconstraints, TRAPS) {
321 ResourceMark rm;
322 bool allocate_new = true;
323 assert(klass->oop_is_instance(), "must be InstanceKlass");
324
325 Array<int>* def_vtable_indices = NULL;
326 bool is_default = false;
327 // default methods are concrete methods in superinterfaces which are added to the vtable
328 // with their real method_holder
329 // Since vtable and itable indices share the same storage, don't touch
330 // the default method's real vtable/itable index
331 // default_vtable_indices stores the vtable value relative to this inheritor
332 if (default_index >= 0 ) {
333 is_default = true;
334 def_vtable_indices = klass->default_vtable_indices();
335 assert(def_vtable_indices != NULL, "def vtable alloc?");
336 assert(default_index <= def_vtable_indices->length(), "def vtable len?");
337 } else {
338 assert(klass == target_method()->method_holder(), "caller resp.");
339 // Initialize the method's vtable index to "nonvirtual".
340 // If we allocate a vtable entry, we will update it to a non-negative number.
341 target_method()->set_vtable_index(Method::nonvirtual_vtable_index);
342 }
343
344 // Static and <init> methods are never in
345 if (target_method()->is_static() || target_method()->name() == vmSymbols::object_initializer_name()) {
346 return false;
347 }
348
349 if (target_method->is_final_method(klass->access_flags())) {
350 // a final method never needs a new entry; final methods can be statically
351 // resolved and they have to be present in the vtable only if they override
352 // a super's method, in which case they re-use its entry
353 allocate_new = false;
354 } else if (klass->is_interface()) {
355 allocate_new = false; // see note below in needs_new_vtable_entry
356 // An interface never allocates new vtable slots, only inherits old ones.
357 // This method will either be assigned its own itable index later,
358 // or be assigned an inherited vtable index in the loop below.
359 // default methods inherited by classes store their vtable indices
360 // in the inheritor's default_vtable_indices
361 // default methods inherited by interfaces may already have a
362 // valid itable index, if so, don't change it
363 // overpass methods in an interface will be assigned an itable index later
364 // by an inheriting class
365 if (!is_default || !target_method()->has_itable_index()) {
366 target_method()->set_vtable_index(Method::pending_itable_index);
367 }
368 }
369
370 // we need a new entry if there is no superclass
371 if (klass->super() == NULL) {
372 return allocate_new;
373 }
374
375 // private methods in classes always have a new entry in the vtable
376 // specification interpretation since classic has
377 // private methods not overriding
378 // JDK8 adds private methods in interfaces which require invokespecial
379 if (target_method()->is_private()) {
380 return allocate_new;
381 }
382
383 // search through the vtable and update overridden entries
384 // Since check_signature_loaders acquires SystemDictionary_lock
385 // which can block for gc, once we are in this loop, use handles
386 // For classfiles built with >= jdk7, we now look for transitive overrides
387
388 Symbol* name = target_method()->name();
389 Symbol* signature = target_method()->signature();
390
391 KlassHandle target_klass(THREAD, target_method()->method_holder());
392 if (target_klass == NULL) {
393 target_klass = _klass;
394 }
395
396 Handle target_loader(THREAD, target_klass->class_loader());
397
398 Symbol* target_classname = target_klass->name();
399 for(int i = 0; i < super_vtable_len; i++) {
400 Method* super_method = method_at(i);
401 // Check if method name matches
402 if (super_method->name() == name && super_method->signature() == signature) {
403
404 // get super_klass for method_holder for the found method
405 InstanceKlass* super_klass = super_method->method_holder();
406
407 // private methods are also never overridden
408 if (!super_method->is_private() &&
409 (is_default
410 || ((super_klass->is_override(super_method, target_loader, target_classname, THREAD))
411 || ((klass->major_version() >= VTABLE_TRANSITIVE_OVERRIDE_VERSION)
412 && ((super_klass = find_transitive_override(super_klass,
413 target_method, i, target_loader,
414 target_classname, THREAD))
415 != (InstanceKlass*)NULL)))))
416 {
417 // Package private methods always need a new entry to root their own
418 // overriding. They may also override other methods.
419 if (!target_method()->is_package_private()) {
420 allocate_new = false;
421 }
422
423 if (checkconstraints) {
424 // Override vtable entry if passes loader constraint check
425 // if loader constraint checking requested
426 // No need to visit his super, since he and his super
427 // have already made any needed loader constraints.
428 // Since loader constraints are transitive, it is enough
429 // to link to the first super, and we get all the others.
430 Handle super_loader(THREAD, super_klass->class_loader());
431
432 if (target_loader() != super_loader()) {
433 ResourceMark rm(THREAD);
434 Symbol* failed_type_symbol =
435 SystemDictionary::check_signature_loaders(signature, target_loader,
436 super_loader, true,
437 CHECK_(false));
438 if (failed_type_symbol != NULL) {
439 const char* msg = "loader constraint violation: when resolving "
440 "overridden method \"%s\" the class loader (instance"
441 " of %s) of the current class, %s, and its superclass loader "
442 "(instance of %s), have different Class objects for the type "
443 "%s used in the signature";
444 char* sig = target_method()->name_and_sig_as_C_string();
445 const char* loader1 = SystemDictionary::loader_name(target_loader());
446 char* current = target_klass->name()->as_C_string();
447 const char* loader2 = SystemDictionary::loader_name(super_loader());
448 char* failed_type_name = failed_type_symbol->as_C_string();
449 size_t buflen = strlen(msg) + strlen(sig) + strlen(loader1) +
450 strlen(current) + strlen(loader2) + strlen(failed_type_name);
451 char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen);
452 jio_snprintf(buf, buflen, msg, sig, loader1, current, loader2,
453 failed_type_name);
454 THROW_MSG_(vmSymbols::java_lang_LinkageError(), buf, false);
455 }
456 }
457 }
458
459 put_method_at(target_method(), i);
460 if (!is_default) {
461 target_method()->set_vtable_index(i);
462 } else {
463 if (def_vtable_indices != NULL) {
464 def_vtable_indices->at_put(default_index, i);
465 }
466 assert(super_method->is_default_method() || super_method->is_overpass()
467 || super_method->is_abstract(), "default override error");
468 }
469
470
471 #ifndef PRODUCT
472 if (PrintVtables && Verbose) {
473 ResourceMark rm(THREAD);
474 char* sig = target_method()->name_and_sig_as_C_string();
475 tty->print("overriding with %s::%s index %d, original flags: ",
476 target_klass->internal_name(), sig, i);
477 super_method->access_flags().print_on(tty);
478 if (super_method->is_default_method()) {
479 tty->print("default ");
480 }
481 if (super_method->is_overpass()) {
482 tty->print("overpass");
483 }
484 tty->print("overriders flags: ");
485 target_method->access_flags().print_on(tty);
486 if (target_method->is_default_method()) {
487 tty->print("default ");
488 }
489 if (target_method->is_overpass()) {
490 tty->print("overpass");
491 }
492 tty->cr();
493 }
494 #endif /*PRODUCT*/
495 } else {
496 // allocate_new = true; default. We might override one entry,
497 // but not override another. Once we override one, not need new
498 #ifndef PRODUCT
499 if (PrintVtables && Verbose) {
500 ResourceMark rm(THREAD);
501 char* sig = target_method()->name_and_sig_as_C_string();
502 tty->print("NOT overriding with %s::%s index %d, original flags: ",
503 target_klass->internal_name(), sig,i);
504 super_method->access_flags().print_on(tty);
505 if (super_method->is_default_method()) {
506 tty->print("default ");
507 }
508 if (super_method->is_overpass()) {
509 tty->print("overpass");
510 }
511 tty->print("overriders flags: ");
512 target_method->access_flags().print_on(tty);
513 if (target_method->is_default_method()) {
514 tty->print("default ");
515 }
516 if (target_method->is_overpass()) {
517 tty->print("overpass");
518 }
519 tty->cr();
520 }
521 #endif /*PRODUCT*/
522 }
523 }
524 }
525 return allocate_new;
526 }
527
528 void klassVtable::put_method_at(Method* m, int index) {
529 #ifndef PRODUCT
530 if (PrintVtables && Verbose) {
531 ResourceMark rm;
532 const char* sig = (m != NULL) ? m->name_and_sig_as_C_string() : "<NULL>";
533 tty->print("adding %s at index %d, flags: ", sig, index);
534 if (m != NULL) {
535 m->access_flags().print_on(tty);
536 if (m->is_default_method()) {
537 tty->print("default ");
538 }
539 if (m->is_overpass()) {
540 tty->print("overpass");
541 }
542 }
543 tty->cr();
544 }
545 #endif
546 table()[index].set(m);
547 }
548
549 // Find out if a method "m" with superclass "super", loader "classloader" and
550 // name "classname" needs a new vtable entry. Let P be a class package defined
551 // by "classloader" and "classname".
552 // NOTE: The logic used here is very similar to the one used for computing
553 // the vtables indices for a method. We cannot directly use that function because,
554 // we allocate the InstanceKlass at load time, and that requires that the
555 // superclass has been loaded.
556 // However, the vtable entries are filled in at link time, and therefore
557 // the superclass' vtable may not yet have been filled in.
558 bool klassVtable::needs_new_vtable_entry(methodHandle target_method,
559 Klass* super,
560 Handle classloader,
561 Symbol* classname,
562 AccessFlags class_flags,
563 TRAPS) {
564 if (class_flags.is_interface()) {
565 // Interfaces do not use vtables, except for java.lang.Object methods,
566 // so there is no point to assigning
567 // a vtable index to any of their local methods. If we refrain from doing this,
568 // we can use Method::_vtable_index to hold the itable index
569 return false;
570 }
571
572 if (target_method->is_final_method(class_flags) ||
573 // a final method never needs a new entry; final methods can be statically
574 // resolved and they have to be present in the vtable only if they override
575 // a super's method, in which case they re-use its entry
576 (target_method()->is_static()) ||
577 // static methods don't need to be in vtable
578 (target_method()->name() == vmSymbols::object_initializer_name())
579 // <init> is never called dynamically-bound
580 ) {
581 return false;
582 }
583
584 // Concrete interface methods do not need new entries, they override
585 // abstract method entries using default inheritance rules
586 if (target_method()->method_holder() != NULL &&
587 target_method()->method_holder()->is_interface() &&
588 !target_method()->is_abstract() ) {
589 return false;
590 }
591
592 // we need a new entry if there is no superclass
593 if (super == NULL) {
594 return true;
595 }
596
597 // private methods in classes always have a new entry in the vtable
598 // specification interpretation since classic has
599 // private methods not overriding
600 // JDK8 adds private methods in interfaces which require invokespecial
601 if (target_method()->is_private()) {
602 return true;
603 }
604
605 // Package private methods always need a new entry to root their own
606 // overriding. This allows transitive overriding to work.
607 if (target_method()->is_package_private()) {
608 return true;
609 }
610
611 // search through the super class hierarchy to see if we need
612 // a new entry
613 ResourceMark rm;
614 Symbol* name = target_method()->name();
615 Symbol* signature = target_method()->signature();
616 Klass* k = super;
617 Method* super_method = NULL;
618 InstanceKlass *holder = NULL;
619 Method* recheck_method = NULL;
620 while (k != NULL) {
621 // lookup through the hierarchy for a method with matching name and sign.
622 super_method = InstanceKlass::cast(k)->lookup_method(name, signature);
623 if (super_method == NULL) {
624 break; // we still have to search for a matching miranda method
625 }
626 // get the class holding the matching method
627 // make sure you use that class for is_override
628 InstanceKlass* superk = super_method->method_holder();
629 // we want only instance method matches
630 // pretend private methods are not in the super vtable
631 // since we do override around them: e.g. a.m pub/b.m private/c.m pub,
632 // ignore private, c.m pub does override a.m pub
633 // For classes that were not javac'd together, we also do transitive overriding around
634 // methods that have less accessibility
635 if ((!super_method->is_static()) &&
636 (!super_method->is_private())) {
637 if (superk->is_override(super_method, classloader, classname, THREAD)) {
638 return false;
639 // else keep looking for transitive overrides
640 }
641 }
642
643 // Start with lookup result and continue to search up
644 k = superk->super(); // haven't found an override match yet; continue to look
645 }
646
647 // if the target method is public or protected it may have a matching
648 // miranda method in the super, whose entry it should re-use.
649 // Actually, to handle cases that javac would not generate, we need
650 // this check for all access permissions.
651 InstanceKlass *sk = InstanceKlass::cast(super);
652 if (sk->has_miranda_methods()) {
653 if (sk->lookup_method_in_all_interfaces(name, signature, Klass::find_defaults) != NULL) {
654 return false; // found a matching miranda; we do not need a new entry
655 }
656 }
657 return true; // found no match; we need a new entry
658 }
659
660 // Support for miranda methods
661
662 // get the vtable index of a miranda method with matching "name" and "signature"
663 int klassVtable::index_of_miranda(Symbol* name, Symbol* signature) {
664 // search from the bottom, might be faster
665 for (int i = (length() - 1); i >= 0; i--) {
666 Method* m = table()[i].method();
667 if (is_miranda_entry_at(i) &&
668 m->name() == name && m->signature() == signature) {
669 return i;
670 }
671 }
672 return Method::invalid_vtable_index;
673 }
674
675 // check if an entry at an index is miranda
676 // requires that method m at entry be declared ("held") by an interface.
677 bool klassVtable::is_miranda_entry_at(int i) {
678 Method* m = method_at(i);
679 Klass* method_holder = m->method_holder();
680 InstanceKlass *mhk = InstanceKlass::cast(method_holder);
681
682 // miranda methods are public abstract instance interface methods in a class's vtable
683 if (mhk->is_interface()) {
684 assert(m->is_public(), "should be public");
685 assert(ik()->implements_interface(method_holder) , "this class should implement the interface");
686 if (is_miranda(m, ik()->methods(), ik()->default_methods(), ik()->super())) {
687 return true;
688 }
689 }
690 return false;
691 }
692
693 // Check if a method is a miranda method, given a class's methods array,
694 // its default_method table and its super class.
695 // "Miranda" means an abstract non-private method that would not be
696 // overridden for the local class.
697 // A "miranda" method should only include non-private interface
698 // instance methods, i.e. not private methods, not static methods,
699 // not default methods (concrete interface methods), not overpass methods.
700 // If a given class already has a local (including overpass) method, a
701 // default method, or any of its superclasses has the same which would have
702 // overridden an abstract method, then this is not a miranda method.
703 //
704 // Miranda methods are checked multiple times.
705 // Pass 1: during class load/class file parsing: before vtable size calculation:
706 // include superinterface abstract and default methods (non-private instance).
707 // We include potential default methods to give them space in the vtable.
708 // During the first run, the current instanceKlass has not yet been
709 // created, the superclasses and superinterfaces do have instanceKlasses
710 // but may not have vtables, the default_methods list is empty, no overpasses.
711 // This is seen by default method creation.
712 //
713 // Pass 2: recalculated during vtable initialization: only include abstract methods.
714 // The goal of pass 2 is to walk through the superinterfaces to see if any of
715 // the superinterface methods (which were all abstract pre-default methods)
716 // need to be added to the vtable.
717 // With the addition of default methods, we have three new challenges:
718 // overpasses, static interface methods and private interface methods.
719 // Static and private interface methods do not get added to the vtable and
720 // are not seen by the method resolution process, so we skip those.
721 // Overpass methods are already in the vtable, so vtable lookup will
722 // find them and we don't need to add a miranda method to the end of
723 // the vtable. So we look for overpass methods and if they are found we
724 // return false. Note that we inherit our superclasses vtable, so
725 // the superclass' search also needs to use find_overpass so that if
726 // one is found we return false.
727 // False means - we don't need a miranda method added to the vtable.
728 //
729 // During the second run, default_methods is set up, so concrete methods from
730 // superinterfaces with matching names/signatures to default_methods are already
731 // in the default_methods list and do not need to be appended to the vtable
732 // as mirandas. Abstract methods may already have been handled via
733 // overpasses - either local or superclass overpasses, which may be
734 // in the vtable already.
735 //
736 // Pass 3: They are also checked by link resolution and selection,
737 // for invocation on a method (not interface method) reference that
738 // resolves to a method with an interface as its method_holder.
739 // Used as part of walking from the bottom of the vtable to find
740 // the vtable index for the miranda method.
741 //
742 // Part of the Miranda Rights in the US mean that if you do not have
743 // an attorney one will be appointed for you.
744 bool klassVtable::is_miranda(Method* m, Array<Method*>* class_methods,
745 Array<Method*>* default_methods, Klass* super) {
746 if (m->is_static() || m->is_private() || m->is_overpass()) {
747 return false;
748 }
749 Symbol* name = m->name();
750 Symbol* signature = m->signature();
751
752 // First look in local methods to see if already covered
753 if (InstanceKlass::find_local_method(class_methods, name, signature,
754 Klass::find_overpass, Klass::skip_static, Klass::skip_private) != NULL)
755 {
756 return false;
757 }
758
759 // Check local default methods
760 if ((default_methods != NULL) &&
761 (InstanceKlass::find_method(default_methods, name, signature) != NULL))
762 {
763 return false;
764 }
765
766 InstanceKlass* cursuper;
767 // Iterate on all superclasses, which should have instanceKlasses
768 // Note that we explicitly look for overpasses at each level.
769 // Overpasses may or may not exist for supers for pass 1,
770 // they should have been created for pass 2 and later.
771
772 for (cursuper = InstanceKlass::cast(super); cursuper != NULL; cursuper = (InstanceKlass*)cursuper->super())
773 {
774 if (cursuper->find_local_method(name, signature,
775 Klass::find_overpass, Klass::skip_static, Klass::skip_private) != NULL) {
776 return false;
777 }
778 }
779
780 return true;
781 }
782
783 // Scans current_interface_methods for miranda methods that do not
784 // already appear in new_mirandas, or default methods, and are also not defined-and-non-private
785 // in super (superclass). These mirandas are added to all_mirandas if it is
786 // not null; in addition, those that are not duplicates of miranda methods
787 // inherited by super from its interfaces are added to new_mirandas.
788 // Thus, new_mirandas will be the set of mirandas that this class introduces,
789 // all_mirandas will be the set of all mirandas applicable to this class
790 // including all defined in superclasses.
791 void klassVtable::add_new_mirandas_to_lists(
792 GrowableArray<Method*>* new_mirandas, GrowableArray<Method*>* all_mirandas,
793 Array<Method*>* current_interface_methods, Array<Method*>* class_methods,
794 Array<Method*>* default_methods, Klass* super) {
795
796 // iterate thru the current interface's method to see if it a miranda
797 int num_methods = current_interface_methods->length();
798 for (int i = 0; i < num_methods; i++) {
799 Method* im = current_interface_methods->at(i);
800 bool is_duplicate = false;
801 int num_of_current_mirandas = new_mirandas->length();
802 // check for duplicate mirandas in different interfaces we implement
803 for (int j = 0; j < num_of_current_mirandas; j++) {
804 Method* miranda = new_mirandas->at(j);
805 if ((im->name() == miranda->name()) &&
806 (im->signature() == miranda->signature())) {
807 is_duplicate = true;
808 break;
809 }
810 }
811
812 if (!is_duplicate) { // we don't want duplicate miranda entries in the vtable
813 if (is_miranda(im, class_methods, default_methods, super)) { // is it a miranda at all?
814 InstanceKlass *sk = InstanceKlass::cast(super);
815 // check if it is a duplicate of a super's miranda
816 if (sk->lookup_method_in_all_interfaces(im->name(), im->signature(), Klass::find_defaults) == NULL) {
817 new_mirandas->append(im);
818 }
819 if (all_mirandas != NULL) {
820 all_mirandas->append(im);
821 }
822 }
823 }
824 }
825 }
826
827 void klassVtable::get_mirandas(GrowableArray<Method*>* new_mirandas,
828 GrowableArray<Method*>* all_mirandas,
829 Klass* super, Array<Method*>* class_methods,
830 Array<Method*>* default_methods,
831 Array<Klass*>* local_interfaces) {
832 assert((new_mirandas->length() == 0) , "current mirandas must be 0");
833
834 // iterate thru the local interfaces looking for a miranda
835 int num_local_ifs = local_interfaces->length();
836 for (int i = 0; i < num_local_ifs; i++) {
837 InstanceKlass *ik = InstanceKlass::cast(local_interfaces->at(i));
838 add_new_mirandas_to_lists(new_mirandas, all_mirandas,
839 ik->methods(), class_methods,
840 default_methods, super);
841 // iterate thru each local's super interfaces
842 Array<Klass*>* super_ifs = ik->transitive_interfaces();
843 int num_super_ifs = super_ifs->length();
844 for (int j = 0; j < num_super_ifs; j++) {
845 InstanceKlass *sik = InstanceKlass::cast(super_ifs->at(j));
846 add_new_mirandas_to_lists(new_mirandas, all_mirandas,
847 sik->methods(), class_methods,
848 default_methods, super);
849 }
850 }
851 }
852
853 // Discover miranda methods ("miranda" = "interface abstract, no binding"),
854 // and append them into the vtable starting at index initialized,
855 // return the new value of initialized.
856 // Miranda methods use vtable entries, but do not get assigned a vtable_index
857 // The vtable_index is discovered by searching from the end of the vtable
858 int klassVtable::fill_in_mirandas(int initialized) {
859 GrowableArray<Method*> mirandas(20);
860 get_mirandas(&mirandas, NULL, ik()->super(), ik()->methods(),
861 ik()->default_methods(), ik()->local_interfaces());
862 for (int i = 0; i < mirandas.length(); i++) {
863 if (PrintVtables && Verbose) {
864 Method* meth = mirandas.at(i);
865 ResourceMark rm(Thread::current());
866 if (meth != NULL) {
867 char* sig = meth->name_and_sig_as_C_string();
868 tty->print("fill in mirandas with %s index %d, flags: ",
869 sig, initialized);
870 meth->access_flags().print_on(tty);
871 if (meth->is_default_method()) {
872 tty->print("default ");
873 }
874 tty->cr();
875 }
876 }
877 put_method_at(mirandas.at(i), initialized);
878 ++initialized;
879 }
880 return initialized;
881 }
882
883 // Copy this class's vtable to the vtable beginning at start.
884 // Used to copy superclass vtable to prefix of subclass's vtable.
885 void klassVtable::copy_vtable_to(vtableEntry* start) {
886 Copy::disjoint_words((HeapWord*)table(), (HeapWord*)start, _length * vtableEntry::size());
887 }
888
889 #if INCLUDE_JVMTI
890 bool klassVtable::adjust_default_method(int vtable_index, Method* old_method, Method* new_method) {
891 // If old_method is default, find this vtable index in default_vtable_indices
892 // and replace that method in the _default_methods list
893 bool updated = false;
894
895 Array<Method*>* default_methods = ik()->default_methods();
896 if (default_methods != NULL) {
897 int len = default_methods->length();
898 for (int idx = 0; idx < len; idx++) {
899 if (vtable_index == ik()->default_vtable_indices()->at(idx)) {
900 if (default_methods->at(idx) == old_method) {
901 default_methods->at_put(idx, new_method);
902 updated = true;
903 }
904 break;
905 }
906 }
907 }
908 return updated;
909 }
910
911 // search the vtable for uses of either obsolete or EMCP methods
912 void klassVtable::adjust_method_entries(InstanceKlass* holder, bool * trace_name_printed) {
913 int prn_enabled = 0;
914 for (int index = 0; index < length(); index++) {
915 Method* old_method = unchecked_method_at(index);
916 if (old_method == NULL || old_method->method_holder() != holder || !old_method->is_old()) {
917 continue; // skip uninteresting entries
918 }
919 assert(!old_method->is_deleted(), "vtable methods may not be deleted");
920
921 Method* new_method = holder->method_with_idnum(old_method->orig_method_idnum());
922
923 assert(new_method != NULL, "method_with_idnum() should not be NULL");
924 assert(old_method != new_method, "sanity check");
925
926 put_method_at(new_method, index);
927 // For default methods, need to update the _default_methods array
928 // which can only have one method entry for a given signature
929 bool updated_default = false;
930 if (old_method->is_default_method()) {
931 updated_default = adjust_default_method(index, old_method, new_method);
932 }
933
934 if (RC_TRACE_IN_RANGE(0x00100000, 0x00400000)) {
935 if (!(*trace_name_printed)) {
936 // RC_TRACE_MESG macro has an embedded ResourceMark
937 RC_TRACE_MESG(("adjust: klassname=%s for methods from name=%s",
938 klass()->external_name(),
939 old_method->method_holder()->external_name()));
940 *trace_name_printed = true;
941 }
942 // RC_TRACE macro has an embedded ResourceMark
943 RC_TRACE(0x00100000, ("vtable method update: %s(%s), updated default = %s",
944 new_method->name()->as_C_string(),
945 new_method->signature()->as_C_string(),
946 updated_default ? "true" : "false"));
947 }
948 }
949 }
950
951 // a vtable should never contain old or obsolete methods
952 bool klassVtable::check_no_old_or_obsolete_entries() {
953 for (int i = 0; i < length(); i++) {
954 Method* m = unchecked_method_at(i);
955 if (m != NULL &&
956 (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) {
957 return false;
958 }
959 }
960 return true;
961 }
962
963 void klassVtable::dump_vtable() {
964 tty->print_cr("vtable dump --");
965 for (int i = 0; i < length(); i++) {
966 Method* m = unchecked_method_at(i);
967 if (m != NULL) {
968 tty->print(" (%5d) ", i);
969 m->access_flags().print_on(tty);
970 if (m->is_default_method()) {
971 tty->print("default ");
972 }
973 if (m->is_overpass()) {
974 tty->print("overpass");
975 }
976 tty->print(" -- ");
977 m->print_name(tty);
978 tty->cr();
979 }
980 }
981 }
982 #endif // INCLUDE_JVMTI
983
984 // CDS/RedefineClasses support - clear vtables so they can be reinitialized
985 void klassVtable::clear_vtable() {
986 for (int i = 0; i < _length; i++) table()[i].clear();
987 }
988
989 bool klassVtable::is_initialized() {
990 return _length == 0 || table()[0].method() != NULL;
991 }
992
993 //-----------------------------------------------------------------------------------------
994 // Itable code
995
996 // Initialize a itableMethodEntry
997 void itableMethodEntry::initialize(Method* m) {
998 if (m == NULL) return;
999
1000 _method = m;
1001 }
1002
1003 klassItable::klassItable(instanceKlassHandle klass) {
1004 _klass = klass;
1005
1006 if (klass->itable_length() > 0) {
1007 itableOffsetEntry* offset_entry = (itableOffsetEntry*)klass->start_of_itable();
1008 if (offset_entry != NULL && offset_entry->interface_klass() != NULL) { // Check that itable is initialized
1009 // First offset entry points to the first method_entry
1010 intptr_t* method_entry = (intptr_t *)(((address)klass()) + offset_entry->offset());
1011 intptr_t* end = klass->end_of_itable();
1012
1013 _table_offset = (intptr_t*)offset_entry - (intptr_t*)klass();
1014 _size_offset_table = (method_entry - ((intptr_t*)offset_entry)) / itableOffsetEntry::size();
1015 _size_method_table = (end - method_entry) / itableMethodEntry::size();
1016 assert(_table_offset >= 0 && _size_offset_table >= 0 && _size_method_table >= 0, "wrong computation");
1017 return;
1018 }
1019 }
1020
1021 // The length of the itable was either zero, or it has not yet been initialized.
1022 _table_offset = 0;
1023 _size_offset_table = 0;
1024 _size_method_table = 0;
1025 }
1026
1027 static int initialize_count = 0;
1028
1029 // Initialization
1030 void klassItable::initialize_itable(bool checkconstraints, TRAPS) {
1031 if (_klass->is_interface()) {
1032 // This needs to go after vtable indices are assigned but
1033 // before implementors need to know the number of itable indices.
1034 assign_itable_indices_for_interface(_klass());
1035 }
1036
1037 // Cannot be setup doing bootstrapping, interfaces don't have
1038 // itables, and klass with only ones entry have empty itables
1039 if (Universe::is_bootstrapping() ||
1040 _klass->is_interface() ||
1041 _klass->itable_length() == itableOffsetEntry::size()) return;
1042
1043 // There's alway an extra itable entry so we can null-terminate it.
1044 guarantee(size_offset_table() >= 1, "too small");
1045 int num_interfaces = size_offset_table() - 1;
1046 if (num_interfaces > 0) {
1047 if (TraceItables) tty->print_cr("%3d: Initializing itables for %s", ++initialize_count,
1048 _klass->name()->as_C_string());
1049
1050
1051 // Iterate through all interfaces
1052 int i;
1053 for(i = 0; i < num_interfaces; i++) {
1054 itableOffsetEntry* ioe = offset_entry(i);
1055 HandleMark hm(THREAD);
1056 KlassHandle interf_h (THREAD, ioe->interface_klass());
1057 assert(interf_h() != NULL && ioe->offset() != 0, "bad offset entry in itable");
1058 initialize_itable_for_interface(ioe->offset(), interf_h, checkconstraints, CHECK);
1059 }
1060
1061 }
1062 // Check that the last entry is empty
1063 itableOffsetEntry* ioe = offset_entry(size_offset_table() - 1);
1064 guarantee(ioe->interface_klass() == NULL && ioe->offset() == 0, "terminator entry missing");
1065 }
1066
1067
1068 inline bool interface_method_needs_itable_index(Method* m) {
1069 if (m->is_static()) return false; // e.g., Stream.empty
1070 if (m->is_initializer()) return false; // <init> or <clinit>
1071 // If an interface redeclares a method from java.lang.Object,
1072 // it should already have a vtable index, don't touch it.
1073 // e.g., CharSequence.toString (from initialize_vtable)
1074 // if (m->has_vtable_index()) return false; // NO!
1075 return true;
1076 }
1077
1078 int klassItable::assign_itable_indices_for_interface(Klass* klass) {
1079 // an interface does not have an itable, but its methods need to be numbered
1080 if (TraceItables) tty->print_cr("%3d: Initializing itable indices for interface %s", ++initialize_count,
1081 klass->name()->as_C_string());
1082 Array<Method*>* methods = InstanceKlass::cast(klass)->methods();
1083 int nof_methods = methods->length();
1084 int ime_num = 0;
1085 for (int i = 0; i < nof_methods; i++) {
1086 Method* m = methods->at(i);
1087 if (interface_method_needs_itable_index(m)) {
1088 assert(!m->is_final_method(), "no final interface methods");
1089 // If m is already assigned a vtable index, do not disturb it.
1090 if (TraceItables && Verbose) {
1091 ResourceMark rm;
1092 const char* sig = (m != NULL) ? m->name_and_sig_as_C_string() : "<NULL>";
1093 if (m->has_vtable_index()) {
1094 tty->print("vtable index %d for method: %s, flags: ", m->vtable_index(), sig);
1095 } else {
1096 tty->print("itable index %d for method: %s, flags: ", ime_num, sig);
1097 }
1098 if (m != NULL) {
1099 m->access_flags().print_on(tty);
1100 if (m->is_default_method()) {
1101 tty->print("default ");
1102 }
1103 if (m->is_overpass()) {
1104 tty->print("overpass");
1105 }
1106 }
1107 tty->cr();
1108 }
1109 if (!m->has_vtable_index()) {
1110 assert(m->vtable_index() == Method::pending_itable_index, "set by initialize_vtable");
1111 m->set_itable_index(ime_num);
1112 // Progress to next itable entry
1113 ime_num++;
1114 }
1115 }
1116 }
1117 assert(ime_num == method_count_for_interface(klass), "proper sizing");
1118 return ime_num;
1119 }
1120
1121 int klassItable::method_count_for_interface(Klass* interf) {
1122 assert(interf->oop_is_instance(), "must be");
1123 assert(interf->is_interface(), "must be");
1124 Array<Method*>* methods = InstanceKlass::cast(interf)->methods();
1125 int nof_methods = methods->length();
1126 int length = 0;
1127 while (nof_methods > 0) {
1128 Method* m = methods->at(nof_methods-1);
1129 if (m->has_itable_index()) {
1130 length = m->itable_index() + 1;
1131 break;
1132 }
1133 nof_methods -= 1;
1134 }
1135 #ifdef ASSERT
1136 int nof_methods_copy = nof_methods;
1137 while (nof_methods_copy > 0) {
1138 Method* mm = methods->at(--nof_methods_copy);
1139 assert(!mm->has_itable_index() || mm->itable_index() < length, "");
1140 }
1141 #endif //ASSERT
1142 // return the rightmost itable index, plus one; or 0 if no methods have
1143 // itable indices
1144 return length;
1145 }
1146
1147
1148 void klassItable::initialize_itable_for_interface(int method_table_offset, KlassHandle interf_h, bool checkconstraints, TRAPS) {
1149 Array<Method*>* methods = InstanceKlass::cast(interf_h())->methods();
1150 int nof_methods = methods->length();
1151 HandleMark hm;
1152 assert(nof_methods > 0, "at least one method must exist for interface to be in vtable");
1153 Handle interface_loader (THREAD, InstanceKlass::cast(interf_h())->class_loader());
1154
1155 int ime_count = method_count_for_interface(interf_h());
1156 for (int i = 0; i < nof_methods; i++) {
1157 Method* m = methods->at(i);
1158 methodHandle target;
1159 if (m->has_itable_index()) {
1160 // This search must match the runtime resolution, i.e. selection search for invokeinterface
1161 // to correctly enforce loader constraints for interface method inheritance
1162 target = LinkResolver::lookup_instance_method_in_klasses(_klass, m->name(), m->signature(), CHECK);
1163 }
1164 if (target == NULL || !target->is_public() || target->is_abstract()) {
1165 // Entry does not resolve. Leave it empty for AbstractMethodError.
1166 if (!(target == NULL) && !target->is_public()) {
1167 // Stuff an IllegalAccessError throwing method in there instead.
1168 itableOffsetEntry::method_entry(_klass(), method_table_offset)[m->itable_index()].
1169 initialize(Universe::throw_illegal_access_error());
1170 }
1171 } else {
1172 // Entry did resolve, check loader constraints before initializing
1173 // if checkconstraints requested
1174 if (checkconstraints) {
1175 Handle method_holder_loader (THREAD, target->method_holder()->class_loader());
1176 if (method_holder_loader() != interface_loader()) {
1177 ResourceMark rm(THREAD);
1178 Symbol* failed_type_symbol =
1179 SystemDictionary::check_signature_loaders(m->signature(),
1180 method_holder_loader,
1181 interface_loader,
1182 true, CHECK);
1183 if (failed_type_symbol != NULL) {
1184 const char* msg = "loader constraint violation in interface "
1185 "itable initialization: when resolving method \"%s\" the class"
1186 " loader (instance of %s) of the current class, %s, "
1187 "and the class loader (instance of %s) for interface "
1188 "%s have different Class objects for the type %s "
1189 "used in the signature";
1190 char* sig = target()->name_and_sig_as_C_string();
1191 const char* loader1 = SystemDictionary::loader_name(method_holder_loader());
1192 char* current = _klass->name()->as_C_string();
1193 const char* loader2 = SystemDictionary::loader_name(interface_loader());
1194 char* iface = InstanceKlass::cast(interf_h())->name()->as_C_string();
1195 char* failed_type_name = failed_type_symbol->as_C_string();
1196 size_t buflen = strlen(msg) + strlen(sig) + strlen(loader1) +
1197 strlen(current) + strlen(loader2) + strlen(iface) +
1198 strlen(failed_type_name);
1199 char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen);
1200 jio_snprintf(buf, buflen, msg, sig, loader1, current, loader2,
1201 iface, failed_type_name);
1202 THROW_MSG(vmSymbols::java_lang_LinkageError(), buf);
1203 }
1204 }
1205 }
1206
1207 // ime may have moved during GC so recalculate address
1208 int ime_num = m->itable_index();
1209 assert(ime_num < ime_count, "oob");
1210 itableOffsetEntry::method_entry(_klass(), method_table_offset)[ime_num].initialize(target());
1211 if (TraceItables && Verbose) {
1212 ResourceMark rm(THREAD);
1213 if (target() != NULL) {
1214 char* sig = target()->name_and_sig_as_C_string();
1215 tty->print("interface: %s, ime_num: %d, target: %s, method_holder: %s ",
1216 interf_h()->internal_name(), ime_num, sig,
1217 target()->method_holder()->internal_name());
1218 tty->print("target_method flags: ");
1219 target()->access_flags().print_on(tty);
1220 if (target()->is_default_method()) {
1221 tty->print("default ");
1222 }
1223 tty->cr();
1224 }
1225 }
1226 }
1227 }
1228 }
1229
1230 // Update entry for specific Method*
1231 void klassItable::initialize_with_method(Method* m) {
1232 itableMethodEntry* ime = method_entry(0);
1233 for(int i = 0; i < _size_method_table; i++) {
1234 if (ime->method() == m) {
1235 ime->initialize(m);
1236 }
1237 ime++;
1238 }
1239 }
1240
1241 #if INCLUDE_JVMTI
1242 // search the itable for uses of either obsolete or EMCP methods
1243 void klassItable::adjust_method_entries(InstanceKlass* holder, bool * trace_name_printed) {
1244
1245 itableMethodEntry* ime = method_entry(0);
1246 for (int i = 0; i < _size_method_table; i++, ime++) {
1247 Method* old_method = ime->method();
1248 if (old_method == NULL || old_method->method_holder() != holder || !old_method->is_old()) {
1249 continue; // skip uninteresting entries
1250 }
1251 assert(!old_method->is_deleted(), "itable methods may not be deleted");
1252
1253 Method* new_method = holder->method_with_idnum(old_method->orig_method_idnum());
1254
1255 assert(new_method != NULL, "method_with_idnum() should not be NULL");
1256 assert(old_method != new_method, "sanity check");
1257
1258 ime->initialize(new_method);
1259
1260 if (RC_TRACE_IN_RANGE(0x00100000, 0x00400000)) {
1261 if (!(*trace_name_printed)) {
1262 // RC_TRACE_MESG macro has an embedded ResourceMark
1263 RC_TRACE_MESG(("adjust: name=%s",
1264 old_method->method_holder()->external_name()));
1265 *trace_name_printed = true;
1266 }
1267 // RC_TRACE macro has an embedded ResourceMark
1268 RC_TRACE(0x00200000, ("itable method update: %s(%s)",
1269 new_method->name()->as_C_string(),
1270 new_method->signature()->as_C_string()));
1271 }
1272 }
1273 }
1274
1275 // an itable should never contain old or obsolete methods
1276 bool klassItable::check_no_old_or_obsolete_entries() {
1277 itableMethodEntry* ime = method_entry(0);
1278 for (int i = 0; i < _size_method_table; i++) {
1279 Method* m = ime->method();
1280 if (m != NULL &&
1281 (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) {
1282 return false;
1283 }
1284 ime++;
1285 }
1286 return true;
1287 }
1288
1289 void klassItable::dump_itable() {
1290 itableMethodEntry* ime = method_entry(0);
1291 tty->print_cr("itable dump --");
1292 for (int i = 0; i < _size_method_table; i++) {
1293 Method* m = ime->method();
1294 if (m != NULL) {
1295 tty->print(" (%5d) ", i);
1296 m->access_flags().print_on(tty);
1297 if (m->is_default_method()) {
1298 tty->print("default ");
1299 }
1300 tty->print(" -- ");
1301 m->print_name(tty);
1302 tty->cr();
1303 }
1304 ime++;
1305 }
1306 }
1307 #endif // INCLUDE_JVMTI
1308
1309
1310 // Setup
1311 class InterfaceVisiterClosure : public StackObj {
1312 public:
1313 virtual void doit(Klass* intf, int method_count) = 0;
1314 };
1315
1316 // Visit all interfaces with at least one itable method
1317 void visit_all_interfaces(Array<Klass*>* transitive_intf, InterfaceVisiterClosure *blk) {
1318 // Handle array argument
1319 for(int i = 0; i < transitive_intf->length(); i++) {
1320 Klass* intf = transitive_intf->at(i);
1321 assert(intf->is_interface(), "sanity check");
1322
1323 // Find no. of itable methods
1324 int method_count = 0;
1325 // method_count = klassItable::method_count_for_interface(intf);
1326 Array<Method*>* methods = InstanceKlass::cast(intf)->methods();
1327 if (methods->length() > 0) {
1328 for (int i = methods->length(); --i >= 0; ) {
1329 if (interface_method_needs_itable_index(methods->at(i))) {
1330 method_count++;
1331 }
1332 }
1333 }
1334
1335 // Only count interfaces with at least one method
1336 if (method_count > 0) {
1337 blk->doit(intf, method_count);
1338 }
1339 }
1340 }
1341
1342 class CountInterfacesClosure : public InterfaceVisiterClosure {
1343 private:
1344 int _nof_methods;
1345 int _nof_interfaces;
1346 public:
1347 CountInterfacesClosure() { _nof_methods = 0; _nof_interfaces = 0; }
1348
1349 int nof_methods() const { return _nof_methods; }
1350 int nof_interfaces() const { return _nof_interfaces; }
1351
1352 void doit(Klass* intf, int method_count) { _nof_methods += method_count; _nof_interfaces++; }
1353 };
1354
1355 class SetupItableClosure : public InterfaceVisiterClosure {
1356 private:
1357 itableOffsetEntry* _offset_entry;
1358 itableMethodEntry* _method_entry;
1359 address _klass_begin;
1360 public:
1361 SetupItableClosure(address klass_begin, itableOffsetEntry* offset_entry, itableMethodEntry* method_entry) {
1362 _klass_begin = klass_begin;
1363 _offset_entry = offset_entry;
1364 _method_entry = method_entry;
1365 }
1366
1367 itableMethodEntry* method_entry() const { return _method_entry; }
1368
1369 void doit(Klass* intf, int method_count) {
1370 int offset = ((address)_method_entry) - _klass_begin;
1371 _offset_entry->initialize(intf, offset);
1372 _offset_entry++;
1373 _method_entry += method_count;
1374 }
1375 };
1376
1377 int klassItable::compute_itable_size(Array<Klass*>* transitive_interfaces) {
1378 // Count no of interfaces and total number of interface methods
1379 CountInterfacesClosure cic;
1380 visit_all_interfaces(transitive_interfaces, &cic);
1381
1382 // There's alway an extra itable entry so we can null-terminate it.
1383 int itable_size = calc_itable_size(cic.nof_interfaces() + 1, cic.nof_methods());
1384
1385 // Statistics
1386 update_stats(itable_size * HeapWordSize);
1387
1388 return itable_size;
1389 }
1390
1391
1392 // Fill out offset table and interface klasses into the itable space
1393 void klassItable::setup_itable_offset_table(instanceKlassHandle klass) {
1394 if (klass->itable_length() == 0) return;
1395 assert(!klass->is_interface(), "Should have zero length itable");
1396
1397 // Count no of interfaces and total number of interface methods
1398 CountInterfacesClosure cic;
1399 visit_all_interfaces(klass->transitive_interfaces(), &cic);
1400 int nof_methods = cic.nof_methods();
1401 int nof_interfaces = cic.nof_interfaces();
1402
1403 // Add one extra entry so we can null-terminate the table
1404 nof_interfaces++;
1405
1406 assert(compute_itable_size(klass->transitive_interfaces()) ==
1407 calc_itable_size(nof_interfaces, nof_methods),
1408 "mismatch calculation of itable size");
1409
1410 // Fill-out offset table
1411 itableOffsetEntry* ioe = (itableOffsetEntry*)klass->start_of_itable();
1412 itableMethodEntry* ime = (itableMethodEntry*)(ioe + nof_interfaces);
1413 intptr_t* end = klass->end_of_itable();
1414 assert((oop*)(ime + nof_methods) <= (oop*)klass->start_of_nonstatic_oop_maps(), "wrong offset calculation (1)");
1415 assert((oop*)(end) == (oop*)(ime + nof_methods), "wrong offset calculation (2)");
1416
1417 // Visit all interfaces and initialize itable offset table
1418 SetupItableClosure sic((address)klass(), ioe, ime);
1419 visit_all_interfaces(klass->transitive_interfaces(), &sic);
1420
1421 #ifdef ASSERT
1422 ime = sic.method_entry();
1423 oop* v = (oop*) klass->end_of_itable();
1424 assert( (oop*)(ime) == v, "wrong offset calculation (2)");
1425 #endif
1426 }
1427
1428
1429 // inverse to itable_index
1430 Method* klassItable::method_for_itable_index(Klass* intf, int itable_index) {
1431 assert(InstanceKlass::cast(intf)->is_interface(), "sanity check");
1432 assert(intf->verify_itable_index(itable_index), "");
1433 Array<Method*>* methods = InstanceKlass::cast(intf)->methods();
1434
1435 if (itable_index < 0 || itable_index >= method_count_for_interface(intf))
1436 return NULL; // help caller defend against bad indices
1437
1438 int index = itable_index;
1439 Method* m = methods->at(index);
1440 int index2 = -1;
1441 while (!m->has_itable_index() ||
1442 (index2 = m->itable_index()) != itable_index) {
1443 assert(index2 < itable_index, "monotonic");
1444 if (++index == methods->length())
1445 return NULL;
1446 m = methods->at(index);
1447 }
1448 assert(m->itable_index() == itable_index, "correct inverse");
1449
1450 return m;
1451 }
1452
1453 void klassVtable::verify(outputStream* st, bool forced) {
1454 // make sure table is initialized
1455 if (!Universe::is_fully_initialized()) return;
1456 #ifndef PRODUCT
1457 // avoid redundant verifies
1458 if (!forced && _verify_count == Universe::verify_count()) return;
1459 _verify_count = Universe::verify_count();
1460 #endif
1461 oop* end_of_obj = (oop*)_klass() + _klass()->size();
1462 oop* end_of_vtable = (oop *)&table()[_length];
1463 if (end_of_vtable > end_of_obj) {
1464 fatal(err_msg("klass %s: klass object too short (vtable extends beyond "
1465 "end)", _klass->internal_name()));
1466 }
1467
1468 for (int i = 0; i < _length; i++) table()[i].verify(this, st);
1469 // verify consistency with superKlass vtable
1470 Klass* super = _klass->super();
1471 if (super != NULL) {
1472 InstanceKlass* sk = InstanceKlass::cast(super);
1473 klassVtable* vt = sk->vtable();
1474 for (int i = 0; i < vt->length(); i++) {
1475 verify_against(st, vt, i);
1476 }
1477 }
1478 }
1479
1480 void klassVtable::verify_against(outputStream* st, klassVtable* vt, int index) {
1481 vtableEntry* vte = &vt->table()[index];
1482 if (vte->method()->name() != table()[index].method()->name() ||
1483 vte->method()->signature() != table()[index].method()->signature()) {
1484 fatal("mismatched name/signature of vtable entries");
1485 }
1486 }
1487
1488 #ifndef PRODUCT
1489 void klassVtable::print() {
1490 ResourceMark rm;
1491 tty->print("klassVtable for klass %s (length %d):\n", _klass->internal_name(), length());
1492 for (int i = 0; i < length(); i++) {
1493 table()[i].print();
1494 tty->cr();
1495 }
1496 }
1497 #endif
1498
1499 void vtableEntry::verify(klassVtable* vt, outputStream* st) {
1500 NOT_PRODUCT(FlagSetting fs(IgnoreLockingAssertions, true));
1501 assert(method() != NULL, "must have set method");
1502 method()->verify();
1503 // we sub_type, because it could be a miranda method
1504 if (!vt->klass()->is_subtype_of(method()->method_holder())) {
1505 #ifndef PRODUCT
1506 print();
1507 #endif
1508 fatal(err_msg("vtableEntry " PTR_FORMAT ": method is from subclass", this));
1509 }
1510 }
1511
1512 #ifndef PRODUCT
1513
1514 void vtableEntry::print() {
1515 ResourceMark rm;
1516 tty->print("vtableEntry %s: ", method()->name()->as_C_string());
1517 if (Verbose) {
1518 tty->print("m %#lx ", (address)method());
1519 }
1520 }
1521
1522 class VtableStats : AllStatic {
1523 public:
1524 static int no_klasses; // # classes with vtables
1525 static int no_array_klasses; // # array classes
1526 static int no_instance_klasses; // # instanceKlasses
1527 static int sum_of_vtable_len; // total # of vtable entries
1528 static int sum_of_array_vtable_len; // total # of vtable entries in array klasses only
1529 static int fixed; // total fixed overhead in bytes
1530 static int filler; // overhead caused by filler bytes
1531 static int entries; // total bytes consumed by vtable entries
1532 static int array_entries; // total bytes consumed by array vtable entries
1533
1534 static void do_class(Klass* k) {
1535 Klass* kl = k;
1536 klassVtable* vt = kl->vtable();
1537 if (vt == NULL) return;
1538 no_klasses++;
1539 if (kl->oop_is_instance()) {
1540 no_instance_klasses++;
1541 kl->array_klasses_do(do_class);
1542 }
1543 if (kl->oop_is_array()) {
1544 no_array_klasses++;
1545 sum_of_array_vtable_len += vt->length();
1546 }
1547 sum_of_vtable_len += vt->length();
1548 }
1549
1550 static void compute() {
1551 SystemDictionary::classes_do(do_class);
1552 fixed = no_klasses * oopSize; // vtable length
1553 // filler size is a conservative approximation
1554 filler = oopSize * (no_klasses - no_instance_klasses) * (sizeof(InstanceKlass) - sizeof(ArrayKlass) - 1);
1555 entries = sizeof(vtableEntry) * sum_of_vtable_len;
1556 array_entries = sizeof(vtableEntry) * sum_of_array_vtable_len;
1557 }
1558 };
1559
1560 int VtableStats::no_klasses = 0;
1561 int VtableStats::no_array_klasses = 0;
1562 int VtableStats::no_instance_klasses = 0;
1563 int VtableStats::sum_of_vtable_len = 0;
1564 int VtableStats::sum_of_array_vtable_len = 0;
1565 int VtableStats::fixed = 0;
1566 int VtableStats::filler = 0;
1567 int VtableStats::entries = 0;
1568 int VtableStats::array_entries = 0;
1569
1570 void klassVtable::print_statistics() {
1571 ResourceMark rm;
1572 HandleMark hm;
1573 VtableStats::compute();
1574 tty->print_cr("vtable statistics:");
1575 tty->print_cr("%6d classes (%d instance, %d array)", VtableStats::no_klasses, VtableStats::no_instance_klasses, VtableStats::no_array_klasses);
1576 int total = VtableStats::fixed + VtableStats::filler + VtableStats::entries;
1577 tty->print_cr("%6d bytes fixed overhead (refs + vtable object header)", VtableStats::fixed);
1578 tty->print_cr("%6d bytes filler overhead", VtableStats::filler);
1579 tty->print_cr("%6d bytes for vtable entries (%d for arrays)", VtableStats::entries, VtableStats::array_entries);
1580 tty->print_cr("%6d bytes total", total);
1581 }
1582
1583 int klassItable::_total_classes; // Total no. of classes with itables
1584 long klassItable::_total_size; // Total no. of bytes used for itables
1585
1586 void klassItable::print_statistics() {
1587 tty->print_cr("itable statistics:");
1588 tty->print_cr("%6d classes with itables", _total_classes);
1589 tty->print_cr("%6d K uses for itables (average by class: %d bytes)", _total_size / K, _total_size / _total_classes);
1590 }
1591
1592 #endif // PRODUCT